School of Dentistry

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Tabriz Faculty of Dentistry is located in Tabriz, capital city of East Azarbayjan Province and is the only dental schoolwestern Iran. Tabriz Dental School was founded in 1986. The first students entered in 1987, graduating in 1993. In 1997 the school moved into a new and modern building, covering 22,000 square meters. The school expanded its educational programs in 2001 by offering its postgraduate specialty courses in three fields and at present it offers seven postgraduate specialty courses. Prospects for the Future We are determined, by asking for assistance from the Almighty, to promote the school's academic excellence, raise the standards of oral health in the community and join the circle of highly qualified dental schools in the country through optimizing instruction standards and innovative research programs. Mission Tabriz Faculty of Dentistry as the only dental school in the north-western Iran and as a part of a major university has combined and enjoyed the endeavors of competent and qualified academic staff with appropriate facilities and has committed itself to: Training highly qualified general practitioners and specialists; Updating the knowledge and skill of the graduates working in the north-western Iran;

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Evaluation of Mechanical Properties Associated with the Stability of Orthodontic Mini-implants by Finite Element Analysis
(Tabriz University of Medical Sciences, School of dentistry, 2019) Abdollahzadeh Baghaei, Tannaz; Pouyafar, vahid; Orthodontics; Sadr Haghighi, amirhouman
Background: The design of an orthodontic mini-implant is a significant factor in determining its primary stability and therefore its clinical success. The purpose of this study was to measure the relative influence of mini-implant design factors including diameter, length, degree and length of taper both in the threaded and non-threaded area, pitch and thread depth/diameter on the primary stability. Methods: Thirty two 3-dimensional assemblies of mini-implant models with their surrounding bone were generated using finite element analysis software. The maximum displacement of each mini-implant model was measured as they were loaded with a 2 N horizontal force. Employing Taguchi’s design of experiments as a statistical method, the contribution of each design factor to primary stability was calculated. As the effect of the upper diameter and length was abundant, to better detect the impact of the remaining design factors, another set of twenty five models with a fixed amount of length and diameter was generated and evaluated. Analysis of variance was conducted to evaluate the statistical significance of the impact of each factor in the both set of experiments (α=0.05). Results: In the first set of experiments the upper diameter and length showed a great impact on the primary stability (53% and 45%, respectively, p=0.000). The effect of the remaining factors was not statistically significant. According to the second set of experiments, threaded taper angle (64%, p=0.005), non-threaded taper angle (16%, p=0.011), Non-threaded taper length (7%, p=0.016), pitch (6%, p=0.017), thread depth/upper diameter (2%, p=0.026) and threaded taper length (2%, p=0.027) significantly affected the primary stability (in a descending order). Conclusion: Upper diameter and length were the most important factors affecting the primary stability, respectively. Excluding the upper diameter and length; threaded taper angle, non-threaded taper angle and non-threaded taper length were the main factors influencing the primary stability, respectively. Tapering is suggested only if the upper diameter increases as well. Addition of a non-threaded tapered part to the mini-implant also contributes to the primary stability.
Investigating the effect of different composite restorations surface preparation methods on the shear bond strength of orthodontic brackets.
(Tabriz University of Medical Sciences, School of Dentistry, 2025) Rezaei Torkamani, Ali; Rezaei, Yashar; Orthodontics; Ravadgar, Mehdi; Abdollahzadeh Baghaei, Tannaz
Background: Bond failure at the interface of bracket and composite restoration occurs in cases of improper surface preparation. Aim: The aim of this study is Investigating the effect of different composite restorations surface preparation methods on the shear bond strength of orthodontic brackets. Materials and methods: 180 composite cubes were mounted in acrylic blocks. The samples were first stored in normal saline at 37°C for 14 days. Then the samples were randomly divided into 12 groups of 15. Diamond burs were used for mechanical preparation of groups 1, 2, 3, and 4; sandblasting was used for groups 5, 6, 7, and 8; and groups 9, 10, 11, and 12 were left without mechanical preparation. For bracket bonding to the samples, GC Ortho Connect composite was used in half of the groups (groups 1, 2, 5, 6, 9, and 10) and Transbond XT 3M composite was used in the other half (groups 3, 4, 7, 8, 11, and 12). G-Premio bonding was used in half of the groups that used GC Ortho Connect composite (groups 1, 5, and 9) and no bonding was used in the other half (groups 2, 6, and 10). Also, in half of the groups that used composite Transbond XT 3M was used. G-Premio bonding was used (groups 3, 7, and 11) and in the other half, Transbond XT 3M was used (groups 4, 8, and 12). After connecting the American Central Dental bracket to the composite samples with the aforementioned methods, the samples were stored in 37°C normal saline for another week. A universal testing machine was used to measure the shear strength of the bond when separating the bracket from the surface of the composite restorations. The adhesive residue index (ARI or adhesive residue index) was also examined. To compare the failure and shear bond strength based on the type of preparation and type of composite, a two-way ANOVA test (if normal) and a Kruskal-Wallis test (if abnormal) were used. For significant cases of ANOVA test, Tukey's post hoc test will be used for pairwise comparison of groups. A multifactor ANOVA test was used to compare means. The significance level in all tests was considered less than 5%. Results: The shear bond strength in the sandblasting method was significantly lower than without mechanical preparation. However, it was similar to the milling method. There was also no significant difference between the milling method and without mechanical preparation. The shear bond strength in the application of G-Premio bonding was significantly higher than that of Transbond XT 3M and no bonding. Also, the strength in Transbond XT 3M bonding was significantly higher than that of no bonding. The type of composite did not have a significant effect on the shear bond strength. In summary, the results showed that mechanical preparation (p = 0.019) and bonding (p < 0.001) had significant effects on the shear bond strength, while composite did not (p = 0.347). The interaction effects were not significant, indicating that the effect of each factor on the shear bond strength was independent of the others. The remaining adhesive index study showed that the highest frequency of adhesive index 3 (all adhesive remaining on the initial composite) was in group 3 (Transbond XT 3M composite, milling, G-Premio bonding) with a frequency of 66.7%, group 4 (Transbond XT 3M composite, milling, Transbond XT 3M bonding) with a frequency of 46.7%, and group 1 (GC ORTHO CONNECT composite, milling, G-Premio bonding) with a frequency of 40%. The highest frequency of adhesive index zero (no adhesive remaining on the initial composite) was in group 6 (GC ORTHO CONNECT composite, sandblasting, no bonding) with a frequency of 93.3%. Conclusion: Mechanical preparation has significant effects on shear bond strength. The method without mechanical preparation along with the use of G-Premio bonding has the highest shear bond strength. The type of bonding has significant effects on shear bond strength. The shear bond strength was significantly higher in the use of G-Premio bonding. The type of composite has no significant effects on shear bond strength. The interaction effects (mechanical preparation, bonding type, and composite type) are not significant, indicating that the effect of each factor on shear bond strength is independent of the others.
The relationship of Bolton’s ratios with orthodontic charactristics of anterior teeth and skeletal pattern.
(Tabriz University of Medical Sciences, Faculty of Dentistry, 2022) Karimzadeh, Behnaz; Eidi, Ali; Orthodontics; Kachoei, Mojhghan; Abdollahzadeh Baghaei, Tannaz
Background: The concept of proportional balance of maxillary and mandibular teeth size has emerged since the onset of dental articulation theory. Since then, various methods (analyzes) have been proposed to investigate the intermaxillary teeth size relationships. Bolton's ratios have been used more widely in research and clinical practice, and over the time. Therefore, the values obtained from Bolton's study are known as the standard of diagnosis and treatment planning of orthodontic cases. Objective: The aim of this study was to investigate the ideal Bolton's ratios required to achieve the class I canine relationship and optimal occlusion in patients with class I, II, and III skeletal patterns, and also to evaluate the correlation of skeletal and dental orthodontic factors with Bolton's anterior and overall ratios. Materials and Methods: This study was performed on post-treatment dental models and lateral cephalograms of 210 subjects achieved optimal occlusion. Bolton's anterior and overall ratios were calculated following the measurement of the mesiodistal width of the teeth, the thickness and inclination of incisors, the angulation of maxillary and mandibular canines, and overbite. To assess the intra and inter-examiner errors, dental models and radiographs of 10 subjects were randomly selected and all their measurements were repeated after eight weeks by the researcher and the supervisor. Then, the Intra-class Correlation Coefficient was analyzed by comparing the data sets of each measurement. Then the relationship of each of the studied factors with Bolton's ratios was analyzed using univariate and multivariate regression models. One-way analysis of variance and one sample t-test were used to compare the ideal Bolton's ratios of each group with each other and with reference values, respectively. Results: The Intra-class Correlation Coefficient was ranged between 0.87 and 0.99, which indicates the high accuracy of the measurements. The anterior ratios of the whole 210 subjects and class I group were significantly different from Bolton's reference value (p-value = 0.008 and 0.009, respectively). Also, the standard deviations of anterior and overall ratios were higher than those of Bolton's study. According to the results of regression analyses, there was a significant correlation between U1-OP and the anterior ratio of class II group. Also, overbite, the labiolingual thickness of maxillary incisors, and MP-FH had significant correlations with the anterior ratio of class III group. On the other hand, the angulation of maxillary and mandibular canines, MP-FH, and overbite were significantly correlated with the overall ratio of class II group (p-value < 0.05). Due to the higher correlation coefficient of "overbite and labiolingual thickness of the maxillary incisors" with "the anterior ratio" of class III group, two formulae were designed to predict the anterior ratio of class III group using these variables. Discussion: Higher standard deviations of anterior and overall ratios indicated that a much wider range of Bolton's ratios can lead to optimal occlusion. Therefore, blind adherence to the reference values can impose unnecessary invasive interventions on the patient. This study showed that the correlation of different variables with Bolton's anterior and overall ratios is very complex. So, each of the skeletal and dental factors, in addition to affecting Bolton's ratios, also affects each other. Generally, it seems that any factor that affects the anterior dental arch will influence Bolton's ratios. Conclusion: Orthodontic treatment planning should not be based on blind adherence to Bolton's reference values. Therefore, it is better to decide about stripping, build-up, and tooth extraction, after achieving relative alignment of teeth and appropriate overjet and overbite, by considering the dental and skeletal factors and the type of skeletal malocclusion.