Dental Anatomy: Permanent Mandibular 1st and 2nd Molars

#36, #46

According to FDI, identify tooth number for mandibular 1st molars

#37, #47

According to FDI, identify the tooth number for mandibular 2nd molars

mandibular 1st molar

what is the first permanent tooth to erupt

fissures

which area of the occlusal surface of permanent molars does the decay begin

fissure

narrow channel, groove, or crevice (รอยแตก) at the depth of a groove

2

how many transverse ridges does mandibular molars have?

distal half and mesial half

where are the transverse ridges located on the occlusal table of mandibular 1st molar?

1. MB and ML triangular ridges = 1 TR

2. DB and DL triangular ridges = 1 TR

3

how many fossae (shallow depression on tooth surface) does mandibular molars have

6-7 years

what is the eruption period for man. 1st molar?

*erupt during the same period as max. 1st molar

11-13 years

what is the eruption period for man. second molar?

hint: during the same period as max second molar (12-13)

5

man. 1st molar developed from how many lobes?

**for molars, lobes = cusps

4

man. 2nd molar developed from how many lobes?

**for molars, lobes = cusps

distobuccal groove and mesiobuccal groove

name all the grooves in mandibular 1st molar from the buccal view

distal, DB, MB, ML, DL

name all the cusps in mandibular 1st molar

root trunk

the distance from CEJ to the start of furcation

• longer mean that the furcation is more deeper below the gum line (makes it more difficult to access and clean with instruments)

*get longer from first molar to third molar

*mandibular has 2 roots. max. has 3 roots

pentagon

what geometric shape does the occlusal table of mandibular 1st molar resembles?

more cervical

fill in the blank: distal MR is ___ than the mesial MR

*applies to every posterior teeth except maxillary first premolar

v-shaped

what shape does the distal MR resembles (allows you to see all 5 cusps)

all

which cusps are visible from buccal view of man. first molar

only lingual cusps are visible

what cusps are visible from lingual view of man. first molar

only mesial cusps are visible

what is the outline form of cusps from mesial view of the mandibular 1st molar

only distal cusps

what cusps are visible from the distal view of the mandibular first molar

trapezoid

what is the geometric outline for facial/lingual view of the mandibular right 1st molar

rhomboid; pentagon (or hexagonal)

what is the geometric outline for the mesial/disal aspect and the occlusal aspect of the mandibular first molar?

junction of occlusal and middle third

what is the mesial contact area of the mandibular first molar

*same as distal but more bucally positioned

junction of occlusal and middle third

what is the distal contact area for the mandibular first molar

*same as mesial’s but more cervical

2

how many root does mandibular first molar have?

3

how many canals does mandibular first molar have?

• 2 canals is in the mesial root: mesiobuccal and mesiolingual

short

what is the length of the root trunk of mandibular first molar

widely

how are the roots spread in mandibular first molar

• mesial root is wider buccolingually (can be visible from distal view)

total 5; 3 horns under 3 buccal cusps; 2 pulp horns under 2 lingual cusps

what is the number of pulp horns and where is it under?

*the # of pulp horn = # of cusps

hypercementosis

unusual thickening of cementum on the roots

mandibular first molar

important points: in the mandibular arch, which tooth is the LARGEST

• it has the LARGEST mesiodistal dimensions

• mandibular molars (both) wider mesiodistally and faciolingually

  • all OTHERS (eg. max. molars, man/max premolars) are wider faciolingually than mesiodistally

zig zag

what is the pattern of the central groove on occlusal surface of mandibular 1st molar

• has 3 fossae

MB > ML => DL > DB > Distal

rank the cusps size of man. first molar from largesse —> smallest

lingual

Which cusps are longer, lingual or buccal?

buccal pit

Clinical alerts (man. molars): the mesiobuccal groove of the man. 1st molar and buccal groove of man 2nd molar is terminate in a buccal pit

—> which pit is at higher risk of developing caries?

difficult to place instruments subgingivally on the lingual side

Clinical alert (all mandibular molars): when viewed from mesial or distal, all mandibular molar crowns tilt lingually. How does this trait pose difficulty to certain oral care procedures.

4 cusps: ML, MB, DL, DB

How many cusps are in the mandibular second molar. Name it.

MB > ML => DL > DB

Rank the size of the cusps from largest to smallest

• 4 cusps are all nearly the same size

• same ranking as the first molar

mesial MR is more occlusal and distal MR is more cervical

marginal ridge heights of man 2nd molar

all

what cusps of are visible when viewed from buccal aspect of the man. second molar

• lingual cusps are taller than buccal *jum wai duay

only lingual cusps

what cusps are visible from lingual view of the mandibular second molar

only mesial cusps

from mesial view of the mandibular second molar, what cusps can be seen?

distal cusps and sometimes MB cusps

from distal view of the mandibular second molar, what cusps can be seen

trapezoid

what is the geometric outline for facial/lingial view of mandibular second molar?

rhomboidal

what is the geometric outline of the mandibular second molar when viewed from mesial or distal?

rectangular

what is the geometric outline for mandibular second molar when viewed from occlusal view

(molars are more squared)

junction of occlusal and middle third

what is the mesial contact area of the mandibular second molar

middle third

what is the distal contact area for mandibular second molar

2 roots and 3 canals

how many roots and canals does mandibular second molar have?

• root in mesial and distal

• 2 canals in mesial and 1 canal in disal

  • wider mesial root

roots of mandibular second molar are closer together, straighter, and more inclined toward the distal

what traits of the roots can be used to distinguish between mandibular second molar and first

cervical third

what is the height of contour for the buccal surface of the mandibular second molar

middle third

what is the lingual height of contour for the mandibular second molar

• tooth is very symmetrical

• occlusal pattern looks like a + sign

• central groove is striaght (unlike the first molar, zig zag)

• has more supplemental grooves than first molar

• all the cusps are nearly equal in size (ML and MB are slightly larger)

• it has a prominent buccal cervical ridge toward mesial

what are the main important points about the mandibular second molar that can be used to distinguish between first and second?

MB cusps of max. first molar; DL cusp of max. first molar

which tooth does the man. first molar occlude with and which part of the tooth is it?

max. second molar

which tooth does mandibular second molar occlude with

MB cusp of the maxillary first molar occludes with the MB grove of the mandibular 1st molar

what is class I molar occlusion (most common type)

MB cusp of the max firs molar is mesial to the MB groove of he mandibular 1st molar

what is class II molar occlusion (less common type)?

MB cusp of the maxillary first molar is distal to the MB groove of the mandibular 1st molar

what is class III occlusion (least common type)