| Objective: The purpose of this study is to observe the effect of cryopreservation on transplanted teeth,to study the prognosis of tooth autotransplantation after cryopreservation,to widen the indications of tooth autotransplantation,and to provide theoretical support for clinical preservation of extracted wisdom teeth for selective transplantation.Methods:three adult male beagle dogs with 27 left upper and lower first teeth,second incisor,third incisor and first premolar were used as experimental subjects.The experimental group A(left upper first incisor,second incisor,third incisor)was placed in normal saline after extraction and cryopreserved at-80 ℃ for 2 weeks.Group B(left lower first incisor,second incisor,third incisor)was placed in 10% DMSO solution after extraction and cryopreserved at-80 ℃ for 2 weeks.Control group C(3 first premolars)were transplanted as control group.The general condition,tooth mobility,probing depth(PD)and imaging findings of beagle dogs were observed and recorded regularly.One dog was killed randomly every 4 weeks after operation,and the mandible was taken for micro CT examination and decalcification section to observe the histopathological changes.The gingival attachment,apical inflammation,changes of root and peri root alveolar bone were compared between frozen and immediate grafts.Results: 1.Clinical observation: there was no accidental death,systemic or local infection in all dogs.In experimental group A,one tooth fell off 4weeks after operation(11.1%),two teeth fell off 8 weeks after operation(33.3%),one tooth fell off 12 weeks after operation(44.4%);In group B,one tooth fell off 4 weeks after operation(11.1%),one tooth fell off 8weeks after operation(22.2%)and one tooth fell off 12 weeks after operation(33.3%);In control group C,one tooth fell off 8 weeks after operation(11.1%).2.With the increase of time,the mobility of grafted teeth was improved,but some teeth were loose and dropped;At 4 weeks after operation,the PD value of experimental group A was higher than that of control group C(P< 0.05);The PD value of experimental group B was higher than that of control group C,and the difference was not statistically significant(P >0.05);The PD value of experimental group A was higher than that of experimental group B,and the difference was statistically significant(P <0.05).At 8 weeks after operation,the PD value of experimental group A was higher than that of control group C(P < 0.05);The PD value of experimental group B was higher than that of control group C,and the difference was not statistically significant(P > 0.05);The PD value of experimental group A was higher than that of experimental group B,and the difference was statistically significant(P < 0.05).At 12 weeks after operation,there was only one tooth left in experimental group A,so the PD value of experimental group B was higher than that of control group C(P < 0.05).3.Imaging observation: in the experimental group A,the cervical absorption occurred at the 4th week,the absorption aggravated at the 8th week,and individual teeth absorbed to the crown at the 12 th week.In the experimental group B,the cervical absorption occurred at the 4th week,and gradually aggravated at the 8th week,and the absorption of individual teeth was more than 1 / 3 in the root at the 12 th week;in the group C,the absorption occurred outside the root at the 8th week,and aggravated at the12 th week.No apical shadow was found in all teeth.4.Bone mass comparison:At 4 weeks after operation,there was no significant difference in BV / TV between experimental group A,experimental group B and control group C(P > 0.05).At 8 weeks after operation,BV / TV of experimental group A was lower than that of control group C(P < 0.05);Bv / TV of experimental group B was lower than that of control group C,and the difference was not statistically significant(P >0.05);Bv / TV of experimental group A was smaller than that of experimental group B,with statistical significance(P < 0.05).At 12 weeks after operation,there was only one tooth left in experimental group A,so only experimental group B and control group C were analyzed.The results showed that bv / TV of experimental group B was less than that of control group C,with statistical significance(P < 0.05).5.Histological observation:in the experimental group A,the apical granulation tissue proliferated at 4weeks after operation,the cementum was not damaged,and there was superficial absorption at 8 weeks,the osteoclasts were active,and only the middle layer of dentin was absorbed at 12 weeks;in the experimental group B,the cementum showed shallow concave absorption,the fibers were irregular,and the absorption was heavier at 8 weeks,and the individual root dentin was completely absorbed at 12 weeks;in the group C,the cementum was intact at 4 weeks,and the root dentin was completely absorbed at 8 weeks The absorption at 12 weeks was similar to that at 8 weeks.Conclusion: The results showed that the healing of teeth preserved by cryopreservation was similar to that of immediate autogenous tooth transplantation.The healing of teeth preserved by cryoprotectant was better than that of teeth preserved by immediate autogenous tooth transplantation,which may be related to the protective effect of cryoprotectant on periodontal ligament cells.However,in the long-term observation,serious alveolar bone absorption and root resorption occurred.In addition to freezing injury,it may also be related to surgical mechanical injury and thermal stimulation.It is necessary to further improve the operation methods and operating instruments,optimize the freezing procedure,and also need more samples and longer observation and study. |
PDF Full Text Request