Influence of a propolis-based irrigant solution on gap formation and bond strength of posts bonded to root canal dentin using different resin cements.

This study evaluated the influence of an aqueous propolis-based solution (PROP) on gap formation and bond strength of posts bonded to root canal dentin using resin cements. Endodontically-treated bovine incisors received different irrigation protocols: 1) 2.5% sodium hypochlorite (NaOCl)/17% EDTA/NaOCl; 2) saline solution (NaCl)/EDTA/0.12% chlorhexidine (CHX); 3) NaOCl/PROP/NaOCl; 4) NaCl/PROP/CHX; 5) NaCl/PROP/NaCl. Posts were then bonded with cements: RelyX ARC; Panavia F2.0; or RelyX U200 (n=10). The specimens were cross-sectioned. Gaps were assessed and performed the push-out bond strength test. Surface roughness of dentin fragments was also evaluated. Statistical analysis was performed (5%). RelyX U200 exhibited greater gap-free interfaces. Bond strength varied as a function of cements and irrigation protocols. PROP irrigation had no negative effect on the bond strength (p>0.05). Roughness increased significantly after NaOCl/EDTA/NaOCl, but remained unaltered after PROP irrigation protocols. Propolis-based irrigation protocols do not interfere in the bonding performance of posts cemented to root canal dentin.

Hydrolytic degradation of different infiltrant compositions within different histological zones of enamel caries like-lesions.

This study evaluates the effects of resin infiltrant composition and caries histological zone on the hydrolytic degradation of resininfiltrated artificial bovine enamel caries (RI-AEC). Different resin infiltrants were tested (n=26 per group): Icon (G1); TEGDMA 60%, UDMA 20%, and HEMA 20% (TUH); TEGDMA 80% and HEMA 20% (TH); and TEGDMA 75% and Bis-EMA 25% (TB). Following caries infiltration, samples were cut perpendicularly, and transverse microhardness were analyzed (at two histological zones: surface layer and lesion body) before and after 21 days of water immersion. TB presented lower decrease in microhardness (due to hydrolytic degradation) than the other groups, with a large effect size (Hedge's G from 0.83 to 1.19) and high power (84 to 99%). Neither histological zone nor its interaction with resin infiltrant composition significantly affected the outcome. In conclusion, resin composition affected microhardness of RI-AEC upon water immersion, and TB was the least affected.

Influence of the incorporation of triclosan methacrylate on the physical properties and antibacterial activity of resin composite.

The incorporation of antimicrobials in the composites as an attempt to reduce bacterial adhesion without jeopardizing mechanical properties is a challenge for Dentistry. OBJECTIVE To evaluate the bacterial adhesion and physical properties of a composite containing the methacrylate triclosan- derivative monomer (TM). METHODOLOGY TM was synthesized and added to an experimental composite. Samples were divided into two groups: Control and TM (13.4 wt%). Antibacterial Activity: Three specimens of each material were prepared and placed on bacterial suspensions of Streptococcus mutans for 1, 5 and 10 days. After these periods the counting of the colonies (log10) was performed. Assays was performed in triplicate. Physical Properties: Three-body Abrasion (TBA): Ten specimens of each material were prepared and stored at 37°C/24 h. The surface roughness (Ra) and hardness (KHN) were analyzed. Next, the specimens were submitted to abrasive wear (30,000 cycles) and re-evaluated for Ra and KHN; Sorption/solubility (SS): cylindrical specimens (n=10) were prepared and weighted. The specimens were immersed in deionized water for 7 days at 37°C and then their weight was verified again. SS were calculated using accepted formulas; Diametral tensile strength (DTS): specimens (n=10) underwent test performed in an Instron universal testing machine at a crosshead speed of 1 mm/min. Data were submitted to appropriate statistical tests according to data distribution and assay (p<0.05). RESULTS Bacterial Adhesion: TM showed a significant reduction on biofilm accumulation in the evaluated periods: 1 day (1.537±0.146); 5 days (2.183±0.138) and 10 days (4.469±0.155) when compared with Control: 1 day (4.954±0.249); 5 days (5.498±0.257) and 10 days (6.306±0.287). Physical Properties: For TBA, SS and DTS no significant difference was found between groups Control and TM. The incorporation of methacrylate triclosan-based monomer in the experimental composite reduce bacterial adhesion of S. mutans and did not affect important polymer properties.

Synthesis and application of triclosan methacrylate monomer in resin composites.

OBJECTIVES: To evaluate the antibacterial activity, bacterial viability, cytotoxicity, and mechanical/physical properties of a novel methacrylate triclosan-derivative monomer (TM) incorporated in dental resin composite. METHODS: TM was synthesized by esterification and, after characterization by FT-IR, was added to an experimental composite. Samples were divided into two groups according to TM presence, i.e., C1 (control) and C2 (C1 + 14.4% TM). Microbiological properties: Specimens (C1 and C2) were prepared and placed on bacterial suspensions of Streptococcus mutans. Antibacterial activity, MTT, and live/dead bacterial viability were used to test the resin composites. All assays were performed in triplicates. Mechanical properties: Specimens underwent compression (CS) and flexural strength (FS) tests conducted in an Instron universal testing machine at a crosshead speed of 0.5 mm/min. Physical properties: Specimens were assessed for Knoop hardness (KHN) and crosslink density (CD). Fourier transform infrared spectroscopy allowed the degree of conversion (DC) to be evaluated. Data were subjected to appropriate statistical tests according to data distribution and assay (p < 0.05). RESULTS: Microbiological properties: C2 showed the lowest biofilm accumulation and the highest membrane-compromised bacteria in the biofilm. Mechanical/physical properties: For CS, FS, KHN, and DC, there was no significant difference between groups C1 and C2; however, significant difference was observed for the CD assay. CONCLUSIONS: The triclosan methacrylate reduces bacterial adhesion of S. mutans and decreased the formation of bacterial biofilm without affecting important polymer properties. The triclosan methacrylate incorporated in resin composite could greatly reduce the live bacterial adhesion of S. mutans and decrease the formation of bacterial biofilm without affecting important polymer properties. CLINICAL SIGNIFICANCE: The resin composites containing triclosan methacrylate could greatly reduce the bacterial adhesion and biofilm formation. That might prevent the secondary caries round the margins of the restorations.

Influence of the incorporation of triclosan methacrylate on the physical properties and antibacterial activity of resin composite

Abstract The incorporation of antimicrobials in the composites as an attempt to reduce bacterial adhesion without jeopardizing mechanical properties is a challenge for Dentistry. Objective: To evaluate the bacterial adhesion and physical properties of a composite containing the methacrylate triclosan- derivative monomer (TM). Methodology: TM was synthesized and added to an experimental composite. Samples were divided into two groups: Control and TM (13.4 wt%). Antibacterial Activity: Three specimens of each material were prepared and placed on bacterial suspensions of Streptococcus mutans for 1, 5 and 10 days. After these periods the counting of the colonies (log10) was performed. Assays was performed in triplicate. Physical Properties: Three-body Abrasion (TBA): Ten specimens of each material were prepared and stored at 37°C/24 h. The surface roughness (Ra) and hardness (KHN) were analyzed. Next, the specimens were submitted to abrasive wear (30,000 cycles) and re-evaluated for Ra and KHN; Sorption/solubility (SS): cylindrical specimens (n=10) were prepared and weighted. The specimens were immersed in deionized water for 7 days at 37°C and then their weight was verified again. SS were calculated using accepted formulas; Diametral tensile strength (DTS): specimens (n=10) underwent test performed in an Instron universal testing machine at a crosshead speed of 1 mm/min. Data were submitted to appropriate statistical tests according to data distribution and assay (p<0.05). Results: Bacterial Adhesion: TM showed a significant reduction on biofilm accumulation in the evaluated periods: 1 day (1.537±0.146); 5 days (2.183±0.138) and 10 days (4.469±0.155) when compared with Control: 1 day (4.954±0.249); 5 days (5.498±0.257) and 10 days (6.306±0.287). Physical Properties: For TBA, SS and DTS no significant difference was found between groups Control and TM. The incorporation of methacrylate triclosan-based monomer in the experimental composite reduce bacterial adhesion of S. mutans and did not affect important polymer properties.

Effect of Camphorquinone Concentration in Physical-Mechanical Properties of Experimental Flowable Resin Composites.

The aim of this study was to evaluate the effect of camphorquinone concentration in physical-mechanical properties of experimental flowable composites in order to find the concentration that results in maximum conversion, balanced mechanical strength, and minimum shrinkage stress. Model composites based on BISGMA/TEGDMA with 70% wt filler loading were prepared containing different concentrations of camphorquinone (CQ) on resin matrix (0.25%, 0.50%, 1%, 1.50%, and 2% by weight). Degree of conversion was determined by FTIR. Surface hardness was assessed before and after 24 h ethanol storage and softening rate was determined. Depth of cure was determined by Knoop hardness evaluation at different depths. Color was assessed by reflectance spectrophotometer, employing the CIE-Lab system. Flexural strength and elastic modulus were determined by a three-point bending test. Shrinkage stress was determined in a Universal Testing Machine in a high compliance system. Data were submitted to ANOVA and Tukey's test (α = 0.05). The increase in CQ concentration caused a significant increase on flexural strength and luminosity of composites. Surface hardness was not affected by the concentration of CQ. Composite containing 0.25% wt CQ showed lower elastic modulus and shrinkage stress when compared to others. Depth of cure was 3 mm for composite containing 1% CQ and 2 mm for the other tested composites. Degree of conversion was inversely correlated with softening rate and directly correlated with elastic modulus and shrinkage stress. In conclusion, CQ concentration affects polymerization characteristics and mechanical strength of composites. The concentration of CQ in flowable composite for optimized polymerization and properties was 1% wt of the resin matrix, which allows adequate balance among degree of conversion, depth of cure, mechanical properties, and color characteristics of these materials.

Clinical Time Required and Internal Adaptation in Cavities restored with Bulk-fill Composites.

AIM: The aim of this study was to compare the restorative time required and the internal adaptation after thermomechanical aging of class I restorations using either the conventional incremental technique or bulk-fill technique. MATERIALS AND METHODS: Cavities (Class I) were prepared on the occlusal surface of human third molars. 40 teeth were divided into four experimental groups according to the restorative technique (n = 10): G1 = 3 mm increment of Surefill SDR Flow + 1 mm Filtek P60; G2 = 3 mm increment of Filtek Bulk-Fill + 1 mm Filtek P60; G3 = Filtek P60 inserted with incremental technique; G4 = 3 mm increment of Filtek Z350 Flow XT + 1 mm increment of Filtek P60. The required restorative clinical time for each technique was marked. Specimens were submitted to thermomechanical loading (20,000 mechanical cycles-80 N/thermal cycling-5/55°C for 30 seconds). After, samples were sectioned, ratio of internal gaps to interface length (%) was recorded using dye-staining-gap technique. Data were submitted to analysis of variance (ANOVA) and Tukey's test (95% significance). RESULTS: There was no significant difference in gap formation and none of the groups was completely gap-free. However, a significant reduction on required restorative clinical time was observed for G1 (167 ± 7 seconds), G2 (169 ± 4 seconds), and G4 (169 ± 8 seconds) when compared with G3 (204 ± 8 seconds). CONCLUSION: No significant difference in gap formation was found among bulk-fill and conventional incremental restorative technique tested; however, the use of a bulk-fill composite reduced 20% of the required restorative clinical time. CLINICAL SIGNIFICANCE: None of the restorative techniques applied were able to prevent internal gap formation. The use of bulk-fill composite reduced the required clinical time to perform class I restorations.

Evaluation of sorption/solubility, softening, flexural strength and elastic modulus of experimental resin blends with chlorhexidine.

OBJECTIVES: To evaluate physical-chemical properties of experimental diacetate chlorhexidine (CHX)-added resin blends. METHODS: Blends were formulated: G1)TEGDMA; G2)TEGDMA/0.1%CHX; G3)TEGDMA/0.2%CHX; G4)TEGDMA/UDMA; G5)TEGDMA/UDMA/0.1%CHX; G6)TEGDMA/UDMA/0.2%CHX; G7)TEGDMA/BisEMA, G8)TEGDMA/BisEMA/0.1%CHX; G9)TEGDMA/BisEMA/0.2%CHX. Icon(®) was the control group. For sorption/solubility (SS), cylindrical specimens (n=5) were prepared and their weight obtained. The specimens were immersed in deionized water for 7days at 37°C and their weight was verified again. SS were calculated using accepted formulas. For softening, cylindrical specimens (n=10) were prepared and initial Knoop hardness number (KHN) obtained. The specimens were immersed in absolute ethanol for 24h at 37°C and final KHN accomplished. Softening values were calculated by KHN reduction percentage. For elastic modulus (EM) and flexural strength (FS) bar specimens were prepared (n=10) and values obtained with a universal device (three point, 5mm distance, 0.5mm/min, load of 50N). The data was analyzed using one-way ANOVA and Tukey test (α=5%). RESULTS: TEGDMA/BisEMA blends and Icon(®) showed the lowest sorption from blends (p>0.05), and Icon(®) was the most soluble material (p<0.01). TEGDMA/UDMA/0.1%CHX showed the highest softening, similar to Icon(®) (p>0.05). For EM, all blends were different than Icon(®) (p<0.01). For FS, TEGDMA blends were similar to Icon(®), showing the lowest averages (p>0.05). CONCLUSIONS: Monomers chemical characteristics influenced the physical-chemical properties of experimental blends more than CHX. Between the blends tested, UDMA blends presented satisfactory results for assays evaluated. CLINICAL SIGNIFICANCE: Infiltrants CHX-added could arrest and reinforce initial caries lesions, and the antimicrobial effect could prevent new lesions in sound enamel adjacent to the infiltrated area.

Effect of monomer blend and chlorhexidine-adding on physical, mechanical and biological properties of experimental infiltrants.

OBJECTIVES: The aim of the study was to evaluate antimicrobial inhibition zone, degree of conversion (DC) and Knoop hardness (KH) of experimental infiltrants. Experimental low viscosity monomer blends were prepared and chlorhexidine diacetate salt (CHX) (0.1% or 0.2%) was added comprising the groups: G1) TEGDMA; G2) TEGDMA/0.1CHX; G3) TEGDMA/0.2CHX; G4) TEGDMA/UDMA; G5) TEGDMA/UDMA/0.1CHX; G6) TEGDMA/UDMA/0.2CHX; G7) TEGDMA/BISEMA; G8) TEGDMA/BISEMA/0.1CHX; G9) TEGDMA/BISEMA/0.2CHX. Icon® was used as control group. METHODS: Specimens of resin blends were made (n=9) to accomplished DC and KH. Pour plate was accomplished to evaluate antimicrobial groups' activity against Streptococcus mutans (SM) and Lactobacillus acidophilus (LA). Data obtained were submitted to two-way ANOVA and Tukey tests for blends comparisons and Dunnett's test for comparisons between experimental infiltrants and Icon® (p<0.05). RESULTS: In relation to antimicrobial effect, uncured blends showed higher antibacterial activity than cured ones for the most of blends. After polymerization, G5 showed the highest inhibition zone against SM and, G3 and G6 against LA. Concerning KH, TEGDMA/UDMA-based blends showed the highest values of KH number and it was influenced by monomeric base, regardless CHX concentration. DC was not affected by monomer blend composition, neither for CHX concentration. The antimicrobial activity was affected by monomeric base, CHX concentration and polymerization. Experimental infiltrants presented similar or higher performance than Icon® for the properties evaluated. SIGNIFICANCE: White spot lesion infiltration with low viscosity monomer blends (infiltrants) is an alternative to stop initial caries lesions progression. The incorporation of an antimicrobial agent as chlorhexidine diacetate salt in infiltrants composition could enhance the performance of these materials.

Polymerization kinetics and polymerization stress in resin composites after accelerated aging as a function of the expiration date.

OBJECTIVES: To determine the effect of material condition (new, aged, and expired) on the polymerization kinetics and polymerization stress of different classifications of dental composites. MATERIALS AND METHODS: Specimens were obtained according to the following factors: Composites: (3M ESPE) Filtek P60, Filtek Z250, Filtek Z350XT, and Filtek Silorane; and Material conditions: new, aged, and expired. The syringe composites underwent an accelerated aging protocol (Arrhenius model) representing approximately 9 months of aging. Infrared (IR) spectra were obtained kinetically and were analyzed for: maximum conversion rate (%/s), time into exposure when maximum rate occurred (s), conversion at maximum rate (%), and total conversion (%) at 90 s by comparison of absorption IR peak ratios before and after polymerization. Polymerization was evaluated at the bottom surface of 2.0 mm-thick specimens. Polymerization stress was determined in a tensilometer, inserting the composite between acrylic rods fixed to clamps in a universal test machine and dividing the maximum load recorded by the rods cross-sectional area. Polymerization stress (MPa) was calculated at 300 s. Data were statistically analyzed by two-way ANOVA and Tukey's post hoc test (α=0.05). RESULTS: The majority of the polymerization kinetic parameters were not influenced by the material condition. Silorane composite presented significantly lower conversion rate and lower conversion at the maximum rate when expired (p<0.05). The nanofilled composite (Filtek Z350XT) presented a significantly higher total conversion when aged and expired compared to the new one (p>0.05). In all conditions, Filtek Z350XT and Filtek Silorane presented significantly lower conversion rates (p < 0.05). Filtek Silorane also exhibited the lowest stress, irrespective of the material condition (p<0.05). The polymerization stress was not influenced by the material condition (p>0.05). CONCLUSIONS: Most of the kinetic parameters are not influenced by the material condition. Filtek P60 and Filtek Z250 are more stable as both composites present similar polymerization kinetic results, irrespective of the material condition. Silorane composite presents lower stress values among the tested materials in all conditions. Aging does not affect stress development in restorative composites.

Influence of chemical degradation and abrasion on surface properties of nanorestorative materials

Aim: The aim of this in vitro study was to investigate the synergistic effect of chemical degradation (erosion) and three-body abrasion (mechanical degradation) on the surface roughness (Ra) and hardness (KHN) of two nanorestorative materials and two conventional materials. Methods:Disc-shaped specimens (5 mm in diameter, 2 mm thick) of Filtek Z350TM and TPH SpectrumTM composites and Ketac NanoTM and VitremerTM light-curing glass ionomer cements, nanomaterials and conventional materials were prepared according to the manufacturer's instructions. After 24 h, polishing procedures were performed and initial measurements of Ra and KHN were taken in all specimens. The specimens were divided into 12 groups (n = 10) according to material and storage media: artificial saliva, orange juice, and Coca-Cola(r). After 30 days of storage, the specimens were submitted to mechanical degradation and re-evaluated for Ra and KHN. Data were tested for significant differences by repeated-measure three-way ANOVA and Tukey's tests (p<0.05). Results:Erosion and abrasion wear significantly decreased hardness of all materials. Only Filtek Z350 roughness, however, was not affected by erosion and abrasion. All materials showed a significant increase in surface roughness after erosion and abrasion, except for Filtek Z350. After chemical and mechanical degradation, the KHN of all samples had decreased significantly. After mechanical degradation, the acidic drinks (Coca-Cola(r) and orange juice) were more aggressive than artificial saliva to all materials. Conclusions:A synergistic effect was observed by the increase in roughness for all materials, except for Filtek Z350; hardness values decrease for all materials, regardless of whether they were nanofilled or not. The RMGICs were more susceptible to degradation than the composites, considering both hardness and roughness surface parameters.

Mechanical properties of composites as functions of the syringe storage temperature and energy dose

Objective: To investigate the mechanical properties of different classifications of composites indicated for posterior application as functions of the storage condition and of the energy dose. Material and Methods: Specimens (8x2x2 mm) were obtained according to the factors: I) Composites (3M ESPE): Filtek P60, Filtek Z350XT, and Filtek Silorane; II) Syringe storage conditions: room temperature, aged, oven, refrigerator, and freezer; and III) Energy dose: 24 J/cm2 and 48 J/cm2. After photoactivation, the specimens were stored at 37ºC for 24 h. After storage, a three-point bending test was carried out in a universal testing machine at 0.5 mm/min. Flexural strength (S) and flexural modulus (E) were calculated. Data were analyzed by three-way ANOVA and Tukey's test (α=0.05). Results: Different storage conditions significantly affected the silorane composite for S; conversely, no effects were noted in terms of E. The accelerated aging protocol significantly increased the S of Filtek P60 and Filtek Silorane, whereas storage in the oven significantly decreased the S for all of the composites tested. Filtek P60 was the only composite not affected by the lower storage temperatures tested for S, whereas for the silorane this parameter was impacted at the same conditions. The factor "dose" was not statistically significant. Conclusions: The syringe storage at different temperature conditions proved to influence mostly the flexural strength, a clinically important characteristic considering the posterior indication of the materials tested. The silorane composite should not be stored at lower temperatures. .

Mechanical properties of composites as functions of the syringe storage temperature and energy dose.

OBJECTIVE: To investigate the mechanical properties of different classifications of composites indicated for posterior application as functions of the storage condition and of the energy dose. MATERIAL AND METHODS: Specimens (8 x 2 x 2 mm) were obtained according to the factors: I) Composites (3M ESPE): Filtek P60, Filtek Z350XT, and Filtek Silorane; II) Syringe storage conditions: room temperature, aged, oven, refrigerator, and freezer; and III) Energy dose: 24 J/cm(2) and 48 J/cm(2). After photoactivation, the specimens were stored at 37 ºC for 24 h. After storage, a three-point bending test was carried out in a universal testing machine at 0.5 mm/min. Flexural strength (S) and flexural modulus (E) were calculated. Data were analyzed by three-way ANOVA and Tukey's test (α = 0.05). RESULTS: Different storage conditions significantly affected the silorane composite for S; conversely, no effects were noted in terms of E. The accelerated aging protocol significantly increased the S of Filtek P60 and Filtek Silorane, whereas storage in the oven significantly decreased the S for all of the composites tested. Filtek P60 was the only composite not affected by the lower storage temperatures tested for S, whereas for the silorane this parameter was impacted at the same conditions. The factor "dose" was not statistically significant. CONCLUSIONS: The syringe storage at different temperature conditions proved to influence mostly the flexural strength, a clinically important characteristic considering the posterior indication of the materials tested. The silorane composite should not be stored at lower temperatures.

Randomized, double-blind, placebo-controlled clinical trial on the effects of propolis and chlorhexidine mouthrinses on gingivitis.

OBJECTIVE: The aim of this study was to compare the effects of typified propolis and chlorhexidine mouthrinses on gingival health in a randomized double-blind placebo-controlled clinical trial. MATERIAL AND METHODS: Sixty participants were randomized to 3 mouthrinse study groups: 1) 2% typified propolis (n = 20); 2) 0.12% chlorhexidine (n = 20), and 3) placebo (n = 20). Participants rinsed unsupervised twice a day for 28 days. The Papillary Bleeding Score (PBS) was measured on the mesio-buccal surfaces of all teeth at baseline and 28 days thereafter. Co-variance analysis was employed to compare PBS average values and the number of sites with PBS ≥ 2 among study groups. Sub-group analysis was further applied to participants who were < 40 years-old. RESULTS: The results show efficacy of propolis mouthrinse when comparing before and after treatment protocols significantly for a reduction of mean PBS scores. For younger participants propolis mouthrinse was superior to all groups in reducing mean PBS scores and significant when compared to 0.12% chlorhexidine mouthrinse. CONCLUSION: The efficacy of 2% typified propolis mouthrinse was demonstrated in reducing the levels of gingival inflammation. These results need to be duplicated by other investigators under similar study protocols.

Randomized, double-blind, placebo-controlled clinical trial on the effects of propolis and chlorhexidine mouthrinses on gingivitis / Ensaio clínico duplo-cego randomizado e placebo-controlado dos efeitos de enxaguatórios a base de própolis e clorexidina na saúde gengival, para análise

Objective: The aim of this study was to compare the effects of typified propolis and chlorhexidine mouthrinses on gingival health in a randomized double-blind placebo-controlled clinical trial. Material and Methods: Sixty participants were randomized to 3 mouthrinse study groups: 1) 2% typified propolis (n = 20); 2) 0.12% chlorhexidine (n = 20), and 3) placebo (n = 20). Participants rinsed unsupervised twice a day for 28 days. The Papillary Bleeding Score (PBS) was measured on the mesio-buccal surfaces of all teeth at baseline and 28 days thereafter. Co-variance analysis was employed to compare PBS average values and the number of sites with PBS ≥ 2 among study groups. Sub-group analysis was further applied to participants who were < 40 years-old. Results: The results show efficacy of propolis mouthrinse when comparing before and after treatment protocols significantly for a reduction of mean PBS scores. For younger participants propolis mouthrinse was superior to all groups in reducing mean PBS scores and significant when compared to 0.12% chlorhexidine mouthrinse. Conclusion: The efficacy of 2% typified propolis mouthrinse was demonstrated in reducing the levels of gingival inflammation. These results need to be duplicated by other investigators under similar study protocols.

Objetivos: O propósito deste estudo foi o de comparar os efeitos de enxaguatórios a base de própolis tipificada e clorexidina na saúde gengival, empregando-se um ensaio clínico duplo cego, randomizado, e placebo-controlado. Material e Métodos: Sessenta participantes foram randomizados em 3 grupos de enxaguatórios, a saber: própolis tipificada 2% (n = 20), clorexidina 0,12% (n = 20) e placebo (n = 20). Os participantes bochecharam duas vezes ao dia por 28 dias os respectivos enxaguatórios. Medidas do índice de sangramento papilar (PBS) foram feitas na superfície mésio-bucal de todos os dentes dos participantes no tempo basal e após 28 dias. Análise de co-variância foi empregada permitindo comparações entre os grupos das médias do PBS e do número de sítios ≥ 2. Análise de sub-grupo foi efetuada em participantes com idade < 40 anos. Resultados: Constataram-se os efeitos positivos do enxaguatório de própolis a 2% na reducão da inflamação gingival após uso não supervisionado por 28 dias. Análise no sub-grupo de parcipantes com idade < 40 anos constatou superioridade do enxaguatório de própolis quando comparado com o enxaguatório de clorexidina a 0,12%. Conclusão: Este ensaio clínico demonstrou a eficácia de enxaguatório de própolis tipificada a 2% na redução da inflamação gengival. Estes resultados necessitam ser duplicados por outros investigadores.

Evaluation of polymerization characteristics and penetration into enamel caries lesions of experimental infiltrants.

OBJECTIVES: To evaluate the properties of experimental infiltrant blends by comparing them with the commercial infiltrant Icon(®) and penetration homogeneity into enamel caries lesions. METHODS: Groups were set up as follows: G1 (TEGDMA 100%); G2 (TEGDMA 80%, Ethanol 20%); G3 (TEGDMA 80%, HEMA 20%); G4 (TEGDMA 75%, BisEMA 25%); G5 (TEGDMA 60%, BisEMA 20%, Ethanol 20%); G6 (TEGDMA 60%, BisEMA 20%, HEMA 20%); G7 (TEGDMA 75%, UDMA 25%); G8 (TEGDMA 60%, UDMA 20%, Ethanol 20%); G9 (TEGDMA 60%, UDMA 20%, HEMA 20%) and Icon(®). Ten specimens were comprised by each group for the following tests (n=10): degree of conversion (DC), elastic modulus (EM), Knoop hardness (KH), and softening ratio (SR). Infiltrant penetration was evaluated using confocal microscopy (CLSM). Data were subjected to two-way ANOVA and a Tukey's test (5%). Data comparing experimental materials and Icon(®) were analysed using ANOVA and Dunnett's test (5%). RESULTS: The highest DC values were found in G1, G7, G8, and G9. The lowest DC values were found in G2, G4, G5, and G6. EM and KHN were significantly lower in HEMA and with ethanol addition for all blends, except for G9. There was no significant difference among the groups regarding SR, and it was not possible to take KHN readings of G2, G5, and G8 after storage. There was no significant difference among groups for infiltrant penetration into enamel lesions. CONCLUSIONS: The addition of hydrophobic monomers and solvents into TEGDMA blends affected DC, EM, and KHN. UDMA added to TEGDMA resulted in an increase in DC, EM, and KHN. Overall, solvents added to monomer blends resulted in decreased properties. The addition of hydrophobic monomers and solvents into TEGDMA blends does not improve the penetration depth of the infiltrants.

Hydrolytic degradation of silorane- and methacrylate-based composite restorations: Evaluation of push-out strength and marginal adaptation.

OBJECTIVES: This study compared the hydrolytic degradation of composite restorations based on methacrylate and silorane systems regarding bond strength and marginal adaptation. Materials and methods. Sixty bovine incisors were ground flat to obtain a 2-mm thick slice in which conical preparations were made. The specimens were randomly distributed into four groups (n = 15) according to the restorative system (silorane-Filtek LS/P90 adhesive; methacrylate-Filtek P60/Adper Easy Bond) and the degradation protocol (control: immediate evaluation; hydrolytic degradation: 6 months storage in water at 37°C). Marginal adaptation was evaluated using a dye staining technique. Digital images of the stained gaps were obtained to calculate the marginal gap (%), the ratio between the stained margins and the total length of the margin. Push-out bond strength test was conducted (0.5 mm/min). Marginal adaptation data was submitted to Kruskal-Wallis test and the bond strength data to two-way ANOVA/Tukey's test (α = 0.05). Results. The marginal adaptation was neither affected by the restorative system nor by the degradation protocol, although the number of perfect sealed reduced after 6 months. No significance was observed among the groups. No significance was noted between the silorane- and the methacrylate-based restorations for immediate bond strength. After the hydrolytic degradation, the silorane system showed higher bond strength then the methacrylate restorations. Conclusion. The silorane and methacrylate restorative systems produce restorations with similar immediate interfacial quality and 6 months of water storage does not cause significant bonding degradation for both systems. The silorane restorations show an increase in the bond strength after 6 months.

Effects of curing protocols on fluid kinetics and hardness of resin cements.

The effects of polymerization protocols on water sorption/solubility, the diffusion coefficient (D), the flux (J), and the hardness (KH) of two resin cements were evaluated. The materials were manipulated and divided into three groups (n=6) according to the curing protocol: PA=photoactivation (40 s); DP=delayed photoactivation (10 min self-curing plus 40 s photoactivated); CA=chemical activation. After desiccation, the specimens were weighed, stored in water (37ºC), evaluated over 28-days, and hardness recorded. Chemical activation resulted in lower net water uptake, D, and J for RelyX ARC (RX). For Variolink II (VL), CA yielded equivalent D and lower J; however, photoactivation resulted in lower net water uptake. Hardness of VL was less affected by the water storage, irrespective of the polymerization protocol. Considering the water diffusion parameters, VL demonstrated immediate photoactivation dependence; for RX, a chemical activation. Different polymerization protocols affect the fluid kinetics and the hardness of the resin cements tested.

Influence of etching time and bonding strategies on the microshear bond strength of self- and light-cured pit-and-fissure sealants

This study evaluated the impact of extended etching and bonding strategies on the microshear bond strength of three sealant materials. Two pit-and-fissure sealants [FluroShield, Dentsply (light-cured) and AlphaSeal, DFL (self-cured)] and one light-cured flowable composite resin (Permaflo, Ultradent) were evaluated according to different enamel etching times (15 s or 30 s) and bonding procedures (no adhesive application, application of primer/hydrophobic resin or hydrophobic resin only). Intact enamel blocks were obtained from bovine teeth and sealed via the tested protocols. After 24 h, the microshear bond strength test was performed in a universal testing machine at a crosshead speed of 0.5 mm/min. Failure modes were classified by stereomicroscopy. Data were submitted to a three-way ANOVA and to Tukey's test (α=0.05). There was no statistically significant difference (p>0.05) among the materials. Permaflo showed higher bond strength when etched for 30 s alone. Enamel overetching decreased the bond strength of the light-cured sealant. Primer/bond previous treatment improved bond performance for AlphaSeal. In conclusion, from the tested conditions, all sealant materials presented similar bond strength values in relation to bonding protocol and etching time. The flowable composite can be used as a pit-and-fissure sealant. The use of a three-step adhesive system was essential for the self-cured sealant application.

Este trabalho avaliou o impacto de tempos aumentados de condicionamento ácido e da estratégia adesiva na resistência de união por microcisalhamento de três materiais utilizados como selantes de fóssulas e fissuras. Dois tradicionais selantes, [FluroShield, Dentsply (fotoativado) e AlphaSeal, DFL (quimicamente ativado)] e uma resina composta de baixa viscosidade (Permaflo, Ultradent) foram utilizados de acordo com diferentes tempos de condicionamento ácido (15 s e 30 s) e diferentes estratégias de união (sem aplicação de sistema adesivo, aplicação de um primer + resina hidrófoba, e aplicação apenas de uma resina hidrófoba). Fragmentos de esmalte intacto foram obtidos de incisivos bovinos e os materiais foram aplicados respeitando-se os protocolos anteriormente descritos. Após 24 h, o teste de microcisalhamento foi executado utilizando-se uma máquina de ensaio universal, com velocidade de 0,5 mm/min. O padrão de fratura foi classificado com auxílio de lupa estereoscópica. Os dados foram submetidos aos testes ANOVA a três critérios e de Tukey (α=0.05). Não houve diferenças estatisticamente significantes entre os materiais. Permaflo apresentou maior resistência de união quando o esmalte foi condicionado por 30 s apenas. O sobrecondicionamento do esmalte diminuiu a resistência de união do selante fotopolimerizável. O tratamento prévio do esmalte com primer + resina hidrófoba melhorou a performance adesiva para o AlphaSeal. Todos os materiais apresentaram valores de resistência de união estatisticamente similares em relação ao protocolo adesivo e ao tempo de condicionamento ácido. A resina composta de baixa viscosidade poderá ser utilizada como selante de fóssulas e fissuras. A aplicação de um sistema adesivo de três passos é essencial durante o selamento com selante quimicamente ativado.

Impact of adhesive and photoactivation method on sealant integrity and polymer network formation

We evaluated the influence of photoactivation method and hydrophobic resin (HR) application on the marginal and internal adaptation, hardness (KHN), and crosslink density (CLD) of a resin-based fissure sealant. Model fissures were created in bovine enamel fragments (n = 10) and sealed using one of the following protocols: no adhesive system + photoactivation of the sealant using continuous light (CL), no adhesive system + photoactivation of the sealant using the soft-start method (SS), HR + CL, or HR + SS. Marginal and internal gaps and KHN were assessed after storage in water for 24 h. The CLD was indirectly assessed by repeating the KHN measurement after 24 h of immersion in 100% ethanol. There was no difference among the samples with regard to marginal or internal adaptation. The KHN and CLD were similar for samples cured using either photoactivation method. Use of a hydrophobic resin prior to placement of fissure sealants and curing the sealant using the soft-start method may not provide any positive influence on integrity or crosslink density.