مجله تحقیق در علوم دندانپزشکی
سال دهم شماره 3 (پیاپی 37، پاییز 1392)

Denture stomatitis results from colonization of oral Candida on the surface of denture acrylic base. To control this infection،Candida biofilm formation must be prevented using mechanical and chemical decontamination. The purpose of the present study was to evaluate the effect of Amylase، Papaein and Pepsin solutions on removal of Candida Albicans plaques formed on acrylic resin plates. In this experimental study Candida biofilm was formed on 220 acrylic resin plaques. The average attached Candida cells on 20 randomly selected plates were determined by staining of the plates with Crystal violet and observing them under an optical microscope. 200 contaminated plates were then randomly divided into 4 groups of 50، immersed in 100µg/ml Amylase، Pepsin، and Papain enzyme solutions as test groups، as well as sterile distilled water as negative control group. They were kept in solutions for 8 hours in room temperature. The mean attached Candida cells were determined and data was analyzed using ANOVA and T- test using SPSS software. The average Candida cells attached on to acrylic resin plates on each visual field after decontamintion with Papain solutions was 2. 39±0. 76، Pepsin 7. 14±1. 47 followed by Amylase 8. 22±1. 29، but it was 9. 66±1. 54 in negative control group. The results showed significant differences (P=0. 001). Papain enzyme cleaned 78. 9% of attached Candida cells on acrylic resin plates، whereas Amylase showed minimum antimicrobial properties by removing only 27. 4% of attached Candida cells. Papain solution has maximum effect on removal of Candida from acrylic resin plates

previous studies have reported the benefits of probiotic dairy products on oral microbiota. To this date، no study has been conducted on the effects of these products on salivary pH. It’s clear that the salivary pH plays an important role in the initiation of tooth demineralization processes. This study was done to evaluate the effect of probiotic yoghurt on the salivary pH of orthodontic patients. This cross over، double blind، clinical trial study was done on 20 orthodontic patients referred to a private office in Tehran 3 months into their of orthodontic treatment. The patients’ salivary pH was measured at the beginning of the study. The patients were randomly assigned to 2 groups. The first group consumed the A (probiotic) yoghurt and the second group consumed the B (non probiotic) yoghurt for 2 weeks. After 6 weeks of wash out period، the patients consumed the yoghurt for another 2 weeks. The measurement for Salivary pH was taken at the beginning as well as the end of both 2 week periods of yoghurt consumption. Results were compared by repeated measured ANOVA. The salivary pH before and after consumption of probiotic yogurt was 6. 79±0. 32 and 7. 08±0. 39 respectively (p<0. 05). In non probiotic group the pH before and after consumption was 6. 86±0. 35 and 6. 88±0. 36. Comparison of the results indicated that probiotic yogurt can cause an increase in the salivary pH while non probiotic yogurt had no effect on the salivary pH. Consumption of probiotic yogurt would be a simple and practical method for salivary pH elevation and providing a suitable condition for remineralization of tooth mineral structures.

Adhesion of S. mutans to the dental porcelain surface is may lead to development of gingival inflammation and secondary caries. Surface roughness is considered to be a factor affecting the bacterial adhesion to the porcelain. The purpose of this study was to evaluate the effect of four different surface treatment methods on the adhesion of S. mutans to dental porcelains. Sixty specimens (10×3 mm) of Noritake porcelain were fabricated. Specimens were divided into 4 groups (n=15) that were treated with one of the following four surface finishing techniques: 1. glazing 2. overglazing 3. polishing (with Kenda kit) 4. nonglazed (without any surface treatment). The samples were exposed to bacterial suspension (1x106 cell/ml) with standard code of S. mutans PTCC1643، and were cultured in blood agar. The level of adhesion of the S. mutans on specimens was assessed and the specimen’s surface roughness were determined with SEM. Data was analyzed with one-way Kruskal-Wallis and Mann-whitney test and the correlation between the level of adhesion and specimens surface roughness was evaluated by pearson test. The average bacterial adhesion in each group was as follows: Glazed group (35±20. 92)، Overglazed group (28±6. 73)، Polished group (103±22. 1)، Nonglazed group (115±16. 2). There difference in 4 groups was statistically significant (p<0. 05). The average surface roughness in each group was found to be as follows: Glazed group (0. 67±0. 004)، Overglazed group (0. 48±0. 003)، Nonglazed (0. 89±0. 005)، and Polished (1. 7±0. 004). Statistically significant differences were seen between all groups. (p<0. 0001) There was a positive correlation between the adhesion of S. mutans and surface roughness. (p=0. 0001) This in vitro study indicates that the samples in the Overglazed group had the lowest bacterial adhesion whereas the Nonglazed group had the maximum bacterial adhesion. Furthermore، the Glazed surfaces show less adhesion than the Polished surfaces.

Increased enamel surface roughness is a problem associated with bleaching of teeth. Bleaching treatment can also result in unwanted side effects such as decreased enamel microhardness، increased staining and greater caries vulnerability. The aim of this study was to evaluate the enamel surface roughness exposed to white strip bleaching and a home bleaching system. In this Experimental study، 30 enamel blocks obtained from 15 newly extracted human third molars were divided into two groups The samples were exposed to bleaching agents for 14 (group 1) and 21 (group 2) days، twice a day for 30 minutes. Group one received Day White ACP (9. 5% H2O2) and group 2 was exposed to Crest White Strip supreme (14% H2O2). The surface roughness of each specimen was analyzed initially and after treatment with a profile meter. The paired sample t - test was used for data comparison before and after in each group and independent sample t test was used for data comparing between two groups. Surface roughness in white strip group and home bleaching were 4. 06±1. 42 and 3. 3 ±0. 73 respectively which indicated an increase in comparison to baseline figures: 2. 22 ± 0. 67 and 3. 01±0. 16. The increase in surface roughness was significant within in each group. (p<0. 05). However، no significant difference existed between the two groups and bleaching agents. (p>0. 05) The results confirm that enamel surface roughness increases after bleaching and there is not any difference between two groups.

Calcium hydroxide paste has been used extensively in combination with different vehicles within the root canal. The aim of this study was to determine the pH changes in the root surface dentin after placement of two calcium hydroxide formulation into the root canal. To conduct this experimental study، 33 extracted human teeth with single-root were cleaned and shaped by standard step back technique. Three cavities with the depth of 0. 75 mm and diameter of 1. 5 mm were prepared in cervical، middle and apical area of the facial surface of the roots. The teeth were then divided into 3 groups randomly. The canals of the first group (A) were filled with creamy mixture of calcium hydroxide and normal saline، the second group (B) were filled with creamy mixture of calcium hydroxide and 2% chlorhexidine using lentulo spiral drills. In group (C) the canals were left empty as the negative control. The pH in different areas were measured at 1، 3، 7، 14 days. The results were analyzed with the repeated measured ANOVA test. Based on our findings، the pH value in normal saline group was significantly higher at all times compared to other groups (p<0. 001). The maximum average pH value (9. 9± 0. 5) was found to be in group (A) on the third day and in the apical area. In the group (B) the maximum average pH value on the third day in the apical area was 8. 7± 0. 3. Little changes of pH value at the root surface dentin، could be due to failure of hydroxyl ions to penetrate into the dentin tubules. Furthermore، to achieve a higher pH value at the dentinal surface، it is preferential to use normal saline as a vehicle for calcium hydroxide rather than materials with acidic pH

Very little is known about the fracture resistance of endodontically treated teeth restored with different design of esthetic post systems. The aim of this study was to compare the fracture resistance and failure mode of endodontically treated teeth restored with two different types of quartz fiber post. In this experimental، in-vitro study، twenty mandibular premolars with similar size were chosen and randomly divided into 2 groups (n=10). After cutting the crowns and endodontic therapy، the teeth were restored with a quartz fiber single taper light-posts in group A and quartz fiber D. T light-post in group B. All posts were cemented with a dual cure cement. Composite resin cores were built up using a pre-formed polyester matrix and every specimen was embedded in an acrylic resin block with a layer of elastic polyether Impergum surrounding the roots as PDL. Compressive load was applied at 135 degree angle to the long axis of the tooth at a crosshead speed of 1mm/min until fracture occurred. T-test was used to determine the significance of the failure load values between the two groups. There was no significant statistical difference in fracture resistance among two groups. The fracture load in groups A and B were 366. 7±102. 7 (N) and 382. 4 ±67. 3 (N) respectively. (P<0. 6) According to the findings of this study، two different designs of quartz fiber posts did not influence the fracture resistance of endodontically treated teeth.

Due to the limitations of conventional radiography in the diagnosis of secondary caries. The purpose of this study was to assess the efficacy of Digital Subtraction Radiography in detection of secondary caries.

This Diagnostic in-vitro study was conducted on 40 healthy permanent molars stored in 10% formalin solution. Eighty standard CL. II cavities were prepared on mesial and distal surfaces of sample teeth and were restored using amalgam restorations. Teeth were fixed in XCP Film holder with Putty and initial digital images were taken of each tooth and were stored in a memory device. Cavities for secondary caries were created in gingival walls of each tooth by a no. 1 round bur to a depth of 1 mm. and were restored by red wax. The images are reviewed by experts and the results were analyzed of using statistical analysis software SPSS (16).

The positive predictive value (PPV) and negative predictive vale (NPV)، sensitivity and specificity،in the mesial surface were 71. 6%،75. 4%، 69. 6% and 77. 2% respectively and 77%، 87%، 86%، 79. 4% in the distal surface. The diagnostic error rate in the mesial surface (26. 2%) was higher compared to the distal surface. (17. 4%)، The difference was is statistically significant. (p <0/001)

The results of this study showed that DSR can be useful in the evaluation of secondary caries.

An important step before establishing CBCT as a common orthodontic diagnostic approach is to assess landmark reliability. The purpose of the present study was to evaluate intra- and inter observer reliability in 3D landmark identification using CBCT images.

A total of 30 CBCT images were selected for this experimental study. Working independently، two observers identified 14 landmarks، twice in the CBCT images. Selecting the most appropriate slice in the axial، coronal، and sagittal views، the position of the landmark was recorded in millimeters for the X، Y، and Z coordinates respectively. Intra- and inter observer reliability values were determined using Pearson’s correlation test.

The Intra class correlation (ICC) was >0. 7 for 97. 6% of intra observer assessments and 92. 8% of inter observer assessments. None of the ICCs were <0. 6. The ICC was ≥0. 9 for 25 (59. 5%) of the intra observer assessments. The ICC was ≥0. 9 for 28 (66. 67%) of the inter observer assessments. The mean differences between the two observers in 95. 2% of the cases were less than 2 millimeters.

Considering the limitations and the results of the present study، the intra- and inter observer reliability was high. With proper training of the operator، the three-dimensional landmark identification using CBCT can offer consistent and reproducible data.

The prevalance of periodontal disease is escalating among the elderly population and there are major information gaps in the region regarding this issue. This study was designed to determine the periodontal status and its related factors in elderly residents of nursing homes supervised by Behzisty organization in Tehran in year 2011. This cross-sectional study was conducted in all nursing homes in Tehran. The elderly with following criteria were evaluated: minimum one tooth، no mental disease and no need for prophylactic antibiotic therapy. The plaque index، calculus index، bleeding on probing (BOP)، clinical attachment loss (CAL) and probing depth were evaluate. Related factors including: age، sex، education، smoking، history of periodontal treatment، duration of residency in nursing home، occupation، bailsman’s occupation، were assessed. The prevalence and severity of periodontal disease were determined and the Fisher exact test was utilized to evaluate the role of the related factors. A total of 607subjects were evaluated، of which، 137 had the inclusion criteria of our study. 58 (42. 3 %) were female and 79 (57. 6 %) were male. The mean age was 64. 3 ±1. 8 and 7subjects (5. 1%) didn’t have periodontal disease. Our results indicated that 18. 9% had mild periodontitis، 44. 5% had moderate periodontitis and 31. 41% had sever periodontitis. Low education، smoking and not brushing، aging over 66 y and were significant factors in subjects with periodontal disease. (p<0. 001) High prevalence of periodontal disease in the elderly population of nursing homes located in Tehran indicates the necessity for treatment measures. It should be a priority for the Behzisty Organization to not only create treatment facilities but to provide for such imperative measures as well.

In rural areas of Iran، Family physicians are the primary care professionals in whom patients seek treatment for their medical issues as well as oral lesions. The aim of this study was to evaluate medical students'' skill in diagnosis and treatment of oral mucosal lesions. In Ahvaz Jondishapoor university of medical sciences in 2012. This descriptive study was conducted on Eighty medical interns that selected and asked to complete the study questionnaire. The questionnaire consisted of 18 questions validated by using other similar valid studies. Five experts in the field of oral disease assessed the reliability of the questionnaire. Data were was analyzed using SPSS software. 42. 5% of interns were male and 57. 5 % were female ranging from24 to 26 years of age. The mean score for diagnostic skills was 3. 97 ± 0. 25 in male interns and 3. 83 ± 0. 16 in female participants. The mean score for skills relating to treatment approach in male and female interns was 1. 94 ± 0. 17 and 1. 96±0. 13 respectively. There was no statistically significant difference between the male and female subjects in terms of qualities such as diagnostic skills or treatment approach pertaining to oral diseases. (p = 0. 23) Medical students do not possess proper knowledge and skills required for treatment of patients with oral mucosal lesions. Therefore، proper educational proceedings pertaining to the diagnosis and treatment of oral diseases should be considered for medical students. Educational authorities also need to be informed in this regard.