Spontaneous early exposure of submerged implants: I. Classification and clinical observations

Background: It is believed that during the osseointegration phase of submer ged dental implants, complete mucosal coverage and isolation of the implant from the oral cavity avoids trauma and infection and establishes favorable conditions for osseointegration. Spontaneous early exposure is one of the complications that could adversely affect osseointegration of implants. Methods: This study clinically classifies spontaneous early exposure and de scribes and analyzes this complication in a group of 148 patients treated w ith 372 submerged implants: 216 (58%) in the mandible and 156 (42%) in the maxilla. Edentulous sites were exposed by mid-crestal incisions and full th ickness gingival flaps. Incisions were closed in an attempt to achieve comp lete closure and healing by primary intention. Measurements were taken to a void mechanical trauma to the mucosa over the implants. Patients were follo wed up weekly and examined to identify early exposures. Perforations were c lassified according to the degree of exposure from 0 (no perforations) to 4 (complete exposure). Results: Of the implants 51 (13.7%) presented spontaneous early exposure,(2 8) (13%) in the mandible and 23 (14.7%) in the maxilla. Class 2 perforation was the most frequent, followed by Class 3, Class I and Class 4. Inflammat ion at the mucosal orifices of the perforations was minimal, but no objecti ve index (bleeding, probing) was taken in order to avoid morphological chan ges of the lesions that were biopsied for histological examination. Conclusions: Early perforation and partial exposure of the implant's coveri ng device are a focus for plaque accumulation which, if left untreated, may result in inflammation, damage to the peri-implant mucosa, and possible pe ri-implant loss.