lecture 6 ABNORMALITIES OF TEETH

lecture 6 ABNORMALITIES OF TEETH

1. Enviromental Alterations of Teeth

   • 1- Environmental effects on tooth structure development:
     • formation of enamel or dentin
       • The ameloblasts are extremely sensitive to external stimuli
     • ENAMEL
       • ENAMEL remodeling does NOT occur after initial formation / abnormalities are permanent.
         • The enamel develops stages
           • 1) Matrix formation: enamel proteins laid down. 2) Mineralization: minerals deposited and majority of original proteins removed. 3) Maturation: final mineralization and remnants of original proteins removed.
         • TIMING >>>
           • AFFECTS the location and severity
       • environmental enamel defects
         • Hypoplasia
           • quantitative defect./ form of pits, grooves, or larger areas of missing enamel.
           • it does actualy means that mineralization improper (less than normal ) hypomineralization
         • Enamel opacities
           • Diffuse
             • increased white opacity with no clear boundary
           • Demarcated
             • decreased translucence, increased opacity, and a sharp boundary
           • Yellow or brown opacities are more porous than white opacities+ more strongly associated with post-eruptive loss of enamel.
       • A common pattern is seen as a result of systemic influences
         • exanthematous fever
           • first 2 years of life. - Horizontal rows of pits or diminished enamel
             • on anterior teeth and first molars
               • Enamel loss is bilaterally symmetric / similar pattern of enamel defects can be seen in the cuspids, bicuspids, and second molars at age of 4 to 5 years.
       • • 1- Turner Hypoplasia/ turner tooth:
           • on permanent teeth
             • caused by periapical inflammatory disease or traumatic injury of the overlying deciduous tooth
               • most frequently in the permanent bicuspids (premolars) bc relationship to deciduous molars
                 • Anterior teeth are involved less frequently.
           • vary from focal areas of white, yellow, or brown discoloration to extensive hypoplasia can involve the entire crown.
         • 2- Molar Incisor Hypomineralization (MIH)
           • first molar / incisors >>>
             • incisors only white opacities that primarily create aesthetic problems.
           • sharp demarcation
             • very difficult to anesthetize.
               • Yellow/brown opacities << porous<< post-eruptive enamel loss chipping of dentin<< more sensitive<< avoidance of proper oral hygiene <<rapid caries development.
           • multifactorial.
             • Nutrition
             • Birth and neonatal factors
             • childhood illnesses
             • High fever
             • Antibiotics
             • Environmental toxins
             • Long duration of breast feeding
             • Fuoride
         • • 3- Hypoplasia Caused by Antineoplastic Therapy:
             • degree and severity
               • age at treatment,
               • form of therapy
               • dose and field of radiation
             • chemotherapy <severity<radiotherapy
               • even low doses of both could cause deffect in dentine and enamel
                 • Stunting of the mandibular
                   • chemotherapy + radiotherap:. V-shaping and shortening in the roots and alveolar bone loss in the mandible
                     • chemotherapy +radiotherapy : tapering PM/ blunted canine
             • alterations
               • Hypo+microdontia.
               • Radicular hypoplasia
               • Enamel hypoplasia
               • radiotherapy +
                 • mandibular hypoplasia + reduction vertical development of the lower third of the face.
                   • mandibular hypoplasia :direct - from radiation // indirect - growth failure<<altered pituitary function<< cranial radiation
               • chemotherapy alone
                 • less dramatic alterations enamel hypoplasias and discolorations, slightly smaller tooth size, and occasional radicular hypoplasia.
                   • chemotherapy : microdontia of maxillary and mandibular second premolars and second molars
           • 4- Dental Fluorosis
             • excess amounts of fluoride
               • enamel defects<<retention of the amelogenin proteins in the enamel structure<<hypomineralizedwhite<<chalky areas. so it's hypomineralization+ hypoplasia
                 • past <<moderate to severe enamel fluorosis<< mottled enamel.
             • definitive diagnosis requires:
               • bilaterally symmetric distribution of defects
               • excessive fluoride intake, or elevated levels of fluoride in enamel or other tissues.
             • Close monitoring of all sources of fluoride intake during the first 3 years
               • reduction in dental fluorosis can be seen if brushing with fluoride toothpaste does not start until after 12 months of age
                 • reconstitution of infant formula with fluoridated water should be avoided.
           • • 5- Syphilitic Hypoplasia:
               • STD / TRANSM TO EMBRIO
               • affected teeth
                 • anterior
                   • Hutchinson incisors:
                     • rowns shaped like straight-edge screwdrivers, with greatest circumference present in middle third and a constricted incisal edge. o Middle portion of incisal edge often demonstrates a central hypoplastic notch
                 • posterior
                   • mulberry molars:
                     • o Constricted occlusal tables. o Disorganized surface anatomy that resembles the surface of a mulberry
   • 3-Environmental discolorations of teeth 4-Localized disturbances in eruption
   • 2- Post-developmental structure loss
     • aTTrition
       • Tooth-Tooth
       • factors
         • > Poor-quality or absent enamel (e.g., fluorosis, environmental or hereditary enamel hypoplasia, or dentinogenesis imperfecta)
         • > Premature contacts (edge to edge occlusion)
         • > Intraoral abrasives, erosion, and grinding habits
       • clinically
         • deciduous and permanent
         • incisal and occlusal
         • Large, flat, smooth, and shiny
         • anteriors
           • maxillary
             • lingually
           • mandibular
             • labially
         • this interproximal loss can result in a shortening of the arch length.
           • Pulp exposure
           • mesial of the permanent first lower molar wears faster than the distal of the primary second molar
     • ABRAsion
       • mechanical action of an external agent.
       • causes
         • toothbrushing .horizontal brushing stroke
           • horizontal cervical notches on the buccal surface of exposed radicular cementum and dentin
             • sharply defined margins and a hard, smooth surface.
         • pencils, toothpicks, pipe stems, and bobby pins / Chewing tobacco, cracking nuts and seeds, biting fingernails or thread
           • rounded or V-shaped notches in the incisal edges of anterior teeth
         • dental floss
           • interproximal radicular cementum and dentin.
       • acid<< more rounded and shallower.
         • degree of loss is greatest on prominent teeth (i.e., cuspids, bicuspids, and teeth adjacent to edentulous areas
     • Erosion
       • chemical
       • Salivary buffering low flow rates: therapeutic radiation, certain medications, and Sjögren syndrome
       • clinically
         • teeth
           • Facial and palatal surfaces of maxillary anterior
             • shallow spoon-shaped depressions in the cervical portion of the crown
               • When palatal surfaces are affected, the exposed dentin has a concave surface and shows a peripheral white line of enamel
           • facial and occlusal surfaces of mandibular posterior teet
             • a concave depression of dentin surrounded by an elevated rim of enamel.
         • central depression of dentin is surrounded by elevated enamel.
         • limited to the facial surfaces of the maxillary anterior teeth is often associated with dietary sources of acid
           • confined to incisal portions of anterior teeth of both arches, an external environmental source is suggested
           • palatal surfaces of maxillary anterior teeth and occlusal surfaces of posterior teeth of both arches, regurgitation of gastric secretions is a probable cause

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