Open Sandwich Research Articles

Gallatabenzene Ligands Emerging from Open Lutetocene and Yttrocene Methyl Complexes.

Utilizing ternary mixtures [LnMe3]n/K(2,4-dtbp)/GaMe3(Ln = Lu, Y; 2,4-dtbp = 2,4-di-tert-butyl-pentadienyl), a series of metallacycles is accessible via tandem salt metathesis/deprotonation.Depending on the precursor molar ratio, both gallatabenzene and lutetacyclic moieties with fully planar metallacycles are obtained, which were further analyzed using DFT calculations. The precursor molar ratio affects the extent of pentadienyl C-H-bond activation and oligomerization to tetra- and pentametallic arrays. Reacting a 1:2:2 mixture at -40 °C gave the open sandwich methyl complex (2,4-dtbp)2Lu(CH3), displaying a vital intermediate for subsequent ring-closure reactions.

Vibration analysis of functionally graded carbon nanotube‐reinforced composite open cylindrical shells with damping film embedded

AbstractIn the present study, a discrete layer model was established to explore the vibration performance of Functionally Graded Carbon Nanotube‐Reinforced Composite (FG‐CNTRC) open cylindrical shells with damping film embedded based on the first‐order shell theory. There are four configurations of stacking arrangements considered for FG‐CNTRC open cylindrical shells with damping film embedded. The equivalent structural parameters of the top and bottom FG‐CNTRC panels are generated by implementing the extended mixing rule. Governing equations are derived based on the Hamilton principle and solved with the Naiver solution. Subsequently, after verifying the validity of this paper's solution by comparing it with the published literature, a parametric elaborated investigation discloses the variation patterns of vibration performance of four FG‐CNTRC open cylindrical shells with damping film embedded. The conclusions of the study can be used as a useful guide about open cylindrical composite shell structures with the design of high strength and damping.Highlights Discrete layer vibration model was bulit based on first‐order shell theory. Vbration performance of FG‐CNTRC open sandwich shells was studied. Variation patterns of frequency and loss factor was disclosed.

Long-term patient-reported outcome measures (PROMs) after primary ventral or small midline incisional hernia repair.

Ventral hernia repair is a common elective surgical procedure lacking strong evidence for specific operative approaches. This study aimed to evaluate the outcomes of primary suture repair or polypropylene sandwich mesh repair for ventral hernias. The main outcome measures were the rate of hernia recurrence, and evaluation of long-term complications and patient-reported outcomes. This retrospective cohort study evaluated patient perceived recurrence and pain in patients who had undergone a primary ventral hernia (epigastric, supraumbilical, or umbilical) repair or small (≤20 mm) midline incisional hernia repair 10 years after the procedure. Short-term follow-up occurred up to 6 weeks after the initial operation, while long-term follow-up included patients who were reviewed clinically or interviewed via telephone at or beyond 3 years after the procedure. Most (75/100, 75.0%) patients had an extra-peritoneal sandwich mesh repair. Short-term follow-up showed minimal pain and normal activities for all patients (97/97, 100%). Long-term follow-up (median 12 years [IQR 11-13]) was achieved in 95.9% (93/97) of patients with only a small number reporting a slight bulge (5/93, 5.4%) and intermittent mild discomfort (8/93, 8.6%). Nine patients (9/97, 9.3%) experienced hernia recurrence, diagnosed at a median of 26 months [interquartile range, IQR, 7-58] post-operatively. These findings suggest that an open sandwich mesh technique is a safe and effective method for repairing primary ventral hernias and small midline incisional hernias and is associated with favourable long-term patient-reported outcomes.

СИСТЕМАТИЧЕСКИЙ ОБЗОР МЕТОДОВ ВОССТАНОВЛЕНИЯ ПРОКСИМАЛЬНЫХ ПОЛОСТЕЙ ЖЕВАТЕЛЬНЫХ ЗУБОВ: СОВРЕМЕННОЕ СОСТОЯНИЕ И ПЕРСПЕКТИВНЫЕ ТЕХНОЛОГИЧЕСКИЕ ДОСТИЖЕНИЯ

Relevance. To maintain dental health and maintain the normal structure of the dental system, a deep understanding of methods for restoring lost dental tissue is necessary. When restoring class II carious lesions, open and closed sandwich techniques were used, as well as various methods of manipulating composite materials. Systematization of existing research will allow the dentist to better navigate the available techniques and provide better treatment to his patients. Aim: To conduct a systematic review of the effectiveness of the method for restoring proximal contacts of posterior teeth. Materials and methods. As part of the study, a systematic analysis of the technique for restoring contact points of teeth was carried out, in compliance with established criteria. Initial data were obtained by searching the Google Scholar, ScienceDirect, PubMed, ResearchGate, CyberLeninka and eLIBRARY.RU databases using the following key terms: «recovery methods», «contact point», «open sandwich», «closed sandwich», «filling technique», «point of contact», «closed centripetal», «open centripetal». Results. To conduct a systematic review, 7 articles were reviewed on the seal quality of restorations made using the open sandwich, closed sandwich, and total bonding methods. In 85% of cases, the open sandwich method was indicated by the authors as the most appropriate for creating sealed class 2 restorations. Conclusions. The best tightness of restorations in in vitro studies in 85% of cases was achieved using the technique of filling an open sandwich. The tightness of the restoration not only affects the choice of material, but also prevents its application. Further comparative in vivo studies on the survival of class 2 restorations made using the open sandwich or total bonding method are needed.

Long term clinical performance of 'open sandwich' and 'total-etch' Class II composite resin restorations showing proximal deterioration of glass-ionomer cement.

To compare clinical performance of resin composite posterior Class-II restorations placed with etch-and-rinse adhesive or open sandwich technique using glass-ionomer cement. Data on Class II restorations placed by one dentist between 1990 and 2016 were collected from patient files, including caries risk, tooth related variables, applied materials and dates of last check-up visit and restoration placement. Open sandwich restorations were placed before 2001, while after 2001, a total-etch technique using etch-and-rinse 3-step adhesive was used when placing a Class II composite restoration. For statistical analysis, Kaplan-Meier statistics and a multilevel Cox-Regression was conducted (p<0.05). Annual Failures Rates (AFR) were calculated. 675 Class II restorations were placed in 91 patients, 491 total-etch restorations (observation time 2-18y), and 184 open sandwich restorations (observation time 19-29y) showing AFRs at 15 years as 2.9% for total-etch and 9.7% for open sandwich restorations. Secondary caries as failure was equally distributed among the 2 groups and 27% of the failures in the open sandwich group were due to proximal deterioration of glass-ionomer cement. The Cox-regression showed a significant higher risk for failure for the open sandwich technique compared to total-etch class-II composite restorations (HR=2.9; p<0.001). Application of glass-ionomer cement using the open sandwich technique cannot be recommended for class-II restorations as being more complex and showing poorer clinical performance.

Effect of RMGI Roughness and Dentin Bonding Primer on Shear Bond Strength of Sandwich-type Restorations.

The open sandwich technique is a reliable alternative to amalgam placement in deep proximal box preparations, where proper isolation and enamel bonding may not be possible. It is often difficult to prepare the box for composite placement without affecting the resin-modified glass ionomer (RMGI) that has been placed in the gingival portion. We hypothesized that RMGI surfaces that are roughened or those that use all steps in the manufacturing bonding protocol, including the priming solution, applied before placing a bonded composite increment, would have greater composite/RMGI shear bond strength. Shear bond strengths (SBS) of RMGI tested in the presence and absence of SiC roughening and primer-coating were tested using a fourth-generation dentin bonding agent to composite after thermocycling. Twenty specimens for four test conditions were fabricated and investigated. Data were subjected to a two-way ANOVA and the Holm-Sidak post-hoc test. Placing dentin primer on unabraded RMGI provided a statistically significant improvement in SBS, but only modestly. Furthermore, because bond failure consistently occurred within the RMGI itself, none of the surface modifications have a clinically relevant impact on SBS at the RMGI to the composite interface. Clinicians should be aware that they need not avoid RMGI abrasion and do not need to incorporate all components of a fourth-generation bonding system when covering an RMGI sandwich layer with composite.

Evaluation of the Outcome of Modified Open Sandwich Technique and Conventional Composite Resin Restoration: For Managing Class II Cavity of Primary Molars Among 4- 8 years Old Children

Background: Dental caries is the most prevalent disease in humans, especially during early childhood. The restoration of such an extensive carious lesion should be done properly to reestablish their anatomy and hence their masticatory, phonetic, esthetic, and space-maintainer functions in the dental arches. Composite resins are the most commonly used tooth-colored restorative material, but many difficulties occur particularly when used directly in posterior restorations. The objective of the study was to compare the clinical effectiveness of the Modified Open Sandwich Technique and Conventional Composite Resin Restoration for managing class II caries on primary molars. Material &amp; Methods: This was a randomized control trial and was conducted in the Department of Pedodontics, Faculty of Dentistry, Bangabandhu Sheikh Mujib Medical University (BSMMU), Dhaka, Bangladesh during the period from October, 2021 to September, 2022. In our study we included 68 patients with proximal dental caries of primary molars with reversible pulpitis. The patients were divided by using random sampling technique into two groups – Group A (The modified open sandwich technique, n=34) and Group B (The conventional composite resin restoration, n=34). Results: In total 68 patients from both the groups completed the study. In our study we found mean±SD of age was 5.37±1.24 years. 76.5% of cases of the modified open sandwich technique restorations were &amp; 82.4% of the conventional composite resin restoration were &lt; 6 years. Mandibular primary molars were 64.7% and 53% for the modified open sandwich technique and conventional composite resin restoration respectively. Conventional composite resin restorations showed 32.4% postoperative sensitivity and the modified open sandwich technique restorations showed 11.8%. After 12 months of follow-up, no secondary caries developed. Good marginal adaptation in 100% of cases were found in the modified open sandwich technique and 88.2% for conventional composite restorations. Conclusion: In our study we found that postoperative sensitivity developed more in conventional composite restorations in comparison to the modified open sandwich technique. Initially marginal adaptation showed better in the modified open sandwich method technique. So, conventional and modified open sandwich composite resin techniques were acceptable for primary molar teeth considering secondary caries and marginal adaptation.

Comparison of Marginal Compliance and Microleakage of CL V Restorations in Deciduous Anterior Teeth Using Two Different RMGI Liners

Introduction: Microleakage has always been a problem in restorative dentistry. To decrease microleakage, different restorative techniques and materials have been recommended. The purpose of this study was to evaluate micro leakage of the composite restoration in deciduous anterior teeth using the open sandwich technique by two different liners.&#x0D; Materials &amp; Methods: This cross-sectional experimental study was conducted at Khorasgan University in 2019. A total of sixty intact deciduous canine teeth were divided into 3 groups of 20. At the buccal surface of the specimens, the Class V cavity was extracted at 1 mm below the CEJ (Cementoenamel junction) and in groups 1 and 2, ionoseal liner and Fuji II ionomer glass were placed at the buccal floor. Cavities were restored with Z250 composite resin. In group 3 which served as the control, restorations was perfromed without liners. All samples are prepared for establishment after dying in methylene blue 0.5% solution. The buccal lingual incisions with a thickness of 1 mm were inspected under stereo microscope for micro leakage. A total of 5 samples were extracted from each group via random sampling to examine the marginal compliance under SEM (Scanning electron microscope). The intergroup comparisons were made using the chi-square and Kruskal-Wallis tests. Besides, intra-group comparisons were performed using the Mann-Whitney U test. All statistical procedures were performed at a significance level of less than 0.05 (p value &lt; 0.05) using Gpower software.&#x0D; Results: The outcome of this study showed that microleakage of gingival margin in open sandwich techniques with ionoseal and Fuji II (group 1, 2) was significantly higher than in control group (p value = 0.033).but in comparison between group 1,2 there was no significant difference (p value = 0.795). In SEM evaluation there was no significant difference in gingival microleakage (p value = 0.232).&#x0D; Conclusion: Use of two liners: Ionoseal and Fuji II in Class V cavities restored by opensandwich technique in deciduce anterior teeth can reduce gingival microleakage.

Evaluation of Marginal Microleakage in Class II Composite Restorations Using Open Sandwich and Snowplow Techniques

Introduction: Adaptation of posterior composites to dental walls has been questioned for various reasons and polymerization shrinkage is one example. Thus, the present study investigated microleakage ocurring from different class II composite restorations techniques.&#x0D; Materials and Methods: In this in-vitro study class II cavities with cervical margins 1 mm below the CEJ (Cementoenamel junction) were prepared in 64 extracted human premolars. The teeth were randomly divided into two groups. Group 1 (open sandwich): Glass ionomer was injected on the floor of the cavity and the rest of the cavity was restored using composite resin using incremental technique. Group 2 (Snowplow) one layer of flowable composite was placed in the bottom of the cavity and was co-cured with the first layer of composite resin. The rest of the cavity was restored the same as group 1. To evaluate the microleakage, the specimens were thermocycled for up to 3000 cycles and immersed in 1% methylene blue solution for 72 hours. Then they were sectioned mesiodistally and evaluated under a stereomicroscope. Data were analyzed via Mann-Whitney and Fishers exact test and p value &lt; 0.05 was considered significant.&#x0D; Results: The mean value for microleakage in group 1 (795.74 ± 494.04 mμ) was lower than group 2 (972.99 ± 457.8 mμ), but the results were not statistically significant (p value = 0.117).&#x0D; Conclusion: It appears that microleakage in both open sandwich technique and Snowplow technique did not portray statistical significance, so both of them can be used.

Effect of methyl substituents on the preferred conformations of Bis(pentadienyl) open metallocenes

Density functional theory (DFT) methods indicated that the preferred geometries, spin states, and energetics of unsubstituted bis(pentadienyl)metal open sandwich complexes (C5H7)2M of the first row transition metals (M = Ti to Ni) are similar to those of the corresponding substituted and more stable (2,4-Me2C5H5)2M open sandwich complexes with 2,4-dimethylpentadienyl ligands. Structures with two fully bonded pentahapto η5-C5H7 ligands are energetically preferred for iron and for the transition metals to the left of iron in the Periodic Table. However, for the electron-rich first-row transition metals cobalt and nickel, structures with at least one trihapto η3-C5H7 ligand are preferred in order to prevent the electron configuration of the central metal atom from exceeding the favored 18-electrons. For the manganese systems (C5H7)2Mn and (2,4-Me2C5H5)2Mn the presence of the two methyl substituents is found to have little effect on the complicated potential energy surface with low-energy structures in the doublet, quartet, and sextet spin states.

In vitro marginal and internal adaptation of four different base materials used to elevate proximal dentin gingival margins.

BackgroundThere is still debate about the most appropriate restorative material category to relocate the proximal deep cervical margins, thus, this study aimed to compare the marginal and internal adaptation of four base materials used for deep margin elevation, and to evaluate each base material/overlying composite interface. Material and MethodsFifty six molars received class II cavities with dentin/cementum gingival margins. They were divided into four groups and their gingival margins were elevated using either; resin modified glass ionomer (RMGI), highly viscous conventional glass ionomer (HV-GIC), flowable bulk fill resin composite (Bulk Flow) and bioactive ionic resin (Activa). The rest of the cavities were completed with the same overlying composite. Half of each group was either; kept in sterile water for 1 week, or subjected to 18 months water storage and 15,000 thermal cycles. Base materials/gingival dentin interfaces were examined under a scanning electron microscope at different magnifications, and percentage of continuous margin (% CM) and maximum gap width (MGW) were analyzed, in addition to base materials/overlying composite interfaces evaluations. % CM values were statistically analyzed using Two-way analysis of variance, Tukey post hoc tests (at p<0.05) and Pearson’s correlation while MGW values were analyzed using Kruskal–Wallis, Mann–Whitney U tests and Spearmen correlation ResultsBoth Bulk Flow and Activa had better marginal integrity than RMGI and HV-GIC. All base materials were adversely affected by aging. All base materials/overlying composite interfaces were continuous and age defying. ConclusionsIn terms of marginal integrity, Bulk Flow and Activa might be preferable for proximal dentin margin elevation under direct restoration compared to the other tested base materials. Key words:Deep proximal margin, interface analysis, marginal quality, open sandwich technique.

Insight into through-space conjugation in rotation-restricted thermally activated delayed fluorescence compounds

Two pairs of rotation-restricted TADF compounds via through-space charge transfer are investigated. Sandwich molecules exhibit similar photophysical properties and better electroluminescent performance compared with the open sandwich counterparts.

Deep proximal margin rebuilding with direct esthetic restorations: a systematic review of marginal adaptation and bond strength.

This review aimed to characterize the effect of direct restorative material types and adhesive protocols on marginal adaptation and the bond strength of the interface between the material and the proximal dentin/cementum. An electronic search of 3 databases (the National Library of Medicine [MEDLINE/PubMed], Scopus, and ScienceDirect) was conducted. Studies were included if they evaluated marginal adaptation or bond strength tests for proximal restorations under the cementoenamel junction. Only 16 studies met the inclusion criteria and were included in this review. These studies presented a high degree of heterogeneity in terms of the materials used and the methodologies and evaluation criteria of each test; therefore, only a descriptive analysis could be conducted. The included studies were individually evaluated for the risk of bias following predetermined criteria. To summarize the results of the included studies, the type of restorative material affected the test results, whereas the use of different adhesive protocols had an insignificant effect on the results. It could be concluded that various categories of resin-based composites could be a suitable choice for clinicians to elevate proximal dentin/cementum margins, rather than the open sandwich technique with resin-modified glass ionomers. Despite challenges in bonding to proximal dentin/cementum margins, different adhesive protocols provided comparable outcomes.

Consideration of concrete and steel sandwich tunnel elements

To date, super-long road tunnels were only realised in reinforced concrete, fabricated in a dry-dock such as at Busan Geoje or in an industrial facility such as used at the Øresund and the HZMB link. The length, width and depth of the Shenzhong link however required consideration of a wider pallet of technical solutions and an extensive study to transverse and longitudinal concepts was undertaken. Although the recommended option for the immersed tunnel section was based on more criteria the structural and constructability issues turned out to be decisive in the selection of the preferred option. The results from a structural comparison between a reinforced concrete, post-tensioned concrete, open sandwich and full sandwich tunnel are described and discussed followed by the accompanying specific constructability issues. Before going into the calculations a brief outline of the Shenzhong project is given and innovations and lessons learned from other recently constructed projects of interest for steel construction are summarized. Criteria like durability, robustness, overall risk profile, construction time, sustainability and construction costs were taken into account during the design process but are not described in this paper.

Incubation Period, Spore Shedding Duration, and Symptoms of Enterocytozoon bieneusi Genotype C Infection in a Foodborne Outbreak in Denmark, 2020.

BackgroundMicrosporidia are rarely reported to cause outbreaks of diarrhea. We describe a foodborne outbreak of microsporidiosis from a workplace canteen in November 2020 in Denmark.MethodsA probable case was defined as any person using the canteen between 4 November and 13 December 2020, reporting at least one gastrointestinal symptom, whereas a confirmed case also had an Enterocytozoon bieneusi positive stool sample. A web-based questionnaire was used to collect clinical, epidemiological, and food exposure data. We performed a retrospective cohort study and tested stool samples from affected individuals for bacterial, viral, and parasitic pathogens, including E. bieneusi.ResultsAltogether, 195 individuals completed the questionnaire. We identified 52 cases (65% male; median age 45 years [range 25–65]). Diarrhea (90%), fatigue (83%), and abdominal pain (79%) were the most commonly reported symptoms. Eight cases were laboratory-confirmed and had E. bieneusi genotype C. The incubation period was between 5 and 12 days, and polymerase chain reaction (PCR)-detectable spore shedding occurred up to 43 days after symptom onset. Disease was associated with consuming food from the workplace canteen on 4 November 2020 (relative risk [RR[, 2.8 [95% confidence interval [CI]: 1.4 – 5.4]) and lunchboxes containing open sandwiches (RR, 3.2 [95% CI: 1.4 – 7.2]) served that day.ConclusionsThis is the second documented foodborne outbreak of E. bieneusi genotype C-associated diarrhea worldwide. Epidemiological findings advocated an open sandwiches lunchbox from 4 November 2020, as a likely source. E. bieneusi may be an under-reported cause of outbreaks of diarrhea, and testing for it might be useful in foodborne outbreak investigations.

Controllable Synthesis and Enhanced Photoactivity of Two‐Dimensional Bi2WO6 Ultra‐Thin Nanosheets

AbstractTwo‐dimensional Bi2WO6 ultra‐thin nanosheets were controllably synthesized by a cetyltrimethylammonium bromide (CTAB)‐assisted hydrothermal method. The structure, morphology, energy gap, and thickness of the samples were characterized by X‐ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), atomic force microscopy (AFM), (diffuse reflection spectroscopy) DRS, and so on. The photocatalytic activity of the samples was analyzed by the degradation of rhodamine B. The photocatalytic performance of the ultrathin nanosheets was much enhanced nearly 3.5 folds higher than that of Bi2WO6 nanoparticles, which was attributed to the narrow band gap and the open sandwich structure, resulting in the improved light harvesting and the rapid separation and transfer of the photoinduced charge carriers. According to the radical trapping results, the dominant active species involving in the photocatalytic process were determined.

An enhanced open sandwich immunoassay by molecular evolution for noncompetitive detection of Alternaria mycotoxin tenuazonic acid

Open sandwich enzyme-linked immunosorbent assay (OS-ELISA), a novel noncompetitive immunoassay format, has shown great potential in rapid detection for small molecules compared with traditional competitive format. Here, an enhanced OS-ELISA towards the mycotoxin tenuazonic acid (TeA) was developed for the first time based on heavy chain variable region (VH) and light chain variable region (VL) from the hybridoma cells (3F10) producing anti-TeA monoclonal antibody (mAb). The established OS-ELISA exhibited a limit of detection of 0.08 ng/mL, and was 13 times more sensitive than mAb-based indirect competitive ELISA (ic-ELISA). The proposed assay was also applied to detect TeA contents in juice, flour and tomato ketchup samples with satisfactory recoveries of 87.6%–111.3%. Finally, the great accuracy of the established OS-ELISA method was validated by the standard ultra-performance liquid chromatography/tandem mass spectrometry (UPLC-MS/MS).

Open sandwich fluorescence-linked immunosorbent assay for detection of soy isoflavone glycosides

To detect major soy isoflavone glycosides, namely daidzin (DZ) and genistin (GEN), novel open sandwich fluorescence-linked immunosorbent assay (os-FLISA) was developed by taking advantage of enhanced interactions between variable regions of heavy (VH) and light chain (VL) domains in the presence of an antigen. The VH and VL genes were expressed in Escherichia coli as a chimera protein with green fluorescence protein (AcGFP1) and maltose-binding protein (MBP), respectively. Comprehensive characterization of os-FLISA displayed nearly the same specificity as parental DZ- and GEN-specific monoclonal antibody, demonstrating the potential of the developed assay for detection of both DZ and GEN. Their detectable range in this system exhibited at 0.1–12.5 μg mL−1. Subsequent validation analysis revealed that os-FLISA was reliable and accurate system for detection of total soy isoflavone glycosides. Notably, this is the first FLISA based on an open sandwich system, which can be employed for the detection of small molecules.

Effects of Resin-modified Glass Ionomer Cement and Flowable Bulk-fill Base on the Fracture Resistance of Class II Restorations: An Original Laboratory Experimental Study

The purpose of this study was to investigate the fracture resistance of marginal ridges restored using different techniques (amalgam, open sandwich technique, and incremental placement) and to compare these with smart dentin replacement (SDR) bulk-fill. Amalgam, dispersalloy; a nanohybrid resin composite (Tetric N Ceram), a resin-modified glass ionomer cement (RMGIC) base (Fuji II LC), and flowable bulk-fill composites (SureFil SDR) were used. Standardized class II (occluso-distal) OD cavities were prepared on 60 (n = 12) extracted premolars, and five different protocols were used to restore the teeth: group 1, dispersalloy; group 2, dispersalloy with 4 mm Fuji II LC base; group 3, incrementally placed Tetric N Ceram; group 4, Tetric N Ceram with 4 mm Fuji II LC base; and group 5, Tetric N Ceram with SureFil SDR. The restorations were thermocycled then fractured using a universal testing machine, the maximum fracture load of the specimens was measured (N), and the type of fracture was recorded. Statistical analysis was carried out using one-way analysis of variance. Amalgam groups showed the lowest fracture resistance, with no significant difference between the based and nonbased groups. The highest fracture resistance was displayed by Tetric N Ceram with SDR base, and it was significantly higher than all the groups except the Tetric N Ceram nonbased group. The RMGIC based Tetric N Ceram displayed intermediate fracture resistance. The majority of the restorations showed mixed types of fracture except for nonbased amalgam, which mostly failed cohesively through amalgam. SDR-based composite was the only group that showed severe tooth failures. The use of a 4 mm thick RMGIC base had no detrimental effect on the fracture resistance of class II amalgam and composite restorations. Bulk-fill SureFil SDR placed under a conventional resin-based composite had similar fracture resistance to incrementally placed composite but higher than amalgam and composite restorations based on RMGIC.

Acid Resistance of Glass Ionomer Cement Restorative Materials.

In view of the need for aesthetics, restorations of teeth will typically be completed using tooth colored restorative materials. With the advent of biomimetic restorative materials, such as glass ionomer cements (GIC), much greater emphasis is now being placed on how well such materials can resist the challenge of acids that are present in foods and drinks, or gastric contents that are regurgitated. This laboratory study compared the dissolution and behavior of five GIC materials (GC Fuji® VII, GC Fuji® Bulk, GC Fuji® IX Fast, Fuji® IX Extra and GC Equia® Forte Fil) when exposed to three acids (citric acid, phosphoric acid and lactic acid), versus ultrapure deionized water, which was used as a control. Discs of each material GIC were submerged in solutions and percentage weight changes over time determined. Subsequently, the GIC materials were also placed as a part of standardized Class II sandwich restorations in bovine teeth (n = 20), and submerged in the solutions, and the extent of GIC dissolution and protection of the adjacent tooth was scored. Weight loss increased with time and with acid concentration. Overall, the most soluble material was GC Fuji® IX Extra, while GC Fuji® IX Fast and GC Fuji® Bulk were less soluble, and the least soluble material was GC Equia® Forte Fil. The most destructive solution for both the discs and for GIC restorations in teeth was 10% citric acid, while the least destructive acid was 0.1% lactic acid. The more recent GIC materials GC Fuji® Bulk and GC Equia® Forte Fil showed increased acid resistance over the older GIC materials, and this further justifies their use in open sandwich Class II restorations in more hostile environments.