Showing 20 results for Rahimi
F. Baghaei-E- Naeini , M. Ebrahimizadeh ,
Volume 12, Issue 1 (9 1999)
Abstract
Odontoma is an odontogenic lesion with epithelial and mesenchymal origin and is composed of differentiated dental parts. Than because of abnormal organization of mature tissues. It seems that it is a hamartoma rather than real tumor. Odontoma is seen in two types of compound & complex.Out of 57 studied cases, 31 cases (54.2%) were of complex type 12 cases (21 %) were compound & 8 cases were of cystic. The age of incidence ranged from 5.5 to 68 years. The mean age in complex odontoma was 27 years & compound type was 19 years. There was no significant difference regarding the sex in the complex type. In compound odontoma women were affected 2 times more than means.Complex type are found in mandibular posterior era ereas more and compound type in anterior regions .In this studied found 12 cases impaction teeth.
Sh. Jafari , N. ebrahimi-E- Daryani , S. Zeinali, M. motalleb Nejad ,
Volume 14, Issue 2 (9 2001)
Abstract
Helicobacter pylori infection causes gastric and duodenal ulcer. However recurrence of infection after eradication would suggest the existence of other reinfecting sources in the gastrointestinal tract (Gl). The aim of this study was to assess the existence ofhelicobacter pylori in dental plaques of patients harboring Helicobacter pylori in their GI tract. Antral biopsies were taken from 40 patients with Gl problems and cultured. Samples were also taken from dental plaques of patients with positive Helicobacter pylori culture under microaerophilic conditions and evaluated by polymerase chain reaction (PCR) reamplification. The mean age of patients was 40 years 24 (60%) male and 16 (40%) female. The results obtained from dental plaque cultures, which analysed by PCR were all negative, however 7 (17.5%) cases were found positive by PCR reamplification. The results showed that Helicobacter pylori could exist in dental plaque and PCR reamplification could be used for its detection as a more sensitive technique. More research should be conducted to examine any relation between the existence of Helicobacter pylori in dental plaques and recurrent GI disorders.
B. Ebadian , R. Mosharaf , M. Ebrahimi ,
Volume 16, Issue 4 (9 2004)
Abstract
Statement of Problem:Iranian product, Acropars autopolymerizing acrylic resin is nowadays widely used in dental prostheses. Dimensional change is a common problem among Iranian made acrylic resins in making custom trays and record bases, seems to be more than the similar foreign products. In order to achieve a technique for making a record base with minimum dimensional changes, more research is necessary.
Purpose: The aim of the present study was to determine a curing technique for Iranian autopolymerizing acrylic resins leading to the least polymerization shrinkage and the most adaptation between record bases and stone casts.
Materials and Methods: In this experimental study, 40 stone casts were divided into four 10- member group. For each group, polymerization shrinkage was determined at three points with one of the following techniques: Bench curing, Curing under a coat of petroleum jelly , Curing in a monomer saturated atmosphere, Curing in boiled water. Adaptation between bases and stone casts were measured at three points (the right and left crests of the ridge and the midpalatal region) with a light-measuring microscope. To analyze
the data, Variance analysis was used.
Results: The monomer atmosphere technique showed the minimum dimensional changes and the samples in boiled water group had the maximum dimensional changes. No statistical differences were observed between other groups.
Conclusion: More adaptation between record bases and stone casts was observed in monomer atmosphere polymerization technique. The differences between bench curing and curing under a coat of petroleum jelly techniques with this method were not statistically significant. Therefore, it is suggested for making base records with maximum adaptation.
D. Goodarzi Pour , S. Ebrahimi Moghaddam ,
Volume 17, Issue 4 (7 2005)
Abstract
Statement of Problem: A few decades have past from using radiographic technology as an accurate paraclinical method and always protective measurements is applicated against ionizing radiation. As dental radiography is a routine procedure in dentistry the importance of protective strategies is clear.
Propose: The aim of this descriptive study is to evaluate the protection principles in centers which have intraoral radiographic devices in Yazd.
Material and Methods: We have considered all three aspects of practitioner, environment and patient protection using questionnaire and visiting those centers.
Results: 33/7% of dental offices ,10 clinics ,3 institution and faculty of dentistry had intraoral radiographic equipments. Stablishment of protection principles for radiographer was favorable. 7.7% of centers had x-ray room with leaded walls, 23.1% had curtain , in 69/2% of centers radiographers stood in correct position and distance while taking radiograph. Regarding to protection of environment, beams leakage control in 23.1% dental offices, 70% of clinics, all institution and faculty of dentistry have done.
Conclusion: Non of the centers used rectangular localizator, thyroid shield, film holder and just some centers used leaded apron in specific circumstances. We have concluded that patient protection constitute less consideration. Generally lack of protective consideration is related to deficient knowledge of operators. Lack of information about protection equipments causes decrease of demanding of these tools and ultimately lack of these equipments in the market.
S. Rahimi , B. Jodeiri ,
Volume 18, Issue 3 (11 2005)
Abstract
Background and Aim: The goal of endodontics is to seal the root canal system from the orifice to apical constriction completely and tridimensionally.Hence perforations during root canal therapy, because of caries or resorptions must be sealed and obturated with ideal materials. The aim of this study was to histologically compare two kinds of mineral trioxide aggregate Root MTA and Pro Root MTA for furcal perforation repair in developed teeth in dog.
Materials and Methods: In this experimental study, thirty teeth consisting of second, third and fourth mandibular premolars of five German shepherd dogs were selected. Twenty-four teeth were randomly divided into four experimental groups (6 teeth each). One pair of Root MTA and Pro Root MTA groups studied in one month and the other in three months intervals. Positive and negative control groups was each contained three teeth. In positive control group, perforations were not treated and negative control group contained intact teeth. In experimental groups perforations repaired after one week exposure to oral cavity with Root MTA or Pro Root MTA. After time intervals animals were subjected to vital perfusion and 6 m histologic sections were prepared. Inflammation and hard tissue formation were ranked by Cox criteria. Data were analysed using Mann-Whitney and Chi-Square statistical tests with P<0.05 as the limit of significance.
Results: There was statistically significant lower inflammation and higher hard tissue formation in three months Root MTA and Pro Root MTA groups compared to one month interval (P<0.05). There was no statistically significant difference in inflammation and hard tissue formation between Root MTA and Pro Root MTA in each intervals (P>0.05).
Conclusion: Mineral Trioxide Aggregate is an adequate material for furcal perforation repair in dog’s teeth. Root MTA could be a good substitute for Pro Root MTA considering the lower cost and similar characteristics.
H. Kermanshah , Sh. Farzin Ebrahimi,
Volume 20, Issue 2 (9 2007)
Abstract
Background and Aim: All ceramic, inlay-retained resin bonded fixed partial denture is a conservative method for replacement of missing teeth, because of minimal tooth reduction. The connector between the retainer and the pontic is the weak point of these bridges. Reinforcement of ceramic core will increase the clinical longevity. The aim of this study was to determine the effect of zirconia on flexural strength of IPS Empress 2 core ceramic.
Materials and Methods: In this experimental in vitro study, twenty eight bar shape specimens (17´3.1´3.1 mm) were made of four different materials: (1) Slip casting in-ceram alumina core (control group) (2) Hot-pressed lithium disilicate core ceramic (IPS Empress 2) (3) IPS Empress 2 with cosmopost (zirconia post) inserted longitudinally in the center of the bar (4) IPS Empress 2 with cosmopost (zirconia post) inserted longitudinally in bottom of the bar. Specimens were subjected to three-point flexure loading with the span of 15mm, at a cross-head speed of 0.5 mm/min. Failure loads were recorded and analyzed using one-way ANOVA and Tomhane Post-hoc tests and p<0.05 was set as the level of significance. Fractured surfaces were then observed by scanning electron microscope (SEM). Four additional samples were made as the third group, and zirconia-IPS interface was observed by SEM before fracture.
Results: Mean values and standard deviations of three point flexural strengths of groups 1 to 4, were: 378.4±44.6, 258.6±27.5, 144.3±51.7, 230±22.3 MPa respectively. All the groups were statistically different from each other (P<0.05), except groups 2 and 4. The flexural strengths of groups 2, 3, 4 were significantly lower than group 1. Group 3 had the lowest flexural strength. SEM analysis showed that the initiated cracks propagated in the interface of zirconia post and IPS Empress 2 ceramic.
Conclusion: Based on the results of this study, inserting zirconia post (cosmopost) in IPS Empress 2 ceramic does not reinforce all-ceramic inlay retained resin bonded fixed partial dentures.
N. Shadman, Sh. Farzin Ebrahimi, N. Molaie,
Volume 23, Issue 4 (20 2011)
Abstract
Background and Aims: This ex vivo study was done to evaluate the effect of different adhesive systems on microleakage of class V composite restorations.
Materials and Methods: Thirty extracted human third molar teeth were selected and class V cavities were prepared (3×3×1.5 mm) on buccal and lingual surfaces. Then, teeth were divided into 3 groups. Adhesives used in this study were Excite (Ivoclar/Vivadent), AdheSE(Ivoclar/Vivadent) and AdheSE-one Ivoclar (Vivadent/Vivadent). After application of adhesives, cavities were restored with a resine composite (InTen-S A1/ Ivoclar), in 3 increments and cured with QTH light curing unit (700 mW/cm). After 24 hours storage of teeth in 370C water, teeth were thermocycled (500 cycles in 5-550C) and stored in 1% basic fushin for 24 hours. After that, the specimens were rinsed with running water and mounted in a self-cured acryl. Finally, the specimens were sectioned and maximum depth of dye penetration for each restoration was measured using stereomicroscopy. The results were statistically analyzed with Mann-Whitney U test.
Results: In comparison between enamel and dentin margins in each group, microleakage in enamel margins were less than that of dentin margins. This difference was statistically significant in Excite and AdheSE-one groups (P=0.001, P=0.043). AdheSE showed the least microleakage in dentin margins however, there was no significant difference between 3 bonding agents (P=0.14). In enamel margins, there were significant differences between 3 bonding agents (P=0.001). Excite showed the lowest microleakage and AdheSE-one had the highest microleakage.
Conclusion: The least enamel microleakage was associated with the total-etch and least dentin microleakage was observed in the two-step self-etch adhesive system.
K. Ghazi Khanlou Sani, A. Eskandarlou, N Rostampour, A. Rahimi,
Volume 24, Issue 3 (21 2011)
Abstract
Background and Aims: The evaluation of absorbed dose received by patients could give useful information for radiation risk estimation. This study was performed to compare the entrance skin dose received by patients in cone beam computed tomography (CBCT), conventional and spiral computed tomography (CT).
Materials and Methods: In this experimental study, 81 calibrated TLD chips were used. the TLD chips were placed on facial, thyroid and end of sternum skin surface in patients referred for CT of the paranasal sinuses (3 TLD chips for each area) to estimate the absorbed dose received by central part of radiation field, thyroid and out of field areas, respectively. The data were analyzed using one-way ANOVA and Tukey tests.
Results: The dose delivered to the center of irradiated field was about 0.79±0.09 mGy in CBCT technique compared with 16.31±3.71 and 18.84±4.12 mGy for spiral and conventional CT, respectively. The received dose by the out of field areas was about 54 percent of central area dose. There was statistical significant relationship between the imaging modalities and absorbed dose received by patients (P=0.016). The least absorbed dose was for CBCT and the greatest dose was for conventional CT imaging technique.
Conclusion: The dose delivered to central area of irradiated field in conventional and spiral CT imaging modalities was about 24 times greater than of that in CBCT. Also, the highest received dose was for central area of radiated field and the lowest dose was for the out of field areas.
Niloofar Shadman, Shahram Farzin Ebrahimi, Arezo Abrishami, Hasty Sattari,
Volume 25, Issue 3 (1 2012)
Abstract
Background and Aims: The purpose of this experimental study was to investigate the shear bond strength of three new adhesive systems to enamel and dentin of permanent human teeth using three new etch and rinse and self-etch adhesive systems.
Materials and Methods: Sixty intact caries-free third molars were selected and randomly divided into 6 groups. Flat buccal and lingual enamel and dentin surfaces were prepared and mounted in the acrylic resin perpendicular to the plan of the horizon. Adhesives used in this study were Tetric N-Bond, AdheSE and AdheSE-One F (Ivoclar/Vivadent, Schaan, Liechtenstein). The adhesives were applied on the surfaces and cured with quartz tungsten halogen curing unit (600 mW/cm2 intensity) for 20 s. After attaching composite to the surfaces and thermocycling (500 cycles, 5-55ºC), shear bond strength was measured using a universal testing machine at a crosshead speed of 0.5 mm/min. The failure modes were examined under a stereomicroscope. The data were statistically analyzed using T-test, one-way ANOVA, Tukey and Fisher's exact tests.
Results: In enamel, Tetric N-Bond (28.57±4.58 MPa) and AdheSE (21.97±7.6 MPa) had significantly higher bond strength than AdheSE-One F (7.16±2.09 MPa) (P<0.0001). Tetric N-Bond had higher bond strength than AdheSE but there was not any significant difference between them (P=0.093). In dentin, there were significantly differences among all adhesives (P<0.001). Tetric N-Bond (20.62±3.03 MPa) showed the highest and AdheSE-One F (6.54±1.13 MPa) had the lowest value. The bond strength in enamel was higher than that observed in dentin and the difference was significant in Tetric N-Bond (P=0.044) and AdheSE (P=0.000) groups. There were no significant differences in the mode of failures among groups (P>0.05).
Conclusion: Shear bond strength to dentin in Tetric N-Bond (etch and rinse system( was higher than self-etch adhesives (AdheSE and AdheSE-One F). The bond strength to enamel and dentin in two-step self-etch (AdheSE) was higher than one-step self-etch (AdheSE-One F).
Marzieh Alikhasi, Mahnaz Arshad, Hakime Siadat, Susan Rahimian,
Volume 25, Issue 3 (1 2012)
Abstract
Background and Aims: Passive fit of prosthetic frameworks is a major concern in implant dentistry. Impression technique is one of the several variables that may affect the outcome of dental implants. The purpose of this study was to compare the three dimensional accuracy of direct and indirect abutment level implant impressions of ALL-ON-4 treatment plan.
Materials and Methods: A reference acrylic resin model with four Branemark fixtures was made according to All-On-4 treatment plan. Multiunit abutments were screwed into the fixtures and two special trays were made for direct and indirect impression techniques. Ten direct and ten indirect impression techniques with respective impression transfers were made. Impressions were poured with stone and the positional accuracy of the abutment analogues in each dimension of x, y, and z axes and also angular displacement (Δθ) were evaluated using a Coordinate Measuring Machine (CMM). Data were analyzed using T- test.
Results: The results showed that direct impression technique was significantly more accurate than indirect technique (P<0.001).
Conclusion: The results showed that the accuracy of direct impression technique was significantly more than that of indirect technique in Δθ and Δr coordinate and also Δx, Δy, Δz.
Eshagh Ali Saberi, Fereydoon Sargolzaei Aval , Arab Mohammad Reza Mohammad Reza , Seddighe Ebrahimipour ,
Volume 26, Issue 3 (8-2013)
Abstract
Background and Aims: The purpose of this study was to evaluate the tissue responses to octacalcium phosphate (OCP) and calcium hydroxide (CH) used as direct pulp capping (DPC) materials in cat teeth.
Materials and Methods: 72 premolar teeth of 9 cats were selected and divided into 3 groups (Two experimental and one control group). After the cats had been anesthetized, the pulp were exposed and capped directly with OCP, CH or no capping material as control group. The cavities of all three groups were filled with Glass ionomer cement (GI). Histological evaluations were performed at two, four and eight weeks after pulp capping. After tissue preparation procedures, paraffin blocks were prepared. After preparation and staining of the sections, the relevant variables were measured by optical microscope. The results were analyzed using Mann-Whitney U and Chi-square tests ( α =0.05).
Results: Two weeks after pulp capping, all specimens in three groups showed mild to sever inflammation. The formation of hard tissue (dentinal bridge) at in the exposed areas of the experimental groups was more noticeable for calcium hydroxide than that of octacalcium phosphate group. These differences were statistically significant (P<0.001). At four weeks, hard tissues were observed in both groups which were more evident for the CH group and there were statistically significant difference between two experimental groups (p<0.003). At eight weeks, continuous hard tissues were observed in both groups and there were no statistically significant difference between them (P>0.05), but hard tissues continuity were better for in the OCP than that of the CH.
Conclusion: It seems that the formation of hard tissue in CH because of its porosities had a worse percentage in sealing of the pulp than the OCP .
Mohammad Ebrahimi Saravi, Yushiaho Refoa, Yunes Nazari Dashlibrun, Reza Sharifi,
Volume 26, Issue 4 (1-2014)
Abstract
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.
Dastnaei Peimaneh Hosseini , Dastgurdi Maziar Ebrahimi ,
Volume 27, Issue 4 (1-2015)
Abstract
Background and Aims: In case of nonsurgical endodontic re-treatment or replacing a restoration, one of the best methods for removing post from the canal is using an ultrasonic vibration. The aim of this study was to evaluate the effect of ultrasonic vibration time on the retention of post luted with zinc phosphate or glass ionmer cements.
Materials and Methods: 96 sound extracted lower premolars were selected. The coronal section of specimen was removed and the roots were endodontically treated. A 9-mm post space was prepared in each specimens and a stainless steel Parapost XP was cemented into the post space. Half of the specimens were cemented with the Zinc phosphate cement and the other by g lass ionomer cement. After 7 days of storage, both groups were equally divided into 4 subgroups of 12 teeth. Control group did not receive any treatment. The other subgroups subjected to ultrasonic vibration for 4, 8 or 12 minutes. The retention of all specimens was evaluated and data were analyzed using ANOVA and Tukey tests.
Results: In control (no ultrasonic) group and 4 minute ultrasonic group, the retention of posts luted with Zinc phosphate cement were not significantly differen t from those luted with g lass ionomer cement. (P=0.372). On the other hand , applying of ultrasonic vibration for 8 and 12 minutes in zinc phosphate and 12 minutes in g lass ionomer caused a significant reduction in the retention of posts (P=0.01).
Conclusion: Although, the initial retention of two cements was not different, the ultrasonic vibration had more catastrophic effect on zinc phosphate in comparison to glass ionomer.
Ali Eskandarizadeh, Shahram Farzin Ebrahimi, Niloofar Shadman, Saeed Rahmani,
Volume 29, Issue 1 (7-2016)
Abstract
Background and Aims: Slow polymerization rate in early stage of light curing process leads to higher monomers movement and entering in polymer network that cause higher mechanical properties.The aim of this study was to evaluate the effect of light activation methodes (immediate, 5 and 10 minutes delay) on the push-out bond strength of cemented fiber posts in different regions of root canal with two types of resin cements.
Materials and Methods: In sixty extracted human single canal, the teeth were decoronated from cement enamel junction and after root canal therapy, FRC postec plus were cemented with two resin cements, Duolink and Variolink 2, in three curing methods; immediate, 5 and 10 minutes of delay. After storing in a dark place for 24 hours, they were cut into three sections: coronal, middle and apical. The push-out bond strength test was performed using a universal testing machine. The failure modes were observed using a stereomicroscope. Data were analyzed using ANOVA and Tukey post hoc test (P<0.05).
Results: In Duolink, immediate light curing had significantly higher bond strength than that of two delayed methods (P>0.05). In immediate light curing method, regardless of root region, Duolink had higher push-out bond strength than that of Variolink 2 (P=0.02). In all subgroups, there were reductions in the bond strengths from coronal to apical. Mixed failure at the cement-fiber post interface was predominent in all groups.
Conclusion: 5 and 10 minutes delay caused reduction in the push-out bond strength for Variolink 2 but did not have significant effect for Duolink resin cement.
Mohammad Javad Etesami, Seyyed Lotfollah Derakhshan, Kiomars Nazari Moghadam, Mohammad Ebrahimi Saravi,
Volume 29, Issue 1 (7-2016)
Abstract
Background and Aims: Cleaning and shaping is one of the most important stages in endodontic treatment. Single-file systems save time and reduce the risk of transmission of pathogens. This in vitro study was aimed to compare the rate of canal transportation after the preparation of the stimulated resin root canal with two single-file systems, namely Waveone and Reciproc.
Materials and Methods: Thirty stimulated resin root canal blocks with size 8/0. 02 K file were randomly divided into two study groups. The preparation in Group A and Group B was performed using Reciproc and Waveone files, respectively. Pre and post- preparation photographs were taken and the images were superimposed to evaluate the inner and outer wall’s curvature tendency at three points (apical, middle and coronal) using AutoCad pragram. Data were analyzed using T-test.
Results: Based on the results, the degree of transportation in the inner and outer walls of the canal was less at the level of 3 millimeters (P<0.001) and there was no significant difference between the two groups regarding the deviation at the levels of 1 and 5 millimeters (P>0.05).
Conclusion: Waveone showed better performance in the middle third of canal and this system maybe recommended.
Arash Zar Bakhsh, Ezzatollah Jalalian, Nilufar Rahimi, Shahrzad Sadr Haghighi,
Volume 29, Issue 1 (7-2016)
Abstract
Background and Aims: The zirconia coated FRC posts (Ice light) is the next generation of aesthetic posts , ice light features 70% fill of zirconia enriched, parallel glass fiber for exceptional strength. Its flexibility is close to dentine so stress is distributed. The aim of this study was to evaluate the effect of post type (FRC post and the zirconia coated FRC post) on the retention to the root canal wall.
Materials and Methods: 20 extracted human premolar teeth with 14 mm length were selected. After post space preparation, the teeth were randomly divided into two groups: Group1: the zirconia coated FRC post (Danville, USA) Group2: FRC post (RTD DT light post, France). All posts were cemented with a dual-cure resin cement (Panavia, Kuraray, Japan). All specimens were mount in acrylic cylinders, and the push-out test was done using a universal testing machine (Instron 5500 R, USA) at 1 mm/min speed. Data were analyzed using T-test.
Results: The retentive strengths were in coronal (75.27+14.81 MPa), in middle (64.38+15.29 MPa) and in apical (51.46+13.29 MPa) for the zirconia coated FRC post, and also were in Coronal (59.16+1.91 MPa), in middle (66.83+12.32 MPa) and in apical (67.88+17.47 MPa) for the FRC post. There was no significant difference in mean retentive strength between two groups in each region (P=0.07).
Conclusion: The FRC post and zirconia coated FRC post had similar retention to the root canal walls.
Ali Eskandarizadeh, Shahram Farzin Ebrahimi, Niloofar Shadman, Saeed Rahmani,
Volume 30, Issue 2 (8-2017)
Abstract
Background and Aims: Delay in light irradiance can improve the polymeric structure and mechanical properties of resin cement and uniform stress distribution. The aim of this study was to evaluate the effect of light activation modes (immediate, 5 and 10-minute delay) on the push-out bond strength of cemented fiber posts with two types of resin cements in different of root canal regions.
Materials and Methods: In sixty extractedsingle canal and endodontic therapied roots, FRC Postec Plus were cemented with two resin cements, Nexus3 and Panavia F2.0, in three curing methods, immediate, 5, and 10 minute delay. After 24 hours storing in a dark place, they were cut into three sections: coronal, middle and apical. The push-out bond strength test was performed using the universal testing machine. Failure modes were evaluated using stereomicroscope. Data were analyzed by ANOVA and Tukey post hoc test with P<0.05 as the level of significance.
Results: In Nexus3, the immediate light curing had significantly higher bond strength (11.18±4.32) than delay methods (P=0.001). In Panavia F2.0, the 5-minute delay had significantly the highest bond strength (13.34±4.62) (P<0.05). There was no correlation between the different light curing methods and root canal regions. In Nexus3, the coronal region had higher bond strength (11.83±3.7) than that of middle (9.12±3.1) (P=0.015), and middle than of apical (5.65±2.77) (P=0.00), and coronal than that of apical (P=0.002). In Panavia F2.0, there were not significant differences among regions (P>0.05).
Conclusion: Delay in light curing of dual-cure resin cement's had different effects on the push-out bond strength.
Abbas Rahimi Foroushani, Nooshin Akbari Sharak, Mohamad Javad Kharazi Fard,
Volume 30, Issue 2 (8-2017)
Abstract
Background and Aims: In recent years, dental implants have received special attention in dentistry. Due to the remarkable success of predictable dental implants, there is growing interests in the scientific community from descriptions of implant success toward identify factors associated with implant failure. The purpose of this study was to identify the risk factors associated with implant failure in an objective and statistically valid manner.
Materials and Methods: To address the research purposes, we used a cohort study in which a total of 2368 implants were placed on 1011 patient in the Clinic of Tehran University of Medical Sciences. The predictor variables included demographic variables, the health status and variables are related to implants. The outcome variable of interest was implant failure. The overall implant survival was estimated using the Kaplan-Meier analysis. First, risk factors were identified using Chi-square test and Fisher's exact test and then the Cox proportional hazard regression models were used for more analysis.
Results: The overall 39 month implant survival using the Kaplan-Meier function was 0.99±0.002. The implant location (jaws) (P=0.049) and type of teeth (P=0.011) were found to have significant relation with failure times in Cox proportional hazard model.
Conclusion: According to result of this study, both implant location and type of teeth had effection the failure times so that, the survival in mandible was higher than maxilla. The failure rate was higher in anterior teeth than that of others (molar, premolar, canine and primary).
Pooya Jannati, Mohammad Ebrahimi Saravi, Tahmineh Bamdadian, Farhad Sobouti, Sahar Cheperli, Jamshid Yazdani Charati, Nasrin Khaki, Sahba Amini, Abbas Mesgarani,
Volume 32, Issue 4 (1-2020)
Abstract
Background and Aims: One of the most important challenges for dentists is providing a crown with appropriate marginal fit and gap. The 135-degree tooth preparation found to have some advantages such as technical ease and appropriate finish line record. Despite the advantages of 135-degree tooth preparation, scant research has been done in this area. Therefore, the aim of this study was to compare 135-degree and deep chamfer tooth preparation on the marginal fit and marginal gap of posterior metal-ceramic crowns.
Materials and Methods: Deep chamfer and 135-degree tooth preparation were performed on the two first mandibular molars with healthy coronal tissue and similar size. Impression was taken from each tooth and 30 crowns were made on each die. The sample plastered with fit checkers were pressed under the force of 40 N for 3 min in a universal testing machine. They were measured and recorded under a loop with 40x power in three points on each aspect. Data were analyzed by Wilcoxon and Kolmogorov-Smirnov tests using SPSS version 24.
Results: The mean marginal fit values in deep chamfer and 135-degree were 48.5417µm and 55.3333 µm, respectively with no statistically significant difference (P>0.05). While the mean marginal gap in deep chamfer (2.4833 µm) was significantly higher (P<0.05) than 135-degree (1.0083).
Conclusion: It can be concluded that the marginal gap by 135-degree’s tooth preparation was lower than that of deep chamfer in metal-ceramic crowns. However, no significant difference in the marginal fit between the deep chamfer and 135-degree tooth preparation was found.
Roshanak I Montazeri Hedesh, Ghazaleh Baniebrahimi, Roza Haghgoo, Kosar Alinejad,
Volume 34, Issue 0 (5-2021)
Abstract
Background and Aims: Promoting children's oral health is the basis for increasing the level of community health and the goal of pediatric dentistry. By recognizing all the factors affecting the health and formation of the child's health habits, a fundamental step can be taken to promote oral health. The aim of this study was to evaluate the effect of parenting styles and demographic characteristic on OHI-S (Simplified Oral Health Index) in 2018.
Materials and Methods: In this cross-sectional study, 244 children aged 6-12 years in Behbahan-Iran with their parents were studied. The demographic questionnaire (variables such as parents 'age, economic status, gender, occupation and parents' education were recorded) and Bumrind questionnaire were used. The oral health status of children was assessed to determine the simplified oral hygiene index. Then, the obtained data were analyzed using SPSS 25 software and regression and Pearson correlation test.
Results: The results showed that the children of parents who used the permissive method had higher score of simplified oral hygiene index (P<0.001) and simplified calculus index (P<0.001). However, in children of parents who used the authoritative parenting style, a decreased simplified oral hygiene index (P<0.001) and simplified debris Index (P<0.001) were observed. However, the method of authoritarian parenting style did not have a significant relationship with the simplified oral hygiene index (P=0.890), simplified calculus index (P=0.404), and simplified debris Index (P=0.721). |
Conclusion: Powerful authoritarin and authoritative parenting practices have a clear impact on the oral health status of children. Therefore, parenting paratices can be considered as one of the main factors affecting the oral health of children.
