Prospective clinical trial of dental implants in persons with ectodermal dysplasia

Statement of problem. Ectodermal dysplasia is a hereditary condition in which hypodontia is the second most frequently occurring sign. Hypodontia is associated with lack of development of the alveolar ridge and results in less volume of bone for support of conventional prostheses. Minimal development of the alveolar ridge can affect the bone volume available for the placement of dental implants. Purpose. This clinical trial evaluated the survival of implants placed in individuals with a form of ectodermal dysplasia and severe hypodontia. Material and methods. Two hundred sixty-four titanium endosteal dental implants were placed in 51 subjects: 37 males and 14 females between the ages of 8 and 68 (mean age 20.5 years, median age 16.5 years). Two hundred forty-three implants were placed in the anterior mandible, and 21 were placed in the anterior maxilla with a 2-stage surgical protocol. Either fixed-detachable dentures or bar-clip overdentures were provided. Subjects were followed up for 0 to 78 months after second-stage surgery. Kaplan-Meier survival rates and curves were produced to describe the survival of the implants for the different age groups and implant locations. Repeated-measures Cox regression models were used to evaluate the hazard ratios for age and location, with α=.05 as the criteria for significance. Results. Of the 243 implants placed in the anterior mandible, 221 (91%) survived. Of the 21 implants placed in the anterior maxilla, 16 (76%) survived. Fourteen of the 51 (27%) subjects had a failed implant. All but 2 failures occurred before or at second-stage surgery. Implant-supported prostheses were provided for all patients. Conclusion. Within the limitations of this study, the results support the continued use of endosteal dental implants in this patient population with appropriate precautions in the maxilla.