Oral Rehabilitation of Young Adults with Amelogenesis Imperfecta

H.-K. Yip, BDS, MEd, MMedSc, PhD, FRACDSa Oral Rehabilitation of Young Adults Roger J. Smales, MDS, DDSc, FDSRCS, FADM, with Amelogenesis Imperfecta FHKAM (Dent Surg)b

Purpose: This article describes the restorative management of two patients in whom the diagnosis of amelogenesis imperfecta was not made until young adulthood. Materials and Methods: Amelogenesis imperfecta is a variable developmental abnormality of the tooth enamel that affects relatively few persons. Previous case reports have focused largely on the early management of children and young adolescents. However, some patients may not be diagnosed correctly or may not request dental treatment until they are older, as with the two cases presented. In some instances, parents fail to appreciate the importance of early intervention. Results: Both patients required intensive preventive therapy and extensive restorative treatment over several years. The correct sequencing of treatment phases was required to achieve relief of pain and provide satisfactory function and esthetics. Conclusion: The two cases presented illustrate the degree of complexity that extended restorative treatments can involve, especially following severe tooth wear and poor bonding of restorations to the affected enamel. Int J Prosthodont 2003;16:345–349.

melogenesis imperfecta (AI) is a rare develop- calcification, taurodontism, and root malformations; Amental abnormality of the tooth enamel, with a failed tooth eruption and impaction of permanent variable occurrence of approximately 1:4,000 to teeth; progressive root and crown resorption; congen- 1:14,000 in Western populations.1–3 A widely used itally missing teeth; and anterior and posterior open- classification system for AI is based on genetic in- bite occlusions (Fig 1). Children and young adolescents heritance, histopathology, and specific clinical den- exhibit these general features of AI, which may not be tal characteristics.3 A more recent classification sys- the same in young adults, where caries and marked tem also includes limited molecular and biochemical sensitivity may commonly result from widespread ex- information.4 In general, the inheritance pattern is posed dentin in the permanent teeth. This exposure usually autosomal dominant or recessive, or X-linked. may arise either from a deficiency in the enamel at- Within affected families, there is an extremely vari- tachment to dentin or from extensive occlusal wear of able clinical appearance of enamel hypoplasia, defective enamel that may also result in the loss of oc- hypocalcification, or hypomaturation, depending on clusal vertical dimension (OVD). In younger patients which stages of enamel formation are involved.5 especially, there may be appreciable dentoalveolar Dental features associated with AI include6–10: quan- compensation for the wear. Excessive tooth enamel titative and qualitative enamel deficiencies; pulpal wear may also occur at proximal contacts or, con- versely, interproximal tooth spacing may be present when the teeth are small and the enamel is inherently a Associate Professor, Oral Diagnosis, Faculty of Dentistry, The thin. University of Hong Kong, People’s Republic of China. bVisiting Research Fellow, Dental School, The University of Factors adversely influencing restoration man- Adelaide, South Australia. agement may include poor oral hygiene with associated gingivitis and gingival hyperplasia. Oral hy- Reprint requests: Dr H.-K. Yip, Oral Diagnosis, Prince Philip Dental Hospital, 34 Hospital Road, Hong Kong SAR, People’s giene is poor in some patients, often because of 8 Republic of China. Fax: + (852) 2547 0164. e-mail: tooth hypersensitivity and the presence of an an- [email protected] terior open bite associated with mouth breathing.

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incentive for maintaining her oral hygiene. The brown, discolored posterior teeth were restored subsequently, when the patient was 19 to 22 years old, with metal-ceramic and gold crowns at the existing OVD. At a 5-year review, there was some gingival recession around the restored anterior teeth (Fig 3), and the metal-ceramic crowns on the maxillary anterior teeth were replaced with all-ceramic crowns to further improve the appearance of the patient (Fig 4).

Patient 2 Fig 1 Anterior view of a patient with amelogenesis imperfecta, poor oral hygiene, and an anterior open bite. This case illustrates the more complex management of a healthy 22-year-old man who presented with AI and abnormal second and third molar development with delayed eruption (Fig 5). His main initial con- cern was toothache caused by extensively carious posterior teeth. The severe occlusal wear with loss of OVD was partly compensated for by dentoalveolar growth. Limited pitted, hypoplastic enamel re- mained on the worn teeth. The maxillary anterior There may have been little or no oral health care gingival tissues were overgrown and fibrous, and during childhood. Pitted enamel surfaces also pre- gingival recession was associated with the posterior dispose plaque accumulation, but spaced teeth may teeth. His oral hygiene was poor. The patient stated reduce caries susceptibility. Oral hygiene has to be that his primary teeth were small and discolored, and maintained at a high standard if restorative proce- that his parents and five siblings were not similarly dures are to have a favorable long-term prognosis. affected. Treatment objectives for the young adult patient Initial treatment involved the relief of pain, pro- also include the relief of pain and improvement of phylaxis and scaling, and oral hygiene instruction. facial esthetics and function. Most reports of the A 0.2% chlorhexidine mouthrinse was also pre- treatment of AI have involved children and young scribed. Carious pulp exposures required subse- adolescents. There are very few more recent reports quent root canal therapy for three posterior teeth. regarding the oral rehabilitation of older per- The eight unerupted abnormal second and third sons.11,12 molars were removed surgically under general anes- thesia. A maxillary occlusal acrylic resin splint was Case Presentations made at an increased OVD to assess the patient’s re- sponse before commencing the oral rehabilitation Patient 1 phase. Thin gold crowns were then placed on all posterior teeth at the increased OVD (Fig 6). This A healthy 18-year-old woman was referred by her treatment was followed by gingival and crown general dental practitioner for the treatment of AI lengthening surgery for the maxillary anterior teeth, (Fig 2). She wanted to improve the appearance of her and the interim restoration of all the anterior teeth anterior teeth especially, which were discolored with indirect resin composite veneers bonded to brown and had stained, pitted, hypoplastic enamel. enamel. The veneers required frequent rebonding The patient stated that her primary teeth were also over several years. The maxillary right canine re- discolored. There was minimal occlusal tooth wear, quired extraction because of a root fracture; fol- without exposed dentin. She also had poor oral hy- lowing bone augmentation, it was replaced with a giene, caries, and several unsatisfactory restora- single-tooth implant. Subsequently, when the pa- tions. tient was 28 years old and could afford further treat- The oral hygiene of the patient was improved ment, the mandibular anterior teeth were restored after intensive therapy, then porcelain veneers were with porcelain veneers bonded to dentin, and the bonded to enamel following preparation of all maxillary anterior and all premolar teeth were re- the anterior teeth. The patient was extremely pleased stored with metal-ceramic crowns to optimize es- with the result, and she gained an additional thetics (Fig 7).

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Fig 2 Panoral radiograph of patient 1, with amelogenesis imperfecta and missing maxillary left canine.

Fig 3 (above right) Anterior view of patient 1 at a 5-year review. There is some gingivitis and gingival recession at the restoration margins.

Fig 4 (right) Anterior view of patient 1. The maxillary metal-ceramic crowns are replaced by all-ceramic crowns for improved appearance.

Fig 5 Panoral radiograph of patient 2, with amelogenesis imperfecta showing lack of enamel radiopacity and malformed second and third molars with large pulp chambers and crown resorption.

Fig 6 (above right) Anterior view of patient 2. The maxillary anterior teeth are surgically lengthened, and provisional resin composite veneers are placed. The posterior teeth are restored with complete gold crowns.

Fig 7 (right) Anterior view of patient 2. The gingival condition is much improved following better oral hygiene and the daily use of a chlorhexidine mouthrinse. An implant replaces the extracted maxillary right canine, and all anterior teeth have been restored using metal-ceramic crowns.

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Discussion Complete-mouth rehabilitation • Crown lengthening of worn maxillary anterior Of practical importance for the restorative treatment and other selected teeth if required of AI are the following parameters: • Metal-ceramic crowns or thin all-ceramic and polymer resin–bonded crowns and porcelain ve- • Size of the pulp chambers and amount of occlusal neers if the enamel is suitable for bonding and interproximal tooth wear • Loss of OVD and degree of dentoalveolar com- Maintenance phase pensation • Monitor oral hygiene, periodontal and pulpal sta- • Number, form, color, and sensitivity of the af- tus, and restorations fected permanent teeth • Strength of attachment of the enamel to dentin Initial restorative treatments should be conserva- and dentin quality tive, using direct adhesive materials. However, de- • Thickness of enamel and degree of mineraliza- fective enamel quantity and quality might require se- tion, and the ability of restorations to bond satis- lective clinical crown lengthening surgery and the factorily to the affected enamel placement of crowns for adequate retention, esthetics, and the reestablishment of OVD. Newer dentin bonding systems provide more reli- OVD can be reestablished using several restorative able bonding to dentin than did earlier systems and, methods, but careful treatment planning is required although the newer systems also infiltrate enamel before undertaking the occlusal rehabilitation.18 prisms more effectively,13,14 they might provide more Overdentures are the least expensive and least inva- durable dentin bonding than when attempting to sive treatment approach and, should patients be un- bond to abnormal enamel. Several studies have found able to adapt to an altered increased OVD, the pros- an absence of typical etch patterns in enamel af- theses can be adjusted or remade. The dentures can fected by thin, smooth, hypoplastic, and male X- also act as reservoirs for topical fluoride gels and de- linked variants of AI.15,16 Hypocalcified and hypo- sensitizing agents. matured enamel in particular also contain increased Although posterior resin composite onlays with amounts of protein.17 cusp coverage may be functionally adequate to A major restorative problem can be the continued reestablish the OVD in some instances of AI, bonded debonding of interim resin composite veneers, as cast restorations are preferable when multiple molar occurred with patient 2. In this situation, adequate re- restorations are required for occlusal stability.19,20 tention of the final restorations requires crowns, or re- Preparations for thin gold crowns are also more con- moval of the overlying defective enamel is suggested servative than those for metal-ceramic crowns,11 and before bonding the veneers to the exposed dentin. gold crowns are preferred for restoring molars that The general treatment sequence suggested for have extensive interproximal and occlusal wear. The young adults presenting with AI is as follows. creation of a tin oxide or silica layer on the sand- blasted fitting surfaces of metal-alloy castings signif- Preventive and initial phases: icantly improves the adhesion of luting cements.21,22 Restoring primary molars using nickel-chromium • Oral hygiene instruction, prophylaxis, and scaling crowns, and then later the permanent molars with • Fluoride and chlorhexidine mouthrinses, control thin gold crowns, early in life will preserve the OVD of dentin hypersensitivity and prevent interproximal tooth wear. Metal-ceramic • Extraction of nonstrategic teeth, initial urgent crowns with labial porcelain margins are considered restorative treatments a satisfactory esthetic option in adults for restoring de- •Orthodontic and other consultations fective anterior and posterior teeth. The preparations are more conservative than those required for all-ce- Restorative phase (over an extended period): ramic crowns with high-strength cores.

Reestablish appropriate OVD if required Conclusion • Maxillary overdenture or provisional occlusal splint • Resin composite buildups for anterior and other The complexity of the management of patients with selected teeth if the enamel is suitable for resin AI supports the suggestion that the prosthodontic pro- bonding fession should have a key position in the rehabilita- • Thin gold crowns or resin-bonded cast onlays tion of rare disorders.23 Treatment of patients with AI for posterior teeth should start with early diagnosis and intervention to

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COPYRIGHT © 2003 BY QUINTESSENCE PUBLISHING CO, INC. PRINTING OF THIS DOCUMENT IS RESTRICTED TO PERSONAL USE ONLY. NO PART OF THIS ARTICLE MAY BE REPRODUCED OR TRANSMITTED IN ANY FORM WITHOUT WRITTEN PERMISSION FROM THE PUBLISHER. Yip/Smales Rehabilitation of Amelogenesis Imperfecta prevent later restorative problems. However, some pa- 10. Winter GB. Amelogenesis imperfecta with enamel opacities tients may not seek treatment until young adulthood, and taurodontism: An alternative diagnosis for “idiopathic den- after advanced tooth wear and the associated tooth tal fluorosis.” Br Dent J 1996;181:167–172. 11. Lumley PJ, Rollings AJ. Amelogenesis imperfecta: A method of sensitivity, functional, and esthetic problems have al- reconstruction. Dent Update 1993;20:252–255. ready occurred, leading to the need for complex 12. Nel JC, Pretorius JA, Weber A, Marais JT. Restoring function and restorative treatments. esthetics in a patient with amelogenesis imperfecta. Int J Periodontics Restorative Dent 1997;17:478–483. Acknowledgments 13. Nakabayashi N, Pashley DH. Hybridization of Dental Hard Tissues. Chicago: Quintessence, 1998:37–39. 14. Yoshida Y, van Meerbeek B, Nakayama Y, et al. Adhesion to and The authors wish to acknowledge the support received from Prof decalcification of hydroxyapatite by carboxylic acids. J Dent Res Urban Hägg, Chair Professor in Orthodontics, Faculty of Dentistry, 2001;80:1565–1569. The University of Hong Kong. Some financial assistance received 15. Wright JT, Duggal MS, Robinson C, Kirkham J, Shore R. The min- from a CERG grant (A/C 10202943) is also appreciated. eral composition and enamel ultrastructure of hypocalcified amelogenesis imperfecta. J Craniofac Genet Dev Biol 1993;13:117–126. References 16. Seow WK, Amaratunge A. The effects of acid-etching on enamel from different clinical variants of amelogenesis imperfecta: An 1. Bedi R. The management of children with amelogenesis imper- SEM study. Pediatr Dent 1998;20:37–42. fecta. Restorative Dent 1989;5:28–34. 17. Wright JT, Deaton TG, Hall KI, Yamauchi M. The mineral and 2. Sundell S, Koch G. Hereditary amelogenesis imperfecta. I. protein content of enamel in amelogenesis imperfecta. Connect Epidemiology and clinical classification in a Swedish child pop- Tissue Res 1995;32:247–252. ulation. Swed Dent J 1985;9:157–169. 18. Wassell RW, Steele JG. Considerations when planning occlusal re- 3. Witkop CJ. Amelogenesis imperfecta, dentinogenesis imper- habilitation. A review of the literature. Int Dent J 1998;48:571–581. fecta and dentin dysplasia revisited: Problems in classification. 19. Hunter L, Stone D. Supraoccluding cobalt-chrome onlays in the J Oral Pathol 1988;17:547–553. management of amelogenesis imperfecta in children: A 2-year 4. Aldred MJ, Crawford PJM. Amelogenesis imperfecta: Towards a case report. Quintessence Int 1997;28:15–19. new classification. Oral Dis 1995;1:2–5. 20. Sengun A, Ozer F. Restoring function and esthetics in a patient 5. Aldred MJ, Crawford PJM. Molecular biology of hereditary with amelogenesis imperfecta: A case report. Quintessence Int enamel defects. Ciba Found Symp 1997;205:200–209. 2002;33:199–204. 6. Sundell S. Hereditary amelogenesis imperfecta. I. Oral health in 21. Fisher FJ, Smith DP. Amelogenesis imperfecta—A method of re- children. Swed Dent J 1986;10:151–163. habilitation. Dent Update 1984;11:513–522. 7. Walls AWG. Amelogenesis imperfecta with progressive root re- 22. Moulin P, Degrange M, Picard B. Influence of surface treatment sorption. Br Dent J 1987;162:466–467. on adherence energy of alloys used in bonded prosthetics. J Oral 8. Rowley R, Hill FJ, Winter GB. An investigation of the associa- Rehabil 1999;26:413–421. tion between anterior open-bite and amelogenesis imperfecta. 23. Bergendal B. The role of prosthodontists in habilitation and re- Am J Orthod 1982;81:229–235. habilitation in rare disorders. Int J Prosthodont 2001;14:466–470. 9. Collins MA, Mauriello SM, Tyndall DA, Wright JT. Dental anom- alies associated with amelogenesis imperfecta. Oral Surg Oral Med Oral Pathol Oral Radiol Endod 1999;88:358–364.

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