Short-term aging and the dentin bond strength of adhesive systems.

The aim of this study was to compare the effects of 2 aging methods on the dentin bond strength of different adhesive systems, including a universal adhesive. Seventy-two third molars were sectioned to create flat midcoronal dentin surfaces, which were randomly assigned to 12 groups (n = 6 each) according to the aging method (conventional aging, defined as 6 months of water storage; accelerated aging by means of a pH-cycling method; or negative control [immediate bond strength]) and adhesive system (Adper Single Bond 2, Clearfil SE Bond, Prime & Bond 2.1, or Scotchbond Universal). Composite resin blocks were constructed on the flattened dentin surfaces after application of the appropriate adhesive, and the specimens were stored in water for 24 hours. Specimens from the control group were immediately sectioned into resin-dentin sticks (0.8 mm2) and subjected to a microtensile bond strength test. Specimens from the experimental groups were sectioned and tested after undergoing the assigned aging method. Data were analyzed with 2-way analysis of variance and a Tukey test (α = 0.05). The study findings showed that neither aging method significantly affected the dentin bond strength (P = 0.917). Of the 4 adhesives, Adper Single Bond 2 had the highest bond strength value after aging (P < 0.001). Scotchbond Universal adhesive demonstrated statistically significantly higher bond strength values than Clearfil SE Bond and Prime & Bond 2.1, which had statistically similar values. Adhesive failures at the resin-dentin interface or adhesive failures mixed with cohesive failure of the adjacent substrate predominated in all groups. The 2 aging processes did not result in degradation of the adhesive interface or jeopardize the dentin bond strength of any of the adhesives tested.

Can Endodontic Irrigating Solutions Influence the Bond Strength of Adhesives to Coronal Dental Substrates? A Systematic Review and Meta-Analysis of In Vitro Studies.

PURPOSE: To systematically review the literature to analyze the influence of endodontic irrigating solutions on the bond strength of adhesives to coronal enamel or dentin. MATERIALS AND METHODS: The PubMed/MEDLINE, Web of Science and Scopus electronic databases were used to select laboratory studies related to the research question, without publication year or language limits. From 2461 potentially eligible studies, 2451 were selected for full-text analysis, and 97 were included in the systematic review. Two authors independently selected the studies, extracted the data, and assessed the risk of bias. Pooling bond strength data were calculated using RevMan5.1 with random effects model (α = 0.05), comparing control (no endodontic irrigating solution) and experimental groups (one or more endodontic solutions). RESULTS: No significant difference was found between the control and experimental groups (p = 0.12) in the overall meta-analysis and in the meta-analysis excluding chlorhexidine (p = 0.06). High heterogeneity was found in the meta-analyses. Most included studies in the systematic review were scored as having a high risk of bias. CONCLUSION: The different endodontic irrigating solutions evaluated showed no negative influence on the bond strength of dental adhesives to coronal dental substrates.

Phosphoric Acid Containing Chlorhexidine Compromises Bonding of Universal Adhesive.

PURPOSE: To examine the influence of phosphoric acid containing chlorhexidine on the dentin bond stability of a universal and a 2-step etch-and-rinse adhesive. MATERIALS AND METHODS: Eighty sound bovine incisors were randomly assigned to 8 groups (n = 10) according to: phosphoric acid (37% phosphoric acid [CTR] or 37% phosphoric acid with 2% chlorhexidine [CHX]); adhesive (Scotchbond Universal Adhesive [SBU]or Adper Single Bond 2 [SB2]); and water storage time (24 h and 6 months). Both acids and adhesives were applied to flat dentin surfaces (following manufacturer's instructions) upon which composite cylinders were built up (0.72 mm2). After storage in distilled water at 37°C for 24 h or 6 months, the composite cylinders were submitted to microshear bond strength (µSBS) testing. Bond strength data (MPa) were analyzed using three-way ANOVA and post-hoc Tukey's test (α = 5%). RESULTS: The interaction among factors was significant (p = 0.012). Both adhesives showed similar 24-h bond strengths regardless of the phosphoric acid. After 6 months, similar values were found for both materials when control phosphoric acid was used, but CHX phosphoric acid produced statistically significantly lower bond strengths for SBU. SB2 bond strength was not affected by acid type. CONCLUSION: Phosphoric acid containing chlorhexidine induced premature bond strength degradation of Scotchbond Universal Adhesive.

Is Adhesive Bond Strength Similar in Primary and Permanent Teeth? A Systematic Review and Meta-analysis.

PURPOSE: To systematically review the literature on laboratory studies to determine whether the bond strength of adhesives to primary teeth is similar to that to permanent teeth. MATERIALS AND METHODS: This systematic review was conducted according to PRISMA and registered in PROSPERO (CRD42014015160). A comprehensive literature search was conducted considering in vitro studies published up to June 2015 in the PubMed/MEDLINE database, with no limit on year of publication. Two reviewers independently selected papers, extracted data and assessed the risk of bias. From 422 eligible studies, 42 were fully analyzed. Thirty-seven studies were ultimately included in the systematic review and meta-analysis. A global comparison was performed with a random-effects model at a significance level of p < 0.05, expressed by the difference of means between the groups. The mean bond strengths and standard deviations were tabulated and statistical analyses were conducted in RevMan 5.1 (The Cochrane Collaboration). RESULTS: There was a significant difference between groups, with permanent teeth presenting higher bond strength than primary teeth (p = 0.0005). When the enamel and dentin substrates were considered separately, dentin presented the same trend (p = 0.002), while for enamel there was no significant difference between the dentitions (p = 0.11). The majority of the studies had a high bias risk. CONCLUSION: Adhesives have higher bond strengths when applied to permanent than to primary teeth. This difference was also valid when the comparison was made between permanent and primary dentin.

Performance of resin composite restorations in the primary dentition: a retrospective university-based study.

BACKGROUND: Limited data is available on variables influencing the survival of composite restorations in primary teeth. AIM: This retrospective university-based study assessed the survival and risk factors associated with failures of resin composite restorations performed in primary teeth. DESIGN: The sample was composed of 961 restorations from records of 337 patients (178 girls and 159 boys) attended in a university dental clinic. The restorations' longevity up to 48 months of follow-up was assessed using the Kaplan-Meier survival test. Multivariate Cox regression analysis with shared frailty was used to evaluate the factors associated with failures (P < 0.05). RESULTS: Mean survival time was 41.5 months (95% CI: 39.7-43.3), with 70.6% of the restorations surviving after 48 months of evaluation. The overall annual failure rate up to 48 months follow-up was 8.3%. Restorations placed in lower arch had lower survival rate than those in upper arch (HR: 1.82, 95% CI: 1.02-3.28). Restorations involving two or more surfaces had more risk of failure than restorations placed in cavities involving only one surface (HR: 2.55 95% CI: 1.34- 4.83). Girls had less risk of failure in their restorations (HR: 0.43, 95% CI: 0.19-0.96). CONCLUSION: Individual and dental variables such as gender, arch type and number of restored surfaces were associated with failure of composite restorations performed in children under daily life clinical environment.

Can Coloured Fluoride Gel Stain Demineralised Enamel?

PURPOSE: This study evaluated the colour changes of demineralized enamel after treatment with coloured fluoride gel. MATERIALS AND METHODS: Enamel blocks obtained from bovine incisors were submitted to artificial caries induction by pH cycling followed by fluoride gel applications (2% sodium fluoride, pH 6.8) using a colourless gel (control group), pink or blue gels. The enamel optical properties were evaluated by spectrophotometry, using the CIE L*a*b* system at baseline (sound enamel), after artificial caries induction (demineralised enamel) and after each of the five fluoride gel applications (weekly intervals). Changes in enamel optical properties (ΔE) were analysed by two-way ANOVA and Tukey's test (α = 0.05). RESULTS: No significant differences were found among fluoride gels (p = 0.476) regardless of the presence of pigments in the gel. ΔE values were significantly different (p < 0.001) between baseline evaluation and treated enamel (after fluoride gel application). CONCLUSION: This in vitro study demonstrated that colour changes in enamel do not occur during fluoride gel treatment, regardless of the presence or absence of coloured pigments in the gel.

The Bonding Performance of a Universal Adhesive to Artificially-created Caries-affected Dentin.

PURPOSE: To evaluate the bonding performance of a universal adhesive to sound and artificially-created caries-affected dentin, using either the etch-and-rinse or self-etch strategy. MATERIALS AND METHODS: Flat midcoronal dentin surfaces from 48 third molars were randomly assigned to eight groups according to the substrate (sound dentin and artificially-created caries-affected dentin [pH cycling for 14 days]) and the adhesive or application mode (Scotchbond Universal: self-etch or etch-and-rinse strategies; Adper Single Bond 2 and Clearfil SE Bond, a two-step etch-and-rinse adhesive and a two-step self-etch adhesive as controls, respectively). Then, composite blocks were constructed, the specimens were further stored in water for 24 h, and composite-dentin sticks were prepared (0.8 mm2) and tested under tension at 1.0 mm/min. Data were analyzed with two-way ANOVA and Tukey's test (α = 0.05). RESULTS: All adhesives tested on artificially-created caries-affected dentin presented similar µTBS (p > 0.05), and inferior bonding performance when compared to sound dentin (p = 0.000). On sound dentin, Scotchbond Universal presented higher bond strengths when applied in the etch-and-rinse than self-etch mode, but comparable bond strength in each application mode in relation to the respective control adhesive (p = 0.04). CONCLUSION: Scotchbond Universal can be used in different application modes when bonded to artificially-created caries-affected dentin; however, the etch-and-rinse strategy improves its bonding ability to sound dentin. Moreover, Adper Single Bond 2 and Clearfil SE Bond presented similar bond strengths, regardless of the dentin condition and comparable performance in relation to each strategy of Scotchbond Universal.

Role of Etching Mode on Bonding Longevity of a Universal Adhesive to Eroded Dentin.

PURPOSE: To assess the immediate and six-month microshear bond strength (µSBS) of a universal adhesive applied using different etching strategies on sound and eroded dentin. MATERIALS AND METHODS: Eighty bovine incisors were polished to obtain flat buccal dentin. Forty teeth were submitted to a pH-cycling model to simulate artificial erosion (3x/day cola drink for 7 days). Teeth from both dentin conditions (sound and eroded) were randomly assigned to four groups according to the adhesive and etching approach: a universal adhesive in self-etch and etch-and-rinse modes (Scotchbond Universal Adhesive), and as controls a two-step etch-and-rinse adhesive (Adper Single Bond Plus), and a two-step self-etch adhesive (Clearfil SE Bond). Four composite restorations (Z250) were built up on each dentin surface, using the area delimitation technique. Half of the specimens were evaluated in the µSBS test after 24 h of water storage, and the other half were evaluated six months later. Data (MPa) were analyzed with three-way repeated measures ANOVA and Tukey's post-hoc tests (α = 0.05). RESULTS: The µSBS values of all adhesives significantly decreased after six months of aging (p = 0.01). Lower µSBS values were obtained in eroded dentin (p = 0.04). The universal adhesive showed similar µSBS to the self-etch adhesive used as control, irrespective of the etching strategy. However, Scotchbond Universal Adhesive applied in self-etch mode performed better than the control etch-and-rinse adhesive (p = 0.02). CONCLUSION: The universal adhesive does not provide the same bonding efficacy on eroded dentin as on sound dentin, and its performance does not depend on the etching mode.

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 Fisher's 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).

Endodontic Irrigation Protocols: Effects on Bonding of Adhesive Systems to Coronal Enamel and Dentin.

OBJECTIVE:  To evaluate the influence of endodontic irrigation protocols on bond strength of total-etch and self-etch adhesive systems to coronal enamel and dentin. MATERIALS AND METHODS:  A total of 66 coronal slices from 11 permanent molars were assigned to six groups (n = 11): endodontic irrigation protocols (5% sodium hypochlorite + 17% EDTA; 2% chlorhexidine gel + saline solution + 17% EDTA or no solution - control) and adhesive systems (Adper Single Bond 2 or Clearfil SE Bond). Dental slices were exposed to endodontic irrigation protocols for 30-minute prior to the application of the adhesive systems. Starch tubes were placed over the enamel and the dentin surfaces of each slice (2-4 tubes in each substrate) and filled with Filtek Z350 XT (3M ESPE) to build the microshear bond strength (µSBS) specimens (0.72 mm2 sectional area). After 24 hours of water storage (37°C), µSBS test was performed. Bond strength data (MPa) were analyzed by two-way ANOVA, separately for enamel and dentin (α = 0.05). RESULTS:  µSBS means were not influenced by endodontic irrigation protocols in enamel (p = 0.12) nor dentin (p = 0.49). Clearfil SE Bond system presented higher µSBS values than Adper Single Bond 2 both on enamel (p = 0.024) and dentin (p = 0.005). CONCLUSION:  Endodontic irrigation protocols (5% sodium hypochlorite or 2% chlorhexidine gel + saline solution combined with 17% EDTA) do not jeopardize the bond strength of adhesive systems to coronal enamel and dentin. CLINICAL SIGNIFICANCE: The results of this in vitro study suggest that endodontic irrigation protocols do not impair on bonding effectiveness of adhesive systems to coronal enamel and dentin. (J Esthet Restor Dent 29:222-228, 2017).

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 Tukey's 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.

Selective Acid Etching Improves the Bond Strength of Universal Adhesive to Sound and Demineralized Enamel of Primary Teeth.

PURPOSE: To evaluate the influence of enamel condition and etching strategy on bond strength of a universal adhesive in primary teeth. MATERIALS AND METHODS: Thirty-six primary molars were randomly assigned to six groups (n = 6) according to the enamel condition (sound [S] and demineralized [DEM]/cariogenic challenge by pH cycling prior to restorative procedures) and adhesive system (Scotchbond Universal Adhesive [SBU]) used in either etch-and-rinse (ER) or selfetching (SE) mode, with Clearfil SE Bond as the self-etching control. The adhesives were applied to flat enamel surfaces and composite cylinders (0.72 mm2) were built up. After 24-h storage in water, specimens were subjected to the microshear test. Bond strength (MPa) data were analyzed using two-way ANOVA and Tukey's post-hoc tests (α = 0.05). RESULTS: Significant differences were found considering the factors adhesive system (p = 0.003) and enamel condition (p = 0.001). Demineralized enamel negatively affected the bond strength, with µSBS values approximately 50% lower than those obtained for sound enamel. SBU performed better in etch-and-rinse mode, and the bond strength found for SBU applied in self-etching mode was similar to that of CSE. CONCLUSIONS: Enamel etching with phosphoric acid improves the bond strength of a universal adhesive system to primary enamel. Demineralized primary enamel results in lower bond strength.

Is There a Best Protocol to Optimize Bond Strength of a Universal Adhesive to Artificially Induced Caries-affected Primary or Permanent Dentin?

PURPOSE: To evaluate whether the etch-and-rinse or self-etching mode of a universal adhesive is the best protocol to optimize bond strength to primary and permanent artificially-induced caries-affected dentin. MATERIALS AND METHODS: Flat midcoronal dentin surfaces were exposed in 24 primary and 24 permanent molars and submitted to pH cycling for 14 days to induce artificial caries-affected dentin. For each tooth type (primary and permanent), the teeth were randomly assigned to 4 different groups according to the adhesive systems and bonding strategy: a universal adhesive, Scotchbond Universal Adhesive, in self-etching and etch-and-rinse modes; a twostep etch-and-rinse adhesive, Adper Single Bond 2 (control); and two-step self-etching system, Clearfil SE Bond (control). After bonding and restorative procedures, specimens were sectioned to obtain rectangular sticks (0.8 mm2) that were submitted to microtensile tests (crosshead speed: 1 mm/min). The data were analyzed using two-way ANOVA (α = 0.05). RESULTS: The universal adhesive showed bond strengths similar to those of the control groups, irrespective of the bonding strategy. Likewise, statistically similar bonding performance was observed for all adhesives to either artificially- induced caries-affected primary or permanent dentin. CONCLUSION: The new universal adhesive, Scotchbond Universal Adhesive, can be used in both application modes in artificially-induced caries-affected primary and permanent dentin, as the bond strength was not influenced by the different substrates or application mode.

Dry-bonding Etch-and-Rinse Strategy Improves Bond Longevity of a Universal Adhesive to Sound and Artificially-induced Caries-affected Primary Dentin.

PURPOSE: To evaluate the effect of the etching strategy on the immediate and 1-year microtensile bond strength (µTBS) and structural reliability of a universal adhesive to sound and artificially-induced caries-affected dentin of primary teeth. MATERIALS AND METHODS: Flat midcoronal dentin surfaces were exposed in 50 primary molars, which were then randomly assigned to 10 groups according to substrate (sound dentin [SD] and artificially-induced caries-affected dentin [CAD] with pH cycling for 14 days) and etching approach using Scotchbond Universal Adhesive (self-etching or dry or wet-bonding etch-and-rinse strategies) with Adper Single Bond Plus (two-step etch-and-rinse adhesive) and Clearfil SE Bond (two-step self-etching system) as controls. Composite buildups were constructed and sectioned to obtain bonded sticks (0.8 mm2) to be subjected to microtensile testing immediately or after 1 year of water aging. Data were analyzed using three-way repeated measures ANOVA and Tukey's test (α = 0.05). Weibull modulus and characteristic strength were also determined. RESULTS: A decrease in bond strength was observed after 1 year of water aging, except when the universal adhesive was used in the dry-bonding etch-and-rinse and self-etching approaches. However, the self-etching approach resulted in lower µTBS values in SD, while no difference among experimental groups was observed in CAD. Overall, higher Weibull modulus values were achieved in the groups with higher bond strength. The relationship between characteristic strength and bond strengths was not linear for all groups. CONCLUSION: The bond longevity of the universal adhesive using the dry-bonding etch-and-rinse approach on sound and artificially-induced caries-affected primary dentin was better than the other bonding agents and approaches tested.

Tribochemical Glass Ceramic Coating as a New Approach for Resin Adhesion to Zirconia.

PURPOSE: To investigate the effects of a novel tribochemical silica coating technique with powders made from feldspathic ceramic and leucite-based ceramic on the bond strength of zirconia to resin cement before and after aging. MATERIALS AND METHODS: Zirconia blocks were divided into 3 groups according to the material used for airborne-particle abrasion: 1) SP (control): silica-coated alumina particles; 2) FP: feldspathic ceramic powder; 3) LP: leucite glass-ceramic powder. After silanization, composite resin cylinders were cemented on the zirconia surface using a dual-curing resin cement. Prior to the shear bond strength (SBS) test, half of the samples (n = 15) were stored in distilled water for 24 h; the other half (n = 15) were submitted to aging (10,000 thermocycles of 5°C to 55°C; 150 days of water storage). The bond strength data were analyzed using two-way ANOVA and Tukey's test (α = 0.05). Scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS), and x-ray diffraction analysis were performed. RESULTS: The initial bond strengths did not differ significantly between the groups (p = 0.053). However, after aging procedures, airborne-particle abrasion with feldspathic ceramic powder (FP) resulted in higher values of bond strength (p = 0.0001). SEM and EDS indicated that all the treatments promoted silica deposition on the Y-TZP surface ceramic. Airborne-particle abrasion with FP and LP induced a lower percentage of the monoclinic phase. CONCLUSION: Airborne abrasion with fine feldspathic ceramic particles is a novel tribochemical technique and appears to be suitable for improving the bond strength between zirconia and resin cements.

Doxycycline as a matrix metalloproteinase inhibitor to prevent bond degradation: the effect of acid and neutral solutions on dentin bond strength.

The aim of this in vitro study was to evaluate the pH effect of doxycycline solutions on the immediate dentin bond strength of a total-etch adhesive system. Twenty human molars were divided into 4 groups (n = 5) after acid etching according to surface treatment: 10% acidic doxycycline, 10% neutral doxycycline, 2% chlorhexidine, and control. Composite resin blocks were made and subjected to microtensile testing. Mean bond strength values were submitted to a 1-way analysis of variance and a Tukey test (α = 0.05). No statistically significant differences between the experimental groups were found (P = 0.093). The chlorhexidine group showed the highest number of pretesting failures. The application of either acidic or neutral doxycycline solution prior to the dentin adhesive did not influence the bond strength of the total-etch adhesive system evaluated.

Bonding Performance of a Multimode Adhesive to Artificially-induced Caries-affected Primary Dentin.

PURPOSE: To investigate the bonding of a new universal adhesive applied using different etching strategies on sound and caries-affected dentin of primary teeth. MATERIALS AND METHODS: Flat dentin surfaces from 50 primary molars were randomly assigned to 10 groups according to substrate (sound dentin [SD] vs caries-affected dentin [CAD] pH cycled for 14 days) and bonding approach (Scotchbond Universal Adhesive: self-etching, vs dry or wet-bonding etch-and-rinse strategies; Adper Single Bond Plus [two-step etch-and-rinse adhesive] and Clearfil SE Bond [two-step self-etching system] as controls). After 24 h of water storage, bonded sticks with cross-sectional areas of 0.8 mm2 were tested for microtensile bond strength (µTBS). Two sticks from each tooth were immersed in silver nitrate solution in order to evaluate nanoleakage (NL) with SEM. The µTBS means were analyzed using two-way ANOVA and Tukey's tests. For NL, the Kruskal-Wallis and Mann-Whitney tests were used (α = 0.05). RESULTS: The influence of the etching strategy on the bonding performance of the universal adhesive was substrate dependent. The self-etching approach resulted in lower µTBS values and higher silver nitrate uptake into hybrid layers for Scotchbond Universal Adhesive on SD, while no difference among experimental groups was observed in CAD. CONCLUSION: It is preferable to use the universal adhesive following either a dry- or wet-bonding etch-and-rinse approach on both sound and caries-affected primary dentin.

Effect of prolonged air drying on the bond strength of adhesive systems to dentin.

This in vitro study evaluated the effect of air-drying time on degree of solvent evaporation (DE), dentin microtensile bond strength (µTBS), and degree of conversion (DC) of 5 adhesive systems: Adper Single Bond 2, XP Bond, Prime & Bond 2.1, OptiBond Solo, and Adper Easy One. For DE testing, 20 µL of each material was submitted to measurements in a digital balance after an air stream of 3, 5, 10, 20, 30, or 60 seconds; the weight loss was computed and converted to a percentage (DE). For µTBS testing, 50 sound human molars were divided into groups (n = 5). The 5 adhesive systems were applied either in accordance with manufacturers' instructions for solvent drying time (control) or with a prolonged drying time (20-30 seconds). After composite resin was built up on the hybridized surfaces, the teeth were stored for 24 hours and then sectioned to obtain beams that were loaded until fracture. For DC testing, specimens of each adhesive and air-drying condition (n = 3) were evaluated by means of attenuated total reflectance Fourier transform infrared spectroscopy. Data were submitted to 2-way analysis of variance, t test, and Spearman test for correlation analysis. Prolonged air drying resulted in significantly greater DE than did the time suggested by the manufacturers. The adhesives XP Bond and Adper Easy One showed significantly greater µTBS with prolonged air drying. The DC was not affected by air-drying time. No statistically significant correlation was found between DC and µTBS values. Depending on the material, bond strength can be improved by prolonged air-drying times.

Is It Possible to induce Artificial Caries-affected Dentin using the Same Protocol to Primary and Permanent Teeth?

AIM: This in vitro study compared the mineral loss of natural and artificially-created caries-affected dentin in primary and permanent teeth using the same protocol to induce caries lesions. MATERIALS AND METHODS: Twenty molars presenting natural occlusal dentin caries lesions (10 primary-PriC and 10 perma-nent-PermC; control group), and 20 sound molars (10 primary -PripH and 10 permanent-PermpH; experimental group), were selected. Occlusal cavities were prepared in teeth of the experimental group that were submitted to pH-cycling for 14 days to simulate caries-affected dentin. All specimens were longitudinally sectioned and prepared in order to obtain Knoop micro-hardness values from 15 to 250 urn depth, starting in bottom of center of natural lesions or cavities. The microhardness (KHN) data were submitted to three-way repeated measures analysis of variance (ANOVA) and Tukey's tests (α = 0.05). RESULTS: Considering all depths, there was no statistically significant differences (p > 0.05) between the mineral loss of the control (PriC = 30.9 ± 6.4 and PermC = 40.8 ± 8.6) and experimental (PripH = 27.3 ± 11.1 and PermpH = 35.5 ± 14.0) groups, neither between primary and permanent teeth. CONCLUSION: The mineral loss of the artificially-created caries-affected dentin is similar to that from naturally developed dentin caries lesions. CLINICAL SIGNIFICANCE: The pH-cycling model may be a suitable method to simulate caries-affected dentin in both permanent and primary teeth.

Effect of cariogenic challenge on bond strength of adhesive systems to sound and demineralized primary and permanent enamel.

PURPOSE: To evaluate the effect of cariogenic challenge on the bond strength of adhesive systems to sound and artificially demineralized enamel of primary and permanent teeth. MATERIALS AND METHODS: Eighty molars (40 primary, 40 permanent) were randomly assigned to 16 groups (n = 5) according to the type of tooth (primary [PRIM] or permanent [PERM]), enamel condition (sound [S] or demineralized [DEM]), treatment after the restorative procedure (control [C] or cariogenic challenge [pH]), and adhesive system (Adper Single Bond [SB] or Clearfil SE Bond [SE]). Teeth from the DEM group were subjected to cariogenic challenge by pH cycling prior to restorative procedures and pH group specimens were subjected to cariogenic challenge before the microshear test. One of two adhesive systems was applied to the flat enamel surfaces and composite cylinders (0.45 mm2) were built. The microshear bond test was performed. The data (MPa) were subjected to ANOVA and Tukey's test (α = 0.05). RESULTS: No statistically significant differences were detected between the adhesive systems. The S groups exhibited higher bond strength values than the DEM groups, as did C groups compared to pH groups. PERM groups also had higher bond strength values than PRIM groups, excluding PRIM S and PERM S, which had similar values. CONCLUSION: The bond strength to demineralized enamel of primary teeth was lower than to the demineralized enamel of permanent teeth. Cariogenic challenge negatively influenced enamel bond strength, regardless of the type of tooth and adhesive system.