مجله دانشکده دندان پزشکی اصفهان
سال یازدهم شماره 4 (پیاپی 51، مهر و آبان 1394)

Considering the application of magnification in evaluation of digital images during root canal therapy to assess the tip of small endodontic files، the purpose of the present study was to evaluate measurement accuracy of endodontic file lengths in periapical digital radiography after using digital magnification tools. In this experimental study، thirty-five human single rooted permanent teeth with 20‒24 mm of canal length were selected. ISO #08 endodontic files were placed in the root canals up to the working length. The files lengths were measured with digital caliper as gold standard. Periapical digital images were obtained with Digora storage phosphor plates and their special scanner، Digora Optime، using a Prostyle dental X-ray unit as original images. Magnification tools were applied to each original image. Two blind radiologists measured the file lengths on original and magnified images. The measurements were compared using ANOVA and Bonferroni test (α=0. 05). All the digital images with and without magnification overestimated file lengths in comparison to the gold standard (p value = 0. 45). Measurement accuracy of ×2 and ×3 magnified images did not show any significant differences in comparison to original digital images (p value = 1 and p value = 0. 44، respectively). There was no significant difference between ×2 and ×3 magnification (p value = 0. 15). Images with ×3 magnification overestimated measurements compared to original digital images; however، the differences were not significant (p value = 0. 10). Under the limitations of the present study and based on the results، use of magnification tool did not influence length measurement accuracy of small endodontic files on digital periapical radiographs in vitro.

Periodontal disease is one of the most important diseases in health topics. The aim of this study was to determine the effect of periodontal treatment on quality of life. In this quasi-experimental, interventional study, 45 patients with chronic periodontitis were asked to complete the “quality of life” questionnaire before starting the treatment and four months after periodontal therapy. Then the questioners were evaluated and scored. Wilcoxon’s test was used to compare each question before and after treatment. Paired t-test was used to compare quality of life indices before and after treatment. T-test was used to compare the quality of life indices between males and females and between patients with mild to moderate and moderate to severe periodontitis (α=0.05). The mean scores of all the indices of quality of life, including sports, nutrition, stress control, business activity, physical status and appearance, sleep and rest, social relations and physical health, showed significant differences before and after periodontal treatment (p value < 0.001). Differences between the mean scores of indices of quality of life after periodontal treatment in females were higher than males, but they exhibited significant differences only in sports and business activity (p value = 0.006 and p value = 0.004, respectively). There were no statistically significant differences in the mean scores of all the indices evaluated in patients with mild to moderate periodontitis and with moderate to severe periodontitis before and after treatment (p value > 0.05). Under the limitations of the present study, it can be concluded that periodontal treatment improves the quality of life.

Excessive temperature rise during drilling of the mandible for dental implant placement might damage adjacent osseous tissues. Various factors affect temperature rise, including the geometrical parameters of surgical drills, one of which is the drill bit head angle. The aim of this research was to determine suitable drill bit head angle to induce minimum temperature rise during mandible drilling operation for dental implant placement.

In this research, the finite element analysis software DEFORM-3D Ver 6.1 was used for mandibular cortical bone drilling. To this end, three drill bits with different head angles of 70, 90 and 118 degrees were designed in this software. Three-dimensional modeling of the mandible was performed using CT scan images and MIMICS 10.01 software. To place the drill bit on the mandibular model, CATIA V5R19 software was used to remove a tooth from the distal end of the mandibular model. Finally, to perform the drilling operation, the model of the mandible was imported to DEFORM-3D Ver 6.1 software in STL format.

At the end of these simulations, the diagrams of maximum heat generated in mandibular bone during drilling operation and mean temperatures were obtained. The results showed that the drill bit with 70° head angle resulted in the minimum mean temperature of 75.4ºC compared to 90 and 118 degrees with mean temperatures of 81.1°C and 93.4°C, respectively.

The results indicated that drill bit with 70° head angle is more appropriate for mandibular bone drilling operation than other larger bit angles.

Given controversies over the extent of root canal preparation and the importance of root canal preparation and flaring in microleakage and its effect on the preservation of teeth, the aim of this study was to evaluate the effect of the root canal flaring extent on bacterial microleakage in vitro. In this in vitro study 126 human single canal teeth were selected using simple sampling technique. After decoronation with a diamond disk, access cavities were prepared and the root canals were prepared with step-back technique up to file #30. Then the teeth were divided into three groups randomly for root canal flaring up to files #45, #55 #70 after the master apical file. After the preparation, the root canals were obturated with lateral condensation technique. To evaluate microleakage every 3 days Enterococcus faecalis solution was injected to the samples and microleakage was evaluated for 90 days by turbidity of the antiserum solution around the root. Data were analyzed with SPSS 20 using chi-squared test and survival analysis (α=0.05). The results showed that during the 90-day study period microleakage was significantly lower in group 2 compared to the other two groups (p value = 0.025 and p value = 0.036), and maximum survival rate was observed in this group. However, the survival analysis did not reveal any significant differences between group 1 and group 3 (p value = 0.717). The results showed that root canal preparation up to different file sizes affected microleakage and preparation up to file #55 resulted in the least microleakage.

One of the main problems in stress analysis of new prosthesis materials stems from their unpredictable shape. The aim of this study was to determine the effect of adhesives and ligament on stress distribution in cantilever and fixed-end prostheses. In the present study, finite element analysis was used to prepare physical models from natural teeth. Then three-dimensional images were prepared from the finite element model and the relevant prostheses. The finite element was prepared to apply the proper load and boundary conditions, followed by calculation of shear and von Mises stresses along with displacements in teeth, adhesives and prostheses. In the fixed-end prosthesis the Z100 adhesive exhibited the highest von Mises stress value, which increased with an increase in the adhesive elastic modulus. Panavia 2 adhesive ranked the second after Z100 adhesive. Variolink and C&B adhesives exhibited less von Mises stresses under the same loading condition. Elimination of ligaments resulted in an 0.2% increase in the shear stress in Panavia 2 and Z100. In the cantilever prosthesis, the Z100 adhesive still exhibited the highest stress value, with Panavia 2 ranking the second. Elimination of ligaments in the cantilever prosthesis resulted in a slight decrease in von Mises stresses in all types of adhesives, contrary to fixed-end prosthesis. The effect of ligaments on the displacement of the cantilever prosthesis was more than that on the fixed-end prosthesis. Based on the results, there were less stresses in fixed-end prosthesis compared to cantilever prosthesis. Although the shear and von Mises stresses were higher in Panavia 2 and Z100 adhesives compared to Variolink and C&B, due to their Poisson’s ratios and elastic moduli, which were close to those of the dentin, they produced less displacement in the prostheses.

The aim of this study was to determine purpose-based self-evaluation for the diagnosis of oral pathologic lesions among Isfahan dental school students in different educational levels so that the shortcomings and advantages of theoretical courses on the subject could be evaluated from the beginning to the end of the course.

In this cross-sectional, descriptive-analytical study a self-evaluation questionnaire was designed by students and approved by the Department of Oral and Maxillofacial Pathology academic staff in Isfahan Dental School. A total of 164 dental students in 6th, 10th and 12th semesters were included in the study using census sampling technique. The students answered the questions. Data were analyzed with SPSS 20 using two-way ANOVA and Kruskal-Wallis, Mann-Whitney and post hoc Tukey tests (α=0.05).

A total of 164 dental students from semesters 6 (68, 41.5%), 10 (51, 31.1%) and 12 (45, 27.4%) were evaluated. The mean scores of self-assessment were higher in students in the10th and 12th semesters compared to students in the 6th semester (p value = 0.001). Two-way ANOVA showed that the effects of educational level and sex on the mean self-evaluation score were significant (p value = 0.004 and p value = 0.006, respectively).

Self-evaluation scores of students to diagnose oral pathologic lesions were higher in students in the 10th and 12th semesters compared to those in the 6th semester, with a significant relationship with gender and age. In this context, female students exhibited higher scores compared to boys and the scores increased with age.

Research has shown that oral health-related knowledge and behaviors are poor for pregnant women and the prevalence of dental caries and other periodontal disease is relatively high among them. This study examined the effect of educational intervention on the oral health-related practice of pregnant women using TTM. This randomized controlled quasi-experimental study was carried out in the first half of 2013 in Qazvin, Iran. Using a multistage sampling procedure, 130 pregnant women referring to health centers in Qazvin were selected to participate in the study. Demographic data, TTM construct-related questions and oral health-related behaviors of pregnant women were collected using valid and reliable self-administered questionnaires before and after intervention. According to the needs assessment and based on TTM constructs, three 45-minute sessions of group discussions associated with lectures, debating and pamphlets were held for the experimental group. Finally, the data were analyzed with SPSS 19.0 using chi-squared test, independent and paired t-tests and Wilcoxon and Mann-Whitney tests (α=0.05). After training, significant increases were observed in the means of self-efficacy (from 23.6±6.4 to 39.5±8.6), preparation steps (from 1.6±0.9 to4.2±0.7), profits (from 29.2±9.0 to 51.4±12.3) and change processes (from 27.9±8.1 to 54.4±10.5) in the experimental group (P< 0.001). Also, a significant decrease was found in the mean score of costs (from 24.4±5.7 to 11.7±7.0) (p value < 0.001). In addition, the mean score of oral health behaviors in pregnant women increased significantly in the experimental group (from 49.0±6.8 to 73.6±9.4) (p value < 0.001). Intervention with the use of trans-theoretical model in pregnant women is able to improve oral health behaviors and develop underlying and predisposing factors related to health behaviors.

Bioactive glasses have been reported to be able to stimulate more bone regeneration compared to other bioactive ceramics but they lag behind other bioactive ceramics in terms of commercial success. The full potential of bioactive glasses is yet to be explored, with research activity in this respect being on the rise. The purpose of this paper was to review the applications of bioactive glasses in synthetic bone grafts and natural bone regeneration.Search strategy: This paper reviewed the current products and the recent developments in an attempt to evaluate the current state of this new industry. All the relevant articles published in Pubmed, Google Scholar and Science Direct from 1971 to 2013 with the key words Bioglass, Scaffold, Graft and bone were searched. After studying 120 article abstracts, some of the papers were reviewed completely and 76 articles covering the most important clinical and biological aspects of synthetic bone grafts and natural bone regeneration were selected. The 45S5 Bioglass was the first artificial material that was found to form a chemical bond with bone, launching the field of bioactive ceramics. In vitro studies showed that bioactive glasses bond with bone more rapidly than other bioceramics, and their osteogenic properties were attributed to their dissolution products stimulating osteoprogenitor cells at the genetic level. However, calcium phosphate products such as tricalcium phosphate and synthetic hydroxyapatite are more widely used in the clinic. This review focused on the effects of various products on synthetic bone grafts. Since bioceramics are fragile they cannot be applied to bone defects that are subjected to cyclic loads, as they are brittle. To overcome this problem, bioactive glass polymer hybrids are being synthesized that are resistant and durable, with identical coefficients of bioactive minerals and polymers in their chemical structure.