Morphology of Primary Teeth PDF

Morphology of Primary Teeth LECTURE 10 DR YASAR MANSOUR AMSU DeciduousS Teeth Primary Teeth Milk Teeth Decidere means to fall off These teeth are shed (fall off) and replaced by permanent teeth MILK Teeth due to their WHITE appearance 6 months -12 years Primary teeth G...

Morphology of Primary Teeth LECTURE 10 DR YASAR MANSOUR AMSU DeciduousS Teeth Primary Teeth Milk Teeth Decidere means to fall off These teeth are shed (fall off) and replaced by permanent teeth MILK Teeth due to their WHITE appearance 6 months -12 years Primary teeth GUIDE the permanent teeth Smaller in size Smaller crown height/ root length ratio Greater crown width/height ratio Relatively flat occlusal table Whiter in colour/ thinner dentine More bulging B & L cervical ridges Constricted cervix Occlusal aspect: constricted occlusal table Primary teeth Differences to Permanent: 1.The crowns of primary anterior teeth are wider mesiodistally compared to inciso gingival than are the permanent teeth. 2. The roots of primary anterior teeth are narrower and longer comparatively. 3. The roots of the primary molars are longer and more slender and flare more, extending out beyond projected outlines of the crowns. This flare allows more room between the roots for the development of permanent tooth crowns. 4. The cervical ridges of enamel of the anterior teeth are more prominent. 5. The crowns and roots of primary molars at their cervical portions are more slender mesiodistally. 6. The cervical ridges buccally on the primary molars are much more pronounced, especially on the maxillary and mandibular first molars. 7. The buccal and lingual surfaces of primary molars are flatter above the cervical curvatures than those of permanent molars; this narrows the occlusal surfaces. 8. The primary teeth are usually less pigmented and are whiter in appearance than the permanent teeth.  Roots highly slender and divergent, flare-out.  Small root trunk  Root narrow mesio-distally  Maxillary Central incisor  The only incisor with MD width larger crown height  Mesial and distal profiles overhang root profiles  No labial grooves, depressions or lobes  Cingulum  Bulging & more incisally located  May extend further toward the incisal edge – lingual ridge  Unmarked by pits or grooves  Marginal ridges are clearly evident  Maxillary Central incisor  Constricted cervix from all aspects  In proximal surfaces Cervical line is more convex incisally  Conical root with rounded apex  Maxillary lateral incisor Much smaller than central Mesial and Distal profiles are more in line with root profiles Distal incisal angle is more rounded Labial surface is more convex Mesiodistally Lingual fossa is deeper Marginal ridges more prominent Cervical line is similar to that of central Rounded from incisal aspect  Mandibular central incisor Bilaterally symmetrical 90 degree MI & DI angles Incisal margin is horizontal Prominent cingulum with lingual margin extending incisally Marginal ridges are less marked than those of maxillary incisors Lingual fossa is shallower Mandibular central incisor Occlusal: Labial surface is flat Mesio-distally Cervical line is similar to that of Maxillary incisors Root 3 times the height of the crown Narrow & conical with pointed apex  Mandibular lateral incisor  Incisal edge slopes distally  DI angle is rounded  D profile is more rounded  Greater crown height/MD ratio than mand. central  LL diameter > MD  Cingulum, fossa & MRs are similar to those of mandibular Central  Mandibular lateral incisor Root Narrow & conical Apex has D inclination D surface has narrow vertical depression  Maxillary canine  MD width > crown height  Well developed cusp  Labial or lingual views: diamond in shape  M & D profiles overhang root’s  HOCs are much near the cervix than in permanent  Labial & lingual cervical 1/3s are markedly convex  No labial ridge or depressions  Cervix constricted Mandibular canine  Crown height > MD width  Less cervically converging M & D profiles  Labial and lingual aspects: arrow in shape  No labial ridge or grooves  HOCs are much near the cervix than in permanent  LL diameter smaller than that of deciduous max. canine  Less prominent cingulum or Marginal ridges. shallower fossae than in deciduous max. canine  Maxillary 1st molar  Most atypical of all primary or permanent molars  Intermediate between a premolar & a molar  Smallest molar in all  Maxillary 1st molar  Buccal aspect  MD diameter much larger than crown height  M part is higher Occluso-Cervical than D M because it is more projected cervically onto the root area  Marked cervical constriction  Root  Very little root trunk  3 roots strongly divergent  L root is midway between the 2 B roots LINGUAL ASPECT 3 roots can be seen MB cusp can be seen  Maxillary 1st molar  Mesial aspect  Mesial marginal groove  B HOC is more cervically located than L  Buccal cervical ridge is more prominent in 1st molars than in 2nd  Roots B roots are straight & buccally directed L root is banana shaped with strong B curved apical 1/3 DISTAL Aspect Smaller/ narrower than Mesial aspect  Maxillary 1st molar  Occlusal aspect  Trapezoidal  M & D profiles are straight & slightly L convergent  B cusp larger than L  B triangular ridge more prominent than L  B groove separates DB cusp from MB  Central pit  Central groove  Transverse ridge (oblique ridge) between B groove & D MR  H-shaped pit/groove pattern  Central groove  Triangular supplemental grooves  M & D marginal grooves  Maxillary 2nd molar  Morphologically considered a model for the permanent 1st maxillary molar  Allows prediction of what the 1st maxillary molar will look like  This is called isomorphy  4 cusps  Cervical constriction  Cervical 1/3 bulging  Small root trunk  Roots thinner & divergent  Mandibular 1st molar  4-cusped tooth  Buccal aspect  2 cusp: MB & DB  M half larger than D half  M half projects more occlusally & occupies 2/3s of crown area  M profile is straight  D profile is curved and overhanging  CL inclines downward from D to M  Roots  2 divergent roots; M & D  M is longer  Mandibular 1st molar  Lingual aspect  2 cusps: ML & DL  ML cusp is conical & larger than DL  Outlines of B cusps are visible  CL is more straight & horizontal than that of the B aspect  Mandibular 1st molar  Mesial aspect  Buccal cervical ridge (BCR)  From MB cusp tip a straight incline to BCR  M MR is high & prominent  Mesial marginal groove separates M MR from ML cusp ridge  CL is convex occlusally & lower on the B end  Root  Extremely broad BL (sometimes as broad as the crown)  Mandibular 1st molar  Distal aspect  All 4 cusps & M root profiles are visible  B profile is less bulging than from mesial aspect  D MR is lower and less prominent than M MR  CL is more straight & horizontal than that of M aspect  Mandibular 1st molar  Occlusal aspect  it is rectangular  BL width is greater from M than D  MB cusp is the largest, followed by ML, DB & DL  M Transverse ridge, interrupted by  Central groove; extends from M pit to central pit  M pit  2 supplemental grooves; of which ML crosses M MR  Central pit  B& L grooves  Often a D pit  Mandibular 2nd molar  Morphologically considered a model for the permanent 1st mandibular molar  Allows prediction of what the 1st mandibular molar will look like  isomorphy  Cervical constriction  Cervical 1/3 bulging  Little root trunk  Roots thinner & divergent THANK YOU