Luciana Fávaro Francisconi-Dos-Rios

Tooth discoloration is a frequent concern among dental patients. While many professionals and patients choose veneers or other invasive solutions, Minimal Intervention Dentistry (MID) recommends non- and microinvasive approaches to preserve tooth structure. Objective To assess Brazilian dentists’ knowledge and practices on tooth discoloration and how education and professional profile may influence them. Methodology A cross-sectional observational study was conducted with 384 volunteer dentists via an online series of questions on causes, diagnosis, treatment (per tissue removal), and professional-patient relationship. Answers were scored (1=correct/affirmative, 0=incorrect/negative). Descriptive and multivariate regression analyses were performed (α=0.05). Results Most respondents were female, aged 20-49, from the Southeast region. Correct answer rates: 69.9% for causes, 69.4% for diagnosis, 48.8% for treatment, 83.6% for professional-patient relationship, 56.4% overall. Graduation from public universities and holding graduate training in Operative or Pediatric Dentistry or Orofacial Harmonization were associated with better outcomes. Conclusion Knowledge of non- and microinvasive approaches to tooth discoloration remains limited. Broader educational efforts are needed, especially among specific groups of professionals who showed lower performance.

Objective: Knowledge about the effects of different phosphoric acids can help clinicians choose the appropriate acid etchant, preserving dental structure without compromising bond strength. This study aimed to analyze the morphology, surface loss, and roughness of different acid etching agents, especially a self-limiting phosphoric acid, at different time intervals. Material and Methods: Bovine enamel specimens were allocated into experimental groups (n = 5). The surfaces were treated with acid etchant (UE: UltraEtch; C37: Condac37; PE37: Power Etching 37%; DGC: Dental Gel Conditioner; SE: Scotchbond Etchant) for 15, 30, 60, 90, and 120 s. Surface loss and roughness were evaluated with an optical profilometer, and morphological analyses was performed by Scanning Electron Microscopy. Data were statistically analyzed (α=0.05). Results: The surface loss increased for all acids over time, except for UE. Up to 60 s, none of the acids promoted different surface loss. For 90 s, UE showed the smallest loss, and SE exhibited the greatest loss; for 120 s, UE had the smallest loss, while DGC and SE had the highest. The roughness increased for all acids over time, including UE, except for 90 s. For 90 s, DGC promoted the highest surface roughness, while UE, PE37, and SE showed the smallest. Compared to the control, all acids showed significant differences in structural loss and roughness. Finally, the type 2 etching pattern predominated. Conclusion: UltraEtch exhibited a self-limiting etching behavior, even though it causes an increase in surface roughness, it does not promote a significantly increasing surface loss over time. KEYWORDS Acid Etching; Enamel; Morphology; Phosphoric Acid; Surface Properties.

Considering that a single passive application of hydrochloric acid (HCl) as a resin infiltration pretreatment can remove between 20 and 45 µm of enamel and cause etching that extends up to 2 mm beyond the white spot lesions (WSLs), it is plausible that its repeated and active applications could result in a greater amount of dental tissue being removed. Objective To evaluate the enamel surface loss and micromorphology after etching with 15% HCl using two application methods (passive-P and active-A) and varying numbers of applications (C-placebo – 120 s; 1x HCl – 120 s; 2x HCl – 120 s + 120 s; 3x HCl – 120 s + 120 s + 120 s). Methodology Bovine incisors with ≤0.3 µm initial curvature were randomized into eight groups (n=12) based on microhardness, followed by WSL simulation. A central window was etched according to experimental conditions, and surface loss was assessed using optical profilometry and micromorphology via scanning electron microscopy (SEM). Two-way ANOVA and Tukey's test were used for surface loss, and the chi-square test evaluated the association of experimental conditions with etching patterns (α=0.05). Results 1xP generated intermediate mean surface loss, positioned between the values observed for passive control (PC) and active control (AC), and those for 2xP and 3xP. Losses from active applications were significantly higher than passive ones and were increased by the number of applications. SEM showed Types II and III etching patterns and Type II was more frequent. There was no association between treatment and etching pattern. Conclusion Multiple and active HCl applications may raise concerns about removal of the remaining tooth structure, challenging the principles of minimal intervention dentistry.

The aim of this study was to assess the effect of a chlorhexidine digluconate solution (CHX) applied as an antiproteolytic agent for controlling erosive tooth wear or as part of the adhesive treatment on long-term bond strength to eroded dentin. Dentin specimens were abraded with a 600-grit silicon carbide (SiC) paper for 1 min (sound dentin - S), subsequently treated with 2% CHX for 1 min (with excess removed, followed by a 6-hour rest), and eroded by exposure to Coca-Cola for 5 min, three times a day, for 5 days (CHX-treated and eroded dentin - CHXE), or only eroded (eroded dentin - E). The specimens were acid-etched (15 s), rinsed (30 s), dried (15 s), and rehydrated with 1.5 μL of distilled water for 1 min, with excess removed (control - S.C/CHXE.C/E.C) or 2% CHX (S.CHX/CHXE.CHX/E.CHX). Adper Single Bond 2 was scrubbed twice on the surface for 15 s each and then light-cured for 10 s, and resin composite cores were built up. Specimens were sectioned into beams and microtensile bond strength was tested (μTBS; 0.5 mm/min) immediately or after 18-month aging. Failure modes were analyzed using a digital microscope. Data (μTBS/MPa) were analyzed by three-way ANOVA, followed by Tukey’s test (α = 0.05). μTBS to E and CHXE, irrespective of the rehydration solution and aging period, were equivalent to each other and lower than that to S. CHX as the rehydration solution reduced immediate and long-term µTBS to S. Aging reduced μTBS. By controlling tooth wear or interface aging, CHX could not influence long-term bonding to eroded dentin.

This study evaluated the color change (ΔE₀₀) and penetration depth (PD) of white spot lesions (WSLs) infiltrated with the resin infiltrant (Icon^®) functionalized with methacrylate epigallocatechin-3-gallate (EGCG). To introduce polymerizable double bonds, EGCG was reacted with methacryloyl chloride (EM). Subsequently, the Icon resin infiltrant (I) was loaded with neat EGCG (IE) or EGCG–methacrylate (IEM) at 2 wt% each. WSLs were created on bovine enamel blocks and treated with I, IE, or IEM. Sound and untreated enamel surfaces were used as controls (C). Infiltrant PD (%) was determined by Confocal Laser Scanning Microscopy (CLSM, n = 12) analysis. For color change (ΔE₀₀) determination (n = 14), ΔL, Δa, and Δb, half of each sample was kept sound as a reference area. The color was determined with a spectrophotometer. Data were statistically evaluated (p = 0.05). Surface morphology was obtained as a qualitative response variable using 3D CLSM. PD (%) did not differ statistically for I, IE, and IEM (p = 0.780). Groups I and IEM showed similar performance on color change (ΔE₀₀) compared to the control group, while IE exhibited intermediate results, with no significant difference observed between the untreated, I, and IEM groups (p < 0.001). IEM promoted the masking of the WSL color without interfering with the PD.

There are many suitable strategies for addressing caries, which is an ongoing worldwide problem. Although white spot lesions (WSLs) can be either remineralized naturally or treated with non- or micro-invasive strategies, their whitish and opaque appearance may persist.

Objectives To evaluate the effect of Nd:YAG laser irradiation as a prior desensitizing strategy on immediate and medium-term microtensile bond strength (µTBS) to simulated hypersensitive dentin. Materials and methods Flat mid-coronal dentin was obtained from third molars and submitted to a 600-grit SiC paper (1 min; N: normal dentin) or subsequently challenged with citric acid (6%, 1 min; H: simulated hypersensitive dentin). Afterwards, dentin was or was not (C: control; HC, NC — each n = 7) irradiated with Nd:YAG laser (L: laser; 1.0 W/10 Hz/100 mJ/4 irradiations of 50-60 s; HL, NL — each n = 7). A 2-step self-etch adhesive (Clearfil SE Bond) was applied and composite (Filtek Z350) buildups were constructed. After 24-h (distilled water/37 °C) storage, specimens were sectioned into beams and tested (µTBS; 0.5 mm/min) immediately or after 6-month aging. Three-way ANOVA and Tukey tests were applied (α = 0.05). Qualitative evaluation of the adhesive interface (n = 1 extra tooth per group) was performed by Confocal Laser Scanning Microscopy. Results Substrate condition (p < 0.001), laser irradiation (p < 0.001), and aging (p = 0.002) influenced the results. Furthermore, there was interaction between substrate and irradiation (p < 0.001). Laser irradiation favored µTBS exclusively to hypersensitive dentin immediately and after aging. µTBS to hypersensitive dentin was higher than that to the normal substrate only when it was laser-irradiated. In any case, immediate µTBS was always higher than that after aging. CLSM revealed longer and more numerous resin tags for simulated hypersensitive dentin, and shorter and fewer resin tags for laser-irradiated dentin. No differences were observed in the hybrid layer itself. Conclusion Nd:YAG laser irradiation prior to restoration favored the µTBS of a self-etch adhesive and resin composite to hypersensitive dentin. Clinical relevance Desensitizing strategies are usually tried before performing restorative treatments in hypersensitive dentin; therefore, they may influence behavior of the adhesive interface established. However, instead of causing concern, Nd:YAG laser irradiation revealed a favorable effect on the aforementioned interface.

Objective: To evaluate knowledge of undergraduates and qualified dentists from a Brazilian Dental School in treating Dentine Hypersensitivity (DH). Methodology: Data obtained from a 22-item questionnaire were analysed and arranged in distribution figures. Results: Of 100 respondents, 66.3% indicated that up to 25% of their patients had DH; 41.7%, that the duration of discomfort was up to eight weeks; 78.4%, that they examined a patient with DH within the last two-four weeks; and 70.4%, that this was done after the patient initiated the conversation on DH. Most of participants responded DH affects patients’ quality of life, and its aetiology was attrition, exposed dentine, occlusal interference, gingival recession or abrasion. The most common ways to diagnose DH were sensitivity history analysis, clinical examination, clinical testing and probing; and conflicting conditions were fractured restoration, bleaching sensitivity, marginal leakage, chipped tooth and periodontal disease. Furthermore, 82.5% and 78.7% of respondents indicated they were confident in diagnosing DH and providing advice to patients, but only 38.8% identified hydrodynamic theory as its underlying mechanism. To evaluate pain from DH they considered self-assessment, dental examination, dietary analysis and thermal assessment; and as recommendations, the use of desensitizing dentifrices, education on toothbrushing, in-office application of desensitizing products, and restorations. Conclusion: There is still confusion concerning the aetiology, the diagnosis and the subsequent management of DH, and both students and qualified dentists need better education.