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Deciduous- 20 teeth- emerge about 7 mos- shed between 6th 13th yearSuccedaneous (Permanent)- 32 teeth- full dentition is achieved usually at 18 yrs old
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IncisorsCutting & shearingCanines- Puncturing & holdingPremolarsMolarsCrushing & grinding
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Hard portionsDentinEnamelCementumSoft portionsPulpPeriodontal ligamentGingiva
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Similar to bone in composition20% organicCollagen fibers80% inorganic92% crystals of hydroxyapatite
Sensitive to touch, cold & acid-containing food- nerves from pulp extending for some distance to dentin- transmission of sensory stimuli by odontoblast processes
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Radially striatedDentinal tubulesApical process of Odontoblasts
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Occurs at the mineralization front (predentin to dentin)Deposition of globular aggregates of crystals of hydroxyapatiteOccur along or within collagen fibersInterglobular spaces occasional angular spaces containing organic matrix only
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Hardest substance in the body99% mineral (hydroxyapatite crystals)1% organic (amelogenins & enalamins- high proline & phosphorus content)Consists of thin enamel rods or prismsAmeloblasts- secrete enamel matrix- with apical extensions (Tomes process)- contain secretory granules- covers the crown after the synthesis of enamel until eruption
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Lines of Schreger- alternate light and dark bands of enamel prisms (oblique)
Lines of Retzius- concentric lines- rhythmic deposition & mineralization of enamel
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Covers the rootClosely resembles boneComposed of: collagen, glycoproteins & mucopolysaccharidesCementoblasts- in unmineralized matrix at the surface of the rootCementocytesDevelops Haversian system with aging
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Envelops the rootBetween Cementum & Alveolar boneMade up of dense layer of collagenOblique upward arrangement from cementum to boneMore fibroblasts & blood vessels than other ligaments in the bodyFunction:1. anchor tooth to its socket2. provide limited degree of movement
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Occupies the central cavityFrom tissue that formed the dental papilla during embryonic developmentCells:1. Stellate cells- communicate with each other and odontoblasts via gap junctions2. WBCs- lymphocytes, macrophages, plasma cells, eosinophilsZone of Weil cell-free area near the odontoblasts lining the pulp cavity
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Blood vesselsthrough apical foramenLymphatic vesselsNerve fibersMyelinated & unmyelinated nervesSensory
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Mucous membrane lining the outer surface of alveolar bone Epithelium : keratinizing stratified squamous- lacks stratum granulosum- exhibits parakeratosisattached to the enamel (cuticle), cementum & periodontal ligament (hemidesmosomes)- epithelial attachment of Gottlieb
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Lamina propria- firmly bound to the periosteum of alveolar bone- contains lymphocytes & PMNsFree gingiva(marginal gingiva)- less firmly attached, within 1mm of a toothGingival crevice(sulcus)- shallow furrow separating the free gingiva from the enamel- unkeratinized- lacks connective tissue papilla
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Components:- cancellous bone- cortical bone (2 layers)> outer: continuation of cortex of mandible/maxilla> inner: surrounds the root and forms the socket- Source of blood vessels & nerves in the pulp cavity
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Function:- attachment of teeth- aids in resisting pressure on teeth during mastication- source of blood calcium
