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Objectives: This in vitro study aimed to investigate the toothbrushing wear on both enamel and dentin surfaces of reference and commercially available dentifrices. Methods: Bovine enamel and dentin blocks were initially polished and embedded within a resin composite in square shapes (10×8×6 mm3). Employing toothbrushes equipped with nylon bristles, a toothbrushing machine was utilized, subjecting dentin specimens (n = 36) to 500 brush cycles and enamel samples to 5000 brush cycles (n = 36). Before and after the brushing simulation (2.45-N, 180 strokes per minute), an advanced contact profilometer was employed to measure the abraded depth. The wear rates were analyzed by using One-way ANOVA with two-sided Dunnett's multiple comparisons with a control (water). Results: Significant variations were observed among the tested toothpaste formulations, particularly in dentin wear, where Sident and Prodent showed notably higher values (7.30 μm and 9.67 μm, respectively) compared to the water control group (0.79 μm). Prodent also induced the highest enamel wear (2.64 μm) among the toothpaste formulations, while water, Zendium, and Denttabs exhibited comparatively lower enamel wear values. Statistical analysis using One-way ANOVA with two-sided Dunnett's multiple comparisons against the control (water) confirmed these differences. Significance: Toothbrushing with water causes minimal wear on enamel and dentin tissues, suggesting the predominant effect of three-body wear when using an abrasive medium. Comparing the standard references for dentifrice abrasives, Sident and Sylodent exhibit similar wear rates, making them reliable choices for in-vitro tests. When employed in a similar frequency, the wear rate of commercial toothpaste depends more on its composition than its form (paste or tablets). [ABSTRACT FROM AUTHOR]

The surface of dental materials is exposed to various prophylaxis protocols during routine dental care. However, the impact of these protocols on the functional properties of the material's surface remains unclear. This study investigates the influence of different dental prophylaxis protocols on the surface properties and their effect on the mechanical performance of CAD-CAM restorative materials. Discs (Ø = 15 mm, thickness = 1.2 mm) were fabricated from resin composite (RC, Tetric CAD), leucite-reinforced (LEU, IPS Empress CAD), lithium disilicate (LD, IPS e.max CAD), and zirconia ceramics (ZIR, IPS e.max ZirCAD MT). The materials were subjected to six prophylactic treatments: untreated (CTRL), prophylactic paste fine (PPF), prophylactic paste coarse (PPC), pumice stone (PS), air abrasion with sodium bicarbonate jet (BJ), and ultrasonic scaling (US). Biaxial flexural fatigue tests, along with fractographic, roughness, and topographic analyses, were conducted. No significant changes in fatigue strength were observed for RC, LD, and ZIR under any prophylaxis protocols. However, LEU subjected to BJ treatment exhibited significantly reduced fatigue strength (p = 0.004), with a 22% strength reduction compared to the monotonic test and substantial surface alterations. Surface roughness analyses revealed increased roughness for RC treated with PPF, PPC, and PS compared to CTRL (p < 0.05), while LD exhibited decreased roughness following PPF, PS, and US treatments (p < 0.05). In ZIR, only the BJ protocol increased roughness (p = 0.001). In conclusion, dental prophylaxis protocols do not significantly affect the mechanical strength of RC, LD, and ZIR materials, thus allowing any protocol to be used for these materials. However, for LEU ceramics, the BJ protocol should be avoided due to its effect of reducing fatigue strength and damaging the surface. [ABSTRACT FROM AUTHOR]

This study aimed to evaluate the marginal and internal adaptation of CAD/CAM crowns milled using two different milling protocols (fine or extra-fine) within a 4-axis milling machine. The crowns were fabricated from lithium disilicate ceramic (IPS e.max CAD) and resin composite (Tetric CAD), assessing their fit in various regions. The crowns (N = 40, n = 10) were milled from lithium disilicate and resin composite using a CEREC Primemill unit. Four groups were formed based on the material and milling protocol: EFLD (extra-fine lithium disilicate), FLD (fine lithium disilicate), EFRC (extra-fine resin composite), and FRC (fine resin composite). The crowns were measured using the replica technique, evaluating internal and marginal adaptation in 18 measuring points per specimen. Data were statistically analyzed using ANOVA and Tukey's test. Resin composite crowns demonstrated a significantly better internal fit compared to lithium disilicate (p < 0.001). Marginal and internal measurements for resin composites were consistently smaller across regions compared to lithium disilicate. No significant differences were found between milling protocols except for the axial wall region (p = 0.001), where extra-fine milling resulted in smaller values. Resin composite crowns exhibited superior internal fit compared to lithium disilicate, regardless of milling protocol. Both the fine and extra-fine milling protocols had minimal impact on adaptation, except at the axial wall region, with both protocols promoting adequate results overall. [ABSTRACT FROM AUTHOR]

Background: The present in vitro study aimed to evaluate the fatigue behavior of teeth filled with a calcium silicate-based sealer (Bio-C Sealer, BC) or an epoxy resin-based sealer (AH Plus, AH), in bulk or associated with gutta-percha as main core material. Methods: Seventy-two sound human maxillary anterior teeth were initially selected. Sixty of them, were randomly chosen, and had their root canals prepared using nickel-titanium reciprocating instruments, being again randomly assigned to five experimental groups (n = 12): C+ (control + prepared but not filled); BC-B (BC in bulk); BC-GP (BC+ gutta-percha); AP-B (AH in bulk); AP-GP (AH+ gutta-percha). An additional negative control group (C−) was considered (n = 12), consisting only on sound teeth, without preparation and filling. The specimens were submitted to a survival analysis after the cyclic fatigue test. Results: Sound teeth (C−) presented the best fatigue performance (P < 0.05), being similar only to the AP-GP group (P > 0.05). Despite that, all experimental groups showed similar fatigue behavior (P > 0.05) to C+ (BC-B = BC-GP = AP-B = AP-GP = C+). Based on that, it can be seen that the use of gutta-percha, as a main core material, associated with the AH Plus sealer, reestablished the mechanical fatigue performance of endodontically treated teeth comparable to sound teeth, still consisting on the most promising approach to rehabilitate such scenario. Teeth filled in bulk, had discreetly higher risk of premature failures and inferior fatigue performance. [ABSTRACT FROM AUTHOR]

ABSTRACT Objective Materials and Methods Results Conclusion Clinical Significance The aim of this study was to assess the effect of opaque stain application to the intaglio surface of lithium disilicate glass ceramics on the masking ability of discolored substrates and bond strength to a resin‐based luting agent (depending on etching time); the stain film‐thickness was also assessed.Ceramic specimens were produced with CAD‐CAM blocks of lithium disilicate (IPS e.max CAD). Two opaque stains were tested at ceramic intaglio surface: opaque glassy stain for titanium frameworks (OP‐ti) and low‐fusion glassy stain for ceramic characterization (LFG‐iv). Non‐stained ceramic specimens served as controls. For optical and colorimetric analyses, A2‐shaded ceramics of medium and low‐translucencies were tested, in thicknesses of 1.0‐ and 1.5‐mm (n = 10), with two coupling agents (non‐shaded—glycerin and A2‐shaded try‐in paste). CIEDE2000 formula was used for calculation of translucency parameter (TP00) and color differences (ΔE00). Whiteness index for dentistry (WID) was also reported. ΔE00 were assessed over discolored substrates (tooth‐shaded A2—reference, A4, C3, and C4; coppery metal, silvery metal, white zirconia, and PEEK). Microshear bond strength of stained and non‐stained ceramic specimens to a resin‐based luting agent was evaluated. Film‐thickness of stains was assessed by scanning electron microscopy.The application of opaque stains to the intaglio surface of lithium disilicate ceramics resulted in significant reduction of TP00 (p < 0.001) and WID (p < 0.001) and differences in L*, C*, and ho color coordinates (especially with OP‐ti) (p < 0.001). ΔE00 was significantly reduced in stained ceramic groups in comparison with the control, for all discolored substrates (p < 0.001). Acceptable color matching was obtained with stained ceramic specimens for all discolored substrates, depending on the type of stain, ceramic thickness, ceramic translucency, and coupling agent. The application of stains to the ceramic intaglio surface was not detrimental to bond strength to a resin‐based luting agent, but depended on the time of hydrofluoric acid‐etching (20 s for OP‐ti and 60 s for LFG‐iv) (p < 0.001). Film‐thickness of stains presented mean values <70 μm.The application of opaque stains to the intaglio surface of lithium disilicate glass ceramics was effective to mask severely discolored substrates, presenting adequate bond strength to the luting agent and thin film‐thicknesses.For indirect restorations over severely discolored substrates, the application of opaque stain to the intaglio surface of lithium disilicate glass ceramic ensures acceptable color matching, with adequate bond strength to resin‐based luting agents and clinically acceptable stain film‐thickness. [ABSTRACT FROM AUTHOR]

This study aimed to assess the association of demographic conditions, socioeconomic status, clinical variables, and psychosocial factors with the number of filled teeth in adolescents from public schools. This cohort study comprised 1,134 12-year-old adolescents enrolled in public schools in Santa Maria, Brazil, in 2012. They were followed-up in 2014, where 743 individuals were reassessed (follow-up rate of 65.52%) for the number of filled teeth. Data were collected via dental examinations and structured interviews. Demographic and socioeconomic characteristics were collected from parents or legal guardians. The psychosocial factor comprised students' subjective measurement of happiness (Brazilian version of the Subjective Happiness Scale - SHS). Dental examinations were performed to assess the number of filled teeth through decay, missing, and filled teeth index (DMF-T). Unadjusted and adjusted Poisson regression analyses were performed to assess the association between baseline variables and filled teeth at follow-up. The number of filled teeth in 2012 and 2014 were 193 (17.02%) and 235 (31.63%), respectively. The incidence of filled teeth in 2014 was 42 (5.65%). Adolescents with untreated dental caries, those who visited the dentist in the last 6 months, those that exhibited being happier, and those who had filled teeth at baseline were associated with a higher number of filled teeth at follow-up. We conclude that the number of filled teeth in adolescents was influenced by clinical and psychosocial factors, emphasizing the need to focus on oral health policies in individuals with higher disease burden and those who feel psychologically inferior.