Volumetric changes following ridge preservation or spontaneous healing and early implant placement with simultaneous guided bone regeneration

AIM To assess volumetric and linear changes following ridge preservation (RP) or spontaneous healing plus early implant placement with or without simultaneous guided bone regeneration (GBR). MATERIALS AND METHODS In eight adult beagle dogs, the mesial roots of the mandibular P3, P4 and M1 were extracted. Sites were randomized to either ridge preservation (RP) or spontaneous healing (SH). Four weeks later dental implants were placed either with (RP2) or without removing non-integrated DBBM (RP1). In RP2 and SH sites, GBR was applied using a demineralized bovine bone mineral and a resorbable membrane. Impressions were taken postextraction (SH)/postridge preservation (RP1; RP2), before and after implant placement and after healing of 4 and 12 weeks. Casts were digitized to allow for superimposition and measurement of contour alterations. RESULTS Median ridge width reduction from postextraction (SH)/postridge preservation (RP1;RP2) to implant placement ranged from -13.9% (SH) to -19.7% (RP) (p > .05), whereas from implant placement to sacrifice, it was statistically significantly lower in group RP1 (-5.5%) compared to group SH (-23.4%; p = .0013) and group RP2 (-22.1%; p = .0026). Encompassing the entire study period, median ridge width changes ranged between -17.8% (SH), -24.8% (RP2) and -32.5% (RP1) (p > .05). CONCLUSIONS Irrespective of the treatment modality and the healing period, part of the ridge contour was lost. Early implant placement after ridge preservation without additional GBR resulted in a more stable ridge contour after implant placement compared to controls.