Synthesis and characterisation of microcapsules for self-healing dental resin composites.

AIM: The purpose of this study was to i) synthesise TEGDMA-DHEPT microcapsules in a laboratory setting; ii) characterise the resultant microcapsules for quality measures. MATERIALS & METHODS: Microcapsules were prepared by in situ polymerization of PUF shells. Microcapsules characterisation include size analysis, optical and SEM microscopy to measure the diameter and analyse the morphology of PUF microcapsules. FT-IR spectrometer evaluated microcapsules and benzyl peroxide catalyst polymerization independently. RESULT: Average diameter of TEGDMA-DHEPT microcapsules was 120 ± 45 µm (n: 100). SEM imaging of the capsular shell revealed a smooth outer surface with deposits of PUF nanoparticles that facilitate resin matrix retention to the microcapsules upon composite fracture. FT-IR spectra showed that microcapsules crushed with BPO catalyst had degree of conversion reached to 60.3%. CONCLUSION: TEGDMA-DHEPT microcapsules were synthesised according to the selected parameters. The synthesised microcapsules have a self-healing potential when embedded into dental resin composite as will be demonstrated in our future work.

Performance of direct and indirect onlay restorations for structurally compromised teeth.

STATEMENT OF PROBLEM: Research is lacking on the restoration of structurally compromised posterior teeth using direct composite resin or indirect restorations. PURPOSE: The purpose of this in vitro study was to measure the fracture resistance and microleakage of different onlay restorations fabricated by using conventional and digital computer-aided design and computer-aided manufacturing (CAD-CAM) to restore structurally compromised teeth. MATERIAL AND METHODS: Mandibular molars (n=54) were prepared for onlay restorations. Teeth were allocated to 3 groups (n=18) according to the type of restoration materials, nanohybrid composite resin (Grandio blocs), resin hybrid ceramic (SHOFU Block HC), and fiber-reinforced composite resin (everX Posterior). Onlays were bonded using a dual-polymerized adhesive resin cement. All specimens were thermocycled, followed by cyclic loading. Based on the type of investigation conducted, fracture resistance, and microleakage test, each group was then divided into 2 equal subgroups (n=9). The collected data were statistically analyzed with the chi-square of the Fischer exact test (α=.05). RESULTS: Fracture resistance testing revealed a statistically significant difference between groups (P<.001). The fiber-reinforced composite resin demonstrated the highest fracture resistance, with statistically significantly less microleakage compared with the other groups (P=.013). CONCLUSIONS: Direct fiber-reinforced composite resin could be considered a suitable alternative to CAD-CAM composite resin for the restoration of structurally compromised teeth.

Effect of Bleaching Agents on Discoloured Resin-Based Composites for Direct Restorations: A Systematic Review.

The purpose of the review was to assess the influence of office and home bleaching on the color durability after staining of resin-based composites (RCs) for direct restorations. A web-based search for possibly relevant scientific papers in the English language between January 2013 and August 2022 was conducted in the databases such as PubMed, Scopus, Cochrane Library, and EMBASE. In-vitro studies that explored the influence of in-office and other bleaching treatments on the discolored RC for direct restorations in extracted human teeth were included. Case studies, case series, animal studies, systematic reviews, and letters to the editor were not considered. A total of 212 articles from a web-based search and 32 studies from a manual search were retrieved. After removal of duplicate records, 181 titles and abstracts were reviewed for eligibility; 92 were chosen for full-text analysis, and nine in-vitro studies matched the inclusion criteria. The two examiners examined the methodological quality of the selected studies independently based on the study design, methodological soundness, and data analysis. Distinct values were assigned to studies evaluating color variations of stained RC subjected to bleaching agents. The methodological quality scores were expressed as a percentage of the highest possible score based on the established scoring system and categorized as indicating a low, moderate, and high level of evidence. The reversal of color alterations following home and office bleaching was found to be dependent on the RC used. Within the limitations of the in-vitro investigations, it was deduced that the bleaching agents were successful in eliminating stains and improving the durability of the color to near baseline values.

A review and current state of autonomic self-healing microcapsules-based dental resin composites.

OBJECTIVE: This study systematically reviews the literature on self-healing microcapsule technology and evaluates the biocompatibility of self-healing microcapsules and the efficiency of crack repair within resin-based dental composites. METHODS: An electronic search was carried out using the following databases: MedLine (PubMed), Embase, the Cochrane Library and Google Scholar. All titles and abstracts of the articles and patents found were analysed and selected according to the eligibility criteria. Only studies published in English were included; the outcomes sought for this review were dental resin composites with self-healing potential. There were no restrictions on the type of self-healing system involved in dental resin composites. RESULTS: The search yielded 10 studies and 2 patents involving self-healing approaches to dental resin composites. According to the current literature on self-healing dental resin composites, when a crack or damage occurs to the composite, microcapsules rupture, releasing the healing agent to repair the crack with a self-healing performance ranging from 25% to 80% of the virgin fracture toughness. SIGNIFICANCE: Self-healing strategies used with resin composite materials have, to date, been bioinspired. So far, self-healing microcapsule systems within dental composites include poly urea-formaldehyde (PUF) or silica microcapsules. The main healing agents used in PUF microcapsules are DCPD monomer and TEGDMA-DHEPT, with other agents also explored. Silica microcapsules use water/polyacid as a healing agent. All self-healing systems have shown promising results for self-repair and crack inhibition, suggesting a prolonged life of dental composite restorations. More investigations and mechanical enhancements should be directed toward self-healing technologies in dental resin composites.