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 ( RP 2) or without removing non‐integrated DBBM ( RP 1). In RP 2 and SH sites, GBR was applied using a demineralized bovine bone mineral and a resorbable membrane. Impressions were taken postextraction ( SH )/postridge preservation ( RP 1; RP 2), 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 ( RP 1; RP 2) 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 RP 1 (−5.5%) compared to group SH (−23.4%; p  = .0013) and group RP 2 (−22.1%; p  = .0026). Encompassing the entire study period, median ridge width changes ranged between −17.8% ( SH ), −24.8% ( RP 2) and −32.5% ( RP 1) ( 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.