1. Dental Anatomy, Morphology and Occlusion Max & Mandibular Incisors
RSD 811

2. Dental Anatomy and Morphology

3. MAXILLARY AND MANDIBULAR INCISORS

4. MAXILLARY CENTRAL INCISOR
General Characteristics
Development
Views
Axial Inclination & Occlusion
Root
Pulp Spaces

5. General Characteristics
Widest Incisor Crown; 2nd Largest tooth
Shape and position affect facial esthetics
Geometrical shapes:
Labial or lingual view: trapezoid
Proximal: triangle
Adjacent to midline; mesials contact

6. DEVELOPMENT Calcification begins: 3-4 months
Enamel completed: years
Eruption: years
Root completed years
Develops from 4 lobes
3 labial lobes(mammelons)
4th lobe yields Cingulum

7. LABIAL VIEW Tooth length is 22-24 mm
Coronal length is mm(2nd largest tooth in mouth
Coronal width at interproximal contacts: 8 to 9 mm
Widest of all the incisors
At CEJ: 6-7 mm

8. LABIAL VIEW(CON’T) Basic coronal shape is trapezoid
Mammelons may be on newly erupted teeth
Incisal edge shows a slight convexity, but is basically straight
Mesioincisal angle approaches 90 degrees

9. LABIAL VIEW(CON’T)
Mesio incisal angle is located more incisally than the more rounded disto-incisal angle. Therefore the incisal edge goes slightly more gingivally from the mesio labial to disto-labial line angles.

10. LABIAL VIEW(CON’T) Mesial outline is relatively straight
Distal outline is more convex
Mesio labial line angle longer and straighter than distolabial line angle
Interproxinal contacts occur at the greatest convexity of the proximal surfaces

11. LABIAL VIEW(CON’T)
Mesial contact is in the incisal 1/3rd near the incisal edge; very small incisal embrasure
Distal contact near the junction of the incisal and middle 1/3rd’s
Buccal cervical line(CEJ) is convex in an apical direction; centered distal to midline
Flat mesial and distal emergence angles

12. LABIAL VIEW(CON’T) Generally smooth with small irregularities
Two labial grooves
Root is cone-shaped, regular, and blunt
Length of the root is mm which is 2-3 mm longer than the crown
Root has a small distal inclination

13. LINGUAL VIEW Similar to labial, but slightly smaller
Has convexities and concavities(unlike the labial), resulting in “scoop” form
Prominent mesial and distal marginal ridges extend cervically and flow into cingulum

14. LINGUAL VIEW(CON’T)
Incisal ridge is raised and continuous with mesial and distal marginal ridges
Lingual fossa is concave in mesio distal and inciso cervical dimensions
Prominent marginal ridges and well developed lingual fossa are arch traits for maxillary incisors

15. LINGUAL VIEW(CON’T)
Large cingulum in cervical 1/3rd of the lingual surface
Incisal to the cingulum, the lingual surface is concave forming the lingual fossa
A lingual pit may be found at the cervical end of the lingual fossa(more commonly found in max lateral incisors)

16. LINGUAL VIEW(CON’T) CEJ is convex apically; centered distal to midline
Lingual CEJ more convex than labial CEJ
Root tapers lingually(arch trait)

17. PROXIMAL VIEWS
Shape is a triangle with the base at CEJ and apex at incisal ridge
Incisal ridge is centered labiolingually
Labial surface is convex inciso-cervically
Lingual surface has both convex and concave areas

18. PROXIMAL VIEWS(CON’T)
Greatest labiolingual dimension is about 7 mm
At CEJ, the labiolingual dimension is approximately 6 mm
Labial and Lingual heights of contour are in the cervical 1/3rd of the crown

19. PROXIMAL VIEWS (CON’T)
Interproximal contact area is more incisal on the mesial than the distal
CEJ shows greater convexity on mesial than distal
Crown may appear thicker labiolingually from a distal view point
Facial of root is more convex than lingual

20. INCISAL VIEW Shape is a triangle with base on the labial
Mesial outline is longer, resulting in distal positioning of the apex of the triangle
Root is completely obscured from view
Labial surface is convex mesiodistally with a slight distolingual shape

21. INCISAL VIEW(CON’T)
Labial developmental grooves can be viewed, if present
Mesiolabial and distolabial line angles are clearly seen
Lingual line angles are less evident
Lingual embrasures are wider than those of the labial

22. ROOT Conical, but converges lingually to give a triangular form
Much variability in apical 1/3rd of this and all other teeth
Horizontal view
Labial, lingual, distal surfaces: convex
Mesial: convex and concave

23. OCCLUSION
The lingual surface of the maxillary central incisors occludes normally with the labio-incisal surface of the mandibular central and lateral incisors

24. AXIAL INCLINATION Proximal view: 28 degrees(apex tilted lingually)
Labial view: 2 degrees(Apex tilted mesially)

25. PULP SPACES
Horizontal sections: circular in the apical; elliptical at CEJ, and wider elliptically (mesiodistally) in the coronal portion of the pulp chamber
Large, single, widest mesiodistally at roof
Sections:
Longitudinal section:
Mesiodistal-3 horns
Labiolingual-smooth apical taper; slight labiolingual constriction at CEJ

26. MAXILLARY LATERAL INCISOR
General characteristics
Development
Views
Axial Inclinations & Occlusion
Root and Pulp Spaces

27. GENERAL CHARACTERISTICS
Closely resembles central but smaller in all dimensions

28. DEVELOPMENT First evidence of calcification: 1 yr
Enamel completed yrs
Eruption yrs
Root completed yrs

29. DEVELOPMENT(CON’T) Development may not be normal
Most variation of any tooth except 3rd molars
Peg-shaped laterals
Congenitally-missing laterals

30. LABIAL VIEW More curvature than the central Rounded incisal edge
Rounded incisal angles(mesial and distal)
Disto incisal angle is more rounded than the mesial

31. LABIAL VIEW(CON’T) Proximal contacts Emergence Angle
Mesial: junction of incisal and middle 1/3rd
Distal: middle 1/3rd (incisal portion)
Emergence Angle
Flat interproximally; allows room for interdental papilla

32. LINGUAL VIEW
The marginal ridges, cingulum, and incisal ridge are more pronounced than the central incisors resulting in a more accentuated lingual fossa
The tooth tapers lingually-similar to the central incisor
Pit more likely

33. PROXIMAL VIEW Smaller crown/root ratio than central
Smaller labiolingual measurement
Curvature of CEJ is less than central
Longitudinal curves may be seen on root, resulting in flat or concave mesial and distal root surfaces
Width of crown looks thicker from distal view

34. Incisal The labial surface is more convex than the central incisors
Resembles a small canine

35. AXIAL INCLINATION Proximal View: 26 degrees (apex to lingual)
Labial View: 7 degrees (apex to mesial)

36. Occlusion
Occlusion is with mandibular lateral incisor and canine

37. ROOTS AND PULP CHAMBER Apex is more pointed than central
Frequent distal bend of the apex
Smaller than central
More likely to exhibit constrictions and accessory canals

39. MANDIBULAR CENTRAL INCISOR
General Characteristics Development Views Axial Inclination and Occlusion

40. GENERAL CHARACTERISTICS
Smallest tooth in the dental arch
Narrower mesiodistally, but almost as wide labiolingually as maxillary central
Masticating forces are in a labiolingual direction
Long root relative to the maxillary central

41. DEVELOPMENT(4 LOBES) First calcification seen 3-4 months
Enamel completed years
Eruption years
Root completed years
Normal path of eruption from the lingual

42. LABIAL VIEW Length of crown 9mm Mesial-distal width of crown 5mm
Labio-lingual width of crown 6mm
Length of tooth mm
General outline Form Trapezoid

43. LABIAL VIEW(CON’T)
Labial surfaces of #24, #25 are relatively straight and smooth
Disto incisal angle is only slightly more rounded than mesial
Convexity is greater cervically than incisally
Proximal contacts are in the incisal 1/3rd

44. LINGUAL VIEW
The lingual surface incisal to the cingulum and within the small marginal ridges is slightly concave mesio distally and inciso cervically. This results in a small, shallow lingual fossa and the absence of a lingual pit

45. PROXIMAL VIEWS General shape is triangular Facial surface-convex
Lingual surface-concave and convex
Height of contours: ½(or less) mm from CEJ-Curvature of CEJ greater on mesial
The incisal edge is slightly lingual of a perpendicular line that bisects the tooth labiolingually

46. Incisal View Very symmetrical
Incisal edge is almost centered labiolingually
Tapers lingually
Lingual development is slight

47. AXIAL INCLINATION 22 degrees (apex to lingual)
2 degrees (apex to mesial)

48. OCCLUSION
The normal occlusion of the mandibular central incisor is with the incisolingual surfaces of the maxillary central incisor

50. MANDIBULAR LATERAL INCISOR
General Characteristics
Development
Views
Axial Inclination and Occlusion
Root and Pulp Spaces

51. GENERAL CHARACTERISTICS
Slightly wider mesiodistally than central (maxillary incisors are just the opposite)
Similar in form and function to central
Mesial and distal contacts are in incisal 1/3rd with small incisal embrasures
Few traces of development; mammelons are normally lost soon after birth

52. DEVELOPMENT 4 lobes First calcification: 3-4 months
Enamel completed: 4-5 years
Eruption: years
Root Completed years

53. LABIAL VIEW Slightly wider mesiodistally than central (arch trait)
Mesial line angle often longer than distal
Incisal edge is often more cervical as one proceeds distally
Disto incisal angle is more rounded and more cervical than the mesio incisal angle

54. LINGUAL VIEW Similarity to central very close except for:
Asymmetry mesiodistally, distal 1/3rd more convex
Tooth is slightly wider than central
Lingual fossa of the mandibular lateral incisor is slightly more evident

55. PROXIMAL VIEWS
Mesial and distal views are very similar to central except for the CEJ
Slightly higher on mesial than distal

56. INCISAL VIEW
Incisal ridge is not perpendicular to a line bisecting the tooth labiolingually
Allows for curvature of the arch
Crown appears twisted distolingually on the root

57. AXIAL INCLINATION Proximal view: 23 degrees (apex lingual)
Labial view: 0 degrees (midline)

58. OCCLUSION
The mandibular lateral incisor occludes with the incisolingual surfaces of the maxillary central incisor and maxillary lateral incisor

59. ROOTS
Roots of mandibular incisors are flattened on the mesial and distal surfaces with the possibility of longitudinal grooves
Roots are symmetrical and straight(lateral incisors may be dilacerated in apical 1/3rd of root)
Lateral’s root is larger than centrals

60. PULP SPACES
Pulp chamber follows external form; wider in the labiolingual direction
Horizontal cross-section of the pulp chamber shows an elliptical shape that is widest mesiodistally in the crown, widest facio-lingually in mid-root and circular in apex
Two canals may be present

61. SUMMARY: MANDIBULAR INCISORS
Narrowest teeth of incisors
Lateral wider than central
Shallow lingual fossa
Flat labial surfaces
Roots oval in cross-section, much wider labio- lingually than mesio distally
Crown wider labiolingually

62. Today in D-611 Continue all projects you have started Begin:
1.2 Waxing proximal contours of #10(UL29) and #12 MO (UL49A)
1.3 #7 MFL(UR24) and MFLI #9(UL14A)