AngleⅡ类错(牙合)畸形患者牙弓宽度的测量分析

目的：比较分析AngleⅡ类错[牙合]畸形患者牙弓宽度及其牙弓形态特点。方法：选择AngleⅡ^1类错[牙合]畸形患者（平均年龄15．6岁）、AngleⅡ^2类错[牙合]畸形患者（平均年龄15．8岁）和对照组AngleⅠ类轻度错[牙合]畸形患者（平均年龄16．2岁）的原始模型各40副,测量每副模型的上下尖牙、第一前磨牙、第二前磨牙、第一磨牙之间的距离,计算上、下颌对应牙弓宽度差;对各组各项牙弓宽度和牙弓宽度差进行t检验。结果：AngleⅡ^1类错[牙合]畸形患者上颌牙弓宽度较AngleⅠ类轻度错[牙合]畸形患者狭窄,但差异无显著性（Jp〉0．05）,AngleⅡ^1类错[牙合]畸形患者下颌牙弓宽度与AngleⅠ类轻度错[牙合]畸形患者无显著差异（P〉0．05）;AngleⅡ^2类错[牙合]畸形患者上颌中、后牙弓宽度和下颌牙弓宽度较AngleⅠ类轻度错[牙合]畸形患者的牙弓宽度窄,差异有显著性（P〈0．05）;AngleⅡ^1类错[牙合]畸形患者下颌牙弓宽度比AngleⅡ^2类错[牙合]畸形患者下颌牙弓宽大,差异有显著性（P〈0．05）;AngleⅡ^1类错[牙合]畸形患者上下颌宽度差小于AngleⅠ类轻度错[牙合]畸形患者,尖牙、第二前磨牙处差异有显著性（P〈0．05）;AngleⅡ^2类错[牙合]畸形患者上下颌牙弓宽度差与AngleⅠ类轻度错[牙合]畸形患者无显著差异（P〉0．05）;AngleⅡ^1类错[牙合]畸形患者上下颌牙宽度差比AngleⅡ^2类错[牙合]畸形患者小,尖牙处宽度差差异有显著性（P〈0．05）。结论：AngleⅡ^1、AngleⅡ^2错[牙合]畸形患者上颌牙弓以及AngleⅡ^2错[牙合]畸形患者下颌牙弓宽度发育均有不足．治疗中可适当进行扩弓。     

Asymmetric dental arch treatment with Forsus fatigue appliances: Long-term results

Objectives:To investigate the treatment efficacy and follow-up stability of the asymmetric Forsus appliance by evaluating longitudinal changes in dental arch asymmetry on digital dental models from 21 patients.Materials and Methods:Maxillary and mandibular reference lines were used for measurements of intra-arch asymmetry at pretreatment (T1), posttreatment (T2), and 4.2 years after treatment (T3). Maxillary and mandibular measurements were performed relative to the dental midline and anterior reference line on digital dental models. To determine the amount of asymmetry between the Class I and Class II sides of a given arch, all maxillary and mandibular parameters were measured on each side of the model separately. Repeated-measures analysis of variance/paired sample t-tests were performed to evaluate dental arch asymmetries at the P < .05 level.Results:The alveolar transverse dimensions of the posterior segment of both arches were increased during treatment (P < .05) and remained stable during the retention period. Class II subdivision malocclusion was caused by distal positioning of the mandibular canine, premolars, and first molar on the Class II side (P < .05). Asymmetry was resolved by treatment with asymmetric Forsus appliances. The resolved asymmetry remained stable over the long term. There were no significant differences between T2 and T3 (P > .05).Conclusions:The asymmetric Forsus appliance can be used to treat dental arch asymmetry in patients with Class II subdivision malocclusions.     

Changes in dental and basal archforms with preformed and customized archwires during orthodontic treatment

ObjectivesTo evaluate changes to the dental and dentoalveolar (WALA Ridge) arch widths with preformed and customized archwires during orthodontic treatment.Methods20 patients treated with preformed archwires and 20 treated with customized archwires were recruited. Pre-treatment (T1) and post-treatment (T2) mandibular casts were used to determine the changes in dental and dentoalveolar arch width measured at the canine, premolar and molar areas. Ratios of transverse dental to dentoalveolar movements were also calculated. Results were compared to an untreated control group with mandibular casts taken at two comparable time points. Data were analyzed using ANOVA and t-test.ResultsSignificant changes in dental and dentoalveolar arch width were found with the preformed archwire group when compared to the control (p < 0.05). However, no significant changes in dental and dentoalveolar arch width were found with the customized archwire group compared to the control. Significant correlations were found between the dental and dentoalveolar arch widths. However, the ratios of dental to dentoalveolar transverse change differed between the groups and indicated that the types of movements were contrasting between the preformed and custom arch forms as each expanded the dental arches.ConclusionsThe WALA Ridge is a stable landmark when archwires are customized or shaped to the WALA Ridge. Changes in the WALA Ridge are expected when preformed archwires are used which do not conform to the patient's dentoalveolar arch width defined by the WALA Ridge. This is probably accounted for by the different types of tipping combined with extrusion that both methods employ.     

Three-dimensional analysis of molar compensation in patients with facial asymmetry and mandibular prognathism

Objective:To evaluate the characteristic transverse dental compensations in patients with facial asymmetry and mandibular prognathism and to compare features of dental compensations between two types of mandibular asymmetry using 3-dimensional (3D) cone-beam computed tomography (CBCT).Materials and Methods:Seventy-eight adult patients with skeletal Class I (control group; n  =  33; 19 men and 14 women) or skeletal Class III with facial asymmetry (experimental group; n  =  45; 23 men and 22 women) were included. The experimental group was subdivided into two groups according to the type of mandibular asymmetry: translation type (T-type; n  =  20) and roll type (R-type; n  =  19). CBCT images were acquired before orthodontic treatment and 3D analyses were performed.Results:The transverse dental distance was significantly different between the two groups only at the palatal root apex of the maxillary first molar (P < .05). In the experimental group, the first molar axes were compensated significantly on both arches except the maxillary nondeviated side. The vertical molar heights were different between the two groups only on the maxillary arch (P < .001). The R-type showed greater mandibular ramal length difference and menton deviation than the T-type (P < .001). In the R-type, transverse compensation of the maxillary first molars was more obvious than with the T-type, which resulted in canting in the maxillary occlusal plane.Conclusions:Mandibular asymmetry with prognathism showed a characteristic transverse dental compensation pattern. The mandibular asymmetry type influenced the amount and direction of molar compensation on the maxillary arch.     

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.     

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.     

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.     

Effectiveness of twin-block and Mandibular Protraction Appliance-IV in the improvement of pharyngeal airway passage dimensions in Class II malocclusion subjects with a retrognathic mandible

Objective:To test the hypothesis that twin-block and Mandibular Protraction Appliance-IV (MPA-IV) are not effective in improving the pharyngeal airway passage (PAP) dimensions among Class II malocclusion subjects with a retrognathic mandible.Materials and Methods:Eighty-three subjects ranging in age from 8 to 14 years were divided into four groups. Group I included 30 Class I malocclusion subjects (healthy controls); group II consisted of 16 Class II malocclusion subjects (Class II controls); group III had 16 subjects in whom Class II malocclusion was treated by MPA-IV; and the remaining 21 subjects formed group IV, whose Class II malocclusions were corrected by twin-block appliance. Lateral cephalograms recorded at the beginning of orthodontic treatment in group I subjects and at the beginning and end of follow-up/treatment with functional appliance in group II, III, and IV subjects were analyzed to determine the PAP dimensions. Paired t-test, one-way analysis of variance, and Tukey tests were applied for statistical analysis, and a P-value .05 was considered statistically significant.Results:Soft palate length was decreased significantly in group III (P < .05) and group IV (P < .001) subjects. Soft palate thickness in group IV subjects was increased significantly as compared to group II (P < .05) and group III (P < .01) subjects. The improvement in soft palate inclination in group III and group IV subjects was significant (P < .01). The oropharynx depth was increased significantly in group III (P < .05) and group IV (P < .001) subjects. The depth of the hypopharynx was increased significantly (P < .01) in group IV subjects.Conclusions:The twin-block appliance was more efficient than the MPA-IV in the improvement of PAP dimensions among Class II malocclusion subjects with retrognathic mandible.     

Arch width development in Class II patients treated with the Fr?nkel appliance

This article compares the arch development in growing Class II patients after Fr?nkel therapy with arch development in a similar group of untreated Class II subjects. Sixty treated and forty-seven untreated persons were compared for a 2- to 4-year period. Expansion of the maxillary and mandibular dental arches occurred to a much greater extent in patients undergoing Fr?nkel treatment than in the control subjects. The expansion was not limited to a particular region of the dental arch in the treated cases, although the largest expansion values were recorded in the premolar and molar regions. Lesser values were recorded in the canine region.     

Dental arch dimensions in the mixed dentition: a study of Brazilian children from 9 to 12 years of age

Objective

This study evaluated dental arch dimensional changes of Brazilian children.

Material and methods

Dental casts were taken from 66 children (29 males; 37 females) with normal occlusion selected among 1,687 students from public and private schools aged 9, 10, 11 and 12 years, according to the following criteria: Class I canine and molar relationships; well-aligned upper and lower dental arches; mixed dentition; good facial symmetry; no previous orthodontic treatment. Dental arch dimensions were taken by one examiner using the Korkhaus’ compass and a digital pachymeter. ANOVA test was applied to compare the arch dimensions at the different ages and the t-test was used to compare the arch dimensions of male and female subjects. Arch forms were compared by means of chi-square tests.

Results

Only the maxillary anterior segment length showed a statistically significant increase from 10 to 12 years of age. Males had a significantly larger maxillary depth than females at the age range evaluated. The predominant dental arch form found was elliptical.

Conclusion

In the studied age range, anterior maxillary length increased from 10 to 12 years of age, males had larger maxillary depth than females and the predominant arch form was elliptical.     

Effects of fixed functional therapy on tongue and hyoid positions and posterior airway

Objective:To evaluate how therapy with a fixed functional appliance affects airway dimensions, dentoalveolar changes, and tongue and hyoid positions.Materials and Methods:A retrospective study was carried out on 46 pre- and posttreatment lateral cephalometric radiographs of 23 post-peak Class II patients (12 girls, 11 boys) treated with a Forsus Fatigue Resistant Device (FRD) appliance. The radiographies were taken at the start and at the end of Forsus FRD appliance therapy when a Class I or overcorrected Class I canine and molar relationship was achieved. The process took an average of 5 months 13 days ± 1 month 4 days. Skeletal and dental parameters were measured using Dolphin software, and the sagittal airway area was measured by AutoCAD software.Results:Analyses of the pre- and posttreatment means revealed that there was no statistically significant skeletal correction of the sagittal malocclusion; increase of lower incisor inclination, decrease of upper incisor inclination, decrease of interincisal angle, and rotation of occlusal plane all contributed to the reduction of overjet. The tongue area and intermaxillary space area increased in response to these dentoalveolar changes; however, there was no statistically significant change in the hyoid position or the oropharyngeal area between the two time points.Conclusions:The dentoalveolar changes produced by Forsus FRD appliance did not cause any significant posterior airway changes in young adult patients.     

Cervical vertebra morphology in different skeletal classes: A Three-Dimensional Computed Tomography Evaluation

Objective:To describe cervical vertebra morphology in subjects with different anteroposterior jaw relationships.Materials and Methods:Cone-beam computed tomography images of 31 female subjects aged 19 to 41 years were evaluated. Subjects constituted two groups according to the ANB angle: group 1, skeletal Class II (ANB angle >5); and group 2, skeletal Class III (ANB angle <1). Nine linear measurements and one angular measurement were used to assess the vertebral morphology. The Mann-Whitney U-test was used for statistical analysis.Results:The mean atlas dorsal arch height was significantly shorter in Class II subjects compared with those in Class III (P < .05). The cervical vertebra morphological analysis by cone-beam computed tomography was of comparable precision to three-dimensional computed tomography evaluations. This study confirmed previous findings that Class II subjects have significantly lower atlas dorsal arch heights.Conclusion:The height of the atlas dorsal arch of cervical vertebrae is affected by the anteroposterior skeletal pattern.     

Occlusion and tooth/arch dimensions in the primary dentition of preschool Jordanian children

Summary. Objectives. To assess tooth and arch dimensions, occlusal relationships and the presence of spacing or crowding in primary dentition of Jordanian children. Study design. A list of 10 kindergartens was randomly selected in the governate of Irbid, Jordan. A total of 1048 children (2·5–6 years old) with complete primary dentitions were examined for occlusal relationships in three planes, and the presence of spacing or crowding. Of those, study casts were taken for 87 randomly selected 4–5‐year‐old children (39 girls, 48 boys). Measurements of tooth and arch dimensions were made using electronic digital sliding callipers. Results. In general, males had larger mesiodistal tooth width and larger arch dimensions. Bilateral mesial step molar relationship was found in 47·7% of children followed by bilateral flush terminal molar relationship in 37% and bilateral distal step in 3·7%. Asymmetric right/left molar relationship was found in 11·6% of children examined. Class I canine relationship was found in 57% of children, followed by Class II canines in 29% and Class III canines in 3·7%. Fifty per cent of children examined had Class I incisors, 24·7% had Class II Division 1, 13·5% had Class II Division 2 and 11·8% showed reversed overjet. Ideal overbite was seen in 44·3% of children, reduced overbite in 21·8%, increased overbite in 28·2% and 5·7% had anterior openbite. Buccal crossbite was seen in 7% of the sample. Generalized spacing was found in 61·8% and 61·1% of children in the upper and lower arches, respectively. Anthropoid spaces were found in 70% of the upper arches and in 51% of the lower arches. Conclusions. Males had larger tooth/arch dimension than that of females in the primary dentition stage. Mesial step molar relationship was found in 47·7% of the subjects followed by flush terminal molar relationship in 37%. The majority of children examined had spaced primary dentition.     

A pilot clinical study of Class III surgical patients facilitated by improved accelerated osteogenic orthodontic treatments

Objective:To evaluate if the improved accelerated osteogenic orthodontics (IAOO) procedure could speed Class III surgical patients'' preoperative orthodontic treatment duration and, if yes, to what extent. This study was also designed to determine whether or not an IAOO procedure affects the tooth-moving pattern during extraction space closure.Materials and Methods:The samples in this study consisted of 24 Class III surgical patients. Twelve skeletal Class III surgery patients served as an experimental group (group 1) and the others as a control group (group 2). Before treatment, the maxillary first premolars were removed. For group 1, after the maxillary dental arch was aligned and leveled (T2), IAOO procedures were performed in the maxillary alveolar bone. Except for this IAOO procedure in group 1, all 24 patients experienced similar combined orthodontic and orthognathic treatment. Study casts of the maxillary dentitions were made before orthodontic treatment (T1) and after extraction space closure (T3). All of the casts were laser scanned, and the amount of movement of the maxillary central incisor, canine, and first molar, as well as arch widths, were digitally measured and analyzed by using the three-dimensional model superimposition method.Results:The time durations T3–T2 were significantly reduced in group 1 by 8.65 ± 2.67 months and for T3–T1 were reduced by 6.39 ± 2.00 months (P < .001). Meanwhile, the tooth movement rates were all higher in group 1 (P < .05). There were no significant differences in the amount of teeth movement in the sagittal, vertical, and transverse dimensions between the two groups (P > .05).Conclusion:The IAOO can reduce the surgical orthodontic treatment time for the skeletal Class III surgical patient by more than half a year on average. The IAOO procedures do not save anchorage.     

Comparison of arch forms between Korean and North American white populations

The purpose of this study was to evaluate morphologic differences in the mandibular arches of Korean and North American white subjects. The subjects were grouped according to arch form (tapered, ovoid, and square) to compare the frequency distribution of the 3 arch forms between the ethnic groups in each Angle classification. The sample included 160 white (60 Class I, 50 Class II, and 50 Class III) and 368 Korean (114 Class I, 119 Class II, and 135 Class III) subjects. The most facial portion of 13 proximal contact areas was digitized from photocopied images of the mandibular dental arches. Clinical bracket points were calculated for each tooth according to mandibular tooth thickness data, and then 4 linear and 2 proportional measurements were taken. Arch width was statistically significantly smaller in the white group than in the Korean group, but arch depth did not differ. In the Korean group, the most frequent arch form was square, whereas in the white group the tapered arch form predominated. When the subjects were regrouped by arch form, the Korean arches had a tendency to be larger and deeper than the white arches within each of the 3 arch form types.     

Treatment outcomes of various force applications in growing patients with skeletal Class III malocclusion:: A comparative lateral cephalometric study

ObjectivesTo evaluate skeletal, dentoalveolar, and soft tissue changes between intraoral light force application and extraoral heavy force application in growing patients with skeletal Class III malocclusion.Materials andMethods: A retrospective study was conducted with pretreatment and posttreatment lateral cephalometric data from 50 subjects with skeletal Class III malocclusion. In the first group (15 boys, 10 girls; 8.67 ± 2.13 years old), each subject wore a biocreative horseshoe appliance (CHS) with two Class III elastics that exerted a force of 200 g. In the second group (13 boys, 12 girls; 8.96 ± 1.82 years old), each subject wore a Petit-type facemask and a lingual arch with hooks fixed to the maxillary arch with a total force of 700 g. Both groups of patients were instructed to wear the appliance approximately 14 hours a day, and 22 linear measurements and 8 angular measurements were evaluated. Changes of measurements from each group were compared by paired t-tests, considering a 5% significance level.ResultsForward growth of the maxilla, improvement of the maxilla–mandible relationship, and upper incisor flaring were achieved in both groups without any statistically significant difference between them. Lateral cephalometric analysis also showed that U1 exposure, IMPA (Angle between mandibular plane and mandibular incisor axis), FMIA (Angle between FH plan and mandibular incisor axis), and L1-APog (Angle formed by the intersection of tooth axis of lower incisor and A-Pog line, Distance from lower incisor edge to A-Pog line) showed statistically significant differences. Lower incisors were inclined lingually in the CHS group.ConclusionsDuring treatment of skeletal Class III malocclusion, the CHS with light Class III intermaxillary elastics therapy exhibits similar orthopedic changes to the maxillary complex and more dental changes to the lower anterior teeth compared with facemask therapy.     

Adult Class lll Treatment Using a J-Hook Headgear to the Mandibular Arch

Objective:To evaluate the treatment effects of high-pull J-hook headgear on the lower dental arch in nongrowing Class III patients.Materials and Methods:Fourteen nongrowing Class III patients having an Angle Class III malocclusion and ANB angle of less than 1.0 degree, were treated with high-pull J-hook headgear to the lower arch. Using lateral cephalograms and plaster models obtained before treatment (T1), after active treatment (T2), and after the retention period (T3), the treatment outcome was analyzed.Results:The incisal edge of the lower central incisor moved a mean of 1.2 mm to the lingual and 1.7 mm to the occlusal between T1 and T2. The axis of the lower incisor inclined 4.0° to the lingual. The lower first molar cusp moved 1.5 mm to the distal and the root apex moved 2.0 mm to the mesial. Molar angulations were tipped 9.8° to the distal. The occlusal plane showed 4.5° counterclockwise rotation. The mean intermolar width increased 1.5 mm on average. Comparison of the records between T2 and T3 showed minimal changes.Conclusions:Distal movement of the lower dental arch using J-hook headgear was clearly demonstrated, confirming that the application of high-pull J-hook headgear to the lower arch was effective for improvement of the Class III occlusion.