Amelogenesis Imperfecta

1. AmelogenesisImperfecta Shilpa.M

2. Otherwise known as….. • A I • Hereditary Enamel Dysplasia • Hereditary Brown Enamel • Hereditary Brown Opalescent Teeth

3. What is Amelogenesis Imperfecta ? • 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.

4. 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.

5. Prevalence • 1 in 700 to 1 in 15,000

6. Etiology • 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 • enamelin • amelogenin • ameloblastin • tuftelin • amelotin • dentine sialophosphoprotein (DSPP;) • enzymes such as kallikrein and • matrix metalloproteinase 20 (MMP20) Any mutations in these proteins can cause AI.

7. A I & D I

8. Development of enamel.. • 3 stages.. • formative stage deposition of organic matrix. • Calcification stage matrix mineralization • Maturation stage crystallites enlarge and mature

9. A I • 3 Types.. • Hypoplastic • Hypocalcified • Hypomaturation • A 4th type of A I is a combination of hypoplastic & hypomaturation types.

10. Classification of A I • Based on clinical,histological,&genetic criteria-Witkop & Sauk • Hypoplastic Pitted, AD Local, AD Smooth, AD Rough, AD Rough, AR Smooth, X-linked dominant • Hypocalcified DiffuseAD Diffuse AR • Hypomaturation Diffuse , X-Linked recessive Diffuse Pigmented, AR Snow-capped teeth, X-linked • Combination Type Hypomaturation-hypoplastic with taurodontism,AD Hypoplastic-hypomaturation with taurodontism,AD

11. Clinical features.. • Hypoplastic Type. The enamel is not formed to full normal thickness

15. Hypocalcified Type. • The enamel is so soft that it can be removed by a prophylaxis instrument. • Yellow brown or orange on eruption, stained brown to black with time. • Exhibits rapid calculus apposition. • Coronal enamel lost with function, except for the cervical portion which is mineralized better. • Autosomal recessive—more severe.

18. Hypomaturation Type. • The enamel can be pierced by an explorer point under firm pressure • can be lost by chipping away from the underlying normal appearing dentin. • Teeth are normal in shape, but exhibit a mottled , opaque white brown yellow discoloration. • Snow capped pattern- exhibit a zone of white opaque enamel on the incisal or Occlusal third of the crown.

22. Other features… • Both dentitions are affected • In Some cases teeth may appear normal, in others may be extremely unsightly. • Color of the crown can vary from yellow to dark brown. • Enamel might have numerous parallel vertical wrinkles or grooves. • Open contact points • Occlusal surfaces and incisal edges are frequently abraded

23. Radiographic Features • The enamel may appear totally absent • When present may appear as a thin layer , chiefly over the tips of the cusps & on the interproximal surfaces. • In some cases calcification is so much affected that enamel & dentin seem to have the same radio density, making differentiation between the two difficult.

25. Histological Features • Hypoplastic type—disturbance in the differentiation or viability of ameloblasts. • Hypocalcification type– defects of matrix structure and of mineral deposition. • Hypomaturation type– alteration in enamel rod & rod sheath structures.

26. Management • Treatment depends on the specific AI type and the character of the affected enamel. • Treatments range from preventive care using sealants and bonding for esthetics to extensive removable and fixed prosthetic reconstruction.

27. Treatment of hypoplastic type • Therapy for the hypoplastic AI types typically involves the use of bonding procedures to protect the malformed teeth from caries and improve esthetics. • Hypoplastic teeth usually have reasonably well mineralized enamel, albeit thin and/or pitted, making them suitable for restorative therapies involving bonding to the enamel . • Composite resin or porcelain veneers can be bonded to the anterior teeth when the incisor shape, size and/or color requires modification.

28. Continued….. • 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.

29. Porcelain veneers

30. Treatment of hypocalcified & hypomaturation types • The hypomaturation and hypocalcified AI types can be restored with conventional approaches if the enamel is not severely involved. • if enamel is severely hypomineralized and of insufficient strength to retain bonded or intracoronal restorations, full coverage restorations should be placed. • In cases of severely hypomineralized enamel, stainless steel crowns are indicated in the primary and early permanent dentitions.

31. Continued… • stainless steel crowns with composite inserts or composite crowns that are retained both by mechanical undercuts and bonding can greatly reduce tooth sensitivity and provide reasonable esthetics. • The dentist should not rely on retention from bonding alone in those cases with very weak and poorly mineralized enamel.

32. Continued…. • 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.

35. 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.

36. Thank you all