Dental Polymethyl Methacrylate Research Articles

Influence of Novel SrTiO3/MnO2 Hybrid Nanoparticles on Poly(methyl methacrylate) Thermal and Mechanical Behavior.

While dental poly methyl methacrylate(PMMA) possesses distinctive qualities such as ease of fabrication, cost-effectiveness, and favorable physical and mechanical properties, these attributes alone are inadequate to impart the necessary impact strength and hardness. Consequently, pure PMMA is less suitable for dental applications. This research focused on the incorporation of Strontium titanate (SrTiO3-STO) and hybrid filler STO/Manganese oxide (MnO2) to improve impact resistance and hardness. The potential of STO in reinforcing PMMA is poorly investigated, while hybrid filler STO/MnO2 has not been presented yet. Differential scanning calorimetry is conducted in order to investigate the agglomeration influence on the PMMA glass transition temperature (Tg), as well as the leaching of residual monomer and volatile additives that could pose a threat to human health. It has been determined that agglomeration with 1 wt% loading had no influence on Tg, while the first scan revealed differences in evaporation of small molecules, in favor of composite PMMA-STO/MnO2, which showed the trapping potential of volatiles. Investigations of mechanical properties have revealed the significant influence of hybrid STO/MnO2 filler on microhardness and total absorbed impact energy, which were increased by 89.9% and 145.4%, respectively. Results presented in this study revealed the reinforcing potential of hybrid nanoparticles that could find application in other polymers as well.

In Vitro Characterisation of 3D Printable Filaments Subjected to Edible Liquids: An Analysis of Fused Deposition Modelling for Intraoral Applicability.

To evaluate the influence of edible liquids on the characteristic properties of 3D printable materials compared to conventionally used dental resin acrylic. Dental polymethyl methacrylate (PMMA) specimens were fabricated from preformed molds while polylactic acid (PLA) and polyethylene terephthalate glycol (PETG) specimens were 3D printed using fused deposition modelling at 0.1 mm layer thickness. All specimen forms adhered to ISO 37:2017 and ISO 604:2002 specifications. Specimens underwent controlled immersion for 180 hr into different media (no immersion (control), oil, soda, milk, and caffeine). Changes in mass (g), plastic deformity (N/mm2), ultimate tensile stress (N), flexural deformity (N/mm2), and break force (N) were evaluated using analysis of variance. There was an increase in mass for all specimens following immersion with significant interactions between immersion media and the materials. The materials exhibited significant differences in plastic deformity (F (df) = 156.632(2), P < 0.001), ultimate tensile stress (F (df) = 109.521(2), P < 0.001), and break force (F (df) = 319.785 (2), P < 0.001) with no significant interactions with immersion media (P > 0.05) on both accounts. Materials showed no significant differences in flexural deformity (F (df) = 2.693(2), P = 0.074) but with significant interactions (F (df) = 4.984(8), P < 0.001) between acrylic and immersion media. Commercially available 3D printable PLA and PETG filaments printed at 0.1 mm thickness possess approximately half the mechanical resilience as dental PMMA with comparable flexural deformity after exposure to edible liquids.

A statistical model of the rate-dependent fracture behavior of dental polymer-based biomaterials.

An insight into the fracture behavior of dental polymer-based biomaterials is important to reduce safety hazards for patients. The crack-driven fracture process of polymers is largely stochastic and often dependent on the loading rate. Therefore, in this study, a statistical model was developed based on three-point bending tests on dental polymethyl methacrylate at different loading rates. The fracture strains were investigated (two-parameter Weibull distribution (2PW)) and the rate-dependency of the 2PW parameters were examined (Cramér-von Mises test (CvM)), arriving at the conclusion that there could be a limiting distribution for both quasi-static and dynamic failure. Based on these findings, a phenomenological model based on exponential functions was developed, which would further facilitate the determination of the failure probability of the material at a certain strain with a given strain rate. The model can be integrated into finite element solvers to consider the stochastic fracture behavior in simulations.

The use of graphene for dental polymethylmethacrylate reinforcement – A systematic review

Objectives: To produce a systematic review regarding the effect of graphene-reinforced polymethylmethacrylate used in dentistry on mechanical properties. Methods: Electronic databases (Pubmed/MEDLINE, Web of Science, Embase) were independently searched by two researchers for relevant studies published up to December 2021. An additional manual search was performed to identify relevant publications. The population, intervention, comparison, and outcome (PICO) question was “In dentistry, does graphene-reinforced polymethylmethacrylate offer better mechanical properties than conventional polymethylmethacrylate?”. The selection of articles was carried out according to the established inclusion and exclusion criteria, following the PRISMA flowchart. The inter-investigator reliability was assessed by Cohen’s Kappa coefficient. The risk of bias was assessed using the Joanna Briggs Institute Critical Appraisal Checklist for Quasi-experimental Studies. Results: Six in vitro studies were included in the qualitative analysis. A total of 247 specimens were evaluated: 81 made of non-reinforced PMMA resin and 166 of PMMA reinforced with graphene. The mechanical properties evaluated were flexural strength, flexural modulus, hardness, biaxial flexural strength, and impact strength. These properties seem to improve with the addition of graphene in certain concentrations. The analysis of the risk of bias showed low risk. Conclusions: Within the limitation of this study, graphene seems to strengthen some mechanical properties of PMMA dental resin. However, more studies are needed to understand the ideal graphene concentration to improve resin’s clinical performance.

Influence of Counterface Materials on the Tribological Behavior of Dental Polymethyl Methacrylate Reinforced by Single-Walled Carbon Nanotubes (SWCNT)

Influence of Counterface Materials on the Tribological Behavior of Dental Polymethyl Methacrylate Reinforced by Single-Walled Carbon Nanotubes (SWCNT)

Effects of graphene nanoplatelets and montmorillonite nanoclay reinforcement on dental polymethyl methacrylate

AbstractThe study aimed at developing a cytocompatible dental polymer composite with high mechanical and surface characteristics by reinforcing polymethyl methacrylate resin with graphene nanoplatelets and montmorillonite nanoclay. After ball milling the particles into the polymer samples were prepared via conventional compression molding method. Samples were tested for flexural strength, polishability, fatigue failure, wear, hardness, and cytotoxicity. The fracture mode and surface polish were tested using a field emission scanning electron microscope. Most properties displayed enhancement at the tested fraction weight in relation to the control, while some properties were downgraded. However, the tested polymer composite was cytocompatible at all concentrations. Within study limits, graphene nanoplatelets and montmorillonite nanoclay reinforced polymer brought about a positive effect to a particular degree. Establishing optimal concentration of reinforcement and alternate blending methods may boost the resultant characteristics of the resin composite.

Effect of heat polymerization conditions and microwave on the flexural strength of polymethyl methacrylate.

Objective:The objective of this study is the effect of different heat polymerization conditions on the strength of polymethyl methacrylate (PMMA) resin base is unknown. Distinguishing one method that provides improved mechanical properties may be beneficial to the clinical success of complete and partial dentures and overdentures. The purpose of this study was to evaluate the effect of different polymerization methods on the flexural strength of a dental PMMA resin.Materials and Methods:Forty PMMA specimens (64 mm × 10 mm × 4 mm) were prepared with 4 different polymerization methods (n = 10); heat polymerization at 74°C for 9 h, at 100°C for 40 min, and with 620 kPa pressure at 100°C for 20 min. The remaining group of specimens was microwave polymerized at 180 W for 6 min. All specimens were thermocycled at 5°C and 55°C for 5000 times. Three-point flexure test was used to measure the flexural strength of specimens. One-way ANOVA and Tukey Honestly Significant Difference were applied to analyze the differences in flexural strengths (α = 0.05).Results:The flexural strength of heat-polymerized groups was similar. The flexural strength of microwave polymerized group was significantly different and lower than the other groups (P < 0.05).Conclusion:Polymerizing conventional heat-polymerizing PMMA resin with microwave energy resulted in a significant decrease in flexural strength. The results of this study suggest that clinicians may benefit from using heat polymerization when processing PMMA denture bases instead of microvawe polymerization when tested brand is used.

Relationship between basic dental polymethyl methacrylate polymer roughness and surface topography and microbial biofilm formation using different polishing techniques

Aim. To determine the relationship between surface roughness and surface topography of the basic dental polymethyl methacrylate polymer polished by different methods and microbial adhesion of microorganisms (Porphyromonas gingivalis, Fusobacterium nucleatum and Streptococcus sanguis) and fungi (Candida albicans) causing periodontal diseases. Methods. Surface topography of the basic dental polymethyl methacrylate polymer was studied by atomic force microscopy; microbiological methods were used to study the adhesion of bacteria and Candida fungi causing periodontal diseases to the surfaces of the samples polished by different methods. Results. It was shown that Streptococcus sanguis had the highest adhesion degree to the polymer surface after milling, Porphyromonas gingivalis and Candida albicans had moderate, and Fusobacterium nucleatum - low adhesion degree. The adhesion dropped significantly after the sample had been polished in dental laboratory or using the «Ergo Boxing» compared to dental unit polishing, where the decrease was less significant. The article contains 2D- and 3D-atomic force microscopy pictures of polymer surface after different polishing methods use. Images obtained by atomic force microscopy clearly display the surface of the basic dental polymethyl methacrylate polymer polished by different methods. Conclusion. Polymer samples processed by «Ergo Boxing» and dental laboratories are characterized by minimal microbial adhesion when compared with other methods.

The effects of cyclic stress on dental polymethylmethacrylate. II. Flexural fatigue.

Mechanisms of fatigue failure in polymers and the aims of fatigue testing have been examined, and factors affecting testing summarized. In the light of available work in several fields, parameters have been suggested for realistic flexural fatigue testing of denture base resins. A testing machine has been developed, with which the changes in properties of acrylic resin after fatigue in different environments can be studied. These changes developed gradually after 10(4) cycles and were related to the development of bulk crazing rather than to thermal effects. The amount of decay in the elastic modulus was not such that the material could have been said to have "failed".

The effects of cyclic stress on dental polymethylmethacrylate. I. Thermal and environmental fluctuation.

Alternative resins to traditional denture base acrylic need to be assessed for both short- and long-term performance before their potential can be evaluated. Much dental materials testing is carried out on fresh material and a baseline of knowledge about the properties of aged material is incomplete. Studies have been carried out to examine the effects of thermal and environmental fluctuation on dental acrylic, with testing procedures reconsidered so as to resemble service conditions as closely as possible. Thermal cycling proved detrimental to the resin only when superimposed on intermittent partial drying out and resaturation.

A review of the properties of some denture base polymers

INTRODUCTION Acrylic denture base materials have been widely available in the United Kingdom for about 40 years. The loss of rubber supplies to the United Kingdom in 1942 completed the change over to acrylic resins which had really begun in 1935 with the introduction of Kallodent, in its injection moulded form, by Imperial Chemical Industries Ltd. The production of acrylic resin for dentistry is the now familiar dough moulding technique which was introduced by Kulzer shortly after Kallodent. This basic material and technique has remained as the denture base material of choice since that time, although various polymers have been developed for use in dentistry to overcome the strength deficiencies of polymethylmethacrylate (PMMA). Polymers such as the polyamides, epoxy resin, polystyrene, vinyl-acrylic, rubber graft polymers and polycarbonate have been used. Modification of PMMA and the addition of fillers has also been attempted. Over the past few years acrylic resin polymers have also been modified so that they could be used in a more versatile fashion and a review of the properties of these pour-type denture base resins has been published (Bates et al., 1977). The total amount of money spent on repairs to acrylic dentures in the National Health Service of England and Wales between 1948 and 1978 is reliably estimated at a figure of g27.9 million at a cost of JZ28.1 million (not allowing for variations in monetary value) (Dental Estimates Board, 1979) and so the strength of these resins is still a cause for concern. Further recent efforts have been made to improve these deficiencies by developing different polymers based upon dental PMMA, with the addition of rubbers. This produces a resin that consists of a matrix of PMMA within which is dispersed an interpenetrating network of rubber and PMMA. This leads to a situation where a developing crack accelerates in the PMMA, but decelerates whilst crossing the rubber phase, thus increasing the fracture resistance. It is therefore useful to review some of the physical and mechanical properties of a range of these higher strength polymers and compare them with other acrylic denture base resins.

Studies on the Fatigue Properties of Dental Plastics Materials

Dental plastic materials (most of them are polymethyl-methacrylate polymer) are commonly used for partial and full denture as prosthetic appliance. For the basic design of raising efficiency of these materials it is important to promote their experimental knowledge as to their fatigue strength which has not hitherto been sufficiently developed.So in this paper a report is made on the fatigue strength of these materials, the relation between the surface roughness and strength and the influence of the polymerization method employed on these materials.As the result of the experimental studies the following conclusions are made.There has been remarkable influence of the polymerization method on these materials which were finished with the emery paper, number 04. The wet heat polymerization is superior to the dry heating on the static and fatigue strength. The degeneration of fatigue strength of the dry heat polymerization is greater than the static properties and the surface roughness influences for fatigue strength.The influence of the finishing methods on the surface roughness is not seen in the results of the surface inspection but in their fatigue strength.In the comparative study of the dental materials with the engineering materials, the S-N curves of the dental materials show their continuous behavior, and their difference from polymethyl-methacrylate (PMMA) of the engineering materlais. And the degeneration of fatigue strength of dental PMMA materials is less than that of their static strength.