Multidisciplinary Management of Amelogenesis Imperfecta in an Adolescent

Amelogenesis imperfecta (AI) is a heterogenous group of genetic conditions characterized by defects in enamel formation. Mutations in genes that cause AI can be inherited in an autosomal recessive, dominant, or X-linked manner.¹

In the United States, the prevalence of AI is estimated to be one in 14,000.² AI can be classified into three phenotypes: hypomaturation, hypo­mineralized, and mixed AI.³ However, phenotypic classification can be difficult due to post-eruptive changes in teeth caused by functional wear.^1,4 Patients with any form of AI often require complex, lifelong, multidisciplinary dental care.⁵

The effect of dental esthetics on the psychological well-being of patients is highly relevant. Especially among young patients and women, dental esthetics have a significant social impact.⁶ An interview study of adolescents and young adults with AI found they had feelings of embarrassment and shame.⁷ Patients in the study reported they were afraid of what others thought of them and had an insecurity that increased with age. Improving the smiles of patients with AI, therefore, may significantly improve their quality of life.

Successful multidisciplinary dental treatment relies on excellent communication between team members and the patient.⁸ Complex dental treatments may require prolonged periods of provisionalization and coordination between multiple dentists and dental laboratories.^9,10 A strong association exists between prosthetic dentistry and periodontics in the longevity of fixed dental restorations.^11,12 This includes proper restoration contours and crown margin placement that permit more effective oral hygiene.¹³

Case Report

In this case report of a young patient with AI, the goals of treatment are improved esthetics, protection of dentin, and minimization of future tooth loss.  A 17-year-old white nonsmoking woman reported with a history of AI. Her chief concern was functional and esthetic oral reconstruction (Figures 1-5). Preliminary diagnostic records included a full-mouth series of radiographs, cone-beam computed tomography, intra- and extra-oral photographs, and mounted models.

She was missing teeth #s 1, 16, 17, and 32. Tooth #21 was impacted. Teeth #s 2, 12, 13, 14, and 18 had stainless steel crowns. Teeth #s 6, 7, 8, 9, 10, 20, 22, 23, 24, 25, 26, and 27 had bonded restorations.

Exposed dentin was present on the clinical crowns of unrestored teeth. These teeth showed signs of significant occlusal wear and/or fractures. Many teeth had soft exposed tooth structure and/or minor carious lesions. Teeth #s 12 to 14 were super-erupted. Tooth #8 was mesially inclined. Tooth #20 was intruded.

The anterior overjet was approximately 2 mm. The overbite was approximately 6 mm. The maxillary tooth midline was approximately 1 mm to the right of the mandibular midline. The periodontal probing depths were 2 to 4 mm. Despite the overall low clinical plaque levels, the maxillary tooth sites exhibited a high degree of gingival inflammation.

Radiographically, periodontal bone levels appeared normal, all teeth had normal root lengths, and no endodontic pathology was noted. The teeth were not mobile. After discussing the findings, treatment options, and risks with the patient and her parents, we agreed to treat the patient with full-mouth single-unit restorations. Clinical crown lengthening and interim provisional crowns were needed to deliver natural appearing restorations and maintain a healthy periodontium.

All findings were reviewed with the patient and her mother. An initial digital design and wax-up models were created and presented to the patient and parents for approval. The restorative plan included removing teeth #s 2, 15, 18, 21, and 31.

The case was mounted on an articulator in centric relation. A facebow and bilateral manual manipulation were used to mount the models. Centric relation mounting was verified in the mouth post-mounting. The patient’s bite would be anteriorly opened by 2 mm. This would enable the achievement of an ideal occlusal plan and optimum thickness for the occlusal ceramics.

Final restorations were single unit tooth-supported crowns. Clinical crown lengthening provided adequate clinical crowns for stable restorations and esthetics. After approval of the plan, the patient was sent to an oral surgeon for removal of teeth #s 2, 15, 18, 21, and 31. Following healing of these sites, the patient began her restorative phase of treatment.

The first step was to remove the current restorations and any soft or carious tooth structure. Crown preparations were made and provisional restorations were placed. (Figure 6) Polymethyl methacrylate (PMMA) provisional restorations were made using impressions taken from the diagnostic wax-up. All teeth were determined to be restorable and no endodontic therapy was deemed necessary. Vinyl polysiloxane (VPS) impressions were taken of the crown preparations for a second digital design and diagnostic wax up. Using this information, the need for clinical crown lengthening surgery was determined. The patient was referred to a periodontist.

Following detailed written instructions, the periodontist treated the maxillary and mandibular teeth with clinical crown lengthening. The maxillary teeth were treated at the first surgical appointment. Ostectomies were performed to resemble the desired gingival contours and create a 3 mm space between the osseous crest and margins of the provisional restorations. (Figure 7) This permitted placement of the gingival margins in the predetermined position.

The gingival flaps were secured using a continuous 4.0 polytetrafluoroethylene suture. A maxillary anterior frenectomy was also performed. The wound was closed using 4.0 plain gut sutures (Figure 8). At the second surgical appointment, the mandibular tooth sites were treated with clinical crown lengthening surgery following the written instructions. The patient was advised to maintain excellent oral hygiene and use an over-the-counter fluoride mouthrinse. The patient was released to complete the final restorative phase of treatment. Final impressions were approved for 12 weeks following the last surgery.

Twelve weeks following surgery, the crown preparations and provisional restorations were refined by the general dentist. Impressions were taken for a second set of provisional crowns. Final design decisions, including shade selection, were made. Lab-fabricated PMMA provisional crowns were delivered about 3 weeks later.

The patient and her mother approved the tooth shapes, color, bite, esthetics, and phonetics. The patient remained in the PMMA provisional crowns for about 7 months. Pulp vitality was monitored. Endodontic treatment was not deemed necessary.

After about 7 months, final crown margin adjustments were made and full-arch impressions were taken. Impressions were made using heavy and light VPS. At the dental laboratory, final restoration design was made digitally and approved by the general dentist (Figures 9-12).

Final high translucent monolithic zirconium crowns were fabricated and cemented in place using a resin-modified glass ionomer luting cement. At the patient’s request, the crowns had shade B1 without shade gradations (Figures 13-17). Final restorations were natural and highly esthetic in appearance. The patient was able to maintain excellent oral hygiene and the periodontium was healthy.

The patient and her mother reported significant beneficial effects of the treatment. The patient reported feeling more confident and comfortable in social settings, as well as smiling more often and feeling more attractive. As a result, she was better able to interact with her peers and develop closer relationships.

Discussion

Several treatment options were discussed with the patient and her mother.  This included dental implant-supported restorations. Given that AI is characterized by defects in the formation of enamel, it would seem reasonable that a concomitant increase in the risk of dental caries would be present.¹ This is, however, not necessarily the case. A systematic review of the literature found a low dental caries susceptibility among patients with AI.¹⁴ This may be due to the lack of proximal contacts, elimination of fissures, and with hypoplasitic AI, a microbacterial specificity.¹⁴ Caries risk therefore, was not a compelling reason to replace teeth using dental implants.

Considering the patient’s young age, the possibility of continuous craniofacial growth was a concern. Maxillomandibular changes throughout adulthood may lead to complications, such as implant infraocclusion (IO) and interproximal contact loss (ICL).¹⁵ A study of single-implant restorations in the posterior and anterior regions, 3 months to 11 years after restoration insertion, found 52.8% to have interproximal contact loss.¹⁵

A literature review of the prevalence and contributing factors to ICL between implants and adjacent teeth found that ICL might occur as early as 3 months after prosthetic treatment.¹⁶ In this study, ICL ranged between 18% and 66% in the maxilla and 37% to 54% in the mandible. A retrospective case series report of implants placed in adolescents, ages 10 to 19 and followed up from 5 to 15 years, found that ICL and IO were the most common complications.¹⁷

A retrospective study evaluated young adults (ages 15.5 to 21) and mature adults (ages 40 to 55) who had single implants placed in their anterior maxillary sextant.¹⁸ The mean interval of re-evaluation was 4.2 years. All patients showed IO of the implant-supported crowns. No difference was found between men and women.

A more recent review of the literature regarding implants placed in the anterior maxilla found that facial skeletal growth and teeth eruption are evident in the second and third decades of life.¹⁹ This study concluded that, where possible, placement of an anterior maxillary implant should be delayed in the adolescent patient.¹⁹ The distinct possibility of the development of ICL and IO discouraged the use of dental implants in this young patient.

Good communication between the patient, dentists, and dental laboratory is critical to treatment success.²⁰ Precise planning and clear communication is especially important with full-mouth rehabilitation cases.²¹ The use of digital planning software can aid in this communication. Visual representations are very useful in communicating future treatment. The patient must have clear and appropriate expectations. Dentists and the dental lab need to follow through with the assurances made to the patient.

Support for permanent fixed prosthetic tooth-supported restorations of young patients with AI can be found in the literature.²² Material selection for this case was primarily decided by the patient’s young age and need for long-term success of the crowns. Zirconia is a crystalline oxide of zirconium that has good mechanical, optical, and biological properties.²³ Zirconia has the highest hardness among the various restorative materials used in dentistry.²⁴ Studies show it is a biocompatible biomaterial. The addition of yttria content increases the translucency, but decreases its strength.²⁵

In this case, monolithic zirconia crowns were used. For the molars, zirconia with a lower yttria content (3Y-TZP, 3 mole % Y-TZP) was used for its higher strength. For the remaining teeth, zirconia with a higher yttria content (5Y-TZP, 5 mole % Y-TZP) was used for its higher esthetic value. The choice of shade B1 without cervical color staining was made by the patient.

Clinical crown lengthening is necessary when available clinical crown height is insufficient. Proper position of the crestal bone and gingival margins will ensure restorations that do not violate biologic width and permit restorations with proper esthetic proportions.²⁵ In addition, restorations with proper crown margin placement and crown contours will permit effective oral hygiene and reduce the risk of future caries and/or periodontal disease.

Zirconium-based restorations made from computer-aided design and computer-aided manufacturing technology provide better results, in terms of marginal fit, inflammation reduction, maintenance, and the restoration of periodontal health and oral hygiene, compared to constructions made by conventional methods, and from other alloys.²⁶ Compared to subgingival margins, supragingival margins offer better oral hygiene, which can be maintained and do not lead to secondary caries or periodontal diseases.²⁷

An important goal of dentistry is to improve the patient’s quality of life. As reported, dental esthetics affect the psychologic and social welfare of the adolescent patient.⁶ A systematic review of articles dealing with bullying and dentofacial traits found the majority of studies (88%) reported a relationship between malocclusion or dental structural defects and exposure to bullying among young adolescents.²⁸

Another study specifically evaluated the oral health-related quality of life (OHRQoL) of patients with severe AI before and after crown therapy.²⁹ Of 26 patients (ages 9 to 22, mean 16.1 ± 3.1) with severe AI, most reported significantly improved OHRQoL after crown therapy. The patient in this article had poor self-perception of her smile prior to treatment. Consistent with the literature, the patient reported being very happy with her smile after treatment. Her confidence was improved dramatically afterward. This allowed her to engage actively and positively in her social environment and with her peers.

Conclusion

Patients with AI may face psychological, social, and dental challenges. Adolescents are vulnerable to oral health-related self-perception problems. Good communication and coordination of care are critical for dentists and dental labs to provide the most successful treatment outcomes for patients with AI.

References

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From Decisions in Dentistry. October/November 2024;10(6):28-31.