Guided bone regeneration with intentionally exposed membranes and its implications for implant d

Aim Post-extraction alteration of the alveolar bone topography is one of the main problems associated with tooth loss. Guided bone regeneration (GBR) technique avoids in great part alveolar bone resorption after extractions This randomized controlled study aimed to evaluate the influence of early membrane exposure on GBR in humans. Materials and methods The study involved 13 patients, each with 2 premolars with orthodontic indication for extraction. After extractions, clinical measurements were recorded for alveolar depth (AD), buccal-lingual (BL) and mesio-distal (MD) dimensions of the alveoli, and radiographic measurements for radiographic alveolar depth (RAD), width (AW), and total alveoli area (AA). Polytetrafluorethylene (e-PTFE) membranes were then adapted and fixed over the extraction sockets, and based on membrane coverage sockets were divided in: Group I - flap was rotated to completely cover the membrane; Group II - flap was conventionally replaced and membrane remained, intentionally, partially exposed. All patients received antibiotics and after 4 weeks all membranes were removed. Patients were followed up to 6 months, when new X-rays were taken and re-entry surgeries were performed to obtain final clinical and radiographic measurements. Results Mean variation between pre and post-operative measurements for Group I were: AD=12.01; BL=9.16; MD=5.66; RAD=12.17; AW=5.45; AA=38.43; and for Group II were: AD=10.23; BL=8.41; MD=5.08; RAD=10.08; AW=4.94; AA=31.88. Group I presented significantly higher clinical and radiographic values (Mann-Whitney test, p<0.05) comparing to Group II, regarding all studied parameters. Conclusions Early e-PTFE membrane exposure had a negative effect on alveolar bone formation in humans.