| Objective:This study analyzed the changes of craniomaxillofacial soft and hard tissues,sagittal diameter of upper airway and hyoid bone position before and after treatment in patients with class Ⅲ malocclusion of permanent dentition treated with straight wire transmission technique,and explored the corrective mechanism and clinical effect of this technique.At the same time,the changes of maxillofacial and sagittal diameter of upper airway and hyoid bone caused by non-surgical orthodontic treatment in patients with skeletal class Ⅲ malocclusion were preliminarily discussed.The relationship between position changes can provide clinical reference for non-surgical orthodontic treatment of class Ⅲ malocclusion.Methods:In this study,11 patients with Class Ⅲ malocclusion were selected from the Department of Orthodontics,the First Affiliated Hospital of DaLian Medical University from January 2017 to January 2019.There were 4 males and 7 females,with an average age of 18.5 years.Six of the 11 patients had their mandibular third molars extracted before treatment,and five had not been extracted because the germ of the mandibular third molars was not fully developed and the extraction trauma was serious.All cases were treated strictly according to the concept and procedure of straight wire arch.Before and after treatment,X-ray imaging data and clinical records were clear and complete.All X-ray films showed clear and easily identifiable soft and hard structures of craniomaxillofacial region.All markers and measurements were strictly and accurately measured by the authors in accordance with the unified standards.SPSS17.0 software package was used to pair t-test the measured values of craniomaxillofacial soft and hard tissues,sagittal diameter of upper airway and hyoid position before and after the treatment of class Ⅲ malocclusion in permanent dentition.Pearson correlation analysis was made between the changes of hard tissues before and after treatment and the changes of soft tissues,sagittal diameter of upper airway and hyoid position respectively.P < 0.05 for the difference has statistical significance.P < 0.01 for the difference has high statistical significance.Result:1.The results showed that:(1)The sagittal direction of maxillary and mandibular bones changed significantly: the SNA angle increased by 2.28±3.07,the ANB angle increased by 1.52±1.36,the Wits value increased by 4.89±3.45,and the APDI value decreased by 3.09±4.45.The difference was statistically significant before and after treatment,indicating that the sagittal imbalance of maxillary and mandibular bones was improved after treatment.(2)Vertical upward craniomaxillofacial changes also occurred:MP-SN angle increased by 0.06±3.53,FH-MP angle increased by 0.05±2.48,on average,there was no significant difference before and after treatment.(3)Significant compensatory movement occurred in the upper and lower anterior teeth: U1-SN increased by 7.47±7.01,L1-MP angle decreased by 7.26±3.94,L1-NB(mm)value decreased by 2.82±2.06,L1-NB(°)angle decreased by 8.05±5.66,the difference was highly significant,indicating that the upper anterior teeth were further corrected by transmission straight wire arch technique.The lower anterior teeth were further adducted with inclined lips.2.The results of craniomaxillofacial soft tissue changes: before and after treatment,the craniomaxillofacial soft tissue changes significantly,LL-Sn ⊥ FH decreases by2.83±1.92 on average,indicating that the protrusion of lower lip improves;Lip-diff increases by 2.69±1.20 on average,showing that the patient’s profile changes from concave to straight;UL-B line decreases by 0.07±1.51 on average,and H angle decreases by 0.18±1.39 degrees on average.It indicated that the upper lip of soft tissue had slight adduction,but the difference was not statistically significant.3.The results of sagittal diameter change of upper airway: UPW increased by 0.54±3.01,MPW decreased by 0.61±1.93,LPW decreased by 1.69±3.36,PAS decreased by0.78±2.03,and SPP-SPPW decreased by 1.15±2.70 on average,with no statistical significance.4.The results of hyoid position change were as follows:(1)Hyoid bone moved downward vertically without statistical significance: the average increase of AH-SN value was 1.23±5.97,the average increase of AH-FH value was 0.93±4.74,the average increase of AH-PNS value was 0.85±3.98,and the average decrease of Ar-AH-Me angle was 1.14±8.04.(2)Hyoid bone moved forward in sagittal diameter with no statistical significance: the average decrease of AH-Or value was 0.03±4.32,the average decrease of AH-RGn value was 0.63±4.43,and the average increase of AH-CVP value was0.17±2.87.5.The changes of hard tissues in maxillofacial region were positively correlated with soft tissue,sagittal diameter of upper airway and hyoid position:(1)Hard tissues and soft tissues: LL-Sn_FH was positively correlated with SNB(r=0.718,p<0.05),L1-MP(r=0.748,p<0.01),which was highly correlated with L1-MP;LL-Sn_FH was negatively correlated with ANB(r=-0.654,p<0.05),and Lip-di was negatively correlated with L1-MP.-MP(r=-0.713,P < 0.05)was negatively correlated,with statistical significance.(2)Hard tissue and sagittal diameter of upper airway: MPW was positively correlated with L1-MP(r = 0.689,P < 0.05)and had statistical significance.(3)Hard tissue and hyoid position: AH-Or was negatively correlated with SNB(r=-0.606,P < 0.05),while AH-Or was positively correlated with MP-SN(r = 0.690,P < 0.05),with statistical significance.Conclusion:1.Using straight wire transmission technology to correct Class Ⅲ malocclusion,the normal overbite coverage of the anterior teeth was established after orthodontic treatment.The occlusal relationship of the posterior teeth was good,and the profile was significantly improved.The effect of orthodontic treatment with informed consent of both doctors and patients before orthodontic treatment was achieved.The patients and their families were very satisfied with the effect of orthodontic treatment.It has certain guiding significance for the clinical treatment of Class Ⅲ malocclusion.2.The treatment of Class Ⅲ malocclusion with transmission straight wire arch can improve skeletal imbalance to a certain extent,but it still relies mainly on compensatory tooth movement.It can effectively improve the soft tissue profile by coordinating the lip-chin relationship with a large amount of adduction of lower dentition.The location of lower anterior teeth lip-lingual is closely related to the soft tissue profile: LL-Sn_FH is positively correlated with L1-MP,with a high degree of statistical significance;It was negatively correlated with L1-MP and had statistical significance.3.The sagittal diameter of upper airway decreases before and after the treatment of Class Ⅲ malocclusion with transmission straight wire arch,except for nasopharyngeal cavity.The hyoid bone moves forward and downward without statistical significance.MPW is positively correlated with L1-MP,AH-Or is negatively correlated with SNB,and positively correlated with MP-SN,with statistical significance.Although there is no significant difference in the sagittal diameter of upper airway and hyoid position caused by orthodontic treatment,there is a correlation between the two,which still needs clinical attention. |
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