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In vitro comparative evaluation of antioxidative effect of selenium alone and in combination with green tea and alpha-tocopherol on the shear bond strength of universal composite resin to enamel after in-office bleaching.

Antioxidant application soon after bleaching process increases the shear bond strength (SBS) of composite resin to enamel. The aim of the study was to evaluate the antioxidant effects of selenium alone and in combination with alpha-tocopherol (αT) and green tea (GT) on SBS of composite resin to enamel following in-office bleaching with 38% hydrogen peroxide (HP). Sixty extracted human single -rooted premolar teeth were cleaned and embedded in acrylic resin blocks at the level of cementoenamel junction(CEJ) followed by bleaching with 38% hydrogen peroxide (HP) and arbitrarily divided into seven groups (n=10) for antioxidant application: Group I (negative control): intact teeth, Group II (positive control): only bleaching, Group III: 10% selenium (Se), Group IV: 10% alpha tocopherol (αT), Group V: 10% αT +10% Se, Group VI: 10% Green tea (GT), Group VII: 10%GT+10% Se. In all groups, self-etch adhesive was applied and composite restoration was done, and specimens were stored in distilled water for 24h followed by SBS evaluation. One-way analysis of variance and post hoc Tukey's tests were used (P < 0.05). The highest SBS was found in negative control Group I (intact teeth) and least in positive control Group II (bleached teeth), whereas in experimental groups, Group VII (GT + Se) showed highest followed by Groups V (αT + Se), III (Se), and VI (GT) and least in Group IV (αT). Combination of selenium with green tea and alpha tocopherol enhanced the SBS of composite resin following in-office bleaching.

Effect of glass-ceramic coating versus alumina air-abrasion on the bond strength and residual stress of zirconia.

To assess the effect of glass-ceramic coated zirconia versus alumina air-abraded zirconia on the shear bond strength (SBS) of resin cement and investigate the residual stresses present on both mechanically pre-treated surfaces. A total of 180 zirconia disks, with diameters of 10mm and 5mm, were divided into two groups: DCMhotbond glass-ceramic coated, followed by hydrofluoric acid etching (DCM), and alumina air-abraded (AB). All mechanically pre-treated disks were conditioned with G-Multi Primer and bonded using G-Cem Linkforce Cement. Ninety specimens were immersed in distilled water for 24h and subsequently allocated into three groups based on aging conditions (n = 15/subgroups): immediate testing, 5000 thermal cycles, and 10,000 thermal cycles. Then, the shear bond strength was assessed, and the obtained data were subjected to analysis using a two-way ANOVA, followed by a one-way ANOVA and Tukey's HSD post hoc test (α = 0.05). The residual stresses present on both mechanically pre-treated surfaces were examined using X-ray diffraction analysis. The mean SBS values of the DCM and AB groups showed no significant difference under each aging condition. The SBS of DCM groups was not affected by thermal cycles, whereas the SBS of AB groups exhibited a significant decrease following thermal cycles. Glass-ceramic coated surfaces exhibited higher compressive stresses than alumina air-abrasion. The DCMhotbond glass-ceramic coated zirconia showed comparable bond strength to the alumina air-abrasion technique. The DCMhotbond glass-ceramic coating technique is a promising alternative for zirconia surface pre-treatment. However, further investigations are needed before suggesting its clinical use.

Interface adhesion on layered zirconia: Effects of the veneering ceramic material and veneering technique.

To evaluate the effect of different veneering ceramics and veneering techniques on the bond strength to zirconia. 3Y-TZP zirconia blocks were sliced into 60 slabs, polished, and sintered. Each slab received one ceramic cylinder (Ø = 3.4mm, 5mm-high), according to the veneering ceramic type (feldspathic-FEL or lithium disilicate-based-LD) and the veneering technique (file-splitting with resin-based luting agent-RC, file-splitting with fusion ceramic-FC, or heat-pressing-HT), which resulted in six groups: FEL-RC, FEL-FC, FEL-HT, LD-RC, LD-FC, LD-HT. After preparation, the samples were immersed in distilled water for 24h before the shear bond strength (SBS) test. The failure modes were classified as adhesive, predominantly adhesive, or cohesive. Representative failure mode images were taken in a Scanning Electron Microscope. The SBS data were analyzed by two-way ANOVA and Tukey's test. Both type of veneering ceramic and technique affected the bond strength. FC led to the highest SBS values. RC and HP provided similar results when compared within each veneering ceramic. Lithium disilicate achieved lower bond strength than feldspathic ceramic when the heat-pressing technique was applied. The most frequent failure modes were predominantly adhesive and adhesive for FEL and LD, respectively. File-splitting with fusion ceramic provided the highest adhesion to zirconia when feldspathic or lithium disilicate-based ceramics were used. The heat-pressing technique for veneering with lithium disilicate significantly decreased the bond strength when compared to the feldspathic ceramic.

Nova proposta para avaliação da solubilidade de materiais biocerâmicos em tubos de dentina após imersão em PBS: um estudo laboratorial

Abstract Introduction Repair materials must have low solubility. Phosphate buffered saline (PBS) allows simulating clinical condition and interaction with dentin may be important for the correct evaluate of mass loss of bioceramic cements. Objective To evaluate the effect of distilled water (DW), or PBS immersion on the solubility of Bio-C Repair (BCR, Angelus) or MTA Repair HP (MTAHP, Angelus) using a dentin tube model. Material and method Bovine dentin tubes with a length of 4 mm, an internal diameter of 1.5 mm and walls thickness of approximately 1 mm were made. The specimens were immersed in DW for 24h, then filled with BCR or MTAHP (n = 14) and stored in an oven at 37°C and 95% humidity for 24h. After being weighed on a precision balance to determine the initial mass, the specimens were immersed in DW (pH 6.5) or PBS (pH 7.0) (n = 7) for 28 days. Empty tubes also were used for calculating the mass loss of the dentin (n=4). After this period, the specimens were weighed until stabilization of the final mass occurred (0.001g). The solubility of each material was evaluated. ANOVA and Tukey statistical tests were performed (α=0.05). Result BCR and MTAHP showing gain of mass in DW and mass loss in PBS (p&lt;0.05). Conclusion The immersion solution influenced the solubility of BCR and MTAHP using dentin tube model. The new methodological proposal could be an alternative to ISO standards for testing the solubility of bioceramic cements.

Mushroom extract induces resistance in passion fruit and in vitro control of Xanthomonas axonopodis pv. Passiflorae

In vitro inhibitory capacity of Lentinula edodes and Agaricus blazei extracts on Xanthomonas axonopodis pv. passiflorae and their capacity to induce resistance in passion fruit in a greenhouse are evaluated. Aqueous crude extracts (CEs) were prepared by hydrating the basidiocarp dry powder with distilled water for 24h, at 4 ºC. CEs were added in test tubes at concentrations 10, 20, 30 and 40%, whilst control contained water only. Bacterial suspension (1 mL) was added to each tube (108 cfu.mL-1) and incubated in the dark at 28 °C for 24h. The bacterial suspension was measured by a spectrophotometer at 550 nm. Passion fruit cultivars IAC-275 and Epagri Oval Grande were sown on two substrates in a greenhouse: substrate 1 (SB) - horizon B soil; substrate 2 (SBC) - 40% soil from horizon B + 40% organic compost + 20% roughage (rice husk). A. blazei aqueous crude extract (ACE) treatments were applied at 20% and 40%; L. edodes ACE 20% and 40%; biofertilizer Agromos® 1% and control (without treatment) were started when the plants were in the 4-6 leaf stage. Sprays were done weekly, totaling four applications. Seven days after the first application and seven days after the last spraying, leaves were collected to evaluate chitinase, peroxidase and β-1,3-glucanase activity seven days. In vitro aqueous mushroom extracts inhibited the CFU of X. axonopodis pv. passiflorae and increase in the activity of peroxidase and β-1,3-glucanase was observed in passion fruit plants in the greenhouse.

The effect of adjustment and finishing procedure on roughness, strength, and phase transformation of monolithic zirconia.

To evaluate the effect of adjustment and finishing procedures and thermal aging of monolithic zirconia on the surface roughness, phase transformation, and flexural strength. One hundred disk-shaped monolithic zirconia specimens were randomly divided into 5 groups: control, received only glazing; group Gr, was grinded; group GrP, was grinded and polished; group GrG, was grinded and re-glazed; group GrPG, was re-glazed after grinding and polishing. Half of the each group were stored in distilled water for 24h and the remaining were thermocycled for 5000 cycles. Topographic evaluations were done with profilometer and scanning electron microscope. Phase changes were assessed through X-ray diffractometer. The biaxial flexural strength test was calculated by universal test machine. Statistical analysis was performed by using two-way ANOVA and Tukey multiple comparison test (p < 0.05). Group Gr showed statistically higher surface roughness and flexural strength values than the other groups (p < 0.001). However, no significant differences were observed between finishing groups (p >0.05). Phase transformation was occurred in all groups but the differences were not statically significant (p >0.05). Artificial aging had no effect on surface roughness, flexural strength, and phase transformation (p >0.05). Surface roughness significantly increased after grinding, but finishing procedure approximated it to the control group. Glazing after grinding decreased the flexural strength, but polishing did not. Zirconia polishing system may be an alternative to re-glazing for monolithic zirconia. Polishing is one of the most effective finishing procedures that can improve the physical properties of the material without damaging its mechanical properties.

Dry physical crosslinking of porcine corneal grafts. In vitro study

AbstractPurpose(1) To compare the effects of wet and dry crosslinking (CL) on swell‐resistance of porcine corneal grafts; (2) for grafts obtained by dry physical CL methods, to evaluate some of their surgically relevant properties.MethodsExperiment 1. The cornea was cut out of a frozen porcine eyeball with epithelium and Descemet's membrane removed. 30 such grafts were distributed into 10 groups of treatment (3 per group): five groups of wet grafts (wet control; Riboflavin/ultraviolet‐A CL at doses 5.4 and 54 J/cm2; glutaraldehyde CL at concentrations 0.1 and 1%) and five groups of air‐dried grafts (dry control; ultraviolet‐C (UVC) at doses of 5.4 and 54 J/cm2; dehydrothermal (DHT) CL at 80 and 105 °C). All grafts were immersed in distilled water for 24h, then their light transmission and swelling ratio were measured.Experiment 2. 18 grafts (6 groups: wet non‐hydrated control; wet control; dry control; UVC 54 J/cm2; DHT 105°C; DHT 105°C + UVC 54 J/cm2) were immersed in water for 24 hr, then distant visual quality at 5 m, central thickness (CT) and suture retention strength (SRS) were tested. ANOVA and post‐hoc Tukey HSD tests were used.ResultsExp. 1. There was a significant difference in water content and light transmission between all groups at 24h hydration (p &lt; 0.05, ANOVA). DHT 105°C grafts had significantly lower water content and the highest light transmission in comparison to all other groups (p &lt; 0.05 for each comparison, Tukey HSD).Exp. 2. At 24 hr hydration, DHT+UVC treated grafts allowed distinguishing optotypes 0.4–0.6 (decimal). CT varied from 600 to 1200 microns for DHT+UVC and UVC groups, respectively. Control grafts swelled up to 6000 microns in the center. SRS of all grafts was significantly higher than the strength of the Nylon 9‐0 thread (p&lt;0.05, Tukey HSD).ConclusionsDry physical CL methods allow obtaining corneal grafts with increased swell‐resistance compared to wet CL methods, while maintaining the strength sufficient for their surgical fixation.

Comparison of the Shear Bond Strength of Acid Etched and Er,Cr:YSGG Laser Irradiated IPS Empress II and Feldspathic Ceramic Surfaces to Metal Brackets: an in-Vitro Study

In this experimental study, the effects of Er,Cr:YSGG laser on the shear bond strength (SBS) of brackets bonded to two ceramic surfaces (Feldspathic and IPS Empress II) were compared to hydrofluoric (HF) acid etching. 60 ceramic discs were prepared, including two groups: Feldspathic and IPS Empress II surfaces. In each group, the following subgroups were prepared: 2W Er,Cr:YSGG laser, 2.5W Er,Cr:YSGG laser, and HF acid-etching. Ceramic primer and adhesive resin composite were applied and then light-cured to bond the ceramic cylinders to brackets. The samples were stored in distilled water for 24h and then, thermocycled. SBS testing was performed with a universal testing machine. Two-way ANOVA was used to compare SBS among subgroups (P&lt;0.05). The highest SBS was seen in feldspathic surfaces with HF preparation (14.61±3.11MPa). There was a significant difference in SBS between different surface treatments except between the laser groups of IPS Empress II. Also, feldspathic surfaces had significantly higher SBS than IPS Empress II in all groups except HF. Conventional surface treatment provides much stronger adhesion than laser regardless of the ceramic type. Er,Cr:YSGG laser is effective on the SBS of the feldspathic ceramics, but not in IPS Empress II ceramics. So, laser treatment can be recommended as a favorable setting for treating feldspathic surfaces.

Influence of Different Placement Techniques of Bulk-fill Resin Composite on Microleakage of Class II Cavity Preparation

Aim: To evaluate the microleakage at the gingival seat of the class II cavity restored with bulk-fill resin composite using different placement techniques.&#x0D; Materials and Methods: Two standardized class II cavities (MO and DO) were prepared in forty sound extracted human premolars. The cervical margin of the proximal box is located at 1 mm occlusal to the cementoenamel junction (CEJ). The prepared teeth were divided into four groups of 10 teeth each (n=20 cavities) and restored with Tetric N-Bond total-etch adhesive, followed by resin composite, Tetric N-Ceram Bulk-fill placed in four different techniques: GpI; as bulk-fill in a single increment, GpII; horizontal layering, GpIII; oblique (wedge-shaped) layering, GpIV; vertical layering. All restored teeth were stored in distilled water for 24h at 37ºC, thermocycled, and then soaked in 2% methylene blue dye for 24h. Teeth were then sectioned for microleakage evaluation using a stereomicroscope. Data were collected and statistically analyzed. Two specimens from each group were selected at random and examined under a scanning electron microscope (SEM) for marginal adaptation of restoration.&#x0D; Results: No statistically significant differences in the microleakage score were observed between the four placement techniques (P=0.610). However, bulk placement had the highest mean and median score (3.0 ±1.45&amp;4). The horizontal, oblique, and vertical techniques had lower scores than bulk placement (2.30±1.81, 2.6±1.66, 2.45±1.61) respectively.&#x0D; Conclusions: Microleakage could not be eliminated by any of the tested placement techniques. Incremental placement techniques showed a lower score of microleakage compared with the bulk placement. The horizontal layering of bulk-fill composite showed the best results in terms of the marginal seal with tooth structure.

Shear Bond Strength of a Multi-Mode Universal Adhesive Containing Hydroxy-Apatite Nanoparticles to Dentin (In vitro study)

Aim: To evaluate the effect of addition of Hydroxyl-Apatite nanoparticles to a commercial universal adhesive on sheer-bond-strength to dentin using two application modes, immediately and after thermocycling. Methods: A-commercial UA was used for bonding composite-resin to dentin and considered as control. 10% of HAp were prepared and added to the commercial UA and considered as experimental. 88-freshly extracted sound human premolar teeth were sectioned to expose mid-coronal-dentin. Samples were y divided into: control and experimental group. Each group was further divided based on the application protocol. Half of the samples were stored in distilled water for 24h at 37°C for immediate SBS testing whereas the other half was subjected to thermocycling for 20,000 cycles. SBS was measured one-day post polymerization and after thermocycling using universal testing machine. SBS values and failure modes were recorded and statistically analyzed. Results: the experimental group presented significantly lower resin-dentin SBS than the control group. Thermocycling significantly lowered SBS values for both groups. When using SE mode, the experimental group reported lower resin-dentin SBS than the control group before and after thermocyclying. When using ER mode before thermocycling, no significant difference was found between the two groups, while after thermocycling, the experimental group reported significantly higher resin-dentin SBS than the control group. For both adhesive groups, mixed failure dominated with ER mode while adhesive failure dominated with SE mode. Conclusions:Addition of HA may provide resistance to degradation and offer a potential to improve resin-dentin bond stability against thermal changes when ER protocol is applied.

Dynamic mechanical and thermal properties of clear aligners after thermoforming and aging

BackgroundBased on the role of properties of aligner materials on their efficiency, we aimed to assess their thermomechanical properties after thermoforming and simulated aging.MethodsIn this experimental study, 96 samples of polyethylene terephthalate glycol (PETG) aligners (Duran and Erkodur) were prepared and divided to three groups: control (C), after thermoforming (T), after thermoforming and aging (TA). Thermoforming was done through 3D-printed molds, and aging was exerted by 200 thermal cycles after immersion in 37°C distilled water for 24h. Flexural modulus, hardness, glass transition temperature (Tg), elastic and viscous modulus, and loss factor were evaluated. Two-way ANOVA, T-independent, and Tukey HSD tests were done for statistical analysis and significance level was set to 0.05.ResultsIn both materials, flexural modulus decreased significantly after thermoforming, 88% in Duran and 70% in Erkodur, but did not change significantly after aging. After thermoforming, hardness decreased significantly in both materials (22% in Duran and 7.6% in Erkodur). Dynamic Tg was significantly lower in T and TA in both materials. At all temperatures (25, 37, 55°C) in Duran, the elastic modulus difference was only significant between C and TA, but in Erkodur, it decreased significantly in T, and there was no significant change after aging. Viscous modulus and loss factor showed the same change patterns at all temperatures. In both materials, they increased after thermoforming, but did not change significantly after aging.ConclusionThermoforming had more prominent role than aging in diminishing of thermomechanical properties. In general, Duran had greater thermomechanical stability than Erkodur.

Influência da polimerização adicional na microdureza de compósitos diretos para uso indireto: estudo in vitro

The aim of this study was to verify the effect of additional polymerization with microwave and autoclave on the microhardness of 3 different commercial brands of composite resin compared to the ceromere. Cylindrical specimens (6mm x 3mm) were made with a split matrix divided into 10 groups of 13 bodies, with: Photoactivation (LED light on the top surface-40s; photoactivation LED + microwave (500W per 3min) immersed in 100ml distilled water and Photoactivation LED + autoclave (full cycle). The Ceromere group was activated according to the manufacturer's recommendation. The specimens went through a finishing and polishing sequence being stored with a cotton moistened in distilled water for 24h. They were taken to the microhardness meter (three dentations, 50g/15s load). The analysis of variance (ANOVA) was performed with post hoc Games Howell at a level of 5%. It was verified that the ceromere did not differ from the groups Z250 photo and microwave, but was inferior to the Z250 group with autoclave, and the microhardness of this was higher than the other groups. The Tetric group was inferior to all other groups. It was concluded that the additional polymerization methods promoted an increase of the superficial microhardness of the Z250 resin and this did not present a difference of microhardness when compared to the Ceromere

Influencia de la vibración sónica y el tipo de cemento en la fuerza de unión de los postes de fibra de vidrio después del envejecimiento

Introduction: This study evaluated the influence of sonic vibration and thermocycling on the bond strength of fiberglass posts using conventional dual-cured and self-adhesive resin cements. Material and Methods: Ninety-six single-rooted endodontically treated teeth were divided randomly into eight groups according to the cement used (dual-cured or self-adhesive resin cement), use of sonic vibration during post accommodation, and aging conditions (24h in distilled water or 5,000 thermal cycles). The fiberglass posts (White Post DC1, FGM) were cleaned with alcohol, treated with silane and cemented with dual-cured (Allcem Core, FGM) or with self-adhesive resin cement (seT, SDI). For groups in which sonic vibration was used, the posts were accommodated, and sonic vibration was applied for 10 s using a special tip placed on top of the post (Sonic Smart Device, FGM). Pull-out tests were performed after storage in distilled water for 24h at 37°C or after thermocycling (5000 cycles, at 5°C and 55°C). The results were evaluated using three-way ANOVA and Tukey’s test (α=0.05). Results: Significant differences were not observed between the bond strengths of dual-cured (87.93±41.81 N) and self-adhesive cement (82.53±41.43 N). Bond strength for the sonic vibration groups (100.36±42.35 N) was significantly higher than for groups without sonic vibration (70.13±34.90 N). There were significant differences between specimens subjected to thermocycling (98.33±39.42 N) and those stored for 24h in distilled water (72.16±39.67 N). Conclusion: It can be concluded that both sonic vibration and thermocycling significantly improved bond strength of fiberglass posts with the two evaluated resin cements.

Does Pigment Incorporation into Regular Composite Resins for Posterior Buildups Alter Their Bond Strength?

Posterior build-ups are auxiliary devices to orthodontic treatment which are made with resin-based or glass ionomer composites. Their removal requires care to protect the tooth surface, therefore, pigmented materials are preferred for a better visualization. This study proposed a pigmentation experimental technique of a regular composite resin, evaluating the microshear bond strength test (µ-SBT) of this experimental pigmented resin and comparing with a blue-colored polyacid-modified composite resin, used for posterior buildups. Forty-eight buccal and lingual surfaces of human teeth were used and randomly divided into 4 groups (n=12). The groups were divided into: C (control), regular composite resin; P, regular composite resin pigmented; UBL, Ultra Band Lok™; OB, Ortho Bite™. The composites were bonded using a matrix to obtain microcylinders and prepared for each experimental groups. The samples were then stored in distilled water for 24h at 37°C followed by a µ-SBT. The types of bond failures were evaluated using a stereoscopic magnifying glass (10×). The data were analyzed by ANOVA with Fisher post hoc and Dunnett´s test. Means of µ-SBT± standard deviation (MPa) were: C (39.98a±13.0), P (40.09a± 14.3); UBL (33.26ab±8.6); OB (28.70b±5.5). The most prevalent type of failure was adhesive (80.4%). Further, was not observed a statistically significant correlation between the bond strength values and failure patterns. The pigmentation of a commercially available resin did not alter the µ-SBT and exhibited similar adhesiveness as a polyacid-modified composite resin.

Effect of Energy Drinks on the Inorganic Composition of a Composite Resin Material

Composite resins are used in Dentistry to perform direct aesthetic restorations, and are a material whose properties can be influenced by the diet of the individual, especially in the face of the action of beverages with acid pH, such as energy drinks. The aim of this in vitro study was to evaluate the effect of two energy beverages on the chemical composition of a nanoparticulate composite resin, at two-time intervals. Filtek Z350XT (3M/ESPE) composite resin was used to produce thirty-six specimens (discs) of 6.0mm x 1.5mm dimensions. The specimens were initially immersed in distilled water for 24h at 37ºC and then randomly divided into two groups (n=18); according to the immersion time: 1 month (T1) and 3 months (T2); and in three subgroups (n=6) referring to immersion solutions: distilled water (control) and two energy beverages (RedBull and Monster). The inorganic composition of the specimens was measured by a spectrometry. The data were submitted to two-way ANOVA and Tukey tests. The main inorganic elements of this restorative material were respectively: zirconium (Zr), silicon (Si) and calcium (Ca), which reduced its percentage after immersion time. RedBull was the most active solution, promoting losses of the mineral Si after 1 month of immersion, of Zr, after 3 months, and of Ca after 1 month and after 3 months. Monster influenced losses only in Si, after 1 month. Distilled water did not induce significant losses. Thus, the two energy beverages reduced the inorganic percentage of the nanoparticulate composite resin evaluated in this research.

Theoretical prediction of dental composites yield stress and flexural modulus based on filler volume ratio

ObjectiveA costly advantageous approach in composites development process is to limit experimental tests by predicting mechanical properties with respect to their filler ratio. Models exist for other fields than dentistry. They have been compared to 3-point bending test experimental results for yield stress, flexural modulus and flexural strength. MethodsFive formulations of the same experimental material were made. They were composed of an organic matrix and different ratios of silanated barium glass particles. The samples were stored in distilled water for 24h at 37°C prior to the 3-point bending test. The Turcsányi model for yield stress was notably investigated, and SEM was used to complete data analysis. ResultsThe yield stress showed reproducible results and a good fit with Turcsányi model with respect to filler ratio. The flexural modulus data are not scattered but did not fit with the existing models. No trend could emerge for flexural strength and strain because of scattering; these properties are more unpredictable. The SEM observations of fracture areas confirm a good matrix-filler interface quality. SignificanceSEM pictures validated the numerical parameter obtained from Turcsányi model. The latter therefore seems to be applicable to dental composites. Firstly, it enables to predict the evolution of the material yield stress without testing all filler ratios. Secondly, this model provides a good way to get micro-information on the matrix-filler interface from macroscopic tests. The discrepancy between flexural modulus results and theory highlighted the necessity to include an “interface quality” parameter in accurate predictive models.

Evaluation of the Effect of Household Cleansers on the Color Change of Two Types of Permanent Soft Liners: An In Vitro Study

Many patients use household cleaners to clean denture which can cause discoloration and damage soft liners. The purpose of this study was to evaluate the effect of household cleansers on the color change of two types of permanent soft liners. Methods: In this interventional study, 80 permanent silicone soft liners, including 40 heat-cured liners (Molloplast-B, Detax Gmbh & Co. KG, Ettlingen, Germany) and 40 self-cure liners (Mucopren soft, Kettenbach GmbH & Co. KG, Eschenburg, Germany) were made in brass molds with dimensions of 15×2 mm in accordance with the manufacturer's instructions. The samples were immersed in distilled water for 24h and the initial color was determined using a colorimeter. Then, each group (n=10) was immersed for 8h daily in 2.5% vinegar, 2.5% hypochlorite, 2.5% hand washing liquid, and distilled water (control). Color measurements were performed after 7 and 30 days of immersion in solutions and data were analyzed using ANOVA, independent t-test, and Tukey's post hoc tests. Results: In distilled water, hypochlorite, and vinegar, the mean color change after one month was significantly lower in Molloplast-B than Mucopren (P=0.042, P<0.001, P=0.002); however, in Hand washing, the difference was not significant (P=0.780). Conclusion: The mean color change in Mucopren in all cleansers was higher than Molloplast-B, and the highest change in color was observed in both liners in hypochlorite.

Effect of a self-etching primer containing 4-META and sodium sulfite after phosphoric acid etching on bonding strength of MMA-TBB resin to human enamel

PurposeThe aim of this study was to evaluate the shear bond strength and durability of MMA-TBB resin to human enamel applied a self-etching primer with phosphoric acid etching. MethodsA self-etching primer (Teeth primer, TP) containing 4-methacryloyloxyethyl trimellitate anhydride (4-META) and sodium sulfite and two etchants having different phosphoric acid concentrations (K-etchant gel, KE, 35–45%: Red gel, RG, 20–25%) were used as treatment agent, and MMA-TBB resin was used as luting agent. Enamel surfaces were treated with six methods which were as follow: KE, RG, TP, KE+TP, and RG+TP. After enamel specimens were bonded with MMA-TBB resin and stored in distilled water for 24h, the shear bond strength test was done at 0 thermocycling or 20,000 thermocycling. These results were statistically verified with Steel-Dwass multiple comparisons and Man–Whitney U test. ResultsThe shear bond strength of TP group, KE+TP group, and RG+TP group were significantly higher than KE group and RG group in pre-thermocycling. KE+TP group and RG+TP group were significantly higher than other groups in post-thermocycling. ConclusionsApplying TP with phosphoric acid etching can increased shear bond durability despite difference of phosphoric acid concentrations (35–45% or 20–25%).

Influence of glass-ceramic coating on composite zirconia bonding and its characterization

The aims of this study were to compare micro-tensile bond strength and characterize the bond of ceramic-coated versus air-abraded and chemically treated zirconia specimens. Eight zirconia blocks were fabricated and assigned to two groups as follows: AA-alumina air-abrasion; and CC-DCMhotbond coating followed by alumina air-abrasion and hydrofluoric acid etching. For each group, two identically pre-treated zirconia blocks were applied G-Multi Primer, cemented together with G-Cem Linkforce cement and cut into 30 stick-shaped specimens (1×1×9mm3). A total of 120 specimens were stored in distilled water for 24h and then assigned to three groups: (i) short-term test, (ii) thermocycling for 5000, and (iii) thermocycling for 10,000 cycles. The specimens were tested in tensile mode. The bond strength results were analyzed using two-way ANOVA, followed by one-way ANOVA and Dunnett T3 (α=0.05). Failure mode and surfaces were analyzed with optical microscopy and SEM. The EDS, FTIR, XRD, and FIB-SEM were used for chemical, crystalline phase analyses. The AA groups recorded higher mean bond strength than the CC groups in all aging conditions. Thermocycling did not affect the bond strength of the AA groups, whereas the bond strength of the CC groups decreased significantly after aging. The MDP monomer and silane in G-Multi Primer chemically reacted with mechanically pre-treated AA and CC surfaces via the absorption of P-O and Si-O groups. The bond strength of a conventional protocol involving alumina air-abrasion was greater than ceramic coating technique.

Effect of self-etch adhesives on the internal adaptation of composite restoration: a CP-OCT Study.

Despite improvements in dental adhesive materials, internal adaptation remains a challenge in bonded restorations. The aim of this study was to compare microgaps and internal floor adaptation between two different self-etch adhesives in class-V cavities using cross-polarization optical coherence tomography (CP-OCT). In this in vitro study, standardized round class-V cavities were prepared in 20 non-carious human upper central incisor teeth. They were randomly divided into two groups, TN and SE, with each group receiving a different dental adhesive. In TN group, the adhesive used was all-in-one Tetric N-Bond Self-Etch (TN; Ivoclar/Vivadent, Liechtenstein), while SE group was bonded with two-step self-etch Clearfil SE Bond 2 adhesive (SE; Kuraray Noritake Dental Inc, Japan). The prepared cavities were restored with flowable composite and then stored in distilled water for 24h. Next, they were immersed in silver nitrate, followed by immersion in a photo-developing solution. Optical comparison was carried out by CP-OCT to assess microgaps and composite adaptation at the cavity floor. A Mann-Whitney test was applied to the data, which showed a statistically significant difference in composite adaptation among the two groups (p < 0.001) with the SE group showing superior adaptation. CP-OCT is a reliable tool for non-invasive imaging that gives an insight into composite performance. Better adaptation was found with the two-step self-adhesive for the composite used in this study.