The Experimental Study On Reimplantation Of Avulsed Teeth

Dental avulsion is a serious traumatic injury which is involved with theperiodontal ligament, cementum, alveolar bone, gingival and pulp tissues. Thebest treatment of it is accepted as re-implantation. However, the avulsed teethare generally complicated by root resorption after replantation which make theteeth fall off. This invariably leads to the failure of tooth replantation.The success of the dental reimplant depends on the re-establishment of theperiodontal ligament, and the precondition is the function of the aliveperiodontal ligament cell. Huge amounts of experiments and clinical researcheson factors have been finished in order to increase the success rates of thereplantation. These studies have found that the important factors about thesuccess of avulsed tooth depend on the extra-oral time, storage conditions andappropriate root surface treatment. The extra-oral time and storage conditionsare the most important factors in determining the viability of the remaining PDL cells, and thus affect the success rates of the tooth re-implantation. Yet, How toreduce the number of viable PDL cells with the prolongation of the dry time?How to lead to resorption of the root of the replanted tooth?How to effects onthe healing types of replantation tooth?This kind of study is less. Propolis is aresinous hive substance produced by honeybees from products collected fromplants. The substance contains multiple biological activity material. Propolis isable to promote proliferation of the human periodontal ligament fibroblasts invitro. In dentistry, the propolis has been applied in periodontology. In dentaltraumatology, there are some studies that evaluated the use of propolis as astorage medium for avulsed teeth and root surface treatment in cases of delayedtooth replantation abroad. But the study on the use of propolis is few at home.The aim of this research is to evaluate the viability change of the PDL cellsof the avulsed teeth in different extra-oral timing and storage medium, and tostudy whether propolis could promote the periodontal healing of delayed teeth.We evaluated the viability change of the PDL cells of the avulsed dog’s teeth indifferent extra-oral timing and storage medium by0.4%Trypan Blue Stains. Wealso applied propolis in the avulsed dog’s teeth replantation. After that，Wewatch the tissue recovery of replanted tooth through sections, and analysis thefunctions of propolis on the recovery of replanted tooth, and provideexperimental basis for the treatment of tooth re-implantation. The study aredivided in three experiments as follows:Experiment one: The vitality assessment on the periodontal ligament cellsderived from the avulsed dog’s teeth in different extra-oral time.The20dog teeth were extracted under local anesthesia, after that the teethwere divided into5groups. The extracted teeth were stored in room conditionfor0,30,60,120,240min respectively. The PDL cells were isolated by direct enzymatic digestion method, and the number of them were examined by0.4%Trypan Blue Stains. The results show that the number of viable PDL cellsdecreased with the prolongation of the dry time. At0,30,60,120and240minutes, the survival rate of PDL cells was95.5%,33.6%,23.6%,18.5%and0.8%respectively. Conclusion: The number of viable PDL cells remarkablydecreased with the prolongation of the dry time.Experiment two: Comparison on PDL Cell survival of the avulsed dog’steeth in different storage mediums.The15dog teeth were extracted under local anesthesia, after that, theywere divided into3groups. The extracted teeth have been stored in roomcondition for30min, which were divided into3groups and were treated withthree storage medium for2hours, HBSS, milk and10%Propolis respectively.The above method was used for the assessment on PDL cell livability. Theresults show that the PDL cells all have vitality when the teeth stored in10%Propolis, HBSS and milk for2hours. There were no significant statisticdifferences between10%Propolis and HBSS, but there was significantdifference between milk group and the other. Conclusion: The10%Propolis andHBSS were better in maintaining PDL cell viability than milk.Experiment three: Effect of different root surface treatment on delayedtooth replantation in dogs.The24dog teeth were extracted under local anesthesia, after that they weredivided into4groups. The teeth were maintained in a dry environment for60min. And then, the pulp was extirpated and the papilla, enamel organ andperiodontal ligament were removed. The teeth were immersed in20ml of2%fluoride solution and20ml of20%propolis respectively. After30min ofimmersion in the solutions, the root canals were dried and filled with calcium hydroxide paste and the teeth were replanted. The immediately replantationgroup was the positive control. The negative control teeth were air-dried andreplanted without further treatment. The animals were euthanized60days afterreplantation. Study the resorption by observing the sections. Calculate the rootresorption rate of the replanted tooth and the rate of surface resorption，inflammatory resorption or replacement resorption. The results showed that theroot resorption rate of the20%propolis solution,2%fluoride solution and thenegative control groups increase gradually, and there were significant differentamong them(P <0.05). The negative control teeth tended to have moreinflammatory root resorption compared with those treated with fluoride orpropolis. The positive control teeth tended to have more inflammatory rootresorption compared with those treated with fluoride or propolis. However, thecomparative analysis did not reveal statistically significant differences (P>0.05)between the treatment modalities when used for delayed tooth replantation.Conclusion: Both20%propolis solution and2%fluoride solution can promotethe healing of periodontal tissue of replanted tooth and reduce the inflammatoryresorption, and there were no significant differences between them.