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This is a good compliation of all teeth and questions related to NDB I have covered pretty much 95% and it helpled me a lot and I guess my last posting in DA will be occlusion please read this and also refer to your Wheelers for tooth diagrams try and memorise all angles ok for now:
Permanent Teeth:
Maxillary Central Incisors:
(For a diagram of the following, see page 134 of Wheeler)
The maxillary central incisor:
-is the widest ANTERIOR tooth mesio-distally
(the widest tooth in the mouth is the mandibular first molar)
-is the only tooth with a pulp wider mesio-distally than facio-lingually
-is the only tooth with a cross section thru the CEJ that appears triangular
(the base of the triangle is facial; the apex points lingual)
-has the second tallest crown in the mouth
(the mandibular canine has the tallest crown in the mouth; the maxillary canine has the third tallest crown in the mouth)
From a facial or lingual view, the crown shape of every tooth in the mouth is a trapezoid (with the long side incisally/occlusally and the short side gingivally). The maxillary central is flat facially and wide mesio-distally. It has a ridge (like the elevations which soldiers hid behind in the civil war) in the middle of the facial surface. It has a fairly straight mesial outline nearly parallel to the root. The distal outline is more convex. Like all incisors, it has a fairly straight incisal ridge. The mesial inciso-gingival contact location is in the incisal third of the crown; the distal contact point is at the junction of the incisal and middle thirds. This is due to the sharp mesio-incisal corner and the round disto-incisal corner.
Mamelons are the bumps that are found on the incisal edges of permanent incisors. All permanent incisors (but not canines or primary incisors) erupt with 3 mamelons. (C do not erupt with mamelons.) The mamelons (one mesial, one distal, and the smallest one in the middle) represent 3 of the 4 developmental lobes (the cingulum represents the 4th lobe).
An embrasure is a V-shaped space around a contact area. There are 4 embrasures around each anterior contact area (incisal, gingival, facial, and lingual). Teeth are narrower lingually than they are facially, so the lingual embrasure is always wider than the facial embrasure. The exceptions are the maxillary first molar (which is wider lingually and has a smaller lingual embrasure) and between the mandibular centrals (where the facial and lingual embrasures are equal).
The maxillary central has well-developed lingual anatomy (though not as well-developed as that of the maxillary lateral). There are a series of elevations around the lingual fossa. There is a mesial marginal ridge (MMR), distal marginal ridge (DMR), cingulum, and incisal ridge.
All anterior teeth have a wedge-shaped (triangular) crown from a proximal view. The facial height of contour reflects the cervical ridge. The CEJ is considered a self-protective feature of the dentition because (in a young mouth) the epithelial attachment is here and prevents bacteria from invading deeper structures. The interproximal bone is parallel to the CEJs of adjacent teeth.
From an incisal view, the tooth has a triangular shape. The cingulum appears to the distal half of the tooth. That means that the mesial leg of the triangular shape is longer than the distal leg.
All maxillary anteriors have one root and one root canal. The maxillary central's root is straight, has a blunt apex, and is short (no longer than that of the maxillary lateral).
Maxillary Lateral Incisors:
(For a diagram of the following, see page 143 of Wheeler)
The maxillary lateral:
-has the best developed lingual anatomy
-is the most likely to have dens-in-dente
-is the 2nd most congenitally malformed or missing (second to the third molars)
The maxillary lateral is just like a maxillary central but squashed mesio-distally (making it rounder) and with better developed lingual anatomy. Surrounding the lingual fossa are the mesial marginal ridge, distal marginal ridge, cingulum, and incisal ridge. When malformed, the maxillary lateral tends to be peg-shaped. It might have a groove running onto the distal side of the root from the lingual pit. This anatomy makes scaling difficult (possible clinical correlation question).
The shape of the crown is trapezoidal from the facial. The mesial inciso-gingival contact point is at the junction of the incisal and middle thirds; the distal contact point is in the middle third. The mesio-incisal corner is sharper than the distal. There is one root (which is inclined distally and is as long or longer than that of the maxillary central) and there is one root canal. The bulky incisal ridge is in line with the long axis of the tooth. From an incisal view, the maxillary lateral appears oval shaped. It is as wide or wider facio-lingually as it is mesio-distally.
Mandibular Central Incisors:
(For a diagram of the following, see page 156 of Wheeler)
The mandibular central incisor:
-is the smallest tooth
-is the narrowest mesio-distally tooth
-is the most symmetrical tooth
-is the first succedaneous tooth (6 year molars are the first permanent teeth but do not replace primary teeth and do not qualify as "succedaneous")
Like all permanent incisors, the mandibular central erupts with 2 pulp horns, 3 mamelons, and lingual anatomy. The crown is fan-shaped, which makes the inciso-gingival contact points both in the incisal third of the tooth. (The mandibular lateral also has mesial and distal contact points in the incisal third, but the distal contact point is LOW in the incisal third. The mandibular canine has a mesial contact point in the incisal third and a distal contact point in the middle third. According to a nit-picky board question, the mandibular central is the only mandibular anterior which has both its mesial and its distal contact points at the same level.)
The smallest facial embrasure in the mouth is between the mandibular centrals. It might be the same size as the lingual embrasure, making it an exception to the rule that lingual embrasures are always larger than facial.
Mandibular incisors have smooth lingual anatomy. They usually have one root and one root canal, but maybe 40% have 2 root canals. The root is flat mesio-distally with a mesial and a distal concavity. (The deeper concavity is on the distal and faces the deep mesial concavity on the mesial surface of the adjacent lateral).
From an interproximal view, the facial CEJ is at a different level from the lingual CEJ on mandibular anterior teeth. The incisal edge is lingual to the long axis of the tooth, so from an incisal view less of the lingual side is visible than the facial surface. The pulp appears narrower from the facial view than from the interproximal view. The facial heights of contour protrude least on mandibular anteriors (they are biggest on mandibular molars).
Mandibular Lateral Incisors:
(For a diagram of the following, see page 164 of Wheeler)
The mandibular lateral is similar to the mandibular central but larger and not as symmetrical. (In contrast, the maxillary central is bigger than the maxillary lateral.) Right and left mandibular laterals can be distinguished because each has an incisal edge that appears twisted on its apex (as it goes from mesial to distal, it curves lingually) and an incisal ridge that is not at a right angle to the mesial and distal sides (as it goes from mesial to distal, it slightly slopes gingivally). The mandibular lateral is oval in cross section.
Maxillary Canines:
(For a diagram of the following, see page 176 of Wheeler)
The maxillary canine:
-is the widest ANTERIOR tooth bucco-lingually
(All posterior teeth are wider bucco-lingually, especially the maxillary first molar- which is the widest in the mouth.)
-is the longest tooth inciso-apically
-has the longest root
-has the third longest crown (behind the maxillary central and the mandibular canine)
Canines do not erupt with mamelons. The lingual anatomy is different from that of incisors; it still has a mesial marginal ridge, distal marginal ridge, and cingulum. But it does not have a lingual fossa because it has a lingual ridge which splits the lingual fossa into a mesial fossa and a distal fossa.
The maxillary canine erupts with 1 pulp horn and a prominent facial ridge on the (pointy) facial cusp. The mesial contact point is at the junction of the incisal and middle thirds; the distal contact point is in the middle third. (On both the maxillary and mandibular canines, the distal side reaches out more to make contact with the adjacent tooth than the mesial side does.) The maxillary canine bulges out mesio-distally from the CEJ more so than does the mandibular canine.
The facial cusp has a mesial cusp slope that is shorter than the distal cusp slope. (This is true of all teeth except for the primary maxillary canine and the permanent maxillary first pre-molar.) The mesial side is straighter than the distal. There is a concavity on the distal side of the root (the mandibular canine has a concavity on the mesial side of its root).
From an interproximal view, the cusp tip is facial to the long axis of the tooth. (So from an incisal view, more of the lingual surface is visible than the facial surface.) It is widest facio-lingually in the cervical third (since the facial and lingual heights of contour are in the cervical third) so the pulp canal is also widest facio-lingually in the cervical third.
Mandibular Canines:
(For a diagram of the following, see page 188 of Wheeler)
The mandibular canine:
-has the longest crown
-is the second longest tooth (next to the maxillary canine)
-has the second longest root (next to the maxillary canine)
-is the only tooth with a root that is inclined mesially
-is the anterior tooth most likely to have a bifurcated root
The mandibular canine has a duller cusp tip than does the maxillary canine. The mesial inciso-gingival contact point is in the incisal third. The distal contact point is in he middle third (but leaning toward the occlusal). A lingual ridge separates the mesial and distal fossa.
From an interproximal view, the mandibular canine has its incisal edge centered over or slightly lingual to the long axis of the tooth. The facial side makes a smooth arc due to its subtle crest of curvature.
From an occlusal view, the mandibular canine appears to have an oval shape.
Maxillary Pre-Molars:
Maxillary pre-molars have roots that are longer than incisors but shorter than canines; they have crowns that are shorter than canines but longer than molars. They have inciso-gingival contact points in the middle third. Like all maxillary posteriors, they have a trapezoidal shape when viewed interproximally.
(For a diagram of the following, see page 200 of Wheeler)
The maxillary first pre-molar:
-has a concavity in its crown gingival to the contact area
-on the facial cusp, has a longer mesial cusp slope than distal cusp slope
-has a mesial marginal ridge developmental groove
-has the shape of a kidney in cross-section
-bifurcates halfway down the root
-has the greatest demarcation between the pulp chamber and the pulp canals
From a lingual view, the the maxillary first pre-molar's lingual cusp appears to the mesial of the facial cusp, rounder than the facial cusp, and shorter than the facial cusp.
From the occlusal view, the maxillary first pre-molar is hexagonal in shape. There is a prominent facial ridge, a distal ridge, a mesial ridge, and a triangular ridge. There are triangular ridges from the facial and lingual cusps; these two triangular ridges meet perpendicular to the central developmental groove and form a transverse ridge which separates the mesial and distal pits.
The maxillary first pre-molar has 2 pulp horns, 2 roots and 2 root canals (the lingual canal is bigger than the facial canal).
(For a diagram of the following, see page 211 of Wheeler)
The maxillary 2nd pre-molar is similar to the maxillary first pre-molar. Unlike the first pre-molar, the lingual cusp is the same height as the facial cusp, but still to the mesial. There is no concavity on the crown. Instead of a long central groove with few supplemental grooves, it has a short central groove with a lot of supplemental grooves that make it look wrinkly. The mesial cusp slope is shorter than the distal cusp slope. From an occlusal view, it is rounder than the first pre-molar, but still hexagonal in shape. The maxillary second pre-molar has 1 root; about 50% have 2 canals.
Mandibular Pre-Molars:
(For a diagram of the following, see page 224 of Wheeler)
The mandibular first pre-molar:
-is the only tooth with its MMR at a grossly different angle than its DMR
-is the smallest pre-molar
-has the narrowest and smallest root of all the pre-molars
-has the most prominent transverse ridge of all the pre-molars
-is the only tooth with a mesio-lingual groove from the occlusal to the lingual
Except in terms of crown height, the mandibular first pre-molar is smaller than the mandibular second pre-molar in all dimensions. From an interproximal view, the facial cusp appears centered over the long axis; the lingual cusp tip is in line with the lingual surface of the root.
The mandibular first pre-molar has a tall facial cusp with a mesial slope shorter than the distal slope. From a lingual view, 4 surfaces (distal, mesial, occlusal and lingual) are visible because the tooth narrows facio-lingually. From an interproximal view, the mesial marginal ridge slopes cervically as it goes from occlusal to apical. The triangular ridges come together and separate the mesial and distal pits. The occlusal view has a diamond shape. It has one root and usually one root canal. 30% have a second root canal.
(For a diagram of the following, see page 233 of Wheeler)
The mandibular second pre-molar:
-is the pre-molar most likely to be congenitally missing
-is the pre-molar most likely to have a central pit
-is the pre-molar most likely to have 1 root and 1 canal
The mandibular second pre-molar is a transition between the first pre-molar and the first molar. Its lingual cusp is higher than that of the first pre-molar, but still not as high as that of the first molar.
If a mandibular second pre-molar is congenitally-missing, the roots of the primary mandibular second molar will not be resorbed and the primary tooth may be retained.
There are 2 types of mandibular second pre-molars. The 3 cusp type has three pulp horns. From an occlusal view, it has a square occlusal form and grooves that form a "Y." The 2-cusp type has a crescent-shaped appearance from an occlusal view.
The mesio-lingual cusp of the 3-cusp type is bigger than the disto-lingual cusp. There is a groove on the lingual surface between them. A cross-section of the root appears oval-shaped or round. The pulp is shaped like a funnel and has a dramatic constriction (though not as dramatic as that of the maxillary first pre-molar).
Maxillary Molars:
The "Rule of Singh" is designed to help determine whether a MAXILLARY tooth viewed from the occlusal is from the right or the left side of the mouth. Arrange the diagram so the lingual side is closer to your chest and the buccal side is away from your chest. If the mesial side is now on your left, the tooth is from the left side of the mouth. If the mesial is on your right, the tooth is from the right side of the mouth.
(For a diagram of the following, see page 250 of Wheeler)
The maxillary first molar:
-is the subject of a lot of board questions
-is the only tooth that is wider lingually than facially
-is the widest tooth facio-lingually
-is the only tooth with 2 triangular ridges on 1 cusp (the mesio-lingual cusp)
-has a concavity on the distal surface of its crown
The maxillary first molar has a cusp of Carabelli lingual to the mesio-lingual cusp. The cusp of Carabelli reminds us that this tooth formed from 5 lobes. (The other teeth to form from 5 lobes are the mandibular first molar and the 3-cusp form of the mandibular second pre-molar. The mandibular first molar has one lobe form each of the 5 cusps. The mandibular second pre-molar has one lobe for the mesial-marginal ridge, one for the distal marginal ridge, one for the mid-facial lobe, one for the facial lobe, and one for the lingual lobe.)
The mesio-lingual cusp has 2 triangular ridges; one heads down the cusp to the central groove, where it meets the triangular ridge from the mesio-buccal cusp to form the transverse ridge. The other triangular ridge heads down the mesio-lingual cusp to meet the triangular ridge of the disto-buccal cusp and form the oblique ridge. The transverse groove of the oblique ridge connects the distal fossa and central fossa.
There are 4 grooves on the maxillary first molar. There is a lingual groove; it extends onto the occlusal surface and becomes the distal oblique groove and ends in the distal pit. There is also a facial groove and a transverse groove of the oblique ridge.
There are 4 major functional cusps (the cusp of Carabelli is not functional). But there are only 3 major cusps from a developmental standpoint (the disto-lingual cusp gets progressively smaller on the maxillary second and third molars). The 3 major developmental cusps are the mesio-buccal, the mesio-lingual, and the disto-buccal.
Even though we all agree the facial surface of the maxillary first molar has a trapezoidal form, it has 5 sides from the facial view (according to an old board question). It has a lingual groove in the middle of the tooth. (On the second and third molars, the lingual groove is positioned more distally.)
The maxillary first molar has a tri-furcation with all its roots centered above the crown (the second and third maxillary molars have a more distal inclination to their roots). The palatal root is the longest and is the only root in the mouth with both a facial and a lingual concavity. The mesio-buccal root is the widest facio-lingually. The disto-buccal root is the shortest. It has a large root trunk.
The occlusal view has a rhomboidal shape with acute angles at the disto-lingual and mesio-buccal corners. It has obtuse angles at the disto-buccal and mesio-lingual corners. The height of the distal marginal ridge is the same as the height of the mesial marginal ridge and the height of the oblique ridge. The distal cusp of the mandibular first molar occludes with the distal fossa.
The mesio-lingual cusp is the biggest and tallest of all the cusps of the maxillary first molar. The mesio-buccal cusp is second largest; the disto-lingual cusp is third largest; the disto-buccal cusp is 4th largest. (On the second and third molars, the disto-lingual cusp is smaller and becomes the 4th largest cusp.)
When preparing a maxillary first molar for endo, the access should be made in triangular form to include 3 orifices. The longest leg of the triangle should be between the palatal and mesio-buccal orifices; the most acute angle should be at the mesio-buccal orifice; the most obtuse angle should be at the disto-buccal orifice.
There are 4 functional cusps, so there are 4 pulp horns. There are usually 3 canals, but 40% of the time, a 4th canal is in the mesio-buccal root.
(For a diagram of the following, see page 260 of Wheeler)
The maxillary second molar is similar to the first molar. But it has 2 types; there is a 4-cusp type (which has a lingual groove on the distal half of the lingual surface) and a 3-cusp type (in which the disto-lingual cusp is non-existent). From an occlusal view, the 3-cusp type has the occlusal shape of a heart. Both types have a large root trunk and 3 roots which are more fused and more inclined distally than those of the first molar. It rarely has more than 3 canals.
(For a diagram of the following, see page 268 of Wheeler)
Third molars are the teeth most frequently congenitally missing or malformed. The maxillary third molar has short crowns and long roots. (Mandibular molars have big crowns and short roots). Root length is important because longer roots are more easily anesthetized (possible clinical correlation).
Mandibular Molars:
The mandibular molars all have 2 roots. The mesial root is always bigger and wider facio-lingually than the distal. The biggest and straightest canal is in the distal root, which is better designed for paraposts. (There are 2 canals in the mesial root and they have to be small to both fit.)
(For a diagram of the following, see page 282 of Wheeler)
The mandibular first molar:
-is the widest tooth mesio-distally
-has 5 major functioning cusps
-erupts with 5 pulp horns
The mandibular first molar is 1mm wider mesio-distally than facio-lingually. It has 2 roots in a broad furcation. It is likely to have decay on the facial surface because of its buccal groove and buccal pit.
All 5 functioning cusps of the mandibular first molar can be seen from the facial or the distal aspect. The biggest cusp is the mesio-facial (the mesial supporting cusp). The tallest cusp is the mesio-lingual cusp. The smallest is the distal cusp.
The mandibular first molar has 4 grooves; it has a central developmental groove, mesio-facial groove, disto-facial groove and lingual groove.
(For a diagram of the following, see page 293 of Wheeler)
The mandibular second molar has roots which are more fused, more distally inclined, shorter in height, and shorter in width. In contrast to the mandibular first molar, the mandibular second molar has 4 cusps and only 3 grooves (a facial groove, lingual groove and central developmental groove). The occlusal view has a rectangular shape and grooves which form a plus (+) sign. The mesial side is wider than the distal, a helpful identification trait.
(For a diagram of the following, see page 303 of Wheeler)
Mandibular third molars have big crowns and short roots. They are frequently missing or malformed. They have fused roots with a distal inclination.
Primary Teeth:
Primary teeth can be grouped into 3 categories- anteriors, second molars, and first molars. All of them are different from permanent teeth in the following ways:
A- Primary teeth have thinner, whiter, less calcified enamel that is more uniform in depth than the enamel of permanent teeth.
B- Primary teeth have a thinner DEJ (so it's easier to have a pulp exposure).
C- Primary teeth have more prominent pulp horns.
D- Primary teeth have bigger cervical bulges (especially the first molars).
E- Primary teeth have enamel rods which go from the DEJ occlusally.
F- Primary teeth have a more narrow cervix.
G- Primary teeth have a narrower root trunk.
H- Primary teeth have roots which are more flared and skinny.
Most of the other traits that are exhibited by permanent teeth are held by the corresponding primary teeth. (For example, the widest anterior primary tooth mesio-distally is the maxillary central; the widest anterior tooth facio-lingually is the maxillary canine; the smallest tooth is the mandibular central.)
There are generally diastemas between the crowns of primary teeth, which appear short and fat. That makes the roots appear longer in comparison. By age 3, all primary teeth should be in occlusion.
Primary Anteriors:
The primary maxillary canine is one of only 2 teeth to have a longer mesial cusp slope than distal cusp slope on its incisal edge. (The permanent maxillary first pre-molar is the other.) From the facial view, the primary maxillary canine appears to have a diamond-shaped crown (unlike the trapezoidal-shaped crowns of all other teeth).
The mandibular lateral has a more exaggerated slope on its incisal edge than does the permanent lateral.
Primary Second Molars:
Primary second molars resemble the permanent first molars that will erupt adjacent to them.
The primary maxillary second molar is the widest primary tooth facio-lingually. It has 3 roots; the palatal is longest; the mesio-buccal is widest facio-lingually and has 2 canals. It has a rhomboidal occlusal outline.
The primary mandibular second molar is the widest primary tooth mesio-distally. It has 5 cusps; the smallest is the distal cusp (barely). It has two roots; the mesial root is bigger and has 2 canals.
Primary First Molars:
The primary first molars are the most unique deciduous teeth. They have 4 cusps and very prominent cervical bulges.
The primary maxillary first molar has a crown that resembles a permanent maxillary pre-molar and 3 roots that resemble a maxillary 6 year molar. It has occlusal grooves which form an "H".
The primary mandibular first molar is a very primitive looking tooth. It is probably the best answer when you're not sure how to answer a question about primary teeth. It has a mesio-lingual cusp shaped like an ice-cream cone that is the tallest cusp of the tooth. From the facial view, the mandibular first molar has a CEJ that curves up toward the distal.
Don't forget; it's us against the national boards. Good luck everyone-
Permanent Teeth:
Maxillary Central Incisors:
(For a diagram of the following, see page 134 of Wheeler)
The maxillary central incisor:
-is the widest ANTERIOR tooth mesio-distally
(the widest tooth in the mouth is the mandibular first molar)
-is the only tooth with a pulp wider mesio-distally than facio-lingually
-is the only tooth with a cross section thru the CEJ that appears triangular
(the base of the triangle is facial; the apex points lingual)
-has the second tallest crown in the mouth
(the mandibular canine has the tallest crown in the mouth; the maxillary canine has the third tallest crown in the mouth)
From a facial or lingual view, the crown shape of every tooth in the mouth is a trapezoid (with the long side incisally/occlusally and the short side gingivally). The maxillary central is flat facially and wide mesio-distally. It has a ridge (like the elevations which soldiers hid behind in the civil war) in the middle of the facial surface. It has a fairly straight mesial outline nearly parallel to the root. The distal outline is more convex. Like all incisors, it has a fairly straight incisal ridge. The mesial inciso-gingival contact location is in the incisal third of the crown; the distal contact point is at the junction of the incisal and middle thirds. This is due to the sharp mesio-incisal corner and the round disto-incisal corner.
Mamelons are the bumps that are found on the incisal edges of permanent incisors. All permanent incisors (but not canines or primary incisors) erupt with 3 mamelons. (C do not erupt with mamelons.) The mamelons (one mesial, one distal, and the smallest one in the middle) represent 3 of the 4 developmental lobes (the cingulum represents the 4th lobe).
An embrasure is a V-shaped space around a contact area. There are 4 embrasures around each anterior contact area (incisal, gingival, facial, and lingual). Teeth are narrower lingually than they are facially, so the lingual embrasure is always wider than the facial embrasure. The exceptions are the maxillary first molar (which is wider lingually and has a smaller lingual embrasure) and between the mandibular centrals (where the facial and lingual embrasures are equal).
The maxillary central has well-developed lingual anatomy (though not as well-developed as that of the maxillary lateral). There are a series of elevations around the lingual fossa. There is a mesial marginal ridge (MMR), distal marginal ridge (DMR), cingulum, and incisal ridge.
All anterior teeth have a wedge-shaped (triangular) crown from a proximal view. The facial height of contour reflects the cervical ridge. The CEJ is considered a self-protective feature of the dentition because (in a young mouth) the epithelial attachment is here and prevents bacteria from invading deeper structures. The interproximal bone is parallel to the CEJs of adjacent teeth.
From an incisal view, the tooth has a triangular shape. The cingulum appears to the distal half of the tooth. That means that the mesial leg of the triangular shape is longer than the distal leg.
All maxillary anteriors have one root and one root canal. The maxillary central's root is straight, has a blunt apex, and is short (no longer than that of the maxillary lateral).
Maxillary Lateral Incisors:
(For a diagram of the following, see page 143 of Wheeler)
The maxillary lateral:
-has the best developed lingual anatomy
-is the most likely to have dens-in-dente
-is the 2nd most congenitally malformed or missing (second to the third molars)
The maxillary lateral is just like a maxillary central but squashed mesio-distally (making it rounder) and with better developed lingual anatomy. Surrounding the lingual fossa are the mesial marginal ridge, distal marginal ridge, cingulum, and incisal ridge. When malformed, the maxillary lateral tends to be peg-shaped. It might have a groove running onto the distal side of the root from the lingual pit. This anatomy makes scaling difficult (possible clinical correlation question).
The shape of the crown is trapezoidal from the facial. The mesial inciso-gingival contact point is at the junction of the incisal and middle thirds; the distal contact point is in the middle third. The mesio-incisal corner is sharper than the distal. There is one root (which is inclined distally and is as long or longer than that of the maxillary central) and there is one root canal. The bulky incisal ridge is in line with the long axis of the tooth. From an incisal view, the maxillary lateral appears oval shaped. It is as wide or wider facio-lingually as it is mesio-distally.
Mandibular Central Incisors:
(For a diagram of the following, see page 156 of Wheeler)
The mandibular central incisor:
-is the smallest tooth
-is the narrowest mesio-distally tooth
-is the most symmetrical tooth
-is the first succedaneous tooth (6 year molars are the first permanent teeth but do not replace primary teeth and do not qualify as "succedaneous")
Like all permanent incisors, the mandibular central erupts with 2 pulp horns, 3 mamelons, and lingual anatomy. The crown is fan-shaped, which makes the inciso-gingival contact points both in the incisal third of the tooth. (The mandibular lateral also has mesial and distal contact points in the incisal third, but the distal contact point is LOW in the incisal third. The mandibular canine has a mesial contact point in the incisal third and a distal contact point in the middle third. According to a nit-picky board question, the mandibular central is the only mandibular anterior which has both its mesial and its distal contact points at the same level.)
The smallest facial embrasure in the mouth is between the mandibular centrals. It might be the same size as the lingual embrasure, making it an exception to the rule that lingual embrasures are always larger than facial.
Mandibular incisors have smooth lingual anatomy. They usually have one root and one root canal, but maybe 40% have 2 root canals. The root is flat mesio-distally with a mesial and a distal concavity. (The deeper concavity is on the distal and faces the deep mesial concavity on the mesial surface of the adjacent lateral).
From an interproximal view, the facial CEJ is at a different level from the lingual CEJ on mandibular anterior teeth. The incisal edge is lingual to the long axis of the tooth, so from an incisal view less of the lingual side is visible than the facial surface. The pulp appears narrower from the facial view than from the interproximal view. The facial heights of contour protrude least on mandibular anteriors (they are biggest on mandibular molars).
Mandibular Lateral Incisors:
(For a diagram of the following, see page 164 of Wheeler)
The mandibular lateral is similar to the mandibular central but larger and not as symmetrical. (In contrast, the maxillary central is bigger than the maxillary lateral.) Right and left mandibular laterals can be distinguished because each has an incisal edge that appears twisted on its apex (as it goes from mesial to distal, it curves lingually) and an incisal ridge that is not at a right angle to the mesial and distal sides (as it goes from mesial to distal, it slightly slopes gingivally). The mandibular lateral is oval in cross section.
Maxillary Canines:
(For a diagram of the following, see page 176 of Wheeler)
The maxillary canine:
-is the widest ANTERIOR tooth bucco-lingually
(All posterior teeth are wider bucco-lingually, especially the maxillary first molar- which is the widest in the mouth.)
-is the longest tooth inciso-apically
-has the longest root
-has the third longest crown (behind the maxillary central and the mandibular canine)
Canines do not erupt with mamelons. The lingual anatomy is different from that of incisors; it still has a mesial marginal ridge, distal marginal ridge, and cingulum. But it does not have a lingual fossa because it has a lingual ridge which splits the lingual fossa into a mesial fossa and a distal fossa.
The maxillary canine erupts with 1 pulp horn and a prominent facial ridge on the (pointy) facial cusp. The mesial contact point is at the junction of the incisal and middle thirds; the distal contact point is in the middle third. (On both the maxillary and mandibular canines, the distal side reaches out more to make contact with the adjacent tooth than the mesial side does.) The maxillary canine bulges out mesio-distally from the CEJ more so than does the mandibular canine.
The facial cusp has a mesial cusp slope that is shorter than the distal cusp slope. (This is true of all teeth except for the primary maxillary canine and the permanent maxillary first pre-molar.) The mesial side is straighter than the distal. There is a concavity on the distal side of the root (the mandibular canine has a concavity on the mesial side of its root).
From an interproximal view, the cusp tip is facial to the long axis of the tooth. (So from an incisal view, more of the lingual surface is visible than the facial surface.) It is widest facio-lingually in the cervical third (since the facial and lingual heights of contour are in the cervical third) so the pulp canal is also widest facio-lingually in the cervical third.
Mandibular Canines:
(For a diagram of the following, see page 188 of Wheeler)
The mandibular canine:
-has the longest crown
-is the second longest tooth (next to the maxillary canine)
-has the second longest root (next to the maxillary canine)
-is the only tooth with a root that is inclined mesially
-is the anterior tooth most likely to have a bifurcated root
The mandibular canine has a duller cusp tip than does the maxillary canine. The mesial inciso-gingival contact point is in the incisal third. The distal contact point is in he middle third (but leaning toward the occlusal). A lingual ridge separates the mesial and distal fossa.
From an interproximal view, the mandibular canine has its incisal edge centered over or slightly lingual to the long axis of the tooth. The facial side makes a smooth arc due to its subtle crest of curvature.
From an occlusal view, the mandibular canine appears to have an oval shape.
Maxillary Pre-Molars:
Maxillary pre-molars have roots that are longer than incisors but shorter than canines; they have crowns that are shorter than canines but longer than molars. They have inciso-gingival contact points in the middle third. Like all maxillary posteriors, they have a trapezoidal shape when viewed interproximally.
(For a diagram of the following, see page 200 of Wheeler)
The maxillary first pre-molar:
-has a concavity in its crown gingival to the contact area
-on the facial cusp, has a longer mesial cusp slope than distal cusp slope
-has a mesial marginal ridge developmental groove
-has the shape of a kidney in cross-section
-bifurcates halfway down the root
-has the greatest demarcation between the pulp chamber and the pulp canals
From a lingual view, the the maxillary first pre-molar's lingual cusp appears to the mesial of the facial cusp, rounder than the facial cusp, and shorter than the facial cusp.
From the occlusal view, the maxillary first pre-molar is hexagonal in shape. There is a prominent facial ridge, a distal ridge, a mesial ridge, and a triangular ridge. There are triangular ridges from the facial and lingual cusps; these two triangular ridges meet perpendicular to the central developmental groove and form a transverse ridge which separates the mesial and distal pits.
The maxillary first pre-molar has 2 pulp horns, 2 roots and 2 root canals (the lingual canal is bigger than the facial canal).
(For a diagram of the following, see page 211 of Wheeler)
The maxillary 2nd pre-molar is similar to the maxillary first pre-molar. Unlike the first pre-molar, the lingual cusp is the same height as the facial cusp, but still to the mesial. There is no concavity on the crown. Instead of a long central groove with few supplemental grooves, it has a short central groove with a lot of supplemental grooves that make it look wrinkly. The mesial cusp slope is shorter than the distal cusp slope. From an occlusal view, it is rounder than the first pre-molar, but still hexagonal in shape. The maxillary second pre-molar has 1 root; about 50% have 2 canals.
Mandibular Pre-Molars:
(For a diagram of the following, see page 224 of Wheeler)
The mandibular first pre-molar:
-is the only tooth with its MMR at a grossly different angle than its DMR
-is the smallest pre-molar
-has the narrowest and smallest root of all the pre-molars
-has the most prominent transverse ridge of all the pre-molars
-is the only tooth with a mesio-lingual groove from the occlusal to the lingual
Except in terms of crown height, the mandibular first pre-molar is smaller than the mandibular second pre-molar in all dimensions. From an interproximal view, the facial cusp appears centered over the long axis; the lingual cusp tip is in line with the lingual surface of the root.
The mandibular first pre-molar has a tall facial cusp with a mesial slope shorter than the distal slope. From a lingual view, 4 surfaces (distal, mesial, occlusal and lingual) are visible because the tooth narrows facio-lingually. From an interproximal view, the mesial marginal ridge slopes cervically as it goes from occlusal to apical. The triangular ridges come together and separate the mesial and distal pits. The occlusal view has a diamond shape. It has one root and usually one root canal. 30% have a second root canal.
(For a diagram of the following, see page 233 of Wheeler)
The mandibular second pre-molar:
-is the pre-molar most likely to be congenitally missing
-is the pre-molar most likely to have a central pit
-is the pre-molar most likely to have 1 root and 1 canal
The mandibular second pre-molar is a transition between the first pre-molar and the first molar. Its lingual cusp is higher than that of the first pre-molar, but still not as high as that of the first molar.
If a mandibular second pre-molar is congenitally-missing, the roots of the primary mandibular second molar will not be resorbed and the primary tooth may be retained.
There are 2 types of mandibular second pre-molars. The 3 cusp type has three pulp horns. From an occlusal view, it has a square occlusal form and grooves that form a "Y." The 2-cusp type has a crescent-shaped appearance from an occlusal view.
The mesio-lingual cusp of the 3-cusp type is bigger than the disto-lingual cusp. There is a groove on the lingual surface between them. A cross-section of the root appears oval-shaped or round. The pulp is shaped like a funnel and has a dramatic constriction (though not as dramatic as that of the maxillary first pre-molar).
Maxillary Molars:
The "Rule of Singh" is designed to help determine whether a MAXILLARY tooth viewed from the occlusal is from the right or the left side of the mouth. Arrange the diagram so the lingual side is closer to your chest and the buccal side is away from your chest. If the mesial side is now on your left, the tooth is from the left side of the mouth. If the mesial is on your right, the tooth is from the right side of the mouth.
(For a diagram of the following, see page 250 of Wheeler)
The maxillary first molar:
-is the subject of a lot of board questions
-is the only tooth that is wider lingually than facially
-is the widest tooth facio-lingually
-is the only tooth with 2 triangular ridges on 1 cusp (the mesio-lingual cusp)
-has a concavity on the distal surface of its crown
The maxillary first molar has a cusp of Carabelli lingual to the mesio-lingual cusp. The cusp of Carabelli reminds us that this tooth formed from 5 lobes. (The other teeth to form from 5 lobes are the mandibular first molar and the 3-cusp form of the mandibular second pre-molar. The mandibular first molar has one lobe form each of the 5 cusps. The mandibular second pre-molar has one lobe for the mesial-marginal ridge, one for the distal marginal ridge, one for the mid-facial lobe, one for the facial lobe, and one for the lingual lobe.)
The mesio-lingual cusp has 2 triangular ridges; one heads down the cusp to the central groove, where it meets the triangular ridge from the mesio-buccal cusp to form the transverse ridge. The other triangular ridge heads down the mesio-lingual cusp to meet the triangular ridge of the disto-buccal cusp and form the oblique ridge. The transverse groove of the oblique ridge connects the distal fossa and central fossa.
There are 4 grooves on the maxillary first molar. There is a lingual groove; it extends onto the occlusal surface and becomes the distal oblique groove and ends in the distal pit. There is also a facial groove and a transverse groove of the oblique ridge.
There are 4 major functional cusps (the cusp of Carabelli is not functional). But there are only 3 major cusps from a developmental standpoint (the disto-lingual cusp gets progressively smaller on the maxillary second and third molars). The 3 major developmental cusps are the mesio-buccal, the mesio-lingual, and the disto-buccal.
Even though we all agree the facial surface of the maxillary first molar has a trapezoidal form, it has 5 sides from the facial view (according to an old board question). It has a lingual groove in the middle of the tooth. (On the second and third molars, the lingual groove is positioned more distally.)
The maxillary first molar has a tri-furcation with all its roots centered above the crown (the second and third maxillary molars have a more distal inclination to their roots). The palatal root is the longest and is the only root in the mouth with both a facial and a lingual concavity. The mesio-buccal root is the widest facio-lingually. The disto-buccal root is the shortest. It has a large root trunk.
The occlusal view has a rhomboidal shape with acute angles at the disto-lingual and mesio-buccal corners. It has obtuse angles at the disto-buccal and mesio-lingual corners. The height of the distal marginal ridge is the same as the height of the mesial marginal ridge and the height of the oblique ridge. The distal cusp of the mandibular first molar occludes with the distal fossa.
The mesio-lingual cusp is the biggest and tallest of all the cusps of the maxillary first molar. The mesio-buccal cusp is second largest; the disto-lingual cusp is third largest; the disto-buccal cusp is 4th largest. (On the second and third molars, the disto-lingual cusp is smaller and becomes the 4th largest cusp.)
When preparing a maxillary first molar for endo, the access should be made in triangular form to include 3 orifices. The longest leg of the triangle should be between the palatal and mesio-buccal orifices; the most acute angle should be at the mesio-buccal orifice; the most obtuse angle should be at the disto-buccal orifice.
There are 4 functional cusps, so there are 4 pulp horns. There are usually 3 canals, but 40% of the time, a 4th canal is in the mesio-buccal root.
(For a diagram of the following, see page 260 of Wheeler)
The maxillary second molar is similar to the first molar. But it has 2 types; there is a 4-cusp type (which has a lingual groove on the distal half of the lingual surface) and a 3-cusp type (in which the disto-lingual cusp is non-existent). From an occlusal view, the 3-cusp type has the occlusal shape of a heart. Both types have a large root trunk and 3 roots which are more fused and more inclined distally than those of the first molar. It rarely has more than 3 canals.
(For a diagram of the following, see page 268 of Wheeler)
Third molars are the teeth most frequently congenitally missing or malformed. The maxillary third molar has short crowns and long roots. (Mandibular molars have big crowns and short roots). Root length is important because longer roots are more easily anesthetized (possible clinical correlation).
Mandibular Molars:
The mandibular molars all have 2 roots. The mesial root is always bigger and wider facio-lingually than the distal. The biggest and straightest canal is in the distal root, which is better designed for paraposts. (There are 2 canals in the mesial root and they have to be small to both fit.)
(For a diagram of the following, see page 282 of Wheeler)
The mandibular first molar:
-is the widest tooth mesio-distally
-has 5 major functioning cusps
-erupts with 5 pulp horns
The mandibular first molar is 1mm wider mesio-distally than facio-lingually. It has 2 roots in a broad furcation. It is likely to have decay on the facial surface because of its buccal groove and buccal pit.
All 5 functioning cusps of the mandibular first molar can be seen from the facial or the distal aspect. The biggest cusp is the mesio-facial (the mesial supporting cusp). The tallest cusp is the mesio-lingual cusp. The smallest is the distal cusp.
The mandibular first molar has 4 grooves; it has a central developmental groove, mesio-facial groove, disto-facial groove and lingual groove.
(For a diagram of the following, see page 293 of Wheeler)
The mandibular second molar has roots which are more fused, more distally inclined, shorter in height, and shorter in width. In contrast to the mandibular first molar, the mandibular second molar has 4 cusps and only 3 grooves (a facial groove, lingual groove and central developmental groove). The occlusal view has a rectangular shape and grooves which form a plus (+) sign. The mesial side is wider than the distal, a helpful identification trait.
(For a diagram of the following, see page 303 of Wheeler)
Mandibular third molars have big crowns and short roots. They are frequently missing or malformed. They have fused roots with a distal inclination.
Primary Teeth:
Primary teeth can be grouped into 3 categories- anteriors, second molars, and first molars. All of them are different from permanent teeth in the following ways:
A- Primary teeth have thinner, whiter, less calcified enamel that is more uniform in depth than the enamel of permanent teeth.
B- Primary teeth have a thinner DEJ (so it's easier to have a pulp exposure).
C- Primary teeth have more prominent pulp horns.
D- Primary teeth have bigger cervical bulges (especially the first molars).
E- Primary teeth have enamel rods which go from the DEJ occlusally.
F- Primary teeth have a more narrow cervix.
G- Primary teeth have a narrower root trunk.
H- Primary teeth have roots which are more flared and skinny.
Most of the other traits that are exhibited by permanent teeth are held by the corresponding primary teeth. (For example, the widest anterior primary tooth mesio-distally is the maxillary central; the widest anterior tooth facio-lingually is the maxillary canine; the smallest tooth is the mandibular central.)
There are generally diastemas between the crowns of primary teeth, which appear short and fat. That makes the roots appear longer in comparison. By age 3, all primary teeth should be in occlusion.
Primary Anteriors:
The primary maxillary canine is one of only 2 teeth to have a longer mesial cusp slope than distal cusp slope on its incisal edge. (The permanent maxillary first pre-molar is the other.) From the facial view, the primary maxillary canine appears to have a diamond-shaped crown (unlike the trapezoidal-shaped crowns of all other teeth).
The mandibular lateral has a more exaggerated slope on its incisal edge than does the permanent lateral.
Primary Second Molars:
Primary second molars resemble the permanent first molars that will erupt adjacent to them.
The primary maxillary second molar is the widest primary tooth facio-lingually. It has 3 roots; the palatal is longest; the mesio-buccal is widest facio-lingually and has 2 canals. It has a rhomboidal occlusal outline.
The primary mandibular second molar is the widest primary tooth mesio-distally. It has 5 cusps; the smallest is the distal cusp (barely). It has two roots; the mesial root is bigger and has 2 canals.
Primary First Molars:
The primary first molars are the most unique deciduous teeth. They have 4 cusps and very prominent cervical bulges.
The primary maxillary first molar has a crown that resembles a permanent maxillary pre-molar and 3 roots that resemble a maxillary 6 year molar. It has occlusal grooves which form an "H".
The primary mandibular first molar is a very primitive looking tooth. It is probably the best answer when you're not sure how to answer a question about primary teeth. It has a mesio-lingual cusp shaped like an ice-cream cone that is the tallest cusp of the tooth. From the facial view, the mandibular first molar has a CEJ that curves up toward the distal.
Don't forget; it's us against the national boards. Good luck everyone-
