Study on the morphology of the mandibular basal bone and dental arch of skeletal Class Ⅱ malocclusion
10.13591/j.cnki.kqyx.2025.06.007
- VernacularTitle:骨性Ⅱ类错(牙合)下颌基骨与牙弓形态的研究
- Author:
Yu BAI
1
;
Meng GAO
;
Dongmei LIU
;
Tao WANG
;
Xue FENG
Author Information
1. 陕西省人民医院口腔科,陕西西安(710068)
- Publication Type:Journal Article
- Keywords:
skeletal Class Ⅱ malocclusions;
dental and basal bone arch form;
WALA ridge;
curve fitting
- From:
STOMATOLOGY
2025;45(6):436-439
- CountryChina
- Language:Chinese
-
Abstract:
Objective To study the relationship between the mandibular bone arch and the dental arch in patients with skeletal Class Ⅱ malocclusion and compare it with the Class Imalocclusion by establishing a 3D digital model.Methods A total of 25 cases with skeletal Class Ⅱ malocclusion and 25 cases with skeletal Class Ⅰ normal occlusion were selected.The mandibular model was scanned and a three-dimensional digital model was set up.After the determination of the WALA ridge and the FA point,the reference plane and coordinate system was established.Four degree polynomial curve fitting was performed with WALA ridge and FA point coordinates to re-present the corresponding basal and dental arch curves.The width difference between the basal arch curve and the dental arch curve was measured and calculated at 3 mm,10 mm,and 18 mm away from the horizontal axis of the coordinate.The differences of basal bone and dental arch width between skeletal Class Ⅱ and skeletal Class Ⅰ malocclusion was compared.Results The width differences be-tween the arch and the dental arch in the anterior,middle and posterior mandibular segments of skeletal Class Ⅱ patients were-1.58 mm,1.80 mm and 3.80 mm,respectively.The width differences between the arch and the dental arch in the anterior,middle and pos-terior mandibular segments of skeletal Class Ⅰ patients were 2.08 mm,2.92 mm and 4.24 mm,respectively.There was a significant difference between skeletal Class Ⅱ and skeletal Class Ⅰ in the anterior and middle segments(P＜0.05),but no significant difference in the posterior segment(P＞0.05).Conclusion In skeletal Class Ⅰ patients,the width of the basal bone is larger than that of the dental arch,and the dental arch was located medial to the basal bone.In skeletal Class Ⅱ patients,the width of the anterior arch is larger than the width of the basal bone,that is,the dental arch is located outside the basal bone.The width difference of the basal arch in skeletal Class Ⅱ is smaller than that in skeletal Class Ⅰ.
