To compare the 1-year clinical performance of lithium disilicate and resin composite CAD/CAM onlay restorations. Twenty patients that required two restorations in posterior teeth, with at least one cusp to be covered, received two onlays. One was made with IPS e.max CAD (Ivoclar-Vivadent) and the other with Lava Ultimate (3M Oral Care). Two blind observers evaluated the restorations at baseline and 1 year after the onlays were cemented, according to FDI criteria. At each recall, digital photographs, bite-wing radiographs and impressions of the restorations were taken for SEM evaluation of the interface. Results were analyzed by Mann–Whitney U and Wilcoxon tests (p < 0.05). At baseline and in the 1-year recall, both CAD/CAM materials exhibited excellent results in most criteria with similar esthetic, functional and biological properties (p > 0.05). However, deterioration in surface lustre (p = 0.020) and color match/translucency (p = 0.039) were detected for IPS e.max CAD onlays after 1-year. Under SEM evaluation, there were no statistically differences in micromorphological criteria at baseline nor after a year between IPS e.max CAD and Lava Ultimate onlays. Conclusion: After 1 year of clinical service IPS e.max CAD and Lava Ultimate onlays showed a similar clinical performance that needs to be confirmed in long-term evaluations.
The microhardness of self-adhesive, dual-cure resin cements, when used to lute fiber posts, depends on the material brand, with higher values of microhardness verified at the coronal third. Because changes in microhardness were detected between 24 hours and 7 days after luting, clinicians should take this into account to prevent damage to the biomechanical bonding of the post cement-dentin immediately following cementation. SUMMARYPurpose: To compare the microhardness of several dual-cure, self-adhesive resin cements used to lute fiber posts at 24 hours and seven days after cementation.Methods: Bovine incisors were selected to lute 15 fiber posts that were 12 mm long (FRC Postec Plus size 3, Ivoclar-Vivadent). Five resin cements were tested: Multilink Automix (Ivoclar-Vivadent), without light-curing, and the self-adhesive resin cements Maxcem Elite (Kerr), RelyX Unicem (3M ESPE), G-Cem (GC), and Smartcem 2 (Dentsply), which were lightcured for 40 seconds (LED Bluephase, IvoclarVivadent). Each root was embedded in chemically cured acrylic resin and stored at 378C for 24 hours. The roots were transversally sectioned into nine specimens that were each 1 mm thick, with three specimens corresponding to each root third. Indentations (100g, 30 seconds) were performed on each section in the resin cement, at 24 hours and seven days after cementation, using a Vickers digital microdurometer (Buehler). Data were analyzed by two-way analysis of variance, Stu-
The aim of the present study was to evaluate the effect of 0.1% chitosan (Ch) solution as an additional primer on the mechanical durability and enzymatic activity on dentine using an etch-and-rinse (E&R) adhesive and a universal self-etch (SE) adhesive. Microtensile bond strength and interfacial nanoleakage expression of the bonded interfaces for all adhesives (with or without pretreatment with 0.1% Ch solution for 1 min and air-dried for 5 s) were analyzed immediately and after 10,000 thermocycles. Zymograms of protein extracts from human dentine powder incubated with Optibond FL and Scotchbond Universal on untreated or Ch-treated dentine were obtained to examine dentine matrix metalloproteinase (MMP) activities. The use of 0.1% Ch solution as an additional primer in conjunction with the E&R or SE adhesive did not appear to have influenced the immediate bond strength (T0) or bond strength after thermocycling (T1). Zymography showed a reduction in MMP activities only for mineralized and demineralized dentine powder after the application of Ch. Application of 0.1% Ch solution does not increase the longevity of resin–dentine bonds. Nonetheless, the procedure appears to be proficient in reducing dentine MMP activities within groups without adhesive treatments. Further studies are required to comprehend the cross-linking of Ch with dentine collagen.
The aim of the present study was to assess whether different dentin conditioning protocols with different acids [phosphoric acid, ethylene diamine tetra acetic acid (EDTA), and polyacrylic acid (PAA)] influence the bond strength of fiber posts along the radicular depth when luted with self-adhesive resin cement. Twenty single-rooted teeth were randomly divided into four experimental groups (n = 5) according to dentin treatment: Group 1: no treatment; Group 2: etching with 35 % phosphoric acid for 10 s; Group 3: 17 % EDTA application for 60 s; and Group 4: conditioning with 25 % PAA for 30 s. RelyX Fiber Posts were luted with the self-adhesive resin cement RelyX Unicem 2 Automix (3M ESPE). Roots were transversally sectioned into nine 1-mm thick specimens, three corresponding to each root third and a push-out test was performed. Data were analyzed by two-way ANOVA and Tukey test (p < 0.05). Failure mode was determined and specimens with representative failures for each group were observed under scanning electron microscopy. According to the results, dentin treatment influenced the bond strength (p < 0.001), whereas the root third did not (p > 0.05). Fiber posts luted after treating dentin with phosphoric acid, and PAA exhibited the highest push-out bond strength values, while the lowest were obtained after EDTA application. Intermediate results were obtained when dentin was not conditioned. In conclusion, the bond strength of the self-adhesive resin cement RelyX Unicem 2 improves when root dentin is treated with 35 % phosphoric acid or 25 % PAA, before fiber posts luting irrespective of the root depth.
Background: The aim of this study was to compare the shear bond strength (SBS) of a flash-free and precoated orthodontic adhesive with a compomer orthodontic adhesive before and after thermocycling. The adhesive remnant index (ARI) was also determined for both adhesives. Material and Methods: A total of 120 human premolars were randomly divided into two groups (n=60) according to the orthodontic adhesive used: APC Flash-Free Adhesive Coated Appliance System (APC FF) or Transbond PLUS Color Change Adhesive (TP), as control. Then three subgroups were established according to the aging procedure: water storage (37ºC, 24h), thermocycling for 10,000, or 20,000 cycles. A SBS test was performed and ARI value for each specimen was also assessed. Results were analyzed by two-way ANOVA and Tukey's Chi-square test (p < 0.05). Results: SBS values were significantly influenced by thermocycling (p < 0.01). Neither the orthodontic adhesive nor the interaction between adhesive and thermocycling statistically affected SBS results (p > 0.05). Conclusions: APC FF and TP showed similar bond strength results. Thermocycling induced a significant decrease in SBS values for the two adhesives tested, without differences between 10,000 and 20,000 thermal cycles. Moreover, APC FF left less adhesive remnants on the enamel compared to TP.
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