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Purpose: To evaluate the shear bond strength (SBS) of resin composite to dentin contaminated with artificial saliva (AS) containing mucin and amylase using an experimental method controlling the volume of saliva and adhesive in a defined surface area., Methods: Flat bonding surfaces were prepared on extracted human molars (320 grit surface). Using adhesive tape, a 4.5 mm bonding window was prepared on the dentin surfaces. Groups (n= 12) were prepared using the etch & rinse (ER) or self-etch (SE) modes for Adhese Universal (ADH), Scotchbond Universal Plus (SBU), and Prime & Bond active (PBA) dental adhesives (DA). For the control (C) groups, the adhesives were applied per the manufacturers' instructions with 2.0 µl or 3.0 µl of the adhesive. For the saliva-contaminated groups, 1.0 µl of artificial saliva with mucin was applied in the bonding window either dried or allowed to remain wet before the application of either 2.0 µl or 3.0 µl of the adhesive. After the adhesive film was air dried and light cured using an Ultradent bonding fixture, Spectrum TPH3 was bonded to the prepared surfaces. After water storage for 24 hours at 37°C, the specimens were debonded and shear bond strength (SBS) was calculated (MPa). A Kruskal-Wallis test with Bonferroni correction was used to determine group differences (P< 0.05). Scanning electron microscopy (SEM) was performed to visualize the interfacial surfaces prepared using an ion-etching technique., Results: Mean SBS for the three adhesives were similar in both ER and SE modes to uncontaminated dentin surfaces for all the control groups. For dentin contaminated with dried or wet saliva, both the surface condition and the adhesive system were significant factors at a confidence level of 95%. For the dried saliva test groups, ADH and PBA with 3.0 µl of adhesive generated similar SBS values to controls while SBU generated lower values. Lower values were generated when using 2.0 µl of adhesive for the three adhesives in SE and ER modes except for PBA in the ER mode. Using wet saliva and 3.0 µl of adhesive ADH and SBU generated lower SBS values while PBA generated similar values to controls. Under SEM, morphology at the adhesive dentin interfaces was similar among the adhesives to uncontaminated dentin but notable differences were observed for SBU and ADH for both wet and dried saliva-contaminated surfaces., Clinical Significance: Salivary contamination differentially affects shear bond strength and the morphology of the bonded interface of universal adhesives to dentin. These differences are specific to the adhesive tested and are influenced by using the etch and rinse or self-etch strategies and the volume of adhesive used. When concerned about salivary contamination clinically, maximizing the volume of adhesive on the substrate may help mitigate the deleterious effects of saliva contamination., Competing Interests: The authors declared no conflict of interest. This study was supported through a research grant awarded to Creighton University School of Dentistry. Frank Pfefferkorn and Luisa Antunes are employees of Dentsply/Sirona. The research was conducted at Creighton University, Omaha Nebraska, Nihon University, Tokyo Japan, and the Center of Excellence for Polymer Development, Konstanz, Germany., (Copyright©American Journal of Dentistry.)

Purpose: To evaluate the effect of different finishing and polishing systems on the surface roughness of a resin composite subjected to simulated saliva-, acid-, and enzyme-induced degradation., Methods: 160 specimens (n= 40) were fabricated with Filtek Z350 XT nanofilled composite and analyzed for average surface roughness (Ra). The specimens were finished and polished using: AD - Al₂O₃-impreginated rubberized discs (medium, fine, and superfine grit, Sof-Lex); SD - silicon carbide and Al₂O₃-impregnated rubberized discs (coarse, medium and fine grit, Jiffy,); MB - 12- and 30-multiblade burs. The control group (CT) (n= 40) comprised specimens with a Mylar-strip-created surface. Specimens from each group were immersed in 1 mL of one of the degradation methods (n= 10): artificial saliva (ArS: pH 6.75), cariogenic challenge (CaC: pH 4.3), erosive challenge (ErC: 0.05M citric acid, pH 2.3) or enzymatic challenge (EzC: artificial saliva with 700 µg/mL of albumin, pH 6.75). The immersion period simulated a time frame of 180 days. Ra measurements were also performed at the post-polishing and post-degradation time points. The data were evaluated by three-way ANOVA for repeated measures and the Tukey tests., Results: There was significant interaction between the finishing/polishing system and the degradation method (P= 0.001). AD presented the greatest smoothness, followed by SD. After degradation, CT, AD and SD groups became significantly rougher, but not the MB group, which presented no difference in roughness before or after degradation. CT and AD groups showed greater roughness in CaC, ErC and EzC than in ArS. The SD group showed no difference in roughness when the specimens were polished with CaC, EzC or ArS, but those treated with ErC had greater roughness. In the MB group, the lower roughness values were found after using CaC and EzC, while the higher values were found using ErC or ArS., Clinical Significance: As far as degradation resistance of nanofilled composite to hydrolysis, bacterial and dietary acids and enzymatic reactions is concerned, restorations that had been finished and polished with Al₂O₃-impregnated discs had the smoothest surfaces., Competing Interests: The authors declared no conflict of interest., (Copyright©American Journal of Dentistry.)

Purpose: To determine the microhardness, color change, surface roughness, and micromorphology of tooth enamel submitted to bleaching treatment with 7.5% hydrogen peroxide (HP) with added calcium, amorphous calcium phosphate, sodium fluoride (NaF), and hydroxyapatite (HA)., Methods: 80 enamel slabs were used (n = 10). Three commercial agents [Pola Day 7.5%, Day White ACP 7.5% (DW-ACP), and White Class Calcium 7.5% (WC-Calcium)], three experimental (7.5% HP+NaF, 7.5% HP+HA, and 7.5% PH+NaF+HA), a positive control (with HP), and a negative control (without HP) groups were assessed. The commercial products were applied according to manufacturers' recommendations and the experimental ones were applied for 1.5 hours daily. During and after treatment, specimens were stored in artificial saliva. Tests were performed at baseline, 7, 14, 21, 28, and 35 days. Data were analyzed by ANOVA and Tukey's test (α = 0.05)., Results: DW-ACP presented lower microhardness and HP+HA presents the highest values (P < 0.05); only the experimental group presented color change similar to the commercial agents (P > 0.05). Overall, roughness increased with time (P < 0.05) and porosities, and deposition of crystalline structures in groups HP+HA and HP+NaF+HA were noted. The HP+HA agent was capable of reducing the loss of enamel microhardness due to bleaching and also present color change similar to the commercial products.

Purpose: To evaluate the influence of brushing using toothpastes marketed under different categories on abrasion of sound and eroded enamel in vitro at nanometer scale using a white light interferometer (WLI)., Methods: Enamel surface of resin-embedded bovine incisors were fine polished with diamond slurry and divided into testing area (approximately 2 mm x 4 mm) and reference area using a nail varnish. The enamel specimens were randomly assigned to 10 groups (n = 10 each); six of which were subjected to erosive challenge. The testing area in these eroded groups was exposed to 10 ml of Coca-Cola for 90 seconds and then rinsed for 10 seconds in deionized water (DW). Enamel specimens, except for those in one eroded group, were brushed by an automatic brushing machine with 120 linear motion strokes in 60 seconds under load of 250 g with/without toothpaste slurry. After the toothbrushing abrasion, each specimen was rinsed for 10 seconds with DW followed by immersion in artificial saliva for 2 hours. Toothpaste slurries were prepared containing one of the four toothpastes used and DW in a ratio of 1:2. The erosion-abrasion cycle was repeated three times. Then, the nail varnish was removed and enamel surface loss (SL) was measured by the WLI. Data were statistically analyzed by one-way ANOVA followed by Bonferroni's correction at significance level of 0.05., Results: For eroded specimens, the mean SL values of groups not brushed and brushed with no toothpaste were not significantly different, but were significantly lower than those of whitening, anti-erosion and anti-caries toothpaste groups (P < 0.001). The whitening toothpaste group showed significantly higher SL than all other groups (P < 0.001). For sound enamel specimens, SL was not measured except for the whitening toothpaste group.

Purpose: To analyze whether immersion in sodium fluoride (NaF) solutions and/or common acidic beverages (test solutions) would affect the surface roughness or topography of lithium disilicate ceramic., Methods: 220 ceramic discs were divided into four groups, each of which was subdivided into five subgroups (n = 11). Control group discs were immersed in one of four test beverages for 4 hours daily or in artificial saliva for 21 days. Discs in the experimental groups were continuously immersed in 0.05% NaF, 0.2% NaF, or 1.23% acidulated phosphate fluoride (APF) gel for 12, 73, and 48 hours, respectively, followed by immersion in one of the four test beverages or artificial saliva. Vickers microhardness, surface roughness, scanning electron microscopy (SEM) associated with energy dispersive spectroscopy, and atomic force microscopy (AFM) assessments were made. Data were analyzed by nested analysis of variance (ANOVA) and Tukey's test (α = 0.05)., Results: Immersion in the test solutions diminished the microhardness and increased the surface roughness of the discs. The test beverages promoted a significant reduction in the Vickers microhardness in the 0.05% and 0.2% NaF groups. The highest surface roughness results were observed in the 0.2% NaF and 1.23% APF groups, with similar findings by SEM and AFM. Acidic beverages affected the surface topography of lithium disilicate ceramic. Fluoride treatments may render the ceramic surface more susceptible to the chelating effect of acidic solutions.

Purpose: To investigate the effects of desensitizing agents on dentin tubule occlusion, acid and tooth brushing challenge, and microhardness change of human dentin., Methods: Partially demineralized dentin slabs were divided into four groups (n = 30): (1) Control, (2) Non-desensitizing toothpaste, (3) Pro-Argin toothpaste, (4) CPP-ACP paste. The specimens were treated with these dentifrices for 2 minutes/day and soaked in artificial saliva (AS) for 24-hour remineralization. Then the dentin discs were divided into three subgroups for removal resistance tests: acid challenge, mechanical brushing challenge and blank control. Changes in dentin morphology were observed using scanning electron microscopy (SEM). Vickers microhardness measurements were performed at baseline and after 24-hour remineralization for all groups., Results: A surface layer and intra-tubular crystals were observed in SEM imaging of Pro-Argin toothpaste and CPP-ACP paste groups, which occluded most of the dentin tubules for those specimens. But the dentin tubules were opened after the acid challenge again. Moreover, the dentin microhardness showed a slight increase after 24-hour AS immersion. The percentage microhardness gain (PMG) values of these two groups were 5.4% and 5.1% respectively, which were significantly higher than the other groups (P < 0.05).

Purpose: To compare the dentin tubule-occluding ability of fluoroaluminocalciumsilicate-based (Nanoseal), calcium phosphate-based (Teethmate Desensitizer), resin-containing oxalate (MS Coat ONE) and diamine silver fluoride (Saforide) dentin desensitizers using artificially demineralized bovine dentin., Methods: Simulated hypersensitive dentin was created using cervical dentin sections derived from bovine incisors using phosphoric acid etching followed by polishing with a paste containing hydroxyapatite. The test desensitizers were applied in one, two, or three cycles, where each cycle involved desensitizer application, brushing, and immersion in artificial saliva (n= 5 each). The dentin surfaces were examined with scanning electron microscopy, and the dentin tubule occlusion rate was calculated. The elemental composition of the deposits was analyzed with electron probe microanalysis. Data were analyzed by one-way ANOVA and the Tukey honestly significant different test., Results: Marked deposit formation was observed on the specimens treated with Nanoseal or Teethmate Desensitizer, and tags were detected in the specimens' dentin tubules. These findings became more prominent as the number of application cycles increased. The major elemental components of the tags were Ca, F, and Al (Nanoseal) and Ca and P (Teethmate Desensitizer). The tubule occlusion rates of MS Coat ONE and Saforide were significantly lower than those of Nanoseal and Teethmate Desensitizer (P< 0.05).

Purpose: To compare the effect of different treatments (heat capsule, ultrasound, and dual treatments) on the setting kinetics and maturation properties of a conventional GIC (EQUIA, GC) to that of standard setting., Methods: The optimal durations of the heat and ultrasonic treatments were determined by monitoring changes in the COO-/COOH ratio, surface hardness, and temperature within the samples. The influence of optimal treatments on the maturation properties of the GIC (microhardness, and 3-point flexural strength) were assessed using GIC samples incubated in artificial saliva for 24 hours, 1 month, and 3 months., Results: The optimal durations of the heat and ultrasonic treatments for accelerating setting were 5 minutes and 35 seconds, respectively. The dual treatment using the optimal conditions of the individual treatments further enhanced the setting kinetics. A temperature peak (49°C) within the GIC was detected during setting. Only the dual treatment increased the mechanical properties of the GIC after 24 hours compared to the control, while no significant difference was observed after 1 and 3 months.

Purpose: To analyze the efficacy of Colgate Plax Whitening mouthwash containing 1.5% hydrogen peroxide., Methods: 30 enamel fragments, obtained from the proximal surfaces of human third molars were darkened with Orange II methyl orange. The fragments were divided into three groups according to the type of bleaching agent applied (n = 10): (1) 10% carbamide peroxide gel (positive control, PC) was applied for 2 hours/day for 28 days; (2) a solution containing 1.5% hydrogen peroxide (Plax) was applied for 4 minutes once a day for 28 days, and (3) no bleaching agent, kept in artificial saliva (negative control, AS). The specimens were kept in artificial saliva between treatment intervals. The specimens were photographed before darkening (baseline), after darkening and before lightening and on the 28th day of whitening. Afterwards, they were analyzed with color measurement software using the CIELab system. The data for the L*, a* and b* parameters were submitted to two-way ANOVA with repeated measures. The values of deltaL *, deltaa *, deltab * and deltaE* were calculated using two procedures: (1) darkened versus original, and (2) bleached versus darkened. This data was submitted to the one-way ANOVA test. Multiple comparisons were conducted using the Tukey test (alpha = 0.05)., Results: When the specimens were subjected to bleaching agents, there was a significant increase in the brightness (L* parameter) of the enamel exposed to the gel and also to the bleaching solution. However, higher brightness was observed for the PC (gel) group. As for the axis a* parameters, there were no significant differences between the bleaching products. Regarding the axis b* parameters, the PC group underwent major changes (indicating a color change toward blue chroma), statistically greater than those of the Plax group. After bleaching, there was a significantly greater color change (deltaE*) in the PC group. Although the Plax solution caused a color change, it was less than that produced by the gel. The slightest color change was observed in the control group, in which no bleach was used. The mouthwash containing hydrogen peroxide was able to lighten the darkened human enamel, but to a lesser degree than the lightening produced by 10% carbamide peroxide.

Purpose: To evaluate in vitro root caries formation in human permanent teeth and to determine the effects of commercially available dentifrices containing different amounts of fluoride, while employing a well-tested artificial caries system using an acidified gel., Methods: Root surfaces from caries-free human permanent teeth (n = 10) underwent debridement and fluoride-free prophylaxis. The tooth roots were sectioned into six portions, and acid-resistant varnish was placed with two sound root surface windows exposed on each tooth portion. Each portion from a single tooth was assigned to a treatment group: (1) No treatment control; (2) Denticious 5000 dentifrice (5,000 ppm F + xylitol); (3) PreviDent 5000 (5,000 ppm F); (4) AIM dentifrice (1,500 ppm F); (5) Listerine dentifrice (1,300 ppm F); and (6) Crest Regular Paste (1,500 ppm F). Tooth portions were treated with fresh dentifrice twice daily for 180 seconds, followed by fresh synthetic saliva rinsing over a 7-day period. Controls were exposed twice daily to fresh synthetic saliva rinsing over a 7-day period. In vitro root caries were created using an acidified gel (pH 4.25, 21 days). Longitudinal sections (three sections/tooth portion, 30 sections/group; 60 lesions/group) were evaluated for mean lesion depths (water imbibition, polarized light). Statistical analyses were performed using ANOVA and Duncan's Multiple Range test., Results: Mean lesion depths were 389 +/- 43 microm for No treatment - control, 223 +/- 33 microm for Denticious 5000 dentifrice, 242 +/- 42 microm for Prevident 5000, 337 +/- 29 microm for AIM dentifrice, 297 +/- 37 microm for Listerine dentifrice, and 282 +/- 34 microm for Crest Regular Paste dentifrice. All treatment groups had mean depths significantly less than the No treatment - control group (P < 0.05). Denticious 5000 and PreviDent 5000 had significantly reduced mean depth compared with the other dentifrice treatment groups (P < 0.05).

Purpose: To assess in vitro the effect on enamel erosion (ERO) and erosion followed by abrasion (ERO+ABR) of varnishes with different fluoride concentrations, supplemented or not with sodium trimetaphosphate (TMP)., Methods: Bovine enamel blocks were randomly divided into six groups according to the type of varnish used: placebo (no F), NaF 5%, NaF 2.5%, NaF 2.5% plus TMP 3.5%, NaF 2.5% plus TMP 5%, NaF 2.5% plus TMP 10%. Varnishes were tested for ERO and ERO+ABR, separately for 3 and 5 days. ERO was done by immersion in Sprite Zero (5 minutes, 4x/day), while ERO+ABR was performed by brushing for 15 seconds after each erosive challenge. Enamel wear (microm) and cross-sectional hardness (AKHN) were assessed after the experimental periods. Data were analyzed by ANOVA, Tukey's test and Pearson's correlation coefficient (P< 0.05)., Results: Varnishes supplemented with TMP promoted significantly lower wear and hardness loss when compared to the other treatments in all conditions studied (P< 0.05). Similar wear rates were observed for the placebo, NaF 2.5% and NaF 5% varnishes (P> 0.05). Greater wear was observed after 5 days of ERO and ERO+ABR when compared with 3 days (P< 0.05). Positive and significant correlations were found between enamel wear and AKHN. No dose-response relationship was found between TMP concentration and wear and hardness. It was concluded that fluoride varnishes supplemented with TMP had a higher protective effect against ERO and ERO+ABR, which was associated with a reduction in enamel softening.

Purpose: To evaluate the effects of a surface pre-reacted glass-ionomer (S-PRG) filled coating material to arrest artificial enamel lesions in primary teeth., Methods: Buccal and lingual enamel was demineralized in 0.1 M lactic acid buffer solution (pH 4.75) for 5 days and then divided in the PRG-applied and non-PRG areas. Proximal surfaces were used as a control area without demineralization and coating application. Teeth were divided into three groups (n = 4) according to the 1-week immersion in different solutions: Group 1 (distilled water), Group 2 (demineralizing solution) and Group 3 (artificial saliva). Hardness and Young's modulus by nano-indentation test, and elemental contents and ultrastructure by SEM/EDX analysis were obtained. Data were statistically analyzed using ANOVA and Fisher's PLSD at alpha = 0.05., Results: Only for the non-PRG area in Group 1, the hardness and Young's modulus of the demineralized surface enamel were significantly lower than those of the enamel 30-60 microm beneath the surface. Demineralized enamel of non-PRG and PRG-applied areas showed similar SEM views. Only for the non-PRG area in Group 2 and control area in Group 3, the Ca/P of the surface enamel was significantly higher than that of the enamel 5-10 microm beneath the surface. There was no significant difference of the Ca/P among the measuring points from the surface to 10 microm depth of enamel for the PRG applied area in Group 2.

Purpose: To investigate the effect of a fluoride-containing aluminocalciumsilicate nanoparticle glass dispersed aqueous solution (Nanoseal) on enamel and dentin, under the hypothesis that this material can form insoluble mineral deposits that confer acid resistance to the tooth structure and occlude open dentin tubules., Methods: Labial enamel and dentin of human extracted incisors were used. Morphology of the enamel and dentin artificially demineralized with a lactic acid solution that before and/or after coated with the test material were analyzed with a wavelength-dispersive X-ray spectroscopy electron probe microanalyzer with an image observation function (SEM-EPMA). Moreover, incorporation of the calcium and silicon by enamel and dentin were also detected with SEM-EPMA., Results: Application of the fluoroaluminocalciumsilicate-based tooth coating material resulted in the deposition of substances (nanoparticles) onto the enamel surface porosities and open dentin tubules on the artificial lesions. Prior coating with the test material reduced the demineralization-induced loss of enamel and dentin. Moreover, Ca and Si incorporation into superficial enamel and dentin was detected.

Purpose: To evaluate the effects of experimental xylitol dentifrices with and without fluoride on in vitro root caries formation., Methods: Root surfaces from caries-free human permanent teeth (n = 10) underwent debridement and a fluoride-free prophylaxis. The tooth roots were sectioned into quarters, and acid-resistant varnish was placed with two sound root surface windows exposed on each tooth quarter. Each quarter from a single tooth was assigned to a treatment group: (1) No treatment control; (2) Aquafresh Advanced (0.15% F = 1,150 ppm F); (3) Experimental xylitol dentifrice without fluoride (0.45% xylitol); and (4) Diamynt fluoride dentifrice with xylitol (0.83% sodium monofluorophosphate = 1,100 ppm F and 0.20% xylitol). Tooth root quarters were treated with fresh dentifrice twice daily (3 minutes) followed by fresh synthetic saliva rinsing over a 7-day period. Controls were exposed twice daily to fresh synthetic saliva rinsing daily over a 7-day period. In vitro root caries were created using an acidified gel (pH 4.25, 21 days). Longitudinal sections (three sections/tooth quarter, 60/group) were evaluated for mean lesion depths (water inhibition, polarized light, ANOVA, DMR)., Results: Mean lesion depths were 359 +/- 37 microm for the control Group; 280 +/- 28 microm for Aquafresh Advanced; 342 +/- 41 microm for the experimental xylitol dentifrice without fluoride; and 261 +/- 34 microm for Diamynt. Aquafresh Advanced and Diamynt had mean lesion depths significantly less than those for the no treatment control and the experimental xylitol without fluoride dentifrice (P< 0.05). There were minimal non-significant differences in mean lesion depths between Aquafresh Advanced and Diamynt (P > 0.05).

Purpose: To evaluate the fluoride concentration in enamel after the use of different fluoride products and 48 hours after the cessation of fluoride use., Methods: 16 enamel slabs were divided and treated for 15 days as following: Group A, with an amine fluoride toothpaste and mouthrinse (1400 and 250 mg/L(-1), respectively); Group B, with an amine fluoride toothpaste (1400 mg/L(-1)) and mouthrinse without fluoride; Group C, with a sodium fluoride toothpaste (1400 mg/L(-1)) and mouthrinse (250 mg/L(-1)). Chemical biopsy and multiple means were used to determine fluoride concentration. The data were statistically analyzed using the two-way ANOVA and Tukey HSD tests (P<0.05)., Results: After 15 days of fluoride product use, Group A samples had the highest fluoride uptake (0.19 microg mm(-2)) (P<0.05). 48 hours after the interruption of fluoride product usage, a higher fluoride concentration was found in Group A samples. Although all fluoride products led to an enamel uptake, amine fluoride products promoted the most effective long-term uptake.

Purpose: To examine the laboratory dentin tubules occlusion and mineral precipitation capability of two potassium salts-containing desensitizing toothpastes., Methods: 40 dentin disks were obtained and divided into four groups, including artificial saliva (AS), distilled water (DW), Sensodyne Freshmint (SF) and Colgate Sensitive (CS). Dentin permeability measurement was performed after EDTA etching, initial brush, 3-day brush, 7-day brush and citric acid challenge, respectively. Attenuated total reflection Fourier transform infrared spectroscopy (ATR-FTIR) was used to monitor the variation of mineral content before and after treatments. The ultra-morphology of dentin surface was examined using scanning electron microscopy (SEM) to evaluate tubule occlusion., Results: The two potassium salts-containing desensitizing toothpastes significantly reduced dentin permeability to less than 40% after 7-day treatment (P<0.05). The ATR-FTIR analysis showed increase of the intensity of the phosphate peak after a 7-day brushing period using both of the tested toothpastes. However, the dentin permeability significantly increased and the intensity of phosphate peak decreased after acid etching for all groups. The SEM examination revealed partially occluded dentin tubules after toothpaste treatments, but after the acid challenge the tubules were opened again.

Purpose: To evaluate the effect of casein phosphopeptide-amorphous calcium phosphate (CCP-ACP) application on the microhardness of bleached enamel and compare it to that of fluoride application., Methods: 10 extracted bovine incisors were cut into four sections (4 x 4 x 3 mm) that were randomly distributed among five groups (n = 8). All groups were bleached three times using 38% hydrogen peroxide (HP), with 5-day intervals between bleaching, according to the following treatment protocols: Group A: bleaching only; Group B: bleaching + daily CCP-ACP paste; Group C: bleaching + daily casein phosphopeptide-amorphous calcium fluoride phosphate (CPP-ACPF) paste; Group D: bleaching + daily 250ppm NaF solution; Group E: bleaching + APF gel (once after final bleaching). Specimens were maintained in artificial saliva throughout the experiment. Baseline and post-treatment Vickers microhardness values were obtained for all specimens. Statistical analysis was performed using one-way ANOVA and post-hoc Tukey tests., Results: Groups B and C showed significant increases in enamel microhardness following treatment (P < 0.001), whereas no statistically significant changes were observed in Groups A, D, or E (P > 0.05). One-way ANOVA of delta Vickers microhardness numbers (deltaVHN) revealed significant differences among groups (P < 0.001), with Group B showing the highest deltaVHN and Group A the lowest.

Purpose: To establish methods to quantitate the physical surface change, not the chemical color bleaching change, of enamel occurring with hydrogen peroxide treatment in solution and commercially available plastic strips., Methods: Bovine enamel was polished to a sound, uniform, optical flat, white subsurface that was used as the initial substrate for all substrate modification, treatment and instrumental measurement using digital photography-image analysis, SEM and profilometry. Sound enamel was treated with 10, 20 and 30% solutions of hydrogen peroxide. Plastic strips were used to treat both sound and acid modified enamel surfaces. Etched enamel, similar to a 10-second exposure to lemon juice, was treated with 0.5, 1, 3, 5, 10, and 15% hydrogen peroxide for 24-hour exposure at 37 degrees C to obtain a dose response curve to this modified enamel., Results: The digital photography-image analysis system and scanning electron microscopy (SEM) were effective in detecting enamel surface porosity and structure disruptive changes, respectively. Plastic strip treatment of both sound and etched enamel produced little surface change. Measurable surface change of etched enamel was detected with as low as 1% hydrogen peroxide in solution. The surface change with 15% hydrogen peroxide was statistically significant. Dye uptake as measured by image analysis indicated an increase in surface porosity that was more evident with the acid modified surface. SEM studies were consistent with this observation.

Purpose: To examine the remineralization effects of a bioerodible fluoridated resin., Methods: 36 extracted permanent molars were suspended into an artificial caries solution to create an artificial caries-like lesion. Teeth were sectioned longitudinally to obtain 100 microm sections containing the artificial caries-like lesion, then photographed with polarized light microscopy in an imbibition media of water, representing a minimum of 5% pore volume. An acid-resistant varnish was applied to the surfaces of the sections, leaving only the natural external tooth surface and caries-like lesion exposed. The external tooth surface of 12 samples had 5% sodium fluoride varnish applied, 12 samples had 5% sodium fluoride bioerodible resin applied, and the remaining samples acted as controls. The sections were returned to the tooth, placed in an artificial saliva solution and brushed daily for 30 days. The sections were removed and photographed under polarized light as before. Using a computerized imaging system, the area of the body of the lesion was measured, comparing the same section before and after the 30-day experimental period to evaluate the remineralization process., Results: The mean percent area remineralization (+/-SD) was: bioerodible fluoridated resin 44.1 +/- 12.1; fluoride varnish 19.1 +/- 9.2; control 2.4 +/- 3.4. ANOVA indicated a significant variance among groups (P < 0.001). Tukey's multiple comparison test demonstrated the fluoridated resin to enhance remineralization significantly greater (P < 0.001) than the fluoride varnish and control and the fluoride varnish to enhance remineralization significantly greater (P < 0.002) than the control.

Purpose: To compare the remineralization of incipient artificial interproximal caries in the presence of three glass-ionomer cements (highly-filled glass-ionomer cement, compomer, resin-modified glass-ionomer cement) and a resin composite (control)., Methods: Proximal restorations were simulated by placing tooth specimens and the various glass-ionomer cements in closed containers with artificial saliva at 37 degrees C and pH 7.0 for 30 days with constant circulation. Tomographic images were obtained with a micro CT scanner at 90, 180, and 270 days, and density-measuring software was used to calculate the micro-density of artificial caries lesions in the specimens. The mean density changes were compared between groups in order to evaluate the effects of remineralization. All data were analyzed using one-way ANOVA and the post-hoc Tukey multiple comparison test at P < 0.05., Results: While the density of artificial caries lesions increased for all treatments, the increases for the three glass-ionomer groups were significantly higher than that for the resin group in each 3-month period. As time increased, the amount of density also increased for the glass-ionomer groups, and significant differences were found between the remineralization effects of the glass-ionomer groups. The micro CT proved to be an effective evaluation method.

Purpose: To evaluate the microhardness and shear bond strength of human enamel treated with an 18% carbamide peroxide bleaching varnish., Methods: 40 dental enamel slabs were embedded and ground flat, dividing them into four groups (n=10) which received the varnish application for 14 consecutive days: (G1) one daily varnish application; (G2) two daily varnish applications with an interval of 15 minutes; (G3) two daily varnish applications with an interval of 5 hours. After varnish application, the slabs were immersed in artificial saliva changed daily. The control group (G4) consisted of slabs (n=10) that did not receive any varnish treatment and were maintained in artificial saliva for 14 days. Microhardness tests were performed with Knoop indentation with a load of 25 grams for 5 seconds at the beginning of the treatment (baseline values) and after 7 and 14 days. Cylinders were made with microhybrid resin composite and one-bottle adhesive system for shear bond strength tests. Using a universal testing machine with a speed of 0.5 mm/minute to obtain the values in MPa., Results: The Kruskal-Wallis test showed no changes in microhardness values among groups after 7-day varnish application, although there was a decrease in microhardness values when using an 18% carbamide peroxide varnish twice a day with a time-interval of 5 hours between applications (P < 0.05). For enamel shear bond strength, ANOVA test (P > 0.05) did not show significant differences among the groups (G1=15.8; G2=15.2; G3=19.0; G4=15.1).

Purpose: To assess the shear bond strength of resin composite to human enamel and dentin after using a whitening dentifrice containing carbamide peroxide for 21 days., Methods: Thirty enamel and 30 dentin slabs were embedded, flattened and randomly divided into three groups (n=10) that received different treatments: carbamide peroxide containing dentifrice (Rembrandt Plus), fluoride containing dentifrice (Close Up with fluoride), and immersion in artificial saliva as the control group. Applications were made for a 15-minute period daily, immersing the slabs in a suspension with distilled water and dentifrice in the ratio of 3:1 (weight) for 21 days. For the rest of the time, the slabs were kept in an artificial saliva solution. After the last application, an adhesive system (Single Bond) was used to bond resin-based composite cylinders (Z100) to the enamel and dentin surfaces for the shear bond strength tests. These tests were carried out in a universal testing machine at a speed of 0.5 mm/minute., Results: ANOVA and the Tukey test for enamel and Kruskal-Wallis and the Dunn Method for dentin, showed significant differences between slabs treated with Rembrandt Plus (REM) and the artificial saliva control group, with higher values for REM (P < 0.05). There were no differences in mean bond strengths of enamel and dentin treated with Close Up with fluoride (CLO) and REM, nor were any differences shown between CLO and the artificial saliva control group. A whitening dentifrice containing carbamide peroxide increased the bond strength of restorative systems.

Purpose: To evaluate the microhardness and surface roughness of enamel and root dentin bleached with 10%, 15% and 22% carbamide peroxide agents., Methods: 52 slabs of enamel and root dentin (6 x 3 x 2 mm) were cut from bovine incisors, ground flat and polished. According to a randomized complete block design, enamel and root dentin slabs (n = 13) were independently allocated to be bleached with one of the following carbamide peroxide-containing agents (CP): 10% (Rembrandt Bleaching Gel Plus), 15% (Rembrandt Xtra Comfort), or 22% (Rembrandt Xtra Comfort Ultra Strength). The control groups were mock-treated with artificial saliva. The bleaching procedures consisted of daily application of the agents on dental substrate surfaces for 2 hours, followed by immersion in artificial saliva for 22 hours over 21 days. Knoop microhardness and surface roughness were measured initially, on sound dental tissues, and at the postbleaching phase., Results: In enamel, microhardness attained after bleaching with 10% CP and 15% CP were similar and significantly lower than that observed for the control group. Specimens bleached with CP 22% did not differ from any of the other groups tested. In root dentin, microhardness changes were indistinguishable. ANOVA showed no significant difference among treatments with respect to surface roughness.

Purpose: To design an artificial mouth in order to evaluate if a new diagnostic tool (Clinpro Cario Diagnosis) can be used for early detection of secondary caries at resin composite margins in vitro., Methods: 32 intact human third molars received standardized Class-V resin composite restorations (Tetric Ceram bonded with Syntac SC). After storage for 4 weeks at 37 degrees C, teeth were subjected to 5,000 or 10,000 thermocycles (+/- 5 degrees C and +/- 55 degrees C) and polysiloxane impressions were taken. Streptococcus mutans 10449 (SM) was used in a nutrition medium to initiate a secondary caries process. Daily, the teeth were incubated for 2 x 2.5 hours in SM containing nutrition medium followed by 2 x 9.5 hours incubation in artificial saliva. Teeth were investigated after total incubation periods of 4, 6, and 8 weeks. After the different incubation protocols, the restoration margins were evaluated for infection and secondary caries processes in using Clinpro Cario Diagnosis which measures site-specifically the lactic acid production of SM in response to a sucrose challenge. The color signal was read 5 minutes after removal of the diagnostic impression. After thermocycling and biological load cycling, precision polysiloxane impressions were taken and replicas were investigated under a light microscope for gap widths at enamel and dentin margins. Demineralization was evaluated by fluorescence microscopy in using a special FITC filter. The demineralization depths at the cavity margin were calculated with Xpert for Windows using a pixel distance of 5 microm., Results: After the different thermocycling protocols, no differences in gap widths and demineralization depths were found (P > 0.05). After SM incubation, gap widths and demineralization depths were significantly dependent on SM incubation time and previous number of thermocycles (P < 0.05). Lactic acid formations of SM were detectable by Clinpro Cario Diagnosis at dentin cavosurface margins formed after 6 weeks of incubation with SM (P < 0.05).

Purpose: To evaluate the in vitro differential effect of sonic energy, delivered by Sonicare Advance, on cariogenic and non-cariogenic bacteria biofilms., Methods: A wild strain of Streptococcus mutans, Lactobacillus acidophilus, Streptococcus salivarius and Veillonella alcalescens was isolated from human dental plaque. For each of the four microorganisms a biofilm adherent to bovine enamel disks, coated with artificial saliva, was obtained. Biofilms were divided into four groups and were exposed to acoustic energy delivered by Sonicare for 0 (control group), 5, 15 and 30 seconds. The distance between the end of the bristles and the disk surface was set to 7 mm, to ensure that the biofilm removal was simply due to fluid forces and not to the contact with the bristle tips during the brushing cycle. A colorimetric technique (MTT assay), based on the reduction of a yellow tetrazolium salt to a purple formazan, was used to evaluate the reduction of the adherent biomass after the exposure to the sonic energy., Results: ANOVA results showed that sonic energy exposure significantly reduced the biomass of S. mutans and S. salivarius adherent to the disks, while L. acidophilus and V. alcalescens seemed to remain basically unaffected. In the two streptococcal groups, the increase of the exposure time led to different reduction trends; while S. salivarius exhibited a progressive decrease over time, S. mutans showed a rapid reduction of the adherent biomass after a 15-second exposure to Sonicare.

Purpose: To evaluate the effect of tray-based and trayless tooth whitening systems on surface and subsurface microhardness of human enamel., Methods: Enamel slabs were obtained from recently extracted human third molars. Specimens were randomly assigned to six groups according to tooth whitening treatment (n = 10): 6.0% hydrogen peroxide (HP) (Crest Whitestrips), 6.5% HP (Crest Professional Whitestrips), 7.5% HP (Day White Excel 3), 9.5% HP (Day White Excel 3), 10% carbamide peroxide (Opalescence), and a control group (untreated). Specimens were treated for 14 days following manufacturers' recommended protocols, and were immersed in artificial saliva between treatments. Enamel surface Knoop microhardness (KHN) was measured immediately before treatment, and at days 1, 7, and 14 of treatment. After treatment, subsurface microhardness was measured at depths of 50-500 microm. Data were analyzed for statistical significance using analysis of variance., Results: Differences in microhardness for treated vs. untreated enamel surface were not statistically significant at any time interval. For 6.5% and 9.5% HP, there was a decrease in surface microhardness values during treatment, but at the end of treatment the microhardness values were not statistically different from the baseline values. For the enamel subsurface values, no differences were observed between treated vs. untreated specimens at each depth. Trayless and tray-based tooth whitening treatments do not significantly affect surface or subsurface enamel microhardness.

Purpose: To measure the dentin substrate wear associated with toothbrush use utilizing an in vitro specimen modeled to simulate the prominences of teeth and thus more closely simulate the clinical situation., Materials and Methods: Dentin sections were cast within resin to produce a specimen configuration with three half-round ridges: a central ridge containing dentin (3 x 10 mm) and two similar ridges on each side of the central ridge. The specimens were brushed for the equivalent of the amount of time an individual tooth surface would be brushed in a 2-year period using a machine that simulated typical movement of a toothbrush across the specimen under controlled load and fluid conditions. Brushing was done with either a manual toothbrush (MTB), the Braun Oral-B 3D Excel (PTB1) or the Sonicare Elite (PTB2) and various loads. Dentin substrate loss was measured by profilometry., Results: Using this ridged specimen configuration, the results showed that the MTB and PTB1 had the highest amount of dentin substrate wear in both average depth and average maximum depth measurements. Increased toothbrush force from 90 g to 150 g increased the dentin substrate wear of both PTBs. PTB1 produced approximately 4-5 times greater average wear than PTB2 (P < 0.05).

Purpose: To measure, over time, the release of fluoride from a resin-modified glass-ionomer cement, loaded with different levels of fluoride, then to evaluate the adjacent dentin demineralization inhibition relative to these fluoride levels., Materials and Methods: (Phase I) 25 standardized discs were fabricated from a non-fluoridated resin-based composite (control), resin-modified glass-ionomer cement and resin-modified glass-ionomer cement loaded with sodium fluoride at 1%, 2% and 3% by weight fluoride. Fluoride release was evaluated over 30 days. (Phase II) 50 restorations, from the materials listed in Phase I, were placed as Class V restorations in teeth, the teeth were acid-challenged, then dentin margins adjacent to restoration margins were evaluated for demineralization., Results: As sodium fluoride additions increased, fluoride release increased. Evaluation of demineralization indicated the resin-modified glass-ionomer cement inhibited adjacent demineralization in a direct relationship with sodium fluoride concentration where 3% fluoride exhibited significantly less adjacent demineralization than all other groups; 2% and 1% fluoride exhibited significantly less adjacent demineralization than the non-loaded resin-modified glass-ionomer cement and non-fluoridated resin-based composite control (P< 0.05).

Purpose: To evaluate the role of compomers in secondary caries formation in vitro., Materials and Methods: 36 human teeth with caries-free enamel (coronal) and root surfaces underwent a fluoride-free prophylaxis. Class V cavities were prepared in buccal and lingual coronal and root surfaces. The teeth were divided into two groups with 3 treatment subdivisions [12 teeth per restorative material (6 with coronal restorations and 6 with root surface restorations)]). The preparations were restored with: (1) filled composite (Filtek Z250 with Single Bond), (2) fluoride-releasing compomer [Hytac with Prompt L-Pop (fluoride-releasing water-based adhesive)]; or (3) fluoride-releasing compomer [Dyract AP with Prime & Bond NT (fluoride-releasing acetone-based adhesive)]. 24 cavities (6 teeth with 2 cavities/tooth) were available with each treatment. The teeth were thermocycled (500 cycles at 5-50 degrees C) in synthetic saliva prior to artificial caries formation. After lesion formation, 5 longitudinal sections were taken from each specimen for polarized light evaluation. Mean surface lesion depths and wall lesion frequencies were determined., Results: The Filtek Z250 group had significantly (P < 0.05, ANOVA, DMR) greater mean body of the lesion depths in coronal (205 microm) and root surfaces (221 microm) than either the Hytac (119 microm coronal and 161 microm root surfaces) or the Dyract AP (127 microm coronal and 149 microm root surfaces) groups. Likewise, wall lesion frequency was significantly higher (P < 0.05, ANOVA, DMR) for the Filtek Z250 group (41% coronal and 37% root surfaces) compared with either the Hytac (31% coronal and 25% root surfaces) or Dyract AP (26% coronal and 21% root surfaces) groups. No differences in outer body of the lesion depths or wall lesion frequencies were found between Hytac and Dyract AP for coronal and root surface restorations (P > 0.05, ANOVA, DMR).

Purpose: To determine the fluoride ion release/uptake of two conventional glass-ionomer cements (GICs) manufactured for use with the ART approach (Fuji IX GP, Ketac-Molar), as compared with that of a resin-modified GIC (Fuji II LC)., Materials and Methods: 15 specimens of each material were prepared and placed in vials with artificial saliva and stored at 37 degrees C. The solution was replaced weekly for 6 wks, and the fluoride ions released were measured in ppm each week. After 6 wks, the 15 specimens of each material were divided into three equal groups and placed into three fluoride recharging agents (1.23% APF gel, 1.1% neutral NaF and 0.001% CaF2) for 4 min at 23 degrees C. Fluoride ion measurements of the recharged specimens were carried out at 1 day, 2 days, then weekly for another 6 wks., Results: All freshly-mixed specimens showed the highest fluoride ion release after 1 week, then the release rates dropped quickly to become largely stabilized after 3 wks. After one 4-min exposure to APF gel the initial fluoride ion release increased significantly for all materials. The highest rates were during the first day, but then dropped very quickly to again become largely stabilized after usually 3 wks. Exposure to NaF and CaF2 did not usually result in significantly sustained fluoride ion release by any material. The order of release/uptake for all three agents was Fuji II LC > Fuji IX GP > Ketac-Molar. The mechanism of fluoride ion release after the application of different fluoride recharging agents is not clear. It may occur partly by washout of recharge agents that are retained in the pores and cracks of the restorative materials, for APF gel is viscous and difficult to wash off completely with deionized water; by erosion of surfaces by low pH agents, or by the subsequent release of fluoride ions from within the cement matrix.

Purpose: To evaluate the effect of finishing and polishing techniques on surface roughness of resin-based composites (RBCs)., Materials and Methods: Forty specimens of each material were cured under Mylar strips and immersed in artificial saliva for 1 wk. Samples were tested with a profilometer to obtain baseline average surface roughness (Ra). Specimens of both RBCs were then finished and polished according to four techniques: (1) Sof-Lex disks; (2) Sof-Lex disks followed by Prisma Gloss; (3) Enhance points; (4) Enhance points followed by Prisma Gloss application. New readings of the roughness pattern were carried out and the difference of post-polishing and baseline values were analyzed., Results: ANOVA test (alpha = 0.05) did not show differences between materials (P = 0.9393) nor interaction effects (P = 0.3094), but significant difference among the finishing/polishing techniques were detected (P = 0.0157). Tukey's test showed that the smoothest surface was obtained when the specimens were treated by Sof-Lex followed by Prisma Gloss polishing paste; and the worst results were obtained after using Enhance points alone.