| Objective To establish an animal model to study how to remove osseointegrated dental implants by thermal stimulation with minimally invasive.To provide a new method of removing a failed dental implant,which could lay a foundation for the removal surgury by thermal stimulation in the future.Methods The study divided into three procedure:First,established the dog model with osseointegrated dental implants,five mongrel dogs of 1-2 years old were selected as experimental animal.The third or fourth mandibular premolars were extracted and dental implants were placed in the edentulous area after 2 months.The osseointegration was confirmed by clinical and radiological examination after 3 months;Secondly,Study of thermal stimulation to remove osseointegrated implants,the right side of dogs was randomly selected as experimental group for thermal stimulation,and the left side as blank control group.48±1? for 1min(stimulation A),53 ± 1 ? for 2.5min(B),59 ± 1 ? for 3.5min(C)were used to stimulate the experimental group respectively.The probing depth(PD),modified plaque index(m PLI),implant stability quotient(ISQ),radiological manifestations and probability to remove the implants by torque wrench of bilateral implants were observed and measured at the 4th week after and before thermal stimulation.Thirdly,the experimental implants were removed by the thermal stimulation,when the the implants of left side removed by using trephine.Measuring the width and height of both sides before removal surgery,2 months after removal surgery,2 months after removal surgery,and comparing bone changes of the alveolar ridges.SPSS22.0 statistical software was used to analyze the statistical data of the experiment.Results There was no significant difference in experimental group and control group on ISQ,m PLI and PD between after 4 weeks and before stimulation A and B,and there was no obvious change in radiography.The implant could not be removed by torque wrench.Compared with the control group in stimulation C,the ISQ of the experimental group decreased significantly(P <0.05),and the X-ray shows linear low density image around the implant,and the bone density around the low density image increased slightly.But there was no significant difference in m PLI and PD(P> 0.05).On the experimental group,the implants could be removed with the torque of 50 Ncm,and the control group could not be removed.2 months after implants' removal,the alveolar bone of both sides healed well.Compared with the preoperation of removal in experimental side,there was no significant change in width and height(P>0.05).Compared with the experimental side,the width and height of alveolar ridge of control side reduced more(P<0.05)3 months after removal.There was no significant difference between 3 months and 2 months after operation in groups(P> 0.05).Conclusion The dog model of removing osteointegrated implants with minimal trauma by thermal stimulation is successfully established.The animal experiment demonstrates that appropriate thermal stimulation(59 ± 1 ? for 3.5 min)can destroy the bone around dental implant limitedly. |
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