Patrick C. Hardigan

An In Vitro Evaluation of the Sealing Ability of a New Root-canal–obturation System

In this study the sealing ability of a new urethane methacrylate resin-based sealer, EndoRez, was evaluated using a fluid-filtration model. Sixty-four single-rooted lower bicuspids were decoronated, instrumented, and divided into 3 groups of 20 each with 4 teeth used as controls. In group A, the roots were obturated with EndoRez and a single cone of gutta-percha, group B with AH Plus and a single cone of gutta-percha, and group C was obturated using gutta-percha with warm vertical compaction and AH Plus sealer. All specimens were allowed to set for 7 days in 100% humidity at 37 degrees C. The groups were compared for differences in the amount of leakage (mm/h) using a Chi-square test. The leakage of group A was significantly higher at p = 0.01 than the other two groups. There was no significant difference in leakage between groups B and C.

Comparison of different finishing/polishing systems on surface roughness and gloss of resin composites

OBJECTIVES The aim of this study was to compare four finishing/polishing systems (F/P) on surface roughness and gloss of different resin composites. METHODS A total of 40 disc samples (15 mm × 3 mm) were prepared from a nanofill - Filtek Supreme Plus (FS) and a micro-hybrid resin composite - Esthet-X (EX). Following 24h storage in 37°C water, the top surfaces of each sample were roughened using 120-grit sandpaper. Baseline measurements of surface roughness (Ra, μm) and gloss were recorded. Each composite group was divided into four F/P disk groups: Astropol[AP], Enhance/PoGo[EP], Sof-Lex[SL], and an experimental disk system, EXL-695[EXL] (n=5). The same operator finished/polished all samples. One sample from each group was evaluated under SEM. Another blinded-operator conducted postoperative measurements. Results were analysed by two-way ANOVA, two interactive MANOVA and Tukeys t-test (p<0.05). RESULTS In surface roughness, the baseline of two composites differed significantly from each other whereas postoperatively there was no significance. The Sof-Lex F/P system provided the smoothest surface although there were no statistical significance differences between F/P systems (p>0.01). In gloss, FS composite with the EXL-695 system provided a significantly higher gloss (p<0.01). EX treated by Soflex revealed the least gloss (p<0.05). SEM images revealed comparable results for F/P systems but EX surfaces included more air pockets. CONCLUSIONS Four different finishing/polishing systems provided comparable surface smoothness for both composites, whereas EXL with FS provided significantly higher gloss. SEM evaluations revealed that the EX surface contained more air pockets but F/P systems were compatible.

The Effect of Ceramic Restoration Shade and Thickness on the Polymerization of Light and Dual-cure Resin Cements

OBJECTIVES Inadequately polymerized resin cements may negatively affect the clinical performance of cemented all-ceramic restorations. The purpose of this in vitro study was to evaluate the effect of ceramic thickness and shade on the microhardness of various light-cured (LC) and dual-cured (DC) resin cements. The amount of light transmission through the restoration was also evaluated to correlate the results. METHODS Three different brands of resin cements (Appeal/Ivoclar; Calibra/Dentsply; Nexus 2/Kerr) were used in LC and DC forms to prepare disk-shaped samples (0.5-mm thickness × 5-mm diameter) (n=15). Study group samples were light-cured for 40 seconds (Flashlite 1401/Discus Dental) through four shades (ETC1, ETC2, ETC3, ETC4) and four thicknesses (1 mm, 2 mm, 3 mm, 4 mm) of all-ceramic ingot discs (IPS Empress Esthetic/Ivoclar). Control samples were directly cured without the presence of ceramic. The light transmission through various shades and thicknesses of ceramics was measured using a hand-held radiometer (Demetron, Kerr). Vickers microhardness measurements were performed (Micromet/Buehler) at 24 hours following dark storage in 37°C water. Correlation between ceramic shade, thickness, and light intensity readings (mW/cm2) with respect to microhardness was statistically evaluated using analysis of variance (p=0.05). RESULTS Ceramic thickness of 3 mm and/or above significantly decreased the microhardness values in all LC and DC groups (p<0.0001). Ceramic shade had a significant effect only on Calibra in both LC and DC groups (p<0.0001). Microhardness values of LC groups were significantly lower than DC groups (p<0.0001). Control groups had significantly higher hardness values in all cement groups (p<0.0001). There was a significant correlation between the amount of light transmitted and hardness (p=0.000). CONCLUSION The ceramic thickness has a more intense effect on polymerization compared to the ceramic shade. Overlying ceramic thickness of 3 mm and above was found to adversely affect the polymerization of LC and DC resin cements and therefore a 3-mm thickness was considered the critical threshold.

Factors associated with risk for unprotected receptive and insertive anal intercourse in men aged 40 and older who have sex with men.

Abstract The frequency of HIV infection is increasing in men who have sex with men (MSM) aged 40 and older yet little is known about factors that influence their risky sexual behavior, such as sexual positioning. The goal of this study was to examine multi-level factors associated with unprotected receptive anal intercourse (URAI) and unprotected insertive anal intercourse (UIAI) in MSM aged 40 and older. A community-based sample of 802 self-identified MSM aged 40–94 years was recruited through targeted outreach from community venues (e.g., bars, social events) in South Florida and completed an anonymous pen-and-paper questionnaire. Logistic regression showed that younger age (i.e., aged 40–59; odds ratio [OR]=0.6; 95% confidence interval [CI]: 0.4, 0.9), HIV-positive status (OR=2.8; 95% CI: 1.9, 4.0), drug use (OR=2.6; 95% CI: 1.7, 3.7), a larger number of male sexual partners (OR=1.7; 95% CI: 1.3, 2.3), and lower scores on internalized homonegativity (OR=0.9; 95% CI: 1.0, 1.0) were associated with higher risk for URAI. Younger age (OR=0.4; 95% CI: 0.3, 0.6), HIV-positive status (OR=1.5; 95% CI: 1.0, 2.1), drug use (OR=1.6; 95% CI: 1.1, 22.3), Viagra use (OR=1.7; 95% CI: 1.2, 2.4), larger number of sexual partners (OR=2.1; 95% CI: 1.6, 2.9), and holding views more characterized by high optimism concerning the future (OR=1.1; 95% CI: 1.0, 1.1) were associated with higher risk for UIAI. These results provide useful information that may guide the development of tailored prevention interventions to reduce the growing rates of HIV among MSM aged 40 and older.

Thermal Safety of Er:YAG and Er,Cr:YSGG Lasers in Hard Tissue Removal

OBJECTIVE The aim of this study was to compare the thermal safety of Er:YAG and Er,Cr:YSGG lasers with conventional multi-use and single-use diamond burs. BACKGROUND DATA Thermal effect of tooth preparation is mostly evaluated through the pulp chamber because it is difficult to measure the temperature of the preparation surface. A new in vitro method was introduced to simultaneously evaluate the heat increase of the preparation surface together with the pulp chamber. METHODS Six laser and bur instrument groups were used to make standardized preparations on buccal surfaces of 60 intact third molars. The preparations removed an equal volume of hard tissue from each tooth (4 mm occluso-gingival x 8 mm mesial-distal x 1.6 mm bucco-lingual). The teeth also included tunnel preparations from the opposite (lingual) surface, exposing the pulpal axial wall (axial dentin wall in contact with the pulp chamber from the preparation surface site). An infrared thermal camera was positioned to capture the preparation surface in direct vision, while the pulpal axial wall was indirectly reflected to the thermal camera via a minimal-energy-loss mirror. Data from both surfaces were analyzed statistically using Nested Least Squares Analysis. RESULTS The laser groups generated significantly lower heat compared to bur groups on the preparation surfaces. In contrast, both lasers generated greater pulpal heat increase, and the Er:YAG laser group showed significance (p < 0.0001). CONCLUSIONS Lasers produced less heat on the preparation surface but more on the pulpal axial wall. However the temperature rise was less than the 5.5 degrees C threshold margin of safety.

Development and Validation of a Brief Computer-Administered HIV-Related Health Literacy Scale (HIV-HL)

Health literacy is related to a number of health status variables and has been associated with medication adherence in persons treated for HIV infection. Currently-available measures of health literacy require lengthy administration or have content or format limitations. In this paper we report the preliminary development and validation of a brief computer-administered health literacy test that includes content focused on medication adherence as well as questions based on a video simulation of an HIV-related clinical encounter. The measure shows significant relations with other measures of health literacy, HIV-related knowledge, and electronically-measured medication adherence. We also present receiver operating characteristic analyses that provide estimates of various scores’ sensitivities and specificities so that the HIV-Related Health Literacy Scale can be used as a screening measure.ResumenEl alfabetismo en salud está relacionado con un sinnúmero de variables y ha sido asociado con la adherencia a los medicamentos en personas que reciben tratamiento para la infección por el VIH. Las medidas de alfabetismo en salud que están actualmente disponibles toman mucho tiempo en administrarse y evidencian limitaciones de contenido o formato. En este artículo, reportamos el desarrollo preliminar y la validación de una prueba computarizada breve de alfabetismo en salud cuyo contenido se centra en la adherencia a los medicamentos, así como en preguntas basadas en un video que presenta una simulación de una visita médica relacionada con el VIH. Esta medida demuestra relaciones significativas con otras medidas de alfabetismo en salud, el conocimiento relacionado al VIH y la adherencia a los medicamentos medida electrónicamente. También presentamos análisis de la curva ROC que proveen estimados de la sensibilidad y especificidad de varias puntuaciones, de modo que la medida VIH-AS pueda ser utilizada como un cribado.

Should my new curing light be an LED

The new generation LED curing light units have significantly improved curing performance compared to first generation lights, and even some second generation LED curing light units. This study compared the curing performance of 10 new generation LED light curing units (FLASH-lite 1401, LE Demetron 1, Coltolux, Ultra-Lume 5, Mini LED, bluephase, Elipar FreeLight 2, Radii, Smartlite IQ and Allegro) for depth of cure against a high-powered halogen curing light unit (Optilux 501). Depth of cure measurements were utilized per the ANSI/ADA No 27 standard to detect differences between the lights at three time intervals (10, 20 and 40 seconds). A total of 660 samples were prepared (n=10/group). A full factorial ANOVA and Tukeys HSD test showed FLASH-lite 1401 performed significantly better than the other lights at 10- and 20-second time intervals (p<0.01). This study also demonstrated that an exposure time of 20 seconds or longer assures a better depth of cure, 40 seconds being the optimal polymerization time for all of the curing light units.

Maximum Angle of Ocular Duction During Visual Fixation as a Function of Age

Purpose: To measure and compare the maximum angle of ocular duction in healthy individuals as a function of age. Methods: A calibrated arc perimeter was modified to display one of six randomly presented targets (high contrast Snellen equivalent letters), in both vertical (supra/infraduction) and horizontal (ab/adduction) gaze to the dominant eye of 204 healthy volunteers with best-corrected visual acuity. A bite-bar and headrest were employed to prevent head movement. Using a modified method of limits for discrimination threshold, a maximum mean angle of ocular duction was determined by stepping a target out in 5° steps until an error was reported and thereafter bracketing around the limits of the target identification in 1° steps. A mean threshold value was determined as the angle at which a subject obtained a correct response 75% of the time in two and as many as three trials in each of four randomly presented directions of gaze (abduction, adduction, supraduction and infraduction). Results: A decrease in mean maximum duction angle was found over all age groups in all four directions (p < 0.001), with a steep decline beginning in the sixth decade and almost doubling in the oldest age group tested (80–95 year-olds). The percent of change in mean maximum angle of duction due to age from the 14–19 to the 80–95 year-olds was: abduction 21%, adduction 24%, supraduction 35%, infraduction 26%. Conclusion: Baseline data are useful to differentiate normal changes occurring with age from early signs of disease. Additionally, disease progression and effects of treatment can be monitored.

Active avoidance learning in zebrafish (Danio rerio)—The role of sensory modality and inter-stimulus interval

The zebrafish (Danio rerio) promises to meet the growing need of a high throughput model in the fields of gerontological and neurobehavioral research by possessing highly conserved anatomy and physiology with vertebrates, while having low maintenance costs. Here we further explore the conditions of active avoidance learning in zebrafish. Two pairs of distinct aversive conditioning experiments using shuttle boxes were designed to compare the effects of sensory modality and conditioned-unconditioned stimulus interval (CS-US interval) upon memory formation and retention. We found that olfactory conditioning with phenylethyl alcohol as a CS was significantly more likely to produce a successful outcome than with a visual CS. Likewise a 10 s CS-US interval yielded significantly more successful memory formation than a 15 s interval. These conditions may further facilitate the use of zebrafish to explore the genetic and neuronal base of active avoidance learning and its neuropharmacological improvement.

A Comparison of Two Educational Methods on Immigrant Latinas Breast Cancer Knowledge and Screening Behaviors

Underutilization of screening mammography by Latinas continues unabated and may contribute to disparities in disease-free survival and mortality. Objective. Comparison of two discussion group-centered educational interventions at enhancing breast cancer knowledge, breast self-exams (BSE), and screening mammography. Methods. Pre-test post-test study design. Two cohorts of 200 Latinas each participated in survey screening and discussion groups at baseline. One cohort also viewed an animated video and had BSE training. Breast cancer knowledge, self-reported BSE and mammography history were measured at baseline and three months post-intervention. Results. Breast cancer knowledge scores were good for both groups at baseline, and significantly increased at three month follow-up for both groups (p<.05) but no significant difference was observed between groups at baseline or post-intervention. Conclusion. Community-based discussion groups are a cost-effective method for improving breast cancer knowledge and promoting screening behaviors.