1. ANATOMY OF THE PERIODONTIUM

2. Department of Periodontics and Community Dentistry
Prof. Fatin Awartani
Department of Periodontics and Community Dentistry

3. Part II Cementum and Alveolar bone

4. Cementum

5. Calcified mesenchymal tissue that forms the outer covering of the anatomic root

6. Cementum:
Provides a means of attachments for the periodontal ligament fibers to the tooth.
Consists of calcified collagen fibers and interfibriller ground substance.
Made up of 40-45%of inorganic material and % organic matter and water.

7. Cementum Composition Organic matrix50%-55% Type I collagen (90%)
Type III collagen (5%)
Cementocytes
Proteoglycans*
Glycoprotiens
Phosphoprotiens
Inorganic content: Hydroxyapetites (45-50%)

8. Width varies from 16 to 60 microns in the coronal half of the root and 150 to 200 microns in the apical third of the root.
Width increases with age, 95 microns at age 20 and 215 microns at age 60.

9. Cementum
What are the sources of collagen fibers in cementum? Extrinsic sharpeys fibers formed by Fibroblasts. Intrinsic Fibers of the cementum matrix formed by cement oblasts.

10. The insertion of sharpy’s fibers into the cementum
Extrinsic Fibers
- Constitute a considerable proportion of the bulk of
Cementum.
- The embedded portion of the principal fibers of the
periodontal ligament.
- Formed by the fibroblasts
- Composed of mainly collagen
type I, coated by collagen type III.
The insertion of sharpy’s fibers into the cementum

11. Intrinsic fibers cementocytes Belong to the cementum matrix
Produced by cementoblasts

12. Types of cementum

13. Two types of cementum acellular and cellular
acellular cementum is found on the coronal areas of the root.
cellular cementum is found in the apical areas of the roots and in the furcation areas of multirooted teeth.

14. TWO MAIN FORMS OF CEMENTUM
ACELLULAR - first to be formed
covers approximately the cervical
third of half of the root
does not contain cells
formed before the tooth reaches occlusal plane
sharpey’s fibers make up most of the structure of acellular cmentum

15. CELLULAR(secondary cementum)
formed after tooth reaches occlusal
plane
contains cells in lacunae
less calcified than acellular
more common on apical half of tooth
greatest increase with age is cellular type in apical half of root

16. Acellular and cellular cementum are both arranged in lamellae separated by Incremental lines parallel to the long axis of the root.

17. Types of Cementum Schroeder's Classification
Acellular Afibrillar Cementum
Acellular Extrinsic Fiber
Cellular intrinsic Fiber cementum.
Cellular mixed stratified cementum
Intermediate Cementum

18. Schroeder Acellular afibrilar cementum
Acellular extrinsic fiber cementum
Cellular mixed stratified cementum
Cellular intrinsic fiber cementum
Intermediate cementum
contents
Mineralized ground substance
Densely packed bundles of sharpy’s fibers
Extrinsic (sharpy’s f)
Intrinsic
fibers
- celss
- Intrinsic
- cells
Poorly defined zone near the cementodentinal junction of certain teeth.
source
cementoblasts
Fibroblasts+ cementoblasts
Fibroblasts + cementoblasts
site
Coronal cementum
cervical
third of
roots
Apical third of roots
Apices
furcation areas.
Fills resorption lacunae.
thickness
1-15μm
30-230μm μm
Schroeder

19. Cementoenamel junction: the area where enamel and cementum meet at the cervical region of the tooth.
Three different relationships among the enamel and cementum:
60% to 65% of the cases the cementum overlaps the enamel
30% of the cases edge to edge
5% to 10% cementum fails to meet enamel resulting in exposed dentin

20. CEMENTOENAMEL JUNCTION
In the last case, gingival recession may result in accentuated
Sensitivity because of exposed dentin.

21. Abnormalities of cementum
Cemental aplasia or hypoplasia:
Absence or paucity of cellular cementum.
Cemental hyperplasia or hypercementosis:
Excessive deposition of cementum.
An age related phenomenon.

22. Microscopic cementum resorption Extremely common 90.5%
In the apical third of the root 76.8%
19% in the middle third
4%in the gingival third
70% confined to cementum( no dentin involvement)
Henry Jl et al.

23. Ankylosis
Fusion of the cementum and alveolar bone with obliteration Of the periodontal ligament

24. Recession :Exposure of cementum to oral environment

25. Alveolar Bone
Osseous tissue is rigid connective tissue that is normally organized into definite structures termed bone.
The alveolar process is defined as the parts of the maxilla and the mandible that form and support the sockets of the teeth

26. Alveolar Bone

27. The Alveolar Process Consist Of
1-Inner and outer cortical Plate (Compact Bone)

28. 1-compact bone include :
a-The Haversian canal
b-Volk-manns canals(blood supply)
c- Lamella and osteocyte in lacunae.

29. 2- Cancellous bone (spongy):
spongy Bone:
-Between the two compact layers
-Consist of trabeculae that enclose marrow spaces.

30. 3-The alveolar bone proper :
Bone lines the socket and extends over the alveolar crest often appears as a radiodense line, termed the lamina dura.
-Other term Bundle bone.

31. Alveolar bone consist of
Summary
Alveolar bone consist of
1- alveolar bone proper
(lamina dura in radiographs)
2- trabecular bone
3- compact bone

32. 1)Alveoli: The space in the alveolar bone that accommodate the roots of the teeth (tooth socket).

33. 2)Supporting alveolar bone: cancellous and cortical bone that surrounds the alveolar bone proper

34. 3)Interproximal bone (interdental septum): bone located between the roots of adjacent teeth. 4)Interradicular bone: bone located between the roots of multirooted teeth

35. 5)Radicular bone: alveolar process located on the facial or lingual surfaces of the roots of teeth

36. Composition of Alveolar Bone
1-The cells(osteoblast,osteoclast and osteocytes).
2-Extra-cellular matrix consists consists of two-thirds inorganic matter and one third
organic matrix.

37. CELLS OF ALVEOLAR BONE
Calcified matrix with osteocytes enclosed in lacunae
Constantly changing
Osteoblasts deposit
Osteoclasts resorb
Matrix deposited by osteoblasts is not mineralized and is termed osteoid. As new osteoid is deposited the old osteoid mineralizes.
Osteoclasts are large multinucleated cells that are often on surface or in Howship’s lacunae. Main function is resorption of bone.

38. The inorganic matrix is composed of the minerals calcium and phosphate, The organic matrix consists mainly (90%) of collagen type I, with small amounts of non collagenous proteins

39. The cortical plates and the bone lining of the socket meet at the alveolar crest, usually 2mm below the cementoenamel junction.

40. Patterns of bone destruction in periodontal disease
1-Horizontal bone loss 2-Verticl or Angular defects. 3-Osseous craters. 4-Ledges

41. FENESTRATION - isolated areas which the root is denuded of bone and root surface is covered only by periosteum and overlying gingiva
DEHISCENCE - denuded areas extend through the marginal bone

42. Fenestration: Dehiscence:
some bone present in the bone coverage
the most coronal portion is missing at the coronal portion of the roots

43. Differences Between Cementum and Bone
Cementum is not vascularized. Cementum has minor ability to remodel. Cementum is more resistant to resorption compared to bone Cementum lacks neural component Cementum contains a unique proteoglycan interfibrillar substance. 70% of bone is made by inorganic salts Cementum contains 46% of inorganic salts

44. Summary: Periodontium consists of 4 different tissues:
Gingiva
Cementum
PDL
Alveolar bone
They are anatomically separated, but functionally , they all depends on each other in maintaining a viable, healthy supporting structure for the tooth.

45. Have a nice future perio patient!