Effects of rhBMP-2/7 Heterodimer and RADA16 Hydrogel Scaffold on Bone Formation During Rabbit Mandibular Distraction.

PURPOSE: The effects of a recombinant human bone morphogenetic protein-2/7 (rhBMP-2/7) heterodimer and a RADA16 (Ac-RADARADARADARADA-CONH2) hydrogel scaffold on bone formation during distraction osteogenesis were evaluated. MATERIALS AND METHODS: Forty New Zealand white rabbits, which underwent mandibular lengthening, were randomly divided into 5 groups. One group served as the control group. The others received 2 µg of rhBMP-2 homodimer, 2 µg of rhBMP-2/7 heterodimer, 100 µL of RADA16, or 100 µL of RADA16 plus 2 µg of rhBMP-2/7 heterodimer in the mandibular distraction gap at the beginning of distraction. Fluorine-18-labeled fluoride positron emission tomography was used to assess osteogenesis both after distraction and at the end of consolidation. Dual-energy x-ray absorptiometry (DEXA) examination and bone histologic findings were also evaluated. RESULTS: At the end of distraction, the radioactivity concentration in the distracted area was significantly greater in the RADA16 plus rhBMP-2/7 heterodimer group than in the other groups (P < .01). The differences among the other 4 groups were also statistically significant in the following order: rhBMP-2/7 heterodimer group greater than the rhBMP-2 homodimer group, which was greater than the RADA16 group (or control group; P < .05). However, the radioactivity concentration of the RADA16 group was slightly greater than that of the control group with a nonsignificant difference (P > .05). By the end of consolidation, the activity in the control group, RADA16 group, rhBMP-2 homodimer group, and rhBMP-2/7 heterodimer group had significantly diminished (P < .05). However, the activity in the RADA16 plus rhBMP-2/7 heterodimer group remained at the same level (P > .05). The DEXA results and bone histologic findings indicated that more callus regeneration was noted in the RADA16 plus rhBMP-2/7 heterodimer group than in any other group. CONCLUSIONS: The use of rhBMP-2/7 heterodimer and RADA16 hydrogel scaffold significantly promoted mandibular distraction osteogenesis.

H2O2/HCl and heat-treated Ti-6Al-4V stimulates pre-osteoblast proliferation and differentiation.

The purpose of the present study was to evaluate the bioactivity of chemical treatment of titanium alloy (Ti-6Al-4V) in vitro. Smooth-surface discs of Ti-6Al-4V were used in this study. Sandblasted, dual acid-etched and H(2)O(2)/HCl heat-treated discs were set as test group, and sandblasted, dual acid-etched discs as control group. SEM and XRD analysis revealed a porous anatase gel layer on rough surface in the test group and a rough surface in the control group. Mouse pre-osteoblasts (MC3T3-E1 cells) were cultured on these 2 group discs, and then cell proliferation and differentiation were examined 4 days, 7 days, and 14 days after cell seeding. Cell proliferation was greatly stimulated at all time points when cultured in test group (P < .05). The alkaline phosphatase (ALP) activity and osteocalcin (OC) production were much higher in the test group compared with the control group at every time point investigated (P < .05). Furthermore, in the test group, the expressions of alkaline phosphatase-2, osteocalcin, and collagen type I alpha 1 mRNAs were significantly up-regulated as compared with those in the control group (P < .05 or P < .01). The results suggested that H(2)O(2)/HCl and heat-treatment might facilitate better integration of Ti-6Al-4V implants with bone.

[Clinical evaluation of wedge-shaped defect restored by gingival retraction technique].

OBJECTIVE: To evaluate the periodontal conditions after the wedge-shaped defect was restored by gingival retraction technique. METHODS: A total of 138 mandibular premolars with wedge-shaped defect were selected and divided into A, B groups. Group A was restored with Dyract after using retraction cord. Group B was directly restored with Dyract. Clinical parameters including plaque index (PLI), gingival index (GI), sulcus bleeding index (SBI), probing depth (PD), volumes of gingival crevicular fluid (GCF) and levels of aspartate aminotransferases (AST) of gingival crevicular fluid were measured at baseline, 1 week, 1 month, 3 months and 6 months after operation. RESULTS: There was no difference in PLI, GI, SBI, PD between group A and B during 6 months after operation, while the difference of GCF and AST was significant between group A and B at 3 months and 6 months after operation (P < 0.05, P < 0.01). CONCLUSIONS: Gingival retraction technique applied in wedge-shaped defect restoration can reduce the damage to the periodontal tissue.

[The influence of autogenous bone graft in cleft palate on maxillary growth: an experiment study in rats].

PURPOSE: This study was designed to investigate the influence of autogenous bone graft in cleft palate on maxillary growth in rats. METHODS: Forty Wistar strain male rats aged 4 weeks were randomly divided into four groups. Each group had 10 rats. Group 1 was the unoperated control group. Group 2 had a surgically created cleft palate but unrepaired. Group 3 also had a surgically created cleft palate which followed by a two-flap palatoplasty repair immediately. Group 4(experimental group) also had a surgically created cleft palate, but the cleft palate was reconstructed by autogenous rib graft with two-flap repair. All animals were sacrificed on the 10th week after operation. The data were analyzed using SPSS. And one-way ANOVA was used for comparison of the four groups. RESULTS: The experimental group was significantly smaller than unoperated control group and cleft palate group in the maxillary widths variables, length variables (AD),height variables(P<0.01).Except rats in the experimental group had significantly greater posterior palate width than rats in two-flap repair group(P<0.01),there were no significant difference between the two procedures in maxillary growth variables(P>0.05).But the experimental group was smaller in the maxillary heights, length variables than the two-flap group. CONCLUSIONS: These findings showed that repair of the cleft palate by autogenous rib graft had positive effect on preventing the contraction of maxillary width. But in the maxillary anteroposterior and vertical development, the experimental group possibly had more severe retardation than two-flap repair group.