Tehran University of Medical Sciences Frontiers in Dentistry 2676-296X 10 2 2013 03 15 112 8 Mahmood Kazemi Assistant Professor, Department of Prosthodontics, Faculty of Dentistry, Tehran University of Medical Sciences, Tehran, Iran. Ahmad Rohanian Abbas Monzavi Mohammad Sadegh Nazari 2015 10 16 Accurate delivery of torque to implant screws is critical to generate ideal preload in the screw joint and to offer protection against screw loosening. Mechanical torque-limiting devices (MTLDs) are available for this reason. In this study, the accuracy of one type of friction-style and two types of spring-style MTLDs at baseline, following fatigue conditions and sterilization processes were determined.Five unused MTLDs were selected from each of Straumann (ITI), Astra TECH and CWM systems. To measure the output of each MTLD, a digital torque gauge with a 3-jaw chuck was used to hold the driver. Force was applied to the MTLDs until either the friction styles released at a pre-calibrated torque value or the spring styles flexed to a pre-calibrated limit (target torque value). The peak torque value was recorded and the procedure was repeated 5 times for each MTLD. Then MTLDs were subjected to fatigue conditions at 500 and 1000 times and steam sterilization processes at 50 and 100 times and the peak torque value was recorded again at each stage.Adjusted difference between measured torque values and target torque values differed significantly between stages for all 3 systems. Adjusted difference did not differ significantly between systems at all stages, but differed significantly between two different styles at baseline and 500 times fatigue stages.Straumann (ITI) devices differed minimally from target torque values at all stages. MTLDs with Spring-style were significantly more accurate than Friction-style device in achieving their target torque values at baseline and 500 times fatigue. https://fid.tums.ac.ir/index.php/fid/article/view/692 https://fid.tums.ac.ir/index.php/fid/article/download/692/667

Tehran University of Medical Sciences Frontiers in Dentistry 2676-296X 10 2 2013 03 15 119 23 Ahmad Jafari Associate Professor, Pedodontic Department, School of Dentistry, Tehran University of Medical Sciences, Tehran, Iran. Sima Shahabi Nasim Chiniforush Ali Shariat 2015 10 16 The purpose of this study was to evaluate the effect of Er:YAG laser on the shear bond strength of resin modified glass ionomer (RMGI) to enamel.Twenty extracted caries-free human premolars were selected. The teeth were embedded in acrylic resin. The buccal surfaces of each sample were ground to plane enamel with carbonated disc. The teeth were randomly divided in two groups. In the first group, the surfaces were treated by Er:YAG laser (350mJ/10Hz). The second group was prepared by carbide bur. Fuji IX RMGI was adhered to surfaces of the samples in both groups in rod shape. The shear bond strength of samples was measured by a universal testing machine. The results of the two groups were analyzed by T- test.The means and standard deviations of shear bond strength of the laser-treated group and the bur-treated group were 6.75 ± 1.99 and 4.41 ± 1.62 Mpa, respectively. There is significant difference in the shear bond strength of RMGI between the two groups (P-value=0.01).The laser group showed better results. Er:YAG laser can be an alternative technology in restorative dentistry. https://fid.tums.ac.ir/index.php/fid/article/view/690 https://fid.tums.ac.ir/index.php/fid/article/download/690/665

Tehran University of Medical Sciences Frontiers in Dentistry 2676-296X 10 2 2013 03 15 124 33 Sahil Jindal Senior Lecturer, Department of Pedodontics and Preventive Dentistry, Surendera Dental College and Research Institute, Rajasthan, India. Ritu Jindal Kanika Gupta Sandeep Mahajan Sunidhi Garg 2015 10 16 Comparative evaluation of the reinforcing effect of different post systems in the restoration of endodontically treated human anterior teeth at two different lengths of post space preparation- an in vitro study.135 extracted human incisors were endodontically treated, out of which 120 teeth were decoronated 2mm above the cementoenamel junction and divided into four experimental groups based on the post system to be used: Glass fiber post (GFP) and stainless steel post (SSP), titanium post (TTP), cast metal post (CMP). Each group was divided into two sub-groups according to the length of post space preparation: 5mm and 10mm. All the samples were restored with metal crowns. The fracture resistance was measured by applying loads at an angle of 135º to the long axis of teeth in an instron universal testing machine. Fracture mode was analyzed for all the samples. Results from the four test groups were compared and analysed using one-way ANOVA test and the Post-hoc Bonferroni test to demonstrate differences between pairs of groups.The results revealed that SSP group at 10mm post space length showed the significantly ("P-value< 0.05") highest fracture resistance (793.7787 N). Decrease in post length resulted in the decrease in fracture resistance in all the groups reduced to values even lesser than the control (437.8733N).The different post systems used in the study were able to reinforce endodontically treated teeth only at 10mm post space length. https://fid.tums.ac.ir/index.php/fid/article/view/688 https://fid.tums.ac.ir/index.php/fid/article/download/688/664

Tehran University of Medical Sciences Frontiers in Dentistry 2676-296X 10 2 2013 03 15 134 40 Sumitha Upadhyay Specialist Resident, Department of Pedodontics & Preventive Dentistry, Mangalore, India. Arathi Rao Ramya Shenoy 2015 10 16 To investigate and compare the amount of fluoride release of conventional, resin modified and nanofilled resin modified glass ionomer cements.Tablets of glass-ionomer cements were immersed in deionized water and incubated at 37°C. After 1, 2, 7, 15 and 30 days, fluoride ion was measured under normal atmospheric conditions by fluoride ion selective electrode. Buffer (TISAB II) was used to decomplex the fluoride ion and to provide a constant background ionic strength and to maintain the pH of water between 5.0 and 5.5 as the fluoride electrode is sensitive to changes in pH. Statistical evaluation was carried out by one way ANOVA (Analysis of Variance) using SPSS 11.0. The significance level was set at p< 0.05.The release of fluoride was highest on day 1 and there was a sudden fall on day 2 in all three groups. Initially fluoride release from conven-tional glass-ionomer cement was highest compared to the other two glass-ionomer cements, but the amount drastically reduced over the period. Although the amount of fluoride release was less than both the resin modified and nanofilled resin modified glass-ionomer cement, the release was sustained consistently for 30 days.The cumulative fluoride release of nanofilled resin modified glass ionomer cement was very less compared to the conventional and resin modified glass ionomer cements and Nanofilled resin modified glass ionomer cement released less but steady fluoride as compared to other resin modified glass ionomer cements. https://fid.tums.ac.ir/index.php/fid/article/view/686 https://fid.tums.ac.ir/index.php/fid/article/download/686/661

Tehran University of Medical Sciences Frontiers in Dentistry 2676-296X 10 2 2013 03 15 141 6 Armita Rouhani Assistant Professor of Endodontics, Dental Research Center, Faculty of Dentistry, Mashhad University of Medical Sciences, Mashhad, Iran. Jamileh Ghoddusi Neda Naghavi Zahra Ebadzadeh Majid Akbari 2015 10 16 The aim of this study was to compare the apical seal of curved canals obturated with Resilon/Epiphany with gutta-percha/AH Plus.Thirty-four extracted human mandibular molars with 25-40 degree canal curvature of the mesial root were selected for this study. After preparation, the mesiobuccal canals were obturated with gutta-percha and AH- Plus sealer (group G) or Resilon and Epiphany sealer (group R). Four specimens served as control. Microleakage was evaluated after passing 3 and 30 days using the fluid filtration technique. The data were analyzed statistically using parametric tests.In the 3-day evaluation, the mean microleakage in group R was significantly less than in group G (P< 0.05). After 30 days, there was no significant difference between the two groups (P> 0.05). In group G, the leakage values at the end of 30 days were significantly less than values at the end of 3 days. Although in group R the mean leakage decreased after 30 days, this reduction was not statistically significant.Resilon/Epiphany provided a better seal than gutta-percha/AH-Plus in severely curved root canals immediately after obturation, although with the passage of time, Resilon/Epiphany was equivalent to gutta-percha/AH Plus in sealing properties. https://fid.tums.ac.ir/index.php/fid/article/view/684 https://fid.tums.ac.ir/index.php/fid/article/download/684/659

Tehran University of Medical Sciences Frontiers in Dentistry 2676-296X 10 2 2013 03 15 147 54 Sedigheh Khedmat Dental Research Center, Dentistry Research Institute, Department of Endodontics, School of Dentistry, Tehran University of Medical Sciences, Tehran, Iran ; Researcher, Iranian Center for Endodontic Research, Tehran, Iran. Fatemeh Momen-Heravi Malihe Pishvaei 2015 10 16 Handling of endodontic sealers is greatly dependent on their elasticity and flow ability. We compared the viscoelastic properties of three root canal sealers.AH Plus (Dentsply, De Trey, Konstanz, Germany), Endofill (Dentsply Hero, Petrópolis, Rio de Janeiro, Brazil) and AH26 (Dentsply, De Trey, Konstanz, Germany) were mixed according to the manufacturers' instructions. The resulted pastes were placed on the plate of a rheometer (MCR 300, Anton-Paar, Graz, Austria). The experiments were performed at 25°C and 37°C. Viscoelastic properties of the sealers including loss modulus (G″), storage modulus (G') and complex viscosity (η*) were studied using dynamic oscillatory shear tests. The shear module versus frequency (from 0.01 to 100 S(-1)) curves were gained using frequency deformation sweep test. Three samples of each material were examined at each temperature. The mean of these three measurements were recorded.The storage modulus of AH plus was higher than its loss modulus at two temperatures. Endofill exhibited a crossover region in which the storage modulus crosses the loss modulus in both temperatures. At 25°C the loss modulus of AH26 was higher than the storage modulus (G″>G'). In contrast, at 37°C G' was greater than G″ (G'>G″). Both shear modules of AH Plus and Endofill decreased as the temperature raised from 25°C to 37°C. On the contrary, the loss modulus and storage modulus of AH26 increased at 37°C.In both test temperatures, AH Plus behaved like viscoelastic solids and Endofill exhibited a gel-like viscoelastic behavior. AH26 at 25°C behaved like liquids, while at 37°C it was an elastic solid-like material. https://fid.tums.ac.ir/index.php/fid/article/view/682 https://fid.tums.ac.ir/index.php/fid/article/download/682/657

Tehran University of Medical Sciences Frontiers in Dentistry 2676-296X 10 2 2013 03 15 155 63 Rahab Ghoveizi Assistant Professor, Department of Prosthodontics, Shahid Beheshti University of Medical Sciences, School of Dentistry, Tehran, Iran. Marzieh Alikhasi Mohammad-Reza Siadat Hakimeh Siadat Majid Sorouri 2015 10 16 Crestal bone loss is a biological complication in implant dentistry. The aim of this study was to compare the effect of progressive and conventional loading on crestal bone height and bone density around single osseointegrated implants in the posterior maxilla by a longitudinal radiographic assessment technique.Twenty micro thread implants were placed in 10 patients (two implants per patient). One of the two implants in each patient was assigned to progressive and the other to conventional loading groups. Eight weeks after surgery, conventional implants were restored with a metal ceramic crown and the progressive group underwent a progressive loading protocol. The progressive loading group took different temporary acrylic crowns at 2, 4 and 6 months. After eight months, acrylic crowns were replaced with a metal ceramic crown. Computer radiography of both progressive and conventional implants was taken at 2, 4, 6, and 12 months. Image analysis was performed to measure the height of crestal bone loss and bone density.The mean values of crestal bone loss at month 12 were 0.11 (0.19) mm for progressively and 0.36 (0.36) mm for conventionally loaded implants, with a statistically significant difference (P < 0.05) using Wilcoxon sign rank. Progressively loaded group showed a trend for higher bone density gain compared to the conventionally loaded group, but when tested with repeated measure ANOVA, the differences were not statistically significant (P > 0.05).The progressive group showed less crestal bone loss in single osseointegrated implant than the conventional group. Bone density around progressively loaded implants showed increase in crestal, middle and apical areas. https://fid.tums.ac.ir/index.php/fid/article/view/680 https://fid.tums.ac.ir/index.php/fid/article/download/680/655

Tehran University of Medical Sciences Frontiers in Dentistry 2676-296X 10 2 2013 03 15 164 8 Faramarz Mojtahedzadeh Assistant Professor, Dental Research Center, Dentistry Research Institute and Department of Orthodontics, Tehran University of Medical Sciences, Tehran, Iran. Saeed Alizadeh Bahareh Riazi Ahmad Reza Shamshiri 2015 10 Shadab Rashtak Dental Implant Research Center, Tehran University of Medical Sciences Tehran, Iran. Soolmaz Akbari Dental Implant Research Center, Tehran University of Medical Sciences Tehran, Iran. Samareh Badri Dental Implant Research Center, Tehran University of Medical Sciences Tehran, Iran. Niloufar Daneshparvar Dental Student, Tehran University of Medical Sciences Tehran, Iran. Amirreza Rokn Associated Professor, Dental Implant Research Center and Periodontics Department, Tehran University of Medical Sciences Tehran, Iran. 2015 10 16 The focus of this paper is to evaluate the influence of mechanical characteristics of the implant on primary stability in different bone types, based on resonance frequency analysis (RFA).A number of 60 Nobel Biocare Replace Select TiUnit Tapered implants of two different lengths (10 mm and 13 mm) and three different widths as 3.4 mm (narrow platform (NP)), 4.3 mm (regular platform (RP)) and 5 mm (wide platform (WP)) were placed into two different groups of bone blocks. Bone blocks were different in bone quality, but similar to bone types D1 and D3. Immediately, after implant placement, implant stability quotient (ISQ) was measured using the Osstell mentor device.ISQ values for implant placements in D1 bone were significantly higher than those for implants placed in D3 bone. In D1 bone, the implant length did not make any significant difference in primary stability; however, in D3 bone, the primary stability of the implant increased when longer implants were utilized. NP implants presented significantly lower ISQ values compared to the two wider implants.In cases of low bone quality, the optimum increase in the implant length and diameter should be taken into account to achieve higher primary stability. https://fid.tums.ac.ir/index.php/fid/article/view/606 https://fid.tums.ac.ir/index.php/fid/article/download/606/581

Tehran University of Medical Sciences Frontiers in Dentistry 2676-296X 10 5 2013 10 15 456 60 Leila Khojastepour Associated Professor, Department of Oral Radiology, School of Dentistry, Shiraz University of Medical Sciences, Shiraz, Iran. Pegah Bronoosh Assistant Professor, Department of Oral Radiology, School of Dentistry, Shiraz University of Medical Sciences, Shiraz, Iran. Shahdad Khosropanah Associated Professor, Department of Cardiology, School of Medicine, Shiraz University of Medical Sciences, Shiraz, Iran. Elham Rahimi Student Research Committee, School of Medicine, Shiraz University of Medical Sciences, Shiraz, Iran. 2015 10 16 To report the association of pulp calcification with that of cardiovascular disease (CVD) using digital panoramic dental radiographs.Digital panoramic radiographs of patients referred from the angiography department were included if the patient was under 55 years old and had non-restored or minimally restored molars and canines. An oral and maxillofacial radiologist evaluated the images for pulpal calcifications in the selected teeth. The sensitivity, specificity, positive predictive value and negative predictive value of panoramic radiography in predicting CVD were calculated.Out of 122 patients who met the criteria, 68.2% of the patients with CVD had pulp chamber calcifications. Pulp calcification in panoramic radiography had a sensitivity of 68.9% to predict CVD.This study demonstrates that patients with CVD show an increased incidence of pulp calcification compared with healthy patients. The findings suggest that pulp calcification on panoramic radiography may have possibilities for use in CVD screening. https://fid.tums.ac.ir/index.php/fid/article/view/604 https://fid.tums.ac.ir/index.php/fid/article/download/604/579

Tehran University of Medical Sciences Frontiers in Dentistry 2676-296X 10 5 2013 10 15 461 5 Javad Chalipa Assistant Professor, Department of Orthodontics, Tehran University of Medical Sciences, Tehran, Iran. Mohammad Sadegh Ahmad Akhondi Professor, Dental Research Center, Dentistry Research Institute, Department of Orthodontics, Tehran University of Medical Sciences, Tehran, Iran. Sepideh Arab Assistant Professor, Department of Orthodontics, Qazvin University of Medical Sciences, Qazvin, Iran. Mohammad Javad Kharrazifard Post Graduated Student of Epidemiology, Dental Research Center, Tehran University of Medical Sciences, Tehran, Iran. Maryam Ahmadyar General Dental Practitioner, Tehran, Iran. 2015 10 16 The purpose of this study was to evaluate the shear bond strength (SBS) of orthodontic brackets bonded with two types of nano-composites in comparison to a conventional orthodontic composite.Sixty extracted human first premolars were randomly divided into 3 groups each containing 20 teeth. In group I, a conventional orthodontic composite (Transbond XT) was used to bond the brackets, while two nano-composites (Filtek TM Supreme XT and AELITE Aesthetic Enamel) were used in groups II and III respectively. The teeth were stored in distilled water at 37°C for 24 hours, thermocycled in distilled water and debonded with a universal testing machine at a crosshead speed of 1 mm/min. The adhesive remnant index (ARI) was also evaluated using a stereomicroscope.AELITE Aesthetic Enamel nano-composite revealed a SBS value of 8.44±2.09 MPa, which was higher than Transbond XT (6.91±2.13) and Filtek TM Supreme XT (6.04±2.01). Statistical analysis revealed a significant difference between groups II and III (P < 0.05). No significant difference was found between groups I and III, and between groups I and II (P > 0.05). Evaluation of ARI showed that Transbond XT left fewer adhesive remains on teeth after debonding.Results of this study indicate that the aforementioned nano-composites can be successfully used for bonding orthodontic brackets. https://fid.tums.ac.ir/index.php/fid/article/view/603 https://fid.tums.ac.ir/index.php/fid/article/download/603/578

Tehran University of Medical Sciences Frontiers in Dentistry 2676-296X 10 5 2013 10 15 466 77 S Tharani Kumar Senior Lecturer, Sathyabama University Dental College, Chennai, India. Saurabh Saraf Oral and Maxillofacial Surgeon, Director, Pearls Dental Studio, Nagpur, India. S Prasanna Devi Associate Professor, Department of Computer Science Engineering, Apollo Engineering College, India. 2015 10 16 The primary aim of this study is to determine maximum bite force in molar and incisor regions of healthy individuals, to evaluate the bite force after open reduction and internal fixation of mandibular fractures using micro plates, for a period of up to 6 weeks and to determine the rate of recovery of maximum bite force in an Indian population. https://fid.tums.ac.ir/index.php/fid/article/view/601 https://fid.tums.ac.ir/index.php/fid/article/download/601/576

Tehran University of Medical Sciences Frontiers in Dentistry 2676-296X 10 5 2013 10 15 478 86 Mansour Khorasani Associated Professor of Oral and Maxillofacial Surgery Department, School of Dentistry, Qazvin University of Medical Sciences, Qazvin, Iran. Mohsen Hasani Barzi Assistant Professor of Neurosurgery Deptartment, School of Medicine. Qazvin University of Medial Sciences, Qazvin, Iran. Bahman Derakhshan Assistant Professor of Oral and Maxillofacial Surgery Department, School of Dentistry, Qazvin University of Medical Sciences, Qazvin, Iran. 2015 10 16 Plagiocephaly (oblique skull) is premature fusion of one of the coronal sutures. Frontal plagiocephaly is a rare congenital deformity in the skull that is the most complicated form of craniosynostosis to treat. Examination of all sutures is necessary for diagnosis of craniosynostosis In this article, a 10-month-old, healthy girl with deformity of the right forehead and orbit that is caused by frontal plagiocephaly and coronal unilateral synostosis is presented. This abnormality was corrected by frontal craniotomy and fronto-orbital complex advancement under general anesthesia. An exact clinical and radiographic (Multislice CT scan with 3-dimensional three dimensional reconstruction) examination with the suitable time of surgery is necessary for diagnosis of skull abnormality and prevention of treatment delay. Furthermore, 3D stereo-photo-grammetry is a radiation-free, non invasive method for evaluating the growth pattern of children in long term. https://fid.tums.ac.ir/index.php/fid/article/vie