Microtensile Bond Strength of Resin Composite Bonded to Caries-affected Dentin with Three Adhesives

Biodentine or Mineral Trioxide Aggregate as Direct Pulp Capping Material in Mature Permanent Teeth with Carious Exposure? A Systematic Review and Meta-analysis

OBJECTIVE

To evaluate the success rate of direct pulp capping (DPC) with Biodentine in mature permanent teeth with carious vital pulp exposure compared to that of DPC with mineral trioxide aggregate (MTA) by means of a systematic review and meta-analysis.

DATA SOURCES

The two authors searched independently the literature published through July 31, 2020, in five electronic databases (PubMed, the Cochrane Central Register of Controlled Trials, Web of Science Core Collection, the Wiley Online Library, and the SCOPUS database).

STUDY SELECTION

The research protocol was previously registered in the PROSPERO database (CRD42020192511). Clinical studies that met the inclusion criteria were chosen and independently screened by the authors.

DATA EXTRACTION

A custom-designed spreadsheet was used to extract the data. The quality of each study was evaluated by means of the revised Cochrane risk of bias (ROB) tool or the ROB of nonrandomized studies of interventions tool.

DATA SYNTHESIS

Three randomized controlled trials and one retrospective study met the inclusion criteria. Only one study had a high risk of bias. The included studies reported data on a total of 95 participants with an age range of 8-51 years. No significant difference was observed in the overall treatment outcome when comparing Biodentine with MTA (Risk ratio=1.00, 95% confidence interval [0.93-1.07], p=1.00).

CONCLUSIONS

Biodentine had comparable clinical and radiographic success to that of MTA when used as a DPC agent in mature permanent teeth with carious vital pulp exposure. Additional high-quality studies are needed.

Degradation of Multimode Adhesive System Bond Strength to Artificial Caries-Affected Dentin Due to Water Storage

The purpose of this study was to evaluate the influence of water storage on bond strength of multimode adhesive systems to artificially induced caries-affected dentin. One hundred twelve sound bovine incisors were randomly assigned to 16 groups (n=7) according to the dentin condition (sound; SND, artificially induced caries-affected dentin; CAD, cariogenic challenge by pH cycling for 14 days); the adhesive system (SU, Scotchbond Universal Adhesive; AB, All-Bond Universal; PB, Prime & Bond Elect; SB, Adper Single Bond 2; and CS, Clearfil SE Bond), and the etching strategy (etch-and-rinse and self-etch). All adhesive systems were applied under manufacturer's instructions to flat dentin surfaces, and a composite block was built up on each dentin surface. After 24 hours of water storage, the specimens were sectioned into stick-shaped specimens (0.8 mm2) and submitted to a microtensile test immediately (24 hours) or after six months of water storage. Bond strength data (MPa) were analyzed using three-way repeated-measures analysis of variance and post hoc Tukey test (α=5%), considering each substrate separately (SND and CAD). The etching strategy did not influence the bond strength of multimode adhesives, irrespective of the dentin condition. Water storage only reduced significantly the bond strength to CAD. The degradation of bond strength due to water storage was more pronounced in CAD, regardless of the etching strategy.

Bond Durability of Different Resin Cements to Caries-Affected Dentin Under Simulated Intrapulpal Pressure

Objective:

To evaluate the durability of the bond of different resin cement systems to normal dentin (ND) and caries-affected dentin (CAD) with and without simulated intrapulpal pressure (IPP).

Methods and Materials

Molars with midcoronal caries were used. Occlusal enamel was cut to expose both dentin substrates (ND and CAD). Dentin substrates were differentiated using visual, tactile, caries-detecting dye, and dye-permeability methods. Prepared crown segments were equally divided according to the tested resin cement systems: etch-and-rinse resin cement, self-etch resin cement containing methacryloyloxydecyl dihydrogen phosphate (MDP), and self-adhesive resin cement. In addition to the dentin substrates and the resin cement types, the effect of application/storage conditions (with or without simulated IPP and with or without thermocycling) were tested. A microtensile bond strength test was done using a universal testing machine. Failure modes were determined using a scanning electron microscope.

Results

Etch-and-rinse resin cement strength values were significantly affected by the difference in the dentin substrates as well as the different application/storage conditions. Self-etch adhesive containing MDP bonded equally to ND and CAD and remained stable under all tested conditions. Self-adhesive resin cement revealed a similar bond to ND and CAD; however, its values were the lowest, especially when IPP and thermocycling were combined. Mixed failure was the predominant failure mode.

Conclusions

Etch-and-rinse resin cement was sensitive to dentin substrate and application/storage conditions. Resin cement with self-etch adhesive containing MDP revealed more reliable bonding to ND/CAD even when IPP and thermocycling were combined. The bonding of the self-adhesive resin cement could not compete with other resin cements.

The Effect of Self-adhesive and Self-etching Resin Cements on the Bond Strength of Nonmetallic Posts in Different Root Thirds

PURPOSE

The purpose of this study was to evaluate the effect of self-adhesive and self-etching resin cements on the bond strength of nonmetallic posts in different root regions.

MATERIALS AND METHODS

Sixty single-rooted human teeth were decoronated, endodontically treated, post-space prepared, and divided into six groups. Glass-fiber (GF) posts (Exacto, Angelus) and fiber-reinforced composite (FRC) posts (EverStick, StickTeck) were cemented with self-adhesive resin cement (Breeze) (SA) (Pentral Clinical) and self-etching resin cement (Panavia-F) (SE) (Kuraray). Six 1-mm-thick rods were obtained from the cervical (C), middle (M), and apical (A) regions of the roots. The specimens were then subjected to microtensile testing in a special machine (BISCO; Schaumburg, IL, USA) at a crosshead speed of 0.5 mm/min. Microtensile bond strength data were analyzed with two-way ANOVA and Tukey's tests.

RESULTS

Means (and SD) of the MPa were: GF/SA/C: 14.32 (2.84), GF/SA/M: 10.69 (2.72), GF/SA/A: 6.77 (2.17), GF/SE/C: 11.56 (4.13), GF/SE/M: 6.49 (2.54), GF/SE/A: 3.60 (1.29), FRC/SA/C: 16.89 (2.66), FRC/SA/M: 13.18 (2.19), FRC/SA/A: 8.45 (1.77), FRC/SE/C: 13.69 (3.26), FRC/SE/M: 9.58 (2.23), FRC/SE/A: 5.62 (2.12). The difference among the regions was statistically significant for all groups (p < 0.05). The self-adhesive resin cement showed better results than the self-etching resin cement when compared to each post (p < 0.05). No statistically significant differences in bond strengths of the resin cements when comparable to each post (p > 0.05).

CONCLUSION

The bond strength values were significantly affected by the resin cement and the highest values were found for self-adhesive resin cement.

Relationship between Operator Skill and In Vitro Microleakage of Different Adhesive Systems in Class V Restorations

Objectives. The aim of this study was to evaluate the influence of operator skill on microleakage in class V composite restorations. Materials and Methods. A total of 16 dentists and 25 dental students were enrolled, and 123 extracted teeth were allocated according to the adhesive being tested: Scotchbond Multipurpose, Adper Scotchbond 1 XT, and AdheSE. Each operator was asked to restore one tooth from each experimental group: two class V cavities were cut on each tooth and each adhesive was used on the same tooth before and after instructions for its use. After filling cavities with composite (Z100), the teeth were thermocycled. Results. For all of the tested adhesives, the mean microleakage score was lower for the dentists than for the students. The mean scores for the three tested adhesives were statistically similar before and after instructions for use. Conclusion. Our results indicate that the skill of the operator has a significant influence on microleakage.

Effect of thermal and mechanical loading on marginal adaptation and microtensile bond strength of a self-etching adhesive with caries-affected dentin

Aim:

This study evaluated the effect of thermal and mechanical loading on marginal adaptation and microtensile bond strength in total-etch versus self-etch adhesive systems in caries-affected dentin.

Materials and Methods:

Forty class II cavities were prepared on extracted proximally carious human mandibular first molars and were divided into two groups: Group I — self-etch adhesive system restorations and Group II — total-etch adhesive system restorations. Group I and II were further divided into sub-groups A (Without thermal and mechanical loading) and B (With thermal and mechanical loading of 5000 cycles, 5 ± 2°C to 55 ± 2°C, dwell time 30 seconds, and 150,000 cycles at 60N). The gingival margin of the proximal box was evaluated at 200X magnification for marginal adaptation in a low vacuum scanning electron microscope. The restorations were sectioned, perpendicular to the bonded surface, into 0.8 mm thick slabs. All the specimens were subjected to microtensile bond strength testing. The marginal adaptation was analyzed using descriptive studies, and the bond strength data was analyzed using the one-way analysis of variance (ANOVA) test.

Results and Conclusions:

The total-etch system performed better under thermomechanical loading.

Microtensile bond strength of one- and two-step self-etching adhesives on sclerotic dentin: the effects of thermocycling

This study evaluated the effects of thermocycling on the microtensile bond strength (microTBS) of one- and two-step self-etch adhesives (SEAs) to sclerotic dentin. Two adhesives, Clearfil S3 Bond (S3), a one-step self-etch adhesive (1-SEA), and Clearfil SE Bond (SE), a two-step self-etch adhesive (2-SEA), were applied on cervical lesions in human premolars with sclerotic or normal dentin. After adhesive application, the lesions were restored and built up using a resin composite (Clearfil AP-X). After 24 hours in water storage, the restored teeth were sectioned into 0.7 x 0.7 mm composite-dentin beams. The beams were then aged with 0, 5,000 or 10,000 thermocycles. The use of two adhesives, two substrate types and three thermocycling regimens yielded 12 experimental groups of 14-19 beams each. The beams were subsequently subjected to microTBS testing at a crosshead speed of 1 mm/minute and statistical analyses were computed with three-way ANOVA and Tukey's post hoc test at p < 0.05. Three-way ANOVA showed statistically significant effects on bonding effectiveness by lesion type, adhesive system, thermocycling or combinations of the adhesive system and thermocycling (p < 0.05). With sclerotic dentin, although S3 and SE provided comparable microTBS after 24 hours of water storage, S3 showed significantly lower microTBS than SE after thermocycling (p < 0.05). Regardless of lesion type, the microTBS for S3 decreased significantly after 5,000 or 10,000 thermocycles, while the microTBS for SE showed a significant decrease only after 10,000 thermocycles. Regardless of the extent of thermocycling, the microTBS values for either SE or S3 bonded to sclerotic dentin were significantly lower than to normal dentin (p < 0.05). The results suggested that thermocycling had a significant negative effect on the bond strength of the two SEAs tested. In contrast to 2-SEA, 1-SEA might not be a good choice for sclerotic dentin when seeking durability of the resin-dentin bond.

Effect of filler content of flowable composites on resin-cavity interface

The purpose of this in vitro study was to evaluate marginal integrity and wall adaptation in 1- and 2-mm-deep cavities restored with a high filler-loaded flowable composite in comparison to a flowable composite with lower filler content and a conventional hybrid composite. 1-mm-deep dentin and 2-mm-deep enamel-dentin Class I cavities were prepared and restored with a self-etch adhesive and with one of the composites. Samples were crosscut and evaluated for marginal integrity and gap formation using a digital microscope. Selected samples were also observed using a scanning electron microscope. For 1-mm-deep cavities, no differences in marginal integrity and wall adaptation were observed among the three composites. For 2-mm-deep cavities, those restored with the bulk technique and with the higher filler-loaded flowable composite demonstrated a similar outcome as that of the conventional hybrid composite. On the effect of restorative techniques, cohesive enamel defects were observed in bulk-filled 2-mm-deep cavities. However, when the incremental technique was used in conjunction with the higher filler-loaded flowable composite and the conventional hybrid composite for 2-mm-deep cavities, superior results were obtained.

Direct comparison of the bond strength results of the different test methods: a critical literature review

OBJECTIVE

The goal of this paper is to undertake a literature search collecting all dentin bond strength data obtained for six adhesives with four tests (shear, microshear, tensile and microtensile) and to critically analyze the results with respect to average bond strength, coefficient of variation, mode of failure and product ranking.

METHOD

A PubMed search was carried out for the years between 1998 and 2009 identifying publications on bond strength measurements of resin composite to dentin using four tests: shear, tensile, microshear and microtensile. The six adhesive resins were selected covering three step systems (OptiBond FL, Scotch Bond Multi-Purpose Plus), two-step (Prime & Bond NT, Single Bond, Clearfil SE Bond) and one step (Adper Prompt L Pop).

RESULTS

Pooling results from 147 references showed an ongoing high scatter in the bond strength data regardless which adhesive and which bond test was used. Coefficients of variation remained high (20-50%) even with the microbond test. The reported modes of failure for all tests still included high number of cohesive failures. The ranking seemed to be dependant on the test used.

SIGNIFICANCE

The scatter in dentin bond strength data remains regardless which test is used confirming Finite Element Analysis predicting non-uniform stress distributions due to a number of geometrical, loading, material properties and specimens preparation variables. This reopens the question whether, an interfacial fracture mechanics approach to analyze the dentin-adhesive bond is not more appropriate for obtaining better agreement among dentin bond related papers.

Effect of Operator-specific Handling on Tooth-composite Interface and Microleakage Formation

After calibration of the restoration procedure, three operators experienced differences in tooth-composite interface morphology and microleakage formation. These differences reflect technique-sensitivity of the etch-and-rinse adhesive. The lowest microleakage on dentin was related to an enhanced interface integrity. After additional application of an adhesive component, sealing of the enamel and dentin was partially enhanced, but microleakage formation did not decrease. These results are helpful in the comparative evaluation of other bonding systems.

Comparison between regional micropush-out and microtensile bond strength of resin composite to dentin

OBJECTIVE

In this study we compared the micropush-out (micro-PO) and microtensile (micro-TBS) test methods for resin composites on different levels and surfaces of dentin.

MATERIAL AND METHODS

Thirty-four sound human molars were divided into two groups in accordance with the dentin surface used (occlusal (O) or mesio-distal (M)), then subdivided into a further two groups in accordance with the test method (micro-PO (P) or micro-TBS (T)). In groups OP and OT, teeth were ground occlusally perpendicular to their axis, and in groups MP and MT, mesio-distally parallel to their axis to expose dentin. Dentin disks were prepared from different regions of the teeth either in an occluso-cervical (group OP) (n=5) or mesio-distal direction (group MP) (n=5) (S, superficial; M, middle; D, deep). One-hundred-and-twenty standardized occlusal cavities were prepared in these dentin disks using a conical-shaped diamond rotary cutting instrument. The adhesive (Adper Scotchbond Multi-Purpose Dental Adhesive) and a composite material (Filtek Z250 Universal Restorative) were applied and polymerized with a LED light curing unit (Elipar FreeLight 2). The disks (n=20/per group) were tested in a universal testing machine and pushed out with a cross-head speed of 1.0 mm/min. In groups OT (n=12) and MT (n=12), the teeth were ground to expose superficial, middle, and deep dentin. Build-ups of resin composite were constructed with the same materials. The specimens were serially sectioned and trimmed to hour-glass shapes, then tested with the micro-TBS tester at a rate of 1 mm/min. Failure modes were examined using a stereomicroscope and scanning electron microscope.

RESULTS

ANOVA revealed significant differences among the groups (p<0.001). With the push-out test, no premature failure occurred, the variability of the data distribution was acceptable, and regional differences in bond strength among dentin levels could be assessed.

CONCLUSIONS

The micro-PO test method could be an alternative to the micro-TBS technique.