The Impact of Global Health Experiences on the Emergency Medicine Residency Milestones.

OBJECTIVES: Identify the impact of experiences in global health (GH) on the Accreditation Council for Graduate Medical Education (ACGME) competencies in emergency medicine (EM) residents and describe the individual characteristics of EM residents with global health experience compared to those without. METHODS: From 2015 to 2018, 117 residents from 13 nationally accredited United States EM residency training programs were surveyed. Specifically, the survey gathered demographic data and information regarding timing, type, location and duration of short term experiences in global health (STEGH). The survey collected both qualitative and quantitative data regarding resident experiences, including number of procedures performed and self-assessment of the impact on their residency milestones. ACGME milestone data from survey respondents was collected from each resident's training program coordinators. Chi-squared analysis and t-tests were conducted to assess differences between residents with STEGH and those without. A generalized linear model (GLM) was utilized to assess the effects of time and experience with interaction on achieving milestones in each of the competency domains, to compare milestone achievement over time between residents with STEGH and those without. RESULTS: Out of 117 EM residents, 60 were female (44%), the mean age was 30 years (standard deviation = 3.1), and 84 (71.8%) reported STEGH in general, including prior to residency (64.5%). 33 (28.2%) reported having completed STEGH during residency. The results of the GLM analysis showed that residents with STEGH during residency had significantly higher scores compared to those without the experience or STEGH pre-residency across all six competencies. CONCLUSIONS: STEGH in EM residents was associated with higher milestone achievement in certain ACGME competency domains including medical knowledge, practice-based learning and improvement, and professionalism. Participation in STEGH during residency appeared to show the strongest effect, with higher scores across all six competencies.

A randomized, blinded, clinical investigation of breath odor reduction efficacy of a stabilized chlorine-dioxide containing flavored mouthwash.

PURPOSE: To evaluate the efficacy of a flavored, non-fluoridated, alcohol-free mouthwash containing 0.1% chlorine dioxide in reducing oral malodor. METHODS: This was a randomized, 8-week, single site, double blind, crossover design with a 2-week washout period between crossover phases. Fifty subjects with clinically diagnosed intrinsic oral malodor were enrolled according to inclusion/exclusion criteria and randomized to one of two groups. Washout period initiated at end of Phase I and crossover design implemented prior to Phase II. Calibration for organoleptic judges performed at baseline for both phases. RESULTS: 48 subjects completed the study. No significant differences in intensity scores at baseline were found for both groups during both phases (P> 0.05). Within group comparisons for placebo revealed no significant differences with organoleptic intensity scores for all visits during both phases (P> 0.05). During Phase I, the mean changes in organoleptic scores for the test group were significantly different from the baseline at each visit: Weeks 1 to 3 (P< 0.05). After crossover, significant differences were found for the last two visits: Weeks 7 and 8 (P< 0.05). No adverse effects to oral tissues were observed or reported. This product is safe to use for up to 3 weeks and resulted in a decrease in oral malodor. CLINICAL SIGNIFICANCE: Results suggested that twice-daily use of a 0.1% chlorine dioxide-containing flavored mouthwash, in conjunction with normal oral hygiene care, provided clinically relevant improvements in oral malodor for up to 3 weeks.

Syntrophic metabolism facilitates Methanosarcina-led methanation in the anaerobic digestion of lipidic slaughterhouse waste.

Different inoculum to slaughterhouse waste (SHW) ratios (Ino/SHW) influences the digester performance, substrate utilization, and methane yield through microbial shift and their metabolic syntrophy. Acetoclastic Methanosarcina (68-87%) was dominant in the exponential phase, overpowering the initial abundance of Methanosaeta (86% of methanogens) in the SHW digesters. Positive interactions among acetogenic and acetate-oxidizing species of Clostridium (11%) with Methanosarcina (84% of methanogens) improved the methanogenic activity (292 mL g-1 VSinitial d-1) and final VS utilization (90%) at the highest Ino/SHW loading. In contrast, significant improvement of methane yield (152% higher than the control) at the lowest Ino/SHW loading was attributed to strong syntrophy among Methanosaeta (24% of methanogens) and its exoelectrogenic partners, Bythopirellula (0.52%) and Mariniphaga (0.08%) and the acetogenic Cloacimonas (0.16%) and Longilinea (0.32%). These syntrophic interactions among the core microbiota induced major metabolic activities, including butanoate, glycine, serine and threonine, methane, propanoate, and pyruvate metabolism, and quorum sensing.

Rapid recovery of methane yield in organic overloaded-failed anaerobic digesters through bioaugmentation with acclimatized microbial consortium.

Acidification during anaerobic digestion (AD) due to organic overloading is one of the major reasons for process failures and decreased methane productivity in anaerobic digesters. Process failures can cause the anaerobic digesters to stall completely, prolong the digester recovery period, and inflict an increased operational cost on wastewater treatment plants and adverse impacts on the environment. This study investigated the efficacy of bioaugmentation by using acclimatized microbial consortium (AC) in recovering anaerobic digesters stalled due to acidosis. Overloading of digesters with food waste leachate (FWL) led to the accumulation of volatile fatty acids (11.30 g L-1) and a drop in pH (4.67), which resulted in process failure and a 22-fold decline in cumulative methane production compared to that in the initial phase. In the failure phase, the syntrophic and methanogenic activities of the anaerobic digester microbiota were disrupted by a significant decrease in the abundance of syntrophic populations such as Syntrophomonas, Syntrophorhabdus, Sedimentibacter, and Levilinea, and the phylum Euryarchaeota. Bioaugmentation of the failed digesters by adding AC along with the adjustment of pH resulted in the prompt recovery of methane productivity with a 15.7-fold higher yield than that in unaugmented control. The abundance of syntrophic bacteria Syntrophomonas and phylum Euryarchaeota significantly increased by 29- and 17-fold in the recovered digesters, respectively, which showed significant positive correlations with methane productivity. Methanosarcina and acetoclastic Methanosaeta played a major role in the recovery of the digesters; they were later replaced by hydrogenotrophic Methanoculleus. The increase in the abundance of genes associated with biomethanation contributed to digester recovery, according to the functional annotation of 16S rDNA amplicon data. Thus, bioaugmentation with AC could be a viable solution to recover digesters experiencing process failure due to organic overloading.

Association Between the Economic Environment and the Living Organ Donation Rate: Evidence and Implications.

BACKGROUND: We studied the contribution of the economic environment to an individual's decision to donate an organ by examining the relationship between the unemployment rate and the living donation rate. STUDY DESIGN: We obtained living organ donation data from the Organ Procurement and Transplant Network (OPTN) containing 134,138 organ donation events from 1990 through 2016. We obtained monthly unemployment rates from the Bureau of Labor Statistics (BLS) from 1990 through 2016, and obtained quarterly real gross domestic product (real GDP) by state from the Bureau of Economic Analysis (BEA) from 2005 through 2016. We conducted graphical and statistical analysis with regression modeling using state and time fixed effects. RESULTS: Descriptive graphical plots suggest that unlike the unemployment rate, the donation rate is non-cyclical over time, implying little association between the two factors. This is conferred by a linear regression model using state and calendar month fixed effects, where we found no significant association between the unemployment and donation rates (95% CI [-0.004, 0.008], interpreted as the change in number of donations per 100,000 people associated with 1% change in the unemployment rate). We also did not find any significant association between the real GDP and the donation rates. Subgroup analysis by sex, race, and age also revealed no significant associations. CONCLUSIONS: The unemployment rate and the real GDP do not appear to be associated with the living organ donation rate, suggesting that the economic environment may not play a major role in the decision to donate an organ.

Clinical impact of pre-hypertension on the risk of cancer in male and female subjects.

There are few studies assessing pre-hypertension and an impaired fasting glucose (IFG) and their combined effects on the cancer risk. We investigated the impact of pre-hypertension on cancer risk and IFG, and their combined effects on the cancer risk. This study included 371,762 subjects (≥40 years) who had never been diagnosed with hypertension, diabetes mellitus (DM), and cancer before. During a mean follow-up of 10.06 ± 1.86 years, 35,605 (9.58%) of the subjects developed cancer. In men only, cancer risk was significantly increased with an increase in the blood pressure (BP) (P for trend < 0.001), and were increased in the hypertension range, but not the pre-hypertension range. When analyzing the combination effect of BP and fasting glucose, cancer risks were serially increased with an increase in the fasting glucose in a dose-dependent manner, but not with an increase in BP. These results were more consistently significant in the never-smoker and non-alcohol drinking groups. However, in women, there was no significant difference. In conclusions, increased BP status or the fasting serum glucose level status were associated with cancer risk in men. Furthermore, the combination of both pre-hypertension and IFG also was associated with a cancer risk in men.

Waste sludge derived adsorbents for arsenate removal from water.

Aqueous arsenate [As(V)] was removed using an aluminum-based adsorbent (ABA) and coal mine drainage sludge coated polyurethane (CMDS-PU) prepared using alum and coal mine sludge, respectively. Their As(V) removal efficiencies were compared with each other and granular ferric hydroxide (GFH). The mineralogy and surface chemistry of materials were determined using wavelength dispersive X-ray fluorescence (WD XRF) and Fourier transform infrared spectroscopy (FTIR), respectively. The angle-resolved X-ray photoelectron spectroscopy (AR-XPS) studies confirmed As(V) retention on the adsorbent surfaces. The adsorption kinetics data were fitted to pseudo second-order rate equation. The faster As(V) uptake kinetics of GFH and ABA (GFH > ABA > CMDS-PU) were attributed to their large pore volume and mesoporous nature. Langmuir adsorption capacities of 22, 31 and 10 mg/g, were achieved for GFH, ABA and CMDS-PU, respectively. As(V) adsorption on GFH, ABA and CMDS-PU was endothermic. GFH and ABA were efficient over a wide pH range (3-10). In column studies, GFH, ABA, and CMDS-PU successfully treated 23625, 842, and 158 bed volumes (BVs) and 2094, 6400, and 17 BVs of As(V)-contaminated water with 9.5 and 27 EBCT, respectively (at pH = 6.0, Asi = 600 µg/L). The GFH and ABA have a potential to be used at large-scale aqueous phase As(V) remediation.

Interspecies microbial nexus facilitated methanation of polysaccharidic wastes.

Compositional variations in organic wastes influence microbial abundancy and syntrophy during anaerobic digestion (AD), impacting the normal performance of digesters for methanation. Investigation of the microbial dynamics during AD following augmentation with polysaccharidic wastes (PW) revealed the association of effective digester performance and methane yields with the microbial nexus. Dominance of the acidogenic saccharolytic genera, Prevotella, Eubacterium, and Lachnoclostridium, enhanced the utilization of carbohydrates (54%) in PW-augmented digesters. Spearman's rs correlation showed dynamic interspecies interactions among acetogenic syntrophs, and that of iron oxidizers/reducers with acetoclastic and hydrogenotrophic methanogens. Propionate oxidizers in Chloroflexi (i.e., Bellilinea, Levilinea, and Longilinea) exhibited positive associations with acetoclastic methanogens. Increase in the population of acetoclastic methanogens (Methanosaeta, 77% and Methanosarcina, 9%) accelerated the methanogenic activity of PW-augmented digesters by 7 times during the exponential phase, increasing the methane yield (75%) compared to the control. Thus, microbial syntrophy facilitated the effective methanation of PW during AD process.

A 3 months clinical evaluation comparing two professional bleaching systems of 25% and 40% hydrogen peroxide and extended treatment outcome using a power versus a manual toothbrush.

OBJECTIVES: To assess two professional tooth bleaching products: Philips Zoom WhiteSpeed (PZW) and Ultradent Opalescence Boost PF (UOB); and to assess bleaching maintenance after use of Philips Sonicare power toothbrush (SDC) or manual toothbrush (MTB). METHODS: There was a randomized, parallel clinical trial. Eligible subjects were 18-75 years, with VITA Classical shade (VCS) of A3 on anterior teeth. Subjects were randomized to bleaching with PZW or UOB. Tooth color and shade were assessed using VITA EasyShade (VES), VCS, and VITA Bleachedguide (VBG). Subjects returned on Days 7 and 30. On Day 30, participants were dispensed either SDC or MTB for home use until Day 90. RESULTS: A total of 135 subjects completed the study. For the primary endpoint, ΔE at Day 7, a significantly larger reduction was observed for PZW than UOB (P value = .0059). Significant differences in shade were also observed at Day 7 for VCS (P value = 0.0106), and VBG (P value = .0489). On Day 90, the SDC was statistically superior to MTB in maintaining shade per VBG and VCS, but not ΔE. CONCLUSIONS: At Day 7, PZW showed statistically greater change in overall color and shade than UOB. The SDC maintained tooth shade significantly better than MTB. Both bleaching regimens were safe. CLINICAL SIGNIFICANCE: The outcomes confirm the bleaching efficacy advantage of a lower H2 O2 dose-LED accelerated professional tooth bleaching system, compared to a higher-dose H2 O2 approach. The safety assessments via clinical intraoral exam and daily logged use of subjects' desensitizing agents, and the incidence and severity of reported sensitivity, provide evidence that both professional products are safe for use. Finally, powered tooth brushing may confer an advantage to manual tooth brushing in maintaining tooth shade-change results following professional whitening.

Efficacy of stabilized chlorine dioxide-based unflavored mouthwash in reducing oral malodor: An 8-week randomized controlled study.

PURPOSE: To evaluate the efficacy of a mouthwash containing stabilized chlorine dioxide in reducing oral malodor when used as an adjunct to tooth brushing compared with the use of a placebo mouthwash. METHODS: This 8-week study in healthy subjects with clinically diagnosed intrinsic oral malodor was a 2-way crossover, double-blind, randomized, and controlled trial design, which was conducted at a single site. Subjects were randomized to receive either unflavored, non-fluoridated, and alcohol-free mouthwash containing 0.1% stabilized chlorine dioxide or a placebo mouthwash with identical bottle packaging. Both groups were provided with the same toothpaste and toothbrush. Subjects consented to the 8-week participation and were instructed to use their allocated treatment twice daily. In Phase I, quantified odor intensity [measured by an organoleptic intensity rating scale of 0-5, with 0=malodor cannot be detected and 5=very strong malodor] was independently evaluated by three calibrated judges at baseline, and after 1, 2, and 3 weeks of treatment. Following a 2-week washout period, Phase II initiated with the redistribution of test products. The subjects' organoleptic scores were assessed by the calibrated judges at baseline, and 6, 7, and 8 weeks of treatment. RESULTS: A total of 50 subjects were enrolled and randomized into the two groups. Of these, 47 subjects completed the study. The baseline organoleptic intensity scores for both groups during Phase I and Phase II were not significantly different (P= 0.224, P= 0.071, respectively). At all visits, the organoleptic scores for the placebo rinse group during both Phase I and Phase II were not significantly different. During Phase I, the mean of individual organoleptic change scores from the stabilized chlorine dioxide rinse group were significantly different from the baseline at the last two follow-up visits:Week 1 (P= 0.088), Week 2 (P= 0.001), Week 3 (P= 0.1×10-3). During Phase II, the mean of individual organoleptic change scores from the stabilized chlorine dioxide rinse group were also significantly different from the baseline at the last two follow-up visits: Week 6 (P= 0.120), Week 7 (P= 0.004), Week 8 (P= 0.002). CLINICAL SIGNIFICANCE: The results of this study suggest the daily use of a stabilized chlorine dioxide-containing unflavored mouthwash as an adjunct to brushing with fluoride toothpaste provides a clinically relevant reduction in oral malodor after 3 weeks of twice-daily use.

Clinical implication of an impaired fasting glucose and prehypertension related to new onset atrial fibrillation in a healthy Asian population without underlying disease: a nationwide cohort study in Korea.

AIMS: For healthy populations without comorbidities, whether prehypertension and impaired fasting glucose (IFG) are associated with new onset atrial fibrillation (AF) is not well known. METHODS AND RESULTS: We included 366 507 subjects (age ≥20 years) not diagnosed with non-valvular AF from the Korean National Health Insurance Service-National Sample Cohort (NHIS-NSC) from 2003 to 2008. In total, 139 306 subjects diagnosed with AF-related comorbidities were excluded, and a 227 102 healthy population was followed up until 2013. The body mass index (BMI), blood pressure (BP), and fasting blood glucose (BG) level were acquired during National health check-ups. Subjects with IFG [hazard ratio (HR) 1.16, P = 0.017] had a higher AF risk and the diastolic BP (HR 1.11, P = 0.045) was a stronger indicator for an AF incidence than the systolic BP. After dividing the subjects into two mutually exclusive groups, AF incidence was increased dramatically by the combination effect of both prehypertension and an IFG in BMI <25 kg/m2 group, but, in BMI ≧25 kg/m2 group, did not show this tendency. An IFG related to AF risk was more prominent in the BMI <25 kg/m2 population (HR 1.18, P = 0.025) than those with a BMI ≥25 kg/m2, and subjects with both an IFG and prehypertension had a greater AF risk (HR 1.27, P = 0.016) than those without. CONCLUSION: Even in a healthy Asian populations without comorbidities, prehypertension and IFG were important risk factors of AF. Specifically, when prehypertension, including systolic and diastolic BPs, was finally combined with the IFG, the risk of new onset AF was increased especially in the BMI <25 kg/m2 group.

Antiplaque/antigingivitis efficacy and safety of a cetylpyridinium chloride/zinc gluconate mucoadhesive gel. Results of a 6-month clinical trial.

This article presents the results of a controlled clinical trial evaluating a new at-home treatment to improve gingival health. Designed for overnight application at the gingival margins and in the interproximal spaces, the product is a mucoadhesive gel containing 0.10% cetylpyridinium chloride (CPC) and 0.592% zinc gluconate (ZG). The authors assessed the efficacy and safety of the CPC/ZG gel in adults with low-to-moderate gingival and plaque index scores by comparing clinical and laboratory findings for subjects using the CPC/ZG gel with those for subjects using the control gel (0% CPC and 0.592% ZG). Clinical findings at 3 and 6 months showed statistically significant improvements in two of the three major indices of gingival health in the CPC/ZG group compared with the control group. The performance of the treatment gel was supported by results of microbial analyses of plaque samples.

Evaluation of Sterilox for controlling microbial biofilm contamination of dental water.

The purpose of the investigation was to evaluate the effectiveness of Sterilox, a sterilizing unit that produces a hydrochlorous acid solution that controls microbial contamination as well as reduces biofilms and endotoxin in dental unit waterlines (DUWLs). A total of 15 dental units were used: 10 in the Sterilox group and 5 in the control group (treatment with Bio2000). Distilled water was used as source water. Samples were collected at the baseline, 1-day, and 1, 2, 4, and 8 weeks. A scanning electron microscope was used to evaluate the biofilm in dental tubing before and after the treatment. The content of endotoxin was analyzed using the Chromogenic Limulus Method. The baseline CFU revealed high microbial counts (> 39,000 CFU/mL) in all DUWLs. After the treatment and throughout the study, the Sterilox practically eliminated the CFU in the waterlines, while the control group remained at high CFU counts similar to the baseline values. The differences between the 2 groups were significant (P < .05). The endotoxin analysis of the DUWL samples indicated that the average amount of endotoxin per milliliter increased immediately after the Sterilox shock treatment, indicating the lysis of gram-negative bacteria. Endotoxin content then quickly declined and remained at an acceptable level throughout the study Endotoxin in controls fluctuated in higher levels. It was concluded that Sterilox is effective at controlling microbial contamination and reducing biofilms and endotoxin in DUWLs.

Halitosis update: a review of causes, diagnoses, and treatments.

Up to 50 percent of the U.S. population reports that their own "bad breath" has concerned them during some point in the course of their lifetime. Half of this group is indeed likely to have an ongoing sporadic or a chronic breath malodor problem. This report looks at the phenomenon of malodorous breath, which oddly persists in a society rife with scientific and medical advancements. Also reviewed are the primary causes, diagnoses, treatments, and research frontiers.

Tooth whitening in children and adolescents: a literature review.

The purpose of this paper was to summarize the findings of a literature review on the use of peroxide-based tooth-whitening agents in children and adolescents. Safety considerations, including localized adverse effects and toxicological concerns, are described. Oral findings include: (1) 1 in every 2 to 3 patients may experience tooth sensitivity and/or gingival irritation after bleaching treatment, which may be more traumatic an experience for children than adults; (2) depending on dose, duration, frequency, and route, studies indicate excessive exposure to peroxide can be potentially harmful; (3) degree of potential toxicity and harmful outcomes increases in those who overuse whiteners--a concern in teenagers; (4) careful case selection using stringent criteria is suggested for primary teeth whitening; (5) whitening in healthy adolescents is a case-by-case determination that must include the weighing of risks (oral health and age) vs benefits (improved esthetic perception). It is hoped that the present review will lead to a better understanding of the health implications of tooth whitening in children and adolescents, and offer guidance for treatment that provides satisfactory outcomes externally (enamel and gingiva) and internally (endodontic tissues and systemic health).

The antimicrobial potential of 14 natural herbal dentifrices: results of an in vitro diffusion method study.

BACKGROUND: Increasing numbers of Americans are using natural herbal products for general and oral health care. Few of these products, however, have undergone rigorous testing, as evidenced by the limited amount of information on their safety and efficacy in the literature. The authors conducted an in vitro study to evaluate the antimicrobial potential of 14 natural herbal dentifrices. METHODS: The authors used a diffusion method to evaluate the antimicrobial effectiveness of 14 natural herbal dentifrices against four microorganisms: Streptococcus mutans, Streptococcus sanguis, Actinomyces viscosus and Candida albicans. Colgate Total (Colgate-Palmolive, New York City) and sterile pyrogen-free water served as the positive and negative controls, respectively. The authors tested the natural herbal dentifrices at full strength and at 1:1 dilution. They measured the zones of inhibition at 24 and 48 hours to evaluate the antimicrobial potential of the dentifrices. RESULTS: Six herbal dentifrices were effective in inhibiting the growth of all four microorganisms. The positive control produced significantly sized inhibition zones with all four microorganisms, while the negative control produced no observable zones. Six herbal dentifrices produced larger inhibition zones with A. viscosus than did the positive control. Six herbal dentifrices were inhibitory against C. albicans at full strength, but at 1:1 dilution, only three had such inhibitory effect. One herbal dentifrice produced microbial growth around and over the samples, indicating possible microbial contamination of the toothpaste. Only one herbal dentifrice showed consistent antimicrobial activity against all four microorganisms. CONCLUSIONS: The variation in antimicrobial inhibition among the herbal dentifrices indicates that more research is needed to validate their effectiveness claims. CLINICAL IMPLICATIONS: This study provides practitioners with insight into the claims of natural herbal dentifrices' antimicrobial effects.

Comparative tooth whitening efficacy of 18% carbamide peroxide liquid whitening gel using three different regimens.

OBJECTIVE: Recently, a novel paint-on liquid whitening gel--Colgate Simply White Clear Whitening Gel--which contains 18% carbamide peroxide, has been developed as a self-administered tooth bleaching system. The purpose of the present study was to determine the efficacy and safety of this product using alternate exaggerated or simplified treatment regimens. METHODOLOGY: This was a three-week clinical trial using a parallel, double-blind, stratified protocol with three different instructions for application: 1) twice-daily, no air-drying, and 15 minutes without eating/drinking; 2) three times daily, 30-second air-drying and 30 minutes without eating/drinking; or 3) four times daily, 30-second air-drying and 30 minutes without eating/drinking. One-hundred and twenty (120) healthy volunteers were balanced into three equal groups based on shade scores (A3 or darker). Clinical evaluations (shade guide, oral tissue health, gingival index and visual analog sensitivity score) were performed on each group at baseline and weekly for the next 21 days. At the conclusion of the study, a survey of the subjects' opinions on their assigned product regimen was also conducted. RESULTS: Subjects who used Colgate Simply White Clear Whitening Gel three and four times daily achieved the greatest shade improvement (5.88 +/- 1.53 shades, and 5.57 +/- 1.54, respectively). However, these values were only about one shade better than the value observed for the more convenient, twice-daily, "no-dry" regimen (4.51 +/- 1.77 shades), though they were statistically significant (p < 0.05). The result for the four-times daily protocol was not statistically different from the three-times group. Also, no differences were observed between the groups concerning oral tissue health, gingival index or tooth sensitivity, and no adverse effects were observed or reported regardless of the regimen used. Surveys completed by the subjects showed that those who used the twice-daily, "no-dry" regimen found the product to be the easiest to use, the most comfortable and the most pleasant tasting. CONCLUSION: It can be concluded from the clinical data that three or four applications of Colgate Simply White Clear Whitening Gel per day provided better efficacy. In addition, the use of the whitening gel twice daily, even without "dry time" and only 15 minutes without eating/drinking, yielded results that were comparable to previously reported results using the original on-label directions. The potential additional benefit to the "simplified regimen" is that it was perceived to be the most convenient and comfortable. The use of Colgate Simply White Clear Whitening Gel up to four times daily for up to three weeks is also safe, and the tendency of abusing the product with more frequent daily use may be deterred by the inconvenience reported by the study subjects.

Comparison of clinical efficacy and safety of three professional at-home tooth whitening systems.

A three-cell, randomized, parallel, investigator-blinded clinical trial was conducted to compare the efficacy and safety of three professional at-home tooth whitening systems, including Crest Professional Whitestrips (6.5% H2O2), Day White 2 (7.5% H2O2) and Nite White Excel 2 (16% carbamide peroxide equivalent). Ninety subjects were randomly assigned to three groups (30/group). Subjects were instructed to use the assigned whitener following the manufacturers' instructions. Clinical examinations at baseline, and on days 3, 7, 14, and 18 (Day White), or 21 (Crest Professional Whitestrips and Nite White) included the following parameters: 1) oral tissues; 2) tooth shade by the Vitapan Classical shade guide; 3) tooth shade by a chromameter with a jig; and, 4) tooth sensitivity and gingival irritation. The results showed significant shade reductions with time in all three groups. Nite White resulted in significantly greater shade reductions in periods between days 7, 14, or 21 and baseline than did the other two systems. Tooth sensitivity and gingival irritation, which were mostly mild and transient, occurred in all groups. It is concluded that all three whitening systems evaluated are effective and safe. Nite White Excel is superior to the other two systems because it provides a greater whitening efficacy with comparable or lower incidence of tooth sensitivity and gingival irritation.