| Skeletal class Ⅲ malocclusion is a common maloclusion in clinic,and its incidence is high in China.The incongruity of maxillary and mandibular leads to the skeletal class Ⅲ malocclusion characteristic concave facial profile.Malocclusion endangers the oral function of patients,furthermore such facial profile causes patients to fall into deep distress,affecting their normal social,work and life,and more seriously,affecting their mental health.Compared with other types of malocclusion,skeletal class Ⅲ patients tend to have a stronger desire to seek facial improvement.Orthodontic camouflage and orthognathic surgery are usually used as a treatment.In the treatment of skeletal class Ⅲ malocclusion,there is no clear borderline between what can be achieved by orthodontic camouflage and what inevitably requires orthognathic surgery.Further exploration is needed.In recent years,the study of facial morphology has been deepening in the field of orthodontics,and facial features are of great significance for the diagnosis of malocclusion and the making treatment plans;the chin is an important element of the 1/3 lower face.Including the nose,lips and chin,the 1/3 lower face is the key part of orthodontic treatment,and the chin greatly affects a person’s profile.In this study,CBCT was used to study the soft tissue profile and chin morphology of skeletal class Ⅲ malocclusion in adult males,and to explore whether there are differences among different vertical skeletal features of skeletal class Ⅲ in adult males,so as to provide reference and diagnostic ideas for clinical diagnosis and treatment.This study includes two parts:Part I Research on soft tissue facial profile in skeletal class Ⅲ adult males of different vertical facial skeletal featuresObjective:This research compares the soft tissue profile characteristics of different vertical facial features of skeletal class Ⅲ in adult males,providing diagnostic and therapeutic ideas and reference data for the field of orthodontics and orthognathic surgery.Methods:90 untreated male adult patients with skeletal class Ⅲ underwent CBCT.Basing on the magnitude of the mandibular plane angle(MP-FH and MP-SN),they were divided into three groups: high angle group,mean angle group and low angle group.Each group consisted of 30 subjects.Some related items of six different soft tissue profile analysis were used to measure each group.The measurement indexes of each group were statistically analyzed.The discrepancy between the three groups were compared.Results:1.There was no statistical difference in the results of three groups of sagittal projection measurement items in skeletal class Ⅲ malocclusion,including ∠SNA,∠SNB,∠ANB(P>0.05)2.The linear measurement items that have statistical differences in the three groups were:Bs-H line,Pog-Sn⊥FH.They are respectively belong to Holdway analysis and Epker analysis.The measurement value of Bs-H line was the smallest in the high angle group.Compared with the mean angle group and the low angle group,the shortest distance from mentolabial sulcus(Bs)to H line was found in the high angle group;the measurement value of Pog-Sn⊥FH was the largest in the low angle group.Compared with the high angle group and the mean angle group,the chin protrusion was greater in the low angle group.3.The angle measurement items that have statistical differences in the three groups was Z angle.The measurement value of Z angle was the largest in the low angle group,which was significantly statistical different from that in the high angle group and the mean angle group,suggesting that the low angle group’s facial protrusion was greater.Conclusion:There are discrepancy features in soft tissue profile of skeletal class Ⅲ adult males with different vertical facial skeletal features.It is necessary to provide a more individual treatment plan basing on the specific facial features of the patients so as to achieve better therapeutic effect.Part Ⅱ Research on chin morphology in skeletal class Ⅲ adult males of different vertical facial skeletal features.Objective:Comparison the hard and soft tissue of chin morphology characteristics of different vertical facial features in skeletal class Ⅲ adult males,providing diagnostic and therapeutic ideas and reference data for the field of orthodontics and orthognathic surgery.Methods:90 untreated male adult patients with skeletal class Ⅲ underwent CBCT.Basing on the magnitude of the mandibular plane angle(MP-FH and MP-SN),they were divided into three groups: high angle group,mean angle group and low angle group.Each group consisted of 30 subjects.The soft and hard tissues of the chin were respectively measured in three groups.The measurement indexes of each group were statistically analyzed.The discrepancy between the three groups were compared.Results:1.The measurement items of hard tissue of chin that have statistical differences in the three groups were:chin height,chin angle,chin curvature.The difference is mainly reflected in the high angle group.Compared with the mean angle group and the low angle group,the high angle group has the longest chin height,smaller chin angle,larger chin curvature.The chin morphology in the high angle group seems slender and flat,while in the low angle group,it seems short and thick.2.The measurement items of soft tissue of chin that have statistical differences in the three groups was mentolabial sulcus.The difference is mainly reflected in the high angle group.The high angle group has the biggest mentolabial sulcus.It can be seen from the face that the mentolabial sulcus with high angle is shallow,the 1/3 lower face is longer,and the curve from the lower lip to the chin is more flat.Conclusion:The chin morphology is different,which in the skeletal class Ⅲ adult males with different vertical skeletal facial features.In clinical work,we should making a more individual treatment plan according to the specific chin morphological characteristics of patients in order to achieve better therapeutic effect. |
