IntroductionMicrobial infection plays an important role in persistent periapical lesions.1 Insufficient disinfection of root canals could lead to treatment failure and persistent periapical pathology. 2Conventional techniques of root canal treatments such as mechanical instrumentation and chemical debridement with antimicrobial irrigants, such as sodium hypochlorite (NaOCl), chlorhexidine and calcium hydroxide do not always suffice to predictably render root canals free of bacteria.3,4 Factors such as anatomical complexities, bacterial growth as biofilm, render complete disinfection of the root canal system almost impossible. 5Studies have revealed a success rate of 94% with a negative culture before obturation has decreased to 68%, with a positive culture.2 Resolution of periapical lesions is more achievable when there is negative culture before obturation. 6Cross sectional studies have reported 20%-60% of treatment failure and 52% of endodontic failure in Iranian population.7-10 Existence of intracanal microorganisms would lessen the treatment outcomes of endodontic re-treatment comparing to primary endodontic treatment. 2Based on the previous studies, bacterial microflora in teeth with failed endodontic treatment is different from the microflora of the primary endodontic infection. All culture and PCR based methods have shown that primary endodontic infection is a polymicrobial infection involving fully anaerobic microorganisms, 5,11 while the failure AbstractIntroduction: The aim of this study was to compare the antibacterial efficacy of diode laser 810nm and photodynamic therapy (PDT) in reducing bacterial microflora in endodontic retreatment of teeth with periradicular lesion. Methods: In this in vivo clinical trial, 20 patients who needed endodontic retreatment were selected. After conventional chemo mechanical preparation of root canals, microbiological samples were taken with sterile paper point (PP), held in thioglycollate broth, and then were transferred to the microbiological lab. In the first group, PDT with methylene blue (MB) and diode laser (810 nm, 0.2 W, 40 seconds) was performed and in the second group diode laser (810 nm, 1.2 W, 30 seconds) was irradiated. Then second samples were taken from all canals. Results: CFU/ml amounts showed statistically significant reduction in both groups (P < 0.001). CFU/ml amounts were compared between the two groups and there was no statistical difference. Conclusion: PDT and diode laser 810 nm irradiation are effective methods for root canal disinfection. PDT is a suitable alternative for diode laser 810 nm irradiation, because of lower thermal risk on root dentin.
Vitamin D participates in the calcification of enamel and dentin and the appropriate immune responses to oral microbial infections. We aimed to assess the association between the most common vitamin D receptor (VDR) polymorphisms (ApaI,FokI, TaqI, BsmI, and BglI) and the risk of dental caries in children. Methods: PubMed/MEDLINE, Cochrane Library, Web of Science, and Scopus databases were comprehensively searched until 19 January 2021. Meta-analysis with odds ratios as the effect estimate along with 95% confidence intervals and subgroup analysis were conducted using Review Manager 5.3 software. Publication bias and sensitivity analyses were conducted by Comprehensive Meta-Analysis, version 2.0 software. Results: Seventy-eight studies were retrieved from the databases, with nine studies included in the final analysis. Based on five genetic models, there was no association between ApaI (rs7975232), TaqI (rs731236), BsmI (rs1544410), FokI (rs2228570), and BglI (rs739837) polymorphisms and susceptibility to dental caries, except for the FokI (rs10735810) polymorphism. Conclusion: Among the VDR polymorphisms considered, an association was found between the FokI (rs10735810) polymorphism and the risk of dental caries, with a protective role of the f allele and ff genotype.
Background and objective: Inflammation and cell-mediated immunity can have significant roles in different stages of carcinogenesis. The present meta-analysis aimed to evaluate the association between the polymorphisms of IL-8 (-251T/A) and IL-6 (-174G/C) and the risk of oral cancer (OC). Methods: PubMed/MEDLINE, Web of Science, Cochrane Library, and Scopus databases were searched until December 18, 2020 without any restrictions. RevMan 5.3 software was used to calculate the results of forest plots (odds ratios (ORs) and 95% confidence intervals (CIs)); CMA 2.0 software was used to calculate funnel plots (Begg’s and Egger’s tests), and SPSS 22.0 was used for the meta-regression analysis. Moreover, trial sequential analysis was conducted to estimate the robustness of the results. Results: Eleven articles including twelve studies were selected for the meta-analysis. The pooled ORs for the association between IL-8 (-251T/A) polymorphism and the risk of OC in the models of A vs. T, AA vs. TT, TA vs. TT, AA + TA vs. TT, and AA vs. TT + TA were 0.97 (p = 0.78), 0.86 (p = 0.55), 0.78 (p = 0.37), 0.83 (p = 0.45), and 1.10 (p = 0.34), respectively. The pooled ORs IL-6 (-174G/C) polymorphism and the risk of OC in the models of C vs. G, CC vs. GG, GC vs. GG, CC + GC vs. GG, and CC vs. GG + GC were 1.07 (p = 0.87), 1.17 (p = 0.82), 1.44 (p = 0.38), 1.28 (p = 0.61), and 0.96 (p = 0.93), respectively. There was no association between IL-8 (-251T/A) polymorphism and OC susceptibility, but the C allele and GC and CC genotypes of IL-6 (-174G/C) polymorphism were associated with the risk of OC based on subgroup analyses, that is to say, the source of control and the genotyping method might bias the pattern of association. Conclusions: The meta-analysis confirmed that there was no association between the polymorphisms of IL-6 (-174G/C) and IL-8 (-251T/A) and the susceptibility of OC. However, the source of control and the genotyping method could unfavorably impact on the association between the polymorphisms of IL-6 (-174G/C) and the risk OC.
Introduction:Cortical bone is an important anatomical structure and its thickness needs to be determined prior to many dental procedures to ensure treatment success. Imaging modalities are necessarily used in dentistry for treatment planning and dental procedures. Three-dimensional image reconstruction not only provides visual information but also enables accurate measurement of anatomical structures; thus, it is necessarily required for maxillofacial examination and in case of skeletal problems in this region.Aims:This study aimed to assess the ability of three Cone Beam Computed Tomography (CBCT) systems including Cranex 3D, NewTom 3G and 3D Promax for Three-Dimensional (3D) image reconstruction of the cortical plate with variable thicknesses.Methods:Depending on the cortical bone thickness, samples were evaluated in three groups of ≤ 0. 5 mm, 0.6 -1 mm and 1.1-1.5 mm cortical bone thickness. The CBCT scans were obtained from each sample using three systems, their respective FOVs, and 3D scans were reconstructed using their software programs. Two observers viewed the images twice with a two-week interval. The ability of each system in the 3D reconstruction of different thicknesses of cortical bone was determined based on its visualization on the scans. The data were analyzed using SPSS and Kappa test.Results:The three systems showed the greatest difference in the 3D reconstruction of cortical bone with < 0.5 mm thickness. Cranex 3D with 4×6 cm2 FOV had the highest and 3D Promax with 8×8 cm2 FOV had the lowest efficacy for 3D reconstruction of cortical bone. Cranex 3D with 4×6 cm2 and 6×8 cm2 FOVs and NewTom 3G with 5×5 cm2 and 8×5 cm2 FOVs showed significantly higher efficacy for 3D reconstruction of cortical bone with 0.6-1mm thickness while 3D Promax followed by NewTom 3G with 8×8 cm2 FOV had the lowest efficacy for this purpose.Conclusion:Most CBCT systems have high efficacy for 3D image reconstruction of cortical bone with thicknesses over 1 mm while they have poor efficacy for image reconstruction of cortical bone with less than 0.5 mm thickness. Thus, for accurate visualization of anatomical structures on CBCT scans, systems with smaller FOVs and consequently smaller voxel size are preferred.
Background: The inappropriate use of pamphlets rather than textbooks is an educational problem faced by most students. Note-taking and reading pamphlets rather than reading textbooks regardless of defects and shortcomings with their own structure cannot cover the required materials for students. Objectives: The present study aimed to investigate the status of the textbooks used by the dentistry students of Kermanshah University of Medical Sciences (KUMS), Iran. Methods: This descriptive study was conducted on the students of the dentistry school of KUMS. In total, 148 students were selected via random sampling. Data were collected using a valid and reliable questionnaire. Data analysis was performed in SPSS version 18. Results: In total, 67.6% of the students used the content presented by professors in the class, and only 2% used the original English textbooks of dentistry. The analysis of the priorities of the type of resource indicated that the highest frequency belonged to the use of printed pamphlets (55.4%), and the lowest frequency belonged to the use of printed versions and electronic audio files (0.7%). Additionally, evaluation of access to resources showed the maximum frequency of a group pamphlet to be 35.8%, while the lowest frequency belonged to the pamphlet prepared by others (2.7%). Conclusions: According to the results, the students showed great interest in note-taking and reading pamphlets rather than reading textbooks. The insufficient fluency of students in English, high costs of reference books, and a large amount of resources made the students more likely to use pamphlets.
Background: The laser is utilized for the removal of the smear layer, cleaning and disinfecting the dental canal. Recently, diode laser has been offered with a wavelength of (635-980nm) for cleaning and disinfecting the dental root canal. Objective: There is not adequate evidence for microcrack formation when using diode lasers with different powers. Therefore, the present study was conducted in order to analyze various powers of a diode laser in microcrack formation in dental root canals. Methods: In this experimental study, 100 mandibular incisor teeth that were extracted because of periodontal disease were selected. Using stereo-microscope, the presence of crack and fracture of the root was evaluated before and after canal instrumentation. Then, samples were randomly divided into 10 groups (10 samples in any group) based on different powers of laser and canal to be humid or dry under laser radiation. The laser was utilized for 10s puls within three iterated times. The samples were cross-sectioned after disinfection with a diode laser at 3 and 6mm length from the dental apex. Sections were observed under a scanning electron microscope and images were taken. Results: The frequency of microcracks is increased at the distance of (3-6mm) from the dental apex by an increase in laser power level from 2 to 4w (P<0.05). Similarly, results showed that the probability of microcrack formation under dry condition than the humid condition at the distance of 3mm from the dental apex might increase to 6.606 times and at the distance of 6mm from the dental apex increase to 4.978 times more. Conclusion: The optimal power of diode laser in the wavelength of (980nm) for cleaning and disinfecting of the root canal with the minimum damage on hard periodontium tissue is 1.5w.
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