Dental and alveolar arch widths in normal occlusion and Class III malocclusion

The aim of this study was to compare the transverse dimensions of the dental arches and alveolar widths of Class III malocclusion group with a group of untreated normal occlusion subjects. This study was performed using measurements on dental casts of 150 normal occlusion (mean age, 21.6 +/- 2.6 years) and 100 Class III malocclusion (mean age, 15.4 +/- 2.2 years) subjects. Independent samples t-test was applied for comparing the groups. The findings of this study indicated that the mandibular intercanine and intermolar alveolar widths were significantly larger in the Class Ill group when compared with the normal occlusion sample (P < .001). Maxillary interpremolar, intermolar widths and all maxillary alveolar width measurements were significantly narrower in the Class III group (P < .001). In addition, the lower canine and premolar alveolar width measurements were also statistically significantly larger in the normal occlusion group when compared with the Class III malocclusion group (P < .001). Subjects with Class III malocclusion tend to have the maxillary teeth inclined to the lingual and mandibular teeth inclined to the buccal direction because of the restriction of maxillary growth and development according to dental arch width measurements. Therefore, rapid maxillary expansion should be considered before or during the treatment of a Class III patient with or without face-mask therapy.     

A comparison of arch widths in adults with normal occlusion and adults with class II, Division 1 malocclusion

This study compares arch widths and other cast and cephalometric measurements of 36 normal-occlusion subjects (19 males, 17 females) with 39 Class II, Division 1 subjects (20 males, 19 females). None of the subjects had received orthodontic treatment. Analysis of variance demonstrated that subjects with normal occlusion had larger maxillary molar widths, maxillary canine widths, and maxillary alveolar widths than subjects with malocclusion; only male subjects with normal occlusion had larger mandibular molar widths and mandibular alveolar widths than the malocclusion subjects; the normal occlusion and malocclusion groups had similar mandibular canine widths; and when the lower molar and alveolar widths were subtracted from corresponding upper widths, the remainders of the Class II group were negative instead of positive, contrary to the normal group. This revealed a posterior crossbite tendency in the Class II group.     

Comparison of dental arch and alveolar widths of patients with Class II, division 1 malocclusion and subjects with Class I ideal occlusion

This study evaluates dental arch and alveolar widths of patients with Class II, division 1 malocclusion. Thirty female patients with Class II, division 1 malocclusion were compared with 30 female subjects with Class I ideal occlusion. Patients with posterior crossbites even in a single tooth were excluded from the study. According to our results, arch widths measured between maxillary second premolars and maxillary first molars were found narrower in the Class II, division 1 group, and mandibular intercanine widths were narrower in the Class I group. Interalveolar widths showed no difference between the groups. These results suggested that transverse discrepancy in Class II, division 1 patients originated from upper posterior teeth and not from the maxillary alveolar base. Therefore, slow maxillary expansion rather than rapid maxillary expansion may be considered before or during the treatment of Class II, division 1 patients.     

Arch widths in class II-2 adults compared to adults with class II-1 and normal occlusion

OBJECTIVE: To compare (1) arch widths in adults with Class II division 2 (II-2), Class II division 1 (II-1), and Class I normal occlusions, (2) genders, (3) gender dimorphism, (4) differences between maxillary and mandibular arch widths, and to (5) develop adult norms for arch widths. MATERIALS AND METHODS: Subjects were white Americans with no history of orthodontic treatment. Arch width dimensions measured were: intercanine, intermolar, and molar alveolar in both arches. Analysis of variance (ANOVA) and Duncan's test were used to compare groups. RESULTS: Comparison of pooled genders showed the II-2 group had maxillary arch widths significantly smaller than the normal occlusions and significantly larger than the II-1 group. All groups had similar mandibular intercanine and alveolar widths. The II-2 and II-1 groups had similar mandibular intermolar widths, both significantly smaller than normal occlusions. The II-2 group had a maxillary/mandibular intermolar difference significantly smaller than the normal occlusions, and significantly less negative than the II-1 group. Gender comparisons in two of six widths showed normal and II-2 male subjects were similar, and in six of six widths normal and II-2 female subjects were similar; in five of six widths II-2 and II-1 male and female subjects were similar. Gender dimorphism occurred in five of six widths in normal occlusions, four of six widths in II-2, and one of six widths in II-1. CONCLUSIONS: Arch width dimensions of II-2 subjects were intermediate between normal and II-1 occlusions. In both Class II malocclusions, the process that narrows arch widths was more pronounced in male than in female subjects.     

Dental arch dimensions in Class II division 1 malocclusions with mandibular deficiency

OBJECTIVE: To test the hypothesis that there is no difference in the dimensions of the upper and lower dental arches in Class II division 1 malocclusion with a mandibular deficiency compared to normal Class I occlusion dental arches. MATERIALS AND METHODS: Photocopies of the dental arches of 48 patients exhibiting Class II division 1 malocclusion with mandibular deficiency and of 51 individuals with normal occlusion were compared. Mandibular deficiency was diagnosed clinically. All 99 individuals were in the permanent dentition. The ages of the subjects ranged from 11 years 4 months to 20 years (mean age = 12 years 5 months). RESULTS: When compared to subjects with normal occlusion, the upper dental arches of the Class II division 1 patients presented reduced transverse dimensions and longer sagittal dimensions while the lower arches were less influenced. CONCLUSION: The hypothesis is rejected. Significant differences are present between the dimensions of the upper and lower dental arches in Class II division 1 malocclusion (with a mandibular deficiency and in the permanent dentition) compared to normal Class I occlusion dental arches.     

Dental arch widths and mandibular-maxillary base widths in Class II malocclusions between early mixed and permanent dentitions

The aim of the study was to analyze the transverse morphology and development of the dental arches and skeletal mandibular-maxillary bases in untreated Class II malocclusions. Using the records of the Belfast Growth Study, a Class II division 1 group (II/1) and a Class II division 2 group (II/2) were compared with a Class I group and a control group with good occlusion. On posteroanterior cephalograms, maxillary skeletal base width and bigonial and biantegonial widths were determined at two-year intervals between seven and 15 years. Maxillary and mandibular intermolar widths were measured on the associated study casts. As a result, maxillary skeletal base widths were smallest in the Class II/1 subjects. No statistically significant differences were found among the groups for the skeletal mandibular widths. With respect to the development of the dental arches, maxillary intermolar widths were smaller in the Class II/1 group than in the Class I and the good-occlusion groups. These group differences were present for the total period of observation, ie, seven to 15 years, and statistically significant at most ages. When the relative difference between the maxillary and the mandibular intermolar widths was examined, the Class II/1 cases were found to have the largest average difference (about -2.5 mm for boys and -1.5 mm for girls), indicating a relatively narrow maxillary arch. Less pronounced molar differences were found in the Class II/2 group. In the Class II/1 subjects the deviations in molar differences observed at 15 years of age were established already at 7 years of age and maintained during 7 and 15 years of age.     

Comparison of arch width,alveolar width and buccolingual inclination of teeth between Class II division 1 malocclusion and Class I occlusion

Objective:To compare the arch width, alveolar width, and buccolingual inclination of maxillary and mandibular posterior teeth between Class II division 1 malocclusion and Class I occlusion.Materials and Methods:Forty-five subjects with Class I occlusion and 45 subjects with Class II division 1 malocclusion were selected to measure the maxillary and mandibular arch width and alveolar width of premolars and first molars with digital caliper. Buccolingual inclination of maxillary and mandibular premolars and first molars were measured with a modified universal bevel protractor.Results:All of the posterior teeth in both groups were lingually tilted. The maxillary premolars and first molars were significantly more lingually tilted (P < .05) in Class II division 1 malocclusion than in Class I occlusion. Mandibular first premolars were significantly less lingually tilted in Class II division 1 malocclusion than in Class I occlusion. No significant difference of buccolingual inclination was found in mandibular second premolars and first molars between the two groups. No significant difference in maxillary and mandibular arch width and alveolar width was found between the two groups.Conclusions:Buccolingual inclination rather than arch width and alveolar width plays an important role in transverse discrepancy of Class II division 1 malocclusion.     

Angle Ⅱ1与正常(牙合)牙弓形态差异 --应用欧几里德距离矩阵分析法

目的：分析比较AngleⅡ^1和正常[牙合]牙弓形态差异。方法：以年龄均为13～17岁的Angle Ⅱ^1和正常[牙合]各60名为研究对象，利用YM-2115三维测量仪在所有个体的上下颌模型上标定对应于牙尖及切缘中点的标志点，用欧几里德距离矩阵分析法（Euclidean-distance matrix analysis，EDMA）分析Angle Ⅱ^1和正常[牙合]的牙弓形态差异。结果：（1）无论男女性，Angle Ⅱ^1的上牙弓长度大于正常[牙合]的上牙弓，女性大1．8％，男性大2．7％；二者的牙弓形态差异有显著性（P〈0．001），且后牙对形态差异所起的作用较前牙大，其中AngleⅡ^1的后上牙弓宽度较正常殆窄是一主要因素。（2）无论男女性，AngleⅡ^1的下牙弓长度稍大于正常[牙合]的下牙弓，二者的牙弓形态差异无显著性。结论：临床上扩展AngleⅡ^的后上牙弓宽度可能是协调上下牙弓形态的重要措施之一。     

严重深覆(牙合)型AngleⅡ2错(牙合)牙弓宽度的测量分析

目的 :分析严重深覆牙合型AngleⅡ2 错牙合的牙弓形态特点。方法 :严重深覆牙合型AngleⅡ2 错牙合 3 2副模型为实验组 ,对照组 64副模型中AngleI错 牙合和AngleⅡ1错牙合各 3 2副模型 ,分别测量上颌尖牙之间距离、上颌第一磨牙之间距离、下颌尖牙之间距离和下颌第一磨牙之间距离。结果 :采用两样本t检验 ,四项指标中只有实验组的下颌前段牙弓宽度明显窄于对照组 (P <0 .0 0 1)。结论 :除了下颌前部牙弓宽度变窄外 ,严重深覆牙合型AngleⅡ2 错牙合牙弓形态基本正常。     

江苏地区正常的牙弓形态

目的:通过对125名江苏地区正常人群的模型测量,建立江苏地区正常牙弓宽度及长度的平均值,并分析牙弓形态特征,为正畸临床的诊断和治疗提供依据。方法:选取正常模型125副(男61副,女64副),用扫描仪输入电脑,运用Winceph 8.0软件测量牙弓宽度及长度,对测量结果进行统计分析。结果:确立了以Currier外侧曲线为参考点的正常各段牙弓宽度及长度的平均值,结果表明江苏地区正常人群中,男性牙弓宽度及长度均大于女性。构建了江苏地区正常的牙弓形态,并建立了牙弓形态的β函数。结论:牙弓形态存在种族、地区和性别的差异,临床上应参照本民族、本地区的标准。β函数有助于指导临床错的诊断和治疗。     

A cephalometric comparison between Angle Class II, division 2 malocclusion and normal occlusion in adults

The lateral cephalometric radiographs of 56 adults with Angle Class II/2 malocclusion and of 81 persons with normal Class I occlusion are compared. The statistical analysis includes the calculation of the mean value, standard deviation and the determination of differences (Wilcoxon rank-test). Group characteristics are tested by stepwise discriminant analysis. The following statements regarding Angle Class II/2 as compared with normal Class I result from this study. The upper incisors are in a retruded position. The B-point is significantly retropositioned, whereas the pogonion is in a more normal position. The length of the mandibular corpus and the total length of the mandible are slightly diminished only. Normal values result for the size and position of the maxilla, the inclination of the mandibular corpus (angle between mandibular plane and NSe) and the gonion angle.     

Oral rehabilitation of adult class II, division 1 malocclusion complicated by collapse of posterior occlusion

The complications and limitations in rehabilitating an adult woman with class II, division 1 malocclusion and posterior occlusal collapse is described with special consideration given to the aspects of time, the patient's personality and socio-economic situation. Fixed restorations were chosen for optimum function, comfort and to enhance the patient's emotional security. The importance of an individual treatment approach is stressed.     

不同面部生长型正常及安氏Ⅱ类1分类错的前牙倾斜度及牙代偿特征

目的比较不同面部生长型正常的前牙倾斜度,以及安氏Ⅱ类1分类错的前牙代偿特征,为临床治疗提供参考。方法在X线头颅定位侧位片上对158例正常及246例安氏Ⅱ类1分类错的前牙倾斜度相关的测量指标进行分析,并研究其代偿特征。结果1）正常垂直生长型中上下颌前牙相对舌倾,水平生长型中上下颌前牙相对唇倾。2）与正常不同生长型均值比较,安氏Ⅱ类1分类错上颌前牙在不同生长型中相对于正常均唇倾,下颌前牙在垂直生长型和平均生长型中相对于正常唇倾,在水平生长型中没有变化。结论在临床矫治安氏Ⅱ类1分类错患者时,应根据患者的生长型及牙代偿特征,选择相应的矫治方法和控制重点。     

Nonextraction treatment of severe class II, division 2 malocclusions: Part 1

Nonextraction treatment of severe Class II, Division 2 malocclusions is presented. Timing, sequencing of appliance therapy, and segmental arch treatment are discussed. The effects of orthodontic treatment, pubertal growth, and postpubertal growth are illustrated with different growth responses. Corrections of the handicapping malocclusions were achieved by the development of arch circumference, torque, intrusion of incisors, and vertical buccal dentoalveolar development. Various subtypes of Class II, Division 2 malocclusion are presented. Pretreatment and posttreatment records are evaluated.