Journal of Dental Medicine
Year:2008 | Volume:20 | Issue:4 (53)|Papers Count:10

Background and Aim: Sealing the root canal system is of great importance in endodontic treatment especially in infected teeth. Several materials have been introduced for this purpose. The aim of the present study was to evaluate the sealing ability of MTA as an orthograde root filling material and compare it with laterally condensed gutta-percha with sealer.Materials and Methods: Thirty-six extracted human maxillary central and canine teeth were used in this experimental study. After preparation and surface disinfection with 1% NaOCl solution, the crowns of the teeth were cut at cemento-enamel junction.Roots were randomly divided into four groups: two experimental groups of 15 roots each (gutta-percha with AH26 sealer and MTA) and two control groups of 3 roots each (positive and negative). After root canal preparation and filling, the sealing ability of each technique was assessed by immersion in 1% methylene blue dye for 72 hours. Then the teeth were cleared and the extent of dye penetration was measured with a stereomicroscope. Data were analyzed by T-test with P<0.05 as the level of significance.Results: The results showed that the mean microleakage was 1.1mm (SD=2.1) in the gutta percha group and 3.4mm (SD= 2.1) in the MTA group.This difference was statistically significant (P=0.013).Conclusion: Based on the results of this study, canal obturation with gutta-percha and AH26 sealer may provide a better apical seal compared with MTA. However, further studies on microbial leakage are needed for more precise evaluation of the sealing ability of MTA.

Background and Aim: Nowadays, esthetic dentistry has become an important part of modern dentistry.Bleaching is considered as a conservative, safe and effective way for treatment of discolored teeth. Although bleaching is commonly used on anterior teeth, the bleaching gel may come into contact with patient's former amalgam restorations and result in corrosive effects, dissolution of amalgam phases and increasing release of mercury. Mercury released from dental amalgam during mouthguard bleaching can be absorbed and increase the total mercury body burden. The aim of this study was to determine the amount of mercury released from Iranian and foreign brands of amalgams with spherical and admixed particles, polished and unpolished, after 16%carbamide peroxide gel application.Materials and Methods: This experimental in vitro study was performed on 256 Iranian and foreign amalgam samples with spherical and admixed particles. The provided samples were put in distilled water and classified according to the type of amalgam, shape of particles and quality of surface polishing. The test samples were placed in Nite White 16% carbamid peroxide gel and control samples were put in phosphate buffer (Ph=6.5) for 14 and 28 hours. The amount of released mercury was calculated using AVA-440 Mercury Analysis System (Thermo Jarrell Ash model SH/229) with cold-vapor atomic absorption. Data were analyzed using t-test, four way and three way ANOVA tests with P<0.05 as the level of significance.Results: 16% Nite White carbamide peroxide gel caused a significant increase in amount of mercury released from amalgams in all groups (P<0.05). Mercury release from Iranian amalgam was higher than that from the foreign brands (P<0.05). There was no significant difference in mercury released from spherical and admixed amalgams (P>0.05). The amount of mercury released from Iranian and foreign amalgams was time dependent (P<0.05). Furthermore, the amount of mercury released from unpolished amalgams was higher than polished ones (P<0.05).Conclusion: The present study indicated that exposure of amalgam to 16% Nite White carbamide peroxide gel causes a significant increase in mercury release from the amalgam which is significantly influenced by the brand, exposure time, and surface polishing.

Background and Aim: An important criterion for success assessment of implant-supported prostheses is marginal fit. Vertical and horizontal discrepancy can result in loosening of the prosthetic screw, crestal bone resorption, peri-implantitis and loss of osseointegration. Despite careful attention to waxing, investing, and casting, marginal discrepancies are inevitable. The aim of this study was to evaluate the marginal gap and overhang in three casting methods with two different alloys in ITI implants.Materials and Methods: In this experimental in vitro study 48 analog abutments were randomly divided into six groups as follows: 1) burn out cap + BegoStar, 2) impression cap + BegoStar, 3) conventional wax up + BegoStar, 4) burn out cap + Verabond2, 5) impression cap + Verabond2, 6) conventional wax up + Verabond2. Waxing was done in 0.7 mm thickness verified by a digital gauge and a putty index was made for all groups. Reamer was used for correction of the finish line after casting in all groups. Castings were seated on analog abutments and embedded in acrylic resin. Specimens were sectioned by isomet instrument and polished and cleaned by ultrasonic cleaner for 10 min. The marginal gap and overextended margins of castings were examined under a Scanning Electron Microscope (SEM) (X200). The mean gap and margin overextension were calculated for each group. Data were analyzed by multivariate analysis and Bonferroni post-hoc test with p<0.05 as the level of significance.Results: No significant difference in gap size was observed among the three casting methods with two alloys (P=0.056). The marginal gap was not different in the studied casting methods (P=0.092). Gold alloy crowns showed lower marginal gaps compared to base metal alloy crowns (P<0.001). No significant difference in overhang size was observed among casting methods with two alloys (P=0.093). Base metal alloy crowns showed less overhang compared to gold alloy crowns (P<0.001). There was a significant correlation between overhang and use of impression cap in base metal alloys (P<0.001).Conclusion: Based on the results of this study, vertical discrepancy of frameworks made with gold alloy were less than those made with base metal alloy. Base metal alloy demonstrated fewer overhangs. Conventional wax up or using burn out caps produced less horizontal discrepancy.

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.

Background and Aim: Chin cup is an orthopedic appliance for treating growing skeletally Cl III patients.The amount of chin forward movement in addition to morphologic changes in bony structure, determines the final profile of treated patients. The aim of this study was to evaluate the amount of morphologic changes of symphysis after chin cup therapy in skeletally Cl III patients.Materials and Methods: In this clinical trial, twenty eight cephalometries before and after chin cup therapy of 14 skeletally Cl III patients were analyzed. Landmarks introduced by Ricketts were determined to evaluate the symphysis and describe its relation to mandible. Also four additional measurements regarding the symphysis individually were evaluated and analyzed. Data were analyzed by paired t and pearson tests with P<0.05 as the level of significance.Results: The results showed that the height of symphysis increased after treatment (P=0.02), but its depth decreased (P=0.04). The sysmphysis turned down and back.Conclusion: These findings suggest that in Cl III malocclusions with a prognathic mandible, chin cup therapy creates changes in the horizontal dimension of symphysis morphology, which improves the Cl III profile. If the patient isn’t a vertical grower, vertical changes of symphysis would be desirable. In addition, changes in the vertical dimension of the mandible (body and ramus) could be observed as a backward and downward rotation.

Background and Aim: Osteoblasts and periodontal ligament cells play a major role in wound healing after root end resection. The interaction of osteoblasts with filling materials is critical in healing of surgical lesions.The aim of this study was to evaluate the morphology and adhesion of human osteoblasts (MG-63 cell line) in contact with IRM, gray MTA, white MTA and Portland cement (PC) as root end filling materials.Materials and Methods: In this in vitro study, human osteoblasts of osteosarcoma were provided from the cell bank of Iran Pasteur Institute, and cultured in RPMI 1640 medium. Test materials were mixed according to the manufacturer's instructions and placed in contact with osteoblast cells. After the first, third and seventh days discs of materials with grown cells were fixed and examined by scanning electron microscopy.Results: Results showed that after 7 days most of the osteoblasts were attached to the surface of both gray and white MTA and PC and appeared flat or round, however cells adjacent to IRM were round without any adhesion and spread.Conclusion: Based on the results of this study, human osteoblasts have a favorable response to gray and white MTA and Portland cement compared to IRM.

Background and Aim: Processing conditions affect sensitometric properties of X-ray films. In this study, we aimed to evaluate the sensitometric characteristics of Insight (IP), a new F-speed film, in fresh and used processing solutions in dental office condition and compare them with Ektaspeed Plus (EP).Materials and Methods: In this experimental in vitro study, an aluminium step wedge was used to construct characteristic curves for Insight and Ektaspeed Plus films (Kodak Eastman, Rochester, USA).All films were processed in Champion solution (X-ray Iran, Tehran, Iran) both manually and automatically in a period of six days. Unexposed films of both types were processed manually and automatically to determine base plus fog density. Speed and film contrast were measured according to ISO definition. Data were analyzed using one-way ANOVA and T tests with P<0.05 as the level of significance.Results: IP was 20 to 22% faster than EP and showed to be an F-speed film when processed in automatic condition and E-F film when processed manually. Also it was F-speed in fresh solution and E-speed in old solution. IP and EP contrasts were similar in automatic processing but EP contrast was higher when processed manually. Both EP and IP films had standard values of base plus fog (<0.35) and B+F densities were decreased in old solution.Conclusion: Based on the results of this study, InSight is a F-speed film with a speed of at least 20% greater than Ektaspeed. In addition, it reduces patient exposure with no damage to image quality.

Background and Aim: Proximal segment movements following different methods of ramus osteotomy is one of the undesired consequences of orthognathic surgery. Theoretically, it seems that intraoral verticosagittal ramus osteotomy can minimize the movement of proximal segment. In this study, changes in intergonial distance and ramus flaring angles were evaluated and compared in transverse plane after mandibular set back by two osteotomy techniques.Materials and Methods: In this randomized clinical trial 20 patients with mandibular prognathism without any asymmetry were selected and divided into two groups of 10 each. One group was treated by bilateral sagittal split ramus osteotomy and the other by intraoral verticosagittal ramus osteotomy technique.Intergonial width and inner ramal angle in transverse plane were measured on radiographs before and 1 and 12 weeks post surgery. Data were analyzed using covariance test with P<0.05 as the level of significance. Results: Changes of intergonial distance and interramal angle in each group were significant after 1 and 12 weeks after surgery. No statistically significant difference was observed between the two studied groups.Conclusion: According to the results of this study, there is no difference between bilateral sagittal split and intraoral verticosagittal ramus osteotomy techniques regarding mandibular width and ramus flaring changes.

Background and Aim: Improving esthetics is a major goal in periodontal treatments and especially reconstruction of dental papilla is of great importance. Different techniques have been developed, however the results are not completely predictable. The aim of the present study was to compare the possibility of papilla reconstruction using connective tissue graft with and without Emdogain.Materials and Methods: In this clinical trial, 40 classes II lost interdental papilla (Nordland- Tarnow classification) in 18 patients (4 male and 14 female) were studied. Samples were randomly devided into two groups. Case group was treated by connective tissue graft and emdogain (Straumann-USA) and controls were treated using connective tissue graft only. Periodontal parameters including papilla height (PH), periodontal pocket depth (PPD) and clinical attachment level (CAL) were measured before surgery, and 3 and 6 months after treatment. At the tenth days and 1 month after treatment only the papilla height was measured. Repeated measures analysis was used for data analysis with p<0.05 as the level of significance.Results: In the control group the mean papilla height changed from 3.38 ± 0.89 to 2.85 ± 0.93 on the 3rd month and 2.90 ± 0.95 on the 6th month. The mean PPD changed from 2.8 ± 0.68 to 2.55 ± 0.70 on the 3rd month and 3.06 ± 1.25 on the 6th month. The mean CAL changed from 3.88 ± 1.29 to 3.79 ± 1.25 on the 3rd month and 4.11 ± 1.44 on the 6th month. In test group the mean papilla height changed from 2.98 ± 0.91 to 2.45 ± 1.55 on the 3rd month and 2.55 ± 1.48 on the 6th month. The mean PPD changed from 2.75 ± 1.49 to 2.63 ± 1.38 on the 3rd month and 2.88 ± 1.39 on the 6th month. The mean CAL changed from 3.75 ± 1.24 to 4.01 ± 1.45 on the 3rd month and 4.28 ± 1.63 on the 6th month. These differences were not significant between the studied groups (P>0.05).Conclusion: Based on the results of this study, use of connective tissue with or without emdogain is not effective in interdental papilla reconstruction.

Background and Aim: The efficiency of disinfecting materials and procedures in removal of contamination from dental surfaces and equipments is essential. In authors' previous study, daily use of 2:100 dilution of 5% sodium hypochlorite in water and disposable covers were recommended since HBV contamination was found on semi-critical parts of the operative dentistry department. The aim of this study was to evaluate the HBV contamination following application of the recommended procedures.Materials and Methods: The study was conducted in two parts. In the first cross-sectional part, samples were collected from 17 sites of dental surfaces. In the second interventional part samples were collected from 10 sites of 9 dental and 3 sites of 2 light cure units, before and after disinfection with 5% sodium hypochlorite solution diluted to 2:100. Sterile cotton swabs moistened with sterile BSAS (Bovine Serum Albumin in Sodium Chloride) solution were used for sampling. Samples were tested by PCR technique in Pasteur Institute, Iran.Results: None of the samples collected in the first part of the study showed contamination. In the second part of the study, from 96 samples taken from various parts of dental and light cure units, before and after disinfection, there was only one HBV contaminated site before disinfection which showed no contamination after disinfection.Conclusion: Based on the results of this study, disinfecting procedure with 5% sodium hypochlorite solution diluted to 2:100 along with using disposable covers is effective in preventing HBV contamination.