Overdentures supported by two IMZ implants in the lower jaw. A retrospective study of peri-implant tissues

Between 1987 and 1990, 57 edentulous patients were treated with overdentures supported by 2 endosseous IMZ implants connected by a bar in the lower jaw. The condition of the peri-implant tissue was evaluated for a loading period ranging from 12 to 57 months (mean 30 months and median 24 months). The evaluation parameters included Plaque Index, Bleeding Index, Gingiva Index, pocket depth, dysesthesia of chin or lip, peri-implant bone loss and loss of implants. During the healing phase prior to the construction of an overdenture, 3 implants were lost. After a healing period of 6 months, these implants were successfully replaced. During the follow-up period, a Plaque Index < or = 1 was observed in 45 patients and an abundance of plaque and calculus was observed in 1 patient. Heavy or profuse bleeding and severe gingival inflammation was observed in 3 patients. The mean pocket depth was 3.6 +/- 1.7 mm. None of the patients experienced lip or chin dysesthesia. Marginal bone loss was observed around 30 (26%) implants. From this study it is concluded that, once proper osseointegration is obtained, 2 IMZ implants connected with a bar in the lower jaw supply a proper base for the support of an overdenture; the condition of the peri-implant tissues is steady and independent of the follow-up time.