Surface Anatomy of Permanent Teeth PDF

Surface anatomy of permanent teeth Anterior teeth They are divided into: Incisors Canines and  Incisors There are four maxillary incisors and four mandibular incisors. ♥ Two central incisors contact with each other in the midline (m...

Surface anatomy of permanent teeth Anterior teeth They are divided into: Incisors Canines and  Incisors There are four maxillary incisors and four mandibular incisors. ♥ Two central incisors contact with each other in the midline (mesially) and with the lateral incisors distally. ♥ Two lateral incisors contact with the central incisor mesially and with the canine distally.  Number of lobes: All anterior teeth (incisors and canines) formed of four lobes, three labially and one lingually. 4 4 1 2 3 1 2 3  Chronology Enamel organ appearance. 5 m.i.u Beginning of calcification. 3-4 m. except 2 10-12m  Crown completed. 4-5y Eruption. 6-8 y Root completed. 10-12y  Beginning Crown Eruption Root of calc. completed completed (month) 1 3-4 7 1 6 2 10-12 8 2 3-4 7 3 11 4-5 3 9  For easy teeth description We have to speak about :  Geometric outline of the crown.  Outlines of the crown and root. Convex Concave Surface anatomy of the crown and root (anatomical landmarks). All teeth have 5 aspects 1 Facial Lingual Mesial Distal Incisal  1 Maxillary central incisor is the first tooth from the midline. The two upper centrals are the widest of all the incisors. The crown is the longest of all human teeth.  Geometric outline of the crown Facial and lingual aspects have trapezoidal out line. Smallest uneven side cervically.  Facial and lingual outlines of the crown Cervical outline (convex root wise) Mesial outline Distal outline (convex) (more convex) D M At the junction In the I 1\ 3. of M& I 1\ 3. Rounded Sharp mesioincisal distoincisal angle Incisal (straight and may angle have mamelons) When?  Outlines of the root  The mesial and distal outline of the root tapered to a blunt apex The apex is centralized on the long axis so extraction could be done by rotation movement  Surface anatomy of the crown and root. 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. The root surface is smooth and convex  Lingual aspect Elevations: Marginal ridges (mesial and distal) cingulum Cingulum (cervically) Incisal ridge Depressions: Lingual fossa Incisal ridge Marginal ridges ☺You have to notice that the lingual surface of all teeth is smaller in size than the labial due to the lingual convergence. This convergence of the teeth is to accommodate the larger arch size facially than lingually  Geometric outline of the crown Proximal (mesial and distal) aspects have triangular outline Base cervically. Apex incisally.  Mesial and distal Outlines It’s Triangular and formed of Labial outline: convex with maximum convexity at the cervical third which represent ……. Lingual outline: convex incisally which represent……. Concave at the middle which represent… Convex cervically which represent……… Cervical outline: Curves incisally.  Outlines of the root The outlines tapered from the cervical line to a blunt rounded apex  M D The crown has smooth convex proximal surfaces. Contact areas: Near the junction of I & Near the MI angle. M 1\ 3. Cervical line: The curvature is Curved incisally. shallower than mesially. Roots They have convex smooth surfaces.  Incisal aspect Outline and surface anatomy  The outline is triangular in shape. The base is placed labially and apex lingually. The mesiodistal dimension (width) is greater than the labiolingual The crown is tapered lingually. Note: The elevations and depressions in the crown lingually and labially appeared in this aspect. Lingual fossa Identify the tooth, the aspect and the anatomical landmark. Maxillary lateral incisor Lingual Mesial Distal Labial Incisal  1 2 *Its crown is the broadest of the *Its crown is smaller in all anterior teeth dimensions than 1 except its *It is the longest tooth of all root is longer human teeth 1 2 Labial aspect D M D M sharp M I angle. rounded M I angle. rounded D I angle. more rounded D I angle. Incisal outline Straight Rounded (curved) 1 2 MCA-----in incisal1/3 near the MCA---- at the junction of mesio-incisal angle Incisal and middle 1/3s DCA-----at the junction of incisal and middle 1/3s DCA-----in the center of middle 1/3. 1 2 Root is longer, narrower and has Root has cone shape with developmental depression on its mesial surface Blunt apex -Root tapers evenly to apical 1/3 then curve distally with a pointed apex.  Lingual aspect Elevations are well developed Marginal Cingulum ridges Depressions: Incisal ridge Lingual fossa, more concave and circumscribed Note: (characteristic feature) Lingual pit could be found in the 2 and should notice that all elevations are well developed than 1 Identify the tooth, the aspects and tell FOUR differences between them. Answer A- Upper P. central incisor. B- Upper P.lateral incisor Lingual aspect 1- Size. 2- The elevations and depressions 3- The incisal angles. A B 4- The root.  1 2 Mesial aspect Lb Lg Lb Lg The crown long and thick Shorter and thinner. labiolingually. The mesial surface is flat The surface is flatter. Contact area at I 1\3 near Near or at the junction of the M I angle. I & M 1\3  1 2 Distal aspect C.A. at the junction of I & In the center of the M 1\3 crown.  Incisal aspect 1 2 *Geometric outline---- Geometric outline--- triangular rounded or oval *M-D> Lab-Ling *M-D = Lab-Ling *The cingulum is shifted *The cingulum is centered distally When palatal pit is present; it is located in the depth of the lingual fossa ☻Pulp cavity of Upper central incisor ►Mesio-distal section - The pulp chamber is wide conforming the shape of the crown. - It presents three pulp horns corresponding to the three Trapezoidal mamelons. Triangular - The root canal tapers towards the apex. ►Labio-lingual section - The pulp chamber - The root canal tapers gradually pointed incisally, then as it traverse the root ending in a follows the increase in constriction at the apex (the the crown dimension apical foramen). cervically. Pulp Cavity Pulp is circular Pulp Cavity  ☻Pulp cavity of upper lateral incisor  Is similar but smaller than that of central incisor.  It consists of a single root canal and a pulp chamber.  Malformations Of The Upper Permanent Lateral Incisor 3 1 Missing lateral Peg-shaped incisor. lateral incisor.  Mandibular incisors *They are smaller than maxillary incisors. * * *1 is smaller than 2 which is the reverse Of the situation in 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 central incisor Labial Lingual Mesial Distal Incisal 2 Labial Lingual Mesial Distal Incisal  Mandibular central incisor Is the first mandibular tooth from the midline. It is the smallest tooth in the permanent dentition. *Its crown has fan shaped appearance It is the most symmetrical tooth in the permanent dentition. Mandibular lateral incisor It’s very similar to lower central incisor, but slightly larger.  Geometric outline of the crown Facial and lingual aspects have trapezoid out line. Smallest uneven side cervically.  Facial and lingual outlines of the crown 1 2 D M D M Mesial & distal outlines are straight tapering evenly to the narrow cervix. Its crown has fan shaped Its crown has also fan shaped appearance appearance It is more symmetrical Its crown is less symmetrical Incisal edge is straight and * Theincisal edge is straight and perpendicular to the long axis slop downward in a distal of the tooth. direction.  1 2 D M D M *Mesio-incisal angle----sharp *Mesio-incisal angle----sharp *Disto-incisal angle-----sharp *Disto-incisal angle-----rounded MCA &DCA-----at the same *DCA is more cervically than level (incisal to the junction of MCA incisal and middle 1/3s )  Outlines of the root 1 2  *The root of lower central incisor tapers toward the pointed apex  -Its apical third curved distally  -It has mesial and distal developmental depressions  The root of lower lateral incisor Is the same but longer  Surface anatomy of the crown and root. Labial aspect of 1&2 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 errupted teeth. The root surface is smooth and convex  Lingual aspect Incisal ridge Marginal Elevations: ridges Marginal ridges (mesial and distal) Cingulum (cervically) Cingulum Incisal ridge Depressions: Lingual fossa, shallow  1 Lingual aspect 2 The fossae appear shallower in the lower teeth. The elevations (cingulum, *The same but the MMR is marginal ridges and incisal longer than DMR as the ridge are poorly developed mesial outline is longer than than in 1 the distal one. The cingulum is centered *The cingulum is deviated distal to the center of the lingual surface.  Geometric outline of the crown Proximal (mesial and distal) aspects have triangular outline Apex incisally. Base cervically.  Mesial and distal Outlines It’s Triangular and formed of Labial outline: convex with maximum convixity at the cervical third which represent ……. Lingual outline: convex incisally which represent……. Concave at the middle which represent… Convex cervically which represent……… Cervical outline: Curves incisally. Note: The convexity of labial and lingual outlines are well developed in the upper teeth than lower teeth. Why?  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 The lingual inclination is a characteristic feature of lower teeth The incisal ridge is lingual to the root axis This lingual inclination facilitates proper occlusion.  2 Mesial aspect distal aspect Contact area at the I 1\3 Contact area more cervically to contact the lower canine Note: the distal aspect is shorter than mesially due to distal tilting of the incisal ridge Roots Root surface showed longitudinal developmental depression which is deeper distally than mesially.  Incisal aspect The outline is diamond in shape. The labiolingual (thickness) is greater than the mesiodistal dimension. The incisal ridge in 1 is at right angles to a line bisecting the crown labiolingually. The cingulum is centered. The crown is tapered lingually. The incisal edge is not at right angle to the line bisecting the crown Lab- Ling The cingulum is displaced distally  Crown is twisted disto-lingually on its root to allow the incisal ridge to follow the curve of dental arch (characteristic feature)  Beginning Crown Eruption Root of calc. completed completed (month) 1 3-4m 7 1 6 2 10-12m 8 2 3-4m 7 3 11 4-5m 3 9  Convex out lines Straight outlines Incisal edge straight curved Tilted Straight Incisal angles Sharp MI, Sharp MI, Rounded Sharp angles rounded DI angles rounded DI They all have the same elevations and depressions. Enumerate and state the differences: Upper central Well developed elevations but the lateral more Upper lateral developed. Fossa ? Lower incisors Less developed. Fossa ?  Labial Aspect 1 2 1 2 Geometric outline Trapezoidal Incisal M Sharp Round Sharp Sharp angles D Round more Sharp Round Size Widest Smaller narrowest Larger than 1 than 1 Root Single Cone Curved dist.  Lingual Aspect 1 2 1 2 Lingual convergence Elevations M,D,I More Less MR,longer ridges developed IR, slope distally Lingual Deep Deeper Shallow Shallow fossa with Ling. pit  Mesial Aspect 1 2 1 2 Geometric line Triangular Cervical Convex incisally line Contact near the between near the MI between M MI angle M & I third angle & I third area Incisal Perpendicular on Inclined lingually ridge the long axis Distal Aspect 1 2 1 2 Contact More cervically than mesially area Cervical Less by 1 mm than mesially curvature Root Root developmental depression  Incisal Aspect 1 2 1 2 Geometric Diamond Triangular outline Incisal ridge Centered labio- lingually Inclined Inclined lingu- lingually distally Ling. Width > Thickness convergence Crown tapers lingually Width = Width& Width > Thickness Thickness Thickness > Width thickness Can you tell *which tooth *which aspect *which surface anatomical landmark 2 , labial aspest, cervical ridge. 2, lingual aspect, lingual pit. 1 , labial aspect, cervical ridge. 2, lingual aspect, cingulum, M&D marginal ridges Identify the tooth, the aspect and the anatomical landmark. 2, lingual aspect, long mesial A marginal ridge, short distal marginal ridge. 1, mesial aspect, contact area, cervical line. A is for 2, incisal aspect, B distally tilted cingulum. B is for 1 , incisal aspect, lingual fossa.