Journal of Dental Medicine

  Background and Aims: Oral health prepares us for daily activities without discomfort, and dissatisfaction. In this research, agreement level between parents and children aged 11-14 year-old in reporting child oral health-related quality of life was studied in Isfahan city.

  Materials and Methods: In this descriptive, analytical and cross-sectional study 128 pairs of parents and children aged 11-14 were selected with random sampling technique from schools in Isfahan and were asked to complete the relevant questionnaires. The questionnaires evaluated quality of life in four fields of oral signs, functional deficits and emotional and social health. In order to evaluate child-parent agreement, intra-correlation coefficient (ICC), Pearson’s correlation coefficient, Spearman’s correlation coefficient and intra-class correlation coefficient (ICC) were used (α=0.05).

  Results: The agreements between PPQ_11-14 (parent perception questionnaire), CPQ_11-14 (child perception questionnaire) and the related fields were 0.81, -0.67. The highest agreement level (ICC=0.83) was related to emotional health (excellent), followed by functional deficits (ICC=0.80), social health (ICC=0.69) and oral signs (ICC=0.64). Pearson's test showed significant correlations between CPQ_11-14 and PPQ_11-14 (r=0.81) (P<0.01).

  Conclusion: Although parents, especially mothers, may be used as proxies for their children in relation to quality of life and related fields, the views of both should be obtained in order to fully represent child oral health-related quality of life issues.

  Background and Aims: Bleaching agents not only affect the tooth structure, but also may alter the properties of restorative materials. The aim of this in vitro study was to evaluate the effect of different bleaching regimens on the microhardness of four tooth-colored restorative materials.

  Materials and Methods: Eighty specimens of four restorative materials (Microhybrid resin composite (Z250 (3M, ESPE), nanohybrid composite Z350 (3M, ESPE), packable composite P60 (3M, ESPE), and resin modified glass ionomer Vitremer (3M, ESPE)) were fabricated and were polished after 24 h with Soflex discs (3M,ESPE). Then the specimens were divided into two groups: In office bleach group, 40 specimens (10 of each restorative material) were bleached with hydrogen peroxide 37.5% for 30 min in two sessions with 7 days interval. In home bleaching group, 40 specimens were bleached with carbamid peroxide 22%, 6 h a day for 14 days. Vickers microhardness test were done before and after bleaching (baseline). Finally data were evaluated using analysis of Variance.

  Results: Two bleaching regimens were significantly decreased the microhardness values. In Z250 resin composite, the microhardness values before and after bleaching were 95.30 and 92.67 kg/mm², respectively. for office bleaching (P=0.011) and 95.38 and 92.39 kg/mm² for home bleaching (P<0.001). In Z350 resin composite, the microhardness values before and after bleaching were 98.29 and 92.41 kg/mm², for office bleaching (P<0.001) and 97.35 and 93.44 kg/mm² for home bleaching (P<0.001) respectively. In P60 resin composite, the microhardness values before and after bleaching were 103.10 and 96.16 kg/mm², respectively. for office bleaching (P=0.045) and 102.61 and 98.16 kg/mm² for home bleaching (P=0.001). In resin modified glass ionomer (Vitremer), the microhardness values before and after bleaching were 56.79 and 49.41 kg/mm², respectively. for office bleaching (P=0.004) and 54.17 and 46.50 kg/mm² for home bleaching (P<0.001). There was no significant difference between two bleaching agents (P=0.365).

  Conclusion: Dental bleaching agents decrease the microhardness of tooth-colored restorative materials.

  Background and Aims: Successful root canal therapy requires knowledge of tooth anatomy and root canal morphology. For permanent mandibular premolars, great variety in size, shape and number of roots and root fusion expression has been reported in the literature. There is a wide variety of methods used in studies for evaluating the root canal morphology. One of these methods is Cone-beam Computed tomography (CBCT) that reduces the limitations of two-dimensional X-ray imaging, with less exposure in comparison with other 3D radiographies. Thus, this study was designed to evaluate the differences in the root and canal morphology of permanent mandibular premolars in an Iranian population by means of CBCT images.

  Materials and Methods: We searched a database of CBCT scans and evaluated 400 (20-60 years old) patients who met the inclusion criteria and teeth in this images (CBCT) were evaluated in three dimensions (Axial, Coronal and Sagital). Tooth length, number of roots, number of canals, canal type, root curvature and the effect of gender on any of the items mentioned were evaluated. Data were analyzed using T-test.

  Results: The average length of the first premolar of mandibular was 22.27 mm and second premolar was 22.28 mm. 98.4% of the first premolar and 98.2% of the second premolar were single root., and 87.3% and 93.1% were single channel. The incidence of number of canals based on vertochy divisions were:type 1: 90.7% and 90.8%, type 0: 2.2% and 2.8%, type 4: 3.3% and 3.1%, type 6: 1.4% and 2.1% and type 3: 2.5% and 1.5% respectively. In any case, there was no significant difference between males and females (P<0.001).

  Conclusion: Results indicate that dentists can obtain valuable information about the anatomy and morphology of the root canals using CBCT.

  Background and Aims: Metallic nano-particles show exclusive biological, chemical and physical characteristic. The purpose of this research was to evaluate the effect of various amounts of nanosilver incorporation (0 (as control), 20, 40, 80, 120, 200 ppm) on the mechanical Properties ( compressive and flexural strength) of resin modified Glass ionomer Cement.

  Materials and Methods: Based on ISO 4049 and ISO 9971 for polyalkenoid cements, 90 cases in each group were prepared for the flexural and compressive strength. Specimens in 6 groups with different amounts of nanosilver (20, 40, 80, 120 and 200 ppm) and control (Fuji II LC improved), stored in distilled water at 37 ° C for 1 day and 30 days. Flexural strength, using a three-point bending method, Modulus of elasticity and the compressive strength were measured by universal testing machine (Zwick) with crosshead speed of 0.5 mm/min. Data were analyzed using two-way ANOVA and Tukey post HOC test.

  Results: The flexural strength and modulus of various amounts of nanosilver incorporation of resin modified glass-ionomer cement were not significantly different (P>0.05). The compressive strength of incorporating of
20 ppm compared with control (P=0.01), 40 ppm (P=0.02) and 80 ppm compared with control (P<0.001) were increased. The flexural strength and compressive strength of Fuji II LC, containing nanosilver particles were increased after 1 day and 1 month significantly (P<0.001).

  Conclusion: Incorporation of 20 to 80 ppm nanosilver into Fuji II LC had increased mechanical properties compared to the original cement.

  Background and Aims: Iatrogenic damage to adjacent tooth during proximal cavity preparation is one of the most common side effects in operative dentistry. The aim of this study was to determine prevalence of iatrogenic damages to adjacent tooth during the preparation of proximal Class II cavities among undergraduate students at dental faculty of Tehran University of Medical Sciences in 2010 .

  Materials and Methods: 106 posterior permanent teeth which had Class II decay with sound proximal surfaces of adjacent teeth were selected and restored by dental students awarding the aims of the present study. After finishing restoration, proximal surfaces were completely dried by air and evaluated with dental chair light. In doubtful cases, surfaces were evaluated with × 3 magnification. Damages were classified into 2 groups abrasion and groove. Data were analyzed using Fishers exact and Pearson chi square tests .

  Results: The frequency of adjacent surfaces damage were 57.5%, with 31.1% damages as abrasion and 26.4% as groove. Students who used matrix band and wedge in proximal area as preventive instruments showed 53.4% damages and other students showed 57.3% damages (P>0.05). A significantly higher number of females and students at restorative course level (3) used wedge and matrix band than males and students at restorative course level (4) for protecting adjacent teeth (P<0.05).

  Conclusion: According to the high percentage of iatrogenic damages on adjacent sound teeth in class II cavity preparation, teaching of preventive methods and using proper techniques is necessary for dental students as future dentists.

  Background and Aims: One of the important aspects for evaluating an organization is assessing the level of satisfaction of the clients. This study was conducted to compare the level of satisfaction between traditional and new methods of delivering dental care in the clinic of Tehran University of Medical Sciences.

  Materials and Methods: A cross-sectional study was conducted on 308 patients received dental care at the dental clinics of Tehran University of Medical Sciences in spring 2010. Data were collected from Comprehensive Care Unit (CCU) in addition to 7 isolated clinics including restorative, periodontics, endodontics, radiology, and prosthodontics (fix and removable) using translated version of the Dental Satisfaction Questionnaire (DSQ), consisted of 19 questions in three main domains in addition to demographic questions. Descriptive statistics was used as percentage of answers. In order to compare the mean score between domains ANOVA test was used.

  Results: The standardized mean scores in each domain were: pain control 58±17, access 59±12, quality 68±11 and total Dental Satisfaction Index (DSI) score of 62±10. 92.5% of the respondents reported that students were very careful when examining their patients. 96.8% reported that they treat their patients with respect . The most common reasons for dissatisfaction apart from waiting time and getting appointments were not providing preventive care and pain control.

  Conclusion: The results of this study shows acceptable level of satisfaction with dental care in teaching clinics of this dental school, however efforts on implementing preventive care and pain control strategies are suggested.

  Background and Aims: Making accurate impressions of prepared teeth when they are adjacent to dental implants is of great importance. In these situations, disregarding the selection of appropriate impression material and technique, not only can affect accuracy of transferring of the 3-dimentional spatial status of implant, but also can jeopardize the accurate recording of tooth. In the present study, the accuracy of two impression materials with taper impression copings for recording implant position and surface details was evaluated.

  Materials and Methods: One metal reference model with 2 implants (Implantium) and a preparation of three grooves on a tooth according to ADA no. 19 standard was fabricated. 10 medium- consistency polyEther (PE) impressions using custom trays and 10 polyVinyl Siloxane (PVS) putty wash impressions using prefabricated trays with conical impression coping were made. Impressions were poured with ADA type IV stone. A Coordinate Measuring Machine (CMM) evaluated x, y and angular displacement of the implant analog heads and also accuracy of groove reproduction were measured using a Video Measuring Machine (VMM). These measurements were compared to the ones from reference model. Data were analyzed using one-way ANOVA and T-test.

  Results: Putty wash PVS had less linear discrepancy compared with reference model (P > 0.001). There was no significant difference in the surface detail reproduction (P = 0.15).

  Conclusion: Putty wash PVS had better results for linear displacement compared with medium consistency PE. There was no significant difference in surface detail reproduction between the two impression materials.

  Background and Aims: Retention and stability of the post and core system is the key factor for success of final restoration . The aim of this study was to evaluate the microtensile bond strength of the different composite core materials and bonding systems to a fiber post.

  Materials and Methods: To evaluate the bond strength of the composite resins to a fiber post ( DT light post) 60 posts were divided into six groups : group A: Heliomolar Flow + Seal Bond, group B: Heliomolar Flow + SE Bond , group C: Valux Plus + Seal Bond , group D: Valux Plus + SE Bond , group E: Corecem + Seal Bond, group F: Corecem + SE Bond. All samples were thermocycled for 5000 cycles (5-55 ⁰C) and cut into four bars for the microtensile bond strength test. Failure modes were identified using a stereomicroscope. Data were analysed using One-way ANOVA and Tukey HSD post hoc test (P<0.05).

  Results: The interaction between composite resin materials and bonding systems were positive. The conventional hybrid composite (Valux Plus) had significantly higher bond strength compared with the core specific flowable composite (Corecem) when Seal Bond was applied as bonding agent (P<0.05). However, when SE Bond was utilized hybrid composite demonstrated significantly lower bond strength than that of other two groups (P<0.05).

  Conclusion: The performance of a particular composite is affected by the bonding system that is applied. A single composite resin may have different bond strength when combined with different bonding system.

  Background and Aims : According to the common application of non-metal prefabricated posts in dentistry and lack of enough information about the stress distribution in the root canal walls by these posts, this study was performed to compare the effect of two simple taper and double taper posts on the stress distribution on root canal walls by photo elastic method .

  Materials and Methods: The design of this study was experimental in photoelastic system. The posts, used in this investigation, were double taper and simple taper fiber posts with 0.9 mm diameter and 20 mm length and epoxy resin. First two photo elastic models with tooth dimensions were fabricated and the posts were placed inside the model. Then the core of the each post was fabricated on the model. Each models were loaded in polariscope and the formed fringe order colored ring were photographed.

  Results: In 100 N, 90 degree angle loading in cervical and apical fringe order showed 2.50 and 1.39 in simple taper posts and 1.39 and 2.35 in double taper post. In 150 N, 30 degree angle loading in cervical and apical fringe order showed 4 and 2.65 in simple taper posts, and 4 and 2.5 in double taper post.

  Conclusion: In the vertical and oblique loads, double taper fiber post showed better stress distribution than that of simple tapered posts.

  Background and Aims: Dental implants have been studied for replacement of missing teeth for many years. Productivity of implants is extremely related to the stability and resistance under applied loads and the minimum stress in jaw bone. The purpose of this study was to study numerically the 3D model of implant under thermal loads.

  Materials and Methods: Bone and the ITI implant were modeled in “Solidworks” software. To obtain the exact model, the bone was assumed as a linear orthotropic material. The implant system, including implant, abutment, framework and crown were modeled and located in the bone. After importing the model in Abaqus software, the material properties and boundary conditions and loads were applied and after meshing, the model was analyzed. In this analysis, the loads were applied in two steps. In the first step, the mechanical load was applied as tightening torque to the abutment and the abutment was tightened in the implant with 35 N.cm torque. In the second step, the thermal load originated from drinking cold and hot water was applied as thermal flux on the ceramic crown surface in this model.

  Results: Thermal analysis results showed that the thermal gradient in the bone was about 5.5 and 4.9 degrees of centigrade in the case of drinking cold and hot water respectively , although the maximum gradient of the whole system was reduced to 14 degrees, which occurred, in the crown by drinking cold water.

  Conclusion Thermal stresses were so small and it was because of the low thermal gradient. Maximum stresses occurred in the abutment were due to the tension preloads which were originated from the tightening torque.

  Background and Aims: Thermal changes in the oral cavity can be transferred to the implants placed in bone and affect the prognosis of the treatments. Furthermore, some investigators proposed improvement of habitual consumption of hot or cold beverages. The aim of the present study was to measure the effect of temperature changes in the oral cavity following consumption of hot and cold drinks on the temperature of implant.

  Materials and Methods: In this clinical trial, 3 eligible patients were selected. Two months after implant insertion, temperature of the implants was measured following the drinking of hot and cold beverages using a sensor connected to a thermometer. The thermal changes of the implants through the different time intervals were analyzed using Friedman non-parametric test.

  Results: The implant temperatures were significantly increased in the time following drinking of the hot beverages (P=0.009). Furthermore, the implant temperature were statistically decreased in the time after drinking cold beverage (P=0.004). When drinking hot beverages, the maximum and minimum temperatures were 41.57 ⁰ C and 36.77 ⁰ C, respectively. The maximum and minimum temperatures of the implants were also 34.13 ⁰ C and 26.83 ⁰ C , respectively, when drinking cold beverages.

  Conclusion: It seems that the temperatures noted in the implants in the current study cannot weaken the prognosis of implant restorations however, habitual consumption of hot and cold beverages can lead to debilitating implant prognosis and therefore, should be given the necessary warnings to patients.

  Background and Aims: Impacted third molar reduces the bone level in the distal aspect of second molar, and sometimes it can lead to root resorption of the adjacent tooth. The purpose of this study was to determine this resorption using panoramic and periapical radiographs.

  Materials and Methods: In this cross-sectional descriptive study 54 patient (28 men, 26 women) above 15 years old with the average of 22 years in Oral and Maxillofacial Department of Tehran University were studied. A periapical radiography from the third molar and a panoramic radiograph were taken from each patient (Because of their routine use and evaluation of accuracy of panoramic compared with periapical), and the magnitude of the root resorption for the second molar was determined by 2 observers and written in a questionnaire. Data were analyzed using Fisher test.

  Results: The prevalence of the root resorption of the second molar adjacent to the impacted third molar in the panoramic and the periapical radiographies, with respect to the limitation of the sample size were 46.3% and 31.5%, respectively, with 95% confidence(P>0.05). Most of these resorptions were in the cervical third of the second molar roots and in cases in which the third molars were mesially oriented or horizontal. There was also no significant difference between panoramic and periapical radiographs.

  Conclusion: Due to the increased risk of the resorption of the second molar adjacent to the third molar, extraction of the impacted third molars, especiall y mesially oriented or horizontal ones are recommended.

  Background and Aims: Application of fluoride products is known as one of the most successful interventions to prevent dental caries. This study aimed to compare the costs of in-office fluoride therapy versus salt fluoridation in Iranian population.

  Materials and Methods: In this study, the costs relating to the use of in-office fluoride therapy were analyzed using Activity Based Costing during 2011 from two perspectives. From the perspective of service provider, direct medical costs and indirect costs and from the view of service recipient, three parts: direct medical and non-medical costs and indirect costs, were considered. Costing for public consumption of salt fluoridation was estimated based on salt processing costs, including purchase, installation, monitoring, maintenance and repair of machinery, equipment, personnel expenses and cost of raw materials, used in this study.

  Results: Costs relating to performing a single in-office fluoride therapy was estimated to be 245,032 Rials from the perspective of service providers, and 239,600 Rials from the patient view. Estimated total cost to produce fluoridated salt for a unit of 10 million populations, was calculated to be 35 billion and 940 million Rials or 3, 594 Rials per person per year.

  Conclusion: It was concluded that per-capita costs of community based salt fluoridation was far less than in-office fluoride therapy. Salt fluoridation could be advised to be an affordable way to prevent dental caries in Iranian population.

  Background and Aims : As midwives are in frequent contact with pregnant mothers, they may play a key role in their oral health care (OHC). In this study, we aimed to evaluate the effect of an educational program on Tehran University of Medical Sciences midwifery students’ knowledge and preparedness on OHC in pregnant mothers. Materials and Methods: The midwifery third year students of central campus (n=29) were randomly selected as intervention group and their counterparts in Hemmat campus (n=33) as control. Students in both groups were asked to fill in a questionnaire included 8 demographic question and 18 OHC knowledge and one question on their preparedness to implement OHC. Then the educational intervention was implemented using lecture, demonstration of the correct methods of brushing and flossing on the models and role play method. The follow- up questionnaire was delivered 3 months later. Data were analyzed using Mann-Whitney test, T-test, Chi-Square test, ANOVA and Regression by SPSS software.

  Results: The mean OHC in pregnancy knowledge score in intervention and control group were 26.7 and 24.8 at baseline which were changed into 48.5 and 29.1, respectively (P<0.001). Among the students 52.6% in the intervention group and 36.4% in the control group reported very high preparedness to implement OHC in pregnancy. These figures were 68.2% and 41.7% in the post-test.

  Conclusion: The promising findings of this educational intervention comprising of both student and teacher-centered methods speak for possibility of improving these students knowledge and preparedness and implies on the necessity to incorporate the related course in midwifery education.

  Background and Aims: Occurrence of medical emergencies in dental offices is not uncommon. The most important and the first step in controlling the medical emergencies is the ability to provide basic life support which needs knowledge, experience and equipments. The aim of this study was to investigate the knowledge of dentists relating to the management of medical emergencies in dental office and their willingness towards holding related educational workshops.

  Materials and Methods: This analytic cross-sectional research was accomplished in Babol among 132 general and specialist dentists in 2010. A validated questionnaire (Knowledge and attitudes of reliability: Cronbach's α value 79% and 84% respectively) consisting of 17 questions about knowledge (score of 14-17: excellent, 11-14: good, 8-11 moderate and less than 8: poor), three questions about attitude and demographic characteristics was distributed. Data were analyzed using t-test, X² and Pearson correlation statistics using SPSS.

  Results: 119 dentists (91.9%) filled out the questionnaire. The average age was 38.6 ( ± 7.5) years with 84 (70.6%) male and 35 (29.4%) female individuals. The average score of knowledge was 9.31 ( ± 2.31) out of 17 points which was negatively correlated to the graduation year (r=-0.43) and age of dentists (r=-0.3). 94% were agreed with workshops and 75% were agreed with equipment of office and emergency kit and 84.9% were not satisfied with the academic education in that field.

  Conclusion: Knowledge of dentists in Babol was not sufficient in the field of medical emergencies which needs intervention for improving and updating by means of holding workshops and continuing education program.

  Background and Aims : The aim of this study was to evaluate the effect of chlorhexidin 2%, sodium hypochlorite 2.5% and hydrogen peroxide 3% as three effective and regular disinfectants on the microleakage of 7th generation bonding agents in vitro.

  Materials and Methods: 45 extracted molar teeth without carries were collected and disinfected. On buccal and lingual aspects of these teeth conventional class V cavity preparation were done (90 cavities), then randomly divided to 4 groups, three of them had 10 teeth (20 cavities) and one of them had 5 teeth (10 cavities) as control group. Cavities in each experimental group prepared with one of the disinfectants and then 7th generation bonding (Optibond all in one, kerr) was used as noted by manufacturer, then cavities filled with composite and polished. Bonding agent was used without our previous disinfectants manipulation in control group. Specimens were thermocycled with 1000 thermal cycles between 5 and 55 ⁰ C each for 30 seconds and then immersed in the methylene blue 5%, then sectioned mesiodistally and investigated for microleakage under stereomicroscope (Olympus, Japan). Data were analyzed using Kruskal-Wallis and Wilcoxon mean rank tests.

  Results: Despite the lower mean rank values for the untreated group at both occlusal and gingival aspects, the Kruskal-Wallis procedure (α=0.05) showed that the treatment factor did not significantly affect the mean rank values neither in occlusal (P=0.12) nor in gingival (P=0.39) part of cavities.

  Conclusion: According to the results of this study, antimicrobial agents such as chlorhexidine 2%, sodium hypochloride 2.5% and hydrogen peroxide 3% can be used perior to 7th generation dentin bonding agent
(Optibond all in one, kerr) without much concern.

  Background and Aims: The increase in the number of complex implant cases has drawn the attention of researchers toward materials having bone regeneration promoting ability. Socket preservation and bone graft are recommended to minimize bone resorption. The aim of this study was to evaluate a kind of xenograft collagenic bone (osteo biol gen_oss) in socket regeneration.

  Materials and Methods: This randomized clinical trial was performed in 12 cases (6 in test and 6 in control groups) with two hopeless teeth. After tooth extraction, in test group, graft material was put in sockets but in the control group the socket was healed naturally. Three months later, during implant placement the specimens from both sites were sent to a pathologist for histologic and histomorphometric evaluations. Data were analyzed using Mc Nemar and Wilcoxan sigh rank test (α=0.05).

  Results: There were no significant differences between two groups in foreign body reaction, inflammation, bone vitality and percentage of bone gain. Average percentage of residual graft in test site was 6.73±1.43.

  Conclusion: Osteobiol gen_oss xenograft is an appropriate biocompatible osteoconductive material that promotes bone regeneration at 3 months following socket preservation in human extraction sockets.

  Background and Aims : Antibiotics are commonly used for controlling the growth of porphyromons gingivalis (P.g) which is one of the most important etiologic factors in the periodontal diseases. Different side effects of synthetics and chemical drugs such as increasing the drug resistancy in the human pathogens have led to study on the herbal antibacterial effect. The aim of this study was to evaluate the antibacterial effect of cinnamon on the growth of porphyromons gingivalis in chronic periodontitis patients with deep pockets.

  Materials and Methods: In this experimental study, samples were provided from patients having pockets. After culturing the microorganism and diagnosis of P.g by gram staining and biochemical tests, cinnamon in different concentrations (10, 50, 100, 250, 500, 750 and 1500 mg/ml ) with oil solvent were prepared and placed by disks in the cultures medium. Positive controls were amoxicillin, metronidazole, ciprofloxacin, amikacin and gentamycin . Oil was negative control. Then the plates were incubated for 24 hours in 37 ⁰ C and then non-growth halos by disk diffusion method, MIC (Minimum Inhibitory Concentration) and MBC (Minimum Bactericidal Concentration) were determined. Data were analyzed using One-way ANOVA test.

  Results: The results showed that the cinnamon at the concentration of MIC=750 mg/ml had the inhibitory effects of bacteria and at the concentration of MIC=1500 mg/ml had killing effect. However, this antibacterial effect compared with commonly used antibiotics (amoxicillin, metronidazole), was much weaker (P<0.001).

  Conclusion: Cinnamon showed an antimicrobial effect on porphyromonas gingivalis in chronic periodontitis patients with deep pockets.

  Background and Aims: Since recurrent caries are one of the major causes of failure in resin restorations, the production of antibacterial resin composites was always under investigation. The aim of this study was to evaluate the efficacy of fissure sealants containing nanosilver particles against the Streptococcus mutans.

  Materials and Methods: In this experimental study, the antibacterial properties of two sealants (with fluoride (Clinpro 3M) and without fluoride (Concise 3M) was investigated with 0, 0.01, 0.02, 0.03, 0.04, 0.05% w/w after adding nano-silver using direct contact test. Sealants formed on the walls of 500ml micro tube and after curing, they left in contact with bacterial suspension. In periods of 3, 24, 48h, a 10 µl volume of liquid medium was placed in blood agar culture and after 24 h incubation at 37ºC, the number of S.mutans colony was counted by colony counter. Data were analyzed using ANOVA and
T-test.

  Results: Results reported sealants with fluoride comparing to non fluoride ones had significant effect on inhibition of S.mutans growth (P<0.001). The direct contact test demonstrated that by increasing the amount of nano particles, the bacterial growth was significantly diminished (P<0.001).

  Conclusion: While sealants with fluoride demonstrated antibacterial effect, sealants with incorporation of higher weight percentage of nanosilver particles, had stronger and more significant antibacterial effect in direct contact test.

  Background and Aims : The root fracture resistance of endodontically treated teeth depends on the types of posts. The aim of this study was to compare the effect of two types of bonded non-metallic posts with different elasticity modulus on the fracture resistance of endodontically treated teeth under compressive loads.

  Materials and Methods: In this in vitro experimental study, 20 fresh extracted mandibular premolars were selected and sectioned adjacent to the CEJ and then were endodontically treated. The specimens were randomly divided into two groups (n=10). After post space preparations, the fiber RTD Light posts (R.T.D, France) and zirconia coated fiber posts (ICE light, Danville) were cemented into the root canals. Composite resin (Lumiglass R.T.D, France) cores were built up. Aluminium foil was used to mimic the PDL, and the specimens were embedded in acrylic resin and tested in a Universal Testing Machine. A compressive load was applied at a 90 degree angle until fracture at a crosshead speed of 1mm/min. Data were analyzed using one-way ANOVA and T test .

  Results: The mean fracture resistance of R.T.D group was (1083.11 ± 156.74 (N)) and the mean of ICE light group was (865.18 ± 106.24 (N)). The highest mean fracture resistance was observed in RTD fiberglass and a statistically significant difference was observed between the two groups (P<0.001).

  Conclusion: FRC posts with zirconia coating due to unfavorable fractures of the teeth should be used with caution, and thus, fiber posts are preferred.