Its is about eruption of teeth

1. By: Dr Arbab Zia
erruption

2. • By the end of this lecture the student is excepted to:
• Describe different eruption movement
• Theories of eruption
Objectives
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3. • Physiological tooth movement in axial direction from tooth s developmental position in
jaw to functional position in occlusal plane is called tooth eruption
• Consists of
• Preerruptive tooth movement
• Eruptive tooth movement
• Posterruptive tooth movement
introduction
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4. • Movement of tooth in preparation to eruption is called preeruptive tooth movement
• Includes:
• bodily movement
• Great deal of space is present between tooth germs at start but with growth of tooth
germs there is crowding which is relieved by compensatory growth of jaws. Bone resorbs
on one side and deposited on other and tooth moves bodily in extra space
• eccentric movements
• Happens due to relative movement of deciduous and permanent tooth germ
• Growth of jaws
• Bodily movement
• Tooth germs one part remains stationary and other grows
Preeruptive tooth movement
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5. cont
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6. • Movement in axial direction from jaw to occlusal plane in axial direction
• Also called prefunctional phase
• Coincides with end of secretory phase during amelogenesis
• As root formation is initiated and root dentin is laid down increase in tooth size is
compensated by eruptive movement
• Shortly thereafter , cementum, pdl, and bone is formed
• Bone is removed in teeth which are about to erupt
• Teeth having deciduous predecessors have a gubernacular canal and its contents
• Permanent tooth germ in entirely closed in bony crypt except for small canal having
fibrous connective tissue and epithelial remnants of dental lamina called gubernacular
cord
Eruptive tooth movement
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7. cont
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8. • Osteoclast expand this area in preparation for erupting permanent tooth germ
• When surface epithelium is reached, oral and REE proliferate and migrate into
disorganized connective tissue to form a solid plug of epithelium
• Central cells of this epithelium degenerate and epithelium lined canal is produced
through which the tooth erupts
• Tooth continues to erupt till it reaches occlusion
cont
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9. • Movement of tooth after occlusal plane is reached
• Also called functional phase
• Maintains position of tooth as jaws grow and compensates for wear
• Mesial drift to compensate for proximal wear can account for 7 mm and involves
contraction of transseptal ligament and an anteriorly directed force
• Occlusal movement associated with occlusal wear. Cementum deposition at apical area is
infilling phenomenon
• Axial movement associated with condylar growth which separate teeth between 14-18
years
Post eruptive movement
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11. • Fibroblasts in pdl have fibronexus which includes intermediate actin contractile filaments,
fibronectin and cell to cell adheren contacts and can also phagocytize collagen material
mcq
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12. • A number of theories have been put forward but only 4 merit serious consideration
mechanism
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13. • Bone is selectively resorbed and deposited to provide an eruption pathway
• Bone remodeling cells are provided by dental follicle or bone lining cells which secrete
proteolytic enzymes under hormonal influence
• Dental follicle is necessary for bone remodeling to occurr
Bone remodeling theory
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14. • As root formation continues tooth erupts
• A fixed base is required against which root formation will result in eruption
• This fixed base was postulated to be cushion hammock ligament but in reality it is the
pulp delineating membrane and no such fixed base exist
• Points against this theory are:
• Teeth without roots still erupt
• Even if root formation is completed still teeth erupt
• Teeth erupt more than their root length
Root formation theory
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15. • Vascular pressure from pulp and pdl result in eruption
• Points in favor of this theory are:
• Teeth move in synchrony with pulse
• Ground substance swell to 50 % and result in pressure which can cause
eruption in dogs
• Hypotensive drugs increases where as symphathetic system stimulation
decreases eruption
• Fenestrated capillaries increase with eruption
• Vascoconstrictor can decrease rate of eruption
• Points against this theory are
• Even if vascular supply is cut teeth erupt and pressure is not sufficient
Vascular pressure theory
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17. • Sailor pulling a rope
• Fibroblasts have contractile property and provide contractile force on collagen bundles
attached to tooth surface
• They are attached to each other by adheren junctions and to ECM by fibronexus
• Pdl fibers are angulated and their remodeling is done by fibroblasts
• Points against this theory are that contractile nature, fibronexus and adheren junctions
are disputed.
• In reality a number of factors are responsible for tooth eruption
• Rate of eruption is 1u per day in crypt, 7.5u per day when moves out of crypt, 1mm per
day after it appears in oral cavity
Pdl traction theory
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19. • Mononuclear cells are recruited at dental follicle
• They differentiate into bone remodeling cells
• Bone is resorbed at coronal half of dental follicle and formed as base
• Dental follicle is not only target site for cells but also regulates eruption
Cellular events
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20. • Eruption is localized genetically programed event
• Dental follicle has genes that encode various molecules which result in interaction of
dental follicle and bone remodeling cells
• TGF beta, EGF, CSF-1, monocyte chemotactic protein 1 increase rate of eruption
• PTHrp, VEGF and IL-1 alpha present in stellate reticulum regulate activity of osteoclasts
thus stellate reticulum also has a role in eruption
• OPG interferes with binding of RANKL to RANK receptor on mononuclear cells regulating
osteoclast function
• Corebinding factor a 1, ODF controls osteoblastic differentiation
• MMP and its inhibitors secreted by dental follicle degrade ECM
• Stellate reticulum secrete PTHrp, IL I, TGF beta. Rest by dental follicle
Molecular events
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21. • Neonatal or natal teeth
• Prism structure is absent, cementum is missing and
Dentin is atubular or with giant tubule
• Premature deciduous tooth loss may result in early eruption
• Delayed eruption
• Due to nutrition, genetics, endocrine abnormalities, bone diseases
• Blocking of eruption path way by drifted teeth, ankylosis, cyst, fibrous tissue
• Impacted teeth
• Defects in genes such as CSF-1 lead to eruption problems
• When teeth is erupting there is inflammation and baby has fever with malaise
• Supra erupted teeth
Clinical considerations
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22. • Variation in eruption timing
• Aspirin, brufin which block PG pathway may delay eruption
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23. • ORBANS 13th edition
• Ten cates 8th edition
• Berkowitz 4th edition
• Internet
References
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24. Thank You