Effect of the Nd:YAG laser on the micro-tensile bond strength of composite resin to dentin with hypersensitivity using different universal adhesives.

Background: This study aimed to evaluate the effect of the Nd: YAG laser on the tensile bond strength of composite resin to dentin with hypersensitivity using different universal bonding systems. Material and Methods: After cutting the crown of 252 molars, buccal cervical enamel was removed at a thickness of approximately 2 mm, and 252 smooth dentin surfaces were exposed. Then they were etched with 0.5 M ethylenediaminetetraacetic acid (pH = 7.4) to stimulate hypersensitivity. The specimens were then randomly divided into 12 groups (n= 21) according to the surface treatments performed. After etching and bonding according to the manufacturer's recommendations in each group, the entire dentin surface was restored with Valux Plus composite resin. The samples were thermocycled and a universal test machine was used to measure the microtensile bond strength. The failure mode for each sample was observed under a stereomicroscope. For data analysis, the Bonferroni test, the independent t-test and the three-way anova test were used. Results: The average microtensile bond strength in non-laser samples was higher than the average in laser samples (P<0.001). In comparison with the bonding agent type in both cases with and without laser, the highest average microtensile bond strength was related to ALL-BOND (P<0.001), meanwhile the lowest average tensile strength in samples without laser was related to G-Premio universal adhesive (P<0.001), and the lowest average microtensile strength in samples with laser belonged to Prime and Bond Elect group (P<0.001). Conclusions: Nd: YAG laser irradiation of the dentin surface before applying the adhesive significantly decreased the microtensile bond strength of the composite resin to the dentin surface. Key words:Nd:YAG laser, Bond strength, Dentin, hypersensitivity, Universal adhesives.

The Effect of Direct Observation of Procedural Skills on Learning and Satisfaction of Students in Community Dentistry Course.

Introduction: Direct Observation of Practical Skills (DOPS) tests is a valuable method for clinical assessment. This study aimed to implement the DOPS test to assess the procedural skills of community dentistry courses and its effects on mastery learning and satisfaction of professors and students at Tabriz faculty of dentistry in 2021-2022. Methods: In a quasi-experimental study, 60 dentistry students of a class were assigned into two study (n=30) and control (n=30) groups by Permuted block randomization. In the case group, the skills were related to Fluoride therapy, fissure sealant therapy, and health education evaluated by DOPS. In the control group, these skills were evaluated by traditional evaluation methods. Each test was repeated three times. Finally, the satisfaction of students in the case group was assessed by a questionnaire. The chi-square test was used to compare qualitative variables. Repeated measure ANOVA test was used to compare the mean scores in three stages and two groups. P value less than 0.05 was considered significant. Data were analyzed using SPSS 16 software. Results: A significant difference in the mean score of Fluoride therapy, pit and fissure sealant therapy, and health education was seen between the case and control groups (P<0.001). Also a significant increase in these skills in the third stage of assessment in the case group was observed (P<0.001). The professors and students' satisfaction was considerably high on the DOPS test. Conclusion: The DOPS method had more impact on Fluoride therapy, pit and fissure sealant therapy, and health education's learning process in dentistry students than the conventional evaluation. The professors and students' satisfaction level was high regarding DOPS. The advantages of the DOPS method are student-centeredness, objectivity, and appropriate feedback.

Ergonomic Evaluation of Senior Undergraduate Students and Effect of Instruction Regarding Ergonomic Principles on It.

Background and objective: Musculoskeletal disorders in dentists due to abnormal postures may result in economic and health problems. To prevent these problems, the working posture of dental students should be assessed and corrected in dental procedures. This study was undertaken to assess the effect of instruction regarding ergonomic principles on them by using the Rapid Entire Body Assessment (REBA) method. Material and methods: The posture of 117 students was assessed by REBA before and after of the "Ergonomic principles in dentistry" course. The sample size was selected based on previous studies on this issue. REBA scores were assessed by SPSS software using Friedman-test. Results: The statistical analysis of data gathered from this study showed that the ergonomic structure had a significant effect only in the group of right-handed females (P=0.046). In other groups, no significant change was observed (P>0.05). There was no significant change before and after instruction in REBA classifications (negligible, low risk, medium risk, high risk, very high risk) (P>0.05). There was no relation between the types of positions and REBA score (P>0.05). Conclusion: Ergonomic instruction can significantly decrease musculoskeletal disorders in female dentists who use their right-hand to work. In the other groups, however, the absolute amount of danger became better, but this change was not statistically significant.

Comparison of General Dentistry Curriculum in Iran with Eight of the World's Top Dental Faculties.

Background and objectives:A curriculum is a general and immense outline of an educational activity. A curriculum defines teaching content, student and curriculum assessment methods, and ultimately defines the framework for each activity in the curriculum. Given the importance of training in medicine and dentistry, the purpose of this study was to compare Iran's general dentistry curriculum with eight of the world's top dental faculties. Materials and methods:In descriptive-comparative research, the important components and parameters of the curriculum of the PhD in dentistry at several universities in the world were studied and compared with Iranian curriculum. The present study was conducted in two stages: The first phase included finding the best dental faculties in the world; the second phase was to identify and examine the various components of the curriculum of the PhD in Public Dentistry in Iran and the 8th highest dental faculties in the world and compare them according to Loudvigsson indicators. The results of the study were reported using descriptive statistics (frequency and percentage). Results:All of the evaluated indicators were in the Iranian curriculum. The study of the eight top universities in the world showed that the indicators worth paying attention to, including critical thinking and scientific approach in the program, student-centered curriculum, horizontal and vertical integration, systematic education, education based on community health care system, community-based education and ethical principles, existed in all curricula of the studied colleges. The presence of a selective framework in a curriculum and early clinical exposure was only available in the educational curriculum of four universities: Toronto, UNC, Minnesota and UCLA. The focus on small group work was defined as the prevailing educational method in three Herman Ostrow, Minnesota and UCSF universities. The problem-solving learning index was only presented at two universities in Osaka and NYU. Conclusion:The highest rates of Loudvigsson indicators in general dentistry curriculums of eight universities in the world were 90% and at least 72.7%, while the above indicators were 100% in the dentistry curriculum of Iran. According to the indicators of Loudvigsson, Iran's dental training program is ranked high in content.

Comparing Vitamin D Serum Levels in Patients with Oral Lichen Planus and Healthy Subjects.

STATEMENT OF THE PROBLEM: Lichen planus disease is a chronic inflammatory lesion without a known etiology. Recent studies have indicated the role of vitamin D on immune system and proposed its anti-inflammatory effects. PURPOSE: This study aimed to compare vitamin D serum levels in patients with oral lichen planus and healthy subjects. MATERIALS AND METHOD: In this case‒control study, 18 patients suffering from oral lichen planus referred to the Department of Oral Medicine, Tabriz Faculty of Dentistry were chosen as the case group and 18 healthy people were chosen as the control group. A 5-mL blood sample was taken from all subjects and the subjects' vitamin D serum levels were assessed with a vitamin D total (25-hydroxy vitamin D) kit by employing the electrochemiluminescence technique. The results were analyzed and compared by using SPSS17 statistic software. p< 0.05 was considered statistically significant. RESULTS: The mean vitamin D level in serum of patients with oral lichen planus was 30.7±20.38ng/ml and in healthy subjects was 36.45± 15.33ng/ml, the difference was not statistically significant (p= 0.346). CONCLUSION: The difference between the level of vitamin D in the serum of patients suffering from oral lichen planus and healthy individuals was not significant.

Effect of Consecutive Removal and Placement of Abutments during Prosthetic Procedures on an Increase in Proinflammatory Cytokine Levels around Dental Implants

Objective: To evaluate the effect of repeated removal and placement of abutments during prosthetic stages on increasing proinflammatory cytokine levels around dental implants. Material and Methods: All the patients with dental implants, referring to the prosthodontics private office during a 3-month period, were examined in relation to the health of the implants and included in the present study based on inclusion criteria; the patients had a multi-unit abutment on one side of the jaw and a conventional healing abutment on the implant on the other side of the jaw. Samples of gingival crevicular fluid were taken from all the eligible subjects for immunological analyses. The samples were taken from the sulcus around each implant in each subject. The samples were sent to the immunology laboratory for determination of IL-6 and IL-1ß proinflammatory cytokines with the use of an ELISA kit. Data were analyzed with SPSS 16 and Descriptive statistics and T-test was used. Statistical significance was set at p<0.05. Results: The results showed that the mean concentrations of IL-1ß and IL-6 in the group with multi-unit abutment were less than those in the conventional abutment group. In addition, comparison of the means of IL-6 and IL-1ß concentrations showed that in both groups the concentration of IL-6 was higher than that of IL-1ß. Conclusion: The use of multi-unit abutments resulted in less inflammation compared to the use of conventional two-segment abutments, which require repeated removal and placement during the prosthetic stage.

Effect of Home Bleaching on the Color Matching of Composite Resin Restorations

Objective: To investigate the effect of home bleaching on color matching between the dental restoration and the adjacent tooth structure after the staining process. Material and Methods: Ten intact maxillary central incisors were used. After preparation (semimesial restoration of the specimens), the specimens were immersed in a colored solution for 14 days and then were washed and the bleaching process was there after performed. A spectrophotometer apparatus was used to determine the color of the specimens in the part of the tooth filled with restorative material three times, including before the staining process, fourteen days after the staining process and immediately after the bleaching process. Paired t-test was employed to compare the color of the intact tooth and the dental restoration before and after the staining and bleaching processes. The level of significance was set at 5%. Results: Pre-bleaching E color of the teeth was 68.1, which increased to 78.8% after bleaching, and this increase was also statistically significant (p<0.001). Pre and Post-bleaching E color of composite restorations was 65% and 77.6%, respectively. This increase was also statistically significant (p<0.001). Postbleaching E color of the tooth and composite material was 78.8% and 77.6%, respectively. This difference was not statistically significant (p=0.342). Conclusion: The staining and bleaching processes had a significant effect on the discoloration of the dental restoration and the tooth; however, the application of bleaching on the teeth and composite improved the tooth composite color-match.

Evaluation of Periodontal Status of Adjacent Teeth to Posterior Single- Tooth Implant during a One-Year Period after Restoration: A Cross- Sectional Study

Objective: To evaluate the periodontal status of teeth adjacent to the posterior single tooth implant during one year after restoration. Material and Methods: In this crosssectional study, 36 patients, which were systematically and had received the implant(s) of single posterior teeth over the past year were selected. The teeth adjacent to singleposterior tooth implants were evaluated regarding bleeding on probing, mobility, gingivitis and periodontal pockets during the follow up period of 3, 6 and 9 months under the supervision of two specialists. To investigate the relationship between periodontal statuses, the Chi-square test was used, and the Kruskal-Wallis test was used to assess statistical significance of periodontal indexes in the period under assessment. The p-value of less than 0.05 was considered significant. Results: There was no significant relationship between the variable of bleeding on probing, mobility, gingivitis and periodontal pocket in the studied distal and mesial teeth. Out of studied patients, after 9 months, only 11.1% had one of the periodontal problems, as a result, 88.9% of crowns replacement of single-posterior tooth does not make any periodontal damages to adjacent teeth. Conclusion: Crowns replacement of implant does not have any destructive impact on periodontal condition of adjacent teeth.

Prevalence of Dental Malocclusions in Patients admitted to the Department of Orthodontics, School of Dentistry, Tabriz, in 2016.

AIM: This study is aimed at investigating the prevalence of disorders among patients referred to Tabriz Dental School in 2016. MATERIALS AND METHODS: This research was conducted in a cross-section method and taken from all patients admitted during this period. Classification of dental occlusion in patients was based on Angle's definition, skeletal classification was based on Steiner's analysis, and overjet and overbite values and other patient-related information were imported from the records in the extractive sector and in specific forms. After reviewing the data, the forms of individual patients were inputted into the computer and analyzed. RESULTS: In terms of dental condition, the prevalence of malocclusion CL.I, malocclusion CL.II, and malocclusion CL.III was respectively, 50, 36.8, and 13.2%. In terms of overjet condition, 13.9% of patients had normal overjet, 67.1% had increased overjet, 8.9% had reduced overjet, and 10.1% had reversed overjet. In terms of overbite, 17.7% of patients had normal overbite, 53.2% had increased overbite, 8.9% had decreased overbite, 15.2% had open bite, and 5.1% had deep bite. Skeletally, 24.1% of patients had skeletal abnormalities CL.I, 62% had skeletal deformities CL.II, and 13.9% had skeletal CL.III. CONCLUSION: The most common dental malocclusion among patients was related to CL.I and the most common skeletal malocclusion was related to CL.II, and malocclusions of CL.III had the least prevalence both dentally and skeletally. There was no significant relationship between dental and skeletal malocclusions and also between different malocclusions and gender. CLINICAL SIGNIFICANCE: Knowledge of the prevalence of different types of dental and jaw anomalies is considered as the first step in the evaluation and treatment of these disorders. It is worth mentioning that the results of the study can be used in treatment planning required in the province and even in the country.