Measurement And Analysis Of Soft And Hard Tissue Changes Of Mandibular Prognathism By Surgery First Approach

Objective:Based on Surgery-first approach treatment,with simple sagittal split ramus osteotomy(BSSRO)and rapid postoperative orthodontic to treat mandibular prognathism,to evaluate the changes of soft and hard tissue profile of the patients by analysis of the relationship between the changes of soft and hard tissue before and after operation.All the results to guide the formulation of the plan,and to predict the effect of the operation.Methods:To collect the X ray cephalometric of mandibular prognathism treated in the Department of Maxillofacial Plastic Surgery,Plastic Surgery Hospital,Chinese Academy of Medical Sciences from January 2010 to December 2016 were included in this study.The X ray cephalometric of patients with TO(preoperative),T1(one week after surgery)and T2(6 months or more)were measured and analyzed,then to evaluate the correlation between soft and hard tissues changes and to gennerate soft tissue to hard tissue movement ratios.Results:After Surgery-first approach treatment(1)Sagittal change of Hard tissue:B,D,Pog,and Me point set back 9.54mm,9.45mm,9.87mm and 9.29mm separetively(P<0.001).The mandible was retreated and the mandibular protrusion was relieved.SNB,ANB and SND wits become near the normal value.(2)Sagittal change of Soft tissue:After the treatment,LL,Si,Pos and Mes point set back 8.12mm,9.96mm,10.62mm and 10.12mm separetively(P<0.001).Compare to the beginning of the treatment,most index of the soft tissue in this study were changed stastistically,such as Cm-Sn-UL,LL-Si-Pos wits become near the normal value,facial profile improved significantly.(3)The recurrence degree of the Hard tissue in each group:LI,B,Pog and Me were 22.8%,23.4%,26.1%and 27.3%,respectively,but the degree of recurrence was less than 2mm.(4)The correlation between soft and hard tissue changes:there is a strong moderate correlation between the soft and hard tissue movement(r>0.80),LL:LI=96.8%,SB:B=105.9%,Pos:Pog=100.2%,Mes:Me=80.8%.Conclusion:The results of this study supported that Surgery-first approach can correct the mandibular protrusion,shorten the period of treatment.To evaluate the patients with postoperative effect of hard and soft tissue,we found the mandibular prognathism have significantly improved and the facial type of the patients presurgically with a concave profile had been changed to normal.Although relapse of the sagittal and vertical movements had been observed,but the relapse were in an acceptable range within 2mm.In the sagital direction,there is a strong correlation between the soft and hard tissue changes.So we recommended to use Surgery-first approach as one of the treatment choices to treat mandibular prognathism.