Abstracts

Exposure to phenytoin is often associated with the development of gingival hyperplasia. In institutionalized mentally retarded/developmentally disabled patients, the degree of gingival hyperplasia is often severe, leading to periodontal disease requiring surgical intervention or to loss of dentition. The purpose of this ongoing study is to assess the safety and efficacy of conversion from phenytoin to topiramate in institutionalized patients with gingival hyperplasia. Topiramate was chosen based on evidence suggesting efficacy against a broad spectrum of seizure types.
The study protocol and all procedures were approved by the University of Louisville IRB. This is an open label study with degree of gingival hyperplasia as the primary outcome measure. At the Hazelwood Center For Persons With Mental Retardation, 62 of 209 adults were receiving phenytoin at study initiation. After exclusion of 13 edentulous patients, 44 of the remaining 49 patients were found to have gingival hyperplasia in varying stages of severity. Informed consent was obtained from caregivers of 21 patients. Patients received a baseline periodontal assessment and a 3 month assessment of seizure frequency. Adjunctive topiramate was then titrated to a target dose of 200 mg bid, followed by tapering and discontinuation of phenytoin. Four months after phenytion was discontinued, the periodontal evaluation was repeated. Patients experiencing adverse events received alternative medication chosen by the treating physician.
Baseline periodontal evaluations revealed moderate to severe gingivitis with friable, hemorrhagic tissue and pocket depths exceeding 5mm. Four months after tapering phenytoin, 19 patients had improved tissue quality with diminished pocket depths and firm, fibrous gingivae. Following substitution of topiramate for phenytoin, 3 patients had fewer seizures, 13 had no change in seizure frequency and 5 had increased seizures resulting in alternative treatment (including one episode of status epilepticus requiring reinstatement of phenytoin).
Exposure to phenytoin is asociated with significant gingival hyperplasia in approximately 90% of the dentulous patients in this institutionalized population. The degree of gingival hyperplasia improved substantially by four months after pheytoin withdrawal in 90% of patients. Our findings suggest that topiramate or other antiepileptic drugs may be safe, effective alternatives to phenytoin in institutionalized patients with phenytoin-induced gingival hyperplasia.
[Supported by: University of Louisville School of Medicine
University of Louisville School of Dentistry]