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The resin infiltration concept is one of the most widely used minimally invasive restorative techniques in restorative dentistry with the most outstanding therapeutic effect, and it is also one of the key research directions in restorative dentistry. “Infiltration resin” is the specialty restorative material for the technology, which is the key factor to success. The specialized restorative material is commonly known as “infiltrant/infiltration resins” “resins infiltrant” “infiltrant” or “resins,” which will be consistently referred to as “infiltration resins” throughout the article. The paper aims to provide a comprehensive overview of infiltration resins by introducing the development of their therapeutic mechanisms, basic components, current challenges, and future trends, Based on existing literature, we analyze and compare how changes in the base monomer's structure and ratio affect the effectiveness of infiltration resins, from the material's structure‐effective relationship. After compiling the information, the existing solution strategies have been listed to offer substantial support and guidance for future research endeavors. [ABSTRACT FROM AUTHOR]

Dental caries is the most widespread form of disease, affecting over 90% of the global population. Amalgam fillings, which have been in use for nearly two centuries, will face an European Union ban by 2025. Although photocomposite fillings are a suitable alternative, health concerns persist because of potential substance release into the oral cavity. This study aimed to evaluate the release of photoinitiator substances and monomers from dental materials into various solvents at different temperatures over 30 days. Cylindrical specimens of the composite resins were submerged in different extraction solutions and incubated at 37 and 50°C. The findings demonstrated that both the extraction solvent and extraction temperature significantly influenced the quantity of leachables (p < 0.05). Furthermore, most leachables were released within the initial days, although some monomers continued to elute for over 30 days. The estimated daily intake was calculated for the worst‐case scenario, confirming the biocompatibility of the composite fillings. The weight loss of dental materials ranged up to 3.5% after 30 days, regardless of the extraction conditions and dental material (p > 0.05). In conclusion, this study contributes to filling several research gaps in the field by addressing the biocompatibility of various dental materials through quantitative and qualitative analyses supported by statistical evaluation. [ABSTRACT FROM AUTHOR]

In clinical applications, resin‐based dental composites primarily face challenges with fractures and secondary caries. To overcome these issues, the physical characteristics of dental composites, especially mechanical properties, need to be improved. Hydroxyapatite (HA), present in the structure of the teeth, is preferred due to its biological properties, and zirconia (ZrO2) nanoparticles are known to enhance the mechanical properties of this type of composites. The aim of this study is to develop resin‐based dental composites containing HA and ZrO2 nanoparticles. The study also aims to explore the synergistic effect of these two nanoparticles on the physical properties of the developed composites. Composites with nine different compositions were prepared by mixing the components with the help of a mortar mill. The flexural and compressive strength, polymerization shrinkage, depth of cure and water sorption, and solubility properties of the prepared composites have been investigated. All composites have been found to meet the requirements of ISO 4049 standard. Among them, composite containing 5 wt. % HA and 1 wt. % ZrO2 (H5Z1) has exhibited the highest flexural strength with an increase of 58% compared to the control sample, and composite containing 3 wt. % HA and 2 wt. % ZrO2 (H3Z2) has exhibited the highest compressive strength with an increase of 22% compared to the control sample. Other physical properties of the composites have been found to be in an acceptable level. Highlights: Dental composites with HA and ZrO2 fillers were developed by a mortar mill.Synergistic effect of HA and ZrO2 nanoparticles was investigated.Mechanical properties of dental composites were significantly improved.Physical properties of dental composites were found to be at acceptable levels.Depth of cure decreases with increasing HA and ZrO2 loading. [ABSTRACT FROM AUTHOR]

The durability of dental materials, when used in the mouth, is determined by their mechanical qualities. Composite resins are frequently used in dental restorations. Flexural tests and Vickers micro‐hardness tests on selected dental composite materials were performed in a universal testing machine (ASTM D790‐10 standard) and Vickers micro‐hardness tester (ASTM E384‐11e1standard). In this study, four different dental composite material samples are employed. The samples are dipped in a chewing tobacco solution for a few days before being removed and put through the tests. Also in this work, four different machine learning models were tested to see how well they could analyze the mechanical characteristics of dental composite materials when submerged in a chewing tobacco solution. For predicting the mechanical properties of dental composite specimens, four distinct machine‐learning models (extreme gradient boosting (XGBoost), adaptive boosting (AdaBoost), random forest, and k‐nearest neighbors (KNN) have been selected. AdaBoost machine learning model yields a coefficient of regression value of 0.9903 in predicting the flexural strength, whereas the XGBoost model gives a coefficient of regression value of 0.9890 in predicting the Vickers hardness distinctly better than the other models. [ABSTRACT FROM AUTHOR]

Although salivary liquid can degrade constituents in resin‐based dental composites in short‐term incubations, there is a knowledge gap on how longer‐term aging impacts their bulk strength. We address this through extended aging studies with resin‐based dental composites in different environments. Two commercial composites (FIL and AEL) were aged aseptically at 37°C in air (A, control), artificial saliva (AS), and esterase enzyme amended AS (EAS). Diametral and pushout strength were measured after periods of 120–180 days. At 120 days, the diametral strength of composites aged in air was 69.9 ± 11.0 and 57.7 ± 3.31 MPa in FIL and AEL, respectively. These were significantly greater compared to composites aged in AS (32.1 ± 7.01 and 46.2 ± 9.38 MPa in FIL and AEL, respectively) or EAS (36.7 ± 8.49 and 43.5 ± 5.51 MPa in FIL and AEL, respectively). In contrast, pushout strength for both composites were smaller in A compared to those aged in AS and EAS, results attributed to AS absorption and polymer expansion. No significant change in either diametral or pushout strength occurred after 120 days. There was no significant difference between aging in AS and EAS, suggesting that esterase did not significantly decrease the bulk material strength to a greater extent than AS under the test conditions. Aqueous diffusivities for the composites ranged from 8.4 to 11 × 10−13 m2/s, with associated porosities ranging from 0.06% to 0.10%. These results indicate that saturation of a typical dental composite occurs over a time frame of 4–5 months, longer than typical aging studies. Together, the results demonstrate the importance of aging time on composite strength. [ABSTRACT FROM AUTHOR]

In this present study, the preference selection index method (PSI) was applied to identify the best formulation among ceramic fillers such as glass ionomer cement (GIC), nanosilica and nanoalumina nanofiller in the dental composites. The comparative assessment of the effect of nanofillers (nanoalumina and nanosilica fillers) and glass ionomer cement has been evaluated. Dental composites with 0, 10, and 20 wt% of nanoalumina, nanosilica and glass ionomer cement were fabricated. These composites were analyzed for physico‐mechanical and wear properties. The PSI multi‐criteria decision making technique was used to rank the composites with various filler content. The performance defining attributes for the comparative assessment were set as void content, hardness, compressive strength, flexural strength, diametral tensile strength, and wear properties against load and speed. The PSI of dental composite reinforced with 20 wt% nanosilica (DCSi‐20) was maximum (0.896) followed by dental composite reinforced with 20 wt% glass ionomer (DCGi‐20) (0.889) and hence DCSi‐20 demonstrated as most preferred dental composite material followed by DCGi‐20. DC‐0 showed the least preference dental composite materials on the basis of desirable physical, mechanical, and wear properties. Finally, it can be concluded that despite of more void content and low flexural strength, overall performance of glass ionomer is comparable with nanosilica and more significant with respect to nanoalumina. [ABSTRACT FROM AUTHOR]

Commercial bisphenol A‐glycol methacrylate (BisGMA)/triethyleneglycol‐dimethacrylate (TEGDMA) have been widely used as dental restorative material; however, the poor mechanical and anti‐wear properties greatly limited their applied range. In this study, iron‐containing hydroxyapatite (FeHA) nanoparticles that mimic the chemical composition and microstructure of natural bamboo rat incisor enamel were synthesized and used as reinforcement in BisGMA/TEGDMA resins. The as‐prepared polycrystalline FeHA have a rod like morphology with uniformly dispersed iron. The effects of nanoparticle–resin weight ratios on the mechanical properties, tribological properties, and bioactivity of FeHA‐BisGMA/TEGDMA resins were investigated. In vitro bioactivity of the studied resin composites in artificial saliva showed that a dense and continuous apatite layer was formed on the surface of the resin composite. Findings revealed that doping a suitable content of FeHA nanoparticle, especially at 0.75 wt% FeHA, would significantly improve the tribological and mechanical properties as well as bioactivity of the dental resin composites. [ABSTRACT FROM AUTHOR]

Introduction: The durability and longevity of composite restoration are much dependent on the accurate delivery of the energy required to polymerise the material. This study aimed to investigate the extent to which undergraduate dental students acquire and retain light‐curing skills following hands‐on training. Materials and Methods: Hands‐on training comprises faculty tutoring for critical aspects of the light‐curing procedure, such as distance and angulation of the light‐curing tip. Assessments of the students' ability to deliver a specified radiant exposure to class III and I simulated RBCs using a dental simulator (MARC‐PS®) at three different time points after the training. Data were analysed using repeated measure ANOVA. Results: Immediately after the training, students' performance on curing was improved (p <.05). Overall, the radiant exposure increased after training, but the students lost some of the benefits with time. For curing in the anterior section (anterior sensor‐class III), the mean radiant exposure values increased by approximately 20% after the training. After 2 years, the values were 15% greater than baseline values. For curing in the posterior section (posterior sensor‐class I), the mean radiant exposure values increased by approximately 150% after the training. A significant decrease (p <.05) was observed; however, the radiant exposure values were still 82% greater than the baseline after 2 years. Conclusion: A hands‐on training dedicated to light‐curing procedures facilitated acquisition and retention up to a 2‐year follow‐up of skill on how light cure composite inside the mouth. The training was more relevant for curing in posterior areas, where orientation can significantly impact light‐curing. A hands‐on training where the radiant exposure can be measure gave objective measurement metrics to guide the curing performance. This approach is an effective means of teaching practical skills to dental students. [ABSTRACT FROM AUTHOR]

Bonding of resin composite fillings, for example following root‐canal treatment, is a challenge because remaining gaps grow and lead to failure. Here, phase‐contrast‐enhanced micro‐computed tomography (PCE‐CT) is used to explore methods of non‐destructive quantification of the problem, so that countermeasures can be devised. Five human central incisors with damaged crowns were root‐filled followed by restoration with a dental post. Thereafter, the crowns were rebuilt with a resin composite that was bonded conventionally to the tooth with a dental adhesive system (Futurabond U). Each sample was imaged by PCE‐CT in a synchrotron facility (ID19, European Synchrotron Radiation Facility) with a pixel size of 650 nm. The reconstructed datasets from each sample were segmented and analysed in a semi‐automated manner using ImageJ. PCE‐CT at sub‐micrometre resolution provided images with an impressive increased contrast and detail when compared with laboratory micro‐computed tomography. The interface between the dental adhesive and the tooth was often strongly disrupted by the presence of large debonded gaps (on average 34% ± 15% on all surfaces). The thickness of the gaps spanned 2 µm to 16 µm. There was a large variability in the distribution of gaps within the bonding area in each sample, with some regions around the canal exhibiting up to 100% discontinuity. Although only several micrometres thick, the extensive wide gaps may serve as gateways to biofilm leakage, leading to failure of the restorations. They can also act as stress‐raising 'cracks' that are likely to expand over time in response to cyclic mechanical loading as a consequence of mastication. The observations here show how PCE‐CT can be used as a non‐destructive quantitative tool for understanding and improving the performance of clinically used bonded dental restorations. [ABSTRACT FROM AUTHOR]

With environmental concerns, the development of a posterior restorative as a true alternative to dental amalgam is needed. Hence in this regard, the development of dental composites have gained more and more research interest, as they have the advantages of better aesthetic look, better physical, mechanical and tribological properties over the other available dental materials. In this study, the physical, mechanical and wear behavior of dental composite materials have been reviewed. Numerous experimental results, analytical studies and their significance were also discussed for various dental composite materials. The wear performances of dental composite materials depend up on various factors including oral environment, resin chemistry, filler technology and interfacial bonding strength etc. In oral environment, the presence of medium such as water, air, heptane, ethanol, artificial saliva etc. and durations up to which composite is kept such as seven days, one month or three months etc. affect the performance of dental composite. Abrasion and erosion are two major causes for the wear behavior of dental composite / human teeth. The major issue, most significant challenges and effect of each of those factors affecting the performance of dental composite materials were also presented along with some recommendation. [ABSTRACT FROM AUTHOR]

Objective: The aim of this study was to evaluate the color stability of two resin‐based composites photo‐activated by two light curing units (LCU) with different irradiances. Materials and Methods: Hundred disc‐shaped specimens (2‐mm thick) of a nanofilled (FZ‐ FiltekTM Z350 XT, 3M ESPE) and a microhybrid (ED—Empress® Direct, Ivoclar Vivadent) composites were photo‐activated with two LCU: Valo® Cordless, Ultradent (VA—1800 mW/cm2) or Radii‐cal, SDI (RA—900 mW/cm2). Samples (n = 5) were immersed during 12 days in distilled water (WT), orange juice (OJ), red wine (RW), coffee (CF), or Brazilian tea (BT). CIELAB coordinates were obtained using a spectrophotometer (Easyshade 4.0, Vita Zahnfabrik) before (T0) and after (T1) immersion. CIEDE2000 color difference (ΔE00) and whiteness index for dentistry (WID) were calculated. Data was analyzed by two‐way ANOVA and Tukey's test (α = 0.05%). Results: FZ light‐activated by VA showed higher L* and WID values (T0) and lower ΔE00 values after immersion in WT, OJ, and RW. However, there was no effect of both factors on ΔE00 when samples were immersed in BT and CF. ED light‐activated by RA showed significant higher C* values (p ≤ .05). Conclusions: The nanofilled composite photo‐activated with higher irradiance showed greater L* and WID values and better color stability. However, all samples immersed in colored beverages showed ΔE00 values above the acceptability threshold. Clinical Significance: Initial color of resin‐based composites can change after immersion in staining beverages. However, the best color stability was obtained by the nanocomposite photo‐activated by a light‐curing unit of higher irradiance. [ABSTRACT FROM AUTHOR]

The aims of this study were to evaluate 1) the effect of different light-curing training methods on first-year dental students' light-curing performance immediately after and one year after training and 2) the effect of dental student year (first vs. third year) and different light-curing training methods on students' light-curing efficacy. The study was organized into two parts, conducted in 2013 and 2014. In the first part, all students (N=66) in the first-year restorative course at a Canadian dental school were invited to participate in a light-curing activity immediately after training; after 12 months, those students (now in their second year) were asked to again perform the light-curing activity. In the second part, all the subsequent first-year students (N=75) and third-year students (N=95) were invited to perform the same light-curing activity after training. Each class was divided into three groups: the Control group received a lecture; the Tips group received the same lecture plus tips on "7 Steps to Ensure Better Light Curing"; and the Simulator group received the lecture, tips, and hands-on training using the patient simulator. In the first part of the study, all 66 students participated in the first year; 39 of those participated a year later. In the second part, all students in both years participated. For the first part, time had a significant effect on light-curing performance, with significantly higher results in the second year. When the first-year students' results were isolated, training method had a significant effect on mean and maximum irradiance values. The second part found a significant effect of training on mean (p=0.003) and maximum (p=0.021) irradiance. The interaction DDS*training was significant (p=0.037) when the after-training values were analyzed. These results point to the need for further research to determine the most effective light-curing training methods. [ABSTRACT FROM AUTHOR]

Objective The aim of this study was to investigate the effect of shade and opacity on the change in light transmission through different thicknesses of a nano-hybrid composite during curing. Materials and Methods Twelve different shades of Venus Diamond (Heraeus Kulzer) were placed in disk shaped molds with thickness of 1, 2, and 3 mm (n = 3 per group) and cured with an LED light-curing unit. Initial, final and average irradiance, and the total amount of energy passing through the specimen were measured using the MARC Resin Calibrator at every 10s for a total of 40s. The translucency parameter and the contrast ratio were obtained using a chromameter. Results were analyzed with ANOVA/Tukey's test (α = 0.05). Results All shades and all thicknesses (up to 3 mm) experienced an increase in light transmittance during curing. The majority of the increase occurred during the initial 10s exposure, with significant increase occurring from subsequent exposures only in thicker specimens (i.e., 3 mm). The increase in irradiance at the bottom during curing was dependent on shade, with darker shades and greater depths of material showing less increase. Conclusions For one specific resin composite formulation, an increase in translucency occurs as cure progresses, and the increase is enhanced for composites with greater lightness and lower contrast ratio. Clinical significance Composites demonstrate increased light transmittance as curing progress, which may improve depth of cure., The thicker composite showed the least increase in light transmission within the same shade., The increase in translucency is enhanced for composites with great lightness and lower contrast ratio. [ABSTRACT FROM AUTHOR]

A new photoinitiator based on a bis-silylketone (BSK) structure is proposed as a novel compound leading to highly efficient initiating silyl radicals for the polymerization of methacrylates (e.g., a bisphenol A-glycidyl methacrylate/triethyleneglycol dimethacrylate blend (70%/30% w/w)) upon exposure to a blue light emitting diode and a green laser diode. The polymerization profiles are recorded by real time Fourier transform IR (FTIR) spectroscopy. Absorption, fluorescence, electron spin resonance (ESR), and steady state experiments are used to investigate the involved chemical mechanisms. Molecular orbital calculations are also carried out. Remarkably, BSK efficiently works in the presence of an iodonium salt. The overall mechanism for the initiation step is clarified. This novel class of silyl radical generating photoinitiators is really promising for the photopolymerization of methacrylates, e.g., in dental materials. [ABSTRACT FROM AUTHOR]

ABSTRACT To reduce human exposure risk to bisphenol A derivatives, a new 2,2-bis[p-(2'-hydroxy-3'-methacryloxypropoxy) phenylene]propane (Bis-GMA) free dental composites material GEC-66% was prepared using a dendritic macromer (G-IEMA) as one component of resin matrix. Properties of GEC-66%, such as double bond conversion (DC), polymerization shrinkage, water sorption (WS) and solubility, flexural strength (FS) and modulus, and cytotoxicity on human dental pulp cells were evaluated. The commercial Bis-GMA contained restorative material 3M ESPS FiltekTM Z250 was used as a control. The results showed that GEC-66% had higher DC and WS, comparable shrinkage and solubility, and less cytotoxicity, when compared with Z250. Though FS of GEC-66% was lower than that of Z250, it still met the ISO requirement for polymer-based restorative materials. All of these proved that GEC-66% had potential to be used in clinic. [ABSTRACT FROM AUTHOR]

This study investigated the effect of shape, size, and surface modification of hydroxyapatite (HAP) fillers on the degree of conversion (DC) and mechanical properties of a model BisGMA/TEGDMA composite initially and after 4 weeks of storage. Ten percent of conventional glass fillers were replaced by HAP spheres (Sph), silicon-doped spheres (SphSi), whiskers (Wh), silicon-doped whiskers (WhSi), and nanosized HAP particles (Nano). Spheres were specifically structured agglomerates consisting of a central void and radially orientated primary particles, whereas whiskers were compact monocrystals. DC, Vickers hardness (HV), flexural strength (Fs), flexural modulus (Ef), compressive strength (Cs), and compressive modulus (Ec) were tested. There were no significant differences in the DC between all tested groups. HV decreased by 5.4-17% with the addition of HAP, while Fs increased by 13.9-29% except in Nano group (decrease by 13%). After storage, Sph and SphSi groups showed similar HV, Ef, Cs and Ec and higher Fs than the control. The fracture mode of HAP spheres was through the central void whereas whiskers showed longitudinal delamination, transverse, and mixed fractures. HAP spheres with or without silicon- doping have a potential to be part of the filler content of dental composites. © 2013 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 101B: 1469-1476, 2013. [ABSTRACT FROM AUTHOR]

ABSTRACT The aim of this study was to evaluate, using atomic force microscopy, the effect of two different bleaching agents on the modification of dental composites materials. This modification will be judged by analyzing the variation of surface roughness and surface morphology of two different composites: one containing nanoparticles and other consisting of microhybrid resin. The bleaching was performed by using two different concentrations of hydrogen peroxide: HP Blue (20% hydrogen peroxide) and Whiteness HP Maxx (35% hydrogen peroxide). Disks of Esthet X and Filtek™ Z350 composites were used. Atomic force microscopy was used for analyses of the same place of the sample before and after treatment. A total of 12 analyses were performed per group ( n = 12). The samples were analyzed qualitatively by evaluating morphological changes in the images and quantitatively by using roughness parameters (Ra). Data were analyzed statistically using Kruskal-Wallis, Mann-Whitney, and Friedman tests ( P < 0.05). Changes were observed both qualitatively and quantitatively only in the groups where Esthet X resin was used. The use of hydrogen peroxide bleaching agents caused changes only in the surface of microhybrid composites, with no changes being observed in the composite containing nanoparticles. Despite being even significant, these alterations are clinically slight and can be eliminated by polishing them. Microsc. Res. Tech. 76:481-485, 2013. © 2013 Wiley Periodicals, Inc. [ABSTRACT FROM AUTHOR]

The objective of this study is to synthesize antibacterial methacrylate and methacrylamide monomers and formulate antibacterial fluoride-releasing dental composites. Three antibacterial methacrylate or methacrylamide monomers containing long-chain quaternary ammonium fluoride, 1,2-methacrylamido- N, N, N-trimethyldodecan-1-aminium fluoride (monomer I), N-benzyl-11-(methacryloyloxy)- N, N-dimethylundecan-1-aminium fluoride (monomer II), and methacryloxyldecylpyridinium fluoride (monomer III) have been synthesized and analyzed by nuclear magnetic resonance (NMR) and mass spectrometry (MS). The cytotoxicity test and bactericidal test against Streptococcus mutans indicate that antibacterial monomer II is superior to monomers I and III. A series of dental composites containing 0-6% of antibacterial monomer II have been formulated and tested for degree of conversion (DC), flexure strength, water sorption, solubility, and inhibition of S. mutans biofilms. An antibacterial fluoride-releasing dental composite has also been formulated and tested for flexure strength and fluoride release. The dental composite containing 3% of monomer II has a significant effect against S. mutans biofilm formation without major adverse effects on its physical and mechanical properties. The new antibacterial monomers can be used together with the fluoride-releasing monomers containing a ternary zirconiun-fluoride chelate to formulate a new antibacterial fluoride-releasing dental composite. Such a new dental composite is expected to have higher anticaries efficacy and longer service life. © 2012 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 2012. [ABSTRACT FROM AUTHOR]

In this study, microstructures of dental composites were observed using high resolution scanning transmission electron microscopy (HR STEM). Samples for these observations were prepared by focused ion beam system. Two kinds of dental composites were investigated: (1) polymer-ceramic composite containing nano-sized ceramic fillers and (2) ceramic-polymer composite based on the nano-structured yttrium stabilized zirconia. The first composite is a popular material for dental fillings whereas the second is used for the fabrication of fixed partial dentures. The results are discussed in terms of the evaluation of fabrication process of the composites. [ABSTRACT FROM AUTHOR]

Purpose: This study assessed the effect of 6 months of aging in water on surface roughness and surface/subsurface hardness of two microhybrid resin composites. Materials and Methods: Filtek Z250 and Charisma were tested. Cylindrical specimens were obtained and stored in distilled water for 24 hours or 6 months, at 37°C. For Knoop hardness evaluation, the specimens were transversely wet-flattened, and indentations were made on surface and subsurface layers. Data were submitted to three-way ANOVA and Tukey's test (α≤ 0.05). Surface roughness baseline measurements were made at 24 hours and repeated after 6 months of storage. Data were submitted to repeated measures ANOVA and Tukey's test (α≤ 0.05). Results: Surface hardness (KHN, kg/mm2) means (± standard deviation) ranged from 55 ± 1 to 49 ± 4 for Z250 and from 50 ± 2 to 41 ± 3 for Charisma, at 24 hours and 6 months, respectively. Subsurface means ranged from 58 ± 2 to 61 ± 3 for Z250 and from 50 ± 1 to 54 ± 2 for Charisma, at 24 hours and 6 months. For both composites, the aged specimens presented significantly softer surfaces ( p < 0.01). For the subsurface hardness, alteration after storage was detected only for Charisma, which presented a significant rise in hardness ( p < 0.01). Z250 presented significantly harder surface and subsurface layers in comparison with Charisma. Surface roughness (Ra, μm) means ranged from 0.07 ± 0.00 to 0.07 ± 0.01 for Z250 and from 0.06 ± 0.01 to 0.07 ± 0.01 for Charisma, at 24 hours and 6 months, respectively. For both composites, no significant roughness alteration was detected during the study ( p= 0.386). Conclusions: The 6-month period of storage in water presented a significant softening effect on the surfaces of the composites, although no significant deleterious alteration was detected for the subsurface hardness. In addition, the storage period had no significant effect on the surface roughness of the materials. [ABSTRACT FROM AUTHOR]

The aims of this study were, first, to measure shrinkage induced by different methods of pulse-delay light curing and, second, to verify their influence on the marginal adaptation of class V restorations in enamel and dentin. Eight groups, comprising seven groups ( n = 6) with different pulse-delay parameters and a control group, were compared for dynamic linear displacement and force by using a fine hybrid composite. Based on these results, the pulse-delay curing procedure with the lowest shrinkage force was chosen and tested against the control group with respect to marginal adaptation in class V restorations ( n = 8) before and after simultaneous thermal and mechanical loading. Statistically significant differences between groups were found for both shrinkage properties tested, with one pulse-delay group giving the lowest overall shrinkage values. However, the percentages of ‘continuous margin’ of this group, and of the control before and after loading, were not significantly different in dentin, whereas a significantly lower percentage of ‘continuous margin’ was detected in the pulse-delay group in enamel after loading. [ABSTRACT FROM AUTHOR]

In this work, the synthesis of two new antishrinking methacrylic monomers of spiroorthocarbonate type, SOC‐IP‐UDMA and SOC‐UDMA, is discussed, along with studies of their performance as polymeric matrix in dental composites. The monomers were photoactive with components of a conventional resin composite. In order to study the photocuring kinetics of these SOC monomers, a real‐time test was performed using FTIR spectroscopy. It was found that SOCs promoted higher double bond conversions (DC) than conventional methacrylic monomer bis‐GMA (48%), reaching a DC value of 68% for SOC‐UDMA and 75% for SOC‐IP‐UDMA. The shrinkage stress that accompanies curing of dental composites was measured by a universal testing machine. These new monomer SOCs are capable of reducing the shrinkage up to 51.1% and 27.7% for both methacrylic monomers when they were compared with bis‐GMA as control. Also, a dynamical mechanical analysis was conducted on the dental composites, obtaining a higher modulus and a range of Tg values from 80 to 100 °C. Others parameters like flexural properties, solubility, and sorption water were determined, obtaining values better than or equal to the parameters established by the standard ISO 4049. These monomers can be considered as alternative matrixes to replace bis‐GMA in dental composites. © 2018 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019, 136, 47114. [ABSTRACT FROM AUTHOR]

Dental restorative resin composites are a pivotal class of organic/inorganic hybrid materials. The main reasons for their failure are secondary caries and dental composite fractures, which prevent their long‐term service in posterior restorations. A remedy to these problems is improving the interfacial adhesion between the resin matrix and the fillers. Surface‐modified inorganic fillers show strong potential as more than just a bond between these two phases and can therefore be considered a medium to compensate for the deficits of dental composites. This paper mainly discusses strategies to improve the interfacial adhesion of dental composites, including surface treatments of fillers with coupling agents, polymers, and tetraethyl orthosilicate (TEOS) coatings, as well as the selection of porous fillers capable of micromechanical resin matrix/filler interlocking. Additionally, the existing deficiencies of these strategies and the prospects for dental composites are discussed. Dental restorative composites are vulnerable to unsatisfactory mechanical properties, which are due in part to the degradation of the matrix/filler interfacial bonding during service. The main modification strategies to improve their interface adhesion are discussed in this work, including surface treatments of fillers with coupling agents, polymers, tetraethyl orthosilicate (TEOS) coating, and the selection of porous fillers. [ABSTRACT FROM AUTHOR]