Permanent Canines PDF

Permanent Canines Dr. \ Manar A. Selim Oral Biology Department Faculty of Dentistry  General features  There are four permanent canines, 2 canines in each dental arch, one right and one left.  They are situated distal to the lateral incisors and mesial to the...

Permanent Canines Dr. \ Manar A. Selim Oral Biology Department Faculty of Dentistry  General features  There are four permanent canines, 2 canines in each dental arch, one right and one left.  They are situated distal to the lateral incisors and mesial to the first premolars.  Their main function is tearing of food materials during mastication. They are the longest teeth in the oral cavity characterized by long crowns and the longest roots. The roots are also strong and thick, this gives them a very strong attachment in the alveolar process of the jaw. Labial surface Mesial surface  In the alveolar process, over the labial aspect of their roots there is a well developed bone ridge called the canine eminence which together with the canines form and position provide facial support and ensure facial expressions (esthetic value). The crown of the canines is bulky and thick labiolingually and triangular in shape from the proximal aspects. Proximal surface It is trapezoidal in shape from the labial and lingual aspects. The middle labial lobe is highly developed incisally forming well- developed cusp that is why they are called ( cuspids) and labially forming the labial ridge.  Maxillary Canine Chronology: Appearance of enamel organ 6 month IUL First evidence of calcification 4-5 months Crown completed 6-7 years Eruption 11–12 years Root completed 14-15 years Chronology: 3 3 Appearance of enamel organ 6 m i.u.l. 6 m i.u.l Beg. Of calcification 4-5 m 4-5 m Crown completed 6-7 y 6-7 y Eruption 11-12 y 9-10 y Root completed 14-15 y 12-13 y  Labial surface Geometric outline of the crown: Trapezoidal in shape with the short of uneven sides cervically and the long side incisally. The labial surface of the crown is smooth and convex with maximum convexity at the cervical third (cervical ridge).  Labial surface - The middle labial lobe is over developed forming the labial ridge which extends from the cervical line to the tip of the cusp. - The labial surface of the crown is smooth except for two depressions (Mesiolabial and distolabial developmental depressions) that demarcate the site of union between the three labial lobes are seen in the incisal third.  Labial surface Mesial outline: convex from cervical line till the mesial contact area (at the junction of of the incisal and middle thirds) then continues as concave till the cusp tip. Distal outline: concave from cervical line till the distal contact area (at the center of the middle third) then continues as convex till the cusp tip. Cervical line: convex towards the root.  Labial surface - It has one cusp with mesial and distal slopes (mesial and a distal cusp ridges). - The mesial slope is shorter than the distal one. - The cusp tip is on a line with the long axis of the tooth.  Labial surface - The root is slender, conical with pointed apex. Its apical third shows distal inclination. Lingual surface  Lingual surface - The crown and root are narrower lingually than labially. - There is a well developed cingulum at the cervical third, mesial and distal marginal ridges are prominent and incisally there are mesial and distal cusp ridges. - A well developed lingual ridge extends from the cingulum to the cusp tip, dividing the lingual fossa into mesiolingual and distolingual fossae.  Lingual surface The root is smooth and convex, narrower lingually than labially  Mesial Aspect - The canine appears bulky from this aspect with greater labiolingual measurement than any other anterior tooth. - It is triangular in shape with the base of the triangle at the cervix and the apex at the cusp tip.  Mesial Aspect Labial outline is convex from the cervical line to the cusp tip with the crest of curvature at the cervical third represent cervical ridge Lingual outline is convex at the cervical third represent cingulum, in the middle third it’s straight due to presence of lingual ridge and convex again at cusp ridge. The cusp tip is labial to a line bisecting the root.  Mesial Aspect - The cervical line is convex towards the crown. - The root appears conical and tapers to blunt apex. - The mesial surface of the root has a shallow developmental depression.  Distal Aspect - The cervical line shows less convexity to the crown than the mesial aspect. - The distal marginal ridge is more developed than the mesial marginal ridge. - The distal contact area is more cervically. - The developmental depression on the distal side of the root is deeper.  Incisal Aspect Geometric outline--- Diamond - The labiolingual measurement is greater than the mesiodistal measurement. - The cusp tip is nearer to the labial outline and deviated mesially. - The mesial slope is shorter than the distal slope. - The labial outline is broader than that of the lingual.  Incisal Aspect - The labial ridge is well seen with two mesial and distal depressions on both sides. - The cingulum makes up the cervical third of the crown lingually. - The lingual ridge is well developed. - The mesiolingual and distolingual fossae are located located on both sides of the lingual ridge  Pulp cavity 0f max. canine a. Mesiodistal section: narrow pulp chamber and narrow root canal. a. Labiolingual section: The pulp chamber pointed incisally the root canal is wide in the cervical and middle thirds then decreases in size apically. a. Cross section: appears oval, larger labiolingually than mesiodistally.  Mandibular Canine Chronology: Appearance of enamel organ 6 month IUL First evidence of calcification 4-5 months Crown completed 6-7 years Eruption 9–10 years Root completed 12-13 years Maxillary Canine Mandibular Canine  Mandibular Canine It resembles the maxillary canine in form and function. Its crown appears a little longer, narrower mesiodistally and the elevations & depressions are less developed than those of the upper canine.  The root may be bifurcated.  Labial surface Maxillary Canine Mandibular Canine  Labial surface - The crown of mandibular canine appears longer due to: - The crown of mandibular canine is narrower mesiodistally. - The mesial and distal contact areas are closer incisally to the cusp ridges.  Labial surface - The mesial contact area is in the center of the incisal third. - The distal contact area is at the junction between the middle and the incisal thirds.  Labial surface - The mesial outline of the crown of the mandibular canine is nearly straight while the distal outline is convex. - The mesial cusp ridge is also shorter than the distal cusp ridge. - The distal outline is shorter than the mesial outline because the distal cusp ridge slopes downwards.  Labial surface - The cusp tip and ridges of the mandibular canine are less developed compared to those of the maxillary canine. - The root is shorter and its apex is more pointed than that of the maxillary canine.  Lingual surface - All the elevations and depressions are poorly developed. - The cingulum, the marginal and the cusp ridges are less distinct. Maxillary Canine Mandibular Canine  Lingual surface - The lingual ridge is almost absent except at the cusp tip (restricted to the incisal third). - The lingual fossa is less pronounced. Maxillary Canine Mandibular Canine  Lingual surface Maxillary Canine Mandibular Canine  Mesial Aspect - The incisal portion is thinner labiolingually, this makes the cusp appears more pointed. - The tip of the cusp is centered over the root or slightly lingually inclined. - On the root, the mesial developmental depression is more marked than the upper canine. Maxillary Canine Mandibular Canine  Mesial Aspect Lingual outline is concave in the middle third of lower canine rather than straight as in upper canine due to short lingual ridge which located only in incisal third. Maxillary Canine Mandibular Canine  Distal Aspect - There is little differences between upper and lower canines from the distal aspect except those mentioned on the mesial surface.  Distal Aspect - The distal marginal ridge is more pronounced than the mesial marginal ridge. - The cervical line curves less than in mesial. - The distal contact area is more cervically. - More pronounced developmental depression on the root.  Incisal Aspect - The cusp ridges appear narrower. - The cusp tip is slightly lingually inclined. - The cingulum, ridges and Mandibular Canine Maxillary Canine fossae are less pronounced.  Pulp cavity 0f mand. canine - Similar but smaller than that of the upper canine.  Pulp cavity 0f mand. canine - Sometimes the root of lower canine may have two root canals. When the root is bifurcated, there are always two canals which open separately in two apical foramina. Thank You