Cementum

Cementum also commonly known as root cementum , is a highly mineralized tissue covering the entire root surface.
Cementum is also often referred to as a bone-like tissue. Cementum contains two types of fibers, mainly extrinsic (Sharpey's) fibers and intrinsic fibers. Fibroblasts and cementoblasts are the fiber secreting cells.

1. CEMENTUM DR. OINAM MONICA DEVI

2. CONTENTS 1. Introduction And Definition 2. History 3. Physical Characteristics 4. Functions Of Cementum 5. Formation Of Cementum ( Cementogenesis ) 6. Cementoid Tissue 7. Incremental Lines In Cementum 8. Classification Of Cementum 9. Mineralisation 10. Biochemical Composition

3. 11.Thickness Of Cementum 12.Cementoenamel Junction 13.Cementodentinal Junction 14.Age Changes  15. Cementum Resorption And Repair  16.Alterations Resulting From Periodontal Pathology 17.Hypercementosis 18.Alterations In Cementum   19.Neoplasm associated with Cementum 20.Applied Anatomy of Cementum on Periodontal health   21.References  

4. INTRODUCTION Derived from Latin “ caementum ”, quarry stone. Component of tooth as well as periodontium . Provides anchorage for collagen fibre bundles of periodontal ligament and supra-alveolar fibres of the gingiva . Root surface area covered by it represents the ground available for connective tissue attachment. Present irrespective of functional status.

5. DEFINITION It is the calcified, avascular , mesenchymal tissue that forms the outer covering of the anatomic root. [ CARRANZA ] Cementum is a hard, avascular connective tissue that covers the roots of teeth. [ TEN CATE’S]

6. HISTORY

7. PHYSICAL CHARACTERISTICS

8. FUNCTIONS OF CEMENTUM

9. CEMENTOGENESIS (Formation of Cementum ) - Pre-functional Developmental Stage During root development. Time range 3.75 to 7.75 years. -Functional Developmental Stage Commences when tooth reaches the occlusal plane. Continues throughout the life.

10. -Initiation of Cementum Formation Restricted 200-300 micrometer coronally from the advancing root end. -Origin of Cementoprogenitor Cells 1.) From the Dental Follicle 2.) From Hertwig’s E pithelial R oot Sheath[HERS]

11. Hertwig’s epithelial root sheath: inner and outer epithelium Send an inductive message to the facing ectomesenchymal cells of pulp Odontoblasts develop and P redentin layer forms Epithelial root sheath interrupted, cells of dental follicle in contact with predentin form cementoblasts CEMENTUM FORMS

12. CEMENTOBLASTS Cementoblasts derived from dental follicle involved in the formation of Cellular Intrinsic Fiber Cementum (CIFC). Cementoblasts derived from HERS involved in the formation of Acellular Extrinsic Fiber Cementum (AEFC). Some cementoblasts get entrapped and are called Cementocytes . Cementocytes are present in spaces called lacunae. Present in the deeper layers are non viable as the distance from the surface increases and diffusion of nutrients decreases.

13. Some key molecules in the Periodontium GROWTH FACTORS Transforming growth factor Platelet derived growth factor Insulin like growth factor Promote cell differentiation during cementogenesis ADHESION MOLECULES Bone sialoprotein Osteopontin Promote adhesion of selected cells to newly forming root EPITHELIAL/ ENAMEL PROTEINS Promote follicle cells along cementoblasts pathway COLLAGENS Types-I , II,I XII regulate periodontal tissues during development and regeneration GLA PROTEINS Matrix Gla Protein/ Bone Gla Protein Prevent abnormal ectopic calcification TRANSCRIPTION FACTORS Runt-related transcription factor 2 Osterix Cementoblast differentiation SIGNALLING MOLECULES Osteoprotegerin Receptor activated kappa B Ligand Mediate bone and root resorption by osteoclasts CEMENTUM-SPECIFIC PROTEINS Cementum Protein 1 Local regulator of cell differentiation and extracellular matrix mineralisation

14. CEMENTOID Under normal conditions, growth of cementum is a rhythmic process and as a new layer of cementoid is formed, the old one calcifies. A thin layer of cementoid can usually be observed on the cemental surface and lined by cementoblasts . Connective tissue fibers from the periodontal ligament pass between the cementoblasts into the cementum .

15. INCREMENTAL LINES OF CEMENTUM Incremental lines , seen in cementum (Lines of Salter ) , as during the process of cementogenesis . In cementogenesis, there are periods of rest and periods of activity. The periods of rests are associated with these lines. The lines are closer in acellular cementum as this cementum is formed slow.

16. CLASSIFICATION OF CEMENTUM

17. Presences & Absence Of Cells ACELLULAR CEMENTUM CELLULAR CEMENTUM 1.Found on cervical third of tooth. Mainly seen at apical third and inter radicular area though a thin layer is present all over root. 2.Embedded cementocytes are absent. Embedded cementocytes are present. 3.Deposition rate is slower. Deposition rate is faster. 4.First formed layer Formed after acellular cementum . 5.Width is more or less constant. Highly variable. 6.Sharpey’s fibres are well mineralised . Sharpey’s fibres are partially mineralised . 7.Incremental lines are regular and closed packed. Irregular and placed wide apart.

18. Based On Location

19. Origin Of Fibres EXTRINSIC FIBERS INTRINSIC FIBERS 1. Derived from PDL Derived from C ementum . 2. Formed by F ibroblast . Formed by C ementoblast . 3.Run in same direction of the PDL principal fibers i.e. perpendicular or oblique to the root surface. Run parallel to the roo t s u rface and at right angles to the extrinsic fibers.

20. Presence / Absence Of Fibres Fibrillar Cementum : Cementum with a matrix that contains well-defined fibrils of type I collagen. Afibrillar Cementum : Cementum that has a matrix devoid of detectable type I collagen fibrils. Instead, the matrix tends to have a fine, granular consistency.

21. SCHROEDER & PAGE CLASSIFICATION (1986) Classified CEMENTUM on the basis of : Location Morphology Histological Appearance

22. 1.Acellular Afibrillar Cementum (AAC) 2.Acellular Extrinsic Fiber Cementum (AEFC) 3.Cellular Intrinsic Fiber Cementum (CIFC) 4.Cellular Mixed Stratified Cementum (CMSC) 5.Intermediate Cementum

23. 1-15 um 30-230 um

24. MINERALISATION Mineralization begins in the depth of precementum . Fine hydroxyapatite crystals are deposited, first between and then within the collagen fibrils by a process that is identical to the mineralization of bone tissue. Zander & Hurzeler examined the thickness of cementum on extracted human teeth from individuals of varying ages & concluded that the mean, linear rate of cementum deposition on single-rooted teeth is about 3 µm per year (but varying greatly with tooth type, root surface area, and type of cementum being formed).

25. A similar rate has been found for acellular extrinsic fiber cementum in premolars and in nonfunctioning, impacted teeth. The width of the precementum layer is about 3-5 µm. Process of establishing the appropriate condition for crystallization & growth of the individual crystals in cementum normally are extremely slow and extend over a period of several months. CMSC-LOWER MINERAL CONTENT THAN AEFC.

26. BIOCHEMICAL COMPOSITION

27. CEMENTUM PROTEINS - Glycosaminoglycans (GAGs): Proteoglycans creates the cemental incremental lines only in cellular cementum . Major GAGs: hyaluronic acid, dermatan sulfate, chondratin sulfate & keratan sulfate. Play major regulatory roles during cementum mineralization and are associated with initial phase of cementum formation.

28. -Bone Sialoprotein & Osteopontin : Play a major role in filling spaces created during collagen assembly. Regulators of hydroxyapatite crystal nucleation and growth. Role in differentiation of cementoblast progenitor cells to cementoblasts . Osteopontin regulates cell migration, differentiation & survival. Sialoprotein modulates the process of cementogenesis & is involved in the process of chemoattraction , adhesion & differentiation of pre- cementoblasts .

29. -Alkaline Phosphatase : Play important role in skeletal mineralization. Regulate tissue turnover & cell proliferation, differentiation, maturation. Major function: hydrolysis of inorganic pyrophosphate, a potent inhibitor of hydroxyapitite formation. Plays key biological role in the mineralization of bone & cementum .

30. CEMENTUM SPECIFIC PROTEINS Cementum - Derived Growth Factor: Insulin- like ,growth factor-1 like molecule. Repair or regulate tissues. Ability of cell migration, adhesion, mitogenic activity & differentiation, essential for periodontal regeneration. Cementum has the potential to regulate the metabolism & turn over of surrounding tissues because of this growth factor.

31. Cementum Attachment Protein (Cap): Promotes the attachment of gingival fibroblasts , endothelial cells & smooth muscle cells, but not oral sulcular epithelial cells . Capacity to direct cell migration of alveolar bone cells. Binds selectively to periodontal ligament cells and supports periodontal ligament cell attachment to root surfaces.

32. Enamel- Associated Proteins In Cementum : Synthesized by Hertwig’s epithelial root sheath cells. Results in the formation of a cellular- like tissue or bone with the characteristics of cellular intrinsic fiber cementum . Functions: promotion of cell proliferation, differentiation & up-regulation of extracellular matrix production. Involved in root formation .

33. Osteonectin Mainly secreted by osteoblasts . Important for mineralization process. Found in the PDL. Osteocalcin Also known as bone Gla protein as it contains carboxyglutamic acid ( Gla ) residues. Mainly secreted by osteoblasts ( Mariotti , 1993), regulate mineralization process, prevent hypercalcification of the cementum surface.

34. MINERAL COMPONENT Magnesium : 0.5- 0.9% , half than dentin, more in deeper layers. Fluoride : 0.9% weight more on surface layer and more in apical cementum Sulfur: 0.1-0.3% as a constituent of organic matrix.

35. THICKNESS OF CEMENTUM 16-60µm coronal half = 16-60µm apical third and furcation = 150-200 µm Thicker on distal than on mesial surfaces. Between 11 to 70 years of age, thickness increases 3 times. Cemental deposition continues throughout life. Deposition most rapid in apical areas.

36. CEMENTOENAMEL JUNCTION Vandana and Haneet : Cementoenamel junction: An insight,2019 60% = cementum overlaps the cervical end of enamel 30% = cementum meets the cervical end of enamel 10% = enamel and cementum do not meet 1.6% = enamel overlaps cementum

37. VARIOUS METHODS OF CEJ LOCATION CONVENTIONAL METHODS Visual Tactile By straight explorer By periodontal probe Radiographic : Intraoral periapical (IOPA) radiograph Bite wings RVG MODIFIED METHODS Computer linked electronic constant pressure probes Florida probe Inter probe/ Perio probe Birek probe/Toronto automated probe Jeff coat probe/Foster miller probe.

38. CEMENTODENTINAL JUNCTION The terminal apical area of cementum where it joins the internal root dentin is called cementodentinal junction (CDJ). The nature of CDJ is of particular importance, being of interest biologically because it forms an interface (a fit) between two very different mineralized tissues. Clinical importance - Involved in the processes maintaining tooth function while repairing a diseased root surface. Width of CDJ is 2 to 3µm and remains relatively stable .

39. CEMENTIODENTINAL JUNCTION Smooth in permanent teeth Scalloped in deciduous teeth

40. AGE CHANGES CONTINOUS DEPOSITION Forms on roots throughout life. More apically than cervically . Reduces root surface concavities thicker layer in root surface grooves and in furcations . Variation in tooth position influence pattern of deposition.

41. Cementum although is less susceptible to resorption than bone. Resorption is carried out by multinuclear odontoclasts & may continue into the root dentine. SYSTEMIC FACTORS –Calcium deficiency –Hypothyroidism –Hereditary fibrous osteodystrophy , –Paget's disease. IDIOPATHIC LOCAL FACTORS –Trauma from occlusion. – Orthodontic movement –Pressure from malaligned erupting teeth, –Cysts and Tumors –Teeth without functional antagonists; –Embedded teeth; –Replanted and transplanted teeth; – Periapical and periodontal disease

42. MICROSCOPICALLY: Bay like concavities in the root surface. Multinucleated giant cells and large mononuclear macrophages found. Newly deposited cementum is demarcated from old by deeply staining irregular line k/a Reversal line. Reversal line has few collagen fibrils and highly accumulated proteoglycans with mucopolysaccharides .

43. REPAIR Needs viable connective tissue. If epithelium proliferates no repair. Origin of Cementoblasts and factors regulating their recruitment not understood. Only odontogenic cells in PDL Epithelial rests of Malassez

44. ALTERATIONS RESULTING FROM PERIODONTAL PATHOLOGY 1.EFFECT OF GINGIVAL INFLAMMATION Loss of collagen fibres of the gingiva Dissolution of mineral crystals Cervical root resorption

45. 2.EXPOSURE OF CEMENTUM TO ORAL ENVIRONMENT Non-carious cementum is permeable to organic and inorganic ions. Bacterial invasion is common. Bacterial lipopolysaccharides detected . Hypermineralized surface zone depends on the inorganic ion concentration.

46. CHANGES ASSOCIATED WITH PERIODONTAL POCKETS

47. ALTERATIONS IN CEMENTUM

48. ANKYLOSIS Fusion of cementum and alveolar bone with obliterated PDL. Occurs in teeth with cemental resorption . After periodontal inflammation, tooth replantation , occlusal trauma. Resorption of root and its gradual replacement by bone. Lack physiological mobility, metallic percussion. No proprioception .

49. CONCRESCENCE Fusion of teeth by cementum . After root formation has been completed. Traumatic injury or crowding of teeth with resorption of the interdental bone. Difficulty in extraction.

50. ROOT CARIES Initiates on mineralized cementum and dentin surfaces which have greater organic component than enamel tissue. Occurs most frequently on the buccal and lingual surfaces of roots.

51. ABRASION Pathologic wearing of tooth substance through some abnormal mechanical process. Occurs on the exposed root surfaces of teeth, but under some circumstances, it may be seen elsewhere on tooth. Abrasion caused by dentrifrice manifests as a “V-shaped or wedge shaped” ditch on the root side of CEJ in teeth with recession.

52. CEMENTICLES Abnormal, calcified bodies in the periodontal ligament Form from remnants of HERS Usually ovoid or round Size ranges from 0.1- 0.4 mm Classified as Free, Attached or Embedded Local trauma Appear in increasing numbers in the aging person

53. ENAMEL PEARLS If some HERS cells remain attached to forming root surface, they can produce focal deposits of enamel like structures called ENAMEL PEARLS. CLINICAL SIGNIFICANCE: Plaque retentive structures. Promote periodontal disease. Look similar to calculus, but cannot be scaled off. Only grinding will help in elimination .

54. CEMENTAL TEARS Small spicules of cementum torn from the root surface—i.e. cemental tears—or fragments of bone detached from the alveolar plate If found lying free in the periodontal ligament CEMENTAL TEARS may resemble cementicles , particularly after they have undergone some remodeling through resorption and subsequent repair.

55. ENAMEL PROJECTIONS Common tooth anomaly that can act as a contributing factor in the development and progression of periodontitis . Flat, ectopic deposits of enamel apical to the normal cemento -enamel junction (CEJ) level in molar furcation areas. Triangular shape and a tapering form. Extend apically into furcation areas. Most commonly found at the buccal surfaces of mandibular molars.

56. Classification of Cervical enamel projection (Masters and Hoskins 1964) Grade I: The enamel projection extends from the CEJ of the tooth toward the furcation entrance. Grade II: The enamel projection approaches the entrance to the furcation . It does not enter the furcation and therefore no horizontal component is present. Grade III: The enamel projection extends horizontally into the furcation .

57. HYPERCEMENTOSIS Non- neoplastic deposition of excessive cementum that is continuous with the normal radicular cementum . Factors Associated with Hypercementosis LOCAL FACTORS Abnormal occlusal trauma Adjacent inflammation Unopposed teeth [e.g., impacted, embedded, without antagonist) SYSTEMIC FACTORS Neoplastic and non- neoplastic conditions including benign cementoblastoma Cementifying fibroma Cemental dysplasia Acromegaly and pituitary gigantism Paget's disease of bone Rheumatic fever Thyroid goiter

58. Acceleration in the elongation of a tooth owing to loss of an antagonist is accompanied by hyperplasia of the cementum . This hypercementosis is most prominent in the apex of the root. Inflammation in the root apex, as a result of pulpal infection ,sometimes, stimulate excess deposition of cementum . Cementum is laid down on the root surface at some distance above the apex. Occlusal trauma results in mild root resorption . Such resorption is repaired by secondary cementum .

59. CLINICAL FEATURES: Occurs predominantly in adulthood & the frequency increases with age. Occurrence has been reported in younger patients with familial clustering demonstration suggesting hereditary influence. RADIOGRAPHIC FEATURE: Affected teeth demonstrate a thickening or blunting of the root . Radiolucent shadow of PDL and radiopaque lamina dura always seen. NO TREATMENT REQUIRED.

60. NEOPLASMS ASSOCIATED WITH CEMENTUM

61. CEMENTOBLASTOMA

62. CEMENTIFYING FIBROMA Resemble focal cemento-osseous dysplasia. The neoplasm is composed of fibrous tissue that contains a variable mixture of bony trabeculae , cementum like spherules or both. Origin - Odontogenic or from PDL. CLINICAL FEATURE: 3 rd &4 th decades, female predilection. Most common site- mandibular premolar and molar area. Seldom cause any symptoms and are detected only on radiographic examination.

63. Radiographically , the lesion most often is well defined and unilocular . TREATMENT: Enucleation of the tumor.

64. PAGET’S DISEASE Characterized by enhanced resorption of bone. Etiology: unknown, viral infection, inflammatory cause, autoimmune, connective tissue and vascular disorder. CLINICAL FEATURES: Middle age and both males and females are effected. Involvement of facial bone- LEONTIASIS OSSEA. MAXILLA- progressive enlargement, alveolar ridge widened, palate flattened, tooth become loosened. MANDIBLE: findings are similar but not as severe as maxilla. GENERALISED HYPERCEMENTOSIS of the tooth seen. RADIOGRAPHIC FINDING: COTTON-WOOL appearance of paget’s bone. CHARACTERISTIC HISTOLOGIC FEATURE: JIGSAW OR MOSAIC PATTERN. TREATMENT: No specific treatment.

65. HYPOPHOSPHATASIA Rare metabolic bone disease that is characterized by a deficiency of tissue -nonspecific alkaline phosphatase . One of the first presenting sign may be the premature loss of the primary teeth caused by a lack of cementum on the root surfaces. The histopathologic examination of either a primary or permanent tooth that has been exfoliated from an affected patient often shows an absence or a marked reduction of cementum that covers the root's surface. TREATMENT: Symptomatic because the lack of alkaline phosphatase cannot be corrected

66. HYPERPITUITARISM Gigantism is the childhood version of growth hormone excess and is characterized by the general symmetrical overgrowth of the body parts. - Prognathic mandible, frontal bossing, dental malocclusion, and interdental spacing are the other features. -Intraoral radiograph may show hypercementosis of the roots. Acromegaly is characterized by an acquired progressive somatic disfigurement, mainly involving the face and extremities, but also many other organs, that are associated with systemic manifestations. -Dental radiograph may demonstrate large pulp chambers and excessive deposition of cementum on the roots.

67. APPLIED ANATOMY OF CEMENTUM ON PERIODONTAL HEALTH Cementum is the site where soft-tissue attachment has to be re-established. Cementum matrix is a rich source of many growth factors which influence the activities of various periodontal cell types (Narayanan and Bartold , 1996; Saygin et al., 2000 )

68. Alteration in the biochemical composition of cementum during periodontal disease results in loss of active substances and deposition of inhibitors such as endotoxins . Diseased cementum inhibits connective tissue cell attachment and growth and promotes epithelial attachment ( Terranova and Martin, 1982;Polson , 1986 ) T his was the rationale for new therapeutic approaches in which diseased roots are conditioned to promote connective tissue attachment ( Bartold et al ., 2000 ).

69. POSSIBLE ROLE OF CEMENTUM IN REGENERATION Cementum And Periodontal Wound Healing And Regeneration by Wojciech J. Grzesik , A.S. Narayanan , 2002

70. Preservation of root cementum as a goal in periodontal therapy may be an important factor to avoid root structure loss and dentin hypersensitivity in maintenance patients and to prevent root resorption. R oot cementum may act in three directions, associated or not, as 1) A source of growth factors from its matrix. 2) Barrier , avoiding the undesirable interaction of dentin matrix proteins with the healing site. 3) By cementoblast modulation of cementum regeneration .

71. REFERENCES Carranza’s Clinical Periodontology (9 TH Edition): Carranza F. A, Newman M.G., Takei H.H. and Klokkevold P.R. Clinical Periodontology And Implant Dentisitry (5 TH Edition): Jan Lindhe , Niklaus P. Lang and Thorkild Karring tion Orban’s oral histology and embryology- 13th Edi Nanci A: Periodontium . Ten Cate’s Oral Histology: Development,Structure , and Function, 8th ed. Elsevier, 2008. Bosshardt DD, Selvig KA. Dental cementum : the dynamic tissue covering of the root. Periodontol 2000 1997; 13: 41-75 The Periodontium - Schroeder Shafer’s textbook of oral pathology-7 th edition

72. Oral and Maxillofacial Pathology,4th  Edition.By  Neville Diekwisch TG, Thomas GH:Developmental Biology of Cementum . Int. J. Dev. Biol. 45: 695-706 (2001) Patricia Furtado Gonçalves.et al. Dental cementum reviewed: development, structure,composition,regeneration and potential functions. Braz J Oral Sci. January/March 2005 - Vol.4 - Number 12 Kharidi Laxman Vandana , Ryana Kour Haneet.Cementoenamel junction: An insight.J Indian Soc Periodontol 2014;18:549-54. Aggarwal P, Saxena S, Bansal P. Incremental lines in root cementum of human teeth: An approach to their role in age estimation using polarizing microscopy. Indian J Dent Res 2008;19:326-30. Zenóbio,E.G ., Vieira T.R.,R.P.C., Bustamante,H.E ., Gomes,Shibli,J.A .,& Soares,R.V (2015).Enamel Pearls Implications on Periodontal Disease.Case reports in dentistry,2015.  

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