Journal of Dental Medicine

Background and Aims: Poly methyl methacrylate (PMMA) is still the most commonly used material in prosthetic dentistry. However, there are problems with the mechanical properties of this type of material including low flexural strength. Addition of nanoparticles into the polymer is one way to improve the mechanical properties of acrylic resin. In the present study, the effect of silicon dioxide (SiO₂) nanoparticles addition into the heat-cured acrylic resin in different concentrations was investigated. Because of the controversy had been observed in previous articles, the aim of this study was to investigate the mechanical properties of PMMA/SiO₂ nanoparticle obtained from different percentages of SiO₂.
Materials and Methods: In this in-vitro study, acrylic resin specimens containing 0, 1, 3 and 5% silicon dioxide (SiO₂) were prepared. The specimens were placed inside the gypsum molds and placed under pressure for three times. The mold cured in boiling water for 30 min. A trimmer was used to remove the additives. Sandpapers with 180, 320 and 600 grains of silicon-carbide were used for final finishing and polishing. Finally, the flexural strengths were measured using a universal testing machine. Data were finally analyzed by ANOVA and Tukey tests at a significant level of 5% using SPSS software.
Results: The mean flexural strengths and standard deviations of control group, 1% filler, 3% filler, and 5% filler, were 57.24±8.30, 69.98±7.26, 60.16±9.18, and 61.59±9.28 MPa, respectively. After comparing significant values between each group with the control group, a significant difference was observed between the control and 1% filler group (P=0.021). However, no significant difference was observed between 3 and 5% fillers with the control group or each other. The significant differences (P-value) between 3% filler and control group were 0.892 and between 5% filler and control group was 0.975.
Conclusion: The results of the present study showed that the use of low percentage of silicone dioxide (SiO₂) nanofiller could improve the flexural strength of poly methyl methacrylate acrylic resin.

Background and Aims: Dry socket is one of the most common complications following dental surgery. Therefore, effective prevention of dry socket can significantly improve patient recovery after tooth extraction. The aim of this study was to evaluate the effect of tranexamic acid combined with a Gelfoam carrier on the prevention of dry socket following surgical removal of impacted mandibular third molars.
Materials and Methods: This parallel randomized clinical trial was conducted in 2023 on 72 patients (40 in the intervention group and 32 in the control group) at the Department of Oral and Maxillofacial Surgery, Faculty of Dentistry, Islamic Azad University, Tehran Unit. In the intervention group, 250 mg of tranexamic acid powder was placed into the extraction socket and covered with Gelfoam, whereas the control group received sterile gauze only. The diagnosis of dry socket was made 2–3 days postoperatively by an independent surgeon. Statistical analysis was performed using the chi-square test, likelihood ratio, and Fisher’s exact test, with a significance level set at P<0.05.
Results: The incidence of dry socket was 7.5% in the intervention group and 34.4% in the control group. All statistical tests demonstrated a significant reduction in the occurrence of dry socket in the intervention group (P≤0.005). These findings are consistent with the physiological mechanism of tranexamic acid in inhibiting fibrinolysis and stabilizing the blood clot, resulting in a marked reduction compared with the control group.
Conclusion: Topical application of the tranexamic acid in combination with Gelfoam following extraction of impacted third molars is an effective, simple, and cost-effective method for the prevention of dry socket. For broader clinical recommendation, further studies with larger sample sizes, comparisons with existing standard preventive methods, and longer follow-up periods are suggested.