Permanent Incisors Introduction Centrals and laterals 7 8

Permanent Incisors

Introduction: • • Centrals and laterals #7, 8, 9, 10 and 23, 24, 25, 26 Maxillary larger than mandibular Important in esthetics, mastication, phonetics

Terminology: CEJ mamelons cingulum lingual fossa marginal ridge

Some common traits: • Incisal edge present = incisor • Mamelons: 2 or 3 • Marginal ridges more parallel to long axis • Presence of lingual fossa and cingulum

Permanent Maxillary Central Incisor

General characteristics: • Arch position: on either side of midline – Adjacent mesial surfaces • Universal #8 and #9 • M-D almost as wide as I-C dimension* • Wider M-D than F-L* (I-C > M-D > F-L) • Widest M-D of all anterior teeth* *type trait

Development timeline* • • Beginning calcification: 3 - 4 months Completion of enamel: 4 - 5 years Eruption: 7 - 8 years Root completion: 10 years (2 years later) *Fuller/Denehy

Labial View • Basic crown shape is trapezoidal • Surface generally flat, developmental depressions visible • M-D and I-C dimension more nearly equal* (as compared to other incisors) • Cervical line more flat (more than any other anterior teeth)

Labial view: • Incisal edge perpendicular to long axis • Facial height of contour in cervical third • Mamelons visible in newly erupted teeth

Labial view: mesial outline • Mesial outline nearly straight • MI angle sharp • Mesial contact area (HOC) at incisal third

Labial view: distal outline • Outline more convex than mesial • DI angle more rounded • Distal contact area (HOC) near junction of incisal-middle third

Lingual View • Slightly narrower M-D than labial • Surface has both convexity and concavity – – Marginal ridges, M and D Cingulum Lingual fossa Incisal ridge

Lingual view: • M and D outlines similar to labial view • CE curvature greater than labial, slight offset to distal • Lingual height of contour at cervical third • M and D marginal ridges border lingual fossa

Mesial View • Crown basically triangular • Mesial CE line curvature is greatest of any tooth* • Incisal edge is in line with long axis • Mesial height of contour (mesial contact area) at incisal third

Mesial view: • Labial outline – slightly convex – height of contour at cervical third – incisal 2/3 nearly flat • Lingual outline: S-shape – concave incisally – convex cervically – height of contour at cervical third • Incisal edge slopes lingually

Distal View • Generally similar to mesial • Distal surface slightly more convex than mesial • CE line curvature is less than mesial • Distal HOC near junction of -middle third incisal

Incisal View • • Roughly triangular outline* Lingual narrower than labial Wider M-D than F-L* Incisal edge is midway faciolingually *type trait

Root • Single, conical, straight • Cross-section at cervical roughly triangular* • Ratio of crown to root: 2/5 to 3/5

How to tell if you have a maxillary central: • Presence of incisal edge, sloping lingually • M-D width broad (8 -9 mm) – M-D almost as wide as I-C dimension* • Wider M-D than F-L* – I-C > M-D > F-L • Relatively flat labial surface • M and D incisal corners relatively sharp • Root cross-section more triangular

How to distinguish right from left: • Mesial outline straighter than distal* (distal has more convexity than mesial) • MI angle is sharper than DI* • CE line curvature is greater on mesial* • Mesial HOC more incisal than distal* • Lingual cervical line sometimes offset distally

Next… Maxillary Lateral Incisor

Permanent Maxillary Lateral Incisor

General Characteristics • Second tooth from midline • Between maxillary central and maxillary canine • Universal numbers: #7 and #10 • Resembles maxillary central except: – Smaller in all dimensions except root length* – Generally more rounded – Displays more variation in form

Development Timeline: • • Beginning calcification: 1 year Completion of enamel: 4 - 5 years Eruption: 8 - 9 years Root completion: 11 years

Labial View • Mesial outline – More convexity than mesial of central – HOC (contact area) is at incisal third (closer to the junction of the incisal and middle thirds)

Labial View • Distal outline – DI corner noticeably more rounded than MI (most rounded incisal corner*) – HOC is at junction of incisal-middle third to the middle of the middle third

Labial view: • Incisal outline – More rounded than central esp. DI corner – Greatest rounding of any incisor* • Labial height of contour: cervical third

Lingual View • • Marginal ridges more prominent Lingual fossa deeper Lingual pit often present Linguogingival fissure sometimes present • Height of contour at cervical third

Mesial View • Labial outline is convex • Lingual outline is S-shape • CE line curvature greater than distal • Incisal edge is inline with long axis of tooth • Mesial HOC near junction of incisal and middle 1/3

Distal View • Similar to mesial except – HOC more cervical (closer †o middle 1/3) – CE line curvature less than mesial

Incisal View • Generally more convexity than central • MD ≥ FL dimension • Incisal edge is midway faciolingually

Root • Single rooted • Root wider F-L than M-D • Apical third may be deflected distally* • Cross-section more ovoid than central

Variations and anomalies: • Most variations in form besides third molars* • May be congenitally missing • “Peg” lateral: peg-shaped crown

How to tell if you have a maxillary lateral: • • • Smaller in size than max central More distinct lingual anatomy Presence of deeper lingual fossa Presence of lingual pit Incisal outline more rounded M and D outlines more rounded

How to tell right from left: • MI corner sharper than DI corner* • Mesial CE line curvature greater than distal • Mesial height of contour more incisal than distal’s* • Distal outline more convex* • Apex deflected distally

Laboratory Project

For lab today…

Boley Gauge

Video of lab project…

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