Assessment of pharyngeal airway volume in adolescent patients affected by bilateral cleft lip and palate using cone beam computed tomography

Objective:To test the null hypothesis that there were no significant differences for pharyngeal airway volumes between the adolescent patients affected by bilateral cleft lip and palate (BCLP) and well-matched controls using cone beam computed tomography.Materials and Methods:The study sample consisted of 16 patients (11 female and 5 male; mean [SD] age 14.1 [2.1] years) affected by BCLP and 16 patients (10 female and 6 male; mean [SD] age 13.4 [2.0] years) as age- and sex-matched control group. Craniofacial measurements and pharyngeal airway dimension, area, and volume measurements of patients in both groups were calculated and statistically examined using Student''s t-test and multiple linear regression analyses.Results:Statistically significant differences were found between the BCLP and control groups for SNB (P < .05), SN-GoGn (P < .05), Co-A (P < .05), PAS (P < .01), minAx (P < .01), and oropharyngeal airway volume (P < .05). The most predictive variables for oropharyngeal airway volume were found as PAS (r  =  .655 and P  =  .000) and minAx (r  =  .787 and P  =  .000).Conclusions:The null hypothesis was rejected. Oropharyngeal (P < .05) and total (P > .05) airway volumes were found to be less in the BCLP group, and thus the treatment choice in these patients should have positive effects on the pharyngeal airway.     

Risk factors for small pharyngeal airway dimensions in preorthodontic children: A three-dimensional study

Objective:To analyze which parameters, gathered from standard orthodontic diagnostic material, were most relevant for identifying small pharyngeal airway dimensions in preorthodontic children.Materials and Methods:The sample was composed of 105 cone beam computed tomography scans of healthy preorthodontic children (44 boys, 61 girls; mean age, 10.7 ± 2.4 years). Airway volume and minimal cross-sectional area were three-dimensionally assessed. Cephalometric features and skeletal maturity were assessed on generated two-dimensional cephalograms. Associations were analyzed and adjusted for age, gender, and skeletal maturity by multiple regression analyses.Results:Airway volume and minimal cross-sectional area were significantly smaller in prepubertal children (P < .001, P < .05, respectively) and positively associated with age (P < .001, P < .01, respectively). After adjustment of age, skeletal maturity and gender significant associations were found between pharyngeal airway dimensions and craniofacial morphology. Airway volume was positively associated with maxillary and mandibular width (P < .01; P < .001, respectively) and anterior face height (P < .05; P < .05, respectively). Minimal cross-sectional area was positively associated with maxillary and mandibular width (P < .01; P < .001, respectively) and negatively associated with sagittal jaw relationship (AnPg, P < .05). Mandibular width and age were the most relevant factors for airway volume (r² = 0.36). Mandibular width and sagittal jaw relationship were the most relevant factors for minimal cross-sectional area (r² = 0.16).Conclusion:Pharyngeal airway dimensions were significantly associated with age, skeletal maturity, and craniofacial morphology in all three planes. Children with a reduced mandibular width and increased sagittal jaw relationship are particularly at risk of having small pharyngeal airway dimensions.     

The influence of craniofacial morphology on the upper airway dimensions

Objective:To evaluate the influence of craniofacial morphology on the upper airway dimensions in healthy adult subjects.Materials and Methods:The records of 276 healthy 17- to 27-year-old patients were extracted from the cone-beam computed tomography image database of the Institute of Stomatology, Riga Stradins University. Dolphin 11.7 software was used to evaluate craniofacial anatomy and semiautomatic segmentation of the upper airway. Measurements of oropharyngeal airway volume (OPV), minimal cross-sectional area (CSAmin), and nasopharyngeal airway volume (NPV) were obtained. The presence of adenoid tissues was recorded. Associations between variables were analyzed by Spearman''s correlation coefficients, and multivariate linear regression analysis was used to identify factors that had a possible influence on upper airway dimensions.Results:The following factors were identified as influencing the variability of NPV (23%): SNA angle, gender, and presence of adenoids. Statistically significant, although weak, correlations were found between SNB angle and OPV (r  =  0.144, P < .05) and CSAmin (r  =  0.182, P < .01).Conclusion:The results suggest that craniofacial morphology alone does not have a significant influence on upper airway dimensions.     

Morphometric evaluation of changes in the alveolar bone and roots of the maxillary anterior teeth before and after en masse retraction using cone-beam computed tomography

Objective:To evaluate the morphometric changes in the alveolar bone and roots of the maxillary anterior teeth (MXAT) after en masse retraction with maximum anchorage (EMR-MA).Materials and Methods:The samples consisted of 37 female adult patients who had Class I dentoalveolar protrusion (CI-DAP) and were treated by extraction of the first premolars and EMR-MA. Using three-dimensional cone-beam computed tomography taken before treatment and after space closure, the maxillary central incisors (MXCI, N  =  66), lateral incisors (MXLI, N  =  69), and canines (MXC, N  =  69) were superimposed using individual reference planes. After alveolar bone area (ABA), vertical bone level (VBL), root length (RL), root area (RA), and prevalence of dehiscence (PD) were measured at the cervical, middle, and apical levels, statistical analyses were performed.Results:On the palatal side, ABA significantly decreased in all levels of MXAT (P < .001; middle of MXC, P < .01). MXCI and MXLI exhibited a greater decrease in the ratio of change in palatal ABA than did MXC (cervical, P < .01; middle and apical, P < .05; total, P < .001). Palatal/labial ABA ratios decreased in MXCI (cervical, middle, total, P < .001; apical, P < .05) and MXLI (cervical, P < .001; apical, P < .05). They showed greater amounts and ratios of change in VBL on the palatal side compared to the labial side (all P < .001). The palatal side showed more PD in the cervical area than did the labial side (MXCI and MXLI, P < .001; MXC, P < .01). Significant root resorption occurred in MXAT (RL and RA, all P < .001).Conclusions:During EMR-MA in cases with CI-DAP, ABA and VBL on the palatal side and RL and RA of MXCI and MXLI were significantly decreased.     

The use of SPHARM-PDM and mean latitude axis to evaluate airway changes

Objective:To introduce new 3-D imaging techniques to characterize shape and volume changes of the oropharyngeal space after bilateral sagittal split osteotomy (BSSO) advancement.Materials and Methods:Longitudinal cone-beam computed tomography (CBCT) scans were obtained for 20 patients undergoing BSSO advancement at three time points (T1 = presurgery, T2 = splint removal, and T3 = 1 year after surgery). Segmentation of the airway was performed using the following boundaries: hard palate/posterior nasal spine superiorly and lower border of C3 to the base of the epiglottis inferiorly. For shape measurements, point-based correspondent models and mean latitude axis were obtained for all the data using SPHARM-PDM software. All 3-D correspondent models were rigidly registered using Procrustes alignment. Absolute distance maps and corresponding vector maps were calculated to show shape and vector differences between each correspondent point. Mean latitude axis is a new imaging method to calculate minimum cross-sectional areas along the long axis of the airway independent of head position/alignment.Results:The airway volume increased (P < .01) after BSSO advancement (2973.9 mm³ ± 27882.0) and was stable (−439.9 mm³ ± 3308.8) 1 year post-op. 3-D color maps and semitransparency overlays showed more lateral than anteroposterior expansion of the airway after BSSO advancement. Mean latitude axis was used to measure minimum cross-sectional area, showing a statistically significant increase (52.7 mm² ± 46.7) (P < .01) after surgery and remained stable (−10.3 mm² ± 43.3) 1 year after surgery.Conclusions:SPHARM-PDM and mean latitude axis are useful tools to assess airway shape change. BSSO advancement produces a significant increase in pharyngeal airway volume and minimum cross-sectional area. The airway space increased more transversely than anteroposteriorly.     

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.     

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.     

The short-term treatment effects of face mask therapy in Class III patients based on the anchorage device: Miniplates vs rapid maxillary expansion

Objective:To compare the short-term treatment effects of face mask therapy with miniplates (FM-MP) and face mask therapy with rapid maxillary expansion appliance (FM-RME) in growing Class III malocclusion patients with maxillary hypoplasia.Materials and Methods:Twenty patients were allocated into two groups according to the anchorage device: FM-MP group (n  =  10; mean age  =  11.2 ± 1.2 years; miniplates in the zygomatic buttress area) and FM-RME group (n  =  10; mean age  =  10.7 ± 1.3 years; bonded or banded RME). The face mask was applied for 12 to 14 hours/day in both groups with a force of 400 g/side directed 30° downward and forward from the occlusal plane. Lateral cephalograms were taken before (T1) and after FM-MP or FM-RME therapy (T2). Skeletodental and soft-tissue variables were measured. Paired and independent t-tests were performed for statistical analysis.Results:Both groups exhibited significant forward movement of point A and posterior repositioning and opening rotation of the mandible from T2 to T1. The FM-MP group showed significant protraction of orbitale (ΔSNO), and the FM-RME group showed a decrease in overbite and an increase in Björk sum. Comparing the amount of changes between the two groups, the FM-MP group displayed greater forward movement of the maxilla than the FM-RME group (ΔSNA, ΔA to N perp, all P < .05). However, the FM-RME group exhibited a greater opening rotation of the mandible (ΔSNB, Björk sum, all P < .01; ΔPog to N-perp, P < .05) and labioversion of the maxillary incisors (ΔU1-FH, P < .05).Conclusion:FM-MP therapy induces a greater advancement of the maxilla, less posterior repositioning and opening rotation of the mandible, and less proclination of the maxillary incisors than FM-RME therapy.     

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.     

Skeletal and Soft Tissue Point A and B Changes Following Orthodontic Treatment of Nepalese Class I Bimaxillary Protrusive Patients

Objectives:To test the hypothesis that there is no correlation in the interrelationships of skeletal and soft tissue points A and B with anterior teeth retraction.Materials and Methods:Thirty adult Class I bimaxillary protrusion patients treated with preadjusted appliances after first premolar extraction were included. Pretreatment and posttreatment variables were compared using paired t-test, and the relationship of soft and hard tissue variables was studied using Pearson correlation coefficient and linear regression equation.Results:Mean point A and soft tissue point A (sA) were retracted 2.7 mm (P < .001) and 1.7 mm (P < .001), and mean point B and soft tissue point B (sB) were retracted 2.1 mm (P < .001) and 1.2 mm (P < .001), respectively. Mean ratio of retraction of point A with sA and point B with sB was 1.5∶1 and 1.7∶1, respectively. A significant degree of correlation existed between retraction of point A and soft tissue point A (r  =  0.648, P < .01) and point B and soft tissue point B (r  =  0.806, P < .01). Linear regression analysis used to predict the changes in sA and sB showed significant relationship between point A and sA (r  =  0.543, F  =  11.7, R²  =  0.29, P < .001) and point B and sB (r  =  0.825, F  =  59.7, R²  =  0.68, P < .001). Decreases in hard and soft tissue convexity were due to the retraction of the skeletal and soft tissue points A and B in addition to the lips retraction.Conclusions:The hypothesis is rejected. Retraction of skeletal point A and B lead to retraction of sA and sB under controlled root positions. Nearly proportionate changes existed in the skeletal points and overlying corresponding soft tissue points.     

Comparison of dimensions and volume of upper airway before and after mini-implant assisted rapid maxillary expansion

ObjectivesTo evaluate changes in dimensions and volume of upper airway before and after mini-implant assisted rapid maxillary expansion (MARME) and observe correlations between changes of upper airway and vertical skeletal pattern in young adults.Materials and MethodsIn this retrospective study, 22 patients (mean age, 22.6 ± 4.5 years; 4 male 18 female) with transverse discrepancy underwent MARME. Cone beam computed tomography was taken before and 3 months after expansion. Vertical and horizontal dimensions and volume of the nasal cavity, nasopharyngeal, retropalatal, retroglossal and hypopharyngeal airway were compared before and after MARME. Correlations between changed volume and dimensions were explored, as well as the vertical skeletal pattern.ResultsNasal osseous width, maxillary width, volume of the nasal cavity and nasopharynx increased significantly (P < .05). Enlarged nasopharyngeal volume correlated with increased nasal width at the PNS plane (P < .05). There were no correlations between expanded volume and maxillary width. No measurements except nasal cavity volume had a correlation with Sum angle. Increased maxillary width correlated negatively with hard palate thickness (P < .05).Conclusions(1) MARME caused an increase in volume of the nasal cavity and nasopharynx, with expansion of nasal osseous width and maxillary width. (2) Enlarged nasal width at the PNS plane contributed to the increase in nasopharynx volume. Enlarged maxillary width showed no direct relation with increased volume. (3) In this study, it was unclear about the association between changes of the upper airway and vertical skeletal pattern because of complex structures. (4) Palate thickness affected skeletal expansion of the maxilla in MARME.     

An evaluation of two different mandibular advancement devices on craniofacial characteristics and upper airway dimensions of Chinese adult obstructive sleep apnea patients

Objectives:To evaluate the effects of two different mandibular advancement devices (MADs) on craniofacial characteristics and upper airway dimensions of Chinese adult patients with obstructive sleep apnea (OSA).Materials and Methods:Forty-five patients with OSA were recruited as part of a prospective randomized crossover trial for treatment with two different MADs. Lateral cephalograms were taken, and the Epworth Sleepiness Scale and the Sleep Apnea Quality of Life Index were completed at baseline.Results:The Apnea-Hypoxia Index was highly significantly reduced with the monoblock (P < .001) and significantly reduced with the twin block (P < .01). The monoblock demonstrated a superior result than the twin block (P < .05). A significant reduction was found in the distances between the hyoid bone to retrognathia (monoblock, P < .01; twin block, P < .001) as well as the distance between the hyoid bone and mandibular plane angle (P < .001). Furthermore, soft palate length increased significantly (P < .05) with both MADs. However, the changes did not differ in favor of either MAD.Conclusion:Monoblock was the better MAD to improve OSA severity. No difference could be found in changes of subjective OSA indicators. Significant but similar cephalometric changes were observed, indicating both MADs alter the position of the surrounding musculature and improve upper airway patency. Therefore, the different design features of the MADs suggest an impact on some OSA indicators.     

Assessment of changes in the nasal airway after nonsurgical miniscrew-assisted rapid maxillary expansion in young adults

Objectives:To evaluate changes in the volume and cross-sectional area of the nasal airway before and 1 year after nonsurgical miniscrew-assisted rapid maxillary expansion (MARME) in young adults.Materials and Methods:Fourteen patients (mean age, 22.7 years; 10 women, four men) with a transverse discrepancy who underwent cone beam computed tomography before (T0), immediately after (T1), and 1 year after (T2) expansion were retrospectively included in this study. The volume of the nasal cavity and nasopharynx and the cross-sectional area of the anterior, middle, and posterior segments of the nasal airway were measured and compared among the three timepoints using paired t-tests.Results:The volume of the nasal cavity showed a significant increase at T1 and T2 (P < .05), while that of the nasopharynx increased only at T2 (P < .05). The anterior and middle cross-sectional areas significantly increased at T1 and T2 (P < .05), while the posterior cross-sectional area showed no significant change throughout the observation period (P > .05).Conclusions:The results demonstrate that the volume and cross-sectional area of the nasal cavity increased after MARME and were maintained at 1 year after expansion. Therefore, MARME may be helpful in expanding the nasal airway.     

Tooth-borne vs bone-borne rapid maxillary expanders in late adolescence

Objective:To evaluate the immediate effects of rapid maxillary expansion (RME) on the transverse skeletal and dentoalveolar changes with bone-borne (C-expander) and tooth-borne type expanders using cone-beam computed tomography (CBCT) in late adolescents.Materials and Methods:A sample of 28 female late-adolescent patients was divided into two groups according to the type of expander: bone-borne (C-expander, n  =  15, age  =  18.1 ± 4.4 years) and tooth-borne (hyrax, bands on premolars and molars, n  =  13, age  =  17.4 ± 3.4 years). CBCT scans were taken at 0.2-mm voxel size before treatment (T1) and 3 months after RME (T2). Transverse skeletal and dental expansion, alveolar inclination, tooth axis, vertical height of tooth, and buccal dehiscence were evaluated on maxillary premolars and molars. Paired t-test, independent t-test, one-way analysis of variance, and Scheffé post hoc analysis were performed.Results:The C-expander group produced greater skeletal expansion, except in the region of the first premolar (P < .05 or < .01), which showed slight buccal tipping of the alveolar bone. The Hyrax group had more buccal tipping of the alveolar bone and the tooth axes, except in the region of the second molar (P < .05 or < .01 or < .001). Dental expansion at the apex level was similar in the banded teeth (the first premolar and the first molar). Vertical height changes were apparent on the second premolar in the hyrax group (P < .05 or < .01). Significant buccal dehiscence occurred at the first premolar in the hyrax group (P < .01 or < .001). There were no significant differences between tooth types for any variables in the C-expander group.Conclusions:For patients in late adolescence, bone-borne expanders produced greater orthopedic effects and fewer dentoalveolar side effects compared to the hyrax expanders.     

Three-dimensional analyses of palatal morphology and its relation to upper airway area in obstructive sleep apnea

Objective:To evaluate the relationship between palatal morphology and pharyngeal airway morphology in patients who have obstructive sleep apnea (OSA) and compare with a nonsnoring and nonapneic control group.Materials and Methods:Three-dimensional maxillary dental cast measurements from 25 OSA patients (6 women, 19 men) with a mean age of 41.5 (4.8) years, and 25 control group participants (14 women, 11 men) without any symptom of OSA with a mean age of 38.3 (3.7) were correlated with an analysis of pharyngeal area evaluated with lateral cephalograms. Intermolar and intercanine widths and palatal volumes were calculated on the dental casts, and the upper airway area measurements were performed on lateral cephalograms.Results:OSA patients had smaller oropharyngeal volume and upper airway when compared with controls (P < .001). Palatal area measurements were significantly smaller in OSA (P < .001). OSA patients had significantly narrower maxilla with smaller intermolar and intercanine widths (P < .001). A positive correlation was found between the palatal morphology and pharyngeal dimensions.Conclusions:A significant correlation exists between palatal morphology and pharyngeal airway.     

Effects of severity and location of nonsyndromic hypodontia on craniofacial morphology

Objective:To evaluate the effects of severity and location of nonsyndromic hypodontia on craniofacial morphology.Materials and Methods:A total of 154 patients with at least two or more congenitally missing teeth were selected and divided into two groups (group I [mild]: patients with two to five missing teeth; group II [severe]: patients with six or more missing teeth). The patients with hypodontia were divided into three groups according to the location of missing teeth in the dental arches (anterior, posterior, and both anterior and posterior) and location of missing teeth between the jaws (maxilla, mandible, and both maxilla and mandible). Fifty Class I patients without any missing teeth served as the control group. Twenty-one measurements were performed on lateral cephalograms. Intergroup differences for the severity and location of hypodontia were analyzed using analysis of variance (ANOVA) and post-hoc Tukey tests.Results:Significant decreases were found in mandibular plane angles (P < .05), upper and lower incisor measurements (P < .05), anterior (P < .001) and posterior (P < .05) face heights, and ramus height (P < .01), as well as a significant increase in the soft tissue convexity angle (P < .05) among the hypodontia groups and control group. These differences were more excessive in the severe hypodontia group. Upper lip-E plane measurements were significantly longer in the mandible group than in the maxilla group (P < .01).Conclusions:Patients with congenitally missing teeth have different craniofacial morphologies. The severity and location of missing teeth have a significant effect.     

Comparison of pharyngeal airway volume among different vertical skeletal patterns: A cone-beam computed tomography study

Objective:To test the null hypothesis that there are no significant differences in pharyngeal airway volumes among adult patients with different vertical skeletal patterns and a clinically normal sagittal skeletal pattern using cone-beam computed tomography (CBCT).Material and Methods:The study sample consisted of 100 adult patients (45 men and 55 women; mean age  =  24.0 ± 5.3 years) with a normal sagittal skeletal pattern divided into three groups according to the vertical skeletal patterns: high angle (32 patients: 15 women and 17 men), low angle (34 patients: 14 women and 20 men), and normal angle (34 patients: 16 women and 18 men) groups. Nasopharyngeal, oropharyngeal, and total airway volumes of patients in all vertical groups were calculated. Group differences were analyzed using one-way analysis of variance and post hoc Tukey tests.Results:Nasopharyngeal airway volume in the high-angle group (mean  =  6067.9 ± 1693.9 mm³) was significantly lower than that of the low- and normal-angle groups (P < .01). Oropharyngeal airway volume was highest in the low-angle group (mean  =  15,957.6 ± 6817.2 mm³) and significantly decreased in the control (mean  =  11,826.1 ± 4831.9 mm³; P  =  .008) and high angle (mean  =  10,869.1 ± 4084.1 mm³; P  =  .001) groups. Total airway volume was highest in the low-angle group (mean  =  24,261.6 ± 8470.1 mm³) and lowest in the high-angle group (mean  =  16,937.0 ± 5027.4 mm³; P < .001).Conclusion:The null hypothesis was rejected. Significant differences were found in pharyngeal airway volumes among different skeletal vertical patterns.     

In vitro and in vivo mechanical stability of orthodontic mini-implants: Effect of sandblasted,large-grit,and anodic-oxidation vs sandblasted,large-grit,and acid-etching

Objective:To compare in vivo and in vitro mechanical stability of orthodontic mini-implants (OMIs) treated with a sandblasted, large-grit, and anodic-oxidation (SLAO) method vs those treated with a sandblasted, large-grit, and acid-etching (SLA) method.Materials and Methods:Fifty-four titanium OMIs (cylindrical shape, drill-free type; diameter  =  1.45 mm, length  =  8 mm, Biomaterials Korea Inc, Seoul, Korea) were allocated into control, SLA, and SLAO groups (N  =  12 for in vivo and N  =  6 for in vitro studies per group). In vitro study was carried out on a polyurethane foam bone block (Sawbones, Pacific Research Laboratories Inc, Vashon, Wash). In vivo study was performed in the tibias of Beagles (6 males, age  =  1 year, weight  =  10 to 13 kg; OMIs were removed at 8 weeks after installation). For insertion and removal of OMIs, the speed and maximum torque of the surgical engine were set to 30 rpm and 40 Ncm, respectively. Maximum torque (MT), total energy (TE), and near peak energy (NPE) during the insertion and removal procedures were statistically analyzed.Results:In the in vitro study, although the control group had a higher insertion MT value than the SLA and SLAO groups (P < .01), no differences in insertion TE and NPE or in any of the removal variables were noted among the three groups. In the in vivo study, the control group exhibited higher values for all insertion variables compared with the SLA and SLAO groups (MT, P < .001; TE, P < .01; NPE, P < .001). Although no difference in removal TE and removal NPE was noted among the three groups, the SLAO group presented with a higher removal MT than the SLA and control groups (P < .001).Conclusions:SLAO treatment may be an effective tool in reducing insertion damage to surrounding tissue and improving the mechanical stability of OMIs.     

Masseter muscle changes following orthognathic surgery: A long-term three-dimensional computed tomography follow-up

Objective:To evaluate the long-term changes of masseter muscle morphology in skeletal Class III patients with facial asymmetry following two-jaw orthognathic surgery (Le Fort I osteotomy + intraoral vertical ramus osteotomy).Materials and Methods:Using computed tomography (CT), a longitudinal study was conducted on 17 skeletal Class III patients with facial asymmetry. Measurements from the reconstructed three-dimensional (3D) CT images were compared from T1 (before surgery), T2 (1 year after surgery), and T3 (4 years after surgery). The maximum cross-sectional area (CSA), orientation, thickness, and width of the masseter muscle were measured on both the deviated and nondeviated sides. The control group included 17 volunteers with skeletal and dental Class I relationships without dentofacial deformities.Results:At T1, there were no significant differences in CSA, thickness, or width of masseter muscle between the deviated and nondeviated sides. Masseter muscle orientation was significantly more vertical on the nondeviated side than on the deviated side at T1 (P < .01); no significant bilateral differences were noted at T2 and T3. At T1, masseter muscle measurements were significantly lower than controls (P < .01). During T1–T3, a significant increase was noted in CSA, thickness, and width (P < .01) of masseter muscle. At T3, no significant difference was noted between the study and control groups.Conclusion:After surgery, the masseter muscle measurements of skeletal Class III asymmetry patients showed no significant differences compared with the control group within the 4-year follow-up period, indicating adaptation to the new skeletal environments and increased functional demand.     

Skeletal and dental effects of molar distalization using a modified palatal anchorage plate in adolescents

Objective:To evaluate and compare skeletal effects and the amount of molar distalization in maxilla using modified palatal anchorage plate (MPAP) vs headgear appliances in adolescent patients.Materials and Methods:Pre- and posttreatment lateral cephalograms of 45 Class II malocclusion patients were analyzed; 24 were treated with MPAP appliances (age, 12.4 years) and 21 with headgear (age, 12.1 years). Fixed orthodontic treatment started with the distalization process in both groups. Thirty-two variables were measured and compared between both groups using multivariate analysis of covariates.Results:There was no significant main effect of the appliance type on the treatment results (P  =  .063). Also, there was no significant main effect of the appliance type on both pre- and posttreatment comparisons (P  =  .0198 and .135, respectively). The MPAP and headgear groups showed significant distalization of maxillary first molars (3.06 ± 0.54 mm and 1.8 ± 0.58 mm, respectively; P < .001). Sagittal skeletal maxillomandibular differences were improved after treatment (P < .001), with no significant differences between the two groups. No significant difference in treatment duration was found between the groups.Conclusions:The MPAP showed a significant skeletal effect on the maxilla. Both MPAP and headgear resulted in distalization of maxillary first molars. Therefore, it is recommended that clinicians consider the application of MPAP, especially in noncompliant Class II patients.