A 3dMD Study Of The Oral Soft Tissue Morphological Characteristics In Young Female Patients With Skeletal Class Ⅰ Gummy Smile Malocclusion

Objective: The aim isto study the the oral soft tissue morphological characteristicsin young female patientswith skeletal classⅠ gummy smile malocclusion by three-dimensional photography(3dMD),in orderto provide evidence forthe prevention and treatment of gummy smile.Methods: CBCT and 3dMD were taken in 306 patientswith new orthodontic treatment.58 female patientswere selected according to the inclusion criteria,all of whom were patientswith skeletal classⅠ(0°≤ANB≤5°).According to the gingival exposure(GE)during smiling,the sampleswere divided into two groups: the gummy smile group(30 patients,average age 22.50±2.10 years)and the non-gummy smile group(control group)(28 patients,23.32±1.96 years).CBCT imageswere imported into Invivo software to measure 8 jaw bone measurement items.3dMD imageswere imported into 3dMDvultus2.5.2 software to measure 56 facial soft tissue measurement itemsat the lip rest position and the maximum smile position.The statistical analysiswasperformed with SPSS 22.0.Results:1.In the lip rest position,the linearlength(rLLCL)and arc length(rLLCL’)of lowerlip chin in gummy smile group were greaterthan those in control group(P<0.05).2.In the maximum smile position,intercommissural width(sICW)and lip gap(sLG)in gummy smile group were significantly greaterthan those in control group(P<0.01),and the smile index(SI)and upperlip red curve height(sULRH)in gummy smile group were smallerthan those in control group(P<0.05).3.From the lip rest position to the maximum smile position,changesin intercommissural width(ΔICW)、lip gap(ΔLG)、upperlip line length(ΔULL)、upperlip arc length(ΔULL’)、upperlip line length change ratio(ΔULL/rULL)upperlip arc length change ratio(ΔULL’/rULL)、upperlip red curve height(ΔULRH)and upperlip red curve height change ratio(ΔULRH/rULRH)in gummy smile group were greaterthan those in control group(P<0.05).4.From the lip rest position to the maximum smiling position,the upward position change of the upperlip and cornersof the mouth(Lsy、CLy、CRy)and the lateral position change of the cornersof the mouth(CLx、CLx)were greaterin gummy smile group than in control group(P<0.05).5.Correlation analysisshowed that sICW、sULRH、SI、ΔULL、ΔICW、ΔULRH、ΔULL’、ΔULRH/rULRH、Lsy、CRy、Cly wasweakly correlated with Ge,and sLG 、 ΔLG 、 ΔULL/rULL 、 ΔULL’/rULL’wasmoderately correlated with Ge(P<0.05).Conclusion: The oral soft tissue morphological characteristicsof young female patientswith skeletal classⅠ gummy smile malocclusion were : 1)The length of upperlip wasthe same asnormal;2)Perioral muscle ishyperactive during smiling,mainly reflected in the vertical direction;3)Changesin the lowerlip during smiling were not associated with gummy smile.