Journal of Dentistry
Year:2021 | Volume:22 | Issue:1|Papers Count:12

Statement of the Problem: The efficacy of erbium-doped yttrium aluminum garnet (Er: YAG) laser on the debonding properties of certain post materials has remained largely unex-plored. Purpose: This study aimed to investigate the effect of Er: YAG laser irradiation on debond-ing of cemented glass fiber posts in root canal treated teeth. Materials and Method: In this in vitro study, forty root canal treated mandibular premolar teeth were used in this study. Glass fiber posts were bonded using Panavia F 2. 0 cement in the root canal space, and samples were divided into two groups. In the test group, samples were exposed to laser radiation of 7W, 350mJ, frequency of 20Hz and discontinued washing spray. In the control group, samples were left untouched. In each group, samples were sectioned into 1. 5mm thick slices from the coronal, middle, and apical thirds of the root (N=120). Tensile bond strengths were evaluated using the push-out test and the failure patterns were evaluated using scanning electron microscopy (SEM). To compare the laser and non-laser groups at each location, independent sample t test was applied, and to compare bond strength between the locations in each group, one-way ANOVA and Tukey’ s HSD post hoc was applied. Results: A significant difference in tensile strength was observed between the laser-irradiated group and control group; tensile bond strength was much higher in the control group (p<0. 001). The highest frequency of fractures was observed at the cement-dentin interface. Given the used parameters, complete debonding was not achieved in the laser-irradiated group. Conclusion: Laser radiation reduced the bond strength of glass fiber posts to resin cement without complete debonding.

Statement of the Problem: The mechanisms of operation of dental scanners are based on different technologies. Considering these differences, there are many types of scanners available in the market. Purpose: This in vitro study aimed to compare the accuracy (precision and trueness) of seven commonly used dental scanners. Materials and Method: In this in vitro experimental study, the accuracy of 7 common extra oral scanners (Sirona ineos inLab, Sirona X5, Dentium, Imes Icore 350I, Amann Girrbach, 3shape D700, and 3Shape E3) were evaluated. Each of scanners performed 7 scans of im-plant abutment of SIC (SIC MAX. GH1). Data from each scanner were then compared to data received from 3Shape Trios intra oral scanner as a reference. For evaluating the accura-cy of each scanner, trueness and precision was evaluated. Collected data were analyzed using Kruskal Wallis and Bonferroni tests via SPSS version 22. Results: Descriptive statistics showed the best trueness was for 3Shape E3 scanner with the average of 35. 37μ m and the worst trueness belonged to Sirona x5 scanner with the average of 51. 75μ m. Furthermore, the best precision was achieved for 3Shape E3 scanner with the average of 35. 34, while the lowest precision was detected in 3Shape D700. The scanners had statistically significant differences with each other in terms of trueness and precision (p<0. 05). Conclusion: Based on the results of this study, the extra oral scanner, 3shape E3, had the best trueness and precision. The lowest amount of trueness among the studied scanners was for the extra oral scanner, Sirona x5, and the lowest precision was for scanner 3shape D700.

Statement of the Problem: Alveolar bone resorption associated with periodontal disease is a common finding and generally irreversible. It impairs mastication and causes esthetic problems for patients. Bisphosphonates are the most commonly used antiresorptive agents for bone diseases. Purpose: Considering the risk of bisphosphonate-related osteonecrosis of the jaw, this study aimed to assess the effect of 2% risedronate gel on calvarial bone defects in rabbits. Materials and Method: In this animal study, critical-size defects of 8mm were created in the calvaria of 20 New Zealand white rabbits. In group 1 (n=10), 2% risedronate gel was applied into the right side defect while the left side defect remained empty and served as control. In group 2 (n=10), placebo gel was applied into the right side defect, while the left side defect remained empty and served as control. Five rabbits in each group were sacrificed at 1month and the remaining five at 2 month, post-operatively, and tissue samples were collected for histomorphometric analysis. Histomorphometric assessments included bone fill, degree of inflammation, number of osteoblasts, number of osteoclasts, and foreign body reaction at the site. Data were statistically analysed using SPSS version 25 via the Dunn test and Kruskal-Wallis test. Results: No bone remodeling was noted in any group at 1 month. The risedronate group showed significantly higher bone fill than the other groups after 2 months (p= 0. 016). At 2 months, the number of osteoblasts was significantly higher in the risedronate group (p< 0. 05). The groups were not significantly different in terms of inflammation score at 1 (p= 0. 31) or 2 (p=0. 69) months. Foreign body reaction was not observed in any group at any time point. No osteoclast was detected in any group at any time point. Conclusion: Risedronate gel showed superior efficacy with regard to regeneration of rabbit calvarial bone defects compared to the placebo and control groups.

Statement of the Problem: The success of metal-ceramic restorations depends on the bond strength between porcelain and alloy. These restorations can be fabricated through different casting and computer-aided design/computer-aided manufacturing (CAD/CAM) techniques. Purpose: This study aimed to compare the bond strength of porcelain to milled sintered (Sintron) and casting (Co-Cr and Ni-Cr) base metal alloys. Materials and Method: In this in vitro experimental study, 63 rectangular bars (25×3×0. 5 mm) were fabricated of three base metal alloys: casting Ni-Cr, casting Co-Cr, and milled sintered Co-Cr alloy. Feldspathic porcelain (3×8 mm) was applied at the center of each bar with 1. 5 mm thickness. The specimens were thermally aged. Bond strength was evaluated through three-point flexural test. Failure mode was evaluated by optical and electron micro-scope. Data were analyzed with one-way ANOVA and Tukey's post hoc test (α =0. 05). Results: The mean flexural bond strength of porcelain to milled sintered Co-Cr alloy (24. 58± 5. 16 MPa) was significantly higher than that of casting Ni-Cr (21. 13± 6. 34 MPa) (p= 0. 03) and casting Co-Cr (20. 98± 4. 84 MPa) alloys (p= 0. 04). However, the two casting alloys were not significantly different in this regard (p= 0. 93). The failure mode in all specimens was of cohesive type. Conclusion: Bond strength of CAD/CAM milled sintered Co-Cr alloy was better than that of the conventional casting alloys and could serve as a suitable alternative to those alloys.

Statement of the Problem: Adolescents are at risk of obesity and caries due to various factors such as diet and poor health habits; these factors may affect their body mass index (BMI) and salivary components. Therefore, it is necessary to assess these factors and their relationship in this age group. Purpose: This study aimed to evaluate the association between decayed missing filled teeth index (DMFT), salivary alpha amylase (sAA) level and age-specific BMI in adolescent girls. Materials and Method: A cross-sectional study was conducted on 81 females aged 13-15 years in 3 groups of BMI percentiles; “ normal” , “ at risk for overweight” and “ overweight” (n=27). DMFT was calculated and unstimulated saliva samples were collected. The sAA level was measured with a spectrophotometer. Data were analyzed using Kolmogorov-Smir-nov test, Kruskal-Wallis and Spearman correlation tests using SPSS (version 23) at p< 0. 05. Results: The concentration of sAA and mean DMFT were estimated 1326. 56± 4. 73 U/L and 2. 77± 2. 36, respectively. There was no significant difference in sAA level and mean DMFT among BMI groups. A positive and significant correlation was found between sAA and DMFT in overweight group (r: 0. 46, p= 0. 014). Conclusion: Within the limitation of this study, higher levels of sAA may be considered as an indicator for dental caries in overweight adolescent girls.

Statement of the Problem: Oral squamous cell carcinoma (OSCC) is the most common malignancy of the oral cavity. Early diagnosis of OSCC by using biomarkers provides pre-ventive treatment approach to suppress the disease in early stages. CD44 as a cancer stem cell (CSC) marker may be cleaved by MT1-MMP and plays an important role in migration of cancer cells. TGF-B promotes formation of invasive cancer cells phenotype through epithelial mesenchymal transition (EMT) and induces MT1-MMP formation. Purpose: The aim of this study was to evaluate the expression of TGF-B and CD44 in leukoplakia (premalignant lesion), squamous cell carcinoma (SCC), and normal oral muco-sa to determine the role of these markers in the carcinogenesis process of the oral mucosa. Materials and Method: In this retrospective study, the expression of TGF-B and CD44 were evaluated in 55 paraffin-embedded specimens (10normal mucosa, 15 non-dysplastic leukoplakia, 15 dysplastic leukoplakia, and 15 OSCC) by immunohistochemistry. Statistical analyses were performed using Kruskal-Wallis, Mann-Whitney, and Spearman’ s rank cor-relation tests. Results: Evaluation of CD44 and TGF-B expression in the four studied groups showed statistical significant difference for each marker (p< 0. 001). Pairwise comparison of CD44 and TGF-B expression in all groups except normal mucosa and non-dysplastic leukoplakia demonstrated statistical significant difference. In addition, there was positive significant correlation between two markers (r= 0. 914, p< 0. 001). Diagnostic test’ s accuracy for identi-fication of OSCC and dysplastic leukoplakia from non-dysplastic leukoplakia and normal tissues and recognition of OSCC from dysplastic leukoplakia showed optimum sensitivity and specificity. Conclusion: Increased expression of CD44 as a cancer stem cell marker and TGF-B as an EMT marker from normal mucosa to non-dysplastic leukoplakia, dysplastic leukoplakia, and OSCC and also the significant correlation between these two markers indicated their role in carcinogenesis of oral mucosa.

Statement of the Problem: Adequate compressive strength is an important characteristic for an ideal liner. Purpose: This study aimed to assess the compressive strength of several commonly used liners. Materials and Method: This in vitro, experimental study evaluated 120 samples fabricated of Dycal, Calcimol LC, Vitrebond, Activa Bioactive, and TheraCal LC (n=24) liners accord-ing to the manufacturers’ instructions. The samples were fabricated using a cylindrical stain-less steel mold with 6± 0. 1 mm height and 4± 0. 1 mm internal diameter. Half of the samples in each group (n=12) underwent compressive strength test immediately after completion of their primary setting while the other half (n=12) underwent compressive strength test after 24 h. During this period, the samples were immersed in deionized water (grade 3) and incu-bated at 37± 1° C and 100% humidity for 24 h. The compressive strength was measured us-ing a universal testing machine. Data were analyzed using two-way ANOVA followed by Tukey’ s post-hoc test. Results: The compressive strength of the five liners was significantly different (p< 0. 05). Calcimol LC showed maximum compressive strength both immediately after setting and after 24 h. The compressive strength at 24 h was significantly higher than the primary com-pressive strength in all groups (p< 0. 05). Conclusion: Within the limitations of this study, it seems that Calcimol LC, Activa Bioac-tive Liner, and TheraCal LC have adequate compressive strength and can be used alone to provide adequate support for the restorative materials.

Statement of the Problem: Tooth color changes followed by treatment with bioceramic materials are always a matter of concern. Purpose: The aim of the present in vitro study was to compare tooth discoloration that oc-curs in human teeth filled with ProRoot WMTA (DENTSPLY Tulsa Dental Specialties, Tulsa, OK) and those filled with Nano Fast Cement (NFC) over the course of 3 months. Materials and Method: In this experimental study, Thirty human intact premolars were obtained. The roots of all teeth were removed by a horizontal cut about 2 mm below the cementoenamel junction. The pulp tissues were removed using a barbed broach (Mani, Tok-yo, Japan). The teeth were randomly divided to 3 groups (n= 10) including the control (no material), ProRoot WMTA and NFC. The experimental materials were condensed into the crowns and the teeth ends were sealed with light-cure glass ionomer cement (GC Corpora-tion, Tokyo, Japan). The color was assessed at TBL (baseline; after preparation of the cavities but before placement of the materials), TPO (immediately after placement of the filling mate-rial and provisional restoration), T4 (after 4weeks of storage), and T12 (after 12weeks) of storage. Results: The discoloration was evident in all teeth, immediately (TPO) after applying MTA and NFC. The highest Δ Ε was noted in WMTA at 12 weeks, followed by NFC; however, the-re was no significant difference between the discolorations induced by these two materials. Conclusion: Similar levels of clinically observable tooth discoloration were detected by using either WMTA or NFC.

Statement of the Problem: Ultra-soft bristles are recommended for individuals with gingival recession, dentinal hypersensitivity, and patients who have undergone periodontal surgeries. However, comparative effectiveness of ultra-soft toothbrushes on dental plaque and bleeding indices has not extensively been studied, and a consensus has yet to be reached on their effi-cacy. Purpose: The aim of this study was to investigate the effect of ultra-soft toothbrushes with different commercial brands on plaque and bleeding indices. Materials and Method: In this crossover randomized clinical trial, 30 participants were se-lected using convenience sampling method. The subjects were randomly divided into three groups (n=10). In the first session, the bleeding index was recorded. Then each subject was given a toothbrush (Oral B, GUM, or Fuchs), asked to brush at least twice a day using the Bass technique, then avoid brushing for 24 hours after a week and refer for recording the indices. During the second session, bleeding on probing was recorded before brushing, and plaque indices were recorded before and after brushing. Plaque indices before brushing were considered the baseline plaque indices. After one week of washout, each subject used the next toothbrush in terms of the group involved. Turesky plaque index, O’ Leary plaque index, and bleeding index were evaluated. The distribution of data was normal. Therefore, ANOVA, t-test, and post hoc tests were used for the analysis of data. Results: The bleeding and plaque indices decreased significantly compared to the baseline with the use of all the three ultra-soft toothbrushes evaluated (p< 0. 05), with no significant differences between the three brands (p> 0. 05) except for the superiority of Fuchs toothbrush in decreasing the Turesky plaque index. Conclusion: Ultra-soft toothbrushes can reduce plaque index compared to the baseline, but they do not decrease the plaque index up to the optimal level, which might affect their pre-scription.

Statement of the Problem: Zataria multiflora (ZM) is a thyme-like plant that belongs to the Lamiaceae family. It is native to the center and south of Iran, Pakistan, and Afghanistan. Evi-dence shows that ZM contains thymol and carvacrol and is therefore, effective for the treatment of many conditions especially fungal infections. Oral candidiasis is the most common opportun-istic infection of the oral mucosa that plays a role in the development of denture stomatitis. Purpose: This study aimed to compare the antifungal efficacy of ZM and nystatin suspension for the treatment of denture stomatitis. Materials and Method: This single-blind clinical trial evaluated 28 patients (> 18 years old) suffering from type II or III denture stomatitis. Patients were divided into two groups. The con-trol group used nystatin suspension while the case group used ZM drop. The number of Can-dida albicans (C. albicans) colony-forming units (CFUs) and erythema of the palate were eval-uated at baseline and at 14 days after treatment. Data were analyzed using SPSS version 11 via Student’ s t test and repeated measure ANOVA. Results: The results showed similar efficacy of nystatin and ZM in the reduction of C. albicans CFUs compared to the baseline value (p= 0. 593). Both medications significantly decreased the colony count (p< 0. 001). Nystatin and ZM had similar efficacy for the reduction of erythema as well (p= 0. 256) and both caused a significant reduction in erythema of the palate (p<0. 001). Conclusion: ZM drop was as effective as the nystatin drop in the resolution of erythema of the palate and reduction of C. albicans colony count.

The treatment of gingival recession is a frequent demand due to aesthetic concern, root caries, and /or root hypersensitivity. The purpose of this case study was to evaluate the success and predictability of coronally advanced flap (CAF) in combination with periph-eral blood mesenchymal stem cells (PBMSCs) and platelet rich fibrin matrix(PRFM) for the management of Miller's Class II gingival recession. CAF followed by placement of PBMSCs and PRFM was performed on a male patient, aged 25 years having Miller’ s Class II gingival recession of 5-6 mm on the upper left canine, premolars and molars. The patient was followed up for 3 months. Root coverage of 60. 0% and clinical attach-ment gain of 3 mm were evident following 3 months of follow-up. This novel technique showed an effective way to increase the width of attached gingiva and treat gingival recession.

Ameloblastoma is one of the most common benign epithelial odontogenic tumors of jaws. We report a case of long-standing slow-growing giant ameloblastoma involving almost all of mandibular bone. The solid multicystic lesion was excised, and the histopathological examination showed the follicular type of ameloblastoma. Furthermore, the defect was reconstructed with microvascular osteocutaneous free fibular graft.