Condylar response to functional therapy with Twin-Block as shown by cone-beam computed tomography

Objective:To evaluate the condylar changes through cone-beam computed tomography (CBCT) images in patients treated with Twin-Block functional appliance.Materials and Methods:In this retrospective study, CBCT images of 30 patients who were treated with the Twin-Block appliance were used. Mandible was segmented and pretreatment and posttreatment (T0 and T1) condylar volume was compared. The angle between sella-nasion-Point A (SNA), angle between sella-nasion-Point B (SNB), angle between Point A-nasion-Point B (ANB), midfacial length (Co-A), mandibular length (Co-Gn), and the distances from right condylion to left condylion (Co_R-Co_L) were also measured on three-dimensional images. Differences were analyzed with Wilcoxon signed rank tests, and Mann-Whitney U-tests were used to compare the scores of male and female participants. Significance was set at P < .05.Results:In this study, a decrease in SNA and ANB (P < .05 and P < .01, respectively) and an increase in SNB (P < .01) were found. Additionally, Co_R-Co_L, Co-Gn, and condylar volume increased at both the left and right sides (P < .01). However, increase at Co-A was not statistically significant (P > .05). Comparison of differences by sex was not statistically significant for all measurements (P > .05).Conclusion:Twin-Block appliance increases condylar volume, mandibular length, and intercondylar distance by stimulating growth of condyle in an upward and backward direction.     

Effects of growth hormone and functional appliance on mandibular growth in an adolescent rat model

Objectives:To investigate the individual and synergistic effects of growth hormone (GH) and functional appliance (FA) on mandibular growth in an adolescent rat model.Materials and Methods:Forty adolescent (6-week-old) female Wistar rats were randomly divided into four groups (10 rats in each group). The control group received a sham treatment (intra-abdominal injection of phosphate-buffered saline), the GH group received an intra-abdominal injection of recombinant human growth hormone, the FA group was treated with a mandibular advancement device, and the GH+FA group received both the GH and FA treatments. The amount of mandibular growth in each group was measured quantitatively using cone-bean computed tomography. The growth of condylar cartilage and expression of matrix metalloproteinases–1 and –13 (MMP-1 and MMP-13) and type II and X collagen (Col II and Col X) were assessed using histological staining and immunostaining techniques.Results:After 4 weeks, there was significant mandibular growth in the FA group compared with the control group (P < .05). The GH+FA group had significantly greater mandibular length, thickness of condylar cartilage, and expression of MMP-1, MMP-13, Col II, and Col X in the cartilage than the other groups (P < .05). The GH+FA group and GH group had significantly greater weight than the FA and control groups (P < .05).Conclusions:The FA as well as GH+FA stimulated mandibular growth in adolescent rats.     

Correlation between panoramic radiography and cone-beam computed tomography in assessing maxillary impacted canines

Objective:To determine the usefulness of panoramic radiographs in determining the labio-palatal position of maxillary impacted canines (MICs) and root resorption of permanent incisors on cone-beam computed tomography (CBCT) in correlation with the mesiodistal position of MICs on panoramic radiographs.Materials and Methods:This retrospective radiographic study reviewed 64 patients with 86 MICs. Subjects were divided into two groups: group I (<15 years old) and group II (>15 years old). The mesiodistal position of the MICs'' cusp tips was classified into five sectors on panoramic radiographs. The labio-palatal position of the MICs and root resorption of permanent incisors were evaluated on CBCT. The statistical correlation between panoramic radiograph and CBCT results was examined using the chi-square test and the Fisher exact test.Results:Most of the positions of MICs were palatal (67%), followed by labial (28%) and mid-alveolus (5%; P < .05). Labial positioned MICs on CBCT were more frequent in panoramic sector 1, mid-alveolus MICs were more common in sector 2, and palatally positioned MICs were more frequent in sectors 3, 4, and 5. The association between sectors of the MICs on panoramic images and the labio-palatal position of the MICs on CBCT was statistically significant (P < .001). Root resorption of adjacent incisors showed a significant difference according to sector location (P < .01) and was mainly found in sectors 4 and 5.Conclusions:This study showed that the labio-palatal position of MICs and resorption of permanent incisors might be predicted using sector location on panoramic radiographs.     

Alterations of panoramic radiomorphometric indices in children and adolescents with beta-thalassemia major: A fractal analysis study

Background Beta-thalassemia major is an inherited disorder that can cause bone deformity and loss of bone mineral density. The objective of this study is to evaluate the cortical and trabecular mandibular bone morphology of children and adolescents who have beta-thalassemia major (ß-TM) using a fractal dimension (FD) analysis and different panoramic radiomorphometric indices with digital panoramic radiographic images (DPRIs).Material and Methods The study included 80 patients (with 40 patients each of ß-TM and control). The mandibular cortical width (MCW), panoramic mandibular index (PMI), mandibular cortical index (MCI), and simple visual estimation (SVE) were evaluated, and an FD analysis of five regions of interest (ROIs) (ROI 1: in basal cortical bone; ROI 2: in premolar region; ROI 3: in molar region; ROI 4: in angulus mandible and ROI 5: in condyle region) was obtained in all DPRIs. Quantitative variables were analyzed using the student’s t-test , Kruskal–Wallis and Mann-Whitney U tests.Results When the ß-TM groups were compared with controls, there were no statistically significant differences found in the mean FD values, the ROIs of the trabecular bone, or the SVE. There was a significant correlation in the mean MCW, PMI, ROI of cortical bone (ROI 1), and MCI between ß-TM and control groups (p < 0.001, p < 0.001, p = 0.047, and p = 0.046, respectively). The mean MCW values correlated with the SVE in both the ß-TM and control groups (p = 0.031 and p < 0.001, respectively). While the mean MCW values correlated with the MCI (p = 0.04) in the control group, the mean MCW values were not correlated with the MCI (p = 0.493) in ß-TM group.Conclusions The current study revealed lower MCW and PMI values in the ß-TM group. While the mean FD values of trabecular bone is similar to the control groups, the mean FD value is lower in cortical bone in the ß-TM group. MCW, PMI, FD of cortical bone and MCI may be key indicators in individuals with beta-thalassemia major. Key words:Beta-thalassemia major, fractals, panoramic radiography.     

Mandibular vertical asymmetry in adult orthodontic patients with different vertical growth patterns: A cone beam computed tomography study

Objective:To evaluate condylar and ramal vertical asymmetry in adult orthodontic patients with different vertical growth patterns and a clinically normal sagittal skeletal pattern using cone-beam computed tomography (CBCT).Materials and Methods:The study sample consisted of 101 adult orthodontic patients (48 men and 53 women) divided into three groups according to their vertical growth patterns: high- (33 patients; mean age, 25.06 ± 6.05 years), low- (34 patients; mean age, 24.88 ± 5.22 years), and normal-angle (34 patients; mean age, 24.14 ± 4.26 years) groups. Condylar, ramal, condylar plus ramal height, and index measurements were performed using CBCT images and analyzed using one-way analysis of variance and post hoc Tukey tests.Results:There was no statistically significant difference in height measurements between right and left sides in each group, except a slight difference of approximately 0.5 mm for condylar height (CH) in the low-angle group (P < .05). No statistically significant gender differences were found for the values (P > .05). In the high-angle group, the ramal height (RH) and condylar plus ramal height (CH + RH) on both sides were found to be less than those of the low- (P < .001) and normal-angle groups (P < .017 and P > .017, respectively), and the asymmetry index values were slightly higher than those of the low- and normal-angle groups (P > .05).Conclusions:The high-angle group showed statistically significantly smaller values of RH and CH + RH on both sides and statistically insignificantly higher asymmetry index values than the low- and normal-angle groups.     

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.     

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.     

Periodontal consequences of mandibular incisor proclination during presurgical orthodontic treatment in Class III malocclusion patients

Objective:To test the hypothesis that periodontal changes are similar between proclined and minimal-changed mandibular incisor position groups during presurgical orthodontic treatment for Class III orthognathic surgery.Materials and Methods:The following measurements were performed before and after presurgical orthodontic treatment of 75 patients (proclination group, 39 subjects; minimal-change group, 36 subjects): clinical crown length, sulcus and bone probing depths, and width of attached gingiva from clinical examination; infradentale-to-MP (perpendicular distance of infradentale to mandibular plane) from examination of lateral cephalograms; and the distance between the cementoenamel junction and alveolar crest from examination of periapical radiographs. Data were compared between the two groups, and a regression analysis was performed to investigate factors affecting the periodontal changes.Results:In both groups, clinical crown length and bone probing depth increased during presurgical orthodontics (P < .05). Infradentale-to-MP and the width of attached gingiva decreased more in the proclination group than in the minimal-change group (P < .05). Proclination and protrusion of the mandibular incisors, and treatment duration affected the periodontal changes.Conclusions:The null hypothesis was rejected. Proclination of the mandibular incisors for decompensation in Class III surgery patients seems to result in labial alveolar bone recession and a decrease in width of attached gingiva. However, the amount of the periodontal recession appeared to be clinically insignificant.     

Is there an asymmetry of the condylar and coronoid processes of the mandible in individuals with unilateral crossbite?

Objectives:To evaluate if there is a true skeletal asymmetry of the condylar and coronoid processes of the mandible in growing individuals with unilateral posterior crossbite (UPC) either functional or not.Materials and Methods:This cross-sectional study screened a total of 1120 cone beam computed tomography (CBCT) scans based on inclusion and exclusion criteria. The final sample comprised 20 CBCT images of individuals with UPC and 19 CBCT images of individuals without transverse malocclusion. The lengths of the condylar and coronoid processes were measured to evaluate asymmetry, as well as the magnitude of the mandibular lateral deviation in the UPC group.Results:There was a significant difference between the lengths of the affected and nonaffected sides of the coronoid processes in the UPC group (P < .01). The same was not observed in the condyle in the UPC group (P > .05). There were no significant differences between the groups (P > .05).Conclusions:Although no differences in the condyle were observed, the coronoid process was asymmetric in individuals with UPC. However, this asymmetry was not considered to be clinically significant.     

Evaluation of characteristics of the craniofacial complex and dental maturity in girls with central precocious puberty

Objectives:To identify unique characteristics of the craniofacial complex and dental maturity in girls with central precocious puberty (CPP).Materials and Methods:This study included 34 Korean girls with idiopathic CPP (mean age, 8.6 ± .5 years) and 28 normal healthy girls of the same chronological age. An initial evaluation of the growth pattern of the craniofacial complex and dental maturity was conducted by analyzing lateral cephalometric and panoramic radiographs.Results:The mandibular ramus height (44.4 ± 4.1 mm) and total mandibular length (10.8 ± 4.3 mm) (P = .004 and .021, respectively) were greater and the lower anterior facial height was lesser (63.2 ± 2.4 mm) (P = .040) in the CPP group than in the reference group. In addition, the gonial angle (12.9 ± 6.1°; P = .045) and the mandibular plane angle (34.9 ± 4.8°; P = .012) were smaller in girls with CPP than in normal healthy girls. All the mandibular teeth were more mature in girls with CPP (P < .001). A strong positive correlation was observed between the mandibular tooth formation stages and the presence of CPP in girls (r = .756 to .957; P < .001).Conclusions:CPP had an effect on the anteroposterior growth of the mandible in the craniofacial complex and the rotation of the mandibular plane angle. Early maturation of the mandibular teeth was observed in girls with CPP.     

Three-dimensional soft tissue evaluation after rapid maxillary expansion and mandibular midline distraction osteogenesis

ObjectivesTo evaluate the effects of rapid maxillary expansion (RME) and mandibular midline distraction osteogenesis (MMDO) on facial soft tissues using three-dimensional (3D) images.Materials and MethodsA total of 20 patients (average age 15.86 ± 2.17 years) were treated with RME and MMDO using tooth-borne distractors. Three-dimensional photographs of each patient were taken with a stereophotogrammetry system at baseline (T0), at the end of the distraction period (T1), and at the end of the consolidation period (T2). All data were analyzed using a dependent-samples t-test at a significance level of 5%.ResultsTotal and lower face height increased after MMDO (P < .05). Nasal and mouth width increased after RME as compared with baseline (P < .05). The labiomental angle increased at T1 and decreased at T2 (P < .05). After MMDO, the convexity angle increased while the mandibular angle decreased (P < .05). Upper and lower lip angles increased after RME (P < .05). The distance from the lower lip to the E plane increased after MMDO and decreased after RME (P < .05).ConclusionsThe MMDO and RME procedures provide an efficient nonextraction treatment alternative for transverse maxillomandibular deficiency. MMDO may improve the facial soft tissue profile in the transverse and vertical axis of the mandibular region.     

Soft tissue airway dimensions and craniocervical posture in subjects with different growth patterns

Objective:To compare the dimensions of the nasopharynx and oropharynx of subjects with different growth patterns and to determine whether any correlation exists with their craniocervical posture.Materials and Methods:Cephalometric radiograph of 60 subjects (16–25 years old), taken in natural head position, were divided into three groups according to the mandibular plane angle: hypodivergent (SN/MP <26°), normodivergent (SN/MP 26°–38°), and hyperdivergent (SN/MP <38°). Correlations were calculated between nasopharyngeal area, oropharyngeal area, and craniocervical posture. Continuous variables were compared by one-way analysis of variance, and the significance of mean difference between the groups was done by the Tukey post hoc test. A value of P < .05 was considered statistically significant.Results:Patients in the hyperdivergent group were found to have significantly smaller nasopharyngeal and oropharyngeal areas than the other groups (P < .001 and P < .05, respectively). Similarly, the oropharyngeal area in the normodivergent group was significantly smaller than that in the hypodivergent group (P < .05). However, no significant differences were found in the nasopharyngeal area between the hypodivergent and normodivergent groups and between the hyperdivergent and normodivergent groups (P > .05). Reduced pharyngeal airways were typically seen in patients with a large craniocervical angle and a large mandibular inclination.Conclusions:Smaller nasopharyngeal and oropharyngeal airways were seen in connection with a large craniocervical and a large mandibular inclination. We therefore suggest that the vertical skeletal pattern may be one of the factors that contribute to nasopharyngeal and oropharyngeal obstruction.     

Can modifying shielding,field of view,and exposure settings make the effective dose of a cone-beam computed tomography comparable to traditional radiographs used for orthodontic diagnosis?

ObjectivesTo analyze the effect of changes in exposure settings, field of view (FOV), and shielding on radiation to an adult and child phantom from cone-beam computed tomography (CBCT) imaging compared to panoramic and lateral cephalometric radiographs.Materials and MethodsThe effective dose to an adult and child anthropomorphic phantom by the CS 9300 using various scan protocols was recorded. Absorbed radiation was measured with optically stimulated luminescence dosimeters and effective dose calculated using 2007 International Commission on Radiological Protection tissue weighting factors. Scan protocols included different FOVs, voxel sizes, and standard versus low-dose protocols. Radiation shielding was used when it did not interfere with FOV. Panoramic and lateral cephalometric radiographs were taken with the Orthophos SL.ResultsEven with shielding, smaller FOVs, and increased voxel sizes, the effective dose of standard CBCT scans was higher than panoramic and lateral cephalometric radiographs. A shielded limited FOV standard scan combined with a lateral cephalometric radiograph resulted in a lower dose (P < .001) than a full FOV standard scan. Low-dose shielded scans resulted in significant dose reductions to the adult (P < .05) and child (P < .001) phantoms compared to the respective panoramic and lateral cephalometric radiographs combined. Image quality analysis was not possible with radiation equivalent phantoms.ConclusionsUnlike standard CBCTs, shielded low-dose CBCT protocols in the CS 9300 have lower effective doses than conventional radiographs for adult and child phantoms. If high resolution and cranial base visualization are necessary, combining a shielded LFOV standard exposure with a cephalometric radiograph is recommended.     

Effect of post–orthognathic surgery condylar axis changes on condylar morphology as determined by 3-dimensional surface reconstruction

Objective: To evaluate the effect of postoperative condylar axis changes on mandibular condylar remodeling by comparing the condylar head in three-dimensional (3D) surface reconstructions before and after surgery in skeletal Class III deformities (one-jaw [mandibular setback] or two-jaw surgery), and also to determine the relationship between condylar inward rotation and condylar surface remodeling after orthognathic surgery.Materials and Methods:A retrospective analysis was conducted of 30 patients with skeletal Class III deformities who had received orthognathic surgery. Group 1 underwent one-jaw surgery (10 men, five women, age 22.4 ± 3.3 years), and group 2 underwent two-jaw surgery (10 men, five women, age 22.3 ± 2.2 years). Sixty condyles were reconstructed and superimposed pre- and postoperatively to compare the changes of condylar surfaces. The relation between the condylar axis change and the surface change using the Pearson correlation were investigated from the 3D image software.Results:Condylar surface changes before and after the surgery were significant. The postoperative inward rotation of the condyles was correlated with the average absolute deviation of the condyles, regardless of the surgery type (one- or 2-jaw surgery; r  =  .70, P < .05).Conclusion:After orthognathic surgery, condylar surface changes occurred, and condylar inward rotation was closely related to changes of condylar surface.     

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.     

Comparison of condylar size among different anteroposterior and vertical skeletal patterns using cone-beam computed tomography

Objectives:To compare condylar size among different anteroposterior and vertical skeletal patterns using cone-beam computed tomography (CBCT).Materials and Methods:The study included 166 subjects (61 men, mean age: 27.2 ± 7.6 years; 105 women, mean age: 27.4 ± 9.2 years). The anteroposterior skeletal patterns of the subjects were classified into Classes I (−1° ≤ A point–nasion–B point angle [ANB] < 4°), II (ANB ≥ 4°), and III (ANB < −1°). The vertical skeletal patterns were classified into hypodivergent (mandibular plane [MP] ≤ 23°), normodivergent (23° < MP < 30°), and hyperdivergent (MP ≥ 30°) groups. The condylar length, height, and width were examined using CBCT images. Analysis of covariance was used to compare three condylar size measurements among the three anteroposterior groups and the three vertical groups using sex as a covariate. Both left and right sides were examined. Nine groups were further divided according to the anteroposterior and vertical groups, and two-way analysis of covariance (ANCOVA) was applied to estimate the composite effect of skeletal patterns in both directions.Results:Sex as a covariate showed statistical significance in most examinations. The condylar height on both sides had statistically different anteroposterior skeletal patterns (P < .001). The condylar width on both sides also had statistically different vertical skeletal patterns (P < .001). After adjusting for sex, the condylar height and width on both sides increased from Class II, Class I, and Class III. The condylar width on both sides increased from the hypodivergent group, the normodivergent group, and the hyperdivergent group. No composite effect of skeletal patterns in both directions was observed.Conclusions:Condylar height and width considerably differed among subjects with different anteroposterior or vertical skeletal patterns. The anteroposterior or vertical skeletal patterns independently affected the condylar size.     

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.