Chin cup effects using two different force magnitudes in the management of Class III malocclusions

Objectives:To evaluate the dental and skeletal effects of chin cup using two different force magnitudes in the management of Class III malocclusion cases.Materials and Methods:Fifty growing patients (26 males and 24 females) with skeletal Class III and mandibular prognathism were selected. The patients were divided into three groups. Patients in group 1 (n  =  20) were treated with a chin cup and occlusal bite plane using 600 g of force per side. Patients in group 2 (n  =  20) were subjected to the same treatment as in group 1 but using 300 g of force per side. In group 3 (n  =  10) no treatment was performed. For all patients, lateral cephalograms were taken before treatment and after 1 year. Cephalograms were traced and analyzed. The collected data were analyzed statistically using one-way analysis of variance and the Tukey test.Results:In the treatment groups, the SNB angle and ramus height decreased significantly. The ANB angle, Wits appraisal, anterior facial height, mandibular plane angle, and retroclination of the mandibular incisors were significantly increased in comparison to the control group. Utilization of either force showed no significant differences, except that the reduction in the ramus height was significantly greater with the use of higher force.Conclusions:The use of a chin cup improved the maxillomandibular base relationship in growing patients with Class III malocclusion but with little skeletal effect. The utilization of either force had the same effects, except that the higher force had a more pronounced effect in reduction of ramus height.     

Treatment of Class III malocclusion using miniscrew-anchored inverted Forsus FRD: Controlled clinical trial

Objectives:To evaluate the skeletal, dental, and soft tissue changes after the use of miniscrew-anchored inverted Forsus fatigue-resistant device (FRD) in treatment of Class III malocclusion.Materials and Methods:In this controlled clinical trial, 16 patients (9 girls and 7 boys; age 12.45 ± 0.87 years) were consecutively treated with miniscrew-anchored inverted Forsus FRD. This group was compared with a matched control group of 16 untreated patients (8 girls and 8 boys; age 11.95 ± 1.04 years). Miniscrews were inserted bilaterally between the maxillary canine and first premolar. Forsus FRD was selected and inserted in an inverted manner mesial to the mandibular headgear tube and distal to the maxillary canine bracket.Results:Class I molar and canine relationships with positive overjet were achieved in an average period of 6.4 ± 1.46 months. Maxillary forward growth showed a statistically significant increase (SNA°: 1.73 ± 0.53, P < .5), maxillary incisor proclination was statistically significant (U1 to NA°: −0.39 ± 0.33, P > .5), and the lower incisors exhibited significant retroclination (L1 to NB°: 1.65 ± 0.83, P < .5). Significant lower lip retrusion and upper lip protrusion were obvious treatment outcomes (P < .5).Conclusions:The use of miniscrew-anchored inverted FRD could effectively increase maxillary forward growth, but it did not prevent mesial movement of the maxillary dentition. Significant lower incisor retroclination was observed. Significant esthetic improvement of the facial profile was achieved primarily because of lower lip retrusion and upper lip protrusion.     

Treatment outcomes of Class II malocclusion cases treated with miniscrew-anchored Forsus Fatigue Resistant Device: A randomized controlled trial

Objective:To evaluate the skeletal, dental, and soft tissue effects of the Forsus Fatigue Resistant Device (FRD) used with miniscrew anchorage and compare them with those of the conventional Forsus FRD.Materials and Methods:This study was carried out on 38 patients. These patients were randomly allocated into three groups. The 14 patients in group 1 (aged 12.76 ± 1.0 years) were treated with the FRD appliance. In group 2, the 15 patients (aged 12.52 ± 1.12 years) received treatment with FRD using miniscrew anchorage, and the 9 patients in group 3 (aged 12.82 ± 0.9 years) received no treatment as a control group. Linear and angular measurements were made on lateral cephalograms before and immediately after Forsus treatment. Data were analyzed statistically using paired t-, ANOVA, and Tukey tests.Results:Class I molar relationship and overjet correction were achieved in both treatment groups. Although mandibular growth was statistically nonsignificant, there was a significant headgear effect on the maxilla. Mandibular incisor proclination, maxillary incisor retroclination, and distalization of maxillary molars were significant in both treatment groups. However, no significant differences were found between the treatment groups.Conclusions:Class II correction was mainly dentoalveolar in both treatment groups. Use of miniscrews with Forsus did not enhance mandibular forward growth nor prevent labial tipping of the mandibular incisors.     

Evaluation of the miniplate-anchored Forsus Fatigue Resistant Device in skeletal Class II growing subjects: A randomized controlled trial

Objectives:To evaluate the use of direct miniplate anchorage in conjunction with the Forsus Fatigue Resistant Device (FFRD) in treatment of skeletal Class II malocclusion.Materials and Methods:Forty-eight females with skeletal Class II were randomly allocated to the Forsus plus miniplates (FMP) group (16 patients, age 12.5 ± 0.9 years), Forsus alone (FFRD; 16 patients, age 12.1 ± 0.9 years), or the untreated control group (16 subjects, age 12.1 ± 0.9 years). After leveling and alignment, miniplates were inserted in the mandibular symphysis in the FMP group. The FFRD was inserted directly on the miniplates in the FMP group and onto the mandibular archwires in the FFRD group. The appliances were removed after reaching an edge-to-edge incisor relationship.Results:Data from 46 subjects were analyzed. The effective mandibular length significantly increased in the FMP group only (4.05 ± 0.78). The mandibular incisors showed a significant proclination in the FFRD group (9.17 ± 2.42) and a nonsignificant retroclination in the FMP group (−1.49 ± 4.70). The failure rate of the miniplates was reported to be 13.3%.Conclusions:The use of miniplates with the FFRD was successful in increasing the effective mandibular length in Class II malocclusion subjects in the short term. The miniplate-anchored FFRD eliminated the unfavorable mandibular incisor proclination in contrast to the conventional FFRD.     

Mandibular rotation during the transitional dentition

Objective:To determine whether dentoalveolar changes or vertical condylar growth is more closely related to the true forward rotation of the mandible during the transition between the late primary and early mixed dentition stages of development.Materials and Methods:The sample included 50 subjects (25 males and 25 females) with Class I (N  =  25) and Class II (N  =  25) molar relationships. They were selected based on the availability of lateral cephalograms at two developmental stages: T1: last film with complete primary dentition (5.8 ± 0.4 years) and T2: first film with permanent incisors and permanent molars fully erupted (8.0 ± 0.2 years). Seventeen landmarks were identified and 22 measurements were calculated. The mandibles at T1 and T2 were superimposed using natural reference structures in order to measure true mandibular rotation.Results:The mandible underwent −2.4° ± 2.6° of true rotation, 1.9° ± 2.4° of remodeling, and −0.6° ± 1.8° of apparent rotation. There were no significant sex or Class differences in true rotation, remodeling, and apparent rotation. There was a moderate correlation (r  =  0.76) between true rotation and remodeling and a moderately low correlation (r  =  0.40) between true rotation and apparent rotation. There was a weak correlation between true rotation and SNA (r  =  0.28). True rotation was most closely associated with the increases in U1/S-N (r  =  −0.34), increases in U1/PP (r  =  −0.36), and decreases in Id-Me (r  =  0.36).Conclusions:Independent of sex and Class, the true mandibular rotation that occurred between the late primary and early mixed dentition was mostly masked by angular remodeling, resulting in limited amounts of apparent rotation. True rotation was significantly related to anterior dentoalveolar changes but not to the vertical growth changes that occurred.     

Dentofacial characteristics in orthodontic patients with centric relation–maximum intercuspation discrepancy

Introduction:To investigate dentofacial characteristics of orthodontic patients with centric relation (CR)–maximum intercuspation (MI) discrepancy and to analyze changes in dentofacial characteristics between CR and MI positions in these patients using lateral cephalograms.Materials and Methods:Adult female patients were classified into two groups: large CR-MI discrepancy (greater than 2.0 mm horizontal or vertical mandibular incisor movements during CR to MI change, n  =  20) and small CR-MI discrepancy (less than 1.0 mm horizontal and vertical mandibular incisor movements during CR to MI change, n  =  22). All subjects underwent temporomandibular joint (TMJ) magnetic resonance imaging prior to treatment. Gnathological stabilizing splints were used to find a reliable CR position in patients with large CR-MI discrepancy. Sixteen variables from lateral cephalograms were analyzed to identify differences in cephalometric variables between CR and MI positions in patients with large discrepancy. Differences in dentofacial cephalometric variables at MI positions between patients with large and small CR-MI discrepancies were also analyzed.Results:Patients with large CR-MI discrepancy had backward positioning and rotation of the mandible at the MI position compared to the norm. In addition, the mandible moved more posteriorly and rotated more in a clockwise direction during MI to CR change. Interestingly, all patients with large CR-MI discrepancy had TMJ disk displacement. There were no significant differences in the cephalometric variables of the MI positions between patients with small and large CR-MI discrepancies.Conclusions:This study suggests that adult patients with backward positioning and rotation of the mandible should be carefully evaluated as a result of the potential CR-MI discrepancy.     

Incisor inclination changes produced by two compliance-free Class II correction protocols for the treatment of mild to moderate Class II malocclusions

Objective:To compare the changes in incisor inclination between two compliance-free Class II correction protocols for the treatment of mild to moderate Class II malocclusions.Materials and Methods:Among Class II malocclusion patients a total of 38 consecutive patients treated with the Xbow appliance and later with full brackets (XB) were compared to 36 consecutive patients treated with Forsus connected to the archwire while on full brackets (FO). Evaluated cephalometric variables were overjet, overbite, skeletal Class II, lower incisor inclination, and upper incisor inclination. Factors that were analyzed were gender, treatment type, age at start of treatment (T1), and treatment length. Independent t-tests, χ², multiple analysis of variance, and Pearson correlations were applied.Results:No differences in incisor inclination between both treatment protocols were identified. At T1 no statistical difference for any cephalometric variable was demonstrated with regard to gender and treatment type. Gender was also not associated with a different treatment time or age at T1. The mean treatment time was 24.2 months for XB and 30.2 months for the FO group (P  =  .037). XB patients averaged 10 fewer months of fixed edgewise appliances compared to FO patients. Neither gender nor treatment type had any influence on the changes of the evaluated dependent variables between T1 and the end of treatment. Lower incisors proclined more the longer the treatment (P  =  .005). Both overjet and upper incisor inclination were affected by age at T1 (P  =  .001 and P  =  .014, respectively).Conclusions:Both compliance-free Class II correction protocols for the treatment of mild to moderate Class II malocclusions appear to generate the same amount of incisor inclination. Large variability was identified.     

A randomized clinical trial comparing mandibular incisor proclination produced by fixed labial appliances and clear aligners

Objective:To compare the mandibular incisor proclination produced by fixed labial appliances and third generation clear aligners.Materials and Methods:Patients underwent a course of orthodontic treatment using either fixed labial appliances or clear aligners (Invisalign). Mandibular incisor proclination was measured by comparing pretreatment and near-end treatment lateral cephalograms. Eligibility criteria included adult patients with mild mandibular incisor crowding (<4 mm) and Class I skeletal bases (ANB, 1–4°). The main outcome was the cephalometric change in mandibular incisor inclination to the mandibular plane at the end of treatment. Eligible patients picking a sealed opaque envelope, which indicated their group allocation, was used to achieve randomization. Data was analyzed using a Welch two-sample t-test.Results:Forty-four patients (mean age, 26.4 ± 7.7 years) were randomized in a 1:1 ratio to either the fixed labial appliance or the clear aligner group. Baseline characteristics were similar for both groups: Fixed appliance mean crowding was 2.1 ± 1.3 mm vs clear aligner mean crowding, 2.5 ± 1.3 mm; pretreatment mean mandibular incisor inclination for the fixed appliance group was 90.8 ± 5.4° vs 91.6 ± 6.4° for the clear aligner group. Fixed appliances produced 5.3 ± 4.3° of mandibular incisor proclination. Clear aligners proclined the mandibular incisors by 3.4 ± 3.2°. The difference between the two groups was not statistically significant (P > .05).Conclusion:There was no difference in the amount of mandibular incisor proclination produced by clear aligners and fixed labial appliances in mild crowding cases.     

Evaluation of the splint-supported Forsus Fatigue Resistant Device in skeletal Class II growing subjects

ObjectivesTo evaluate the use of the Forsus Fatigue Resistant Device (FFRD), supported with bimaxillary splints, in treatment of skeletal Class II malocclusion.Materials and MethodsData from 46 skeletal Class II females who received either conventional Forsus alone (FFRD group) (15 patients, 12.54 ± 0.90 years), FFRD and bimaxillary splints (splint-FFRD group) (15 patients, 12.29 ± 0.82 years), or were untreated controls (16 subjects, 12.1 ± 0.9 years) were retrieved from previous clinical trials. FFRD was inserted onto the mandibular archwire in the FFRD group after leveling and alignment with multibracket appliances. In the splint-FFRD group, Forsus was inserted between fixed maxillary and mandibular splints. Treatment continued until reaching an edge-to-edge incisor relationship.ResultsBoth treatment groups failed to induce significant mandibular skeletal effects compared to the normal growth exhibited by untreated controls. The splint-FFRD group showed significant reduction of SNA (−0.88° ± 0.51°) and ANB (−1.36° ± 0.87°). The mandibular incisors showed significant proclination in the FFRD (9.17° ± 2.42°) and splint-FFRD groups (7.06° ± 3.34°).ConclusionsThe newly proposed splint-supported FFRD was equally effective as the conventional FFRD in treatment of Class II malocclusion with dento-alveolar changes and additional maxillary restricting effect. It has an additional advantage of immediate initiation of the Class II correction.     

Maxillary anterior alignment stability in Class I and Class II malocclusions treated with or without extraction

Objective:To compare the postretention stability of maxillary incisors alignment in subjects with Class I and II malocclusion treated with or without extractions.Materials and Methods:The sample comprised 103 subjects with initial maxillary anterior irregularity greater than 3 mm and was divided into four groups: group 1 comprised 19 patients with Class I malocclusion treated with nonextraction (mean initial age = 13.06 years); group 2 comprised 19 patients with Class II malocclusion treated with nonextraction (mean initial age = 12.54 years); group 3 comprised 30 patients with Class I malocclusion treated with extractions (mean initial age = 13.16 years); group 4 comprised 35 patients with Class II malocclusion treated with extractions (mean initial age = 12.99 years). Dental casts were obtained at three different stages: pretreatment (T1), posttreatment (T2), and long-term posttreatment (T3). Maxillary incisor irregularity and arch dimensions were evaluated. Intergroup comparisons were performed by one-way analysis of variance followed by Tukey tests.Results:In the long-term posttreatment period, relapse of maxillary crowding and arch dimensions was similar in all groups.Conclusion:Changes in maxillary anterior alignment in Class I and Class II malocclusions treated with nonextractions and with extractions were similar in the long-term posttreatment period.     

Dentofacial effects of two facemask therapies for maxillary protraction: Miniscrew implants versus rapid maxillary expanders

Objective:To compare the dentofacial effects of maxillary protraction with two facemask therapies in growing Class III patients: facemask in association with miniscrew implants (MSI/FM) and facemask with rapid maxillary expanders (RME/FM).Materials and Methods:Forty-three Chinese patients with Class III malocclusion and maxillary deficiency were randomly assigned to a MSI/FM sample of 20 patients and a RME/FM sample of 23 subjects. The changes in dentofacial cephalometric variables from the beginning (T1) to the end of treatment (T2) were compared with t-test for paired samples in both groups and for independent samples between the two groups.Results:No significant cephalometric differences were observed between the two groups in active treatment effects except for maxillary dental variables. However, significant favorable changes in both maxillary and mandibular skeletal components were noted in two groups after treatment. Sagittal measurements showed the maxilla was advanced, mandibular projection was reduced, and the relative sagittal intermaxillary discrepancy improved. Patients experienced additional unfavorable outcomes of clockwise rotation of the mandible as well as retroclination of the lower incisors. The soft tissue profile was improved remarkably in both groups. Proclination of the maxillary incisors and mesialization of the maxillary dentition were significantly different between the two groups. The increases in U1-SN, U1-VR, and U6-VR were 6.41°, 2.78 mm, and 1.24 mm less in the MSI/FM group than in the RME/FM group, respectively.Conclusions:Compared with the RME/FM therapy, the MSI/FM protocol using a smaller magnitude of protraction force improves skeletal relationships and soft tissue profile and reduces the undesired dentoalveolar effects.     

Evaluation of mandibular volume classified by vertical skeletal dimensions with cone-beam computed tomography

Objective:To investigate the relationship between anteroposterior and vertical differences in maxillofacial morphology and mandibular volume.Materials and Methods:Subjects comprised 213 Japanese adults (84 males and 129 females) who were divided into three groups based on mandibular basal arch (ANB) and Wits, measured in a cephalometric analysis: Class I (−1° ≤ ANB < 4°,−1 mm ≤ Wits < 0 mm), Class II (ANB ≥ 4°, Wits ≥ 0), and Class III (ANB <−1°, Wits <−1 mm). Subjects were also divided into three groups based on the mandibular plane angle (Mp), as follows: hypodivergent (Mp < 23°), normodivergent (Mp  =  23–30°), and hyperdivergent (Mp > 30°) groups. Mandibular volume was measured from cone-beam computed tomographic images that were analyzed using Analyze™ image processing software and compared among the three groups in each classification.Results:No significant differences were noted in mandibular volume among Classes I, II, and III. An inverse relationship was found between mandibular volume and Mp, and a significant difference was noted in mandibular volume between the hypodivergent and hyperdivergent groups.Conclusions:In addition to two-dimensional analysis, such as lateral cephalometry, three-dimensional information such as volume, provided by cone-beam computed tomography, contributes to a more detailed assessment of maxillofacial morphology.     

Dentofacial traits in association with lower incisor alveolar cancellous bone thickness: A multiple regression analysis

Objective:To identify dentofacial anatomic traits associated with lower incisor cancellous bone thickness (LICBT) and then to assess their separate contributions and their combined contributions to the variation in LICBT.Materials and Methods:A consecutive sample of cone beam computed tomography (CBCT) data taken in a university hospital within the same setting was retrospectively reviewed. Within the sample, CBCT data of 252 eligible subjects were reconstructed and measured for LICBT, facial traits, and mandibular symphyseal traits. A backward multiple linear regression was employed to explore the association between LICBT and seven representative dentofacial traits.Results:Four dentofacial traits (vertical facial pattern, transverse jaw relationship, lower incisor cervical diameter, and mandibular symphyseal width) were identified as significantly associated with LICBT. The combination of these four factors could predict 64.3% of variations in LICBT (adjusted R² = 0.643). Further comparison of LICBT among different transverse jaw relationships suggested that the LICBT of the normal (5.94 ± 1.58 mm) group and the inferior convergent group (5.38 ± 1.32 mm) were significantly larger than that of the crossbite group (4.34 ± 1.27 mm) and the superior convergent group (4.53 ± 1.67 mm).Conclusions:The bony support of lower incisors is significantly associated with several dentofacial traits. Reduced lower incisor bony support was statistically associated with increased vertical facial pattern, transverse jaw discrepancy, thinner mandibular symphyseal width, and smaller lower incisor cervical diameter.     

Treatment effects of the Forsus Fatigue Resistant Device used with miniscrew anchorage

Objective:To evaluate the dentofacial effects of the Forsus Fatigue Resistant Device (FRD) used with miniscrew anchorage (FRDMS) and compare them with those of conventional FRD and an untreated Class II control group.Materials and Methods:The sample consisted of 48 Class II subjects. Sixteen patients (13.68 ± 1.09 years of age) were treated with FRDMS, whereas 17 subjects (14.64 ± 1.56 years of age) were treated with only FRD. Also, a control sample of 15 untreated Class II subjects (14.13 ± 1.50 years of age) was constructed. Angular and linear measurements were made on 96 lateral cephalograms. Paired t, one-way analysis of variance, and Tukey tests were used for statistical analysis.Results:Class I molar relationship and overjet correction were achieved in an average period of 6.5 ± 1.97 and 5.5 ± 1.80 months in the FRDMS and FRD groups, respectively. No skeletal effect was determined in both treatment groups. Greater overbite correction was found in the FRD group. Retrusion and extrusion of maxillary incisors, distalization of maxillary molars, and extrusion of mandibular molars were significant in both treatment groups. Labial tipping of mandibular incisors was significantly greater in the FRD group than in the FRDMS group.Conclusion:Overjet and molar correction was totally dentoalveolar. Unfavorable labial tipping of mandibular incisors was effectively minimized with the usage of miniscrews.     

Herbst treatment with mandibular cast splints—revisited

Objective:The objective of this study was to reassess the dento-skeletal treatment effects and the amount of anchorage loss during reduced mandibular splint (RMS) Herbst treatment.Materials and Methods:One hundred consecutive Class II patients treated with a RMS-Herbst appliance were analyzed. The mean pretreatment age of the patients was 14.5 years, and the mean treatment time with the Herbst appliance was 8.1 months. Both before (T1) and after (T2) Herbst treatment a cephalometric measurement of lower incisor inclination, a sagittal occlusion analysis, and a dental cast analysis were performed. A comparison was performed with a historic Herbst control group treated with total mandibular cast splints (TMS).Results:During treatment the lower incisors proclined markedly (12.9° ± 4.6°). The amount of incisor proclination in the RMS group was, on average, 3.6° larger (P < .001) than in the TMS group. The lower incisor proclination increased from 11.9° (prepeak) to 14.3° (young adult). The level of professional experience of the practitioners performing the treatment did not influence the amount of incisor proclination significantly. The total available space in the lower arch increased by an average of 1.8 mm, and a space opened between the lower second premolars and lower permanent first molars in 62% of the present RMS-Herbst (average of 0.4 mm per side).Conclusions:Treatment with RMS-Herbst appliances leads to higher proclination of the lower incisors than does treatment with TMS-Herbst appliances; it also leads to an overall larger amount of anchorage loss.     

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.     

Long-term evaluation of Class II subdivision treatment with unilateral maxillary first molar extraction

Objective:To evaluate the long-term effects of asymmetrical maxillary first molar (M1) extraction in Class II subdivision treatment.Materials and Methods:Records of 20 Class II subdivision whites (7 boys, 13 girls; mean age, 13.0 years; SD, 1.7 years) consecutively treated with the Begg technique and M1 extraction, and 15 untreated asymmetrical Class II adolescents (4 boys, 11 girls; mean age, 12.2 years; SD, 1.3 years) were examined in this study. Cephalometric analysis and PAR assessment were carried out before treatment (T1), after treatment (T2), and on average 2.5 years posttreatment (T3) for the treatment group, and at similar time points and average follow-up of 1.8 years for the controls.Results:The adjusted analysis indicated that the maxillary incisors were 2.3 mm more retracted in relation to A-Pog between T1 and T3 (β  =  2.31; 95% CI; 0.76, 3.87), whereas the mandibular incisors were 1.3 mm more protracted (β  =  1.34; 95% CI; 0.09, 2.59), and 5.9° more proclined to the mandibular plane (β  =  5.92; 95% CI; 1.43, 10.41) compared with controls. The lower lip appeared 1.4 mm more protrusive relative to the subnasale-soft tissue-Pog line throughout the observation period in the treated adolescents (β  =  1.43; 95% CI; 0.18, 2.67). There was a significant PAR score reduction over the entire follow-up period in the molar extraction group (β  =  −6.73; 95% CI; −10.7, −2.7). At T2, 65% of the subjects had maxillary midlines perfectly aligned with the face.Conclusions:Unilateral M1 extraction in asymmetrical Class II cases may lead to favorable occlusal outcomes in the long term without harming the midline esthetics and soft tissue profile.     

A Comparison Study of Upper Airway among Different Skeletal Craniofacial Patterns in Nonsnoring Chinese Children

Objective:Patients with OSAS (obstructive sleep apnea syndrome) demonstrate decreased upper airway dimension and craniofacial skeletal abnormalities. The study was performed to analyze whether upper airway dimensions differed among Chinese nonsnoring children of different sagittal and vertical skeletal facial morphologies.Materials and Methods:Lateral cephalometric records were used to measure the dimensions of the upper airway. Two groups of subjects were studied. A group of subjects with a normodivergent facial pattern (n  =  190; FH-MP angle between 23.5° and 30.5°) was divided into three subgroups according to ANB angle (Class I, II, or III). A second group of subjects with a normal sagittal facial pattern (n  =  180; ANB angle between 0.7° and 4.7°) was divided into three subgroups according to the FH-MP angle (low angle, normal angle, or high angle). All subgroups were matched for age and sex.Results:In the group of subjects with a normodivergent facial pattern, a significant tendency for reduced upper airway dimension in the inferior part (palatopharyngeal and hypopharynx) was found in the Class III, Class I, and Class II subgroups, in that order. In the group of subjects with a normal sagittal facial pattern, the superior part of the airway (nasopharyngeal and palatopharyngeal) decreased with increasing mandibular plane angle.Conclusion:The sagittal and vertical skeletal patterns may be contributory factors for the variation of the inferior and superior part of the upper airway, respectively. Skeletal deficiency of nonsnoring Chinese children may predispose them to upper airway obstruction.     

The Class II Carriere Motion appliance:: A 3D CBCT evaluation of the effects on the dentition

ObjectivesTo determine three-dimensional treatment changes produced by the Class II Carriere Motion appliance (CMA) in Class II adolescent patients with Class I and Class II skeletal relationships.Materials and MethodsThe sample included 59 adolescents (16 boys and 43 girls) with unilateral or bilateral Class II molar and bilateral Class II canine relationship. They were divided into group 1 with skeletal Class I (N = 27; ANB 2.90° ± 1.40°; 13.30 ± 1.53 years) and group 2 with skeletal Class II (N = 32; ANB 6.06° ± 1.64°; 13.26 ± 1.76 years). Cone beam computed tomography images were traced with Invivo software pretreatment (T1) and post-CMA usage (T2). The treatment changes in 36 measurements were calculated in each group, and the changes in 16 measurements were compared between them.ResultsIn group 1 and 2, maxillary first molars underwent significant distal movement (1.92 mm ± 0.80 mm and 1.67 mm ± 1.56 mm, respectively) with distal tipping and rotation, maxillary canines underwent significant distal movement (2.34 mm ± 1.07 mm and 2.24 mm ± 1.91 mm, respectively) with distal tipping and rotation, and mandibular molars underwent significant mesial movement (–1.37 mm ± 1.23 mm and –2.51 mm ± 1.51 mm, respectively) with mesial tipping. Between the groups, there were significant differences in mandibular molar mesial movement and the U1-SN changes (P < .05).ConclusionsThe CMA corrected Class II malocclusion through distal tipping and rotational movement of maxillary canines and molars and corrected mesial tipping of mandibular molars. Significantly more mandibular molar mesial movement and maxillary incisor flaring were observed in patients with skeletal Class II.     

Response of the maxillary dentition to a statically determinate one-couple system with tip-back mechanics: A prospective clinical trial

Objective:To quantify the effects of tip-back mechanics on the maxillary first molars and incisors.Materials and Methods:Sixteen subjects with Class II end-on malocclusion were treated with an intrusion arch to achieve distalization of the maxillary molar through tip-back mechanics. Lateral cephalograms were taken prior to molar tip-back (T1), after molar tip-back (T2), and after molar root uprighting (T3). Data were analyzed using the Friedman’s and Wilcoxon signed rank tests to evaluate differences in time points (P ≤ .016).Results:The maxillary first molar distalized 1.53 mm (P = .001) with 6.65° (P = .001) of distal tipping and 0.86 mm (P = .001) of extrusion at T2. Minor relapse of the first molar (mesial direction) was seen at T3. The maxillary incisors flared labially 0.4 mm, and the incisor root apex moved palatally 1.19 mm (P = .005) at T2. At T3, the incisor root apex moved palatally 1.5 mm (P = .003) from T1. An angular change from T1 of 3.31° (P = .008) and 3.53° (P = .014) was seen at T2 and T3, respectively, as a result of palatal root movement of the maxillary incisors.Conclusions:A significant amount of distalization of maxillary molars was attained at the crown level with tip-back mechanics. Palatal root angulation change was significant in the incisors with minimal anteroposterior movement of the incisal edge.