29 Questions
How many well-developed cusps does the mandibular first molar have?
Five
Which groove is related to the mesial buccal aspect of the mandibular first molar?
MBOG
What is the largest tooth in the mandibular arch?
Mandibular first molar
How many roots does the mandibular first molar typically have?
Two
Which cusp is not part of the mandibular first molar?
Oblique Cusp (OBC)
Which feature describes the curvature of the cervical line on the lingual aspect?
Uneven and waving
Which lingual cusp has the greatest width?
Mesiolingual cusp
Where does the lingual developmental groove extend to?
One third down the crown
How is the line of the cemento-enamel junction on the buccal surface described?
Curving regularly towards the root
Which aspect of the tooth is characterized by the crown being shorter distally than mesially?
Distal aspect
What is the characteristic of the mesial marginal ridge in relation to the cusps tips?
Located about 1mm below the level of the cusps tips
Where is the contact area located on the mesial outline of the crown?
At the junction of occlusal and middle third
Where is the distal cusp located in the buccolingual direction?
Buccal to the center
Which aspect of the crown is convex with the crest of curvature in the middle third?
Lingual
How are the two buccal cusps described?
Flat occlusally and convex
What is the profile of the buccal cusp from the mesial aspect?
Flat
Which cusp is the largest among the five well-developed cusps?
Mesiobuccal cusp
What percentage of the mesiodistal width do the two buccal cusps make together?
80%
What shape is the occlusal outline?
Rectangular
Which developmental groove separates the mesiobuccal cusp from the distobuccal cusp?
Mesiobuccal developmental groove
Which fossa is located distal to the mesial marginal ridge?
Mesial triangular fossa
What can be seen from the buccal aspect due to their length?
Mesiolingual and distolingual cusps tips
Which root is narrower bucco-lingually?
Distal root
Which developmental groove passes from the central pit to the buccal surface between the mesiobuccal and distobuccal cusps?
Mesiobuccal developmental groove
Which cusp ridge is labeled as DLCR in the occlusal aspect of the mandibular first molar?
Distolingual cusp ridge
What is the relationship between the central developmental groove and triangular fossae on the mandibular first molar?
It passes from the central pit to the mesial and distal triangular fossae.
Which labeled part represents the central developmental groove in the occlusal aspect diagram of the mandibular first molar?
CDG
In which direction does the distobuccal developmental groove pass?
Distally between the distobuccal and distal cusps.
Where is the lingual developmental groove located in relation to the cusps?
Between the mesiolingual and distolingual cusps
Study Notes
Distal Aspect
- Distal aspect is a reverse outline of the mesial
- Crown is shorter distally than mesially
- Distal cusp is located buccal to the center buccolingually
- Distal marginal ridge is short and curves cervically
- Cervical line is irregular
- Distal root is narrower bucco-lingually than the mesial root
Occlusal Aspect
- Occlusal outline is rectangular in shape, larger mesiodistally than buccolingually
- Five well-developed cusps: mesiobuccal, mesiolingual, distolingual, distobuccal, and distal cusp (smallest)
- Distal contact area is located at the distal cusp
- Three fossae: central, mesial triangular, and distal triangular fossae
Buccal Aspect
- Cemento-enamel junction curves regularly towards the root
- Mesial outline of crown is straight from cervix to contact area
- Distal outline of crown is similar to mesial outline with a lower crest of curvature
- Two buccal cusps and distal cusp are completely outlined from this aspect
- Two buccal cusps are convex, not pointed, while distal cusp is rounded
- Two buccal developmental grooves: mesiobuccal and distobuccal
Mandibular First Molars
- Largest tooth in the mandibular arch
- Has five well-developed cusps: two buccal, two lingual, and distal cusp
- Buccal surface is inclined lingually with two buccal developmental grooves
- Normally has two well-developed roots
Anatomy of Mandibular First Molar
- Distal buccal groove (DBOG)
- Distal root (DR)
- Distal lingual cusp (DLC)
- Distal cusp (DC)
- Oblique cusp (OBC)
- Mesial lingual cusp (MLC)
- Mesial buccal cusp (MBC)
- Mesial buccal groove (MBOG)
- Central lobe (CL)
- Mesial root (MR)
Developmental Grooves
- Central developmental groove passes from central pit to mesial and distal triangular fossae
- Mesiobuccal developmental groove passes from central pit to buccal surface between mesiobuccal and distobuccal cusps
- Distobuccal developmental groove passes from central groove in distal direction between distobuccal and distal cusps
- Lingual developmental groove passes lingually between mesiolingual and distolingual cusps
Occlusal Aspect Figures
- Figure 69: Mandibular first molar - occlusal aspect
- Distobuccal cusp ridge (DBCR)
- Distobuccal developmental groove (DBDG)
- Distal cusp ridge (DCR)
- Distal triangular fossa (DTF)
- Distolingual cusp ridge (DLCR)
- Lingual developmental groove (LDG)
- Mesiolingual cusp ridge (MLCR)
- Mesial triangular fossa (MTF)
- Supplemental groove (SG)
- Mesiobuccal cusp ridge (MBCR)
- Mesiobuccal developmental groove (NBDCG)
- Figure 70: Mandibular first molar - occlusal aspect
- Central pit (CP)
- Distal marginal ridge (DMR)
- Distal pit (DP)
- Central developmental groove (CDG)
- Mesial pit (MP)
- Mesial marginal ridge (MMR)
Lingual Aspect
- Lingual aspect has a reverse outline to the buccal aspect
- Cervical line is curved and uneven
- Mesiolingual cusp is wider than the distolingual cusp
- Lingual developmental groove separates the two lingual cusps
Mesial Aspect
- Cervical line is curved and higher lingually than buccally
- Buccal outline of crown is convex from cervical line to crest of curvature
- Lingual outline of crown is convex with crest of curvature in the middle third
- Mesial marginal ridge is located below the level of the cusp tips
A quiz about the morphology of molars, covering the distal and occlusal aspects.
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