Journal of dentistry (Shiraz, Iran)最新文献

Statement of the problem: Dentin bonding with etch-and-rinse adhesives involves demineralizing the 5-8µm of the surface dentin to create micro space for resin infiltration. The presence of continuous fluid movement in dentin tubules and positive pulpal pressure prevents complete water replacement by resin monomers. This results in areas of demineralized dentin, which contain collagen fibers without resin infiltration. The exposed collage fibers are subjected to enzymatic degradation leading to less durable hybrid layer.

Purpose: The aim of this study was to evaluate the remineralizing effect of the nanoparticles on the resin dentin bonding interface.

Materials and method: The three experimental remineralizing nanoparticles were characterized for their morphology, size, and composition. A total of 48 extracted non-carious human third molar teeth were sectioned at 2 mm below the cemento enamel junction. Class I cavity was prepared and the tooth samples were placed in an intra pulpal pressure simulation device. After etching of the prepared cavity, the samples were randomly divided into four groups (n=10) as follows: (1) control group(c) (n=10) (2) Nano-hydroxyapatite (nHAP) (n=10) (3) Chitosan-nanohydroxyapatite (Chi-nHAP) (n=10) (4) Mesoporous silica-hydrox-yapatite (MS-nHAP) (n=10). After 30 days remineralization period, the samples were evaluated for micro tensile bond strength, hybrid layer morphology, and mineral composition of the hybrid layer. The results were analyzed statistically by one-way ANOVA and Tukey's multiple post hoc tests.

Results: Scanning electron microscopic observation of nanoparticles revealed irregular particle shapes with calcium phosphate ratio of 1.60. The zeta analyzer showed a mean diameter of 161.0 nm, 323.0nm, 185.0nm for nHAP, Chi-nHAP, and MS-nHAP respectively. Post hoc Bonferroni test revealed significantly higher bond strength for nHAP, Chi-nHAP, and MS-nHAP when compared to control group. MS-nHAP resulted in the uniform deposition of apatite crystal on the surface without any evidence of dentinal tubules openings and had higher mineral to matrix ratio compared to other groups.

Conclusion: MS-nHAP nanoparticles can be considered as a reliable source of calcium and phosphate for biomimetic remineralization of hybrid layer. Application of nanoparticle remineralization precursors before application of dentin bonding agents results in remeralization of exposed collagen fibers thereby improving the clinical longevity of hybrid layer.

Statement of the problem: Dentin adhesion is challenging and needs modifications. Newly introduced nature-derived materials may be a useful solution in improving dentin adhesion. The use of natural antimicrobial agents for pretreating prepared dentin surfaces before restoration has become of interest.

Purpose: The present study investigated the effect of natural compounds on the shear bond strength (SBS) of resin composite adhesively bonded to dentin.

Materials and method: Sixty extracted human molar teeth were randomly divided into six groups (n= 10); Group I: two-step etch and rinse adhesive system, Adper Single Bond 2 (SB₂) (experimental control), Group II: 2.5% Chitosan+etch+SB₂, Group III: 15% Neem (Azadirachta indica)+etch+SB₂, Group IV: 15% Tulsi (Ocimum sanctum)+etch+SB₂, Group V: 2% Aloe vera+etch+SB₂, and group VI: 2% Chlorhexidine (CHX)+etch+SB₂. Resin composite (Z350, 3M ESPE USA) was placed over the prepared dentin surfaces and was light cured. Data analysis was performed using One-way ANOVA and post hoc Tukey's test (p< 0.05).

Results: Neem specimens showed the highest mean SBS, statistically greater than the control (p= 0.042). Other experimental groups showed no significant differences in SBS comparison to the control. The mean SBS values of 2.5% Chitosan, 15% Neem, 15% Tulsi, and 2% Aloe vera were significantly higher than 2% CHX (p= 0.046, p= 0.001, p= 0.010 and p= 0.002 respectively).

Conclusion: Dentin pretreatment with Neem may improve the bond strength of a two-step etch and rinse adhesive system. The application of Chitosan, Tulsi, Aloe vera, and CHX did not demonstrate significantly different SBS values from that of the Control, although CHX was lower.

Statement of the problem: One of the main signs of cancer development is increasing of cell proliferation activity. Expression of the Ki-67 as a cell proliferation marker is extensively utilized in pathology studies as an indicator of proliferation in human tumors. According to studies, Ki-67 plays an effective role in the pathology of malignant and pre-malignant oral mucosa lesions.

Purpose: The current study aimed to systematically review the Ki-67 expression in oral lichen planus without dysplasia and compare it with oral epithelial dysplasia.

Materials and method: In this meta-analysis, all articles in the English language were searched in databases including Web of Science, PubMed, Embase, Scopus, and Google Scholar until July 2023. MeSH terms and free keywords were used in the search step. Expression of Ki-67 in oral lichen planus and oral epithelial dysplasia was analyzed by Comprehensive Meta-Analysis software.

Results: Nine hundred and two articles related to the searched words were found. According to the selection criteria, 12 retrospective articles were selected. Low quality was not observed in any of the records by the Newcastle-Ottawa scale and most of them had a relatively good quality. Totally, 593 patients were examined. The heterogeneity between studies was not significant. The meta-analysis results indicated a significantly lower Ki-67 expression in oral lichen planus without dysplasia in comparison to oral epithelial dysplasia.

Conclusion: The more intense expression level of Ki-67 in oral epithelial dysplasia compared with oral lichen planus was observed. The ki-67 expression could be utilized to indicate the existence and intensity of epithelial dysplasia and disease progression.

Statement of the problem: Antimicrobial photodynamic therapy (aPDT) is a protocol proposed for reduction of bacterial load in deep dentin caries in primary and permanent dentitions. However, considering the difference in the morphology of dentinal tubules in primary and permanent teeth, the effect of this treatment may be different on the two dentition types.

Purpose: This systematic review and meta-analysis aimed to assess the effect of type of dentition as a determinant of microbial load reduction by aPDT in deep dentin caries.

Materials and method: An electronic search was conducted in Scopus, Web of Science, Cochrane, Medline, and Embase databases, from the first record until April 30, 2022. After article screening by three reviewers, seven studies were included in this meta-analysis. The mean log of Streptococcus mutans (S. mutans) count, Lactobacillus spp. count, and the entire bacteria in the cavity before and after aPDT was calculated with 95% confidence interval (CI), and compared between the two groups of primary and permanent teeth by the random effect model. The I² test was applied to assess the heterogeneity of the findings. Publication bias was evaluated by visual examination of the funnel-plot symmetry.

Results: Of 7 retrieved articles, analysis of 3 studies on permanent teeth showed that aPDT caused a significant reduction in total bacterial count in the cavity [SMD: 0.64, 95% CI:(0.31, 0.96), p= 0.0001), S. mutans count [SMD: 0.92, 95% CI:(0.58, 1.25), p< 0.0001], and Lactobacillus spp. [SMD: 1.1, 95% CI:(0.76, 1.45), p< 0.00001)]. Analysis of the remaining 4 studies on primary teeth indicated that aPDT had a significant effect only on S. mutans count [SMD: 0.60, 95% CI:(0.23, 0.97), p= 0.001), and its effect on total bacterial count of the cavity [SMD: 0. 90, 95% CI:(-0.02, 1.82), p= 0.05] and Lactobacillus spp. [SMD: 0.18, 95% CI:(-0.29, 0.64), p= 0.45)] was not significant.

Conclusion: The results showed that aPDT could serve as an effective adjunct for reduction of microbial load in permanent teeth.

Statement of the problem: The creation of a proper seal of the root canal with canal-filling materials, such as gutta-percha and sealer, is one of the essential factors in the success of root canal treatment. In addition, the penetration depth of the sealer is one of the influential factors in creating a proper seal, which improves the sealing ability of the canal and the burial of microorganisms.

Purpose: This study aimed to investigate the effect of cold atmospheric plasma on the depth of tubular penetration of two types of resin sealer: AH26 and Beta RCS sealers.

Materials and method: In this experimental study, thirty-two premolar teeth with single root and single canal were selected as samples and after cutting their crowns from the apex distance of 15mm, the canals were prepared with rotary files. Samples were divided into four groups of eight, according to the type of sealer and plasma application: AH26 sealer (AH), plasma+AH26 sealer (PAH), Beta RCS sealer (Beta), and plasma+Beta RCS sealer (PBeta). The cold lateral condensation technique was used for the obturation of canals. The maximum penetration depth and the percentage of sealer penetration were obtained from microscopic images at three coronal, middle, and apical sections. Due to the non-normal distribution of data, the Mann-Whitney U test was used for statistical analysis (p< 0.05).

Results: No significant difference was observed between the study groups in the penetration percentage and maximum penetration depth of AH and Beta in the presence and absence of plasma. However, in the coronal section, the depth of maximum sealer penetration was significantly higher in the AH group than in the Beta group (p< 0.05).

Conclusion: The use of plasma did not affect the maximum penetration depth and penetration percentage of AH26 sealer and Beta RCS sealer.

This study investigates the calcifications in the parotid glands of a patient with Sjögren's syndrome (SS). A 52-year-old female patient presented for a routine dental examination who found to have multiple radiopacities in both parotid glands on panoramic radiograph. Further evaluation revealed swelling and tenderness in the parotid glands, decayed teeth, and dryness of the mouth and eyes. Ultrasound examination showed enlarged parotid glands with heterogeneous echogenicity, hypoechoic and cystic foci, and multiple calcifications. Laboratory tests indicated positive findings for rheumatoid factor and anti-SSA/SSB antibodies, consistent with a diagnosis of Sjögren's syndrome. Treatment primarily focuses on relieving symptoms and preventing clinical manifestations.

Statement of the problem: Success of pulpotomy of primary teeth depends on biological and cytotoxic effects of pulp capping agents. Mineral trioxide aggregate (MTA), Biodentine, calcium enriched mixture (CEM) cement, and ferric sulfate (FS) are among the commonly used pulp capping agents (PCAs) for pulpotomy, and their successful application has been previously evaluated.

Purpose: This study aimed to compare the cytotoxicity of PCAs against mesenchymal stem cells isolated from human exfoliated deciduous teeth (SHEDs).

Materials and method: In this in vitro study, SHEDs were exposed to MTA, Biodentine, CEM cement, and FS for 24 and 72 hours. The methyl thiazolyl tetrazolium (MTT) assay was performed for five different concentrations of PCAs after 24 and 72 hours of exposure. Data were analyzed by ANOVA.

Results: Generally, the biocompatibility increased by reduction in concentration. All tested concentrations showed higher biocompatibility at 72 hours compared with 24 hours (p< 0.0001). Comparison of cytotoxicity of different biomaterials revealed no significant difference at any time point (p> 0.05).

Conclusion: In general, the cytotoxicity of MTA, Biodentine, CEM cement, and FS was comparable, with no significant difference. Cytotoxicity decreased over time and by a reduction in concentration of biomaterials. MTA and Biodentine showed maximum biocompatibility followed by FS, and CEM cement.

Statement of the problem: One of the most important factors in the clinical longevity of composite resin restorations is proper adhesion, which is achieved using phosphoric acid. Different phosphoric acid products might affect the micro-shear bond strength of composite resin to enamel.

Purpose: The present study aimed to evaluate the micro-shear bond strength of composite resin to sound enamel using six different brands of acid-etch agents.

Materials and method: The present in vitro study was carried out on 72 extracted sound human (mandibular and maxillary) first premolar teeth. The teeth crowns were divided into two equal parts with a mesiodistal cut and randomly assigned to six groups in terms of the acid etchant brand: Ultra-etch, SDI, Morvabon, FGM, Nik Darman, and Experimental. The bonding procedure was carried out using the Margin Bond enamel adhesive. Tygon tubes (1×0.7 mm) containing composite resin were bonded to each enamel surface. After 24 hours of storage in distilled water, each sample underwent a shearing force with a crosshead speed of 0.5 mm/min. The morphologic changes were evaluated using scanning electron microscopy. The data were analyzed with SPSS using one-way ANOVA and Tukey test (p< 0.05).

Results: One-way ANOVA showed that micro-shear bond strength in different etchant agents have significant differences (p< 0.001). The highest and lowest composite resin micro-shear bond strengths belonged to Ultradent and SDI brands, respectively. The enamel surfaces in the SDI group revealed residual debris after dissolution.

Conclusion: Preparation of the enamel surface with different phosphoric acid products might affect the micro-shear bond strength and enamel surface morphology differently. Further clinical studies are suggested to evaluate the effect of different types and concentrations of acid etching agents on the enamel and dentin bonds.

Medical emergencies, though rare, may occur unpredictably in a dental office during or after dental procedures. It may occur accidentally or subsequent to systemic problems of patients. These series of clinical events entail instantaneous management to evade any potential consequences. Basic life support measures require sufficient knowledge, expertise, skills, and equipment. Several medications and equipment are necessary to be available for immediate reach in any dental office. Health authorities of different countries usually propose these lists to dental practitioners. However, the best emergency kit is the one, which is arranged and maintained by the dentists based on their needs and easily accessible for immediate use. Considering the importance of this subject and the results yielded from the regular visits of the Dental Supervision Department (Vice Chancellor for treatment of Shiraz University of Medical Sciences) to the dental centers of Shiraz in the spring and summer of 2023, we decided to recall the importance of emergency medicines and equipment through a brief communication.

Schwannomas are considered benign soft tissue tumors that originate from Schwann cells. Oral Schwannomas are rare and account for only 1% of all Schwannomas. Cellularschwannoma (CS) is a rare histological variant of schwannoma, characterized by high cellularity and cellular atypia. We present a case of localized growth of palatal mucosa that imitated the features of malignant peripheral nerve sheath tumor (MPNST) on histopathological examination; it was differentiated from MPNST by the correlation of clinical, histopathological, and immunohistochemical features.