LAUSR

OBJECTIVES to assess the impact of collagen membrane application on bone formation surrounding implants placed simultaneously with the bone ring technique. MATERIAL AND METHODS Dental implants were inserted simultaneously with the bone ring technique in standardized, vertical alveolar bony defects in the mandible of dogs. On one side of the mandible the augmented sites were covered with a collagen membrane (M Group). On the contralateral side, no membranes were used (NM Group). Implants were left to heal with osseointegration for three and six months. The harvested samples were analyzed by means of micro-CT. RESULTS A non-parametric analysis of data revealed that the membranes were not a significant negative factor for bone volume (BV), but for bone-to-implant contact (BIC, p = .04). Absence of healing caps impaired BV (p = .04) and BIC (p = .02) as well. Furthermore, loss of healing caps and exposure to the oral environment significantly and negatively affected BV (p < .001) and bone mineral density (p < .05) within 2 mm below the implant shoulder. Implant exposure and healing time had a negative interaction effect on both BV (p = .01) and BIC (p = .01). CONCLUSIONS Within its limitations, the present study revealed no benefit of membrane application to implant placement simultaneous with the bone ring technique. Disruption of soft tissue healing was identified as a risk factor for decrease in BV and BIC.