Showing 30 results for Post
Y. Refoua , O. Mahdavi ,
Volume 13, Issue 1 (4-2000)
Abstract
: 32 patients were entered in randomized double blind clinical research. The patients were divided into two groups. Group A(18 patients) were given a single dose of 20 mg Piroxicam one hour pre-surgery. Group B(14 patients) were received 325 mg Acetaminophen every six hours immediately after surgery. The mouth opening was measured pre-surgical treatment. Pain relief was evaluated in both groups lsl and 8th hour after surgery. The mouth opening was measured lsl and 7,b day after surgery. The results showed that the analgesic effects of Piroxicam were higher than acetaminophen, however, the comparison of trismus means revealed no significant difference.
M. : Pak Nejad , Y. Soleimani-E-Shayesteh , Z. Mohammad Zadeh ,
Volume 13, Issue 3 (10-2000)
Abstract
Guided Tissue Regeneration (GTR) is the most recent and common method for regeneration of class II forcation molars. However, it requires membrane, which seems expensive for most of the patients. In order to overcome this problem, Coronally Position Flap (CPF) procedure may be applied which arresting the epithelial cell down growth, follow the same aim. This study is aimed to compare GTR technique utilizing bioresorable collagen membrane and CPF utilizing citric acid. Nine patients with grade II forcation defects were selected. Defects were bilateral that randomly assigned into two groups: GTR and CPF groups. Measurements recorded at baseline and after surgery (6 months). Paired-T test was performed on these data. The following results were obtained after 6 months: In both groups significant reduction in probing pocket depth were measured in GTR and CPF groups, 1.55 Ind 1.88 mm, respectively. Also, open vertical probing depth: 0.33, 1.11 mm. Reduction in forcation weight in both groups was 0.22 mm. Bone fill was observed in 0.33% and 51% of defects. No recession was observed in GTR group, in CPF was 0.11 mm. Loss of attached gingiva was 0.34 and 0.78 mm, respectively. No significant difference was found between clinical parameters except OHPD. Comparison of means at the day (0 and 180) in each group showed the success for regeneration of forca. Considering the results, it can be concluded that CPF may substitute for GTR technique.
Mh. Shahroodi , H Berenji ,
Volume 14, Issue 1 (7-2001)
Abstract
Many different methods are suggested to restore endodontically treated teeth. Prefabricated posts can not be indicated for all teeth and cast posts require extra time and cost. In addition, with the introduction of full ceramic restorations, achieving the ideal esthetic with metal post underneath them may be problematic or impossible because the darkness of the metallic posts may show through the highly translucent all ceramic restorations. In this article the review of litature and describiton of applied methods of different procedure in restoring the root canal therapied teeth and few techniques of non metallic posts fabrication such as fiber reinforced composite and zirconium oxide posts have been described.
E. Yasini , N Mohammadi ,
Volume 14, Issue 4 (1-2002)
Abstract
Posterior composite restorations, due to polymerization contraction, result in microleakage. Different methods have presented to reduce this phenomena. The aim of this study is to evaluate the effects of flowable and condensable composites to reduce microleakage. Seventy extracted human teeth were prepared with proximal class II cavities with gingival margin 1 mm below CEJ. The teeth randomly were divided into 7 groups. Groups I & II were restored with a dentin bonding (DB) agent plus a Prodigy condensable (Kerr Co.) composite, placing incremental or bulky, respectively.. In groups IK IV, V a dentin bonding agent was applied and then cavities were restored with Tetric flow composite resin as a base plus either a hybrid composite (Tetric ceram, Vivadent Co.) or a Prodigy condensable composite (Cond), placing bulky or incremental. Groups VI and VII were restored with a resin modified glass ionomer (GI) (Fuji II Lc Co.) as a base plus either Prodigy condensable or Tetric ceram. Restorations were polished, thermocycled, and immersed in 0.3% basic fushin. After that samples were sectioned and studied under a stereomicroscope to evaluate dye penetration. Results showed that all restorations showed some degree of microleakage and according to kruskall- wallis statistical analysis, there were not any significant differences between all groups (P-0.051). Then fore pair comparison, between groups. Mann-Whitney analysis was used and no statistical difference was observed. However. Gh DB- Tetric group showed the least microleakage and DB+ Cond (bulk) the most one. Due to lack of an" statistical difference among different materials methods, it is concluded that no method or restorative material have been able to eliminate microleakage in margins completely yet, and using a flowable composite resin, in place of resin modified glass ionomer or using a condensable composite, instead of conventional In brid composites, do not have any effect
M. Ghavamnasiri , Saa. Hosseini , H. Farzaneh ,
Volume 16, Issue 1 (4-2003)
Abstract
Statement Problem: A few studies have been conducted about bioglass posts.
Aim: The aim of this study was to compare bioglass posts with prefabricated metallic posts in clinical performance of extensive composite restorations for anterior endodontically treated teeth.
Materials and Methods: Sixty endodontocally maxillary anterior teeth, with horizontally or vertically destruction, were selected. Teeth were divided into two groups based on the kind of post: Metallic prefabricated parapost and bioglass post. Each group was divided into three subgroups based on anterior bite: normal, deep bite and edge to edge. Gutta-percha was removed from 2/3 of canal length for parapost and 1/3 for bioglass post. After etching with phosphoric-acid (37%) and applying dentine bonding syntac, Duo cement was used for the adhesion of bioglass post and a self cured composite (Degufil) for parapost. Restoration was done with a hybrid composite (Heliomolar). Follow up studies, radio-graphically and clinically, were done every three months for a 1.5-year period. Exact Fisher and Pearson tests were used for data analysis.
Results: Apical lesion was not observed in any of the radiographs. Post seal was increased by resin cement and dentin bonding agent. Post type did not significantly affect on the clinical success rate of the restorations. The retention of restoration, for both posts, was the same. Crown destruction had no significant effect on success rate. The type of anterior bite had a significant effect on success rate, as the total 6.6% failure rate was related to the patients with anterior deep bite.
Conclusion: It is suggested to use metallic paraposts and bioglass posts, in extensive composite restorations for patients with deep-bite, more conservatively.
T. Hoseinzadeh-Nik , A. Malakooti,
Volume 17, Issue 4 (1-2005)
Abstract
Statement of Problem: Craniocervical Posture is a factor in the development and function of Craniofacial Structure. Previous studies of different samples have demonstrated associations between craniocervical posture and craniofacial morphology.
Purpose: This study aimed lo examine whether any significant association is evident or not between craniocervical posture and the occurrence of Class il & Class III skeletal malocclusions.
Materials and Methods: A sample of 76 subjects with Class II & Class III skeletal malocclusion aged 9-i 1 and>18 years were selected. None of them had received orthodontic treatment. Lateral cephalometric radiographs were taken in natural head position (NHP), and craniocervical and craniohorizental angels were traced and determined for analysis of craniocervical posture.
Results: According to the craniocervical posture, most class II skeletal patients have flexed heads and class MI skeletal patients have extended heads, as a result malocclusion in these patients seems to become more severe.With increase in age. class II skeletal patients have more flexed their heads and malocclusion become more severe, while with increase in age in class ill skeletal patients, their heads become extended and once again malocclusion thought lo be more severe. In class II skeletal patients, craniocervical posture has a significant correlation with the vertical growth pattern, but shows little correlation with the horizontal growth pattern. In class 111 skeletal patients, craniocervical posture shows no correlation to any of the vertical & horizontal growth patterns, of course the mean of vertical angles is less in these patients and probably in order to make these relation significant in Class III skeletal patients there is need for more samples, in class II & class III skeletal patients, the amount of Na.prep-point A and pog-Na.prep with craniocervical posture shows a significant correlation.
Conclusion: Consideration of craniocervical posture (in addition to cephalometric angles) lead to making better treatment planning.
M. Ghavam , H. Kermanshah , M. Ataei , N. Shadman ,
Volume 20, Issue 1 (5-2007)
Abstract
Background and Aim: Insufficient polymerization of resin cements is of considerable clinical importance, because of mechanical deficiencies and biological side effects of uncured resin. Dual cure resin cements are getting popular in luting tooth colored posts and although their curing is claimed to proceed chemically, polymerization efficiency in deep areas of canal is uncertain. The aim of this study was to evaluate degree of polymerization of dual-cure resin cements used for luting translucent and opaque fiber posts in different distances from the light tip.
Materials and Methods: In this experimental in vitro study, degree of conversion of two dual cured resin cements, Rely X ARC (3M, ESPE) and Nexus 2 (Kerr, USA) were measured when used with DT-Light and DT-White posts (RTD, France). The light curing unit used was Optilux 501, with output of 650-700 mw/cm2 with emitting time of 60 seconds. Degree of conversion was measured in three different depths (4, 6, 8 mm) by FTIR. The data were analyzed using ANOVA and Post hoc tests. P<0.05 was considered as the level of significance.
Results: DC% of Rely X with either of the posts was not significantly different in the studied depths (P>0.05). Nexus used with DT-Light had lower DC% in 8 mm depth (P<0.05). Nexus used with DT-White showed lower DC% in 8 mm depth compared to 4 mm depth. The control groups of both cements showed significant increased DC% in 4 mm depth compared to 6 and 8 mm depths (P<0.05). DT-White caused decreased DC% in both cements in 4 mm. DT-Light caused increased DC% of Rely X in 6 mm depth compared to DT-White and control. DT-Light increased DC% of Nexus in 6 and 8 mm depths, compared to DT-White and control groups.
Conclusion: Based on the results of this study, application of translucent fiber posts has a significant effect on degree of polymerization in dual-cure resin cements, compared to opaque types. Their better light transmission to deep areas due to the effect of optical fibers, can lead to better results.
H. Kermanshah , Sh. Farzin Ebrahimi,
Volume 20, Issue 2 (5-2007)
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.
E. Aminsalehi , S. Emami Ardestani ,
Volume 20, Issue 4 (1-2008)
Abstract
Background and Aim: The use of fiber reinforced posts in endodontically treated teeth has become increasingly common. But their retention in root canals must be considered seriously. The aim of this study was to evaluate the effect of light-cure and dual-cure bondings on regional bond strength of a fiber composite post.
Materials and Methods: In this experimental in vitro study, 20 endodontically treated teeth were randomly divided into two groups. In the first group, a dual-cure bonding (Scotchbond Multi-Purpose Plus, 3M ESPE/USA) [SBMP] was used and in the other group, a light-cure bonding (Single Bond, 3M ESPE/USA) [SB] was applied according to the manufacturer's instructions. A dual-cure resin cement (Rely X ARC, 3M ESPE/USA) was used to cement the post (Glassix, Harald Nordin SA,Switzerland). Coronal 8mm of cemented posts were sectioned in equal thirds using a 0.1mm diamond disc. Each slice was polished by a soft and wet abrasive paper in order to get a 2mm thickness. Loading was performed by a testing machine (Zwick/Germany) at a speed of 1mm/min until the post was dislodged. Data were analyzed using one-sample Kolmogorov-Smirnov, T and ANOVA tests with P<0.05 as the level of significance.
Results: There was a significant difference between the two adhesive systems in the middle third of the canal block with higher bond strength in SBMP group (p=0.02). In SB group the bond strength of the cervical region was higher than the middle and apical thirds (p<0.05). In SBMP group, there was no statistically difference between bond strength of the three regions (p=0.117).
Conclusion: Based on the results of this study, dual-cure bonding could be recommended for composite post cementation into root canals, because its bond strength was more uniform in different regions of root and greater in the middle and third regions.
F. Shirani, Mr. Malekipoor, P. Mirzakoochaki, M. Eravani,
Volume 21, Issue 2 (11-2008)
Abstract
Background and Aim: Microleakage has been always a major concern in restorative dentistry. The curing contraction of composites still presents a problem with controlling microleakage and postoperative sensitivity. The aim of this study was to investigate the effect of flowable and dual-cure resin composite liners on gingival microleakage of packable resin composite restorations.
Materials and Methods: Sixty Class II cavities with cervical margins 1 mm below the CEJ were prepared in 30 extracted human molars. The teeth were randomly divided into five groups of 12 each. In control group, each tooth was restored incrementally with Tetric Ceram composite without applying any liner. In the second and forth groups, flowable materials- Tetric Flow and dual-cure composite resin cement Relay X ARC were placed respectively as a 1-mm thick gingival increment and cured before the resin composite restoration, whereas, in the third and fifth groups liners were cured with the first increment of packable composite.The restored teeth were stored for one week in distilled water at 370C, and thermocycled between 50C and 550C, sealed with nail varnish except the tooth - composite interface in cervical restoration margins and immersed in 2% basic fuchsin for 24 hours. Dye penetration was evaluated using a stereomicroscope with 28x magnification. The data were analyzed by Kruskal-Wallis and Mann-Whitney U-tests with p<0.05 as the level of significance.
Results: The results of this study indicated that there were significant statistical differences between control - cured flowable liner, control-flowable liner without separately curing, control-cured dual cure composite resin cement groups.However there were no significant differences between dual-cure composite resin cement without separately curing-control,cured flowable liner-cured dual cure composite resin cement, flowable liner without separately curing-dual cure composite resin cement without separately curing groups.
Conclusion: The results of this study indicated that none of techniques could thoroughly eliminate microleakage in gingival floor, however the effect of flowable or a dual-cure liner on reducing the gingival microleakage was found to be statistically significant in tested restorative material.
M. Mirzaei, E. Yassini, M. Ghavam, A. Pahlavan, M. Hasani Tabatabaie, S. Arami, H. Kermanshah, B. Esmaieli,
Volume 21, Issue 2 (11-2008)
Abstract
Background and Aim: Various studies have shown that reliable bond at the root - post - core interfaces are critical for the clinical success of post - retained restorations. Severe stress concentration at post - cement interface increases post debonding from the root. To form a bonded unit that reduces the risk of fracture, it is important to optimize the adhesion. Therefore, some post surface treatments have been proposed. The purpose of this study was to investigate the influence of various surface treatments of tooth - colored posts on the bonding of resin cement.
Materials and Methods: In this interventional study, 144 tooth colored posts were used in 18 groups (8 samples in each group). The posts included quartz fiber (Matchpost), glass fiber (Glassix), and zirconia ceramic (Cosmopost) and the resin cement was Panavia F 2.0. The posts received the following surface treatments: 1- No surface treatment (control group), 2- Etching with HF and silane, 3- Sandblasting with Cojet sand, 4- Sandblasting with Cojet sand and application of silane, 5- Sandblasting with alumina particles, 6- Sandblasting with alumina particles and application of silane. Then, posts were cemented into acrylic molds with Panavia F 2.0 resin cement. The specimens were placed in water for 2 days and debonded in pull - out test. Statistical analysis was performed using ANOVA followed by Tamhane and Tukey HSD. Failure modes were observed under a stereomicroscope (10 ). P<0.05 was considered as the significant level.
Results: Surface treatments (sandblasting with Cojet and alumina particles ,with or without silane) resulted in improved bond strength of resin cement to glass fiber post (Glassix) and zirconia ceramic (Cosmopost) [p<0/05], but not to the quartz fiber post (Matchpost). In general, higher bond strengths resulted in a to higher percentage of cohesive failures within the cement.
Conclusion: Based on the results of this study, sandblasting with cojet and alumina particles increases bond strength of resin cement to glass fiber post (Glassix) and zirconia ceramic (Cosmopost).Generally, the bond strength of resin cement to the posts is affected by the post's composition and surface treatment.
M. Atai, M. Ghavam, E. Yasini, M. Mirzaei, A. Pahlavan, M. Hasani Tabatabaie, S. Arami, H. Kermanshah, S. Kameli,
Volume 21, Issue 2 (11-2008)
Abstract
Background and Aim: Nonmetallic tooth- colored posts adhere to canal walls by dentin bonding agents and resin cements. Better retention and proper distribution of stress result from enough and proper bonding. The purpose of this study was to evaluate bond strength of D.T. Light - post with two different resin cements (self-cure & dual-cure) and to investigate the effect of irrigating solutions applied in root canal on bond strength of the resin cements and D.T.Light- post to root canal wall.
Materials and Methods: In this experimental study 40 single root teeth (maxillary canine & central) were selected and stored in 0.1% thymol solution for one week and transferred to distilled water. The teeth were decoronated 2mm above CEJ. The canal space was mechanically enlarged using k-files (up to # 70). The teeth were randomly divided into two groups. The first group was irrigated with 2.6% NaOCl, and the second was irrigated with normal saline. After drying, the teeth were filled with gutta percha cones using lateral condensing method. After two weeks the post space was prepared and D.T.Light- post was inserted in each subgroup using self or dual-cure cements according to manufacturer's instructions. After thermocycling, the apical part was cut 1cm below CEJ. The remained length was divided into 9 equal sequential sections. Each section was submitted to shear push-out test in universal testing machine. Statistical analysis of the bond strength data was performed using ANOVA and post hoc tests with p<0.05 as the level of significance. All failed specimens were examined under stereomicroscope. Degrees of conversion of the cements were determined by FTIR.
Results: Significant difference in bond strength values were found among sites (P=0.001) and cements (P=0.03). With increasing in depth, bond strength decreased. The mean bond strength value in dual-cure resin cement was higher than self-cure cement. The irrigating solutions caused no significant difference in bond strength (P=0.46). DC% had significant difference in various depths.
Conclusion: According to the results of this investigation, bond strength of dual-cure cement is higher than self-cure one in D.T Light- post because of post's translucency. 2.6% sodium hypochlorite does not affect the bond strength.
Sh. Nasermostofi, A. Raghanians, S. Banava, E. Jalalian, A. Abdollah,
Volume 22, Issue 1 (8-2009)
Abstract
Background and Aim: A key factor in restoring the endodontically treated teeth is ferrule preparation. When the ferrule is absent, occlusal loads may cause the post or root to fracture. The purpose of this in vitro study was to evaluate the effect of ferrule preparation on fatigue resistance of teeth restored with quartz-fiber posts.
Materials and Methods: Twenty single-rooted lower premolars having similar dimentions were randomly devided into two groups of 10. In control group the teeth were prepared with 3-mm of remaining coronal tooth structure and in test group teeth were prepared with 1-mm of remaining coronal tooth structure. The teeth were endodontically treated. 9-mm long Post holes were prepared, and D.T. light quartz-fiber(RTD,France) posts were cemented with Panavia F2(Kuraray,Japan).Then the core build up was done with Bisco core build up composite(Bisco,USA) and full metal crowns were cemented with Zinc phosphate(Harvard cement, Germany). All specimens were mounted in acrylic resin blocks and intermittently loaded (180 N) at an angulation of 45- degree to the long axis of the teeth at a frequency of 4 loads per second, until failure occurred.
Results: There was significant difference between the loads cycles of two groups studied. (p<0.0001).
Conclusion: The results of this study showed that an increased amount of coronal dentin significantly increases the fracture resistance of teeth restored with quartz-fiber posts.
S. Nokar, H. Dorriz, H. Hajimiragha, N. Shamashyan ,
Volume 22, Issue 1 (8-2009)
Abstract
Background and Aim: Debonding is the most common failure type of fiber posts. This in vitro study aimed to evaluate the bond strength of 3 different fiber posts cemented with a resin luting agent in three regions of prepared post spaces after being subjected to termocycling.
Materials and Methods Thirty six mandibular first premolars were sectioned at the cemento-enamel junction and were treated endodontically. After one week the post spaces were prepared and roots were divided into 3 groups of 12 specimens according to the post types (D.T.Composipost, D.T.White, D.T.Light). Sealbond Cement Dual II was used in all groups. One day after cementation, specimens were subjected to 3500 thermal cycles (5oC/55oC). Each root was then embedded in acrylic resin and sectioned perpendicular to long axis. Three 1-mm tick segments from apical, middle and cervical thirds were prepared. Push out test was performed. Data were analyzed with 2-way ANOVA (P<0.05). All root segments and dislodged posts were observed with stereomicroscope to figure out their failure modes.
Results: The post type had no significant effect on bond strength (p=0.08). However bond strength at the coronl segment was higher than the other segments (p=0.005). Mixed mode was the mostly occurred failure mode with D.T.Composipost and D.T.Light but with D.T.White, the mostly occurred failure mode was adhesive between the post and cement.
Conclusion: Different fiber posts have relatively similar bond strength to root dentin, bond strength at the coronl segment was higher than the other segments.
M. Saatchi, F. Mosavat, F Razmara, B. Soleymani,
Volume 22, Issue 4 (1-2010)
Abstract
Background and Aims: Despite the significant improvement in dentistry, pain after endodontic therapy is still of concern for patients. Non-steroidal anti-inflammatory drugs are the most commonly prescribed oral analgesics used for dental pain relief after root canal treatment. The purpose of this study was to compare the effectiveness of Ibuprofen versus slow-released Diclofenac Sodium in controlling pain following root canal treatment.
Materials and Methods: In this randomized clinical trial, mandibular molars with irreversible pulpitis in 90 patients were selected. The patients were divided into three groups (Ibuprofen, slow-released Diclofenac Sodium and placebo). After examination patients filled in the consent form. Then they received one of the mentioned drugs. After inferior alveolar nerve block, access cavity was prepared and the root canals were prepared using passive step back method. The canals were dried and temporary filling material was placed. Then the pain evaluation form (visual analog scale) was explained and delivered to the patients. Data were analyzed using Repeated Measurement ANOVA, Kruskal-wallis and Man-Whitney U tests.
Results: The mean pain intensity in slow-released Diclofenac Sodium group was 0.87 0.95, 1.17 1.10 for Ibuprofen group, and 2.14 1.70 for placebo group. The differences between groups were statistically significant (P<0.001). The effect of Ibuprofen in controlling post endodontic pain in the first 2 hours was more than slow-released Diclofenac Sodium (P=0.01), but in 10, 18, and 36 hours after treatment, slow-released Diclofenac Sodium was more effective than Ibuprofen (P<0.001).
Conclusion: Premedication with single dose of slow-released Diclofenac Sodium can control post endodontic pain for a longer period of time compared with Ibuprofen.
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S. Yaghobee , V. Esmaeili ,
Volume 23, Issue 2 (10-2010)
Abstract
Background and Aims: Musculoskeletal disorders in dentists due to abnormal postures may result in economic and health problems. To prevent these problems, the working posture of dental students should be assessed and corrected in dental procedures. This study determine these problems and the effect of training courses on them by Rapid Entire Body Assessment method (REBA).
Materials and Methods: The posture of 69 students were assessed by REBA before and after of the “Ergonomic principles in dentistry” course. The subjects which were used in the training course were based on the previous studies on this issue. The REBA scores were assessed by SPSS software using Paired T-test.
Results: The results showed that the students’ posture should be corrected. Postures of 94.2% of students were in moderate and high risk level which needed to be corrected. The worst working positions were during surgery, endodontic and pediatric dentistry procedures. Although the REBA scores before and after training course were statistically different (P<0.05), the training did not improve the posture of students remarkably.
Conclusion: The students’ working postures should be improved. One-day ergonomic principles course improved the working posture of students but it was not sufficient. More training and instructions are needed to have a good working position in dental procedures.
Mohamad Hosein Lotfi Kamrani, Mahdi Tabrizizadeh, Yosef Khlil Sefat, Vahid Yegane,
Volume 24, Issue 4 (1-2012)
Abstract
Background and Aims: The seal provided by a root canal filling may be compromised by post space preparation. The aim of this study was to compare coronal microleakage around cast posts and prefabricated pins.
Materials and Methods: Thirty-eight extracted single-rooted, maxillary human teeth were prepared with step back method and filled with gutta-percha and sealer. After removing 8 mm of coronal gutta-percha with peeso-reamer drills #2 in twenty canals, the teeth were divided into three groups: cast post & core, prefabricated pin, and gutta-percha (without any post or pin). After thermocycling, the samples were immersed in India ink for seven days. Finally, the specimens were cleared and the coronal microleakage of dye was then measured by the stereomicroscope. The data were analyzed by One-way ANOVA and Tukey HSD tests.
Results: According to the results, the mean dye penetration in cast posts, pins, and group without post or pin was 3.3 (0.39), 5.2 (0.47), and 7.2 (0.15) mm, respectively. There was no statistically significant difference between the groups (P>0.05).
Conclusion: Considering the importance of adequate filling of crown for prevention of microleakage, the method for coronal filling must be selected with caution. According to the results of this study, no significant difference between microleakage of cast posts and prefabricated pins was observed.
Zafar Mahdavi Ezadi, Ezatolah Jalalian, Mohamad Hasan Salari, Shima Azimzad, Tahmine Safaie, Mahdi Shirazi, Behzad Salari,
Volume 26, Issue 4 (1-2014)
Abstract
Background and Aims : According to the common application of non-metal prefabricated posts in dentistry and lack of enough information about the stress distribution in the root canal walls by these posts, this study was performed to compare the effect of two simple taper and double taper posts on the stress distribution on root canal walls by photo elastic method .
Materials and Methods: The design of this study was experimental in photoelastic system. The posts, used in this investigation, were double taper and simple taper fiber posts with 0.9 mm diameter and 20 mm length and epoxy resin. First two photo elastic models with tooth dimensions were fabricated and the posts were placed inside the model. Then the core of the each post was fabricated on the model. Each models were loaded in polariscope and the formed fringe order colored ring were photographed.
Results: In 100 N, 90 degree angle loading in cervical and apical fringe order showed 2.50 and 1.39 in simple taper posts and 1.39 and 2.35 in double taper post. In 150 N, 30 degree angle loading in cervical and apical fringe order showed 4 and 2.65 in simple taper posts, and 4 and 2.5 in double taper post.
Conclusion: In the vertical and oblique loads, double taper fiber post showed better stress distribution than that of simple tapered posts.
Ezatollah Jalalian, Mona Sadegh, Rana Mohamadi, Reihane Aghajani, Elnaz Shafiee,
Volume 27, Issue 1 (4-2014)
Abstract
Background and Aims : The root fracture resistance of endodontically treated teeth depends on the types of posts. The aim of this study was to compare the effect of two types of bonded non-metallic posts with different elasticity modulus on the fracture resistance of endodontically treated teeth under compressive loads.
Materials and Methods: In this in vitro experimental study, 20 fresh extracted mandibular premolars were selected and sectioned adjacent to the CEJ and then were endodontically treated. The specimens were randomly divided into two groups (n=10). After post space preparations, the fiber RTD Light posts (R.T.D, France) and zirconia coated fiber posts (ICE light, Danville) were cemented into the root canals. Composite resin (Lumiglass R.T.D, France) cores were built up. Aluminium foil was used to mimic the PDL, and the specimens were embedded in acrylic resin and tested in a Universal Testing Machine. A compressive load was applied at a 90 degree angle until fracture at a crosshead speed of 1mm/min. Data were analyzed using one-way ANOVA and T test .
Results: The mean fracture resistance of R.T.D group was (1083.11 ± 156.74 (N)) and the mean of ICE light group was (865.18 ± 106.24 (N)). The highest mean fracture resistance was observed in RTD fiberglass and a statistically significant difference was observed between the two groups (P<0.001).
Conclusion: FRC posts with zirconia coating due to unfavorable fractures of the teeth should be used with caution, and thus, fiber posts are preferred.
Majid Akbari, Mohhamad Javad Moghaddas, Sara Majidinia,
Volume 27, Issue 2 (6-2014)
Abstract
Background and Aims: The aim of this study was to evaluate the fracture strength of restored teeth with three different types of E glass-fiber posts after thermo-mechanical loading.
Materials and Methods: Sixty extracted upper central incisor human teeth, with similar size, were selected and divided into three groups (n=20). Endodontic treatment was done in all groups and crowns were sectioned from 2 mm above CEJ. Then one type of posts in each group (Anthogyr, Svensk, Hetco) cemented using Panavia cement and the crowns were restored with a composite. The specimens in each group were thermocycled for 6000 cycles (5-55°C) and subjected to 1200000 cycles of mechanical loadiong in an artificial mouth machine. Then the fracture strength was measured and data were analyzed using ANOVA and T-student test (α=0.05).
Results: The mean fracture strengths in Hetco group before and after thermomechnical loading were 581.098 ± 192.742 N and 564.74±213.59 N, in Anthogyr group were 664.358 ± 135.878 N and 629.12±390.3 N and, in Svensk group were 780.258 ± 379.133 N and 779.84±282.59 N, respectively. There was no significant difference between groups and also there was no significant difference in each group before and after thermo-mechanical loading (P>0.05).
Conclusion: Restored teeth with Hetco fiber glass post were similar in terms of the fracture strength with that of two other posts after thermo-mechnical loading.
