Flavonoids effects against bacteria associated to periodontal disease and dental caries: a scoping review.

This scoping review focused on exploring the efficacy of flavonoids against bacteria associated with dental caries and periodontal diseases. Inclusion criteria comprise studies investigating the antibacterial effects of flavonoids against bacteria linked to caries or periodontal diseases, both pure or diluted in vehicle forms. The search, conducted in August 2023, in databases including PubMed/MEDLINE, Scopus, Web of Science, Embase, LILACS, and Gray Literature. Out of the initial 1125 studies, 79 met the inclusion criteria, majority in vitro studies. Prominent flavonoids tested included epigallocatechin-gallate, apigenin, quercetin, and myricetin. Predominant findings consistently pointed to bacteriostatic, bactericidal, and antibiofilm activities. The study primarily investigated bacteria associated with dental caries, followed by periodontopathogens. A higher number of publications presented positive antibacterial results against Streptococcus mutans in comparison to Porphyromonas gingivalis. These encouraging findings underline the potential applicability of commercially available flavonoids in materials or therapies, underscoring the need for further exploration in this field.

Effect of experimental dentin etchants on dentin bond strength, metalloproteinase inhibition, and antibiofilm activity.

OBJECTIVE: this study evaluated dentin microtensile bond strength (µTBS) and failure modes (at 24 h and one year), bonding interface regarding hybridization, surface morphology regarding demineralization, in situ metalloproteinase (MMP) activity, and antibacterial effect of three dentin etchants compared to 35% phosphoric acid (PA). MATERIALS AND METHODS: The Adper Single Bond 2 adhesive (3 M Oral Care) was applied on moist dentin etched with PA (control) or on air-dried dentin etched with 3% aluminum nitrate + 2% oxalic acid (AN), 6.8% ferric oxalate + 10% citric acid (FO), or 10% citric acid (CA). The µTBS test used 40 human teeth (n = 10). Failure modes and surface morphology were analyzed by scanning electron microscopy (n = 3), while bonding interface morphology and MMP activity were evaluated by laser scanning confocal microscopy (n = 3). Antibacterial activity was evaluated against S. Mutans biofilm by means of viable cells count (CFU/mL). RESULTS: PA presented the highest bond strengths regardless of aging time. PA, AN, and CA showed stable bond strengths after one year of storage. Adhesive and mixed failures were predominant in all groups. Thin hybrid layers with short resin tags were observed for the experimental etchants. The AN-based etchant was able to inhibit MMP activity. All tested etchants presented antibacterial activity against S. Mutans biofilm. SIGNIFICANCE: This study suggests different dentin etchants capable of inhibiting MMP activity while also acting as cavity disinfectants.

Effect of Tooth Brushing Cycles and Dentifrice Fluoride Concentration on a Glazed CAD/CAM Ceramic.

PURPOSE: To evaluate the effect of tooth brushing and dentifrice fluoride (F-) concentration on changes in color and translucency (ΔE00 and ΔT00, respectively), surface gloss (GS), surface roughness (Sa), and microstructure of a glazed CAD/CAM ceramic. MATERIALS AND METHODS: Ceramic blocks (e.max/CAD) were sectioned into rectangular plates (14 x 12 x 1 mm), and one surface of each sample was glazed. Samples were divided into three groups according to the F- concentration in the dentifrice (0, 1,100, and 5,000 µg/g) and were then subjected to 60,000 tooth brushing cycles. Luminosity and color were measured using a spectrophotometer at baseline and after every 20,000 cycles to obtain their ΔE00 and ΔT00 values. Another set of samples was prepared to measure the GS with a gloss meter and the Sa with a confocal laser microscope. The GS and Sa results were subjected to analysis of variance, Tukey test, and Dunnett test (α = .05). RESULTS: After 60,000 tooth brushing cycles, all of the variables were clinically acceptable, and there were no significant differences in the ΔE00, ΔT00, GS, or Sa among the fluoridated dentifrices. The GS values decreased significantly as the number of tooth brushing cycles increased. CONCLUSION: The ΔE00, ΔT00, GS, and Sa values were all clinically acceptable after the glazed e.max/CAD ceramic had been subjected to 60,000 tooth brushing cycles with dentifrices containing up to 5,000 µg/g of F-.

Effect of build orientation in gloss, roughness and color of 3D-printed resins for provisional indirect restorations.

OBJECTIVES: The purpose of this study was to evaluate the effect of build orientation of 3D-printed provisional resins (3DRs) on gloss (Gs), surface roughness (Sa), maximum profile valley depth (Rv), and color difference (∆E00). METHODS: PMMA CAD/CAM blocks (Vita Temp/Vita) were sectioned and served as a Control. Four 3DRs (Cosmos-SLA/Yller, Cosmos-DLP/Yller, PriZma-Bioprov/Makertech, Nanolab/Wilcos) were obtained as discs (15-mm diameter, 2.5-mm thickness) in three orientations (0°, 45°, and 90°) using different 3D printers (Form 2/Formlabs, P30/Straumann, Hunter/Flashforge, W3D/Wilcos, respectively). Samples were then cleaned with isopropyl alcohol prior to post-curing in specific post-curing units. Half of the samples' surface was covered with an adhesive tape and submitted to 10,000 toothbrushing (TB) cycles. The Gs and Sa at the brushed and not brushed surfaces were evaluated with a glossmeter (Novo-curve) and a laser confocal microscope (OLS5000) (n = 10), which also obtained the Rv and 3D representative images of the interface between not brushed and brushed surfaces. Electron microscopy images of the surface of some samples was also performed (n = 3). On another set of samples (n = 5), the coordinates of luminosity and color were obtained with a spectrophotometer (Easyshade V) at baseline and after 16.7 h and 200 h of UVB aging, to calculate the ∆E00 using CIEDE:2000 formula. Additionally, 3DRs photoinitiators were identified using a minispectrometer (USB2000 +) (n = 5). Data of Gs and Sa were submitted to three-way-, Rv to two-way-, and ∆E00 to mixed-ANOVA tests, followed by Tukey's test (α = 0.05). For all variables, results from experimental groups were compared to control using Dunnett's test (α = 0.05). Student's t-test was used to compare the control at different TB cycles (Gs, Sa) or aging periods (∆E00) (α = 0.05). RESULTS: Build orientation of 3DRs did not influence any of the variables studied. The 10,000 TB cycles resulted in a decrease in Gs and increase in Sa for all resins tested. The control showed higher Gs after 10,000 TB cycles than Cosmos-SLA and Nanolab resins. Compared to all 3DRs, Control presented lower ∆E00 after 200 h of UVB aging. All 3DRs presented higher ∆E00 than the clinically acceptable after 200 h of UVB aging. Lucirin® TPO was identified in all 3DRs, although PriZma might also present other photoinitiators and Nanolab might present Irgacure 369. SIGNIFICANCE: Alterations in build orientation are very useful and frequently performed in the day-today of 3D-printing, thus its effect in the optical properties and in the topography of 3D-printed restorations is very relevant. For the evaluated 3D-printed provisional resins, build orientation did not influence any of the variables studied (Gs, Sa, Rv, and ∆E00), even after toothbrushing cycles and UVB aging.

Effect of build orientation in accuracy, flexural modulus, flexural strength, and microhardness of 3D-Printed resins for provisional restorations.

PURPOSE: This study evaluated the effects of 3D-printing build orientation on accuracy, flexural modulus (FM), flexural strength (FS), and microhardness of selected, commercial 3D-printed provisional resins (3DRs). MATERIAL AND METHODS: PMMA CAD/CAM provisional material (Vita Temp/Vita) served as Control. Four 3DRs (Cosmos-SLA/Yller, Cosmos-DLP/Yller, PriZma-Bioprov/Makertech, Nanolab/Wilcos) were used in three printing orientations (0°, 45°, and 90°). Printed samples were cleaned with isopropyl alcohol prior to post-curing in specific post-curing units. For each group, 20 bar-shaped samples (25 × 2x2 mm) and ten disc-shaped samples (15-mm diameter, 2.5-mm thick) were obtained. The dimensions of bar samples were measured and the mean percent errors were compared to the reference (digital) values to obtain "accuracy" (n = 20). Samples were then aged in distilled water at 37 °C and half were submitted to a three-point bend test in a universal testing machine after 24 h and the other half after 1 year (n = 10). Disc samples were polished prior to microhardness evaluation (n = 10). Microstructure and elemental composition of filler particles in the 3DRs were analyzed using scanning electron microscopy (SEM) and energy dispersive x-ray spectroscopy (EDS) (n = 3). Accuracy and microhardness were submitted to two way-, and FM and FS to three way-ANOVA, followed by Tukey's tests. Results of experimental groups were compared to a milled PMMA Control using Dunnett's tests, and Student's t-tests compared FM and FS to Control at different aging periods (α = 0.05). RESULTS: Except for Cosmos-DLP, the 90° orientation demonstrated the best overall accuracy in all dimensions evaluated. The overall accuracy of Cosmos-SLA was not significantly different from Control and higher than other 3DRs. The FM of all 3DRs was lower than Control, regardless of orientation and aging period. After 1 year of aging, FS of 45°-Cosmos-SLA and all orientations of PriZma were not different from Control, while 90°-Cosmos-SLA was higher. Build orientation had no influence on microhardness of the 3DRs: Nanolab was the only resin harder than Control. Very few nanometric spherical filler particles were found in Cosmos-SLA, Cosmos-DLP, and PriZma, while Nanolab presented higher number of particles having irregular shapes and sizes. CONCLUSIONS: In general, although build orientation did not influence microhardness results, the 90° -orientation resulted in the best overall accuracy for most 3DRs. After 1-year water storage, Cosmos-SLA printed vertically showed the highest FS, while the PMMA Control obtained the highest FM for both aging periods.

Polymerization Kinetics, Shrinkage Stress, and Bond Strength to Dentin of Conventional and Self-adhesive Resin Cements.

PURPOSE: To evaluate the kinetics of polymerization and shrinkage stress of resin cements, as well as their bond strength to dentin after 24-h or one-year water storage. MATERIALS AND METHODS: Three conventional resin cements were evaluated: RelyX Ultimate (RUL), Panavia V5 (PNV), and Multilink N (MLN); and three self-adhesive resin cements: RelyX Unicem 2 (RUN), Panavia SA Cement Plus (PSA), and G-CEM LinkAce (GCL). Degree of conversion (DC), maximum polymerization rate (RPmax) and gel time values were obtained using Fourier-transform infrared spectroscopy (FTIR/ATR). Shrinkage stress values were determined with a tensiometer, using a universal testing machine (n=5). Indirect resin composite restorations (Solidex) were fabricated and cemented to the dentin surface using self-adhesive resin cements, or conventional resin cements with self-etching adhesive (n=5). Bonding performance was evaluated with the microtensile bond strength (µTBS) test after 24 h or one year of water storage. RESULTS: MLN exhibited a higher DC (76.7%), whereas the percentage of other materials differed slightly (ranging from 54% to 58.5%). The RPmax and shrinkage stress values differed significantly between the cements. PSA showed the longest gel time. Significantly higher µTBS were observed for conventional resin cements after 24-h and one-year storage; a decrease in µTBS was observed for MLN only. CONCLUSION: Self-adhesive resin cements may not perform as well as conventional resin cements. Although both categories of cements presented similar polymerization kinetics and shrinkage values, the self-adhesive resin cements showed lower µTBS compared to those of conventional resin cements. Nevertheless, storage time only affected the bonding performance of MLN.

Color alterations, flexural strength, and microhardness of 3D printed resins for fixed provisional restoration using different post-curing times.

OBJECTIVES: To evaluate the effect of post-curing times on the color change, flexural strength (FS), modulus (FM) and microhardness at different depths of four 3D printed resins. MATERIALS AND METHODS: A characterization of the light emitted by 3D-resin post-curing unit (Wash and Cure 2.0, Anycubic) was performed. The tested 3D printed resins were Cosmos Temp3D (COS), SmartPrint BioTemp (SM) Resilab3D Temp (RES) and Prizma3D BioProv (PRI) were evaluated under five different post-curing conditions (no post-curing or 5-, 10-, 15, and 20 min of post-curing). For color change analysis, 10 mm diameter x 1 mm thick discs (n = 7) were printed, and the luminosity, color and translucency were measured before post-curing as control, and repeatedly after 5 min cycles of post-curing until a total of 20 min was reached for ΔE00 [CIED2000 (1:1:1)] calculation. For FS and FM, 25 × 2×2 mm (n = 10, for each post-curing time) 3D printed bars were subjected to a 3-point being test. Knoop microhardness (KHN) was measured transversally on 5 × 5×5 mm blocks (n = 10, for each post-curing time). Color results were analyzed by one-way repeated measures ANOVA (factor: color change). FS and FM were analyzed by two-way ANOVA (factors: Material*Post-Curing Time). KHN was analyzed individually for each material by two-way ANOVA (factors: Depth*Post-Curing Time). RESULTS: The post-curing time significantly influenced the ΔE00, FS, FM and KHN of all the evaluated materials. COS and SMA presented ΔE00 values above the acceptability threshold after 5 and 10 min of post-curing, respectively. The FS of RES reached a plateau after 5 min of post-curing, and for PRI and SMA, the FS stabilized after 10 min of post-curing. The post-curing process improved the KHN of the tested materials, and longer exposure periods were associated to higher KHN values at all the evaluated depths. SIGNIFICANCE: A fine adjustment of the post-curing time is crucial to produce adequate mechanical properties in 3D-printed restorative resins, while minimizing the color alterations on the restorations. For the evaluated resins, 5-10 min of post-curing will result in adequate mechanical properties, without affecting the acceptability in the color of the material. However, the results are material-dependent, and evaluation of each specific resin is advised.

Antibacterial efficacy of non-thermal atmospheric plasma against Streptococcus mutans biofilm grown on the surfaces of restorative resin composites.

The aim of this study was to evaluate the antimicrobial efficacy of non-thermal atmospheric plasma (NTAP) against Streptococcus mutans biofilms. Resin discs were fabricated, wet-polished, UV sterilized, and immersed in water for monomer extraction (37 °C, 24 h). Biofilms of bioluminescent S. mutans strain JM10 was grown on resin discs in anaerobic conditions for (37 °C, 24 h). Discs were divided into seven groups: control (CON), 2% chlorhexidine (CHX), only argon gas 150 s (ARG) and four NTAP treatments (30 s, 90 s, 120 s, 150 s). NTAP was applied using a plasma jet device. After treatment, biofilms were analyzed through the counting of viable colonies (CFU), bioluminescence assay (BL), scanning electron microscopy (SEM), and polymerase chain reaction (PCR). All NTAP-treated biofilm yielded a significant CFU reduction when compared to ARG and CON. BL values showed that NTAP treatment for 90 s, 120 s or 150 s resulted in statistically significantly lower metabolic activity when compared to the other groups. CHX displayed the lowest means of CFU and BL. SEM showed significant morphological changes in NTAP-treated biofilm. PCR indicated damage to the DNA structure after NTAP treatment. NTAP treatment was effective in lowering the viability and metabolism of S. mutans in a time-dependent manner, suggesting its use as an intraoral surface-decontamination strategy.

Microhardness homogeneity of RBCs light-cured with a multiple-peak LED and surface characterization after wear.

This in vitro study evaluated the effect of the beam homogeneity of a multiple-peak light-curing unit on the surface microhardness and the effect of toothbrushing wear on the microhardness, surface roughness, roughness profile, volume loss, and gloss retention of incremental and bulk-fill resin-based composites (RBCs). A LED light-curing unit (VALO) with four LEDs at the tip end (405, 445, 465A, and 465B nm emission peak) was used according to each manufacturer-recommended time to obtain disks (n=10) of six RBCs: Estelite Sigma Quick, Charisma Classic, Tetric EvoCeram Bulk Fill, Filtek Z250, Filtek Supreme Ultra, and Filtek Bulk Fill. Microhardness values were obtained according to each LED positioning of the light-curing unit on the top surface of the RBCs and were analyzed before and after toothbrushing regarding microhardness, surface roughness, roughness profile, volume loss, and gloss retention. Microhardness was considered homogeneous on the top surface regardless of the type of RBC or wavelength tested (p>0.05). Overall, toothbrushing did not reduce the microhardness of the RBCs but influenced the gloss values for most RBCs (p<0.001). Charisma Classic presented the greatest surface roughness and roughness profile after toothbrushing (p<0.05). Volume loss did not differ among RBCs (p>0.05). In conclusion, different wavelengths of the LED did not affect the top surface microhardness, regardless of the RBCs tested; and bulk-fill composites presented similar surface changes (microhardness, surface roughness, roughness profile, volume loss, and gloss retention) when compared to conventional composites after toothbrushing.

Microhardness homogeneity of RBCs light-cured with a multiple-peak LED and surface characterization after wear

Abstract This in vitro study evaluated the effect of the beam homogeneity of a multiple-peak light-curing unit on the surface microhardness and the effect of toothbrushing wear on the microhardness, surface roughness, roughness profile, volume loss, and gloss retention of incremental and bulk-fill resin-based composites (RBCs). A LED light-curing unit (VALO) with four LEDs at the tip end (405, 445, 465A, and 465B nm emission peak) was used according to each manufacturer-recommended time to obtain disks (n=10) of six RBCs: Estelite Sigma Quick, Charisma Classic, Tetric EvoCeram Bulk Fill, Filtek Z250, Filtek Supreme Ultra, and Filtek Bulk Fill. Microhardness values were obtained according to each LED positioning of the light-curing unit on the top surface of the RBCs and were analyzed before and after toothbrushing regarding microhardness, surface roughness, roughness profile, volume loss, and gloss retention. Microhardness was considered homogeneous on the top surface regardless of the type of RBC or wavelength tested (p>0.05). Overall, toothbrushing did not reduce the microhardness of the RBCs but influenced the gloss values for most RBCs (p<0.001). Charisma Classic presented the greatest surface roughness and roughness profile after toothbrushing (p<0.05). Volume loss did not differ among RBCs (p>0.05). In conclusion, different wavelengths of the LED did not affect the top surface microhardness, regardless of the RBCs tested; and bulk-fill composites presented similar surface changes (microhardness, surface roughness, roughness profile, volume loss, and gloss retention) when compared to conventional composites after toothbrushing.

Resumo Este estudo in vitro avaliou a homogeneidade do feixe de um fotopolimerizador de múltiplos picos na microdureza superficial e o efeito da escovação na microdureza, rugosidade superficial, perfil de rugosidade, perda de volume e retenção do brilho de compósitos a base de resina (RBCs) incrementais ou bulk-fill. Um fotopolimerizador LED (VALO) com quatro LEDs na ponteira (405, 445, 465A e 465B nm de pico de emissão) foi usado de acordo com o tempo recomendado por cada fabricante para obtenção de discos (n=10) de seis RBCs: Estelite Sigma Quick, Charisma Classic, Tetric EvoCeram Bulk Fill, Filtek Z250, Filtek Supreme Ultra e Filtek Bulk Fill. Os valores de microdureza foram obtidos seguindo o posicionamento de cada LED na superfície superior das amostras e foram analisados antes e após a escovação quanto a microdureza, rugosidade superficial, perfil de rugosidade, perda de volume e retenção do brilho. A microdureza foi considerada homogênea no topo da superfície, independentemente do tipo de RBCs ou comprimento de onda testados (p>0.05). No geral, a escovação não reduziu a microdureza das RBCs, mas influenciou o brilho para a maioria das RBCs (p<0.001). Charisma Classic apresentou os maiores valores de rugosidade superficial e perfil de rugosidade após a escovação (p<0.05). A perda de volume não diferiu entre as RBCs (p>0.05). Em conclusão, os diferentes comprimentos de onda do LED não alteraram a microdureza do topo da superfície, independentemente das RBCs testadas; e as resinas bulk-fill apresentaram alterações superficiais similares (microdureza, rugosidade superficial, perfil de rugosidade, perda de volume e manutenção do brilho) quando comparadas às resinas convencionais após a escovação.

Effect of toothbrushing on the surface of enamel, direct and indirect CAD/CAM restorative materials.

PURPOSE: To determine the effects of tooth brushing on the surface roughness (Sa) and morphology, maximum relative depth (Rv), gloss (GU), and microhardness (MH) of four esthetic restorative materials and enamel. MATERIALS AND METHODS: A light-curing composite resin (Filtek Supreme Ultra [FSU], 3M ESPE), two hybrid resin/ceramic CAD/CAM materials (Lava Ultimate [LAV], 3M ESPE, and VITA Enamic [VEN], VITA Zahnfabrik), and a CAD/CAM feldspathic ceramic (VITA Blocs Mark II [VMA], VITA Zahnfabrik) were evaluated. Bovine enamel (ENA) was used as a control group. All surfaces were polished in accordance with the manufacturer's instructions. Samples were analyzed before and after brushing (30,000 cycles) regarding Sa and Rv using a 3D laser-measuring microscope. GU was evaluated every 10,000 tooth brushing cycles. MH was also measured before and after tooth brushing. The surfaces were observed using scanning electron and laser measuring microscopies to determine the wear patterns. Data were analyzed by paired t test, one-way or two-way repeated measures analysis of variance, and Tukey test (α = .05), depending on the method performed. RESULTS: The Sa increased significantly after brushing for all materials, except for VMA, which showed the opposite effect. ENA and VEN showed higher Rv than VMA. After 30,000 tooth brushing cycles, VMA showed the highest GU, while FSU showed the lowest. Also, little surface topography changes were observed for VMA. MH did not change significantly after 30,000 brushing cycles, except for LAV. CONCLUSION: Brushing caused surface alterations in all tested materials except for feldspathic ceramic. The changes were more evident in resin-based materials.

Influence of beam homogenization on bond strength of adhesives to dentin.

OBJECTIVE: This study evaluated the effect of beam homogeneity on the microtensile bond strength (µTBS) of two adhesive resins to dentin. METHODS: One polywave light-emitting-diode (LED) LCU (Bluephase Style, Ivoclar Vivadent AG) was used with two different light guides: a regular tip (RT, 1010 mW/cm2 emittance) and a homogenizer tip (HT, 946 mW/cm2 emittance). The emission spectra and beam profiles were measured from both light guides. Extracted third molars were prepared for µTBS evaluation using two adhesive systems: Excite F (EXF) and Adhese Universal (ADU). Bond strength was calculated for each specimen (n = 10) at locations that correlated with the output of the two LED chips emitting blue (455 nm) and the one chip that emitted violet light (409 nm) after 24-hs and after one-year water-storage. The µTBS was analyzed using a four-way analysis of variance (factors: adhesive system, light guide, LED wavelength, and storage time) and post-hoc Tukey test (α = 0.05). RESULTS: EXF always delivered a higher µTBS than ADU (p < 0.0001), with the µTBS of ADU being about 20% lower than EXF. The light guide (p = 0.0259) and storage time (p = 0.0009) significantly influenced the µTBS. The LED wavelengths had no influence on the µTBS (p > 0.05). SIGNIFICANCE: Homogeneity of the emitted light beam was associated with higher 24-h µTBS to dentin, regardless of the adhesive tested. Also, differences in the composition of adhesives can affect their compatibility with restorative composites and their ability to maintain bonding over one year.

Photodynamic inactivation of Streptococcus mutans by curcumin in combination with EDTA.

OBJECTIVE: This study aimed to test the efficacy of photodynamic inactivation (PDI) mediated by curcumin with EDTA against Streptococcus mutans in planktonic suspension using blue LED light. METHODS: Antibacterial activity of curcumin and EDTA was evaluated by determination of their minimal inhibitory concentration (MIC) and minimal bactericidal concentration (MBC). The fractional inhibitory concentration index (FICI) was used to estimate the synergistic effect of various combination ratios of curcumin and EDTA against S. mutans. Cultures of S. mutans (18 h, 37 °C, 5% C02) were prepared to test the effect of curcumin-mediated PDI (50 µM and 500 µM) with or without 0.4% EDTA and 40 s of light-activation with blue light. EDTA and each concentration of curcumin were also tested individually. Chlorhexidine (0.2%), was used as positive control. Planktonic suspensions were also analyzed by viable colony counts (VCC), confocal laser scanning microscopy (CLSM), transmission electron microscopy (TEM), and polymerase chain reaction (PCR). RESULTS: The MIC values of curcumin and EDTA were 5 mM and 0.125% respectively. FICI showed a synergistic interaction between curcumin and EDTA. All the combinations with curcumin and blue LED light resulted in a complete inactivation of the S. mutans and CLSM confirms these results, TEM showed morphological changes produced by the PDI. No damage on DNA structure was detected by PCR. SIGNIFICANCE: Curcumin-mediated PDI with EDTA using a blue light, shows a strong inhibitory effect against S. mutans in planktonic culture. Because of the unspecific target mechanism, it could be a promising technique for disinfection of dental tissues.

Adhesion, Mechanical Properties, and Microstructure of Resin-matrix CAD-CAM Ceramics.

PURPOSE: To investigate the effects of 1-year water storage and surface treatments on shear bond strength (SBS) of two composite cements bonded to resin matrix CAD-CAM ceramics (RMCs) and on the mechanical properties of RMCs. MATERIALS AND METHODS: Three types of RMCs were tested: 1. polymer-infiltrated hybrid ceramic (PIHC, Enamic, VITA Zahnfabrik); 2. resin nanoceramic (RNC, Lava Ultimate, 3M Oral Care); and 3. flexible hybrid ceramic (FHC, Cerasmart, GC). One indirect laboratory composite (ILC, Epricord, Kuraray Noritake) was used as control. For each material, 60 plates (14 x 7 x 1 mm) were prepared for the SBS test and submitted to three different surface treatments: following manufacturer's instructions, non-thermal atmospheric plasma application (30 s), and plasma + bonding agent. Two composite cements were tested: RelyX Ultimate (3M Oral Care) and Panavia V5 (Kurarary Noritake). Two resin cylinders (1.5 mm diameter x 1.5 mm height) were bonded to each plate (n = 10), with one tested after 24-h storage in distilled water and the other after 1 year of storage in distilled water. Twenty rectangular bars (12 x 2 x 1 mm) of each indirect material were prepared and submitted to the 3-point flexural test after 24-h or 1-year water storage to determine the elastic modulus (EM) and flexural strength (FS) (n = 10). Fractured samples were also examined with SEM and energy dispersive x-ray spectroscopy (EDS). SBS data were analyzed by four-way ANOVA, and EM and FS data by two-way ANOVA, followed by Tukey's post-hoc test (α = 0.05). RESULTS: Groups treated in accordance with manufacturer's instructions exhibited higher SBS than did plasma and plasma + bonding agent groups for all indirect materials, composite cements, and storage periods tested. In general, RelyX Ultimate displayed higher mean SBS than did Panavia V5, except for some groups of ILC where manufacturer's instructions were followed. After 1-year storage in water, all groups exhibited a significant reduction in SBS, except for some groups that following manufacturer's instructions. ILC showed the lowest values of EM and FS. Among the CAD-CAM materials, FHC exhibited the lowest EM and highest FS means, while PIHC possessed the highest EM and lowest FS means for both storage periods. CONCLUSIONS: In general, following the respective manufacturer's instructions yielded the best bond strength results. For most materials, 1-year water storage decreased bond strength of composite cements to RMCs, as well as their FS, while increasing their EM. Microstructure and composition influenced the mechanical properties studied.

Effects of sodium hypochlorite as dentin deproteinizing agent and aging media on bond strength of two conventional adhesives.

This study evaluated the effect of 10% sodium hypochlorite (NaOCl) as deproteinizing agent and storage media on bond strength (BS) of two etch-and-rinse adhesive systems to dentin. Twenty-eight sound extracted human third molars were divided in four groups (n = 7), according to dentin treatment (conventional etching or etching followed by 10% NaOCl application) and adhesive systems (GB-Gluma 2Bond and OS-One-Step). After dentin treatments and adhesive application, a composite block was built-up on dentin surface and teeth were serially sectioned to obtain bonded sticks specimens. The sticks were submitted to three aging conditions: (24H) 24 hr in water (immediate), (SH) 3 hr of NaOCl accelerated-aging or (1Y) 1 year of water storage. Afterward, submitted to microtensile bond strength test (µTBS), failure modes and adhesive interfaces analyzes. Data were analyzed by two-way analysis of variance (ANOVA) and Tukey's test (α = .05). Dentin deproteinization before bonding significantly reduced µTBS for GB-treated group (p < .05), regardless the aging conditions. Water storage for 1 year (1Y) and NaOCl accelerated-aging (SH) decreased µTBS for both adhesives. Yet, the groups stored in NaOCl (SH) exhibited the lowest BS results (p < .05). Bond strength of deproteinized dentin was dependent on the adhesive system composition and NaOCl accelerated-aging promoted decreased bond strength and further degradation than water storage for 1 year.

Effect of Metal Primers on Bond Strength of a Composite Resin to Nickel-Chrome Metal Alloy.

This study evaluated the effects of three metal primers and one multi-mode adhesive system on the shear bond strength (SBS) of a flowable composite resin to nickel-chrome metal alloy (Ni-Cr). Ninety plates were cast from Ni-Cr and divided in nine groups (n=10). The surfaces were sandblasted with Al2O3 and primed with three adhesive primers: Alloy Primer (AP), Universal Primer (TP) and RelyX Ceramic Primer (CP), and a multi-mode adhesive (Scotchbond Universal, SU). The Adper Single Bond Plus (SB) and SU adhesives were also combined with adhesive primers. Control group did not have any surface treatment. The groups were: AP, AP+SB, AP+SU, TP+SB, TP+SU, CP+SB, CP+SU and SU. Composite cylinders were built on alloy surface. After 24 h, half the specimens were subjected to SBS and the other half to thermal cycling before testing. Data were analyzed by two-way ANOVA and Tukey's test (a=0.05). Failure modes were assessed by SEM observation. Higher SBS were obtained with AP and TP combined with adhesives at 24 h and the lowest one for control group. Thermocycling reduced SBS for AP, CP+SU and SU. Combination between TP and SU resulted in the highest SBS after the thermocycling. TP groups showed all types of failures and high incidence of mixed failures. The use of AP and UP metal primers before application of SU and SB adhesive systems increased the SBS of composite to Ni-Cr. These combinations between metal primers and adhesives had the highest SBS after thermocycling.

Effect of Metal Primers on Bond Strength of a Composite Resin to Nickel-Chrome Metal Alloy

Abstract This study evaluated the effects of three metal primers and one multi-mode adhesive system on the shear bond strength (SBS) of a flowable composite resin to nickel-chrome metal alloy (Ni-Cr). Ninety plates were cast from Ni-Cr and divided in nine groups (n=10). The surfaces were sandblasted with Al2O3 and primed with three adhesive primers: Alloy Primer (AP), Universal Primer (TP) and RelyX Ceramic Primer (CP), and a multi-mode adhesive (Scotchbond Universal, SU). The Adper Single Bond Plus (SB) and SU adhesives were also combined with adhesive primers. Control group did not have any surface treatment. The groups were: AP, AP+SB, AP+SU, TP+SB, TP+SU, CP+SB, CP+SU and SU. Composite cylinders were built on alloy surface. After 24 h, half the specimens were subjected to SBS and the other half to thermal cycling before testing. Data were analyzed by two-way ANOVA and Tukey’s test (a=0.05). Failure modes were assessed by SEM observation. Higher SBS were obtained with AP and TP combined with adhesives at 24 h and the lowest one for control group. Thermocycling reduced SBS for AP, CP+SU and SU. Combination between TP and SU resulted in the highest SBS after the thermocycling. TP groups showed all types of failures and high incidence of mixed failures. The use of AP and UP metal primers before application of SU and SB adhesive systems increased the SBS of composite to Ni-Cr. These combinations between metal primers and adhesives had the highest SBS after thermocycling.

Resumo Este estudo avaliou os efeitos de três primers para metais e um sistema adesivo multi-mode na resistência da união por cisalhamento (SBS) de um compósito resinoso de baixa viscosidade a uma liga niquel-cromo (Ni-Cr). Noventa placas Ni-Cr foram divididas em 9 grupos (n=10). As superfícies foram jateadas com Al2O3 e condicionadas com três primers adesivos: Alloy Primer (AP), Universal Primer (TP) e Rely X Ceramic Primer (CP) e um adesivo multi-mode (Scotchbond Universal, SU). Os adesivos Adper Single Bond Plus (SB) e SU foram combinados com os primers para metais. O grupo controle não recebeu nenhum tipo de tratamento superficial. Os grupos foram: AP, AP+SB, AP+SU, TP+SB, TP+SU, CP+SB, CP+SU e SU. Cilindros de resina foram construídos na superfície da liga. Após 24 h, metade dos espécimes foi submetido ao SBS, a outra metade foi termociclada previamente. Os dados foram analisados pelos testes ANOVA dois fatores e Tukey (a=0.05). Os tipos de fraturas foram determinados utilizando microscopia eletrônica de varredura (MEV). Os maiores valores de SBS foram obtidos com AP e TP combinados com adesivos após 24 h e o menor valor foi obtido no grupo controle. A ciclagem térmica reduziu a SBS para AP, CP+SU e SU. Combinação entre TP e SU resultou em altos valores de SBS após termociclagem. Os grupos TP apresentaram todos os modos de fratura e alta incidência de fraturas mistas. O uso dos primers AP e UP para metais antes da aplicação dos sistemas adesivos SU e SB aumentou a SBS entre o Ni-Cr e a resina composta. Essa combinação entre primers e adesivos mostrou os maiores valores de SBS após a termociclagem.