Bone healing in critical-size defects treated with platelet-rich plasma activated by two different methods. A histologic and histometric study in rat calvaria.

BACKGROUND AND OBJECTIVE: The purpose of this study was to analyze histologically the influence of platelet-rich plasma (PRP) coagulated with two different activators on bone healing in surgically created critical-size defects (CSD) in rat calvaria. MATERIAL AND METHODS: Forty-eight rats were divided into three groups: C, PRP-C and PRP-T. An 8 mm diameter CSD was created in the calvarium of each animal. In group C, the defect was filled by a blood clot only. In groups PRP-C and PRP-T, the defect was filled with PRP activated with either calcium chloride or thromboplastin solution, respectively. Each group was divided into two subgroups (n = 8 per subgroup) and killed at either 4 or 12 weeks postoperatively. Histologic and histometric analyses were performed. The amount of new bone formed was calculated as a percentage of the total area of the original defect. Percentage data were transformed into arccosine for statistical analysis (analysis of variance, Tukey's post hoc test, p < 0.05). RESULTS: No defect completely regenerated with bone. Group PRP-C had a statistically greater amount of bone formation than groups C and PRP-T at both time points of analysis. No statistically significant differences were observed between groups C and PRP-T. CONCLUSION: It can be concluded that the type of activator used to initiate PRP clot formation influences its biological effect on bone healing in CSD in rat calvaria.

Bone healing in critical-size defects treated with platelet-rich plasma: a histologic and histometric study in rat calvaria.

BACKGROUND AND OBJECTIVE: The purpose of this study was to analyze histologically the influence of autologous platelet-rich plasma on bone healing in surgically created critical-size defects in rat calvaria. MATERIAL AND METHODS: Thirty-two rats were divided into two groups: the control group (group C) and the platelet-rich plasma group. An 8-mm-diameter critical-size defect was created in the calvarium of each animal. In group C the defect was filled by a blood clot only. In the platelet-rich plasma group, 0.35 mL of platelet-rich plasma was placed in the defect and covered by 0.35 mL of platelet-poor plasma. Both groups were divided into subgroups (n = 8) and killed at either 4 or 12 wk postoperatively. Histometric (using image-analysis software) and histologic analyses were performed. The amount of new bone formed was calculated as a percentage of the total area of the original defect. Percentage data were transformed into arccosine for statistical analysis (analysis of variance, Tukey, p < 0.05). RESULTS: No defect completely regenerated with bone. The platelet-rich plasma group had a statistically greater amount of bone formation than group C at both 4 wk (17.68% vs. 7.20%, respectively) and 12 wk (24.69% vs. 11.65%, respectively) postoperatively. CONCLUSION: Within the limits of this study, it can be concluded that platelet-rich plasma placed in the defects and covered by platelet-poor plasma significantly enhanced bone healing in critical-size defects in rat calvaria.

Comparative study of collagen and expanded polytetrafluoroethylene membranes in the treatment of human class II furcation defects.

The purpose of this study was to compare the changes in clinical attachment when either a non-resorbable ePTFE membrane or an absorbable collagen membrane was used as a barrier during surgical treatment of class II molar furcation defects. Thirteen patients, mean age 43.2 years, with two comparable class II molar defects were treated using a split mouth design. Pre-surgical standardized probings were made using an automated probe at a constant force of 25 grams. Four to 6 weeks after initial therapy, the furcations were surgically debrided, the membranes placed to occlude separate furcation defects in each patient, and the sites closed. The ePTFE membrane was removed 6 weeks after placement. Six months postsurgery, the clinical measurements were repeated. Student t test was used to compare the results. There were no significant differences in the mean initial measurements between the treatment groups. The mean decrease in vertical probing depth was 1.40 +/- 1.68 mm for the collagen treated sites and 1.07 +/- 0.81 mm for the ePTFE treated sites. The decrease in horizontal probing depth was 1.49 +/- 1.97 mm for the collagen treated sites and 0.79 +/- 2.16 mm for the ePTFE treated sites. No significant differences were found between any of the clinical parameters measured. Based on the results of this short-term clinical study, the absorbable collagen membrane was statistically equivalent to the non-resorbable ePTFE membrane in the clinical resolution of class II furcation defects.

Small versus large particles of demineralized freeze-dried bone allografts in human intrabony periodontal defects.

Various particle sizes of demineralized freeze-dried bone allograft (DFDBA) are currently used to treat patients with periodontal osseous defects. However, the effect of particle size on the healing of human intrabony periodontal defects is unknown since there have been no direct clinical comparisons. The purpose of this study was to compare the bony defect resolution obtained using two different particle size ranges of DFDBA. Cortical bone from a single donor was processed and ground to final particle sizes of 250 mu to 500 mu or 850 mu to 1,000 mu using an analytic mill. Paired interproximal intrabony periodontal defects in 11 patients were grafted with DFDBA. Soft and hard tissue measurements were made using an electronic constant-force probe at the initial and reentry surgeries. Treated sites in 10 patients were reevaluated by reentry approximately 6 months postoperatively. Mean bony defect fill was 1.66 mm for the large particle group and 1.32 mm for the small particle group. There was no statistically significant difference in bony fill between defects grafted with the different particle sizes of DFDBA when used in humans.