Journal of Dentistry
Year:2011 | Volume:12 | Issue:1 (30)|Papers Count:14

Statement of Problem: Periodontal regeneration in the furcation defect is considered as one of the most challenging aspects of periodontal therapy. Among different approaches, GTR has shown promising biologic and clinical results. There is evidence indicating that the use of platelet-rich plasma (PRP) may improve the outcome of regenerative periodontal therapy.Purpose: This study aimed to examine the effect of the combination of PRP and Bio-oss on bone regeneration in class II furcation defects in dogs.Materials and Method: 48 experimental defects with 5 mm horizontal and 5 mm vertical open probing depth were created in furcation areas of each premolar of dogs. The defects were randomly divided into 3 groups: test group in which the defects were grafted with bio-oss and PRP, control group in which the defects were grafted with bio-oss alone, and negative control group in which no graft was used. An absorbable collagen membrane was placed over each defect site and the flaps were sutured. The animals were sacrificed 3 months later and biopsy samples were taken from the defect sites for histologic and histomorphometric assessment. In each section, the area fractions (%) within the bone specimens occupied by newly formed bone, soft tissue, and residual grafting particles were determined. The data were analyzed statistically using Student's t test through SPSS software (version 13.0).Results: The bone fill was 61% in the test group, 58% in the control group, and 39% in the negative control group. Although no significant difference was observed between the test and control groups, the differences between the test and control groups with negative control group were significant (p<0.05). In the control group, the lamellar bone formation was higher and the chronic inflammatory infiltration was lower.Conclusion: Within the limitations of this study, the use of bio-oss and PRP in the treatment of class II furcation involvement has no additional benefit over bio-oss alone. However, it seems that PRP can improve the quality of the new bone while decreasing the amount of tissue inflamation.

Statement of Problem: Squamous cell carcinoma (SCC) is the most common cancer of the mouth, but its pathogenesis is unknown. HER2/neu is a protoncogene with homologue sequence with EGF. aSMA is a smooth muscle specific actin which indicates the existence of myofibroblasts in the oral cancer stroma. Purpose: This study aimed to measure the frequency of Her2/neu and (alpha) aSMA in oral SCC. Materials and Method: For this study, 18 paraffinized blocks of OSCC were immunostained with Anti HER2/neu, Anti (Alpha) SMA. Percentage and degree of the epithelial cells staining and percentage staining of myofibroblasts were considered. The results of the study were analyzed using kappa and X2.Results: From 18 cases of OSCC, 3 and 12 cases were positive with HER2/neu and aSMA, respectively. In the normal oral mucosa, one case was positive (Score 2) with HER2/neu but aSMA positive myofibroblasts were not seen in the stroma of OSCC. A significant difference was seen in aSMA expression in OSCC and the normal oral mucosa (p=0.002). No significant difference was found in HER2/neu expression in OSCC and normal mucosa (p>0.05).Conclusion: The results of this study suggest that aSMA has an effective role in pathogenesis and aggressive behavior of OSCC but HER2/neu has no main role in this type of oral cancer.

Statement of Problem: Porcelain laminate veneer is one of the most important restorations in dentistry because of stable esthetic and low destructive technique. But the main reason of failure in this treatment is porcelain fracture. Therefore, tooth preparation has an important role in fracture resistance of porcelain laminate veneer. Purpose: The aim of this in-vitro study was to compare the effect of tree preparation designs, shoulder and chamfer and heavy chamfer, on fracture strength of porcelain laminate veneer. Materials and Method: This experimental and in-vitro study was performed on 30 upper central teeth without fracture, carries or any problem. The teeth were divided into three-10 teeth groups. Then, the preparation design was performed perfectly. In the palatal surfaces of the first group we used deep chamfer preparation design and the shoulder and the chamfer designs were performed for the second and third groups, respectively. Then the samples were put in instron machine with the angle of 30 degrees. The force rate which led to break in those samples was determined. The data were analysed usig t-test.Result: Resistance against breakage in the deep chamfer, shoulder and chamfer groups were 283.40±17, 231.50±25.61 and 254±21.71 Newton, repectvely. No significant difference was found among the groups.Conclusion: The higher fracture resistance was observed in deep Chamfer/palatal over lap technique, so we prefer to use this kind of preparation for palatal extension of Porcelain Laminate Veneers.

Statement of Problems: The main disadvantage of elastic chains is their rapid force decay. Thus, pre-stretching has been recommended as a method to overcome this ever existing problem. However, the information regarding the magnitude and the method of its performance are still obscure or varied.Purpose: This study was designed to evaluate the effect of pre-stretching on force degradation of the synthetic elastomeric chains. Materials and Method: This experimental study had two categories of synthetic elastomeric chains: 1. Control (unprestretched) 2. Test (prestretched). The test groups were pre-stretched to 33%, 100% and 200% of the original length. We evaluated 4 control and 16 test groups from four manufacturers. In a period of 5 seconds, each specimen was pre-stretched in the rate of 30 mm per minute. Then, all the specimens were stretched to 25 mm and fixed in this distance on the frames and were merged in 37 degree water. Their forces were measured at 0 hour, 1 hour, 24 hours, 1 week, and 3 weeks. Data were analyzed using Friedman, ANOVA and Green house-Geisser test.Results: All the 20 groups had force degradation in the study period (p<001). The highest rate of force degradation (about half of the total force degradation) occurred at the first hour. But the rate of force degradation declined over time. In all brands, force degradation was smaller in pre-stretching 200% than the control group (p<0.01-0.001). Conclusion: Synthetic elastomeric chains from several companies have different effects from different distances of pre-strectching, so the appropriate pre-stretching length must be defined for each kind of synthetic elastomeric chain.

Statement of Problems: Ethnic and sex differences in the mesiodistal width of the teeth have been proved in different studies. The prediction methods of the canine and premolar width have been obtained from other populations, which are in controversy with the results of previous Iranian studies.Purpose: The aim of this study was to determine the accuracy of the Tanaka-Johnston prediction equations and Moyer’s prediction tables in the prediction of un-erupted canines and premolars in a South Iranian population. Also, new regression equations and tables are presented to predict the width of the un-erupted canines and premolars based on the sum of the mesiodistal width of the lower incisors. Materials and Method: For this cross-sectional study, a total of 715 dental casts were recruited from southern Iranian population. The greatest mesiodistal widths of all the teeth were measured using digital caliper with the accuracy of 0.01 mm. All the data were compared with Moyers’s and Tanaka-Johnston predictions using Pearson Correlation, independent t-test and paired sample t-test. New regression equations were presented with multiple linear regression tests and new prediction tables were presented with LMS chart maker software.Results: Tanaka-Johnston equations and Moyer’s prediction tables revealed a significant difference with the mesiodistal dental width of southern Iranian population and the predictions were overestimated in this population. Also, there was a significant difference between the mesiodistal width of the teeth of males and females. So, new regression equations and tables (based on the sum of the lower incisors) were introduced for different jaws and sexes in this study. The suggested regression for prediction of the maxillary canine and premolars based on the summation of mesiodistal width of the lower incisors was y=0.529x+9.161 and for prediction of the mandibular canine and premolarsit was y=0.567x+7.827.Conclusion: Tanaka-Johnston and Moyer’s prediction tables overestimate the actual size of southern Iranian’s teeth width; Moyers prediction tables are not accurate in the prediction of the width of the canines and premolars in none of the percents. So, application of these methods is not suggested for Iranian population.

Statement of Problem: Psychosomatic factors and their association with dermatological disorders are well recognized; yet, their importance in oral lichen planus (OLP) is still debated. Purpose: This study was done to determine the importance of stress in patients with OLP.Materials and Method: In this cross-sectional case control study, the control group consisted of 47 apparently healthy patients without any mucosal lesion, and the experimental group consisted of 52 biopsy proven OLP subjects (28 erosive lichen planus and 24 reticular form) which were age and sex matched with the control group. They were referred to department of oral medicine in Tabriz University of Medical Science during May 2008-July 2008. The General Health Questionnaire-version 12 (GHQ-12) and the Perceived Stress Scale (PSS) were used to evaluate stress in OLP patients and control group.  The data were analyzed through Kruskal-Wallis and Man Whitney tests. P value less that 0.05 was considered as significant.Results: The patients with erosive lichen planus had significantly more stress (Z=4.123, p<0.05) than the controls. Similar findings were noted between the reticuler lichen planus and control group (Z=5.891, p<0.05). However, the differences in stress (Z=2.248, p>0.05) was found to be non-significant between the patients with erosive lichen planus and reticular form.Conclusion: A significantly higher level of stress was found in the OLP patients (both erosive and reticular form) than the control group, but no significant difference was noted between the patients with erosive lichen planus and reticular form. Therefore it can be concluded that psychological stressors play an important role in the creating OLP.

Statement of Problem: The control of microleakage presents a challenge for posterior composite restorations. The technique for composite placement and treatment technique may cause some modifications in the microleakage. The results of different studies are varied. Purpose: This study aimed to evaluate the marginal microleakage in class II P60 resin composite restorations prepared with two restorative techniques and two polymerization systems. Materials and Method: Standard class II cavity preparations were performed on 56 carries- free extracted molars. Then, the teeth were randomly divided into four groups: 1) Bulk placement and conventional polymerization 2) Incremental placement and conventional polymerization 3) Bulk placement and soft start polymerization 4) Incremental placement and soft start polymerization. All the cavities were restored with single bond and P60 (3M/ESPE) resin composite. After thermocycling, the specimens were immersed in 2% methylene blue solution for 24 hours and then washed. After sectioning, dye penetration was assessed by light stereomicroscopy at 40x magnification and then evaluated for microleakage by Kruskal-Wallis Test and Mann-Whitney tests.Results: Significant differences were found between the bulk with incremental technique and soft start with conventional polymerization. The highest and lowest rates of microleakage were in bulk conventional and incremental soft start group, respectively. A significant difference was found between groups.Conclusion: The use of incremental placement technique and soft start system results in less microleakage.

Statement of Problem: One of the considerations regarding the space analysis in study casts is the issue of speed and precision in analysis.Purpose: This research aimed to design a software to conduct space analysis and evaluate its accuracy compared to manual space analysis.Materials and Method: This reasearch was conducted in two stages: Exploratory and Cross- Sectional. The subjects were selected randomly from patients between 7 to 11 years of age referring to the orthodontics clinic at the dentistry school of the Islamic Azad University. About 30 study models (15 pairs) were randomly selected. Space analysis with manual method was performed .Space analysis with the aid of Cyber Space Analysis software was also carried out by locating the required landmarks on digital images of dental casts. The accuracy of this software in comparison with the manual method in space analysis for mixed dentition was evaluated using T student test.Results: The average time required for space analysis using the software was 3.4 minutes as compared to the manual method which took 7.81 minutes on average. The results from software-assisted space analysis showed no significant difference with that obtained from the manual method (p<0.0001).Conclusion: The results from software-assisted space analysis were similar to those of the manual method. However, software-assisted space analysis is carried out more quickly than the manual method.

Dental caries is a chronic infection disease that manifests itself through demineralization of dental tissues and cavitations in the tooth structure. The diagnosis of dental caries poses challenges due to the complex interaction of multiple endogenous causal factors. Naturally, visual and visual-tactile examinations have been the most commonly used diagnostic aids in caries examination for many years. A major drawback in common dental examination was the use of varied diagnostic criteria by various authors. Some extensive reviews regarding this have emphasized the need for a unique system for the diagnosis of such caries. Thus, International Caries Detection and Assessment System (ICDAS) emerged as a benchmark for detection and assessment of dental caries. The main objective of the new system is to improve the level of information to help make informed decision about diagnosis, prognosis, and clinical management of caries at both individual and public health levels.This study aimed to review traditional caries diagnosis methods and also describe the philosophy of the new ICDAS system for diagnosis and assessment of caries and also demonstrate how it can serve as a basis and benchmark for clinical and epidemiological research.

Cementoblastoma is a rare neoplasm accounting for less than 1% of all odontogenic tumors. It mostly arises in the mandible but rarely in the maxilla. The tumor appears as a slow-growing solitary mass which usually results in pain and swelling.In this report, the clinical, radiographic and histopathologic characteristics of cementoblastoma in a case of maxillary cementoblastoma with delayed diagnosis are presented.

The angiofibroma is a rare benign vascular tumor that often occurs in the nasopharyn and paranasal sinuses in male adolescents. Presentation of this lesion in the oral cavity is very rare. This paper presents the case of a-50-year old male with an angiofibroma on the buccal mucus as exophytic lesion with red-brown color which had grown during 8 years. Based on the clinical findings, working diagnosis was mesenchymal tumor. After excisional biopsy, histopathologic feature proved to be angiofibroma.

The Nasopalatine duct cyst is the most common developmental nonodontogenic cyst of the oral cavity, occurring in about 1% of the population. The most common presenting symptoms include swelling of the anterior palate, drainage and pain. Occasionally, this cyst is seen unilaterally. Nasopalatine duct cysts are treated by surgical enucleation. Recurrence and malignant transformations are rare. We reported a 54 y/o male patient from Tabriz. His chief complaint was unilateral swelling of the anterior right side of the maxillary mucosa. In clinical examination, a slight and painless swelling in the region of the right maxillary central, lateral and canine teeth was seen. Occlusal radiographs demonstrated well defined unilocular radiolucency. Final histopathologic diagnosis was “Nasopalatine duct cyst”.