Contact angle and surface free energy of experimental resin-based dental restorative materials after chewing simulation

The chemical and optical stability evaluation of injectable restorative materials under wet challenge

OBJECTIVES

To investigate and compare the chemical and optical stability of four restorative composite materials: two injectable resins, one flowable resin and one compomer.

METHODS

Two injectable nano-filled composite resins: G-aenial Universal (GU) and Beautifil Injectable XSL (BI), a flowable composite resin: Filtek Supreme Flowable (FS) and a compomer: Dyract Flow (DF), in A2 shade were tested and compared. Water sorption and solubility were conducted according to ISO4049:2019 standard; ICP-OES and F-ion selective electrode were used to test the elemental release; Degree of conversion (DC) was obtained by using FTIR; water contact angle was obtained by static sessile drop method, and a spectrophotometer was used for optical properties (ΔE⁎, ΔL⁎ and TP). SPSS 28.0 was used for statistical analysis and the significant level was pre-set as α = 0.05.

RESULTS

GU performed the best in water sorption and solubility, FS had the lowest elemental release, the best colour stability, and the highest DCIM and DC24-h. DF, the compomer had the lowest, and GU and BI, the injectable composites had the largest water contact angle, respectively. Correlations were found between water sorption and water solubility.

CONCLUSIONS

The four composite restorative materials showed different chemical and optical behaviours. Overall, composite resins performed better than compomer, while additional laboratory and in vivo tests are necessary to obtain a more comprehensive comparison between injectable and flowable composite resins. Wsp and Wsl are influenced by many common factors, and the values are highly positively related.

CLINICAL SIGNIFICANCE

A comprehensive understanding of materials is crucial before selecting materials for clinical practice. Composite resins rather than compomers are recommended because of their exceptional properties, which make them eligible for a wide range of clinical applications and an elongated lifespan.

The effect of quaternary ammonium polyethylenimine nanoparticles on bacterial adherence, cytotoxicity, and physical and mechanical properties of experimental dental composites

A significant problem related to the functioning of resin-based composites for dental fillings is secondary or recurrent caries, which is the reason for the need for repeated treatment. The cross-linked quaternary ammonium polyethylenimine nanoparticles (QA-PEI-NPs) have been shown to be a promising antibacterial agent against different bacteria, including cariogenic ones. However, little is known about the properties of dental dimethacrylate polymer-based composites enriched with QA-PEI-NPs. This research was carried out on experimental composites based on bis-GMA/UDMA/TEGDMA matrix enriched with 0.5, 1, 1.5, 2 and 3 (wt%) QA-PEI-NPs and reinforced with two glass fillers. The cured composites were tested for their adherence of Streptococcus Mutans bacteria, cell viability (MTT assay) with 48 h and 10-days extracts , degree of conversion (DC), water sorption (WSO), and solubility (WSL), water contact angle (CA), flexural modulus (E), flexural strength (FS), compressive strength (CS), and Vickers microhardness (HV). The investigated materials have shown a complete reduction in bacteria adherence and satisfactory biocompatibility. The QA-PEI-NPs additive has no effect on the DC, VH, and E values. QA-PEI-NPs increased the CA (a favorable change), the WSO and WSL (unfavorable changes) and decreased flexural strength, and compressive strength (unfavorable changes). The changes mentioned were insignificant and acceptable for most composites, excluding the highest antibacterial filler content. Probably the reason for the deterioration of some properties was low compatibility between filler particles and the matrix; therefore, it is worth extending the research by surface modification of QA-PEI-NPs to achieve the optimum performance characteristics.

Surface Properties and Streptococcus mutans Biofilm Adhesion of Ion-Releasing Resin-Based Composite Materials

OBJECTIVE

To evaluate the adhesion of Streptococcus mutans (S. mutans) and related surface properties of ion-releasing resin-based composite (RBC) restorative materials.

METHODS

Two ion-releasing RBCs, Activa (ACT) and Cention-N (CN), were compared to a conventional RBC (Z350) and a resin-modified glass ionomer cement (Fuji-II-LC). Ten disk-shaped specimens were fabricated for each material (n=40). After standardized surface polishing procedure, the surface properties of the specimens were evaluated using surface roughness measurements by a profilometer and hydrophobicity using water contact angle measurements. To assess bacterial adhesion, the number of S. mutans bacteria was calculated from colony-forming units (CFU). Confocal laser scanning microscope analysis was done for qualitative & quantitative assessment. The data were analyzed using One-way ANOVA followed by Tukey's post-hoc test to compare the mean values of surface roughness, water contact angle and CFU values. To compare the mean dead cell percentage Kruskal-Wallis rank test and Conover test were used. A p-value of ≤ 0.05 was used to report the statistical significance.

RESULTS

Z350 and ACT had the smoothest surfaces, followed by CN, and the roughest surface was seen in FUJI-II-LC. The lowest water contact angles were seen in CN, and Z350, and the highest were in ACT. S. mutans counts were the highest in ACT and the lowest in Z350 and CN. CN and Fuji-II-LC registered the highest percentage of dead bacterial cells, while the lowest were in ACT.

SIGNIFICANCE

Surface properties did not significantly influence bacterial adhesion. More S. mutans bacteria accumulated on ACT than on the nanofilled composite and on CN. CN had antibacterial effects against Streptococcus mutans biofilms.

Biomaterials and Clinical Applications of Customized Healing Abutment-A Narrative Review

Customized healing abutments have been introduced in clinical practice along with implant surgery to preserve or create natural-appearing hard and soft tissue around the implant. This provides the benefits of reducing the overall treatment time by eliminating the second stage and reducing the elapsed time of the fabrication of the final prostheses. This article aims to review the types and properties of materials used for the fabrication of customized healing abutments and their clinical applications. Articles published in English on customized healing abutments were searched in Google Scholar, PubMed/MEDLINE, ScienceDirect, and the Scopus databases up to August 2022. The relevant articles were selected and included in this literature review. Customized healing abutments can be fabricated from materials available for dental implants, including PEEK, PMMA, zirconia, resin composite, and titanium. All the materials can be used following both immediate and delayed implant placement. Each material provides different mechanical and biological properties that influence the peri-implant tissues. In conclusion, the studies have demonstrated promising outcomes for all the materials. However, further investigation comparing the effects of each material on peri-implant soft and hard tissues is required.

The Influence of Modified Experimental Dental Resin Composites on the Initial In Situ Biofilm-A Triple-Blinded, Randomized, Controlled Split-Mouth Trial

The purpose of the study was to investigate the bacterial viability of the initial biofilm on the surface of experimental modified dental resin composites. Twenty-five healthy individuals with good oral hygiene were included in this study. In a split-mouth design, they received acrylic splints with five experimental composite resin specimens. Four of them were modified with either a novel polymeric hollow-bead delivery system or methacrylated polymerizable Irgasan (Antibacterial B), while one specimen served as an unmodified control (ST). A delivery system based on Poly-Pore^® was loaded with one of the active agents: Tego^® Protect 5000 (Antiadhesive A), Dimethicone (Antiadhesive B), or Irgasan (Antibacterial A). All study subjects refrained from toothbrushing during the study period. Specimens were detached from the splints after 8 h and given a live/dead staining before fluorescence microscopy. A Friedman test and a post hoc Nemenyi test were applied with a significance level at p < 0.05. In summary, all materials but Antibacterial B showed a significant antibacterial effect compared to ST. The results suggested the role of the materials’ chemistry in the dominance of cell adhesion. In conclusion, dental resin composites with Poly-Pore-loaded active agents showed antibacterial effectiveness in situ.

The effect of new anti-adhesive and antibacterial dental resin filling materials on gingival fibroblasts

OBJECTIVE

Aim of this study was to evaluate the biocompatibility of four experimental antiadhesive and antibacterial dental filling composites on human gingival fibroblasts (HGFs).

METHODS

For these experimental resin composites a delivery system based on novel polymeric hollow beads, loaded with Tego Protect (Aa1), Dimethicone (Aa2), Irgasan (Ab1) and methacrylated polymerizable Irgasan (Ab2) as active agents was used. The cultured HGFs' cell integrity, proliferation, viability, collagen synthesis and cytokine release were measured. For this purpose, human gingival fibroblasts were treated with eluates from all four composites and compared with an experimental standard composite (ST). Eluate extraction times 24 h and 168 h were chosen.

RESULTS

Statistical analysis was conducted via a mixed model. Both antibacterial composites reduced proliferation, collagen and cytokine synthesis significantly (p < 0.05), increasing with time of elution. Ab1 did also have a damaging effect on the membrane and on cell viability.

SIGNIFICANCE

Overall, it can be concluded that the antiadhesive composites showed clear advantages over the antibacterial composites in terms of biocompatibility. This study also continues to show the potential of the new poly-pore system, as it can be used for a variety of other applications in future composite mixtures.

Surface Testing of Dental Biomaterials-Determination of Contact Angle and Surface Free Energy

The key goal of this study was to characterize surface properties of chosen dental materials on the base on the contact angle measurements and surface free energy calculations. Tested materials were incubated in the simulated oral environment and drinks to estimate an influence of conditions similar to those in the oral cavity on wetting and energetic state of the surface. Types of materials were as follows: denture acrylic resins, composite and PET-G dental retainer to compare basic materials used in a prosthetics, restorative dentistry and orthodontics. The sessile drop method was used to measure the contact angle with the use of several liquids. Values of the surface free energies were estimated based on the Owens-Wendt, van Oss-Chaudhury-Good and Zisman's methods. The research showed that surface wetting depends on the material composition and storage conditions. The most significance changes of CA were observed for acrylic resins (84.7° ± 3.8° to 65.5° ± 3.5°) and composites (58.8° ± 4.1° to 49.1° ± 5.7°) stored in orange juice, and for retainers (81.9° ± 1.8° to 99.6° ± 4.5°) incubated in the saline solution. An analysis of the critical surface energy showed that acrylic materials are in the zone of good adhesion (values above 40 mJ/m²), while BIS-GMA composites are in the zone of poor adhesion (values below 30 mJ/m²). Study of the surface energy of different dental materials may contribute to the development of the thermodynamic model of bacterial adhesion, based on the surface free energies, and accelerate the investigation of biomaterial interaction in the biological environment.

Evaluation of surface characteristic and bacterial adhesion of low-shrinkage resin composites

This study aimed to examine the surface characteristics of low shrinkage composites and adhesion of Streptococcus mutans and Streptococcus mitis to these materials. Control material (glass) and three low shrinkage composites (Charisma Diamond, Kalore GC, Beatiful II LS) were used. After polishing procedure was applied to composite specimens, surface roughness (SR), surface free energy (SFE), and contact angle measurements were performed. Surfaces of composite were analyzed using scanning electron microscope and energy-dispersive X-ray spectroscopy. After pellicle formation with artificial saliva, S. mutans and S. mitis biofilms were incubated in 5% CO₂ for 24 h at 37°C and were analyzed using confocal laser scanning microscopy. The lowest SR and highest SFE values were found in the control group. While the contact angle of control was statistically lower than composites, statistically difference was not found between composite groups. S. mutans adhesion of composites was significantly lower than control group, but there was no significant difference between composites. S. mitis adhesion of all groups was statistically similar. SR did not affect the S. mutans and S. mitis adhesion. Less adherence of S. mutans to low shrinkage composites was associated with low SFE and high contact angle values. Even though the highest SR was observed in the Charisma Diamond, no difference was found between the composites in terms of bacterial adhesion.

In vitro precision evaluation of blue light scanning of abutment teeth made with impressions and dental stone casts according to different 3D superimposition methods

PURPOSE

The purpose of this in vitro study was to determine the precision evaluation of blue light scanning of abutment teeth impressions and dental stone casts according to different 3D superimposition methods.

METHODS

Impressions and dental stone casts of the maxillary canine, 1st premolar, and 1st molar were fixed; they were repeatedly scanned 11 times, (6 types, total n = 66). Stereolithography (STL) files were superimposed one by one, and used to obtain 10 root mean square (RMS) values with the 2 superimposition methods (best-fit-alignment, no control). Statistical analysis included the independent t test and one-way ANOVA with Tukey honest significant differences (α = 0.05).

RESULTS

RMS ± Standard Deviation (SD) values for the best-fit-alignment method of the abutment teeth impressions of the maxillary canine, 1st premolar, and 1st molar was 8.07 ± 0.76, 5.03 ± 0.23, and 6.59 ± 0.24, respectively, and those of the no control method were 9.36 ± 0.82, 7.10 ± 1.14, and 8.17 ± 0.36 respectively. RMS ± SD values for the best-fit-alignment method for the dental stone casts were 4.07 ± 0.27, 3.39 ± 0.07, and 3.29 ± 0.07, respectively, and those for the no control method were 6.26 ± 2.50, 4.98 ± 1.16, and 4.55± 0.74, respectively.

CONCLUSIONS

Using different 3D superimposition methods, blue light scanning of abutment teeth impressions and dental stone casts shows high precision. The no control method showed lower precision best-fit-alignment. However, the results may help advance the digital dental CAD/CAM research and the clinical field of Prosthodontics.

Laser-Aided Enamel Conditioning: A Comparison of Microleakage Under Brackets Following Different Aging Procedures

Objective:

To evaluate microleakage under the orthodontic adhesives applied following two version of erbium:yttrium aluminum garnet (Er:YAG) laser-aided enamel conditioning after thermal and thermomechanical simulators.

Materials and Methods:

A comparative analytical study based on metal braces bonded on the enamel of extracted teeth ( n = 160) etched with acid, Er:YAG laser and Er:YAG laser with an X-Runner handpiece, and self-etch adhesives. An arch wire was ligatured to samples which were embedded in acrylic blocks by two with periodontal ligaments. The specimens were subdivided into two groups: those aged with thermal cycling and thermomechanical aging procedures. The samples were immersed in basic fuchsin solution (0.5%) for 24 h. Buccolingual sections were performed on the mesial and distal wings of the braces. The color penetration at the gingival and occlusal margins of the adhesive-bracket and enamel-adhesive was evaluated under a stereomicroscope. The median and mean values of microleakage in both groups were evaluated with Kruskal–Wallis and Mann–Whitney U tests ( P < .05).

Results:

The highest microleakage was recorded in the gingival part of the samples aged with the thermomechanical aging procedure ( P = .001). The amount of microleakage generally increased in the samples subjected to thermomechanical loading, but the only significant difference was recorded in the gingival part in each four different conditioning methods.

Conclusion:

Microleakage of the phosphoric acid-etched groups was recorded with lower values for both aging methods. Thermomechanical aging should be included to microleakage studies due to increased microleakage on gingival side for all etching groups.

Silver nanoparticle-loaded hydroxyapatite coating: structure, antibacterial properties, and capacity for osteogenic induction in vitro

AgNP-HAC has the potential to be used on the surfaces of orthopedic and dental implants for infection prophylaxis.

Inverse Gas Chromatographic Examination of Polymer Composites

Inverse gas chromatographic characterization of resins and resin based abrasive materials, polymerpolymer and polymer-filler systems, as well as dental restoratives is reviewed.