Journal of Mashhad Dental School
Year:2020 | Volume:44 | Issue:3|Papers Count:11

Introduction: The present study aimed to evaluate the effect of home bleaching on the color enhancement of white spot lesions (WSLs) after orthodontic treatment. Materials & Methods: This interventional semi-experimental study was conducted on 10 patients with inactive WSLs after orthodontic treatment who referred to Mashhad Dental School between May 2016 and May 2017. The tooth color was measured by a spectrophotometer at baseline and the color determination was performed in the area of healthy enamel (F1) and the adjacent demineralized enamel (F2). Afterward, the teeth underwent home bleaching for 2 weeks. The color measurements were performed one day and one week after the treatment under the same condition. The color change of the healthy and demineralized groups at each time point was compared to each other; moreover, the color differences between healthy and demineralized areas were compared at the three different time points. The collected data were analyzed using an independent samples t-test and repeated measures ANOVA. Furthermore, a p-value of less than 0. 05 was considered statistically significant. Results: The degree of color change before the treatment and one day after the treatment was greater in healthy enamel (9. 28± 3. 29), compared to demineralized enamel (6. 98± 2. 92). However, the results of the independent samples t-test revealed no significant difference between healthy and demineralized enamel regarding the color change at various time points (P>0. 05). There was no significant difference between the color change of healthy (F1) and demineralized (F2) enamels at the three evaluated time points (P>0. 05). Conclusion: Based on the results, under the conditions of this study, home bleaching was not an effective method for the color improvement of enamel WSLs after orthodontic treatment.

Introduction: Recurrent aphthous ulcers (RAU) are one of the most common lesions of the oral mucosa affecting at least 10-20% of the general population. Various factors have been reported as predisposing or related factors to RAU. However, the etiopathogenesis of the condition is still unknown, and no definitive medication is available in this regard. This study aimed to compare the levels of the salivary folate, ferritin, and vitamin B12 in patients with RAU versus healthy controls. Materials and Methods: This cross-sectional study compared 30 patients in the case group and 30 healthy individuals in the control group. Moreover, in selecting the case and control groups, it was tried to match them in terms of age, gender, and to some extent socio-economic status. Folate, ferritin, and vitamin B12 levels were evaluated using specific kits and enzymelinked immunosorbent assay techniques. The data were analyzed in SPSS software (version17) using descriptive statistics (Mean± SD) Mann Whitney U test, and independent t-tests. A P-value less than 0. 05 was considered statistically significant. Results: The results of the Mann-Whitney U test showed that the salivary level of vitamin B12, folate, and ferritin was significantly lower in the patients with RAU, compared to the healthy group (P<0. 05). Conclusion: The results of this study show that low salivary levels of vitamin B12, folate, and ferritin can be effective in increasing the risk of recurrent oral aphthous ulcers.

Introduction: Nanoparticles have been recently used in dentistry to improve the resin composite properties. In addition to its antimicrobial effect, copper oxide nanoparticles improve some of the resin composite properties. The durability of composite restorations is another matter. In this study, the effect of mechanical load cycling on the microleakage of the mixture of copper oxide nanoparticle and flowable composite was investigated. Materials and Methods: In this study, 96 healthy premolar teeth were randomly divided into eight groups. Copper oxide nanoparticles with weight concentrations of 0. 1% and 0. 3% were added to the Z350 flowable composite, and occlusal pit and fissures were sealed. Mechanical loading cycling was performed with a force of 70 Newtons and repetition rates of 0, 50, 000, 100, 000, and 200, 000 loads. The teeth were cut after staining with methylene blue, and the dye penetration was checked by a stereomicroscope and qualitatively scored. The data were analyzed using the Kruskal-Wallis and Mann-Whitney U tests. Results: In both concentrations of nanoparticles, with an increasing number of load-cycling cycles, microleakage significantly increased. In the 0. 1% group, the two-way comparisons of groups between 1 to 4, 1 to 3, and 2 to 4 and in the 0. 3% groups between 5 to 7, 5 to 8, and 6 to 8 were significantly different. In the comparison of different concentrations to similar load cycling rates, there was no significant difference in the amount of microleakage. Conclusion: Mechanical loading cycling increased the microleakage rate in both two concentrations when the frequency of load was higher than 50, 000 loads. There was no difference in the microleakage rates of groups with different concentrations and similar load cycling. By increasing the concentration from 0. 1% to 0. 3%, microleakage did not increase significantly.

Introduction: According to the prevalence of dental trauma, the importance of its rapid treatment, and the need for planning to determine the appropriate agent for its management and referral, the purpose of this study was to evaluate the management of dental trauma and its referral pattern among general dentists in Mashhad, Iran, in 2016. Materials & Methods: This cross-sectional study was performed on 120 general dentists in Mashhad. To collect information, a valid and reliable researcher-made questionnaire was used. After obtaining consent, the questionnaire was provided to the dentist. Following the collection of the information, the results were reported descriptively in the form of tables and charts. Results: Most cases treated during the year by general dentists were crown fractures with or without pulpal involvement and root fractures. However, the avulsion or displacement of the tooth was less commonly treated by general dentists. Among the dental traumas, the most frequent cause of referral was root fracture. Dentists generally referred most dental traumas to endodontists. Treatment difficulty caused by the young age of the patients and the time required for the procedure was the main cause of referring patients to other specialists. Conclusion: Except for crown and root fractures with or without pulp involvement, other trauma cases are referred to specialists because of the difficulty of treatment due to the low age of the majority of patients with trauma and the time required for the implementation of the treatment.

Introduction: The present study aimed to evaluate the incidence of obstructive sleep apnea (OSA) after monomax mandibular setback surgery using a combination of Berlin, STOP-BANG, and Epworth Sleep Scale questionnaires. Materials and Methods: This double-blind quasi-experimental before-after study was carried out on a total of healthy patients with class III deformity and eligible for orthognathic mandibular setback surgery. Age, gender, body mass index, neck circumference, and amount of mandibular setback were recorded in the study checklist. The incidence of OSA was assessed for all the patients 1 week before the operation and 1 and 6 months following the surgery using the aforementioned questionnaires under the supervision of a pulmonary specialist. Descriptive and analytical statistics were analyzed by SPSS software (version 17). A p-value of less than 0. 05 was considered statistically significant. Results: A total of 30 patients, including 15 males and 15 females, with a mean age of 25. 77± 4. 76 years participated in this study. The mean scores of OSA questionnaires increased a month after mandibular setback surgery using bilateral sagittal split osteotomy, compared to those reported before the operation; however, 6 months following the surgery, the results numerically reduced closer to the patient’ s normal condition. The amount of mandibular setback was directly correlated with the incidence of OSA in patients 1 and 6 months after the surgery based on all the three questionnaires; nevertheless, it was significantly and directly correlated with STOP-BANG questionnaire (P<0. 05). Conclusion: The obtained results of the present study indicated that there was no evidence of severe OSA 6 months following mandibular setback surgery. Additionally, obese patients and those submitted to a large amount of mandibular setback presented a higher chance of developing OSA. The findings of the present study showed that the results of the numerical changes of the sleep questionnaires and incidence of OSA 1 and 6 months after the surgery and before the operation were significantly lower in patients with mandibular setback up to 5 mm, compared to those with equal or greater than 5 mm.

Introduction: Chlorhexidine is the gold standard of dental plaque prevention. This clinical study assessed the use of a herbal mouthwash (containing thyme, Mentha piperita, and Tanacetum balsamita) to eliminate the negative effects of chlorhexidine mouthwash on crown lengthening post-operative healing. Materials and Methods: Patients were randomly assigned to four groups (n=15) according to the use of different mouthwashes: chlorhexidine, herbal, herbal-chlorhexidine, and normal saline. Modified gingival index (MGI) and plaque index (PI) were measured on the day of surgery. After two weeks, indices of mouthwash flavor, mouthwash preference, parotid gland swelling, tongue discoloration, staining index (SI), plaque index (PI), and modified gingival index (MGI) were measured. Data were analyzed using non-parametric Kruskal-Wallis and Mann-Whitney tests at 5% level. Result: As evidenced by the obtained results, herbal mouthwash significantly improved gingival inflammation and plaque indices (P= 0. 008). Nevertheless, it demonstrated no significant difference with chlorhexidine mouthwash (MGI: 0. 656 and PI: P=0. 080). Furthermore, none of the adverse effects similar to chlorhexidine mouthwash was observed in the patients who used herbal mouthwash. Conclusion: In comparison to chlorhexidine, herbal mouthwash has fewer side effects on parotid swelling indices, discoloration of the tongue and teeth, and taste improvement. It has also positive effects on the improvement of GI and PI indices similar to the chlorhexidine group; therefore, it can be alternatively used instead of chlorhexidine.

Introduction: This study is performed to investigate the distribution of temperature and thermal stresses in ceramic and gold onlay restorations using 3D finite element analysis. Materials and Methods: A three-dimensional model of mandibular first molar is created using 3D scanning method. The simulated model is consisted of enamel, dentin, resin cement and onlay restoration (made of type 2 gold alloy or lithium disilicate ceramic). The crown of the tooth is subjected to temperature changes (4° C or 60° C) for 2 seconds and the temperature distribution and also resultant stresses in the tooth are analyzed. Results: The pattern of temperature and stress distribution is the same in both restorations but heat transfer from the surface to the depth of the tooth in gold restoration is more than ceramic restoration. The maximum stresses in all parts (enamel, dentin, cement and onlay), in ceramic restoration are higher than gold restoration. In both restorations, the stress at the gingival contact surface of the cavity is higher than the other parts of restoration. The maximum stress is detected in the enamel. Moreover, thermal stress in the cervical area of dentin is higher than other parts of dentin. Conclusion: According to the findings of this research, ceramic onlay (which shows better heat isolation) is proposed for deep restorations while due to lower thermal stress in gold onlay, it is more efficient for restorations with shallow depth cavities.

Introduction: Gingival biotype is defined as the faciolingual thickness of keratinized gingiva which plays an important role in periodontal health. Moreover, it affects the periodontal response to physical trauma, the result of periodontal and implant surgery, and restorative and orthodontic treatment. In this regard, the present study aimed to investigate the relationship of gingival biotype with the width of the keratinized gingiva, depth of probe, and height of papilla in the patients who referred to the Dental School at Golestan University of Medical Sciences. Materials and Methods: This cross-sectional study was conducted on 130 patients who referred to the Periodontal Department of the Dental School. For the purposes of the study, their clinical parameters were assessed which included the width of keratinized gingiva, depth of the probe, and height of papilla. Finally, the relationship between the gingival biotype and clinical parameters was investigated. It should be noted that a P-value of 0. 05 was considered statistically significant. Results: Out of 130 participants, 70 and 60 patients had thin and thick gingival biotypes, respectively. Based on the results, the mean values of the keratinized gingiva width, depth of the probe, and height of papilla were 6. 23± 1. 44, 1. 12± 0. 44, and 3. 12± 0. 65 mm, respectively. Moreover, the mean values of keratinized gingiva width, depth of the probe, and height of papilla were 5. 27± 0. 91, 1. 07± 0. 37, and 3. 4± 0. 66 mm in thin gingival biotype, respectively, and 7. 35± 1. 10, 1. 19± 0. 49, and 2. 7± 0. 46 in the thick gingival biotype, respectively. Conclusion: It can be concluded that the mean value of the keratinized gingiva width of the thin biotype was less than that of thick biotype. However, the height of papilla was more in the thin biotype, compared to the thick biotype. Besides, no significant difference was observed between the depth of probe of these two biotypes.

Introduction: Recurrent aphthous stomatitis (RAS) is a common oral disease, which presents as painful and recurrent single or multiple ulcers in the oral mucosa. This condition is an idiopathic disease and has no definitive cure; accordingly, it is very important to find a drug to control the disease. Since green tea is a rich source of antioxidant and has an antiinflammatory effect, this study was aimed to determine the effect of a mucoadhesive paste, containing green tea extract, on RAS. Materials and Methods: This double-blind, placebo-controlled clinical trial was conducted on 52 patients with RAS. The study population was randomly divided into two groups of intervention (using a mucoadhesive paste containing green tea extract) and placebo (using a mucoadhesive paste without drug). They used mucoadhesive paste three times a day for 10 days. Pain severity was measured based on the visual analog scale at the beginning of the study (day zero) and 1, 6, and 10 days post-intervention. In addition, the lesion size was measured using a probe. The data were analyzed in SPSS software (version 21) using two-way repeated measures ANOVA. Results: According to the results, pain and recovery time were significantly lower in the intervention group than in the control group (P<0. 05). However, the ulcer size did not show any statistically significant difference between the two groups over time (P>0. 05). Conclusion: As the findings indicated, the use of mucoadhesive paste, containing green tea extract, can reduce the pain severity and healing time of RAS. However, it was not effective in reducing the size of lesions.

Introduction: This study aimed to evaluate the effect of various disinfectants on flexural strength and hardness of heat-cured acrylic dentures. Materials and Methods: A total of 60 acrylic samples were prepared with dimensions of 3×10×65 milimeters (30 acrylic Acropars and 30 acrylic Ivoclar). The acrylic samples were immersed into distilled water (control group), as well as sodium hypochlorite 1% and ozonated water (case groups) for 120 minutes. Subsequently, half of the samples were subjected to the flexural strength, and the other half were subjected to the hardness tests. The data were analyzed using 2-way ANOVA and Tukey’ s test to compare the results. Results: According to the results, there were no significant differences between the samples immersed in the ozonated water and sodium hypochlorite regarding the flexural strength and hardness of acrylic. Conclusion: It seems that flexural strength and hardness of acrylic after immersion in ozonated water and sodium hypochlorite is not affected during the short-term use. Therefore, it is suggested to use ozonated water to disinfect the patient's teeth.

Introduction: Dental services are high-risk centers to spread the new coronavirus disease 2019 (COVID-19) due to the type of treatment and closeness of the staff to patients. For this reason, several guidelines have been developed by international organizations regarding the necessity for complying with health standards in these centers. The present study aimed to review the guidelines and studies conducted on the prevention and control of COVID-19 in dental settings. Materials and Methods: The current study was carried out to investigate COVID-19 prevention and control strategies in dental settings. Several databases, including Google Scholar, PubMed, and Scopus, since 2019 to 2020 in addition to the guidelines of the Centers for Disease Control and Prevention, Occupational Safety and Health Administration, National Health Service, and American Dental Association were reviewed through subject searching and used in the present study. Results: Studies have shown that the staff of dental centers similar to other health care workers is at high risk of getting COVID-19. The majority of published guidelines have emphasized the elimination of nonemergency measures and provision of remote counseling services to patients. In case of the need for an emergency visit, it is necessary to implement preventive measures, especially hand hygiene and protection measures, to prevent the spread of the virus through aerosol transmission. Conclusion: Due to the increasing prevalence of COVID-19, it is necessary to provide all dental staff with the essential information and training on prevention and control strategies based on scientific guidelines and standards. This issue can play an important role in reducing the number of patients and preventing the spread of the virus in the community.