Methacrylate Research Articles

Candidal Adhesion to an Oral Obturator PMMA Resin Incorporated with Vanillin

An oral obturator is a prosthesis used for a variety of dental conditions to help patients regain their abilities after trauma, surgeries, or having congenital defects. It is commonly made from polymethyl methacrylate (PMMA) resin. Despite that, this resin appliance can give rise to a condition for microbial adhesion and colonization on the resin surface itself and the mucosa beneath. This can place patients at a greater risk of infection. Oral infections caused by Candida species are found to be more common, particularly in immunologically compromised patients and those with other conditions in the oral cavity that often include oral prosthetic appliances. Obturator resin incorporated with vanillin has been produced and shown to have antimicrobial properties against some bacteria and yeasts. The purpose of this study was to determine the adhesion of candida to vanillin incorporated obturator resin. The auto-polymerized resin samples (Orthocryl® EQ, Dentaurum, Germany) were prepared with different concentrations of vanillin incorporation (0.1%, 0.5%, and 1% vanillin w/w). All samples were coated with sterile saliva and incubated at 37 °C for 60 min. The adhesion assay was done with four species of candida (C. albicans ATCC 10231, C. krusei ATCC 14243, C. glabrata ATCC 15126, and C. tropicalis ATCC 1369). The resin samples were placed in a 24-well plate containing 107 CFU/mL of candidal suspension and incubated in a shaking incubator (120 r/min) at 37°C for 2 h for candidal adhesion. Non-adherent cells were removed by washing with phosphate buffer saline (PBS) solution. The remaining adherent cells on the obturator resin surface were quantified by the WST Microbial Cell Counting Kit (Dojindo Molecular Technologies, USA). The Kruskal-Wallis test, followed by Dunn’s method, was applied for statistical analysis. The results showed that the addition of 0.5% and 1% w/w vanillin to oral obturator PMMA resin could significantly reduce the adhesion of all Candida species except that of C. krusei, for which a reduction effect was observed at 1 % vanillin. The percentage reduction of candidal adhesion on obturator resin varies from 9% to 35%, which was highest on C. albicans, followed by C. glabrata (24%), and C. tropicalis (21%). No reduction effect was observed at 0.1% vanillin on all Candida species. In conclusion, vanillin-incorporated oral obturator resin displayed a reducing effect on the adhesion of all tested Candida species. C. albicans was the most susceptible species, while C. krusei was the most resistant. The mechanisms of action could possibly be the aldehyde group of the vanillin structure that causes cell membrane damage, interferes with DNA, RNA, and protein synthesis, as well as enzyme activities within the yeast cell. This newly developed PMMA resin could be valuable for the prevention or as an adjunctive treatment for controlling oral candidal infection among patients who use oral obturators.

SLA printing of POSS-containing, bio-based composites with low dielectric constant and shape-memory function

Improving sustainability and functionality of resins is important for the development of 3D printing technologies. This work demonstrates a novel bio-based and low dielectric resin containing polyhedral oligomeric silsesquioxane (POSS) for stereolithography (SLA) printing to fabricate sensors and shape memory materials with complex geometry. Epoxidized soybean oil (ESO) and methacrylic acid are used to synthesize a biobased methacrylate resin (MESO) via a ring-opening reaction, followed by incorporation of POSS into polymer matrix. In general, the viscosity of POSS/MESO composite resins is in the range of 0.40–0.58 Pa s, making them viable for SLA printing designs. With the addition of 5 wt% POSS, POSS/MESO composites can exhibit excellent mechanical properties, including tensile strength (18.9 MPa), elongation at break (19.8%), and toughness (399.2 MJ/m3). Furthermore, these materials have a very low dielectric constant of 2.97 at 1 MHz, which is desired for microelectronic applications to overcome signal delay and energy loss. In addition, presence of permanent and reversible networks formed by MESO and POSS endows the POSS/MESO composites with good shape memory property. The application demonstrators include fabrication of flexible interdigital electrode sensors and temperature-responsive sensors. Overall, this work provides great potential opportunities to design the bio-based functional sensor with on-demand control over structures by SLA printing.

Photocrosslinkable, Injectable Locust Bean Gum Hydrogel Induces Chondrogenic Differentiation of Stem Cells for Cartilage Regeneration.

Due to the limited therapeutic efficacy of current treatments, articular cartilage regeneration is still challenging work. Scaffold-based tissue engineering provides a promising strategy for cartilage regeneration, but most scaffolds are limited by poor mechanical properties or unfavorable biocompatibility. Here, a novel photocrosslinkable, injectable locust bean gum (LBG)-methacrylate (MA) hydrogel is reported as a biomimetic extracellular matrix (ECM) for cartilage repair with minimal invasive operation. LBG-MA hydrogels show controllable degradation rate and improve mechanical properties and excellent biocompatibility. More importantly, LBG-MA hydrogel significantly induces bone mesenchymal stem cells to chondrogenic differentiation in vitro, as evidenced by high accumulation of cartilage-specific ECM components glycosaminoglycan and upregulated expression of key chondrogenic genes (collagen type II, aggrecan, and sex determining region Y-box9). Besides, the hydrogel is injectable, which can be in situ crosslinked via UV irradiation. Further, the photocrosslinkable hydrogels accelerate cartilage healing in vivo after 8 weeks of therapy. A strategy is provided here for photocrosslinkable, injectable, biodegradable scaffold fabrication based on native polysaccharide polymer for minimal invasive cartilage repair.

Synthesis of a Liquid Lignin-Based Methacrylate Resin and Its Application in 3D Printing without Any Reactive Diluents.

3D printing of bio-based and renewable polymers such as lignin has gained research attention during the last few decades. We report on the synthesis and characterization of a liquid lignin-based photopolymer and its application in additive manufacturing (AM). Wheat straw soda lignin is liquified in an oxyalkylation reaction with propylene oxide under alkaline conditions and modified with methacryloyl chloride to obtain a lignin-based methacrylate resin. Ninety percent of the functional hydroxyl groups are grafted during the synthesis. The photopolymerization efficiency was evaluated by real-time-NIR-photorheology experiments with two different photoinitiators, leading to double bond conversions (DBC) of ≥80%. 3D-printing experiments of the methacrylated lignin were performed with the hot lithography technology. For the first time, a light-curable lignin derivative with a lignin content of over 30% was successfully 3D printed via vat photopolymerization without any reactive diluents, which is a significant improvement over current state-of-the-art solutions. This outstanding result is a motivating proof of concept and a promising starting point for the in-depth evaluation of bio-based precursors as an alternative to nonrenewable derivatives for 3D printing.

Bacterial Adhesion on Dental Polymers as a Function of Manufacturing Techniques.

The microbiological behavior of dental polymer materials is crucial to secure the clinical success of dental restorations. Here, the manufacturing process and the machining can play a decisive role. This study investigated the bacterial adhesion on dental polymers as a function of manufacturing techniques (additive/subtractive) and different polishing protocols. Specimens were made from polyaryletherketone (PEEK, PEKK, and AKP), resin-based CAD/CAM materials (composite and PMMA), and printed methacrylate (MA)-based materials. Surface roughness (Rz; Ra) was determined using a laser scanning microscope, and SFE/contact angles were measured using the sessile drop method. After salivary pellicle formation, in vitro biofilm formation was initiated by exposing the specimens to suspensions of Streptococcus mutans (S. mutans) and Streptococcus sanguinis (S. sanguinis). Adherent bacteria were quantified using a fluorometric assay. One-way ANOVA analysis found significant influences (p < 0.001) for the individual parameters (treatment and material) and their combinations for both types of bacteria. Stronger polishing led to significantly (p < 0.001) less adhesion of S. sanguinis (Pearson correlation PC = -0.240) and S. mutans (PC = -0.206). A highly significant (p = 0.010, PC = 0.135) correlation between S. sanguinis adhesion and Rz was identified. Post hoc analysis revealed significant higher bacterial adhesion for vertically printed MA specimens compared to horizontally printed specimens. Furthermore, significant higher adhesion of S. sanguinis on pressed PEEK was revealed comparing to the other manufacturing methods (milling, injection molding, and 3D printing). The milled PAEK samples showed similar bacterial adhesion. In general, the resin-based materials, composites, and PAEKs showed different bacterial adhesion. Fabrication methods were shown to play a critical role; the pressed PEEK showed the highest initial accumulations. Horizontal DLP fabrication reduced bacterial adhesion. Roughness < 10 µm or polishing appear to be essential for reducing bacterial adhesion.

Lignin-derived new hydrogen donors for photoinitiating systems in dental materials

ObjectivesThe aim of this study is to develop amine free photo-initiating system (PIs) for the photopolymerization of dental methacrylate resins, using seven new hydrogen donors HDA-HDG derived from β-O-4 lignin model. MethodsSeven experimental CQ/HD PIs were formulated with Bis-GMA/TEGDMA (70 w%/30 w%). CQ/EDB system was chosen as the comparison group. FTIR-ATR was used to monitor the polymerization kinetics and double bond conversion. Bleaching property and color stability were evaluated using a spectrophotometer. Molecular orbitals calculations were used to demonstrate C-H bond dissociation energies of the novel HDs. Depth of cure of the HD based systems were compared to the EDB based one. Cytotoxicity was also studied by CCK8 assay using tissue of mouse fibroblasts (L929 cells). ResultsCompared to CQ/EDB system, the new CQ/HD systems show comparable or better photopolymerization performances (1 mm-thick samples). Comparable or even better bleaching properties were also obtained with the new amine-free systems. Comparing to EDB, all HDs exhibited significantly lower C–H bond dissociation energies by molecular orbitals calculations. Groups with new HD showed higher depth of cure. OD and RGR values were similar to that of the CQ/EDB group, ensuring the feasibility of the new HDs in dental materials. Clinical significanceThe new CQ/HD PI systems could be potentially useful in dental materials, presenting improvements in restorations' esthetic and biocompatibility.

Fatigue Resistance of Dissected Lower First Molars Restored with Direct Fiber-Reinforced Bridges—An In Vitro Pilot Study

The aim of this research was to evaluate the mechanical impact of utilizing different fiber-reinforced composite (FRC) systems to reinforce inlay-retained bridges in dissected lower molars with different levels of periodontal support. A total of 24 lower first molars and 24 lower second premolars were included in this study. The distal canal of all molars received endodontic treatment. After root canal treatment, the teeth were dissected, and only the distal halves were kept. Standardized class II occluso-distal (OD) (premolars) and mesio-occlusal (MO) (dissected molars) cavities were prepared in all teeth, and premolar-molar units were created. The units were randomly distributed among four groups (n = six/group). With the aid of a transparent silicone index, direct inlay-retained composite bridges were fabricated. In Groups 1 and 2, both discontinuous (everX Flow) and continuous (everStick C&B) fibers were used for reinforcement, while in Groups 3 and 4, only discontinuous fibers (everX Flow) were used. The restored units were embedded in methacrylate resin, simulating either physiological periodontal conditions or furcation involvement. Subsequently, all units underwent fatigue survival testing in a cyclic loading machine until fracture, or a total of 40,000 cycles. Kaplan-Meyer survival analyses were conducted, followed by pairwise log-rank post hoc comparisons. Fracture patterns were evaluated visually and with scanning electron microscopy. In terms of survival, Group 2 performed significantly better than Groups 3 and 4 (p < 0.05), while there was no significant difference between the other groups. In the case of impaired periodontal support, a combination of both continuous and discontinuous short FRC systems increased the fatigue resistance of direct inlay-retained composite bridges compared to bridges that only contained short fibers. Such a difference was not found in the case of sound periodontal support between the two different bridges.

Dentist ‘An Arsenal’ in the Journey of ‘Tooth in the Eye’-the Osteo-Odonto-Kerato-Prosthesis [OOKP

Background: Global blindness is mainly due to Cataract, after this Corneal disease is the major cause. For end stage corneal disease, the only successful treatment is by providing Osteo-Odonto-Kerato-Prosthesis (OOKP). The dental surgeon will play a vital role in this surgeon. After extracting a canine tooth from the patient, the dental surgeon places the acrylic lamina in the centre of the dentine (Dental Lamina) which acts like an ocular lens, later the Ophthalmic surgeon will place the same in the patient’s blind eye to get vision.&#x0D; Review Results: After electronic search was done on the role of dental surgeon and OOKP , through PubMed, Scopus, Web of Science, Wiley Online, Science Direct Ebscohost and Google Scholar for articles published from 1960 to July 2022, using the Key words, Osteo-Odonto-Kerato Prosthesis (OOKP), Modified Osteo-Odonto-Kerato Prosthesis (MOOKP), Osteo-Odonto-Alveolar Lamina, Corneal Disease Tooth-in-Eye, and Poly Methyl Meth Acrylate (PMMA) Cylinder, finally 14 articles were found to be relevant for the present research topic.&#x0D; Conclusion: Studies shows OOKP is providing vision and the success rate more than 85%. Not a single study mentioned the importance of a dental surgeon in OOKP surgery.&#x0D; Clinical Significance: Though the dental curriculum not mentioned directly about the role of a dentist in the OOKP surgery, but all the dental surgeons should have knowledge on OOOKP Surgery.

Comparison of the color stability and surface roughness of 3-unit provisional fixed partial dentures fabricated by milling, conventional and different 3D printing fabrication techniques

ObjectivesTo compare the color stability and surface roughness of 3-unit provisional fixed partial dentures (FPDs) fabricated by milling, conventional, and different 3D printing fabrication techniques. MethodsA total sample of 160, 3-unit FPDs were subdivided into four groups; subtractive milled resin (SM), two 3D printed resins (Stereolithography; SLA and Digital Light Processing; DLP) and conventional self-cured polymethyl methacrylate resin (CM). Surface roughness (Ra) was assessed twice; at baseline (Ra1) and after artificial tooth brushing (Ra2). Color of the samples was measured after immersion in four different solutions (cola, coffee, black tea and distilled water) at three time intervals (1, 7 and 30 days). Comparisons of the Ra and the color change (∆E00) were done using one-way ANOVA followed by multiple pairwise comparisons using Bonferroni adjusted significance level. Comparisons of the Ra at two stages (Ra1 and Ra2) were done using paired t-test. Univariate linear regression was performed followed by multivariable regression to assess the association between ∆E00 and different factors (materials, solution, and time). Significance was set at P value <0.05. ResultsThe highest change in Ra following artificial tooth brushing was reported in the CM group, while the lowest change was reported in the SM group, with a significant difference between both groups (P<0.001). SM group had significantly lower ∆E00 than the CM group followed by 3D printed SLA and DLP groups (P<0.001). Storage in coffee for 30 days showed the highest ∆E00 values (P<0.001). ConclusionsSM resin showed the least surface roughness and color change followed by 3D printed SLA resin. The difference in printing technology affected the tested properties with improved readings of 3D printed SLA resin. Clinical significanceMilled provisional FPDs showed higher surface smoothness and color stability than those fabricated by SLA printing technology, but with no significant difference between both groups. Therefore, SLA printed resins can be an adequate substitute to milled resins in the fabrication of provisional FPDs to overcome the high expenses of milled provisional FPDs.

Redox Polyelectrolytes with pH-Sensitive Electroactive Functionality in Aqueous Media

A framework of ferrocene-containing polymers bearing adjustable pH- and redox-active properties in aqueous electrolyte environments was developed. The electroactive metallopolymers were designed to possess enhanced hydrophilicity compared to the vinylferrocene (VFc) homopolymer, poly(vinylferrocene) (PVFc), by virtue of the comonomer incorporated into the macromolecule, and could also be prepared as conductive nanoporous carbon nanotube (CNT) composites that offered a variety of different redox potentials spanning a ca. 300 mV range. The presence of charged non-redox-active moieties such as methacrylate (MA) in the polymeric structure endowed it with acid dissociation properties that interacted synergistically with the redox activity of the ferrocene moieties to impart pH-dependent electrochemical behavior to the overall polymer, which was subsequently studied and compared to several Nernstian relationships in both homogeneous and heterogeneous configurations. This zwitterionic characteristic was leveraged for the enhanced electrochemical separation of several transition metal oxyanions using a P(VFc0.63-co-MA0.37)-CNT polyelectrolyte electrode, which yielded an almost twofold preference for chromium as hydrogen chromate versus its chromate form, and also exemplified the electrochemically mediated and innately reversible nature of the separation process through the capture and release of vanadium oxyanions. These investigations into pH-sensitive redox-active materials provide insight for future developments in stimuli-responsive molecular recognition, with extendibility to areas such as electrochemical sensing and selective separation for water purification.

Graphene-Doped Polymethyl Methacrylate (PMMA) as a New Restorative Material in Implant-Prosthetics: In Vitro Analysis of Resistance to Mechanical Fatigue

Provisional prostheses in restorations over several implants with immediate loading in completely edentulous patients increase the risk of frequent structural fractures. An analysis was performed of the resistance to fracture of prosthetic structures with cantilevers using graphene-doped polymethyl methacrylate (PMMA) resins and CAD-CAM technology. A master model was produced with four implants measuring 4 mm in diameter and spaced 3 mm apart, over which 44 specimens representing three-unit fixed partial prostheses with a cantilever measuring 11 mm were placed. These structures were cemented over titanium abutments using dual cure resin cement. Twenty-two of the 44 units were manufactured from machined PMMA discs, and 22 were manufactured from PMMA doped with graphene oxide nanoparticles (PMMA-G). All of the samples were tested in a chewing simulator with a load of 80 N until fracture or 240,000 load applications. The mean number of load applications required for temporary restoration until the fracture was 155,455 in the PMMA-G group versus 51,136 in the PMMA group. Resistance to fracture under cyclic loading was three times greater in the PMMA-G group than in the PMMA group.

Synthesis and evaluation of a novel polycarbonate grafted poly (glycidyl methacrylate) resin for sorption of 131I

To synthesize Q[A(PC-g-PGMA), Glycidyl Methacrylate (GMA) was grafted onto Polycarbonate (PC) using a radiation-induced grafting technique, followed by amination and quaternization. It was studied how total concentration, monomer concentration, and absorbed dosage affect the degree of grafting (DG). FTIR, SEM, and TGA were used to describe the structure of the resultant Q[A(PC-g-PGMA)]. Q[A(PC-g-PGMA)] was utilized in a batch procedure to investigate the sorption efficiency of 131I in varied concentrations of HCl and/or HNO3 solutions. The results showed that 0.01 M HNO3 is the optimum medium for high retention of 131I, with a maximum capacity of 187 mg/g. The kinetic and isotherm data of 131I adsorption revealed that it followed the Pseudo-second-order and Freundlich models, respectively. The sorption process of 131I was discovered to be endothermic and spontaneous after studying thermodynamic parameters such as enthalpy change (ΔH°), free energy change (ΔG°) and entropy change (ΔS°).

In vitro comparison of the color degradation of two computer-aided design/computer-aided manufacturing provisional materials: A 12-month simulation.

This study evaluated the color aging of two computer aided design/computer aided manufacturing (CAD/CAM) provisional materials of different compositions (polymethyl methacrylate and composite resin) after exposure to thermal aging and immersion in coffee for 3, 6, and 12 intraoral months. The current in vitro study was conducted from September to December 2021 at the Craniofacial laboratory at the Saint Joseph University in Beirut, Lebanon. The shades of 2.0 mm thick, 10.0 mm in diameter disk shaped specimens of VITA CAD Temp® and Ceramill® TEMP were measured using the VITA Linearguide 3D MASTER® and a conversion table to extract the CIE LFNx01aFNx01bFNx01 values on a white background (n = 30). The color differences ΔE at 3, 6, and 12 months were calculated and analyzed by repeated measures ANOVA followed by Bonferroni multiple comparisons, univariate analyses, and one sample t tests. The mean ΔET1/T0, ΔET2/T0, and ΔET3/T0 values were significantly higher than the cutoff values for acceptability and perceptibility for the VITA CAD Temp® and the Ceramill® TEMP groups. In addition, the increase in ΔE overtime was significantly greater in the Ceramill® TEMP group compared to the VITA CAD Temp® group. The Ceramill® TEMP changed color more and faster than the VITA CAD Temp®. In addition, whether at 3, 6, or 12 months, the color variations of both materials are not only perceptible but also unacceptable compared to the initial shade.

Chemical characterization of silanized silver nanoparticles impregnated in poly (methyl methacrylate) resin: An in vitro study.

The intention was to determine the chemical interaction of silanized AgNPs with PMMA by Fourier transform infrared (FTIR) spectroscopy. In-vitro comparative study. This study is composed of four groups - 0.75% AgNP, 1.0% AgNP, 1.5% AgNP impregnated with PMMA, and nonimpregnated PMMA as control. The chemical nature of silanized AgNPs was studied using FTIR study. The results showed the appearance of new peak between 1727/cm and 1436/cm, i.e., 1636.476/ cm, 1645.886/cm, and 1646.885/cm, representing the C = C stretch in the experimental groups, i.e., 2, 3, and 4, respectively. This peak confirms that coupling agent has chemically interacted with PMMA. It can be concluded that the AgNPs coated with the silane coupling agent TMSPM has chemically reacted with PMMA.

Comparative evaluation of impact strength of mechanically modified heat polymerized polymethyl methacrylate (PMMA) resin with addition of 0.5, 1, 2 wt% of silver nanoparticles (AgNPs): An in-vitro study.

Polymethyl methacrylate (PMMA) is one of the most widely used denture base material because of favorable esthetics and desirable characteristics such as easy handling. Acrylic resins, although, have some inherent disadvantages such as relatively poor physical and mechanical properties. The objective of the present study was to evaluate and compare the impact strength of unmodified and modified heat cure PMMA-based denture base material with addition of different concentrations of silver nanoparticles (AgNPs) (0.5, 1, 2 wt%). The present in-vitro study comprised of a total of 60 samples allocated to four groups with Group A samples consisting of heat cure acrylic resin without any modification (used as control); Group B samples consisting of heat cure acrylic resin modified with 0.5 wt% of AgNPs; and subsequently, Group C and Group D samples consisting of heat cure acrylic resin modified with 1 wt% and 2 wt% of AgNPs, respectively. The impact strength of the prepared acrylic samples was evaluated using Izod/Charpy Impact Tester, while the values obtained were tabulated and subjected to statistical analysis. Statistical analysis was done using Statistical Package for Social Sciences (SPSS) version 17.0 (SPSS Inc., Chicago, IL, USA), while one-way analysis of variance and Tukey's multiple post-hoc procedures were used for statistical analysis. P < .05 was considered statistically significant. The highest impact strength was found in Group C samples consisting of heat cure acrylic resin modified with 1 wt% of AgNPs to be closely followed by Group B samples consisting of heat cure acrylic resin modified with 0.5 wt% of AgNPs. Group D samples consisting of heat cure acrylic resin modified with 2 wt% of AgNPs, although, revealed relatively lower impact strength compared to Group B and Group C samples. Within the limitations of the present study, it was concluded that the impact strength of mechanically modified heat polymerized PMMA resin was significantly enhanced with addition of varying concentrations of AgNPs, although, it was observed that with an increase in the concentration of AgNPs, a subsequent decrease in the tensile strength of the final polymer material was observed.

Comparative evaluation of the flexural strength of two different CAD/CAM-milled PMMA for long-term fixed provisional restorations

Aim:To determine and compare the flexural strength (FS) of heat-cured poly methyl methacrylate (PMMA) resin,CAD/CAM-milled PMMA resin, and CAD/CAM-milled PMMA resin reinforced with graphene. Materials and methods:In accordance with ISO 10477:2018, thirty rectangular samples with measurements of25 mm (l) x 2 mm (b) x 2 mm (h) were manufactured for the purpose of FS evaluation (Dentistry-polymer-basedcrown and veneering materials). PMMA resin samples that were heat-cured (Group-I; n = 10), CAD/CAM-milled(Group-II; n = 10), and CAD/CAM-milled PMMA resin reinforced with graphene (Group-III; n = 10) were producedand sorted according to the kind of material. Before testing, the samples were kept for a full day in distilledwater. For each of the thirty samples, a 3-point bend test was conducted utilizing a universal testing machine ata crosshead speed of 1.0mm/min till breakage. Utilizing a One-way ANOVA and thepost hocTukey HSD test, theFS data were tabulated and statistically analyzed. Results:For the test samples in Group I, the mean flexural strength was 550.29 MPa. For Group II the mean flexuralstrength was 1481.966 MPa. For Group III the mean FS was 1447.45 MPa. A comparative assessment of Group Itest samples, Group II test samples, and Group III test samples showed that the mean FS is highly significant(P&lt;0.001 ). On multiple comparisons, the mean FS difference between Group I test samples and Group II testsamples was observed to be highly significant (P&lt;0.01 ). The mean FS difference between Group I test samplesand Group III test samples was observed to be highly significant (P&lt;0.01 ). The mean FS difference betweenGroup II and Group III was observed to be insignificant (P&gt;0.05). Conclusion:CADCAM-milled PMMA resin showed the maximum FS followed by CADCAM-milled PMMAresin reinforced with graphene and heat-polymerized PMMA. Therefore, CADCAM PMMA–based polymerscould be utilized for long-term provisional restorations in comparison to heat-polymerized poly methylmethacrylate (PMMA) resin.

Correção Cirúrgica de Desvio Angular Metatársico em uma Potra Puro-sangue Utilizando Ostectomia em Cunha: um relato de caso

Abstract This study describes a corrective procedure for a metatarsal angular malformation using wedge ostectomy in a 41-day-old Thoroughbred filly. A 41.6 °angular malformation of the metatarsus was corrected with wedge ostectomy of the left hindlimb in association with a type II external fixator and methyl methacrylate resin. The animal was subjected to the surgical procedure under general anesthesia. The filly was placed in dorsal recumbency with the left hind limb free for manipulation. A bone saw was used for the wedge ostectomy, while the bars for external fixation were placed using a drill. A Kirschner pin and acrylic resin were then applied. Radiographic images obtained immediately after surgery confirmed a total malformation reduction of 32.6 (from 41.6° to 9°). With medication and a Robert Jones bandage, intensive postoperative care was instituted to ensure that the animal adapted properly to the linear external fixator without overloading the pins and connection bars. No postoperative complications were observed. On the day after surgery, the filly was standing and walking with no signs of pain. After 180 days, total osseous calcification was achieved, and the implants were removed during the second surgery. The filly demonstrated adequate locomotion, performed all the movements, and ran without any difficulty in the paddock. The remaining discrete angular deviations were partially corrected using hoof trimming.

Effect of Incorporation of Boron Nitride Nanoparticles on Impact Strength and Surface Roughness of Heat Cure Poly Methyl Methacrylate Resin: An In Vitro Study

Background: The objective of this research was to explore how the addition of boron nitride (BN) nanoparticles in the concentrations of 1% and 1.5% w/w affect the impact strength and surface roughness of heat-cured poly methyl methacrylate resin (PMMA). Methods: Sixty specimens were made from heat-cured acrylic resin and then divided into control, 1%, and 1.5% w/w BN groups. The impact strength and surface roughness were investigated. One-way ANOVA and Tukey’s post hoc test were used for data analysis. Results: Statistically significant difference is found among the three study groups regarding impact strength (P = 0.011) and surface roughness test (P < 0.001). The post hoc test showed significant differences for all multiple comparisons for the surface roughness test (P < 0.001). Yet, multiple comparisons for the impact strength test revealed only a significant difference between the 1.5% BN and control groups (P = 0.005). Conclusion: The addition of boron BN into PMMA improves impact strength with 1.5% concentration; while adversely increase the surface roughness.

Effects of adding functionalized graphene oxide nanosheets on physical, mechanical, and anti-biofilm properties of acrylic resin: In vitro- experimental study

Background: Polymethyl methacrylate resin is widely used in orthodontic treatments. Graphene oxide (GO) has reactive functional groups on its surface that facilitate binding to various materials such as polymers, biomolecules, DNA, and proteins. This study aimed to investigate the impact of adding functionalized GO nanosheets on the physical, mechanical, cytotoxicity, and anti-biofilm properties of acrylic resin.Materials and Methods: In this experimental study, fifty samples (for each test) were divided into groups of 10, in the form of acrylic resin discs with concentrations of 0, 0.25, 0.5, 1, and 2 weight percentage (wt%) of functionalized GO nanosheets and also the control group. Samples were evaluated in terms of physical properties (surface hardness, surface roughness, compressive strength, fracture toughness, and flexural strength), anti-biofilm properties (On four groups of micro-organisms, including Streptococcus mutans, Streptococcus sanguis, Staphylococcus aureus, and Candida albicans), and cytotoxicity. Data were analyzed using SPSS software version 22, descriptive statistics, one-way analysis of variance test, and Tukey post hoc test. The significance level was considered P < 0.05.Results: No significant difference was observed between the different groups with weight percentages of 0.25, 0.5, 1, and 2% nano GO (nGO) and the control group (without nGO) in terms of surface roughness and toughness. However, compressive strength, three-point flexural strength, and surface hardness showed significant differences between the groups. Furthermore, the degree of cytotoxicity increased by increasing the weight percentage of nano-GO.Conclusion: The addition of functionalized nGO in appropriate concentrations to polymethyl methacrylate can improve the anti-bacterial and anti-fungal biofilm properties without changing or increasing their physical and mechanical properties.

Effects of Microwave and Light Emitting Diode as Disinfection Methods on the Dimensional Stability of Polymethyl Methacrylate and Polyamide Denture Base Resin

Objective: To compare the effects of microwave and light emitting diode disinfection on the dimensional stability of two denture base materials; polymethyl methacrylate and polyamide. Study Design: In-vitro study Place and Duration of Study: Peshawar Dental College and Material Research Laboratories, University of Peshawar from 10 June 2021 to 8 December 2021. Materials and Methods: Fifteen specimens each for polymethylmethacrylate and polyamide were divided into three groups, control, microwave &amp; light emitting diode. The specimens for microwave group were irradiated at 1000W for 3 minutes, thrice a week. The specimens for light emitting diode group were disinfected in a device for 30 minutes, thrice a week. The control group specimens were placed in distilled water for 4 weeks. Dimensions were measured before disinfection, and four weeks after the assigned disinfection. The mean and the standard deviation of the differences between three groups were statistically analyzed using one-way ANOVA and after obtaining significant values, through post hoc Tukey HSD. Results: For polymethylmethacrylate highest dimensional difference (-9.02mm) was noted for microwave disinfected group while the control group showed the lowest value (-6.99mm). For polyamide, the highest dimensional changes were recorded for light emitting diode group (8.66mm) and the lowest (-7mm) for the control group. Statistical analysis showed that the differences were significant for both polymethylmethacrylate and polyamide when compared with the control (p&lt;0.05) but insignificant when microwave disinfected group was compared with light emitting diode group (p&gt;0.05) Conclusion: No significant difference in dimensional stability of both the denture base resins was observed after disinfection with microwave and light emitting diode.