Mechanism of action of Coptidis Rhizome in treating periodontitis based on network pharmacology and in vitro validation.

OBJECTIVE: Explore the therapeutic mechanism of Coptidis Rhizome (CR) in periodontitis using network pharmacology, and validate it through molecular docking and in vitro experiments. METHODS: Screened potential active components and target genes of CR from TCMSP and Swiss databases. Identified periodontitis-related target genes using GeneCards. Found common target genes using Venny. Conducted GO and KEGG pathway analysis. Performed molecular docking and in vitro experiments using Berberine, the main active component of CR, on lymphocytes from healthy and periodontitis patients. Assessed effects on inflammatory factors using CCK-8, flow cytometry, and ELISA. RESULTS: Fourteen active components and 291 targets of CR were identified. 30 intersecting target genes with periodontitis were found. GO and KEGG analysis revealed oxidative stress response and IL-17 signaling pathway as key mechanisms. Molecular docking showed strong binding of Berberine with ALOX5, AKT1, NOS2, and TNF. In vitro experiments have demonstrated the ability of berberine to inhibit the expression of Th17 + and other immune related cells in LPS stimulated lymphocytes, and reduce the secretion of IL-6, IL-8, and IL-17. CONCLUSION: CR treats periodontitis through a multi-component, multi-target, and multi-pathway approach. Berberine, its key component, acts through the IL-17 signaling pathway to exert anti-inflammatory effects.

Enhancing physicochemical, rheological properties, and in vitro rumen fermentation of starch with Melastoma candidum D. Don fruit extract.

The utilization of polyphenol-modified starch in ruminants has not undergone extensive exploration. This study aimed to investigate the impact of the complex formed between starch and Melastoma candidum D. Don fruit extract on physicochemical properties, phenol release kinetics in various buffers simulating the gastrointestinal tract, methane production, and post-rumen digestibility. The interaction between starch and M. candidum D. Don fruit extract significantly (p < 0.001) increased resistant starch and particle size diameter. The maximum phenolic release from complex between starch and M. candidum D. Don fruit extract, due to gastrointestinal tract-simulated buffers, ranged from 22.96 to 34.60 mg/100 mg tannic acid equivalent. However, rumen and abomasum-simulated buffers released more phenolic content, whereas the intestine-simulated buffer showed higher antioxidant activity (ferric ion-reducing antioxidant power). Furthermore, complex between starch and M. candidum D. Don fruit extract significantly decreased dry matter rumen digestibility (p < 0.001) and maximum methane gas production (p < 0.001).

Hyaluronidase inhibits TGF-ß-mediated rat periodontal ligament fibroblast expression of collagen and myofibroblast markers: An in vitro exploration of periodontal tissue remodeling.

OBJECTIVE: To determine the effect of hyaluronic acid (HA) degradation by hyaluronidase (HYAL) in inhibiting collagen fiber production by rat periodontal ligament cells (rPDLCs). DESIGN: Primary rPDLCs were isolated from the euthanized rats and used for in vitro experiments. The appropriate HYAL concentration was determined through CCK-8 testing for cytotoxicity detection and Alizarin red staining for mineralization detection. RT-qPCR and western blot assays were conducted to assess the effect of HYAL, with or without TGF-ß, on generation of collagen fiber constituents and expression of actin alpha 2, smooth muscle (ACTA2) of rPDLCs. RESULTS: Neither cell proliferation nor mineralization were significantly affected by treatment with 4 U/mL HYAL. HYAL (4 U/mL) alone downregulated type I collagen fiber (Col1a1 and Col1a2) and Acta2 mRNA expression; however, ACTA2 and COL1 protein levels were only downregulated by HYAL treatment after TGF-ß induction. CONCLUSIONS: Treatment of rPDLCs with HYAL can inhibit TGF-ß-induced collagen matrix formation and myofibroblast transformation.

Effect of attachment flash on clear aligner force delivery: an in vitro study.

BACKGROUND: The introduction of auxiliaries such as composite attachment has improved the force delivery of clear aligner (CA) therapy. However, the placement of the attachment may give rise to a flash, defined as excess resin around the attachment which may affect CA force delivery. This in vitro study aims to determine the differences in the force generated by the attachment in the presence or absence of flash in CA. MATERIALS AND METHODS: Tristar Trubalance aligner sheets were used to fabricate the CAs. Thirty-four resin models were 3D printed and 17 each, were bonded with ellipsoidal or rectangular attachments on maxillary right central incisors. Fuji Prescale pressure film was used to measure the force generated by the attachment of CA. The images of colour density produced on the films were processed using a calibrated pressure mapping system utilising image processing techniques and topographical force mapping to quantify the force. The force measurement process was repeated after the flash was removed from the attachment using tungsten-carbide bur on a slow-speed handpiece. RESULTS: The intraclass correlation coefficient showed excellent reliability (ICC = 0.96, 95% CI = 0.92-0.98). The average mean force exerted by ellipsoidal attachments with flash was 8.05 ± 0.16 N, while 8.11 ± 0.18 N was without flash. As for rectangular attachments, the average mean force with flash was 8.48 ± 0.27 N, while 8.53 ± 0.13 N was without flash. Paired t-test revealed no statistically significant difference in the mean force exerted by CA in the presence or absence of flash for both ellipsoidal (p = 0.07) and rectangular attachments (p = 0.41). Rectangular attachments generated statistically significantly (p < 0.001) higher mean force than ellipsoidal attachments for flash and without flash. CONCLUSION: Although rectangular attachment generated a significantly higher force than ellipsoidal attachment, the force generated by both attachments in the presence or absence of flash is similar (p > 0.05).

Examination of cytotoxic and antimicrobial effect of whitening toothpastes: an in vitro study.

OBJECTIVE: Toothpastes are widely used to protect oral and teeth health. This study aims to examine the cytotoxic and antimicrobial effects of whitening toothpastes. METHODS: In this study, extracts were prepared according to ISO 10993-12:2021 standard (0.2 g/mL) using whitening and conventional toothpastes. The prepared extracts were added to human gingival fibroblast cell lines (HGF-1) in different dilutions (1:1, 1:2, 1:4, 1:8, 1:16, and 1:32) and a cytotoxicity test was performed. Antimicrobial analysis of toothpastes was performed on Streptococcus mutans, Staphylococcus aureus, and Candida albicans using the hole-plate diffusion method. Cell viability and microbial analysis data were examined using two-way analysis of variance (ANOVA) and Tukey post-hoc test (p < 0.05). RESULTS: Toothpastes with sodium lauryl sulfate (SLS) in their composition showed statistically more toxic effects (p < 0.05). The activated carbon toothpastes without SLS showed over 90% cell viability after dilution. Although the dilution rate of toothpastes containing SLS increased, cell viability remained below 70%. All toothpastes used in the study showed antimicrobial effects on S. mutans, S. aureus, and C. albicans. Toothpaste containing hydrogen peroxide and SLS produced more antibacterial effects than activated carbon, blue covarine, microparticles, and conventional toothpaste. CONCLUSIONS: SLS-containing toothpastes showed more toxicity on HGF-1 cells. Toothpaste containing hydroxyapatite did not show toxic effects on HGF-1 cells. SLS, sodium lauryl sarcosinate and hydrogen peroxide in toothpastes increase antimicrobial effects.

Digital Photocolorimetric Analysis of In Vitro Tooth Color Changes.

OBJECTIVE: Tooth color matching is challenging, and digital photocolorimetry using eLABor_aid (eLAB) provides objective evaluation through polarized photographs. However, its comparability with spectrophotometry remains unclear. METHODS AND MATERIALS: Bovine incisor root canals (n=30) were prepared to simulate an incomplete root apex. The teeth were randomly assigned to three groups based on intracanal medication: control (without medication); calcium hydroxide/propylene glycol; and triple-antibiotic paste (n=10 each). Tooth color was assessed using both eLAB and spectrophotometry. Measurements were taken at the crown medio-cervical region on five-time intervals (baseline, 1, 3, 7, and 14 days). Statistical analysis included two-way repeated-measures ANOVA, Sidak post hoc and Pearson's correlation test (α=0.05). RESULTS: No significant differences were observed between the two methods for either medication or follow-ups (p>0.05). Triple-antibiotic paste exhibited higher color variation (p<0.05). After 7 days, all groups presented significant color changes (p<0.05). Moderate to high correlations (R2 from 0.51 to 0.84, p<0.0001) were found between both methods for all groups at all intervals. CONCLUSION: The eLAB is a reliable method for detecting tooth color changes, and its results are comparable to spectrophotometry analysis.

Enamel Matrix Derivative, 58S5 Bioactive Glass, and Fluoride Varnish for Enamel Remineralization: A Multi-analysis Approach.

PURPOSE: This study aimed to evaluate the enamel remineralization efficacy of enamel matrix derivative (EMD), experimental bioactive glass (BAG), and fluoride varnish in vitro. METHODS AND MATERIALS: Artificial initial caries lesions were developed on fifty human enamel specimens using demineralization solution (pH 4.5, 37°C, 96 hours). Specimens were randomly assigned to five groups (n=10): I-5% NaF varnish (Enamelast), II-experimental 58S5 BAG+37% phosphoric acid (PA), III-EMD (Emdogain) + Ethylenediaminetetraacetic Acid (EDTA), IV-EMD+37% PA, V-Control (untreated). All remineralization agents were applied with pH cycling for seven days. The specimens were scanned by spectral domain optical coherence tomography (SD-OCT) at baseline, at demineralization, and after pH cycling. Lesion depths were measured using image analysis software (ImageJ). Lesions were evaluated using surface microhardness (SMH) and two fluorescence methods (FluoreCam and DIAGNOdent Pen [DDPen]). The data were statistically analyzed by Kruskal Wallis, Friedman, and Wilcoxon tests (α=0.05). RESULTS: According to SD-OCT results, fluoride varnish was found to be the most effective agent in reducing lesion depth (p=0.005). All agents increased the SMH values after pH cycling. No significant difference was found among fluoride varnish, BAG, and EMD+PA groups. These SMH values were significantly higher than EMD+EDTA and control groups (p<0.001). All groups showed lower DDPen scores compared with the control group (p<0.001), however, no significant difference was found among the remineralization agents. In FluoreCam assessment, size and intensity values of all treated groups showed improvement. However, there was no significant difference between the treatment groups in terms of FluoreCam size measurements (p=0.186). CONCLUSION: 58S5 BAG and EMD+PA have remineralization capacity as effective as fluoride varnish. EMD+PA showed better SMH and lesion intensity results than EMD+EDTA.

Interplay Between Minerals in Bottled Water and Fluoride Toothpaste and Caries Lesion Remineralization.

OBJECTIVES: he aim of this in vitro study was to evaluate the effects of some bottled waters on fluoride toothpaste efficacy in enhancing caries lesion remineralization. METHODS: Early caries lesions were created in bovine enamel specimens and stratified into treatment groups based on Vickers surface microhardness (VHN). The present study followed a two (fluoride and fluoride-free toothpaste) by five (four bottled waters and tap water) factorial design. The treatment groups were bottled water with the following attributes: (a) 309.9 ppm Ca/1.20 ppm F; (b) 118.4 ppm Ca/0.16 ppm F; (c) 1.00 ppm Ca/1.01 ppm F; and (d) 0.1 ppm Ca/0.04 ppm F and tap water (48.7 ppm Ca/0.7 ppm F). The five water groups were paired either with 1100 ppm fluoride or fluoride-free toothpaste, yielding 10 groups. Specimens were pH-cycled for 10 days with the daily regimen comprised of twice daily toothpaste slurry, with four exposures to water in between. VHN was measured again and the difference was calculated (ΔVHN). Data were analyzed using two-way ANOVA at a 5% significance level. RESULTS: The two-way interaction between water and toothpaste was significant (p<0.001). All groups except fluoride-free toothpaste/bottled water with 0.1 ppm Ca/0.04 ppm F (p=0.411) had significant increases in VHN after pH cycling (p≤0.023). Fluoridated toothpaste resulted in a higher rate of remineralization compared to fluoride-free toothpaste (all p<0.001). Bottled water with 1.20 ppm F/309.9 ppm Ca exhibited the greatest extent of remineralization within fluoride toothpaste groups (p<0.001) and higher remineralization than lower fluoride water in fluoride-free toothpaste groups (p≤0.006). Within the fluoridated toothpaste group, tap water exhibited significantly less remineralization than all bottled waters (all p<0.001). CONCLUSION: Within the limitation of this study, bottled water with higher fluoride and calcium concentrations might improve fluoridated toothpaste efficacy by enhancing remineralization of early enamel caries-like lesions.

In-vitro evaluation of fracture resistance of teeth restored with different high-viscosity glass ionomer restorative materials and bulk-fill composite resins.

OBJECTIVES: This study aimed to evaluate the effect of restorations made with a glass-hybrid restorative system (GHRS), a high-viscosity glass ionomer restorative material (HVGIC), a high-viscosity bulk-fill composite resin (HVB), a flowable bulk-fill composite resin (FB), and a nanohybrid composite resin (NH), which are commonly preferred in clinical applications on the fracture resistance of teeth in-vitro. MATERIALS AND METHODS: One hundred intact human premolar teeth were included in the study. The teeth were randomly divided into ten groups (n = 10). No treatment was applied to the teeth in Control group. Class II cavities were prepared on the mesial surfaces of the remaining ninety teeth in other groups. For restoration of the teeth, a GHRS, a HVGIC, a HVB, a FB, and a NH were used. Additionally, in four groups, teeth were restored using NH, GHRS, and HVGIC with open and closed-sandwich techniques. After 24 h, fracture resistance testing was performed. One-way ANOVA and Tukey HDS tests were used for statistical analysis of the data. RESULTS: The fracture resistance values of Control group were statistically significantly higher than those of GHRS, HVGIC, FB, NH, HVGIC-CS, GHRS-OS, and HVGIC-OS groups(p < 0.05). There was no statistically significant difference observed between the fracture resistance values of Control, HVB, and GHRS-CS groups (p > 0.05). CONCLUSION: It can be concluded that the use of HVB and the application of GHRS with a closed-sandwich technique may have a positive effect on the fracture resistance of teeth in the restoration of wide Class II cavities. CLINICAL RELEVANCE: The use of high-viscosity bulk-fill composite resin and the application of glass-hybrid restorative system with the closed-sandwich technique in the restoration of teeth with wide Class II cavities could increase the fracture resistance of the teeth.

A conservative approach to localize loose implant screw through cemented crown: an in vitro experimental study.

BACKGROUND: Retrieval of cement-retained implant-supported restorations is intriguing in cases of screw loosening. Detecting the estimated size of the screw access hole (SAH) could decrease destruction to the prosthesis and preserve the crown. OBJECTIVES: To precisely localize loose implant screws through cemented crowns to reduce crown damage after screw loosening. MATERIALS AND METHODS: In this in vitro study, 60 cement-retained implants supported 30 zirconia-based, and 30 ceramics fused to metal (CFM) lower molar crowns were invented, and each was subdivided into three subgroups (10 each). In group I (AI/BI) (control), SAH was created with the aid of orthopantomography (OPG). In contrast, in group II (zirconia-crown), SAH was created with the aid of CBCT + 3D printed surgical guide with a 2 mm metal sleeve in subgroups IIA/IIIA and CBCT + MAR was used to develop SAH in subgroups IIB/IIIB. SEM and Micro-CT scanned the SAH openings to determine the diameter of the hole, cracking, chipping, and chipping volume. RESULTS: Regarding the effect of plane CBCT and CBCT + MAR on prepared crowns, a highly significant association between group I with group II (p = 0.001) and group III (p = 0.002) was detected. Regarding the cracking of SAH, significant differences between the zirconium crown and CFM restoration (p = 0.009) were found, while for the chipping, no significant association was seen between groups (p = 0.19). CONCLUSIONS: CBCT, either as a plane CBCT or with MAR, significantly improved the accuracy of drilling the screw channel and decreased injury to the existing restoration and abutment, aiding in better localization of SAH in loosened implant abutment screws.

Efficacy of the Probiotic L. brevis in Counteracting the Demineralizing Process of the Tooth Enamel Surface: Results from an In Vitro Study.

BACKGROUND: Enamel plays an essential role in protecting the underlying layers of the human tooth; therefore, preserving it is vital. This experimental study aimed to evaluate the potential ability of L. brevis to counteract the action of a demineralizing agent on dental enamel morphology and mineral composition in vitro. METHODS: The sample consisted of 12 healthy human posterior teeth. The coronal portion of each tooth was subdivided into two equal parts longitudinally. The specimens were randomly divided into four groups: artificial saliva, L. brevis suspension, demineralizing agent (DA), and DA plus L. brevis. Scanning electron microscopy (SEM) and energy-dispersive X-ray spectroscopy (EDS) were used to evaluate the surface micromorphology and the mineral content, respectively. The statistical analysis was conducted using a one-way ANOVA, followed by Tukey's post hoc test. RESULTS: SEM analysis did not highlight significant changes in the enamel microstructure of L. brevis-treated specimens compared to the control. DA-induced damage to the enamel structure was drastically reduced when the specimens were contextually exposed to the probiotic. The treatment with DA substantially reduced the weight % of crucial enamel minerals, i.e., Ca and P. Notably, the probiotic was able to reverse the demineralization process, bringing Ca and P weight % back to basal levels, including the Ca/P ratio. CONCLUSIONS: The findings indicate that L. brevis is able to efficiently protect the dental enamel surface from the damage caused by DA and increase the enamel resistance to demineralization. Overall, L. brevis confirms its efficacy in preventing or counteracting the action of carious lesions through a novel mechanism that protects the tooth surface under a chemical challenge that mimics the caries process.

Power Flossing Removes Biofilm From Model Periodontal Pockets In Vitro and Shifts the Microbiome During Biofilm Regrowth.

The Philips® Sonicare® Power Flosser (PSPF) is highly effective in reducing gum disease. Next to effective supragingival cleaning, this may be partially driven by subgingival cleaning. This in vitro study aimed to assess the effectiveness of the PSPF in removing biofilm from a model periodontal pocket up to 6 mm deep and to investigate the taxonomic composition of biofilm regrown after use of the PSPF.

In Vitro Comparison of the Area of Biofilm Removal by the Quad Stream Nozzle Versus a Traditional Oral Irrigator Standard Nozzle.

The objective of this in vitro study was to compare the area of oral biofilm removal by the Philips Sonicare Quad Stream (PSQS) nozzle (used on a Philips® Sonicare® Power Flosser) and a traditional oral irrigator with a standard nozzle (TOIS) when used per the directions for use (DFU) instructions for both devices.

In Vitro Biofilm Removal From Human Enamel Using a Philips® Sonicare® Power Flosser.

The objective of this in vitro study was to quantify the removal of dental biofilm from human enamel surfaces after treatment with the Philips® Sonicare® Power Flosser. Dental biofilms were grown from pooled human saliva on human enamel disks for 4 days, according to an established academic model.* The biofilms (n = 6) were treated with the Philips Sonicare Power Flosser for 3 seconds using the Quad Stream nozzle. To quantify the number of bacteria before treatment, the biofilm volume was measured using optical coherence tomography (OCT) and the bacterial cell density was determined from untreated control samples (n = 6) using confocal laser scanning microscopy (CLSM). After treatment the number of remaining bacteria were counted using CLSM. Additionally, scanning electron microscope (SEM) images were recorded. While before treatment 0.2-mm thick dense biofilms were present, after treatment only scattered groups of bacteria remained (Figure 1 through Figure 4). Quantitative analysis showed 99.96% removal for the Quad Stream nozzle. The Philips Sonicare Power Flosser oral irrigator with Quad Stream nozzle removed over 99.9% of the bacteria in this established laboratory model of dental biofilm.

Effect of Printing Layer Thickness on Optical Properties and Surface Roughness of 3D-Printed Resins: An In Vitro Study.

PURPOSE: To investigate the impact of printing layer thickness on the optical properties and surface roughness of various 3D-printed resins manufactured by digital light processing (DLP) and indicated for provisional and definitive restorations. MATERIALS AND METHODS: A total of 240 specimens from four different 3D-printing resins-VarseoSmile Crown Plus (Bego; VS), Crowntec (Saremco Dental; CR), GC Temp PRINT (GC Dental; TG), and NextDent C&B MFH (NextDent; ND)-were divided into four groups (n = 60 per group). Each group was further divided into three subgroups (n = 20) according to printing layer thickness (25, 50, and 100 µm). All specimens were subjected to thermocycling with coffee before measurements were taken with a spectroradiometer to calculate color differences. The Kubelka-Munk (K-M) absorption (K) and scattering coefficients (S), translucency parameters (TP), and surface roughness (Ra) values were calculated for each printing layer thickness and compared with those of the 2M2 shade tab (target). The data were analyzed using Mann-Whitney U test, the variance accounted for (VAF) coefficient by Cauchy-Schwarz, and post hoc comparisons using Tukey test (α ≤ .05). RESULTS: S (79% ≤ VAF ≤ 100%) and K (40.45% ≤ VAF ≤ 100%) spectral distribution depended on the wavelength. A 25-µm layer thickness resulted in no significant differences from the 2M2 shade for S (P > .230) and K (P > .200). VS showed significantly different S (P = .004) and K (P = .003) values from those of the shade tab with 50-µm layering thickness, whereas other materials did not show significant differences from the 2M2 shade for S (P > .280) and K (P > .301). The 100-µm layer thickness specimens had significantly different S and K values compared to the 2M2 shade tab (P < .004). TP values of resins with 100-µm layer thickness were significantly lower than resins in 25- and 50-µm layer thicknesses (P < .001). The Ra values of resins increased significantly with 100-µm layer thickness (P ≤ .001). CONCLUSIONS: All tested materials, except for VS, showed color properties similar to the target shade when 25- and 50-µm printing layer thicknesses were used. The translucency of resins tended toward an inverse relationship with printing layer thickness. The surface roughness of resins increased significantly with 100-µm layer thickness. However, all resins with a printing thickness of 25 µm showed better color properties and surface roughness.

Manufacturing Accuracy, Intaglio Surface Adaptation, and Survival of Additively and Subtractively Manufactured Definitive Resin Crowns After Cyclic Loading: An In Vitro Study.

PURPOSE: To assess the manufacturing accuracy, intaglio surface adaptation, and survival of resin-based CAD/CAM definitive crowns created via additive manufacturing (AM) or subtractive manufacturing (SM). MATERIALS AND METHODS: A maxillary right first molar crown was digitally designed and manufactured using AM hybrid resin composite (VarseoSmile Crown Plus, Bego [AM-HRC]), AM glass filler-reinforced resin composite (Crowntec, Saremco Dental [AM-RC]), and SM polymer-infiltrated ceramic (Vita Enamic, VITA Zahnfabrik [SM-PICN]). Manufacturing accuracy (trueness and precision) was assessed by computing the root mean square (RMS) error (in µm; n = 15 per material). Intaglio surface adaptation was assessed by calculating the average gap distance (µm). Ten crowns from each group were cemented on fiberglass-reinforced epoxy resin dies and cyclically loaded to simulate 5 years of functional loading. One-way ANOVA, post hoc Bonferroni comparison tests, and Levene's test were used to analyze the data (α = .05). RESULTS: AM-RC had higher overall trueness than AM-HRC and SM-PICN (P ≤ .05), whereas the trueness of AM-RC on the external surface was similar to that of SM-PICN (P = .99) and higher than AM-HRC (P = .001). SM-PICN had lower precision than AM-RC and AM-HRC overall and at internal occlusal surfaces (P ≤ .05). Overall intaglio surface adaptation was similar between all groups (P = .531). However, for the axial intaglio surface, AM-RC and AM-HRC had higher adaptation than SM-PICN (P ≤ .05). All tested crowns survived the cyclic loading simulation of 5 years clinical use. CONCLUSIONS: AM-RC showed high manufacturing accuracy and adaptation. The tested resin-based CAD/CAM materials demonstrated clinically acceptable manufacturing accuracy and simulated medium-term durability, justifying the initiation of clinical investigations to determine their potential implementation in daily clinical practice.

The Effects of Reusing Cobalt-Chromium Alloy Powder on Its Mechanical Properties and Grain Size: An In Vitro Study.

PURPOSE: To characterize material changes that may occur in virgin cobalt-chromium (Co-Cr) alloy powder when it is blended with alloy powders that have been reused multiple times. MATERIALS AND METHODS: Initially, 20 kg of virgin Co-Cr powder was loaded into a laser-sintering device. The tensile test specimens were fabricated in the first (Group 1), fourth (Group 2), seventh (Group 3), tenth (Group 4), and thirteenth (Group 5) production cycles (N = 15). Prior to fabricating the specimens, powder alloy samples were collected from the powder bed for analysis. The tensile strength, elastic modulus, and percent elongation were calculated with tensile testing. Scanning electron microscopy and energy dispersive x-ray spectroscopy (SEM/EDS) and laser particle size distribution (LPSD) were used to analyze the alloy powder samples. The fracture surface of one tensile test specimen from each group was examined via SEM/EDS. One-way ANOVA followed by Dunnett T3 test was used for statistical analysis (α = .05). RESULTS: No difference was observed between groups in terms of tensile strength. A statistically significant difference was observed between Groups 1 and 2 in terms of percent elongation. Groups 2 and 4 were statistically significantly different in terms of both elastic modulus and percent elongation (P ≤ .05). SEM images of the powder alloy showed noticeable differences with increasing numbers of cycles. SEM images and the EDS analysis of the fractured specimens were in accordance with the strength data. CONCLUSIONS: Reusing Co-Cr alloy powder increased the particle size distribution. However, there was no correlation between increased cycle number and the mechanical properties of the powder.

Enhancing Bond Strength of 3D-Printed Resin Posts Using Various Surface Pretreatments: An In Vitro Study.

PURPOSE: This study investigated the impact of common surface pretreatments on the contact angle (CA), surface free energy (SFE), and push-out bond strength (PBS) of custom 3D-printed resin posts. MATERIALS AND METHODS: Post spaces of 60 endodontically treated mandibular premolars were prepared. Custom 3D-printed posts made from permanent crown resin were fabricated for 50 randomly selected post spaces. The specimens were then divided into six groups (n = 10) based on their surface pretreatment methods. These methods included sandblasting (SB), silane (SL), hydrofluoric acid (HF), and hydrogen peroxide (HP). Additionally, two control groups were established: glass fiber control (GFC) and permanent resin control (PRC). CA and SFE were measured for each 3D-printed post group. PBS and failure mode analyses were conducted. The data were analyzed using the two-way ANOVA followed by the Tukey post hoc test (α = .05). RESULTS: The lowest CA values were found in the SB and SL groups. The SB group had the highest SFE compared to all other groups. SL markedly enhanced the PBS of the resin post compared to the PRC at the cervical, middle, and apical levels (P = .001, P = .000, and P = .002, respectively), and the values were comparable to those of the GFC (P = .695, P = .999, and P = .992, respectively). Except in the GFC, SB, and SL groups, mixed failure decreased from the cervical to apical levels, while adhesive failure rates increased. CONCLUSIONS: The application of silane and sandblasting to the surfaces of custom 3D-printed resin posts effectively increased their SFE, thereby enhancing their adhesion.

Positional Trueness with Different Titanium Base Bonding Techniques for Single Implant Crowns: In Vitro Evaluation of Model-Free Workflow Versus Additively Manufactured Models.

OBJECTIVES: To compare the positional trueness of implant-crown bonding to titanium bases (Ti-bases) using different bonding protocols. MATERIALS AND METHODS: A nonprecious alloy model with a single implant at the mandibular right first molar site was digitized, then a single implant crown was designed. The crown was milled, adhesively cemented on a Ti-base, and screw-retained on the implant in the master model to obtain a reference scan. Forty PMMA implant crowns were subtractively manufactured and allocated to one of four study groups (n = 10 crowns per group) based on the bonding protocol on Ti-bases: Group 1 = modelfree bonding; Group 2 = bonding on the master model (control); Group 3 = bonding on a model from an industrial-grade 3D printer (Prodways); Group 4 = bonding on a model from a conventional 3D printer (Asiga). To assess the positional trueness of crowns, the scans of crowns when on the model were superimposed over the reference scan. Median distance and angular deviations were analyzed using Kruskal-Wallis and Mann- Whitney tests (α = .05). Mesial and distal contacts of crowns were assessed by two independent clinicians. RESULTS: The control group (Group 2) resulted in the smallest distance deviations (0.30 ± 0.03 mm) compared to model-free (0.35 ± 0.02 mm; P = .002; Group 1) and conventional 3D printer (0.37 ± 0.01 mm; P = .001; Group 4) workflows. Buccolingual (P = .002) and mesiodistal (P = .01) angular deviations were higher in the conventional 3D printer group than in the control group (P = .002). Proximal contact assessments did not show any differences among groups. CONCLUSIONS: While bonding crowns to Ti-bases on a master model created with an industrial-grade 3D printer resulted in the highest positional trueness, model-free workflows had a similar positional trueness to those manufactured with a conventional 3D printer.

Bacterial sealing ability of calcium silicate-based sealer for endodontic surgery: an in-vitro study.

BACKGROUND: Apical surgery with standard retrograde maneuvers may be challenging in certain cases. Simplifying apical surgery to reduce operating time and streamline retrograde manipulation is an emerging need in clinical endodontics. AIM OF THE STUDY: The aim of the study was to compare the bacterial sealing ability of a calcium silicate-based sealer with the single cone technique combined with root end resection only, and calcium silicate-based sealer as a retrograde filling versus MTA retrofilling, and to analyze bacterial viability using confocal laser scanning microscope (CLSM). MATERIALS AND METHODS: In this in vitro experimental study, 50 extracted human maxillary incisor teeth were instrumented and randomly divided into five groups: three experimental groups, a positive control group, and a negative control group (n = 10/group). In the experimental groups, the roots were obturated using the single cone technique (SCT) and a calcium silicate-based sealer. In group 1, the roots were resected 3 mm from the apex with no further retrograde preparation or filling. In groups 2 and 3, the roots were resected, retroprepared, and retrofilled with either a calcium silicate-based sealer or MTA, respectively. Group 4 (positive control) was filled with a single gutta-percha cone without any sealer. In group 5 (negative control), the canals were left empty, and the roots were sealed with wax and nail varnish. A bacterial leakage model using Enterococcus faecalis was employed to assess the sealing ability over a 30-day period, checking for turbidity and analyzing colony forming units (CFUs) per milliliter. Five specimens from each group were examined using CLSM for bacterial viability. Data for the bacterial sealing ability were statistically analyzed using chi-squared and Kruskal-Wallis tests. RESULTS: The three experimental groups did not show significant differences in terms of bacterial leakage, or bacterial counts (CFUs) (P > 0.05). However, significant differences were observed when comparing the experimental groups to the positive control group. Notably, the calcium silicate-based sealer, when used as a retrofilling, yielded the best sealing ability. CLSM imaging revealed viable bacterial penetration in all the positive control group specimens while for the experimental groups, dead bacteria was the prominent feature seen. CONCLUSION: Within the limitations of this study, it could be concluded that the bacterial sealing ability of calcium silicate-based sealer with the single cone technique combined with root end resection only and calcium silicate-based sealer as a retrograde filling were comparable with MTA retrofilling during endodontic surgical procedures.