Growth Patterns of the Maxillomandibular Complex in Preadolescent Patients With Pierre-Robin Sequence Using Cluster Analysis and Longitudinal Follow-Up Cephalometric Data.

OBJECTIVE: To investigate the growth patterns of the maxillomandibular complex in preadolescent patients with Pierre-Robin sequence (PRS). METHODS: The samples consisted of 20 preadolescent PRS patients who had cleft palate and did not undergo growth-modification therapy or surgical intervention [6 boys and 14 girls; mean age of lateral cephalograms taken, 8.8 y (T1) and 13.7 y (T2)]. According to k-means cluster analysis, four clusters were defined over 3 major groups at T1: (1) Both very retrusive maxilla and mandible group: Cluster-4 [n=4, very large gonial angle, very low facial height ratio (FHR)] and Cluster-1 (n=5, small gonial angle, normal FHR); (2) Retrusive maxilla and very retrusive mandible group (Cluster-3, n=7, normal gonial angle, very low FHR); and (3) Both normal maxilla and mandible group (Cluster-2, n=4, very large gonial angle, low FHR). Seven angular and ratio variables [sella-nasion-A point (SNA), sella-nasion-B point (SNB), A point-nasion-B point (ANB), saddle angle, gonial angle, mandibular-body-length/anterior-cranial-base-length (MBL/ACBL), and FHR] at T1 and T2 and growth change from T1 to T2 were investigated. RESULTS: At T1, SNA, SNB, saddle angle, gonial angle (all P<0.05), and FHR (P<0.01) showed significant difference among 4 clusters. At T2, SNA, SNB and gonial angle (all P<0.05) still showed significant difference among 4 clusters. During T1 to T2, there was no significant change in variables at each cluster except an increase in MBL/ACBL in Cluster-1 and FHR in Cluster-3 (all P<0.05). CONCLUSIONS: Preadolescent PRS patients exhibited diverse skeletal phenotypes at T1, which did not change significantly from their original skeletal patterns by growth during T1 to T2.

Distribution and Phenotype of Goldenhar Syndrome and Its Association With Other Anomalies.

The purpose of this study was to investigate the distribution and phenotype of Goldenhar syndrome (GS) and its association with other anomalies. The samples consisted of 18 GS patients (6 males and 12 females; mean age at investigation, 7.4 ± 4.8 y) who were treated or followed up at the Department of Orthodontics, Seoul National University Dental Hospital between 1999 and 2021. The prevalence of side involvement and degree of mandibular deformity (MD), midface anomalies, and association with other anomalies were evaluated using statistical analysis. The prevalence of unilateral and bilateral MD did not differ (55.6% versus 44.4%). In unilateral MD cases, there was a tendency for higher prevalence of more severe Pruzansky-Kaban types than mild ones (type I, 10%; type IIa, 10%; type IIb, 50%; type III, 30%). Despite hypoplasia of the condyle/ramus complex, compensatory mandibular body growth occurred in 33.3% of GS patients (more severe side in bilateral MD cases, 37.5%, and ipsilateral side in unilateral MD cases, 30%). Class II molar relation was more prevalent than class I and class III molar relations (72.2% versus 11.1% versus 16.7%, P <0.01). Al total of 38.9% of patients had congenitally missing tooth. #7 facial cleft was found in 44.4% of patients. In midface anomalies, ear problem was the most common anomaly, followed by hypoplasia/absence of zygomatic arch and eye problem (88.9% versus 64.3% versus 61.1%, P <0.01). Association with the midface, spine, cardiovascular, and limb anomalies did not differ between unilateral and bilateral MD cases. These results might provide a basic guideline for diagnosis and treatment planning for GS patients.

Classification of Skeletal Phenotypes of Adult Patients With Cleft Skeletal Class III Malocclusion Using Principal Component Analysis and Cluster Analysis.

The purpose of this study was to classify the skeletal phenotypes of adult patients with skeletal class III (C-III) malocclusion and unilateral or bilateral cleft lip and palate using principal component analysis and cluster analysis. The samples consisted of 81 adult C-III patients with cleft lip and palate (CLP) who underwent orthognathic surgery (OGS) or distraction osteogenesis (59 males and 22 females; 50 unilateral cleft lip and palate and 31 bilateral cleft lip and palate; mean age when lateral cephalograms were taken, 22.2±4.6 y). Thirteen angular and one ratio cephalometric variables were measured. Using 4 representative variables obtained from principal component analysis (SNA, SNB, Gonial angle, and Bjork sum), K-means cluster analysis was performed to classify the phenotypes. Then, statistical analysis was conducted to characterize the differences in the variables among the clusters. Five clusters were obtained from 3 groups: severely retrusive maxilla and moderately retrusive mandible group: cluster-1 (23.5%, severely hyperdivergent pattern), cluster-4 (27.2%, moderately hyperdivergent pattern), and cluster-5 (11.1%, normodivergent pattern); moderately retrusive maxilla and normal mandible group: cluster-2 (30.9%, normodivergent pattern); normal maxilla and moderately protrusive mandible group: cluster-3 (7.4%, normodivergent pattern). Although skeletal phenotypes were diverse, distribution of sex and cleft type did not differ among 5 clusters ( P >0.05). Sixty-two percent of cleft patients showed a severely retrusive maxilla and moderately retrusive mandible (cluster-1, cluster-4, and cluster-5), which indicated that these are the main cause of skeletal C-III malocclusion in CLP patients who were treated with OGS. Therefore, it is necessary to consider presurgical orthodontic treatment and surgical planning based on the skeletal phenotypes of CLP patients.

Facial Asymmetry Phenotypes in Adult Patients With Unilateral Cleft Lip and Palate and Skeletal Class III Malocclusion Using Principal Component Analysis and Cluster Analysis.

The purpose of this study was to classify and characterize facial asymmetry (FA) phenotypes in adult patients with unilateral cleft lip and palate (UCLP) and skeletal class III malocclusion. The samples comprised 52 adult UCLP patients (36 men and 16 women; mean age, 22.43 y) who had undergone orthognathic surgery for correction of class III malocclusion. After measurement of 22 cephalometric parameters in posteroanterior cephalograms taken 1 month before orthognathic surgery, principal component analysis was performed to obtain 5 representative parameters [deviation (mm) of ANS (ANS-dev), maxillary central incisor contact point (Mx1-dev), and menton (Me-dev); cant (degree) of the maxillary anterior occlusal plane (MxAntOP-cant) and mandibular border (MnBorder-cant)]. K-means cluster analysis was conducted using these representative parameters. The differences in cephalometric parameters among the clusters were statistically analyzed. The FA phenotypes were classified into 4 types: No-cant-and-No-deviation type (cluster-4, n=16, 30.8%); MxMn-cant-MxMn-dev to the cleft-side type (cluster-3, n=4, 7.7%); Mx-cant-Mn-shift to the cleft-side type (cluster-2, n=15, 28.8%); and Mn-cant-Mn-dev to the noncleft-side type (cluster-1, n=17, 32.7%). Asymmetry in the maxilla and/or mandible were observed in 70% of patients. One third of patients (cluster-2 and cluster-3; sum, 36.5%) exhibited significant cant of MxAntOP induced by cleft and cant or shift of the mandible to the cleft side. Another one third of patients (cluster-1, 32.7%) demonstrated significant deviation and cant of the mandible to the noncleft-side despite cleft in the maxilla. This FA phenotype classification might be a basic guideline for diagnosis and treatment planning for UCLP patients.

Characterization of Spheno-occipital Synchondrosis Fusion From Preadolescents to Young Adults Using Age and Cervical Vertebrae Maturation Index.

The purpose of this study was to characterize the spheno-occipital synchondrosis fusion (SOSF) from preadolescents to young adults. A total of 630 Korean subjects (308 men, 322 women; age range, 6-18 y) were divided into 26 groups according to sex and age. After 3-dimensional computed tomography (CT) images were reoriented using the Frankfort horizontal (FH) plane, mid-sagittal plane, and frontal plane via ON3D software (3DONS), the cervical vertebrae maturation index (CVMI) and SOSF stages were identified using 6-stage and 5-stage scoring systems, respectively. The distributions of stage in each group were statistically investigated. Women showed early appearance and a short range of onset (CVMI stage 2, SOSF stage 2), middle (CVMI stage 4, SOSF stage 3 and stage 4), and completion (CVMI stage 6, SOSF stage 5), indicating rapid skeletal maturation compared with men. In both males and females, there were strong positive correlations between age and CVMI stage (rs=0.902, rs=0.890), between age and SOSF stage (rs=0.887, rs=0.885), and between CVMI and SOSF stages (rs=0.955, rs=0.964) (all P<0.001). The mean ages at SOSF stage 3 and stage 4 (12.7~13.9 y in males and 11.0~12.5 y in females) could be used as indicators of the pubertal growth peak. Regression equations for SOSF stage (y), age (a), and CVMI stage (b) were as follows: y=1.355-(0.133×a)+(0.29007×b)+(0.041×a×b) for males (r2=0.9496); y=1.305-(0.158×a)+(0.455×b)+(0.036×a×b) for females (r2=0.9606). Ordinal logistic regression analyses with the proportional odds model showed that females had more advanced SOSF stages than males (odds ratio: 1.972; 95% CI: 1.063-3.658, P<0.05). Our findings may provide basic references for CVMI and SOSF from preadolescents to young adults.

Association between Condylar Bone Density and Disk Displacement in the Temporomandibular Joint.

Measuring bone density (BD) is a common method of determining bone quality; however, the relationship between condylar BD and the occurrence of temporomandibular joint (TMJ) disorders has not been investigated. To address this knowledge gap, we aimed to investigate condylar BD in terms of TMJ disk displacement (TMJ DD) using computed tomography (CT) and magnetic resonance imaging (MRI). We classified TMJ MRI results according to the position of the disk: normal disk position (Normal), anterior disk displacement with reduction (ADDR), and anterior disk displacement without reduction (ADDNR). After retrospectively evaluating 86 female condyles, we determined the total, cortical, and trabecular BD in the upper-joint portion of the condyle and the whole condyle using CT data. To standardize condylar BD, we calculated the BD ratios by dividing the condylar BD by the cervical axis BD. The Kruskal-Wallis test analyzed the differences in BD measurements in the TMJ DD patient groups and showed significant between-group differences in condylar BD. The total and trabecular BD was significantly higher in ADDNR condyles than in Normal or ADDR condyles (Normal = ADDR < ADDNR). However, there was no significant difference in the cortical BD among the three TMJ DD groups. The BD ratios showed a similar tendency with condylar BD. These results suggest that increased condylar BD - specifically total and trabecular BD - may be significantly associated with ADDNR condyles. Our findings will help clinicians determine the course of treatment for patients with disk-related TMJ disorders.

Effect of Early Spheno-Occipital Synchondrosis Fusion in Preadolescent Patients With Syndromic Craniosynostosis on Craniofacial Skeletal Patterns: A Preliminary Study Using Cephalometric Analysis.

ABSTRACT: The purpose of this study was to investigate the effects of early spheno-occipital synchondrosis (SOS) fusion in preadolescent patients with syndromic craniosynostosis (SC) on the craniofacial skeletal patterns. Twenty preadolescent SC patients were divided into the fused SOS (FS, n = 10; 8 Crouzon and 2 Apert) and not-fused SOS groups (NFS, n = 10; 9 Crouzon and 1 Apert). Lateral cephalograms (mean age: 9.60 years, cervical vertebral maturation index: stage I and II) were used to investigate the skeletal sagittal (ANB) and vertical patterns (SN-GoMe), upward inclination of the anterior cranial base (ACB; SN-FH), degree of midface hypoplasia (MH, SNA), retrusive position of orbitale (SNO), and forward position of the condyle in relation to sella (saddle angle). Using the ordinal values calculated by ethnic norm (criteria: moderate, over ±1 standard deviation, severe, over ±2 standard deviation), statistical analysis was performed. The FS group showed a higher percentage of severe MH than the NFS group (70% versus 10%, P < 0.05). Although the 2 groups did not differ in the distribution of ANB, SN-GoMe, saddle angle, and SN-FH (all P > 0.05), the FS group showed relatively higher percentages of severe Class III (100% versus 70%), severe hyper-divergent pattern (40% versus 10%), severely forward condyle position (30% versus 0%), and moderate and severe upward anterior cranial base inclination (90% versus 50%) than the NFS group. However, the 2 groups exhibited the same distribution of moderately and severely retrusive orbitale position ([50%, 20%], P > 0.05). Early SOS fusion in preadolescent SC patients might not be related to retrusive orbitale position, but to severe MH.

Characterization of Treatment Modalities for Patients With Syndromic Craniosynostosis in Relation to Degree of Midface Hypoplasia and Patient's Age Using Longitudinal Follow-Up Data.

ABSTRACT: The purpose of this study was to investigate the type and frequency of use of treatment modalities (Tx-Mods) in patients with syndromic craniosynostosis (SC) using longitudinal follow-up data. A total of 28 patients with SC (24 Crouzon, 2 Apert, and 2 Antley-Bixler syndromes), who were treated at the Department of Orthodontics, Seoul National University Dental Hospital, Seoul, South Korea between 1998 and 2020, was included. According to the degree of midface hypoplasia (MH) at the initial visit (T1), the patients were divided into the mild-MH (78°≤SNA < 80°, n = 8), moderate-MH (76≤SNA < 78°, n = 7), and severe-MH (SNA < 76°, n = 13) groups. T1-age and Tx-Mods, including cal-varial surgery (CALS), orthopedic treatment (OPT), fixed orthodontic treatment, and midface advancement surgery in childhood (MAS-child) and adulthood (MAS-adult), were investigated. Complexity of MAS-adult was graded as follows: 0, no surgery; 1, orthognathic surgery; 2, distraction osteogenesis (DOG); 3, combination of distraction osteogenesis and orthognathic surgery. Then, statistical analysis was performed. Percentage distribution of Tx-Mods was 71.4% in CALS, 21.4% in MAS-child, 42.9% in OPT, 100% in fixed orthodontic treatment, and 89.3% in MAS-adult. 92.9% of patients underwent MAS more than once. The number of MAS increased according to the severity of MH ( P < 0.05). The complexity of MAS-adult increased as T1-age and severity of MH increased (all P < 0.05); whereas it decreased when CALS and OPT were performed (all P < 0.05). However, MAS in childhood did not guarantee the avoidance of additional MAS in adulthood ( P > 0.05). These findings may be used as basic guidelines for successful treatment planning and prognosis prediction in patients with SC.

Effect of print angulation on the accuracy and precision of 3D-printed orthodontic retainers.

INTRODUCTION: The study aimed to (1) compare the accuracy and precision of 3-dimensional (3D) printed retainers at various angulations and (2) evaluate the effect of angulation on printing time and the amount of resin consumed. METHODS: Using a stereolithography 3D printer, 60 clear retainers were printed at 5 angulations (n = 12, each): 15°, 30°, 45°, 60°, and 90°. Samples for each group were randomly printed in a batch of 6 retainers at all print angulations as print 1 and print 2 cycles. Digital images of the original and printed samples were superimposed. Discrepancies on 8 landmarks were measured by 2 independent examiners, and 0.25 mm was set as the clinically acceptable threshold to determine the accuracy of the retainers. RESULTS: Deviations ranged from 0.074 mm to 0.225 mm from the reference retainer at the cusp tips and incisal edges at all angulations, falling within the threshold of clinical acceptance. However, smooth surface measurements with deviations up to 0.480 mm were deemed clinically not acceptable. Three-dimensional printing at 15° was estimated to be the most time-efficient, whereas 3D printing at 45° was shown to be the most cost-effective setting. CONCLUSIONS: Three-dimensional printed retainers, using a stereolithography printer, were found to be accurate within 0.25 mm at all print angulations at the cusp tips and incisal edges compared with the digital reference file. Smooth facial surfaces did not meet clinical acceptability. Print angulations were shown to affect the cost and amount of resin used.

Comparison of 3-dimensional printing technologies on the precision, trueness, and accuracy of printed retainers.

INTRODUCTION: This study aimed to evaluate the differences in the precision, trueness, and accuracy of 3-dimensional (3D) printed clear orthodontic retainers fabricated using printer systems with different printing technologies. METHODS: Retainers (n = 15) were 3D printed using 4 different printers: stereolithography (SLA), digital light processing (DLP), continuous DLP, and polyjet photopolymer (PPP) printers. Printed retainers were transformed into a digital image through a cone-beam computed tomography scan and compared with the original image using 3D superimposition analysis software. At previously chosen landmarks (R6, L6, R3, L3, R1, and L1), intaglio surfaces of the retainers were compared to that of the reference model. The intercanine and the intermolar width measurements were also assessed. A discrepancy of up to 0.25 mm between the printed retainer and the reference retainer intaglio surfaces indicated accuracy and clinical acceptability. Precision and trueness were also determined. Root mean square and percent of points within the tolerance level were calculated for precision and trueness for each retainer. Statistical significance was set at P <0.05. RESULTS: Interrater correlation coefficient indicated good agreement. Statistically significant differences were found between printer types among the 6 landmarks and the arch width measurements. When evaluating tolerance level and root mean square, statistically significant differences in median precision and trueness among each printer type were found. CONCLUSION: Retainers fabricated by SLA, DLP, continuous DLP, and PPP technologies were shown to be clinically acceptable and accurate compared to the standard reference file. Based on both high precision and trueness, SLA and PPP printers yielded the most accurate retainers.

Characterization of Phenotypes and Treatment Modalities in Patients With Treacher-Collins Syndrome.

ABSTRACT: The purpose of this study was to investigate the phenotypes and treatment modalities (Tx-Mod) in patients with Treacher-Collins syndrome (TCS) using a TCS severity index (TSI). The sample consisted of 14 Korean TCS patients treated at the Department of Orthodontics, Seoul National University Dental Hospital during 1998 to 2019. The TSI was calculated by adding the scores from the number of deformity-involved midface structures (eye, ear, zygoma) and the degree of mandibular hypoplasia (Pruzansky-Kaban type, gonial angle, Sella-Nasion-B point angle). The deformity-involved midface structure, degree of mandibular hypoplasia, oral manifestations, dental phenotypes, and Tx-Mod types were investigated using descriptive statistics. The TSI classified the subjects into 2 mild, 6 moderate, and 6 severe cases. The severity of ear and zygoma deformities, degree of condylar hypoplasia (Pruzansky-Kaban type), clockwise-rotated morphology (gonial angle) and retrusive position (Sella-Nasion-B point angle) of the mandible, and frequency of oral/craniofacial cleft, openbite, congenitally missing tooth and impacted tooth showed a tendency of increase from mild to severe TCS cases. After growth observation (78.6%), diverse combinations of Tx-Mods were applied except for functional appliance therapy. Surgical procedures for eye, ear, and zygoma reconstruction were performed on all patients (100%), whereas fixed orthodontic treatment, mandibular distraction osteogenesis, and orthognathic surgery were performed on 50% of patients. Surgical procedure for hearing improvement was the most frequent Tx-Mod (78.6%). The main desires of TCS patients were to obtain the facial esthetics in the midface and to improve hearing function. The TSI might provide a primary data for individualized diagnosis and treatment planning.

Three-Dimensional Facial Soft Tissue Changes After Orthognathic Surgery in Cleft Patients Using Artificial Intelligence-Assisted Landmark Autodigitization.

ABSTRACT: The purpose of this study was to investigate three-dimensional facial soft tissue changes after bimaxillary orthognathic surgery (BOGS) in patients with cleft lip and palate. The samples consisted of 34 Korean young adult patients with skeletal class III malocclusion who underwent BOGS for maxillary advancement/posterior impaction and mandibular setback. They were divided into cleft-class III (C-CIII) group (n = 18) and noncleft-class III (NC-CIII) group (n = 16). Three-dimensional computed tomography images were taken 1 month before (T1) and 3 months after (T2) surgery. After 34 hard/soft tissue landmarks were automatically identified using software, the amount and direction of change in landmarks and the amount of change in 16 soft tissue variables during T1-T2 were calculated. Then, statistical analysis was performed. Compared to NC-CIII group, C-CIII group showed more posteriorly-positioned hard/soft tissue landmarks, larger alar width, alar base width and philtrum width, and more obtuse nasal tip angle at both T1 and T2 stages. C-CIII group exhibited higher soft-to-hard tissue movement ratios at the bottom of the nose (ΔSn/ΔANS, 1.08 versus 0.81) and the upper part of the upper lip (ΔPoint A'/ΔPoint A, 1.08 versus 0.91), but a lower ratio at the lower part of the upper lip (ΔLs'/ΔIs, 0.72 versus 1.01) than NC-CIII group. The number of hard-soft tissue landmarks with high correlation (>0.90) was smaller in C-CIII group than in NC-CIII group (2 versus 6). Scar tissues and abnormal muscles in the nose and upper lip might elicit different responses in the nasolabial soft tissues to BOGS between C-CIII and NC-CIII patients.

Artificial Intelligent Model With Neural Network Machine Learning for the Diagnosis of Orthognathic Surgery.

Diagnosis and treatment planning are the most important steps in the orthognathic surgery for the successful treatment. The purpose of this study was to develop a new artificial intelligent model for surgery/non-surgery decision and extraction determination, and to evaluate the performance of this model. The sample used in this study consisted of 316 patients in total. Of the total sample, 160 were planned with surgical treatment and 156 were planned with non-surgical treatment. The input values of artificial neural network were obtained from 12 measurement values of the lateral cephalogram and 6 additional indexes. The artificial intelligent model of machine learning consisted of 2-layer neural network with one hidden layer. The learning was carried out in 3 stages, and 4 best performing models were adopted. Using these models, decision-making success rates of surgery/non-surgery, surgery type, and extraction/non-extraction were calculated. The final diagnosis success rate was calculated by comparing the actual diagnosis with the diagnosis obtained by the artificial intelligent model. The success rate of the model showed 96% for the diagnosis of surgery/non-surgery decision, and showed 91% for the detailed diagnosis of surgery type and extraction decision. This study suggests the artificial intelligent model using neural network machine learning could be applied for the diagnosis of orthognathic surgery cases.

What Are the Contributing Factors for Postsurgical Relapse After Two-Jaw Surgery in Patients With Cleft Lip and Palate.

The purpose of this study was to investigate the amount and pattern of postsurgical relapse after 2-jaw surgery in cleft lip and palate patients in terms of the sagittal and vertical aspects. The samples consisted of 21 adult patients who had the similar initial skeletodental pattern before surgery and underwent 2-jaw surgery. They were divided into high relapse (n = 11) and low relapse groups (n = 10) (criteria, 30% forward relapse of the B point). After the cephalometric variables of cephalograms taken at 1 month before surgery (T0), immediately after surgery (T1), and at least 1 year after surgery (T2) were measured, the Wilcoxon test, Mann-Whitney U test, and Pearson correlation test were performed for statistical analysis. When compared with the low relapse group, the high relapse group exhibited significant counterclockwise rotation of the distal segment of the mandible resulting in more forward movement of the mandible and significant labioversion of the maxillary incisors during T1-T2. The amount of postsurgical relapse of the mandible had a positive relationship with the amounts of setback and clockwise rotation of the mandible with surgery. In addition, the more decrease in overbite through surgery occurred, the more relapse (forward movement of the mandible) produced. Therefore, for the prevention of significant postsurgical relapse of the mandible in cleft patients, it is necessary to reduce unnecessary clockwise rotation of the mandible and to increase the vertical stability of maxilla during orthognathic surgery.

Effect of Secondary Alveolar Bone Grafting on the Maxillary Growth: Unilateral Versus Bilateral Cleft Lip and Palate Patients.

The purpose of this study was to investigate the effect of secondary alveolar bone grafting (SABG) on the maxillary growth in patients with unilateral (UCLP) and bilateral cleft lip and palate (BCLP). The samples consisted of 40 Korean boy cleft patients who had the similar initial skeletal characteristics and were treated with the identical treatment protocol. They were divided into UCLP group (N = 25; mean SABG age, 9.9 years; mean follow-up duration, 42.3 months) and BCLP group (N = 15; mean SABG age, 10.2 years; mean follow-up duration, 40.6 months). In the lateral cephalograms taken 1 month before (T1) and at least 2 years after SABG (T2), cephalometric variables were measured. At T1 stage, the 2 groups did not exhibit significant differences in the cephalometric variables except posterior maxillary height (P-HRP) (P < 0.05). At T2 stage, both groups exhibited the reduced sagittal growth (UCLP, ANB, P < 0.001; AB to facial plane angle (AB-FPA), P < 0.01; BCLP, A to N perpendicular, P < 0.05; ANB and AB-FPA, P < 0.001) and the undisturbed vertical growth (A-HRP and P-HRP, all P < 0.001) of the maxilla. During T1 to T2, BCLP group experienced more aggravation of Class III skeletal pattern than UCLP group (ΔAB-FPA, P < 0.05). There, however, were no differences in the amounts of changes in the maxillary vertical position and mandibular plane angulation between the 2 groups. Two-stage SABG procedure subgroup in patients with BCLP demonstrated a more retrusive maxilla compared with 1-stage SABG procedure subgroup (ΔSNA, P < 0.05). Patients with BCLP, especially who underwent 2-stage SABG procedure, might have a possibility of poor sagittal growth of the maxilla compared with patients having UCLP.

Patient's Satisfaction in Skeletal Class III Cases Treated With Two-Jaw Surgery Using Orthognathic Quality of Life Questionnaire: Conventional Three-Stage Method Versus Surgery-First Approach.

OBJECTIVE: To compare the quality of life (QoL) of Class III patients between conventional three-stage method (CTM) and surgery-first approach (SFA) using Orthognathic QoL Questionnaire (OQLQ). MATERIALS AND METHODS: The subjects consisted of 26 Class III patients treated with nonextraction and two-jaw surgery. They were divided into CTM group (N = 15) and SFA group (N = 11). They retrospectively rated the OQLQ scores of 4 domains (social relationship, facial esthetics, function, and awareness of dentofacial deformity) using 0 to 4 scale at initial (T0), just before surgery (T1), 3 month after surgery (T2), and at debonding (T3). Mann-Whitney test and Wilcoxon signed-rank test were performed for statistical analysis. RESULTS: After total OQLQ score of CTM group was deteriorated at T1 stage compared with T0 stage, it was improved at T2 and T3 stages (T0 = 53.9, T1 = 58.1, T2 = 23.5, and T3 = 11.6). Total OQLQ score of SFA group, however, was improved at T2 and T3 stages compared with T0 stage (T0 = 51.6, T2 =  3.1, and T3 = 11.4; T1 was omitted.). Orthognathic QoL Questionnaire scores and their amounts of change did not show any significant difference in each domain and at each stage between 2 groups (T0, T2, T3, ΔT2 - T0, ΔT3 - T2, ΔT3 - T0; all P > 0.05). Both groups showed large change in effect size (ES) of all domains with descending order during T3 - T0: facial esthetics, oral function, social relationship, and awareness of dentofacial deformity (CTM group: -3.97, -3.40, -2.23, -1.25; SFA group: -2.83, -2.33, -1.76, -1.73) CONCLUSIONS: SFA might have an advantage over CTM group in terms of no deterioration stage of OQLQ score.

Postsurgical Relapse in Class III Patients Treated With Two-Jaw Surgery: Conventional Three-Stage Method Versus Surgery-First Approach.

The aim of this study was to investigate the pattern, amount, and distribution of postsurgical relapse in skeletal Class III patients treated with two-jaw surgery (TJS) using conventional three-stage method (CTM) and surgery-first approach (SFA). A total of 38 patients who underwent the nonextraction approach and TJS (LeFort I posterior impaction and mandibular setback) were divided into CTM and SFA groups (all n = 19/group). Lateral cephalograms were taken before treatment (T0), at 1 month before surgery (T1), immediately after surgery (T2), and at debonding (T3) for CTM patients and at T0, T2, and T3 stages for SFA patients. Cephalometric measurements and statistical analyses were performed. There were no significant differences in the cephalometric variables at all stages except maxillary incisor inclination (U1-UOP) and overbite at T0 between 2 groups. They also did not exhibit significant differences in the amounts of surgical movement except for advancement of the maxilla. The mandible in both groups was rotated slightly clockwise by surgery and counterclockwise during T2-T3 without a significant difference. Distribution of cases with "high relapse" (>30%) and "low relapse" (<30%) of the mandible differed for 2 groups (P < 0.05). SFA group had more "high relapse" cases than CTM group (57.9% versus 26.3%). Postsurgical relapse of the mandible had a positive relationship with the amount of mandibular setback in SFA group (P < 0.01) and clockwise rotation of the proximal segment of the mandible in both groups (P < 0.05 and P < 0.01). The results suggest that SFA might be an effective alternative to CTM if the cause of "high relapse" including amounts of mandibular setback and clockwise rotation of the proximal segment of the mandible during surgery can be controlled.

Influence of temporomandibular joint disc displacement on craniocervical posture and hyoid bone position.

INTRODUCTION: The purpose of this study was to evaluate craniocervical posture and hyoid bone position in orthodontic patients with temporomandibular joint (TMJ) disc displacement. METHODS: The subjects consisted of 170 female orthodontic patients who consented to bilateral magnetic resonance imaging of their TMJs. They were divided into 3 groups based on the results of magnetic resonance imaging of their TMJs: bilateral normal disc position, bilateral disc displacement with reduction, and bilateral disc displacement without reduction. Twenty-five variables from lateral cephalograms were analyzed with 1-way analysis of variance to investigate differences in craniocervical posture and hyoid bone position with respect to TMJ disc displacement status. Pearson correlation coefficients were calculated to analyze the relationships between craniofacial morphology and craniocervical posture or hyoid bone position. RESULTS: Subjects with TMJ disc displacement were more likely to have an extended craniocervical posture with Class II hyperdivergent patterns. The most significant differences were found between patients with bilateral normal disc position and bilateral disc displacement without reduction. However, hyoid bone position in relation to craniofacial references was not significantly different among the TMJ disc displacement groups, except for variables related to the mandible. Pearson correlation coefficients indicated that extended craniocervical posture was significantly correlated with backward positioning and clockwise rotation of the mandible. CONCLUSIONS: This suggests that craniocervical posture is significantly influenced by TMJ disc displacement, which may be associated with hyperdivergent skeletal patterns with a retrognathic mandible.

Adhesion of mutans streptococci to self-ligating ceramic brackets: in vivo quantitative analysis with real-time polymerase chain reaction.

OBJECTIVE: To analyze in vivo mutans streptococci (MS) adhesion to self-ligating ceramic brackets [Clarity-SL (CSL) and Clippy-C (CC)] and the relationships between bacterial adhesion and oral hygiene indices. MATERIALS AND METHODS: Four central incisor brackets from the maxilla and mandible were collected from 40 patients (20 patients per each bracket type) at debonding immediately after plaque and gingival indices were measured. Adhesions of Streptococcus mutans, S. sobrinus, and total bacteria were quantitatively determined using real-time polymerase chain reaction after genomic DNA was extracted. Factorial analysis of variance was used to analyze bacterial adhesion to the brackets with respect to the bracket type and jaw position. Correlation coefficients were calculated to determine the relationships of bacterial adhesion to oral hygiene indices. RESULTS: Adhesion of total bacteria and S. mutans to CSL was higher than that to CC (P < 0.001). Adhesion of total bacteria to the mandibular brackets was higher than that to the maxillary ones (P < 0.001), while adhesion of S. mutans to the maxillary brackets were higher than that in the mandibular ones (P < 0.001). In particular, the proportion of S. mutans to total bacteria in CSL was higher than CC (P < 0.05) in the maxillary anterior teeth (P < 0.001). There were no significant differences in adhesion of S. sobrinus between the brackets and jaw positions. Interestingly, no significant relationships were found between bacterial adhesions and oral hygiene indices. LIMITATIONS: Complex bracket configurations may significantly influence bacterial adhesion to orthodontic brackets. Further in vivo study using bracket raw materials will help to define the relationships between bacteria adhesion and enamel demineralization. CONCLUSIONS: Because oral hygiene indices were not significantly correlated with adhesions of MS to self-ligating ceramic brackets, careful examinations around the brackets should be needed to prevent enamel demineralization, regardless of oral hygiene status.

Effect of self-ligating bracket type and vibration on frictional force and stick-slip phenomenon in diverse tooth displacement conditions: an in vitro mechanical analysis.

OBJECTIVE: To evaluate the effects of self-ligating bracket (SLB) type and vibration on frictional force and stick-slip phenomenon (SSP) in diverse tooth displacement conditions when a levelling/alignment wire was drawn. MATERIALS AND METHODS: A total of 16 groups were tested (n = 10/group): Two types of SLBs [active SLB (ASLB, In-Ovation R) and passive SLB (PSLB, Damon Q)]; vibration (30 Hz and 0.25 N) and non-vibration conditions; and 4 types of displacement [2mm lingual displacement of the maxillary right lateral incisor (LD), 2mm gingival displacement of the maxillary right canine (GD), combination of LD and GD (LGD), and control]. After applying artificial saliva to the typodont system, 0.018 copper nickel-titanium archwire was drawn by Instron with a speed of 0.5mm/min for 5 minutes at 36.5°C. After static/kinetic frictional forces (SFF/KFF), and frequency/amplitude of SSP were measured, statistical analysis was performed. RESULTS: ASLB exhibited higher SFF, KFF, and SSP amplitude (all P < 0.001) and lower SSF frequency (all P < 0.05) than PSLB in all displacement groups. Vibration decreased SFF, KFF, and SSP amplitude and increased SSP frequency in control and all displacement groups (all P < 0.001). ASLB exhibited lower SSP frequency than PSLB only under non-vibration condition (P < 0.05 in LD and GD, P < 0.01 in LGD). However, regardless of vibration conditions, ASLB demonstrated higher SSP amplitude than PSLB in all displacement groups (all P < 0.001 under non-vibration; all P < 0.01 under vibration). CONCLUSION: Even in tooth displacement conditions, vibration significantly reduced SFF, KFF, SSP amplitude, and increased SPP frequency in both PSLB and ASLB. However, in vivo studies would be needed to confirm the clinical significance.