Journal of Dentistry, Shiraz University of Medical Sciences
Volume:10 Issue: 4, 2010

Statement of Problem: Decalcification of the enamel in orthodontic patients mainly follows plaque accumulation, but it is promoted by appliance component¬ts and the materials used for bonding. This study was designed to compare the microleakage beneath meta¬llic orthodontics brackets, using two different methods of enamel preparation. Sixty bovine deciduous lower incisors were collected, and divided into two equal groups. For bonding the stainless steel brackets using Transbond XT as light cured composite, the surface enamel preparation of each group was as follows: Group I: Acid etch+Transbond XT primer and Group II: self-etching primer. After immersion in fuchsin basic 0.5% for 24 hours, each group was randomly divided into two subgroups of 15 samples and placed in acrylic block, in order to have mesiodistal and buccolingual sectioning. The sectioned teeth were evaluated under stereomicroscope and both enamel-adhesive and adhesive-bracket interfaces were scored for the microleakage. Kruskal-Wallis and Mann-Whitney U tests were used for statistical analysis to compare the groups. The level of significance was set at p <0.05. No significant differences in the microleakage scores on the gingival and incisal sides were observed in the interfaces between the groups (p >0.05). Mesiodistal margins of the self-etching group showed significantly lower scores for microleakage in the enamel-adhesive interface in comparison with acid etch group (p <0.05). With the limitation of this study using the self-etch primers in enamel preparation for bonding of the orthodontic brackets seems acceptable if all the margins of the brackets are cured directly.

Statement of Problem: Gutta-percha presents no adhesion to the tooth structure and sealers. Ideally, it should be replaced by a material that offers better sealing in the entire length of the root canal. The aim of this study was to compare the coronal microleakage of a root canal filled with different pairs of Gutta-percha (GP), Resilon, Epiphany and AH26. For this study, 130 mandibular premolars were chosen. After decoronation and preparation of the root canals of the teeth, they were divided into four experimental groups with 30 teeth each and 2 control groups. Group one was obturated with GP and AH26 sealer, group two with GP and Epiphany sealer, group three with Resilon tips and Epiphany sealer, and group four with Resilon tips and AH26 sealer. All the groups were obturated, using cold lateral condensation. Micro-leakage was tested using a two-chamber bacterial method. The data were subjected to statistical analysis, using a Kaplan-Meier test. The bacterial microleakage test showed no significant difference between groups (p =0.1718). It is concluded that, in vitro, the epiphany obturation system is as good as gutta-percha sealed with AH26 when compared over 90 days of saliva storage.

Statement of Problem: Periodontal problems seem to be more common in mentally retarded children due to the poorer oral hygiene than in mentally healthy children, but no data are available on periodontal treatment needs in these children in Mashhad. The purpose of this study was to determine periodontal treatment needs of the mentally retarded children in Mashhad, Iran, using the Community Period-ontal Index for Treatment Needs. In this descriptive cross-sectional study, 258 mentally retarded children aged 9-14 years consisting of 38 educable, 95 trainable and 125 profound children residing in governmental and private centers in the city of Mashhad, Iran were assessed for Community Periodontal Index for Treatment Needs (CPITN). For analyzing the results of the study, T-test and analysis of variance (ANOVA) were used. The level of significance was set at p <0.05. Statistical analysis revealed that the mean CPITN among different age groups was 1.34±0.49. The mean CPITN increased with age (p =0.01) and with the level of mental retardation (p= 0.001). The treatments needed for most of the children were oral hygiene instruction (74.42%), followed by scaling (23.64%), and extensive periodontal treatments (1.16%). Only, 0.78% of the population demonstrated healthy periodontal tissue. Mean CPITN was significantly higher in governmental centers than private ones (p =0.02). It was concluded that the periodontal treatment needs (oral hygiene instruction) of the mentally retarded children was high in Mashhad.

Statement of Problem: The chemical reactions occur at the amalgam surface when exposed to bleaching agents. Mercury ion is released from dental amalg-am when bleached. The aim of this in vitro study was to investigate the effect of carbam-ide peroxide (CP) on the release of mercury ion from two types of spherical dental amalgam. Two commercial brands of dental amalgam, Cinalux and GS-80, were selected. 18 amalgam discs of any brand were prepared in silicon moulds according to the manufacturer's instructions. After 60 minutes, the discs were removed and individually immersed in artificial saliva (AS) for 24 h at 37 0C. Then, the discs of any amalgam were divided into two equal test group (A) and control group (B). Each specimen in the test group was treated in eight-hour cycles with 10% CP. The specimens of the control group was treated in similar cycles with AS. All of the solutions were taken for Hg ion release deter-mination, using cold-vapor atomic absorption mercury analyzer system. The data were analyzed using General Linear Model followed by Repeated Measures ANOVA. The results indicated that the bleaching agent significantly caused more mercury ion to be released into the solutions (p <0.05) but artificial saliva did not show this effect. The release rate of mercury from the Cinalux during the two weeks of treatment period with 10% CP showed an increase from 11.63 µg/lit in the first day to 228.85µ g/lit in the last day. The release rate from GS-80 showed a decrease from 130.96 µg/lit in the first day to 80.68µ g/lit in the last day. Treatment with %10 carbamide peroxide increased mercury release from dental amalgam in comparison with the artificial saliva. The release of Hg from 2 brands of dental amalgam was in a safe range.

Statement of Problem: Many epidemiological surveys have been conducted in different parts of the world to determine the prevalence of various types of dental anomalies. There are regional and ethno-racial variations in the prevalence of dental anomalies. To assess the prevalence of dental anomalies in a group of Iranian dental patients in Shiraz dental school, Iran. 414 dental patients referring to dental school and aged between 15-60 years old (257 female and 157 male) were examined clinically and radiographicaly for the presence of dental anomalies, using orthopanthomography. Data were collected and analyzed by Chi-square and Fisher exact tests. Fluorosis was the most prevalent anomaly (7.72%) followed by missing of the wisdom teeth (7%), impaction of teeth (4.34%), microdontia (2.89%), missing of the mandibular second premolars (2.65%), supernumerary teeth (2.4%), missing of the maxillary lateral incisors (1.6%), dilaceration (1.44%), invagination (1.44%), and taurodontism (0.96%). In the comparison of these results with those of other studies, it was indicated that these anomalies occur at different frequencies among various coun-tries and communities in the world. Recognizing these anomalies will facilitate the endodontic, prosthodontic, periodontic and surgical management of such teeth.

Statement of Problem: In thrombosis and ambolism therapy, one of the therapeutive options is the use of anticoagulents. Patients who take anticoagulants are susceptible to bleeding and cannot brush or floss their teeth. They are prone to periodontitis. Periodontal diseases are associated with periodontal cell destruction and consequently their cell contents would be found in the saliva. The assessment of albumin and total protein contents and determi-nation of its correlation with periodontal parameters in patients who take warfarin are the goals of the present study. In this case-control study, the subjects were classified into 2 groups of patients who took warfarin (case group) and those who did not take any medication (control group). In both groups, periodontal parameters such as plaque index (PI), gingival index (GI), pocket depth (PD), bleeding on probing (BOP) and clinical attachment loss (CAL), and total protein and albumin were assessed. T-test and Pearson test were used to analyze the data. Although salivary albumin was significantly higher in the case group in comparison with the control one, total salivary protein contents were not observed differently between the two groups. Compared with the control group, periodontal clinical parameters were high in the case group and obvious significant differences were seen (p <0.05). Appropriate oral and gingival hygiene instruction is necessary due to the high periodontal clinical parameters in patients who take warfarin.

Statement of Problem: Oral Lichen Planus (OLP) is a chronic immunologic disorder with unknown etiology. Stress and anxiety are some risk factors for OLP and Vitamin B12 and folic acid have been proved to be effective micro-nutrients for prevention of anxiety and depression. The purpose of this study was to investigate serum Vitamin B12 and folic acid deficiency in patients with OLP. Forty eight individuals (32 cases with histopatholo-gically proven OLP and 16 healthy subjects) were recruited. Serum folic acid and Vitamin B12 were assessed for each individual. T-test was applied for data analysis. Vitamin B12 deficiency was found in 8 of 32 cases with OLP (25%) while in the control group it was found in 12.5% of the subjects (p >0.05). Of the 32 patients with OLP, one had folic acid deficiency while none of the control subjects had such a deficiency (p >0.05). Although Vitamin B12 deficiency in OLP patients did not show a statistically significant difference compared with healthy subjects, it was approximately twice as much as the control group. And it can be suggested that Vitamin B12 may have some effective roles in OLP pathogenesis while folic acid deficiency cannot be considered as a prominent risk factor in OLP. More studies are needed to prove such relation.

Statement of Problem: Congenital missing tooth is the condition of having genetically one or more missing teeth which cannot be observed clinically or in radiographic images. This is one of the most prevalent anomalies in dental development that occurs either individually or as symptoms of a syndrome. Moreover, for permanent teeth, it is common with a reported prevalence of between 1.6-9.6%. The aim of this study was to assess the prevalence rate and the pattern of congenital missing teeth in adolescents referring to Mashhad School of Dentistry. In this cross-sectional study, a total of 600 panoram-ic radiographs related to the subjects aged 9-14 years (351 girls and 249 boys) were analyzed. The data were recorded in the related forms, and then analyzed using Chi-square and Exact tests. Among 600 panoramic radiographs, 94 teeth were found to be missi-ng. The most and the least frequent missing teeth were the mandibular second premolars and the maxillary central incisors (observed in only 1 subject), respectively. The most commonly absent teeth were the mandibular second premolars, the maxillary lateral incisors, the mandibular central incisors, and the maxillary second premolars in order of the frequency. This study revealed that the frequency of missing tooth in girls is higher than that in boys. Thus, due to the girl's more aesthetic sensibility and also intricate treatment of such anomaly, accurate and frequent examination of adolescents’ particularly girls’ teeth for on-time diagnosis is crucial.

Statement of Problem: Colonization of Helicobacter pylori (Hp) in the oral cavity may increase in the presence of the periodontal disease. It has been suggested that one of the possible mechanisms of reinfection is the recolonization from dental plaque. The purpose of this study was to determine whether periodontal disease was associated with Hp infection. Sixty-five consecutive patients (34 males and 31 females) undergoing endoscopy for investigation of dyspepsia were included in this descriptive cross-sectional study. The mean age of the patients was 41.3±13.5 years. Periodontal examination and Rapid Urease Test (RUT) were done for all of the participants. Statistical analysis was done, using Chi-square test. 53.8% of the patients had periodontal disease and 61.5% of them had gastric Hp infection. There was no statistically significant association between periodontal disease and gastric Hp infection (p =0.455). This study revealed that the presence of periodontal disease in patients with gastric Hp infection could be an independent status.

Statement of Problem: Head and neck cancers occur in a wide variety of tissue types and sites, resulting in a complex range of malignancies cared by physicians in multiple specialties. Epidemiologic aspects of head and neck cancer in Iran have not been studied adequately. The aim of this study was to represent epidemiological aspects of head and neck cancers in Kerman province in Iran. In this retrospective epidemiological study, a total of 2211 cases of head and neck cancers were diagnosed in period 11-year. Data on all malig-nant head and neck cancers were included in this study. Information was obtained from the records of the 18 departments of histopathology in Kerman province. The five most common sites were skin of the head and neck (46.81%), lymph nodes of head and neck (13.98%), larynx (13.48%), oral cavity and pharynx (12.21%), and thyroid (6.20%). Paranasal sinuses were the least common. The incidence rate of head and neck cancers was 10.12/100000 cases. Geographical or regional variations in the prevalence of head and neck cancer indicate that the socio-cultural lifestyles of a population play an important role in head and neck carcinogenesis. This study showed that the incidence rate of head and neck cancers was lower than that in many other countries. However, comparison between our findings with some other studies shows a relation consistency.

Statement of the Problem: During the recent years, new methods of teaching and learning have been introduced for medical and dental students in addition to the traditional teaching techniques. Computer assisted learning (CAL) program is one of these methods which seem to have promising results. To compare a computer -assisted learning (CAL) program about oral red and white lesions with a print medium of identical content. Fifty senior dental students were randomly assigned in a prospective study to either use the CAL program (n=25) or a pamphlet (n=25). After one week since the educational CDs and pamphlets were distributed, both groups were asked to complete the post-intervention multiple choice questionnaire followed by watching 10 clinical slides on oral red and white lesions for 10 minutes. Chi-square and Mann-Whitney tests were used for data analysis. Students in the CAL program group scored higher (16.64) than those in the pamphlet group (13.44) and this difference (3.2 points or 28%) was statist-ically significant (p <0.05). The difference in test scores was most likely related to the use of the CAL program and it seems to be a promising medium as an adjunct to other traditional tutorial methods.

Statement of Problem: The main aim of advancement genioplasty is soft tissue and hard tissue stability which is important in improvement of the patient's aesthetics. The evaluation of the soft and hard tissue stability in advancement genioplasty was the aim of this study. The subjects in this study were 15 patients who prese-nted with retrognathia. All of the 15 patients underwent advancement geniop-lasty alone to correct retrognathia. The soft and hard tissue pogonion in pre-operation, immediately post-operation, and 18 months after operation in two groups of 9 patients with genial advancement less than 7mm (means 5.22mm) and 6 patients with genial advancement equal or greater than 7mm (means 7.16mm) were assessed. After operation, no patient had infection or dehiscence and bone insta-bility. In group 1 with advancement less than 7mm, hard tissue pogonion relap-se was 0.60±0.66mm and soft tissue pogonion relapse was 1.55±0.46mm. In group 2 with advancement equal or more than 7mm, hard tissue pogonion rela-pse of 1.6±0.46mm and soft tissue pogonion relapse of 1.8±0.68mm were observed. Advancement genioplasty is a predictable operation specially when using rigid fixation. In this study, the result of operation in an 18 month period was stable.