(65) Influence of blinded wound closure on the volume stability of different octacalcium phosphate (OCP) bone substitute and procedures: an in vitro cone-beam computed tomographic(CBCT) examination

Introduction: The aim of this study was to investigate the change of volume stability through cone-beam computed tomographic (CBCT) after wound closure following guided bone regeneration (GBR) of peri-implant bony defects depending on the difference in the bone graft material and the use of a fixation pin.

Methods: Twenty peri-implant box-shaped bony defects were created in 10 pig mandibles. Bony defect was augmented once with each of the following GBR procedures: (i)Particulated octacalcium phosphate(OCP) bone substitute + collagen membrane(Group 1), (ii)Particulated OCP bone substitute + collagen membrane + fixation pins(Group 2), and (iii)Moldable OCP bone substitute + collagen membrane(Group 3). CBCT scans were obtained before and after blinded wound closure. The horizontal thickness(HT) of the augmented region was assessed at the implant shoulder(HT0 mm) and at 1–5 mm apical to the implant shoulder(HT1 mm–HT5 mm). The changes of HT during wound closure were calculated as absolute(mm) and relative values (%). Repeated-measures ANOVA was used for statistical analysis.

Results: Wound closure induced a statistically significant change of HT0 mm and of HT1 mm in all the treatment groups(P ≤ 0.05). The change in HT0 mm measured 29.18 ± 13.57% for Group 1, 13.01 ± 10.38% for Group 2, and 13.63 ± 14.50% for Group 3. The reduction in HT0 mm, HT1 mm, HT2 mm, and HT3 mm for Group 1 was significantly higher as compared to Group 2 and Group 3. There were no statistically significant differences in the change of HT between Group 2 and Group 3.

Conclusions: Wound closure induced displacement of the bone substitute resulting in a partial collapse of the collagen membrane in the coronal portion of the augmented site. The stability of volume after GBR was enhanced by the application of fixation pins and by the use of moldable OCP bone substitute.

Lead Author's Contributions to the Research Project. : The Lead Author was responsible for the data collection, performing the data analysis and the composition of the abstract.