Bone formation in large/moderate gap after immediate implantation in response to different treatments: a pre-clinical study in the canine posterior mandible

Abstract

Objectives: This study aims to investigate different treatments on new bone formation around immediate implants in the canine posterior mandible with varying sized mesial-distal gap.

Materials and methods: The 4th premolar and the 1st molar of six Labrador dogs were extracted from the mandible, and 4 dental implants were placed 1 mm below the level of the buccal bone crest. Moderate/large mesial-distal gaps between the implants and the sockets were treated with one of four methods and divided into the following groups: (1) the blank group, (2) the collagen membrane (CM) group, (3) the deproteinized bovine bone mineral (DBBM) group, and (4) the DBBM + CM group. Sequential fluorescent labeling was performed at 4, 8, and 10 weeks after the operation. After 12 weeks, the dogs were euthanized, and specimens were collected for micro-CT scanning and histological analysis.

Results: The survival rate of immediate implant was 100%. Micro-CT showed significant differences in bone mineral density (BMD) and bone volume fraction (BVF) among groups (P = 0.040, P = 0.009); other indicators were not significantly different among groups. Histological analysis showed the proportion of new bone formation and bone-to-implant contact were not significantly different among groups. No significant difference in bone reduction height around dental implant among four groups and varied mesial-distal gap size.

Conclusion: Owing to the restricted sample size, this pilot study lacks conclusive findings. Within the limitation, this study demonstrated that although DBBM significantly increase BMD and BVF, the use of DBBM/CM didn't significantly improve bone formation and healing in extraction sockets around the implants in both moderate and large mesial-distal gap.

Clinical relevance: The use of deproteinized bovine bone in conjunction with collagen is a common practice in immediate implantation procedures in the posterior mandible. However, there is a lack of conclusive evidence regarding the timing and circumstances under which they should be employed.

Keywords: Bone formation; Extraction socket; Immediate implants; Posterior mandible.