| BackgroundThe Mandibular retraction with temporomandibular arthrosis was a complex type of malocclusion,which was more common in clinic.The clinical manifestations of this malocclusion was poor side appearance,temporomandibular disorder,and airway dysfunction.With the in-depth discussion of the correlation between the craniofacial structure and the shape and position of the mandible,the possible etiological mechanism was the retraction of the mandible due to occlusion disorders and perioral muscles dysfunction,which in turn caused the condyle to move backward and the airway structural stenosis.Many scholars agreed that for malocclusion patients with temporomandibular arthrosis,it was necessary to clarify and re-establish the condyle position before orthodontic treatment.It was a reversible and conservative clinical treatment method to treat temporomandibular arthrosis with various splints.Among them,the anterior repositioning splint(ARS)had an anatomical shape,which could induce the mandible to slide to a specific position and adjust the neuromuscular.Therefore,for temporomandibular arthrosis caused by the abnormal position of the mandible,it could achieve multi-dimensional improvement of facial shape,joints and airways.ObjectiveTo investigate the effect of ARS on the condylar position,facial profile and upper airway in patients with mandibular retraction and temporomandibular arthrosis,so as to provide guidance for clinical application of ARS.MethodsIn the study,19 mandibular retraction patients with temporomandibular arthrosis were selected as the observation group.In addition,19 skeletal class I patients without temporomandibular arthrosis in the case bank were selected as control group.For patients in the observation group,the mandibular position was repositioned by manual reduction,and the mandibular position was re-established and stabilized by wearing ARS for 6-8 months.Before and after treatment,all the patients in the observation group were recorded symptoms of temporomandibular disorders,scanned by CBCT system and traced by cephalometric radiograph.At the same time,the lateral cephalometric radiograph images of the patients in the control group were collected and measured.The data was compared and analyzed by SPSS 24 software.Results1 Clinical efficacyAfter the ARS treatment,the cure rates of temporomandibular joint pain,clicking,and limited mouth opening were 66.7%,78.9%,100%,respectively.2 The results of CBCT system are as follow.(1)bilateral joint space.Before and after treatment,the bilateral anterior space reduced(0.83±0.64)mm,the upper space?the posterior space increased(1.76±0.87)mm,(2.59±0.88)mm,respectively.The changes had statistically difference(P<0.01).(2)left and right joint spaceLeft side:Before and after treatment,the anterior space reduced(0.78 ± 0.62)mm,the upper space?the posterior space increased(1.75±0.90)mm,(2.41±0.45)mm,respectively.The changes had statistically difference(P<0.01).Right side:Before and after treatment,the anterior space reduced(0.87±0.64)mm,the upper space?the posterior space increased(1.79±0.88)mm,(2.78± 1.14)mm,respectively.The changes had statistically difference(P<0.01).(3)condylar positionAll patients in the observation group had posterior condylar displacement(100%)before treatment.The median rate of condylar was 15.8%,and the anterior rate of condylar was 84.2%after treatment.3 The results of cephalometric system are as follow.(1)hard tissueBefore and after treatment,SNB increased(1.57±0.68)°,and ANB reduced(1.71±0.72)°;ANS-Me and S-Go increased by(3.05±2.86)mm and(1.91±2.10)mm,respectively.The changes had statistically difference(P<0.05).Compared with the control group before treatment,there were statistically significant differences in the related indexes of the positional relationship between the upper and lower jaws(SNB,ANB,ANS-Me,S-Go).Compared to the control group after treatment,the relationship between the upper and lower jaw was significantly improved,but there was statistically significant difference in SNB and ANB.(2)soft tissueBefore and after treatment,there were statistically significant differences in related indexes of soft tissue sagittal lateral profile(NsSnPg),upper and lower lip and chin relationship(LiSiPg,LsNsPg,LsNsLi).As for related indexes of soft tissue vertical direction,Sn-Mes.increased(3.281±1.58)mm,there were also statistically significant differences.Compared with the control group before treatment,there were statistically significant differences in the related indexes of soft tissue lateral profile and nose,chin and lip relationship(NsSnPg,LiSiPg,LsNsPg,LiNsPg,LsNsLi,Sn-Mes).Compared with the control group after treatment,the face type lateral profile was significantly improved,but there was statistically significant difference in the related indexes of sagittal chin.(3)sagittal diameter of upper airwayIn the upper airway:Before and after treatment,SPP-SPPW?U-MPW and TB-TPPW increased(0.71 ± 0.65)mm?(0.94 ± 1.19)mm?(1.30 ± 1.57)mm,respectively.The changes had statistically difference(P<0.05).In hyoid position:Before and after treatment,H-C3 increased(1.70±2.20)mm,H-FH reduced(1.41 ± 2.76)mm.The changes had statistically difference(P<0.05).ConclusionsFor patients with mandibular retraction and temporomandibular arthrosis,the disc process relationship could be coordinated and the symptoms of TMD could be alleviated obviously after anterior repositioning splint.The anterior repositioning splint could effectively improve the imbalance of sagittal and vertical relationship of soft and hard tissues in mandibular retraction patients with TMD,and coordinate the relationship between nose,lips and chin.After anterior repositioning splint,the sagittal diameter of the airways of the palate and glossopharyngeal segments of patients with mandibular retraction increased significantly,and the hyoid bone shifted forward and upward.After anterior repositioning splint,a good maxillofacial structure was established,which was beneficial to the health of the oral and maxillofacial system,and lied a good foundation for the next orthodontic treatment. |
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