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263 Cards in this Set
- Front
- Back
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What are the 6 steps for a basic operative procedure?
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1. Outline form: external and internal
2. Retention and resistance form 3. Convenience form 4. Removal of remaining caries 5. Finishing enamel walls and margins 6. Cleansing the final cavity preparation |
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Define "external outline form":
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External outline is the extent of the periphery of the prepared cavity.
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The external outline form depends on what 6 factors?
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1. extent of carious lesion
2- proximity of caries to other defects in the enamel (extension for prevention) 3. convenience for access of instruments and finishing restoration 4. relationship of tooth to soft tissue 5. relationship of approximating and opposing teeth 6. esthetics |
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Describe the three general outlines for "extension for prevention":
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- include all of the fissures in the external outline
- include pits and potentially defective developmental grooves, decalcified areas - outline form should result in a restoration which extends to self-cleansing or caries immune enamel |
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The pulpal floor or axial wall should be at least how many mm into dentin?
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0.5 mm
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Restoration placement should be avoided in which extremely sensitive area?
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DEJ
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What are the three main reasons you want to preserve as much dentin as possible?
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- it supports the enamel
- it protects the pulp from thermal, chemical and mechanical stimuli - it acts as a cushion for the forces of occlusion |
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Define "retention form"
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Retention form is the form the cavity takes to prevent displacement of the restoration and is dependent upon five aspects of cavity preparation
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Define "resistance form":
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Resistance form is the form the cavity takes to prevent fractures of both the tooth and restoration.
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Parallel buccal and lingual walls are the ideal, but which should they NEVER be?
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diverging
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How are proximal boxes primarily retained?
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by the triangularity of the box
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What is convenience form?
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The shape or form of the cavity prep that allows adequate:
- visibility - accessibility for operator instrumentation - accessibility for patient oral hygeine |
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Define "anatomic crown":
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portion of the tooth covered by enamel, ends at CEJ
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Define "clinical crown":
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Portion of the tooth which is showing above the gingiva in the mouth
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WHat is the inorganic content of ENAMEL?
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95%
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The hardest part of the enamel is where?
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external surface
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What is the average enamel thickness at:
a) incisal edge b) premolar cusp c) molar cusp |
a) incisal approx. 2 mm
b) premolar approx. 2.3-2.5mm c) molar approx. 2.5-3mm |
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True or false: Dentinal tubules have the greatest diameter at the DEJ?
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FALSE - DEJ = 1-2 microns, Pulpal interface 3-4 microns
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How mineralized is dentin?
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~70%
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What is the main result on the anatomy of the tooth with secondary dentin formation?
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pulp cavity decreases in size
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What is the most sensitive part of the tooth?
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DEJ
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What are the four primary functions of the pulp?
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- sensory
- nutritive - defensive - formative |
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What is the mineralized content of cementum?
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45-50%
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What are the two types of cementum and where are they found primarily?
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ACELLULAR: coronal 2/3 of root surface
CELLULAR: apical 1/3 of root surface |
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What Class of prep is this?
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CLASS II
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What Class of prep is this?
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Class I
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What Class of prep is this?
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Class II
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What Class of prep is this?
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Class V
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What Class of prep is this?
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Class IV
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What Class of prep is this?
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Class III
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What Class of prep is this?
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Class I
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What GV Black Class of prep would this tooth most probably need?
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Class I
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What Class of prep would this tooth need?
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Class I
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What Class of prep is this?
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Class I
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What are the surface designations of CLASS I caries?
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- Occlusal
- Lingual pit - Buccal pit BOL |
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How would you define CLASS II caries?
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Caries in the proximal surfaces of premolars and molars.
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What are the surface designations of Class II caries?
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- MO
- DO - MOD - MODB - MODL - MODBL |
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How would you define CLASS III caries?
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Caries in the proximal surfaces of incisors and canines, not involving incisal angle
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What are the surface designations for CLASS III caries?
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- ML
- MB - DL - DB |
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How would you define CLASS IV caries?
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- caries in proximal surfaces of incisors and canines involving the incisal angle
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What are the surface designations of Class IV lesions?
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- MBI
- MLI - DBI - DLI |
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What are the surface designations of Class V lesions?
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- B
- L - wrap-arounds |
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What is the difference between SIMPLE, COMPOUND, and COMPLEX caries?
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- simple = single surface of tooth
- compound = two surfaces - complex = greater than two surfaces |
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What are the three essential components of dental caries to be present?
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- susceptible tooth
- presence of microorganisms such as Strep. mutans and lactobacilli - dietary factors (sugar) |
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What are the components of a prepared cavity?
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- WALLS
- Line angles - Point angles - Cavosurface |
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Define "line angle":
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- formed where two walls meet
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Define "point angle"
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formed where three walls meet
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Cavosurface angle:
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formed by junction of the wall of the prepared cavity and the unprepared surface of the tooth = external outline of prep.
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Amalgam requires what minimum thickness?
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2mm
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What are the largest teeth in the maxillary arch?
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Maxillary first molar.
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Which is the only tooth that has an oblique marginal ridge?
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Permanent maxillary molar
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What is the BULL rule?
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- Buccal Upper, Lingual Lower
- Triangularity of the box: buccal wall on upper is left straight (for aesthetics), lingual lower is left straight. |
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Today's handpieces run approx at what RPM?
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300,000
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What are slow-speed handpieces generally used for?
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- excavating caries
- refining cavity prep and placing retention - finishing and polishing restorations - prophylaxis - abrasive discs |
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Why are slow speed handpieces no longer used for routine cavity prep?
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- high amounts of vibration is traumatic to the patient
- requires more pressure to remove tooth structure which generates more heat - short bur life - more time consuming / less efficient - bur tends to roll out of certain shapes |
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What are the four primary ways that a tooth can be damaged by improper use of rotary instruments?
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- heat generation due to dull bur, insufficient coolant, or increased pressure
- vibration from a bur that is no longer straight - excessive tooth structure removal - unintentional penetration of sound enamel |
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What are the 3 main ways hand instruments are used?
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1. as explorers
2. as guages (measure depth) 3. as cutting and smoothing tools |
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What are the three parts of a hand instrument?
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- blade
- shank - handle |
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What is GV Blacks nomenclature for hand instruments?
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1. Order
2. Suborder 3. Class 4. Subclass |
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Operative dentistry is used to treat what?
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- pathology
- abnormalities - injuries/ trauma |
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What are the different types of injuries / trauma dealt with in OP?
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- fractures
- attrition (wearing of teeth due to mastication) - abrasion (not due to mastication) - erosion (chemical) - abfraction - iatrogenic (bad dentistry) |
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What are the different types of restorative materials?
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- silver amalgam
- composite - cast gold - porcelain - cohesive gold |
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How thick is enamel usually?
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2.5 mm to 0.1mm
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What is the orientation of enamel rods?
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perpendicular to the surface of the tooth
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WHere is ACELLULAR cementum found?
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CEJ
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Where is cellular cementum primarily found?
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apex
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Define CLASS III prep:
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proximal surfaces of anterior teeth
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Define CLASS IV prep:
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- incisal and proximal surfaces of teeth
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Define CLASS V prep:
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gingival third of the buccal or lingual surfaces of teeth
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Define CLASS VI prep:
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biting surfaces only (cusp tips/ incisal edges)
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Define LINE ANGLE:
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joining of 2 walls
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Define POINT ANGLE:
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joining of 3 walls (a corner)
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WHat are GV BLACKs seven steps for preparation?
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- outline form
- resistance form - retention form - convenience form - refinement - cleansing the cavity |
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Define OUTLINE FORM and features of a good one:
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Should be smooth, fluid, and determine the margins for the prep.
SMooth finish, cuspal support, marginal ridge support |
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Define RESISTANCE FORM and features of a good one:
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should be the best shape and placement of the walls, for the restoration and the tooth, to resist forces without fracture
- flat floor perpendicular to mastication force and sufficient bulk |
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Define RETENTION FORM and features of a good one:
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permit the retention to resist displacement
- composite bevels - |
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What is the instrument formula for THREE COMPONENTS?
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20 - 15 - 3
width of blade (2.0mm) blade is 15mm long 3 degree angle of blade (in reference to the handle) |
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What is the instrument formula for FOUR components?
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15 - 98 - 10 - 14
width of blade 1.5 mm angle of cutting edge = 98' length of blade = 10mm angle of blade 14' |
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What is the preparation criteria of OUTLINE FORM?
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- fluid and smooth
- all pits and primary grooves removed - dovetails into buccal , lingual , and proximal grooves - prep should be centered on developmental groove - marginal ridge walls should be parallel to the external contour of tooth - proximal walls should be slightly flared (2-3 degrees) Isthmus should be just wide enough to accept 1.0mm Thompson Condenser - bur angulation should be perpendicular to occlusal plane or parallel with angulation of the crown |
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What are the preparation criteria of INTERNAL FORM?
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- buccal and lingual walls parallel and parallel with long axis of the crown
- buccal, lingual, and proximal walls shold meet the pulpal floor at sharp angles - buccal and lingual walls should meet proximal walls smoothly - pulpal floor is flat and 1.5 mm depth - pulpal floor is parallel to occlusal plane (perpendicular to force) |
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What are the ADA specifications of AMALGAM?
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- 67-70% silver (increases strength and decreases flow)
- 25-27% tin (increases amalgamation and decreases strength) - 4-5% copper (increases strength, decreases flow) - 0-2% zinc (increases plasticity and marginal integrity) |
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What occurs with UNDERTRITURATION of amalgam?
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- crumbly amalgam that has excess Hg, decreased strength, increased corrosion, and increased setting expansion
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What occurs with OVERTRITURATION of amalgam?
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- decreases working time
- causes setting contractions - gives higher compressive strength |
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What does the mercury used in amalgam come from?
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Cinnabar (mercury sulfide)
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What is the average intake of mercury?
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10-20 mg / day
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What is the maximum amount of mercury released by an amalgam resto?
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3mg / day
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What kind of mercury is found in amalgam?
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elemental
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What kind of mercury is the most toxic?
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Organic (found in tuna fish)
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What are some reasons for using RUBBER DAM ISOLATION?
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- accessibility and visibility
- non-contaminated field - reduce airborne organisms - patient feels more comfortable / protected - time saving (no talking) - soft tissue retraction (Class V) - fewer lawsuits (fewer swallowed materials) |
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Which side of the rubber dam should face towards the dentist?
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DULL SIDE for less reflection of light
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PIN RETAINED AMALGAMS are indicated for:
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- too much tooth structure removed for normal retention features to be effective
- to build up a badly destroyed tooth - interim restoration during periodontal or endodontic treatment - patients who cannot afford to have a crown - elderly patients not capable of coming in for multiple appointments - foundation for full coverage restorations |
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PIN RETAINED amalgams are NOT indicated for:
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- teeth with large pulp chambers
- teeth that are already sensitive - non-vital teeth - teeth inaccessible to pin drill - anterior teeth |
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What are the disadvantages of PIN RETAINED AMALGAM?
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- drilling pin holes and placing pins -> craze lines or fractures
- pins help retain amalgam but amalgam material is not as strong with pin - remaining tooth structure not protected - pin may be come a pulp irritant depending on placement - pulp may be penetrated due to incorrect angulation / depth of pin placement - incorrect placement can lead to external tooth perf - |
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Where SHOULD and SHOULD NOT pins be placed?
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SHOULD:
- proximal line angles of molars - proximal line angles or cusp tips of premolars - at least 0.5 mm from DEJ - if below enamel on tooth measure 1.0mm from edge SHOULD NOT: - interproximals - furcation areas - near root concavities - demineralized dentin |
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What are the numbers associated with drilling pin?
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- Drill a depth of 2.0mm into dentin
- 2 mm of pin should be visible above dentin - one pin per missing cusp - 5mm between pins |
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What do you do if you penetrate the pulp with your pin?
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- run away
- remove pin or pin drill - control bleeding - cover with calcium hydroxide - inform patient - endodontic treatment - avoid lawsuit |
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IDEAL COMPOSITE should have:
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- good marginal seal
- realistic appearance - minimal wear / shrinkage - good strength - insolubility and biocompatibility |
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What are the major components of resins?
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MATRIX PHASE = Bis-GMA, dimethacrylate resin, urethane dimethacrylate
- polymerization initiators DISPERSED PHASE = fillers and tints - crystallized quartz - heavy metal glasses (radiopaque) - pyrogenic silica (ash) - coupling phases (help fillers bond) |
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Enamel wears at what rate?
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8 microns / year
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Wear of composite materials is determined by:
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- filler particle size
- surface porosity - depth of polymerization - degree of polymerization |
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What is the usual degree of polymerization of composite?
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- 55-73%
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What are the wear rates of teeth?
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Mandibular 1st premolar = 1
Max premolars and lower 2nd premolars = 2-3 Mand. 1st molar = 4 Max 1st molar = 5 Max and Mand 2nd molars = 5-6 |
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What is the average marginal gap?
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10-20 microns with average bacteria size of 0.2-5 microns
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WHere are MECHANICAL BONDS found?
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- adhesive and enamel / dentin
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Where are CHEMICAL bonds found?
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Adhesive and resin
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What is the purpose of prep conditioner / etchant?
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- etches enamel, dentin, opens / widens tubules, and removes smear layer
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What is the minimum time of curing a composite restoration?
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20-40 seconds
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What is the wavelength of curing lights?
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475nm (blue) with intensity of 600mW/cm2
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What is the ideal distance of the curing light from composite?
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1mm
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What is the ideal angle of curing light to restoration?
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90 degrees
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True or False: Darker / More Opaque shades cure faster?
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FALSE , cure slower
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What are the advantages of flowable composites?
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- syringeable
- placed directly - low stiffness - highly polishable |
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What are the disadvantages of floweable composites?
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- high poly shrinkage
- greater potential of microleakage - lower wear resistance (less filler) |
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What is FLOWEABLE recommended for?
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- cervical lesions
- sealing teeth after air abrasion - small repairs of teeth - pediatric restorations - class III restorations - first layer in proximal box of class II restorations |
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What are some principles of shade matching?
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- use VITA-SHADE guide
- educate patient regarding difficulties in shade selection - have patients remove lipstick - clean the teeth - wet teeth and select colour before RDI - do not stare for too long - rest eyes by looking at MILDLY BLUE objects - use patient and assistant opinions - use room light and natural light whenever possible - total area first and small areas second |
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What are OCCLUSAL SEALANTS indicated for?
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- stained grooves
- newly erupted teeth with uncoalesced grooves |
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For occlusal sealants which teeth should NOT be cut?
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- newly erupted
- unstained grooves |
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For OCCLUSAL SEALANTS which teeth should be cut?
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- teeth in function for a few years
- stained grooves |
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What are the steps BEFORE YOU BEGIN Class I Amalgam restoration?
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- assess occlusion (don't place comp margins in high stress regions)
- centric occlusion on tooth structure, not restorative material - BL width of prep should be 1/3 or less intercuspal distance - excessive wear from grinding / clenching not good for composite - prep should be as small and narrow as possible - SELECT A SHADE - RDI |
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What are the disadvantages of COMPOSITE RESTORATIONS?
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- technique sensitive
- poly shrinkage 2-3% - less than ideal wear - difficult to obtain adequate Class II interproximal contacts - inconsistent bond to dentin - need for RDI - take longer - greater fee |
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TYPE I Gold is used for what?
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- soft,
- small inlays in regions not subjected to extensive stress (Class III or Class V) - 80-96% gold |
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Type II gold is used for what?
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- medium
- used for normal inlays (Class I, II, III) - 73-83% gold |
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Type III gold is used for what?
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- HARD
- inlays - onlays - crowns - bridges with more occlusal stress - 71 - 80% gold |
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What is the most commonly used gold?
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TYPE III gold
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What is TYPE IV gold used for?
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- extra hard
- bridges where occlusal stress or span require added strength - RMV partials - PFM's - 62-72% gold |
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What is the advantageous property of GOLD?
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resists corrosion
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What is the advantageous property of COPPER?
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- increases hardness
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What is the advantageous property of SILVER?
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counters orange colour of copper
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What is the advantageous property of PALLADIUM?
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increases hardness and melting point
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What is the advantageous property of PLATINUM?
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increases melting point
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What is the advantageous property of ZINC?
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scavenges oxygen, prevent oxidation
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INLAYS can be used for what kind of preprs?
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CLASS I, II, III and IV
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Define ONLAY:
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- cover cusps
- extracoronal - do not extend B and L beyond heights of contour |
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What are the exit angles of INLAY?
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135 degree
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What kind of a bevel should be placed for INLAY?
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0.5 mm occlusal bevel
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What is the purpose of Sealants, Liners or Bases?
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Provide pulpal protection
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How does the adhesive bond to etched enamel or dentin?
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By micro-mechanical retention
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Why are adhesives used under amalgams?
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- provide a better seal against micro-leakage
- decrease post-op sensitivity by sealing dentinal tubules - provide a "weak bond" with amalgam |
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What are the three main types of bases on the market?
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- zinc phosphate cement
- Reinforced Zinc Oxide Eugenol (IRM) - Glass Ionomer cement |
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What is the thickness required for a cavity liner?
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0.5mm
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Where is the most common fracture of small Class II amalgams?
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Fracture at the isthmus
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What are the most common reasons for amalgam fracutre at the isthmus of a Class II restoration?
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- inadequate bulk - isthmus too narrow or too shallow
- heavy contact on the marginal ridge - large base was placed and nothing rigid over it |
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What are some reasons for poor condensation of amalgam?
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- amalgam has too short of a working time
- inadequate pressure during condensation - using amalgam that has set too much - failing to overlap and move stepwise during condensation - too large an increment was added - condenser size was wrong for the location - failure to overfill the restoration |
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How much time should condensation of amalgam take?
|
3.5 minutes (before needing a new mix of amalgam)
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What are the different speeds of Rotary Cutting Instruments?
|
- slow / low speed < 12,000 rpm
- medium / intermediate 12,000 - 200,000 rpm - high speed >200,000 rpm Today's handpieces approx. 300,000 rpm |
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What are slow speed handpieces used for?
|
- excavating caries
- refining cavity prep and placing retention - finishing / polishing restorations - prophylaxis of teeth - abrasive discs |
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High speed handpieces are routinely used for what?
|
- removal of old restorations
- extension to obtain outline form - cuspal reduction |
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What is the relationship between number of flutes on a bur and cutting efficiency?
|
- fewer blades = more efficient cutting and rougher surface
- more blades = less efficient cutting but smoother surface |
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Why are some burs "crosscut"?
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- to increase cutting efficiency
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What is the purpose of polishing an amalgam restoration?
|
- to obtain a smooth surface
- to improve marginal integrity - to remove flash and overhangs - to accentuate grooves - to perfect the occlusion - to correct contours - to decrease tarnish and corrosion |
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When polishing an amalgam with a bur what movement should be done?
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restoration to tooth
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What is the VERTICAL position of interproximal contacts?
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Usually transition of middle and occlusal thirds
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What is the HORIZONTAL position of interproximal contacts?
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Transition of middle and buccal thirds (premolars)
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Bad interproximal contacts can result in what?
|
- recurrent caries
- premature loss of restoration - perio problems - bad breath - loss of arch length (drifting/tilting) - more individual tooth trauma from occlusal forces |
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Which material was found to be the BEST for making Class II contacts with composite?
|
- Sectional matrix system
- Composi-TIght Gold |
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Composite increments should be no more than what thickness?
|
1mm increments on gingival floor
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What are the disadvantages of using floweable composite?
|
- more shrinkage (4-7%)
- less radiopaque - wears faster |
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What is TYPE I GOLD used for?
|
- soft
- used for small inlays in regions not subject to extensive stress (Class III or V) - 80-96% gold |
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What is TYPE II GOLD used for?
|
- medium
- normal inlays (Class I, II, III) - 73-83% gold |
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What is TYPE III gold used for?
|
- hard
- inlays, onlays, crowns, bridges - MOST FREQUENT FOR CASTING - 62-72% gold |
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What is TYPE IV GOLD used for?
|
- extra hard
- bridges where occlusal stress or span require added strength - also removeable partials and PFM's - 62-72% gold |
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What is the desireable property of GOLD?
|
resists corrosion
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What is the desireable property of COPPER?
|
increases hardness
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What is the desireable property of SILVER
|
Counteracts orange colour of copper
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What is the desireable property of PALLADIUM/
|
- increases hardness
- increases melting point |
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What is the desireable property of PLATINUM?
|
- increases melting point
|
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What is the desireable property of zinc?
|
scavenges oxygen, preventing oxidation
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How many teeth are in the PRIMARY DENTITION?
|
10 max
10 mand |
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How many teeth are in the SECONDARY DENTITION?
|
16 max
16 mand |
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Which is the class of dentition only found in SECONDARY?
|
Premolars
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What is the main function of INCISORS?
|
- shearing
- cutting |
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What is the main function of CANINES?
|
- Seizing
- piercing - tearing - cutting food |
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What is the main function of PREMOLARS?
|
- tearing of food
- grinding of food |
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What is the main function of MOLARS?
|
- fulcrum during function
- crushing - grinding - chewing of food |
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Enamel is formed by which cells?
|
Ameloblasts
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Where do the ameloblasts originate from?
|
ECTODERM
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What are TOMES PROCESSES?
|
Ameloblast extensions toward the DEJ
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Enamel is thickest where?
|
INCISAL and OCCLUSAL areas of the tooth
- becomes progressively thinner towards CEJ |
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Tooth colour depends on what factors?
|
- underlying dentin (enamel is translucent)
- thickness of enamel - staining present - degree of calcification and homogenicity |
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What is the volume percent of HYDROXYAPATITE in enamel?
|
90-92%
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Enamel rods are aligned ___________ to the DEJ.
|
perpendicular
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What is the hardest substance of the human body?
|
ENAMEL
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Where is the hardness of the enamel lowest?
|
DEJ
|
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Enamel is what kind of structure?
|
- brittle
- high elastic modulus - low tensile strength - rigid structure |
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Sound coalescence of enamel lobes results in _____ and fault coalescence results in ___________ .
|
GROOVES
FISSURES (faulty) |
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|
What is the percentage of acid usually used in etchant?
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35-50%
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Dentin and pulp tissues originate from what embryologically?
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mesodermal origin
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Dentin is formed by what cells?
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Odontoblasts
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The majority of the tooth is formed with which substance?
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Dentin
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When do the odontoblasts begin dentin formation?
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IMMEDIATELY before enamel formation by ameloblasts
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The most recently formed dentin is always proximal to what region?
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pulp
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Define "predentin"
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unmineralized zone of dentin immediately next to the cell bodies
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Primary dentin is usually completely laid down after how long?
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3 years
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Reparative dentin is usually formed when how much of the tooth is mechanically prepared?
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1.5 mm before the pulp
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Reparative dentin becomes microscopically apparent after how long?
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1 month
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What is the TENSILE and COMPRESSIVE STRENGTH of dentin compared to enamel
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ENAMEL:
tensile - 100 MPa compressive - Less than DENTIN: Compressive 266 MPa |
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How thick is the smear layer?
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a few MICROmeters
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What is the smear layer composed of?
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- denatured collagen
- hydroxyapatite - other cutting debris |
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Etching ENAMEL needs what concentration of acid?
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37+ %
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The convexity of teeth is usually found where?
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- cervical third of the crown on the facial surfaces of all teeth and the lingual surfaces of incisors and canines
- the POSTERIOR TEETH usually have their height of contour in the middle third of the crown. |
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If the convexity of the tooth is too great then what will happen?
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- inadequate stimulation by the passage of food of the investing tissues
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What may occur if there is inadequate contour of the teeth?
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trauma to periodontal apparatus
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What is the WORST way to contour a tooth?:
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OVERCONTOUR
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Where are the PROXIMAL CONTACT AREAS of MAX and MAND CENTRAL INCISORS?
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- incisal third
- slightly FACIAL to the center |
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Where are the proximal contacts in the rest of the teeth?
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- NEAR THE JUNCTION OF INCISAL THIRD and MIDDLE THIRD, or at the MIDDLE THIRD
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Which embrasures are usually bigger?
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LINGUAL
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Remineralization of the damaged tooth structure occurs when what pH is reached?
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5.5
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What in the saliva contributes to remineralize enamel?
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- calcium
- phosphate ions |
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Define CARIOGENICITY POTENTIAL:
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- degree to which a tooth is likely to become carious
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Which bacterial species predominate after a few days iwthin a plaque mass?
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- ANAEROBES
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What are some CLINICAL EXAM FINDINGS associated with increased caries risk?
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GENERAL APPEARANCE: sick, obese, malnourished
MENTAL / PHYSICAL DISABILITY: unable to comply with OHI MUCOSAL MEMBRANESL: dry, red, glossy ACTIVE CARIOUS LESIONS: cavitation/softening of enamel and dentin PLAQUE: GINGIVA: puffy, swollen, red EXISTING RESTORATIONS: |
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Which gender has a greater prevalence for caries?
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FEMALE
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What are the recommended guidelines for prescribing dental radiographs for dentate adults?
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NEW PATIENTS: Individualized radiographic exam
RECALL: High Risk - Bitewings at 12-18 month intervals No caries / No High Risk Factors - BW's at 24-36 mo intervals Periodontal Disease - individualized radiographs |
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What are some LOW INDICATORS of caries risk?
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- no carious lesions in last 3 years
- adequately restored surfaces - good oral hygeine - regular dental attender - fluoride dentrifice use |
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What are some MEDIUM RISK indicators for caries?
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- presence of 2 of the following
- current orthodontic or removeable appliance - several exposed root surfaces or - poor oral hygeine - frequent carb intaek - inadequate exposure to topical fluoride |
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What are some HIGH CARIES RISK indicators?
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- any carious lesion in previous 2yr
- inadequate salivry flow - initial enamel interproximal radiolucencies - presence of >2 of the risk indicators shown in the medium category |
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Why does public confusion regarding the effects of amalgam on human health exist?
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Mass media information is often not based on scientific facts
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The rate at which amalgam alloy reacts with mercury to form a set amalgam restoration is directly related to which factor?
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Heat treatment of the alloy during manufacturing
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What is the WEAKEST metallic phase in a set amalgam?
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Gamma Two
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What is the weakest component of set amalgam?
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VOIDS
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Why is a bevel contraindicated on the cavosurface angle of a Class I dental amalgam cavity prep?
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Thin flange of amalgam restorative material would fracture away
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High copper alloy dental amalgams are more resistant to corrosion due to what?
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Decreased presence of gamma two in the final set
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TRUE or FALSE: Sharp point angles are not a component of resistance form in a cavity.
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TRUE
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What is the area of the tooth that is the MOST sensitive during cavity prep?
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DEJ
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What is the area that is LEAST sensitive during cavity prep?
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ENAMEL
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Tooth #36 has caries in the buccal pit, what kind of prep is this going to be?
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CLASS I
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Why do we prefer narrow cavities to wide?
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conserve tooth strength / structure
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A large carious lesion on the distal surface of a maxillary central incisor is what class?
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CLASS III
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Define EXTERNAL OUTLINE FORM:
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shape or form of preparation at the surface of the tooth
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Contact areas between maxillary premolars are normally found on what portion of the proximal surface?
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Facial half
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How should the walls be related in mesial and distal marginal ridge walls of class I cavity prepared for amalgam?
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should diverge from pulpal floor to cavosurface margin
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Pulpal floor should be placed how deep into dentin?
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0.5mm
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Where are CLASS V cavities found?
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Gingival 1/3 of facial / lingual surfaces of teeth
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In a completed ideal Class V cavity prep for amalgam, the axial wall should be designed how?
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Parallel to the DEJ
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What is the main reason that occlusal wall is longer from external cavosurface to axial wall, than the cervical wall in a Class V prep?
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Enamel width is greater occlusally
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Where is retention placed for a Class V restoration?
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Occlusal and gingival line angles
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How many POINT ANGLES are there in a MO preparation?
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6
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How many WALLS are there in an MO prep?
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8
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What is the most common cause of fracture at the isthmus of a CLASS II dental amalgam?
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Inadequate depth at the isthmus area
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What is the FIRST STEP in removing a rubber dam?
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cut interseptal rubber dam with scissors
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Illustrate the difference between ditching and overfilling. Describe how you would avoid this problem.
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They are the opposite thing – ditching is when the filling is lower than the cavosurface and overfilling the material is above the cavosurface. This problem is avoided by carving the restoration with your instrument moving from tooth to filling with a part of the carving instrument always resting on natural tooth structure.
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Explain the steps you take when polishing an amalgam restoration. What consideration are there , what instruments do you use, etc. What instruments and techniques should you avoid and why?
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When rough irregularities are present on a surface an amalgam finishing bur can be used lightly to remove large surface irregularities. Then a series of polishing tips – brownies, greenies, and supergreenies – are used, cautiously and at a slow rate of rotation to prevent overheating, to make the surface shiny and smooth. Avoid using carbide burs or any instrument that is not specifically designed for polishing amalgam. Using burs on a high speed handpiece will cause excessive heating that will be easily conducted to the pulp by the metal filling. Also avoid overpolishing as this will also cause excessive heating.
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What is the purpose of pins?
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RETENTION
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TRUE or FALSE: Pins re-inforce the amalgam / composite restoration.
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FALSE
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Any area that will receive pin should be what?
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- flat
- perpendicular to long axis of tooth - present in zone of dentin sufficiently wide for placement of a pin |
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What are the ADVANTAGES OF PIN AMALGAMS?
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- where it would allow a more conservative tooth preparation from alternative treatments
- where gingival tissue would maintain a healthier state than if an indirect restoration with subgingival margins was placed - restoration can be placed in one appt - where economics is a primary consideration and the restoration would allow patient to retain the tooth rather than have it extracted - retention form is significantly improved |
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What are DISADVANTAGES OF PIN AMALGAMS?
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- proper contours and occlusal contacts are sometimes difficult to achieve
- drifting pin holes and placing pins may create crazes, fractures, and internal stresses - there is microleakage around all types of pins - pins do not reinforce the restoration and tensile strength are significantly decreased - pins increase the risk of pulp perforation |
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Which category of cavity prep are indicated for PINS?
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CLASS I: NO WAY JOSE!
CLASS IV: Very infrequently, if ever because of boding agents CLASS V: Rare, although |
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If when placing a pin you perforate into the pulp, what do you do?
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1: DO NOT PLACE PIN
2: Place CaOH and cover with Vitrebond |
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Which cavity sealant do we use?
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SINGLE BOND
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What is a cavity ssealant?
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thin film applied to walls of cavity to form a seal
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Why do we use cavity sealants?
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- reduce leakage of oral fluids around margins and walls
- retards penetration of corrosion products from amalgam into dentin - reduces penetration of phosphoric acid (from cements) |
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What is a cavity base?
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Used in moderately deep preparation
- Dentin replacement - provide chemical, thermal, and structural support |
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Which cavity base do we use?
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VITREBOND (GIC)
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Why are GIC's the bases of choice?
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- excellent physical properties
- fluoride release - adheres to tooth structure - may be used as temporary restoration (Fuji IX) |
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What is a cavity liner?
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- deep cavity preps that would benefit from therapeutc procedures
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What is the thickness of liner needed?
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minimal
- 0.5mm |
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Which cavity liner do we use?
|
Dycal
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TRUE or FALSE: IRM does not provide a good marginal seal.
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TRUE
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TRUE or FALSE: IRM in the long-term is soothing to the pulp.
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FALSE - IRM in long term can irritate or even cause pulpal death.
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What is the most important thing in getting a pulp to heal?
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Sealing the cavity against the oral environment is the most important
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How long do you wait to tell if an indirect pulp cap worked?
|
After 8 or more weeks
- pulp remains vital - tooth is not sensitive (hot cold perc) - radiograph shows evidence of remineralization - evidence of dentin bridge |
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What is the best business structure that can provide best success for dental practice?
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Incorporation
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