ABSTRACT Background: This study evaluated enamel surface alterations during dental erosion and compared the protective effects of two fluoride varnishes using atomic force microscopy (AFM). Materials and Methods: In this in vitro experimental study, 20 caries-free teeth were sectioned, yielding 18 suitable enamel blocks. Baseline surface roughness was measured by AFM, and specimens were randomly assigned to three groups ( n = 6): untreated control, Florish, and FluoroDose. After varnish application, specimens underwent standardized pH cycling consisting of immersion in an Iranian carbonated beverage for 5 min, four times daily, with 1-h remineralization intervals in artificial saliva. Postcycling surface topography was reassessed for average roughness (Ra) and root mean square roughness (Rq). Intergroup comparisons were performed using one-way analysis of variance with Tukey’s honestly significant difference post hoc test, and intragroup changes were assessed using paired t -tests (α = 0.05). Results: Baseline Rq ranged from 18.09 to 67.68 nm (mean 40.55 ± 14.5 nm), and Ra ranged from 15.12 to 59.42 nm (mean 32.4 ± 12.6 nm). After erosion, the control group showed a marked increase in Rq, reaching 71.6–277.5 nm (mean 163.0 ± 76.3 nm). Posterosion Rq was significantly lower in the Florish (63.3 ± 9.7 nm) and FluoroDose (60.0 ± 10.6 nm) groups. Both varnishes significantly reduced Ra and Rq compared with the control ( P = 0.003 and P = 0.004, respectively), with no significant difference between varnishes ( P > 0.05). Conclusion: Both fluoride varnishes reduced acid-induced enamel roughening in vitro . Florish showed protective efficacy comparable to FluoroDose and may represent a practical domestic alternative, although clinical studies are needed to confirm effectiveness under dynamic oral conditions and establish its long-term preventive value in practice.
ABSTRACT Background: The rising demand for effective bone graft materials stems from the limitations of autografts, such as limited availability and donor site morbidity. Cuttlebone, a natural and abundant calcium carbonate source, exhibits potential as an alternative due to its structural properties. This in vitro study evaluated bone powders derived from cuttlebone processed by two decellularization methods, such as hydrothermal and chemical–enzymatic, to compare their physicochemical and biological characteristics for bone graft applications. Materials and Methods: In this in vitro study the thermal processing method removed all organic components of the cuttlebone samples, while the enzymatic method retained collagen proteins. The resulting bone powders were characterized using scanning electron microscopy, X-ray diffraction, Fourier transform infrared spectroscopy, energy-dispersive X-ray spectroscopy, and Brunauer–Emmett–Teller analysis. Cytotoxicity and biocompatibility were evaluated using the MTT assay and cell adhesion test. Data were analyzed using one-way ANOVA test with a significance level of <0.05 and Tukey’s test for pairwise comparisons. Results: Enzymatically processed samples retained collagen and showed higher surface area, porosity, and cell adhesion, whereas thermally processed samples were crystalline but cytotoxic. MTT assays demonstrated that the enzymatic group showed over 100% cell viability, indicating excellent biocompatibility, while thermal samples exhibited below 70%. Conclusion: Overall, enzymatically processed cuttlebone demonstrated superior structural features that enhanced cell–surface interactions and biocompatibility, suggesting it as a potential alternative for craniofacial bone tissue engineering applications.
ABSTRACT Background: Restoration strength can be affected by differences in proximal box heights of mesio-occluso-distal (MOD) cavities. Leveling the box depths in MOD cavities using deep margin elevation (DME) can indirectly affect the restoration’s stress distribution. Materials and Methods: The study design was based on finite element analysis (FEA). Ten mandibular first molars with MOD cavities were modeled with varying proximal box depths and restored with either composite or ceramic inlays, with or without deep margin elevation (DME). Models were numerically analyzed using FEA. A force of 200 N was applied obliquely to the occlusal surface of the tooth. Stress distribution in the tooth and restorations was analyzed using the von Mises criterion. Results: Results showed that increasing unilateral depth of the proximal box had no effect on stress distribution in dentin and ceramic inlay and only led to an increase in stress of composite inlay. Application of DME exhibited no effect on the decrease of stress in these groups. By increasing bilateral depth of proximal boxes, stress on dentin increased. Use of bilateral DME reduced stress generated in dentin layer, which was more effective in ceramic inlay group. Compared to composite inlays, ceramic inlays tend to concentrate more stress, which resulted in reduced stress on tooth and possibility of tooth fracture. Conclusion: Different proximal depths of cavity box affected mechanical behavior of restored tooth. DME application was more effective on stress values in bilateral deep cavities compared to unilateral deep cavities.
ABSTRACT Background: Periapical bleeding is a significant complication that can hinder the completion of root canal treatment. This study aimed to evaluate the effectiveness of tranexamic acid in controlling periapical bleeding during root canal procedures. Materials and Methods: In a randomized, blinded clinical trial, 40 patients requiring root canal treatment were randomly assigned to intervention (tranexamic acid) or control (normal saline) groups using a computer-generated sequence with allocation concealment. After access cavity preparation and canal shaping with ProTaper Next rotary files to size X2 under 2.5% sodium hypochlorite irrigation, if bleeding persisted beyond 10 min, the intervention group received 1 cc of tranexamic acid injected via a 27-G regular insulin syringe, while the control group received 1 cc of normal saline. Bleeding cessation was assessed by inserting a sterile paper point to the working length at 3, 6, and 10 min; cessation was defined as no visible blood staining on the paper point. The outcome assessor was blinded to group allocation. Data were analyzed using the Mann–Whitney U test, with statistical significance set at P < 0.05. Results: The mean bleeding cessation time was 1.75 ± 0.063 min in the tranexamic acid group compared to 3.35 ± 0.93 min in the saline group. The Mann–Whitney test revealed a statistically significant difference ( P < 0.001). Conclusion: Tranexamic acid effectively controls periapical bleeding within 10 min during root canal therapy, allowing continuation of the procedure in the same session. Further studies are needed to evaluate its safety profile and impact on long-term treatment outcomes.
ABSTRACT Background: Defects of significant size in the mandible require bone graft regeneration. Tissue engineering presents an innovative approach to address these issues. The purpose of this study was to evaluate the quality of bone formation in large mandibular defects in canines utilizing adipose-derived stem cells (ASCs). Materials and Methods: In this experimental study, six dogs were examined. The study design included collecting samples from the adipose tissue of adult dogs, isolating adipose-derived mesenchymal stem cells, culturing ASCs in Dulbecco’s Modified Eagle Medium supplemented with 1% penicillin–streptomycin, identifying canine ASCs, grafting the ASCs into gelatin foam, and conducting surgery to produce a standardized defect. In the control group, the defect was treated with a titanium plate and gelatin foam, whereas in the treatment group, the titanium plate, gelatin foam, and ASCs were used. After 6 months, mandibular biopsies were performed to evaluate bone tissue architecture using histological techniques and immunohistochemistry to assess osteocalcin protein expression as an indicator of bone tissue formation within the defect. Results: Findings from hematoxylin and eosin and Alizarin Red staining demonstrated the development of mature bone characterized by a structured Haversian system and significant vascularization in the ASC-treated group. Based on immunohistochemical findings, application of ASCs on gelatin foam resulted in detectable osteocalcin expression within the large bone defects. Conclusion: In mandibular defects, the ASC-treated group exhibited superior bone tissue quality compared with the control group.
