Role of non-carious cervical lesions multicausality in the behavior of respective restorations.

OBJECTIVES: To evaluate biocorrosion and eccentric occlusal loading interplay in marginal quality of cervical restorations. METHODS: Cervical wedge-shaped cavities were prepared in extracted premolars and restored with a composite. Premolars underwent either an erosive challenge (E: 1% citric acid/10 min), eccentric occlusal loading (EOL: 150 N/2.5 Hz/106 cycles), E before EOL (E + EOL), E intermediate to EOL (EOL/E/EOL), E after EOL (EOL + E), or no E or EOL (C: control). Marginal quality was analyzed based on a series of Optical Coherence Tomography images. Each of the margins was assigned a gap score (0, 1, 2, or 3) and measurement (µm). For each margin, scores data were analyzed with Kruskall Wallis and Dunn tests, and µm data, with Kruskall Wallis. Overall and for each group, the different margins were compared using Wilcoxon signed-rank test, and the correlation between scores and µm, Spearman's correlation coefficient (α = 0.05). RESULTS: E and EOL, even if associated, did not influence enamel marginal quality. EOL/E/EOL impaired dentin/cementum marginal quality only in the case of scores and compared to E. E + EOL, EOL + E or EOL and even C, without differences between each other, did not influence results differently from E or EOL/E/EOL. Margins in dentin/cementum always showed lengthier gaps. Except for C, E and EOL + E cervical margin, there was a strong positive correlation between scores and µm. CONCLUSIONS: Eccentric occlusal loading and/or biocorrosion cannot be assumed as causes of marginal failure of cervical restorations in wedge-shaped cavities. A relevant concern may still be the establishment of adhesive interfaces in dentin/cementum. CLINICAL SIGNIFICANCE: Although non-carious cervical lesions are strongly being recognized multifactorial and their respective restorations not always behave as expected, biocorrosion and eccentric occlusal loading interplay cannot serve as an explanation for marginal gaps they often present.

Effect of Nd:YAG laser irradiation, used as a desensitizing strategy, on bond strength to simulated hypersensitive dentin.

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.

Obliterating potential of active products for dentin hypersensitivity treatment under an erosive challenge.

OBJECTIVES: To compare the effect of 5 desensitizing agents on the hydraulic conductance (Lp) of dentin and to analyze its surface under a Laser Scanning Confocal Microscope (LSCM) before and after an erosive challenge. METHODS: Lp was analyzed in the following sequence: in the presence of smear layer (pMin), after a 15-second acid etching (pMax), after treatment with a desensitizing agent (pTreat) and after a 1-minute erosive challenge (6% citric acid - pEro). Fifty 1.0 ± 0.2 mm-thick dentin disks were prepared from sound human third molars and were randomly distributed into 5 groups (n = 10): FG-Fluoride gel (control), SA-Sensiactive, PR-Sensitive Pro-Relief, NP-Desensibilize Nano-P and EV-Enamel Pro Varnish. Data were analyzed by two-way ANOVA and Tukey tests (α<0.05). Additional specimens were analyzed under a Laser Scanning Confocal Microscope (LSCM) and by Energy Dispersive X-ray Spectroscopy (EDS). RESULTS: All materials reduced the Lp in some extent, except for FG and EV. After the erosive challenge, SA was the only material effectively able to keep the same Lp of the post-treatment phase, while the other products showed lower resistance upon an erosive challenge. Under the LSCM, the SA and NP materials were more effective to obliterate the opened dentin tubules and demonstrated higher resistance upon an erosive challenge. The EDS analysis evidenced levels of Ca, O, P, Si, Na and S. CONCLUSIONS: Product containing potassium oxalate was the most effective in reducing Lp of dentin samples before and after an erosive challenge. Under a LSCM, products containing potassium oxalate or hydroxyapatite crystals seemed to be occluding the dentin tubules after an erosive challenge.

Influence of surface sealant and erosive challenge on the color change of composite resin subjected to artificial staining.

The aim of this study was to evaluate the influence of surface sealant and erosive challenge on the color change of composite resin after artificial staining with coffee. Forty-eight composite specimens (8 × 1 mm) were prepared and divided into 4 groups (n = 12) based on the timing of sealant application (immediate vs delayed) and exposure to acid (erosive challenge vs no challenge). The groups were subjected to the procedures in the following order: 1, sealant application, erosive challenge, color measurement, coffee immersion, and color measurement; 2, sealant application, color measurement, coffee immersion, and color measurement; 3, erosive challenge, color measurement, sealant application, coffee immersion, and color measurement; and 4, color measurement, sealant application, coffee immersion, and color measurement. In groups 1 and 2, surface sealant was applied immediately after preparation of the specimens. In groups 3 and 4, sealant was applied after the first color measurement. Color was measured with a spectrophotometer using the CIE L*a*b* system. The erosive challenge (groups 1 and 3) was carried out in 0.01M hydrochloric acid, 150 mL/cycle, at room temperature (2-minute immersions 4 times a day for 5 days). After all specimens were immersed in coffee for 14 days, new color measurements were performed. For total color change (∆E*), groups 1 (21.01) and 2 (23.10) presented lower values than groups 3 (27.76) and 4 (26.57). For luminosity (∆L*), the opposite occurred (groups: 1, -16.84; 2, -17.72; 3, -22.62; and 4, -21.22). For ∆a* and ∆b*, the only statistically significant difference was the group 1 ∆b* value, which was the lowest among all groups. The opacity remained stable in all groups. The results suggest that resin luminosity decreases and color variation increases when surface sealant is applied after erosive cycling and storage.

Clinical trials sponsored by industry and other private organizations.

The present manuscript discussed some relevant aspects related to private sponsored clinical trials in dentistry. For decades, the academy has been the major responsible for research in Brazil. Distant from the trade sector, academic research has not always provided clear benefits to society. A key aspect of making benefits clearer is the process of scientific knowledge transference to decision-makers, which is, in fact, the ground of evidence-based dentistry. Although private sponsoring of clinical research seems to be part of the research progress of the business rates, investment in Brazil is lower than those observed in other countries. It is particularly important to understand that instead of creating its own rules, dentistry imported the high-quality standards originally designed for pharmaceutical studies. Therefore, it is critical to understand the original rules and how dental items are classified by regulatory agencies. In fact, knowledge about international and local regulation is a basic assumption in industry-sponsored research. Despite globalization, the identification of industry-sponsored studies through open access databases is still very hard and time-demanding. A common concern when conducting industry-sponsored trials is study biases. Fortunately, many relevant organizations, academic and industry groups, have been working seriously against that. Finally, for less experienced researchers, many aspects related to industry-sponsored studies - such as confidentiality, authorship, budget - are deeply discussed until a final version of the trial agreement can be written and signed, protecting all sides. In short, the scenario should be improved, but it already represents a nice opportunity for dental research.

Functional and aesthetic rehabilitation in posterior tooth with bulk-fill resin composite and occlusal matrix.

The restorative procedure in posterior teeth involves clinical steps related to professional skill, especially when using the incremental technique, which may fail in the long term. A recent alternative is bulk-fill resins, which can reduce polymerization shrinkage, decreasing clinical problems such as marginal leakage, secondary caries, and fracture. This scientific study aims to report a clinical case using bulk-fill resin with an occlusal matrix. As determined in the treatment plan, an acrylic resin matrix was produced to establish an improved oral and aesthetic rehabilitation of the right mandibular first molar, which presented a carious lesion with dentin involvement. The occlusal matrix is a simple technique that maintains the original dental anatomy, showing satisfactory results regarding function and aesthetic rehabilitation.

Dental Bleaching, Microabrasion, and Resin Infiltration: Case Report of Minimally Invasive Treatment of Enamel Hypoplasia.

Enamel hypoplasia occurs because of a defect in formation of the organic matrix during the development of tooth enamel. Minimally invasive procedures of the slightly altered enamel contribute to a greater longevity of teeth and prevent them from relapsing into the repetitive restorative cycle. This case history report aimed to show a sequential technique of minimally invasive procedures for esthetic resolution in anterior teeth. Prior to microabrasion, anterior teeth were bleached in office with 37% hydrogen peroxide. Afterwards, hypoplastic spots on the buccal incisal thirds of the maxillary central incisors were treated with two sessions of microabrasion using phosphoric acid and pumice stone and one session using resin infiltrant. Besides a slight remaining white spot on tooth 21, the masking of spots was done with this sequence of treatments, re-establishing color harmony. Spot depth, diagnosis, and the most relevant treatment choice determined the clinical success.

Clinical trials sponsored by industry and other private organizations

Abstract The present manuscript discussed some relevant aspects related to private sponsored clinical trials in dentistry. For decades, the academy has been the major responsible for research in Brazil. Distant from the trade sector, academic research has not always provided clear benefits to society. A key aspect of making benefits clearer is the process of scientific knowledge transference to decision-makers, which is, in fact, the ground of evidence-based dentistry. Although private sponsoring of clinical research seems to be part of the research progress of the business rates, investment in Brazil is lower than those observed in other countries. It is particularly important to understand that instead of creating its own rules, dentistry imported the high-quality standards originally designed for pharmaceutical studies. Therefore, it is critical to understand the original rules and how dental items are classified by regulatory agencies. In fact, knowledge about international and local regulation is a basic assumption in industry-sponsored research. Despite globalization, the identification of industry-sponsored studies through open access databases is still very hard and time-demanding. A common concern when conducting industry-sponsored trials is study biases. Fortunately, many relevant organizations, academic and industry groups, have been working seriously against that. Finally, for less experienced researchers, many aspects related to industry-sponsored studies - such as confidentiality, authorship, budget - are deeply discussed until a final version of the trial agreement can be written and signed, protecting all sides. In short, the scenario should be improved, but it already represents a nice opportunity for dental research.

Composite vs. ionomer vs. mixed restoration of wedge-shaped dental cervical lesions: Marginal quality relative to eccentric occlusal loading.

Dental cervical restorations may be impacted by resultants of occlusal loads that may have already contributed to the development of the lesion and should rely on materials' favorable properties to bear the stresses. The marginal quality of cervical restorations made with materials of different moduli of elasticity in essence, isolated, or in combination, was evaluated relative to eccentric occlusal loading. Cervical wedge-shaped cavities, prepared in extracted premolars, were restored with a composite resin (CR), a restorative ionomer (GIC), or the composite in combination with a lining ionomer (Mixed restoration: M). Half of the teeth in each group were subjected to eccentric occlusal loading (eol; 150 N / 106 cycles / 2.5 Hz; CReol / GICeol / Meol, n = 10), and the others were stored in 37 °C distilled water (Control: c; CRc / GICc / Mc, n = 10). A fluorescein-modified adhesive favored delimitation of formed gaps, which were evaluated by confocal laser scanning microscopy regarding their presence, location related to the cavity walls, and width and depth (µm), at a 5% significance level. From a comprehensive perspective, neither the loading nor the materials were significantly associated with the qualitative response variables or exerted any influence over the quantitative variables. More specifically, the use of the different materials was significantly associated with the frequency of gaps exclusively when loading was applied (Chi-square test, p = 0.029, CR > M > GIC). Though the marginal quality of cervical restorations may not be influenced by eccentric occlusal loading or the use of different materials, even in association in general, the unfavorable aspects of the use of the composite may be relevant, particularly in face of the existence of eccentric occlusal loads.

Effectiveness of whitening mouthwashes on tooth color: an in vitro study.

Products for tooth whitening (or tooth color maintenance) that improve smile esthetics have become increasingly popular due to their easy accessibility and low cost. This in vitro study assessed the effect of whitening mouthwash on bovine tooth color. Forty-eight bovine teeth were divided into 3 immersion groups: SL, artificial saliva (control); CLW, Colgate Luminous White; and OBW, Oral-B 3D White. After prophylaxis with pumice, the initial color was measured using the CIE L*a*b* system. Teeth were immersed in the solutions for 2 minutes, 3 times per day, for 30 days. Changes in color (ΔE*, ΔL*, Δa*, and Δb*) were measured at days 14 and 30. Data were analyzed with 2-way analysis of variance and Tukey test (P < 0.05). At day 30, values of ΔE* had significantly decreased in group SL and increased in group OBW; in addition, at day 30, the ΔE*values in group CLW were significantly greater than those in group SL. The ΔL* values for groups SL and OBW significantly decreased from day 14 to day 30. At day 30, the Δa* and Δb* values were lower in all 3 groups. The results showed that the whitening mouthwashes did not improve color after 14 and 30 days.

Photobiomodulation versus direct restoration in a patient presenting with dentinal hypersensitivity: a 6-month follow-up.

Despite nearly a century of research, the treatment of cervical dentinal hypersensitivity (DH) remains challenging. This case report discusses the indications for different approaches to the treatment of DH in a single patient; the chosen alternatives took into account the different degrees of tooth wear and levels of pain at different sites. A 31-year-old woman reported DH in the maxillary right canine and first premolar and the maxillary left lateral incisor and canine in response to thermal, tactile, and osmotic stimuli. Clinical examination revealed that the teeth on the right side presented noncarious cervical lesions deeper than 1 mm, while the teeth on the left side presented only minimal wear. Therefore, the right canine and premolar were restored with composite resin to create a mechanical barrier against stimuli and reestablish form, function, and esthetics. Prior to restoration, the teeth on the right side were irradiated with a low-power laser (808 nm, 100 mW, 1.1 J/point, 10 seconds), which was applied in a single session at 2 locations on each tooth. In contrast, the left lateral incisor and canine were irradiated in 3 sessions with the low-power laser, which reduces pain levels and depolarizes nerve fibers by means of cell biomodulation, and received no restorations. A visual analog scale (0.0-10.0) was used to record the patient's pain, and it was found that pain levels for the restored teeth decreased from 9.4 initially to 0.0 immediately after restoration, and pain levels for the irradiated teeth decreased from 5.4 initially to 2.0 after 3 sessions. After 6 months of clinical evaluation, both sets of teeth showed scores of 0.0 (no pain). Based on the results presented, it can be concluded that both treatments provided satisfactory outcomes when applied for the appropriate indication.

Bonding efficiency and durability: current possibilities.

Bonding plays a major role in dentistry nowadays. Dental adhesives are used in association with composites to solve many restorative issues. However, the wide variety of bonding agents currently available makes it difficult for clinicians to choose the best alternative in terms of material and technique, especially when different clinical situations are considered. Moreover, although bonding agents allow for a more conservative restorative approach, achieving a durable adhesive interface remains a matter of concern, and this mainly due to degradation of the bonding complex in the challenging oral environment. This review aims to present strategies that are being used or those still in development which may help to prevent degradation. It is fundamental that professionals are aware of these strategies to counteract degradation as much as possible. None of them are efficient to completely solve this problem, but they certainly represent reasonable alternatives to increase the lifetime of adhesive restorations.

Bonding efficiency and durability: current possibilities

Abstract Bonding plays a major role in dentistry nowadays. Dental adhesives are used in association with composites to solve many restorative issues. However, the wide variety of bonding agents currently available makes it difficult for clinicians to choose the best alternative in terms of material and technique, especially when different clinical situations are considered. Moreover, although bonding agents allow for a more conservative restorative approach, achieving a durable adhesive interface remains a matter of concern, and this mainly due to degradation of the bonding complex in the challenging oral environment. This review aims to present strategies that are being used or those still in development which may help to prevent degradation. It is fundamental that professionals are aware of these strategies to counteract degradation as much as possible. None of them are efficient to completely solve this problem, but they certainly represent reasonable alternatives to increase the lifetime of adhesive restorations.

Thermal-induced polymerization shrinkage in silorane versus methacrylate based resin composite / Contração de polimeração induzida termicamenteem resinas compostas a base de silorano e metacrilato

Shrinkage is a limitation of resin composite, compromising the clinical longevity of the restorative procedure. In an attempt to reduce their harmful effects, researchers have studied monomers with lower values of contraction. As a result, low-shrinkage composites were developed. This study evaluated quantitatively the shrinkage as a function of power density increase based on methacrylates, comparing them with silorane based resin, and qualitatively regarding gap formation between the adhesive interface as function of tooth substrate. Resin Filtek P90 and Filtek Z250 were polymerized with the device Blue Star 3 with 200, 400, 600, 800 and 1000 mW/cm2 keeping volume constant in 12 mm3. For qualitative analysis of restorative interface, class V cavity preparations in bovine incisors were restored in (2x2x2 mm3), photoactivated with the same values of irradiance, and analyzed by scanning electron microscopy at the interface of the wall surrounding enamel, dentin and axial. The quantitative results of the polymerization shrinkage were analyzed by two-way ANOVA and Tukey's test (p<0.05), while qualitative data were submitedd to Mann-Whitney's, Kruskal-Wallis' and Miller's tests. The progressive increase in power density directly influenced the polymerization shrinkage of the materials studied, although the silorane based resin demonstrated significantly lower values. The marginal integrity was influenced by the dental substrate and the power density used.

Este estudo avaliou quantitativamente a contração de polimerização em função do aumento dos valores de densidade de potência irradiados em compósitos à base de metacrilatos e silorano, e qualitativamente a interface restauradora em relação à abertura de fendas marginais, em função da variação do tipo de substrato dentário. As resinas Filtek Z250 e Filtek P90 foram fotoativadas com 200, 400, 600, 800 e 1000 mW/cm2, em um volume constante de 12mm3, e os valores de contração foram aferidos por meio da máquina de ensaios universal. Para análise qualitativa da interface restauradora, preparos cavitários classe V de (2x2x2mm3) foram restaurados em incisivos bovinos, fotoativados com os mesmos valores de irradiância, e analisados em microscopia eletrônica de varredura nas interfaces da parede circundante em esmalte, parede circundante em dentina e parede axial. Os resultados quantitativos da contração de polimerização foram analisados pelo teste ANOVA a dois critérios e Tukey (p<0,05) enquanto para os dados qualitativos os testes Mann- Whitney, Kruskal-Wallis e Miller foram empregados. O aumento progressivo da densidade de potência influenciou diretamente na contração de polimerização dos materiais estudados, não obstante a resina composta à base de silorano ter demonstrado valores significativamente menores. A integridade marginal sofreu influência do substrato dentário bem como da densidade de potência utilizada, para as duas resinas estudadas.

Water interaction and bond strength to dentin of dye-labelled adhesive as a function of the addition of rhodamine B.

OBJECTIVE: This study investigated the effect of the fluorescent dye rhodamine B (RB) for interfacial micromorphology analysis of dental composite restorations on water sorption/solubility (WS/WSL) and microtensile bond strength to dentin (µTBS) of a 3-step total etch and a 2-step self-etch adhesive system. MATERIAL AND METHODS: The adhesives Adper Scotchbond Multi-Purpose (MP) and Clearfil SE Bond (SE) were mixed with 0.1 mg/mL of RB. For the WS/WSL tests, cured resin disks (5.0 mm in diameter x 0.8 mm thick) were prepared and assigned into four groups (n=10): MP, MP-RB, SE, and SE-RB. For µTBS assessment, extracted human third molars (n=40) had the flat occlusal dentin prepared and assigned into the same experimental groups (n=10). After the bonding and restoration procedures, specimens were sectioned in rectangular beams, stored in water and tested after seven days or after 12 months. The failure mode of fractured specimens was qualitatively evaluated under optical microscope (x40). Data from WS/WSL and µTBS were assessed by one-way and three-way ANOVA, respectively, and Tukey's test (α=5%). RESULTS: RB increased the WSL of MP and SE. On the other hand, WS of both MP and SE was not affected by the addition of RB. No significance in µTBS between MP and MP-RB for seven days or one year was observed, whereas for SE a decrease in the µTBS means occurred in both storage times. CONCLUSIONS: RB should be incorporated into non-simplified DBSs with caution, as it can interfere with their physical-mechanical properties, leading to a possible misinterpretation of bonded interface.

Water interaction and bond strength to dentin of dye-labelled adhesive as a function of the addition of rhodamine B

ABSTRACT Objective This study investigated the effect of the fluorescent dye rhodamine B (RB) for interfacial micromorphology analysis of dental composite restorations on water sorption/solubility (WS/WSL) and microtensile bond strength to dentin (µTBS) of a 3-step total etch and a 2-step self-etch adhesive system. Material and Methods The adhesives Adper Scotchbond Multi-Purpose (MP) and Clearfil SE Bond (SE) were mixed with 0.1 mg/mL of RB. For the WS/WSL tests, cured resin disks (5.0 mm in diameter x 0.8 mm thick) were prepared and assigned into four groups (n=10): MP, MP-RB, SE, and SE-RB. For µTBS assessment, extracted human third molars (n=40) had the flat occlusal dentin prepared and assigned into the same experimental groups (n=10). After the bonding and restoration procedures, specimens were sectioned in rectangular beams, stored in water and tested after seven days or after 12 months. The failure mode of fractured specimens was qualitatively evaluated under optical microscope (x40). Data from WS/WSL and µTBS were assessed by one-way and three-way ANOVA, respectively, and Tukey’s test (α=5%). Results RB increased the WSL of MP and SE. On the other hand, WS of both MP and SE was not affected by the addition of RB. No significance in µTBS between MP and MP-RB for seven days or one year was observed, whereas for SE a decrease in the µTBS means occurred in both storage times. Conclusions RB should be incorporated into non-simplified DBSs with caution, as it can interfere with their physical-mechanical properties, leading to a possible misinterpretation of bonded interface.

Amazonian delicacy tucupi is as erosive as a cola-based soft drink.

OBJECTIVE: Acidic diets are advocated as main risk factor for tooth erosion, which could be prevented, or at least controlled, if patients were early advised. It is important to identify, hence, if possible dietary constituents regionally consumed on large scale, such as tucupi, a low-pH yellowish-green color and strong flavor delicacy made from the juice of a bitter cassava, may explain its occurrence in specific patient groups. This cross-over in situ/ex vivo study evaluated tucupi's ability to promote erosion of bovine enamel by assessing its percentage of surface microhardness change (%SMHC), taking a cola-based soft drink and human saliva as positive and negative controls. DESIGN: For three 7-days spaced out legs of 7 days each, nine volunteers wore palatal devices with three bovine enamel blocks, which were challenged with one of the following solutions: TUC-tucupi (n=27); COL-cola-based soft drink (n=27); SAL-saliva (n=27). Erosive challenges were performed extra-orally (4×/day) by dropping TUC or COL at room temperature on specimens. After 5min, palatal devices were replaced into the mouth. SAL permanently acted as the negative control while volunteers solely wore the device. One-way ANOVA followed by Tukey's post-hoc tests (α=0.05) were applied. RESULTS: TUC promoted an enamel %SMHC (-21.56±10.08(a)) similar than that promoted by COL (-18.19±12.99(a); p=0.275), which were both significantly higher than that promoted by SAL (-1.86±13.65(b); p<0.0001). CONCLUSIONS: Besides the most worldwide appreciated cola-based soft drink, the greatly consumed Amazonian delicacy tucupi can be considered a potential risk factor for tooth erosion.

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.