Dental and alveolar arch widths in normal occlusion, class II division 1 and class II division 2

The aim of this study was to compare the transverse dimensions of the dental arches and alveolar arches in the canine, premolar, and molar regions of Class II division 1 and Class II division 2 malocclusion groups with normal occlusion subjects. This study was performed using measurements on dental casts of 150 normal occlusion (mean age: 21.6 +/- 2.6 years), 106 Class II division 1 (mean age: 17.2 +/- 2.4 years), and 108 Class II division 2 (mean age: 18.5 +/- 2.9 years) malocclusion subjects. Independent-samples t-test was applied for comparisons of the groups. These findings indicate that the maxillary interpremolar width, maxillary canine, premolar and molar alveolar widths, and mandibular premolar and molar alveolar widths were significantly narrower in subjects with Class II division 1 malocclusion than in the normal occlusion sample. The maxillary interpremolar width, canine and premolar alveolar widths, and all mandibular alveolar widths were significantly narrower in the Class II division 2 group than in the normal occlusion sample. The mandibular intercanine and interpremolar widths were narrower and the maxillary intermolar width measurement was larger in the Class II division 2 subjects when compared with the Class II division 1 subjects. Maxillary molar teeth in subjects with Class II division 1 malocclusions tend to incline to the buccal to compensate the insufficient alveolar base. For that reason, rapid maxillary expansion rather than slow expansion may be considered before or during the treatment of Class II division 1 patients.     

Arch widths in adults with Class I crowded and Class III malocclusions compared with normal occlusions

OBJECTIVE: To test the hypothesis that there is no difference between adults with Class I crowded (CICR), Class III (CIII), and Class I normal (CIN) occlusions with respect to (1) arch widths, (2) width of the maxillary and mandibular arches, (3) gender dimorphism within groups, and (4) gender comparisons. MATERIALS AND METHODS: Samples of 39 CICR subjects, 40 CIII subjects, and 40 CIN subjects were studied. All subjects were white Americans with no history of orthodontic treatment. An analysis of variance and Duncan's test statistically compared the groups and genders. RESULTS: The CICR group had mean maxillary and mandibular intermolar and alveolar arch widths significantly smaller than the CIN group. The CIII group had mean maxillary intermolar and alveolar arch widths significantly smaller than the CIN group. Mean maxillary and mandibular intercanine arch widths were similar in the three groups. The CICR and CIN groups had similar mean maxillary/mandibular intermolar and alveolar differences significantly larger than the negative differences observed in the CIII group. Gender dimorphisms were identical in the CIII and CIN groups. The CICR group differed by not having a gender dimorphism in the maxillary alveolar width and having a gender dimorphism in the mandibular intercanine width. Gender comparisons between groups were similar in intercanine widths but differed in other widths. CONCLUSIONS: The hypothesis was rejected by the findings of this study.     

Arch width changes in extraction and nonextraction treatment in class I patients

The aim of this retrospective study was to examine the dental arch width changes of extraction and nonextraction treatment in Class I patients. The study was performed on pretreatment and posttreatment dental casts of 60 patients (30 extraction and 30 nonextraction). The mean ages were 14.3 +/- 2.02 years for the extraction group and 14.1 +/- 2.9 years for the nonextraction group. The maxillary and mandibular crowding was -6.7 +/- 3.1 and -6.3 +/- 2.8 mm for the extraction group and -4.5 +/- 3.6 and -2.1 +/- 3.5 mm for the nonextraction group, respectively. The intercanine and intermolar arch width measurements were measured using a digital caliper. Paired samples t-test was used to evaluate the treatment changes within each group. To compare the changes between groups, independent samples t-test was performed. At the start of treatment, the maxillary and the mandibular intercanine and intermolar widths of both groups did not differ statistically. At the end of treatment, maxillary and mandibular intercanine widths of both groups increased significantly. The mandibular intermolar width decreased significantly for the extraction group and the maxillary intermolar width increased significantly for the nonextraction group. The decrease in maxillary intermolar width for the extraction group and the increase in mandibular intermolar width for the nonextraction group were not significantly different. No differences were observed between the groups in maxillary and mandibular intercanine widths. Maxillary and mandibular intermolar width indicated a significantly larger value in the nonextraction group than that in the extraction group.     

骨性Ⅲ类错（牙合）牙弓、基骨弓宽度及协调性分析

目的 探讨骨性Ⅲ类错（牙合）患者牙弓、基骨弓宽度及二者协调性,为临床诊断和治疗提供理论依据.方法 选择骨性Ⅲ类错（牙合）患者33例为实验组,47例个别正常（牙合）为对照组,利用锥形束CT扫描颌面部,将扫描后图像导入Mimics10.01图像处理软件分别测量牙弓宽度、基骨弓宽度,并计算上下颌对应宽度之差,对测量结果进行独立样本t检验.结果 骨性Ⅲ类错（牙合）组上颌牙弓宽度与个别正常（牙合）组比较无显著性差异,但下颌牙弓宽度大于正常（牙合）,其中下颌第一磨牙处平均宽度正常（牙合）为（56.26±3.09）mm,骨型Ⅲ类患者为（57.78±3.22）mm,差异有统计学意义（P＜0.05）;骨性Ⅲ类错（（牙合）上颌基骨弓宽度测量值均小于对照组,其中在上颌第二前磨牙处正常（骀）为（59.11±5.97）mm,骨型Ⅲ类患者为（56.23±5.28）mm,有统计学差异（P＜0.05）,下颌基骨弓宽度均大于对照组,其中在前磨牙及第一磨牙处分别为（47.44±2.96）mm、（59.81±3.87）mm和（76.20±4.20）mm,与正常（牙合）相比差异显著（P＜0.05）.骨性Ⅲ类错（牙合）上下颌基骨弓宽度差值均小于正常（牙合）（P＜0.01）,而牙弓宽度差值仅在尖牙处差异显著（P＜0.05）,其余牙位测量项目无统计学差异.结论 ①骨性Ⅲ类错（牙合）组上颌基骨宽度发育不足,下颌基骨宽度发育过度.②骨性Ⅲ类错（牙合）的宽度不协调表现在基骨水平,牙弓对基骨弓宽度不调有代偿.     

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.     

Transverse dimensions of dental arches in subjects with Class II malocclusion in the early mixed dentition

Objective

The purpose of this study was to analyze the transverse dentoalveolar features of subjects with Class II Division 1 malocclusion in mixed dentition when compared to subjects with normal occlusion.

Materials and methods

The study was performed on 192 randomly selected subjects in the early mixed dentition. According to sagittal skeletal and occlusal features the sample was divided into two groups: 88 subjects (53 females and 35 males) with Class II skeletal disharmony and Class II, division 1 malocclusion (Class II Group, mean age 8 years and 10 months ± 11 months) and 104 subjects (66 females e 38 males) with dentoskeletal Class I relationships (Class I Group, mean age 9 ± 1 years). The Class II group was further divided into two subgroups (maxillary protrusion group and mandibular retrusion group) on the basis of the skeletal characteristics. Intermolar and intercanine distances were measured on dental casts in both arches and posterior and anterior transversal discrepancy (PTID and ATID) were calculated.

Results

Subjects with Class II malocclusion showed a significantly greater negative PTID (−2.1 mm) which was associated with a significantly reduced maxillary width with respect to the Class I group (−2.2 mm). The Class II group showed also a significantly greater negative ATID (−1.4 mm) when compared to the Class I group. Subjects with mandibular retrusion showed a significantly greater reduction both in the maxillary intercanine width (−1.7 mm). and in the maxillary intermolar width (−2.7 mm) with respect to the Class I group. Subjects with maxillary protrusion presented with a significantly greater constriction at the maxillary intermolar width (−1.7 mm) when compared to the Class I group.

Conclusions

Class II malocclusion with mandibular retrusion is associated with a significant constriction of the maxillary arch with reduced intercanine and intermolar widths. When Class II malocclusion is due to a maxillary protrusion the constriction at the maxillary arch is limited to the intermolar width.     

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.     

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.     

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 widths and mandibular-maxillary base width in Class III malocclusions with low, average and high MP-SN angles

OBJECTIVE: To analyze the development of the dental arches and skeletal mandibular-maxillary bases in untreated Class III malocclusions with low averages and high mandibular plane angles in subjects aged 10 to 14. MATERIALS AND METHODS: The records of 50 untreated Japanese girls with Class III malocclusions at age 10 were selected from the files of patients pending orthodontic surgery. The patients included those with low (< or =27 degrees), average (27 degrees through 37 degrees) and high (>37 degrees) mandibular plane angles. The maxillary skeletal base width, biantegonial width, and maxillary and mandibular intermolar width were determined on posteroanterior cephalograms obtained at annual intervals when subjects were between 10 and 14 years of age. The difference between the maxillary and mandibular intermolar width was also calculated and reported. RESULTS: All skeletal and dental transverse widths in the high-angle group were significantly smaller than those in the low-angle group (P < .05) from ages 10 to 14. On the other hand, the maxillary to mandibular molar difference was the same for the three groups (P > .05) at each age. The deviations in molar differences did increase from age 10 to age 14 in all three groups. CONCLUSION: Mandibular plane angles might play a stronger role in the transverse skeletal growth of the maxilla and the mandible than the transverse dental growth of the maxilla and the mandible.     

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.     

Morphological characteristics of the symphyseal region in adult skeletal Class III crossbite and openbite malocclusions

OBJECTIVE: To evaluate the relationship of the morphological characteristics of the symphyseal region of adult Class III malocclusion to the differences in overjet and overbite. MATERIALS AND METHODS: The basal and symphyseal widths along with the alveolar and symphyseal heights were evaluated using data from the lateral cephalograms of Korean adult male skeletal Class III, divided into crossbite (n = 28) and openbite (n = 41) groups. Korean male normal occlusion samples (n = 32) were used as controls. RESULTS: The width of the symphyseal region including the basal width, point B width, Id width, symphyseal thickness, and pogonion width were similar in adult Class III crossbite and normal occlusion groups, but significantly less in the adult Class III openbite group (P < .001). The alveolar height was similar in the adult Class III crossbite and control groups, but significantly less in the adult Class III openbite group (P < .05). However, the symphyseal height was similar in all three groups. CONCLUSIONS: An openbite, rather than a negative overjet, is the major factor influencing the symphyseal morphology in an adult Class III malocclusion.     

Evaluation of mandibular transverse widths in patients affected by unilateral and bilateral cleft lip and palate using cone beam computed tomography

Objective:To evaluate the mandibular dental, alveolar, and skeletal transversal widths in patients affected by unilateral (UCLP) and bilateral (BCLP) cleft lip and palate and to compare the findings with a well-matched normal occlusion sample using cone beam computed tomography images.Materials and Methods:The study sample consisted of 75 patients divided into three groups: the UCLP (29 patients; mean age: 15.40 ± 3.22 years), BCLP (18 patients; mean age: 15.54 ± 3.72 years), and normal occlusion (28 patients; mean age: 15.82 ± 2.11 years) groups. Mandibular dental (intercanine and -molar), alveolar (intercanine and -molar), and skeletal (bigonial width) transversal measurements were performed three-dimensionally and analyzed using the one-way variance analysis and post hoc Tukey tests.Results:Patients affected by UCLP and BCLP had statistically significantly lower intercanine alveolar widths (P < .05 and P < .001, respectively) and larger intermolar (P < .001 and P < .05, respectively) and intermolar alveolar widths (P < .001) compared with the normal occlusion group. Furthermore, the patients affected by UCLP and BCLP had similar mandibular dental, alveolar, and skeletal transversal widths (P > .05).Conclusion:The UCLP and BCLP groups showed statistically significantly smaller values for intercanine alveolar widths and larger values for intermolar dental and alveolar widths compared with the normal occlusion group. This shows the importance of using individualized archwires according to the pretreatment arch widths of the patients affected by UCLP and/or BCLP.     

骨性Ⅲ类错(牙合)、正常(牙合)切牙区牙槽骨形态结构的初步研究

目的：探讨骨性Ⅲ类错[牙合]和正常[牙合]切牙区牙槽骨的形态结构与垂直骨面型间的关系。方法：随机抽取47张恒牙期骨性Ⅲ类错[牙合]病例矫治前的X线头颅侧位片及43张正常[牙合]恒牙期的头颅侧位片,测量上下切牙区的牙槽骨形态结构的相应项目、指标,并对相同面角的骨性Ⅲ类错[牙合]与正常[牙合]的测量结果进行t检验。结果：对于骨性Ⅲ类错[牙合]患者,其UP值在高面角组与中等面角组、低面角组有显著性差异（P〈0．05）,LA值及MxAD值在高面角组与中等面角组的差别有统计学意义（P〈0．05）。对于正常[牙合],其MdAD值在高面角组与中等面角组、低面角组的差别有统计学意义（P〈0．05）,LA值在高面角组与中等面角组、低面角组的差别也有统计学意义（P〈0．05）。而相同面角骨性Ⅲ类错[牙合]的LA值均低于正常殆（P〈0．05）,UP值在中等面角组、低面角组与正常[牙合]的差别也有统计学意义（P〈0．05）,MdAD值也均为骨性Ⅲ类错[牙合]显著小于正常[牙合]（P〈0．01）。结论：骨性Ⅲ类错[牙合]和正常[牙合]的切牙区牙槽骨的形态结构在不同垂直骨面型之间及相同垂直骨面型间均有不同。     

Skeletal and dental contributions to posterior crossbites

The objective of this retrospective study was to compare skeletal and dental arch morphology of children with posterior crossbites with a control group of children without posterior crossbites. The study included 93 patients with a posterior crossbite (33 boys and 60 girls) and 97 patients without a posterior crossbite (50 boys and 47 girls). Skeletal and dental characteristics between the two groups were compared using measurements of dental casts, and lateral and posteroanterior cephalograms. Univariate analyses revealed that seven characteristics were significantly different between the crossbite and non-crossbite groups: mandibular plane angle, lower face height, skeletal maxillary to mandibular width ratio, maxillary intermolar width, mandibular intermolar width, maxillary to mandibular intermolar width ratio, and mandibular unit length. Using maxillary to madibular intermolar width ratio as the outcome measure, a stepwise variable selection technique, analyzed all 190 patients and found only two variables significantly associated with this measure: skeletal maxillary to mandibular width ratio and lower face height. The coefficient of multiple determination for this model was only 13%, indicating that these two variables accounted for only a small portion in the variation of the ratio between the maxillary and mandibular intermolar widths.     

骨性Ⅲ类与Ⅰ类错患者基骨及牙弓宽度的比较研究

目的：评价骨性Ⅲ类错合与骨性I类个别正常合上下颌第一磨牙区基骨及牙弓宽度差异。方法：选取骨性Ⅲ类错合患者与骨性I类个别正常合样本各30例。测量CBCT数据中上颌骨颧弓点和下颌第一磨牙阻抗中心对应的颊侧骨皮质点间的距离作为基骨宽度；测量模型上下颌第一磨牙中央窝之间的距离作为牙弓宽度。使用SPSS 22.0独立样本t检验。结果：上颌基骨宽度Ⅲ类组（63.96±3.78mm）小于I类组（65.67±2.76mm）；下颌基骨宽度Ⅲ类组（62.26±3.12mm）大于I类组（60.29±3.15mm）；基骨宽度差为Ⅲ类组（2.31±2.41mm）小于I类组（5.38±1.24mm）。差异均有统计学意义（P<0.05）。Ⅲ类组与I类组上下颌牙弓宽度均无组间差异（P>0.05）。结论：骨性Ⅲ类患者存在上下颌基骨横向发育不调及上下颌磨牙的颊舌向代偿。     

Is there a relationship between dental crowding and the size of the maxillary or mandibular apical base?

Objective:To determine whether apical base size is related to dental crowding.Materials and Methods:Digital scans of dental casts were taken of 75 untreated Class I adults to measure maxillary and mandibular tooth size, dental arch perimeters, intermolar widths, and intercanine widths. Cone beam computed tomography (CBCT) images were used to measure the apical base of the maxilla and mandible, including the total cross-sectional area, five basal arch perimeters and five basal arch widths. Principal components factor analyses were performed to evaluate the relationships between the apical base size and tooth-size-arch-length discrepancies (TSALD).Results:The dental arch and maxillary apical base measures were significantly larger in males than females. There were only limited sex differences in mandibular apical base size. The dental arch measurements were smaller in subjects with greater upper and lower TSALD. Maxillary and mandibular apical base dimensions were positively interrelated. Low-to-moderate correlations were found between the size of the maxillary apical base and TSALD. The size of the mandibular apical base was not related to upper or lower TSALD. Tooth size showed little to no relationship with TSALD.Conclusions:Although maxillary apical base size is related to maxillary and mandibular crowding in subjects with Class I malocclusion, mandibular apical base size is not.     

牙列拥挤患者与正常[牙合]人的Bohon指数分析

目的探讨牙列拥挤患者与正常[牙合]人Bohon指数的差异，为临床诊疗提供参考。方法分别选取正常[牙合]人91名和安氏Ⅰ类中重度牙列拥挤患者80名作为实验对象，年龄16～26岁，平均年龄21岁，运用昆明医学院正畸科开发的牙[牙合]模型系统测量两组Bolton指数的各项指标，将测量结果导入SPSS，将各项指标进行成组t检验。结果正常骀人与牙列拥挤患者的Bolton指数均无显著性的性别差异；牙列拥挤组的6个上前牙牙冠宽度总和、6个下前牙牙冠宽度总和、上颌12个牙牙冠宽度总和和下颌12个牙牙冠宽度总和均大于正常[牙合]组，都存在高度显著性差异，而两组的Bolton前牙比和全牙比并无显著性差异。结论本研究结果提示安氏I类牙列拥挤患者Bolton指数与正常[牙合]人无明显差异，但对牙列拥挤患者应关注牙量过大的情况。     

A cephalometric, tomographic, and dental cast evaluation of Fr?nkel therapy

The purpose of this study was to evaluate the skeletal, dental, and condylar positional changes induced by Fr?nkel FR-2 therapy. The pre- and posttreatment cephalometric, tomographic, and dental cast records of 25 consecutively treated cases were evaluated. Results showed little Class II skeletal correction with no headgear-type restraining effect on the maxilla or mandibular growth stimulation noted. Significant amounts of maxillary incisor retraction and mandibular incisor proclination were observed. The maxillary intermolar width along with the mandibular intercanine and intermolar widths were significantly increased during treatment. No significant changes in condylar position were found during Fr?nkel therapy and only a small increase in mandibular plane angle was noted.