David W. Chambers

Effects of suspected foodstuff challenging agents in the etiology of recurrent aphthous stomatitis

Two hundred eighteen professional students were surveyed to uncover any association of recurrent aphthous stomatitis (RAS) with a history of allergic diathesis. No significant relationship was uncovered. From this population approximately equal numbers of RAS-positive and RAS-negative subjects were challenged with suspected foodstuff agents thought to have a potential causative role in occurrence of the disease. The results failed to document any causative effect with regard to tomatoes, strawberries, or walnuts.

Usage parameters of nickel-titanium rotary instruments: a survey of endodontists in the United States.

INTRODUCTION Usage of U.S. endodontists regarding rotary root canal instruments is not well-documented. Therefore, the aim of this study was to retrieve data from a representative sample of endodontists regarding contemporary usage of rotary instruments. METHODS A questionnaire addressing (1) nickel-titanium (NiTi) rotary instrument usage and (2) expectations for future instrument design was constructed. An online survey was e-mailed to 954 endodontists in California (n = 358), Iowa (n = 25), Massachusetts (n = 120), Minnesota (n = 49), New York (n = 217), Texas (n = 144), and Wisconsin (n = 41). Data were collected from respondents by using a web-based interface during a 4-month period. Valid responses were received from 359 endodontists, representing a 38% response rate. Chi-square tests and correlation coefficients were used to analyze the data; the level of significance was set at .05. RESULTS Usages varied by region, graduation date, and type of practice. Recent graduates were more likely to use NiTi rotary instruments for every treatment (P = .007), multiple NiTi systems (P = .002), torque control motors (P = .03), and Gates Glidden instruments (P = .001) than were older endodontists. More than 50% of respondents used NiTi rotary instruments in several patients before discarding, and 57% reported cleaning the instruments with a combination of ultrasonics and sterilization. Crown-down was the most frequently used preparation strategy. There were few differences regarding geographic regions. More than 70% of respondents expected similar but improved files during the next 10 years. CONCLUSIONS Differences exist among U.S. endodontists regarding current NiTi instrument use, and expectations for future development might be correlated with level of exposure and training.

Faculty Ratings as Part of a Competency-Based Evaluation Clinic Grading System.

The traditional system for determining grades in dental school clinic courses has been counts of productivity and daily marks for degree of technical excellence. One dental school with a competency-based educational model has redesigned its evaluation system to include assessment of understanding as well as performance of procedures, diagnosis and judgment, and patient management. Competency tests were instituted in all disciplines to replace the required volume of work. A quarterly rating system was developed to replace daily grading. Results from one of the first administrations of the ratings are presented. They show excellent face validity and rater consistency in some cases. Gradients of generalizability are reported, demonstrating that the ratings satisfy the school’s standard for grade defensibility.

An evaluation of ektaspeed plus film versus ultraspeed film for endodontic working length determination

Thirteen teeth in human cadaver sections were accessed and #15 K-files were placed at various lengths in one root canal of each tooth. Using a positioner to ensure duplicate views, radiographs were taken with both Ultraspeed and Ektaspeed Plus X-ray film. Each of the 26 radiographs was coded and then placed in random order. Six endodontic specialists measured the distance from the file tip to the radiographic apex on each film. The results were analyzed by analysis of variance and Cronbachs generalizability theory. It was found that 94% of the variance in measurements was due to differences among the viewers, whereas 5% was due to a combination of viewers and tooth. Only 1% was due to differences between the two types of film. It was concluded that Ektaspeed Plus film may be used for working length radiographs because it requires only approximately 50% of the radiation needed for Ultraspeed film.

Analysis of Temperature Rise and the Use of Coolants in the Dissipation of Ultrasonic Heat Buildup During Post Removal

INTRODUCTION This study was designed to calculate probabilities for tissue injury and to measure effectiveness of various coolant strategies in countering heat buildup produced by dry ultrasonic vibration during post removal. METHODS A simulated biological model was used to evaluate the cooling efficacy of a common refrigerant spray, water spray, and air spray in the recovery of post temperatures deep within the root canal space. The data set consisted of cervical and apical measures of temperature increase at 1-second intervals from baseline during continuous ultrasonic instrumentation until a 10 °C increase in temperature at the cervical site was registered, wherein instrumentation ceased, and the teeth were allowed to cool under ambient conditions or with the assistance of 4 coolant methods. RESULTS Data were analyzed with analysis of variance by using the independent variables of time of ultrasonic application (10, 15, 20 seconds) and cooling method. In addition to the customary means, standard deviations, and analysis of variance tests, analyses were conducted to determine probabilities that procedures would reach or exceed the 10 °C threshold. Both instrumentation time and cooling agent effects were significant at P <.0001. CONCLUSIONS Under the conditions of this study, it was shown that injurious heat transfer occurs in less than 1 minute during dry ultrasonic instrumentation of metallic posts. Cycles of short instrumentation times with active coolants were effective in reducing the probability of tissue damage when teeth were instrumented dry. With as little as 20 seconds of continuous dry ultrasonic instrumentation, the consequences of thermal buildup to an individual tooth might contribute to an injurious clinical outcome.

The ethics of experimenting in dental practice

Experiments, in the sense of novel actions taken with only a probable chance of success, are common in dental practice. Use of new materials or techniques learned in continuing education courses are examples. The grounds for ethically defensible experiments include (a) undertaken for the patients sake, (b) within the standard of care, (c) having a reason for expected success, and (d) performed reflectively. A taxonomy of experiments is presented. The ethical context for this paper is discursive ethics, an approach that emphasizes the right of all affected to participate in mutual acceptance of the action.

The role of orthodontics in the predoctoral education of a dentist

Abstract The position taken here is that reinvesting in upgrading undergraduate orthodontic education is in the best interest of the profession, patients, and orthodontics as a dental specialty. The prospects of a substantial renaissance in the near future are not bright, however. Programs are doomed to failure or only partial success unless there is personal commitment and support by orthodontic leadership and dental school administrations. We must be vigilant to prevent shuffling of curricula and staff which lack commitment. Basic philosophy and deep-seated convictions are not easily changed. Some dedicated teachers have lost their enthusiasm and sought reassignment or left dental education altogether. To reverse this negative process, the existing orthodontic and administrative leadership must be convinced that a reordering of priorities is in order. The administrative structure necessary to bring about this change requires that the orthodontic chairperson should maintain control and a strong interest in graduate orthodontics. However, the departments primary educational responsibility must be to the central commodity of the dental school, namely, students in the undergraduate curriculum. The undergraduate dental student has a central role to play in the future of orthodontics. We must educate these emerging members of the dental community that we are good at what we do and that their patients with dentofacial problems need our services. This means teaching the highest-quality comprehesive care and committing our most competent and impressive instructors to the undergraduate program. If we as orthodontists really believe that clinical competence in comprehensive orthodontics is beyond the scope of predoctoral training, we have an obligation to prove it beyond “lip service.” Orthodontics should be one of the best taught and most demanding educational experiences in the clinical curriculum.

Effects of clinical experience and explorer type on judged crown margin acceptability.

PURPOSE This study was undertaken to simultaneously compare instrumentation type and operator characteristics in judgments of clinical acceptability of crowns exhibiting a controlled range of marginal gaps. The research was conducted in a laboratory setting and generalizability analysis was used as a statistical technique to identify the sources contributing to variation in the judgment outcome. MATERIALS AND METHODS A crown was seated on an ivorine tooth in a device that permitted continuous adjustment in intervals of 25 mum to produce known marginal gaps ranging from zero to 250 microm. Forty-nine students and six faculty members used five types of explorers each to determine, by tactile examination, the point on the controlled increasing marginal gap where they would no longer regard the gap as clinically acceptable. RESULTS There were no differences across type of explorer. Operators with clinical experience had a threshold that rejected crowns at a smaller gap than did those operators without clinical experience (p= 0.007). Faculty members maintained a higher individual degree of consistency in their personal judgments than did students (p= 0.02); however, the inter-operator consistency was significantly lower for faculty members than for students (p < 0.05). CONCLUSIONS Differences among operators in a simulation of the decision regarding gaps in crowns accounted for 63% of the variance; type of explorer used in assisting this decision accounted for about half as much variance. Faculty members making such judgments exhibited high intra-operator consistency but significantly lower inter-operator consistency than did students. The study suggests that the internal standards dentists use for clinical decision making deserves further study as they may be as significant as the equipment used.

The Effects of Faculty Control of Learning on Student Effort

It is commonly assumed in health professions education that knowledge and skills are discrete, objective, and quantifiable and that faculty should control the choice of what is to be learned, how it is taught, and decisions about whether students have mastered the material. Evidence is presented from education, psychology, decision science, and management challenging the assumption that faculty can completely control the learning process, When learning is viewed as an open-ended dialogue, it follows that substituting faculty control and effort for student control and effort will be effective only to a point. Twelve propositions are presented showing the effects, some of them negative, of faculty control of learning on student effort to learn.

A General Method for Describing Sources of Variance in Clinical Trials, Especially Operator Variance, in Order to Improve Transfer of Research Knowledge to Practice

PURPOSE The purpose of this study was to demonstrate how the skill level of the operator and the clinical challenge provided by the patient affect the outcomes of clinical research in ways that may have hidden influences on the applicability of that research to practice. Rigorous research designs that control or eliminate operator or patient factors as sources of variance achieve improved statistical significance for study hypotheses. These procedures, however, mask sources of variance that influence the applicability of the conclusions. There are summary data that can be added to reports of clinical trials to permit potential users of the findings to identify the most important sources of variation and to predict the likely outcomes of adopting products and procedures reported in the literature. MATERIALS AND METHODS Provisional crowns were constructed in a laboratory setting in a fully crossed, random-factor model with two levels of material (Treatment), two skill levels of students (Operator), and restorations of two levels of difficulty (Patient). The levels of the Treatment, Operator, and Patient factors used in the study were chosen to ensure that the findings from the study could be transferred to practice settings in a predictable fashion. The provisional crowns were scored independently by two raters using the criteria for technique courses in the school where the research was conducted. RESULTS The Operator variable accounted for 38% of the variance, followed by Treatment-by-Operator interaction (17%), Treatment (17%), and other factors and their combinations in smaller amounts. Regression equations were calculated for each Treatment material that can be used to predict outcomes in various potential transfer applications. It was found that classical analyses for differences between materials (the Treatment variable) would yield inconsistent results under various sampling systems within the parameters of the study. CONCLUSIONS Operator and Treatment-by-Operator interactions appear to be significant and previously underrecognized sources of variance. It is suggested that variance estimates of factors thought to significantly influence the transfer of research findings to practice contexts and evidence of representative sampling across practice contexts be regularly included in reports of clinical trials.