Maxillary Incisors.pptx

Maxillary Incisors BY DR. AMRUTHA R

1. Permanent mAxillary incisors DR AMRUTHA

2. CONTENTS 11/12/2017 Dr Amrutha 2 Introduction to incisors Class traits common to all incisors Permanent Maxillary Central incisor Permanent Maxillary Lateral incisor Type traits which distinguish Maxillary Central Incisors from Maxillary Lateral Incisors Traits to distinguish maxillary incisors of the left side from those of the right side Arch traits which distinguish maxillary incisors from mandibular incisors

3. INCISORS 11/12/2017 Dr Amrutha 3

4. Etymology: incise means to cut; incisor means cutter (from latin ) 8 in number: 4 maxillary incisors; 4 mandibular incisors 2 central incisors and 2 lateral incisors Location Centrals incisors: on either side of midline Lateral incisors: distal to the central incisors THE MAXILLARY AND THE MANDIBULAR CENTRALS ARE THE ONLY NEIGHBOURING TEETH IN THE DENTAL ARCHES WITH MESIAL SURFACES IN CONTACT WITH EACH OTHER. INTRODUCTION 11/12/2017 Dr Amrutha 4

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6. FUNCTIONS 11/12/2017 Dr Amrutha 6 Cut food : mandibular incisors are like moving blades against the stationary maxillary incisors Articulate speech Help to support the lip and maintain an aesthetic appearance They also help to guide the mandible posteriorly during the final phase of closing

7. MORPHOLOGY 11/12/2017 Dr Amrutha 7 Described under five views/aspects: Facial / labial aspect Lingual / palatal aspect Mesial aspect Distal aspect Incisal aspect Together referred to as proximal aspects

8. INCISOR CLASS TRAITS 11/12/2017 Dr Amrutha 8

9. IDENTIFICATION TRAITS 11/12/2017 Dr Amrutha 9 SET TRAITS (Dentition traits) Distinguish teeth in the primary (deciduous) from secondary (permanent) dentition ARCH TRAITS : Distinguish maxillary from mandibular teeth CLASS TRAITS : Distinguish the four categories (or classes) of teeth: namely incisors, canines, premolars and molars TYPE TRAITS : Differentiate teeth within one class (such as differences between central and lateral incisors, or between 1st and 2nd premolar or between 1st, 2nd, and 3rd molars) distinguishing characteristic, quality, peculiarity or attribute

10. DEVELOPMENTAL LOBES 11/12/2017 Dr Amrutha 10 Incisors develop from four developmental lobes Labial surfaces: three labial portions Mesial lobe Middle lobe Distal lobe Mamelons Developmental depressions The fourth lobe forms the lingual bulge called the cingulum .

11. LABIAL VIEW 11/12/2017 Dr Amrutha 11 Incisal edge is straight (all the other teeth have one or more cusps) Rectangular: inciso - gingivally > mesiodistally Incisor crown contact areas: incisal third, distally-more cervical; EXCEPT mandibular central Taper from areas of proximal contact towards the cervical line More convex on the distal than the mesial side, EXCEPT the mandibular central incisors

12. LABIAL VIEW 11/12/2017 Dr Amrutha 12 Mesioincisal angles are more acute or sharper than the distoincisal angles, EXCEPT in mandibular central incisors Cervical line curves towards the apex Roots taper from cervical line to the apex Incisor roots may bend in apical one-thirds; more often towards the distal; EXCEPT maxillary central incisor Incisor roots are longer than the crowns

13. LINGUAL VIEW 11/12/2017 Dr Amrutha 13 Crowns have a narrow lingual surface because mesial and distal sides converge lingually Mesial and distal marginal ridges Cingulum Lingual fossa

14. PROXIMAL VIEWS 11/12/2017 Dr Amrutha 14 The crowns are wedge-shaped or triangular Height of contour: cervical third; lingually it is represented by the cingulum The contour of the incisal two-thirds of the lingual surface is concave from the cingulum area to the incisal edge

15. PROXIMAL VIEWS 11/12/2017 Dr Amrutha 15 The cervical line proximally curves towards the incisal edge The curvature of the cervical line is greater on the mesial surface than on the distal surface Roots are widest at the cervical region and gradually taper to a rounded apex

16. INCISAL VIEW 11/12/2017 Dr Amrutha 16 Lingual fossa : concave, just incisal to the cingulum Incisal ridge / incisal edge Labial outline is broader and less curved than the convex lingual outline Marginal ridges converge towards the cingulum Crown outline : narrow lingual side than the buccal side Incisal ridge : When an incisor is newly erupted, the incisal portion is rounded and merges with the mesioincisal and the distoincisal angles and the labial and lingual surfaces. This ridge of the crown is called incisal ridge. Incisal edge : An incisal edge does not exist on an incisor until occlusal wear has created a flattened surface linguo-incisally , which surface forms an angle with the labial surface.

17. PERMANENT MAXILLARY INCISORS 11/12/2017 Dr Amrutha 17

18. MAXILLARY INCISORS 11/12/2017 Dr Amrutha 18 Four in number Central incisors are centred in the maxilla, one on either side of the midline; with the mesial surface of each in contact with the mesial surface of the other. The right and left maxillary lateral or second incisors are distal to the central incisors

19. PERMANENT MAXILLARY CENTRAL INCISOR 11/12/2017 Dr Amrutha 19

20. CONTENTS 11/12/2017 Dr Amrutha 20 Introduction Chronology Dimensions Detailed description from all aspects Labial view Lingual view Mesial view Distal view Incisal view Applied aspects

21. INTRODUCTION 11/12/2017 Dr Amrutha 21 Widest tooth mesiodistally of all the anterior teeth Crown sizes of the maxillary central incisor are gender dimorphic, with male larger than female The space, if it is present, between the central incisors is called “midline diastema ”

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23. CHRONOLOGY 11/12/2017 Dr Amrutha 23 First evidence of calcification: 3-4 months Enamel completed: 4-5 years Eruption: 7-8 years Root completed: 10 years

24. DIMENSIONS 11/12/2017 Dr Amrutha 24 Cervicoincisal length of crown: 10.5 mm Length of root: 13.0 mm Mesiodistal diameter of crown: 8.5 mm at cervix: 7.0 mm Labiolingual diameter of crown: 7.0 mm at cervix: 6.0 mm Curvature of cervical line- mesial : 3.5 mm Curvature of cervical line-distal: 2.5 mm

25. LABIAL ASPECT CROWN SHAPE Rectangular CROWN OUTLINES MESIAL OUTLINE: straight and longer than the distal outline DISTAL OUTLINE: more convex than the mesial outline INCISAL OUTLINE: STRAIGHT ; tends to curve downwards towards the centre of the crown, so the crown length is greater at the centre than at the two incisal angles Mamelons will be seen on the incisal ridge; the middle one is smallest CERVICAL OUTLINE: semicircular; has the curvature rootwise

26. LABIAL ASPECT 11/12/2017 Dr Amrutha 26 INCIS0-PROXIMAL CROWN ANGLES The distoincisal angle is not as sharp as the mesioincisal angle PROXIMAL CONTACT AREAS Mesial contact area: approaching the mesioincisal angle Distal contact area: slightly towards the cervical line ROOT SHAPE The root is cone shaped with a blunt apex The outline of the root is regular mesially and distally

27. LINGUAL ASPECT 11/12/2017 Dr Amrutha 27 CINGULUM : A smooth convexity is found immediately below the cervical line MARGINAL RIDGES : Mesially and distally LINGUAL FOSSA : Between the marginal ridges and below the cingulum LINGUO-INCISAL EDGE : Outlining the lingual fossa on level with the marginal ridges THE LINGUAL PORTION IS THUS BORDERED MESIALLY BY THE MESIAL MARGINAL RIDGE, INCISALLY BY THE LINGUAL PORTION OF THE INCISAL RIDGE, DISTALLY BY THE DISTAL MARGINAL RIDGE AND CERVICALLY BY THE CINGULUM.

28. cingulum MMR Lingual fossa DMR LINGUAL ASPECT

29. LINGUAL ASPECT 11/12/2017 Dr Amrutha 29 Some developmental grooves extend from the cingulum into the lingual fossa The crown and the root taper lingually ROOT: Cross-section is triangular with rounded edges One side is labial The other two are mesial and distal sides pointing lingually Mesial side of the triangle is longer than the distal side.

30. MESIAL ASPECT 11/12/2017 Dr Amrutha 30 CROWN SHAPE: wedge or triangular, with the base of the triangle at the cervix and the apex at the incisal ridge. CREST OF CURVATURE: Labially and lingually immediately coronal to the cervical line These crests of contour give the crown its greatest labiolingual measurement

31. MESIAL ASPECT 11/12/2017 Dr Amrutha 31 LABIAL OUTLINE from the crest of curvature to the incisal ridge is very slightly convex LINGUAL OUTLINE The cervical line curves incisally ROOT SHAPE: cone, with the apex usually bluntly rounded.

32. DISTAL ASPECT 11/12/2017 Dr Amrutha 32 The curvature of the cervical line is less in extent on the distal than on the mesial surface. Little difference is evident between the distal and mesial outlines of the maxillary central incisors.

33. INCISAL ASPECT 11/12/2017 Dr Amrutha 33 Crown from this aspect superimposes over the root entirely The labiolingual dimension of the crown is more than two-thirds as great as the mesiodistal diameter The crown conforms to a triangular outline.

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35. CLINICAL CONSIDERATIONS 11/12/2017 Dr Amrutha 35 SHOVEL SHAPED INCISORS An incisor with exaggeration of the marginal ridges is known as a shovel-shaped incisor . It is a genetically determined variation seen in mongoloid races, including North and South American Indians. The maxillary central incisor usually develops normally. One anomaly that sometimes occurs is a short root.

36. PERMANENT MAXILLARY LATERAL INCISORS 11/12/2017 Dr Amrutha 36

37. Introduction Chronology Dimensions Detailed description from all aspects Labial view Lingual view Proximal views Incisal view Applied aspects CONTENTS 11/12/2017 37 Dr Amrutha

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39. Because the maxillary lateral incisor supplements the central incisor in function, their crowns bear a close resemblance. First evidence of calcification: 10-12 months Enamel completed: 4-5 years Eruption: 8-9 years Root completed: 11 years INTRODUCTION & CHRONOLOGY 11/12/2017 39 Dr Amrutha

40. Cervico incisal length of crown: 9.0mm Length of root: 13.0mm Mesiodistal diameter of crown: 6.5mm Mesiodistal diameter of crown at cervix: 5.0mm Labiolingual diameter of the crown: 6.0mm Labiolingual diameter of crown at cervix: 5.0mm DIMENSIONS 11/12/2017 40 Dr Amrutha

41. Crown shape Proportions similar to the central incisor, though dimensionally smaller. Labial surface is more convex or less flat mesiodistally . Mamelons are less prominent. Crown outline is less symmetrical. LABIAL ASPECT 11/12/2017 41 Dr Amrutha

42. Incisal -proximal crown angle : Mesioincisal and distoincisal angles are rounded. Mesioincisal is more acute than distoincisal . LABIAL ASPECT 11/12/2017 42 Dr Amrutha

43. Proximal contact areas : Mesial contract area is in the incisal third, slightly cervical to the incisal edge. Distal contact area is cervical than the mesial , in the middle third. LABIAL ASPECT 11/12/2017 43 Dr Amrutha

44. Root crown ratio : Root is longer in proportion to the crown than that of the central incisor. Root shape : Root tapers evenly towards the rounded apex and the apical end is slightly bent to the distal. LABIAL ASPECT 11/12/2017 44 Dr Amrutha

45. Lingual fossa : Large lingual fossa immediately incisal to the cingulum . Bounded by two marginal ridges. Lingual fossa of maxillary lateral incisor in more prominent than on the central incisor. LINGUAL VIEW 11/12/2017 45 Dr Amrutha

46. Cingulum : Narrower than that of the central incisor and is centered on the root axis line. Marginal ridges : Due to the displacement of the incisal edge slope cervically on the distal side, the distal marginal ridge is shorter than the mesial . Mesial marginal ridge: straight Distal marginal ridge: curved cervicoincisally LINGUAL VIEW 11/12/2017 46 Dr Amrutha

47. Root shape : Root contour is convex and tapers, becoming narrower towards the lingual side. LINGUAL VIEW 11/12/2017 47 Dr Amrutha

48. Incisal edge : Just labial to the root axis line or on the root axis line. Cervical line : Curves incisally on mesial and distal sides. Curvature is greater on the mesial surface. Height of contour : Labial: cervical third Lingual: cingulum PROXIMAL VIEWS 11/12/2017 48 Dr Amrutha

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50. Root shape and root depressions : Tapers evenly throughout the root towards the blunt apex. The mesial root surfaces could have a slight depression in the middle third cervicoapically , slightly lingual to the center faciolingually . PROXIMAL VIEWS 11/12/2017 50 Dr Amrutha

51. Crown proportion : Mesiodistal measurement greater than the labiolingual measurement. Outline shape and cingulum location : Outline is round or oval since the labial outline is more convex. The cingulum is nearly centered mesiodistally . INCISAL VIEW 11/12/2017 51 Dr Amrutha

52. Incisal ridge and contour : The incisal ridge is slightly curved from mesial to distal, the convexity being on the labial side. The distoincisal angle is slightly more lingual than the position of mesioincisal angle. INCISAL VIEW 11/12/2017 52 Dr Amrutha

53. Most commonly missing next to third molars. Peg laterals. Shovel shaped incisors. CLINICAL CONSIDERATIONS 11/12/2017 53 Dr Amrutha

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56. Thank you 11/12/2017 56 Dr Amrutha