RhBMP-7 improves survival and eruption in a growing tooth avulsion trauma model

Long-term loss of avulsed and replanted teeth is a frequent clinical problem. Bone morphogenetic protein-7 (BMP 7) induces cementogenesis in periodontitis-associated periodontal ligament (PDL) defects. This study's aim was to assess the utility of rhBMP 7 in a tooth avulsion trauma model in growing individuals. Immature primary incisors of 12 minipigs were extracted. PDL and cementum were removed either partially (group 1: 4 mm2 [n=28 teeth]; group 2: 16 mm2 [n=26 teeth]) or totally (group 3 [n=26 teeth]). 500 microg rhBMP 7/g collagen matrix was applied to the teeth from one side while the corresponding teeth on the contralateral side served as controls (split mouth model). After an experimental period of 4 months, microradiography, fluorescence and light microscopy of nondecalcified sections were performed. All teeth of group 1 survived and all teeth of group 3 were lost, whether rhBMP-7 was applied or not. In group 2, nine out of ten teeth survived when rhBMP-7 was applied and four out of ten teeth were lost when rhBMP-7 was not applied. In the presence of rhBMP-7, eruption of teeth in group 2 was significantly improved (difference [median]: 5 mm, P<0.05, n=6). Even though there was a tendency towards increased deposition rates of cementum under rhBMP-7, this difference was not significant (Wilcoxon: P>0.05, ANOVA: P=0.002; n=6/group). In conclusion, rhBMP-7 improved survival rates and eruption of replanted teeth in growing individuals. No adverse effects were seen. Based on the present results, future clinical trials appear to be warranted.