molars Flashcards
eruption
first molars: 6-7y
second molars: 12-13y
third molars: 17-21y
smth special abt roots and proportion?
dimensions
crown length < root length
mesio distal > occlusocervical
faciolingual >occlusocervical
all 3 maxillary molars have 3 roots w mesiobuccal, distobuccal, palatal
palatal is the longest root
faciolingual > mesiodistal for maxillary molars
mesiodistal > faciolingual for mandibular molars
crown outline forms
facially: all trapezoidally
m/d: trapezoidal for mx, rhomboidal for mn
occlusally: rhomboidal for mx first and second molar, heart shaped for mx third molar
pentagonal for mn first molar, rectangular/parallelogram for mn second molar, ovoid for mn third molar
number of cusps
mx first molar: 5 (ML>MF>DF>DL>cusp of carabelli)
mx second molar: 4 or 3 (no DL) [M;>MF>DF>DL] CUSP OF CARABELLI IS RARE ON MX SECOND MOLAR
mx third molar: highly variable (L>MF>DF) little to no DL
mn first molar: 5 (MF>ML/DF>DF>D)
mn second molar: 4 (MF>ML>DF>DL)
mn third molar: 4/5 (MF>DF/ML>DL) can be very huge and posess 6-8
facial view
mesio facial and disto facial cusp
mx first molar: mf cusp > df cusp but df cusp is sharpest
mx second molar: mf cusp > df cusp
mx third molar: mf cusp wider and longer than df cusp, df cusp is short and flat
mn first molar: mf cusp is the largest of the 3 facial cusps, df cusp may be sharper than mf but not sharper than distal cusp
mn second molar: mf cusp> df cusp
mn third molar: mf cusp > df cusp
facial view
facial groove anatomy
mx first molar: extends to mid third, slightly distal
mx second molar: doesn’t extend to mid third, distal to the crown
mx third molar: distal to crown
mn first molar: 2 grooves -> MF groove > DF groove, extending to the mid third, mesial to crown
mn second molar: extends to mid of crown
mn third molar: present
facial view
mesio occlusal and disto occlusal angle in maxillary first molars
MO is more well defined, DO is rounded
facial view
mesial and distal prox contacts
mpc for all molars mn and mx are at junction of occlusal and mid third
dpc for mx first and second molar: mid third
dpc for mn first molar: junction of occlusal and middle third
dpc for mn second molar: mid third
facial view
which tooth has mesiodistal ridge?
mn first molar and mn second molar
mesiodistal ridge aka buccogingival ridge
number of roots
describe the ranking of root proportions
mx molars all have 3 roots, mx third molars can have up to 7/8 short roots
mn molars all have 2 roots mn third molar can have up to 8 short roots
mx first molar: P >MF> DF
mx second molar: P>MF=DF
mn first molar: M>D but distal is straighter
mn second molar: M>D but roots are parallel to each other
cross sectional root form of mx first molar and mn second molar
mx first molar: roughly ovoid at mid root area
mn second molar: distal root more nearly round
facial view
root trunk form
mx first molar: deep developmental groove on the facial surface
mx second molar: long and parallel
mx third molar: thin and often fused producing a long trunk, with furcation near the root apices
mn first molar: relatively short trunk
mn second molar: average height, taller than first molar w depression on root trunk
mn third molar: long trunk
facial aspect
observable feat of facial root apices
mx first molar: mesiofacial root apex blunter than distofacial root apex
mn first molar: mesial root apex is blunter than distal root apex
mn third molar: usually root apex is pointed and fused
facial view
extent of root separation
mx first molar: lateral separation of 2 facial roots nearly as wide as the MD dimension
mx second molar: DF root extends slightly distal to surface of crown
mn first molar: root apices widely separated, D root may extend distal to surface of crown
mn second molar: not widely separated
facial view
root angulation
mx first molar: MF curves distally
mx second molar: all have distal inclination
mx third molar: in apical third, all curves distally
mn first molar: curves distally
mn second molar: may both curve towards midline / distally
mn third molar: pointed and fused root
m/d
marginal ridge groove
mesial marginal groove marjority of the time present on mx first molar, second molar, mn first and second molar (with decreasing frequency)
distal marginal ridge occurs on half the time on** mx first molars** and occurs 38% of the time on mx second molars
frequency of having dmr decreases in this order: mx first molar, mn first molar, mx second molar, mn second molar
m/d view
cervical crown form
mesial for all molars: flat / concave
distal for mx first molar has small concavity near DF root, mx second molar usually flat, mn molars distal cervical crown form is flat or slightly convex
m/d view
location of mesial and distal prox contacts
mesial all facially located, ovoid for mx and mn molars
distal is located at the middle for mx molars, facial for mn first molar and middle for mx second molar
all ovoid
m/d view
root dimension
mx first molar: mesio facial root trunk bsae occupies 2/3 of FL dimension, DF root is hidden by MF root in the m/d view
mx second molar: MF root has wider FL dimension than DF root
mn first molar: Mesial root has larger FL dimension than D root
mn second molar: Mesial root has larger FL dimension than D root
m/d view
root apex alignment
mx first molar: mesiofacial root apex is aligned with mesio facial cusp tip
mx second molar: lingual root apex is aligned with Distolingual cusp tip
mn second molar: M root points apically
m/d view
root extension
mx first molar: lingual root extends beyond lingual crown surface, mesiofacial root extends facially to crown
mx second molar: mesiofacial and lingual root does not extend facial to the crown
occlusal view
fossae
mx: central, distal, mesial, distal triangular (distal triangular is minor and distal is major in mx first molar)
mn: central, mesial and distal
occlusal view
oblique ridge
mx first molar: between DF and D ridge of ML cusp
mx second molar: between DF and distal ridge of ML cusp
mx third molar: poorly developed, often absent
occlusal view
transverse ridge
mx first and second molar: between the MF and mesial ridge of ML cusp
mn first and second molar: between mesiofacial and mesio lingual, between distofacial and distolingual
occlusal aspect
developmental grooves
5 main in mx molars: central, facial, distal, oblique, lingual transverse
4 main in mx first molar: central, mesiofacial, distofacial, lingual, central groove forms M or W
3 main in mx second molar: facial, central and lingual, forming a cross and dividing crown into 4 near equal parts
mx third molar has many supplemental grooves
mn third molar has pit groove pattern, highly irregular and many supplemental grooves
