1 2251-9890 Babol University of Medical Sciences 278 Community Oral Health The pattern of use of toothpaste among family members in Tehran Iran Soltani Sorour b Hessari Hossein c Yazdani Reza d b ,University dentistry removed c ,Department of Community Oral Health, School of Dentistry, Tehran University of Medical Sciences, Tehran, IR Iran. d ,Research Center for Caries Prevention, Dentistry Research Institute, Tehran University of Medical Sciences,Tehran, IR Iran. 1 9 2020 9 2 8 15 08 07 2019 02 09 2020 Introduction: Oral health can influence general health and then the quality of life. Regular toothbrushing with toothpaste plays a fundamental role in oral hygiene. The aim of this study was to assess the pattern of utilization of toothpaste among Iranian population. Materials & Methods: This cross-sectional study evaluated the family members of patients (n=715) presenting to dental clinics of School of Dentistry of Tehran University of Medical Sciences, in 2017. A researcher-made questionnaire was used to collect information regarding the pattern of utilization of toothpaste by the subjects. Data were analyzed using Chi-square test via SPSS 25. Results: Of all, 81% participants reported that they personally use toothpaste when toothbrushing and 75.9% stated that all the family members used toothpaste when brushing their teeth. Moreover, 57.2% reported that all the family members shared the same toothpaste; 86.6% reported that they started brushing the teeth of their children at the age of 3 years. When asked about the factors considered when for purchasing - toothpaste, the most important factors were the manufacturing country (42.5%), date of production (38.7%), having standard and authenticity labels (29.5%), the price (29.5%). Conclusion: According to the results, Iranian families have inadequate knowledge about the correct pattern of use of toothpastes.  
288 Prosthodontics Effect of three veneering techniques on fracture resistance and marginal adaptation of zirconia-based crowns Amiri Daneshvar Farshid e Alhavaz Abdolhamiid f Ahmadizenouz Ghazaleh g Bijani Ali h e , Student Research Committee, Babol University of Medical Sciences, Babol, IR Iran. f ,Dental Materials Research Center,Health Research Institute, Babol University of Medical Sciences, Babol, IR Iran. g ,Dental Materials Research Center, Health Research Institute, Babol University of Medical Sciences, Babol, IR Iran. h ,Social Determinants of Health Research Center, Health Research Institute , Babol University of Medical Sciences, Babol, IR Iran. 1 9 2020 9 2 16 25 08 11 2019 02 09 2020 Introduction: The aim of this study was to evaluate the fracture resistance (FR) of zirconia-based crowns veneered with different methods and to assess marginal gap before and after veneering. Materials & Methods: Thirty zirconia copings fabricated by Computer Aided Design/Computer Aided Manufacturing (CAD/CAM) were divided into three groups. In the porcelain layering (PL) group, the copings were manually veneered with VM9 feldspathic porcelain. In the indirect composite (IC) group, the Gradia indirect composite was veneered on zirconia copings, and for the CAD-on (CO) group, the CAD/CAM-fabricated Vita Mark II veneer was cemented onto the copings. For each sample, the marginal gap values at four points (buccal, lingual, mesial and distal) were measured using stereomicroscope and computer software (Motic Images plus 2.0 ML) before and after veneering process. All crowns were cemented on their dies with resin cement and then were loaded by a universal testing machine for failure. Data were analyzed using one-way ANOVA and post-hoc Tukey tests at significant level of 0.05. Results: Mean FR was statistically higher in PL group (3005 N) than IC (2026 N) and CO (1605 N) groups (P=0.000). Before and after veneering, mean marginal gap was 43.42μm and 48.47μm for PL group, 44.69μm and 51.06μm for IC group as well as 53.03μm and 56.08μm for CO group, respectively. Marginal gap had no significant difference in study groups before and after veneering (P=0.56 and 0.18, respectively). The lowest change in marginal gap was observed in CO group. Conclusion: The PL technique might increase the failure resistance of Zirconia-based crowns compared to IC and CO techniques. The marginal gap rate following veneering in all three techniques was within acceptable clinical limits. 285 Oral & Maxillofacial Pathology CD-1a immunoexpression in oral lichen planus and oral lichenoid reaction Majidian Azadeh i Seyedmajidi Maryam j Abbaszadeh Hamid k Sharbatdaran Majid l Jafari Sina m Gholinia Hemmat n i ,Student Research Committee, Babol University of Medical Sciences, Babol, IR Iran. j ,Dental Materials Research Center, Health Research Institute, Babol University of Medical Sciences, Babol, IR Iran. k ,Department of Oral and Maxillofacial Pathology, Faculty of Dentistry, Birjand University of Medical Sciences, Birjand, IR Iran . l ,Cellular and Molecular Biology Research Center, Health Research Institute, Babol University of Medical Sciences, Babol, IR Iran . m ,Department of Prosthodontics, Faculty of Dentistry, Shahed University Tehran,Tehran,IR Iran. n ,Health Research Institute, Babol University of Medical Sciences, Babol, IR Iran. 1 9 2020 9 2 26 34 20 10 2019 10 06 2020 Introduction: Oral lichen planus (OLP) is an immunologically mediated mucocutaneous diseases. Langerhans cells (LCs) are antigen presenting cells resident within oral mucosa which, together with intraepithelial lymphocytes, play a role in mucosal defense. The aim of present study was to determine the immunohistochemical expression of LC in oral lichenoid reaction  (OLR) and OLP compared with normal oral mucosa (NOM). Materials & Methods: In this cross-sectional study, 61 oral mucosal specimens diagnosed histopathologically as OLP (n=31) and OLR (n=30) and 11 NOM were used to study the immunohistochemical expression of CD1a. The CD1a positive LCs in three regions (basal, suprabasal, and connective tissue) were counted in six randomly selected fields. Data were analyzed using the SPSS 24, T-test, ANOVA, LSD, Games-Howell tests. P<.05 was considered significant. Results: CD1a expression in OLP and OLR was significantly higher compared to NOM (P<0.001). CD1a expression in OLP was also significantly higher than OLR (P=0.009). There was a statistically significant difference between the three groups in basal, suprabasal and connective tissue regions (P<0.001).  The mean of CD1a positive cells in the basal, suprabasal and connective tissue regions was significantly higher in the OLP group than OLR and NOM. Also, in comparison between OLR and NOM, the OLR group had significantly more CD1a positive cells (P<0.05). Conclusion: Increasing the number of CD1a in OLP and OLR compared with the NOM indicates the role of LC in the pathogenesis of these diseases. 293 Prosthodontics Effect of soldering on bond strength of porcelain to metal in porcelain-fused-to-metal castings Farzamfar Naser o Mahabadi Meysam p Barekatain Mehrdad Jamshidi Sina o ,University dentistry removed p ,Department of Prosthodontics, Isfahan (Khorasgan) Branch, Islamic Azad University, Isfahan,IR Iran. ,Department of Restorative Dentistry, Isfahan (Khorasgan) Branch, Islamic Azad University, Isfahan,IR Iran. ,Department of Prosthodontics, Isfahan (Khorasgan) Branch, Islamic Azad University, Isfahan,IR Iran. 1 9 2020 9 2 35 41 14 12 2019 10 06 2020 Introduction: Soldering has several applications in prosthodontic treatments; however, the effect of soldering on porcelain to metal bond strength has not been adequately studied. This study was designed to assess the bond strength of porcelain to metal, and the mode of failure at the soldered and non-soldered areas of cubic specimens. Materials & Methods: In this in vitro, experimental study, 40 porcelain-metal specimens were fabricated under similar conditions and divided into two groups (n=20). In the test group, a hole was created at the center of the frame and was then soldered and veneered with porcelain. The second group was considered as a control group. The bond strength was measured at the center of the specimen using the 3-point bending test in a universal testing machine with a crosshead speed of 0.5 mm/min. The mean force required for debonding was determined. Photographs of the specimens were digitalized by a scanner and magnified on a computer screen with x10.5 magnification. Next, each image was divided into 100 squares (1×1 mm). The mode of failure was determined for each specimen. The two groups were compared using independent t-test (p-value˂ 0.05). Results: The mean porcelain-metal bond strength was 36.6±7.3 N for the soldered and 37.4±4.6 N for the non-soldered group with no significant difference between them (P>0.05). The mode of failure was cohesive in all specimens in both groups with no significant difference between them (P>0.05). Conclusion: Within the limitations of this study, the soldered and non-soldered specimens showed no significant difference regarding the porcelain-metal bond strength. 310 Oral & Maxillofacial Radiology A comparison of image artifacts with gutta-percha and different sealers on root filled teeth using cone beam computed tomography: An in vitro study Gholampour Atefeh Soleymani Ali Bijani Ali Haghanifar Sina , Student Research Committee, Babol University of Medical Sciences, Babol, IR Iran. ,Dental Materials Researh Center, Health Research Institute, Babol University of Medical Sciences, Babol, IR Iran. , Social Determinants of Health Research Center, Health Research Institute, Babol University of Medical Sciences, Babol, IR Iran. , Oral Health Research Center, Health Research Institute, Babol University of Medical Sciences, Babol, IR Iran. 1 9 2020 9 2 42 49 11 07 2020 23 08 2020 Introduction: Different materials cause artifacts in cone-beam computed tomography (CBCT) images, which, in turn, reduce the quality of images. The aim of this study was to investigate the abundance of artifacts induced by different root canal therapy sealers with two different CBCT resolutions. Materials & Methods: Roots of four maxillary central phantom teeth were prepared using rotary files in three steps. In the first step, the first tooth was scanned first without gutta-percha and then with gutta-percha No. 25. Gutta-percha No. 25 with resin, the zinc oxide-eugenol (ZOE)-based sealer and the ceramic-based sealer were placed in the teeth No. 2, 3 and 4, respectively. The second step was performed similar to the first step, except that gutta-percha No. 35 was used in the tooth No. 1 with resin- and ZOE-based sealers in the teeth No. 2 and 3. due to the lack of access to the ceramic-based sealer that was not used to continue the study . In the third step, canal obturation was performed in the teeth No. 2 and 3 with resin and ZOE-based sealers. At each step, three CBCT scans were obtained in high and standard resolution conditions. Contrast-to-noise ratio was obtained in three root plans, and the data were analyzed. Results: Gutta-percha alone produced more artifacts than gutta-percha with sealers. Moreover, ZOE-based sealers induced more artifacts than other sealers. There was no significant difference between the three steps. Similarly, at different resolutions, there was no significant difference between gutta-percha and sealer artifacts. The ZOE-based sealers had more artifacts at 1/3 apical whereas resin sealers had more artifacts at 1/3 coronal. Conclusion: The higher artifact of gutta-percha in comparison with gutta-percha and sealer and the artifact decrease in the combination of gutta-percha and resin-based sealer than ZOE-based sealer has led us to recommend the use of resin-based sealer while root canal therapy in order to better evaluation of the CBCT Images of root canal. 302 Endodontics Comparison of apical microleakage of mineral trioxide aggregate, calcium-enriched mixture cement and biodentine as root end filling materials Ghobadi Abbas Soleymani Ali Gholinia Hemmat ,Student Research Committee, Babol University of Medical Sciences, Babol, IR Iran. ,Dental Materials Research Center, Health Research Institute, Babol University of Medical Sciences,Babol, IR Iran. , Health Research Institute, Babol University of Medical Sciences,Babol, IR Iran. 1 9 2020 9 2 50 56 29 05 2020 21 07 2020 Introduction: The aim of this in vitro study was to assess the apical microleakage of mineral trioxide aggregate (MTA), calcium enriched mixture (CEM) cement, and biodentine. Materials & Methods: The study was performed on 76 single-canal human teeth. Root canals were prepared by ProTaper rotary system, obturated with gutta-percha. Thereafter, the apical section of the teeth was cut from 3 mm above the apex, and 3 mm of gutta-percha was removed by an ultrasonic device from the apical part of the root canals. Then, 60 teeth were randomly assigned to 3 groups and filled with MTA, CEM cement, and biodentine. Control groups were also prepared. All surfaces of the samples were covered with two layers of nail polish, except for the surfaces near the apical filling. In each group, half of the samples were immersed in indian ink for 3 days and the other half for 7 days. After clearing, the samples were examined using stereo microscope with 20x magnification and dye penetration was evaluated. Data analysis was performed using Repeated measures and One-way ANOVA and p<0.05 was considered significant. Results: The mean microleakage for MTA, CEM cement and biodentine on the third day were 2576.80 and 2567.60, 2370.20 and the mean on the seventh day were 2431.50, 1516.50 and 1560.70, respectively. The mean leakage was not statistically different in samples on the third and seventh days. The difference of microleakage was statistically significant among these materials. Conclusion: It seems the biodentine compared to MTA and CEM cement have better apical sealing ability. 306 Endodontics Comparison of the push-out bond strength between root mineral trioxide aggregate( MTA) and calcium-enriched mixture (CEM) cement Tavasoli Reza Saeidi Akam Mahmoudi Elham Barijani Naeim Gholinia Hemmat , Student Research Committee , Babol University of Medical Sciences,Babol , IR Iran. , Dental Materials Research Center , Health Research Institute , Babol University of Medical Sciences , Babol , IR Iran. , Dental Materials Research Center , Health Research Institute , Babol University of Medical Sciences , Babol , IR Iran. , Oral Health Research Center , Health Research Institute , Babol University of Medical Sciences, Babol , IR Iran. , Health Research Institute , Babol University of Medical Sciences , Babol , IR Iran. 1 9 2020 9 2 57 62 08 06 2020 31 08 2020 Introduction: Root mineral trioxide aggregate (MTA) is a type of MTA that has been introduced in the Iranian market. There have been few studies on this substance. This study compared the push-out bond strength of Root MTA and CEM cement, which were both Iranian products. Materials & Methods: This in vitro study was performed on 20 extracted maxillary incisors. Samples were divided in  two groups. The canals of the first group were filled with Root MTA and the second group by CEM cement. In order to investigate the push-out bond strength, the device applied a force in the direction parallel to the longitudinal axis of the sample so that the desired materials would fail. Each sample was classified into one of three types of failureincluding adhesive (failure in the material and dentin interface), cohesive (failure in the material itself) or a combination of both. Results: There was no significant difference between the mean pressure on teeth for the two groups (P>0.05). There was no significant difference between the frequencies of different types of failure between the two groups (P>0.05). Cohesive failure in the CEM group was twice as high as in the MTA group (P>0.05). Conclusion:There was no any significant difference between the push-out bond strength of CEM cement and Root MTA cement. These findings demonstrated that Root MTA material showed a satisfactory result in the bond strength test compared to CEM material, and could be used as an alternative to CEM cement. 299 Endodontics Frequency of middle mesial canal and radix entomolaris in mandibular first molars by cone beam computed tomography in a selected Iranian population Hosseini Somaye Soleymani Ali Moudi Ehsan Bagheri Tasnim Gholinia Hemmat , Student Research Committee, Babol University of Medical Sciences, Babol, IR Iran. ,Oral Health Research Center, Health Research Institute, Babol University of Medical Sciences,Babol, IR Iran. ,Dental Materials Research Center, Health Research Institute, Babol University of Medical Sciences,Babol, IR Iran. ,Oral Health Research Center, Health Research Institute, Babol University of Medical Sciences,Babol, IR Iran. ,Health Research Institute, Babol University of Medical Sciences, Babol, IR Iran. 1 9 2020 9 2 63 70 25 01 2020 03 08 2020 Introduction: Although there are many studies about the internal anatomy of mandibular molars, there is still controversy over the frequency of middle mesial canals and isthmuses in the mesial root of mandibular molars and distolingual third root (Radix entomolaris) that  it can be seen in any population, but it is more frequent in Asians and makes endodontic treatment difficult. Because of limited studies on the middle mesial canal, isthmus in north of Iran; therefore, the aim of this study was to investigate the frequency of these variations in the north of country. Materials & Methods:  In this retrospective cross-sectional study, The cone beam computed tomography (CBCT) images of 200 mandibular first molar teeth without any root canal treatment and completely erupted and developed were evaluated. Samples with open apex, internal root resorption, calcification, crown and extensive restoration were excluded. The patients’ gender, age, tooth location (left and right), count of canals in the mesial root, presence or absence of isthmus in mesial root, middle mesial canal and isthmus level in the mesial root and distolingual root (Radix entomolaris) were studied in three groups based on age; <20, 20-40 and >40. Results: From 200 samples, 18 teeth (9%) had middle mesial canal, 38 teeth (19%) had isthmus in mesial root and 6 teeth (3%) had distolingual root (Radix entomolaris). Conclusion: due to the high frequency of isthmuses, middle mesial canals and Radix entomolaris in the population, which cannot be ignored, missing and treating these spaces could be one of the main reasons for failure in root canal treatment. Therefore, it is advised to put more effort into detecting and completely clean and obturate these spaces in surgical and non-surgical endodontic treatments. 298 Pedodontics Comparison of shear bond strength of a composite resin to resin modified and conventional glass ionomer using different bonding systems Banimostafa Mahtab Esmaeili Behnaz Khodadadi Effat Khafri Soraya , Student Research Committee, Babol University of Medical Sciences, Babol, IR Iran. , Dental Materials Research Center,Health Research Institute, Babol University of Medical Sciences, Babol, IR Iran. ,Oral Health Research Center, Health Research Institute , Babol University of Medical Sciences, Babol, IR Iran. , Dental Materials Research Center, Health Research Institute, Babol University of Medical Sciences,Babol, IR Iran. 1 9 2020 9 2 71 78 20 01 2020 15 08 2020 Introduction: Glass ionomers are often used as a base under composite restorations in deep cavities by sandwich technique. The aim of this study was to compare the shear bond strength of composite to resin modified and conventional glass ionomer using total etch , self-etch and universal bonding systems. Materials & Methods: Ninety glass-ionomer samples were prepared for this research: Fuji II (F II), IonoStar Plus (IS) and Fuji II LC (F II LC).Then the specimens were divided into 9 groups (n=10). The surface of the specimens were prepared with three types of bonding: Adper single bond2 (SB), Clearfil SE bond (SE) and Single bond Universal (SU).Then Z250 composite resin was applied on the glass ionomers. The specimens were incubated in distilled water for 24 hours at 37 ° C and then were tested for shear bond strength. The type of failure was determined by a ×40 stereomicroscope and the results of the study were analyzed by nonparametric statistical analysis and Kruskal Wallis test. P≤0.05 was considered significant. Results: The highest shear bond strength was observed in the Fuji II LC + Single bond2 group. There was a statistically significant difference in the shear bond strength of the composite to the two glass ionomers F II and F II LC using SB and SU bonding systems (P=0.033 and P=0.040, respectively).There was no significant difference between the groups regarding the type of failure. Conclusion: Unlike the Fuji II LC and IonoStar Plus glass ionomers, the shear bond strength of the composite to the Fuji II conventional glass ionomer is affected by the type of bonding system. Total-etch and self-etch bonding systems can be used effectively in sandwich technique. Using a resin modified glass ionomer with total etch bonding can improve the shear bond strength of the composite to the glass ionomer.