Journal of Dental Medicine
Year:2012 | Volume:25 | Issue:1 (70)|Papers Count:11

Dentistry has been a field dominated by a constant improvement of synthetic biomaterials. Tissue engineering of tooth is coming to change the panel of the dental materials such as restorative materials and implants. Certainly, it is the largest transition in history of dental materials science in terms of accepting this new and exciting technology. The objective of this article is to present various implications of tissue engineering in different fields of dentistry. To achieve this goal, a review of the literature was carried out by using Medline database to search topics including “dental stem cells”, “teeth tissue engineering”, “regenerative dentistry”, “oral surgery”, “periodontal regeneration” and “regenerative endodontics”. These searches were limited to articles published after the year 2000. On the basis of our literature review, we have found that although there are significant challenges in oral tissues engineering, engineered tissues will find many applications in dentistry within the next few years.

Background and Aims: Recurrent aphthous stomatitis (RAS) is the most common oral mucosal inflammatory disease. The frequency of RAS is as much as 20% in the general population. The cause of RAS is not yet fully understood. Antioxidant is a material which has ability to preserve molecules from damage and also can delay the start of it. The aim of this study was to compare the saliva level of total antioxidant status (TAS) in RAS patients with that of normal subjects.Materials and Methods: In this case-control study, 25 patients with aphthous stomatitis were considered as the case group and 25 healthy subjects as control group. The case and control groups were matched by sex and age.Total antioxidant status (TAS) saliva levels were measured in two groups by spectrophotometer. The data were analyzed with independent sample t-test.Results: The mean and standard deviation of TAS in case group was 1.64±0.64 mmol/L and in control group was 1.49±0.3 mmol/L. There was not significant difference between case and control groups (P=0.464).Conclusion: Results of this study showed that there was no statistically significant difference between RAS patients and healthy subjects in saliva antioxidant status levels.

Background and Aims: Working length determination and remaining this length is of great importance in root canal therapy. Recently, electronic apex locators are being used to determine working length and decrease the number of radiographs. The purpose of this study was to compare the sensitivity of Root ZX and Novapex electronic apex locators with radiography in an in vivo condition.Materials and Methods: In this study, 73 single-canalled teeth of the patients referred to the endodontic department of the Yazd Dental School were evaluated.The access cavity was prepared and working length of the root canals were measured by using the apex locators: Root ZX and Novapex. The file was placed in the root canal and a periapical radiograph was taken using parallel technique. The working lengths obtained by apex locators were recorded and compared with those of radiographs. The data were analyzed by Pearson' s correlation coefficient, Wilcoxon test and paired t-test.Results: The exact measurement without any fault was 46.6% for Root ZX and 20.5% for Novapex compared to radiography. In the range of 0.5 mm fault, the results were 91.8% for Root ZX and 64.4% for Novapex compared to radiographic measurements. The difference between the average of the measured lengths by Root ZX and radiography was not significant (P=0.17). On the other hand, the results showed significant difference between the average of the measured lengths by Novapex and radiography (P=0.017). The difference between two apex locators was not significant (P=0.061).Conclusion: Root ZX and Novapex with high accuracy are useful for determining working length of the root canals in pregnant patients with special anatomic conditions and patients with muscle disharmony. Therefore, the use of these apex locators combined with radiography is recommended in root canal treatments.

Background and Aims: Radiographic examination is a necessary step in diagnosis of horizontal root fracture.The purpose of this study was to determine the sensitivity and specificity of single radiograph for detection of horizontal root fracture.Materials and Methods: In this analytical-descriptive study, 30 human freshly extracted teeth were used. Using a hammer and clamp, the teeth were divided into two sections accidentally and then sections were attached together by cyanoacrylate glue. Two radiographs were taken; with and without a piece of human mandibular bone.Afterward, radiographs were analyzed by three expert dentists using a slide show device.Results: The diagnostic sensitivity and specificity of single radiograph for detection of horizontal root fracture without bone was 100%, but in radiographs of teeth with bone was 82.7% and 100%, respectively.Conclusion: Based on the results of this study, in most cases, the horizontal root fractures can be detected by a single periapical radiograph.

Background and Aims: When composite resin polymerizes, shrinkage stresses tend to produce gaps at the tooth/ restoration interfaces. Surface sealants may reduce or avoid problems related to the marginal interface. The aim of this study was to evaluate the effect of two different surface sealants (Fortify and Optiguard) on the microleakage of class V resin composite restorations.Materials and Methods: Twenty three sound noncarious molars were collected. Totally, 45 Class V cavities with the occlusal margins in enamel and cervical margins in cementum were prepared in both buccal and lingual surfaces. The specimens were randomly assigned in three groups (15 cavities in each group) and then restored with a resin composite. After the finishing and polishing procedures, the restorations in each group were covered with a specific surface sealant, except for the control samples, which were not sealed. After placing restorations, the specimens were thermocycled and then immersed in a 50% silver nitrate solution (tracer agent) for four hours, sectioned longitudinally and analyzed for leakage using a stereomicroscope in a blind manner. The marginal microleakage was evaluated at the occlusal and cervical interfaces and compared among the three groups using the Kruskall-Wallis and the Mann-Whitney U tests.Results: Microleakage was found in all groups at both occlusal and cervical margins. Significantly greater leakage was observed at the cervical margins compared to the enamel margins of the material groups (P=0.005).There was no statistically significant difference among the groups at occlusal margins (P=0.66). In the cervical region, Fortify showed improved results and statistically presented the lowest degree of microleakage (P=0.003).Conclusion: The used sealant materials presented different rates of effectiveness and Fortify decreased marginal microleakage significantly.

Background and Aims: The aim of the present study was to investigate self-perceived need to learn practice management and self reported knowledge in this regard among dentists.Materials and Methods: A group of five academic staff members of Community Oral Health Department (Tehran Dental School) and four dentists formed an expert panel to develop the content of the course. This group developed a list of topics related to principles of successful dental practice. To investigate the necessity of educating the topics and self-assessed knowledge of the topics, a questionnaire was designed and administered to 55 volunteer dentists. Forty six dentists completed the questionnaire. T-test and Chi-square test were used for statistical analyses.Results: Totally more than two-third of the dentists believed that a huge need exists for education of all the topics.The corresponded figure for such topics as ergonomics and medical emergencies was about 90%. About 80% of the dentists felt that they had a vast knowledge of safety and infection control. On the other hand, 54.3% of them reported weak knowledge regarding professional rules and regulations. Self-reported educational need and knowledge of the dentists did not show significant association with their age, gender, and work experience (P>0.05).Conclusion: The dentists believed in the necessity of educating such topics and evaluated their knowledge as deficient in these areas. This shows the necessity of developing courses on these topics.

Background and Aims: The present study aimed to evaluate the barriers to the production of scientific dental articles in dental schools in Iran based on the opinions of dental postgraduate students.Materials and Methods: A self-administered questionnaire was distributed among postgraduate students of all Iranian dental schools in June 2010. The respondents rated their agreement with eight sentences about what hinder them from producing scientific dental articles based on a 5-grade Likert scale. The data were analyzed using Chi-square test.Results: Totally, 270 filled questionnaires from 14 dental schools were received. Of all respondents, 53% were male, the mean age were 29.6±3.8. About half of the respondents reported at least one published article. Less than half of the respondents reported producing an article from undergraduate thesis; more women than men and more younger than older students (P<0.05). About two-third of the respondents rated absence of an English editing center, no financial incentives, no appropriate environment, and no competency for scientific writing as most prevalent barriers to the production of scientific dental articles.Conclusion: To expand the share of Iran in the production of scientific dental documents, the potential of postgraduate dental students must be regarded and suitable condition for scientific writing must be provided.Specifically, based on the findings of the present study, provision of an English editing facility, establishing financial incentives, and providing the students with appropriate environment and efficient scientific writing education are of utmost importance.

Background and Aims: High level of caries was reported in pre-school children at the national level. Due to importance of focusing on high-risk children, this study was carried out to evaluate an oral health promotion program designed for Ameneh orphan center.Materials and Methods: Two centers were chosen and assigned to intervention (Ameneh orphan center) and comparison (Shobeir orphan center). Dental examination has been carried out using dental mirror and blunt probe under artificial light and dmfs index was recorded. Health promotion program including topical fluoride application after dental treatment as well as power point education session for caregivers was delivered in intervention group. Children in the other center were only received routine dental treatment. Data were analyzed using Mann-Whitney and regression tests.Results: 79 children in the intervention group and 51 children in comparison group were evaluated in the study.The mean age of children in the intervention group was 4.7 (SD=1.6) and in the comparison group was 4.6 (SD=1.2). The dmfs index in the intervention and comparison groups was 6.86±10.23 and 8.75±12.42 (NS), respectively. The mean dmfs after intervention in the intervention group was 7.93±11.21 and in the control group was 9.88±12.51, which showed no significant difference (P>0.05). Comparison in subgroups showed that the mean dmfs in the group received fluoride varnish in addition to complete dental treatment was significantly less than the comparison group (P<0.05). Controlling the effect of baseline caries and age on the outcome variable with regression analysis showed that the effect of baseline caries should be considered when comparing two groups.Conclusion: Oral health promotion programs including topical fluoride application can be used in high-risk groups of children.

Background and Aims: Since impression materials usually contact with saliva, blood, and oral soft tissues, their microbial contamination are harmful in immunocompromised patients. The aim of the present study was to determine the bacterial and fungal contamination in common impression materials.Materials and Methods: In current lab trial study, 5 different samples from each 4 impression materials were homogenized in 1 ml Tween 80 and then 100ml of each sample were cultured onto blood agar, EMB, or sabouraud dextrose agar. Bacterial and fungal cultures were incubated at 37o C and 30o C, respectively. The isolated bacterial and fungal colonies were enumerated and identified using specific diagnostic media and tests. Data were analyzed using Kruskal-Wallis test.Results: Totally 75% of samples had one or several bacterial contaminations. Iranian alginate and Speedex (putty) were the most contaminated samples. On the other hand, Speedex (light body) and foreign alginate showed lower contamination. Species of Micrococcus, Staphylococcus, Bacilluses, Corynebacteria, gram negative Citrobacter, Actinomycetes and Neisseria were isolated from the analyzed impression materials. Aspergillus, Penicillium, Alternaria, Cladosporium and Sepdonium were the fungi isolated from impression materials. Statistical significant difference was shown between bacterial contamination of Iranian and foreign alginates (P=0.001). There was no statistical significant differences between the bacterial and fungal isolated colonies (CFU/gr) of 4 tested impression materials (P=0.21).Conclusion: Several opportunistic bacteria and fungi were isolated from impression materials especially from Iranian alginate and Speedex putty which indicated their contamination.

Background and Aims: Since a large marginal opening allows more plaque accumulation, gingival sulcular fluid flow and bone loss, microleakage, recurrent caries and periodontal disease, marginal fit is of great importance in fixed restorations. The aim of this study was to compare the marginal fit of zirconium-based all ceramic (Cercon) frameworks, made by two different approaches (Direct and Wax-up scanning).Materials and Methods: An abutment analog, with 5.5 mm width and height, was selected as an experimental model. Twenty all ceramic cores were made for this model (10 specimens per each group). In the first group (Direct), experimental models were scanned directly using Computer Aided Design/Computer Aided Manufacturing (CAD/CAM). The core was then designed with the aid of a computer and machined. In the second group (Wax-up or CAM) a wax-up pattern was made on the experimental model and then scanned and milled from Cercon blocks. The marginal discrepancy of each specimen was recorded using a stereomicroscope (SZX9, Olympus, Japan) and digital camera (Mode TK, C1380E, JVC, Japan) and then measured by Adobe Photoshop CS software. The data were analyzed using T-test.Results: Mean marginal discrepancy of Direct group (85.2±3.95 mm) was significantly less than that of Wax-up group (120.2±6.91 mm).Conclusion: Improved marginal fit of zirconia ceramics was found with the direct model scanning compared with that of Wax-up scanning using CAD/CAM.