secondarytoothmorphology_distinguishingcharacteristics

8/3/2019 SecondaryToothMorphology_DistinguishingCharacteristics

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DISTINGUISHING CHARACTERISTICSTHOSE CHARACTERISTICS THAT PERMIT AN INDIVIDUAL TOOTH TO BE

IDENTIFIED WHEN THERE ARE NO OTHER TEETH AVAILABLE FOR

COMPARISON

Maxillary Incisors1. When a maxillary incisor has a rounded crown outline form (as viewed facially or

lingually), it is more likely to be a lateral incisor. When a maxillary incisor has asomewhat square crown outline form, it is more likely to be a central incisor.

When the outline form of the proximal surfaces (as viewed facially or lingually) isrelatively convex as opposed to being somewhat straight, the tooth is more likely

to be a lateral incisor. For both central and lateral incisors, the proximal surface

with the most rounded outline form is the distal surface. When the incisal edge

(as viewed facially or lingually) is curved as opposed to being relatively straight,it is more likely to be a lateral incisor. When the proximoincisal angles (as

viewed facially or lingually) are rounded as opposed to being somewhat square, it

is more likely to be a lateral incisor. For both central and lateral incisors, theproximoincisal angle with the most rounding is located distally.

2. When both proximal contacts (areas of greatest convexity on the proximal

surfaces) of a maxillary incisor are located about one-third to one-half of thedistance between the incisal edge and cervical line (as viewed facially or

lingually), it is more likely to be a lateral incisor. For both central and lateral

incisors, the proximal contact that is located farther cervically in on the distalsurface.

3. When the cingulum of a maxillary incisor is large and exhibits a rounded form, it

is more likely to be a maxillary central incisor.

4. When the lingual fossa of a maxillary incisor is relatively small in area and deep,it is more likely to be a lateral incisor. When developmental grooves associated

with the lingual fossa are relatively deep or a groove crosses the cingulum, it is

more likely to be a lateral incisor.5. When a maxillary incisor has nearly identical mesiodistal and faciolingual crown

dimensions (as viewed incisally), it is more likely to be a lateral incisor. When

the mesiodistal dimension is greater than the faciolingual dimension (whenviewed incisally), the incisor is more likely to be a central incisor. For both

central and lateral incisors (as viewed incisally), the proximal surface that is more

rounded is the distal surface.

6. When a maxillary incisor has a root apex that is straight and relatively blunt, it ismore likely to be a central incisor. When the root apex is somewhat sharp and/or

curved, it is more likely to be a lateral incisor. When a maxillary incisor rootcurves, it usually curves toward the distal.

Mandibular Incisors1. When a mandibular incisor has a bilaterally symmetric crown form, it is more

likely to be a central incisor. When there is a lack of bilateral symmetry, the tooth

is more likely to be a lateral incisor.

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2. When a mandibular incisor has an incisal edge (as viewed incisally) that is

perpendicular to a line that bisects the crown faciolingually, it is more likely to bea central incisor. When the crown of a mandibular incisor appears twisted on

the root (as viewed incisally) so that one side of the incisal edge (the distal side) is

located lingual to the other side of the incisal edge, it is more likely to be a lateral

incisor.3. When the incisal edge of a mandibular incisor (as viewed facially) is

mesiodistally straight and perpendicular to the long axis, it is more likely to be a

central incisor. When the incisal edge is curved, it is more likely to be a lateralincisor. When the incisal edge is curved, the curvature occurs toward the distal

surface.

4. When both proximoincisal angles of a mandibular incisor (as viewed facially) areequally sharp, it is more likely to be a central incisor. When one corner (the

distoincisal corner) is slightly more rounded than the other corner, it is more

likely to be a lateral incisor.5. When both proximal contacts of a mandibular incisor (as viewed facially) are

located close to the incisal edge, it is more likely to be a central incisor. Whenone proximal contact (the distal contact) is located farther cervically than the

other contact, it is more likely to be a lateral incisor.6. When both proximal surfaces of a mandibular incisor (as viewed facially) exhibit

comparable convexity, it is more likely to be a central incisor. When one

proximal surface (the distal surface) exhibits greater convexity than the othersurface, it is more likely to be a lateral incisor.

Maxillary And Mandibular Canines1. When the crown and root of a canine (as viewed facially) lie on an almost straight

line on one proximal surface (the mesial surface), it is more likely to be a

mandibular canine. When both proximal crown surfaces extend lateral to the root,the tooth is more likely to be a maxillary canine. When one crown surface (the

distal surface) noticeably bulges lateral to the root, it is more likely to be a

maxillary canine.2. When the facial surfaces of the crown and root (as viewed proximally) form a C-

shaped curve, it is more likely to be a mandibular canine.When a canine hascervical tooth structure that prominently extends facial to the root (as viewed

proximally), it is more likely to be a maxillary canine.3. When the cusp tip of a canine is located lingual to the long axis of the tooth (as

viewed proximally), it is more likely to be a mandibular canine. When the cusp

tip of a canine is located facial to the long axis of the tooth (as viewed

proximally), it is more likely to be a maxillary canine. When the cusp tip is thickfaciolingually, the tooth is more likely to be a maxillary canine.

4. When a canine has a prominent pointed cusp (as viewed facially or lingually), thetooth is more likely to be a maxillary canine. When the angle between the mesial

and distal cusp ridges is obviously obtuse (about 120 degrees or more), the toothis more likely to be a mandibular canine. When the mesial cusp ridge is

positioned such that it nearly parallels the horizontal plane, the tooth is more

likely to be a mandibular canine.

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5. When both proximal contacts of a canine are located one-third to one-half of the

distance between the cusp tip and cervical line (as viewed facially), it is morelikely to be a maxillary canine. When both proximal contacts are located in the

incisal one-third of the crown (as viewed facially), it is more likely to be a

mandibular canine. For both maxillary and mandibular canines, one proximal

contact (the distal contact) is located farther cervically. The mesial proximalcontact of the maxillary canine is located one-third of the distance between the

cusp tip and facial cervical line whereas the distal proximal contact is located one-

half of the distance between the cusp tip and facial cervical line. The mesialproximal contact of the mandibular canine is located close to the incisal edge

whereas the distal proximal contact is located one-third of the distance between

the cusp tip and the facial cervical line.6. When a canine is viewed incisally and the mesial and distal halves exhibit

reasonable symmetry, the tooth is more likely to be mandibular canine. When the

faciolingual and mesiodistal dimensions approximate each other from an incisalview, it is more likely to be a maxillary canine whereas mandibular canines have

a faciolingual dimension that is visibly larger than their mesiodistal dimension.7. When a canine has a prominent, well-developed cingulum, it is more likely to be a

maxillary canine. When a canine has poorly developed marginal ridges and thelingual surface prominences are not distinctly displayed, it is more likely to be a

mandibular canine.

8. When a canine has a wear facet located on the lingual surface, the tooth is morelikely to be a maxillary canine. When a wear facet is located on the facial surface,

the tooth is more likely to be a mandibular canine.

9. When a canine has a sharp root apex, it is more likely to be a maxillary canine.When a canine has a blunt root apex, it is more likely to be a mandibular canine.

When a canine has a mesiodistally narrow root, it is more likely to be amandibular canine. When a canine has a root apex than angles mesially, it is

more likely to be a mandibular canine. When a canine has a bifurcated root, it is

more likely to be a mandibular canine.

Maxillary Premolars1. When a maxillary premolar crown is nearly symmetric (as viewed occlusally), it

is more likely to be a second premolar. When a maxillary premolar has

prominent, angular facioproximal corners (as viewed occlusally), it is more likelyto be a first premolar. When a maxillary premolar has rounded facioproximal

corners (as viewed occlusally), it is more likely to be a second premolar.

2. When there is one marginal ridge groove (the mesial groove) of a maxillary

premolar that is much more prominent than the other, it is more likely to be a firstpremolar. When there is one marginal ridge groove (the mesial groove) that

significantly disrupts the form of the marginal ridge and produces a concavecrown surface (as viewed occlusally), it is more likely to be a first premolar.

When the marginal ridge groove of a maxillary premolar joins a cervical crowndepression, it is more likely to be a first premolar and the surface is more likely to

be the mesial surface. When a marginal ridge groove of a maxillary premolar

creates greater cervical displacement of one marginal ridge (the mesial ridge), it is

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more likely to be a first premolar. When there are no marginal ridge grooves, the

tooth is more likely to be a second premolar.3. When one crown surface (the mesial surface) of a maxillary premolar has a

cervical depression and the other surface (the distal surface) has no cervical

depression, the tooth is more likely to be a first premolar. When there are no

cervical crown depressions, the tooth is more likely to be a second premolar.When there is a cervical crown depression (the mesial depression) of a maxillary

premolar that is deep and joins a deep root depression, the tooth is more likely to

be a first premolar. When one root depression (the mesial depression) of amaxillary premolar is deeper than the other root depression, the tooth is more

likely to be a first premolar. When the distal root depression is deeper than the

mesial root depression, the tooth is more likely to be a second premolar.4. When the lingual cusp tip of a maxillary premolar (as viewed lingually or

occlusally) is displaced toward one proximal surface (the mesial surface), the

tooth is more likely to be a first premolar. When the lingual cusp tip is nearlyaligned with the mesiodistal location of the facial cusp, the tooth is more likely to

be a second premolar.5. When there is a substantial difference between the heights of the facial and

lingual cusps of a maxillary premolar, it is more likely to be a first premolar.When the cusp facial and lingual cusp heights are equal or nearly equal, it is more

likely to be a second premolar.

6. When a maxillary premolar has a long central developmental groove that is aboutone-third or more of the mesiodistal crown dimension, it is more likely to be a

first premolar. When the central developmental groove is short (occupying about

one-quarter of less of the mesiodistal crown width, the tooth is more likely to be asecond premolar. When the central developmental groove of a maxillary

premolar is located well below the marginal ridges, the tooth is more likely to be afirst premolar.

7. When the mesial and distal pits and fossae of a maxillary premolar are relatively

close together (about one-quarter or less of the mesiodistal crown dimension) andthe marginal ridges appear wide and blunt, the tooth is more likely to be a second

premolar. When the fossae approximate the marginal ridges and the ridges are

relatively sharp, the tooth is more likely to be a first premolar.

8. When a maxillary premolar has a number of supplemental grooves, it is morelikely to be a second premolar. When there are very few or no supplemental

grooves, the tooth is more likely to be a first premolar.

9. When a maxillary premolar has a sharp facial cusp that approximates a 90 degreeangle between the cusp ridges (as viewed facially), the tooth is more likely to be a

first premolar. When the angle formed between the facial surface and the

triangular ridge of the facial cusp form an acute angle (as viewed proximally), thetooth is more likely to be a first premolar. When the mesial cusp ridge of the

facial cusp is longer than the distal cusp ridge of a maxillary premolar, the tooth is

more likely to be a first premolar. When the distal cusp ridge is longer than the

mesial cusp ridge, it is more likely to be a second premolar. When there is adepression in the mesial cusp ridge of the facial cusp, the tooth is more likely to

be a first premolar.

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10. When a maxillary premolar has two roots, it is more likely to be a first premolar.

When a maxillary premolar has a crooked root, it is more likely to be a secondpremolar.

Mandibular Premolars

1. When the crown of a mandibular premolar has a rounded diamond-shaped outlineform (as viewed occlusally), it is more likely to be a first premolar. When the

crown of a mandibular premolar has a somewhat square outline form (as viewedocclusally), it is more likely to be a second premolar.

2. When the crown of a mandibular premolar has a developmental groove that

extends from one fossa (the mesial fossa) in a proximolingual direction andcreates a depression in the outline form of the crown, it is more likely to be a first

premolar. When a mandibular premolar crown possesses a developmental groove

on the occlusal surface that traverses from the center of the tooth in a lingual

direction and extends onto the lingual crown surface, it is more likely to be asecond premolar.

3. When a mandibular premolar has one lingual cusp and two fossae, it is morelikely to be a first premolar. When a mandibular premolar has two lingual cuspsand three pits/fossae, it is more likely to be a second premolar. When there are

two lingual cusps on a mandibular premolar and one cusp (the mesiolingual cusp)

is wider and taller than the other cusp (the distolingual cusp), the tooth is morelikely to be a second premolar.

4. When one of the marginal ridges (the mesial ridge) of a mandibular premolar

slopes lingually at about a 45 angle (as viewed proximally), it is more likely to be

a first premolar. When one of the marginal ridges (the mesial ridge) of amandibular premolar is located farther cervically than the other ridge (as viewed

lingually), it is more likely to be a first premolar. When both marginal ridges are

located perpendicular to the long axis of the tooth (as viewed proximally), thetooth is more likely to be a second premolar. When the distance from the cusp tip

to the marginal ridge is about one-half of the occlusocervical crown dimension,

the tooth is more likely to be a first premolar. When the distance from the cusptip to the marginal ridge is about one-third or less of the occlusocervical crown

dimension, the tooth is more likely to be a second premolar.

5. When a mandibular premolar possesses a substantial difference in the heights ofthe facial and lingual cusps (average of 3.6 mm or about one-third of the

occlusocervical crown dimension) with one cusp (the lingual cusp) being much

shorter than the other cusp (the facial cusp), the tooth is more likely to be a first

premolar. When the difference in facial and lingual cusp heights is less than

twenty-five percent of the occlusocervical crown dimension (average of 1.8 mmshorter), the tooth is more likely to be a second premolar.

6. When a mandibular premolar has a sharp facial cusp (about a 100 degree anglebetween the mesial and distal cusp ridges) that is relatively tall, the tooth is more

likely to be a first premolar. When a mandibular premolar has a relatively bluntcusp tip (about 130 degree angle between the mesial and distal cusp arms) that is

relatively short, the tooth is more likely to be a second premolar. With both first

and second premolars, the mesial cusp ridge is shorter than the distal cusp ridge.

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7. When the facial cusp of a mandibular premolar is aligned with the long axis of the

tooth (as viewed proximally), it is more likely to be a first premolar. When thefacial cusp of a mandibular premolar is located facial to the long axis of the tooth

(as viewed proximally), it is more likely to be a second premolar.

8. When the lingual aspect of a mandibular premolar crown is much smaller

mesiodistally than the facial aspect of the crown, the tooth is more likely to be afirst premolar. When the lingual aspect of a mandibular premolar crown has a

greater mesiodistal dimension than the facial aspect of the crown, the tooth is

more likely to be a second premolar.9. When most of the occlusal surface of a mandibular premolar crown is visible (as

viewed lingually) and the visible area comprises about one-half of the

occlusocervical crown dimension, it is more likely to be a first premolar. Whenthe visibility of the occlusal surface is limited and the visible area comprises one-

third or less of the occlusocervical crown dimension (as viewed lingually), the

tooth is more likely to be a second premolar.10. When the occlusal developmental grooves of a mandibular premolar have a Y

shaped form, it is more likely to be a second premolar.11. When the distal proximal contact of a mandibular premolar is located at the same

occlusocervical level as the mesial contact or occlusal to the mesial contact, it ismore likely to be a first premolar. When the distal proximal contact is located

cervical to the mesial proximal contact, the tooth is more likely to be a second

premolar.

Maxillary Molars1. When the mesiodistal and faciolingual crown dimensions of a maxillary molar are

about the same and the tooth presents a degree of squareness (as viewed

occlusally), it is more likely to be a first molar. When the faciolingual dimension

is noticeably larger than the mesiodistal dimension (as viewed occlusally), thetooth is more likely to be a second or third molar. When a maxillary molar

appears heart-shaped (as viewed occlusally), the tooth is more likely to be a third

molar. When the angle between the mesial and facial surfaces of a maxillarymolar is noticeably acute, the tooth is more likely to be a second or third molar.

For all maxillary molars, the faciolingual dimension of the mesial half of the

crown is greater than the faciolingual dimension of the distal half of the crown (as

viewed occlusally)2. When there is a cusp of Carabelli (5

thcusp attached to the lingual surface on the

mesiolingual cusp) present on a maxillary molar, it is more likely to be a first

molar. When there is a distolingual cusp present but no cusp of Carabelli, the

tooth is more likely to be a second molar. When there is no distolingual cusp andno cusp of Carabelli, the tooth is more likely to be a third molar.

3. When one lingual cusp (the distolingual cusp) of a maxillary molar is relativelywide and approaches the height of the other larger lingual cusp (the mesiolingual

cusp), it is more likely to be a first molar. When one lingual cusp (thedistolingual cusp) is considerably smaller in size and height than the other lingual

cusp (the mesiolingual cusp), the tooth is more likely to be a second or third

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molar. When the distolingual cusp is missing and there is only one lingual cusp,

the tooth is more likely to be a third molar.4. When the two facial cusps of a maxillary molar have about the same mesiodistal

dimension and height, it is more likely to be a first molar. When one facial cusp

(the distofacial cusp) is smaller and shorter than the other facial cusp (the

mesiofacial cusp), the tooth is more likely to be a second molar. When thedistofacial cusp is much smaller and shorter than the mesiofacial cusp, the tooth is

more likely to be a third molar.

5. When the facial developmental groove of a maxillary molar (as viewed facially) islocated close to the mesiodistal center of the crown, extends a substantial distance

cervical to the occlusal surface, and ends in a depression or pit, it is more likely to

be a first molar. When the facial developmental groove is located toward one sideof the crown (distal to the mesiodistal center of the crown) and has a relatively

short occlusocervical dimension, the tooth is more likely to be a second molar.

When the facial developmental groove is substantially displaced to the distal, thetooth is more likely to be a third molar.

6. When the mesiodistal dimension of the lingual half of a maxillary molar crown isas large or larger than the facial half of the crown (as viewed occlusally), it is

more likely to be a first molar. When the mesiodistal dimension of the lingualhalf of the crown is noticeably smaller than the mesiodistal dimension of the

facial half of the crown, the tooth is more likely to be a second molar. When the

crown has a significant lingual taper and the lingual surface resembles a C-shapedcurve (as viewed occlusally), the tooth is more likely to be a third molar.

7. When the oblique ridge of a maxillary molar is very prominent and large, the

tooth is more likely to be a first molar. When the oblique ridge is extremely smallor missing, the tooth is more likely to be a third molar.

8. When a maxillary molar has only a limited number of supplemental grooves, thetooth is more likely to be a first molar. When a maxillary molar has a substantial

number of supplemental grooves, it is more likely to be a second or third molar.

9. When a maxillary molar has substantial separation of all three roots, it is morelikely to be a first molar. When the separation of the two facial roots of a

maxillary molar approaches the mesiodistal dimension of the crown, it is more

likely to be a first molar. When the facial roots of a maxillary molar are shaped

like the handles of a pair of pliers (as viewed facially), it is more likely to be afirst molar. When the facial roots of a maxillary molar parallel each other, are

contained within the mesiodistal dimension of the crown, and have a distal

inclination, it is more likely to be a second molar. When the roots of a maxillarymolar are fused and have a substantial distal inclination, it is more likely to be a

third molar. With all maxillary molars, the mesiofacial root has a greater

faciolingual dimension than the distofacial root and often hides the distofacialroot from a mesial view. Conversely, the smaller distofacial root allows the

mesiofacial root to be visible from a distal view.

Mandibular Molars1. When a mandibular molar has three facial cusps and a trapezoidal crown outline

form (as viewed facially), it is more likely to be a first molar. When a mandibular

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molar has two facial cusps and a trapezoidal crown outline form (as viewed

facially), it is more likely to be a second molar. When the crown of a mandibularmolar has a rounded, bulbous form (as viewed facially), it is more likely to be a

third molar. When a mandibular molar has three facial cusps, one of the cusps

(the distal cusp) is usually smaller than the other two cusps.

2. When a mandibular molar has three facial cusps and a hexagonal/pentagonalcrown outline form (as viewed occlusally), it is more likely to be a first molar.

When a mandibular molar has a rectangular crown outline form (as viewed

occlusally), it is more likely to be a second molar. When a mandibular molar hasan ovoid or rounded outline form (as viewed occlusally), it is more likely to be a

third molar. When a mandibular molar (as viewed occlusally) has a prominence

(bulge) toward one corner of the outline form (the mesiofacial corner), it is morelikely to be a second molar.

3. When both proximal surfaces of a mandibular molar form relatively straight lines

(as viewed occlusally), it is more likely to be a first molar. When one proximalsurface (the mesial surface) of a mandibular molar forms a relatively straight line

and the other proximal surface (the distal surface) has a curved C-shaped form (asviewed occlusally), it is more likely to be a second molar. When both proximal

surfaces of a mandibular molar have curved, rounded forms, it is more likely to bea third molar.

4. When the crown of a mandibular molar has a rounded, bulbous outline form (as

viewed proximally), it is more likely to be a third molar.5. When a mandibular molar has a large occlusal table with a mesiodistal dimension

that is greater facially than lingually (as viewed occlusally), it is more likely to be

a first molar. When a mandibular molar has a large occlusal table that isrectangular (as viewed occlusally), it is more likely to be a second molar. When a

mandibular molar has an occlusal table that is ovoid in form and relatively smallin area, resulting in only modest separation of the facial and lingual cusp tips (as

viewed occlusally or proximally), it is more likely to be a third molar.

6. When a mandibular molar has a central developmental groove with a zigzagmesiodistal form, it is more likely to be a first molar. When a mandibular molar

has a central developmental groove that is straight and there is a perpendicular

relationship between the facial and lingual developmental grooves that creates a

shape resembling a plus sign, it is more likely to be a second molar. When amandibular molar has an irregular pit-groove pattern with numerous grooves, it is

more likely to be a third molar.

7. When a mandibular molar has five cusps and only a limited number ofsupplemental grooves, it is more likely to be a first molar. When a mandibular

molar has four cusps and a modest number of supplemental grooves, it is more

likely to be a second molar. When a mandibular molar has a large number ofsupplemental grooves and exhibits a wrinkled appearance because of the

number of grooves, it is more likely to be a third molar.

8. When a mandibular molar has one root (the mesial root) that is curved and

another root (the distal root) that is relatively straight, it is more likely to be a firstmolar. When a mandibular molar has two widely separated root apices, it is more

likely to be a first molar. When both roots of a mandibular molar are nearly

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parallel to each other, it is more likely to be a second molar. When both roots of a

mandibular molar are distinctly separate but both curve distally, it is more likelyto be a second molar. When both roots of a mandibular molar curve distally and

they are also in close approximation or fused, it is more likely to be a third molar.

When both roots of a mandibular molar are in close approximation or fused and

appear short in comparison to the occlusocervical crown dimension, it is morelikely to be a third molar. For all mandibular molars, the mesial root has a greater

faciolingual dimension than the distal root.

(Goodacre Teeth/Disting Character)

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secondarytoothmorphology_distinguishingcharacteristics

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