Lecture 3 - Professor Kelvin: Permanent Incisors

Learning Out Come (LO 1) Permanent Maxillary and Mandibular Incisors The student should be able to: ❖Distinguish the chronological and morphological details of the permanent maxillary and mandibular central and lateral incisor. ❖Distinguish the characteristic features from different aspects of the t...

Learning Out Come (LO 1) Permanent Maxillary and Mandibular Incisors The student should be able to: ❖Distinguish the chronological and morphological details of the permanent maxillary and mandibular central and lateral incisor. ❖Distinguish the characteristic features from different aspects of the teeth (Labial, Lingual, Mesial, Distal & Incisal). ❖Identify & differentiate maxillary from the permanent mandibular incisors. ❖Distinguish a few common variations in tooth morphology. Maxillary Permanent Central Incisor Crown: (Labial View) La Longest and widest anterior tooth Crown wider mesio-distally (M-D) than Facio-Lingually (F-L) Sharp mesio-incisal angle and convex disto-incisal angle D M Root : One root, broad, tapers in the apical third and short compared to all incisors Cervicaldimension M-D approximately equal to F-L  Cont’d Blunt root Surfaces: (Incisal view) La apex Labial surfaces are more rounded from incisal aspect The tooth tapering toward the lingual Cemento-enamel The labial surface is Junction (CEJ) convex Developmental Cingulum located off- grooves center towards distal Narrowest incisal Inciso-distal angle embrasures Deep lingual fossa Inciso-mesial angle Mamelons (seen in newly erupted teeth) and 4 Lingual fossa developmental grooves Cingulum  Cont’d Blunt root o Surfaces: (Labial view) Recap La apex o Labial surfaces are more rounded from the incisal aspect o The tooth tapering toward Cemento-enamel the lingual Junction (CEJ) o The labial surface is convex Developmental o Cingulum located off-center grooves toward distal o Narrowest incisal Inciso-distal angle embrasures o Deep lingual fossa Inciso-mesial angle o Mamelons (seen in newly erupted teeth) and Lingual fossa developmental grooves Cingulum  Cont’d Blunt root o Mamelons (seen in newly La apex erupted teeth) and developmental grooves Cemento-enamel Junction (CEJ) Mamelons Developmental grooves Inciso-distal angle Inciso-mesial angle Lingual fossa Cingulum Maxillary Permanent Central Incisor Crown: (Palatal View) Pa Longest and widest Convex anterior tooth cingulum Crown wider mesio- Marginal ridges distally (M-D) than (shovel-shaped Facio-Lingually (F-L) incisor) Sharp mesio-incisal Lingual fossa angle and convex disto-incisal angle Incisal edge  Maxillary Permanent Central Incisor Root : (Palatal View) Pa One root, broad, tapers in the apical Convex third and short cingulum compared to all Marginal ridges incisors (shovel-shaped incisor) Cervical dimension M-D approximately Lingual fossa equal to F-L Incisal edge  Cont’d Proximal View: Mesial Distal o Mesial curvature of cervical line CEJ (CEJ) is the largest among all teeth (2- 3) mm incisally o The crown conforms to a triangular outline form o The tip of the incisal edge and the root located in the midline o Contact: o Mesial…Mesio-incisal angle o Distal….Slightly cervical to disto- incisal angle Cont’d  Mesial curvature of cervical line (CEJ) is the largest among all teeth (2-3)mm incisally  The crown conforms to a triangular outline form  The tip of the incisal edge and the root located in the midline  Contact:  Mesial….. Mesio-incisal angle  Distal…... Slightly cervical to disto-incisal angle  Anomalies in central Incisor Hutchinson's tooth, Talons Cusp  Maxillary Permanent Lateral Incisor Crown: (Labial View) Root deviates La M-D > F-L (just like to distal the max central incisor) but smaller in size The incisal edge Both angles inclines toward the distal are convex Rounded incisal angles with the distal angle more convex The distal outline is more convex compared to mesial Lingual pit  Maxillary Permanent Lateral Incisor Root: (Labial View) Root deviates La One, cone-shaped, to distal tapers toward the apex and the apical 1/3 deviates to distal Both angles are convex Lingual pit  Cont’d Root may show mesial and distal furrows Cone-shape Lingual surface: root Lingual pit is common. Lingual surface most concave of Furrow any incisors Cingulum very pronounced. CEJ The lingual fossa is more likely convex to to have developmental grooves incisal than the max central incisor (CI) Other features are similar to max CI Cingulum slightly to distal Cont’d Contact: Mesial…...Junction of middle & incisal 1/3 Distal……Middle 1/3 Notes May be congenitally absent May appear pointed (“peg shaped”)  Palatal abscess related to upper left lateral incisor In this case the 11 (FDI) is non vital with PA changes. 12 may be non- vital? Mandibular Permanent Incisors General features: ▪ The permanent mandibular incisors are the smallest teeth of the permanent dentition and the most symmetric ▪ The central and lateral incisors of the mandibular arch resemble each other ▪ Generally, the lateral incisor is larger than the central incisor, in contrast to the teeth in the maxillary arch ▪ Plaque, calculus, and stain, tend to collect in the lingual concavity of the mandibular incisors  Cont’d  The contact areas are near the incisal ridges mesially and distally for both central and lateral incisors  The labial surfaces incline lingually Mandibular Central Incisor La Li Incisal ridge Mesial marginal Distal marginal ridge ridge Lingual fossa Cingulum Cervical line ▪ Crown: ▪ The labial aspect is smooth, regular, tapering evenly to the apical portion of the root ▪ The incisal ridge is straight and at right angle to the long axis of the tooth  Cont’d D ▪ Root: ▪ Tip of the incisal edge is sitting lingual to the midline ▪ Broad root, show furrow mesially and distally ▪ Cervical line curves toward incisal edge M ▪ Contact: Incisal to the junction of incisal and middle 1/3s of the crown  Cont’d D ▪ The labial surface is flattened at the incisal 1/3, the middle 1/3 is more convex ▪ The crown shows mamelons (newly erupted) and traces of developmental lines ▪ The crown is narrower on the M lingual surface than on the labial surface ▪ They have a small convex, centered cingulum, subtle lingual fossa, and equally subtle marginal ridges Mandibular Lateral Incisor ▪ The mandibular lateral incisor Li La is slightly larger than the mandibular central incisor in all dimensions but otherwise is similar ▪ The lateral incisor has a small, distally placed cingulum M D Mandibular Lateral Incisor ▪ The greater height of the (CEJ) Li La curvature on the mesial surface than on the distal surface helps in distinguishing the right lateral incisor from the left lateral incisor M D  Cont’d ▪ The mesial side of the crown is Li La longer than the distal, causing the straight incisal edge to slope distally ▪ The distal contact area is more toward the cervical than the mesial contact M D ▪ The crown is slightly longer than the central incisor ▪ The incisal edge is not at right angle to a line bisecting the crown and the root labio- lingually  Cont’d ▪ The root is similar to the central Li La incisor but considerably longer ▪ The labio-lingual axes of 41&42 are almost parallel in the alveolar process M D Defects of tooth commonly seen in Incisors Enamel Hypoplasia Amelogenesis Imperfecta Mesiodent and Peg lateral Macrodontia and Microdontia Like your tooth prints and fingerprints, your tongue is also unique. No two people share the same tongue print.