The Effect Of Bone Morphogenetic Protein-2on Delayed-replanted Rat Teeth

Objective: The aim of this study is to explore the effect of bonemorphogenetic protein-2(BMP-2) on periodontal healing of delayed-replantedrat teeth with animal experiment.Methods: Thirty-two male Wistar rats were used in our study. They wereweighted250-300g and provided by HeBei Medical University AnimalExperiment Centre. The animals also had well oral hygiene, no caries orperiodontitis.The animals were fed ground solid ration and water ad libitum, except forthe preoperation12h. The animals received exact weight and wereanesthetized with10%chloral hydrate(3ml/kg). Asepsis of the anterior maxillawas performed followed by non-traumatic extraction of the maxillary rightincisor of all animals. The teeth were randomly divided to four groups: GroupA:(Negative control, n=8)、Group B:(Positive control, n=8)、Group C:(BMP-2,n=8)、Group D:(BMP-2+Bio-oss, n=8).Group A: No treatment were performed, immediately replanted. GroupB、C、D: The teeth were placed on a asepsis metal tray and kept dry at roomtemperature for1h. The root canals were filled with vitapex paste injected in aretrograde way. The root apex was sealed by GIC. After root apex sealing, theteeth of Group B were replanted.Root treatment: The root surface in Group C were conditioned withBMP-2paste, and Group D with BMP-2+Bio-oss paste.Sockets treatment: Before replantation, the sockets were irrigated with5ml of saline. BMP-2paste was conditioned in the sockets of Group C, andBMP-2+Bio-oss paste was conditioned in the sockets of Group D.The teeth of Group C and D were replanted in respective sockets. Softfood was taken after operation7d.The animals’ behavior and food intake didn’t change noticeably.The animals were killed at8w after replantation with an excessive doseof anaesthetic. The anatomic pieces containing maxillary right incisor wereremoved, irrigated with saline, fixed in10%formalin and decalcified in a4%EDTA solution, pH6.9. After decalcification, the specimens were embeddedin paraffin. Subsequently, sections of the tissue blocks were madeperpendicularly to the long axes of the roots. The sections were stained byhaematoxylineosin. A histometric analysis was done. The histological slideswere divided into eight parts by four intersecting lines. The point ofintersection coincided with the center of the root canal. At the eight pointswhere the radii intersected with the outer circumference of the root surfaces,the periodontal healing pattern was registered according to the methodmodified from that described by Andreasen as cementum healing (CH): Therewas complete cementum, no inflammation. Normal periodontal healing andbone substitute healing were included; replacement resorption(RR);inflammatory resorption (IR). The occurrence of sites exhibiting each of thehealing patterns was expressed as mean percentage of the total number of sitesexamined for each section and for each root as well as for each of the fourgroups. Compare the mean percentage of each of healing patterns amonggroups.The data of four groups was statistically compared by Kruskal-Wallis testmaking a overall analysis and further analyzed with Mann-Whitney U test. Allthe above data was collected by the SPSS13.0software. Inspection standardswas to take bilateral alpha=0.05, P≤0.05which had statistical significance.Results:1Tissues were evaluated under light microscopy. Group A: After replantation,spaces in alveolar bone and root surface were reattched with periodontalconnective tissue, no inflammatory resorption or ankylosis. Group B: Afterreplantation, larger area inflammatory resorption and ankylosis were found.Group C: After replantation, spaces in alveolar bone and root surface wereinsteaded by newly formed cementum and bone, smaller area of connective tissue reattached and inflammatory resorption. Group D: presence ofcementum and connective tissue reattached, newly formed cementum andbone insteaded periodontal ligament(cementum healing).2According to the method modified from that described by Andreasen, therewere different healing patterns, computed mean percentage of each of thehealing patterns among the four groups. Cementum healing(CH):A-CH(93.404±2.580)%; B-CH(18.013±2.983)%; C-CH(18.633±4.752)%;D-CH(21.160±6.123)%; Replancement resorption(RR): A-RR (6.424±4.272)%、B-RR (65.580±4.962)%、C-RR (68.476±4.123)%、D-RR (68.900±4.370)%；Inflammatory resorption(IR): A-IR(0.173±0.489)%、B-IR(16.408±4.675)%、C-IR (12.891±7.306)%、D-IR (9.941±8.188)；The meanpercentage of each healing patterns among the four groups was tested byKruskal-Wallis taking α=0.05as the inspection standards, P<0.05, thedifference of the mean percentage of healing patterns among groups weretested. Results of the binary comparison between groups by Mann-Whitney Uwere: Group A VS Group B、C、D, P<0.05, statistical difference was tested,the healing of immediately replantation was the best; among other groups,P>0.05, there were no statistical differences.Conclusion:1After teeth avulsion, the prognosis of immediately reimplantation was thebest, obtaining the ideal cementum healing.2BMP-2and Bio-oss, alone or combination applied to the root surface andsockets helped to obtain cementum healing and inhibited root resorption tosome extent. However there was no statistical difference, bFGF and Bio-oss,alone or combination applied to the root surface and sockets could noteffectively inhibit root resorption.