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.

Analysis of color stability and degree of conversion of different types of resin composites.

Resin composites containing surface pre-reacted glass (S-PRG) have been introduced to reduce demineralization and improve remineralization of the tooth structure. However, water diffusion within the material is necessary for its action, which can impair its overall physicomechanical properties over time, including color stability. This study aimed to evaluate the color stability and related degree of conversion (DC) of four resin composites. Discs (6 x 4 mm, n = 5/group) of microhybrid (MH), nanofilled (NF), nanohybrid (NH), and S-PRG-based nanohybrid (S-PRG-NH) composites with two opacities (A2/A2E and A2O/A2D) were prepared. Color (CIELab and CIEDE2000) was evaluated with a spectrophotometer after aging in grape juice (2 x 10 min/10mL/7days). The DC was analyzed by using Fourier transform infrared spectroscopy before and after light-curing. Data were statistically analyzed by using two-way analysis of variance and post-hoc least significant difference tests (p<0.05). In the color stability analysis, the interaction between filler type and opacity was significant (CIELab, p = 0.0015; CIEDE2000, p = 0.0026). NH presented the highest color stability, which did not differ from that of MH. The greatest color alteration was observed for S-PRG-NH. S-PRG fillers also influenced DC (p < 0.05). The nanohybrid resin composite presented favorable overall performance, which is likely related to its more stable organic content. Notwithstanding the benefits of using S-PRG-based nanohybrid resins, mostly in aesthetic procedures, professionals should consider the susceptibility of such resins to color alteration, probably due to the water-based bioactive mechanism of action.

Analysis of color stability and degree of conversion of different types of resin composites

Abstract Resin composites containing surface pre-reacted glass (S-PRG) have been introduced to reduce demineralization and improve remineralization of the tooth structure. However, water diffusion within the material is necessary for its action, which can impair its overall physicomechanical properties over time, including color stability. This study aimed to evaluate the color stability and related degree of conversion (DC) of four resin composites. Discs (6 x 4 mm, n = 5/group) of microhybrid (MH), nanofilled (NF), nanohybrid (NH), and S-PRG-based nanohybrid (S-PRG-NH) composites with two opacities (A2/A2E and A2O/A2D) were prepared. Color (CIELab and CIEDE2000) was evaluated with a spectrophotometer after aging in grape juice (2 x 10 min/10mL/7days). The DC was analyzed by using Fourier transform infrared spectroscopy before and after light-curing. Data were statistically analyzed by using two-way analysis of variance and post-hoc least significant difference tests (p<0.05). In the color stability analysis, the interaction between filler type and opacity was significant (CIELab, p = 0.0015; CIEDE2000, p = 0.0026). NH presented the highest color stability, which did not differ from that of MH. The greatest color alteration was observed for S-PRG-NH. S-PRG fillers also influenced DC (p < 0.05). The nanohybrid resin composite presented favorable overall performance, which is likely related to its more stable organic content. Notwithstanding the benefits of using S-PRG-based nanohybrid resins, mostly in aesthetic procedures, professionals should consider the susceptibility of such resins to color alteration, probably due to the water-based bioactive mechanism of action.

Solvation role of dimethyl sulfoxide on the interaction with dentin bonding systems after 30 months.

OBJECTIVES: To determine whether DMSO could serve as an effective pretreatment to improve the mechanical properties and minimize the degradation of the adhesive interface, through the degree of conversion (DC) and bond strength to dentin of different categories of dentin bonding systems (DBSs) after 30 months. METHODS: DMSO (0, 0.5, 1, 2, 5, 10 vol%) were incorporated into four categories of DBSs: Adper Scotchbond Multipurpose (MP), Adper Single Bond 2 (SB), Clearfil SE Bond (CSE) and Adper Scotchbond Universal (SU). DC was evaluated by Fourier transform infrared spectroscopy (FTIR). For microtensile bond strength test (µTBS), 1 % DMSO were applied on dentin as pretreatment before DBSs. For SU, both strategies were tested. Specimens for µTBS were tested after 24 h, 6 and 30 months. DC and µTBS data were subjected to two-way ANOVA and Tukey test (α < 0.05). RESULTS: Incorporating 5 %/10 % DMSO increased the DC of CSE. Controversially, when combined with SU, 2 % and 10 % DMSO jeopardized the DC. Regarding µTBS, 1 % DMSO pre-treatment increased the bond strength for MP, SB, SU-ER and SU-SE. After 30 months, MP, SU-ER and SU-SE showed a decrease compared to baseline but remained higher than the control. CLINICAL SIGNIFICANCE: DMSO pretreatment may be a useful strategy to improve the bond interface over time. Its incorporation seems to favor the non-solvated systems regarding DC while it seems to show long-term benefits for bond strength using 1 % DMSO for MP and SU systems.

Resin-based materials to control human dentin permeability under erosive conditions in vitro: A hydraulic conductance, confocal microscopy and FTIR study.

OBJECTIVES: To characterize the behavior of three different polymeric agents before and after an erosive challenge on dentin permeability, to analyze their degradation in both conditions, and to analyze their degree of conversion (DC). METHODS: The permeability of human dentin disks (1.0 ± 0.2 mm) was measured with smear layer, after its removal, after treatment (LpTreat) with Gluma Desensitizer, PRG Barrier Coat (PBC) or Icon infiltrant (n = 11/group) and after exposure to citric acid (LpEro) (6%, pH 2.1, 1 min). The specimens were analyzed under a Laser Scanning Confocal Microscope (n = 2/group) and the products' DC were calculated. Data were subjected to 2-way repeated measures ANOVA and post-hoc Bonferroni (permeability analysis), to paired t-test (for specimens treated with Icon) and to t-test (DC analysis) (α < 0.05). RESULTS: Icon showed the lowest LpTreat and LpEro values, while PBC and Gluma did not differ from each other under these conditions. Icon and PBC showed LpEro similar to a dentin with smear layer. Under the Laser Scanning Confocal Microscope, more deposits were noticeable on dentin after treating with PBC. Gluma presented the deepest penetration in dentin. The DC of PBC was the highest. SIGNIFICANCE: Icon caused the highest reduction on permeability values, followed by PBC and Gluma. PBC generated more deposits covering dentin and seemed to be more efficient after an erosive challenge. The association of a polymeric resin with inorganic ion-releasing fillers seem to be a great strategy to manage dentin hypersensitivity under erosive conditions.

S-PRG-based toothpastes compared to NaF toothpaste and NaF varnish on dentin permeability in vitro.

OBJECTIVES: To analyze the effect of 5 toothpastes containing different percentages of S-PRG fillers compared to NaF toothpaste and NaF varnish on the dentin hydraulic conductance (Lp). METHODOLOGY: Dentin disks (1.0±0.2 mm thickness) were cut from third molars, and their Lp values were evaluated using Flodec. The specimens were allocated into 7 groups (n=8). The minimum (smear layer) and the maximum (after acid etching) Lp values were recorded. Lp was also assessed after treatment with either a 0wt.%, 1wt.%, 5wt.%, 20wt.%, or 30wt.% S-PRG toothpaste, a NaF toothpaste, or a NaF varnish. Toothpastes were applied by brushing for 15 s, allowing it to settle for 1 min, and rinsing with deionized water. The NaF varnish was applied for 4 min and was removed with a probe. Specimens were exposed to citric acid (6%, pH 2.1, 1 min) and their final Lp was recorded. The pH of all products was recorded (n=3) and specimens from each group were analyzed by Laser Scanning Confocal Microscopy (LSCM). Data were subjected to 2-way repeated measures ANOVA and post-hoc Bonferroni (a=0.05). RESULTS: The highest Lp reduction was noticed for the 5wt.% S-PRG toothpaste, NaF toothpaste, and NaF varnish. However, the toothpastes containing 5wt.%, 20wt.%, and 30wt.% of S-PRG were similar to all toothpastes but differed from the NaF varnish. After erosion, all groups retrieved their maximum Lp values, except for the NaF varnish. The LSCM evidenced deposits on the surface of specimens treated with 5%, 20%, and 30% S-PRG-based toothpastes and NaF toothpaste. Even more deposits were observed for the NaF varnish. After the erosive challenge, the deposits were diminished in all groups. CONCLUSION: Toothpastes containing 5wt.%, 20wt.%, and 30wt.% of S-PRG fillers behaved similarly to a conventional NaF toothpaste, even after an erosive challenge. The NaF varnish promoted better reduction of the Lp, but its effect was also diminished after erosion.

MIH-Affected Teeth: Clinical Challenges from Diagnosis to Restorative Management.

Teeth affected by molar incisor hypomineralization (MIH) present micromorphologic changes and hypersensitivity, which increase the risk of developing caries lesions and affect bonding procedures. Considering that practitioners still misdiagnose teeth affected by MIH, there is an urge for more knowledge about this topic in order to propose a more adequate and conservative treatment. The purpose of this study was to report the clinical challenges regarding the restorative management of a patient with MIH. A 13-year-old girl sought dental treatment, complaining about hypersensitivity in posterior teeth. Under clinical exams, notable enamel alterations mainly affecting posterior teeth (including molars) presented particular characteristics frequently attributed to MIH, and visible stains on maxillary central incisors were present. Because the mineral and organic content of MIH-affected enamel differ from sound enamel, it may imply special care for bonding of a restorative material. Thus, in order to promote a minimally invasive approach, selective removal of carious tissue and restoration with microhybrid composite resin was conducted after application of a universal bonding system used as self-etching strategy. After a 2-year follow-up, the restorations presented good clinical performance and the patient had limited hypersensitivity discomfort, suggesting a promising performance.

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.

S-PRG-based toothpastes compared to NaF toothpaste and NaF varnish on dentin permeability in vitro

Abstract Objectives To analyze the effect of 5 toothpastes containing different percentages of S-PRG fillers compared to NaF toothpaste and NaF varnish on the dentin hydraulic conductance (Lp). Methodology Dentin disks (1.0±0.2 mm thickness) were cut from third molars, and their Lp values were evaluated using Flodec. The specimens were allocated into 7 groups (n=8). The minimum (smear layer) and the maximum (after acid etching) Lp values were recorded. Lp was also assessed after treatment with either a 0wt.%, 1wt.%, 5wt.%, 20wt.%, or 30wt.% S-PRG toothpaste, a NaF toothpaste, or a NaF varnish. Toothpastes were applied by brushing for 15 s, allowing it to settle for 1 min, and rinsing with deionized water. The NaF varnish was applied for 4 min and was removed with a probe. Specimens were exposed to citric acid (6%, pH 2.1, 1 min) and their final Lp was recorded. The pH of all products was recorded (n=3) and specimens from each group were analyzed by Laser Scanning Confocal Microscopy (LSCM). Data were subjected to 2-way repeated measures ANOVA and post-hoc Bonferroni (a=0.05). Results The highest Lp reduction was noticed for the 5wt.% S-PRG toothpaste, NaF toothpaste, and NaF varnish. However, the toothpastes containing 5wt.%, 20wt.%, and 30wt.% of S-PRG were similar to all toothpastes but differed from the NaF varnish. After erosion, all groups retrieved their maximum Lp values, except for the NaF varnish. The LSCM evidenced deposits on the surface of specimens treated with 5%, 20%, and 30% S-PRG-based toothpastes and NaF toothpaste. Even more deposits were observed for the NaF varnish. After the erosive challenge, the deposits were diminished in all groups. Conclusion Toothpastes containing 5wt.%, 20wt.%, and 30wt.% of S-PRG fillers behaved similarly to a conventional NaF toothpaste, even after an erosive challenge. The NaF varnish promoted better reduction of the Lp, but its effect was also diminished after erosion.

Sodium trimetaphosphate combined to calcium as a strategy to improve dentin-bonding interface / Trimetafosfato de sódio associado ao cálcio como uma estratégia para melhorar a interface adesiva da dentina

Objective: The aim of this study was to evaluate the effect of STMP as biomimetic analog of dentin matrix on the dentin bond strength submitted to artificial cariogenic challenge over time. Material and Methods: The total number of teeth used in the experiment was 60 teeth, which were divided into 6 groups (n = 10). Of these total amount, 10 teeth were not submitted to the artificial cariogenic challenge (ACC), serving as control group (Sound Dentin - SD) while the other 50 were submitted to an ACC (7d/37ºC), being treated with treatment solutions according to each group: SD- deionized water/sound dentin, CD- deionized water/ artificial caries dentin, GIII- STMP, GIV- STMP + Ca(OH)2, GV- STMP + NaF, and GVI- NaF. After treatments (24h), the specimens were restored (Adper Single Bond Universal + Filtek Z250), to obtain resin­dentin sticks with a cross sectional area of 0.8mm2, approximately. Two-third of these sticks were stored in artificial saliva (37°C) for analyzes after 6 and 12 months. The 1/3 remains were subjected to µTBS test (baseline). Data were analyzed by two-way ANOVA and Tukey tests (p<0.05). Results: In general, the highest µTBS values were obtained in sound condition (SD), while the artificial caries condition (CD) determined minimum values. Groups treated with NaF (with or without STMP- GV and GVI) were not able to improve adhesion over time. Only the use of STMP + Ca(OH)2(GIV) improved the µTBS compared to the others caries-challenged dentin after 1 year. The adhesive failure pattern was predominant in all time. Conclusion: The use of the STMP associated with Ca(OH)2 seems to be a viable therapeutic strategy conciliating the biomimetizing capacity to the adhesive process satisfactorily even its performance is not superior to initial condition (AU)

Objetivo: O objetivo deste estudo foi avaliar o efeito do STMP como análogo biomimético da matriz dentinária na resistência de união à dentina submetida a desafio cariogênico artificial ao longo do tempo. Material e Métodos:foram utilizados um total de 60 dentes neste experimento, os quais foram divididos em 6 grupos (n = 10). Desse total, 10 dentes não foram submetidos ao desafio cariogênico artificial (DCA), servindo como grupo controle (Dentina Hígida - DH) enquanto os outros 50 foram submetidos ao DCA (7d / 37ºC), sendo tratados com soluções de tratamento específicas para cada grupo: DH- água deionizada / dentina hígida, DC- água deionizada / dentina submetida ao DCA, GIII- STMP, GIV- STMP + Ca(OH)2, GV- STMP + NaF e GVI- NaF. Após os tratamentos (24h), os corpos-de-prova foram restaurados (Adper Single Bond Universal + Filtek Z250), para obtenção de palitos de resina-dentina com área transversal de aproximadamente 0,8mm2. Dois terços desses palitos foram armazenados em saliva artificial (37°C) para análises após 6 e 12 meses. Os outros 1/3 foram submetidos ao teste µTBS (baseline). Os dados foram analisados por ANOVA a dois fatores e testes de Tukey (p <0,05). Resultados:Em geral, os maiores valores de µTBS foram obtidos em condição hígidas (DH), enquanto a condição subtmetidas ao DCA determinou os menores valores. Os grupos tratados com NaF (com ou sem STMP associado -GV e GVI) não foram capazes de melhorar a resistência de união, ao longo do tempo. Somente o uso de STMP + Ca (OH)2(GIV) melhorou o µTBS em comparação com as outras condições desafiadas por cárie após 1 ano. O padrão de falha adesiva foi predominante em todos os tempos. Conclusão: O uso do STMP associado ao Ca (OH)2 parece ser uma estratégia terapêutica viável conciliando a capacidade biomimetizante ao processo adesivo de forma satisfatória mesmo que seu desempenho não seja superior à condição inicial.(AU)

MDP-based universal adhesive system irradiated with Er,CR:YSGG: Analysis of its performance up to 6 months.

This study aimed to analyze the interaction of a MDP-based universal dentin bonding system (DBS) with Er, Cr: YSGG laser irradiation, measuring the microtensile bond strength to dentin over a six-month period. The experimental design involved three factors: DBS (Adper Scotchbond Universal; Clearfil SE Bond, Adper Scotchbond Multipurpose and Adper Single Bond 2), laser (Control and Er, Cr: YSGG), and time (initial- 7 days and 6 months). Eighty dentin samples from molars were prepared (n=10) with laser irradiation after primer and DBS application. After 7 days, were subjected to micro tensile bond strength test. The data were analyzed by three-way ANOVA and Tukey tests (p<0.05). Both DBS and laser significantly affected the bonding performance and their interaction was statistically significant (p=0.0194). The self-etching mode of the MDP-based universal DBS maintained the bond strength on dentin irradiated with ER, Cr: YSGG after 6 months, while bonding with all other DBS deteriorated.

Performance of MDP-based system in eroded and carious dentin associated with proteolytic inhibitors: 18-Month exploratory study.

The aim of this study was to explore the impact of the interaction between an MDP-based universal adhesive system in etch-and-rinse mode and two proteolytic inhibitors on the longevity of restorations bonded to artificially-affected-dentin substrates. 90 sound human third molars were randomly distributed into three groups according to the substrate: N-no challenges-control (stored in artificial saliva), ACD-artificial caries dentin (6 h DE + 18 h-RE/5 days + 48 h RE) and ERO-artificial erosion dentin (3 × 5 min/5 days with orange juice). They were further redistributed according to dentin pretreatment: W- water (control), CHX-2% digluconate chlorhexidine and E64- 5 µM E64-Trans-Epoxysuccinyl-L-Leucylamido-(4-guanidino) butane, which resulted in the following 9 groups (n = 10): N-W, N-CHX, N-E64, ACD-W, ACD-CHX, ACD-E64, ERO-W, ERO-CHX and ERO-E64. All specimens were restored with Adper Single Bond Universal (Etch-and-rinse mode)/Filtek Z250. Sticks (0.64 mm2) were obtained and subjected to microtensile test (µTBS) in a universal testing machine at 0.5 mm/min for 7-days, 6 and 18-month analyses. Failure modes were classified using optical microscopy (40X). Data were statistically analyzed by three-way ANOVA and Tukey tests (p < 0.05). All individual factors (p < 0.0001) and interaction between factors were statistically significant (substrate X pretreatment (p = 0.00093); substrate X time (p = 0.01035) and pretreatment X time (p = 0.0035). Caries-affected substrate was the most compromised one, disregarding the pretreatment. CHX was mostly affected compared with E64 up to 18 months, possibly due to its calcium-dependent mechanism.

Profile of a 10-MDP-based universal adhesive system associated with chlorhexidine: Dentin bond strength and in situ zymography performance.

The incorporation of functional monomers and proteolytic inhibitors into adhesive systems have shown to be promising strategies to improve the longevity of adhesive restorations. The aim of this study was to evaluate the long-term bonding performance and anti-gelatinolytic effect of a 10-MDP-based universal adhesive system applied in combination with 2% chlorhexidine digluconate (CHX). For that, this study assessed the resin-dentin bond strength and the in situ gelatinolytic activity profile at the adhesive interface at initial and after 6 month of storage. One hundred and two sound human third molars were prepared and randomly divided into 3 groups according to the adhesive strategy: SB (two-step etch-and-rinse adhesive, Adper Single Bond 2, 10-MDP-free control group); SU-ER (Adper Single Bond Universal, 10-MDP containing universal adhesive applied on etch-and-rinse mode); and SU-SE (SU applied on self-etching mode). The groups were subdivided into two according to the dentin pretreatment: W - water or CHX- 2% chlorhexidine digluconate aqueous solution (SB-W; SB-CHX; SU-ER-W; SU-ER-CHX; SU-SE-W; SU-SE-CHX) and subsequently restored according to the manufacturer's instructions. Bond strength (n = 12) was assessed by a microtensile test (µTBS) (500N/0.5 mm/min) after 24h or after 6 months of storage. In situ zymography was performed to evaluate anti-gelatinolytic activity (n = 5). Resin-dentin samples were incubated with fluorescein-conjugated gelatin for 24 h at 37 °C and analyzed by confocal laser scanning microscopy. Fluorescence indicating gelatinolytic activity at hybrid layer zone and adjacencies was quantified using Image J. Data was analyzed by three-way ANOVA and Tukey post-hoc tests (p < 0.05). Results: SU-SE showed the highest bond strength values, while similar results were observed for SU-ER and SB. No statistical significant differences were observed between pretreatment (CHX vs. W) or storage time (initial vs. 6 months of aging). For in situ zymography, fluorescence was detected in all groups and CHX pre-treatment was able to inhibit the gelatinolytic activity in all conditions. The 10-MDP-based universal adhesive system in self-etching mode was the strategy that showed the best bonding performance irrespective of its combination with chlorhexidine. Pre-treatment with CHX did not impair the bond strength when used in combination with 10-MDP and it may promote collagen stability overtime.

Influence of Modulated Photo-Activation on Shrinkage Stress and Degree of Conversion of Bulk-Fill Composites.

This study aimed to evaluate the polymerization properties of bulk-fill materials (low and high-viscosity) by using high-intensity continuous light and intermittent photo-activation in terms of polymerization shrinkage stress and degree of conversion (DC). The following Bulk-fill and Conventional nanofilled resin composites were evaluated: Filtek Z350XT Flow (3M/ESPE), SureFil SDR Flow (Dentsply), Filtek Bulk Fill Flow (3M/ESPE), Filtek Z350XT (3M/ESPE) and Filtek Bulk Fill Posterior (3M/ESPE). A LED device (DB 685, Dabi Atlante) was used for both protocols: continuous uniform and intermittent photo-activation (light-on and light-off cycles) with identical radiant exposure (14 J/cm2). The polymerization shrinkage stress (n=6) was evaluated by inserting a single increment of 12 mm3 between two stainless steel plates (6×2 mm) adapted to a Universal Testing Machine (UTM), at different times. Measurements were recorded after photo-activation. The degree of conversion was evaluated by Fourier transformed infrared spectroscope (FTIR) with an attenuated total reflectance (ATR) accessory (n=5). Data were analyzed by three-way ANOVA and Tukey's HSD (α=0.05) tests. Bulk Fill Posterior presented higher shrinkage stress values when photo-activated with the intermittent technique (p<0.05). The intermittent photo-activation increased the degree of conversion for the low-viscosity bulk-fills (p<0.05). Therefore, the use of modulated photo-activation (intermittent) must be indicated with caution since its use can influence the shrinkage stress and degree of conversion of composites, which varies according to the resin formulations.

Influence of modulated photo-activation on shrinkage stress and degree of conversion of bulk-fill composites

Abstract This study aimed to evaluate the polymerization properties of bulk-fill materials (low and high-viscosity) by using high-intensity continuous light and intermittent photo-activation in terms of polymerization shrinkage stress and degree of conversion (DC). The following Bulk-fill and Conventional nanofilled resin composites were evaluated: Filtek Z350XT Flow (3M/ESPE), SureFil SDR Flow (Dentsply), Filtek Bulk Fill Flow (3M/ESPE), Filtek Z350XT (3M/ESPE) and Filtek Bulk Fill Posterior (3M/ESPE). A LED device (DB 685, Dabi Atlante) was used for both protocols: continuous uniform and intermittent photo-activation (light-on and light-off cycles) with identical radiant exposure (14 J/cm2). The polymerization shrinkage stress (n=6) was evaluated by inserting a single increment of 12 mm3 between two stainless steel plates (6×2 mm) adapted to a Universal Testing Machine (UTM), at different times. Measurements were recorded after photo-activation. The degree of conversion was evaluated by Fourier transformed infrared spectroscope (FTIR) with an attenuated total reflectance (ATR) accessory (n=5). Data were analyzed by three-way ANOVA and Tukey's HSD (α=0.05) tests. Bulk Fill Posterior presented higher shrinkage stress values when photo-activated with the intermittent technique (p<0.05). The intermittent photo-activation increased the degree of conversion for the low-viscosity bulk-fills (p<0.05). Therefore, the use of modulated photo-activation (intermittent) must be indicated with caution since its use can influence the shrinkage stress and degree of conversion of composites, which varies according to the resin formulations.

Resumo O presente estudo teve como objetivo avaliar as propriedades de polimerização de materiais bulk-fill (baixa e alta viscosidade) utilizando luz contínua de alta intensidade e fotoativação intermitente em relação ao estresse de contração de polimerização e grau de conversão (DC). As seguintes resinas compostas Bulk-fill e nanohíbridas convencionais foram avaliadas: Filtek Z350XT Flow (3M/ESPE), SureFil SDR Flow (Dentsply), Filtek Bulk Fill Flow (3M/ESPE), Filtek Z350XT (3M/ESPE) e Filtek Bulk Fill Posterior (3M/ESPE). Um dispositivo de LED (DB 685, Dabi Atlante) foi utilizado nos dois protocolos: fotoativação contínua e intermitente contínua (ciclos de liga e desliga) com exposição idêntica (14 J/cm2). A tensão de contração de polimerização (n=6) foi avaliada através da inserção de um incremento único de 12 mm3 entre duas placas de aço inoxidável (6×2 mm) adaptadas a uma Máquina de Ensaio Universal (UTM), em tempos diferentes. As medições foram registradas após a fotoativação. O grau de conversão foi avaliado por FTIR-ATR (n=5). Os dados foram analisados ​​pelos testes ANOVA a três fatores e teste de Tukey (α=0,05). A resina Bulk Fill Posterior apresentou maiores valores de tensão de contração quando fotoativadas com a técnica intermitente (p<0,05). A fotoativação intermitente aumentou o grau de conversão nas resinas bulk-fill de baixa viscosidade (p<0,05). Portanto, o uso de fotoativação modulada (intermitente) deve ser indicado com cautela, uma vez que seu uso pode influenciar a tensão de contração e o grau de conversão dos compósitos, o que varia de acordo com as formulações da resina.

Effect of diode laser irradiation on the bond strength of polymerized non-simplified adhesive systems after 12 months of water storage.

OBJECTIVES: The aim of this in vitro study was to evaluate the bonding strength of non-simplified dentin bonding systems (DBS) to dentin irradiated with a diode laser (970 nm) immediately and after 12 months of water storage following either primer or bond application. MATERIAL AND METHODS: The experimental design included three different factors: DBS type [AdperTM Scotchbond Multipurpose (MP) and Clearfil™ SE Bond (CSE)], irradiation [without irradiation - control (C), irradiation after primer application (AP), and irradiation after bond application (AB)], and time [initial (I) and after 12 months of water storage (12 m)]. Sixty sound human third molars (n = 10) were obtained, and their flat occlusal dentin areas were prepared and standardized. Laser irradiation was performed in the contact mode perpendicular to the dental surface over an automatically selected scanning area at a pulse energy of 0.8 W, frequency of 10 Hz, and energy density of 66.67 J/cm2. After 7 days of treatment, the specimens were cut, and half of them were subjected to microtensile testing (500 N/0.05 mm/min), whereas the remaining sticks were examined after 12 months of water storage. The obtained data were analyzed by three-way analysis of variance (ANOVA) followed by a Tukey test (p<0.05). The observed fracture modes were investigated using a portable digital microscope with a magnification of 40x. RESULTS: Among the utilized DBS, MP generally exhibited higher bond strengths, but did not always differ from CSE under similar conditions. The irradiation factor was statistically significant only for the MP/AB groups. After 12 months of storage, all groups demonstrated a significant reduction in the bond strength, whereas the results of fracture analysis showed a predominance of the adhesive type. CONCLUSIONS: The laser treatment of non-simplified DBS was not able to stabilize their bonding characteristics after 12 months.

Clinical performance of the composite resin veneers: the minimally invasive approach / Desempenho clínico de facetas de resina composta: uma abordagem minimamente invasiva / Desempeño clínico de las carillas de resina compuesta: un enfoque mínimamente invasivo

Minimally invasive approach lead composite resin veneers restorations as a conservative and alternative treatment option, with the aim to improve the aesthetics anterior dentition. Clinically, this treatment reducing the clinical time and has a lower cost than indirect technique. In addition, new resin composite was developed to support the clinician to make more natural restorations. The present case report aim to evaluated the clinical performance of direct composite veneer technique was restored with 100% supra-nano spherical filler composite. A 39-year-old female, searched for restorative treatment of anterior teeth, which were unaesthetically altered. In the clinical examination, it was observed color alterations in maxillary left and right incisors and canines due to use of medicines, and bruxism. The treatment plan included an in-office dental bleaching, removal of inadequate anterior restorations and confection of composite veneers restorations. The dental bleaching was performed with hydrogen peroxide 35% activated by LED/laser in two sessions. Those restorations were performed using supra-nano spherical resin-based composite, color A1 for dentin and enamel, with direct composite laminate veneer technique. After six-month follow-up, the restorations presented good clinical aspect, absence of biofilm accumulation and abrasive wear. Therefore, direct veneer restorations may be alternative treatment for anterior teeth esthetic problems, suggesting a promising performance of these new composites(AU)

A abordagem minimamente invasiva torna as facetas de resina composta conservadoras e opção de tratamento alternativo para melhorar a estética da dentição anterior. Clinicamente, esse tratamento reduz o tempo operatório e tem um custo menor que a técnica indireta. Além disso, uma nova resina composta foi desenvolvida para ajudar o clínico a fazer restaurações mais naturais. O presente relato de caso tem como objetivo avaliar o desempenho clínico da técnica direta de faceta de resina composta de preenchimento 100% supra-nano-esférico. Paciente de 39 anos, sexo feminino procurou o tratamento restaurador dos dentes anteriores, que foram alterados inesteticamente. No exame clínico foram observadas alterações de cor nos incisivos superiores, esquerdo e direito, e caninos devido ao uso de medicamentos e bruxismo. O plano de tratamento incluiu clareamento dentário em consultório, remoção de restaurações anteriores inadequadas e confecção de facetas de resina composta. O clareamento dental foi realizado com peróxido de hidrogênio a 35% ativado por LED / laser em duas sessões. Essas restaurações foram realizadas utilizando resina composta supra-nano-esférica, cor A1 para dentina e esmalte, com técnica direta de laminado composto. Após seis meses de acompanhamento as restaurações apresentaram bom aspecto clínico, ausência de acúmulo de biofilme e desgaste abrasivo. Portanto, facetas diretas de resina composta podem ser um tratamento alternativo para problemas estéticos de dentes anteriores, sugerindo um desempenho promissor desses novos compósitos(AU)

El abordaje mínimamente invasivo hace que las facetas de resina compuesta conservadoras y opción de tratamiento alternativo para mejorar la dentición anterior estética. Clínicamente, este tratamiento reduce el tiempo clínico y tiene un costo menor que la técnica indirecta. Además, un nuevo compuesto de resina fue desarrollado para ayudar al clínico a hacer restauraciones más naturales. El presente relato de caso tiene como objetivo evaluar el desempeño clínico de la técnica directa de faceta de resina compuesta de relleno 100% supra-nano-esférico. Paciente de 39 años, sexo femenino buscó el tratamiento restaurador de los dientes anteriores, que fueron alterados intemporal. En el examen clínico se observaron alteraciones de color en los incisivos superiores, izquierdo y derecho, y caninos debido al uso de medicamentos y bruxismo. El plan de tratamiento incluyó blanqueamiento dental en consultorio, remoción de restauraciones anteriores inadecuadas y confección de facetas de resina compuesta. El blanqueamiento dental fue realizado con peróxido de hidrógeno al 35% activado por LED / láser en dos sesiones. Estas restauraciones se realizaron utilizando resina compuesta supra-nano esférica, color A1 para dentina y esmalte, con técnica directa de laminado compuesto. Después de seis meses de seguimiento las restauraciones presentaron buen aspecto clínico, ausencia de acumulación de placa dental y desgaste abrasivo. Por lo tanto, las facetas directas de resina compuesta pueden ser un tratamiento alternativo para problemas estéticos de dientes anteriores, sugiriendo un desempeño prometedor de estos nuevos compuestos(AU)

Understanding the interaction of resin composite with light for predictable aesthetic results in anterior teeth: A case report / Compreensão da interação das resinas compostas com a luz para resultados estéticos previsíveis em dentes anteriores: Relato de caso

This case report illustrates a conservative technique for reintervention on anterior composite restorations in a young patient with composite veneers. The treatment incorporated the use of photos and digital planning to establish a harmonious smile design. In order to conserve the dental tissues, existing resin composites restorations in maxillary anterior teeth were carefully removed to minimize enamel reduction, followed by a study of color and shade of teeth considering factors such as hue, chroma, luminosity, opacity, translucency and light effects. Eight direct veneers were built up with resin composite taking the optical properties of the material into account and their influence on the thickness of the layers that create specific light effects when superimposed on each other. To obtain excellent results with a predictable working protocol, nanohybrid composite systems facilitate good aesthetics, avoiding more invasive treatment in an economic manner.(AU)

O presente relato de caso ilustra uma técnica conservadora para a re-intervenção em restaurações diretas de resina composta em pacientes jovens. O tratamento consistiu em fotos e planejamento digital para obtenção de um desenho digital do sorriso individual e harmonioso. De acordo com os princípios de máxima conservação da estrutura dentária, as restaurações existentes nos dentes superiores anteriores foram criteriosamente removidas para minimizar a redução do esmalte, seguido do estudo de cor e sombra dos dentes considerando fatores como matiz, croma, valor, opacidade, translucidez e efeitos de luz. Oito facetas diretas foram realizadas em resina composta considerando as propriedades ópticas do material e a influência destas na espessura das camadas de resina para criar efeitos de luz singulares quando sobrepostas. Para a execução de uma odontologia estética e consciente, em associação a um protocolo de trabalho previsível, os sistemas de resinas compostas nanohibridas possibilitam resultados estéticos satisfatórios, evitando tratamentos mais invasivos de maneira economicamente viável.(AU)

Does laser diode irradiation improve the degree of conversion of simplified dentin bonding systems?

OBJECTIVE: This study aimed to investigate the effect of laser diode irradiation on the degree of conversion (DC), water sorption (WS), and water solubility (WSB) of these bonding systems in an attempt to improve their physico-mechanical resistance. MATERIAL AND METHODS: Two bonding agents were tested: a two-step total-etch system [Adper™ Single Bond 2, 3M ESPE (SB)] and a universal system [Adper™ Single Bond Universal, 3M ESPE (SU)]. Square-shaped specimens were prepared and assigned into 4 groups (n=5): SB and SU (control groups - no laser irradiation) and SB-L and SU-L [SB and SU laser (L) - irradiated groups]. DC was assessed using Fourier transform infrared spectroscopy with attenuated total reflectance. Additional uncured resin samples (≈3.0 µL, n=5) of each adhesive were also scanned for final DC calculation. For WS/WSB tests, similar specimens (n=10) were prepared and measured by monitoring the mass changes after dehydration/water storage cycles. For both tests, adhesive fluids were dropped into standardized Teflon molds (6.0×6.0×1.0 mm), irradiated with a 970-nm laser diode, and then polymerized with an LED-curing unit (1 W/cm2). RESULTS: Laser irradiation immediately before photopolymerization increased the DC (%) of the tested adhesives: SB-L>SB>SU-L>SU. For WS/WSB (µg/mm3), only the dentin bonding system (DBS) was a significant factor (p<0.05): SB>SU. CONCLUSION: Irradiation with a laser diode improved the degree of conversion of all tested simplified dentin bonding systems, with no impact on water sorption and solubility.

Does laser diode irradiation improve the degree of conversion of simplified dentin bonding systems?

Abstract Simplified dentin-bonding systems are clinically employed for most adhesive procedures, and they are prone to hydrolytic degradation. Objective This study aimed to investigate the effect of laser diode irradiation on the degree of conversion (DC), water sorption (WS), and water solubility (WSB) of these bonding systems in an attempt to improve their physico-mechanical resistance. Material and Methods Two bonding agents were tested: a two-step total-etch system [Adper™ Single Bond 2, 3M ESPE (SB)] and a universal system [Adper™ Single Bond Universal, 3M ESPE (SU)]. Square-shaped specimens were prepared and assigned into 4 groups (n=5): SB and SU (control groups - no laser irradiation) and SB-L and SU-L [SB and SU laser (L) - irradiated groups]. DC was assessed using Fourier transform infrared spectroscopy with attenuated total reflectance. Additional uncured resin samples (≈3.0 µL, n=5) of each adhesive were also scanned for final DC calculation. For WS/WSB tests, similar specimens (n=10) were prepared and measured by monitoring the mass changes after dehydration/water storage cycles. For both tests, adhesive fluids were dropped into standardized Teflon molds (6.0×6.0×1.0 mm), irradiated with a 970-nm laser diode, and then polymerized with an LED-curing unit (1 W/cm2). Results Laser irradiation immediately before photopolymerization increased the DC (%) of the tested adhesives: SB-L>SB>SU-L>SU. For WS/WSB (μg/mm3), only the dentin bonding system (DBS) was a significant factor (p<0.05): SB>SU. Conclusion Irradiation with a laser diode improved the degree of conversion of all tested simplified dentin bonding systems, with no impact on water sorption and solubility.