Analysis The Effects Of Patients With Class â…¡ Malocclusion Teated By Forsus Combined With Straight Wire Appliance

BackgroundAngle’s class II malocclusion is clinically common malocclusion deformity, the diagnosis and treatment of which are relatively complicated, especially for patients with mandibular retrusion. Passive backward movement of the mandible leads to disharmony among joint position, tooth position and muscle position, affecting the normal functions of stomatognathic system and facial appearance[1]. Therefore, early treatment with a functional corrector can promote normal growth and development of the teeth, occlusion, jaws and face. Generally large in size, conventional functional corrector gives a foreign body sensation, thus most children are unwilling to use it. It is often applicable to two-phase orthodontic treatment lasting for a long period and can not be used in combination with a fixed corrector. Therefore, many orthodontists begin to prefer the fixed functional corrector, which can act reliably without patients’ cooperation and can be jointly used with a fixed corrector. We compared and analyzed the effects of ForsusTM spring combined with straight wire appliance for fixation, in the orthodontic treatment of the children with Angle’s class II division I malocclusion with mandibular retrusion who were at the age of development fastigium or pre-development fastigium, and discussed the clinical effects and action mechanisms of Forsus spring, so as to provide clinicians with a theoretical basis and clinical guidance. ObjectiveThis study applied functional orthodontic treatment combined with fixed orthodontic treatment to the patients with Angle’s class II division I malocclusion with mandibular retrusion who were at the age of puberty and pre-puberty. Cephalometric x-ray analysis was made to the lateral cephalometric radiographs of the patients at different stages in the treatment group and the control group, and the changes in the teeth, bone and soft tissue were compared. The mechanism and effect of Forsus spring combined with fixed orthodontic treatment were discussed to provide references for the design of clinical orthodontic treatment. Methods11 patients(6 boys and 5 girls), with a mean age of 12.45 ± 1.67 years, at stage CS2 or CS3 and having Angle’s class II division I malocclusion with mandibular retrusion, were enrolled in the treatment group. 8 patients(4 boys and 4 girls), with a mean age of 13.52 ± 1.86 years, who opted not to receive the treatment after coming to our hospital for the first time and consulting the design of orthodontic treatment protocol, and did not receive any treatment until coming for the second time to seek treatment when lateral cephalometric radiographs showed stage CS4, were included in the control group. According to the analysis of dental crowding, the lingual inclination of anterior teeth and other factors, the patients in the treatment group needed to receive the orthodontic treatment of tooth extraction and had Forsus spring installed, with the upper and lower dentition leveled and aligned and the archwire replaced by 0.019×0.025″ stainless steel rectangular archwire, where the Forsus spring was removed after being used for 6.57 ± 0.34 months on average when the relationship between the overjet and the overbite, molar relationship and the facial contour were obviously improved, and the sliding method plus class II traction was adopted for the maxilla and mandible to close extraction space and maintain the curative effect. Lateral cephalograms were taken for all patients at the beginning of orthodontic treatment(stage T1), at the time of removing Forsus spring(stage T2) and after closing extraction space(stage T3) to make cephalometric analysis of the teeth, occlusion and face in sagittal and vertical planes, and for the patients in the control group during the consultation for the first time(stage C1) and the visit for the second time(stage C2) to make comparative analysis of the changes in growth and development. An independent samples t-test was conducted to determine the matching between the treatment group at stage T1 and the control group at stage C1. A paired t–test was carried out to evaluate the variation differences among stages T1, T2 and T3 and between stages C1 and C2. SPSS17.0 was used to process and analyze the data. Results1. In the treatment group, from stage T1 to stage T2, SNB increased by 2.39°, ANB decreased by 3.04°, SN/OL increased by 2.01°, point B moved forward 3.21 mm and downward 1.91 mm, point Pg moved forward 3.49 mm, Co-Go increased by 3.07 mm, Ar-Pg increased by 3.19 mm, U1-FHp decreased by 1.32 mm, U6-CFH decreased by 1.36 mm, L1-FHp increased by 5.12 mm, L1-CFH increased by 3.34 mm, L6-FHp increased by 4.12 mm, L6-CFH decreased by 1.45 mm, U1/SN decreased by 4.31°, L1/MP increased by 4.26°, the H angle decreased by 4.12°, the nasolabial angle increased by 2.98°, the distances between the upper lip and lower lip and line E respectively decreased by 1.15 mm and 1.28 mm, the protruding point of the upper lip moved backward 1.16 mm, and the protruding point of the lower lip, the mentolabial sulcus point and the soft issue pogonion respectively moved forward 1.83 mm, 2.58 mm and 2.62 mm, on average. There was statistical significance in the differences(p<0.05). There was no obvious difference in SN/PP, SN/MP and point A between the above-mentioned two stages(p>0.05).2. From stage T2 to stage T3, U1-FHp decreased by 2.36 mm, U6-FHp increased by 2.30 mm, U6-CFH increased by 1.85 mm, L6-FHp increased by 3.32 mm, U1/SN decreased by 5.43°, L1/MP decreased by 3.40°, the distances between the upper lip and lower lip and line E respectively decreased by 1.05 mm and 0.59 mm, and the protruding point of the upper lip moved backward 1.37 mm, on average. There was statistical significance in the differences(p<0.05).3. From stage T1 to stage T3, SNB increased by 2.66°, ANB decreased by 2.89°, point B moved forward 3.37 mm and downward 2.15 mm, point Pg moved forward 3.84 mm, Co-Go increased by 3.12 mm, Ar-Pg increased by 3.42 mm, the H angle decreased by 4.82°, the nasolabial angle increased by 6.39°, the distances between the upper lip and lower lip and line E respectively decreased by 2.21 mm and 1.87 mm, the protruding point of the upper lip moved backward 2.54 mm, and the protruding point of the lower lip, the mentolabial sulcus point and the soft issue pogonion respectively moved forward 1.46 mm, 2.56 mm and 3.09 mm, on average. The differences were significant(p<0.05). There was no significant difference in the positions of SN/PP, SN/MP, SN/OL, SNA and point A between the above-mentioned two stages(p>0.05).4. Before the treatment, there was no obvious difference in the measured values of the patients between two groups, demonstrating good matching thereof. In the control group, from stage C1 to stage C3, SNB increased by 1.31°, ANB decreased by 0.84°, point B moved forward 1.23 mm and downward 1.03 mm, point Pg moved forward 1.56 mm, Co-Go increased by 1.73 mm, Ar-Pg increased by 1.63 mm, the H angle decreased by 1.83°, and the protruding point of the lower lip, the mentolabial sulcus point and the soft issue pogonion respectively moved forward 0.59 mm, 0.77 mm and 1.18 mm(p<0.05). In addition to the changes as a result of growth and development, the SNB in the treatment group increased by 1.35° more than the increment of the control group, the ANB therein decreased by 2.05° more than the decrement thereof, the Co-Go therein increased by 1.45 mm more than the increment thereof, the Ar-Pg therein increased by 1.79 mm more than the increment thereof, point B therein moved forward 2.14 mm and downward 1.12 mm more than the increments thereof, point Pg therein moved forward 2.28 mm more than the increment thereof, the H angle therein decreased by 2.99° more than the decrement thereof, the nasolabial angle therein increased by 6.14° more than the increment thereof, the distances between the upper lip and lower lip and line E therein respectively decreased by 1.88 mm and 1.28 mm more than the decrements thereof, the protruding point of the upper lip therein moved backward 2.11 mm more than the increment thereof, and the protruding point of the lower lip, the mentolabial sulcus point and the soft issue pogonion therein respectively moved forward 0.87 m, 1.79 mm and 1.91 mm more than the increments thereof(p<0.05). There was no obvious difference in SNA, SN/PP, SN/MP, SN/OL and point A between the two groups(p>0.05).5. After orthodontic treatment, the overbite of anterior teeth reduced by 8.06 mm, with 40% from osteal change and 60% from tooth change; the molar relationship showed a variation of 8.12 mm, with 39% from osteal change and 61% from tooth change. Conclusions1. For Angle’s class II division I malocclusion, the functional corrector combined with straight wire appliance enables the fixed orthodontic treatment to be given simultaneously with functional orthodontic treatment, stimulates the growth of the mandible, promotes forward movement of the mandible and better improves skeletal craniofacial pattern.2. For patients with class II division I malocclusion with mandibular retrusion accompanied by dental crowding, Forsus spring can better shape the teeth and jaws, more obviously improve facial contour and shows more advantages in tooth movement and anchorage control combined with straight wire appliance for fixation.3. The functional corrector combined with straight wire appliance can reduce the difficulty in the orthodontic treatment of Angle’s class II division I malocclusion with mandibular retrusion, shorten the time of treatment and improve treatment efficiency.