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356 Cards in this Set
- Front
- Back
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Teeth must harmonize with what 3 frames |
Face, Lips and Gingiva |
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What 3 reference lines are used to obtain harmony |
Horizontal, Vertical, Sagittal |
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What are the 3 horizontal reference lines |
1. Interpupillary line 2. Lip line 3. Gingival plane |
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What do you evaluate with the Interpupillary line? |
Orientation of Incisal plane, Gingival margins, Maxilla |
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What qualities make a smile older |
1. Reduced incisal embrasures 2. Leveling of gull wing effect 3. Straight smile line; concave is VERY displeasing |
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How do you evaluate the gingival plane |
In relation to Interpupillary line and upper lip line (moderate vs gummy smile) |
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Describe a moderate smile |
Upper lip covers cervical of max incisors (3mm or less of gums exposed) |
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Describe a gummy smile |
More than 3mm of gum exposed |
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What do you do for gingival asymmetry |
If lip line is low you usually don't need to correct; if lip line is moderate or high you may need surgery or ortho |
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What do you evaluate with facial midline |
Location and axis of dental midline & mediolateral discrepancies in tooth position (want max central midline to be at midline of face) |
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What's more important: the mediolateral position of the max centrals relative to the facial midline OR the vertical orientation of the max centrals |
Vertical orientation of max centrals (don't want any slant/canting |
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What do you evaluate with the lip line in general |
Length and curvature of lips influences amt of tooth exposure at rest and in function |
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What do you evaluate with the upper lip line |
Length of max incisor exposed at rest and during smiling & vertical position of gingival margins during smile |
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What do you evaluate with the lower lip line |
Buccolingual position of the incisal edge of max incisors & curvature of incisal plane (convex and gull wing smile lines both esthetic) |
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What gender displays more tooth structure at rest |
Females (3.4mm) (males expose 1.91mm) average maxillary incisor display with lips at rest |
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Is it youthful or old to display more tooth structure |
Youthful (also more feminine) |
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Describe convex smile line/incisal plane |
Incisal edges of canines and central incisors aligned |
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Describe gull wing smile line |
Incisal edges of canines and central incisors aligned but longer than lateral incisors |
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Which is more esthetic: convex or gull wing smile line |
Trick question, they're both esthetic, depends on personal preference; but do set denture teeth with gull wing (Abt prefers convex) |
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What qualities make a smile youthful |
1. Prominent and well-developed central incisors 2. Well-defined incisal embrasures 3. Convex or gull wing smile line |
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What is the only vertical reference line |
Facial Midline |
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What are the four factors of esthetic composition |
1. Frame and Reference 2. Proportion and Idealism 3. Symmetry 4. Perspective and Illusion |
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What line should/does the incisal plane follow during smiling |
Lower lip line |
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How can you correct a gummy smile? |
If the centrals are short with a gummy smile --> lengthen centrals and move gingiva apically (if centrals are ideal size then you can't elongate them) |
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What does the sagittal plane evaluate |
Profile view/Sagittal Reference 1. Upper lip support 2. Lower lip relation 3. Occlusal plane - e.g. lips retruded, protruded, overclosed? & Phonetic Reference |
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What contributes to upper lip support |
Somewhat controlled by position of max teeth; Gingival 2/3 of teeth contribute to main support of lip |
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What does the lower lip relation explain |
Relationship of max incisal edges to lower lip used as a guide for general assessment of incisal edge position and length |
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What are the "F" and "V" positions |
Positions at which incisal edges of max anterior teeth permit most fluent pronunciation of "F" and "V"
Incisal edges should make definite contact at inner vermillion border of lower lip
Determine facial position of incisal third of max central incisors; must conform to path of closure of lower lip |
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What is the occlusal plane |
Established by incisal and occlusal surfaces of teeth and should coincide with Camper's plane; should slant upwards as you go posteriorly |
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When won't the incisal plane correspond to posterior plane of occlusion |
Supraeruption/elongation of max anterior teeth |
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What is Camper's Plane |
Extends from inferior border of ala of nose to superior border of tragus of ear |
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What are the 4 sounds used to aid in esthetic diagnosis |
1. "M" sound 2/3. "F" and "V" sounds 4. "S" sound
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"M" Sound |
used to achieve relaxed, rest position determine how much tooth structure showing |
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"F" and "V" sounds |
determine lingual tilt of incisal third of max centrals and whether abnormally elongated (determine length and B-L position of max centrals) |
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"S" sound |
determines vertical dimension of speech/closest speaking space - anterior speaking space - max and mand incisal edges in near contact - posterior speaking space - varies w/ amt of mand protrusion necessary to bring anterior teeth in near contact |
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What does it mean when teeth are clicking together when speaking |
VDO has been opened too much; impinging on freeway space |
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What does it mean if there's too much space when using "S" Sounds |
VDO is too closed |
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What is equated with the "harmony of proportions" |
Beauty |
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What is idealism |
Study and replicate ideal tooth forms before creating variation and characterization |
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What do proportion and idealism determine in esthetic dentistry |
1. optimum size of max centrals 2. optimum relationship b/w the dimensions of the max central incisor, lat incisor and canine |
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What is the pleasing width:length ratio for max centrals |
Between 75-80% (<65% too narrow, >85% too short and square)
*About size of piece of paper (8.5x11) |
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What is the Golden Proportion |
smile most esthetic when each tooth in smile is about 60% of size of tooth mesial to it (exact number is 0.618)
*not necessarily accurate; use as a loose guide |
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What constitute symmetry and diversity |
Regularity and Balance of tooth arrangement Harmonious facial features (more symmetry closer to midline needed for esthetics) |
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Is natural dentition usually symmetrical or asymmetrical |
Almost ALWAYS asymmetrical |
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What constitute perspective and illusion |
Alter perception of shape of an individual tooth and change one esthetic element to effect another |
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Perception involves |
Widening and narrowing Shortening and lengthening |
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Illusion involves |
Create illusion of larger/narrower teeth in the exact same space - vary outline or silhouette form --> effect light reflection |
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Is symmetry more critical close to or far from the midline |
Close to midline |
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How do you give illusion of a widened tooth |
- Displace line angles laterally - Flatten facial outline - Highlight texture and gloss with horizontal lines and ridges - Decrease facial embrasures - Displace proximal contacts labially |
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How do you give illusion of a narrowed tooth |
- Displace line angles medially - Increase convexity of facial outline - Highlight texture and gloss with vertical lines and ridges - Increase facial embrasures - Displace proximal contacts lingually - Shadow proximal aspects with extrinsic staining |
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Applications for widening a tooth |
- Increase narrow pontic space - Improve tooth proportions - Correct elongated clinical crowns after perio or implant surgery (gingiva have been moved apically to lengthen tooth after bone loss or caries --> appears too long and narrow) |
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Applications for narrowing a tooth |
- Close diastema (ortho is first choice for tx if teeth are ideal size; need teeth to look less wide) - Reduce large pontic space - Control tooth proportions |
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How do you give illusion of a shortened tooth |
- Emphasize prominence of cervical convexity - Displace cervical convexity - Accentuate downward tilt of incisal third - Highlight texture and gloss with horizontal lines and ridges - Emphasize CEJ |
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How do you give illusion of a lengthened tooth |
- Flatten the cervical convexity - Displace the cervical convexity apically - Lighten the cervical aspect - Highlight texture and gloss of line angles and create vertical ridges |
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Applications for shortening a tooth |
- Asymmetry of the max centrals - Long pontics - Control proportions - Correct elongated clinical crowns after perio or implant surgery |
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Applications for lengthening a tooth |
- Asymmetry of the max centrals - Correct short max central that can't be lengthened surgically |
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What is the root effect in esthetic dentistry |
Occurs when the gingival margin is displaced apically and clinical crown made longer (usually b/c of caries) --> acct for this by displacing the CEJ and showing the root |
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What is the shading perspective in natural dentition |
Four max incisors have same shade; canines appear darker |
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What do we want the shading perspective to be prosthetically |
Smooth transition w/ progressive shade saturation from central incisor to canine (emphasizes dominance of max centrals) |
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What is the Munsell Color Order System |
Color system w/ 3 dimensional phenomenon (Hue, Chroma, Value) |
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Hue |
distinguishes one color from another (green vs blue); short wavelength = violet, long wavelength = red |
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Chroma |
Intensity/saturation of hue; strong vs weak (light yellow vs dark yellow) |
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Value |
Relative lightness or darkness; high values appear too bright/white in dentistry |
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What two phases does Color Replication Process consist of |
Shade-matching and Shade-duplication |
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What is surface characteriziation |
Lines, characteristics, discrepancies etc that different teeth have, must be incorporated into restoration |
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What does the shade-matching phase involve |
Visual shade selection OR Instrument analysis |
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What does the shade-duplication phase involve |
Corresponding porcelain OR porcelain mixing and then Surface characterization to make the porcelain crown |
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What are the guidelines for shade-matching |
Balanced lighting (daylight) Remove lipstick/bright clothing Clean teeth Beginning of visit (not too dry) View pt at eye level Wet tooth and shade guide if they have different surface characteristics Make choice quickly, <5 secs (eye fatigue) Use canine to choose hue (highest chroma) Always select shade after bleaching Always pick LOWER CHROMA, HIGHEST VALUE Map polychromatic nature of tooth - include all special characteristics and multiple shades (include chart or image) |
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What shade guide should you use at Penn? |
Vita-3D (based more on value not hue) |
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When deciding between a couple different shades, which one should you pick |
Lower Chroma and Highest Value; you can intrinsically stain to make tooth darker/more intense, but can't make the tooth lighter |
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When sending info to the lab about tooth shade and characterization, what is the minimum amt of info that you should include |
Divide tooth into thirds (cervical, middle, incisal) and have different gradations for each area (i.e. cervical areas usually darker than incisal) |
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What is the most perfect instrument color analysis tool available |
None have been perfected; should use instruments along with shade guides |
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What does the shoulder provide to a crown prep |
Marginal integrity and Structural durability |
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What does the vertical lingual wall of the anterior crown prep provide |
Retention and resistance |
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What does the concave cingulum reduction of an anterior crown prep provide |
Structural durability |
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What does the axial reduction of a crown prep provide |
Retention and resistance; Structural durability |
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What do rounded angles of a crown prep provide |
Structural durability (don't want material to fracture at sharp angles, esp ceramic) |
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Is the cingulum reduction of a max central flat or concave |
Concave |
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Is the cingulum reduction of a canine flat or concave |
Flat (slightly convex in areas) |
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Which requires more reduction: ceramic prep or PFM prep |
PFM prep requires more reduction b/c it involves more material |
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What type of material is integrity |
Self-cure, composite resin |
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What are the two categories of alloys used to fuse to porcelain |
Noble Metals and Base Metals |
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What are the types of Noble Metals used for PFM |
Gold-based and Palladium-based |
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What are types of Base Metals used for PFM |
Titanium, Nickel, Cobalt
Ni-Cr-Be Ni-Cr Co-Cr Ti & Ti alloys |
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What are the steps of the Lost Wax Casting |
1. Wax pattern approved 2. Spruing 3. Investing 4. Burnout 5. Casting 6. Breakout casting from investment 7. Pickle Casting 8. Remove Sprue and Polish 9. Deliver to Patient |
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What is Spruing (in Lost Wax Casting) |
Apply Sprue Pin and Attach to Sprue Base Purpose is to provide a channel in the set investment for wax removal and for molten metal to fill the mold space |
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What is Investing (in Lost Wax Casting) |
Put sprue base/sprue/wax pattern in copper ring --> mix and pour investment material into copper ring (surrounding the wax pattern and sprue) |
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What is Burnout (in Lost Wax Casting) |
Remove sprue base (usually made of plastic) from top of casting ring --> set at high temps in oven (temp determined by type of investment) --> wax pattern burned out of investment leaving an empty mold space |
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What is Casting (in Lost Wax Casting) |
Melt alloy then push it through to fill the mold space in the casting ring --> forms the metal crown |
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What is Pickling (in Lost Wax Casting) |
Immerse removed casting in hot acid solution (removes oxides from surface) --> get nicer casting
Used for Gold Only |
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What is the Casting Formula |
Wax shrinkage + Solidification shrinkage = Die stone expansion + wax expansion + investment setting expansion + hygroscopic expansion + thermal expansion of investment (balance only occurs when you immerse casting in water - hygroscopic expansion) |
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Which undergoes more casting/solidification shrinkage: Gold/Noble metals or Base metals |
Base metals: 2-2.5% shrinkage; cast at much higher temp and higher melting temp --> shrink more
Noble metals = 1.4-1.6% shrinkage
(Wax pattern shrinkage = ~.3-.8%) |
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Which undergoes more expansion: Type IV or Type V master die stone gypsum |
Type V: has .3% expansion
(Type IV has .1% expansion; also very minimal wax pattern expansion
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What is the purpose of hygroscopic expansion |
Immersing the casting ring in water while it's setting helps compensate for alloy shrinkage (as opposed to normal bench top setting)
Normal setting expansion = .4% Hygroscopic expansion = 1.2-2.2% |
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Which undergoes more shrinkage in the casting process: metal alloys while setting or wax patterns |
Metal alloys (Base metals more than noble) = 2.0-2.5%; 1.4-1.6%
(wax pattern shrinkage = .3-.8%) |
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How does the temperature used in heating investments effect shrinkage/expansion |
High heat causes greater thermal expansion of investment material than low heat (1-1.6% vs 0-0.6%)
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What is the purpose of a die spacer |
Paint/varnish placed on die before making the wax pattern --> provides room for cement later (has NOTHING to do with expansion) |
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How do you determine what type of investment material to use |
The combined setting and thermal expansions of the wax, metal, and gypsum used determine manufacturer recommendation for investment material for ideal casting (must use appropriate investment material) |
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What is the purpose of a liner in the casting ring |
Provides a cushion that allows investment to expand during heating; doesn't reach the top so investment has room to lock into casting ring |
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What is the direct vs indirect spruing technique |
Direct: go directly from sprue base to the wax pattern Indirect: metal flows into a bar and then into the mold space |
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What are the requirements of a sprue |
Thickness - should be thick as thickest portion of wax pattern Provide reservoir - area where metal remains molten for longest period of time during casting, allows molten to fill space completely (in indirect technique the runner bar is the reservoir); simple sprue pins in direct technique need an add'l bulb as the reservoir Direction - need a direct path for the molten metal (prevent bubbles/disturbance), shouldn't be too long b/c molten metal could freeze |
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What materials are typically used for sprues |
Wax or plastic (plastic must be removed from mold space before it melts) |
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What is a direct sprue |
Has single, and small multi-unit attachments; Two types: constricted and flared
the metal will solidify quickly and you'll get a suck back porosity |
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What is the difference between a constricted direct sprue and a flared direct sprue |
Constricted are for low density alloys; Flared are for high density alloys |
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What is an indirect sprue |
For low density/high melting PFM alloys (base metal and some palladium); exposed button will solidify rapidly; runner bar serves as reservoir; stabilizes wax patterns against distortion; equalizes flow of metal to all parts of casting |
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How should the runner bar be placed for an indirect sprue |
In a vertical position in center of gravity so that the metal stays molten and you get a better casting |
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What is the center of mass/heat center of the casting unit in indirect technique |
Runner bar - the flow of molten metal in the bar raises the temp of the surrounding investment; the heat around the bar also keeps the metal molten longer
(use orientation dots to position the bar vertically in the casting machine --> ensures simultaneous mold filling in all areas) |
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What is Venting in the Casting process and what are the indications for its use |
Allows rapid escape of gases from the mold cavity when molten metal rushing in; if gas gets trapped --> prevents complete filling of mold space
Indicated for: large castings, High Pd and Base-metal alloys, dense investments (e.g. silicon, porcelain-bonded)
(not always necessary; ex: porous investments like gypsum) |
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What is the purpose of a Liner in the Casting process |
Provides room for investment expansion |
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What types of materials are used as Liners in Casting process |
Asbestos - first used Organic Cellulose material (fluffy paper) Silica alumina fiber Ceramic/cellulose combo - currently used |
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Why do you want to keep ring liners short in casting rings |
3.0mm short of ring
Saves space to secure the investment in the ring so it doesn't fly out during casting; also produces a more uniform expansion |
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What is Ringless Casting |
Popular w/ high-temp alloys and other materials that require a lot of expansion Make casting ring out of wax instead of metal Once the investment has set --> remove the wax and you only have investment material (has unlimited expansion) |
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What is debubblizer and why is it used in the investing process |
A surface tension reducing agent applied to the wax pattern in a thin coat to prevent formation of bubbles |
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What type of investments are and aren't used for PFM |
Gypsum-bonded investments can be used up to 700 oC - so not used for casting PFM
Use Phosphate and Silicate bonded investment for PFM |
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How should investment be stored during setting after its poured |
In a humidor with 100% relative humidity so it doesn't dry out and crack during the burnout process |
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How long is the burnout process |
Long enough to ensure complete elimination of all wax; 30-60 min depending on type of investment material used
Avoid excessive heat soaking and excessive length of time --> sintering of investment --> rough casting surface |
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What is a crucible in the casting process |
Container used to heat alloy; color-coded for different alloys |
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What is the ideal casting temperature for alloys |
100-200 degrees higher than the melting temp of the alloy |
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Can you reuse alloys that have been previously cast |
You can reuse Gold but you can NOT reuse Base metal alloys
(can reuse each button ONCE - otherwise you won't maintain props of alloy) |
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What are the heat sources used for melting alloys |
Torch Melting Electrical Heating Arc Melting |
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What zone of melting is best/ideal for melting alloy when using Torch Melting |
Reducing zone |
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What types of gas do you use to melt the different types of metal alloys |
Type I - Type IV Gold: use natural gas Other alloys: use propane-oxygen mixtures (liable to overheating) |
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What is centrifugal casting |
Centrifugal force proportional to: - radius of casting arm - mass of metal - extra turns for low density alloys b/c you need more force
(Gold = 3 turns; Base metal = 4 turns) |
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What is flux in the casting process |
Powder material used to prevent oxidation of metal; typically used only for Gold; spread on the molten alloy |
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What is the safest type of casting |
Vacuum/pressure casting; you melt the alloy to a prescribed temp |
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When is the pickling technique used |
For Gold ONLY to remove oxides formed on casting |
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What technique is used to clean PFM alloy castings |
Sandblast (pickling used for Gold) |
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What are common types of casting defects |
Distortion of wax pattern Fins - cracked investment, metal flows in Surface roughness Bubbles - excess debubblizer, air Nodule Excessive heat |
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What causes casting defects |
Underheating - incomplete casting, carbon coating Prolonged heating - disintegration of investment Foreign bodies Porosity Inadequate reservoir - incomplete casting Adequate reservoir - no button cast Poor alloy castability - doesn't flow enough, blunt margins |
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What investment materials are used for the different types of metal |
Type I to Type IV gold: use Gypsum (can't use for PFM b/c it cant be heated above a certain temp) Phosphate-bonded: carbon containing (easy to divest, but makes alloy brittle) and non-carbon containing Silicate-bonded
Must be able to heat the metal/investment a little above melting temp in order to get a good investment |
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What are the major components in all investments |
Binder, Refractory, Setting Agent |
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What impacts setting expansion |
Silica sol:water ratio (more silica = more expansion; more water = less expansion)
usual ratio is 3:1 |
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What is the difference in expansion b/w Crystabolite and Quartz in phosphate-bonded investment |
Crystabolite = low temp expansion Quartz = high temp expansion
both are forms of silica diozide |
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What do setting, hygroscopic and thermal expansion offset in phosphate-bonded investment |
Freezing shrinkage of the metal and shrinkage of the wax patterm |
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What can you do to reduce bubble formation in phosphate-bonded investment |
Use debubblizer (prevent poor surface wettability)--> coat surface of wax pattern with investment before pouring investment into ring Use vacuum or open investing Allow investment to set in pressure pot |
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What are the binder, refractory and setting agent used in phosphate-bonded investment |
Binder - Mono Ammonium Phosphate, Magnesium Oxide Refractory - Quartz + Cristabolite (low temp expansion), Quartz (high temp burnout/expansion) Setting Agent/Reaction (colloidal silica) - Binder + Setting agent --> Green Strength (early reaction) |
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What are the types of Phosphate-bonded Investment |
Ag-Pd Au-Pd Ni-Cr |
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What is the refractory used in silica-bonded investment |
Quartz only - b/c using it at a much higher temp |
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What are the binder, refractory and setting agent in a silicate-bonded investment |
Binder: Ethylorthosilicate Refractory: Quartz only Setting agent: Magnesium oxide - promotes gelation setting reaction |
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What type of expansion does Silicate-bonded investment undego |
Thermal expansion only (alpha quartz to beta quartz) |
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What metal causes discoloration/green of margins on a porcelain crown? |
Silver (Ag) |
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What are the three adherence controlling elements used and what do they do? |
Fe, Sn, In (Iron, Tin and Indium) included in trace amounts in the metal layer to provide an oxide layer for porcelain to bond to
Only required for noble metal alloys b/c base metal alloys provide their own oxides |
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Is low or high sag resistance good for long span bridges? |
High sag resistance - prevents the material from buckling when heated |
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What role does Beryllium play in the casting process and final outcome of the PFM alloy |
PFM alloys that include beryllium bond to porcelain well, are easily cast, have easier flow and are easier to mask b/c the oxide layer is thin |
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What is an Optical Scanner LED and what are the two examples of them? |
LED = Light-emitting diode
Scanner depends on a reflective surface and requires a contrasting medium/powder
Examples: Lava and CEREC |
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What is a Laser Scanner and what are the two examples of them? |
Scans and measures distances from the tooth surface to acquire the image; no powder required
Examples: Cadent iTero and E4D |
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What is the Cadent iTero Scanner |
Laser scanner - powder not required Take digital impressions and send to lab to produce restoration Vertically taller than CEREC and E4D
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What is the 3M ESPE Lava COS scanner |
LED scanner - powder required Take digital impressions and send to lab to produce restoration |
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What is the CEREC by Sirona scanner |
LED Scanner - powder required Has a milling machine - on site impressions |
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What is the E4D by D4D scanner |
Laser scanner - no powder required Has a milling machine - on site impressions (can also send to a lab) vertically shorter than CEREC |
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When is it better to take digital impressions as opposed to regular impressions |
If they have a strong gag reflex If they have severely compromised teeth that could be lost or moved in a regular impression |
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What type of powder is used for LED digital scanners and how does it work |
Titanium Dioxide powder serves as a reflecting agent for scanning with LED; use a light coating (remove excess with air) and only recoat in between scans |
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What is the order of vertical height for the scanners |
Cadent iTero > CEREC > E4D |
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What type of retraction device is used in clinic to take a digital impression |
Ultragate retraction |
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Is isolation/tissue retraction necessary to take digital impressions |
Yes. Must retract teeth and lips, use suction and dry angles to keep VERY dry |
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What is the order of scanning fora digital impression |
First - opposing arch Second - preparation and contacts Third - operative arch Fourth - bite registration |
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What is the proper patient position for taking a digital impression |
Patient should be upright Occlusal plane should be parallel to the floor |
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How should your arms and hands be positioned when taking a digital impression |
Use handshake grip Forearm and the wand should be parallel to the arch Dominant hand should guide the wand rotation Non-dominant hand stabilizes the camera tip
(similar to playing pool) |
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How close to the tooth surface should you be when taking a digital impression and how should the image capturing appear on screen |
Should be 1mm from tooth surface If too far --> yellow dot becomes small If too close --> yellow do becomes large (Yellow dot should fill the dotted circle) |
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On what surface of the tooth should the digital impression begin |
Occlusal surface (then move toward buccal, then back to occlusal, then move toward lingual) |
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Should you be looking at the monitor or the patient when taking a digital impression |
Look at the monitor |
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How long do you have to complete the scan of one arch |
7 minutes (you can then save, inspect and re-scan if needed --> merge the images) |
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What are the digital impressions currently used for at Penn |
All-ceramic restorations |
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What type of finish line/prep design can NOT be scanned with the LAVA digital impression scanner |
Can NOT scan a bevel; must be a modified shoulder finish line |
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What are the requirements for an acceptable scan when taking a digital impression (what percentages of the different tooth surfaces must be captured) |
100% of preps and contacts, occlusal surfaces and working cusps 90% of buccal surfaces 60% of lingual surfaces |
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How many teeth should be captured in the bite registration for a digital impression and what does the bite registration relate |
Scan 3-5 teeth Relates upper and lower arches in space |
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How long do you have to scan a bite registration for a digital impression |
2 minutes |
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What preparation design is recommended for use with the LAVA scanner digital impression and what is not recommended |
Chamfer shoulder recommended Feathered/beveled margins NOT recommended |
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Do crowns from digital scans have better marginal fit than crowns from silicone impressions; what about interproximal contact and occlusion |
Yes - revealed significantly better; but marginal fit for both are clinically acceptable
(Crowns from digital scans have better interproximal contact; Equal in regard to occlusion) |
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What is the most destructive restoration for a tooth |
Full-coverage crown; cause a lot of trauma and destruction, avoid if possible to do a less invasive procedure (inlay, onlay, composite, etc) |
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From what tooth layer does the shade of the tooth primarily come |
Dentinal layer (enamel layer is VERY translucent, almost clear) |
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What are the two major advantages of ceramics for restorations |
Durable and Biocompatible (inert against chemical/biologic influences from oral cavity) |
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What broader category does porcelain fall into |
Ceramic; porcelain is a type of ceramic |
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What are the two major categories of Ceramic Materials |
Silica-based (glass-based/feldspathic) - more traditional High Strength (oxide-based) - contains metal oxides to strengthen material |
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What are examples of silica-based ceramic materials |
Traditional Feldspathic ceramic Reinforced Feldspathic ceramic Polycrystalline glass ceramic |
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How does polycrystalline glass ceramic differ from the feldspathic ceramics |
Has an amorphous glass phase (not pure glass) and controlled crystallization during firing (increased strength from crystals during cooling) |
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What does the firing process do to ceramic |
Makes it strong, hard and inert |
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What happens to silica during the firing process of a ceramic |
Unchanged during firing; provides stability |
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Is it best to build ceramic as one mass or in increments and why |
In increments/layers to best mimic natural tooth structure and becomes materials shrink a lot during firing (15-20%) |
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Describe the sintering process in Silica ceramic making |
Glass that's been crushed and purified is fused together |
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Describe the fritting process in Silica ceramic making |
Freezing fused glass in an amorphous state by putting it in water |
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Why do you ground fritted glass before making ceramic structure |
ground into smaller particles so you can add pigments and metal oxides to get different shades and opacities |
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How should the Silica ceramic structure be built up (what are the steps/layers involved) |
Build up layers to block metal substructure Achieve dentin shading Cover with more translucent enamel layer |
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What is the texture of the ceramic while building it up before firing |
Slushy/slurry because you mix powder with special liquid or water; use a brush to apply a layer of slush |
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Explain the firing and cooling processes for ceramics (what temperature, what steps) |
Veneering porcelains fired at different temps Want controlled conditions - so use vacuum in oven/furnace During cooling, crystallization occurs - changes composition of ceramic somewhat
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What is the name of the first bake/layer of the ceramic after firing and what does it do |
Opaque bake - creates an oxide layer that can bond well to the metal alloy or high-strength ceramic core |
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What is the purpose of the core/framework used with ceramic and what is it made of |
Either metal alloys or high strength ceramic
Used for strength; w/o the core chewing forces would destroy the restoration quickly |
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How do you decide what type of veneering ceramic to use |
Depends on core material and its: coefficient of thermal expansion, modulus of elasticity, fracture toughness, and framework design |
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What determines the baking/fusing temp of a veneering porcelain? |
Substrate and melting temp of the alloy |
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What is the importance of crystallization in the making of a ceramic veneer |
Makes restoration slightly stronger Gives different physical properties depending on number of crystals in the system
(crystallization occurs during cooling) |
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How many times can you fire porcelain and what happens if you fire more than this amount |
3-4 times max Crystallization will become uncontrolled and crystals will grow erratically --> have to start over |
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What happens when metal put under stress versus when ceramics put under stress |
Metal alloys have high MOE --> undergo elastic and then plastic deformations when put under stress before breaking
Ceramics are brittle and will fracture (no deformations/bending first) |
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What are the types of support used for ceramics (which are brittle) |
Core - made of metal or high-strength ceramic Resin bonding - adhesive dentistry; use composite resin to increase fracture strength |
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What determines the success of a restoration and prevents it from falling out |
Retentive prep - basically parallel walls OR adhesive bonding - use composite to bond restoration to tooth structure |
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What changes the flexure strength of a ceramic porcelain |
Increased by changing the crystal content of the material (increase crystals by changing composition of components --> changes the MOE --> increased flexure strength) |
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Is there a limit to the number of crystals you can add to increase strength |
Yes. Once crystals are very small and fill up space you can't add anymore |
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Name the two major types of Reinforced Feldspathic porcelains |
Leucite-reinforced (not commonly used) Lithium disilicate (more popular) |
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Name three High-strength Ceramics |
Glass-infiltrated alumina Densely sintered alumina Zirconia |
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What type of ceramic has the highest fracture strength/ what is the order of fracture strength for both silica-based and high strength ceramics |
Zirconia - also has highest opacity
zirconia>densely sintered alumina>glass-infiltrated alumina>lithium disilicate>leucite reinforced feldspathic>feldspathic |
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What type of ceramic is the most translucent (most esthetic) |
Feldspathic - also has lowest fracture strength
feldspathic>leucite-reinforced feldspathic>lithium disilicate>glass-infiltrated alumina>densely sintered alumina>zirconia |
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What is the main difference between glass-infiltrated alumina and Silica(glass)-based ceramics |
In glass-infiltrated alumina glass is used as a filler, so it's stronger than silica-based ceramic in which glass is the matrix |
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What procedure is used to make densely sintered alumina |
CAD/CAM Scan --> Design --> Milling of enlarged die --> Ceramic powder application --> Milling --> Sintering --> Finished coping - works against shrinkage b/c computer takes shrinkage into account with calculations
(very successful procedure) |
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What two ceramic types are milled out slightly larger than the restoration to account for shrinkage during firing |
Densely sintered alumina Zirconia |
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What shape is Zirconia |
Tetragonal |
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How does Zirconia prevent a crack from spreading through the entire ceramic system |
Transformation toughening: when a crack occurs, it's partially stabilized by zirconia changing from its 3D tetragonal shape to a monoclinic form; puts the crack under compression |
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Is there any significant difference between success of PFM posterior crowns and PFZ (porcelain fused to zirconia) crowns |
No, there's no significant difference |
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What role does fluorescence play |
Natural teeth have fluorescence, especially in gingival areas; caries look dark/brown when fluorescent light shined on it |
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What is the most popular full coverage restoration and why |
Full contour zirconia (more popular than PFM); can design everything on computer and color it; costs the same as PFM |
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What is the goal of laminate veneers |
Improve esthetics and simulate destructed enamel |
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When do we use laminate veneers |
Genetic malformation of tooth (peg laterals) Discoloration of teeth (tx to an extent, may need coping underneath for translucency) Trauma Improved esthetics Malpositioning of teeth (tx to an extent, but probably need ortho too) Closing diastema Erosion/abrasion/wear
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What materials are used for laminate veneers |
Mostly ceramic (usually Silica-based feldspathic, but needs support) Sometimes composite restoration |
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What do you need to understand in order to fabricate veneers successfully |
Tooth anatomy/morphology; appropriate anatomic guidelines of teeth |
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What factors are key to the success of laminate veneers |
Resin bonding (relies on bond strength) Minimally invasive - stay in enamel (best bond b/c you can etch it) Supragingival Follow tooth curvature (three labial planes) Chamfer in marginal areas (create space for ceramic) w/ distinct finish line
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What can you use to ensure that you don't cut into dentin when doing a veneer prep |
Black water-proof marker on enamel |
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What is an elbow preparation in a veneer prep |
Going slightly into interproximal area to avoid having natural tooth structure show when patient turns head |
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About how much of the enamel should remain after reducing |
At least 50% |
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What should you avoid when extending the veneer prep interproximally |
Opening contact areas with prep
(after prep, slice with finishing strip or disk to create some space for impression material/master cast cutting) |
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What is the alternative prep to the elbow prep |
There is no contact area --> open up interproximally and extend prep to palate |
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What is the biggest enemy to resin bonding in the mouth |
Moisture |
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What can you use to ensure that you have reduced the veneer prep enough |
Putty or thermoplastic device (omnivac) |
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When taking the final impression of the veneer prep, what technique do you use |
2 cord technique Thinner cord remains during impression, thicker cord removed before impression |
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What type of provisional and technique is ideal for the veneer prep and what are not ideal and why |
Non-ideal: - Bonding composite - have to cut it off and destroy prep - Conventional provisional - won't stay in place b/c no retention, would need cement
Ideal: - Direct provisional - use omnivac and spot bond technique |
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What are the steps of the spot bond technique for fabricating a provisional for a veneer prep |
Acid etch parts of the tooth, rinse, place bonding agent on some parts of tooth, cure, fill up omnivac halfway with composite, cure - close open margins with composite by hand - hard to bond composite to already cured composite especially at margins |
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What area of the veneer prep is most important when fabricating the provisional |
Marginal areas - want them smooth so you won't get gingival inflammation or recession/exposure; if veneer doesn't fit at margins --> start over |
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How do you prepare the ceramic veneer to be bonded to the enamel of the prepped tooth |
Etch with Hydrofluoric acid - remove glass matrix b/w crystals to get a rougher surface Remove residual acids and salts with ultrasonic cleaner (alcohol and acetone) Apply silane coupling agent - wets surface for mechanical and chemical bond (key to successful bond strength) |
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What is the purpose the silane coupling agent applied to the ceramic veneer before it's bonded to the tooth |
Adheres to silica crystals that are exposed from etching Key for successful bond strength - gives mechanical and chemical bond |
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What types of etch do you use when for a prepped veneer |
Self-etch: if there's more dentin, for small/entire cavity, selective enamel etch in large cavities; Etch and rinse: if there's more enamel, for larger restorationsW |
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What types of composite do you use and when for a veneer |
Light Cure, Dual Cure, Self Cure (self cure not used very often b/c of fixed working time; dual cure has longer working time but tends to discolor over time; light cure - use two different materials for optimal brightness) |
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What is the only way to achieve a properly designed framework |
By waxing the restoration to complete anatomic contour and then cutting back a consistent amount for the porcelain |
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What does waxing to complete anatomic contour allow for the framework design and restoration |
Even/ideal thickness of porcelain Proper porcelain-metal interfaces (not visible) Good connector design Optimally placed occlusal contacts |
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What is the minimum porcelain thickness needed for esthetic and the maximum thickness to avoid fracture |
1mm-2mm |
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What should the thickness of the ceramic be at the porcelain-metal interface |
At least 0.5mm |
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How far away from the porcelain-metal interface should the occlusion/centric stops be |
At least 1.5mm |
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What material should oppose a restoration at the contacting surfaces |
The same type of material (metal opposing metal, porcelain opposing porcelain)
ex: porcelain very abrasive, if opposing gold restoration could damage it |
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Which material is more difficult to have at the occlusal surface in a restoration: porcelain or metal |
Porcelain - more abrasive than enamel - lower strength than metal occlusal surfaces - harder to obtain correct occlusal form - must be polished/glazed to reduce issues |
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What should be done to avoid much damage/wear to opposing dentition with metal or porcelain restoration |
give an occlusal/night guard to protect the dentition from the restoration - especially for large restorations |
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How do connectors effect the success of a prosthesis |
Size, shape and position influence success - must be sufficiently large to prevent distortion and fracture; but not too large (for cleaning and esthetic purposes) - need correct shape for esthetics - usually 3-4mm vertical height |
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What is a pontic? |
Artificial tooth of a fixed dental prosthesis |
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What should you evaluate in the mouth in order to prepare the pontic design? |
Dimensions of edentulous areas, form and shape of gingival surface |
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What is an ideally shaped ridge for a pontic |
Smooth, regular surface of attached gingiva Height and width allow placement of pontic which appears to emerge from ridge Adequate facial height to sustain appearance of interdental papilla Want broad, not knife-edged |
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Is it worse to lose residual ridge height or width and what are the classes of defect |
Worst to lose height Class 0 - no defect Class 1 - lost width Class 2 - lost height Class 3 - lost width and height |
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For which class(es) of residual ridge defect should you consider surgery to augment the ridge |
Class II and Class III |
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How do you classify contact (according to contact with oral mucosa) |
No Mucosal Contact: Sanitary Mucosal Contact: Ridge lap Modified ridge lap Conical Ovate |
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What is a Sanitary pontic and when is it recommended |
No mucosal contact of the pontic w/ oral mucosa; sanitary b/c allows easy cleaning
Problems: may entrap food, least esthetic; limited to posterior mandible/for low lip line |
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What is a Saddle/Ridge Lap pontic and when is it recommended |
AVOID - concave surface can't be cleaned |
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What is a Modified Ridge Lap pontic and when is it recommended |
Combines best features of Sanitary and Modified Ridge Lap pontics - esthetic and easy to clean - overlaps ridge on facial and clears ridge on the lingual - should be convex - most common pontic for visible areas |
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What is a Conical pontic and when is it reocmmended |
For narrow ridges - touches at one point in the center; easy to clean; not very esthetic |
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What is the Ovate pontic and when is it recommended |
Most esthetic Appears to grow out of the gingiva Creates a convex tissue surface (depression or hollow in the ridge - need surgery to build up) Only done when required for perio b/c ridge augmented Has no unsupported porcelain |
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What is most essential for the success of a pontic |
Plaque control/ease of cleaning - choose design that allows for easy plaque control |
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Can you continue with casting/crown finishing if there's a defect in the crown margin |
No, you must remake the crown
(if there's a small nodule far away from the margin you can remove it with 1/4 round bur) |
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Should there be contact between the die and the internal surface of the casting/crown |
No, you need space for the luting agent; remove all contacts; use spray indicator (i.e. occlude) - should see even amount with no rubbing, relieve all pressure areas
(also remove all nodules - remove slightly more than nodule to ensure complete seating) |
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What happens if you remove too much from the intaglio surface of your casting/crown |
Loss retention/resistance |
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Name the steps of the finishing process of a casting/crown |
1. Check Internal margins 2. Check Intaglio surface - remove defects and relieve pressure areas 3. Remove Sprue - reestablish proper coronal tooth structure and function 4. Check Proximal contacts 5. Check Occlusal contacts 6. Check Axial walls 7. Check External Margins |
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What should you use to remove the sprue from your casting |
Carborundum separating disk; leave small area in center and twist to separate
Refine with stones and sandpaper disks |
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Should your proximal contacts on your casting be slightly loose or slightly tight |
Fit slightly too tight on the die --> should fit well in the mouth - DONT overreduce contact
Use articulating paper between castings/teeth to check |
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What shape should your connectors/embrasures be? |
U-shaped not V-shaped |
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What is the minimum thickness of the metal in your casting |
0.2mm |
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What is the most important reason for a highly polished casting aside from esthetics |
For optimum plaque control/to minimize plaque accumulation |
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What type of tools should you use to remove surface defects from your casting |
Abrasives |
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What two materials do you use for the final polishing of your casting |
Tripoli and Rouge |
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What step of the finishing process for your casting should you complete in the mouth |
Finishing the external margins - if you have access; if limited access, finish on the die |
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What do you use after abrasive disks, green stones and carborundum separating disks once smoothness and contour are acceptable |
Rubber wheels and points |
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When do you need to evaluate your metal-ceramic restoration? |
Once just evaluating the metal framework and then reevaluate following addition of porcelain |
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When you try in the metal framework intraorally, what must you have |
Absolute passive fit |
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What do you need to do to the metal framework if there isn't passive fit |
Solder transfer: Section/solder the framework, adjust it and then lute the pieces together¢ |
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What is the most likely reason for the metal framework touching opposing teeth in occlusion (when they're supposed to have PFM) |
Under-reduced preps |
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What does a tissue transfer allow you to do when checking a metal framework |
Gives you better adaptation of the tissue to the pontic for esthetics |
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What is a coping transfer and how does it help during the metal framework checking process |
Allows you to take an impression of the metal coping; the poured up model can be used if you break the die on your master cast |
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What is the stage in which you want to get your porcelain back to check after approving the metal framework |
Bisque-bake stage: stage right before glazing - want to minimize number of times you fire up the porcelain so check and readjust porcelain in this stage before glazing |
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What should you use to remove a provisional restoration before trying in the PFM fixed restoration |
Hemostats or crown-removing forceps |
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What is the order for evaluating the PFM fixed prosthesis chairside |
1. Check proximal contacts 2. Check marginal integrity 3. Check stability 4. Check occlusion 5. Check contour 6. Characterization 7. Glazing/polishing
All metal sequence: Internal margins, Intaglio surface, Remove Sprue, Proximal contacts, Occlusal contacts, Axial walls, External Margins |
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Should you adjust one proximal contact at a time or both sides at once when checking the contacts of your PFM |
Adjust both sides at once/alternating |
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What techniques do you use to check fit of the PFM |
Occlude or elastomeric paste (Fitchecker) - relieve pressure areas don't adjust with the fitchecker in the crown |
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What tools do you use to assess the marginal integrity of your PFM crown |
Sharp explorer - margins should be undetectable Confirm with Radiograph (Bitewing, not PA) |
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What is this the next step taken with your PFM casting/crown if you have: overhang ledge open margin |
Small overhang can often be corrected by adjusting the casting, smooth an area Small ledge may increase risk of recurrent decay, may be able to correct w/ new impression of framework/new die and add porcelain Open margin requires a new casting |
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What do you do if there's a deficient margin in metal area of casting versus in porcelain |
In metal - you can't solder and add to the margin, have to start over
In porcelain - can add the margin on to the porcelain if you can get an accurate impression with the margin present (but don't want too much firing of porcelain) |
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What happens when you have excessive firing of your porcelain |
Devitrified - changes from glassy to a crystalline state and porcelain becomes brittle and opaque |
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What do you if your casting isn't in occlusion with metal versus porcelain |
Remake if metal cast Additional firing if porcelain |
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What does characterization of the PFM involve |
Duplicate surface detail of natural teeth Generate textures of normal anatomic form Don't overcharacterize |
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What occurs during glazing of porcelain |
Surface layers slightly melt May apply surface stains for characterization Sufficient glazing required to limit plaque and fracture |
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Is polishing a suitable alternative to glazing porcelain |
Yes; provides greater control of surface luster and distribution; and show that it's no more abrasive than glazing
Unpolished porcelain is much more abrasive than polished or glazed |
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What are some of the main problems that lab techs have with work submitted to them by dentists |
Insufficient info in work authorization Submission of deficient impressions Inadequate occlusal records |
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What guidelines should dentists follow when submitting info to a lab tech |
Provide written instructions that details work, describes materials to use, and coloration (describe, photo, drawing etc) Provide accurate: impressions, casts, registrations Identify crown margins Properly clean and disinfect everything |
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What guidelines should lab techs follow when received info from dentist |
Follow guidelines of written instructions and include ample space for instructions on form Return case to check mounting if possible inaccuracy Match shade indicated Return work in a timely manner Follow infection control standards |
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What does a work authorization include |
General description of restoration to be made Material specification Desired occlusal scheme Connector design for FDP Pontic and substructure design Substructure design for metal ceramic restoration Shade selection (and distribution chart) Date of next scheduled pt appt Diagnostic waxing Casts of provisional restorations Digital images |
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What is the purpose of interim cement/when is it used |
Recommended to temporarily assess definitive prosthesis in cemented form; risky b/c it may be difficult to remove, and may loosen and be lost |
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How do you remove a prosthesis once it has been definitively cemented |
Must be drilled off and remade |
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When do you use traditional cements and when do you use adhesive resins |
Traditional cements for cast crowns and FDPs (not when adhesion needed) Adhesive resins for some restorations (all ceramic) when you need adhesion |
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What are the most commonly used luting agents for cast restorations |
Dental cements |
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Do you want a cement that's soluble or insoluble |
Prefer insoluble cement because you don't want it to be soluble in oral fluid and dissolve |
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What happens if cement dissolves in marginal areas (as a result of exposure to oral fluid) |
Space for bacteria and debris |
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What single luting agent meets all ideal properties |
None |
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Zinc phosphate cement |
*First cement, no longer used (but long history of success) Adequate strength Acceptable film thickness Reasonable working time Excess material easily removed Some toxic effects on pulp (acidic; evaluate RDT - remaining dentin thickness Could cause sensitivity and pulpal irritation/damage *High solubility and leakage |
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Zinc polycarboxylate cement |
Exhibits *adhesion to tooth only (due to calcium chelation; but no adhesion to casting) *Biocompatible High viscosity, difficult to mix Inferior long term retention (increase P:L ratio for decreased solubility; capsules make this and mixing easier) Often used as a temp cement Short working time Excess material hard to remove Low strength, low solubility *Use with retentive/resistant restorations and to avoid pulp irritation
Ex: Durelon - used in clinic |
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Glass ionomer cement |
Adheres to enamel and dentin Biocompatible Releases fluoride *Exhibits translucency Decent mechanical props Radiolucent appearance when set (hard to distinguish caries and overhang in radiograph) *Water contamination causes erosion Some *post-op sensitivity (acid in liquid) Use desensitizing agent (gluma) but could decrease retention Popular for cast restorations Ex: Ketac - used in lab |
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Zinc oxide-eugenol (ZOE) |
VERY Biocompatible - obtundant Provides excellent seal Many inferior properties: compressive strength, solubility, film thickness --> limited use
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Zinc oxide eugenol w/ ethoxybenzoic acid (Reinforced ZOE) |
Improved strength with modifier EBA - replaces some of the eugenol Short working time Hard to remove excess material Only use with retentive restorations VERY Biocompatible |
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Resin-modified glass ionomer luting agents (Resin ionomer) |
Combines good props of glass ionomer (*fluoride release and adhesion) with good props of resins (*high strength and low solubility) Less susceptible to water contamination Very popular cement *Avoid with all-ceramic restorations (fracture due to water contamination) May have reduced post-op sensitivity Ex: Fuji Plus |
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Resin luting agents (Adhesive resin and Composite resin) |
High polymerization shrinkage NOT Biocompatible Used for bonded ceramics Adhesive properties (can bond chemically to dentin) Improved properties over the years Not Soluble Different categories based on polymerization method and dentin bonding mechanism (Chemical, light, dural cure); use chemical for metal; light/dual cure for ceramic, light better Very retentive Use when you need adhesion: for all-ceramic and lab processed composite or when casting displaced due to lack of retention Adhesive and composite resins very similar except adhesive has low solubility and composite has high; also less working time with adhesive |
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What material do you not want included in a temp cement |
Eugenol - interferes with polymerization/setting of other cements |
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What are the properties of an ideal luting agent |
Long working time Adheres well to tooth structure AND cast alloys Good retention Provides a good seal Nontoxic to pulp/Biocompatible Adequate strength props Compressible into thin layers Low film thickness Low viscosity and solubility Low microleakage Long working time, short setting time Excess removed easily |
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When should you remove the excess material for different cements? |
Adhesive resins - remove before setting otherwise it'll never come off
Easiest to remove zinc phosphate, can wait until after setting |
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For restorations with poor retention what type of luting agent do you want to use |
FDP with poor retention - use adhesive resin ceramic inlay, ceramic veneer, etc - use adhesive resin or composite resin |
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With a history of post-op sensitivity what luting agents do you and do you not want to use |
Use reinforced ZOE or zinc polycarboxylate (very biocompatible)
Do NOT use composite resin |
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For what types of restorations can you use any luting agent |
Cast crown, PFM, partial FDP, PFM with porcelain margin |
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How do you clean the casting preparation before cementing |
Steam cleaning Ultrasonic Organic solvents
(remove blood, water, saliva) |
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What is the purpose of air abrading a casting before cementing |
Abrasion of internal surface increases retention of casting |
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For what type of temporary cement do you have to remove it with a scaler when ready for the definitive cementation |
Durelon (Zinc polycarboxylate) - the cement will be left on the tooth so you use scaler to clean away excess; if you don't clean properly, could cause incomplete seating |
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What happens if you over-dry the tooth |
Causes desiccation; fluid mvmt in the tubules causes sensitivity; Tooth prep must be dry but not overdry - dab with a cotton pellet |
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What do you use to clean the tooth after removing temporary cement and before definitive cementation |
Pumice and/or chlorhexidine preparation and then gently dry with cotton pellet |
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When might you coat the prepped tooth before cementation with cavity varnish or dentin bodning resin |
For non-adhesive cement ONLY |
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What type of motion do you use to seat the crown with the cement in place |
Rocking motion - so excess cement dissipates and no bubbles form; want to see excess cement come out around the margins |
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What do you use to make sure the crown is seated |
Bite stick or cotton roll - check if bite normal --> bite again - repeat process quickly
Crown can't be in hyperocclusion b/c this was already fixed - make sure it's seated all the way |
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What do you use to remove excess cement and when |
When cement is fully set, remove excess with explorer
Dental floss with a knot used interproximally |
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How long does cement take to completely set/develop final strength |
At least 24 hours |
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What is the problem if the patient comes back after crown has been cemented with redness around the crown |
Left cement in the sulcus |
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What causes a resin cement to set |
Excluding oxygen - must have an oxygen inhibited layer --> coat with oxygen inhibiting gel to promote polymerization |
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When should you clean off excess cement for resin luting agents |
When the cement has just begun to set, NOT when it's completely set, otherwise will have to drill it off |
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What is the ratio of powder:liquid used in lab to cement #30 crown |
1 level spoonful of powder: 2 drops of liquid |
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What type of cement is the Ketac cement used in lab |
Glass Ionomer |
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What is the setting time for Ketac cement used in lab |
7 minutes - when you should begin to remove excess |
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For Zinc Phosphate cement how should the powder and liquid be mixed |
Slowly incorporate powder into liquid, not all together at once - let the acidity dissipate |
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What additional steps are required for some adhesive resins during cementation |
Etching and bonding |
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What is covered in a patient's post-cementation appt? |
Dental health Identify incipient disease Promote plaque control habits Corrective tx if needed |
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How long after placement is the first post-cementation appt |
7-10 days |
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How often should you have recall appts for cast restorations |
Minimally every 6 months |
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Is it more important to distinguish between ideal vs normal occlusion or between physiologic vs pathologic occlusion |
Physiologic vs Pathologic |
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What is physiologic occlusion |
Adult occlusion that has survived despite departure from ideal/normal occlusion |
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What is pathologic occlusion |
Adult occlusion with evidence of pathology of teeth, TMJ, muscles, etc directly attributable to occlusal activity (e.g. ortho malocclusion, interferences, parafunction: grinding, clenching, etc) |
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How do you determine if occlusion is physiologic or pathologic |
Look for signs/symptoms of parafunction |
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What components of the masticatory system does occlusal activity have effects on |
Periodontium Dentition TMJ |
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What is parafunction |
Activity of the masticatory system outside range of normal function (have different intensity, frequency, duration); example of occlusal activity that can cause pathology in periodontium, dentition or TMJ |
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What are the responses of the attachment apparatus to parafunction |
Hyperfunction - physiologic Occlusal trauma - pathologic |
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What does the attachment apparatus consist of |
Cementum, PDL, Alveolar bone |
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What are the results of hyperfunction (a physiologic response to parafunction) |
Thicker PDL Thicker alveolar bone Increased trabeculation of supporting bone
(physiologic/reparative responses to increased parafunctional demand) |
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What are the clinical signs of occlusal trauma |
Increasing tooth mobility Tooth migration Tooth tenderness, thermal sensitivity
Occlusal trauma involves break down of the attachment apparatus as a result of occlusal forces; this lesion is reversible once stimulus removed |
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What are the radiographic signs of occlusal trauma |
Widened PDL Indistinct lamina dura Alveolar bone resorption Root resorption |
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What is the difference between primary and secondary occlusal trauma |
Primary - result of parafunction and strong forces Secondary - result of normal function and weaker forces (happens after primary occlusal trauma already occurring --> accelerated bone loss) |
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What are the potential effects of parafunction on dentition |
Mobility, migration, tenderness, thermal sensitivity, alveolar bone resorption |
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What are the effects of occlusal activity on dentition |
Retrograde wear, abfraction lesions, tooth fracture, pulpal pathology |
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What is retrograde wear and how does it appear |
Occlusal interferences, widened occlusal tables, esthetic and phonetic concerns - all from wearing down tooth cusps and grinding on occlusal tables -> more force on teeth --> more friction --> accelerated wear |
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What is abfraction wear and how does it appear |
Tensile and lateral stresses result from biomechanical loading of teeth; stresses --> fatigue and flexure of enamel and dentin --> deformation and microfracture --> erosion and/or abrasion accelerate loss of affected tooth structure
Wedge-shaped in cervical areas; sometimes on cuspal areas; one or many teeth; usually on teeth with minimal mobility |
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What are the potential effects of parafunction on the muscles |
Jaw pulled out of alignment; if you have occlusal interference can have changes in the jaw with trying to help close to avoid interference --> muscles don't rest and keep responding to interference --> fatigue |
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What are the potential effects of parafunction on the TMJ |
Uncoordinated musculature --> adaptive structural changes --> change in shape of the disk or the condyles (direct relationship b/w shape of condyle after remodeling and abrasion patterns on teeth due to parafunction) |
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What is involved in an occlusal examination |
Patient history Radiographs Comprehensive charting Diagnostic models Examination of oral function (landmark relationships in IC and RC, occlusal interferences, fremitus, etc) |
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How do you treat pathologic occlusion |
Identify occlusal etiologic factors Eliminate or control etiologic factors Eliminate existing pathology Establish therapeutic occlusion |
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What is therapeutic occlusion |
Occlusion that is conducive to health and function of the masticatory system for the individual patient
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What are the objectives of occlusal treatment |
Promote healing of the attachment apparatus Establish occlusal support compatible with requirements of TMJ Control tooth-to-tooth parafunction Eliminate or avoid occlusal awareness |
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What are the treatment modalities for occlusal treatment |
Occlusal equilibration, restorative treatment, appliance therapy, adjunctive therapy |
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What is a resin-retained fixed partial denture |
Consists of one or more pontics supported by thin metal retainers placed lingually and proximally on the abutment teeth |
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What does resin-retained fixed partial denture rely on |
Adhesive bonding between etched enamel and metal casting |
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What concept is resin-retained fixed partial denture based on |
Minimum Invasive Dentistry |
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What was the original RRFPD and how was it made |
Wing-like retainers with funnel shaped perforations for mechanical retention Restorations bonded with heavily filled composite resin
Retainers weakened by perforations, wear of the resin at perforations and limited adhesion |
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How was the RRFPD improved with the "Maryland Bridge" |
Mechanism developed for etching of the metal retainer --> improved retention with resin-to-etched metal bond; get micromechanical bonding from undercuts in metal casting created by etching; can only use Ni-Cr and Cr-Co metal alloys Oral surface of cast retainer highly polished to resist plaque accumulation |
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What is involved in the "Virginia Bridge" - type of RRFPD |
Involves "lost salt crystals" - incorporate salt crystals into retainer patterns to produce roughness on inner surface; permitted use with any metal ceramic alloy |
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What is the Adhesion Bridge - type of RRFPD |
Allows direct adhesion to metal - adhesion promoter 4-META allowed for better adhesion to metal |
