مجله تحقیق در علوم دندانپزشکی
سال دوازدهم شماره 2 (پیاپی 44، تابستان 1394)

Mineral Trioxide Aggregate (MTA) is a material used in many endodontic treatments. Recently a number of studies have reported that Portland Cement (PC) and Pro Root MTA have similar physical, chemical and biological properties. The question is wether the cytotoxity of PC is similar to MTA or it would be a toxic agent? The aim of this study was to compare the cytoxicity of Pro Root MTA and Portland Cement on L929 mouse fibroblasts. In this experimental study, extracts materials of PC and Pro Root MTA were transferred to cell culture plates containing L929 fibroblasts at mixing time (0), 4, 24 hours and 7 days after setting. Distilled water set as positive control group and cell culture mediums set as negative control group were added to cell culture plates containing L929 fibroblasts. After 24 hours incubation, cells were stained by Crystal Violet (CV), and optical density (OD) was read. Data were analyzed using Tukey HSD and one way analysis of variance. P≤0.05 was considered as the level of significance. Pro Root MTA in all experimental groups and PC at 0, 4 hours after mixing had statistical significant difference with positive control group (P≤ 0.001) and no significant difference were found between PC, MTA and negative control group in these times. PC showed statistical significant difference with negative control group, positive control group and Pro root MTA at 24 hours and 7 days after mixing. (P≤0.05) based on the findings of this study PC showed some degrees of cytotoxicity at 24 hours and 7 days after mixing.

Polymerization shrinkage and microleakage would be the noteable concern in dentistry. Several methods have been proposed to overcome the negative effects of the polymerization shrinkage such as using a thin layer of flowable composite beneath composite restorations. The aim of this study was to evaluate the effect of curing flowable composite lining on microleakage in class II hybride composite restorations.

In this in vitro study, 60 class II cavities were prepared on 30 extracted human third molars. The teeth were randomly assigned to 3 groups. Group1: cavity preparation were lined with flowable composite (Filtek flow, 3M ESPE, USA) to about 1 mm occlusogingival thickness and cured for 20 seconds. Remaining cavity was filled with hybrid composite incrementally. Group 2: flowable and hybrid composite were cured simultaneously. Group3: cavity preparations were restored with hybrid composite alone without any application of flowable composite. All samples were subsequently immersed in 2% fuschin solution and sectioned and observed under a stereomicroscope. The significance of data between the groups was determined using kruskal wallis and mann-whitney tests (p˂ 0.05).

There was no significant difference between the samples with separate curing of flowable composite and control group. The microleakage significantly decreased in the group which flowable composite and hybrid composite were cured simultaneously (P< 0.05). No significant differences were seen between the samples which flowable composite was cured seperately and control group(p=0.43).

according to this study, curing the flowable and hybrid composite together can decrease the microleakage in class II composite restorations.

Back ground &

Post and core requires removal of a portion of the gutta-percha from the root canal space. When gutta- percha is removed some factors may have a negative effect on obturating material seal. the purpose of this study compare different methods of gutta percha removal immediately after obturation on apical leakage.

Samples randomly divided into 4 experimental groups (N=15) and two positive & negative control groups (n =5). In group 1 post space were prepared immediately with counter clock wise rotating GG. In group 2 post space were prepared immediately with clock wise rotating GG. In group 3post space were prepared immediately with post space bur. In group 4 post space were prepared immediately with heat carrier. Leakage was measured by using bovin serum albumin, immediately٬ 48 hours and 1 week after obturation. The mean of apical microleakage is evaluated by ANOVA & Post Hoc statistial analysis in each group & in different times.

Heat carrier group showed significantly less leakage than Other groups in all intervals (p< 0/05). Then, revers rotating GG showed less leakage and forward rotating GG showed the greatest leakage. The difference between these two groups was significant at immediate and 48 hours after obturation. Post space bur showed more leakage than reverse rotating GG but less leakage than forward rotating GG. This difference was not significant in all intervals (p>0/05).

According to this study heat carrier technique recommended for immediate post space preparation.

Dimensional changes of the impression materials after disinfection is a serious problem in dentistry which could fail the treatment. The aim of this study is to determine the effect of three disinfectants:2% Deconex,5.25% sodium hypochlorite and Nanosil D2, on dimensional changes of Bayer Alginate.

This experimental study was conducted on 32 impressions were taken from one model. The impressions were divided in to four groups: one group was consireded as the control and the other three case groups were disinfected with the mentioned materials. After disinfection and pouring the casts, measurement was done in different dimensions using Electronic Digital Caliper. The acquired data were analyzed with One Way ANOVA test.

Dimensional changes of Bayer Alginate after disinfection with two mentioned disinfectants 5.25%Sodium Hypochlorite and Nanosil D2 was significant but they were within standard limit. (P.value<0.05)but about 2%Deconex, P.value was not significant.(P.value>0.05)

Evaluating the results showed that 2%Deconex caused less dimensional changes in comparision to 5.25%Sodium Hypochlorite and Nanosil D2 statistically. However percentage dimensional changes of three materials were in standard limit of alginate dimensional changes. Each of them can be used to disinfecting alginate by immersion technique.

Author(s): Several studies have shown a higher success rate of root canal therapy when the canal is free from bacteria at the time of obturation. In vitro studies have indicated that calcium hydroxide is the most effective antimicrobial intracanal medicaments. The aim of this study was to assess the efficacy of some different calcium hydroxide preparation and a new method. For conducting this experimental study, 62 root specimens were used. Segments of root with 5 height and almost 5 mm diameter prepared. The specimens were devided into five groups, according to intracanal medicament used as follows: Calcium hydroxide with Normal saline, Lidocaine 2%, Chlorhexidine %2, Chlorhexidine 0/2%, Iodine Potassium Iodide(IKI) 2%. The medicaments were placed into the canal in creamy consistency, then the specimens were taken in the agar culture plates which contains Entrococcus faecalis. The inhibition zone around each specimen was recorded after 24 hours and result submitted to ANOVA and Tukey’s tests. All calcium hydroxide pastes had some degree of antibacterial activity after 24 hours, but combination of calcium hydroxide with chlorhexidine 2% had significantly more efficacy than the other combinations except lidocaine %2 (P< 0.05). Under condition of this study, it can be concluded that addition of chlorhexidine 2% to Calcium hydroxide may improve its antibacterial activity.

The presence of bacterial biofilms containing periopathogenic bacteria species on tooth surface is the main cause of gingivitis and periodontitis, and mechanical removal of the biofilm as a base of periodontal therapies is not enough in most cases. Today, the role of inflammatory mediators has been demonstrated in innate and acquired immunity in periodontitis. Thus, the aim of this study was to compare the effects of photodynamic therapy as adjunctive treatment of inflammatory mediators levels in gingival crevicular fluid and clinical periodontal status. In this clinical trial study,a sample size of 12 patients, aging from 30 to 60 years old with chronic generalized periodontitis and at least with 4 sites with pocket depths of 4-6 mm were selected. In each patient, two quadrants were selected as studies quadrants. Then, the clinical parameters (BOP, PD, CAL) were recorded in all studied quadrant teeth, and the GCF samples were collected for measurement of inflammatory mediators. After performing phase I periodontal treatment in both two groups, a quadrant was selected as the control; another quadrant was treated by PDT following 6 weeks after the treatment, these parameters were recorded again, and after analysis of GCF samples with an ELISAReader device, the information was recorded. Data analysis and comparison was done using statistical tests of Mc Nemar, Fisher’s exact, Independent & paired t-test. The research was conducted on a total of 24 quadrants. The initial level of TNF-a and periodontal clinical parameters were similar. (P<0.4) TNF-a level changes in the control group and experimental group was 0.68 ± 0.22 and 1.74 ± 1 respectively, which rate of decrease in the experimental group was 2.5 times than control group. (P<0.002) TNF-α level and other indicators of periodontal parameters was reduced in both groups. (P<0.01) And that's the extent of periodontal index changes in the experimental group was better than control, but this difference was not statistically significant. (P<0.2) According to the results, 1% Sodium hypochlorite had the highest inhibitory effect on Enterococcus faecalis, while 100 mg/ml concentration of Zataria multiflora essential oil had the highest inhibitory effect on Candida albicans.

Changing the microhardness of enamel after using the materials is one of the most concerns on the dentists. Many researches were performed regarding the comparison of different bleaching materials but it seems that there is no information about OTC bleaching yet. The aim of this research was to compare the effect of three bleaching materials on the microhardness of enamel. In this research, 45 human third molar were divided in three groups. The microhardness of enamel of each sample was calculated by Vickers. Afterwards the samples of each group were treated with the determined bleaching material as per the instruction of the manufacturing company. In the next step, the microhardness of samples was measured again in order to studying the effect of the bleaching materials. Finally the data were analyzed by using the Repeated Measure ANOVA LSD tests. The treated samples with Paint on and White strip bleaching materials and Toothpaste have 16±4, 10±3 and 3±4 decreases in microhardness. The microhardness of all groups was decreased significantly after bleaching (P <0. 001). Mutual Comparison of evaluated groups of this research showed the similar negative effect of Paint on and White strip bleaching materials (P =0. 001), the effect of White strip and Paint on were evaluated more than the toothpaste (P<0.001). The three materials used in this research decreased the microhardness of enamel. The toothpaste has less effect on microhardness of enamel than the paint on and White strip bleaching materials.

Regarding the serious problems of RPDs(removable partiale denture) on oral soft and hard tissues and the importance of preventing them, this study was aimed to evaluate the Effect of verbal and pamphlet technique instructions in oral hygiene education on periodontal status of removable partiale denture wearers.

In this study, 30 subjects with removable partial dentures were evaluated. The patients were divided into 3 groups; Group 1: patients that are hygiene Educated by student. Group 2: the patients that learning oral brushing, flossing and administration of chlorhexidine in addition to group 1 educations and group 3 recieved educational pamphlet. The patients were examined after 3 months to assess the impact of hygiene education on clinical GI, PD, PI, CAL, GBI. The Repeated Measure ANOVA, Kruskal-Wallis and Wilcoxone test used to comparing periodontal status.

After the 3-mounth follow-up periods, the Significant differences in PI, GBI, PD and GI were observed in groups of 2 and 3versus group1 (P<0.005). There were no significant differences between group 2 and 3.(P>0.05)

Considering to the results of this study, it seems that verbal and pamphlet technique instructions are effective methods to reduce periodontal disease in partiale denture wearers.

Author(s): Ameloblastoma is the most common epithelial odontogenic tumor after odontoma in oral and maxillofacial region with invasive and benign histopathologic appearance but clinical behavior, Clinicopathologic variant, location, age, sex and availability to close long-term follow up of patient must be assessed before deciding treatment. The aim of this study was to report a case of ameloblastoma which was treated with conservative approach. The patient was a 16 years old girl who was attended with intraoral swelling in right mandible area. The covering mucosa was intact and displacement of the right premolars was present. In radiographic examination, a poorly demarcated multilocular radiolucent lesion was observed accompanied by impact severly displaced third molar. The aspiration result was negative and incisional biopsy of tumor was resulted in pathology report of plexiform Ameloblastoma. The lesion was approached with enucleation and currattege, the pathologic reports of margins were free of tumor. 6 month follow up was resulted in no presence of the lesion. 3 Implants were applied for reconstruction of premolars. After 2 years, the patient general health was acceptable and implants was considered in suitable condition. It seems, conservative approach of Ameloblastoma may be effective in young patints with free margins and close follow up; so it can be reduced the complications of extensive and redical treatments.