Amelogenesis Imperfecta represents a group of hereditary defects of enamel unassociated with any other generalized defects. It is entirely an ectodermal disturbance , since the mesodermal components of the teeth are basically normal.
The term amelogenesis imperfecta is reserved for hereditary defects of enamel that are not associated with defects in other parts of the body or other health problems. The enamel defects are highly variable and include abnormalities that are classified as hypo plastic ,hypo maturation, and hypo calcified. The enamel in both the hypo maturation and hypo calcified AI types is not mineralized to the level of normal enamel and can be described as hypo mineralized. AI can be inherited as an x-linked, autosomal recessive (AR), or autosomal dominant (AD) condition.
Dental enamel is a highly mineralized tissue with over 95% of its volume occupied by unusually large, highly organized, hydroxyapatite crystals. The formation of this highly organized and unusual structure is thought to be rigorously controlled in ameloblasts through the interaction of a number of organic matrix molecules that include
Orthodontic therapy may be used to partially close the interdental spaces prior to restoration in those individuals having small square shaped incisors and interdental spacing that is too excessive to close with restorative therapy alone.
Individuals with hypoplastic AI often can retain intracoronal restorations such as amalgams and composite resins.
if the enamel is extremely thin and malformed the teeth can require full dental coverage with crowns.
Resin crowns can be placed on permanent incisors soon after they begin to erupt during the mixed dentition (about age 7 – 10 years). As the gingival margin becomes exposed during continued tooth erupt the resins are easily modified by adding resin to the gingival margin of the tooth.
Ultimately, porcelain fused to metal or other custom fabricated crowns can be placed on the dentition. This may be delayed until late adolescence or early adulthood when all the teeth are present, the teeth are fully erupted, and the gingival height around the teeth has stabilized.
While costly, these types of restorations can allow even severely affected dentitions to be treated and achieve excellent function and esthetics.
The severely affected individual shown in Figure had AR Hypomaturation AI and was treated over several years with stainless steel crowns, orthodontics, orthognathic surgery and eventually porcelain fused to metal crowns to achieve this excellent result.