Deciduous Posterior Teeth PDF

Deciduous Maxillary and Mandibular posterior teeth Dr. Sandeep Gupta Assistant Professor Maxillary st 1 molar  Most atypical of all primary or permanent molars  Intermediate between a premolar & a molar  Smallest molar in all but BL diameter Maxillary 1st molar  Cusps      Bicusped (only MB...

Deciduous Maxillary and Mandibular posterior teeth Dr. Sandeep Gupta Assistant Professor Maxillary st 1 molar  Most atypical of all primary or permanent molars  Intermediate between a premolar & a molar  Smallest molar in all but BL diameter Maxillary 1st molar  Cusps      Bicusped (only MB & ML cusp are present) A small DB cusp is frequently present on the D cusp ridge of the MB cusp Parastyle on the M ridge of MB cusp DL cusp rarely occurs In some cases, a nodular tubercle on the L portion of the D MR resembles a DL cusp Maxillary 1st molar  Buccal aspect     MD diameter >> crown height M part is higher OC than D 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 Maxillary st 1 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 Maxillary st 1 molar  Occlusal aspect          Trapezoidal M & D profiles are straight & slightly L convergent B cusp > 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 nd 2  Morphologically considered a model for the permanent 1st maxillary molar  Allows prediction of what the 1st maxillary molar will look like  This concordance is called isomorphy  Set traits     Cervical constriction Cervical 1/3 bulging Little root trunk Roots thinner & divergent molar Mandibular st 1  Molariform unlike max. 1st  4-cusped tooth  Buccal aspect        2 cusp: MB & DB M half > 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 molar Mandibular st 1  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 molar Mandibular st 1 molar  Mesial aspect        Buccal cervical ridge (BCR) From MB cusp tip a straight incline to BCR Transverse ridge connecting MB & ML 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) Frequently bifid apex Mandibular st 1 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 st 1 molar  Occlusal aspect       Without the BCR, it is rectangular BL width is grater 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 nd 2  Morphologically considered a model for the permanent 1st mandibular molar  Allows prediction of what the 1st mandibular molar will look like  This concordance is called isomorphy  Set traits     Cervical constriction Cervical 1/3 bulging Little root trunk Roots thinner & divergent molar Posterior Deciduous teeth - size & eruption Tooth Crown height MD crown BL crown diameter diameter Tooth length Age at eruption 54 or 64 5.1 mm 7.3 mm 8.5 mm 15.2 mm 12-16 mths 55 or 65 5.7 mm 8.2 mm 10.0 mm 17.5 mm 20-30 mm 84 or 74 6.0 mm 7.7 mm 7.0 mm 15.8 mm 12-16 mm 85 or 75 5.5 mm 9.9 mm 8.7 mm 18.8 mm 20-30 mm Thank You