الرحيم الرحمن الله بسم

Dental anatomy (29/4/10, 9.15a.m)

Important about final practical exam : at 19th May , 2010Has 2 part : -tooth carving and tooth identification : carv one of the teeth that we did in one & a ½ hour (open book) -practical multispot exam (only molars n deciduous teeth)

Maxillary deciduous canine

MD width> crown height : it shares this feature with deci. Max. central incisor

Labial or lingual views: diamond in shape : if we look at this tooth from occlusal view the tooth has diamond shape,also buccal & lingual view also the tooth looks like the shape of diamond. This makes the mesial and distal HOC located as a mid portion of the crown, this makes the mesial n distal sloping ridges of the cusp similarly to the mesial n distal outline ya3ni bringing the tooth to shape like diamond

M & D profiles overhang root’s outline ; located outside the root’s outline ,same with max. deci. Cent. Incisor

HOCs are much near the cervix than in permanent : permanent canine, located incisally, deciduous closer to cervical line nearly in the middle of the crown

Labial & lingual cervical 1/3s are markedly convex : labial n lingual are very convex and have very great constriction at the neck of tooth

MR prominence is related to race: Minimal in Caucasians

Prominent in MongoloidExample: mongoloid like Malaysian have more prominent marginal ridges Caucasian like Jordanian MR in max. deci canine are less prominent.

No labial ridges and depression : labial surface is flat. Don’t have any labial ridges or depression not like permanent max. canine

Mandibular Deciduous Canine

Crown height > MD width : opposite to max canine

Less cervically converging M & D profiles

Labial or lingual aspects: arrow in shape : looks like arrow when we look from labial aspect not like diamond, if its like diamond max. deci. canineNo labial ridge or grooves

HOCs are much near the cervix than in permanent : are closer to the cervix than the permanent canine, but it’s HOC is closer to the cusp than the dec. maxillary canine.

LL diameter < that of deciduous max. canine : LL width is wider than LL of deci. Max. canine

Less prominent cingulum or MRs & shallower fossae than in deciduous max. canine

Important : IN GENERAL, THE FEATURES THAT WE USE TO DISTINGUISH BETWEEN ALL ANTERIOR TEETH IS THE SAME FEATURES AS WE USED TO DISTINGUISH THE PARMANENT ANTERIOR TEETH.BUT IT IS DIFFERENT IN MOLARS.

MAXILLARY 1 ST DECIDUOUS MOLAR

Most atypical of all primary or permanent molars : it looks diff. n very atypical, doesn’t look like premolar or molar,

Intermediate between a premolar & a molar : it is someway intermediate between premolar and molar.

Smallest molar in all but BL diameter : every dimension is the smallest except the BL diameter. The BL diameter is not the smallest diameter here but the other aspect has the smallest diameter compared to other molars.

Cusps: looks like intermediate between premolar n molar

Bicusped (only MB & ML cusp are present)- we have only 2 major cusps : MB n ML, we often have DB n DL cusps but they are

small n not classified as cusp and they are very minimal

A small DB cusp is frequently present on the D cusp ridge of the MB cusp : not a proper cusp because they are very small so not classified as cusps located distal to MB cusp.

Parastyle on the M ridge of MB cusp - Mesiolingually we have from M ridge of MB cusp we have very minimal elevation called parastyle.ya3ni MB cusp has M ridge and D ridge, on M ridge we find parastyle and on D ridge we find the small cusp ya3ni DB cusp.

DL cusp rarely occurs : sometime we can find a very small elevation at Distal to ML cusp we can call it DL cusp but it’s not all the time present and rarely occur.

In some cases, a nodular tubercle on the L portion of the D MR resembles a DL cusp : sometime the Distal MR lingually starts to become tubercle, we can consider it as DL cusp. So a nodular tubercle on lingual portion of D MR can resemble DL cusp;In summary, this tooth have 2 major cusp *MB & ML cusps* , sometimes we can have a very small DB cusp and sometime we don’t have it . We can have DL cusp and sometime we don’t have DL cusp but also we can have nodular tubercle lingually to Distal marginal ridge that resemble the DL cusp.

Buccal aspect

- MD diameter >> crown height : MD diameter is Much2 greater than the crown height, ya3ni the width of crown is greater than height of the crown,

- M part is higher OCly than D because it is more projected cervically onto the root area : because the cervical line is more projected towards the root in the mesial ½ of crown this make the mesial part wider than D part of the crown from the buccal aspect.

- Marked cervical constriction : we have marked cervical constriction on this tooth

- Root : - Very little root trunk - 3 roots strongly divergent - Lingual root is midway between the 2 Buccal roots : we have MB, DB and L root

*Successor tooth that lives between the roots : permanent max. 1st premolar*

Mesial aspect

- Mesial marginal groove : we have mesial marginal ridge groove. Not clear here. - B HOC is more cervically located than L : B HOC is near the cervical of crown and lingual HOC usually located at the middle of the crown -Buccal cervical ridge is more prominent in 1st molars than in 2nd’

1st molar 2nd molar

- Roots: B roots are straight & buccally directed L root is banana shaped with strong B curved apical 1/3 : the apical 1/3 of the lingual root

is directed buccally

Occlusal aspect

o Trapezoidal : the occlusal shape is trapezoidalo M & D profiles are straight & slightly L convergento B cusp > L : Buccal cusp is bigger than the lingual cuspo Buccal triangular ridge more prominent than L : buccal one is bigger than lingual

oneo B groove separates DB cusp from MB : Buccal developmental groove separates

between MB n DB cusp. Not located at mid portion of crown MD.Located closer to the distal part of crown.why? because the MB cusp is bigger

o Central pit : B groove ends in mid portion of crown. At the end we have central pit

o Central groove : start from M pit to D pit o Transverse ridge or oblique ridge? between B groove & D MR : in max molars.

We know that oblique ridge runs from tip of ML cusp to tip of DB. This is the tip of ML cusp n we have ridge that runs towards the DB cusps. But because the shape is not oblique because the DB cusp is small. So to give name oblique is not appropriate because the ridge is not running obliquely.

o H-shaped pit/groove pattern : groove pattern is H shapedo we have Central grooveo We have Triangular supplemental grooves: at triangular fossao M & D marginal grooves : crossing the mesial and distal marginal ridges

Summary :

The tooth is atypical. Many students finds it’s hard to differentiates the teeth. Generally, is looks like premolar but it also looks like molar, but it has two big cusp and two small cusp. The 2 big cusp is located at the mesial side. MB n MD cusp. We have very small DB cusp and often we don’t have any DL cusp.

MAXILLARY 2ND MOLAR

o Morphologically considered a model for the permanent 1st maxillary molar : this tooth exactly looks like the that erupts behind it. What is the tooth? Permanent Max. 1st molar. To differentiates between them is to use only the set traits. The similarity btwn the anatomy is called isomorphy. The tooth look alike. but the tooth is not like the tooth that replace it.

o Allows prediction of what the 1st maxillary molar will look like.: example: if a 4years old child has problem at the 2nd deci. Molar, I will aspect there will be the same problem at the parm. 1st max molar when it is erupted.. and another example. If the 2nd deci max molar has a very prominent cusps of carebelli, the 1st parm. max molar will also have the same prominent cusps of carebelli.

o This concordance is called isomorphy

Set traitso Cervical constrictiono Cervical 1/3 bulgingo Little root trunko Roots thinner & divergent

Other than this the teeth(max. 2nd deci. Molar n max 1st parm. Molar) looks really alike

MANDIBULAR 1ST MOLAR

Molariform unlike max. 1st : looks more like molar rather than the max. 1st molar4-cusped tooth : it has 4 cusps. So it looks more like molar. But at max 1st it looks atypical(doesn’t look like premolar ot molar).

Buccal aspect

o 2 cusp: MB & DB : from buccal aspect we see 1 cusps : MB n DM cuspo M half > D half : Mesial half is bigger than the distal halfo M half projects more occlusally & occupies 2/3s of crown area o M profile is straight

D profile is curved and overhanging : but the mesial profile is inline with the root. But the distal profile is out of the line of the root and looks overhanging from the root.CL inclines downward from D to M : as we go from distal to mesial cervical line is incline downward. This make the crown higher at mesial than distal. because the cervical line is different. The cervical line goes downward as we go mesiallyRoots:

2 divergent roots; M & D rootM is longer : mesial root is longer than distal. And mesial rot is more straight

Lingual aspect

o We see 2 cusps: ML & DL cusps o ML cusp is conical & larger than DL, but the amount of differences between

lingual cusps is much smaller than difference with the buccal cuspso Outlines of B cusps are visible : we can see part of the buccal cuspo CL is more straight(not downward inclination like the buccal aspect) &

horizontal than that of the Buccal aspect

Mesial aspect

o Buccal cervical ridge (BCR): we can see the buccal cervical ridge form the mesial aspect which is very prominent

o From MB cusp tip a straight incline to BCR: the tip of the MB cusp to the buccal cervical ridge is straight incline

o Transverse ridge connecting MB & ML cuspso Mesial Marginal Ridge is high & prominento Mesial marginal groove separates Mesial Marginal Ridge from MesioLingual

cusp ridge o Cervical Line is convex occlusally and lower on the buccal end : at the buccal

end it is very low because it has to be consistenr to connect with the buccal which is very low

o Root : Extremely broad BL (sometimes as broad as the crown) :sometime the

root is as wide as the width of the crown

Frequently bifid apex : like spine process of 7th cervical vertebra

Distal aspect

o All 4 cusps & M root profiles are visible : we can see all the 4 cusps because the distal cusps is smaller than the mesial cusps

o B profile is less bulging than from mesial aspect : mesial aspect is much bulging as we see at the tooth

o Distal Marginal Ridge is lower and less prominent than Mesial Marginal Ridge

o CL is more straight & horizontal than that of Mesial aspect

Occlusal aspect

o Without the BCR, it is rectangular : the tooth is rectangular if we cancel the buccal cervical ridge (BCR)

o BL width is greater from M than D : because mesial part of the crown is greater than the distal part of the crown

o MB cusp is the largest, followed by ML, DB & DL : this is the order of difference in size between all the 4 cusps present.

o M Transverse groove, interrupted by central groove(extend from the mesial pit to the distal pit); M transverse groove extends from M pit to central pit interrupted by the central groove)

o M pit 2 supplemental grooves; of which Mesial Lingually crosses Mesial

Marginal Ridgeo Central pit : mesial pit is very close to the central pit but very far from the distal

pit because mesial ½ is greater than distal ½ .o B& L grooveso Often a Distal pit, sometime we have distal pit and sometime we dont

MANDIBULAR 2 ND MOLAR

o Morphologically considered a model for the permanent 1st mandibular molar : isomorphy to the permanent mand 1st molar, is a mirror of the tooth that erupt behind it which is the parmanent Mand. 1st molar. Example of Exam question (lab) : this tooth is isomorphy to which of the following, so u need to identify this tooth and know that it is isomorphy to the parmanent mand 1st molar that erupt behinds it.

o Allows prediction of what the 1st mandibular molar will look likeo This concordance is called isomorphy o Set traits (used to differentiates between permanent mand 1st molar and deciduous mand.

2md molar) : Cervical constriction Cervical 1/3 bulging Little root trunk Roots thinner & divergent