Identification of Natural Teeth PDF

Faculty Of Dental Medicine Oral Biology Department Lecture: (Identification of natural teeth) Ass. Prof (Fatma Adel Saad)  By Dr. Fatma Adel Saad Associate Professor of Oral Biology Natural Teeth Identification  Permanent incisors Up...

Faculty Of Dental Medicine Oral Biology Department Lecture: (Identification of natural teeth) Ass. Prof (Fatma Adel Saad)  By Dr. Fatma Adel Saad Associate Professor of Oral Biology Natural Teeth Identification  Permanent incisors Upper incisors Lower incisors * Width (MD) >Thickness (BL) *Thickness (BL) > Width (MD) * No lingual inclination * Lingual inclination * No lingual inclination from proximal There is lingual inclination from aspect. proximal aspect. * Upper central > Upper lateral * Lower lateral > Lower central  Upper central incisor Upper lateral incisor *Very wide. *Narrower. *Straight incisal edge. *Curved incisal edge. *M.I angle is sharp but D.I angle is *M.I & D.I angles are rounded. rounded. *Sometimes palatal pit could be *No palatal pit. present. * Root apex is blunt and centralized. *Root apex is pointed and distally curved.  Lower central incisor Lower lateral incisor *The crown is twisted distolingually. *The incisal ridge is at right angles to the labiolingual axis. *The incisal ridge is tilted distally. *The cingulum is centralized. *The cingulum is shifted distally.  General differences between permanent & deciduous anteriors Deciduous teeth are smaller , whiter, constricted cervix, enamel bulge close to cervical line, bulbous crown, Shallow elevations & depressions. Apart from these general differences  deciduous anteriors are similar to their permanent successors except for the following:  Deciduous incisors Upper deciduous incisors * Upper central > Upper lateral Deciduous Permanent Deciduous Permanent 2 1 *Thicker in relation to crown length. *Wider in relation to crown length. *Prominent labial & lingual crests of curvatures. *No mamelons.  Lower deciduous incisors * Lower lateral > Lower central Deciduous Permanent Deciduous Permanent *Incisally; Incisal ridge is centered labiolingually  no lingual inclination. *Proximally; Incisal edge is centered M M D D on the root not lingually inclined as in permanent ones. *In lower B; incisal edge is inclined distally & cingulum is shifted distally.  Permanent canines Upper canine Lower canine M M D D *The crown appears wider *The crown appears and shorter. narrower and longer. *The distal slope reaches *The distal slope does not half the crown length. reach half the crown length.  Deciduous canines Upper canine Lower canine Deciduous Permanent Deciduous Permanent M D M D M D M D *Mesial slope of the cusp is longer than *Distal slope of the cusp is longer than the distal slope. the mesial slope. *Lingually, there is a tubercle extends *Lingually, there is a tubercle extends from cingulum lingual ridge. from cingulum lingual ridge..  Premolars Upper premolars Lower premolars There is no lingual inclination. There is lingual inclination.  Upper first premolar Upper second premolar *The occlusal table is hexagonal. *The occlusal table is oval. *There is long central developmental *There is short central developmental groove, thin marginal ridges, mesial groove, thick marginal ridges, no mesial marginal developmental groove. marginal developmental groove. * No supplemental grooves. * There are supplemental grooves. *There is canine fossa in the mesial *There is no canine fossa in the mesial aspect. aspect. *80 % bi-rooted and 20 % single rooted. *15 % bi-rooted and 85 % single rooted.  Lower first premolar Lower second premolar 2 cusp type 3 cusp type B B L ML DL H type U type *Occlusal table is *Occlusal table is *The occlusal table is diamond. square. rounded. *there is no *there is transverse ridge. *there is transverse transverse ridge. ridge. *From proximal aspect, snake head appearance. *Y shape *H or U shape *two triangular fossae & pits  developmental developmental snake eyes. grooves. groove. *There is MLDG. *There is no MLDG. *There is no MLDG.  Permanent molars Upper molars Lower molars *Occlusal surface is either rhomboidal *Occlusal surface is either hexagonal or heart shape. or rectangular. * Thickness > width. *Width > thickness. *There is no lingual inclination. *There is lingual inclination. * 3 Roots. * 2 Roots IN All Aspects  Roots As we go Posteriorly -Longer root trunk (no definite trunk palatal) -More distally inclined roots & parallel -Less divergent  more closer  fused in 8 Upper 6 Upper 7 Upper 8 M D DB MB MB DB MB DB  Upper molars MB MB MB DL DL DL Occlusal surface is rhomboidal 6 8 (Always found) 7 Usually found) * More DL convergence *DL convergence *DB convergence *MB cusp gets larger as we go *MB cusp gets larger as *There is no lingual convergence. posterior. we go posterior. *DL cusp get smaller as *DL cusp get smaller as *Tubercle of Carabelli on ML cusp. We go posterior. we go posterior. *Many supplemental grooves. *Some supplemental grooves *NO distal contact area, *By exclusion. *It has widely divergent roots. *Fused roots. N.B. Contact area is a small flat area that may be shiny, caries, white or brown in color.  Upper molars 8 7 (Usually found) (May be found) Occlusal surface is heart shape (DL convergence) *DL cusp is missed with NO LDG *DL cusp is missed with NO LDG *One large lingual cusp *One large lingual cusp *No oblique ridge *With oblique ridge *Many supplemental grooves. *Some supplemental grooves. *No distal contact area. *Fused roots. * By exclusion N.B. Contact area is a small flat area that may be shiny, caries, white or brown in color.  Lower molars Occlusal surface is hexagonal (Distal & lingual convergence) 6 8 * By exclusion *Many supplemental grooves. *There is mesial contact area but no distal contact area, sometimes both are missing. *Fused roots. N.B. Contact area is a small flat area that may be shiny, caries, white or brown in color.  Lower molars Occlusal surface is rectangular (Distal & lingual convergence) 7 8 *Many supplemental grooves. * By exclusion *There is mesial contact area but no distal contact area. *Fused roots. N.B. Contact area is a small flat area that may be shiny, caries, white or brown in color.  General differences between permanent & deciduous molars Deciduous teeth are smaller , whiter, constricted cervix, enamel bulge close to cervical line, bulbous crown, Mesiobuccal cervical ridge, constricted occlusal table, shallow elevations & depressions. Apart from these general differences  deciduous molars are having the following charcteristics:  Deciduous molars Upper molars Lower molars * Thickness > width. *Width > thickness. *There is no lingual inclination. *There is lingual inclination. *3 Roots. *2 Roots. Thin, widely divergent & little Thin, widely divergent & little or no root trunk or no root trunk  Upper and lower first deciduous molars D D *There is MB cervical ridge. *There is MB cervical ridge. *Has the criteria of upper molars *Has the criteria of lower molars.  Upper and lower second deciduous molars E E *Similar to 6. *Similar to 6. *Has the criteria of upper molars *Has the criteria of lower molars.