Showing 9 results for Mirfazaelian
H. Siyadat , A. mirfazaelian ,
Volume 15, Issue 2 (8 2002)
Abstract
Microkeakage is one of the most important factors in restoration longevity. Microleakage can lead to recurrent caries, marginal fracture, marginal discoloration and tooth sensitivity. Several methods have been used for in-vitro measurement of microleakage. The present study is a review of the articles,from 1967 to 1999, which have been present in Medline.
M. Kandi Bidgoli , A. Mirfazaelian , Sn. Ostald ,
Volume 18, Issue 1 (30 2005)
Abstract
Statement of Problem: One of newly presented base metal alloys (Minalux) is produced according to VeraBond2 alloy (Ni- Cr base) composition. Several studies showed that, cytotoxicity of base metal alloys can be occurred due to corrosion and element release.
Purpose: This study evaluated the biocompatibility of these two base metal alloys in three steps: as cast, after polishing and after porcelain firing cycles. Release of Ni and Cr ions were measured to determine if there is any difference between these two alloys.
Materials and Methods: Samples of two base metal alloys were subjected to Neutral Red Assay, MTT Assay and Trypan Blue for biocompatibility tests. Fibroblast Balb/c 3T3 cells were used for cell culture. Samples were contacted directly with cells in 37ºc and 5% Co2 concentration for 72 hours. Teflon samples were used as negative control. ANOVA test was used to compare different groups of two alloys. In addition, the release of Ni and Cr ions in to saline solution was measured by means of atomic absorption spectrometry.
Results: MTT and Trypan Blue didn’t show any significant difference between Minalux, VeraBond2 and Teflon. Neutral Red Assay showed no significant difference between these two base metal alloys but as cast group was higher in cytotoxicity in comparisons with polished and firing groups in both two alloys. Release of Cr ion was non detectable (Cr < 1 PPB) but Ni ion was measured and Ni release was significantly different in as cast groups (P=0.007) of two alloys.
Conclusion: There is no significant difference between cytotoxicity of two base metal alloys and polishing and firing can decrease cytotoxicity of both alloys.
A. Mirfazaelian , H. Siadat ,
Volume 19, Issue 1 (3 2006)
Abstract
Dentistry has always benefited from photography as an adjunct tool in diagnosis treatment planning and presentations. The main reason for taking dental photographs is to provide documents and supplements for treatment. A photograph facilitates communication between dentists and laboratories. Quality control will become more important to dental practice in near future and photographs can be used by dentists as self-checking tools. Nowadays performing lectures or publications without presenting pictures is inconceivable.
The camera system must be easy to use and accessories should be always available. Although a good variety of equipments are now available and can be used for close-up photography, the special requirements of dental clinical photography are not always provided by the manufacturers and dealers' recommendations are not always correct. This article tries to help the readers to find and use the most suitable equipments for their routine dental practice.
A. Mirfazaelian , H. Siadat ,
Volume 19, Issue 2 (4 2006)
Abstract
In addition to the camera, other accessories such as retractors and mirrors are necessary for intraoral photography. They enable directly inaccessible subjects, to be viewed and photographed easily. Gaining adequate view, by suitable retractors and mirrors, is the most important step, requiring skill and patient cooperation to achieve successful results. Composition, visualization of the final photograph and a carefully controlled clinical technique must be practiced in order to produce rapid, precise and reproducible clinical photographs. There are many procedures to be followed and precautions to be taken in order to obtain good quality, reproducible dental photographs. Failures can be avoided by following a distinct procedure. This article focuses on clinical equipments such as retractors, mirrors and intraoral photography.
A. Mirfazaelian , H. Siadat ,
Volume 19, Issue 3 (4 2006)
Abstract
Dental portraits are predominantly used for orthodontics, orthognathic surgery and prosthetic dentistry. If these images are to be used for documentation, then the patient must be positioned in accordance with strict guidelines for further references. If the images are to be used to present an aesthetic impression of dental treatment there is more flexibility in positioning the patient. Dental photography is used to make pictures of teeth and surrounding tissues, radiographs, casts and other objects. In this section, standard principles for portrait pictures are explained.
H. Siadat , A. Mirfazaelian ,
Volume 19, Issue 4 (6 2007)
Abstract
Object photography in dentistry including dental instruments, models, teeth and gross specimens has some special features and needs special onsideration. These objects are usualy very small, highly usually reflective and often with very bright surfaces. They need special lighting and other accessories for acceptable results. On the other hand, in laboratories and dental clinics we haven't enough time for taking photographs.The purpose of this article is to introduce the inciples of object photography in dentistry.
H. Siadat, A. Mirfazaelian , M. Alikhasi , M. Mohammad Alizadeh ,
Volume 20, Issue 4 (5 2008)
Abstract
Background and Aim: An important criterion for success assessment of implant-supported prostheses is marginal fit. Vertical and horizontal discrepancy can result in loosening of the prosthetic screw, crestal bone resorption, peri-implantitis and loss of osseointegration. Despite careful attention to waxing, investing, and casting, marginal discrepancies are inevitable. The aim of this study was to evaluate the marginal gap and overhang in three casting methods with two different alloys in ITI implants.
Materials and Methods: In this experimental in vitro study 48 analog abutments were randomly divided into six groups as follows: 1) burn out cap + BegoStar, 2) impression cap + BegoStar, 3) conventional wax up + BegoStar, 4) burn out cap + Verabond2, 5) impression cap + Verabond2, 6) conventional wax up + Verabond2. Waxing was done in 0.7 mm thickness verified by a digital gauge and a putty index was made for all groups. Reamer was used for correction of the finish line after casting in all groups. Castings were seated on analog abutments and embedded in acrylic resin. Specimens were sectioned by isomet instrument and polished and cleaned by ultrasonic cleaner for 10 min. The marginal gap and overextended margins of castings were examined under a Scanning Electron Microscope (SEM) (X200). The mean gap and margin overextension were calculated for each group. Data were analyzed by multivariate analysis and Bonferroni post-hoc test with p<0.05 as the level of significance.
Results: No significant difference in gap size was observed among the three casting methods with two alloys (P=0.056). The marginal gap was not different in the studied casting methods (P=0.092). Gold alloy crowns showed lower marginal gaps compared to base metal alloy crowns (P<0.001). No significant difference in overhang size was observed among casting methods with two alloys (P=0.093). Base metal alloy crowns showed less overhang compared to gold alloy crowns (P<0.001). There was a significant correlation between overhang and use of impression cap in base metal alloys (P<0.001).
Conclusion: Based on the results of this study, vertical discrepancy of frameworks made with gold alloy were less than those made with base metal alloy. Base metal alloy demonstrated less overhang. Conventional wax up or using burn out caps produced less horizontal discrepancy.
H. Siadat, R. Ghoveizi, A. Mirfazaelian, Gh. Ommati Shabestari, M. Alikhasi,
Volume 22, Issue 2 (20 2009)
Abstract
Background and Aim: The aim of this clinical study was to determine the effectiveness of progressive loading procedures on preserving crestal bone height and improving peri-implant bone density around maxillary implants restored with single crowns by an accurate longitudinal radiographic assessment technique.
Materials and Methods: Eleven Micro-Thread Osseo Speed dental implants were placed in 11 subjects and permitted to heal for 6 weeks before surgical uncovering. Following an 8-week healing period, implants underwent a progressive loading protocol by increasing the height of the occlusal table in increments from adding acrylic resin to an acrylic crown. The progressively loaded crowns were placed in 2 mm infraocclusion for the first 2 months, light occlusion for the second 2 months, and full occlusion for the third 2 months. At forth 2 months, a metal ceramic crown replaced the acrylic crown. Digital radiographs of each implant were made at the time of restoration, then after 2, 4, 6, 8, and 12 months of function. Digital image analysis was done to measure changes in crestal bone height and peri-implant bone density.
Results: The mean values of crestal bone loss at 12 months were 0.11 ± 0.19 mm, and when tested with Friedman across the time periods, the differences were not statistically significant (p> 0.05). The mean values of bone density in the crestal, middle, and apical area were tested with Repeated Measure ANOVA across the time periods, the differences were statistically significant (p<0.05).
Conclusion: Progressive loading doesn’t cause crestal bone loss. The peri-implant density measurements of the progressively loaded implants show continuous increase in crestal, middle and apical peri-implant bone density by time.
R. Ghoveizi, Gh. Omati Shabestari, A. Mirfazaelian, R. Sadrimanesh, A. Mangali,
Volume 23, Issue 1 (22 2010)
Abstract
A procedure was explained to fabricate a surgical stent to aid the placement of maxillofacial implants for prosthetic auricular rehabilitation. An impression of the defect was made, and a wax pattern of the missing ear completed and evaluated on the patient. The definitive wax prosthesis was processed in clear acrylic resin. Also an occlusal maxillary splint was fabricated and joined to the acrylic resin ear by using an extraoral acrylic resin bar. Surgical stent provides proper orientation of the acrylic resin ear while remaining attached to the maxillary arch. This surgical stent can also be used for radiographic examination.
