Repolishing Resin Composites After Bleaching Treatments: Effects on Color Stability and Smoothness.

This study aimed to evaluate the effect of repolishing after bleaching on color stability and smoothness of two resin composites aged in a high-staining beverage. Fifty-six disc-shaped specimens (8×2 mm) of each resin composite were fabricated (Filtek Z250, 3M ESPE, microhybrid, and Filtek Z350 XT, 3M ESPE, nanofilled) and then divided according to treatment: bleached or nonbleached. After treatment application, groups were subdivided according to the surface treatment: repolished or unrepolished. A new subdivision was performed according to aging conditions: immersion in red wine for 15 min/d or in artificial saliva for 24 h/d during 30 days. Color (CIE L*a*b* system) and roughness (Ra) were assessed at baseline (P0), after bleaching procedures (P1), after surface treatment (P2), and after aging (P3). Color change (ΔE00) was calculated through the CIEDE2000 formula. Statistical analysis was performed using repeated measures analysis of variance and the Tukey post hoc test. Bleached repolished groups presented lower color alteration than the bleached unrepolished groups from both resin composites when aged in red wine. Repolishing (P1 vs P2) promoted a slight decrease in roughness values of almost all groups. Nanofilled composite presented greater ΔE00 values than microhybrid composite when aged in red wine.

Family practice career attrition, 1969 to 1993: a comparison of 336 civilian and military graduates of one medical school.

Instability of specialty choice and career after initial residency entry will affect health personnel projections. Military physicians may differ from civilian physicians in their specialty choice behaviors during their careers. A cohort of 336 graduates who chose family medicine residency training was identified from the graduating classes of 1969 through 1993 at a large private medical school. Current specialty identification was determined, and attrition from family medicine was computed. As of 1997, 275 graduates (82%) were still in family medicine careers, defined by American Academy of Family Physicians membership or current American Board of Family Practice certification. Of graduates who entered military programs, 22 of 77 (28%) had left family medicine careers; 39 of 259 (15%) of the graduates who entered civilian programs had left. This difference was statistically significant (p = 0.007). Family medicine career retention is lower for males in military programs compared with males in civilian programs or females in military programs.

Tissue sculpturing: an alternative method for improving esthetics of anterior fixed prosthodontics.

Esthetics associated with health of surrounding tissues in fixed prosthodontics is arduous, especially when treating the maxillary anterior region. An unfavorable relationship between residual ridge, pontic, and gingival papilla commonly compromises the final result. Alternative procedures based on biologic procedures can be developed to improve relationships and provide esthetic and functionally acceptable fixed partial dentures. This article describes a technique for the improvement of esthetics with conditioning of the tissue beneath the pontics, by displacing tissue with a treatment restoration. Lateral displacement of tissue under gradual, controlled pressure enhances the interdental papilla, which improves esthetics. The role of plaque control is also discussed in this article.

Incremental change in student knowledge during a third-year family medicine clerkship.

BACKGROUND AND OBJECTIVES: Family medicine clerkships compete with other clinical experiences for a limited amount of available curricular time. The overlap of clinical material covered by other departments raises the possibility that students will realize increased or diminished added value from a family practice rotation if they take it later in the third-year schedule. METHODS: All students (n = 420) in a required third-year clerkship in two geographically distant medical schools completed pre- and post-clerkship multiple choice examinations on the clinical content of family practice. School A has a lock-step schedule; all the clinical rotations are taken in a specific order by all students. School B has a random schedule. These examinations were random samples, stratified by clinical subject area, from the Exam. Kit database, based on the text Essentials of Family Medicine, Second Edition. The difference between the pre- and post-clerkship scores determined the incremental performance. RESULTS: There was no significant change in incremental performance over the course of the year at either school. CONCLUSIONS: The increased fund of knowledge acquired during a family medicine clerkship, as measured by a multiple choice examination, is not diminished by prior clinical clerkships in other specialties.

Variation of bicycle helmet use rates with route distance.

The relationship between bicycle helmet use and demographic measures has been studied extensively. To date, however, there have been very few studies of helmet use by amateur cyclists in organized, noncompetitive, long distance events. Seven hundred eleven riders were observed during three organized events offering route distances ranging from 16 to 161 kilometres. Helmet use ranged from 59% in the shorter distance groups to one hundred percent in the longest distance group. This information can assist organizers of bicycling events by permitting estimation of helmet use rates for planned routes of varying distance.

Personal protective equipment use by in-line roller skaters.

BACKGROUND: In-line roller skating is a growing recreational fitness activity, but little is known about the use of personal protective equipment, such as helmets, wrist guards, elbow and knee pads, by participants. METHODS: An unobtrusive observational study was performed on a stratified random sample of adult and child in-line skaters in Oakland County, Michigan. A follow-up observational study was performed on locations identified as having high rates of in-line skating activity. RESULTS: The prevalence of personal protective equipment use varied greatly with the type of equipment. Helmet use was less than 10% in both phases of the study; wrist guard use ranged from 46% to 65%; and intermediate values were noted for the use of elbow and knee pads. CONCLUSIONS: Recreational in-line skating is concentrated in paved public areas and is largely a young adult activity. The use of some items of personal protective equipment is common, although few skaters wear all recommended items. Efforts to prevent or reduce accidental injury should include consideration of all these factors.

Rates of bicycle helmet use in an affluent Michigan County.

Bicycle helmet use in the United States has remained low despite clear demonstration of its beneficial effect on reducing the incidence of serious head injury. Several interventions have been reported, with variable results and costs. Much of the recent literature has focused on child cyclists and on demographic factors associated with helmet use. This paper reports on helmet use by children and adults in a sample of 652 riders in an affluent southeast Michigan region, chosen to minimize the effect of previously recognized socioeconomic negative predictors that are not readily changed by intervention. Subjects were classified by age, sex, location, riding surface, type of bicycle, child bicycle seat use, child bicycle trailer use, and helmet use by companions. Overall helmet use was 24 percent; infants and toddlers had the highest rate of helmet use at 61 percent, followed by adults at 26 percent and school-aged children at 17 percent. The strongest predictor of helmet use in all age categories was the presence of a helmeted companion. Adult helmet use was also positively predicted by riding in the street and by riding a racing-type bicycle. The use of a city-type bicycle negatively predicted helmet use. For non-adults, female sex and the use of a child seat or trailer were positive predictors. Fostering peer pressure to increase helmet use may be an effective yet relatively inexpensive way to achieve the goal of widespread use of bicycle helmets.

Cardiac arrhythmias during arousal from hibernation in three species of rodents.

Cardiac activity was monitored during arousal from deep hibernation in three species of hibernators (Citellus tridecemlineatus, Marmota monax, and Mesocricetus auratus). Individuals of each species showed marked arrhythmias, and these were confined to a body temperature range of between 11 and 20 degrees C, measured orally or rectally. The arrhythmias consisted of intermittent periods of asystole and bradycardia and were sometimes marked by the appearance of premature ventricular contractions and elevated or depressed S-T segments. Surgical manipulation of euthermic M. monax, under pentobarbital sodium anesthesia, indicated that none of the arrhythmias observed was inducible by injections of cold saline into the vena cava.

Heparin: an old drug with a new paradigm.

Recent studies have shown that heparin is a biochemical representative of a distinct class of compounds known as linear anionic polyelectrolytes. Members of this class are mixtures of individual highly negatively charged chains that show a wide spectrum of specific reactions with biologically active proteins. Upon administration, heparin chains enter a cellular pool and effectively prevent thrombosis by increasing the electronegative potential of the vessel wall. Anticoagulant activity is an unusual feature of a few heparin chains and appears to play a minor role in many clinical uses and in physiological and pathological responses.