Vanara Florêncio Passos

Clinical Evaluation of a 3% Potassium Oxalate Gel and a GaAlAs Laser for the Treatment of Dentinal Hypersensitivity

OBJECTIVES This study evaluated the immediate and 3 month clinical effects of a low-level gallium-aluminum-arsenide (GaAlAs) laser and a 3% potassium oxalate gel for the treatment of dentinal hypersensitivity. MATERIALS AND METHODS A total of 164 teeth from 30 patients with clinical diagnoses of dentinal hypersensitivity were selected for this randomized, placebo-controlled, double-blind clinical study. The teeth were randomized to three groups: GaAlAs laser, oxalate gel, and placebo gel. The treatment sessions were performed at 7 d intervals for four consecutive weeks. The degree of sensitivity in response to an air blast and tactile stimuli was assessed according to a visual analogue scale at baseline, immediately after the fourth application, and then 3 months after the fourth application. The reductions in dentinal hypersensitivity from baseline at the two follow-up assessments were evaluated as the main outcome. RESULTS In both the active and control groups, there were statistically significant reductions in dentinal hypersensitivity immediately after and 3 months after the treatments, when compared with the hypersensitivity at baseline. No significant differences among the three groups could be detected in their efficacy at either the immediate or 3 month evaluations irrespective of the stimulus. CONCLUSIONS The treatments under study were effective for reducing dentinal hypersensitivity, and longer observational periods could enhance the ability of studies to detect differences between active and placebo groups.

Comparison of methods for quantifying dental wear caused by erosion and abrasion

Various methods have been applied to evaluate the effect of erosion and abrasion. So, the aim of this study was to check the applicability of stylus profilometry (SP), surface hardness (SH) and focus‐variation 3D microscopy (FVM) to the analysis of human enamel and dentin subjected to erosion/abrasion. The samples were randomly allocated into four groups (n = 10): G1‐enamel/erosion, G2‐enamel/erosion plus abrasion, G3‐dentin/erosion, and G4‐dentin/erosion plus abrasion. The specimens were selected by their surface hardness, and they were subjected to cycles of demineralization (Coca‐Cola®‐60 s) and remineralization (artificial saliva‐60 min). For groups G2 and G4, the remineralization procedures were followed by toothbrushing (150 strokes). The above cycle was repeated 3×/day during 5 days. The samples were assessed using SH, SP, and FVM. For each substrate, the groups were compared using an unpaired t‐test, and Pearson correlation coefficients were calculated (α = 5%). For enamel, both profilometry technique showed greater surface loss when the erosion and abrasion processes were combined (P <0.05). The correlation analysis did not reveal any relationships among SH, SP, and FVM to G2 and G4. There were significant correlation coefficients (–0.70 and –0.67) for the comparisons between the FVM and SH methods in enamel and dentin, respectively, in G1 and G3. Choosing the ideal technique for the analysis of erosion depends on the type of dental substrate. SP was not sufficiently sensitive to measure the effects on dentin of erosion or erosion/abrasion. However, SP, FVM and SH were adequate for the detection of tissue loss and demineralization in enamel. Microsc. Res. Tech., 2013.

Two-year clinical evaluation of resinous restorative systems in non-carious cervical lesions

This controlled clinical trial evaluated the 2-year clinical performance of a one-bottle etch-and-rinse adhesive and resin composite system (Excite/Tetric Ceram) compared to a resin-modified glass ionomer cement (RMGIC) (Vitremer/3M) in non-carious cervical lesions. Seventy cervical restorations (35 resin composite - RC- restorations and 35 RMGIC restorations) were placed by a single operator in 30 patients under rubber dam isolation without mechanical preparation. All restorations were evaluated blindly by 2 independent examiners using the modified USPHS criteria at baseline, and after 6, 12 and 24 months. Data were analyzed statistically by Fishers exact and McNemar tests. After 2 years, 59 out of 70 restorations were evaluated. As much as 78.8% retention rate was recorded for RC restorations, while 100% retention was obtained for RMGIC restorations. Fishers exact test showed significant differences (p=0.011) for retention. However, there were no significant differences for marginal integrity, marginal discoloration, anatomic form and secondary caries between the RC and RMGIC restorations. The McNemar test detected significant differences for Excite/TC between baseline and the 2-year recall for retention (p=0.02), marginal integrity (p=0.002) and anatomic form (p=0.04). Therefore, the one-bottle etch-and-rinse bonding system/resin composite showed an inferior clinical performance compared to the RMGIC.

Dentin erosion by whitening mouthwash associated to toothbrushing abrasion: a focus variation 3D scanning microscopy study.

The aim of this study was to determine the erosive potential of hydrogen peroxide (HP) containing mouthwash on dentin assessed by Focus variation three‐dimensional (3D) microscopy. Twenty dentin slabs were selected and randomly allocated into two groups (n = 10): DW—Distilled water (pH = 7.27) and HP—1.5% (pH = 3.78). Each specimen was cyclically demineralized (4 × 60 s/day, 10 days) with HP or DW and brushed 3×/day (200 g, 150 strokes—toothpaste with 1,450 ppmF as NaF). Between the challenges, the specimens were exposed to artificial saliva. Afterward, dentin loss was analyzed using focus variation 3D microscopy, and the data were submitted to unpaired t‐test (α = 0.05). Statistically significant difference was found between the mean wear rate (μm, ±SD) of HP (1.98 ± 0.51) and DW (1.45 ± 0.39). The results suggest that the use of HP‐containing mouthwash associated to brushing may increase the risk of tissue loss and focus variation 3D microscopy may be used as a technique for quantifying dental wear. Microsc. Res. Tech. 76:904–908, 2013.

Effects of diode laser therapy and stannous fluoride on dentin resistance under different erosive acid attacks.

OBJECTIVE This in vitro study aimed to evaluate the effect of a low intensity diode laser (λ=808 nm; 60 J/cm2) associated with stannous fluoride on the inhibition of dentin erosion by assessing percentage of superficial hardness loss (%SHL) and calcium release into the acid solution. MATERIALS AND METHODS Human root dentin slabs were assigned to eight groups (n=10), according to treatments (control, stannous fluoride, diode laser therapy, and the combination of stannous fluoride and laser therapy), and acid challenge (hydrochloridric or citric acid). All slabs were subjected to a previous 2 h acquired pellicle formation; laser and fluoride treatments were performed according to the groups. Subsequently, the slabs were exposed to erosive challenge (0.01 M hydrochloridric acid or citric acid 1% for 60 sec). Additionally, calcium released into the acid solution during erosive challenge was analyzed by photometric test. Data were analyzed by ANOVA followed by Tukeys test (p<0.05). RESULTS Mean values (±SD) for %SHL of treated groups did not present statistically significant differences, regardless of the erosive challenge. However, in relation to released calcium concentration, groups treated with laser presented statistically significant lower calcium loss under hydrochloridric acid challenge (p<0.001). To groups under citric acid attack, only the combination of treatments (p=0.037) was able to show a protective effect on dentin. CONCLUSIONS Under the conditions of this study, 808 nm diode laser with or without stannous fluoride could effectively reduce dentin surface loss under both acid exposures. Only calcium concentration analysis was sensitive enough to measure the effects under the tested conditions.

Effect of green tea as a protective measure against dental erosion in coronary dentine

The aim of this study was to evaluate the effect of green tea as a protective measure on eroded dentin. Disks of human coronary dentin were selected based on surface hardness and randomly assigned to 3 groups (n = 10): DW - distilled water, CHX - 0.2% chlorhexidine digluconate, and GT - green tea. The disks were allowed to acquire pellicle for 2 hours and were then subjected to 3 cycles per day of demineralization (C6H8O7 0.05 M, pH 3.75, 60 s), treatment (DW or CHX or GT, 5 min) and remineralization (artificial saliva, 60 min) over a period of 3 days. Changes in the dentin were determined by loss of surface hardness (%SHL) and mechanical profilometry analysis at the end of each day. Data were analyzed by two-way ANOVA followed by Tukeys test for %SHL and profilometry (p < 0.05). Significant reductions in dentin hardness loss were observed only for the CHX group when compared to the DW group (p < 0.05). However, there was no significant difference between the CHX and GT groups (p > 0.05). A significant difference was observed between DW and GT treatments for wear and roughness measurements (p < 0.05). The green tea extract solution was able to reduce the wear and roughness caused by dentin erosion under the conditions of this study.

The Influence of Dentin Demineralization on Morphological Features of Cavities Using Er:YAG Laser

OBJECTIVE The purpose of this study was to evaluate the influence of erbium-doped: yttrium-aluminum-garnet (Er:YAG) laser parameters and different degrees of demineralization on morphological features, diameter, and depth of prepared cavities. BACKGROUND DATA Minimally invasive dentin caries removal has been recommended. Ablation of deep caries lesions using Er:YAG laser should preserve remaining demineralized dentin; however, the influence of the degree of mineralization of this substrate had not been entirely described. MATERIALS AND METHODS A randomized, factorial design was used to study the effects of two factors. Laser parameter was tested at two levels (250 mJ/4 Hz vs. 200 mJ/2 Hz) and degree of demineralization was tested at four levels (control, two-four-eight cycles). Twelve slabs of human dentin were divided into four groups according to the number of cycles induced by pH-cycling: G1, zero cycles; G2, two cycles, G3, four cycles, and G4, eight cycles. An Er:YAG laser was used at an output energy of 250 mJ/4 Hz and 200 mJ/2 Hz for all groups, for 10 sec at 12 mm distance focus/object. Circumference and depth of the cavities were measured on scanning electron microscopy (SEM) images using image analysis software. The mean values were subjected to two way analysis of variance (ANOVA) and Tukey tests. RESULTS When using 250 mJ/4 Hz, the mean values of circumferential area increased significantly in relation to control (503.54 μm(2)) with increasing demineralization level (eight cycles) (555.45 μm(2)). Regardless of the demineralization level, there was also significant statistical difference in the studied measurements of the cavities when 250 mJ/4 Hz and 200 mJ/2 Hz were used. SEM also showed that laser cavity preparations left no smear layer, and the dentinal tubules were clear. CONCLUSIONS The circumferential area and depth measurements were affected by laser parameter and demineralization level (eight cycles). Energy level output represents a relevant factor for increased circumferential area and depth measurements. High demineralized artificially caries-affected dentin may also imply higher ablation. Appropriated parameter of laser pulse frequency/power density for demineralized dentin should be used for effective less-invasive caries treatment.

Investigation on light-assisted preventive effects on dentin erosion

Abstract Background and objective: Dental erosion is now recognized as an important cause of tooth tissue loss. This in vitro study aimed at evaluating the effect of low intensity diode lasers (λ=660 or 808 nm; 100 J/cm2) and a blue light emitting diode (LED) (λ=430–480 nm; central wavelength=455 nm; 1200 mW/cm2) combined with fluoride application on the inhibition of early dentin erosion. Materials and methods: Human root dentin slabs were randomly assigned to eight groups (n=10), as follows: G1 – control, G2 – fluoride (5 min), G3 – LED (455 nm), G4 – laser (660 nm), G5 – laser (808 nm), G6 – fluoride+LED, G7 – fluoride+laser (660 nm) and G8 – fluoride+laser (808 nm). After being submitted to a 2-h-acquired pellicle formation, the slabs were treated according to the groups (1× per day) and subsequently exposed to cyclic erosive challenges (0.01 m HCl for 60 s, 4× per day), over a period of 3 days. Surface changes were determined by microhardness and profilometry analyses. The temperature was also evaluated during irradiation. Kruskal-Wallis and Student-Newman-Keuls tests were used to compare the percentage of surface microhardness change (%SMHC) and ANOVA to assess tissue wear and temperature rise. Results: For all irradiated groups, temperature changes were below 1.6°C and were not statistically significant different (p>0.05). Treated groups did not present evidence of erosion reduction for wear rates (p=0.27); however, for %SMHC analysis, a statistically significant difference was found between the control and treated groups (p=0.008). Conclusion: All treatments were able to reduce the loss of hardness of dentin submitted to a slight erosive challenge. However, no synergic effect was found when fluoride application was combined with light irradiation. Zusammenfassung Hintergrund und Ziel: Dentalerosion gilt als eine der Hauptursachen von Zahngewebeverlust. Die vorliegende In-vitro-Studie untersucht die Wirkung eines Low-Intensity-Diodenlasers (λ=660 oder 808 nm, 100 J/cm2) und einer blau emittierenden LED (λ=430–480 nm; mittlere Wellenlänge=455 nm; 1200 mW/cm2) in Kombination mit Fluorid-Anwendung auf die Hemmung der frühen Dentinerosion. Materialien und Methoden: Humane Wurzeldentin-Schnitte wurden nach dem Zufallsprinzip acht Versuchsgruppen (n=10) zugeordnet: G1 – Kontrollgruppe, G2 – Fluorid (5 min), G3 – LED (455 nm), G4 – Laser (660 nm), G5 – Laser (808 nm), G6 – Fluorid+LED, G7 – Fluorid+Laser (660 nm) und G8 – Fluorid+Laser (808 nm). Nachdem die Proben zur Pellikelbildung für 2 h einer Speichellösung ausgesetzt wurden, wurden die Schnitte entsprechend ihrer Gruppenzuordnung über einen Zeitraum von 3 Tagen 1× täglich behandelt und anschließend zyklisch einer erosiven Substanz (0,01 m HCl für 60 s, 4× täglich) ausgesetzt. Die Oberflächenveränderungen wurden anhand von Mikrohärtebestimmungen und Profilometrieanalysen evaluiert. Während der Laser-/Lichtbestrahlung wurde außerdem die Temperatur ermittelt. Kruskal-Wallis- und Student-Newman-Keuls-Tests wurden angewendet, um die prozentuale Änderung der Oberflächenmikrohärte (%SMHC) statistisch auszuwerten und eine Varianzanalyse (ANOVA), um den Gewebeverschleiß und die Erwärmung zu beurteilen. Ergebnisse: Für alle lichtexponierten Gruppen lagen die Temperaturänderungen unter 1,6°C und wiesen keine statistisch signifikanten Unterschiede auf (p>0,05). Es konnte keine statistisch signifikante Reduktion der Erosion nachgewiesen werden (p=0,27), jedoch ergab sich für %SMHC ein statistisch signifikanter Unterschied zwischen der Kontroll- und den lichtbehandelten Gruppen (p=0,008). Fazit: Mit allen Behandlungsregimen konnte der Härteverlust von Dentin reduziert werden, was den Widerstand gegen erosive Einflüsse leicht verbessern könnte. Es konnte jedoch kein synergistischer Effekt bei kombinierter Licht/Fluorid-Anwendung festgestellt werden.

Ph-activated nano-amorphous calcium phosphate-based cement to reduce dental enamel demineralization

Abstract Enamel demineralization is destructive, esthetically compromised, and costly complications for orthodontic patients. Nano-sized amorphous calcium phosphate (NACP) has been explored to address this challenge. The 20% NACP-loaded ortho-cement notably exhibited favorable behavior on reducing demineralization of enamel around brackets in a caries model designed to simulate the carious attack. The 20% NACP-loaded ortho-cement markedly promotes higher calcium and phosphate release at a low pH, and the mineral loss was almost two fold lower and carious lesion depth decreased the by 1/3. This novel approach is promising co-adjuvant route for prevention of dental caries dissemination in millions of patients under orthodontic treatment.

Carbohydrate-electrolyte drinks exhibit risks for human enamel surface loss

Objectives The aim of this investigation was to give insights into the impact of carbohydrate-electrolyte drinks on the likely capacity of enamel surface dissolution and the influence of human saliva exposure as a biological protective factor. Materials and Methods The pH, titratable acidity (TA) to pH 7.0, and buffer capacity (β) of common beverages ingested by patients under physical activity were analyzed. Then, we randomly distributed 50 specimens of human enamel into 5 groups. Processed and natural coconut water served as controls for testing three carbohydrate-electrolyte drinks. In all specimens, we measured surface microhardness (Knoop hardness numbers) and enamel loss (profilometry, µm) for baseline and after simulated intake cycling exposure model. We also prepared areas of specimens to be exposed to human saliva overnight prior to the simulated intake cycling exposure. The cycles were performed by alternated immersions in beverages and artificial saliva. ANOVA two-way and Tukey HDS tests were used. Results The range of pH, TA, and β were 2.85 - 4.81, 8.33 - 46.66 mM/L and 3.48 - 10.25 mM/L × pH, respectively. The highest capacity of enamel surface dissolution was found for commercially available sports drinks for all variables. Single time human saliva exposure failed to significantly promote protective effect for the acidic attack of beverages. Conclusions In this study, carbohydrate-electrolyte drinks usually consumed during endurance training may have a greater capacity of dissolution of enamel surface depending on their physicochemical proprieties associated with pH and titratable acidity.