Distinctions not valid as disturbances in matrix formation also give rise to disturbances in mineralization &/or maturation.
Two thirds enamel hypoplasia involving permanent dentition during first 10 months so 1st molars, incisors (except mx lat) & canines. Opacities smooth surfaced but some mottled w uneven surface and brown. Chromosomal anomalies (Down syndrome trisomy 21), infectious (viral - teratogenic changes due to rubella appears to be incr incidence of enamel defects in primary tooth, bacterial - congenital syphilis ‘Hutchinson’s incisors’ i.e. permanent incisors where mesial and distal surfaces taper to produce screwdriver-shaped tooth w a notched incisal edge and/or mulberry molars, 1st molars w irregular coronal surface), nutritional disturbances (deficiency in vitamin D ‘rickets’ & excess vitamin D, nutritional factors e.g. calcium, phosphorous, magnesium, protein or lack), fluorosis (lustreless, opaque white patches show mottling, striations and/or pits, areas may become brown w time, hormonal disturbances (hypothyroidism, hypoparathyroidism & diabetes), infection and trauma (disturbance in enamel formation in successional permanent, cementum deposition on crown, hypoplastic or hypocalcified permanent tooth 'Turner’s tooth’).Amelogenesis imperfecta - Hypoplastic (decr enamel, thin yellow-brown colour ‘dentine’, lacks prismatic structure), hypomineralized (newly erupted normal shape/size but enamel fractured bc softness, surface uneven & soft dark brown), hypomaturation (pierced by explorer & brittle, e.g. pigmented Polynesian enamel)
Dentinogenesis imperfecta: deposition of abnormal ground substance.
Odontomes: anomalies of development classified as benign odontogenic neoplasms.
Disturbances in Tooth Eruption-
Premature eruption: natal & neonatal teeth (natal present @ birth & neonatal erupt first 30 days, incisors 4x more common in mand than maxilla. 1 or 2. Loose due to lack root formation. Familial pattern, enamel hypoplasia & more cervical dentine irregular & contains inclusions), permanent (premature loss of deciduous)
Delayed eruption: primary teeth (rare, rickets & cleidocranial dysostosis), permanent teeth (localized, early loss primary or displacement tooth germ. Generalised delayed eruption in cleidocranial dysostosis, pituitary dwarfism, hypothyroidism & Down syndrome)
Embedded & impacted teeth: embedded – unerupted bc lack eruptive force & impacted – prevented by barrier, if teeth erupt because of imbalance in forces refer to same thing.
Submerged Deciduous Teeth: deciduous 2nd molar more mand, normal resorption roots ceases & roots fused to bone (ankylosis). Growth in height of alveolar bone cease but neighbouring teeth continue to move occlusally carrying alveolar bone w them ankylosed tooth appear submerging, cause not known but trauma or infection.