Tissue alterations at implant-supported single-tooth replacements: a 1-year prospective clinical study

The aim of this prospective study was to evaluate dimensional alterations of the peri-implant tissues at single-tooth restorations from the time of implant placement to 1-year post-loading.

Eleven patients, aged 18-36 years, subjected to single-tooth replacements with implant-supported restorations (Brånemark implant system) in the maxillary anterior region were included in the analysis. The implant installation was performed as a two-stage procedure with a 6-month healing interval. Bone dimensions were determined by direct assessments immediately following implant placement and at abutment connection. The prosthetic restoration was placed approximately 1 month after abutment surgery. Radiographic and clinical examinations were performed at crown placement and at 1-year post-loading. Assessments of the soft tissues at the implant site and at the neighboring teeth were performed before and during implant placement, before abutment connection, after crown placement and at the 1-year follow-up examination. Mean values and standard deviations were calculated for each variable and interval, with the subject as the statistical unit.

At the time of abutment connection, a mean loss of bone height at the facial and lingual aspect of the implant amounting to 0.7-1.3 mm (P < 0.05) was recorded, whereas no significant change was noted at proximal sites. A mean reduction of 0.4 mm of the labial bone thickness was observed between implant placement and the second-stage surgery. The radiographic bone-to-implant level showed a mean loss of 0.9 mm between abutment connection and crown placement (P<0.05) and a further 0.7 mm loss at 1 year (P < 0.05). The thickness of the labial mucosa was increased at crown placement followed by a slight remission at 1 year. During the corresponding interval, a mean apical displacement of the labial soft tissue margin of 0.6 mm had taken place (P < 0.05). A papilla fill of > or = 50% was observed at a frequency of 32% at crown placement and 86% at 1 year.

The results demonstrated that following implant surgery remodeling takes place, which is manifested in diminished bone dimensions, both horizontally and vertically, at the facial aspect of the implant. The observed soft tissue alterations after the crown placement may affect the esthetic appeal of the restorative therapy.