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Purpose: To compare fracture strength, failure mode, and chairside time of Class IV fractures restored with CEREC (Chairside Economic Restorations of Esthetic Ceramics) technology or direct composite. Methods: Forty-eight fractured anterior bovine teeth were randomly assigned to three experimental groups (indirect restoration) with margin designs including: A) butt joint, B) short chamfer (one mm), and C) long chamfer (two mm) and a control group (direct composite). Preparations were scanned; restorations were milled from zirconia-reinforced lithium-silicate blocks and cemented. Fracture load (N) and failure mode were analyzed. Techniques were timed from start of margin preparation through finishing. Results were analyzed using one-way analysis of variance or the Kruskal-Wallis test (significance level: P=0.05). Results: Fracture loads (mean±standard deviation) for groups A, B, and C and control group were 2,177±644 N, 2,183±507 N, 2,666±609 N, and 2,358±886 N, respectively (not significantly different; P=0.26). The direct composite was significantly different from all indirect groups (P<0.01) for failure mode. Chairside time was longer for direct restoration. Conclusions: Fracture strength is similar for directly and indirectly fabricated Class IV restorations, with margin design not affecting strength or failure mode. Practitioner's chairside time, but not total time, is reduced when using indirect methods. [ABSTRACT FROM AUTHOR]

Purpose: This study's purpose was to test the hypothesis that, after glass ionomer (Gl) sealant debonding, remaining Gl in the deepest parts of fissures and/or the inhibition of enamel demoralization after artificial caries challenge imparts the residual cariostatic property observed in clinical studies. Methods: Fuji IX Gl sealant was placed on one tooth from 14 matched pairs of noncarious extracted human permanent molars and premolars; the other tooth was the control. Sealed teeth underwent thermocycling (4,000 cycles), and the sealant was manually debonded. The amount of remaining sealant in the fissures was determined using a stereomicroscope. All teeth were placed in lactic acid gel (pH 5.0) at 37 degrees Celsius for three weeks to simulate caries formation. The extent of demineralizotion was determined using the serial micro-hardness method on the cross-sectioned specimens at 0.5 mm from the depth of the central fissure. Results: All teeth had Gl retained in the fissures at a microscopic level. Enamel deminerolization adjacent to the remaining Gl was not significantly different from the control (t test; P=.88). Conclusions: The residual cariostatic property of gloss ionomer sealant is most likely due to a physical barrier of remaining Gl in the fissures rather than a chemical effect on demineralization inhibition. [ABSTRACT FROM AUTHOR]

Purpose: Evaluate cuspal flexure caused by polymerization shrinkage stress, bond integrity, and depth-of-cure of bulk-fill composites. Methods: Twenty-eight extracted permanent molars were mounted in stainless steel rings. Slot-shaped Class II mesio-ocdusal-distal preparations (four mm deep) were restored with Filtek Supreme Ultra (control; two two-mm increments) and bulk-fill composites (Tetric EvoCeram, Venus, Filtek Bulk Fill). The teeth were digitized using a 3D scanner before and after restoration. Before- and after-restoration scons were aligned, and cuspal flexure was calculated. Bond integrity along occlusal interfaces was assessed by dye penetration and measured after overnight immersion in basic fuchsin dye and cross-sectioning. Depth-of-cure was determined on the cross-sections using Vickers hardness. Statistical analysis was performed with one-way analysis of variance. Results: All composites caused inward cuspal flexure (10.4 to 13.6 µm). No statistical difference in flexure was found among the composites (P=.07). No significant difference in microhardness at any restoration depths was found for any composite (.35

Purpose: This study's purpose was to evaluate microleakage of two types of glass ionomer (Gl) and composite restorations with saliva contamination at different stages of restorative procedures. Methods: Extracted teeth with Class V cavities were restored with a conventional Gl, nanofilled RMGI, or total-etched composite. The preparations were contaminated with saliva before the adhesive/primer application or before the restoration placement (n=10). The restored teeth were thermocyded (1000X), stained (basic fuchsin), and sectioned. Microleakage distance was measured and subjected to analysis of variance and Duncan's post-hoc test (P=.05). Results: For the enamel margin, no significant difference was found between the conventional Gl and composite restoration, with or without saliva contamination (P>.05). The nanofilled RMGI with contamination before restoration had the highest microleakage. For the cementum margin, composite had significantly more microleakage than both types of Gl restorations, regardless of saliva contamination. Conclusions: Conventional and resin-modified glass ionomer restorations had less cementum microleakage, while the composite had less enamel microleakage. Saliva contamination did not affect microleakage of the conventional Gl at either enamel or cementum margins. The nanofilled RMGI system was not sensitive to saliva contamination at the gingival margin, but had increased microleakage at the enamel margin, especially after the primer application. [ABSTRACT FROM AUTHOR]

Tooth erosion from an acidic insult may be exacerbated by toothbrushing. The purposes of this study were to develop an in vitro methodology to measure enamel loss after brushing immediately following an acidic episode and to investigate the effect of brushing with an anti-erosive toothpaste. The null hypotheses tested were that tooth erosion after brushing with the toothpaste would not be different from brushing with water and that a 1-hour delay before brushing would not reduce tooth erosion. Forty bovine enamel slabs were embedded, polished, and subjected to baseline profilometry. Specimens were bathed in hydrochloric acid for 10 minutes to simulate stomach acid exposure before post-acid profilometry. Toothbrushing was then simulated with a cross-brushing machine and followed by postbrushing profilometry. Group 1 was brushed with water; group 2 was brushed with a 50:50 toothpaste-water slurry; and groups 3 and 4 were immersed in artificial saliva for 1 hour before brushing with water or the toothpaste slurry, respectively. The depth of enamel loss was analyzed and compared using 1-way analysis of variance and post hoc testing (α = 0.05). Greater enamel loss was measured in groups brushed with toothpaste than in groups brushed with water. One-hour immersion in artificial saliva significantly reduced enamel loss when teeth were brushed with water (group 3; P < 0.05) but not with toothpaste (group 4). This study established a protocol for measuring enamel loss resulting from erosion followed by toothbrush abrasion. The results confirmed the abrasive action of toothpaste on acid-softened enamel., Competing Interests: Disclosure: Drs Dehghan and Tantbirojn are inventors on a pending patent application, "Methods and composition for preventing and treating tooth erosion" (WO2014134463 A1; February 28, 2014). Other coauthors have no financial, economic, commercial, or professional interests related to topics presented in this article.

Purpose: To investigate intrapulpal temperature rise in a primary molar during light activation of a composite restoration to determine if clinically significant pulpal temperatures (greater than 5.5 degrees Celsius) were reached., Methods: Restorative composites (EsthetX HD, Filtek Supreme Ultra, Filtek Bulk Fill) were placed into a primary molar with occlusal preparation (1.5 mm depth; remaining pulpal floor thickness one mm). The pulp was extirpated through a root access to place a thermocouple against the pulpal roof. Temperature changes were recorded during composite restoration light polymerization with three curing lights (one quartz-tungsten-halogen, two LEDs). Sample size was 10. Samples received additional irradiation to assure complete polymerization, followed by a third irradiation for calculating the exothermic heat contribution (subtracting third irradiation temperatures from first irradiation temperatures). Cured restorations were removed after each test, and the tooth was reused. Results were analyzed with Kruskal-Wallis (α =0.05)., Results: Type of curing light and composite material affected the intrapulpal temperature rise, which was up to five degrees Celsius for one combination of LED-composite., Conclusions: Clinicians should be aware of the potential for clinically significant intrapulpal temperature rises when light-activating composite restorations in a primary molar with a moderately deep cavity.

Marginal integrity is important for the longevity of a restoration. An increase in the marginal discrepancy after cementation contributes adversely to the longevity of a restoration. In the past, the preferred method to overcome this discrepancy was to create internal space for the cement by using a number of coats of a die-spacing material. In the digital age, however, this method is no longer the only option. Currently, an amount of die spacer is engineered into the computer program and forms part of the milling process. The present study attempted to identify the optimal setting of the Spacer parameter that a) is necessary for the complete cementation of a Cerec milled all-ceramic crown, and b) does not compromise the strength of the crown postcementation.

Purpose: Evaluate cuspal flexure caused by polymerization shrinkage stress, bond integrity, and depth-of-cure of bulk-fill composites., Methods: Twenty-eight extracted permanent molars were mounted in stainless steel rings. Slot-shaped Class II mesio-occlusal-distal preparations (four mm deep) were restored with Filtek Supreme Ultra (control; two two-mm increments) and bulk-fill composites (Tetric EvoCeram, Venus, Filtek Bulk Fill). The teeth were digitized using a 3D scanner before and after restoration. Before- and after-restoration scans were aligned, and cuspal flexure was calculated. Bond integrity along occlusal interfaces was assessed by dye penetration and measured after overnight immersion in basic fuchsin dye and cross-sectioning. Depth-of-cure was determined on the cross-sections using Vickers hardness. Statistical analysis was performed with one-way analysis of variance., Results: All composites caused inward cuspal flexure (10.4 to 13.6 μm). No statistical difference in flexure was found among the composites (P=.07). No significant difference in microhardness at any restoration depths was found for any composite (.35

Purpose: To compare both quantitatively and qualitatively, the efficacy of dielectrophoresis to diffusion on the uptake of fluoride by enamel., Methods: A 1.23% APF gel was applied to 16 bovine incisor specimens for 20 minutes by dielectrophoresis or diffusion. Absorption and penetration were evaluated by wavelength dispersive spectrometry., Results: Fluoride concentrations in the diffusion group were significantly higher than baseline readings at 10 and 20 microm depths; fluoride concentration in dielectrophoretically treated teeth was significantly higher than the diffusion group at 10, 20, and 50 microm (ANOVA/Student-Newman-Keuls post hoc, P = 0.05). Significantly higher fluoride uptake was found with dielectrophoresis compared to passive diffusion at 10, 20, and 50 microm depths (paired t-test, P = 0.05). Dielectrophoresis doubled fluoride uptake in the superficial layers compared to passive diffusion, and drove the fluoride significantly deeper with an uptake six times higher than diffusion at 50 microm depth. Dielectrophoresis enhanced penetration and increased uptake of fluoride on average by 600% at 50 microm. The amount of fluoride delivered at 50 microm was equivalent to long-term exposure of prophylactic fluoride. With proper polarizing frequencies, dielectrophoresis could enhance fluoride delivery into tooth enamel at higher penetration depths and concentrations than diffusion.