The future of faculty recruitment: Inspiring students into an academic career.

The dilemma surrounding faculty shortages within dental education continues to present significant challenges for the dental profession. There remains a tremendous need to create an effective and sustainable pathway for the recruitment of faculty into dental academia, with an emphasis on the establishment of a more diverse and representative faculty composition. This perspective paper proposes a blueprint to nurture and inspire dental students into academia.

Prediction of the Post-Pubertal Mandibular Length and Y Axis of Growth by Using Various Machine Learning Techniques: A Retrospective Longitudinal Study.

The aim was to predict the post-pubertal mandibular length and Y axis of growth in males by using various machine learning (ML) techniques. Cephalometric data obtained from 163 males with Class I Angle malocclusion, were used to train various ML algorithms. Analysis of variances (ANOVA) was used to compare the differences between predicted and actual measurements among methods and between time points. All the algorithms revealed an accuracy range from 95.80% to 97.64% while predicting post-pubertal mandibular length. When predicting the Y axis of growth, accuracies ranged from 96.60% to 98.34%. There was no significant interaction between methods and time points used for predicting the mandibular length (p = 0.235) and Y axis of growth (p = 0.549). All tested ML algorithms accurately predicted the post-pubertal mandibular length and Y axis of growth. The best predictors for the mandibular length were mandibular and maxillary lengths, and lower face height, while they were Y axis of growth, lower face height, and mandibular plane angle for the post-pubertal Y axis of growth. No significant difference was found among the accuracies of the techniques, except the least squares method had a significantly larger error than all others in predicting the Y axis of growth.

Objective characterization of dental occlusal and fissure morphologies: Method development and exploratory analysis.

OBJECTIVE: To develop clinically applicable methods to characterize occlusal topography and assess possible associations between morphology and caries incidence and development. DESIGN: In this retrospective clinical study, we evaluated caries presence and severity pre- and post-orthodontic treatment for first molars of 147 patients (384 teeth). These teeth were previously scanned using a clinical intraoral scanner, and the obtained digital elevation models were used to 1) analyze the 3D occlusal surface parameters (n = 384) and 2) quantitatively characterize the mandibular molars' (n = 166) fissure patterns using three novel methods. Pearson correlation coefficients were calculated to evaluate the associations among the measurements, and presence/severity of caries pre- and post-treatment were assessed using generalized linear mixed-effects models. RESULTS: Robust quantitative fissure characterizations were developed, and reliable occlusal surface parameters were obtained. In the studied population, none of the parametric measurements (Slope: p = 0.62 for presence, p = 0.96 for severity; Relief Index (RFI): p = 0.36, p = 0.84; Orientation Patch Count rotated (OPCr): p = 0.48, p = 0.13; Dirichlet Normal Energy (DNE): p = 0.91, p = 0.15) or the fissure morphological measurements (Mesial Angle: p = 0.43; Distal Angle: p = 0.86; Average Angle: p = 0.52; Area Difference: p = 0.83; Percent Fissure: p = 0.68) were found to be significantly associated with caries status or severity. CONCLUSION: Despite the lack of correlation in the limited studied sample, the tools developed to characterize occlusal surface topography and fissure morphology have the potential to be used in more comprehensive clinical evaluations.

The TMD-7 as a Brief Measure for Assessing Temporomandibular Disorder.

OBJECTIVES: The aim of this cross-sectional prospective study was to determine the internal consistency of the TMD-7, and compare prevalence of TMD symptoms in an adult population. MATERIALS AND METHODS: Upon presenting to the orthodontic screening appointment, a total of 440 subjects (316 females and 124 males) were asked to complete the TMD-7 questionnaire. A total of 108 of the participants were later excluded from the study either due to the duplicate or missing responses. The final sample consisted of data from 332 participants (232 females and 100 males), aged between 18 and 64 (mean age: 42.9 ± 9.0) years. STATISTICAL ANALYSIS: Cronbach's α statistics were calculated to assess internal consistency. Comparisons between genders, among age categories, and between subjects with versus without prior orthodontic treatment were performed using Wilcoxon ranks sum and Kruskal-Wallis tests. Comparisons for differences in the individual TMD-7 item ratings were performed using Mantel-Haenszel chi-square tests for ordered categorical responses. RESULTS: The calculated Cronbach's α for TMD-7 scale was 0.77. No statistically significant differences were found in the TMD-7 scale score or the individual TMD-7 item ratings between age categories (p = 0.993). Females had significantly higher TMD-7 scale score and higher ratings for headache, pain in jaw, pain in neck, pain in forehead, difficulty opening mouth, and difficulty while eating (p < 0.05). No statistically significant differences were found in the TMD-7 scale score or the individual TMD-7 item ratings between subjects with versus without previous orthodontic treatment (p = 0.075). CONCLUSION: The TMD-7 tool has good internal consistency and can be used reliably for assessment of TMD symptoms in adults. The use of this tool revealed no significant differences between age groups or between subjects with or without previous orthodontic treatment. However, a significant female gender predisposition for TMD symptoms in the adulthood was determined.

Orthodontic and oral health literacy in adults.

OBJECTIVE: The primary aim of the study was to determine levels of literacy in both oral health and orthodontics in an adult population. The secondary study aim was to investigate differences in literacy between males and females. METHODS: Participants included individuals 18 years or older seeking dental treatment at the East Carolina University (ECU) School of Dental Medicine. To determine levels of oral health literacy (OHL) and orthodontic literacy (OrthoL), validated instruments were administered, including the Rapid Estimate of Adult Literacy in Medicine and Dentistry, the Oral Health Literacy Instrument and its separate scales, and a questionnaire on orthodontic literacy. Summary statistics were computed, and statistical significance was set at 0.05. RESULTS: One hundred seventy-two individuals participated in the study and had a mean age of 55.03 (range:18-88). Greater than 70% of the sampled population exhibited inadequate or marginal oral health knowledge. Additionally, greater than 70% of the sample possessed no more than an 8th grade reading level, with regard to basic medical and dental terms. Higher education was weakly associated with higher OrthoL and OHL. Higher age was also weakly associated with lower OrthoL and OHL. Males on average exhibited significantly higher OHL (p < .05) but there were no OrthoL differences between males and females. Dental visit frequency was not associated with OrthoL or OHL. CONCLUSION: Low levels of OrthoL and OHL were observed in the study. While males demonstrated a higher level of OHL than females, neither age nor the occurrence of dental appointments significantly influenced levels of literacy.

The impact of dental curriculum format on student performance on the national board dental examination.

PURPOSE/OBJECTIVE: The effectiveness of different curriculum types has long been debated by dental educators aiming to provide the best education possible to their students. This study aimed to evaluate the effect of curriculum type (hybrid problem-based learning [PBL] vs. traditional) on National Board Dental Examination (NBDE) part I and II pass rates METHODS: A retrospective cohort study was conducted with a hybrid PBL cohort and traditional cohort. NBDE part I and II pass rates for the two cohorts were acquired, along with demographic and scholastic variables. Pass rates, scholastic variables, and demographic variables were compared using two-sample t-tests and chi-square tests. Associations of the variables with pass rates were analyzed using logistic regression. Significance was set at 5% RESULTS: No significant differences in pass rates for NBDE part I and II were observed between the cohorts. Cumulative dental school grade point average (GPA) was found to be an independent predictor of success for NBDE part I (odds ratio (OR): 1.40, 1.24-1.59 for 0.1 point intervals) and II (OR: 1.34, 1.18-1.52 for 0.1 point intervals), (p < 0.01). DAT biology sub-score was found to be predictive of success for NBDE part I (OR: 1.58, 1.14-2.19), (p = 0.01) CONCLUSIONS: No significant difference in NBDE part I and II pass rates between the cohorts was found. Dental school GPA was the most predictive variable for success on NBDE part I and II. These findings may be helpful considerations as institutions assess the structure of their school curricula.

Precision and accuracy assessment of single and multicamera three-dimensional photogrammetry compared with direct anthropometry.

OBJECTIVES: To assess the precision and accuracy of single-camera photogrammetry (SCP) and multicamera photogrammetry (MCP) compared with direct anthropometry (DA). MATERIALS AND METHODS: A total of 30 participants were recruited, and 17 soft tissue landmarks were identified and used to complete a total of 16 measurements. Using SCP and MCP, two three-dimensional (3D) images were acquired from each participant. All 3D measurements and direct measurements were measured twice by the same operator to assess intraexaminer repeatability. Intraclass coefficients (ICCs) were used to evaluate intraexaminer repeatability and interexaminer agreement of the methods. Nonparametric bootstrap analyses were used to compare the means of the measurements among the three methods. RESULTS: All three methods showed excellent intraexaminer repeatability (ICCs > 0.90), except interpupillary distance (ICC = 0.86) measured by SCP. Both SCP and MCP showed excellent interexaminer agreement (ICCs > 0.90), except interpupillary distance (ICC = 0.79), left gonion-pogonion (ICC = 0.74), and columella-subnasale-labrale superior angle (ICC = 0.86) measured by SCP. Overall, there was good agreement between methods, except for columella-subnasale-labrale superior angle (ICC = 0.40) between SCP and MCP. CONCLUSIONS: Both SCP and MCP techniques were found to be reliable and valid options for 3D facial imaging. SCP produced slightly larger mean values for several measurements, but the differences were within a clinically acceptable range. Because of the larger margin of errors, measurements including the gonial area and subnasale should be assessed with caution.

Stress and anxiety in orthodontic residents during the coronavirus disease 2019 pandemic.

INTRODUCTION: The coronavirus disease 2019 pandemic has had far-reaching effects on health care providers and health professional students; however, little is known about the factors related to stress and anxiety levels, specifically among orthodontic residents during this time. METHODS: A 2-part questionnaire, which included modified stress and anxiety inventories, was disseminated electronically to U.S. orthodontic residents between June and July 2020. Descriptive and comparative statistics were used to analyze the data. RESULTS: Overall, 261 participants responded (56% female), representing a response rate of 26.8%. Significant gender differences were found in 18 stress items, with female respondents expressing more stress than their male counterparts. Only 1 stress item (ie, fear of being unable to catch up if behind) varied as a function of the difference on the basis of respondents' stage in the program. First-year residents reported more stress in relation to this than more senior residents. Responses to all anxiety items but 1 item varied by gender, with females reporting higher scores. Residents in the middle stages of their program responded with higher anxiety scores with significant differences on 3 anxiety items. CONCLUSIONS: Although financial responsibilities and travel plans were the most stressful and anxiety-inducing items for orthodontic residents during the early aspect of the coronavirus disease 2019 pandemic, multiple items contributed to their stress and anxiety. In addition, both gender and stage of progress in a residency program impacted the level of stress and anxiety reported by respondents.

The impact of the COVID-19 pandemic on U.S. orthodontic practices in 2020.

INTRODUCTION: This study aimed to investigate the immediate impact and long-term implications of severe acute respiratory syndrome coronavirus on orthodontic practices in the United States in 2020. METHODS: A 35-item survey was developed and validated to investigate the impact of the coronavirus disease (COVID-19) pandemic on the orthodontic specialty. The survey contained 5 domains, including respondent's demographic information, COVID-19 information acquisition, practice ramifications of the COVID-19 pandemic, financial implications of the COVID-19 pandemic, and patient management strategies during the COVID-19 pandemic. This voluntary survey acquired responses from active orthodontists in the United States. Associations of demographic and practice characteristics with items related to COVID-19 were assessed using chi-square tests, with a 5% significance level. RESULTS: The survey was disseminated to 5,694 orthodontists, and 507 complete surveys were obtained (response rate of 8.9%). Respondents indicated that they obtained the most useful information regarding the COVID-19 pandemic through professional associations and internet or online news resources. However, 30% of the orthodontists believed information regarding personal financial guidelines was lacking. Most respondents identified delayed treatment progress and temporary staff layoffs as the 2 most negative ramifications of mandated office closures. Approximately 93% of practices applied for and used some sort of stimulus funding offered through the Coronavirus Aid, Relief, and Economic Security Act. Respondents indicated that the COVID-19 related office closures resulted in an average of 50% decrease in net revenue. CONCLUSIONS: The survey found that the COVID-19 pandemic had a broad and significant impact on patient care and financial aspects of U.S. orthodontic practices in 2020. Although generally accepting of the federal and state recommendations, respondents appeared to desire more guidance during the early phase of the pandemic.

Correlation between Advanced Dental Admission Test performance and dental MATCH success.

PURPOSE/OBJECTIVES: The Advanced Dental Admissions Test was developed in 2016 to aid residency programs evaluate qualified applicants. Since its conception, however, there have been no studies seeking to evaluate the usefulness of the exam regarding an applicants' ability to match with a residency program through the Postdoctoral Dental Matching Program (MATCH). The aim of this study was to evaluate the impact of the Advanced Dental Admission Test performance on student MATCH success into a post-doctoral pediatric residency program. METHODS: This retrospective study evaluated the academic records of pediatric residency applicants using the ADEA PASS and MATCH program between 2017 and 2019. Five scholastic and 7 demographic variables were extracted from student ADEA PASS applications. Applicant MATCH status and preference was obtained from the Postdoctoral Dental Matching Program. Descriptive statistics for each application cycle was calculated and used to evaluate applicant demographic and scholastic data. Correlation coefficients assessed for associations between scholastic/demographic factors and MATCH status/preference. Logistic regression models estimated the probability of MATCH status/preference. Significance was set at 5%. RESULTS: An association was found between ADAT scores and MATCH status, but the influence was minimal (odds ratio: 1.004, 95% confidence interval: 1.001-1.008). Applicant age (P < 0.0216) and dental schools that ranked students (P < 0.0002) were the most significant factors for MATCH status and preference, respectively. CONCLUSIONS: ADAT scores played a minimal role in applicants matching to pediatric residency programs. Applicant age and schools that provide class ranks were found to be significant predictors when considering MATCH status and preference to pediatric residency programs.

A visual evaluation of oral plaque removal utilizing an adjunct enzyme pre-rinse in orthodontic subjects.

OBJECTIVE: To determine if an adjunct proteolytic pre-rinse along with contemporary methods of dental cleaning may more effectively remove visual plaque in subjects with fixed orthodontic appliances. MATERIALS AND METHODS: Forty-three orthodontic subjects, ages 10 to 25, completed this single site, double-blind, crossover clinical trial. Subjects randomly received bromelain enzyme or a powdered-sugar placebo pre-rinse, followed by manual tooth brushing and use of a Waterpik. Subjects received the alternate pre-rinse during the subsequent visit. Baseline and residual plaque accumulation were recorded via disclosing tablet and digital photography. A single, blinded examiner scored visual plaque scores from randomized photographs. Treatment effects on composite plaque score were evaluated using repeated-measures analysis of variance. A 5% significance level was used for all tests. RESULTS: No significant differences in plaque scores were noted at baseline or post-rinse between the enzyme and placebo. The changes from baseline to post-rinse (P = .190), post-brushing (P = .764), and post-Waterpik (P = .882) were not significantly different between interventions. Significant reduction in plaque scores were observed in both arms of the study after brushing (P < .01) and waterjet use (P < .01). Neither age (P = .220) nor gender (P = .449) impacted plaque scores. CONCLUSIONS: Use of a bromelain enzyme pre-rinse alone did not significantly enhance plaque removal. A significant reduction in retained plaque was observed with the application of brushing and or Waterpik.

Is There a Correlation Between Airway Volume and Maximum Constriction Area Location in Different Dentofacial Deformities?

PURPOSE: The purpose of the present study was to correlate the airway volume and maximum constriction area (MCA) with the type of dentofacial deformity in patients who required orthognathic surgery. MATERIALS AND METHODS: The present retrospective cohort study included orthognathic surgery patients selected from the private practice of one of us. The selected cases were stratified into 5 different groups according to the clinical and cephalometric diagnosis of their dentofacial deformity. The preoperative airway volume and anatomic location of the MCA were calculated using the airway tool of the Dolphin Imaging software module (Dolphin Imaging and Management Solutions, Chatsworth, CA) and correlated with the diagnosed dentofacial deformity. Differences in the pretreatment airway volumes and MCA location were compared among the deformities. RESULTS: The MCA location was more often the nasopharynx for maxillary deficiency and the oropharynx for mandibular deficiency deformities. The nasopharynx volume was significantly smaller statistically (P < .005) for maxillary deficiency plus mandibular excess compared with mandibular deficiency. The hypopharynx volume was significantly smaller statistically (P < .005) for vertical maxillary excess plus mandibular deficiency than for both maxillary deficiency and maxillary deficiency plus mandibular excess. No statistically significant difference was found among the different deformity groups in relation to the mean airway volume (P > .005). CONCLUSIONS: The location of the airway MCA seems to have a strong correlation with the horizontal position of the maxilla and mandible. The MCA in maxillary deficiencies (isolated or combined) was in the nasopharynx, and the MCA in mandibular deficiencies (isolated or combined) was in the oropharynx. Clinicians should consider these anatomic findings when planning the location and magnitude of orthognathic surgery movements to optimize the outcomes.

Precision of the virtual occlusal record.

OBJECTIVES: To evaluate the precision of the virtual occlusal record using the Carestream CS3600 Intraoral Scanner (Carestream Dental, Atlanta, Ga). MATERIALS AND METHODS: A total of 20 participants were recruited for this prospective study using preestablished inclusion/exclusion criteria. A complete intraoral scan and two bite registrations were obtained. The participants were instructed to bite with normal pressure when bite registrations were acquired. Contact locations, size (circumference), and intensity were identified on the maxillary first molars and canines. Agreement between contact size and intensity was assessed with intraclass correlation coefficients. Kappa statistics evaluated agreement in contact locations. Statistical significance was set at P < .05. RESULTS: All participant data were included for statistical analysis. Between the two bite registrations, nonstatistically significant differences were observed in the proportion of locations with contacts (P = .7681). A nonstatistically significant difference (-0.25 mm, P = .8416) in mean contact circumference size was observed. A statistically significant difference in mean contact intensity was observed (P = .0448). When evaluating agreement between the bite registrations, a weak correlation for size (intraclass correlation coefficient = 0.35) and intensity (intraclass correlation coefficient = 0.32) was observed as well as a moderate agreement for contact location (κ coefficient = 0.67). CONCLUSIONS: The findings suggest that the Carestream intraoral scanner software possesses adequate precision when acquiring the location and size of the contacts in bite registrations. The scanner failed to demonstrate adequate precision when acquiring contact intensities in bite registrations. Additional research is warranted to further investigate the precision of virtual occlusal records with currently available software systems.

Retrospective CBCT analysis of airway volume changes after bone-borne vs tooth-borne rapid maxillary expansion.

OBJECTIVES: To compare changes in upper airway volume after maxillary expansion with bone- and tooth-borne appliances in adolescents and to evaluate the dentoskeletal effects of each expansion modality. MATERIALS AND METHODS: This retrospective study included 36 adolescents who had bilateral maxillary crossbite and received bone-borne maxillary expansion (average age: 14.7 years) or tooth-borne maxillary expansion (average age: 14.4 years). Subjects had two cone beam computed tomography images acquired, one before expansion (T1) and a second after a 3-month retention period (T2). Images were oriented, and three-dimensional airway volume and dentoskeletal expansion were measured. Analysis of variance was used to test for differences between the two expansion methods for pretreatment, posttreatment, and prepost changes. Paired t-tests were used to test for significance of prepost changes within each method. RESULTS: Both groups showed significant increase only in nasal cavity and nasopharynx volume (P < .05), but not oropharynx and maxillary sinus volumes. Intermolar and maxillary width increased significantly in both groups (P < .05); however, the buccal inclination of maxillary molars increased significantly only in the tooth-borne group (P < .05). There was no significant difference between tooth- and bone-borne expansion groups, except for the significantly larger increase in buccal inclination of the maxillary right first molar after tooth-borne expansion. CONCLUSIONS: In adolescents, both tooth- and bone-borne RME resulted in an increase in nasal cavity and nasopharynx volume, as well as expansion in maxillary intermolar and skeletal widths. However, only tooth-borne expanders caused significant buccal tipping of maxillary molars.

Predictors of orthodontic residency performance: An assessment of scholastic and demographic selection parameters.

OBJECTIVE: To evaluate the association between resident selection criteria, including Graduate Record Examination (GRE) scores, and student performance in an orthodontic residency program. MATERIALS AND METHODS: This retrospective study evaluated the academic records of 70 orthodontic residency graduates from the Indiana University School of Dentistry. The following demographic and scholastic data were extracted from the student academic records: applicant age, gender, ethnicity, race, country of origin, dental school graduation year, GRE score, and graduate orthodontic grade point average (GPA). In addition, student American Board of Orthodontics (ABO) written examination quintiles were obtained from the ABO. Scatterplots, analysis of variance, and correlation coefficients were used to analyze the data. Statistical significance was established at .05 for the study. RESULTS: No associations were found with any component of the GRE, except with the quantitative GRE section, which displayed a weak association with ABO module 2 scores. Dental school GPA demonstrated weak correlations with all ABO modules and moderate correlations with overall and didactic orthodontic GPAs. When assessing demographic factors, significant differences (P < .05) were observed, with the following groups demonstrating higher performance on certain ABO modules: age (younger), race (whites), and country of origin (US citizens). CONCLUSIONS: Findings suggest the GRE has no association with student performance in an orthodontic residency. However, dental school GPA and/or class rank appear to be the strongest scholastic predictors of residency performance.

Preliminary Performance of the Advanced Dental Admission Test (ADAT): Association Between ADAT Scores and Other Variables for Applicants to Residency Programs at a U.S. Dental School.

Historically, dental residency programs have used numerical assessment criteria to evaluate and identify qualified candidates for admission. Recent elimination of such assessment tools has undermined many programs' holistic evaluation process. The Advanced Dental Admission Test (ADAT) was developed and recently piloted in hopes of addressing this issue. The aim of this study was to evaluate the preliminary performance and validity of the ADAT by exploring the association between ADAT scores and other variables for a sample of applicants to residency programs. The WebAdMIT admissions database was used to identify the test scores and educational and demographic information of 92 individuals who completed the pilot ADAT and were seeking a 2017 postgraduate specialty position at Indiana University School of Dentistry. The results showed that the ADAT had strong to weak correlations with certain applicant variables (p<0.05). No significant differences were found for age, race, school location, or country of origin. However, males performed better than females (p<0.05), and non-Hispanics performed better than Hispanics (p<0.01). ADAT component scores were also higher for individuals with a history of research activity (p<0.05). This study found that significant associations existed between the ADAT and indices typically associated with competitive applicants. These findings suggest that the ADAT may serve as a useful numerical assessment instrument, with the potential to identify high-performing candidates. Furthermore, the ADAT seemed to be a plausible option for programs seeking to incorporate a quantitative assessment instrument as part of a holistic candidate selection process.

Risk factors contributing to gingival recession among patients undergoing different orthodontic treatment modalities.

OBJECTIVE: The aim of this study was to investigate the risk factors contributing to gingival recession among patients undergoing orthodontic treatment. METHODS: Records of 100 Caucasian patients who completed orthodontic treatment were evaluated before and after treatment. Intercanine and molar widths, arch perimeter, arch depth, and keratinized gingival height were measured for both arches. The association of orthodontic treatment strategy (changing incisal inclination, expansion, and extraction), keratinized gingival height, and various other measurements with gingival recession was evaluated by using generalized linear mixed models with logistic regression analysis. RESULTS: For each 1 mm increase in pre- and post-treatment keratinized gingival height, there was 0.77 and 0.51 times lower odds of gingival recession. For each 1 mm increase in post-treatment intercanine width, there was 0.80 times lower odds of gingival recession. And for each 1 mm increase in change in the arch depth, there was 1.16 times higher odds of gingival recession. For each 1 mm increase in pre- and post-treatment mandibular symphysis width, there was 0.47 and 0.39 times lower odds of gingival recession. CONCLUSION: Regardless of the type of orthodontic treatment, increased keratinized gingival height, mandibular symphysis width, and post-treatment intercanine width lower the risk of gingival recession.

Accuracy of three-dimensional dental resin models created by fused deposition modeling, stereolithography, and Polyjet prototype technologies: A comparative study.

OBJECTIVES: The aim of this study was to assess the dimensional accuracy of fused deposition modeling (FDM)-, Polyjet-, and stereolithography (SLA)-produced models by comparing them to traditional plaster casts. MATERIALS AND METHODS: A total of 12 maxillary and mandibular posttreatment orthodontic plaster casts were selected from the archives of the Orthodontic Department at the Indiana University School of Dentistry. Plaster models were scanned, saved as stereolithography files, and printed as physical models using three different three-dimensional (3D) printers: Makerbot Replicator (FDM), 3D Systems SLA 6000 (SLA), and Objet Eden500V (Polyjet). A digital caliper was used to obtain measurements on the original plaster models as well as on the printed resin models. RESULTS: Comparison between the 3D printed models and the plaster casts showed no statistically significant differences in most of the parameters. However, FDM was significantly higher on average than were plaster casts in maxillary left mixed plane (MxL-MP) and mandibular intermolar width (Md-IMW). Polyjet was significantly higher on average than were plaster casts in maxillary intercanine width (Mx-ICW), mandibular intercanine width (Md-ICW), and mandibular left mixed plane (MdL-MP). Polyjet was significantly lower on average than were plaster casts in maxillary right vertical plane (MxR-vertical), maxillary left vertical plane (MxL-vertical), mandibular right anteroposterior plane (MdR-AP), mandibular right vertical plane (MdR-vertical), and mandibular left vertical plane (MdL-vertical). SLA was significantly higher on average than were plaster casts in MxL-MP, Md-ICW, and overbite. SLA was significantly lower on average than were plaster casts in MdR-vertical and MdL-vertical. CONCLUSIONS: Dental models reconstructed by FDM technology had the fewest dimensional measurement differences compared to plaster models.

Three-dimensional evaluation of airway volume changes in two expansion activation protocols.

The purpose of this study was to evaluate the airway volume changes associated with rapid maxillary expansion (RME) protocols using different activation rates. A sample of forty RME treated cases was classified into two groups according to the rate of RME activation (Group A: 0.8mm per day and Group B: 0.5mm per day). Three-dimensional images were obtained for each case before and three months after expansion. Dolphin imaging software was used to identify landmarks and calculate airway volumes. Intraclass correlation coefficient was used to confirm reliability and Wilcoxon signed rank tests were used for comparison between the initial and final measurements within each group and between groups. Significant increase in the nasal cavity volume for both groups was observed (P<0.0001 and P=0.001 for groups A and B respectively). The increase in nasopharynx volume was significant in the group with a more rapid activation rate (P=0.0006). Significant differences between the two groups in post-treatment changes were detected in the nasal cavity volume (P<0.0001), nasopharynx volume (P=0.0035), and soft palate area (P=0.0081). A more rapid activation rate results in a higher volume increase for the nasal cavity and nasopharynx than a slower activation rate.