Microleakage after Thermocycling of Three Self-Etch Adhesives under Resin-Modified Glass-Ionomer Cement Restorations

In Vitro Evaluation of the Strength of Dentin Replacement in Complex Posterior Tooth Restoration

Due to the increasing interest in direct restoration, there is a need to address the shortcomings of these restorations, mainly by increasing the longevity of complex direct restorations. The present study aimed to evaluate the tensile strength differences in the complex restoration of posterior teeth with dentin replacement constructed by fiber and non-fiber materials. The samples were extracted from the mandibular permanent-molar and prepared using a complex cavity. The cavity was subsequently restored with the centripetal incremental technique using a nano-fill composite and different base materials, namely fiber dentin replacement, non-fiber dentin replacement, and flowable composite. The universal testing machine was used to consider the tensile strength and the fracture patterns were assessed using stereomicroscopy, followed by Scanning Electron Microscopy (SEM) examination. The data were statistically analyzed using the one-way ANOVA test. No significant differences were noted in the tensile strength of the three base materials. By using stereomicroscopy and SEM, the adhesive fracture patterns were observed more clearly in the cavities with fiber-based dentin replacement, whereas mixed fracture patterns were evident in cavities with non-fiber dentin replacement and flowable composite bases. The results indicated that the addition of fiber in dentin replacement did not affect the tensile strength in the complex restoration. Therefore, dentin replacement of both fiber and non-fiber materials is applicable as a base material for complex restoration of the posterior tooth.

ISP Good Clinical Practice Recommendations for the management of Dentin Hypersensitivity

Dentin hypersensitivity (DH) is a rising concern in clinical dentistry that causes pain and discomfort and negatively affects the quality of life of patients. Indian Society of Periodontology conducted a nationwide survey, involving 3000 dentists in December 2020, which revealed significant knowledge gaps regarding DH, viz., under-diagnosis, incorrect differential diagnosis, and treatment strategies/recommendations for the management of DH patients in daily clinical practice. The current paper has been envisioned and conceptualized to update the practicing Indian dentists regarding the so-called enigma of dentistry “Dentin Hypersensitivity,” based on the best available contemporary evidence. An expert panel was constituted comprising 30 subject experts from across the country, which after extensive literature review and group discussions formulated these recommendations. The panel advocated routine screening of all dentate patients for exposed dentin areas and DH to avoid under-diagnosis of the condition and suggested an early preventive management. Consensus guidelines/recommendations for the use of desensitizing agents (DAs) at home, including the use of herbal agents, are also provided within the backdrop of the Indian context. The guidelines recommend that active management of DH shall be accomplished by a combination of at home and in-office therapies, starting with the simplest and cost-effective home use of desensitizing toothpastes. A diagnostic decision tree and a flowchart for application in daily practice are designed to manage the patients suffering from DH or presenting with exposed dentin areas in dentition. Various treatment methods to manage DH have been discussed in the paper, including the insights from previously published treatment guidelines. Further, a novel system of classification of DH patients based on specific case definitions has been developed for the first time. Explicit charts regarding the available treatment options and the chronology of institution of the agent, for the management in different case categories of DH, have been provided for quick reference. The management strategy takes into account a decision algorithm based on hierarchy of complexity of treatment options and intends to improve the quality of life of the patient by long-term maintenance with an innovatively defined triple C's or 3Cs approach.

Cavity Bases Revisited

OBJECTIVE

The aim of this paper was to review the current literature on cavity bases while focusing on the role of zinc oxide eugenol (ZOE) and resin-modified glass ionomers (RMGI) as cavity bases.

MATERIALS AND METHODS

A thorough literature search between 1970 and 2020 was done using Scopus, PubMed, and Google Scholar databases. The keywords of the search strategy were as below: cavity liners and bases, pulp protection, zinc oxide eugenol, and resin-modified glass ionomer. No specific inclusion or exclusion criteria were applied as to what articles would be included in this review.

CONCLUSION

This review emphasizes that the available literature provides very little evidence to support the routine use of a base under amalgam or composite restorations. This review favors the adoption of "no more lining or bases" in shallow and moderate cavity preparations. However, an exception might be a "protective base" of RMGI following the application of calcium hydroxide (CH) liners in deep cavities. Bonded RMGIs are suitable cavity base materials and should always replace zinc oxide eugenol bases in daily practice.

Evaluation of the effect of home bleaching gel on microleakage of different glass ionomers reinforced with micro-hydroxyapatite

Aim

This study aimed to evaluate the effect of home bleaching gel on microleakage of glass-ionomer cements reinforced with micro-hydroxyapatite (HAP).

Methods

Class V cavities prepared on the forty extracted third molars were restored in four groups (n = 10): Group 1, Zirconomer; Group 2, resin-modified glass ionomer (RMGI); Group 3, Zirconomer + micro-HAP (20% WT); and Group 4, RMGI + micro-HAP (20% WT). After thermocycling (1000 cycles at 5 ± 2/55 ± 2°C, a dwell time of 30 s), each group was randomly divided into two groups. The first half was kept in distilled water and the restorations of the second half were bleached with carbamide peroxide 15% (14 days, each time 6 h/day). A uniform thickness of bleaching agent (0.5-1 mm) was applied on the surfaces of the restorations, extending 1 mm beyond the margins, and the bleaching agent was exchanged every 6 h. Microleakage was evaluated using dye penetration technique that is based on the amount of dye penetration (0.5% basic fuchsine solution) from the occlusal/gingival margins up to the axial wall.

Results

In distilled water, no significant difference was found between the occlusal microleakage scores (P > 0.05). The lowest and highest gingival scores in distilled water were observed in Group 4 and Group 3, respectively. In bleaching environment, there was no significant difference between four groups (P > 0.05). Comparing each glass ionomer in two environments revealed statistically significant differences in gingival and occlusal microleakage of Group 4 and in occlusal microleakage of Group 1 (P < 0.05).

Conclusions

Micro-HAP incorporation did not affect the microleakage of the RMGI and Zirconomer in bleaching environment and their occlusal microleakage in distilled water. The lowest and highest gingival scores in distilled water were observed for the RMGI + micro-HAP and Zirconomer + micro-HAP, respectively. Bleaching procedure negatively affects the microleakage score of RMGI + micro-HAP and occlusal microleakage of Zirconomer.

Evaluation of the effect of adding micro-hydroxyapatite and nano-hydroxyapatite on the microleakage of conventional and resin-modified Glass-ionomer Cl V restorations

Background

Pulpal reaction to restorative materials depends on marginal microleakage, which is a dynamic phenomenon that allows bacteria and fluids to traverse across the tooth-restoration interface. Glass-ionomer cement (GIC) exhibits low microleakage due to direct bonding to tooth structures. Hydroxyapatite (HAP) based on the similarity with tooth structure may decrease the microleakage. The aim of this in vitro study was to evaluate marginal microleakage of a mixture of conventional and resin-modified glass-ionomer (RMGI) with micro- and nano-HAP.

Material and Methods

In this in vitro study, 30 non-carious extracted human third molar teeth were used. Standard Cl V cavities were prepared on the buccal and lingual surfaces. The cavities were restored in six experimental groups as follows: group 1, conventional glass-ionomer cement (CGIC); group 2, CGIC with micro-HAP; group 3, CGIC with nano-HAP; group 4, RMGI; group 5, RMGI with micro-HAP; group 6, RMGI with nano-HAP. The restorations were finished and polished. The teeth were coated with nail polish, sealed with sticky wax, thermocycled and placed in a solution of 2% basic fuchsine for 24 hours. The teeth were sectioned and microleakage was measured. Kruskal-Wallis, Man-Whitney and Wilcoxon tests were used for data analysis (P<0.05).

Results

The data analysis revealed significantly lower microleakage in groups 5 and 6 at both occlusal and gingival margins. Also in these two groups the gingival microleakage was significantly lower than occlusal margin (P=0.009 and P=0.001 respectively), but in groups 1(CGIC) and 3(CGIC+ nano-HAP) and 4(RMGI) the microleakage of occlusal margin were significantly lower than that of gingival margin (P=0.001, P=0.007 and P=0.001 respectively).

Conclusions

Mixing RMGI with nano-HAP and micro-HAP resulted in lower microleakage.

Key words:Glass-ionomer, micro-hydroxyapatite, microleakage, nano-hydroxyapatite.

Correlation between Microleakage and Absolute Marginal Discrepancy in Zirconia Crowns Cemented with Four Resin Luting Cements: An In Vitro Study

Objectives. To evaluate microleakage and absolute marginal discrepancy (AMD) and to assess correlation between AMD and microleakage with four resin luting cements. Material and Methods. 20 extracted human third molars were prepared for full-coverage crowns. 20 zirconia copings were made (LAVA, 3M ESPE) and cemented. Specimens were randomly allocated for each used type of cement into 4 groups, RelyX® (Rx), Multilink® (Mk), PANAVIA 2.1® (P), and Maxcem® (Mx) and immersed in 10% safranin for 72 hours. 20x magnification lenses were used to observe microleakage areas (μm²) and images software was used to measure AMD areas (μm). Discrepancy and microleakage between the cements were compared with one-way ANOVA test with confidence interval of 95%. Results. Rx Group showed microleakage has lowest value and AMD has highest value. P Group showed microleakage has the highest value and Mk Group presented AMD has lowest value. There were no significative differences between the cements. There were no linear correlations between microleakage and AMD; however a complex regression statistical model obtained allowed formulating an association between both variables (microleakage = AMD^0,896). Conclusions. No significative differences were found among 4 types of cements. No linear correlations between AMD and microleakage were found. Clinical Significance. AMD is not easily related to microleakage. Characteristics of cements are fundamental to decreasing of microleakage values.

Comparative Evaluation of Microleakage Between Nano-Ionomer, Giomer and Resin Modified Glass Ionomer Cement in Class V Cavities- CLSM Study

INTRODUCTION

Marginal integrity of adhesive restorative materials provides better sealing ability for enamel and dentin and plays an important role in success of restoration in Class V cavities. Restorative material with good marginal adaptation improves the longevity of restorations.

AIM

Aim of this study was to evaluate microleakage in Class V cavities which were restored with Resin Modified Glass Ionomer Cement (RMGIC), Giomer and Nano-Ionomer.

MATERIALS AND METHODS

This in-vitro study was performed on 60 human maxillary and mandibular premolars which were extracted for orthodontic reasons. A standard wedge shaped defect was prepared on the buccal surfaces of teeth with the gingival margin placed near Cemento Enamel Junction (CEJ). Teeth were divided into three groups of 20 each and restored with RMGIC, Giomer and Nano-Ionomer and were subjected to thermocycling. Teeth were then immersed in 0.5% Rhodamine B dye for 48 hours. They were sectioned longitudinally from the middle of cavity into mesial and distal parts. The sections were observed under Confocal Laser Scanning Microscope (CLSM) to evaluate microleakage. Depth of dye penetration was measured in millimeters.

STATISTICAL ANALYSIS

The data was analysed using the Kruskal Wallis test. Pair wise comparison was done with Mann Whitney U Test. A p-value<0.05 is taken as statistically significant.

RESULTS

Nano-Ionomer showed less microleakage which was statistically significant when compared to Giomer (p=0.0050). Statistically no significant difference was found between Nano Ionomer and RMGIC (p=0.3550). There was statistically significant difference between RMGIC and Giomer (p=0.0450).

CONCLUSION

Nano-Ionomer and RMGIC showed significantly less leakage and better adaptation than Giomer and there was no statistically significant difference between Nano-Ionomer and RMGIC.

The effect of IDS (immediate dentin sealing) on dentin bond strength under various thermocycling periods

PURPOSE

The purpose of this study was to find out the effect of immediate dentin sealing (IDS) on bond strength of ceramic restoration under various thermocycling periods with DBA (dentin bonding agent system).

MATERIALS AND METHODS

Fifty freshly extracted human mandibular third molars were divided into 5 groups (1 control and 4 experimental groups) of 10 teeth. We removed enamel layer of sound teeth and embedded them which will proceed to be IDS, using All Bond II. A thermocycling was applied to experimental groups for 1, 2, 7, 14 days respectively and was not applied to control group. IPS Empress II for ceramic was acid-etched with ceramic etchant (9.5% HF) and silane was applied. Each ceramic disc was bonded to specimens with Duo-link, dual curable resin cement by means of light curing for 100 seconds. After the cementation procedures, shear bond strength measurement and SEM analysis of the fractured surface were done. The data were analyzed with a one-way ANOVA and Tukey multiple comparison test (α=.05).

RESULTS

There were no statistically significant differences between 4 experimental groups and control group, however the mean value started to decrease in group 7d, and group 14d showed the lowest mean bond strength in all groups. Also, group 7d and 14d showed distinct exposed dentin and collapsed hybrid layer was observed in SEM analysis.

CONCLUSION

In the present study, it can be concluded that ceramic restorations like a laminate veneer restoration should be bonded using resin cement within one week after IDS procedure.

Restoration of noncarious cervical lesions: when, why, and how

At this time, restoration of noncarious cervical lesions (NCCLs) is a common occurrence in clinics nowadays. Some reasons for this are the growth of the elderly population, a smaller rate of tooth loss, and possibly the increase of some etiologic factors. These factors include inadequate brushing techniques in gingival recession cases, corrosive food and drink consumption, and occlusal stress concentrating factors (occlusal interferences, premature contacts, habits of bruxism, and clenching). Unfortunately, Class V restorations also represent one of the less durable types of restorations and have a high index of loss of retention, marginal excess, and secondary caries. Some causes for these problems include difficulties in isolation, insertion, contouring, and finishing and polishing procedures. This work aims to help dentists in choosing the best treatment strategy, which necessarily involves steps of problem identification, diagnosis, etiological factor removal or treatment, and, if necessary, restoration. Finally, appropriate restorative techniques are suggested for each situation.