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Background The cementation of indirect restorations is a critical step influencing their long-term clinical success. While dual-cure resin cements are widely used, injectable resin composites have emerged as promising alternatives, offering improved handling, high filler content, and esthetic stability. However, their clinical performance as luting agents for indirect restorations remains insufficiently explored. This trial assessed the clinical performance of indirect hybrid ceramic onlay restorations cemented with injectable resin composite versus dual-cure resin cement over 18 months. Materials and methods A total of 28 participants were randomly assigned to two groups ( n  = 14) based on the cementation protocol. The intervention group received onlays cemented with injectable resin composite (BEAUTIFIL Flow Plus X F03, Shofu Dental Corporation), while the control group received dual-cure resin cement (BeautiCem SA, Shofu Dental Corporation). Standardized procedures were followed for cavity preparation, immediate dentin sealing, cavity optimization, impression-taking, onlay fabrication (SHOFU Block HC, Shofu Dental Corporation), and cementation. Restorations were evaluated at baseline, 6, 12, and 18 months using the modified USPHS criteria. Data were statistically analyzed with significance set at P  ≤ 0.05. Intergroup comparisons were assessed with Chi-squared test, while intragroup comparisons were assessed with Cochran’s Q test. Kaplan–Meier analysis and the log-rank test were used to evaluate survival rates. Results Inter- and intragroup comparisons revealed no significant differences between the two groups for most outcomes ( P  > 0.05). However, at 18 months, dual-cure resin cement exhibited significantly higher marginal discoloration than injectable resin composite ( P  = 0.038). Within the dual-cure resin cement group, a significant decline in alpha scores for marginal discoloration was observed from baseline to 18 months ( P  = 0.007). While no restorations failed (Charlie score), Kaplan–Meier survival analysis and the log-rank test demonstrated a statistically significant difference between the two groups ( P  = 0.029). Conclusions After 18 months, injectable resin composite demonstrated acceptable and comparable clinical performance to dual-cure resin cement, with the added benefit of reduced marginal discoloration. Clinical relevance Injectable resin composites offer a viable alternative to dual-cure resin cements for luting indirect restorations with enhanced esthetic outcomes. Trial Registration https://clinicaltrials.gov/ , (NCT05954156), 20-07-2023.

The replacement of synthetic and petroleum-based ingredients with greener alternatives of natural origin is an imperative issue in rubber technology for the tire industry. In this study, a glycerin-esterified maleated rosin resin, derived from natural resources, is examined as a potential tackifier in styrene–butadiene rubber (SBR) formulations. A comparison is made with two synthetic resins commonly used as tackifiers in tire manufacturing: a petroleum-derived aromatic resin and a phenolic resin. Specifically, this research investigates how these resins affect the structure, dynamics, and curing characteristics of SBR compounds, which are strictly related to the mechanical and technological properties of the final products. Moving die rheometer and equilibrium swelling experiments are employed to analyze vulcanization kinetics and crosslink density, which are differently influenced by the different resins. Information on the polymer–resin compatibility is gained by differential scanning calorimetry and dynamo-mechanical analysis, while solid-state NMR methods offer insights into the structure and dynamics of both cured and uncured SBR compounds at the molecular level. Overall, our analysis shows that the resin of vegetal origin has a comparable impact on the SBR compound to that observed for the synthetic resins and could be further tested for industrial applications.

Biodegradable materials based on poly (lactic acid) (PLA) and a phenolic free modified rosin resin were obtained and studied to control the biodegradability under composting conditions of the materials. The resin was blended in concentrations of 1, 3, 5, 10, and 15 parts per hundred (phr) of base polymer using industrial plastic processing techniques. Additionally, to study the effect of the resin on the compatibility of the PLA, the physical performance, water absorption, mechanical behavior, thermal stability, and microstructure of the materials were assessed. The resin incorporation decreased the resistance to thermal degradation of the resultant material, and the composting disintegration rate was slowed down with the increasing content of the resin. The water diffusion was delayed, and the diffusion and corrected diffusion coefficients decreased with the rising content of UP. The mechanical properties tend to decrease while a saturation effect was observed for contents higher than 3 phr of resin. The optimal amount of resin that can be added to achieve good interaction with PLA matrix, complete miscibility, and good material cohesion is 3 phr.

Phenol–formaldehyde (PF) resin continues to dominate the resin industry more than 100 years after its first synthesis. Its versatile properties such as thermal stability, chemical resistance, fire resistance, and dimensional stability make it a suitable material for a wide range of applications. PF resins have been used in the wood industry as adhesives, in paints and coatings, and in the aerospace, construction, and building industries as composites and foams. Currently, petroleum is the key source of raw materials used in manufacturing PF resin. However, increasing environmental pollution and fossil fuel depletion have driven industries to seek sustainable alternatives to petroleum based raw materials. Over the past decade, researchers have replaced phenol and formaldehyde with sustainable materials such as lignin, tannin, cardanol, hydroxymethylfurfural, and glyoxal to produce bio-based PF resin. Several synthesis modifications are currently under investigation towards improving the properties of bio-based phenolic resin. This review discusses recent developments in the synthesis of PF resins, particularly those created from sustainable raw material substitutes, and modifications applied to the synthetic route in order to improve the mechanical properties.

The aim of this study was to assess the clinical performance of a monoshade universal resin composite as posterior restoration. Twenty adult patients having at least two carious lesions related to posterior teeth were selected. Each patient was provided with a monoshade resin composite (Omnichroma) and polyshade nanohybrid resin composite (Tetric ® N-Ceram) for class I or II restorations. The performance of these restorations was assessed at 1, 3, 6, 9, and 12 months according to the modified United States Public Health Service (USPHS) criteria. Statistical analysis was carried out employing the Friedmann test and the Wilcoxon signed-rank test, with a significance level of p  = 0.05. None of the restorations exhibited any clinical conditions warranting replacement. The monoshade universal group revealed prevalence of (Bravo) scores concerning the anatomic form, surface texture and post-operative sensitivity through the follow-up period ( P  = 0.317). For color match and color stability, the polyshade group revealed a statistically significantly higher incidence of (Alpha) scores after 9 and 12 months ( P  = 0.025). After 12-months of follow-up, the monoshade universal resin composite demonstrated satisfactory clinical performance. It can serve as a viable substitute for polyshade nanohybrid composite where chair side time is an essential concern.

Abstract Objectives To evaluate the effect of the application of an additional hydrophobic bonding resin on the clinical performance of a universal adhesive applied in etch-and-rinse (ER) or self-etch adhesive (SE) strategy in non-carious cervical lesions (NCCLs) after 5 years.Materials and methodsScotchbond Universal Adhesive (3M Oral Care) was applied in 134 NCCLs of 39 subjects using different adhesion approaches: 3-step ER (3-ER), 2-step ER (2-ER), 2-step SE (2-SE), and 1-step SE (1-SE). Enamel and dentin were acid etched prior to application of the universal adhesive for the 3-ER and 2-ER groups. An extra layer of a hydrophobic bonding resin was applied for groups 3-ER and 2-SE. All lesions were restored with Filtek Supreme XTE resin composite (3M Oral Care). Restorations were evaluated at baseline and at 5 years using the modified USPHS criteria. Mann–Whitney U and Wilcoxon tests were performed, and the survival rates (retention/fracture) were analyzed using Kaplan–Meier and log-rank tests (p < 0.05).ResultsThe recall rate was 66.7% at 5 years. The cumulative survival rate was 96.9% for 3-ER, 96.8% for 2-ER, 71.4% for 2-SE, and 81.3% for 1-SE strategies. The log-rank test was statistically significant (p = 0.006). Retention rates were 100% for both ER groups, 75% for 2-SE and 81.3% for 1-SE. At 5 years, 2- and 1-SE approaches showed similar retention rates, but lower than those for 3- and 2-ER. A significant decrease in retention rate was detected for 2-SE (p = 0.007) and 1-SE (p = 0.014) groups between baseline and 5 years. All groups, except 2-ER, showed an increase in marginal discoloration. For this parameter, significant differences were detected between 2-ER and 1-SE (p = 0.004).ConclusionsThe addition of a hydrophobic bonding resin to the recommended application sequence of Scotchbond Universal Adhesive did not improve its clinical performance in NCCLs after 5 years. Higher retention rates were measured when this adhesive was applied in ER mode.Trial registrationThis manuscript is a 5-year follow-up of a randomized clinical trial that started in 2012 when there was no strong recommendation for registration in clinicaltrials.gov. The results after 36 months of clinical service were previously published in this journal.

Background. The aim of the current study was to evaluate and compare the influence of Dycal, Lime-Lite, TheraCal LC, Biodentine, resin-modified glass ionomer cement (RMGIC), and Activa BioActive as the pulp capping material on the shear bond strength of resin composite to dentin. Methods. A total of 70 extracted caries-free molars were randomly assigned to seven groups. Six test groups were covered with various protective liners: Dycal, TheraCal LC, Lime-Lite, Activa BioActive, Biodentine, and RMGIC. The control group received no liner pretreatment. Each sample was bonded to resin composite using the total-etch Tetric N bond adhesive. The samples were then tested for shear bond strength using the universal testing machine at a cross-head speed of 1 mm/min until bond failure occurred. The data were analyzed using the one-way ANOVA test followed by the Tamhane post hoc test for pairwise comparisons of the groups. Results. Independent of the type of the applied liner, all groups exhibited inferior SBS to dentin compared to the control group. TheraCal and RMGIC showed significantly higher shear bond strength than Biodentine and Dycal, which showed the lowest shear bond strength. Lime-Lite and Activa also had significantly lower SBS results than TheraCal. The mode of fracture was predominantly cohesive in Dycal, Biodentine, and TheraCal and adhesive in Activa. Conclusion. This present study concludes that the bond strength of resin composite to dentin can be affected differently using various types of liners.

Mater-Bi® NF866 (MB) was blended with gum rosin and two pentaerythritol esters of gum rosin (labeled as LF and UT), as additives, to produce biobased and compostable films for food packaging or agricultural mulch films. The films were prepared by blending MB with 5, 10, and 15 wt.% of each additive. The obtained films were characterized by optical, colorimetric, wettability, and oxygen barrier properties. Moreover, the additives and the MB-based films were disintegrated under composting conditions and the effect of each additive on the biodegradation rate was studied. All films were homogeneous and optically transparent. The color of the films tended to yellow tones due to the addition of pine resin derivatives. All the formulated films presented a complete UV-transmittance blocking effect in the UVA and UVB region, and those with 5 wt.% of pine resin derivatives increased the MB hydrophobicity. Low amounts of resins tend to maintain the oxygen transmission rate (OTR) values of the neat MB, due to its good solubilizing and compatibilizing effects. The disintegration under composting conditions test revealed that gum rosin completely disintegrates in about 90 days, while UT degrades 80% and LF degrades 5%, over 180 days of incubation. As expected, the same tendency was obtained for the disintegration of the studied films, although Mater-Bi® reach 28% of disintegrability over the 180 days of the composting test.

Background Cervical carious lesions present a clinical challenge due to several factors and require restorative materials with optimal performance. This trial evaluated the clinical performance and cost-effectiveness of low-shrinkage giomer resin composite (LS-GRC) compared to resin-modified glass ionomer (RMGI) for restoring cervical carious lesions over a 12-month period. Participants and methods A total of 56 class V cavities were randomly assigned to two groups ( n  = 28). Intervention group received LS-GRC (Beautifil II LS, Shofu Dental Corporation, Kyoto, Japan), and control group received RMGI (Fuji II LC, GC Corporation, Tokyo, Japan). Restorations were evaluated using revised FDI criteria at baseline, 6, and 12 months. Data were statistically analyzed with a significance level of P  ≤ 0.05. Intergroup comparisons were assessed with Chi-squared test, while intragroup comparisons were assessed with Cochran’s Q test. Incremental cost-effectiveness ratio (ICER) and cost per success ratio (CPSR) were used for cost-effectiveness analysis. Results After 12 months, intergroup comparisons revealed no significant differences for all outcomes ( P  > 0.05), except for surface luster and texture, which favored LS-GRC ( P  < 0.05). Intragroup comparisons revealed no significant differences within LS-GRC group ( P  > 0.016), while within RMGI group, significant differences were observed for surface luster and texture after 12 months ( P  < 0.016). ICER analysis showed that the cost for each additional 1% improvement in clinical outcomes with LS-GRC was approximately 1.6 times higher than that of RMGI. The CPSR for LS-GRC was 4.6% lower than that of RMGI, indicating that, despite its higher initial cost, LS-GRC provided comparable clinical performance, with significantly improved esthetic surface quality and favorable cost-effectiveness over the 12-month period. Conclusions LS-GRC and RMGI exhibited comparable performance and were clinically acceptable after 12 months. Clinical relevance Low-shrinkage giomer resin composite offers bioactivity, superior restoration integrity, and excellent esthetics, helping achieve optimal cervical restorations with improved clinical success, durability, and sustained cost-effectiveness. Trial registration https://clinicaltrials.gov/ , (NCT05930548), 30–06–2023. Graphical Abstract

Background Successful restorative procedures, particularly for patients undergoing head and neck radiotherapy, rely on a robust adhesive interface. Since radiotherapy may alter dental tissues and compromise bonding, this study evaluated how the timing of radiation exposure affects the microtensile bond strength (µTBS) of a universal adhesive to dentin with different application modes. Methods Forty-two human third molars were used in this study. Mid-coronal dentin was prepared using a low-speed saw and polished with silicon carbide paper. The samples were randomly divided into 3 groups ( n  = 6) according to the timing of radiation exposure (no radiation, control; radiation after restoration, F-RT; and radiation before restoration, RT-F). A single radiation dose of 70 Gy was administered to the samples after restoration (F-RT) and before restoration (RT-F). The samples were further divided into 2 subgroups according to the application mode of a universal adhesive (Single Bond Universal adhesive, 3 M Oral Care, St. Paul, MN, USA): etch-and-rinse (ER) or self-etch (SE) mode. After adhesive application, the resin composite was constructed and stored in distilled water at 37 °C for 24 h. Six resin-bonded teeth per group were processed for the µTBS test. The data were analyzed by two-way ANOVA followed by Duncan’s test ( p  < 0.05). Fractured surfaces were observed under a scanning electron microscope (SEM). Additional teeth were prepared for resin‒dentin interface observation ( n  = 1) and observed using an SEM. Results The application mode of the universal adhesive had no influence on the µTBS of dentin, regardless of irradiation ( p  = 0.670). The µTBS values of the control groups were not significantly different from those of the F-RT group but were significantly higher than those of the RT-F group for both application modes. The resin‒dentin interfaces of the samples were similar among the control, F-RT and RT-F groups. More abundant and longer resin tags were observed when the universal adhesive was bonded in ER mode. Conclusion Compared with radiation after restoration, radiation before restoration resulted in an inferior bond strength. The application mode of a universal adhesive had no effect on the bond strength. Clinical significance Restoration prior to the radiation procedure is an advisable strategy.