Effect Of Three Incision Designs On The Impacted Lower Third Molar Extraction On Periodontal Parameters Of Adjacent Second Molar

Objective:To compare the clinical periodontal status of the adjacent second molar(ASM)between different incision designs-the envelope incision,the triangular incision and the modified triangular incision after impacted lower third molar extraction,to provide theoretical guidance for clinical practice.Methods:Patients diagnosed with completely submucosal impacted lower third molars extraction were enrolled and then randomly allocated to the envelop flap group,the triangular flap group and the modified triangular flap group,which were given the envelop incision,the triangular incision and the modified triangular incision respectively,to remove their teeth in the Department of Oral and Maxillofacial Surgery,Stomatological Hospital of Shanxi Medical University from May 1st,2021 to July 31 th,2021.The surgeries were performed by the same senior chief physician and other surgical conditions were the same except for the incision designs.Preoperative imaging of curved tomography to understand the relationship between the ILTM and the ASM,the resistance,the relationship between the mandibular canal and the ILTM.The basic patients information in the three groups was collected,and the periodontal conditions of the ASM was assessed by the probing pocket depth(PPD),attachment loss(AL),plaque index(PLI)and bleeding index(BI)at six sites(mesio-buccal,mid-buccal,disto-buccal,disto-lingual,mid-lingual,mesio-lingual).Measurements were taken preoperatively and1 week,4 week,12 week postoperatively.Statistical analysis was conducted using Graphpad Prism 8.0.2.263 software.Results:1.General condition: A total of 90 patients were followed up,including 30 patients in the envelop flap group,32 patients in the triangular flap group,and 28 patients in the modified triangular flap group.The preoperative demographic characteristics of participants were homogeneous among three groups(P>0.05).2.Periodontal conditions: At baseline,the periodontal indexes of ASM among the three groups were no significant differences(P>0.05).Except for the disto-buccal and disto-lingual sites of the second molar,the PPD and AL of other sites were not significantly different from those before surgery.To futher clarify the effect of ILTM extraction on ASM distal periodontal tissue,the mean values of the distal buccal and distal lingual were used as the final values of the d PPD、d AL、d PLI and d BOP.At 1 week and 4week after surgery,the d PPD,d AL,d PLI and d BOP of ASM were all increased compared with those before surgery,and compared with the envelop flap group and triangular flap group,the modified triangular flap group was significantly reduced,the difference was statistically significant(P<0.05).The distal periodontal conditions of the adjacent second molars at 12 weeks after surgery was basically restored to preoperation.Conclusion:ILTM extraction can disproportionately affect on ASM periodontal tissue.The three incision designs all lead to the increase of d PPD,d AL,d PLI and d BOP,but compared with the envelope incision and the triaugular incision,the modified triangular incision had less effect on clinical periodontal parameters.