Effects of various disinfectants on surface roughness and color stability of thermoset and 3D-printed acrylic resin.

Denture cleansers are extensively utilized to inhibit the colonization of various Candida species. Currently, additive technology in denture fabrication has become more prevalent. This study aims to assess the impact of disinfectants on the surface roughness and color stability of distinct denture bases. Disc-shaped samples (N=66) were exposed to three different disinfectants: 0.5% sodium hypochlorite, 1% hydrogen peroxide, and 2% chlorhexidine. The samples underwent evaluation via spectrophotometry and profilometry, respectively. Data analysis was conducted utilizing analysis of variance (ANOVA) (p < 0.05). Within the heat-cured group, sodium hypochlorite resulted in the most notable change in surface roughness (0.2 µm), while chlorhexidine exhibited the least impact (0.001 µm), showing a significant difference (p <0.008). The color change (ΔE) for 3D-printed samples immersed in all disinfectants was higher compared to heat-cured samples. Among the heat-cured samples, chlorhexidine induced the highest ΔE (2.76), while sodium hypochlorite resulted in the lowest (ΔE = 1.44), and this difference was statistically significant (p <0.008). Chlorhexidine caused the most significant color alteration among the solutions, while sodium hypochlorite induced the most considerable changes in surface roughness.

Shear bond strength of orthodontic brackets to specimens fabricated from temporary restorative materials by 3D-printing, CAD/CAM technology, and the conventional technique after surface treatment by sandblasting and laser.

OBJECTIVES: This study assessed the shear bond strength (SBS) of stainless steel (SS) orthodontic brackets to specimens fabricated from polymethyl methacrylate (PMMA) temporary restorative material by 3D-printing, computer-aided design/computer-aided manufacturing (CAD/CAM) technology, and the conventional technique, after surface treatment by sandblasting and laser. MATERIAL AND METHODS: In this in vitro study, 60 disc-shaped specimens with 8mm diameter and 1mm height were fabricated from PMMA temporary restorative material by 3D-printing, CAD/CAM, and the conventional technique. In each group (n=20), half of the specimens were sandblasted while the other half underwent Er,Cr:YSGG laser irradiation. Brackets were bonded to the specimens and underwent thermocycling followed by SBS testing. Data were analysed by one-way ANOVA, independent t-test, and LSD test (alpha=0.05). RESULTS: A significant difference existed among the three fabrication methods in SBS in both laser (P<0.001) and sandblasting (P<0.001) surface treatment groups. In laser group, the mean SBS of CAD/CAM (P=0.000) and conventional (P=0.000) groups was significantly lower than that of 3D-printing group. In sandblasting group, the SBS of CAD/CAM group was significantly lower than 3D-printing (P=0.000) and conventional (P=0.000) groups. The mean SBS of laser-treated specimens was significantly higher than sandblasted specimens in 3D-printing group (P=0.000), and significantly lower than sandblasted specimens in the conventional group (P=0.000). A significantly higher SBS was obtained by laser treatment compared with sandblasting irrespective of the fabrication method (P=0.000). CONCLUSION: The highest SBS of SS orthodontic brackets to temporary restorative material was recorded for 3D-printed specimens treated by Er,Cr:YSGG laser irradiation.

Comparing knowledge and opinions of medical and dental students in the field of pediatric anesthesia.

Background and Purpose: Dental treatment under general anesthesia (GA) is one of the common treatment methods today for dental treatment in children, so dentists' point of view in this field is very important. Therefore, the purpose of this study was evaluation the awareness and attitude of pediatric dentists and final-year dental students about dental treatment for children under GA. Methods: To conduct this study, 150 people, including 75 general dentists (GD) and 75 final-year dental students (FYDS), were randomly selected in Tehran. In this study, a researcher-made questionnaire containing 15 questions (7 awareness questions and 8 attitude questions) was used to evaluate the awareness and attitude of the participants. After extracting the raw results, statistical analysis of the results was done using SPSS-Ver. 22 software. Results: 60% of the participants (90 people) were men and the remaining 40% (60 people) were women. The results showed that the level of awareness of male dentists was significantly higher than that of female dentists (P = 0.015). In addition, although the awareness level of FYDS was lower than GD, this difference was not statistically significant (P = 0.130). The average level of awareness among different age groups had a significant difference (P = 0.009), so the age group of 36-45 years compared to the younger age groups (25-35 years) and the older age groups (36-45 and 55 -46 years), had a higher level of awareness. Conclusion: According to the findings, it can be concluded that it is necessary to use appropriate educational methods to improve the level of awareness and attitude of children's dentists.

A comparative evaluation of wear resistance of three types of artificial acrylic teeth after removing the glaze layer.

Background: The posterior denture teeth wear faster than the anterior teeth, which can result in occlusal interferences, loss of vertical dimension of occlusion, greater stress accumulation in the anterior region, and higher ridge resorption. This study aimed to compare the wear resistance of three types of artificial acrylic teeth before and after removing the glaze layer. Materials and Methods: This in vitro study compared three types of artificial acrylic teeth, namely, Finex (F), SR Orthotyp DCL (S), and Vita Physiodents (V) in six groups (n = 10). Half of the artificial teeth of each brand underwent 0.5-mm buccal reduction to remove the glaze layer (groups FC, SC, and VC). The teeth were thermocycled and placed in a chewing simulator. The teeth with and without the glaze layer were weighed before and after the wear test. The data were analyzed using ANCOVA (the level of significance was 0.05). Results: The weight reduction (indicative of wear) was 0.03 ± 0.02 and 0.12 ± 0.03 mg in Groups S and SC, 0.03 ± 0.02 and 0.25 ± 0.04 mg in Groups V and VC, and 0.11 ± 0.15 and 0.28 ± 0.1 mg in groups F and FC, respectively. Removing the glaze layer (P < 0.01), type and brand of acrylic tooth (P < 0.01), and the baseline weight of artificial teeth (P < 0.01) had significant effects on wear resistance of artificial teeth. Conclusion: The wear of artificial teeth was greater after removing the glaze layer, and the magnitude of wear was also significantly different among the three brands. The group FC showed maximum wear while the groups S and V showed minimum wear.

Recent findings on chimeric antigen receptor (CAR)-engineered immune cell therapy in solid tumors and hematological malignancies.

Advancements in adoptive cell therapy over the last four decades have revealed various new therapeutic strategies, such as chimeric antigen receptors (CARs), which are dedicated immune cells that are engineered and administered to eliminate cancer cells. In this context, CAR T-cells have shown significant promise in the treatment of hematological malignancies. However, many obstacles limit the efficacy of CAR T-cell therapy in both solid tumors and hematological malignancies. Consequently, CAR-NK and CAR-M cell therapies have recently emerged as novel therapeutic options for addressing the challenges associated with CAR T-cell therapies. Currently, many CAR immune cell trials are underway in various human malignancies around the world to improve antitumor activity and reduce the toxicity of CAR immune cell therapy. This review will describe the comprehensive literature of recent findings on CAR immune cell therapy in a wide range of human malignancies, as well as the challenges that have emerged in recent years.

Biosynthesis of Zn-doped CuFe2O4 nanoparticles and their cytotoxic activity.

Zn-doped CuFe2O4 nanoparticles (NPs) were eco-friendly synthesized using plant extract. These nanoparticles were characterized by X-ray diffraction, Fourier-transform infrared spectroscopy, scanning electron microscope (SEM), energy-dispersive X-ray spectroscopy and thermal gravimetric analysis (TGA). SEM image showed spherical NPs with size range less than 30 nm. In the EDS diagram, the elements of zinc, copper, iron, and oxygen are shown. The cytotoxicity and anticancer properties of Zn-doped CuFe2O4 NPs were evaluated on macrophage normal cells and A549 lung cancer cells. The cytotoxic effects of Zn-doped CuFe2O4 and CuFe2O4 NPs on A549 cancer cell lines were analyzed. The Zn-doped CuFe2O4 and CuFe2O4 NPs demonstrated IC50 values 95.8 and 278.4 µg/mL on A549 cancer cell, respectively. Additionally, Zn-doped CuFe2O4 and CuFe2O4 NPs had IC80 values of 8.31 and 16.1 µg/mL on A549 cancer cell, respectively. Notably, doping Zn on CuFe2O4 NPs displayed better cytotoxic effects on A549 cancer cells compared with the CuFe2O4 NPs alone. Also spinel nanocrystals of Zn-doped CuFe2O4 (~ 13 nm) had a minimum toxicity (CC50 = 136.6 µg/mL) on macrophages J774 Cell Line.

Comparison of shear bond strength of orthodontic stainless-steel brackets on temporary crowns fabricated by three different methods: An in vitro study.

BACKGROUND AND AIMS: Different methods are available for making temporary restorations. The purpose of this study was to determine and compare the shear bond strength of orthodontic brackets on temporary crowns made by three different methods. MATERIALS AND METHODS: In this experimental study, disc form samples (N=54) were made in dimensions 8×1mm, according to the manufacturer's instructions. In this study, we had three groups (N=18) based on manufacturing methods (3D printing, conventional, and CAD/CAM). Following surface preparation of the samples, the brackets were bonded in the centre of the discs. Before the shear bond strength test, the samples were subjected to the thermocycling process. The shear bond strength of brackets was measured by Universal Testing Machine. Data were analysed by one-way ANOVA and LSD post hoc test. RESULTS: The findings indicated that the mean shear bond strength of orthodontic stainless-steel brackets on temporary crowns varied between CAD/CAM and 3D printing methods (P<0.001) and also between CAD/CAM and conventional methods (P<0.001). The mean shear bond strength of orthodontic stainless steel brackets on temporary crowns was not different between 3D printing and conventional methods (P=0.7). CONCLUSION: The shear bond strength of orthodontic stainless-steel brackets bonded to temporary crowns fabricated by conventional and 3D printing methods was similar, and the shear bond strength in the samples fabricated by CAD/CAM method was lower than other specimens.

Retention of Cast Posts Cemented with Two Commonly Used Conventional and Two Resin Cements and the Mode of Root Fracture Following Their Removal.

Objectives: This study aimed to compare the retention of cast posts cemented with four types of cements and assess the mode of root fracture following their removal. Materials and Methods: In this in vitro, experimental study, 48 upper central incisors were randomly divided into 4 groups of 12, and were endodontically treated. The fabricated cast posts in each group were cemented with zinc phosphate (Masterdent), glass ionomer (GI; Meron), Meta resin cement, and Panavia SA resin cement. A device was customized for post removal by a universal testing machine similar to WAM X pliers. The retention of cemented posts was measured by the pull-out test in a universal testing machine. Next, the teeth were macroscopically and microscopically inspected regarding the occurrence and sites of catastrophic fracture, cracks, or craze lines. Quantitative and qualitative data were analyzed by ANOVA, and Chi-square test, respectively (P<0.05). Results: ANOVA showed a significant difference in the mean retention of cements (P<0.001). Panavia provided the highest retention (278.6±34.9 N) followed by zinc phosphate (221.9±28.88 N), GI (161.3±60.7 N), and Meta (140.4±66.54 N). There was no significant difference between the groups regarding the pattern of root fracture (P=0.39). However, site and extent of fractures were significantly different among the groups (P<0.05). Conclusion: The conventional cements provided optimal retention and caused less root damage after post removal. Thus, cements providing adequate retention and allowing easier post removal are recommended for use in endodontically treated teeth with a possibility of requiring retreatment.

Effect of photo core, LuxaCore, and core max II core building materials on fracture resistance of endodontically-treated teeth restored with fiber-reinforced composite posts and ParaPosts.

BACKGROUND: Post and core treatment is commonly performed for endodontically treated teeth to replace the lost tooth structure and reinforce and protect the remaining dental tissue. This study aimed to compare the effect of three-core building materials on fracture resistance of endodontically-treated teeth restored with fiber-reinforced composite (FRC) posts and ParaPosts. MATERIALS AND METHODS: This in vitro, experimental study evaluated 108 sound, single-rooted mandibular first premolars extracted for orthodontic purposes. The teeth were randomly divided into nine groups (n = 12) of control (no endodontic or restorative treatment), FRC + Photo Core (Group 2), FRC + LuxaCore (Group 3), FRC + Core Max II with bonding agent (Group 4), FRC + Core Max II without bonding agent (Group 5), ParaPost + Photo Core (Group 6), ParaPost + LuxaCore (Group 7), ParaPost + Core Max II with bonding agent (Group 8), and ParaPost + Core Max II without bonding agent (Group 9). The fracture resistance was measured by applying the load at 45° angle relative to the longitudinal axis of the tooth with a crosshead speed of 1 mm/min using a universal testing machine. Data were through descriptive statistics, Tukey's test, and one-way analysis of variance (α = 0.05). RESULTS: The mean fracture resistance was 454.0 ± 62.7, 410.8 ± 48.3, 365.1 ± 42.1, 423.7 ± 111.7, 392.4 ± 90.0, 292.3 ± 83.9, 242.3 ± 73.4, 278.2 ± 67.9, and 247.3 ± 49.6 N in Groups 1-9, respectively. Group 4 showed the highest fracture resistance, which was significantly higher than this study the value in all ParaPost and control groups (P < 0.05) but had no significant difference with the fracture resistance of other groups (P > 0.05). CONCLUSION: Fracture resistance is independent of the type of core building material used, and the tested products had no superiority over each other. The mean fracture resistance of FRC post groups were significantly higher than that of ParaPost groups. Furthermore, Core Max II + bonding agent yielded insignificantly higher fracture resistance than Core Max II without bonding agent.

Effect of dental implantation on the hard and soft tissues around the adjacent natural teeth.

BACKGROUND: Dental implantation has become widespread for esthetic and functional rehabilitation following single tooth loss as a preferred alternative to conventional tooth-supported restorations. The main advantage of dental implant placement is that it does not require the preparation of the adjacent sound teeth. OBJECTIVES: The aim of this cohort study was to assess the effect of dental implantation on the hard and soft tissues around the adjacent natural teeth. MATERIAL AND METHODS: In this historical cohort, 34 'connect-type' TBR® implants (bone level), 4 mm in diameter, were submerged in the intact bone of 22 patients (7 males and 15 females). The intraoral and extraoral clinical examination as well as periapical radiography were carried out preoperatively or right after surgery (baseline), at 3 months postoperatively (the time of prosthetic delivery), and at 3 and 6 months after prosthetic delivery. The data was analyzed using the Friedman test (due to the non-normal distribution of the data). In case of presence of a significant difference, pairwise comparisons were performed using the post-hoc Wilcoxon test with the Bonferroni correction. All statistical analyses were performed with a 95% confidence interval (CI) using the SPSS for Windows, v. 16.0 software. The p­value <0.05 was considered statistically significant. RESULTS: The distance from the cementoenamel junction (CEJ) of the adjacent teeth to the bone crest significantly increased at different postoperative time points compared to baseline (p < 0.001). The changes in the papillae of the adjacent teeth were also significant at different postoperative time points (p = 0.04). The pocket depth of the adjacent teeth increased, although the value at 3 months postoperatively was not significantly different from the baseline value (p = 0.842). The distance from the implant shoulder to the bone crest of the adjacent teeth significantly increased at different postoperative time points compared to baseline (p < 0.001). CONCLUSIONS: Our results indicate that implant surgery significantly affects the soft and hard tissues around the adjacent natural teeth.

Comparative Study of Dimensional Accuracy in Three Dental Implant Impression Techniques: Open Tray, Closed Tray with Impression Coping, and Snap Cap.

AIM: Several impression techniques have been proposed to result passive fitness between the prosthesis and osseointe-grated implant. The aim of the study was to compare dimensional accuracy of three impression methods: Open tray, closed tray with impression coping, and closed tray with snap cap. MATERIALS AND METHODS: In this experimental study, a mandibular acrylic model was prepared with a milling machine to place three holes for dental implant analogs (Dio SM) with the dimension of 3.8 × 10 mm into the intended sites (one in midline and two others on the side at a distance of 10 mm) parallel with each other and perpendicular to the plane. Twenty-seven casts were prepared with impression material of polyvinyl siloxane (PVS) and dental stone type IV and divided into three groups. Implant situations were measured by coordinate measuring machine (CMM) and results were analyzed with Kruskal-Wallis and Mann-Whitney test to perform pairwise comparison among the groups. RESULTS: The mean ΔR values for open tray, closed tray with impression coping, and closed tray with snap cap were respectively, 0.070 ± 0.088, 0.173 ± 0.205, and 0.142 ± 0.044. There were statistically significant differences between open tray and closed tray as well as open tray and snap cap methods (p < 0.05), but there was no statistically significant difference between closed tray and snap cap method (p = 0.1). CONCLUSION: Regarding the results, open tray impression technique had the highest dimensional accuracy compared with the other two methods. There were no statically significant differences between closed tray with snap cap and closed tray with impression coping technique. CLINICAL SIGNIFICANCE: Snap cap technique is less time consuming with similar dimensional accuracy in comparison with open tray impression technique.

Immediate vs. delayed endosseous integration of maxi implants: a torque removal animal study.

Background. Delayed loading is one of the concerns in implant patients. Immediate loading can solve the problem and make patients more satisfied. The present study aimed to compare the removal torque of maxi implants under different loading (immediate and delayed) patterns. Methods. This split-mouth experimental study included 2 dogs. Impressions were made and then all the premolars were extracted under general anesthesia. After a three-month healing period, 3 implants were inserted in each quadrant (a total of 12 implants). Anterior and posterior implants (the case group) were splinted by an acrylic temporary bridge in order to make the middle implants (the control group) off the occlusion. The dogs were sacrificed after 6 weeks and bone blocks were submitted for removal torque test. Data were analyzed with ANOVA (P<0.05). Results. Mean torque values for the cases and control groups were 46.82±25.58 and 59.88±15.19, respectively (P=0.582; not significant). Conclusion. It may be concluded that immediate loading does not reduce the reverse torque values of maxi implants. This supports the advantages of immediate loading for maxi implants.