https://jdmt.mums.ac.ir/ Journal of Dental Materials and Techniques en daily 1 Sun, 01 Mar 2026 00:00:00 +0330 Sun, 01 Mar 2026 00:00:00 +0330 https://jdmt.mums.ac.ir/article_27616.html Objective: This study investigated the impact of digital workflow contaminants, including scanning lacquer (SL), scanning spray (SS), and 3D printing resin (PR), on the reverse torque value (RTV) of implant abutment screws.Methods: In this in vitro study, 28 implant-abutment assemblies were randomly allocated into four groups (n=7), based on the type of surface contamination: scanning lacquer (SL), scanning spray (SS), 3D printing resin (PR), and an uncontaminated control group. In the experimental groups, abutment screws and internal implant surfaces were coated with the assigned material for 1 minute, while the control group remained uncontaminated. Abutments were tightened to 25 Ncm, and RTV values were recorded. All specimens then underwent standardized steam cleaning, were retightened to 25 Ncm, and RTV measurements were repeated.Results: Pre-cleaning RTV differed significantly among groups (P<0.001). The SL and SS groups exhibited significantly lower RTV values than the control and PR groups (P<0.05). After steam cleaning, significant differences remained among groups (P<0.001). The control, SL, and SS groups showed comparable RTV values, which were significantly higher than that of the PR group. Following cleaning, RTV increased significantly in the SL (P=0.002) and SS (P=0.03) groups, whereas it decreased significantly in the PR group (P=0.02), and showed no significant change in the control group (P=0.051).Conclusions: Digital workflow contaminants can affect implant screw RTV in a material-dependent manner. Steam cleaning effectively reduced torque loss caused by contamination from scanning lacquer and scanning spray, but it adversely affected RTV in implants exposed to 3D-printing resin. https://jdmt.mums.ac.ir/article_27617.html Objective: Effective removal of necrotic tissue while minimizing cementum damage is essential before replanting avulsed teeth. This study compared different root surface treatments in terms of their effectiveness for removing residual periodontal ligament (PDL) and their impact on histomorphometric properties of cementum.Methods: In this in vitro study, 90 extracted premolars were randomly assigned to nine group based on the root surface treatment applied: Group 1: sterile gauze, Group 2: 5.25% sodium hypochlorite (NaOCl) for 5 minutes, Group 3: 1% NaOCl for 15 minutes, Group 4: 5.25% NaOCl with surfactant for 2 minutes, Group 5: 5.25% NaOCl with surfactant for 5 minutes, Group 6: 1% NaOCl with surfactant for 15 minutes, Group 7: 10% calcium hypochlorite (Ca(OCl)₂) for 35 minutes, Group 8: 10% Ca(OCl)₂ with surfactant for 35 minutes, and Group 9: electric toothbrush. Following treatment, the roots were evaluated histomorphometrically for residual PDL and cementum integrity.Results: Significant differences were observed in residual PDL and cementum integrity among groups (P<0.05). The greatest removal of PDL tissue was achieved with 5.25% NaOCl with surfactant applied for 5 minutes (Group 5) or 2 minutes (Group 4), as well as with 10% Ca(OCl)₂ with surfactant applied for 35 minutes (Group 8) and 10% Ca(OCl)₂ alone (Group 7). Cementum integrity was best preserved in Groups 1, 4, 5, and 6.Conclusions: The addition of surfactant to 5.25% NaOCl improved the removal of residual PDL tissue. Among the protocols, 5.25% NaOCl with surfactant achieved the most effective PDL removal while maintaining optimal cementum integrity. https://jdmt.mums.ac.ir/article_27618.html Objective: This study compared the accuracy of digitally designed intermediate splints with those fabricated using conventional methods in orthognathic surgery.Methods: In this triple-blind randomized clinical trial, 20 patients requiring bimaxillary orthognathic surgery were randomly assigned to receive either digitally designed or conventionally fabricated intermediate splints (n=10). All patients underwent Le Fort I osteotomy and bilateral sagittal split osteotomy. In the digital group, virtual surgical planning was performed using cone-beam computed tomography (CBCT) and intraoral scans to create a three-dimensional model. Intermediate splints were then produced using computer-aided design/computer-aided manufacturing (CAD/CAM) and 3D printing. In the control group, splints were fabricated using conventional model surgery with acrylic resin. To maintain blinding, these splints were subsequently digitized using an intraoral scanner and 3D printed. The primary outcome was surgical accuracy, defined as the absolute difference (mm) between the planned and postoperative maxillary position, measured within 3 days after surgery. Secondary outcomes included intraoperative handling, assessed on a 4-point ordinal scale, and fabrication time (hours). The data were analyzed using the independent samples t-test and chi-square test at the significance level of P<0.05.Results: The discrepancy between planned and achieved maxillary position was significantly smaller in the digital group (0.70±0.67 mm) compared with the conventional group (1.40±0.84 mm; P=0.044). Intraoperative handling and fabrication times did not differ significantly between the groups (P=0.105 and P=0.40, respectively).Conclusions: Digitally designed intermediate splints demonstrated significantly higher accuracy compared with conventional splints, while fabrication time and intraoperative handling were comparable between the two groups. https://jdmt.mums.ac.ir/article_27627.html Objective: This study compared the effects of sodium fluoride varnish (NaF), NaF varnish containing nanohydroxyapatite (nano-HA), and NaF varnish containing casein phosphopeptide-amorphous calcium phosphate (CPP-ACP) on demineralized enamel.Methods: Thirty premolars were split mesiodistally, resulting in 60 specimens. The crowns were immersed in a demineralizing solution (pH 4.4) for 96 hours to create incipient carious lesions, then randomly assigned to three groups (n = 20): Group 1: NaF varnish, Group 2: NaF varnish containing 10 wt% nano-HA, and Group 3: NaF varnish containing 10 wt% CPP-ACP. The mineral content of enamel was evaluated by measuring the calcium-to-phosphorus ratio (Ca/P) at baseline (T1), after demineralization (T2), and following remineralization (T3) using energy-dispersive X-ray spectroscopy, and the changes in mineral content between T2 and T3 (mineral absorption) were calculated. Data were analyzed with repeated measures and one-way ANOVA, followed by Bonferroni and Tukey tests (α = 0.05).Results: ANOVA revealed no significant differences in Ca/P ratio at T1 (P=0.91) or T2 (P=0.88) among groups, but a significant between-group difference was observed at T3 (P<0.001). The nano-HA-containing NaF group had a significantly higher Ca/P ratio than other groups at T3 (P<0.05). There was a significant difference in the percentage of mineral absorption among groups (P<0.001). Group 1 had the lowest and group 2 showed the highest percentage of mineral absorption, with significant differences observed among all groups (P<0.05).Conclusions: NaF varnish containing nano-HA was significantly more effective than other groups in improving the mineral content of demineralized enamel. https://jdmt.mums.ac.ir/article_27629.html Objective: This study assessed the effectiveness of a miniscrew-assisted rectangular loop technique for protracting mandibular second molars without using full-arch appliances.Methods: This prospective pilot quasi-experimental study included 10 orthodontic patients (12 sites), aged 15–25 years, who had their mandibular first molars extracted at least three years earlier, and presented an interdental space of 4–7 mm between the second premolar and second molar. Two miniscrews were placed mesially and distally to the second premolar. Molar uprighting and protraction were performed using rectangular and T-loop mechanics. CBCT scans and study casts were obtained at baseline and after six months to measure primary and secondary outcomes. Primary outcome variables included crown- and root-level distances between the mandibular second premolar and second molar. Secondary outcomes included measurements of alveolar bone parameters (height, thickness, and density), second molar angulation, marginal ridge distance, and second molar first-order angulation. Data were analyzed using paired t-tests with a significance level of α = 0.05.Results: Significant reductions were observed in crown-level (3.3 ± 1.45 mm, P=0.003) and root-level distances (4.39 ± 1.64 mm, P<0.001) between the second premolar and second molar. Second molar angulation relative to the mandibular plane increased significantly (5.56 ± 6.23°, P=0.01). Alveolar bone parameters showed no significant changes (P>0.05). Marginal ridge distance decreased significantly (3.06 ± 1.53 mm, P< 0.001), whereas second molar first-order angulation remained unchanged (P=0.828).Conclusions: The miniscrew-assisted rectangular loop technique allows effective protraction of mandibular second molars and improves molar angulation, while minimally affecting the alveolar bone. https://jdmt.mums.ac.ir/article_27645.html Objective: This study compared the edge chipping resistance of three hybrid ceramics, including two polymer-infiltrated ceramic networks (PICNs; VITA Enamic and Crystal Ultra), and one resin nanoceramic (Lava Ultimate), with a zirconia-reinforced lithium silicate (VITA Suprinity).Methods: In this in vitro study, four restorative materials were prepared and tested (n=10 per group), as follows: 1: VITA Enamic, 2: Crystal Ultra, 3: Lava Ultimate, and 4: VITA Suprinity. Specimens were fabricated in dimensions of 10 × 10 × 2 mm, polished, and subjected to 5,000 thermocycles. Force was applied using a universal testing machine, with an indenter positioned at distances of 0.1 to 0.8 mm from the specimen edge. Edge chipping resistance was calculated from the slope of the force-distance curves. Data were analyzed using ANOVA and Tukey’s test, with significance set at P<0.05.Results: The highest edge chipping resistance was observed in VITA Suprinity (201.03 N/mm), while Lava Ultimate exhibited the lowest (65.69 N/mm). A statistically significant difference was found in edge chipping resistance among the groups (P=0.004). Tukey's test revealed that the edge chipping resistance was significantly greater in VITA Suprinity than in all other groups (P<0.05). Additionally, VITA Enamic and Crystal Ultra showed significantly greater edge chipping resistance than Lava Ultimate (P<0.05).Conclusions: Zirconia-reinforced lithium silicate showed superior edge chipping resistance among the tested materials, while resin nanoceramic showed the lowest. Hybrid ceramics, including resin nanoceramics and PICNs, should be used with caution in high-load areas, as their lower edge chipping resistance increases the risk of marginal failure. https://jdmt.mums.ac.ir/article_27640.html Objective: This study aimed to investigate the antimicrobial effects and retentive strength of glass ionomer cement (GIC) containing cerium oxide nanoparticles (NPs) when used for cementing orthodontic bands, as well as to evaluate the cytotoxicity of these nanoparticles.Methods: Cerium oxide nanoparticles (NPs) were incorporated into glass ionomer cement (GIC) at concentrations of 1%, 2%, and 4%. Disc-shaped specimens were prepared for each concentration, along with a control group without nanoparticles. Antibacterial activity was evaluated against Streptococcus mutans using the direct contact test. The lowest concentration of cerium oxide NPs that thoroughly eliminated bacterial growth was identified and then compared with the control group in the retentive strength test. In addition, cytotoxicity of cerium oxide NPs was assessed on gingival fibroblast cells using the MTT assay. The difference in retentive strength between the two groups was evaluated using an independent samples t-test at the significance level of P<0.05.Results: The direct contact test showed that a 1 wt% concentration of cerium oxide NPs was sufficient to eliminate all Streptococcus mutans. Incorporating 1 wt% cerium oxide into GIC did not significantly affect its retentive strength (P=0.31). Cytotoxicity testing indicated that cerium oxide NPs have relatively low toxicity, with an IC₅₀ (half maximal inhibitory concentration) value of 1000 μg/mL.Conclusions: GIC containing 1 wt% cerium oxide NPs demonstrated significant antibacterial activity against Streptococcus mutans, maintained acceptable retentive strength, and exhibited relatively low cytotoxicity.