Bonding effectiveness and multi-interfacial characterization of two direct buildup resin core systems bonded to post-space dentin

Effect of Erbium, Chromium-doped: Yttrium, Scandium, Gallium and Garnet Laser Tooth Preparation on Gap Formation of Universal Adhesive Bonded to Enamel and Dentin: A Micro-CT and SEM Study

Introduction: The presence of gaps at the bonding interface of resin composite restorations is known to have an impact on restoration longevity. This study aimed to evaluate the effect of erbium, chromium-doped yttrium, scandium, gallium, and garnet (Er, Cr:YSGG) laser irradiation on gap formation at the tooth–resin interface and to compare the reliability of micro-computed tomography (µCT) and scanning electron microscopy (SEM) scans for gap formation assessment. Methods: Thirty standardized non-retentive class V cavities were prepared on sound human premolars using either an Er,Cr:YSGG laser or a round carbide bur (n=15 for each). A universal adhesive and A nano-filled resin composite were applied in accordance with the manufacturer’s recommendations. After water storage for 24 hours at 37°C, the teeth were subjected to thermocycling. Gap formation assessments were performed by µCT (Skyscan 1173 µCT, Brucker, Belgium) and SEM (JEOL JSM-6610LV, Japan), and SPSS version 24.0 (IBM Inc., Chicago, USA) was used to analyze the data at P value<0.05. Descriptive statistics were used to describe the gap formation percentages. To compare the impact of both preparation and assessment methods, a non-parametric Mann–Whitney U test was used. Results: In enamel, similar gap formation values were detected for the two preparation methods (bur and laser). However, the laser-prepared group showed higher gap formation values in dentin. Additionally, higher gap formation values were reported for both preparation methods when µCT was used for assessment. Conclusion: Cavity preparation using a Waterlase laser led to higher gap formation percentages at the dentin–resin interface. In addition, SEM assessment is more reliable for assessing the tooth–resin interface.

Ten Years of Micro-CT in Dentistry and Maxillofacial Surgery: A Literature Overview

Micro-computed tomography (micro-CT) is a consolidated imaging technology allowing non-destructive three-dimensional (3D) qualitative and quantitative analysis by the observation of microstructures with high resolution. This paper aims at delivering a structured overview of literature about studies performed using micro-CT in dentistry and maxillofacial surgery (MFS) by analyzing the entire set of articles to portray the state of the art of the last ten years of scientific publications on the topic. It draws the scenario focusing on biomaterials, in vitro and in/ex vivo applications, bone structure analysis, and tissue engineering. It confirms the relevance of the micro-CT analysis for traditional research applications and mainly in dentistry with respect to MFS. Possible developments are discussed in relation to the use of the micro-CT combined with other, traditional, and not, techniques and technologies, as the elaboration of 3D models based on micro-CT images and emerging numerical methods. Micro-CT results contribute effectively with whose ones obtained from other techniques in an integrated multimethod approach and for multidisciplinary studies, opening new possibilities and potential opportunities for the next decades of developments.

Effectiveness of pretreatment with phosphoric acid, sodium hypochlorite and sulfinic acid sodium salt on root canal dentin resin bonding

PURPOSE

The purpose of this study was to evaluate the effect of pretreatment using phosphoric acid, sodium hypochlorite and sulfinic acid sodium salt on the bonding of one-step self-etching adhesives to root canal dentin.

METHODS

Thirty-six single-rooted sound human premolars were randomly assigned into three groups before applying the one-step self-etching adhesive. These comprised a control group with no pretreatment, an NC group that received phosphoric acid and subsequent sodium hypochlorite gel pretreatments, and an NC+AC group that received an additional treatment with sulfinic acid sodium salt following the same pretreatment applied to the NC group. Microtensile bond strength measurements, bonding interface observations by scanning electron microscopy (SEM), elemental analyses by X-ray photoelectron spectroscopy (XPS) and degree of polymerization (DOP) analyses by Raman spectroscopy were subsequently performed.

RESULTS

The bond strength was significantly higher in the NC+AC group than in the other two groups (Control: P=000.1 and NC: P=0.004). SEM observations showed that resin tags were present in the dentinal tubules in the NC and NC+AC groups. Compared to the control group, the adhesive resin layer had a lower DOP in the NC group, while the DOP for the NC+AC group was higher than that of the NC specimens.

CONCLUSIONS

Bonding to root canal dentin was improved by applying sulfinic acid sodium salt in addition to treatment with phosphoric acid followed by sodium hypochlorite. The DOP of the adhesive resin was reduced by sodium hypochlorite and subsequently restored by applying sulfinic acid sodium salt.

Assessment of Bonding Effectiveness of Adhesive Materials to Tooth Structure using Bond Strength Test Methods: A Review of Literature

Background

The rapid developments in the field of adhesive dental materials have led to improvements in many aspects of clinical dentistry. Adhesive bond strength plays an important role in determining the clinical performance and longevity of dental restorations. Nevertheless, bond strength tests have never been well-standardized, although a number of important recommendations have been made.

Objective

The aim of this paper is to critically review the validity of different bond strength testing methods for assessment of bonding effectiveness of adhesive materials to tooth structure and discuss factors that may affect bond strength measurement.

Data Collection

Relevant literature published between 1983 and 2018 was collected and reviewed from the PubMed database and Google scholar resources.

Review Results

Results of the current bond testing methods should be used to compare materials tested under the same laboratory settings, but they shouldn't be used to make direct inferences on their clinical behaviour. Shear and micro-shear tests, result in non-uniform stress distribution, stress concentration at the substrate area, and predominantly tensile stresses rather than shear stresses. Micro-tensile bond tests provide many advantages over the shear tests, although these methods are technique sensitive and labour intensive.

Conclusion

Bond strength testing methods should be well-standardized, but there are many factors that cannot be fully controlled which leads to variation and misinterpretation of the data about the bonding abilities of adhesives.

Clinical Significance

New adhesive materials should be subjected to a combination of testing protocols to properly assess their bonding effectiveness.