Practical training using BEWE aimed at improving the diagnosis ability of erosive tooth wear for dental students-A randomized trial.

INTRODUCTION: Erosive tooth wear (ETW) has been gaining attention due to its high prevalence. However, ETW clinical diagnosis is difficult and may go unnoticed by many professionals. The present study aimed to develop, implement and evaluate a theoretical-practical training using active methodologies in the development of undergraduate students' skills for the diagnosis of ETW compared to the traditional teaching method. MATERIALS AND METHODS: This randomized controlled study involved two parallel groups: control group (n = 22), with learning based only on theoretical content and test group (n = 24), learning by theoretical-practical activity mediated by monitors/tutors. The theoretical class covered the current concepts of ETW, aetiology, diagnosis, use of the BEWE index, prevention and treatment. The practical training included exercises and discussions based on the diagnosis using BEWE scores of a collection of images and extracted teeth. To evaluate the efficacy of the teaching-learning methods, a theoretical multiple-choice questionnaire and a practical test using images and extracted teeth were applied. The outcome was the number of correct answers. Groups were compared by Mann-Whitney (theoretical knowledge) and T tests (practical ability in diagnosis) (p < .05). RESULTS: There was no significant difference between groups in the theoretical evaluation (p = .866). The test group showed higher ability to diagnose ETW lesions compared to the control group in the practical tests (p = .001). The performance of ETW diagnosis was similar when images were used in comparison to extracted teeth (p = .570). CONCLUSION: The practical activity associated with theoretical classes can be a promising strategy to improve the development of undergraduate students' skills in the diagnosis of ETW.

Brazilian undergraduates' and dentists' knowledge on preventing, diagnosing and managing dentin hypersensitivity: A cross-sectional questionnaire study.

OBJECTIVES: To analyse the knowledge of dental undergraduates and dentists on the prevention, diagnosis and management of dentin hypersensitivity (DH); to compare their knowledge scores; and to understand the related variables using a regression model. METHODS: An original online questionnaire investigated the attitudes, self-reported knowledge ('how much they thought they knew') and real knowledge ('how much they really knew') of 132 students and 338 dentists. Data were analysed descriptively, both knowledge scores were compared using Mann-Whitney and Wilcoxon signed-rank tests and data were subjected to two multiple linear regression analyses considering real knowledge scores as the dependent variable (α < 0.05). RESULTS: The self-reported knowledge on DH was higher than the real knowledge for both students and dentists, but dentists presented the highest scores. Gingival recession and acidic diet were reported as the main predisposing factors for DH by undergraduates and dentists. Students normally managed DH with dietary and hygiene instructions followed by a desensitizing agent application, while dentists managed with occlusal adjustments. The mechanism of glutaraldehyde/HEMA and bioactive fillers on DH is widely unknown by students and dentists. The majority of the questioned individuals cannot differentiate DH from sensitivity of caries or molar-incisor hypomineralization. CONCLUSION: Both students and dentists overestimate their knowledge of DH, revealing deficiencies in prevention, diagnosis and management. Students' knowledge improves towards the end of the Dentistry course, while younger dentists and PhD holders are more knowledgeable. Institutions should implement ongoing DH education for undergraduates and conduct interventions for experienced professionals, especially older ones.

Using digital photographs as a tool to assess the clinical color stability of lithium disilicate veneers: A clinical trial.

STATEMENT OF PROBLEM: Clinical information regarding the color stability of lithium disilicate veneers by using different methods of evaluation is scarce. PURPOSE: This clinical trial aimed to evaluate whether digital photographs are a reliable method of clinically assessing the color stability of lithium disilicate veneers. Standardized digital photographs (ELAB) were compared with the VITA Easyshade spectrophotometer (ES) at baseline and at a 6-month follow-up. MATERIAL AND METHODS: A split-mouth model was used in this randomized clinical trial to assess the performance of ceramic veneers (N=162), which were produced by either the CAD (IPS e.max CAD; n=81) or PRESS technique by heat pressing (IPS e.max PRESS; n=81), including the color dimension assessment. The ELAB evaluation was performed by making digital photographs with polarized light and a white balance (WhiBal) card. These data were transferred to the Adobe Lightroom CC2015 software program in RAW extension. The Digital Color Meter App (Apple) was used to measure L∗, a∗, and b∗ coordinates in this method. The ES color evaluation was performed with a spectrophotometer (Easy Shade) (control group) in the CIELab system. Measurements were performed 1 week after cementation (baseline) and at a 6-month follow-up. Data collected by the ELAB and ES methods were analyzed by a blinded calibrated operator to calculate ΔE by using the Mann-Whitney-Wilcoxon test (α=.05). RESULTS: For all periods, the comparison among ELAB and ES methods (P=.331), CAD×PRESS by ELAB (P=.658), and CAD×PRESS by ES (P=.833) showed no statistically significant differences. CONCLUSIONS: Standardized digital photographs (ELAB) were shown to be a straightforward and available resource for evaluating the color stability of lithium disilicate veneers, manufactured by CAD or PRESS.

Impact of rehabilitation with removable complete or partial dentures on masticatory efficiency and quality of life: A cross-sectional mapping study.

STATEMENT OF PROBLEM: Tooth loss directly affects mastication, cognitive function, and oral health-related quality of life (OHRQoL). Complete dentures (CDs) and removable partial dentures (RPDs) represent a common oral rehabilitation approach. However, studies addressing the impact of removable dentures on replacing missing teeth are lacking. PURPOSE: The purpose of this clinical study was to evaluate whether the OHRQoL, the jaw function limitation (JFL), and the masticatory efficiency of CD and RPD wearers are similar to those of patients with natural teeth and to evaluate whether wearing removable dentures can predict an effect on the OHRQoL, JFL, and masticatory efficiency of their wearers. MATERIAL AND METHODS: The Oral Health Impact Profile (OHIP-14) questionnaire and the JFL scale were used to measure OHRQoL and JFL. Masticatory efficiency was analyzed by using a subjective color-mixing index for the chewing gum bolus and shape index and an objective colorimetric analysis by using a software program ViewGum. Data were analyzed with Kruskal-Wallis and post hoc Dunn tests, followed by multiple linear regression (α=.05). RESULTS: The results from OHIP-14 evidenced that both denture groups presented a low impact on OHRQoL. JFL was higher for all denture wearers. For the subjective color-mixing analysis, the control and RPD groups presented better masticatory efficiency than CD wearers. Colorimetric analysis evidenced better masticatory efficiency for the control group, who differed from the CD and RPD groups. Wearing RPDs was a predictor of impaired JFL and OHRQoL, and the use of CDs was a predictor of impaired JFL and masticatory efficiency. CONCLUSIONS: Despite being rehabilitated, CD and RPD wearers still had impaired OHRQoL, JFL, and masticatory efficiency. Also, the use of these prostheses can predict a negative effect on these 3 variables.

Root caries lesions inhibition and repair using commercial high-fluoride toothpastes with or without tri-calcium phosphate and conventional toothpastes containing or not 1.5% arginine CaCO3: an in situ investigation.

OBJECTIVES: This double-blind, crossover, and in situ study evaluated the effect of commercial high-F toothpastes with or without functionalized ß-tri-calcium phosphate (fTCP) and conventional-F toothpaste containing or not 1.5% arginine-CaCO3 in preventing and repairing root caries-like lesions. METHODS: Twelve volunteers wore palatal appliances containing sound (S) and pre-demineralized (PD) bovine root dentin blocks in 4 phases of 14 days/each. They used F toothpastes, 3×/day: (i) 1,450 µg F/g (conventional-F); (ii) 1,450 µg F/g + 1.5% arginine-CaCO3 (conventional-F + arginine/CaCO3); (iii) 5,000 µg F/g (high-F); and (iv) 5,000 µg F/g (high-F + fTCP). Sucrose solution (20%) was dropped 8×/day on the S blocks. The demineralization in the S blocks and the remineralization in the PD ones were estimated by % of surface hardness difference (%SH-S) and % of SH recovery (%SHR-PD), respectively. Caries lesion area (ΔS) was determined in the blocks. Statistical analyses were performed by one-way ANOVA/Kruskal-Wallis and multiple comparisons tests (p < 0.05). RESULTS: Both high-F toothpastes presented similar effect to prevent early caries lesions and it was higher than conventional-F + arginine/CaCO3. All treatments resulted in significantly lower ΔS values compared with conventional-F toothpaste (p < 0.0001). High-F + fTCP showed non-significantly higher preventive and reversible effect compared to high-F. The effect of conventional-F + arginine/CaCO3 was similar to high-F and lower than high-F + fTCP in preventing and reverting in-deep caries lesions. CONCLUSIONS: Overall, high-F toothpastes seem to be more effective and interesting feasible strategy for both prevention and remineralization actions in root dentin. CLINICAL RELEVANCE: With the trend of increasing dentin root caries, this study brings new evidences about the preventive and repair effect of high-F toothpastes with or without fTCP in root caries and support the use of arginine in toothpastes.

Could applying gels containing chlorhexidine, epigallocatechin-3-gallate, or proanthocyanidin to control tooth wear progression improve bond strength to eroded dentin?

STATEMENT OF PROBLEM: A consensus on whether or how to treat eroded dentin to bond to composite resins is lacking. The role of gels containing chlorhexidine (CHX), epigallocatechin-3-gallate (EGCG), and proanthocyanidin (PAC) in controlling erosive wear progression needs to be evaluated for bonding. PURPOSE: The purpose of this in vitro study was to evaluate the effect of gels containing antiproteolytic agents (CHX or EGCG) or an antiproteolytic and also collagen crosslinking agent (PAC) to control tooth wear progression on the microtensile bond strength (µTBS) of an adhesive system plus a composite resin to simulated eroded dentin. MATERIAL AND METHODS: Superficial occlusal dentin surfaces obtained from sectioned third molars were ground with SiC paper (600-grit; 1 minute; N-normal dentin) or subsequently submitted to an initial erosive challenge (Coca-Cola; 5 minutes). They then received one of the following treatments: application of a placebo (P), a 0.12% CHX digluconate, an EGCG at 400 µM, or a 10% PAC gel (vehicle: hydroxyethylcellulose, propylene glycol, methylparaben, imidazolidinyl urea, and deionized water; active principle: as per the experimental groups when applicable) or no treatment (C: control). Initially demineralized dentin was also submitted to pH cycling (Coca-Cola; 5 minutes, 3×/day, 5 days) to simulate eroded dentin (E). After acid etching all the specimens, adhesive Adper Single Bond 2 was applied, and composite resin (Filtek Z350 XT) was placed. After 24 hours storage in distilled water at 37 °C, the specimens were sectioned into beams, and the µTBS was tested at 0.5 mm/minute. The µTBS values obtained were evaluated considering each tooth as an experimental unit, and 2-way ANOVA and the Tukey post hoc test for multiple comparisons were applied (α=.05). RESULTS: Immediate µTBS values for the eroded dentin were always lower than those for the normal dentin, irrespective of whether any of the gels were applied for wear control. CONCLUSIONS: CHX, EGCG, PAC, and placebo gels, applied after the initial demineralization and before the pH cycling to simulate the eroded dentin, had a similar effect on the µTBS of the adhesive system plus the composite resin to simulated eroded dentin when compared with nonapplication (control).

Sodium Trimetaphosphate as a Novel Strategy for Matrix Metalloproteinase Inhibition and Dentin Remineralization.

The effect of sodium trimetaphosphate (STMP) as an antiproteolytic and remineralizing agent on demineralized dentin was evaluated in vitro. The inhibitory potential of STMP at 0.5, 1.5, 3.5, and 5% against recombinant matrix metalloproteinases (MMPs) MMPs-2 and -9 was assessed by zymography. To investigate its remineralization potential, 40 bovine root specimens were obtained and subjected to a demineralization protocol to produce caries-like dentin lesions. After that, dentin surfaces were divided into 3 areas: (1) mineralized (no treatment); (2) demineralized; and (3) demineralized/treated with STMP and submitted to a pH-cycling associated or not with STMP (1.5, 3.5, or 5% STMP, 10 min of treatment). After that, superficial hardness (SH) and cross-sectional hardness (CSH) were determined. Polarized light microscopy (PLM) was used to qualitatively evaluate mineralization within the caries-like lesions. The zymographic analysis showed that STMP solution is a potent inhibitor of the gelatinolytic activity of MMPs-2 and -9 depending on the dose, since the lowest concentration (0.5%) partially inhibited the enzyme activity, while the higher concentrations completely inhibited enzyme activity. Regarding remineralization effect, only 1.5% STMP solution enhanced both the SH and CSH. PLM showed that the area treated with 1.5% STMP presented similar birefringence as mineralized sound dentin. In conclusion, 1.5% STMP solution is effective as an antiproteolytic agent against MMPs and promotes dentin remineralization.

Radiotherapy alters the composition, structural and mechanical properties of root dentin in vitro.

OBJECTIVES: Post-radiation dental lesions affect mainly the cervical area of the tooth. Until now, there are quite few evidences regarding the effects of radiation exposure on root dentin breakdown. To better understand this effect, we used human root dentin specimens obtained from third molars from similarly aged individuals. MATERIALS AND METHODS: Twenty specimens were analyzed by the surface hardness (SH), energy-dispersive X-ray spectroscopy (EDX), and X-ray diffraction (XRD) to evaluate the baseline properties of their root dentin. Other six human teeth were prepared and analyzed by scanning electron microscopy (SEM). Then the specimens were randomly distributed between two groups (n = 13 per group) and irradiated with a total dose of 55 or 70 Gy in a linear accelerator. The percentage of EDX and surface hardness loss (%SHL) were determined based on measurements before and after irradiation. The specimens were also analyzed after irradiation by SEM and XRD. The Ca/P weight ratio was calculated. RESULTS: Based on SEM analysis, radiation exposure induced dehydration of the dentin. The Ca/P weight ratio decreased (p = 0.0045). The %SHL of specimens irradiated with 70 Gy was higher than that of the 55-Gy group (p < 0.05), although even the lower dose induced root dentin breakdown. CONCLUSIONS: Overall, we can state that radiation exposure changes the composition and structure of human root dentin, which detrimentally affect its hardness. CLINICAL RELEVANCE: The changes reported herein might influence the selection of the dental materials and will bring new knowledge in this field to prevent radiation-related caries in root dentin.

Profile of high-fluoride toothpastes combined or not with functionalized tri-calcium phosphate on root dentin caries control: An in vitro study.

PURPOSE: This in vitro study was conducted in two regimens hypothesizing that high-fluoride (F) toothpaste (5,000 µg F/g) with or without functionalized tri-calcium phosphate (f TCP) would provide additional protection against (1) root caries development and (2) progression. For both regimens, bovine root dentin specimens were used. METHODS: In regimen 1, 60 specimens were subjected daily to alternate immersions between demineralizing and remineralizing solutions for 7 days. The specimens were randomly distributed into four treatment groups (n=15) : non-F toothpaste; Colgate Total 12 (CT) (1,450 µg F/g); Colgate Prevident (CP) (5,000 µg F/g); and Clinpro 5000 (CL) (5,000 µg F/g) associated with (f TCP), and treated with toothpastes/water slurries (1:3 w/w) (5 minutes), twice a day. In regimen 2, the efficacy of the toothpastes to inhibit the progression of the developed lesions was assessed, using the previously described pH-cycling model without additional treatment. The response variables were based on the percentage of surface hardness change (ΔSH), cross-sectional hardness (ΔCSH), mineral content/lesion depth by transversal microradiography (TMR) and the alkali-soluble F uptake. RESULTS: Both high-F toothpastes reduced initial dentin demineralization and increased the F uptake compared to non-F and conventional toothpastes (P< 0.05). In terms of caries lesion progression, all tested toothpastes were able to promote this protection. CLINICAL SIGNIFICANCE: High-F toothpastes, regardless of the presence of f TCP, were more effective than conventional F toothpaste in inhibiting initial root dentin demineralization.

Determining Optimal Fluorescent Agent Concentrations in Dental Adhesive Resins for Imaging the Tooth/Restoration Interface.

Fluorescent dyes like Rhodamine B (RB) have been used to identify the spatial distribution of adhesive restorative materials in the tooth/restoration interface. Potential effects of the addition of RB to dental adhesives were addressed in the past, but no further information is available on how to determine suitable concentrations of RB in these bonding agents for imaging in the confocal laser scanning microscope. This study provides systematical strategies for adding RB to viscous dental adhesive resins, focusing on the determination of the lowest range of dye concentrations necessary to achieve an acceptable image of the dentin/adhesive interface. It was demonstrated that optimized images of the resin distribution in dentin can be produced with 0.1-0.02 mg/mL of RB in the (tested) adhesives. Our approaches took into account aspects related to the dye concentration, photophysical parameters in different host media, specimen composition and morphology to develop a rational use of the fluorescent agent with the resin-based materials. Information gained from this work can help optimize labeling methods using dispersions of low-molecular-weight dyes in different monomer blend systems.

In situ effect of enamel salivary exposure time and type of intraoral appliance before an erosive challenge.

OBJECTIVES: This study tested the effect of enamel salivary exposure time prior to an acid challenge (30 min, 1, 2, or 12 h) and type of intraoral appliance (palatal or mandibular) on initial erosion. METHODS: After initial surface hardness evaluation, enamel blocks (n = 340) were randomly divided into groups and volunteers (n = 20). The control group was not exposed to saliva previously to the erosive challenge. The volunteers wore palatal and mandibular appliances simultaneously. After salivary exposure, the blocks were subjected to acid exposure by immersion in hydrochloric acid (0.01 M, pH 2.3) for 30 s. Then, the enamel surface hardness was evaluated. Data were analyzed using ANOVA, Kruskal-Wallis and Tukey's test (p < 0.05). RESULTS: No difference was observed on percent surface hardness change (% SHC) in the enamel blocks between the types of intraoral appliances. Exposure to saliva for 30 min and 1 h promoted similar enamel resistance to the erosive attack, which was similar to the control group for both appliances. Blocks exposed to saliva for 2 h showed less hardness loss when compared to 30 min. Keeping the blocks in saliva during 12-h overnight resulted in similar percentage of enamel hardness loss compared to 2 h. CONCLUSIONS: A 2-hour in situ exposure to saliva is adequate to promote partial protection against initial erosive lesions, independently of the type of intraoral appliance used. CLINICAL SIGNIFICANCE: This finding will help researchers in the development of erosion studies, which will provide information for dentists to offer a better treatment for erosion.

The abrasive effect of commercial whitening toothpastes on eroded enamel.

PURPOSE: To evaluate the in vitro abrasive effect of commercial whitening toothpastes on eroded bovine enamel samples in respect to erosive tooth wear. METHODS: 72 bovine crowns were embedded, polished and subjected to the baseline profile analysis. The samples were then protected in 2/3 of the enamel surface and were randomly assigned to six groups (n= 12/group): G1: Oral-B 3D White, G2: Close-up Diamond Attraction Power White, G3: Sorriso Xtreme White 4D, G4: Colgate Luminous White, G5: Crest (conventional toothpaste), G6:erosion only (control). All samples were submitted to an erosive pH cycling (4 x 90 seconds in 0.1% citric acid, pH 2.5, per day) and abrasive challenges (2 x 15 seconds, per day) for 7 days. After the first and the last daily cycles, the samples were subjected to abrasive challenges, using a toothbrushing machine, soft toothbrushes and slurry of the tested toothpastes (1.5 N). Between the challenges, the samples were immersed in artificial saliva. The final profile was obtained and overlaid to the baseline profile for the calculation of the erosive tooth wear (µm). The data were subjected to Kruskal-Wallis/Dunn tests (P< 0.05). RESULTS: G1 promoted the highest enamel wear (3.68±1.06 µm), similarly to G3 (3.17± 0.80 µm) and G4 (3.44± 1.29 µm). G3 and G4 performed similarly between them and compared with G5 (2.35± 1.44 µm). G2 (1.51± 0.95 µm) and G6 (0.85± 0.36 µm) showed the lowest enamel wear, which did not differ between them and from G5. Oral-B 3D White showed the highest abrasive potential while Close-up Diamond Attraction Power White showed the lowest abrasive potential on eroded enamel in vitro. CLINICAL SIGNIFICANCE: This study showed that some commercial whitening toothpastes, especially those containing pyrophosphate associated with hydrated silica, enhanced enamel erosive wear.

A 12-month clinical trial examining the effects of a surface sealant on Class I composite resin restorations.

A split-mouth, double-blind trial evaluated the effects of a surface sealant on the clinical performance of Class I composite resin restorations. In 16 patients, 27 pairs of maxillary and mandibular molars or premolars with Class I carious lesions or unsatisfactory restorations were restored with composite resin. For each pair, 1 surface was sealed with surface sealant. Clinical evaluations of marginal integrity, marginal discoloration, anatomical form, and secondary caries were performed by 2 experienced operators using modified US Public Health Service criteria 1-2 weeks and 6 and 12 months after treatment. Data were analyzed with the McNemar test (P < 0.05). After 6 months, only 1 (4%) sealed restoration presented a Bravo rating for marginal integrity. After 12 months, the Bravo ratings for marginal integrity were 2 (7%) for sealed restorations and 1 (4%) for nonsealed restorations. Restorations received a score of Alfa for all other parameters at all time periods. There were no statistically significant differences within or between the sealed and nonsealed groups (P = 1.0). The use of a surface sealant did not improve the clinical performance of posterior composite resin Class I restorations.

Effect of pretreatment with an Er:YAG laser and fluoride on the prevention of dental enamel erosion.

The aim of this study was to evaluate the effect of the Er:YAG laser and its association with fluoride (1.23% acidulate phosphate fluoride gel) on the prevention of enamel erosion. Sixty specimens were obtained from bovine enamel (4 × 4 mm), which were ground flat, polished, and randomly divided into five groups according to the preventive treatments: control-fluoride application; L--Er:YAG laser; L+F--laser + fluoride; F+L--fluoride + laser; L/F--laser/fluoride simultaneously. Half of the enamel surface was covered with nail varnish (control area), and the other half was pretreated with one of the preventive strategies to subsequently be submitted to erosive challenge. When the laser was applied, it was irradiated for 10 s with a focal length of 4 mm and 60 mJ/2 Hz. Fluoride gel was applied for 4 min. Each specimen was individually exposed to regular Coca-Cola® for 1 min, four times/day, for 5 days. Wear analysis was performed with a profilometer, and demineralization was assessed with an optical microscope. Data were analyzed using the Kruskal-Wallis test (wear)/Dunn test and ANOVA/Fisher's exact tests. The group L/F was similar to control group. The other groups showed higher wear, which did not present differences among them. In the demineralization assessment, the groups F+L and L/F showed lower demineralization in relation to the other groups. It can be concluded that none preventive method was able to inhibit dental wear. The treatments L/F and F+L showed lower enamel demineralization.

Role of chlorhexidine in bond strength to artificially eroded dentin over time.

PURPOSE: To assess the long-term effect of a 2% aqueous chlorhexidine (CHX) solution on bond strength to artificially eroded dentin compared to sound dentin. MATERIALS AND METHODS: Flat mid-coronal dentin surfaces of extracted third molars (n = 28) were subjected only to grinding with a 600-grit SiC paper for 1 min (sound dentin S, n = 14) or additionally to erosive pH cycling with a cola-based soft-drink (eroded dentin E, n = 14). After acid etching, rinsing, and air drying, S and E were rehydrated with 1.5 µl of 2% CHX (S2%, n = 7; E2%, n = 7) or of distilled water (control SC, n = 7; EC, n = 7). Composite buildups were incrementally constructed with Filtek Z350 following Adper Single Bond 2 application. Specimens were sectioned into beams, which were subjected to microtensile testing immediately or after 6 or 12 months of aging. Fractured surfaces were observed under a digital microscope (50X magnification). Microtensile bond strength (µTBS) (MPa) was analyzed by three-way ANOVA and Tukey's tests (α = 0.05) and failure mode by the Kruskal-Wallis test (α = 0.05). RESULTS: Compared to sound dentin, eroded dentin was consistently related to lower µTBS. Immediately and after 12-month aging, the effect of CHX was insignificant, but it was significant after 6-month aging, when it conserved the bond strength to both eroded and sound dentin. The percentage of adhesive and mixed failures were equivalent, and significantly more frequent than cohesive failures, whether in dentin or in composite. CONCLUSION: The 2% CHX effect on bond strength conservation to both eroded and sound dentin was not found to be persistent.

Chlorhexidine does not improve but preserves bond strength to eroded dentin.

PURPOSE: To evaluate the effect of aqueous solutions of chlorhexidine digluconate (CHX) in different concentrations on bond strength to eroded dentin up to 6 months, using normal dentin as a control. METHODS: Exposed flat dentin of extracted third molars was only ground with 600-grit SiC paper/1 minute (normal dentin - N), or subsequently eroded by a regular-cola soft-drink (eroded dentin - E). N and E were acid-etched, washed, dried and rehydrated with 1.5 µL, respectively, of distillated water (control - NC / EC); of 0.004% CHX (N0.004% / E0.004%); or of 2% CHX (N2% / E2%). Adper Single Bond 2 was applied in all specimens and resin composite buildups were constructed with Filtek Z350. Specimens were sectioned in beams, which were tested (µTBS) immediately or after 6 months of aging. RESULTS: Microtensile bond strength to eroded dentin was always significantly lower than that to normal dentin. Application of tested CHX solutions did not exert a significant effect immediately; however, after aging, the 2% CHX prevented abrupt bond strength loss both to eroded and normal dentin.

Bleaching technique effect on dentin permeability.

PURPOSE: To evaluate the effect of bleaching techniques on dentin permeability. The hypothesis was that the bleaching agent associated or not to etching and/or energy source would be able to increase dentin permeability (conductance). METHODS: Fifty 1 mm-thick disks of mid-coronal dentin were obtained from human third molars, which were mounted in a filtration chamber, allowing exposure of a standardized area of 0.282 mm2. All specimens were treated with 35% liquid phosphoric acid for 15 seconds to maximize dentin permeability. Then they were randomly allocated to five different conditions: C: placebo gel (negative control); HP: Whiteness HP Maxx (WM)-35% hydrogen peroxide; PA-HP: WM preceded by phosphoric acid etching for 15 seconds. HP-E: WM associated to a light source and PA-HP-E: WM preceded by phosphoric acid etching for 15 seconds and associated to a light source. The bleaching agent was applied for 10 minutes with intermediate agitation at 5 minutes. In the groups associated with a light source, it was activated for 30 seconds every 5 minutes. Afterwards, the permeability (Lp) was measured using the Flodec device. The data were collected and analyzed with one-way ANOVA and Tukey's test (P< 0.05). RESULTS: Mean and standard deviation of Lp were: C = 1.92 (1.04); HP = 1.14 (0.29); PA-HP = 14.40 (8.62); HP-E = 4.18 (5.14); PA-HP-E = 27.32 (13.24). Data revealed that phosphoric acid etching could increase the dentin permeability, while the bleaching agent or light curing alone did not.

Effect of simulated intraoral erosion and/or abrasion effects on etch-and-rinse bonding to enamel.

PURPOSE: To assess the influence of simulated oral erosive/abrasive challenges on the bond strength of an etch-and-rinse two-step bonding system to enamel using an in situ/ex vivo protocol. METHODS: Bovine enamel blocks were prepared and randomly assigned to four groups: CONT - control (no challenge), ABR - 3x/day-1 minute toothbrushing; ERO - 3x/day - 5 minutes extraoral immersion into regular Coca Cola; and ERO+ABR - erosive protocol followed by a 1-minute toothbrushing. Eight blocks were placed into an acrylic palatal appliance for each volunteer (n = 13), who wore the appliance for 5 days. Two blocks were subjected to each of the four challenges. Subsequently, all the blocks were washed with tap water and Adper Single Bond 2/Filtek Z350 were placed. After 24 hours, 1 mm2 beams were obtained from each block to be tested with the microtensile bond strength test (50 N load at 0.5 mm/minute). The data were statistically analyzed by one-way RM-ANOVA and Tukey's tests (alpha = 0.05). RESULTS: No difference was detected among the ABR, ERO, and CONT groups (P > 0.05). ERO+ABR group yielded lower bond strengths than either the ABR and ERO groups (P < 0.0113).

Wear and surface roughness of silorane composites after pH cycling and toothbrushing abrasion.

PURPOSE: To evaluate the effects of toothbrushing abrasion associated with pH cycling on the surface roughness and wear of methacrylate- and silorane-based resin composites. METHODS: Microhybrid methacrylate-based (Filtek Z250), nanofilled methacrylate-based (Filtek Supreme Ultra) and microhybrid silorane-based (Filtek LS) composites were selected for this investigation. For each composite, two groups (n = 10) of rectangular specimens were made. The initial roughness (Ra) of all of the groups was evaluated based on the average of three random tracings with a profilometer, and each specimen had half of its surface protected with two layers of nail varnish to serve as controls. Half of the specimens of each resin were submitted to pH cycling, while the other half were stored in deionized water for 14 days. Subsequently, 100,000 strokes of simulated toothbrushing were performed. Final roughness and wear were measured with the same profilometer, and the values were submitted to ANOVA, Student's t-test and Tukey's test (P < 0.05). RESULTS: The data revealed an increase in surface roughness for Filtek Z250 and Filtek Supreme Ultra after toothbrushing, while Filtek LS showed the opposite behavior. Methacrylate-based composites presented lower wear values [Z250 (4.19 ± 1.73 µm); Supreme Ultra (4.16 ± 0.95 µm)], while the silorane-based composite presented increased surface roughness (11.51 ± 5.69 µm), particularly when submitted to pH cycling (15.31 ± 5.41 µm). Despite the good properties of silorane-based composites, particularly its smooth surface roughness even after pH cycling and toothbrushing abrasion, this composite still presented increased wear, which is an important issue for the development of new resin compositions.

Are S-PRG composites able to resist against erosive and abrasive challenges and protect surrounding enamel in situ?

OBJECTIVES: This study evaluated the resistance of S-PRG (Surface Pre-Reacted Glass-ionomer) composites and other restorative materials against erosive and abrasive challenges and their protective effect on enamel adjacent to the restorations. MATERIALS AND METHODS: Bovine enamel blocks were prepared and randomized into 12 groups, including 6 types of material, each of them subjected to erosion_e or erosion+abrasion_ea: Beautifil II (S-PRG); Beautifil Bulk Restorative (S-PRG); Filtek Z250 XT; Filtek Bulk Fill; EQUIA Forte; Riva Light Cure. Cavities were prepared in the middle of enamel blocks and restored with the materials. Initial profiling measurement was performed on the material and on adjacent enamel (100, 200, 300, 600 and 700 µm from the restoration margin). Palatal intraoral appliances with the restored enamel blocks were used by the volunteers (n = 10). During 5 days appliances were immersed in 2.5 % citric acid for 2 min; 6 × /day (erosion_e). For ea condition, blocks were brushed for 1 min after each acid immersion. Final profile assessment was performed. Data were analysed by two and three way ANOVA followed by Tukey's test (p < 0.05). RESULTS: Material wear: Riva Light Cure showed the highest wear followed by EQUIA Forte and then all resin composites, including the ones with S-PRG (p = 0.000). Enamel wear: there was significant interaction among type of restorative material, wear condition and distance (p = 0.014), enamel around materials showed similar wear (p = 0.983) and the enamel subjected to ea exhibited highest wear (p = 0.000). CONCLUSION: SPRG based composites showed resistance against erosive and abrasive challenges but were not able to protect enamel adjacent to the restorations. CLINICAL SIGNIFICANCE: S-PRG composites exhibit resistance to material wear comparable to resin composites. However, they have shown an inability to effectively protect the adjacent enamel under in situ erosive-abrasive conditions, despite the presence of mineral-loss-preventing ions surrounding materials.