Caroline K. Carrico

Characterization of Weighted Quantile Sum Regression for Highly Correlated Data in a Risk Analysis Setting

In risk evaluation, the effect of mixtures of environmental chemicals on a common adverse outcome is of interest. However, due to the high dimensionality and inherent correlations among chemicals that occur together, the traditional methods (e.g. ordinary or logistic regression) suffer from collinearity and variance inflation, and shrinkage methods have limitations in selecting among correlated components. We propose a weighted quantile sum (WQS) approach to estimating a body burden index, which identifies “bad actors” in a set of highly correlated environmental chemicals. We evaluate and characterize the accuracy of WQS regression in variable selection through extensive simulation studies through sensitivity and specificity (i.e., ability of the WQS method to select the bad actors correctly and not incorrect ones). We demonstrate the improvement in accuracy this method provides over traditional ordinary regression and shrinkage methods (lasso, adaptive lasso, and elastic net). Results from simulations demonstrate that WQS regression is accurate under some environmentally relevant conditions, but its accuracy decreases for a fixed correlation pattern as the association with a response variable diminishes. Nonzero weights (i.e., weights exceeding a selection threshold parameter) may be used to identify bad actors; however, components within a cluster of highly correlated active components tend to have lower weights, with the sum of their weights representative of the set.Supplementary materials accompanying this paper appear on-line.

A Cohort study evaluation of maternal PCB exposure related to time to pregnancy in daughters

BackgroundPolychlorinated biphenyls (PCBs) remain ubiquitous environmental contaminants. Developmental exposures are suspected to impact reproduction. Analysis of mixtures of PCBs may be problematic as components have a complex correlation structure, and along with limited sample sizes, standard regression strategies are problematic. We compared the results of a novel, empirical method to those based on categorization of PCB compounds by (1) hypothesized biological activity previously proposed and widely applied, and (2) degree of ortho- substitution (mono, di, tri), in a study of the relation of maternal serum PCBs and daughter’s time to pregnancy.MethodsWe measured PCBs in maternal serum samples collected in the early postpartum in 289 daughters in the Child Health and Development Studies birth cohort. We queried time to pregnancy in these daughters 28–31 years later. We applied a novel weighted quantile sum approach to find the bad-actor compounds in the PCB mixture found in maternal serum. The approach includes empirical estimation of the weights through a bootstrap step which accounts for the variation in the estimated weights.ResultsBootstrap analyses indicated the dominant functionality groups associated with longer TTP were the dioxin-like, anti-estrogenic group (average weight, 22%) and PCBs not previously classified by biological activity (54%). In contrast, the unclassified PCBs were not important in the association with shorter TTP, where the anti-estrogenic groups and the PB-inducers group played a more important role (60% and 23%, respectively). The highly chlorinated PCBs (average weight, 89%) were mostly associated with longer TTP; in contrast, the degree of chlorination was less discriminating for shorter TTP. Finally, PCB 56 was associated with the strongest relationship with TTP with a weight of 47%.ConclusionsOur empirical approach found some associations previously identified by two classification schemes, but also identified other bad actors. This empirical method can generate hypotheses about mixture effects and mechanisms and overcomes some of the limitations of standard regression techniques.

Burnout, depression and suicidal ideation in dental and dental hygiene students

INTRODUCTION The aim of this study was to assess the relationship between burnout, depressive symptoms and suicidal ideation in dental and dental hygiene students and to evaluate the influence of gender, programme type and year of study. SUBJECTS AND METHODS Third- and fourth-year dental (DS) and first- and second-year hygiene students (DHS) completed the Patient Health Questionnaire (PHQ-9) and an abbreviated Maslach Burnout Inventory online as measures of depressive symptoms/suicidality and burnout, respectively. The statistical analyses included summary statistics and tests for intergroup comparisons (chi-square) to evaluate the influence of gender, programme type (DHS or DS) and year of study. Correlations between depression, suicidality and burnout were also conducted. RESULTS A total of 32 dental hygiene and 119 dental students participated. 40% of the dental and 38% of the hygiene students met criteria for burnout. No differences were found between years or between programmes. Nine per cent of both dental and hygiene students were above the cut-off for moderate depressive symptoms, but there were no statistical differences between the third- and fourth-year dental and the first- and second-year hygiene students. Six per cent of the dental and 9% of the dental hygiene students were above the cut-off for clinically significant suicidal ideation, but there were no statistical differences between dental and hygiene students. There were no differences noted in the dental students based on gender for any of the measures. Depression was significantly associated with all three subscales of burnout. Suicidal ideation was only significantly related to the lack of personal accomplishment subscale of burnout. DISCUSSION These findings suggest the need for introducing preventive measures for such affective states in dental and dental hygiene training programmes.

Treatment management between orthodontists and general practitioners performing clear aligner therapy

OBJECTIVE To investigate differences in case selection, treatment management, and aligner treatment expertise between orthodontists and general practitioners. MATERIALS AND METHODS A parallel pair of original surveys with three sections (case selection, treatment management, and demographics) was sent to orthodontists (N = 1000) and general dentists (N = 1000) who were providers of aligner treatment. RESULTS Orthodontists had treated significantly more patients with aligners, had treated more patients with aligners in the previous 12 months, and had received more aligner training than general dentists (P < .0001). In general, case confidence increased with increasing experience for both orthodontists and general dentists. After adjusting for experience, there was a significant difference in aligner case confidence between orthodontists and general dentists for several malocclusions. General dentists were more confident than orthodontists in treating deep bite, severe crowding, and Class II malocclusions with aligners (P ≤ .0001). Significant differences were also found for all treatment management techniques except interproximal reduction. CONCLUSION There was a significant difference in case selection, treatment management, and aligner expertise between orthodontists and general dentists, although the differences in case selection were small. Overall, it was shown that orthodontists and general dentists elected to treat a variety of moderate to severe malocclusions with aligners but with different utilization of recommended auxiliaries, perhaps demonstrating a difference in treatment goals.

Is Maximal Dosage for Local Anesthetics Taught Consistently Across U.S. Dental Schools? A National Survey

Administration of safe and effective local anesthesia is a cornerstone of dental practice, but there is some discrepancy in recommendations for maximum doses, with the Council on Dental Therapeutics and American Academy of Pediatric Dentistrys guidelines differing from the guidelines of manufacturers and contemporary textbooks. The aim of this study was to determine the level of uniformity across U.S. dental schools in teaching maximal safe doses for commonly used local anesthetics. Faculty members primarily responsible for teaching local anesthesia to dental students at all 62 U.S. dental schools that had graduated classes were invited to participate in a survey in March 2017. The survey included questions about maximum doses taught, awareness of the existence of two differing guidelines, and whether one or both guidelines were commonly taught to students. A total of 37 responses were received, for a response rate of 60%. The respondents included oral and maxillofacial surgeons, general dentists, dental anesthesiologists, and periodontists. Of the respondents, 22% reported being unaware of the existence of more than one standard, and there was inconsistency in teaching practices. A majority (73%) reported teaching the higher maximum dose (7 mg/kg) for lidocaine, while a similar but smaller majority (60%) reported teaching the lower dose threshold (4.4 mg/kg) for mepivacaine. This study found no standard recommended maximum dose of lidocaine or mepivacaine being taught in U.S dental schools. Students should be made aware that there is more than one standard, and teaching should emphasize sound medical and pharmacologic principles. There is also a need to ensure that questions on dental licensing examinations are consistent regarding maximum safe doses for local anesthesia.

Telemedicine Consultations in Oral and Maxillofacial Surgery: A Follow-Up Study

PURPOSE The purpose of this study was to follow up on the previous study in evaluating the efficiency and reliability of telemedicine consultations for preoperative assessment of patients. MATERIALS AND METHODS A retrospective study of 335 patients over a 6-year period was performed to evaluate success rates of telemedicine consultations in adequately assessing patients for surgical treatment under anesthesia. Success or failure of the telemedicine consultation was measured by the ability to triage patients appropriately for the hospital operating room versus the clinic, to provide an accurate diagnosis and treatment plan, and to provide a sufficient medical and physical assessment for planned anesthesia. Data gathered from the average distance traveled and data from a previous telemedicine study performed by the National Institute of Justice were used to estimate the cost savings of using telemedicine consultations over the 6-year period. RESULTS Practitioners performing the consultation were successful 92.2% of the time in using the data collected to make a diagnosis and treatment plan. Patients were triaged correctly 99.6% of the time for the clinic or hospital operating room. Most patients (98.0%) were given sufficient medical and physical assessment and were able to undergo surgery with anesthesia as planned at the clinic appointment immediately after telemedicine consultation. Most patients (95.9%) were given an accurate diagnosis and treatment plan. The estimated amount saved by providing consultation by telemedicine and eliminating in-office consultation was substantial at

Helicopter Mountain Rescue in Slovenia from 2011 to 2015

134,640. CONCLUSION This study confirms the findings from previous studies that telemedicine consultations are as reliable as those performed by traditional methods.

Comparison of intraoral and extraoral scanners on the accuracy of digital model articulation

INTRODUCTION The popularity of adventure recreation in wilderness areas across the world continues to increase. Nevertheless, the risk of injury and illness remains significant. The purpose of this study is to analyze the mountain rescue operations performed in Slovenia between 2011 and 2015. METHODS This retrospective study reports mountain rescue operations documented by the Slovenian National Mountain Rescue Association. The annual number of ground-based and helicopter-based rescues were identified and compared. For 2015, the indication for rescue and the severity of injury were also analyzed, specifically for interventions requiring the use of a helicopter. RESULTS From 2011 through 2015, the number of rescues remained consistent with an annual average of 413 (SD ±15; range, 393-434) rescues. However, the percentage of ground-based rescues varied significantly year by year (P=0.016), with highest rate in 2014 (68%) and the lowest in 2015 (56%). In 2015, 434 mountain rescue operations were reported in Slovenia. Injury accounted for 44%, illness for 10%, and fatality for 9% of the rescues. In 37%, no illness or injury was reported. Helicopter rescue was used in 190 (44%) of all interventions. Among the 190 helicopter rescues, 49% of patients had nonfatal injuries, 29% required no medical treatment, 15% had illness, and 7% had fatal injuries. CONCLUSIONS A significant number of mountain rescue operations were conducted in Slovenia from 2011 through 2015. Most of these were needed for injured, ill, or deceased persons. A notable number of rescues in 2015 required a helicopter.

Maximum Recommended Doses of Dental Local AnestheticsThe Authors Respond

Digital dental technology is increasingly becoming an integral part of the modern orthodontic practice. The accuracy of digitally articulated models is critical when developing orthodontic treatment plans. Objective to determine the accuracy of model articulation generated by extraoral and intraoral scanners. Design One extraoral scanner with a wax (EOW) or vinyl polysiloxane bite registration (EOVPS), and three intraoral digital scanners utilizing confocal static (IOCS), confocal continuous (IOCC), and blue LED light technologies (IOLED) were used. Methods On each scanned image (n = 25 per group), measurements between the maxillary and mandibular molars and canines were performed and then compared to the gold standard values. A deviation of ± 0.5 mm from the gold standard value was considered acceptable. The significance level was kept at 0.05. Results IOCS and IOCC were accurate for all six interarch measurements. IOLED and EOVPS groups produced the next most accurate articulation of the digital models. EOW group resulted in the least accurate articulation. Also, of the software platforms used, the OrthoCAD™ was found to be the most accurate system for making measurements on digital casts. Conclusions Only the scanners with the confocal imaging technology produced accurately articulated models. Differences between the scanners may be related to measurement errors inherent to the technologies employed and the software systems used to process the images.

Management of the Maxillary Diastema by Various Dental Specialties

Dear Dr. Karimbux: The June 2018 issue of the Journal of Dental Education published an article by DeLuke et al. presenting results of a survey of 37 responding U.S. dental schools concerning teaching of the maximum recommended doses (MRDs) of dental local anesthetics.[1][1] As a professor of