Fabio Zovico Maxnuck Soares

Chlorhexidine does not increase immediate bond strength of etch-and-rinse adhesive to caries-affected dentin of primary and permanent teeth

The aim of this study was to evaluate the effect of 2% chlorhexidine digluconate (CHX) on immediate bond strength of etch-and-rinse adhesive to sound (SD) and caries-affected (CAD) primary dentin compared with permanent dentin. Flat dentin surfaces from 20 primary molars (Pri) and 20 permanent molars (Perm) were assigned to 8 experimental groups (n=5) according to tooth type (Pri or Perm), dentin condition (SD or CAD - pH-cycling for 14 days) and treatment (control - C or 60 s application of 2% CHX solution after acid etching - CHX). The bonding system (Adper Single Bond 2) was applied according to manufacturers instructions followed by resin composite application (Filtek Z250). After 24 h water storage, specimens with cross-section area of 0.8 mm² were prepared for being tested under microtensile test (1 mm/min). Data were submitted to ANOVA and Tukeys post hoc test (α=0.05). Failure mode was evaluated using a stereomicroscope at ×400. Treatment with CHX did not result in higher bond strength values than no pre-treatment (C groups), independently of tooth type. Primary teeth and caries-affected dentin showed significantly lower (p<0.05) bond strength means compared with permanent teeth and sound dentin, respectively. Predominance of adhesive/mixed failure was observed for all groups. CHX did not influence the immediate bond strength to sound or caries-affected dentin of primary and permanent teeth.

Does air particle abrasion affect the flexural strength and phase transformation of Y-TZP? A systematic review and meta-analysis

OBJECTIVES A systematic review was conducted to assess the effects of air-particle abrasion procedures on the mechanical strength and phase transformation of yttria-stabilized tetragonal zirconia polycrystal (Y-TZP). DATA This report followed the PRISMA Statement. From 1013 eligible studies, 78 were selected for full-text analysis, from which 37 were excluded. The 41 remaining papers were included for the systematic review; hand-searching yielded three papers. The review comprised a total of 44 studies; 21 were included in the meta-analysis. SOURCES Searches were performed with no publication year limit through November 2015 in PubMed/MEDLINE, Web of Science (Core Collection) and Scopus databases. STUDY SELECTION In vitro studies evaluating the effect of air-particle abrasion protocols on the mechanical strength and/or phase transformation of Y-TZP zirconia specimens, immediately or after aging. For the meta-analysis, flexural strength data of air-particle abrasion vs. control (nonabraded) were globally and subgroup analyzed. Subgroup analyses assessed blasting parameters (particle size, pressure, or time duration) and the effect of aging. Statistical analyses were conducted using RevMan 5.1 (Cochrane Collaboration, Copenhagen, Denmark). Comparisons were performed with random-effect models at a 5% significance level. Phase transformation data were included only in the systematic review, as insufficient data were available for meta-analysis. CONCLUSIONS Airborne-particle abrasion improved flexural strength of Y-TZP, regardless of abrasion parameters and the presence or lack of aging (p≤0.05). Phase transformation tended to be increased by air abrasion immediately or with up to 2h of aging. However, after aging for 12h or more, the abraded Y-TZP showed less monoclinic content than the control.

Degradation of resin-dentin bonds of etch-and-rinse adhesive system to primary and permanent teeth

The aim of this in vitro study was to compare the degradation of resin-dentin bonds of an etch-and-rinse adhesive system to primary and permanent teeth. Flat superficial coronal dentin surfaces from 5 primary second molars and 5 permanent third molars were etched with phosphoric acid and bonded with an adhesive system (Adper Single Bond 2, 3M ESPE). Blocks of resin composite (Z250, 3M ESPE) were built up and the teeth sectioned to produce bonded sticks with a 0.8 mm² cross-sectional area. The sticks of each tooth were randomly divided and assigned to be subjected to microtensile testing immediately (24 h) or after aging by water storage (6 months). Data were analyzed by two-way repeated measures ANOVA and Tukey post hoc test (α = 0.05). Failure mode was evaluated using a stereomicroscope (400×). Microtensile values significantly decreased after the 6 months aging, independent of the dentin substrate. In 24 h, the values obtained to primary dentin were lower compared with permanent dentin. This difference was not maintained after aging. Adhesive/mixed failure was predominant in all experimental groups. In conclusion, degradation of resin-dentin bonds of the etch-and-rinse adhesive system occurred after 6 months of water storage; however, the reduction in bond strength values was higher for permanent teeth.

Erosive effects of beverages in the presence or absence of caries simulation by acidogenic challenge on human primary enamel: an in vitro study

AIM: To evaluate in vitro the erosive effects of beverages in the presence or absence of caries simulation (acidogenic challenge) on the microhardness of primary enamel. METHODS: Forty human primary teeth were submitted to the erosive effects: 3×20-min-long daily immersion in fresh orange juice (orange group), strawberry yogurt drink (yog group), or cola soft drink (cola group) separately or in combination with acidogenic challenge (pH cycling for 10 days). Specimens were also submitted to acidogenic challenge alone, and in the negative control group specimens were not submitted to any treatment. Mineral loss was evaluated by cross-sectional microhardness determination. The data (Knoop hardness numbers, KHN) were subjected to 2-way analysis of variance and Tukey’s post hoc test (α = 0.05%). RESULTS: All the test beverages significantly reduced the sample cross-sectional enamel hardness (KHN ± SD, 235.93 ± 18.15, 257.23 ± 21.79, and 253.23 ± 13.86 in the orange, yog, and cola groups, espectively) compared to samples in the negative control group (290.27 ± 3.92). In vitro acidogenic challenge exacerbated the mineral loss induced by all beverages (166.02 ± 4.28,190.43 ± 17.55, and 198.39 ± 21.39 in the orange, yog, and cola groups combined to acidogenic challenge, respectively) compared to acidogenic challenge alone. CONCLUSIONS: All beverages exhibited erosive effects on primary enamel. Simulated caries challenge considerably exacerbated the enamel softening of primary teeth.

Effect of Two Microshear Test Devices on Bond Strength and Fracture Pattern in Primary Teeth

This in vitro study evaluated the influence of two devices for application of shear load in microshear tests on bond strength and fracture pattern of primary enamel and dentin. Eighty primary molars were selected and flat enamel (40 teeth sectioned mesio-distally) and dentin (40 teeth sectioned transversally) surfaces were obtained. Both surfaces were polished to standardize the smear layer. Two-step etch-and-rinse adhesive systems (Adper Single Bond and XP Bond) were used. Polyethylene tubes was placed over the bonded surfaces and filled with composite resin. The microshear testing was performed after storage in water (24 h/37 °C) using two devices for application of microshear loads: a notched rod (Bisco Shear Bond Tester) or a knife edge (Kratos Industrial Equipment). Failure modes were evaluated using a stereomicroscope. Bond strength data were subjected to ANOVA and chi-square test to compare the failure mode distributions (α=0.05). No significant differences were observed between the groups for dentin and enamel bond strength or fracture patterns (p>0.05). The predominant failure mode was adhesive/mixed. In conclusion, the devices for application of shear loads did not influence the bond strength values, regardless of adhesive system and substrate.

Is there a best conventional material for restoring posterior primary teeth? A network meta-analysis

This study aimed to compare the longevity of different conventional restorative materials placed in posterior primary teeth. This systematic review was conducted following the PRISMA statement and registered in PROSPERO (CRD42016035775). A comprehensive electronic search without date or language restrictions was performed in PubMed/MEDLINE, Cochrane Central Register of Controlled Trials, Scopus, Turning Research Into Practice (TRIP) and Clinical Trials databases up to January 2017, selecting randomized clinical trials that assessed the longevity of at least two different conventional restorative materials performed in primary molars. Seventeen studies were included in this systematic review. Pairwise and network meta-analyses were performed and relative risks and 95% confidence intervals (CI) calculated. Two reviewers independently selected the studies, extracted the data, and assessed the risk of bias. Restorations of primary molars with conventional glass ionomer cement showed increased risk of failure than compomer, resin-modified glass ionomer cement, amalgam, and composite resin. Risk of bias was low in most studies (45.38% of all items across studies). Pediatric dentists should avoid conventional glass ionomer cement for restoring primary molars.

The Thickness of the Adhesive Layer Increases the Misdiagnosing of the Radiolucent Zones and Restoration Replacement Indication

OBJECTIVE To evaluate the influence of the thickness of the adhesive layer and demineralized dentin on the decision to replace composite restoration. MATERIALS AND METHODS Eighty human third molars with occlusal preparations (Class I) were randomly assigned to eight groups (n = 10): adhesive system (Clearfil SE Bond [CSE] or Scotchbond Universal Adhesive [SBU]); the number of adhesive layers (one or two); and substrate (sound or demineralized dentin). A blinded examiner evaluated radiographs of each restored tooth. Obtained scores for the presence or absence of radiolucent zone under restoration were submitted to a relative risk (RR) calculus and Z-test, and the scores for the decision to replace restorations were submitted to Fishers exact test (p < 0.05). RESULTS The relative risk of identifying a radiolucent zone under restoration in sound and demineralized dentin were, respectively, 2 and 1.85 times higher when two layers of adhesive were applied. Demineralized dentin did not increase the probability of identifying a radiolucent zone. A higher relative (1.6, p = 0.01) was observed when two layers of SBU were applied. The number of layers did not influence the relative risk for CSE (RR = 1.3, p = 0.13). CONCLUSION Thicker layers of SBU increase the relative risk of identifying a radiolucent layer under restoration and the decision to replace a/composite restoration, irrespective of the substrate. The presence of demineralized dentin did not increase the probability of identifying a radiolucent zone when compared to sound dentin. CLINICAL SIGNIFICANCE The results of this in vitro study suggest that thicker layers of a particular adhesive under resin composite restorations can negatively influence the decision to replace them. (J Esthet Restor Dent 29:193-200, 2017).

The impact of artificially caries-affected dentin on bond strength of multi-mode adhesives

Aim: The aim of this study is to evaluate the impact of dentin condition on bond strength of multi-mode adhesive systems (MMAS) to sound and artificially induced caries-affected dentin (CAD). Methods: Flat dentin surfaces of 112 bovine incisors were assigned to 16 subgroups (n = 7) according to the substrate condition (sound and CAD– pH-cycling for 14 days); adhesive systems (Scotchbond Universal, All-Bond Universal, Prime and Bond Elect, Adper Single Bond Plus and Clearfil SE Bond) and etching strategy (etch-and-rinse and self-etch). All systems were applied according to the manufacturers instructions, and resin composite restorations were built. After 24 h of water storage, specimens were sectioned (0.8 mm2) and submitted to the microtensile test. Statistical Analysis: Data (MPa) were analyzed using three-way analysis of variance and Tukeys test (α = 0.05). Results: MMAS presented similar bond strength values, regardless etching strategy in each substrate condition. Bond strength values were lower when MMAS were applied to CAD in the etch-and-rinse strategy. Conclusion: The etching strategy did not influence the bond strength of MMAS to sound or CAD, considering each substrate separately. However, CAD impact negatively on bond strength of MMAS in etch-and rinse mode.

Does Bonding Approach Influence the Bond Strength of Universal Adhesive to Dentin of Primary Teeth

OBJECTIVE To evaluate the effect of bonding strategy on microtensile bond strength (μTBS) of a new universal adhesive system to primary tooth dentin. STUDY DESIGN Flat dentin surfaces from 25 primary molars were assigned to 5 groups according to the adhesive and bonding approach: Adper Single Bond 2 (two-step etch-and-rinse adhesive) and Clearfil SE Bond (two-step self-etch system), as controls; Scotchbond Universal Adhesive-self-etch, dry or wet-bonding etch-and-rinse strategies. Composite buildups were constructed and the teeth were sectioned to obtain bonded sticks (0.8 mm2) to be tested under tension at 1mm/min. The μTBS means were analyzed by one-way ANOVA and Tukeys tests (α = 0.05). Failure mode was evaluated using a stereomicroscope (400×). RESULTS Universal adhesive applied following both dry and wet-bonding etch-and-rinse strategies showed similar bond strength compared with control adhesive systems. Self-etch approach resulted in the lowest μTBS values. For all groups, adhesive/mixed failure prevailed. The percentage of premature debonded specimens was higher when the universal adhesive was used as self-etch mode. CONCLUSION The universal adhesive does not share the same versatility of being used in the etch-and-rinse and self-etch approaches; however, the use of the new adhesive following either wet or dry-bonding may be a suitable option as alternative to two-step etch-and-rinse adhesive protocol.

Do adhesive systems influence the color match of resin composites

Background This in vitro study evaluated the influence of adhesive systems on the color match of a resin composite with different translucencies. Methods Sixty disk-shaped specimens were made with A2 and opaque A2 (OA2) shades of nanohybrid resin composite Z250 XT. Specimens of each shade (n = 30) were randomly reassigned to 3 subgroups according to adhesive system: a 2-step etch-and-rinse adhesive (Adper Single Bond Plus), a 2-step self-etch system (Clearfil SE Bond) and a universal adhesive (Scotchbond Universal Adhesive). The bonding agents were applied to resin composite specimens following the manufacturers’ recommendations. Additionally, 5 disk samples of each adhesive system were prepared. Colorimetric evaluation (CIE L*a*b* system) was performed immediately after polishing the sample and application of the adhesive systems. Color changes (ΔE and ΔE00) were calculated between 2 measurements. Color coordinates L*, a* and b* of the adhesive disks were also assessed. The data obtained were analyzed using ANOVA and Tukeys post hoc test (α = 0.05). Results The application of Scotchbond Universal Adhesive to the resin composite A2 shade resulted in the highest color change (p<0.01; ΔE = 3.1 ± 0.7 and ΔE00 = 1.8 ± 0.4). However, no significant difference was observed among adhesive systems when applied to the resin composite OA2 shade (p>0.05). Scotchbond Universal Adhesive revealed augmented yellowing and greening in comparison with other experimental groups. Conclusions The universal adhesive tested resulted in higher visually perceptible color changes when using a more translucent resin composite shade, but this was clinically acceptable.