Functional_anatomy_of_teeth_part_2_lower_anteriors_Dr_HE_Copy.pptx

Functional anatomy of teeth (Lec2) Dr. Hadeer  Mandibular incisors -They are smaller than maxillary incisors. -Mandibular central is smaller than mandibular lateral which is the reverse of the situation in maxillary 1&2. -The width is smaller than the thickness. -T...

Functional anatomy of teeth (Lec2) Dr. Hadeer  Mandibular incisors -They are smaller than maxillary incisors. -Mandibular central is smaller than mandibular lateral which is the reverse of the situation in maxillary 1&2. -The width is smaller than the thickness. -The mamelons worn off soon after eruption. -The incisal ridges are inclined lingually to the root axis.  Mandibular incisors -They are smaller than maxillary incisors. -Mandibular central is smaller than mandibular lateral which is the reverse of the situation in maxillary 1&2. -Theislingual -The width inclination smaller than the thickness. is a characteristic -The mamelons feature worn off soon after eruption.of lower teeth (this lingual inclination -The incisal ridges are inclined lingually to the root axis. facilitates proper occlusion).  Mandibular incisors -They are smaller than maxillary incisors. -Mandibular central is smaller than mandibular lateral which is the reverse of the situation in maxillary 1&2. -Theislingual -The width inclination smaller than the thickness. is a characteristic -The mamelons feature worn off soon after eruption.of lower teeth (this lingual inclination -The incisal ridges are inclined lingually to the root axis. facilitates proper occlusion). lower central incisor tooth  lower central incisor tooth -Its crown has fan shaped appearance. -It’s the most symmetrical tooth in the permanent dentition. -It’s the smallest tooth in the permanent dentition.  lower central incisor tooth Geometric outline of the crown : -Facial and lingual aspects have trapezoidal outline with the smallest side cervically. -Mesial and distal aspects have triangular outline with the apex incisally and the base cervically. -Incisal aspect is oval. Note:  lower central incisor tooth Facial and lingual outlines of the crown :  Central : - Sharp mesio-incisal angle and disto-incisal angle D M - Incisal edge is straight and perpendicular to the long axis of the tooth.  Lateral : - Sharp mesio-incisal angle , Rounded disto-incisal D angle - Incisal edge is straight and slope downward in a  lower central incisor tooth Surface anatomy of the crown : Labial aspect: Elevations: The crown surface is smooth and convex with maximum convexity at the cervical third (CERVICAL RIDGE) Depressions: shallow developmental grooves could be seen separating mamelons in newly erupted teeth.  lower central incisor tooth Surface anatomy of the crown : 5 Lingual aspect: 1 3 2 Elevations: -Marginal ridges (Mesial and distal) 4 -Cingulum(Cervically) (Centered) -Incisal ridge. Note : The elevations are poorly developed than upper central Depressions: -Lingual fossa which is shallow M D.  lower central incisor tooth Surface anatomy of the crown : Proximal (mesial and distal) aspects: -Labial outline: convex with the maximum convexity at the cervical third (cervical ridge). -Lingual outline: (CONCAVO-CONVEX) convex incisally (Incisal ridge) concave at the middle third (lingual fossa)  lower central incisor tooth Surface anatomy of the crown : Proximal (mesial and distal) aspects: -Cervical outline : (cervical line ) Curves incisally Note : The curvature of cervical lines in all teeth distally is less than mesially.The height of curvature decreased also from upper teeth to lower teeth.  lower central incisor tooth Surface anatomy of the crown : Proximal (mesial and distal) aspects: -Contact areas: Both mesial and distal contact areas are at the Incisal one third  lower central incisor tooth Surface anatomy of the crown : Incisal aspect: - The labiolingual dimension (width) is greater than The mesio-distal dimension (thickness). - The cingulum is centered. - The crown is taperd lingually(Lingual convergence) Note: The elevations and depressions in the crown lingually and labially appeared from  Lower central incisor tooth Outlines of the root: -Single root -The apex is pointed and curved distally. Note: - The root of lower lateral incisor is the same but longer.  Lower central incisor tooth Outlines of the root: Note -The root surface has mesial and distal developmental depressions. Note : Lower laterals have the same depressions lower lateral incisor tooth  lower lateral incisor tooth -It’s very similar to lower central incisor but slightly larger.  lower lateral incisor tooth Geometric outline of the crown Note: : Crown is twisted Disto- lingually to allow the incisal ridge to follow the curve of dental arch(Characteristic feature). Oval  lower lateral incisor tooth Facial and lingual outlines of the crown :  Central : - Sharp mesio-incisal angle and disto-incisal D M angle Incisal edge is straight and perpendicular to  - Lateral : the long axis of the tooth. - Sharp mesio-incisal angle , Rounded disto- incisal angle - Incisal edge is straight and slope downward D in a distal direction.  lower lateral incisor tooth Surface anatomy of the crown : Lingual aspect: Elevations: -Marginal ridges (Mesial and distal) Note : The mesial marginal ridge is longer than distal marginal ridge -Cingulum(Cervically) (shifted distally) -Incisal ridge. Depressions: - is the same  Comparison bt lower permanent central and lateral incisors CHARACTERISTICS MANDIBULAR PERMANENT CENTRAL MANDIBULAR PERMANENT LATERAL INCISOR INCISOR Tooth nomenclature Zsigmondy/Palmer Right 1 ; Left 1 Right 2 ; Left2 system Dimensions Smallest tooth in permanent dentition Slightly larger than the mandibular central incisor in all dimensions CROWN Labial aspect Symmetry Crown bilaterally symmetrical Asymmetrical bilaterally Mesial profile Both mesial and distal Straight Distal profile outlines are straight Slightly curved Proximal contacts Both contact areas are at same level, Not exactly same level. Though still in incisal very near to incisal ridge third are cervically located than those of central incisors Mesial Incisal third Incisal third Distal Incisal third Incisal third but cervical to the mesial contact CHARACTERISTICS MANDIBULAR PERMANENT CENTRAL MANDIBULAR PERMANENT LATERAL INCISOR INCISOR Incisal angle Mesioincisal angle Sharp and right angled Sharp and right angled Distoincisal angle Sharp and right angled Slightly rounded Incisal ridge Straight Slopes downwards distally Lingual aspect No major differences seen except that the lateral incisor is wider Marginal ridge Ill-defined Well defined Incisal ridge/edge Located lingual to the vertical root axis Lingual to vertical root axis Proximal surface (Mesial and distal views) CHARACTERISTICS MANDIBULAR PERMANENT CENTRAL MANDIBULAR PERMANENT LATERAL INCISOR Incisal aspect INCISOR It is mainly from incisal view that the mandibular central and lateral incisors can be differentiated from one another Incisal ridge/edge Is at right angles to the labiolingual Is at an angle to the labiolingual bisecting line. It bisecting line is twisted distolingually on the root base to conform to the mandibular arch curvature Cingulum Cingulum is centered mesiodistally shifted distally ROOT Number Single Single Size Shorter and smaller Longer and larger Developmental On both mesial and distal On both mesial and distal surfaces depression surfaces Deeper on distal surface Pulp canals Usually 1, 2 possible 1 lower canine tooth  lower canine tooth Geometric outline: Trapezoid(L) Triangular(M-D) Trapezoid (P) Oval (I)  Comparison bt Upper and Lower permanent Canines CHARACTERISTICS MAXILLARY PERMANENT CANINE MANDIBULAR PERMANENT CANINE General features Lobes Develops from 4 lobes middle From 4 lobes labial lobe is very well-developed Middle labial lobe is not so well- into labial ridge developed So, the labial ridge is less prominent General size Longest tooth of all 2nd longest tooth Bulkier crown Crown longer by 1 mm Longest root of all Root shorter by 1 mm Contd... CROWN Labial aspect Mesiodistal width Crown is broader and shorter Crown is longer and narrower mesiodistally Labial surface The labial surface more convex Labial surface convex The cusp tip Long and pointed Shorter and flatter ( Less pointed ) Cusp slopes Mesial cusp slope is shorter than distal The same one in both Labial ridge Labial ridge is very prominent Labial ridge is less prominent Crown tilt Crown is upright on root base From this aspect crown appears to be tilted distally on root base Contact area Mesial Mesial is at the junction of incisal and in the incisal 1/3 near mesioincisal Distal middle 3rd Distal is at center of middle angle 3rd at the junction of incisal and middle 3rd Contd... Lingual aspect Cingulum Centered.The cingulum is large, Centered.The cingulum is smooth very well developed; sometimes and poorly developed may even be pointed like a small cusp Marginal ridges Marginal ridges are strongly Marginal ridges are thin and less developed developed MMR is longer than DMR Lingual fossa Lingual fossa is more concave Lingual fossa is shallow and smooth Lingual ridge Lingual ridge is more prominent Lingual ridge is less prominent (extends from the cusp tip to the (Restricted to the incisal 1/3) cingulum) Contd... Mesial aspect Crown bulk Crown is more bulky labiolingually Crown appears less bulkier Labial outline More convex due to prominent labial Labial outline is less convex ridge Lingual outline Lingual outline is more convex near Lingual outline shows curvatures of cingulum lesser degree Position of cusp tip Cusp tip is labial to the vertical root axis Cusp tip is lingually placed to the (or centeralized on the long axis of the vertical root axis root) Contd... Incisal edge Incisal edge is lingually sloping Incisal edge is labially sloping CHARACTERISTICS MAXILLARY PERMANENT CANINE MANDIBULAR PERMANENT CANINE Distal aspect Cervical line Less curved Less curved Incisal aspect Dimension Labiolingual dimension is greater among Crown is less bulkier labiolingually all the anteriors Crown symmetry Crown appears asymmetrical with the Crown is symmetrical mesial half of the crown bigger than the distal half Cusp tip Cusp tip is labial to the center of crown Cusp tip is in the center or lingually (Labiolingually)and mesial to the center placed (Labiolingually)And mesial to (Mesiodistally) the center (Mesiodistally) - MESIO-LABIALLY -MESIO-LINGUALLY CHARACTERISTICS MAXILLARY PERMANENT CANINE MANDIBULAR PERMANENT CANINE ROOT Number Single conical root and is never Usually single root may be bifurcated bifurcated Size Longest root Root is 1–2 mm shorter Lingual surface is narrower than Lingual surface is much more narrower labial about ½ of the width of labial surface Apex curvature Apex is pointed Apex is slightly pointed Apical 3rd of the root shows distal Root is usually straight sometimes has curvature distal curvature Developmental Developmental depression on distal Developmental depression on distal depression surface of root is more deeper surface is more pronounced (lower canine deeper than upper canine) Pulp canals Single canal Single canal  Upper and lower canine teeth Outlines of the root: -Single root Note -The root surface is broad bucco-lingual -The root is long , slender(very thin) ,conical with longitudinal depression -The apex is pointed (Developmental and curved distally depression) -The depression is shallower mesially than distally of the same tooth. -Shallower in upper canine than lower canine Test your self  Test your self 1- a- This photo shows ………. Surface of …….. b- Which one is the distal surface (A-B)? And why? 5 6 1 3 2 2- Label the following photo: A 4 B 1-……….. 2-……….. 3-………… 4-………… 5-…………. 6-………….  Test your self : 3- a-This photo shows ………. Surface of …….. A B b-Mention elevations and depressions present on this surface. c- Which one is the distal surface (A-B) ? And Why ? 4- Give reason : The crown of lower lateral is twisted disto lingually.  Test your self : 5- a-This photo shows ………. Surface of …….. A B b-Mention elevations and depressions present on this surface. c- Which one is the distal surface (A-B) ? And Why ? Thank you !