Two year clinical evaluation of a low-shrink resin composite material in UK general dental practices

Proposal of a Modular Classification System for Direct Dental Resin Composites Based on Clinical Applications

The adhesive-resin composite pair has been the cornerstone of direct restorations in dentistry for many years. Resin composites are traditionally classified in three ways based on their inorganic structure, their organic composition and their viscosity. While these classifications have long been associated with the optical, mechanical, and clinical properties of resin composites, recent studies indicate that this classification is not always valid. In recent years, a significant expansion of the range of clinical resin composite families has occurred, each with varying degrees of validation through in vitro and clinical studies. As a result, new resin composites with distinct structures, viscosities, and clinical indications have emerged. Despite this progress, a formal classification of the clinical features of all resin composites is still lacking, leading to terminological inconsistencies in research and potential confusion among clinicians. This brief review, supported by an exhaustive search of the dental literature, proposes a new clinical classification system for resin composites based on their key clinical features to help clinicians and researchers easily identify the key clinical characteristics of formulations. This modular classification, encompassing eight main families and 14 characteristics, is particularly suited to future developments, as current trends aim to simplify procedures by integrating multiple formulations into single products.

The Impact of Simulated Bruxism Forces and Surface Aging Treatments on Two Dental Nano-Biocomposites-A Radiographic and Tomographic Analysis

Background and Objectives: Nowadays, indication of composite materials for various clinical situations has increased significantly. However, in the oral environment, these biomaterials are subjected (abnormal occlusal forces, external bleaching, consumption of carbonated beverages, etc.) to changes in their functional and mechanical behavior when indicated primarily for patients with masticatory habits. The study aimed to recreate in our lab one of the most common situations nowadays-in-office activity of a young patient suffering from specific parafunctional occlusal stress (bruxism) who consumes acidic beverages and is using at-home dental bleaching. Materials and Methods: Sixty standardized class II cavities were restored with two nanohybrid biocomposite materials (Filtek Z550, 3M ESPE, and Evetric, Ivoclar Vivadent); the restored teeth were immersed in sports drinks and carbonated beverages and exposed to an at-home teeth bleaching agent. The samples were subjected to parafunctional mechanical loads using a dual-axis chewing simulator. A grading evaluation system was conducted to assess the defects of the restorations using different examination devices: a CBCT, a high-resolution digital camera, and periapical X-rays. Results: Before mechanical loading, the CBCT analysis revealed substantially fewer interfacial defects between the two resin-based composites (p > 0.05), whereas, after bruxism forces simulation, significantly more defects were identified (p < 0.05). Qualitative examination of the restorations showed more occlusal defects for the Evetric than the other nanohybrid composite. Conclusions: There were different behaviors observed regarding the studied nanocomposites when simulation of parafunctional masticatory forces was associated with aging treatments.

Impact of dietary acids on the surface roughness and morphology of composite resins

This in vitro study was performed to evaluate the surface roughness (Ra) and morphology by scanning electron microscopy (SEM) of composite resins that had been stored in acidic solutions typical of those present in the diet. Three composite resins (4 Seasons, Z250, and P90) were selected and divided into three groups (n = 7) according to the solutions tested: G1: distilled water; G2, Coca-cola, and G3: orange juice. The Ra test was repeated after immersion periods of 15, 90, and 180 days. The mean Ra values were subjected to LS means analysis and the Tukey-Kramer (P < 0.05). One test specimen of each composite resin was selected for SEM analysis after each period. The Ra data indicated that P90 had the lowest Ra values. 4 Seasons and Z250 had statistically similar roughness values for all the solutions and evaluation periods. With the exception of 180-day immersion in Coca-cola, 4 Seasons showed significantly higher values than Z250. SEM analysis showed that P90 was the composite resin most resistant to the actions of all acid solutions for the periods analyzed. Interaction between components of the solutions and the active components of other dietary items, as well as oral hygiene, may affect the chemical degradation of composite resins.

Influence of the organic matrix composition on the polymerization behavior and bulk properties of resin composites containing thiourethane-functionalized fillers

OBJECTIVES

The incorporation of thiourethane-based oligomeric additives into resin composite formulations leads to improvement in mechanical properties and reduction in polymerization stress, but may increase viscosity. The objective of this study was to functionalize filler particle surfaces with thiourethane silane molecules and determine the impact of the inorganic filler loading and surface treatment on the behavior of experimental resin composites with systematically-varied organic matrices.

METHODS

Thiourethane oligomer was synthesized de novo, and grafted to the surface of 0.7um barium glass. BisGMA and TEGDMA (BT) were combined (at 30:70, 50:50 or 70:30 wt%) to 50 or 75 wt% of methacrylate (MA-Sil - control) or thiourethane-silanized (TU-Sil) particles. Composites were made polymerizable by the addition of 0.2 wt% BAPO and 0.05 wt% BHT was added as inhibitor. A mercury arc lamp (320-500 nm) at 800 mW/cm2 was used for all curing procedures. Kinetics of polymerization was assessed by near-IR spectroscopy in real time. Polymerization stress was determined with a cantilever system in real time (Bioman). Flexural modulus and strength were determined in 3-point bending (25x2x2 mm). Water sorption and solubility and film thickness were tested according to ISO 4049. Polymeric network characteristics were analyzed by dynamic mechanical analysis (DMA). Data was analyzed with two-way ANOVA/Tukey's test (95%).

RESULTS

Viscosity increased with the increase in BisGMA and/or filler amounts. Overall, TU-Sil containing composites showed delayed vitrification and higher final DC. Filler concentration did not affect DC neither flexural strength. DC decreased with increasing BisGMA content. Polymerization stress reduced and flexural modulus increased for higher filler content, especially for formulations containing TU-Sil particles. The water stability was positively affected by the increase in amount of BisGMA and inorganic filler particles. In terms of polymeric network, the addition of TU-Sil particles increased the Tg and decreased the E' and cross-link density.

CONCLUSIONS

With the exception of flexural modulus, all tested properties were significantly impacted by the matrix viscosity and/or the addition of TU-Sil filler particles. In general, the use of thiourethane oligomers as a silane coupling agent was able to reinforce the materials and reduce the polymerization stress without negatively affecting the viscosity of the system.

The quest for stable biomimetic repair of teeth: Technology of resin-bonded composites

The rationale leading to the present generation of resin composites is surveyed. There are many sub-classes such as flowable materials with specialized clinical indications. But a simplistic categorization of resin-composite materials is inappropriate. It is better to appreciate the factors that have driven recent developments. These include the search for low shrinkage composites and for greater depth of cure. Other necessary features are good handling behavior and sufficient strength for load-bearing situations. The esthetic challenge is for materials with superior and life-like optical properties and it is important to identify products that are good in every critical property. Nanotechnology has led to certain improvements, but the possibilities and limitations of nanoparticles must be appreciated. In all these developments, the structure and properties of the host tissues are a challenge and inspiration. Thus materials that can emulate the features of enamel and dentin are the goal of biomimetic design.

The Silorane-based Resin Composites: A Review

This article aims to review the research done on the silorane-based resin composites (SBRC) regarding polymerization shrinkage and contraction stresses and their ability to improve the shortcomings of the methacrylate-based resin composites (MRBC). Special attention is given to their physical and mechanical properties, bond strength, marginal adaptation, and cusp deflection. The clinical significance of this material is critically appraised with a focus on the ability of SBRC to strengthen the tooth structure as a direct restorative material. A search of English peer-reviewed dental literature (2003-2015) from PubMed and MEDLINE databases was conducted with the terms "low shrinkage" and "silorane composites." The list was screened, and 70 articles that were relevant to the objectives of this work were included.

Polymer-Based Direct Filling Materials

After a brief review of current restorative materials and classifications, this article discusses the latest developments in polymer-based direct filling materials, with emphasis on products and studies available in the last 10 years. This will include the more recent bulk fill composites and self-adhesive materials, for which clinical evidence of success, albeit somewhat limited, is already available. The article also introduces the latest cutting edge research topics on new materials for composite restorations, and an outlook for the future of how those may help to improve the service life of dental composite restorations.

Durability of a low shrinkage TEGDMA/HEMA-free resin composite system in Class II restorations. A 6-year follow up

OBJECTIVE

The objective of this randomized controlled prospective trial was to evaluate the durability of a low shrinkage and TEGDMA/HEMA-free resin composite system in posterior restorations in a 6-year follow up.

METHODS

139 Class II restorations were placed in 67 patients with a mean age of 53 years (range 29-82). Each participant received at random two, as similar as possible, Class II restorations. In the first cavity of each pair the TEGDMA/HEMA-free resin composite system was placed with its 3-step etch-and-rinse adhesive (cmf-els). In the second cavity a 1-step HEMA-free self-etch adhesive was used (AdheSe One F). The restorations were evaluated using slightly modified USPHS criteria at baseline and then yearly during 6 years. Caries risk and parafunctional habits of the participants were estimated.

RESULTS

Three molar teeth showed mild post-operative sensitivity during 3 weeks for temperature changes and occlusal forces. After 6 years, 134 Class II restorations were evaluated. Twenty-one restorations, 8 cmf-els (11.4%) and 13 ASE-els (20%) failed during the 6 years (p<0.0001). The annual failure rates were 1.9% and 3.3%, respectively. The main reasons for failure were fracture followed by recurrent caries. Most fractures and all caries lesions were found in high risk participants.

SIGNIFICANCE

The Class II resin composite restorations performed with the new TEGDMA/HEMA-free low shrinkage resin composite system showed good durability over six years.

In Vitro Evaluation of Marginal Adaptation of Direct Class II Composite Restorations Made of Different “Low-Shrinkage” Systems

The present study evaluated the influence of various low-shrinkage restorative systems in class II direct composite restorations following simulated occlusal loading. Forty MOD class II cavities were prepared on freshly extracted human lower third molars with proximal margins located mesially 1.0 mm coronal to and distally 1 mm apical to the cementoenamel junction. The samples were randomly distributed into five experimental groups corresponding to the following restorative systems: a conventional resin composite (Tetric) as active control group, a low-shrinkage composite (Extra Low Shrinkage [ELS]) alone or combined with its corresponding flowable version (ELSflow) used as a 1- to 1.5-mm liner, a bulk-filling flowable composite (Surefil SDR) covered by a 1-mm layer of restorative composite (Ceram-X), and a restorative bulk-filling composite (SonicFill). All specimens were submitted to 1,000,000 cycles with a 100N eccentric load into saline. Tooth restoration margins were analyzed semiquantitatively by scanning electron microscopy before and after loading. The percentage of perfect adaptation to enamel varied from 94.15% (SonicFill) to 100% (ELS) before loading and from 69.22% (SonicFill) to 93.61% (ELS and ELSflow) after loading. Continuous adaptation to cervical dentin varied from 22.9% (Tetric) to 79.48% (SDR/Ceram-X) before loading and from 18.66% (Tetric) to 56.84% (SDR/Ceram-X) after loading. SDR/CeramX and SonicFill showed the best cervical dentin adaptation.

Clinical evaluation of fiber-reinforced composite crowns in pulp-treated primary molars: 12-month results

Objective:

The aim of this study was to evaluate the clinical performance of tooth-colored fiber-reinforced composite (FRC) crowns in pulp-treated second primary mandibular teeth.

Materials and Methods:

This split-mouth randomized, clinical trial performed on 67 children between 3 and 6 years with two primary mandibular second molars requiring pulp treatment. After pulp therapy, the teeth were randomly assigned to stainless steel crown (SSC) or FRC crown groups. Modified United States Public Health Service criteria were used to evaluate marginal integrity, marginal discoloration, and secondary caries in FRC crowns at intervals of 3, 6, and 12 months. Retention rate and gingival health were also compared between the two groups. The data were analyzed using Friedman, Cochran, and McNemar's tests at a significance level of 0.05.

Results:

Intact marginal integrity in FRC crowns at 3, 6, and 12 months were 93.2%, 94.8%, and 94.2%, respectively. Marginal discoloration and secondary caries were not found at any of the FRC crowns. The retention rates of the FRC crowns were 100%, 98.3%, and 89.7% at 3, 6 and 12 months, respectively, whereas all the SSCs were found to be present and intact after 12 months (P = 0.016). There was no statistically significant difference between the two groups in gingival health.

Conclusion:

According to the results of this study, it seems that when esthetics is a concern, in cooperative patients with good oral hygiene, FRC crowns can be considered as a valuable procedure.

Functional dendritic compounds: potential prospective candidates for dental restorative materials and in situ re-mineralization of human tooth enamel

This review provides a snapshot of recent progress in the synthesis and application of dendritic compounds as potential prospective candidates for dental restorative materials andin siture-mineralization of human tooth enamel.

Comparing marginal microleakage of three Bulk Fill composites in Class II cavities using confocal microscope: An in vitro study

Aim:

This study aims to evaluate and compare microleakage at the occlusal wall and cervical wall in Class II cavities restored with one SonicFill Bulk Fill composite and two conventional Bulk Fill composites.

Materials and Methods:

Thirty freshly extracted teeth were divided into three groups of 10 teeth each. Standardized Class II cavities were made on the mesial and distal surfaces of each tooth and restored using SonicFill Bulk Fill composite and two conventional Bulk Fill composites, Tetric Evo Ceram, and X-tra fil. After storage, thermocycling and immersion in 0.6% rhodamine dye solution specimens were sectioned and evaluated for microleakage at the occlusal and cervical walls using confocal microscope.

Statistical Analysis Used:

Kruskal-Wallis test, Wilcoxon Signed-Rank test and Mann-Whitney U-test.

Results:

The results demonstrated that in the occlusal wall and cervical wall, SonicFill Bulk Fill composite, showed significantly less marginal microleakage than the other groups.

Conclusion:

Based on the results of this study, SonicFill Bulk Fill composite showed less microleakage than the other conventional Bulk Fill composites.

Degree of Conversion and Hardness of a Silorane-Based Composite Resin: Effect of Light-Curing Unit and Depth

Purpose

To investigate the effect of different light-curing units and depths on the degree of conversion (DC) through Fourier transform infrared spectroscopy (FTIR) and Knoop Hardness Number (KHN) of a silorane-based composite resin (Filtek LS, 3M ESPE, St Paul, MN, USA) (LS).

Materials and Methods

LS specimens mounted in a particular designed matrix were photoactivated by three light-cure units (LCUs) at depths of 2, 3, 4, and 5 mm. The DC was determined in a FTIR spectrometer with an attenuated total reflectance accessory. The KHN was measured in an automatic microhardness tester. The results were analyzed using the Friedman and Spearman statistical tests (α=0.05).

Results

There was no effect of LCUs on the DC (p=0.472) or KHN (p=0.174) for all of the studied depths. The highest DC and KHN means were found at 2-mm depth, which were not statistically different from 3-mm depth, but were higher than 4-mm and 5-mm depths (p=0.007). Spearman analysis found a positive linear correlation between the variables KHN and DC (r=0.858, p&lt;0.000).

Conclusions

The LCUs' effect was not verified. Values of DC and KHN for LS decreased with increasing depth. The highest values for both DC and KHN were obtained at depths of 2-3 mm.

Three-year Clinical Evaluation of Different Restorative Resins in Class I Restorations

The aim of the present study was to evaluate the three-year clinical performance of a nanofilled resin composite, a packable resin composite, and silorane-based resin restorations in Class I occlusal cavities. Twenty-eight patients with at least three similar-sized occlusal lesions in molar teeth participated in the study. A total of 84 Class I occlusal restorations were placed: 28 with nanofilled resin composite (Filtek Supreme), 28 with packable resin composite (P60), and 28 with silorane-based resin (Filtek Silorane). Filtek Supreme and P60 were used with their respective etch-and-rinse adhesive system, Adper Single Bond 2, and Filtek Silorane was used with its respective self-etch adhesive, Filtek Silorane Adhesive. All restorations were placed by the same operator. The restorations were evaluated at baseline, at six months, and annually for three years according to modified US Public Health Service criteria by two calibrated examiners who did not know which restorative resin had been used. The three restorative materials for each category were compared using the χ2 test at a significance level of 0.05. Cochran's Q test was used to compare the changes across the five time points for each restorative material. McNemar's test followed by Bonferroni adjustment was used when significance differences were found. At the end of the three years, 60 restorations were evaluated in 20 patients, with a recall rate of 71.4%. The retention rate was 100% for all restorative resins. Eight restorations from the P60 group, ten from the Filtek Supreme group, and nine from the Filtek Silorane group were rated Bravo for marginal discoloration. For marginal adaptation, three P60, five Filtek Supreme, and 11 Filtek Silorane restorations were rated Bravo. No statistically significant differences in overall clinical performance were found between the restorative materials except for marginal adaptation. P60 showed the best marginal adaptation at the end of the three years. No differences were observed between the restorative resins for any of the evaluation criteria tested (p&gt;0.05). None of the restorations showed postoperative sensitivity, secondary caries, or loss of anatomic form. All restorative resins performed equally well in clinical conditions during the three-year evaluation, and no significant differences were found among them, except for marginal adaptation, in which P60 showed superior results.

Critical appraisal: bulk-fill flowable composite resins

Recent developed flowable composite resins have been marketed for bulk filling of preparations or replacement of dentin in a single increment. The obvious attraction of these materials-quicker placement of restorations-has rapidly made them very popular despite the limited in vitro data and lack of clinical studies. This Critical Appraisal will review some of the available in vitro literature on the topic and summarize the available knowledge in this new category of restorative materials.

Clinical evaluation of resin-based composites in posterior restorations: a 3-year study

OBJECTIVES

The aim of this study was to evaluate the clinical performance of a nanohybrid and a microhybrid composite in class I and II restorations after 3 years.

SUBJECTS AND METHODS

A total of 82 class I and class II restorations were performed in 31 patients (10 males and 21 females) using Grandio and QuiXfil with self-etch adhesives (Futurabond and Xeno III). The restorations were clinically evaluated by 2 operators 1 week after placement (baseline) and at 6 months and 1, 2, and 3 years using modified United States Public Health Service (USPHS) criteria. At the 3-year follow-up, 62 class I and class II cavities were reevaluated in 23 patients (7 males and 16 females). Statistical analysis was performed using Pearson's χ(2) and Fisher's exact tests (p < 0.05).

RESULTS

At the 6-month follow-up, all restorations received Alfa scores with respect to each evaluation criterion. At the 1-year follow-up, 2 QuiXfil restorations had to be replaced and Grandio restorations started to deteriorate in terms of marginal adaptation. At the end of 2 years, 9 Grandio restorations showed significant deterioration of the surface properties, demonstrating Bravo scores. At the end of 3 years, no significant differences were observed regarding color match, marginal adaptation, secondary caries, marginal discoloration, and anatomic form loss between the evaluated materials in 25 class I and 37 class II restorations. At the 3-year follow-up, Grandio restorations had 21% Bravo scores and showed significant deterioration of the surface properties, which were still clinically acceptable according to USPHS criteria. Three QuiXfil and 1 Grandio restorations were replaced because of secondary caries and loss of retention.

CONCLUSIONS

Both the nanohybrid (Grandio) and the microhybrid (QuiXfil) composites were clinically functional after 3 years.

Two-Year Clinical Performance of a Low-Shrinkage Composite in Posterior Restorations

Objectives

The aim of this study was to compare the two-year clinical performance of three restorative systems in posterior restorations, which included a low-shrinkage composite and both etch-and-rinse and self-etch adhesive strategies.

Materials and Methods

After signing an informed consent, 25 patients received three Class I (occlusal) or Class II restorations performed with one of three restorative systems: Filtek Silorane Restorative System, Adper Scotchbond 1 XT (a two-step etch-and-rinse adhesive) with Filtek Z250, and Adper Scotchbond SE (a two-step self-etch adhesive) with Filtek Z250. All materials were applied following the manufacturer's instructions. Two blind observers evaluated the restorations at three different moments (baseline; and after one and two years) according to the US Public Health Service modified criteria. Kruskal-Wallis test and Mann-Whitney U-test were used to compare the behavior of the restorative systems, while Friedman and Wilcoxon tests were applied to analyze the intra-system data (p&lt;0.05).

Results

The three restorative systems showed a statistically similar clinical performance at two years. Intra-system comparisons between baseline and two years showed declining marginal adaptation scores in the restorations placed with all systems. In addition, marginal staining and surface roughness scores were lower after two years for the restorations placed with Adper Scotchbond SE + Filtek Z250.

Conclusions

Although the clinical performance of Filtek Silorane was considered acceptable after two years, no advantage of the silorane-based resin over the methacrylate-based composite was found. Teeth restored with Adper Scotchbond SE showed a tendency for marginal staining, which may compromise the final color of the restorations.

Biofilm Formation on Composite Resins for Dental Restorations: An in Situ Study on the Effect of Chlorhexidine Mouthrinses

Purpose

Biofilm formation on the surface of dental restorative materials by oral bacteria is considered an important step in the development of secondary caries. The aim of this study was to evaluate the in situ effect of a chlorhexidine (CHX)-containing mouthrinse on the biofilm formation occurring on the surface of human enamel and of two resin-based commercially available materials: a silorane-based material (Filtek Silorane®) and a methacrylate-based material (Filtek Supreme XT®).

Methods

53 disks were obtained for each of the two composites and 37 disks for enamel. The surface was characterized by determining the surface roughness and the surface free energy of 5 samples for each of the three materials tested, then the remaining samples were mounted on splints worn by 16 volunteers. The participants were randomly divided into two groups: an experimental group that used 0.12% CHX-based mouthrinse and a control group that used a placebo mouthrinse. Biofilm formation on the different surfaces after a 24 h period was assessed using MTT assay.

Results

The two composites in the group treated with the placebo mouthrinse showed a similar biofilm formation, which was significantly higher than that occurring on enamel surfaces. The CHX-based mouthrinse significantly reduced biofilm formation on the surfaces of the two resin-based materials when compared with the placebo mouthrinse. The reduction was particularly relevant on the Filtek Silorane surfaces.

Conclusions

The new silorane-based material seems to interact with CHX in a promising way from the point of view of biofilm formation control.

Effect of using silorane-based resin composite for restoring conservative cavities on the changes in cuspal deflection

OBJECTIVE

To investigate the effect of using two resin-composite materials for restoring conservative mesio-occluso-distal (MOD) cavities on the changes (incremental and cumulative) in cuspal deflection.

METHODS

Forty extracted sound human maxillary second premolars were subjected to standardized MOD cavity preparation and then divided into two groups (n=20). The first group of teeth was restored with Filtek Z250 (3M ESPE, St Paul, MN, USA), and Filtek P90 (3M ESPE, St Paul, MN, USA) was used in the second group. Incremental cuspal deflection was calculated by measuring the intercuspal distance between the indexed cusp tips before the restoration and at five-minute intervals up to 30 minutes using a stereomicroscope connected to a digital camera. Cumulative cuspal deflection for both materials was also calculated.

RESULTS

Comparing the incremental cuspal deflection of the tested groups at each time interval, it was found that there was no significant difference immediately after curing and at five, 15, 20, and 25 minutes. However, a significant difference was recorded at 10 and 30 minutes. For the cumulative cuspal deflection, Filtek P90 showed significantly lower deflection values than Filtek Z250 only after five minutes.

CONCLUSIONS

Incremental cuspal deflections of both materials over the tested intervals were almost comparable. However, after five minutes of curing, silorane-based resin composite surpassed the methacrylate-based resin composite in controlling the cumulative cuspal deflection.