Does Clockwise Rotation of Maxillomandibular Complex Using Surgery-First Approach to Correct Mandibular Prognathism Affect Surgical Movement and Stability?

PURPOSE: Orthognathic surgery (OGS) using the surgery-first approach (SFA) can decrease treatment time and increase patient satisfaction. Clockwise rotation (CWR) of the maxillomandibular complex to correct mandibular prognathism leads to optimized functional, aesthetic, and stable outcomes. This study examined the combined effect of SFA and CWR of the maxillomandibular complex to correct mandibular prognathism by comparing the surgical movement before (T0) and immediately after OGS (T1) and the stability between T1 and 12 months after OGS (T2). METHODS: This prospective cohort study enrolled patients with skeletal Class III malocclusion who underwent SFA involving Le Fort I osteotomy and bilateral sagittal split osteotomy, with or without genioplasty. Based on the occlusal plane (OP) change at T0-T1, the patients were divided into CWR (OP > 4°) and control (C) groups (OP ≤ 4°). The predictor variable was OP change at T0-T1. The primary outcome variable was the stability of pogonion (Pog) at T1-T2. The covariates included demographic factors, cephalometric measurements (anterior facial height, posterior facial height, OP, mandibular plane angle, incisor mandibular plane angle, overjet, and overbite), and 3-dimensional landmark displacement (anterior nasal spine, A-point, upper central incisor, upper first molar, lower central incisor, lower first molar, Pog, gonion, and condylion). An independent t-test was used to compare between these 2 groups when appropriate. The level of significance was set at P < .05. RESULTS: The sample included 28 patients (17 females) in the C group and 36 (24 females) in the CWR group; the mean ages were 23.89 ± 3.35 and 24.08 ± 4.02 years, respectively. For the surgical movement at T0-T1, the CWR group showed an association with vertical movement of the maxilla at posterior nasal spine (P = .005), anterior nasal spine (P < .001), and A-point (P < .001) and horizontal backward movement of the mandible at B-point (P < .001), Pog (P < .001), and gonion (P = .042). At T1-T2, all landmarks remained stable without clinically significant difference between the 2 groups. CONCLUSION: Surgical movement in the CWR group could vertically displace the maxilla and setback mandible more than that in the C group. Postoperative skeletal stability remained the same between the 2 groups at 1 year after OGS.

Does Clockwise Rotation of Maxillomandibular Complex Using Surgery-First Approach to Correct Mandibular Prognathism Improve Facial Appearance?

BACKGROUND: Facial aesthetics may be optimized based on a deeper understanding of soft tissue changes after orthognathic surgery. PURPOSE: The purpose of the study was to delineate facial soft tissue changes after clockwise rotation (CWR) of the maxillomandibular complex (MMC) to correct mandibular prognathism using the surgery-first approach. STUDY DESIGN, SETTING, SAMPLE: This prospective cohort study enrolled patients over 18 years of age with skeletal Class III malocclusion in the craniofacial center. The patients were excluded with previous history of craniofacial syndrome, orthognathic surgery trauma, infection at surgical sites, chin deviation (menton deviation ≥4 mm), 2 or more missing data points after surgery, or without informed consent. This study compared significant facial changes before (T0) and after orthodontic debonding (T1) in the CWR and control groups. PREDICTOR VARIABLE: The patients were divided in accordance with maxillary occlusal plane change (OPC) after surgery into CWR (OPC >4°) and control (OPC ≤4°) groups. MAIN OUTCOME VARIABLE: The primary outcome variable was frontal lip curvature (FLC: Right Cheilion-Stomion-Left Cheilion, degree) with or without upper lip curving upward at T1, where upper lip curving upward was considered more favorable. COVARIATES: The covariates included age, sex, and various cephalometric measurements. ANALYSES: The Mann-Whitney U test, paired, and independent t-test were implemented to compare the intragroup and intergroup differences. Statistical significance was indicated by P value <.05. RESULTS: The study comprised 34 patients (21 women) in the control group and 37 (29 women) in the CWR group; their mean ages were 23.64 ± 4.38 and 24.21 ± 3.84 years, respectively (P value = .562). At T1, the CWR group had significant increased FLC (P value = .001), alar width (P value = .034), and lower vermilion height (P value = .018), and decreased lower lip length (P value = .004). The high FLC group had significant decreased upper lip projection (P value = .002) and increased nasolabial angle (P value = .013). The significant relationship between CWR and high FLC was supported by the χ2 test (P value = .018) and multiple logistic regression (P value = .017). CONCLUSION: Greater CWR of the MMC increased FLC and lower vermilion height and reduced lower lip length. High FLC resulting from the CWR of the MMC improved facial appearance by moving the upper lip curve upward.

Does the floor of the maxillary sinus affect tooth movement for premolar extraction space closure?

OBJECTIVE: The study investigated orthodontic tooth movement by comparing various horizontal and angular measures of the teeth having different sinus-root relationship (SRR) of patients undergoing first premolar extraction treatment protocols. MATERIALS AND METHODS: This retrospective cross-sectional study included 45 Taiwanese adult patients, classified as the control group (n = 15) and the sinus group (n = 30) according to SRR. The control group had type I SRR (sinus floor above the level connecting the buccal and palatal root apices), whereas the sinus group included patients with type V SRR (the buccal and palatal root displayed apical protrusion into the sinus floor). Morphology was identified using pretreatment orthopantomograms. Lateral cephalometric measurements were conducted before treatment (T1) and at debonding (T2). RESULTS: Post debonding, there were no statistically significant difference in the two groups. However, the incisors in the control group became marginally more upright than those of the sinus group, and the molars demonstrated tipping movement with minimal anchorage loss in the sinus group than in the control group. The total treatment time was not significantly different between the 2 groups. CONCLUSION: The study revealed that the sinus-root relationship does not affect the orthodontic tooth movement. However, a more extensive 3-D study with larger sample size is strongly recommended before coming to any conclusion. CLINICAL RELEVANCE: The lining of the floor of the maxillary sinus does not affect the orthodontic tooth movement.

Does cleft lip and palate affect the severity of malocclusion?

OBJECTIVE: The purpose of this study was to evaluate the 3D anatomical features of unilateral (UCLP) and bilateral (BCLP) complete cleft lip and palate with those of skeletal Class III dentofacial deformities. MATERIALS AND METHODS: In total, 92 patients were divided into cleft and noncleft groups. The cleft group comprised 29 patients with UCLP and 17 patients with BCLP. The noncleft group comprised 46 patients with Class III dentofacial deformities. 3D anatomical landmarks were identified and the corresponding measurements were made on the cone-beam computed tomography (CBCT). RESULTS: The differences between the affected and unaffected sides of the patients with UCLP were nonsignificant. The differences between the patients with UCLP and BCLP were nonsignificant except for the SNA angle. Significant differences between the patients with clefts and Class III malocclusion were identified for the SNA, A-N perpendicular, and A-N Pog line, indicating that the maxillae of the patients in the cleft group were more retrognathic and micrognathic. Relative to the noncleft group patients, the cleft group patients had a significantly smaller ramus height. CONCLUSION: The affected and unaffected sides of the patients with UCLP did not exhibit significant differences. The maxillae of the patients with UCLP were significantly more retrognathic than those of the patients with BCLP. The maxillae and mandibles of the patients in the cleft group were more micrognathic and retropositioned relative to those of the noncleft Class III patients. CLINICAL RELEVANCE: The maxillary and mandibular findings indicated greater deficiencies in the patients with UCLP or BCLP than in those with skeletal Class III malocclusion. Appropriate surgical design should be administered.

Effects of maxillary advancement on maxillary incisor display in patients with skeletal Class III malocclusion and cleft lip and palate.

INTRODUCTION: The information on the hard- and soft-tissue factors correlated with tooth display after LeFort I osteotomy, especially in the surgery-first approach (SFA), are limited. This study aimed to correlate different parameters with the maxillary incisor display in patients with skeletal Class III malocclusion and those with cleft lip and palate (CLP) in SFA. METHODS: This study consisted of 35 patients with skeletal Class III malocclusion and 32 with cleft deformities who had undergone orthognathic surgery. Pretreatment and posttreatment lateral cephalometric analysis were obtained. Maxillary incisor display was measured in photographs. The intraclass correlation coefficient was used to assess the intraexaminer repeatability. The Student t test was used to compare the maxillary incisor display between 2 groups. Analysis of covariance was performed with pretreatment measurement as covariates, and the important determinants for maxillary incisor display were identified by adjusting the baseline measurements. RESULTS: The mean increase of maxillary advancement at point A was 5.25 mm and 1.28 mm downward movement for skeletal Class III malocclusion, whereas it was 4.59 mm advancement and 2.16 mm downward movement for patients with CLP. The resulting maxillary incisor display was 2.86 mm for skeletal Class III malocclusion and 2.56 mm for patients with CLP. The covariates for maxillary incisor display before intervention was significantly associated with the maxillary incisor display after intervention (P <0.001). However, the interaction effect of groups was not seen (P = 0.933). The horizontal position of A, vertical position of ANS, and upper lip length were the most predictable parameters (P <0.001, P <0.001, P = 0.048, respectively) for maxillary incisor display in both groups. CONCLUSIONS: Horizontal position of point A, vertical position of ANS, and upper lip length are the most important determinants for maxillary incisor display for patients with skeletal Class III malocclusion and those with CLP.

Are Signs of Degenerative Joint Disease Associated With Chin Deviation?

PURPOSE: Degenerative joint changes commonly affect the temporomandibular joint (TMJ) and can result in chin deviation. However, the extent of degenerative TMJ changes and chin deviation has not been well-characterized. The present study sought to correlate degenerative TMJ changes with condylar volume, grayscale measures, and chin deviation. MATERIALS AND METHODS: The present cross-sectional study had enrolled women with skeletal Class III malocclusion. Cone-beam computed tomography scans were acquired preoperatively. For each condyle, degenerative TMJ signs were analyzed and the condylar volume and grayscale were measured. The predictor variable was the presence of degenerative TMJ signs, classified as categorical data: 0, if none; 1, only present in 1 joint; and 2, present in both joints. The primary outcome variable was a chin deviation of 3 mm or more. Other associated variables were grouped by age, cephalometric data, and 3-dimensional condylar measurements. Descriptive bivariate statistics were computed, and univariate and multiple logistic regression analyses were conducted to identify any associations between degenerative TMJ disease and chin deviation. RESULTS: We included 85 patients, who were classified into 2 groups: less than 3 mm of chin deviation (n = 43) and 3 mm or more of chin deviation (n = 42). The presence of more than 10 degenerative TMJ signs was significantly associated with the presence of 3 mm or more of chin deviation (P < .001). In multiple regression models, the presence of subcortical sclerosis in 1 joint and in both joints (adjusted odds ratio [OR], 3.698; 95% confidence interval [CI], 1.051 to 13.012; adjusted OR, 5.001; 95% CI, 1.461-17.119, respectively) correlated significantly with the presence of 3 mm or more of chin deviation (P < .05). The volume difference between the 2 condyles was significantly greater in the group with more than 10 degenerative TMJ signs and 3 mm or more of chin deviation than in the group with 10 or fewer degenerative TMJ signs and less than 3 mm of chin deviation (P = .016 and P < .001, respectively). CONCLUSIONS: In women with skeletal Class III malocclusion, the presence of more than 10 degenerative TMJ signs increased the prevalence of 3 mm or more of chin deviation. The presence of subcortical sclerosis in either 1 or both joints and volume differences between the 2 condyles were associated with greater chin deviation.

Skeletofacial Reconstruction for Cleft-Related Deformities: Four Decades of Evolving Cleft Care.

Skeletofacial reconstruction in skeletally mature patients with cleft lip/palate can be challenging because of multifaceted condition-specific anatomical features in addition to several repercussions from surgical intervention during the growing period. This surgical report presents the history and evolving philosophy of cleft-skeletofacial reconstruction at the Chang Gung Craniofacial Center, a referral center for cleft care in Taiwan. The maximization of satisfactory function and the appearance outcome-burden ratio have been the fundamental aims for this team to develop and upgrade cleft-skeletofacial reconstruction over the past 4 decades, with more than 10,000 mature patients treated. The study highlights key lessons learned in outcome-based and patient-oriented changes over time until the current approach, which focuses on patient-centered care with a comprehensive, multidisciplinary, and team-based model. Substantial advances in surgical, orthodontic, anesthetic, and computer imaging aspects have contributed to improving and optimizing the correction of a broad spectrum of facial and occlusal deformities while ensuring safety, predictability, efficiency, and stability in outcomes. Understanding the development and refinement of cleft-skeletofacial reconstruction over the time and transferring these time-tested and scientifically validated protocols and principles to clinical practice may serve as a reliable foundation to continue the advancement and enhancement of the delivery of surgical cleft care worldwide.

History and Evolution of Orthognathic Surgery at Chang Gung Craniofacial Center: Lessons Learned From 35-Year Experience.

BACKGROUND: Modern orthognathic surgery (OGS) was established on the basis of contributions from multidisciplinary centers worldwide. This study reports the history and evolution of OGS at the Chang Gung Craniofacial Center (CGCC) and identifies the lessons learned from 35 years of experience. METHODS: The total number of OGS procedures managed by the CGCC multidisciplinary team between 1981 and 2016 was determined. The database of the senior author (Y.-R.C.) was reviewed for consecutive OGS procedures performed between 2003 and 2016. A literature review was also performed to retrieve the contributions from the total CGCC team. RESULTS: The 35 years of experience at a single center and 13-year experience of a single surgeon corresponded to 8073 and 2883 OGS procedures, respectively. Moreover, 53 peer-reviewed articles were reviewed. Teamwork (plastic surgeons, orthodontists, and anesthetists) ensured an optimal balance between occlusion functional and facial aesthetic outcomes, with patient safety ensured and a minimum of OGS-related complications. Progression from the conventional orthodontics-first approach to the surgery-first OGS approach decreased the overall treatment time. Transition from 1-jaw to 2-jaw surgery enabled more consistent aesthetic outcomes to be achieved. Conversion from the 2-splint to the single-splint technique enabled development of a more precise tridimensional simulation plan and surgical execution, including in challenging scenarios such as malocclusion associated with facial asymmetry. Clockwise pitch rotation of the maxillomandibular complex has been designed for facial aesthetic purposes in class III malocclusion, whereas counterclockwise pitch rotation of the maxillomandibular complex improves airway function in those with sleep apnea. CONCLUSIONS: The lessons learned from experience and outcome-based articles reveal that OGS has successfully evolved at the CGCC, with a balance being achieved between functional and aesthetic outcomes and effective decreases in the burden of care (ie, morbidity, complications, and treatment time).

Does Sleep Quality Affect Temporomandibular Joint With Degenerative Joint Changes?

PURPOSE: The purpose of this study was to answer the following question: Among female patients who have skeletal Class III malocclusion, does poor sleep quality increase the prevalence of degenerative joint changes in the temporomandibular joints (DJC-TMJ)? MATERIALS AND METHODS: We designed a prospective cohort study and enrolled female patients who required orthognathic surgery to correct skeletal Class III malocclusion from January 2014 to December 2017. This is the first serial study to identify the relationship between sleep quality and DJC-TMJ before orthognathic surgery. The predictor variable was sleep quality, documented either as poor, indicated by a Pittsburgh Sleep Quality Index (PSQI) score of 5 or greater, or as good, indicated by a PSQI score of less than 5. The primary outcome variable was the presence of 5 or more DJC-TMJ signs or fewer than 5 DJC-TMJ signs. Other associated variables were grouped into the following categories: demographic variables (age and body mass index) and cephalometric data. Descriptive bivariate statistics were computed and univariate and multiple logistic regression analyses were conducted to identify factors associated with DJC-TMJ. RESULTS: The sample was composed of 52 patients grouped as follows: good sleep quality group (n = 25, PSQI score < 5) and poor sleep quality group (n = 27, PSQI score ≥ 5). Poor sleep quality was significantly associated (P = .027) with an increase in DJC-TMJ signs. In the multiple regression model, a PSQI score of 5 or greater (adjusted odds ratio, 5.806; 95% confidence interval, 1.406 to 23.974) and greater sella-nasion-point A angle (adjusted odds ratio, 1.453; 95% confidence interval, 1.127 to 1.871) were significantly associated (P < .05) with an increased prevalence of DJC-TMJ. CONCLUSIONS: The results of this study suggest that in female patients with skeletal Class III malocclusion, poor sleep quality could increase the prevalence of DJC-TMJ. Future cohort studies are required to support that sleep disturbance can increase DJC-TMJ in the general population.

Vomer flap for hard palate repair is related to favorable maxillary growth in unilateral cleft lip and palate.

OBJECTIVE: Vomer flap repair is assumed to improve maxillary growth because of reduced scarring in growth-sensitive areas of the palate. Our aim was to evaluate whether facial growth in patients with unilateral cleft lip and palate was significantly affected by the technique of hard palate repair (vomer flap versus two-flap). MATERIALS AND METHODS: For this retrospective longitudinal study, we analyzed 334 cephalometric radiographs from 95 patients with nonsyndromic complete unilateral cleft lip and palate who underwent hard palate repair by two different techniques (vomer flap versus two-flap). Clinical notes were reviewed to record treatment histories. Cephalometry was used to determine facial morphology and growth rate. The associations among facial morphology at age 20, facial growth rate, and technique of hard palate repair were assessed using generalized estimating equation analysis. RESULTS: The hard palate repair technique significantly influenced protrusion of the maxilla (SNA: ß = -3.5°, 95 % CI = -5.2-1.7; p = 0.001) and the anteroposterior jaw relation (ANB: ß = -4.2°, 95 % CI = -6.4-1.9; p = 0.001; Wits: ß = -5.7 mm, 95 % CI = -9.6-1.2; p = 0.01) at age 20, and their growth rates (SNA p = 0.001, ANB p < 0.01, and Wits p = 0.02). CONCLUSIONS: The results suggest that in patients with unilateral cleft lip and palate, vomer flap repair has a smaller adverse effect than two-flap on growth of the maxilla. This effect on maxillary growth is on the anteroposterior development of the alveolar maxilla and is progressive with age. We now perform hard palate closure with vomer flap followed by soft palate closure using Furlow palatoplasty. CLINICAL RELEVANCE: These findings may improve treatment outcome by modifying the treatment protocol for patients with unilateral cleft lip and palate.

The Impact of the COVID-19 Pandemic on Orthodontic Adult Patients' Characteristics and Decision on Orthodontic Appliance.

Purpose: There is an overall paucity of data examining the specific details of orthodontic patients' patterns or orthodontic service disruptions possibly influenced by COVID-19 pandemic. Therefore, this study aimed to explore the impact of the COVID-19 pandemic on orthodontic clinic disruption regarding the change in adult patients' characteristics and decisions of orthodontic treatment devices. Patients and Methods: A retrospective sample of 311 patients receiving orthodontic treatment from 2018 to 2022 were collected and divided into two groups: before (n = 167) and during (n = 144) the COVID-19 pandemic. Demographics, dental indices, the index of complexity outcome and need (ICON), and the degree of treatment difficulty were analyzed. Results: There were fewer students among patients during the COVID-19 pandemic than before (24.5% versus 35.9%, P = 0.036). Compared with patients before the pandemic, more patients selected ceramic brackets or Invisalign during the pandemic (P = 0.022). There were higher percentage of class I dental malocclusions among patients during than before the COVID-19 pandemic (P = 0.044). Moreover, the ICON score and the score of the degree of treatment difficulty were both significantly lower for patients during than before the COVID-19 pandemic (63.9±14.0 versus 58.3±15.3, P=0.001 and 7.4±2.6 versus 6.8±2.6, P=0.049, respectively). Conclusion: The COVID-19 pandemic influenced the characteristics and decisions of orthodontic patients. Those who still came to the orthodontic clinic despite the COVID-19 outbreak may have been those with less malocclusion severity and treatment difficulty. Besides, during the time of covid-19 pandemic, more patients chose ceramic bracket and Invisalign as their orthodontic treatment device rather than conventional or self-ligating metal brackets.

Skeletal and dental variables related to the stability of orthognathic surgery in skeletal Class III malocclusion with a surgery-first approach.

PURPOSE: The objectives of the study were to identify the parameters related to skeletal stability after orthognathic surgery in skeletal Class III malocclusion using a surgery-first approach and to analyze the factors correlated with surgical relapse. MATERIALS AND METHODS: Forty-five consecutive patients were included. Serial cephalometric radiographs were traced and superimposed to investigate surgical stability at the initial examination, 1 week postoperatively, and after orthodontic debonding (12.22 mo after surgery). Patient grouping was based on the amount of horizontal relapse at the innermost point of the contour of the mandible between the incisor tooth and the bony chin, the B point (less stable group, n = 15; highly stable group, n = 18). Parameters, such as presurgical skeletal and dental variables, the amount of surgical setback, and total treatment duration, were compared between groups and analyzed for correlations with surgical stability. RESULTS: The mean setback at the innermost point of the contour of the mandible between the incisor tooth and the bony chin was 11.19 mm, and the mean relapse rate was 12.46%. The amount of surgical setback, overbite (positive values), overjet, depth of the curve of Spee, and lower anterior facial height showed statistically significant differences between groups. The amount of surgical setback, overbite (positive values), overjet, and depth of the curve of Spee showed statistically significant correlations with the amount of relapse. Skeletal relapse of the mandible increased significantly as the overbite increased. CONCLUSION: The factors for instability in the surgery-first approach include a larger overbite, a deeper curve of Spee, a greater negative overjet, and a greater mandibular setback. The initial overbite may be an indicator to predict possible skeletal relapse of mandibular setback.

Alteration of masticatory electromyographic activity and stability of orthognathic surgery in patients with skeletal class III malocclusion.

PURPOSE: The purposes of this study were to 1) investigate longitudinal changes in electromyographic masticatory activity subsequent to orthognathic surgery (OGS) in patients with skeletal Class III malocclusion, and 2) compare masticatory muscle activity and skeletal factors in patients with stable versus relapsed mandibular positions after OGS. MATERIALS AND METHODS: A consecutive series of patients with skeletal Class III malocclusion who underwent 2-jaw OGS (35 patients, 17 men and 18 women; age, 24.5 ± 5.0 yr) were included. Lateral cephalometric films were obtained preoperatively (T1), 1 month after OGS (T2), and at completion of orthodontic treatment (T3). Serial cephalometric tracings and analyses were obtained. Surface electromyograms of the anterior temporalis and masseter muscles were recorded at T1, T2, and T3 (6 mo after OGS). Resting tonus, maximum voluntary clench with habitual intercuspation and on cotton pads, and maximum muscle firing were evaluated. Percentage of overlapping coefficient and torque coefficient were calculated. Patients were categorized further into stable and relapse groups according to the sagittal relapse rate of mandibular setback. These surface electromyographic variables were compared between the 2 groups. RESULTS: On average, the mandible showed a significant setback of 10.19 mm and a relapse of 1.12 mm (10.99%). Surgical relapse did not correlate with gender or genioplasty. Serial surface electromyographic data indicated a significant decrease from T1 to T2 that then recovered from T2 to T3. No significant difference between T1 and T3 was noted. Percentage of overlapping coefficient was significantly decreased after OGS. The torque coefficient did not differ significantly from T1 to T3. The relapse group (relapse, >11%; n = 15) had a greater resting tonus of the anterior temporalis muscle at T3, a larger percentage of overlapping coefficient at T1, and a greater maximum voluntary clench of the masseter muscles at all times than in the stable group (n = 20). The relapse group exhibited a greater decrease in facial height (2.18 mm) from T2 to T3 than did the stable group (0.5 mm). CONCLUSION: A larger sagittal relapse of mandibular setback occurred in patients with greater masticatory muscle activity. Modifications in surgical design and overcorrection should be considered in patients with greater masticatory muscle activity before OGS.

Quantitative evaluation of cortical bone thickness in mandibular prognathic patients with neurosensory disturbance after bilateral sagittal split osteotomy.

PURPOSE: The buccal cortical thickness (BCT) between the mandibular canal and the corresponding external cortical surface was compared in patients with and without neurosensory disturbance (NSD) after they underwent a bilateral sagittal split osteotomy (BSSO) to correct mandibular prognathism. PATIENTS AND METHODS: This prospective cohort study was conducted in 146 patients (95 women, 65.1%; 51 men, 34.9%) 18 to 39 years old who underwent bimaxillary surgery (ie, Le Fort I osteotomy and BSSO) to correct mandibular prognathism. NSD was identified using a light touch test with a Semmes-Weinstein monofilament and a pricking pain test with a sharp dental explorer 1 week after surgery. Preoperative cone-beam computed tomographic (CBCT) imaging was used to visualize the bone contacts or fusion of the mandibular canal to the buccal cortical bone and to decrease injury to the mandibular nerve during surgical dissection. Preoperative CBCT imaging also was used to assess the BCT every 2 mm from the mandibular foramen to the furcation of the mandibular first molar in the NSD group and the sensory normal (N) group. RESULTS: The incidence of NSD was 32.5% at 1 week after surgery. There was no statistically significant difference between men and women, the side affected, or genioplasty at the time of undergoing BSSO. Of the total sample group, decreased BCT was identified throughout the observed length of the mandibular canal in the NSD group compared with the N group. Statistically significant decreased BCTs were 16 to 20 mm and 24 mm in the total sample, 6 to 8 mm in the female group, and 16 to 18 mm in the male group. CONCLUSION: Compared with the N group, BCTs in the NSD group were always decreased, especially those located at 16 to 20 mm and 24 mm in the total sample, 6 to 8 mm in the female group, and 16 to 18 mm in the male group.

Projection of the dental workforce from 2011 to 2020, based on the actual workload of 6762 dentists in 2010 in Taiwan.

BACKGROUND/PURPOSE: Planning of the dental workforce, especially the number of dentists, requires the data of actual dental workloads. This study attempts to make projections of the dental workforce from 2011 to 2020, based on a survey of the actual workload of 6762 dentists in 2010. METHODS: In 2010, a database of 11,449 current dentists was retrieved from the file of Department of Health, Executive Yuan, Taipei, Taiwan. Questionnaires with the information of each dentist and 10 questions regarding the actual workload were sent to each dentist with a return envelope. The actual workload of the dentists who returned the questionnaires was analyzed. A projection of dental workforce from 2011 to 2020 was calculated, based on the actual workload. RESULTS: An analysis of the actual dental workload was conducted on 6762 (59.1%) returned questionnaires. The dentist-to-population ratio (defined as the number of dentists per 10,000 people) was 5.0 in 2010. The supply of 400 dentists per year remained constant from 2006 to 2010, and is expected to be sustained for the next 10 years. Because the population of Taiwan will begin to decrease within the next 10 years, we estimate that the dentist-to-population ratio will increase to 6.0 by the year 2020 or earlier. After adjusting for working hours, working days, and gender differences, surplus dentists will number approximately 1069 in 2020. CONCLUSION: An oversupply of dentists and a decrease in population will result in a surplus of dentists. To make better projections of the dental workforce, surplus dentists can be arranged to care for the aged, disabled people, and underserved people.

Craniofacial characteristics in unilateral complete cleft lip and palate patients with congenitally missing teeth.

INTRODUCTION: Congenitally missing permanent teeth are common in patients with clefts. This retrospective study was conducted to evaluate the craniofacial characteristics in patients with unilateral complete cleft lip and palate with congenitally missing permanent teeth. METHODS: A series of 73 consecutive patients with nonsyndromic unilateral complete cleft lip and palate were enrolled. Evaluation of congenitally missing permanent teeth was based on the panoramic films taken from 7 to 11 years of age. The cephalometric films taken around 9 years of age were used to compare the craniofacial morphology in patients with no congenitally missing permanent teeth (n = 20) and 1 (n = 25), 2 (n = 18), and 3 (n = 10) congenitally missing permanent teeth. The Spearman correlation coefficient was used to assess the association of increased numbers of congenitally missing permanent teeth with each cephalometric parameter. RESULTS: Anterior facial height, distance from the maxillary incisor and first molar to the palatal plane, and overjet decreased as the number of congenitally missing permanent teeth increased in patients with unilateral cleft lip and palate. CONCLUSIONS: Unilateral cleft lip and palate patients with congenitally missing permanent teeth have a unique craniofacial morphology with a reduced vertical dimension.

Longitudinal observation of mandibular motion pattern in patients with skeletal Class III malocclusion subsequent to orthognathic surgery.

PURPOSE: The aims of the present study were to delineate the characteristic patterns of 3-dimensional (3D) mandibular movement in patients with skeletal Class III malocclusion compared with normal individuals and to investigate the longitudinal changes in mandible and condylar motion after orthognathic surgery (OGS). PATIENTS AND METHODS: The subjects in the present prospective study consisted of 2 groups. The OGS group included 24 patients with skeletal Class III who underwent OGS. The control group consisted of 25 patients who underwent orthodontic treatment only. The patient records included demographic data, lateral and posteroanterior cephalometric radiographs before treatment, and serial mandibular motion data. In the OGS group, the mandibular motion data were obtained before OGS (T1), 1 month after OGS (T2), and at least 6 months after OGS (T3). The differences in cephalometric measurements and mandibular movements between the 2 groups were compared. The Pearson correlation test was performed to assess the relationship between the cephalometric measurements and the mandibular movements. Serial changes in mandibular movement in the OGS group were also compared. RESULTS: The skeletal pattern in the OGS group demonstrated retrusive maxilla and a protrusive mandible, with a larger mandibular plane angle. For the incisal range of motion, the OGS group's maximal mouth opening was larger than the control group's by 6.9 mm. In the OGS group, the condylar range of motion in retrusion and the Bennett angle were asymmetric. Skeletal Class III patients tended to have a smaller range of condylar retrusion. At 1 month after OGS, the maximal incisal range of motion decreased from 57.23 to 25.61 mm. Other variables, including laterotrusion, movement velocity, and angle and distance of condylar movement in protrusion, reduced significantly. The Bennett angle demonstrated increased symmetry on both sides. Six months after OGS, the condylar motion in opening demonstrated improvements, but to a lesser extent than at T1. The condylar motion in retrusion recovered totally. The maximum incisal range of motion reduced slightly, but remained similar in value to that of the control group. The variables, including laterotrusion, movement velocity, and angle and distance of condylar movement in protrusion, demonstrated total recovery. The mandibular movement variables at T3 were not significantly different from those of the control group. CONCLUSIONS: Skeletal Class III patients demonstrated a larger maximal mouth opening than did the controls, along with similar laterotrusion, but with a smaller retrusive condylar range of movement. The range of incisor motion and condylar movement did not correlate. The deterioration in mandibular motion after OGS can recover totally within 6 months. At T3, the mandibular movement remained consistent with the amount in normal subjects.

Field survey of dental manpower in Taiwan's hospitals.

BACKGROUND/PURPOSE: In Taiwan, dental manpower in hospitals plays an important role in dental education other than clinical service. Questionnaires, as well as a field survey, were conducted to understand the situation of dental manpower in 2007 and 2008. METHODS: During the period from 2007 to 2008, questionnaires about dental administration, clinical dental practice, dental education, dental manpower and dental facilities were mailed to the dental departments of 165 hospitals located around Taiwan; 134 completed the questionnaire and mailed it back. The field survey was also carried out by visiting hospitals, to collect and gather information at the local level. There were 102 hospitals within the 134 hospitals which accepted the field survey; the rate was 62.0%. RESULTS: In 2008, the number of dentists working in the hospitals was 1,421, which was approximately 13% of the number of total dentists in Taiwan (9672). Within the 1,421 dentists, 675 were attending staffs and 745 dentists were training residents. Within the 675 attending dentists, 510 (75.6%) had dental specialist certificates and 272 (40.3%) had teaching positions in dental schools. There were 382 dental interns (6(th) year undergraduate students) taking the training programs in hospitals, most of whom were trained in medical centers (342/382, 89.5%). Moreover, there were 888 dental assistants, 338 of whom were nurses and the other 550 were hospital self-trained personnel. CONCLUSION: Comparing the dental manpower of different types of hospitals in Taiwan, the medical center was the best, followed by the regional hospital and the district hospital was last. When comparing 2008 with 2002, the numbers of both dentists and auxiliary personnel in Taiwan's hospitals increased with years. Although there were still only 13% dentists working in the hospital, they were responsible for teaching young dentists and doing research in hospitals. In other words, the quality of clinical service, teaching, and research in hospitals would influence the development of young dentists.

Improvement of chin profile after mandibular setback and reduction genioplasty for correction of prognathism and long chin.

BACKGROUND: This study evaluated the changes in the chin profile after using mandibular setback and vertical chin reduction genioplasty to correct mandibular prognathism associated with a long and flat chin. METHODS: Sixteen consecutive patients (6 male and 10 female) underwent surgery at a mean age of 22.6 years (range = 18.2-27.8 years). The evaluation consisted of hard and soft tissue analysis before and after treatment. RESULTS: The results showed that improvement in facial profile, chin contour, and dental occlusion was achieved. After an average of 9.4-mm mandibular setback and 5.1-mm vertical osseous chin reduction, the thickness of soft tissue pogonion was increased by 4.0 mm, the supramentale thickness was increased by 1.8 mm, and lower-lip thickness was increased by 1.6 mm. Thus, the mentolabial fold increased from 3.4 to 4.7 mm and the mentolabial angle decreased from 153.4 to 136.9°. The vertical lip:chin ratio became normal. CONCLUSION: The results of this study demonstrated that mandibular setback combined with vertical chin reduction genioplasty offers an alternative for the treatment of patients suffering from mandibular prognathism with a long, nonprojecting chin. LEVEL OF EVIDENCE IV: This journal requires that authors assign a level of evidence to each article.

Characteristics and Dental Indices of Orthodontic Patients Using Aligners or Brackets.

Background. Clear aligners have become a treatment alternative to metal brackets in recent years due to the advantages of aesthetics, comfort, and oral health improvement. Nevertheless, few studies have analyzed the clinical characteristics and dental indices of orthodontic patients using aligners or brackets. Methods. A total of 170 patients received orthodontic treatment at Chang Gung Memorial Hospital in 2021. Patients were stratified by types of treatment (Invisalign® clear aligner (n = 60) or metal bracket (n = 110). Results: Patients were aged 26.1 ± 7.2 years, and most were female (75.0%). The Invisalign® group was older than the bracket group (p = 0.003). The skeletal relationships were mainly Class I (49.4%), followed by Class II (30.0%) and Class III (20.6%). The molar relationships were primarily Class I (38.8%), followed by Class II (37.1%) and Class III (24.1%). The decayed, missing, and filled tooth (DMFT) index was 9.9 ± 6.0, including 2.1 ± 2.9 for decayed teeth, 0.5 ± 1.1 for missing teeth, and 7.3 ± 4.3 for filled teeth. There were no significant differences in the DMFT index or skeletal and molar relationships between the groups (p > 0.05). The index of complexity outcome and need (ICON) was 56.8 ± 13.5, and the score was lower in the Invisalign® group than in the bracket group (p = 0.002). Among the variables included in the ICON assessment, only the aesthetic variable was lower in the Invisalign® group than in the bracket group (p < 0.001). The Frankfort-mandibular plane angle was 27.9 ± 5.1 degrees. Finally, the E-line of the lower lip was lower in the Invisalign® group than in the bracket group (1.5 ± 2.4 versus 2.8 ± 3.1, p = 0.005). Conclusions. Older patients showed a greater intention to choose Invisalign® treatment for improving the appearance of their teeth than younger patients, who chose metal bracket treatment. The demand for Invisalign® aligner treatment for aesthetic reasons was substantial. A soft tissue profile with more protrusive lower lips and a greater need for orthodontic treatment was found in the bracket group.