Journal of Dentistry, Shiraz University of Medical Sciences
Volume:13 Issue: 4, 2012

Statement of Problem: Tooth caries is influenced by different biochemical characteristics of saliva. As hydroxyapatite is the main component of enamel، salivary ion activity product for hydroxyapatite (IPHA) as well as alkaline phosphatase may be attributed to dental caries. The aim of the present study was to compare salivary buffering capacity، alkaline phosphatase and IPHA of adults according to the dental caries and age. One hundred and twenty 19 to 44 years old male individuals were divided into four groups according to the dental caries rate and age: group 1:19-35 years old low dental caries (DMFT <5); group 2:19-35 years old high dental caries (DMFT 5<); group 3:35-44 years old low dental caries (DMFT <11) and 35-44 years old high dental caries (DMFT 11<). Five millilitre of unstimulated saliva was collected، and then buffering capacity، the level of alkaline phosphatase activity and IPHA was determined for each sample. Data was analyzed by soft ware SPSS using two-way ANOVA، Friedman and Mann-Whitney tests. Mean and standard deviation of buffering capacity of group 1 to 4 was 2. 66±0. 54، 2. 64±0. 56، 2. 70±0. 70 and 2. 26±0. 82، respectively. The difference was not significance (p= 0. 305). Mean and standard deviation of alkaline phosphatase activity of group 1 to 4 was 5. 82±2. 91، 5. 30±1. 52، 4. 77±1. 82 and 4. 55±1. 61، respectively. There was no significant difference (p= 0. 692). Mean and standard deviation of IPHA of group 1 to 4 was 29. 39±0. 61، 29. 51±0. 76، 29. 14±0. 56 and 29. 75±0. 75، respectively. The difference was significant (p= 0. 049). Based on the results of the present study، buffering capacity and the level of alkaline phosphatase couldn’t affect dental caries، independently. However، the higher value of IPHA may be attributed to the higher dental caries rate. Ageing decreases alkaline phosphatase activity.

tatement of Problem: A minimally invasive method of preparation is essential to prevent tooth structure weakening and pulp irritation; especially for mandibular anterior single-tooth all-ceramic crowns. According to many investigations، one of the most important reasons of pulp injury caused by tooth preparation for different restorative procedures is reduced “remained wall thickness” (RWT). In order to protect the pulp from irritation، it is necessary to maintain a 0. 5 mm of RWT. The purpose of the present study was to evaluate the effect of all-ceramic crown preparation on pulp chamber RWT of mandibular incisors. Mesiodistal and buccolingual initial images of 24 extracted mandibular incisors were provided. The pulp chamber initial wall thicknesses of buccal، lingual and proximal surfaces of cervical، 1and 2 mm above the cervical areas and also the incisal surfaces of incisal sections were measured using digital radiography and Photoshop software. After all-ceramic crown preparation، images were provided at the same initial positions. The initial and remained pulp chamber wall thicknesses were statistically evaluated and analyzed by ANOVA، paired t-test and a post hoc Tukey test. Repeated measures ANOVA showed that the mean of pre- or post-preparation wall thicknesses were not significantly different for each surface at the three horizontal levels (p> 0. 05). However، there were significant differences between the surfaces for each section. Comparison of pre- and post-preparation wall thicknesses revealed significant differences (p< 0. 05). Proximal surfaces of cervical sections had the least RWT (0. 42±0. 12). According to the results of the present study، the least amount of initial and remained wall thicknesses of pulp chamber were related to the proximal surfaces، particularly in cervical areas. Therefore a reduction of preparation to 0. 7 mm is suggested to prevent future pulp injury for mandibular incisors of 35 to 40- year- old patients and younger who require all-ceramic crown preparations.

atement of Problem: There must be a proper mesiodistal tooth size ratio (Bolton analysis) between maxillary and mandibular teeth for good occlusal interdigitation. Therefore the Bolton analysis should be considered during diagnosis، treatment planning and predication of ultimate results. The purpose of this study was to appraise tooth size ratios in Cl II malocclusion group and compare them with normal individuals. This study was carried out on 60 pre-treatment orthodontic casts of class II malocclusion patients and 60 diagnostic casts of normal occlusion individuals which were selected through cluster sampling in accordance with the selective criteria. Each group consisted of 30 men and 30 women. The greatest mesiodistal diameters of all the teeth on each cast were measured by a digital calliper with 0. 01mm accuracy except the second and third molars. Then tooth size ratios were analyzed as Bolton described. The statistical analysis were performed by chi-square and t-tests using SPSS. The prevalence of anterior and overall tooth size discrepancy was relatively high (28. 3%، 20%)، showing no significant difference between men and women (p> 0. 05). The mean of anterior and overall tooth- size ratios in Cl II malocclusion group were 79. 18 and 92. 39 respectively، which were statistically different from the Bolton study (ideal occlusion) ratios (p< 0. 05). There were no statistical difference between the means of anterior and overall ratios of men and women، neither in Cl II malocclusion group nor in the normal individual group (p> 0. 05). Considering the high frequency of tooth size discrepancy among CLII patients and the significant difference in Bolton ratios between this malocclusion and ideal occlusions; it seems that tooth size discrepancy can be considered as a possible etiologic factor and Bolton analysis should be performed as a pre-treatment diagnostic tool for this type of malocclusion.

Statement of Problem: Home bleaching is a common method for whitening the teeth. However، bleaching may lead to a decrease in the hardness of the enamel. The purpose of this study was to investigate the effects of two different concentrations of carbomide peroxide (CP) on the hardness of the enamel and also to evaluate the effects of the remineralising agents on the hardness of bleached enamel. Crowns of 100 intact extracted human anterior teeth were resected from their roots and mounted in acrylic resin in a way that the buccal surface was parallel to the floor (horizontal). The samples were then divided into 10 groups. The baseline hardness in the middle of the buccal surface was measured through Vickers Micro-hardness test and at a load of 500 gram per second. Then five groups were bleached with 10% carbomide peroxide and other five groups with 22% carbomide peroxide. The Tooth Mousse (TM) paste; MI paste plus (MI); and Crest fluoridated toothpaste was applied for 4 hours to the surface of the enamels in three groups. In the forth group، samples were embedded in fresh cow milk for the same period and the fifth group was kept in distilled water as a control group. Then، the final hardness was measured and the collected data were analyzed by t-test، paired sample t-test and One-way ANOVA test. Bleaching with the aforementioned concentration of CP had no effects on enamel microhardness. In the groups with a 10% CP، none of the demineralising agents had any effect on the hardness value. However، the application of milk increased the hardness. In the groups with a 22% CP، TM paste reduced the enamel microhardness value while Crest، increased it. MI paste and milk didn’t have any effect on it. The use of TM paste results in lower hardness of the bleached enamel. It seems that the high concentration of fluoride in MI paste may be responsible for increased microhardness of enamel. Milk and fluoridated toothpaste have propensity to increase the enamel hardness.

Statement of Problem: Flare up is an acute exacerbation of an asymptomatic pulpal and/or periapical pathosis after commencement or termination of root canal therapy. Its incidence may be different in patients treated by different practitioners regarding their graduation status. The aim of this study was to compare flare up incidence in patients treated by dental students of Shiraz Dental School and those whom were treated by endodontists. Patients'' information including age، gender، and previous history of pain and pulp vitality were taken before treatment of 383patients. 230 of them were treated by senior dental students of Shiraz Dental School and 153of them were treated by endodontists. Students employed conventional step back technique whereas specialists had a chance to select variety of techniques. Data، regarding the quantity of pain experienced by patients were collected 48 hours after treatment. Case was considered a flare up if the patient had experienced severe pain which hadn’t been reduced either by analgesic medication or by consequent swelling. Chi- square statistic tests were used to analyze the receiving data. 41 individuals (10. 7%) out of 383 patients depicted flare up. 13. 5% of these patients were treated by students and 6. 5% were treated by endodontists. The difference was statistically significant. Different rate of flare up in two groups is probably due to the dissimilarity in skills، techniques and materials used by different operators.

Statement of Problem: The effects of individual variations in coping strategies have been debated in studies of the association between stress and chronic periodontitis، with conflicting results. To investigate the associations between stress، coping styles and periodontal disease in a sample of Iranian population. Forty patients with chronic periodontitis and forty control subjects with a healthy periodontium were enrolled in this study and matched for age and gender. Participants were patients undergoing periodontal treatment at the Department of Periodontics، Guilan University of Medical Sciences. A single examiner performed periodontal examination. Psychological assessments، including the Life Events Questionnaire and the Ways of Coping Questionnaire were done by a second examiner; both examiners were blind to the study. Bi-variate and multivariate logistic regression analyses were used to compare results for patients and control subjects. Statistically significant differences in the problem-focused coping (p< 0. 01)، intensity of stress (p< 0. 006)، as well as escape-avoidance (p< 0. 01)، and accepting responsibility (p< 0. 001) subscales were observed between the patient and control groups. Multivariate logistic regression identified a negative association between periodontitis and tooth-brushing frequency (OR= 3. 3، 95% CI: 1. 22- 8. 69)، as well as the accepting responsibility coping style (OR= 1. 5، 95% CI: 1. 14- 1. 98)، and a positive association with stress intensity (OR= 1. 081، 95% CI: 1. 023-1. 143). The results suggest that psychological stress associated with various life events is a significant risk indicator for periodontal disease. Although statistically small، there was a clinically important link between coping strategies and periodontal disease.

hondrosarcomas are slow-growing، malignant mesenchymal neoplasms characterized by formation of cartilage by the tumoral cells. They display a wide range of morphological features from a well-differentiated growing mass resembling a benign cartilage tumour to a high-grade malignancy with aggressive local invasion. Only 5% to 10% of this neoplasm is confined to the head and neck region. Chondrosarcomas of the mandibular condyle may manifest the typical symptoms of the temporomandibular joint dysfunction syndrome. Tumours of the condyle can reach a large size without producing clinically obvious swellings. A rare case of chondrosarcoma of the mandibular condyle in a 34-years old woman is presented in this report. Patient’s chief complaint was pain in the right temporomandibular joint when her mouth was in a maximum opening position. Mild malocclusion، figured as an occlusal discrepancy، was also detected. Radiographs illustrated erosion in the head of condyle. After condylectomy، the excised mass was histologically diagnosed as a grade II chondrosarcoma.

Eosinophilic granuloma (EG) is the mildest and localized form of a group of diseases named Histiocytosis X. It is a destructive osseous lesion characterized by presence of a vast number of eosinophils and histiocytes. It has a neoplastic nature especially in the chronic forms. Based on the site of the lesion، three types are elucidated: 1- intraosseous 2- alveolar 3- mixed. In the last two types، extensive alveolar involvement and loosening of the teeth clinically may resemble aggressive periodontitis (AP). We report a case of EG which was initially diagnosed and treated as AP. The rapid progress، diagnostic problems، etiologic factors and the consequences of late diagnosis and treatment of eosinophilic granuloma are discussed. This explicates why dentists need to know the differential diagnosis of EG with AP for early diagnosis and treatment.