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.

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 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.

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.

Outcome of using vaginal misoprostol for treatment of retained products of conception after first trimester miscarriage: a retrospective cohort study

PURPOSE

Standard treatment for retained products of conception (RPOC) is dilation and curettage (D&C), however, this brings a risk of intrauterine synechiae and subsequent fertility issues. A treatment strategy to avoid D&C is medical management with misoprostol. The justification for misoprostol in this setting is extrapolated from miscarriage and termination literature, however, no studies have looked specifically in the setting of RPOC. The purpose of this study is to determine the efficacy of misoprostol as definitive management of RPOC.

MATERIALS AND METHODS

A retrospective cohort study was conducted from January 2016 to March 2017 at an Early Pregnancy Assessment Clinic. Patients diagnosed with RPOC with clinical symptoms and ultrasound findings of endometrial mass and/or doppler flow treated expectantly, medically with vaginal misoprostol or with a suction D&C underwent a chart review. Primary outcome was resolution of RPOC without surgical intervention.

RESULTS AND CONCLUSIONS

Of 1743 unique pregnancies, 189 women were diagnosed with RPOC. 34% (65/178) chose misoprostol for management of RPOC. Baseline demographics between the three treatment modalities (expectant, medical, surgical) were comparable. 65% (42/65) of patients who took misoprostol avoided D&C. Misoprostol is most effective (76%) in the setting of RPOC if the primary treatment for miscarriage was expectant management, with less success with primary medical management (44%) and primary surgical management (40%).

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.

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.

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.

Microdamage generation by tapered and cylindrical mini-screw implants after pilot drilling

OBJECTIVE

To investigate the relationship between mini-screw implant (MSI) diameter (1.6 vs 2.0 mm) and shape (tapered vs cylindrical) and the amount of microdamage generated during insertion.

MATERIALS AND METHODS

Thirty-six cylindrical and 36 tapered MSIs, 6 mm long, were used in this study. Half of each shape was 1.6 mm in diameter, while the other half was 2.0 mm. After pilot drilling, four and five MSIs were inserted, respectively, into fresh cadaveric maxillae and mandibles of dogs. Bone blocks containing the MSIs were sectioned and ground parallel to the MSI axis. Epifluorescent microscopy was used to measure overall cortical thickness, crack length, and crack number adjacent to the MSI. Crack density and total microdamage burden per surface length were calculated. Three-way analysis of variance (ANOVA) was used to test the effects of jaw, and MSI shape and diameter. Pairwise comparisons were made to control the overall significance level at 5%.

RESULTS

The larger (2.0 vs 1.6 mm) cylindrical MSIs increased the numbers, lengths, and densities of microcracks, and the total microdamage burden. The same diameter cylindrical and tapered MSIs generated a similar number of cracks and crack lengths. More total microdamage burden was created by the 2.0-mm cylindrical than the 2.0-mm tapered MSIs. Although higher crack densities were produced by the insertion of 1.6-mm tapered MSIs, there was no difference in total microdamage burden induced by 1.6-mm tapered and 1.6-mm cylindrical MSIs.

CONCLUSIONS

Pilot drilling is effective in reducing microdamage during insertion of tapered MSIs. To prevent excessive microdamage, large diameter and cylindrical MSIs should be avoided.

Comparison of stainless steel and titanium alloy orthodontic miniscrew implants: a mechanical and histologic analysis

INTRODUCTION

The detailed mechanical and histologic properties of stainless steel miniscrew implants used for temporary orthodontic anchorage have not been assessed. Thus, the purpose of this study was to compare them with identically sized titanium alloy miniscrew implants.

METHODS

Forty-eight stainless steel and 48 titanium alloy miniscrew implants were inserted into the tibias of 12 rabbits. Insertion torque and primary stability were recorded. One hundred grams of tensile force was applied between half of the implants in each group, resulting in 4 subgroups of 24 specimens each. Fluorochrome labeling was administered at weeks 4 and 5. When the rabbits were euthanized at 6 weeks, stability and removal torque were measured in half (ie, 12 specimens) of each of the 4 subgroups. Microdamage burden and bone-to-implant contact ratio were quantified in the other 12 specimens in each subgroup. Mixed model analysis of variance was used for statistical analysis.

RESULTS

All implants were stable at insertion and after 6 weeks. The only significant difference was the higher (9%) insertion torque for stainless steel. No significant differences were found between stainless steel and titanium alloy miniscrew implants in microdamage burden and bone-to-implant contact regardless of loading status.

CONCLUSIONS

Stainless steel and titanium alloy miniscrew implants provide the same mechanical stability and similar histologic responses, suggesting that both are suitable for immediate orthodontic clinical loads.

Three-dimensional quantification of pretorqued nickel-titanium wires in edgewise and prescription brackets

OBJECTIVE

To quantify the three-dimensional moments and forces produced by pretorqued nickel-titanium (NiTi) rectangular archwires fully engaged in 0.018- and 0.022-inch slots of central incisor and molar edgewise and prescription brackets.

MATERIALS AND METHODS

Ten identical acrylic dental models with retroclined maxillary incisors were fabricated for bonding with various bracket-wire combinations. Edgewise, Roth, and MBT brackets with 0.018- and 0.022-inch slots were bonded in a simulated 2 × 4 clinical scenario. The left central incisor and molar were sectioned and attached to load cells. Correspondingly sized straight and pretorqued NiTi archwires were ligated to the brackets using 0.010-inch ligatures. Each load cell simultaneously measured three force (Fx, Fy, Fz) and three moment (Mx, My, Mz) components. The faciolingual, mesiodistal, and inciso-occluso/apical axes of the teeth corresponded to the x, y, and z axes of the load cells, respectively. Each wire was removed and retested seven times. Three-way analysis of variance (ANOVA) examined the effects of wire type, wire size, and bracket type on the measured orthodontic load systems. Interactions among the three effects were examined and pair-wise comparisons between significant combinations were performed.

RESULTS

The force and moment components on each tooth were quantified according to their local coordinate axes. The three-way ANOVA interaction terms were significant for all force and moment measurements (P < .05), except for Fy (P > .05).

CONCLUSION

The pretorqued wire generates a significantly larger incisor facial crown torquing moment in the MBT prescription compared to Roth, edgewise, and the straight NiTi wire.

Personality traits as a potential predictor of willingness to undergo various orthodontic treatments

Objective:

To establish an association between patient personality traits and potential willingness to undergo various orthodontic treatments.

Materials and Methods:

One hundred adolescent individuals aged 12–16 years completed an anonymous electronic questionnaire via Survey Monkey. The 24-item questionnaire contained three major sections: patient demographics, a modified Big Five Inventory (BFI)-10 personality index, and a willingness to undergo treatment assessment. Multiple-variable linear regression analyses were used to determine the associations among age, gender, ethnicity, and the five personality traits simultaneously with willingness to undergo treatment. Statistical significance was set at P ≤ .05.

Results:

Ninety-six of the 100 individuals were included in the statistical analysis. Age, ethnicity, and gender failed to correlate with potential willingness to undergo orthodontic treatment. Several personality dimensions within the modified BFI-10 (agreeableness, conscientiousness, and neuroticism) were significantly associated with willingness to undergo various orthodontic treatments (P ≤ .05). Agreeableness demonstrated positive correlations with five treatment modalities, while both conscientiousness and neuroticism exhibited negative associations with a single treatment modality. Openness and extraversion were the only personality dimensions that failed to associate with any of the treatment modalities. Four of the nine treatment modalities had no association with patient demographics or a patient's personality dimensions.

Conclusions:

Personality traits are useful in predicting a patient's potential willingness to participate in various orthodontic treatments. The agreeableness dimension provided the most utility in predicting patient willingness. Age, ethnicity, and gender were not significant in predicting patient willingness.

The effects of varying alcohol concentrations commonly found in mouth rinses on the force decay of elastomeric chain

OBJECTIVE

To test the effect of alcohol on force decay of elastomeric chains in vitro in order to determine if increasing alcohol concentrations results in an increased amount of elastomeric chain force decay.

MATERIALS AND METHODS

A prospective laboratory study was completed to test the effect of alcohol exposure on orthodontic elastomeric chain. A total of 450 specimens were divided into five test groups. Two test groups were each exposed to different alcohol concentrations (14% and 26.9%) and the other two test groups were exposed to different commercially available mouth rinses (Cēpacol -14% alcohol and Listerine - 26.9% alcohol) for 60 seconds twice a day. The control group followed all of the same procedures but was only exposed to deionized (DI) water. Force measurements were taken at six time points (initial, 1 day, 7 days, 14 days, 21 days, and 28 days).

RESULTS

There were no significant differences among groups at the initial time point (P  =  .52). Statistically significant effects of time on force decay were seen in all groups. All test groups showed significantly more force decay than the control group. Only a few statistically significant differences were observed when comparing force decay among the test groups.

CONCLUSIONS

Alcohol causes an increase in force decay of elastomeric chain over time. A concentration dependence of alcohol on force decay of elastomeric chain was not observed.

The effects of application time of a self-etching primer and debonding methods on bracket bond strength

OBJECTIVE

To test the manufacturer's recommendation for the application rubbing time of a self-etching primer (Transbond Plus, 3M Unitek) and to compare the resulting bond strength of a resin composite (Transbond XT, 3M Unitek) in the traditional laboratory tension on all four wings with a simulation of the clinical single-wing lift-off debonding instrument (LODI; 3M Unitek).

MATERIALS AND METHODS

Flattened stainless-steel maxillary incisor orthodontic brackets (Victory Series, 3M Unitek) were bonded to 108 flattened bovine incisors. The enamel was rubbed with the self-etching primer for 0, 5 (the manufacturer's recommendation), and 10 seconds during a 10-second application. Traditional four-wing and LODI simulated debonding forces and the adhesive remnant index (ARI) were recorded.

RESULTS

One-way analysis of variance testing among rubbing times and debonding methods indicated a significant difference in strength with 0 and 5 seconds of rubbing and between traditional and LODI simulated tension. The bond strengths were higher in the ARI  =  1 subset compared to the ARI  =  3-5 subsets.

CONCLUSIONS

The manufacturer's recommendation for primer rubbing time produced the highest bond strength. Less force is required for debonding when tension is applied to one wing (LODI simulation) vs on all four wings.

The effect of pH levels on nonlatex vs latex interarch elastics

OBJECTIVE

To evaluate the force decay characteristics of nonlatex vs latex interarch elastics within the normal range of salivary pH levels.

MATERIALS AND METHODS

Two nonlatex groups and one latex quasi-control group were tested. Elastics were stretched to 15 mm and were held for 10 seconds (baseline), 4 hours, 8 hours, and 12 hours in artificial saliva solutions with pH levels of 5.0, 6.0, and 7.5. Force magnitudes were measured at 25 mm of activation. Each specimen was used once. Measurements were assessed using three-way analysis of variance (ANOVA).

RESULTS

The three-way interaction between group, pH, and time was not significant (P = .13); the group-by-pH interaction also was not significant (P = .70). However, pH-by-time (P = .0179) and group-by-time (P = .0001) interactions were significant. American Orthodontics nonlatex generated significantly higher loads than Auradonics nonlatex. American Orthodontics nonlatex produced significantly higher forces than American Orthodontics latex at 4, 8, and 12 hours, but not at 10 seconds. American Orthodontics latex was significantly stronger than Auradonics nonlatex at 10 seconds, but not at 4, 8, and 12 hours.

CONCLUSIONS

No clinically significant correlation between pH and force decay was observed.

Light treatment for NASA shiftworkers

Intense artificial light can phase-shift circadian rhythms and improve performance, sleep, and well-being during shiftwork simulations. In real shiftworkers, however, exposure to sunlight and other time cues may decrease the efficacy of light treatment, and occupational and family responsibilities may make it impractical. With these considerations in mind, we designed and tested light-treatment protocols for NASA personnel who worked on shifted schedules during two Space Shuttle missions. During the prelaunch week, treatment subjects self-administered light of approximately 10,000 lux at times of day that phase-delay circadian rhythms. Treatment continued during the missions and for several days afterward. No treatment was administered to subjects in the control group. Treatment subjects reported better sleep, performance, and physical and emotional well-being than control subjects and rated the treatment as highly effective for promoting adjustment to their work schedules. Light treatment is both feasible and beneficial for NASA personnel who must work on shifted schedules during Space Shuttle missions.

Dark goggles and bright light improve circadian rhythm adaptation to night-shift work

We compared the contributions of bright light during the night shift and dark goggles during daylight for phase shifting the circadian rhythm of temperature to realign with a 12-hour shift of sleep. After 10 baseline days there were 8 night-work/day-sleep days. Temperature was continuously recorded from 50 subjects. There were four groups in a 2 x 2 design: light (bright, dim), goggles (yes, no). Subjects were exposed to bright light (about 5,000 lux) for 6 hours on the first 2 night shifts. Dim light was < 500 lux. Both bright light and goggles were significant factors for producing circadian rhythm phase shifts. The combination of bright light plus goggles was the most effective, whereas the combination of dim light and no goggles was the least effective. The temperature rhythm either phase advanced or phase delayed when it aligned with daytime sleep. However, when subjects did not have goggles only phase advances occurred. Goggles were necessary for producing phase delays. The most likely explanation is that daylight during the travel-home window after a night shift inhibits phase-delay shifts, and goggles can prevent this inhibition. Larger temperature-rhythm phase shifts were associated with better subjective daytime sleep, less subjective fatigue and better mood.

3-(2-Carboxyindol-3-yl)propionic acid-based antagonists of the N-methyl-D-aspartic acid receptor associated glycine binding site

A series of substituted 3-(2-carboxyindol-3-yl)propionic acids was synthesized and tested as antagonists for the strychnine-insensitive glycine binding site of the NMDA receptor. Chlorine, and other small electron-withdrawing substituents in the 4- and 6-positions of the indole ring, greatly enhanced binding and selectivity for the glycine site over the glutamate site of the NMDA receptor; one of the most potent compounds is 3-(4,6-dichloro-2-carboxyindol-3-yl)propionic acid (IC50 = 170 nM; greater than 2100-fold selective for glycine). The importance of a heteroatom NH and the enhancing effect of the propionic acid side chain were demonstrated and are consistent with previous results which suggest the presence of a pocket on the receptor which can accept an acidic side chain. Substitution of a sulfur at C3 led to the most potent compound 3-[(carboxymethyl)thio]-2-carboxy-4,6-dichloroindole (IC50 = 100 nM).

Effects of green or white light for treatment of seasonal depression

Twelve subjects with winter depression were treated with equal quanta of green or white light in a randomized crossover study. Each treatment condition consisted of 2 hours of exposure each morning for 1 week, with at least 1 interventing week without treatment. Ratings made without knowledge of treatment condition were done before and after each condition. Both treatments significantly reduced depression ratings. White light was significantly more effective than green light in reducing endogenous symptoms, but not the "atypical" symptoms that are common features of winter depression. Furthermore, sequence of treatment conditions influenced antidepressant responses. Broad-band white light may be optimal for maximizing therapeutic response.

Circadian rhythmicity and behavioral depression: I. Effects of stress

Rats were exposed to repeated sessions of inescapable footshock, and behavioral depression was subsequently assessed by measuring escape performance during exposure to escapable shock in a different testing environment. Free-running circadian activity rhythms were assessed using running wheels for approximately three weeks before and after administration of inescapable shock. Several animals showed lengthening of free-running period and decreases in activity level following shock. Similar effects were also seen in rats that were removed from their running wheels, placed within the shock apparatus, and not given shock, but not in nonhandled control animals. Furthermore, period lengthening in shocked and handled rats was positively correlated with escape performance, suggesting that circadian rhythm alterations occurred in those animals that were best able to cope with shock or handling-related stressors. In contrast, individual differences in circadian period and activity level during baseline conditions were not predictive of either escape performance or circadian rhythm alterations. These results suggest that successful behavioral adaptation to stress may be associated with alterations of circadian rhythmicity.

Circadian rhythmicity and behavioral depression: II. Effects of lighting schedules

Two studies explore the relationship between rhythmicity and behavioral depression. Behavioral depression was induced using inescapable footshock, and assessed by measuring subsequent responses to escapable shock, in rats housed under different light-dark conditions. Experiment 1 compared escape performance in free-running and entrained animals following inescapable shock. Free-running and entrained animals did not exhibit differential vulnerability to the effects of inescapable shock. In addition, there were no systematic effects on phase following shock. However, several free-running animals showed increased circadian period following shock, and lengthening of period was significantly correlated with escape performance. Individual differences in baseline period or phase were not predictive of escape performance. In Experiment 2, "aftereffects" of entrainment to long or short light-dark cycles were utilized to create groups of animals with long or short free-running periods. After the administration of inescapable shock, escape performance was tested. There were no significant differences among experimental groups in escape performance. These results suggest that plasticity of circadian period, but not baseline period per se, may be associated with the ability to adapt to environmental challenges.

Thyroparathyroidectomy produces a progressive escape deficit in rats

Abnormal thyroid status and affective disorders have been associated in the human clinical literature. It has recently been shown that pretreatment with thyroid hormone can prevent escape deficits produced by inescapable shock in an animal analogue of depression. In this report we provide evidence that hypothyroid status can produce an escape deficit in rats. While sham-operated rats improved their performance on a simple escape task over three days of testing, thyroparathyroidectomized rats showed a pronounced decrease in their responses. Markov transition analysis was used to obtain conditional probabilities of escaping given a prior escape or failure to escape for the two groups. This analysis shows that the structure of the data set may be similar for the two groups. These results suggest that if intact rats learn to escape, then hypothyroid rats may learn not to escape.

2- versus 4-hour evening phototherapy of seasonal affective disorder

Seasonal affective disorder (SAD) has been successfully treated with bright light, and morning exposure has been deemed more effective than exposure at other times. Evening treatment may offer a practical advantage, but the optimal duration of exposure has not been established. Six SAD patients were treated at home for 1 week with 2500 lux of light given either from 6 p.m. to 8 p.m. or from 6 p.m. to 10 p.m. using a counterbalanced crossover design with a minimal withdrawal period of 1 week between conditions. Both treatments were effective in reversing SAD symptoms, but neither treatment was superior. These results suggest that evening phototherapy for as little as 2 hours may be a useful and reasonable alternative for the treatment of SAD.

Light-induced plasma melatonin suppression in seasonal affective disorder

1. Subjects with seasonal affective disorder were exposed to 0, 500 and 1000 lux of white light for one hour beginning at 0300 hours. 2. Plasma samples were taken periodically and analysed for melatonin. 3. Plasma melatonin levels were suppressed by exposure to both 500 and 1000 lux light levels, suggesting that SAD patients show no neuroendocrine insensitivity to light but may show supersensitive responses to light.

Treatment of winter depression with a portable, head-mounted phototherapy device

1. A portable, head-mounted device was developed for administration of light therapy. A randomized crossover protocol was used to test the therapeutic efficacy of this device, compared to a standard light box, for treatment of winter depression. 2. Depressive symptoms were significantly reduced by both the head-mounted device and the light box. 3. Therapeutic efficacy of the two devices was not significantly different. 4. The head-mounted device was rated by patients as significantly more convenient than the conventional light box; this may be important in improving patient compliance.

Interactions between nocturnal feeding and wheel running patterns in the rat

The purpose of this experiment was to investigate the relationship between daily patterns of wheel running activity and feeding behavior. Wheel running and bar pressing for food were continuously recorded from rats which had concurrent access to both wheels and food. In a second condition, wheel running and (non-reinforced) bar pressing were recorded during food deprivation. In a third condition, bar pressing for food was recorded while wheel running was prevented. During ad lib access to wheels and food, both behaviors occurred primarily during the dark phase of the light-dark cycle. However, the nocturnal distribution of these responses differed: the early dark hours were primarily devoted to running, while feeding occurred in small, frequent meals. Maximal food intake occurred during the late dark hours, when meals were larger and less frequent, and there was little running. During three days of complete food deprivation, both wheel running and meal initiation attempts (as indicated by nonreinforced bar pressing) maintained their normal daily patterns. However, during wheel deprivation, changes occurred in the temporal distribution of meals which equalized early and late dark food intake. These results show that the availability of an alternative activity, like wheel running, can be an important determinant of daily feeding patterns. However, the daily pattern of wheel running is not influenced by food availability. Different behaviors may show differential plasticity in the coordination of an overall daily behavioral program.

(2-Piperidine)- and (2-pyrrolidine)ethanones and -ethanols as inhibitors of blood platelet aggregation

(E)-4-[4-(Methylthio)phenyl]-1-(2-piperidinyl)-3-buten-2-one hydrochloride (44, RMI 14 133A) was found to inhibit ADP-induced aggregation of blood platelets. It was selected from a large series of (2-piperidinyl)- and (2-pyrrolidinyl)ethanones synthesized by a modified Schopf reaction from enolate magnesium salts of beta-keto acids and 2,3,4,5-tetrahydropyridine trimer or 3,4-dihydro-2H-pyrrole trimer, respectively. Evaluation of the compounds was carried out in vitro on human blood platelets. Structure-activity relationships are discussed. 44 also inhibited platelet aggregation ex vivo in guinea pigs. Subacute toxicity evaluation in dogs and guinea pigs showed it to have an unfavorable therapeutic ratio. 1-[4'-Chloro(1,1'-biphenyl)-4-yl-a1-2-(2-piperdinyl)ethanone hydrochloride (18, RMI 12436A) was found to lower serum cholesterol levles in rats with concurrent accumulation of (3beta)-cholesta-5,7-dien-3-ol, suggesting inhibition of 7-dehydrocholesterol delta7-reductase.