Comparative bonding performance of coronal dentin disks and CAD/CAM resin composite disks for biological restoration: The impact of resin-coating technique.

This study evaluated the bonding performance of coronal dentin disks, designed for biological restoration, and CAD/CAM resin composite disks when bonded to flat dentin surfaces using dual-cure resin cements, with and without a resin-coating (RC) technique. Three distinct groups were established within the non-RC group, each using one of the two types of resin cements in a self-adhesive mode: one-step self-etch adhesive (1-SEA) without light-cure, 1-SEA with light-cure, and a separate group using an alternate cement. Within the RC group, a subgroup was established for each cement. The microtensile bond strength (µTBS) of the disk-dentin beam was tested after 0 and 10,000 thermocycles in a 5°C/55°C. No significant µTBS difference was observed among the non-RC groups. However, when using RC, the µTBSs of coronal dentin disks significantly exceeded those of CAD/CAM resin composite disks. Thermocycle aging did not affect µTBS in any of the bonding methods, except in self-adhesive mode.

Digitally Guided Direct Composite Injection Technique with a Bi-layer Clear Mini-Index for the Management of Extensive Occlusal Caries in a Pediatric Patient: A Case Report.

PURPOSE: This case report presents a direct composite inverse injection technique using a bi-layer clear mini-index fabricated with a digital workflow to restore extensive posterior occlusal cavities in a 13-year-old patient. MATERIALS AND METHODS: After a root canal treatment in the right mandibular first molar and step-wise excavation of deep caries in the left mandibular first molar, the extensive occlusal restorations were digitally designed using CAD software, upon which digital wax-ups were 3D-printed. Bi-layer clear mini-indices consisting of a hard outer plastic layer and an elastic inner silicone layer were prepared from the 3D-printed cast. The bonding surfaces were deproteinized using a 6% sodium hypochlorite solution, and an antioxidant (Clearfil DC Activator; Kuraray Noritake) was utilized to improve the dentin bonding durability of a 2-step self-etch adhesive (Clearfil SE Bond 2; Kuraray Noritake). Subsequently, a highly filled universal-shade flowable resin composite (RC) was incrementally placed into the cavities. To create the final occlusal morphology, the same RC was inversely injected through the opening of the bi-layer indices. RESULTS: The workflow was feasible, and the occlusal cavities were efficiently restored using the injection technique. Occlusal carving and adjustments of the morphology were not necessary, leading to less chair time. At the 1-year follow-up, the clinical outcome was excellent. CONCLUSION: The injection technique with a bi-layer clear mini-index accurately translated the digital wax-ups into large, final restorations. Precise morphology and shortened chair time enhanced patient satisfaction, but at the expense of multiple visits.

Application of Sulfinate Agent in Conjunction with HOCl Smear-Layer Deproteinization Improves Dentin Bonding Durability of One-step Self-etch Adhesives.

PURPOSE: To evaluate the effect of a sulfinate agent on the bonding durability of one-step self-etch adhesives (1-SEAs) to smear-layer-covered dentin deproteinized with hypochlorous acid (HOCl). MATERIALS AND METHODS: Human coronal dentin disks with a standardized smear layer were deproteinized with 100 ppm HOCl solution for 0 s (control), 15 s or 30 s. After rinsing with water for 30 s and air drying, half of the specimens were treated with a sulfinate agent (Scotchbond Universal Dual Cure Activator; SDA) prior to the application of a 1-SEA (Bond Force II [Tokuyama Dental] or Clearfil Universal Bond Quick [Kuraray Noritake]). Microtensile bond strength (µTBS) was measured after 24 h or 10,000 thermal cycles (TC). The data were analyzed by three-way ANOVA with Tukey's post-hoc tests and t-tests at the 0.05 significance level. RESULTS: The 24-h µTBS of both adhesives increased statistically significantly with the HOCl pretreatment for 15 s or 30 s (p < 0.05), but it was not statistically significantly affected by the application of SDA (p > 0.05). However, after TC, the groups treated with the combination of HOCl and SDA maintained their µTBS (p > 0.05), as opposed to untreated dentin and dentin treated with either HOCl or SDA, whose µTBS decreased significantly (p < 0.05). CONCLUSION: The application of the sulfinate agent did not statistically significantly affect the immediate bond strength of 1-SEAs, and it could not prevent a significant decrease in the bond strength to untreated dentin after thermocycling. However, the sulfinate agent significantly improved the bonding durability of 1-SEAs to HOCl smear-layer deproteinized dentin.

Additive effects of touch-activated polymerization and extended irradiation time on bonding of light-activated adhesives to root canal dentin.

STATEMENT OF PROBLEM: The bonding of light-activated adhesives to root canal dentin with an additional touch-polymerization activator has been insufficiently examined. PURPOSE: The purpose of this in vitro study was to investigate the effect of touch-polymerization activators and extended light-irradiation time on the microtensile bond strength (µTBS) of light-activated adhesives. MATERIAL AND METHODS: Post cavities were prepared in 50 extracted mandibular premolars and bonded using Prime&Bond Universal (PBU); PBU+Self Cure Activator (SCA); Clearfil SE Bond 2 (SEB); SEB+Clearfil DC Activator (DCA); or Clearfil Universal Bond Quick ER (UBQ). After light-irradiation for 10 or 20 seconds, the post cavities were filled with dual-activated resin core materials. Eight beams were prepared per specimen and subjected to the µTBS test. The µTBS data were analyzed by using 3-way ANOVAs with the Bonferroni correction (α=.05). RESULTS: The 3-way ANOVAs indicated that the use of touch-polymerization activators (SCA and DCA) significantly increased the µTBS of PBU and SEB in both the coronal (P=.015) and apical (P=.001) regions. The extension of light-irradiation time to 20 seconds significantly improved their µTBS in the apical region (P<.001), but not in the coronal region (P=.09). Light-irradiation for 20 seconds increased the µTBS of UBQ significantly in the coronal region (P=.014). CONCLUSIONS: Touch-polymerization activators improved the bond strength of light-activated adhesives to root canal dentin, especially when combined with an extended light-irradiation time.

Sodium p-Toluenesulfinate Enhances the Bonding Durability of Universal Adhesives on Deproteinized Eroded Dentin.

The effects of deproteinization using sodium hypochlorite (NaOCl) and the subsequent application of an antioxidant (sodium p-toluenesulfinate, STS) onto the bonding durability of universal adhesives on eroded dentin were investigated. Untreated sound dentin served as the control, whereas eroded dentin, which had been prepared by pH-cycling in 1% citric acid and a remineralization solution, was either untreated, deproteinized with a 10% NaOCl gel or deproteinized with the 10% NaOCl gel and subsequently treated with an STS-containing agent. The dentin surfaces were bonded using a universal adhesive (Clearfil Universal Bond Quick, Scotchbond Universal or G-Premio Bond), and the micro-tensile bond strength (µTBS) test was performed after 24 h or 10,000 thermal cycles. The µTBS data were statistically analyzed using a three-way ANOVA and Tukey's HSD post hoc tests. The lowest µTBS was measured on untreated eroded dentin (p < 0.001). Deproteinization of eroded dentin resulted in µTBS similar to untreated sound dentin (p > 0.05), but the highest µTBS was obtained if deproteinization was followed by the application of STS. Thermocycling significantly decreased µTBS in all groups (p < 0.001), except for STS-treated deproteinized eroded dentin (p > 0.05). This indicated that deproteinization, followed by the application of STS, could enhance the bonding durability of universal adhesives on eroded dentin.

Air-blowing strategies for improving the microtensile bond strength of one-step self-etch adhesives to root canal dentin.

The effect of different air-blowing strategies using a prototype of a newly developed clinically applicable warm air-blowing device on the microtensile bond strength (µTBS) of one-step self-etch adhesives (1-SEAs) to human root-canal dentin was evaluated. Post cavities (8 mm depth, 1.5 mm diameter) were prepared and bonded with four 1-SEAs. Air-blowing was performed using normal air (23±1°C) for 10 or 20 s; warm air (60±1°C) for 10 or 20 s; or their combination for 10 s (5 s normal, 5 s warm) or 20 s (10 s normal, 10 s warm). After filling with corresponding core materials and 24-h water storage, µTBS test was performed. For three of the 1-SEAs, combined air-blowing for 20 s significantly increased µTBS compared to other air-blowing strategies (p<0.05). This suggests that the combination of normal and warm air-blowing for 20 s can enhance solvent evaporation from 1-SEAs, thus resulting in their improved bonding performance to root-canal dentin.