Deciduous- 20 teeth- emerge about 7 mos- shed between 6th 13th yearSuccedaneous (Permanent)- 32 teeth- full dentition is achieved usually at 18 yrs old
IncisorsCutting & shearingCanines- Puncturing & holdingPremolarsMolarsCrushing & grinding
Hard portionsDentinEnamelCementumSoft portionsPulpPeriodontal ligamentGingiva
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
Radially striatedDentinal tubulesApical process of Odontoblasts
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
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
Lines of Schreger- alternate light and dark bands of enamel prisms (oblique)
Lines of Retzius- concentric lines- rhythmic deposition & mineralization of enamel
Covers the rootClosely resembles boneComposed of: collagen, glycoproteins & mucopolysaccharidesCementoblasts- in unmineralized matrix at the surface of the rootCementocytesDevelops Haversian system with aging
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
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
Blood vesselsthrough apical foramenLymphatic vesselsNerve fibersMyelinated & unmyelinated nervesSensory
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
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
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
Function:- attachment of teeth- aids in resisting pressure on teeth during mastication- source of blood calcium
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