Showing 116 results for Reza
Neda Moslemi, Mohadeseh Heidari, Reza Fekrazad, Hanieh Nokhbatolfoghahaie, Siamak Yaghobee, Ahmadreza Shamshiri, Mozhgan Paknejad,
Volume 27, Issue 1 (4-2014)
Abstract
Background and Aims : Free gingival graft is one of the most predictable procedures for gingival augmentation, but patient’s discomfort and pain during healing period of palatal donor site is a significant concern. The aim of this study was to evaluate the effect of 660nm low power laser on pain and healing in palatal donor sites.
Materials and Methods: The present split mouth randomized controlled clinical trial was performed in 12 patients at the department of periodontics of Tehran University of Medical Sciences. Patients’ allocation was done by balanced block randomization (laser group and placebo group). In laser test group (wave length: 660 nm, power: 200mW, time of irradiation: 32s) was applied immediately post-surgery and in day 1, 2, 4 and 7 after that. In the control group, laser application was done with off power mode. Evaluation of epithelialization and healing was done with H2O2 and photograph. The number of palliative pills and bleeding was recorded. Wilcoxon test was used to analyze healing during the study. Patient’s pain during study was analyzed using repeated measure ANOVA. Mc Nemar test was used to analyze bleeding. Level of statistical significance was set at 0.05.
Results: Laser group showed better epithelialization (P=0.02) and healing (P=0.01) in day 14 after surgery and showed better epithelialization in day 21(P=0.05). No statistically differences were observed between laser group and control group in terms of bleeding and medication (P=0.51), (P=1).
Conclusion: According to the results of this study, the low power laser can promote palatal wound healing during the second and third week after free gingival graft procedures.
Hadi Asgharzadeh Shirazi, Mohammadreza Mallakzadeh,
Volume 27, Issue 2 (6-2014)
Abstract
Background and Aims: Hydroxyapatite coating has allocated a special place in dentistry due to its biocompatibility and bioactivity. The purpose of this study was to evaluate the relation between the hydroxyapatite thickness and stress distribution by using finite element method.
Materials and Methods: In this paper, the effect of hydroxyapatite coating thickness on dental implants was studied using finite element method in the range between 0 to 200 microns. A 3D model including one section of mandible bone was modeled by a thick layer of cortical surrounding dense cancellous and a Nobel Biocare commercial brand dental implant was simulated and analyzed under static load in the Abaqus software.
Results The diagram of maximum von Mises stress versus coating thickness was plotted for the cancellous and cortical bones in the range between 0 to 200 microns. The obtained results showed that the magnitude of maximum von Mises stress of bone decreased as the hydroxyapatite coating thickness increased. Also, the thickness of coating exhibited smoother stress distribution and milder variations of maximum von Mises stress in a range between 60 to 120 microns.
Conclusion: In present study, the stress was decreased in the mandible bone where hydroxyapatite coating was used. This stress reduction leads to a faster stabilization and fixation of implant in the mandible bone. Using hydroxyapatite coating as a biocompatible and bioactive material could play an important role in bone formation of implant- bone interface.
Hoorieh Bashizadeh Fakhar, Hanieh Kaviani, Mehrdad Panjnoosh, Ahmad Reza Shamshiri,
Volume 27, Issue 2 (6-2014)
Abstract
Background and Aims: It is crucial to verify the relationship between root apices and maxillary sinus floor in some surgical procedures like extraction and implant placement or in orthodontic movements like intrusion. Protrusion of roots into the sinus increases the risk of post extraction pneumatization which in turn decreases the available bone at the implant or denture sites. The aim of this study was to determine the panoramic radiology accuracy for defining the relationship between posterior root apices and the maxillary sinus floor by Cone Beam CT (CBCT).
Materials and Methods: Paired panoramic radiographs and CBCT images of 117 subjects were examined. 452 posterior maxillary roots including second premolar, first and second molar were classified by the means of the relationship with maxillary sinus floor. CBCT was used as Gold standard method, and the agreement of panoramic findings with CBCT was examined statistically. Data were analyzed using Chi-square and Multiple logistic regressions.
Results: Agreement of the panoramic and CBCT results were seen in 57.7% of all cases. Roots which had no contacts with the sinus floor (class 0) showed a high agreement of 89.5% between two imaging techniques. Roots in contact with sinus floor (class 1) showed 58.8 % and cases with root protrusion into sinus cavity (class 3, 4) showed 50% of agreement (P<0.001). Also in 36% of cases with no protrusion into the sinus cavity (class 0, 1, 2), panoramic showed protrusion. The agreement for the premolar was higher than molars (P<0.001)
Conclusion: The majority of roots which their images were projected on the sinus cavity had no vertical protrusion in CBCT cuts. Considering the results, in these cases CBCT can be recommended.
Ahmad Jafari, Masoud Kiani, Mahin Nikkhah, Ronak Bakhtiari, Yahya Baradaran Nakhjavani, Ali Reza Heidari,
Volume 27, Issue 3 (9-2014)
Abstract
Background and Aims: Considering the complications of root canal system, debridement would not be effective only by mechanical instrumentation. Therefore, root canal irrigants with the antimicrobial effect that can eliminate more microorganisms during treatment, becomes important. The aim of this study was to compare the antimicrobial effects of 2% thyme essence, 2.5% sodium hypochlorite (NaClO), and normal saline as root canal irrigants for primary molar teeth.
Materials and Methods: This study was performed on 34 primary molars. Subjects were randomly divided into three groups (N=10). The root canals of the teeth were prepared up to the file #35 and all of the specimens were sterilized, and were then contaminated with entrococccus faecalis suspension (Enterococcus Faecalis ATTC 29212). After 48 hours of incubation, the specimens of each group were irrigated with corresponding irrigants. Then, the microbial specimens were collected with sterile paper points. After incubation, the numbers of Colony Forming Units (CFU) were counted using colony counter. Data were analyzed using Smirnov-Kolmogorov, Kruskal-Wallis and Mann-Whitney tests.
Results: Sodium hypochlorite showed the highest antimicrobial effect and showed significant differences compared with normal saline (P<0.001). However, the differences were not significant with thyme essence 2% (P=0.3).
Conclusion: Thyme essence could be considered as a natural irrigator with a comparable antiseptic effect to sodium hypochlorite.
Mehrdad Panjnoosh, Farnoosh Taghavi, Ahmad Reza Shamshiri,
Volume 27, Issue 3 (9-2014)
Abstract
Background and Aims: There is a risk of nerve injury during the extraction of the impacted third molars, in cases with proximity of the inferior alveolar nerve and this tooth. The aim of this study was to evaluate the effect of different various factors on the degree of vulnerability using CBCT (Cone Beam Computed Tomography) imaging technique.
Materials and Methods: CBCT images of 191 patients referred for the exact assessment of the relationship between the mandibular canal and impacted mandibular third molars were selected. The position of these anatomical structures was evaluated at their contact point. The possible effect of gender, impaction form of the third molars, anatomical relationship between the third molars and the mandibular canal and the age differences were studied. Data were analyzed using Chi-square and Student’s t-test.
Results: There was a close relationship between the mandibular canal and impacted third molars in 81.7% of the patients. The contacts were shown to be significantly higher in females than males (P=0.01) and in the cases with the lingually position of the third molar and the mandibular canal (P<0.001). However, the age and impaction form of the teeth did not have a significant influence (P>0.05).
Conclusion: The risk of nerve damage or exposure is increased in females and lingual position of the mandibular canal to the third molar in cases with higher proximity between these 2 structures in panoramic radiographs using CBCT images. Therefore, the surgeon must pay enough attention in these cases of third molar extraction.
Mohamadreza Khami, Arezo Ebne Ahmadi, Mina Ahmadian, Samaneh Razeghi, Reza Yazdani,
Volume 27, Issue 3 (9-2014)
Abstract
Background and Aims: Tobacco kills 5 million people worldwide annually, according to the Health Ministry reaches this number is about 70,000 people a year in Iran. Dental professionals are in a unique position to promote smoking cessation due to the opportunity for regular interaction with their patients. The aim of this study was to investigate knowledge, attitudes, and skills of dental students at Tehran and Shahid Beheshti dental schools towards tobacco cessation counseling in dental office.
Materials and Methods: In this cross-sectional study, the target group was dental students at Tehran and Shahid Beheshti dental schools, and the sampling method was census. A questionnaire on the knowledge, attitudes, and skills towards tobacco cessation counseling in dental practice was administered to the students (n=93). Data were analyzed using T-test.
Results: The response rate was 100% (93 students participate in this program and all of them filled the questionnaire). The average score of knowledge at Tehran and Shahid Beheshti dental schools was 17.5 and 18.4, respectively (P=0.09), the average score of attitudes was 33.5 and 33.1, respectively (P=0.80). There were no significant differences between the two dental schools in these parts. The average score of skill was 11.9 and 16.6, respectively. The differences between the students of two dental schools in skill were significant (P=0.002).
Conclusion: Although the attitude of dental students at Tehran and Shahid Beheshti schools towards tobacco cessation counseling seemed to be fair, some deficiencies existed in their knowledge and skill. Dental education programs should be implemented properly in this field.
Davari Abdolrahim , Daneshkazemi Alireza , Modaber Maryam , Malekzadeh Mohammad ,
Volume 27, Issue 4 (1-2015)
Abstract
Background and Aims: The most effective preventing tooth decay method is fluoride compounds applications. Some studies suggested that APF gels caused changes on the superficial physical properties of composite. Therefore, the purpose of this study was to evaluate the marginal microleakage of class V composite restorations before and after AFP gel application.
Materials and Methods: The class V cavities in buccal surfaces of 45 molar teeth were made in such a way that occlusal margin was placed in enamel and cervical margin in cement. In group 1, at first fluoride-therapy and then cavity preparation and restoration by composite resin was done. In group 2, at first the class V cavities were prepared and restored, then fluoride-therapy was carried out. In group 3, cavities were prepared and restored with no fluoride-therapy. The dye penetration rate in occlusal and cervical margins was examined by stereomicroscope. Data were statistically analyzed using Kruskal-Wallis and Mann-Whitney test.
Results: There was no statistically significant difference between groups ( P=0.975).
Conclusion: Fluoride-therapy using AFP gel before and after class V composite restorations, had no significant effect on the microleakage of dentin and enamel margins.
Arami Sakineh , Aghasadeghi Mohamadreza , Tabatabaie Masome Hasani , Darvishpour Hojat , Sheikhzadeh Sedigheh ,
Volume 27, Issue 4 (1-2015)
Abstract
Background and Aims: Hepatitis B is an important infection route in dentistry requiring different disinfectants to prevent its transmission. The aim of this study was to compare the effects of chemical disinfectants (FD366, ISORAPID and 5% sodium hypochlorite 2/100) to remove Hepatitis B infections from the dental surfaces.
Materials and Methods: In this experimental laboratory trial, serum of 10 HBV patients was poured into microtubes, FD366, ISORAPID and hypochlorite disinfectants were added to them. PCR experiments with viral diagnostic kits were used to diagnose the virus genome. Real time PCR was used to evaluate after incubation with the disinfectants. The reductions occurred in the viral load of Hepatitis B were statistically analyzed using Kruskal-wallis and Mann-Whitney U tests .
Results: No significant antiviral efficacy was noted following the application of FD366 and ISORAPID disinfectants (P=0/07). However, hypochlorite showed the most efficacy to disinfect Hepatitis B and a significant difference was found among them (P<0.0001).
Conclusion: Under the study limitations, FD366 and ISORAPID disinfectants did not show adequate efficacy to remove Hepatitis B virus. Hypochlorite was the most effective disinfectant.
Haghgoo Roza , Haghgou Hamid Reza , Abbasi Farid , Tavakkoli Mohammad ,
Volume 27, Issue 4 (1-2015)
Abstract
Background and Aims: The main cause of erosion is acid exposure . Side effects of erosion necessitate therapeutic agents’ uses. The aim of this study was to investigate the effects of nano- hydroxy apatite in tooth remineralization following exposure to soft beer.
Materials and Methods: This in vitro experimental study was conducted on 18 human impacted third molars that had been surgically extracted. The microhardness of specimens was measured. Then teeth were exposed to soft beer and their secondary microhardness was measured. The teeth were divided into 2 groups (water and nano-hydroxy apatite solution) and were placed on 9 orthodontics appliances and delivered to 9 volunteers. These volunteers placed the tooth on one side in water for 5 minutes and the tooth in opposite side in nano-hydroxyapatite solution. This application was repeated 6 times a day for 10 days. The microhardness of teeth was measured again. Data were analyzed using Paired T-test.
Results: The tooth enamel microhardness reduced after exposure to soft beer significantly (P=0.04). The microhardness of 9 teeth after being in water showed significant changes (P=0.012). The microhardness of 9 teeth significantly changed after exposure to nano -hydroxyapatite solution (P=0.001) .
Conclusion: Based on the results of this study, 10% solution of nano- hydroxy appatite could restore the erosive lesions .
Shirazi Mohsen , Darvishpour Hojat , Nateghi Reza , Mirhashemi Amir Hosein , Salari Behzad ,
Volume 28, Issue 1 (5-2015)
Abstract
Tehran University of Medical Sciences, Tehran, Iran ( mirahashemi@tums.ac.ir )
Background and Aims: Nowadays patients refer to orthodontist for issue such as dental crowding and other aesthetic problems. The aims of this study were to evaluate the relationship between some of mandibular anatomical landmarks and dental crowding in the patient with skeletal Cl II due to mandibular deficiency.
Materials and Methods: 108 cases have been randomly selected out of patients with mandibular related Cl II problem associated with lower incisor crowding, out of orthodontic patient department of Tehran university of medical sciences. ANB, SNB, mandibular discrepancy, gonial angle, Sn-Go-Gn and IMPA was evaluated out of the data. Lateral cephalograms were used for this matter. The correlation between variables was evaluated by correlation test and after reviewing the data was analyzed using Normality test, the Pearson correlation coefficient was used for normally distributed variables.
Results: Corpus-ramus length ratio had a significant relationship with dental crowding (P≤0.05) but there was no meaningful and significant relationship between other facial landmarks ( P = 0.26 ).
Conclusion: there seems to be a slight relationship between facial landmarks and dental crowding in lower incisors. But further case control and clinical studies may be helpful in achieving more reliable data.
Sara Ghadimi, Mohammad Reza Khami, Samaneh Razeghi,
Volume 28, Issue 1 (5-2015)
Abstract
Background and Aims: Despite significant decline in dental caries in recent decades, the disease remains a
public health problem especially in developing countries. In recent years combined application of laser and
fluoride has been introduced as a new caries-preventive measure. The purpose of the present study was to review
the literature on the preventive effect of combined application of laser and fluoride on the dental caries.
Materials and Methods: PubMed, Google Scholar and EMBASE databases were searched for articles published
from 1990 to November 30, 2013. Various combinations of the following keywords were used: Dental caries,
Laser, Fluoride, Fluoride therapy, Prevention and Enamel. The inclusion criteria included all levels of available
evidence. Articles published only in english language were evaluated, and unpublished data were not sought.
Results: Several studies evaluating the effect of laser alone or combined with topical fluoride to prevent dental
enamel demineralization were found. Studies assessing the combined effect were more frequently done on
permanent teeth and just a few studies were done on primary teeth. In total, most of the studies confirmed that
combined application of laser and topical fluoride has a remarkable effect in prevention of enamel
demineralization compared to application of each of them alone.
Conclusion: Laser irradiation combined with topical fluoride application seems to provide the best prevention
effect on the dental caries initiation and progression in enamel of permanent teeth. However, more experimental
and clinical studies are necessary to be done on the primary teeth in this area.
Mahmod Kazemi, Alireza Pornasrollah, Somayeh Allahyari, Hamid Jalali,
Volume 28, Issue 2 (7-2015)
Abstract
Background and Aims: Adequate retention has significant importance in the prognosis of implant supported cemented the restorations. Limited literature had evaluated the effect of direct wax up or use of plastic coping on the retention of these restorations. This aims of this study was to compare the retention of castings fabricated by the plastic coping and direct wax up for single crown and bridge in three implant systems.
Materials and Methods: 28 specimens of each implant systems were randomly divided into 4 groups. Groups included wax patterns for single crowns and bridges that were made from plastic coping or direct wax up. All the wax patterns were invested and casted with base metal alloy, in similar conditions. After castings were cemented to the related abutments, the specimens were subjected to a pull out force in a universal testing machine at a cross head speed of 0.5 mm/min. The load required to decement each casting was recorded and the mean values for each group were calculated. Data were analyzed using three-way ANOVA.
Results: Comparing the between systems in crowns fabricated from plastic coping, there was no significant difference between Replace and Implantium (P=0.124), but ITI had significantly lower values than that of other systems (P<0.001 Comparing the systems in crowns fabricated from direct wax up, Implantium had the greatest retention and ITI had the lowest retention (P<0/001). Comparing the bridges with both method, Replace had the greatest retention and ITI had the lowest retention.
Conclusion: Implantium and Replace system exhibited the highest retention for fabricating crowns, and bridges, respectively.
Abdolrahim Davari, Soghra Yassaei, Alireza Daneshkazemi, Mohadeseh Khosravanian,
Volume 28, Issue 2 (7-2015)
Abstract
Background and Aims: Orthodontic bracket failure during treatment is a common problem. With the introduction of low shrinkage composites the question is that whether: this sufficient has coefficient bond strength for bonding bracket during orthodontic treatment. The aim of this study was to compare the shear bond strength (SBS) of silorane-based and metacrylate-based composites to metal brackets.
Materials and Methods: 30 human premolar teeth were collected and divided into 2 groups. In group 1, 15 orthodontic brackets were bonded using silorane-based composite, in group 2, 15 orthodontic brackets were bonded using metacrylate-based composite. The shear bond strength of each specimen was determined in an Instron machine. Amount of residual adhesive remaining on each tooth was evaluated using a stereomicroscope. Data were analyzed using T-test to compare the shear bond strength between groups and LSD method to compare the Adhesive Remnant Index (ARI) scores.
Results: There was significant difference in the SBS between the test groups (P<0.001). The mean bond strength of bonding brackets to silorane-based composite was (42.42 ± 7.03) MPa, and the mean bond strength of bonding brackets metacrylate-based composite was (21.08±2.97 ) MPa. No significant difference in the ART was found between groups (P=0.66).
Conclusion: Silorane-based composite provided higher bond strength to orthodontic metal brackets.
Mehdi Araghbidikashani, Elham Esmaili, Gholamreza Eslami, Mohsen Nuori, Hasan Ghaffari, Abbas Salehi,
Volume 28, Issue 2 (7-2015)
Abstract
Background and Aims: The aim of this descriptive longitudinal study was to determine the type of teeth that were more prone in accidental bracket debonding and also to investigate the relationship between broken bracket bond and intervening factors such as age, type of malocclusion and sex.
Materials and Methods: We used a pilot study to determine the correct sample size for this study. According to the pilot study which consisted of 20 records of patients, it was concluded that 576 patient’ records was needed. The mean time for a bracket before it fails was also measured using Kaplan-Meier method. Cox regression analysis was done to examine the effect of age, gender, and class of malocclusion on each tooth with broken bracket. Data were analyzed using the software SPSS 20.
Results: Results showed that the percentage of unexpected broken bracket bond for each tooth varied and they were significantly related only in second premolars in both jaws with malocclusion that was different for each tooth (P=0.037, P=0.004).
Conclusion: Maxillary second premolars and mandibular second premolars had the highest rate of unexpected broken bracket bond in CL II CL I malocclusion respectively. Age, gender and malocclusion had no effect on the unexpected broken bracket bond for other teeth.
Alireza Daneshkazemi, Abdolrahim Davari, Farnaz Farahat, Neda Pazhoohi,
Volume 28, Issue 2 (7-2015)
Abstract
Background and Aims: The purpose of this study was to compare the effect of chlorhexidine 2%, ethanol 70% and sodium ascorbate 10% and delayed bonding for 1 week on the shear bond strength of composite resin to enamel after bleaching.
Materials and Methods: 90 human central incisors were divided into 6 equal groups: Group 1: no bleaching Group 2: bleaching with carbamide peroxide 45% for 45 minutes Group 3: bleaching + restoring specimens in distilled water for 1 week. In group 4, 5 and 6, after bleaching, 1 cc of chlorhexidine 2%, ethanol 70% and sodium ascorbate 10% were applied for 15 minutes. Composite cylinders were bonded on the buccal surfaces. Specimens were thermocycled for 1000 cycles and the shear bond strength test was done. Specimens were examined under stereomicroscope and SEM. Data were analyzed a sign ANOVA and Bonferroni test.
Results: The shear bond strength values were not significantly lower in the bleached teeth (group 3, 4, 5 and 6) than that of negative control group (group 1) (P=1.000, P=0.069, P=0.081, P=1.000) Bonferroni test results show significant difference between test groups (3, 4, 5 and 6) and group 2 (P<1.000, P=0.007, P=0.008, P<1.000) Under SEM, resin tags in group 2 was thinner and lesser than group 3, 4, 5 and 6. The most adhesive failures were in group 2.
Conclusion: Bleaching with carbamide peroxide and immediate bonding of composite decreased the shear bond strength. Sodium ascorbate 10% and delayed bonding for 1 week were the most effective way.
Allahyar Geramy, Amir Hossein Mirhashemi, Sahar Rafiei Chokami, Ahmadreza Shamshiri,
Volume 28, Issue 3 (10-2015)
Abstract
Background and Aims: Cl II malocclusion is one of the most common abnormalities in human societies and using a simple, affordable and accessible treatment that can be provided by general practitioners or specialists, to prevent future malocclusion complications is vital
. Cl II malocclusion treatment using functional appliances such as twin block and anterior inclined bite plan have less cost, side effects and complications compared to fixed orthodontic or orthosurgery
. Until now, the dentoskeletal changes resulting from the application of twin block and anterior inclined bite plan in patients with Class II malocclusion has not been evaluated. The objective of the present study was to assess the dentoskeletal changes following the use of twin-block functional appliance and inclined anterior bite plan in the patients with class II malocclusion div 1 during mixed dentition.
Materials and Methods: In this retrospective cohort trial, 60 patients with the definitive diagnosis of Class II div. 1 malocclusion having ANB>2 and FMA angel between 20 and 30 and without any previous treatment or syndrome who were treated with twin-block or inclined anterior bite plan appliance were selected and their lateral cephalometries were traced before and after treatment. Selected distance and angular landmarks were measured on the cephalograms with the good reliability (ICC=0.953) and the changes occurred in the landmarks were statistically analyzed using Student t test.
Results: Due to the increased mandibular growth, most of the landmarks experienced significant changes following the treatment with twin-block and inclined bite plan (P<0.05). The appliances corrected Class II malocclusion through improvement of mandibular length and position, maxillary and mandibular skeletal and dental relationships (decreased ANB angle and overjet) and stability of mandibular plan inclination. No significant differences were found between the devices regarding most landmarks changes (P>0.05), however, SNA (P=0.04), overjet (P=0.007) and wits appraisal (P=0.004) changed differently after using the appliances.
Conclusion: Despite with most similarities of both twin-block and anterior inclined bite plan to correct class II div. 1 malocclusion, Due to the advantages of anterior inclined bite plan such as less size, good patient cooperation and simple laboratory preparations the appliance can be used as substitute for complex functional appliances to correct class II div. 1 malocclusion before the growth spurt.
Reza Masaeli, Tahereh Sadat Jafarzadeh Kashi, Farhad Shafiei,
Volume 28, Issue 3 (10-2015)
Abstract
Poly (lactic-co-glycolic acid) is a biodegradable polymer which has used in a different fields of medical applications. As PLGA is approved by FDA(food and drug administration) the range of this usage is increasing in comparison to the past. Particularly, PLGA are also developed for the dental field in the form of scaffolds, films, membranes, microparticles, or nanoparticles. PLGA scaffolds have been used to regenerate damaged tissues together with stem cell-based therapy. There is solid evidence thatthe development of PLGA microparticles and nanoparticles may be beneficial to a wide range of dental fields such as endodontic therapy, dental caries, dental surgery, dental implants, or periodontology. The aim of the current paper was to review the recent advances in PLGA materials and their potential uses in Dentistry via exploring related literature during 2004 till 2016 in Science Direct and PubMed.
Nasrollah Jabbari, Seyyed Reza Mousavi, Kamal Firoozi,
Volume 28, Issue 4 (1-2016)
Abstract
Background and Aims: With the increasing use of CT (Computed Tomoghraphy) scans in dentistry especially in the implantology, there may be significant increases in the radiation exposure and its risk. During the last year’s ConeBeam Computed Tomoghraphy (CBCT) has been introduced as an imaging modality for dentistry. The aim of this review article was to present comprehensive information have been published, regarding the radiation dose and image quality of Conventional Multislice Computed Tomography (MSCT), Cone-Beam CT (CBCT) and periapical radiography in dentistry imaging.
Materials and Methods: A review of the literature was carried out in PubMed, Google Scholar, Science Direct and Scopus database using key words (CBCT, MSCT, periapical radiography, radiation dose of dentistry and image quality). These searches were limited to the articles published between the years of 1993 to 2015.
Conclusion: In comparison to MSCT, CBCT had a short scanning times and lower radiation dose, but in comparison to periapical radiography, CBCT had higher radiation dose. In contrast, CBCT with flat panel detector had higher spatial resolution to MSCT. The periapical radiography also had a good image contrast and relatively high resolution. Generally, CBCT was suitable for hard tissue imaging and MSCT was preferred for soft tissue imaging.
Abbas Majdabadi, Mona Ahadi, Reza Fekrazad,
Volume 29, Issue 1 (7-2016)
Abstract
Background and Aims: Nowadays lasers are used as alternatives to the tooth preparation because of reducing pain and bloodshed. The aim of this study was to observe the effect of ArF laser on the dental hard tissues.
Materials and Methods: For this research human molar teeth with no caries or dental restoration and enamel cracks were used. Irradiation laser energies were taken 95, 70 and 50 mJ for enamel and 80, 70 and 50 mJ for dentine. Then, for each of energy values pulse numbers (repetition rate) were adjusted at 200, 400, 600, 800, 1000 and 1500. Ablation was carried out without water spray on both enamel and dentine. Finally, the dimensions of ablated areas were measured by using a camera connected to the computer and results were applied in graphs.
Results: For each energy value, the ablation dimension increased by increasing pulse numbers. Ablation depth in dentine was more than that of for enamel. Trends of graphs for dentine and enamel were the same. SEM images of ablations by 95 mJ energy on enamel and 80 mJ energy on dentine showed sharp edges.
Conclusion: Ablation depths increased by increasing pulse numbers, for each energy level. However, this increase was not that as expected, because the lack of water spray while irradiating.
Narges Ameri , Hakimeh Siadat, Ahmad Reza Shamshiri, Marzieh Alikhasi,
Volume 29, Issue 2 (11-2016)
Abstract
Background and Aims: Marginal accuracy is a crucial factor influencing the clinical long-term reliability of implant-supported fixed dental prostheses (FDPs). The aim of this in vitro study was to evaluate the marginal fit of three-unit zirconia bridge frameworks fabricated using two different computer-aided design (CAD)/
computer-aided manufacturing (CAM) systems (AmannGirrbach and Zirkonzahn).
Materials and Methods: The master model of 3-unit FDP was made of two implant abutments (AmannGirrbach and Zirkonzahn) from canine to second premolar. Twelve frameworks were manufactured using each fabricating system from semi-sintered zirconia blanks, which had to be sintered for final density after milling. After manufacturing, the absolute marginal discrepancy in each abutment were determined by means of Video Measurement System (VMS). The data were analyzed, using independent and paired t test (P=0.05).
Results: For the premolar abutment, the absolute marginal discrepancy of frameworks fabricated by AmannGirrbach system was significantly greater than those of the other system (P=0.005). There was no significant difference between the marginal discrepancy of canine and premolar abutments (P>0.05).
Conclusion: Within the limitations of this study, it could be concluded that the marginal fit of zirconia FDPs was significantly dependent on the CAD/CAM system used, but the abutment size was not an effective factor.
