Journal of Research in Dental Sciences
Year:2011 | Volume:8 | Issue:3 (29)|Papers Count:10

Background and Aim: Candidiasis is not only the most common fungal infection of the oral cavity but also a major cause of discoloration and infection in denture wearers. Extensive use of soft liners and candidal adhesion to these materials has been an issue of concern in removable prosthetic treatments. This study was designed to compared the adhesion of candida albicans to two types of soft liners.Materials and Methods: In this experimental and invitro study 12 specimens of Molloplast B and 12 specimens of Acropars soft liners were transferred to tubes containing suspensions of 1´106 of candida albicans. Tubes were then incubated for 40 and 120 minutes. Following incubation, the specimens were suspended in tubes containing 1ml of sterile saline solution and the suspensions were plated in sabouraud dextrose agar. After 24 and 48 hours of incubation, the number of colony-forming units (CFUS) were counted using light microscope and data was analysed by two way ANOVA.Results: The rate of colonization of Candida albicans to soft liner Molloplast B at 40 and 120 min was (2025±509) and (2483±509) respectively and to soft liner Acropars were (2183±498) and (2533±408). Over time, Candidal adhesion was significantly increased in both soft liners (p<0.05), but there was no significant difference between the two types of soft liners.Conclusion: Use of one soft liner has no advantage over the other in terms of candidal adhesion.

Background and Aim: The relationship between periodontal disease and pregnancy complications has been established in numerous previous studies. The aim of this study was to investigate the effect of the phase I periodontal therapy on the prevention of preeclampsia in pregnant women referred to three hospital centers from 2007 to 2008 during year 1386 and 1387.Materials and Methods: For this clinical trial study 40 pregnant women in 20 to 28 week of pregnancy with a history of preeclampsia and moderate to severe periodontal disease were selected. The intervening factors affecting preeclampsia were matched in both groups. The case group included 20 samples who received the phase I periodontal therapy. No treatment was performed in the control group. Both groups were followed up to delivery and observed for incidence of preeclampsia symptoms. The periodontal parameters including plaque index (PLI), pocket depth ) PD) , bleeding on probing (BOP), gingival recession (GR) and clinical attachment level ( CAL) were recorded for all teeth except the wisdom teeth. Preeclampsia was defined as blood pressure over 140.90 mmHg and proteinuria (+1). Data was subjected to Exact Fisher Test for statistical analysis.Results: PD in control and case group was (2.8±1.34) and (2.1±0.53) mm respectively. CAL in control and case group was (2.4±1.65) and (2.1±0.63) mm respectively and the difference was not statistically significant (p=0.2). Two of the samples in case group (10%) and 4 in the control group (20%) revealed preeclampsia symptoms. The difference was not statistically significant (P=0.3).Conclusion: According to this study, the phase I periodontal therapy prevented the incidence of preeclampsia clinically although statistically there was no differences between two groups.

Background and Aim: Conventional oral radiography poses unwanted limitations on proper detection of class III caries. The purpose of this study was to evaluate the accuracy of Digital Subtraction Radiography( DSC) in the diagnosis of class III caries with various depths.Materials and Methods: This diagnostic study assessed the depth of class III caries on 46 extracted intact permanent anterior human teeth. Direct digital radiography of samples were initially obtained under standard conditions, prior to preparation of manual artificial caries (group A). In each tooth, one proximal surface was randomly selected for creation of an artificial cavity using a 008 round diamond bur (RDB). At this stage, secondary radiographic images were obtained from the samples and they were categorized into (group B). The depth of the previously created caries was then increased by two fold using a 009 RDB (group C) and 010 RDB (group D) followed by secondary radiographic images obtained from each group. The presence or absence of caries was assessed by two examiners after obtaining subtraction images. Data analysis was done by SPSS 11.5 using diagnostic tests.Results: Positive predictive value, negative predictive value, sensitivity, specificity and accuracy of group B were 90%, 84%, 83%, 91% and 87%, respectively and that of group C were 96%, 94%, 93%, 96 and 95%, respectively. For group D all the indices were 100% (P<0.001).Conclusion: Digital Subtraction Radiography (DSR) can be used as a specialized and precise method in the diagnosis of class III caries.

Background and Aim: Stress is a major problem with several side effects among dental students. The present study was conducted to evaluate the level of stress, its sources and related factors among senior dental students at Islamic Azad University (IAU) in year 1389.Materials and Methods: This cross-sectional study assessed the level of stress in 230 senior dental students at IAU in year 1389. Sampling method was (census) and to collect data questionnaires were filled. Beck’s questionnaire was used to evaluate the level of stress and BESQ questionnaire evaluated the sources of stress. Data were analyzed by chi-square test.Results: This study revealed that 39% of the students had low level of stress, 16% had moderate level of stress, 8% had severe level of stress and 37% were stress free. The most important sources of stress included completion of requirements and exams. Female students had significantly higher level of stress compared to male students (p<0.05).Senior of second semester had significantly less stress than first semester students (P<0.05). Age, spousal status, residence location, probation history, total GPA and field selection method had no significant effect on stress level.Conclusion: Based on the prevalence of stress and related sources, overall measures aimed at the reduction of stress are recommended for a better educational environment.

Background and Aim: Angulation of implant and attachment in regard to path of insertion of prosthesis would affect the retention and longevity of the overdenture. The purpose of this study was to evaluate the effect of 5 and 10 degree distolabial of implants and attachments on the retention and longevity of the overdenture.Materials and Methods: This in vitro experimental study was conducted on 25 samples, divided into 5 groups. Each group included twin implants and attachments which were placed into acrylic blocks. Parallel implants and attachments comprised the control group (Group 1). The study groups (Group 2-5) consisted of implants and attachments with 5 and 10 degrees of distolabial inclination. All samples were kept wet using artificial saliva. The level of retention was then measured from cycle one to cycle 3000 (equivalent to 750 days of longevity) using the Santam retention test device. Data was analyzed by ANOVA and Paired T-test.Results: The initial retention measured in groups 1-5 was: (3.8±0.34), (5.6±0.66), (6±0.66), (6.8±0.3) and (6.9±0.28) respectively. The reduction in retention after 3000 cycles in group 1-5 was measured to be: (11%), (32%), (31%), (38%) and 36% respectively. Statistical analysis revealed no significant difference between the initial and final retention levels among the case groups (p<0.2). However, there was significant difference between the control and the case groups in terms of retention (p<0.05).Conclusion: Distolabial inclination of the implant results in an initial increase of retention level followed by a reduction of retention level over time. This degree of inclination has no major influence on the longevity of the implant.

Background and Aim: studies show that only 50-70% of composite material is polymerized. A polymerization shrinkage of less than one percent has been reported by the manufacturer for a newly introduced silorane based composite material named filtek P90 (3M ESPE, USA). However, only few independent studies are available regarding degree of conversion (DOC) of this material. The purpose of this study was to evaluate the degree of polymerization in filtek P90 compared to Z250 using deferential scanning calorimetry (DSC).Materials and Methods: In this experimental study10 composite disks ( 5 sample for each group ), 2´3  millimter dimensions, were prepared in stainless steel molds and cured for 20 seconds based on the manufacturer instruction using a LEDTurbo( Apoza, Japan ) with 950 mw/cm2 ray power against a black surface to omit light reflection. Samples were kept in boxes far from sun light, in room temperature before taking the DSC test. The degree of polymerization was evaluated in each group by DSC (Perkin Elmer, Norwalk, CT, USA) device. Obtained data was analyzed By statistical Mann-Whitney Test.Results: Degree of conversion of Filtek p90 composite measured as 62.56±5.12 whereas degree of conversion of Z250 composite was messaged as: 71.65±5.30. Z250 composite had a higher degree of polymerization compared to Filtek p90 composite. There was statistically significant difference between two groups (p<0.05).Conclusion: Composite Z250 has a higher degree of polymerization compared to Filtek P90.

Background and Aim: Inadequate bond strength of resin cements to dentin appears to be a typical cause of failure in retention of fiber posts. The aim of this study was to compare the effect of two self-adhesive resin cements on shear bond strength of fiber post to dentin.Materials and Methods: This in vitro experimental study included 20 mandibular premolars with a single canal. All samples received standardized endodontic treatment after meeting the inclusion criteria. They were randomly divided into two groups and a post space was prepared in each sample. A size two match post RTD fiber post was cemented into each sample using Biscem (Bisco) in group 1 and Maxcem Elite (Kerr) in group 2 as cementing agents. All samples were then cut into two pieces. Each specimen was loaded with equal force using a Universal Testing Machine. The load was applied from the apical to the coronal portion of each sample until fracture occurred. The mean shear bond strength for two each group was recorded and analyzed using statistical T-test method.Results: The mean shear bond strength was found to be 7.3±2.5 for the Biscem (Bisco) group and 6.6±3.2 for the Maxcem Elite (Kerr) Group. There was no significant difference between the two groups.Conclusion: the use of either resin cement has no significant effect on the shear bond strength of the fiber post to dentin.

Background and Aim: Calcifying odontogenic cyst (COC) is an uncommon odontogenic cyst that was first introduced by Gorlin in 1962. Many different terminologies have been applied to cystic and solid variants, but calcifying odontogenic cyst is the preferred term. Little information is available regarding the clinicopathological features of this lesion. The purpose of this study was analysis of clinicopathologic features of COC’s.Materials and Methods: This existing data study assessed clinical characteristics as well as microscopic features of 21 registered cases of COC’s. Information such as age, gender of the patients and location of COCs were obtained from the records and their microscopic slides were reviewed.Results: Most COCs were found in the mandible (81%) and 76.2% of the cases were located in the posterior regions of the lower jaw. All cases had cystic features (100%) and one was reported to be peripheral. 38.1% of the cases occurred in the second decade and 52.4% were seen in females. Eight cases were associated with odontogenic tumors.Conclusion: All lesions were cyctic and over 1.3 of the them were associated with odontogenic tumors. Contrary to other studies, our findings suggest that the lesions are more common in women and are located mostly in the posterior regions of the mandible. Inodepth immunehistochemical as well as histomorphological evaluations are suggested for a better understanding of biological natures of COCs.