Treatment Effects of Twin-Block and Mandibular Protraction Appliance-IV in the Correction of Class II Malocclusion

Objective:To evaluate the treatment effects of twin-block and Mandibular Protraction Appliance-IV (MPA-IV) in the treatment of Class II division 1 malocclusion.Methods:Fifty North Indian girls with Class II division 1 malocclusion, in the age range of 9–13 years, were chosen. The subjects were divided among a control group (n  =  10), a twin-block group (n  =  25), and an MPA group (n  =  15). Pre–follow-up and post–follow-up lateral cephalograms of control subjects and pretreatment and posttreatment lateral cephalograms of the treatment subjects were traced manually and subjected to a pitchfork analysis.Results:Neither twin-block nor MPA-IV significantly restricted the forward growth of maxilla. Mandibular growth and improvement in the sagittal skeletal relation were significantly greater in the twin-block subjects. Distal movement of the maxillary dentition and mesial movement of the mandibular dentition were more prominent in the MPA-IV subjects. Molar correction and overjet reductions were significantly greater in the treatment subjects (P < .001).Conclusion:Twin-block and MPA-IV were effective in correcting the molar relationships and reducing the overjet in Class II division 1 malocclusion subjects. However, twin-block contributed more skeletal effects than MPA-IV for the correction of Class II malocclusion.     

Effects of twin-block appliance on the anatomy of pharyngeal airway passage (PAP) in class II malocclusion subjects

Background

The use of functional appliances for the correction of retrognathic mandible is very common in orthodontics. Similar appliances known as oral appliances are also frequently used in adults for the treatment of mild to moderate obstructive sleep apnea (OSA). Many studies have reported improvement of pharyngeal airway passage (PAP) dimensions following functional appliance therapy in children and oral appliance therapy in adults. There is only one study in the literature that discussed the effect of oral appliance therapy on posterior pharyngeal wall thickness (PPWT) among subjects with OSA. The effect of functional appliance therapy on PPWT has never been investigated. Thus the present study was conducted to evaluate the effects of twin-block appliance on pharyngeal airway passage (PAP) dimensions and posterior pharyngeal wall thickness (PPWT) in class II malocclusion subjects with retrognathic mandibles.

Methods

Thirty-eight class II malocclusion subjects in the age range of 8 to 14 years with mandibular retrusion were divided into a treatment (n = 20) and control (n = 18) group. Mandibular retrusion in the treatment group subjects was corrected by twin-block appliance. The effect of twin-block appliance on PAP and PPWT dimensions were evaluated from lateral cephalograms recorded prior-to and after 6 months of appliance therapy in the treatment group subjects and the changes were compared with the changes in the control group subjects. Student’s t-test was used for statistical analysis; P-value of 0.05 was considered a statistically significant level.

Results

The depth of the oropharynx was increased significantly in the treatment group subjects (P < 0.001) as compared to the control group subjects (P < 0.05). The depth of the hypopharynx increased significantly in treatment group subjects (P < 0.01). The PPWT at the level of the nasopharynx, oropharynx, and hypopharynx were maintained in the treatment group subjects; whereas in control group subjects, the PPWT was further reduced although the changes were not statistically significant.

Conclusions

Correction of mandibular retrusion by twin-block appliance in class II malocclusion subjects increased the PAP dimensions and maintained the pre-treatment thickness of posterior pharyngeal wall.     

Class II subdivision treatment with the Forsus Fatigue Resistant Device vs intermaxillary elastics

Objective:To compare the effectiveness of comprehensive fixed appliance treatments implemented in combination with Forsus or intermaxillary elastics in Class II subdivision subjects.Materials and Methods:Twenty-eight Class II subdivision patients were allocated to two groups using matched randomization: Forsus group (mean age, 14.19 ± 1.02 years) and elastics group (mean age, 13.75 ± 1.16 years). Patients received fixed appliance therapy in combination with either Forsus or intermaxillary elastics. The study was conducted on lateral cephalograms and digital models acquired before orthodontic treatment and 10–12 weeks after the fixed appliances were removed.Results:The treatment phase comprising the use of Forsus (4.53 ± 0.91 months) was significantly shorter compared with elastics application (6.85 ± 1.08 months). This was also true for comparing duration of overall comprehensive treatment in both groups. Extrusion and palatal tipping of maxillary incisors and clockwise rotation of the occlusal plane were greater in the elastics group (P < .05). The mandibular incisors were proclined in both groups (P < .001), but no significant difference was observed between groups (P > .05). The mandibular incisors showed intrusion in the Forsus group and extrusion in the elastics group; the difference between groups was significant (P < .05). Overbite was decreased in both groups (P < .001) in similar amounts. Improvement in overjet, mandibular midline deviation, and correction of molar relationship on the Class II side were greater in the Forsus group (P < .05).Conclusion:Forsus is more effective for correcting Class II subdivision malocclusion in a shorter treatment period with minimal patient compliance required.     

Three-dimensional positional assessment of glenoid fossae and mandibular condyles in patients with Class II subdivision malocclusion

Objectives:To test the null hypotheses that the positions of the glenoid fossae and mandibular condyles are identical on the Class I and Class II sides of patients with Class II subdivision malocclusion.Materials and Methods:Retrospective three-dimensional (3D) assessments of the positions of the glenoid fossae and mandibular condyles were made in patients with Class II malocclusion. Relative to a fiducial reference at the anterior cranial base, distances from the glenoid fossae and condyles were calculated in pretreatment cone beam computed tomographic scans of 82 patients: 41 with Class II and 41 with Class II subdivision malocclusions. The 3D distances from glenoid fossae to sella turcica in the X (right-left), Y (anterior-posterior), Z (inferior-superior) projections were calculated.Results:Patients with Class II malocclusion displayed a symmetric position of the glenoid fossae and condyles with no statistically significant differences between sides (P > .05), whereas patients with Class II subdivision showed asymmetry in the distance between the glenoid fossae and anterior cranial base or sella turcica (P < .05), with distally and laterally positioned glenoid fossae on the Class II side. (P < .05). Male patients had greater distances between glenoid fossae and anterior cranial fossae (P < .05). The condylar position relative to the glenoid fossae did not differ between the two malocclusion groups nor between males and females (P > .05).Conclusions:The null hypotheses were rejected. Patients with Class II subdivision malocclusion displayed asymmetrically positioned right- and left-side glenoid fossae, with a distally and laterally positioned Class II side, although the condyles were symmetrically positioned within the glenoid fossae.     

Treatment effects of skeletally anchored Forsus FRD EZ and Herbst appliances: A retrospective clinical study

Objective:To evaluate the skeletal, dentoalveolar, and soft tissue effects of the Forsus FRD appliance with miniplate anchorage inserted in the mandibular symphyses and to compare the findings with a well-matched control group treated with a Herbst appliance for the correction of a skeletal Class II malocclusion due to mandibular retrusion.Materials and Methods:The sample consisted of 32 Class II subjects divided into two groups. Group I consisted of 16 patients (10 females and 6 males; mean age, 13.20 ± 1.33 years) treated using the Forsus FRD EZ appliance with miniplate anchorage inserted in the mandibular symphyses. Group II consisted of 16 patients (9 females and 7 males; mean age, 13.56 ± 1.27 years) treated using the Herbst appliance. Seventeen linear and 10 angular measurements were performed to evaluate and compare the skeletal, dentoalveolar, and soft tissue effects of the appliances using paired and Student''s t-tests.Results:Both appliances were effective in correcting skeletal class II malocclusion and showed similar skeletal and soft tissue changes. The maxillary incisor was statistically significantly more retruded in the skeletally anchored Forsus FRD group (P < .01). The mandibular incisor was retruded in the skeletally anchored Forsus FRD group (−4.09° ± 5.12°), while it was protruded in the Herbst group (7.50° ± 3.98°) (P < .001).Conclusion:Although both appliances were successful in correcting the skeletal Class II malocclusion, the skeletally anchored Forsus FRD EZ appliance did so without protruding the mandibular incisors.     

Comparison of stepwise vs single-step advancement with the Functional Mandibular Advancer in Class II division 1 treatment

Objective:To compare two groups of subjects at the peak of the pubertal growth period treated with the Functional Mandibular Advancer (FMA; Forestadent, Pforzheim, Germany) appliance using either single-step or stepwise mandibular advancement.Materials and Methods:This study was conducted on 34 Class II division 1 malocclusion subjects at or just before the peak phase of pubertal growth as assessed by hand-wrist radiographs. Subjects were assigned to two groups of mandibular advancement, using matched randomization. Both groups were treated with the FMA. While the mandible was advanced to a super Class I molar relation in the single-step advancement group (SSG), patients in the stepwise mandibular advancement group (SWG) had a 4-mm initial bite advancement and subsequent 2-mm advancements at bimonthly intervals. The material consisted of lateral cephalograms taken before treatment and after 10 months of FMA treatment. Data were analyzed by means paired t-tests and an independent t-test.Results:There were statistically significant changes in SNB, Pg horizontal, ANB, Co-Gn, and Co-Go measurements in both groups (P < .001); these changes were greater in the SWG with the exception of Co-Go (P < .05). While significant differences were found in U1-SN, IMPA, L6 horizontal, overjet, and overbite appraisals in each group (P < .001), these changes were comparable (P > .05).Conclusion:Because of the higher rates of sagittal mandibular skeletal changes, FMA using stepwise advancement of the mandible might be the appliance of choice for treating Class II division 1 malocclusions.     

Cranial base characteristics in anteroposterior malocclusions: A meta-analysis

Objective:To investigate cranial base characteristics in malocclusions with sagittal discrepancies.Materials and Methods:An electronic search was performed in PubMed, Embase, Web of Science, and the Cochrane Library. A fixed- or random-effect model was applied to calculate weighted mean difference with 95% confidence intervals (CIs) according to statistical heterogeneity. Outcome measures were anterior, posterior, and total cranial base length and cranial base angle. Sensitivity analysis and publication bias were conducted.Results:Twenty studies that together included 1121 Class I, 1051 Class II, and 730 Class III cases qualified for the final analysis. Class III malocclusion demonstrated significantly reduced anterior (95% CI: −1.74, −0.53; P < .001 vs Class I; 95% CI: −3.30, −2.09; P < .001 vs Class II) and total cranial base length (95% CI: −3.33, −1.36; P < .001 vs Class I; 95% CI: −7.38, −4.05; P < .001 vs Class II). Further, Class II patients showed significantly greater anterior and total cranial base length than did Class I patients (95% CI: 0.51, 1.87; P < .001 for SN; 95% CI: 2.20, 3.30; P < .001 for NBa). Cranial base angle was significantly smaller in Class III than in Class I (95% CI: −3.14, −0.93; P < .001 for NSBa; 95% CI: −2.73, −0.68; P  =  .001 for NSAr) and Class II malocclusions (95% CI: −5.73, −1.06; P  =  .004 for NSBa; 95% CI: −6.11, −1.92; P < .001 for NSAr) and greater in Class II than in Class I malocclusions (95% CI: 1.38, 2.38; P < .001 for NSBa).Conclusions:This meta-analysis showed that anterior and total cranial base length and cranial base angle were significantly smaller in Class III malocclusion than in Class I and Class II malocclusions, and that they were greater in Class II subjects compared to controls.     

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.     

Evaluating the effects of functional orthodontic treatment on mandibular osseous structure using fractal dimension analysis of dental panoramic radiographs

ObjectiveTo evaluate the effects of functional appliance treatment on mandibular trabecular structure using fractal dimension (FD) analysis of dental panoramic radiographs.Materials and MethodsThis study was conducted using digital panoramic radiographs of 45 patients with Class II malocclusion treated with functional appliances (treatment group, mean age: 11.39 ± 0.97 years; 23 girls, 22 boys) acquired before (T0) and after (T1) treatment and the panoramic radiographs of 45 control subjects who had undergone no orthodontic treatment (control group, mean age: 11.31 ± 0.87 years; 23 girls, 22 boys). FD values in the condylar process, mandibular corpus, and mandibular angle were analyzed from the panoramic radiographs of both groups.ResultsAnalysis of changes in FD between T0 and T1 revealed significant increases in the FD values of the right and left condylar processes and right mandibular corpus in the treatment group (P < .001) and in the right condylar process in the control group (P < .05). Between-group comparisons demonstrated that the treatment group showed greater changes in the condylar process (right, P < .001; left, P < .05) and right mandibular corpus (P < .05) compared to controls. Correlation analysis between the cephalometric and FD changes in the treatment group showed the right condylar process changes were negatively correlated with GoGn/SN angle (P < .05) and positively correlated with Co-Go (P < .05), although these correlations were weak.ConclusionsFD analysis demonstrated significant changes in trabeculation of the condyle and mandibular corpus in the treatment group compared to the control group. Functional appliance treatment may lead to skeletal correction by altering skeletal form and trabeculation of the mandibular bone.     

Effect of incisor position on the self-perceived psychosocial impacts of malocclusion among Chinese young adults

Objective:To evaluate the impact of the incisor position on the self-perceived psychosocial impacts of malocclusion among Chinese young adults.Materials and Methods:This cross-sectional study included a convenience sample of 17.1- to 22.3-year-old young adults (n  =  1005). The five groups represented were normal occlusion as well as incisor Class I, Class II/1, Class II/2, and Class III malocclusion. For clinical assessment, the incisor relationship was evaluated according to the British Standards Institute Incisor Classification, and the self-perception of dental esthetics was assessed using the Psychosocial Impact of Dental Aesthetics Questionnaire (PIDAQ). Statistical analysis involved the analysis of variance and Tukey multiple-comparison post hoc tests.Results:Psychosocial impacts were different among the five groups for the four PIDAQ domains (P < .001 for all four domains). Statistically significant differences were found between the four malocclusion groups and the normal occlusion group in all four domains (P < .001 for all four domains). Furthermore, statistically significant differences were found between four malocclusion groups.Conclusions:All four malocclusion groups had more severe psychosocial impacts than the normal occlusion group in the four PIDAQ domains. Statistically significant differences were also found between the four malocclusion groups; these malocclusion groups ranked by score, highest to lowest, were Class III, Class II/1, Class II/2, and Class I.     

Sagittal mandibular development effects on the dimensions of the awake pharyngeal airway passage

Objective:To test the hypothesis that sagittal mandibular development has no effects on the dimensions of the awake pharyngeal airway passage.Materials and Methods:Ninety-one subjects (age 15–25 years) with a normal vertical growth pattern of the mandible, normally positioned maxilla, and various sagittal mandibular developments were divided into three groups based on the sagittal mandibular development. Group I included 37 subjects who had a normally positioned mandible (76° ≤ angle between ‘S,’ ‘N,’ and ‘B’; it represents the antero-posterior position of the maxilla in relation to the anterior cranial base [SNB] ≤ 82°), Group II included 31 subjects in whom the mandible was retrognathic (SNB < 76°), and Group III included 23 subjects in whom the mandible was prognathic (SNB > 82°) in relation to the anterior cranial base. Lateral cephalograms were traced manually to evaluate the pharyngeal airway passage.Results:The length of the soft palate was significantly smaller in mandibular prognathism subjects than in subjects with mandibular retrognathism (P < .01). The thickness of the soft palate was significantly greater among subjects with mandibular prognathism than in subjects with normal (P < .01) and retrognathic (P < .001) mandibular development. The sagittal mandibular development had no effect on the dimensions of the nasopharyngeal and hypopharyngeal airway passage. The depth of the oropharynx was comparable among the subjects with normal and retrognathic mandibles but was greater (P < .001) among subjects with mandibular prognathism.Conclusions:The hypothesis is rejected. Sagittal mandibular development had significant effects on the dimensions of the awake pharyngeal airway passage.     

Dentoskeletal effects produced by a Jasper Jumper with an anterior bite plane

Objective:The aim of this retrospective study was to evaluate the dentoskeletal effects produced by a modified Jasper Jumper with an anterior bite plane for the correction of Class II division 1 malocclusion.Materials and Methods:A sample of 32 growing patients (mean age  =  11.9 ± 1.4 years) with Class II division 1 malocclusion and increased overbite were treated with a modified Jasper Jumper (JJ) and anterior bite plane protocol and compared with a matched control group of 30 subjects with untreated Class II malocclusion (mean age 12.2 ± 0.8 years). Lateral cephalograms were taken before treatment (T1) and at the end of comprehensive treatment (T2). Mean treatment duration was 2.1 ± 0.4 years. The T1–T2 changes in the two groups were compared with Student’s t-tests for independent samples.Results:The JJ group was successfully treated to a Class I occlusal relationship with a significant reduction in overjet (–3.9 mm, P < .001) and overbite (–3.1 mm, P < .001). The JJ group exhibited a significant increase in mandibular length and a significant improvement in maxillomandibular sagittal skeletal relationships. The lower incisors were significantly proclined, while the lower first molars demonstrated significant movement in a mesial direction.Conclusions:Use of a modified JJ appliance and anterior bite plane is an effective protocol for the treatment of Class II malocclusion with increased overbite and greater skeletal (75%) than dentoalveolar (25%) effects mainly at the mandibular level.     

Initial growth pattern of children with cleft before alveolar bone graft stage according to cleft type: Unilateral cleft lip and alveolus,unilateral cleft lip and palate,and cleft palate

Objective:To test the null hypothesis that there is no significant difference in the initial growth pattern among three cleft types before alveolar bone graft (ABG) according to cleft type (unilateral cleft lip and alveolus [UCLA], unilateral cleft lip and palate [UCLP], and cleft palate [CP]).Materials and Methods:Samples consisted of the UCLA group, the UCLP group, and the CP group. Individuals were treated with the identical surgical technique by the same surgeon and had no history of orthodontic/orthopedic treatment. Lateral cephalograms taken 1 month before ABG were analyzed using 29 variables. One-way analysis of variance (ANOVA) testing and bivariate and logistic regression analyses were performed.Results:An increasing tendency for Class III relationships in the order of UCLA, UCLP, and CP was noted (ANB, AB-to-facial plane angle, AB-to-mandibular plane angle; P < .001, respectively). UCLP and CP groups demonstrated more posterior positioning of the maxilla (SNA, A-to-N-perp; P < .001, respectively) and a hyperdivergent pattern (gonial angle, SN-GoMe angle, FMA; P < .001, respectively) compared with the UCLA group. Because no differences in palatal plane angle and SN-to-occlusal plane angle were noted among the three groups, the hyperdivergent pattern in the UCLP and CP groups might be due to an innate growth pattern and eventual adaptation of the mandible to maxillary growth. UCLP and CP groups showed more Class III relationships (ANB: P < .05, P < .001, respectively) and a more hyperdivergent pattern (FMA: P < .05, P < .01, respectively) than the UCLA group.Conclusion:When the degree of cleft involvement increases from the primary palate to the secondary palate, the predominance of the Class III relationship and the hyperdivergent pattern increases also.     

Effects of skeletally anchored Class II elastics: A pilot study and new approach for treating Class II malocclusion

Objective:To evaluate the skeletal, dentoalveolar, and soft tissue effects of skeletally anchored Class II elastics and compare them with a matched control group treated by a monobloc appliance for the correction of skeletal Class II malocclusion due to mandibular retrusion.Materials and Methods:Twelve patients (6 girls, 6 boys) were randomly divided into two groups. In the elastics group, six patients (12.9 ± 1.5 years of age; 3 boys, 3 girls) were treated with skeletally anchored Class II elastics. Two miniplates were placed bilaterally at the ramus of the mandible and the other two miniplates were placed at the aperture piriformis area of the maxilla. In the monobloc group (3 boys and 3 girls; mean age, 12.3 ± 1.6 years), patients used the monobloc appliance. The changes observed in each phase of treatment were evaluated using the Wilcoxon matched-pair sign test. Intergroup comparisons at the initial phase of treatment were analyzed by the Mann-Whitney U test.Results:There were statistically significant group differences in Co-Gn, B-VRL, U1-PP, U1-VRL, Ls-VRL, with significant increases in these parameters in the elastics group (P < .05). The mandibular incisors were protruded in the monobloc group (5.45 ± 1.23°), whereas they were retruded in the elastics group (−3.01 ± 1.66°; P < .01).Conclusions:The undesirable dentoalveolar effects of the monobloc appliance were eliminated by using miniplate anchorage. Favorable skeletal outcomes can be achieved by skeletal anchorage therapies which could be an alternative to treat skeletal Class II patients with mandibular deficiency.     

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.     

Three-dimensional analysis of upper airway morphology in skeletal Class III patients with and without mandibular asymmetry

Objective:To compare the three-dimensional (3D) morphology of the upper airway in skeletal Class III patients with and without mandibular asymmetry and to investigate the possible underlying correlations between the morphology of the upper airway and mandibular deviation.Materials and Methods:Cone-beam computed tomography images of 54 subjects with skeletal Class III malocclusion (ANB angle ≤ 0.4°, Wits ≤ −5.5°) were taken and 3D upper airway models were reconstructed using Dolphin 3D software. According to the distance (d) from symphysis menti to the sagittal plane, all subjects were divided into a symmetry group (d ≤ 2 mm) and an asymmetry group (d ≥ 4 mm). Based on the severity of mandibular deviation, the asymmetry group was divided into subgroup I (4 mm ≤d <10 mm) and subgroup II (d ≥ 10 mm). Cross-sectional linear distances, areas, and volumetric variables of the upper airway were measured in the 3D airway model.Results:Width of the inferior limit of the glossopharynx (P3W), cross-sectional area of the anterior limit of the nasal airway (P5S), and height of the glossopharynx (GPH) in the asymmetry group were significantly larger than in the symmetry group. As for subjects with severe mandibular deviation in subgroup II (d ≥ 10 mm), volume of the glossopharynx (GPV), total volume of the pharynx (TPV), length of the inferior limit of the velopharynx (P2L), and ratio of length to width of the inferior limit of the velopharynx (P2L/P2W) showed significantly negative correlations with mandibular deviation (r > 0.7, P < .05).Conclusions:In Class III subjects with severe mandibular asymmetry, the pharyngeal airway showed a tendency toward constriction and presented a more elliptical shape as mandibular deviation became more severe (P < .01).     

Evaluation of the effects of skeletal anchoraged Forsus FRD using miniplates inserted on mandibular symphysis: A new approach for the treatment of Class II malocclusion

Objective:To evaluate the skeletal, dentoalveolar, and soft tissue effects of the Forsus Fatigue Resistant Device (FRD) appliance with miniplate anchorage for the treatment of skeletal Class II malocclusion.Material and Methods:The prospective clinical study group included 17 patients (11 girls and 6 boys; mean age 12.96 ± 1.23 years) with Class II malocclusion due to mandibular retrusion and treated with skeletal anchoraged Forsus FRD. After 0.019 × 0.025-inch stainless steel archwire was inserted and cinched back in the maxillary arch, two miniplates were placed bilaterally on the mandibular symphysis. Then, the Forsus FRD EZ2 appliance was adjusted to the miniplates without leveling the mandibular arch. The changes in the leveling and skeletal anchoraged Forsus FRD phases were evaluated by means of the Paired and Student''s t-tests using the cephalometric lateral films.Results:The success rate of the miniplates was found to be 91.5% (38 of 42 miniplates). The mandible significantly moved forward (P < .001) and caused a significant restraint in the sagittal position of the maxilla (P < .001). The overjet correction (−5.11 mm) was found to be mainly by skeletal changes (A-VRL, −1.16 mm and Pog-VRL, 2.62 mm; approximately 74%); the remaining changes were due to the dentoalveolar contributions. The maxillary and mandibular incisors were significantly retruded (P < .001).Conclusion:This new approach was an effective method for treating skeletal Class II malocclusion due to the mandibular retrusion via a combination of skeletal and dentoalveolar changes.     

Effect of posterior impaction and setback of the maxilla on retropalatal airway and velopharyngeal dimensions after two-jaw surgery in skeletal Class III patients

Objective:To evaluate the changes in retropalatal airway and velopharyngeal dimensions after posterior impaction (PI) only or PI and setback (PI/SB) of the maxilla in patients with skeletal Class III undergoing two-jaw surgery.Materials and Methods:Subjects consisted of 60 Class III patients treated with two-jaw surgery. They were divided into two groups: group 1 (n  = 30; PI of the maxilla; mean  =  2.6 mm) and group 2 (n = 30; PI/SB of the maxilla; mean  =  2.8 mm and 1.8 mm, respectively). Using three dimensional computed tomography images taken 1month before surgery (T0) and at least 6 months after surgery (T1), retropalatal airway volume, minimum cross-sectional area, and lateral and anteroposterior (AP) dimensions of minimum cross-sectional area, soft palate angle, soft palate length, and pharyngeal depth were measured. A paired t-test and independent t-test were used for statistical analysis.Results:Group 1 showed increase in retropalatal airway volume and minimum cross-sectional area (P < .01 and P < .05, respectively). Group 2 exhibited decrease in retropalatal airway volume, minimum cross-sectional area, and lateral and AP dimensions of minimum cross-sectional area (all P < .01). Although groups 1 and 2 showed an increase in soft palate length (P < .01 and P < .001, respectively), pharyngeal depth significantly increased only in group 1 (P < .01). Groups 1 and 2 were significantly different in retropalatal airway volume, minimum cross-sectional area, and AP dimension (P < .05, P < .001, and P < .05, respectively).Conclusion:Because the direction of surgical movement in the maxilla can determine the changes in the retropalatal airway and velopharyngeal dimensions, it is recommended that clinicians investigate whether patients suffer from sleep-related breathing disorders before performing PI/SB of the maxilla.     

Dental archforms in dentoalveolar Class I,II and III

Objective:To test the hypothesis that no differences exist in dental arch dimensions between dentoalveolar Classes I, II, and III, and between male and female subjects, as measured on virtual three-dimensional (3D) models.Materials and Methods:Samples included randomly selected plaster dental casts of 137 white patients (43 Class I, 50 Class II, and 44 Class III) from the Department of Orthodontics, School of Dental Medicine, University of Zagreb, Croatia. Dental models were scanned and digitized using ATOS II SO (“Small Objects”) scanning technology (GOM mbH, Braunschweig, Germany). Eight linear and two proportional measurements were calculated for both upper and lower dental arches.Results:In men, a significant difference in the upper dental arch was present in the incisor region, and in the lower dental arch, differences were found in intercanine and intermolar widths (P < .05). Significant differences were noted between male groups in the upper molar depth dimension (P  =  .022) and in the lower molar and canine depth dimensions (P < .05). Class III males had the greatest lower molar and canine width/depth ratios and the smallest lower canine depth/molar depth ratio. Class III women had wider and shorter mandibular arches when compared with Class I and Class II females.Conclusion:The hypothesis was rejected. The dimensions of the dental arches are related to gender and to dentoalveolar class. Class I and II subjects have similar dimensions of maxillary dental arch, but Class II subjects have a transverse deficit in the mandible. In Class III subjects, the maxillary dental arch is insufficient in transverse and sagittal dimensions, and the mandibular arch dominates in the transverse but not in the sagittal dimension.