Effect of Simulated Dental Pulpal Pressure Using Fetal Bovine Serum for the Bonding Performance of Contemporary Adhesive to Dentin.

This study evaluated the effect of simulated pulpal pressure (SPP) conditions and storage time on contemporary adhesive systems' microtensile bond strength (µTBS) to dentin. Extracted human molars were prepared and randomly divided into four groups according to the adhesives: Clearfil Megabond 2 (CSE), Beautibond Xtreme Universal (BXU), G2-Bond (G2B), and Scotchbond Universal Plus (SBP). Each adhesive group was further divided following the SPP conditions: control with no simulation (SPP-CTR), SPP with distilled water (SPP-DTW), and SPP with fetal bovine serum (SPP-FBS). Resin composite build-ups were prepared, and teeth were stored in water (37 °C) for 24 h (24 h) and 3 months (3 m). Then, teeth were sectioned to obtain resin-dentin bonded beams and tested to determine the µTBS. Data were analyzed using three-way ANOVA, Tukey post hoc tests (=0.05), and Weibull failure analysis. Failure mode was observed using scanning electron microscopy. The µTBS response was affected by adhesive systems, simulated pulpal pressure conditions, and storage time. SPP-CTR groups presented a higher overall bond strength than SPP-DTW and SPP-FBS, which were not significantly different from each other. Only for SBP, the SPP-FBS group showed higher µTBS than the SPP-DTW group. The Weibull analysis showed that the bonding reliability and durability under SPP-DTW and SPP-FBS were inferior to SPP-CTR, and the 24 h bonding quality of adhesives to dentin was superior to that of 3 m. SPP drastically reduced the µTBS of all adhesives to dentin regardless of solution (distilled water or fetal bovine serum). Storage after 3 m also decreased µTBS despite the SPP condition.

Appropriate Immediate Dentin Sealing to Improve the Bonding of CAD/CAM Ceramic Crown Restorations.

This study aimed to use quantitative and qualitative evaluations based on micro-tensile bond strength (µTBS) to clarify the appropriate immediate dentin sealing (IDS) approach for improving the bonding of CAD/CAM ceramic crown restorations. Forty-eight extracted human molars were prepared to obtain standardized abutment specimens and divided into three groups: no IDS (group C: control), IDS performed by a single application of an all-in-one adhesive system (group A), and IDS performed by the combined application of an adhesive system and a flowable resin composite (group F). All specimens were restored with a ceramic crown fabricated by a chair-side CAD/CAM system and were divided into no-stress and stressed groups. After cyclic loading (78.5 N; total, 3 × 105 cycles; 90 cycles/min) on the specimens in the stressed group, all specimens were sectioned. The µTBS values for the occlusal and mesioaxial walls were measured (n = 16) and analyzed statistically. The quantitative bonding performance of groups A and F were superior to that of group C, regardless of the cyclic loading and abutment wall conditions. Group F showed the maximum bond strength and the highest bond durability in the qualitative bonding performance even under the cyclic loading condition simulating clinical mastication.

Bonding States of In Vitro Class 2 Direct Resin Composite Restoration Applied by Various Incremental Techniques.

Incremental techniques are always required for clinical cases of deep and/or large cavities restored with resin composite materials. The purpose of this study was to examine the bonding states of class 2 direct resin composite restoration applied by various incremental techniques after cyclic loading to simulate the intra-oral environment to define the appropriate technique. Three types of resin composites, namely, bulk-fill (B), flowable (F), and conventional resin composite (C), were applied to standardized class 2 cavities by incremental techniques with single- or bi-resin restoratives. After cyclic loading, the micro-tensile bond strength (µ-TBS) of the dentin cavity floor was measured. The Weibull modulus and Weibull stress values at 10%/90% probability of failure were analyzed. Single-resin incremental restorations with B or F and bi-resin incremental restorations with F + B and F + C demonstrated superior µ-TBS (quantitative ability), bonding reliability, and durability (qualitative ability) compared with the single-resin restoration with C (as control). Furthermore, F + B and F + C restoration yielded an excellent performance compared with the single-resin restorations with B, F, and C. In particular, the F + C restoration, which indicates not only the maximum mean µ-TBS, but also the highest values of the Weibull parameters, may be the optimal restoration method, including the esthetic benefits.

The effect of space setting values and restorative block materials on the bonding of metal-free CAD/CAM onlay restorations.

The effects of space setting values and restorative materials on the bonding of metal-free CAD/CAM onlay restoration were examined quantitatively and qualitatively. Seventy-two standardized MODB onlay cavities, prepared using human molars were restored under nine conditions, based on three space setting values, Increased (IC), Standard (SC, control), Decreased (DC), and three restorative block materials, resin-composites (RC), lithium disilicate glass-ceramics (LD), Feldspar ceramics (FC, control). All the restored specimens were subjected to cyclic loading and thereafter the microtensile bond strength (µ-TBS) was measured and analyzed statistically. The effect of space setting value on the µ-TBS varied with the restorative material. The bonding reliability of RC and the bonding durability of LD were significantly superior to FC. The bonding characteristics of RC under IC and DC were similar to those under SC. LD under DC and FC under IC were effective in obtaining an excellent bonding reliability relative to their SC.

The effect of additional photochemical treatments on the bonding of silanized CAD/CAM ceramic restorations after water-storage.

The development of dental CAD/CAM system has made metal-free ceramic restorations more available to patients. Silane coupling treatment is an essential clinical process to achieve reliable and good adhesion with silica-based indirect restoratives. However, long-term water-storage causes the hydrolysis of silane coupling agents and decreases the bond strength. The aim of this study was to examine the effect of additional treatments including photochemical treatments on silane coupling performance in ceramic restorations. The influence of water-storage periods (1d: one day, 1m: one month, and 3m: three months) for the silanized surface of CAD/CAM ceramic restorations was also investigated. In addition, bonding reliability was evaluated as a qualitative measure in order to characterize the bond strength of CAD/CAM restorations. The micro-tensile bond strength (µ-TBS) was measured to explore the benefits of additional photochemical treatments (UV: ultraviolet and VL: visible light irradiations) on silanized surfaces, compared to non-additional treated (CO) and dry heating (DR) conditions. In the CO specimens, µ-TBS decreased in the order of 1d > 1m > 3m. However, in DR, UV, and VL additional treatments, no significant differences could be observed in the 1d, 1m, and 3m groups. The Weibull modulus and 10% failure probability values of the UV and VL specimens were inclined to be significantly greater than those of CO specimens, regardless of the water-storage period. These findings reveal that additional photochemical treatments had a successful effect to improve the bond strength and bonding reliability of the CAD/CAM restorations, when compared to CO and DR conditions.

Effect of differences in the type of restoration and adhesive resin cement system on the bonding of CAD/CAM ceramic restorations.

The effect of differences in the type of restoration and adhesive resin cement system on the bonding of CAD/CAM ceramic restoration after cyclic loading was examined quantitatively and qualitatively. Seventy-two human maxillary first molars were divided into three restoration groups: MOD-inlay, MODP-onlay, and crown. Immediate dentin sealing was applied to the exposed dentin of all prepared specimens. The 24 specimens of each restoration group were further divided into another three groups, and a different adhesive resin cement system was applied to each group for cementation. All restoratives were fabricated from feldspathic-ceramic-blocks and cemented with each adhesive resin cement system according to the manufacturer's instructions. The microtensile bond-strength was measured after cyclic loading and was not significantly affected by differences in the type of restoration or adhesive resin cement system. However, the type of restorations and adhesive resin cement systems did show significant differences in terms of the bonding reliability.

Influence of immediate dentin sealing and temporary restoration on the bonding of CAD/CAM ceramic crown restoration.

This study examined the influences of clinical application of immediate dentin sealing (IDS) and temporary restoration (TR) on prepared abutment surfaces on the bonding of computer-aided design/computer-aided manufacturing (CAD/CAM) ceramic crown restorations after cyclic loading. Standardized abutments were prepared in 60 human mandibular premolars. Dentin surfaces of half of the specimens were sealed with adhesive and flowable composite, while those of the other half were not sealed. A half of both sealed and non-sealed specimens were restored using a temporary cement and temporary crown. Each individual CAD/CAM ceramic crown was fabricated and cemented to an individual abutment. The restored specimens were subjected to cyclic loading, and the micro tensile bond strengths (µ-TBS) were measured. IDS contributed to an increase in the bond strength, whereas TR did not affect the bond strength. IDS restoration without TR yielded the maximum bond reliability in achieve specific µ-TBS values for the restoration and ensuring durability against debonding.

Importance of interim restorations in the molar region.

Interim restoration protects abutment teeth and periodontal tissues until prosthetic treatment ends with the fabrication of a definitive prosthesis, restores and maintains the functions and morphology of the stomatognathic system, and preserves the occlusal contact relationship. Temporary prostheses are used for a short time, to confirm the diagnosis and treatment plan. However, because interim restorations are used only briefly, their importance in ensuring the success of definitive prostheses is often overlooked. This review includes a comprehensive literature review of interim restoration of molars and summarizes the current clinical understanding and status of this functionally important area. Peer-reviewed publications were identified by searching PubMed in November 2018. An interim restoration, even when used briefly, can help dentists evaluate many aspects of the treatment plan and contribute to accurate prognosis of prosthetic treatment.

Effect of immediate dentin sealing applications on bonding of CAD/CAM ceramic onlay restoration.

The effects of immediate dentin sealing (IDS) applications on the bonding of computer-aided design/computer-aided manufacturing (CAD/CAM) ceramic onlay restorations after cyclic loading were examined. Standardized mesial-distal-occlusal-palatal cavities in 32 extracted human molars were prepared. The cavities were divided into four groups: those receiving thin-layered (T), slope-shaped (S), and base-shaped (B) sealing, and the non-sealing group (N) as a control. The intra-cavity dentin walls of the T, S, and B groups were sealed with an all-in-one adhesive and a flowable composite. All cavities were scanned; hence, CAD/CAM onlays were fabricated using ceramic blocks and bonded with a resin cement system. Cyclic loading was applied and the microtensile bond strength (µ-TBS) was measured. It was found that IDS application improved not only the µ-TBS, but also the bonding reliability and durability of the CAD/CAM restoration. In particular, the S restoration exhibited the highest-performance as regards both robust bond strength and stable bonding.

Bonding state of metal-free CAD/CAM onlay restoration after cyclic loading with and without immediate dentin sealing.

To examine the bonding state of metal-free CAD/CAM onlay restorations made from two popular resin composite blocks and a typical glass-ceramic block after cyclic loading, with and without immediate dentin sealing (IDS). Standardized mesial-distal-occlusalbuccal (MODB) cavities in 24 extracted human molars were prepared. The intra-cavity dentin surfaces of half of the cavities were immediately sealed with all-in-one adhesive and flowable composite, while those of the other half were not. All cavities were scanned, from which CAD/CAM onlays were fabricated from three types of block and cemented with an adhesive resin cement system. The restored specimens were subjected to cyclic loading and the intra-cavity microtensile bond strength was measured. IDS improves not only the internal bond strength, but also the bond reliability of metal-free CAD/CAM onlay restorations. The resin composite block seems to be more effective than a typical glass-ceramic block for achieving both high bond strength and excellent bond reliability.

Bonding of flowable resin composite restorations to class 1 occlusal cavities with and without cyclic load stress.

To examine the bonding of flowable resin composite restorations (F-restoration) to class 1 occlusal cavities with and without cyclic load stress, compared with that of a universal resin composite restoration (U-restoration). Two flowable composites and one universal composite (control) were applied with an adhesive system to 42 standardized class 1 occlusal cavities. The restored specimens were subjected to cyclic load stress and no stress modes. The microtensile bond strength (µ-TBS) of the dentin floor was measured. The U-restoration did not show pretesting failure. The F-restorations exhibited pretesting failure, regardless of the stress mode. The µ-TBS was not significantly different among the three restorations, regardless of the stress mode. The cyclic load stress did not influence the µ-TBS of the F-restorations; however, it significantly reduced µ-TBS in the U-restoration. The bonding reliability of the F-restorations was inferior to that of the U-restoration, for both stress modes.