Impact Of Different Periodontal Phenotypes On The Stability Of Mini-implants

Objective: To investigate the effect of different periodontal phenotypes on the stability of orthodontic mini-implants.The results of the experiment can guide clinicians to take individualized treatment as well as preventive measures for patients with different periodontal phenotypes,aiming to increase the success rate of mini-implants in orthodontic treatment.Methods: This study was a prospective study.100 young female patients with skeletal class II malocclusion who were treated in our orthodontic department from August 2020 to June 2022 were selected for the study.The gingival thickness(GT)was measured using transgingival probing method under local anesthesia.According to the gingival thickness,50 patients with thin phenotype and 50 patients with thick phenotype.These patients were extracted 2 first premolar and implanted mini-implants between the second premolar and the first molar in the maxilla,both were loaded with200 g immediately.Monthly follow-up.Plaque index(PLI),sulcus bleeding index(SBI),probing depth(PD),the number of peri-implantitis and successful cases of the two groups were compared and analyzed.Results: The mean gingival thickness of the thin group was(0.85±0.05)mm,and was(1.36±0.07)mm in the thick group.The gingival thickness in the thin group was significantly less than that in the thick group(P<0.01).After six months,the indices of SBI,PD,PIL of the thin phenotype mini-implants were 1.22±0.54,1.51±0.52,1.62±0.60.And the indices of SBI,PD,PIL of the thick phenotype mini-implants were 1.05±0.31,1.33±0.47,1.43±0.54.The SBI,PD and PLI index in the thin group were significantly higher than the thick group,and the differences were statistically significant(P=0.032,P=0.014 and P=0.023).The number of peri-implantitis in the thin phenotype group was 10,the incidence was 10%.And the number of peri-implantitis in the thick phenotype group was 3,the incidence was 3%.The incidence of peri-implantitis in the thin phenotype group were significantly higher than those in the thick group(P=0.045).The number of successful for thin group was 82,and that for thick group was 92.The stability of thin group was significantly lower than that in the thick group(P=0.036).Conclusion: In the female patients studied,the gingival thickness at the mini-implant placement site was significantly less in the thin group than in the thick group.The thin group was more susceptible to external irritation and inflammatory response than the thick group.The incidence of peri-implantitis in thin group were significantly higher than that in the thick group.The stability of thin group is significantly lower than that of the thick group.