Effect of Various Toothpaste Tablets on Gloss and Surface Roughness of Resin-based Composite Materials.

OBJECTIVES: To evaluate the effect of various toothpaste tablets on gloss and surface roughness of resin-based composite. METHODS AND MATERIALS: Sixty-four resin-based composite specimens were divided into four groups of 16 specimens each. Gloss and roughness were measured before and after simulated brushing with three types of toothpaste tablets and one conventional toothpaste: CT: Chewtab Toothpaste Tablets; AT: Anticavity Toothpaste Tablets; HC: Charcoal Toothpaste Tablets; CP: Cavity Protection toothpaste. The Kruskal-- Wallis procedure was performed to compare the differences by groups. Post-hoc comparisons were conducted with Bonferroni corrections (α=0.05). RESULTS: There was a significant drop in gloss for all groups. CT and AT maintained the highest gloss with means of 81.6 GU and 74.1 GU, respectively. The lowest gloss of 24.5 GU was observed for HC. There was a significant increase in roughness for all groups except for CT. CT had the lowest roughness with a mean of 0.034 µm, while HC had the highest roughness with a mean of 0.074 µm. There was a significant correlation between post-brushing gloss and post-brushing roughness (p<0.001, r=-0.884). CONCLUSION: Chewtab Toothpaste Tablets had the least effect on gloss and roughness, while Charcoal Toothpaste Tablets had the most negative effect on the surface properties of resin-based composites.

Tooth Color Change and Erosion: Hydrogen Peroxide Versus Non-peroxide Whitening Strips.

AIM: The study evaluated the efficacy and potential erosion of non-peroxide strips compared to hydrogen peroxide (HP) whitening strips (WSs). METHODS: Color evaluation samples (N=64) were distributed into four groups and treated according to manufacturer's directions. NC: Negative control treated with water; BT: Non-peroxide Brilliant Dissolving Strips; FM: Non-peroxide Fancymay Teeth WSs; WS: Crest 3D Brilliance HP White Strips. A contact-type spectrophotometer was used to measure color at baseline (T1), 1-day posttreatment (T2), and 1-week posttreatment (T3). Teeth were cut to a rectangular block for micro-CT erosion assessment. The samples (N=30) were divided into five groups. In addition to the four groups for color assessment, a positive control (PC) treated with 0.25% citric acid was added. The samples were scanned, reconstructed, and measured for erosion depth using a micro-CT analysis program software. Kruskal-Wallis test was used to determine differences in color change and erosion depth among the groups. Tests of hypotheses were two-sided with an alpha level of 0.05. RESULTS: The mean ΔE*ab at 1-day/1-week posttreatment were 2.4/2.5, 2.8/2.9, 2.8/3.2, and 8.6/11.0 for NC, BT, FM, and WS, respectively. There was a statistically significant difference for ΔE*ab at 1-day and 1-week posttreatment (p<0.001). Group WS had the highest color change, while the other three groups did not differ from each other (p>0.05). Mean erosion depths in microns were 0.52, 0.58, 0.42, 0.49, and 29.55 for NC, BT, FM, WS, and PC, respectively. There was a statistically significant difference among the groups (p=0.004). Group PC had the greatest erosion, while the other groups had negligible erosion that did not differ from each other (p>0.05). CONCLUSION: Peroxide WSs had superior whitening efficacy compared to non-peroxide strips. None of the tested products compromised tooth structure integrity through enamel erosion.

Effect of Bleaching Gel Viscosity on Tooth Whitening Efficacy and Pulp Chamber Penetration: An In Vitro Study.

OBJECTIVES: Whitening efficacy has been related to hydrogen peroxide (HP) diffusion into tooth structure. However, little information is available relating rheological properties to whitening efficacy. The purpose was to evaluate the whitening efficacy and HP penetration level of a 10% HP gel at three different viscosities and to compare them to a strip delivery system. METHODS AND MATERIALS: Extracted molars (n=120) were randomly assigned into five groups (n=24/ group): NC_MED (negative control; median): medium viscosity gel without HP; LOW: 10% HP gel (low viscosity experimental gel, Ultradent Products Inc); MED: 10% HP gel (medium viscosity experimental gel, Ultradent); HIGH: 10% HP gel (high viscosity gel, Ultradent); and CWS: Crest 3D Whitestrips 1-Hour Express (Procter & Gamble). All teeth were subjected to five 60-minute whitening sessions. Instrumental color measurements were performed at baseline (T0), and 1-day after each application (T1-T5), and 1-month after whitening (T6). HP penetration was estimated with leucocrystal violet and horseradish peroxidase. A Kruskal-Wallis test and post hoc Bonferroni test were performed to assess the difference in tooth color change and HP penetration among the groups (α=0.05). RESULTS: Hydrogen peroxide penetration levels and overall color changes at T6 were 0.24 µg/mL / 2.80; 0.48 µg/mL / 8.48; 0.44 µg/mL / 7.72; 0.35 µg/mL / 8.49; 0.36 µg/mL / 7.30 for groups NC, LOW, MED, HIGH, and CWS, respectively. There was a significant difference for HP penetration, while there was no significant difference among the four experimental groups for tooth color change. CONCLUSION: Rheological properties should be considered when developing new whitening formulations.

Performance of two different digital evaluation systems used for assessing pre-clinical dental students' prosthodontic technical skills.

INTRODUCTION: Proper integration of newly emerging digital assessment tools is a central issue in dental education in an effort to provide more accurate and objective feedback to students. The study examined how the outcomes of students' tooth preparation were correlated when evaluated using traditional faculty assessment and two types of digital assessment approaches. Specifically, incorporation of the Romexis Compare 2.0 (Compare) and Sirona prepCheck 1.1 (prepCheck) systems was evaluated. Additionally, satisfaction of students based on the type of software was evaluated through a survey. MATERIAL AND METHODS: Students in a second-year pre-clinical prosthodontics course were allocated to either Compare (n = 42) or prepCheck (n = 37) systems. All students received conventional instruction and used their assigned digital system as an additional evaluation tool to aid in assessing their work. Examinations assessed crown preparations of the maxillary right central incisor (#8) and the mandibular left first molar (#19). All submissions were graded by faculty, Compare and prepCheck. RESULTS: Technical scores did not differ between student groups for any of the assessment approaches. Compare and prepCheck had modest, statistically significant correlations with faculty scores with a minimum correlation of 0.3944 (P = 0.0011) and strong, statistically significant correlations with each other with a minimum correlation of 0.8203 (P < 0.0001). A post-course student survey found that 55.26% of the students felt unfavourably about learning the digital evaluation protocols. A total of 62.31% felt favourably about the integration of these digital tools into the curriculum. CONCLUSIONS: Comparison of Compare and prepCheck showed no evidence of significant difference in students' prosthodontics technical performance and perception.

Evaluation of Stain Penetration by Beverages in Demineralized Enamel Treated With Resin Infiltration.

PURPOSE: To evaluate stain penetration by different beverages in artificially demineralized human teeth treated with resin infiltration. METHODS AND MATERIALS: Sixty extracted human permanent molars were demineralized, treated with resin infiltration (Icon), and immersed in four different beverages (coffee, grape juice, iced tea, and distilled water; N=15) for four weeks. After aging, teeth in the distilled water group were stained with 2% methylene blue for 24 hours. All teeth were sectioned, and stain penetration was evaluated under light microscopy. Chi-square test, independent and paired sample t-test, analysis of variance with the Fisher least significant difference post hoc test, and the Kruskal-Wallis test were used to analyze the results (p<0.05). RESULTS: Resin infiltration-treated surfaces (Icon surfaces) had statistically significant fewer samples with presence of stain penetration compared to untreated surfaces (control surfaces) (p<0.001). There was also a significant decrease in depth of stain penetration in Icon surfaces compared to the control surfaces (p<0.001). Among tested beverage groups, iced tea showed significantly greater depth of stain penetration (0.134±0.029 mm), followed by grape juice (0.118±0.047 mm), methylene blue (0.022±0.019 mm), and coffee (0.008±0.017 mm; p<0.001). CONCLUSION: Both Icon and control surfaces exhibit stain penetration by different beverages (iced tea, grape juice, and coffee). However, resin-infiltrated enamel surfaces allow significantly less depth of stain penetration compared to untreated surfaces. The iced tea group presents greatest depth of stain penetration, followed by grape juice, methylene blue, and coffee.

Spectrophotometric Evaluation of Potassium Nitrate Penetration Into the Pulp Cavity.

OBJECTIVES: The aim of this study was to evaluate the penetration level of potassium nitrate-containing desensitizers or whitening materials into the pulp cavity with regard to the concentration and viscosity of the formulation. METHODS AND MATERIALS: Fifty extracted human molar teeth were prepared and randomized into five groups of 10 specimens each. The control received a 30-minute treatment without any treatment material; the other four groups corresponded to treatment with DayWhite, a 14% hydrogen peroxide whitening material containing potassium nitrate; PreviDent 5000 Sensitive, a desensitizing toothpaste; Relief ACP, a desensitizing gel; or UltraEZ, a desensitizing gel. Potassium nitrate penetration levels were measured spectrophotometrically based on the Griess assay method. Treatment materials were measured for viscosity as a function of shear rate through the use of a cone-and-plate rheometer. RESULTS: Nitrate penetration levels were significantly different among the five groups (p<0.0001, Kruskal-Wallis test). After adjustment for multiple comparisons using an overall 0.05 level of type I error, the distribution of nitrate penetration values was found to differ significantly among all groups with the exception of DayWhite (median: 10.72 µM) and UltraEZ (median: 9.22 µM), which differed significantly from other groups but not from each other. The highest levels of nitrate penetration value were observed for PreviDent (median: 27.61 µM) followed by Relief ACP (median: 19.64 µM). The lowest penetration level was observed for the control group (median: 3.41 µM). Stable end-point viscosities of 11.43 ± 0.67 Pa/s, 1.33 ± 0.06 Pa/s, 0.85 ± 0.09 Pa/s, and 0.40 ± 0.01 Pa/s were observed for UltraEZ, ReliefACP, DayWhite, and PreviDent, respectively. CONCLUSION: Potassium nitrate included in different formulations can penetrate the enamel and dentin within 30 minutes. The level of potassium nitrate penetration is influenced by concentration and may also be partly affected by the viscosity of the material as well as other constituents of proprietary preparations.

Efficacy of do-it-yourself whitening as compared to conventional tooth whitening modalities: an in vitro study.

AIM: To evaluate the efficacy of do-it-yourself (DIY) whitening as compared to conventional tooth whitening modalities using different shade assessment tools. METHODS AND MATERIALS: Extracted human molars (120) were randomly distributed to six groups (n=20). Whitening was performed according to manufacturer's directions for over-the-counter, dentist-dispensed for home use, and in-office whitening. DIY whitening consisted of a strawberry and baking soda mix. Additionally, negative and positive controls were used. Two evaluators used the Vita Classical (VC) and Vita Bleachedguide 3D-Master with interpolated numbers (BGi) for visual assessment at baseline and one-week, one-month, and three-month postwhitening. Instrumental measurements were performed with a spectrophotometer. Kruskal-Wallis procedure was used to assess color changes among groups and intraclass correlation (ICC) to evaluate agreement between evaluators. RESULTS: DIY exhibited lower color change (ΔSGUVC, ΔSGUBGi, ΔE*, where SGU = shade guide unit and E = overall color change) compared to other whitening groups at all time points (p<0.05). ICC demonstrated very good agreement between evaluators with VC and BGi at each time point. Both shade guides were related with each other and strongly related to instrumental measurements (p<0.05). CONCLUSIONS: DIY whitening was the least effective whitening modality. Both VC and BGi are related with each other and have good correlation with instrumental measurements.

Influence of application techniques on contact formation and voids in anterior resin composite restorations.

This study evaluated the influence of three different application techniques on contact formation and voids in anterior resin composite restorations. Artificial ivorine teeth were randomly assigned to three experimental groups, with 20 specimens in each group. One operator performed all restorations using the Teflon tape, pull-through, or bioclear matrix technique. The treatment time required for each restoration was recorded. An examiner blinded to the treatment group performed the visual evaluation of six criteria, including proper contact formation. The restored teeth were cut to yield a total of 180 sections for microscopic evaluation. The Kruskal-Wallis procedure was performed to evaluate the significance of treatment time, number of voids, percent porosity area, and void diameter. There were significant differences in treatment time among the three groups (p<0.05). The bioclear matrix technique required the least time for the treatment of one diastema closure (p<0.05). The Teflon tape technique resulted in proper contact formation in 80% of specimens, a rate that was significantly lower than that associated with the pull-through and bioclear matrix techniques (p<0.05). Out of 540 imaging areas 160 images were free of voids. The number of voids and the percent porosity area were not significantly different among the three techniques (p>0.05). However, the mean void diameter was greater with the bioclear matrix technique compared to the other two techniques (p<0.05).

Intra-articular nuclear factor-κB blockade ameliorates collagen-induced arthritis in mice by eliciting regulatory T cells and macrophages.

Nuclear factor (NF)-κB is a transcription factor implicated in the pathogenesis of autoimmune disorders such as rheumatoid arthritis (RA). Here we have examined the effect of intra-articular administration of the IKK inhibitor, NEMO-binding domain peptide (NBD), on the severity of collagen-induced arthritis (CIA). NBD peptides were injected intra-articularly into the knee joints of DBA/1J mice after the onset of disease. Collagen-injected mice given a scrambled peptide served as controls. Arthritis severity was determined by visual examination of paws. Intra-articular NBD injection reduced the arthritis score and ameliorated morphological signs of bone destruction compared to the controls. Serum levels of type-II collagen-specific immunoglobulin (Ig)G2a antibodies were lower in NBD-treated mice versus the control mice, whereas the levels of type-II collagen-specific IgG1 antibodies were increased by NBD treatment. NBD treatment diminished the proinflammatory cytokines interleukin (IL)-17 and interferon (IFN)-γ in serum, but increased the regulatory cytokine IL-10. NBD-treated CIA mice exhibited significantly higher percentages and numbers of forkhead box protein 3 (FoxP3(+)) CD4(+) CD25(+) regulatory T cells than controls. Immunofluorescence analysis of NBD-treated mice revealed that FoxP3 and Ym1, a marker of alternatively activated macrophages, were juxtaposed to each other within draining inguinal lymph nodes. Intra-articular administration of NBD peptide is effective as an experimental therapy in a murine model of RA. Nevertheless, the intra-articular treatment modality is still associated with systemic effects on the immune system.

The relationship of hydrogen peroxide exposure protocol to bleaching efficacy.

The purpose of this study was to compare two in-office bleaching methods with respect to tooth color change and level of hydrogen peroxide penetration into the pulp cavity and to evaluate relationships between penetration level and color change. Eighty extracted canines were exposed to two different bleaching regimens (conventional vs sealed bleaching technique). After exposure to 38% hydrogen peroxide gel for one hour, hydrogen peroxide amount was estimated spectrophotometrically. Color change was measured per Commission Internationale de l'Eclairage methodology. Linear regression was used to evaluate factors affecting color change, including bleaching technique. The conventional and sealed bleaching groups showed no difference for any color change parameters (ΔL, Δa, Δb, ΔE); however, there was significantly greater hydrogen peroxide penetration in the conventional bleaching group (p<0.05). Linear modeling of the change in lightness (ΔL) showed that the increase in lightness tended to be greater for teeth with lower initial L* values (r=-0.32, p<0.05). After adjustment for initial L*, there was no evidence that ΔL differed with hydrogen peroxide penetration levels (p>0.05) or bleaching technique (mean group difference in ΔL=0.36; p>0.05).

Generation of a temperature-sensitive Edwardsiella tarda mutant and its potential as a prophylactic vaccine in olive flounder (Paralichthys olivaceus).

AIMS: The aim of this study was to generate temperature-sensitive Edwardsiella tarda mutant and to evaluate potential of the mutant as a vaccine in olive flounder (Paralichthys olivaceus). METHODS AND RESULTS: A temperature-sensitive E. tarda mutant was generated by replacement of alr gene promoter with cI857-λP(R) promoter system plus another CI857 expression cassette that was driven by a constitutive promoter of E. tarda (EtPR C28-1). Growth of the mutant strain was not different to that of wild-type E. tarda under conditions of culture at 39°C. However, growth of the mutant strain was retarded by culturing at 25 or 20°C without d-alanine. To further inhibit leakage of λP(R) promoter, the mutant strain was transformed with a vector harbouring an EtPR C28-1-driven cI857 cassette (pEtPR-cI857), which resulted in more limited growth compared to the mutant without the plasmids. The level of alr gene transcription in the mutant E. tarda and the mutant harbouring pEtPR-cI857 was well coincided with the result of bacterial growth. Olive flounder fingerlings immunized with the E. tarda mutant showed decreased mortality, and a boost immunization induced 100% protection against E. tarda infection. The protection rate of fish was proportional to the serum agglutination titre against E. tarda. CONCLUSIONS: An attenuated E. tarda mutant induced by shifting down temperature below 30°C was firstly generated. Immunization of fish with the mutant led to protection against virulent E. tarda challenge. SIGNIFICANCE AND IMPACT OF THE STUDY: The results suggest that the present temperature-sensitive E. tarda mutant can be a good candidate for effective vaccines for prophylaxis of edwardsiellosis. Moreover, as the present E. tarda mutant can be cultured without supplementation of the specific nutrient and can be attenuated just by decreasing temperatures below 30°C, vaccines based on the present E. tarda mutant would be advantageous in an economical aspect.

Penetration pattern of rhodamine dyes into enamel and dentin: confocal laser microscopy observation.

Enamel and dentin are susceptible to extrinsic and intrinsic stains. The purposes of this study were to determine the penetration pattern of Rhodamine B and dextran-conjugated Rhodamine B into the enamel and dentin as observed by confocal laser microscopy and to relate it to the penetration pattern of hydrogen peroxide commonly used as an active ingredient in tooth-whitening agents and high-molecular-weight staining molecules. Eighteen recently extracted human maxillary anterior teeth were used. Teeth were cleaned and painted with nail varnish except for the crown area above the cemento-enamel junction (CEJ). The painted teeth were then immersed in Rhodamine B and dextran-conjugated Rhodamine B (70 000 MW) for 4, 7, 10 and 15 days. Teeth were sliced to 3 mm thickness in transverse plane and mounted on a glass slide just prior to observation with confocal laser microscopy. Rhodamine B and dextran-conjugated Rhodamine B readily penetrated into the enamel and dentin when exposed for 4 and 7 days, respectively. Rhodamine B penetrated along the interprismatic spaces of the enamel into the dentin. The penetration was accentuated in sections with existing crack lines in the enamel. Rhodamine B was readily absorbed into the dentinal tubules at the dentino-enamel junction and continued to penetrate through the dentin via the dentinal tubules into the pre-dentin. Within the limitations of this study, it is concluded that Rhodamine B and dextran-conjugated Rhodamine B when applied to the external surface of the tooth readily penetrate into the enamel and dentin via the interprismatic spaces in the enamel and dentinal tubules in the dentin, suggesting that stain molecules and bleaching agents possibly exhibit similar penetration pathways.

Treatment of Microcotyle sebastis infestation in cultured rockfish Sebastes schlegeli by oral administration of praziquantel in combination with cimetidine.

The effect of cimetidine on the treatment efficacy of praziquantel against Microcotyle sebastis infestation in cultured rockfish Sebastes schlegeli was investigated. Juvenile rockfish were divided into 7 groups, and orally administered praziquantel alone (50, 100 and 200 mg kg(-1) body wt, BW) or in combination with cimetidine at a dose of 200 mg kg(-1) BW for each praziquantel dose. The fish in the control group were administered only saline. The results clearly showed that coadministration of cimetidine with praziquantel led to a significantly increased treatment efficacy of the latter drug, and consequently would lead to a lowering of the total dose of praziquantel, and a reduction in the administration times and costs for the treatment of M. sebastis infestation in cultured rockfish.