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49 Cards in this Set
- Front
- Back
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The crown of what tooth is the longest in the human dentition?
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Maxillary Central Incisors
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T/F: The crown of a max. central incisor is longer cervicoincisally than it is distomesially.
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True
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T/F: The crown of a max. central incisor is widest in the middle 3rd
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False
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What is the average height to width ratio of a maxillary central incisor?
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1.5:1
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What is the average height (Cerivcoincisally) of a maxillary central incisor?
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11.2 mm
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T/F, T/F: in a max. central incisor, the mesioincisal angle is rounded and nearly 90 degrees . On the same tooth, the distoincisal angle is rounded and more acute.
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T/F.
The distoincisal angle is more obtuse. |
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In what direction does the incisal edge of a maxillary central incisor slope cervically?
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Distally
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Where are the mesial and distal contact points located for a max. central incisor?
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Mesial - Incisal 3rd
Distal - Junction of missle and incisal 3rd |
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What is the average crown to root ratio for a max. central incisor?
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1:1.6
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Why do we care about crown to root ratios?
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They are important in determining what teeth to use to support crowns, bridges and partial dentures.
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Where is the shape of a max. central incisor root?
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Thick at the cerival third which narrows through the middle third to a blunt apex.
Is the same width MD as FL. All other max. roots are thicker FL than MD. Think of a big, fat ice cream cone. |
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What is the lingual fossa?
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A depressions found on the lingual side of the crowns of max. central incisors bounded by the cingulum cervically and the marginal ridges mesially and distally.
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What is a "shovel-shaped incisor?"
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A max. central incisor with a deep lingual fossaand prominent marginal ridges.
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Where is the cingulum found on max. central incisors?
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Slightly distal to the root axis line bisecting the crown on the lingual side.
It also defines the lingual height of contour. |
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Which marginal ridge is longer on a max. central incisor and why?
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The mesial ridge is larger because the cingulum points distally.
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What variation can the marginal ridges possess in max. central incisors?
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- Can be absent (deep, smooth fossa)
- Can have 1-4 accessory lingual ridges - Can have a pit on the cingulum near the intersection of the mesial and distal marginal ridges. (May need a sealent to prevent decay) |
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Describe the appearance of accessory lingual ridges on maxillary centrals.
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Narrow, linear ridges on the lingual surface extending from the cingulum to the lingual fossa.
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Describe the lingual root surface of a max. central.
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Convex. Narrower mesiodistally than the facial surface (like a wedge).
Flat on the mesial side and often possesses a longitudinal mesial depression. |
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T/F: The incisal edge of a max central is slightly facial from a proximal viewpoint.
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True.
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There is a slight twisting of the incisal edge that causes the edge to appear slightly lingual when viewed distally/mesially.
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Distally.
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Describe the labial outline of a maxillary central when viewed proximally.
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From cervical to incisal:
Convex -> flat -> broadly curved |
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Describe the curvature of the CEJ (cervical line) of a max. central incisor.
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Like all incisors, the CEJ curves incisally on the distal and mesial aspects of the tooth with the greater curvature occuring on the distal aspect.
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Where are the crests of curvature located for max centrals?
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Lingual - Cingulum
Labial - Just incisal to the CEJ |
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Describe the root outline of a max central from a proximal viewpoint.
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Labial - Slightly convex in the middle third of the root (Looks like a little bump)
Lingual - Nearly straight in the cervical third of the root then a gradual curve down to the apex. |
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Where is the mesial depression located on a max central?
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On the mesial surface of the root between the junction of the middle and lingual thirds of the root.
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Describe the distal aspect of the root of a max central.
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Convex, not flattened like the mesial. No depressions either.
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Why do we care about root morphology?
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It's important to determine anchorage for fixed prosth and to provide succesful endodontic treatment.
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Is the crown of a max central wider FL or MD?
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It's wider MD by about 1.5mm
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What does the pulp chamber of a max central incisor look like?
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The for of the pulp chamber follows the form of the crown, so the pulp chamber of a max central will be slightly triangular in shape (as will be the endodontic access cavity.
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Describe the morphology of the max central incisal ridge.
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1.5-2mm thick and slightly curved from mesial to distal (convex in respect to tongue)
DI angle is lingual to MI angle. |
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Describe the morphology of the labial portion of the max central viewed from the incisal edge.
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Convex in respect to the tongue, but some portions may be completely flat in some people.
Has two slight depressions (mesial and distal) in the incisal and middle thirds) which possess an artistic quality which can cause teeth to look "off" if not reproduced accurately. |
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How does the labial side of a max lateral compare to a max central?
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More convex mesiodistally
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Why does the max lateral incisor appear more oblong?
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Because it is the same length and shape, but is on average 2mm skinnier mesiodistally.
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How does the incisal edge of a max lateral compare to a central?
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Mesioincisal and distoincisal edges are more rounded and sloped. In some cases the distoincisal edge can resemble the cusp slopes of a canine.
Mamelons and labial depressions are also less evident. |
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Where are the contacts on a max lat incisor located?
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Mesial - Incisal 1/3 near the incisal edge
Distal - Junction of incisal and middle 3rds |
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How do the incisal angles of a max lateral compare to a max central?
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Mesioincisal - More acute
Distal - More obtuse, incisal edge slopes further cervically than a central as you move towards the distal. |
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How does the root length of a max lateral compare to those of a max central?
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The root is often slightly longer, .4mm, giving the lateral incisor a higher crown to root ration than a lateral and making it a more stable tooth for retaining appliances.
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How does the root shape of a max lateral compare to that of a max central?
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End of the apical 3rd of the roots bends slightly, usually towards the distal.
This makes the lateral a better anchor in bone. |
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How does the lingual aspect of the max lateral compare to the max central?
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Smaller and more pronounced. Just like a central, it may contain a restorable lingual pit.
Can also have lingual ridges, but isn't nearly as frequent as in centrals. |
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How does the cingulum and marginal ridges of a lateral max compare to a central?
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Cingulum - Smaller, more centered on the long axis of the root.
Marginal ridges - Variable, often worn down into occlusal facets by attrition. The lateral also has a long, straight mesial ridge and a short (due to the curve of the incisal edge) distal ridge. |
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How does the root of a maxillary lateral differ from a maxillary central?
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Depressions on both the mesial and distal surfaces as opposed to the mesial surface only.
Like the root of the central, it is wedge shaped with the "edge" facing the lingual. |
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Describe the incisal ridge of the max lateral from a proximal aspect.
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Incisal ridge is from 1-1.5mm wide and located slightly labial to the root axis.
This is an arch trait that distinguishes max from mand. Slopes cervically towards the lingual from it's most labial point. |
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Describe the curvature of the CEJ from a proximal aspect.
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The curvature is greater (2.5mm) on the mesial aspect.
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Describe the root anatomy from a proximal aspect.
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Root appears blunted and long (Crown to root ratio is higher than centrals)
-Mesial aspect is less convex (flatter)and more likely to have a depression. |
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Describe the crown proportions of a max lateral from an inicisal aspect.
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MD > FL, but in some laterals they can be equal (only a .4mm difference)
The crown is also more oval, with a central, more convex cingulum. The labial countour of a lateral is also FAR more convex (TYPE TRAIT) |
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Describe the differences between the incisal ridge of a max lateral vs. max central
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The incisal ridge of the lateral is almost straight, whereas the incisal ridge of the central is convex from a lingual perspective.
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What is the function of the incisors?
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The mandibular incisors acts as moving blades against the upper incisors to cut food.
They also: 1. Enable articulate speech 2. Support the lips. 3. Guide the mandible in movement. |
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Why are central max and mand incisor's mesial contacts special?
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They're the only mesial contacts in the mouth that touch each other.
If they don't touch, you have a diastema. |
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The incisor develop from 3 developmental nodes. Name them
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Mesial, middle and distal. They also form the facial depressions.
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