JOURNAL OF RESEARCH IN DENTAL SCIENCES
Year:2016 | Volume:13 | Issue:3 (49)|Papers Count:9

Background & aim: One of the most important challenges in Endodontics is to achieve a successful anesthesia in mandibular molars with symptomatic irreversible pulpitis. The purpose of this study was to compare the anesthetic efficacy of buccal and/or lingual supplementary injections of Articaine in mandibular molars with symptomatic irreversible pulpitis Material & Methods: In this prospective, randomized, double blind, clinical trial study, one hundred sixty first and second molars with symptomatic irreversible pulpitis were selected based on included and excluded criteria. Initially all samples received IANB by using 2% lidocaine with 1: 100, 000 epinephrine. After 15 minutes the teeth were negatively responded to cold test received supplementary injections by using 4% Articaine with 1: 100, 000 epinephrine as following groups: 1) control (without supplementary injection) 2) buccal infiltration 3) lingual infiltration 4) buccal_lingual infiltration. Intensity of pain was assessed based on HP-VAS (0-170 mm) in different intervals including access cavity preparation, pulpotomy and pulpectomy. All data were statistically analyzed using Chi-square, T-test and Kruskal-wallis.Result: There is no statistical differences regarding intensity of pain among all groups (P>0.05). However in first molar both buccal and buccal_lingual supplemental infiltrations were significantly more successful than controls (P=0.02 and P=0.005, respectively). In addition buccal_lingual supplemental infiltration in second molars showed higher success compare to control. (P=0.005)Conclusion: It seems that a new approach of buccal_lingual infiltration of Articaine may improve the anesthesia in mandibular molars with symptomatic irreversible pulpitis. However, none of the above methods reach to 100% success.

BACKGROUND & AIM: The importance of oral dysplasia is in this regard that a percentage of these lesions can progress to cancer. According to the research on cutaneous squamous cell carcinoma, complement factor I may play a role in progression of squamous cell carcinoma. The aim of present study was to evaluate immunohistochemical expression of complement factor I between normal and dysplastic oral mucosa.MATERIAL & METHODS: In this case-control study, studied group was consisted of paraffin-embedded tissue blocks of 30 dysplastic oral mucosa samples and 30 normal oral mucosa samples (as control group).4 μ sections were prepared from tissue blocks and stained with complement factor I antibody at pathology laboratory using immunohistochemistry technique. In this study, percentage of stained cells and staining intensity of them was considered and data analyzed by Mann-U-Whitney test. Significancy level was set as P-value of lower than 0.05.Result: 25 cases of normal mucosal samples and 20 cases of dysplastic mucosal samples didn’t stain with this antibody. Mean percentage of stained cells in normal mucosa was 1.5±4.1 and in dysplastic mucosa was 4.16±6.7. (p<0.1) There was no statistically significant difference between normal and dysplastic oral mucosa with regard to mean percentage of stained cells. Semi-quantitative classification of percentage of stained cells also didn’t show any statistically significant difference between normal and dysplastic oral mucosa. Also, with regard to staining intensity, no statistically significant difference was observed between normal and dysplastic oral mucosa.Conclusion: According to immunohistochemical expression of complement factor I didn’t have significant difference between normal and dysplastic oral mucosa, it seems that this factor don’t play a role in initiation of carcinogenesis.

Background & aim: Fiber reinforced composite (FRC) has become a considerable material in restorative dentistry. In this work the effect of different UHMWPE fiber content and fumed silica nanoparticle incorporation on the flexural properties and fracture toughness of UHMWPE fiber-reinforced dental composite was studied.Materials and Methods: FRC used in this experimental study, was made of BisGMA/TEGDMA (70.30) resin and silanized corona treated UHMWPE fibers. The flexural strength and flexural modulus of the FRCs were determined on 2 mm×2 mm×25 mm specimens. The fracture toughness (the critical stress intensity factor, KIC) of the composites was also evaluated using a three-point single edge notch beam (SENB) bending technique. To investigate the effect of fiber content on mechanical properties, three different fiber volume fraction (41%, 33% and 25%) were used. Treated nanosilica filler with different weight percentage (0wt%, 10 wt% and 15 wt%) were added to composite samples to evaluate the effect of nanoparticle incorporation on mechanical properties. The nanoparticles distribution was studied by transmission electron microscopy (TEM). The results were submitted to statistical analysis through ANOVA complemented by Tukey’s test at a significance level of 5%.Results: The results show that flexural strength, flexural modulus and fracture toughness of the samples increases with increase in the fiber percentage and this increasing in FRC is significant (P˂0.05), (flexural strength (225.7±22.2 MPa), flexural modulus (45.225±5.1 GPa), fracture toughness (6.832±1.3 MPa.m1/2). Nanoparticles incorporation (10%wt, 15%wt) show significant reduction (P˂0.05) in flexural strength of the composites.Conclusion: Fracture toughness and flexural properties of FRC increase with increasing fiber content. Also nanoparticles distribution and dispersion are two important factors to determine mechanical properties of hybrid composites.

Background & aim: Esthetic attention of teeth is increasing, nowadays. After aging, restorative composite materials lead to discoloration and bleaching is one of the effective ways to eliminate of restorative composite discolorations. The aim of this study was to investigate discoloration after office bleaching with Hydrogen peroxide 40%.Materials and Methods: in this experimental in vitro study, From each composite (Z100, Z250, Z350, P90) A total of 24 composite discs were prepared with dimensions of 3 * 8. Aging and staining process is done for samples in 4 weeks, then spent the 5000 cycle in Thermocycling devices. The samples are numbered and base line color of each composite is record. Samples were divided into two subgroups with 12 member, and each subgroup exposed to different treatment: 1- untreated control group 2- hydrogen peroxide 40% (Office B.). After 14 days of treatment Composite recorded secondary colors and color changes were calculated. The data were analyzed by ANOVA and Tukey and a significance level of 0.05 was determined.Results: Discoloration after bleaching in composite Z100, Z250, Z350 and P90 were (16.04±2.68), (21.13±3.43), (16.61±2.26) and (7.53±2.36), respectively which had significant difference with control group. (p<0.05). Discoloration of Z250 had significant difference compare with others. (p<0.001)Conclusion: office bleaching causes significant color change in the all types of stained composites and The greatest effect was on the Z250.

Background & aim: Accurate radiographic images are necessary for correct diagnosis and appropriate treatment plan. In patients with permanent teeth and is scheduled to receive comprehensive orthodontic treatment with full band and bracket setup, full mouth intraoral radiographic examination is recommended. Panoramic and lateral cephalometry radiographics are also among documents of patients which it refers as ORD or Orthodontic Radiographic Documentation. Due to reliable 3D images of CBCT, high geometric accuracy and reduce errors in linear and angular measurements, most recently its application in the field of dentistry, such as the use of implants, oral and maxillofacial surgery, orthodontics and endodontics is on the rise, so knowing the dose of target organs in different imaging modalities is essential.Method and materials: In this experimental study, calibrated TLD (thermoluminescence dosimeter) was placed in 12 different phantom organ. Then digital panoramic imaging, lateral cephalometry, full mouth periapical and large FOV of two different CBCT units was applied. For reliability of the study, dosimetry was performed three times and then mean and standard deviation of the results were calculated and were analyzed with ANOVA statistical test.Results: The highest absorbed dose was the right sub mandibular salivary glands with CBCT ASAHI by 4997 svμ followed by right ramus bone marrow with the CBCT ASAHI, and the lowest dose belongs to the frontal lobe of brain with digital intra-oral radiography which was 16 svμ. Totall, obtained absorbed dose for ASAHI CBCT was more than NEWTOM CBCT. The absorbed dose for CBCT scanners were higher than digital intra-oral and extra-oral imaging.Conclusion: Absoreb organs dose in the head and neck with large FOV of CBCT imaging is more than digital intra-oral and extra-oral imaging. But when the additional information and detailed of CBCT is necessary for diagnosis and appropriate treatment plan, if it is possible, the ALADA should be consider while obtaining the scan.

Aim and Background: One of the problems encountered in the restorative dentistry is the degradation of composites in the presence of foods, saliva, and their interaction. In view of that, this study evaluates the effect of Heptane food simulating liquid on the micro-hardness of four different Z250, Z350XT, P60, and P90 composites.Materials and Methods: In this experimental-in vitro study, 20 disks of 2 mm in height and 5 mm in diameter are prepared from each composite (leading to a total number of 80 samples). Using an LED light cure unit, the specimens are carefully polymerized for 40 seconds under a 1000 mw/cm2 light radiation and then immediately polished under water spray by means of subsequent application of coarse to super-fine aluminum oxide disks. These samples are immersed in a 37oC distilled water dark tank for 24 hours. Next, samples of each composite are randomly put into two equal groups of ten. The micro-hardness of each sample is then measured in a Vickers microhardness testing machine. Next, keeping temperature at 37 ºC, the first (control) group and the second (test) group are immersed for 7 days in distilled water and Heptane food simulating liquid, respectively, and the micro-hardness is re-evaluated for each disk. Finally, the recorded data are analyzed using one-way analysis of variance (ANOVA) and Tukey's multiple comparison tests with significance level of lower than 0.05 in SPSS V20 software.Results: It is found that immersing composite disks in distilled water meaningfully increases the micro-hardness of samples (P<0.05). The same finding has been confirmed for the P90 disks which are kept in Heptane. (p=0.01) The micro-hardness of other composites (Z250, Z350XT, and P60) is also increased in the presence of Heptane but none of them was significant (P>0.05).Conclusions: The micro-hardness of samples is increased in the presence of both distilled water and Heptane food simulating liquid but the amount of this increase totally depends on the type of composite and also the sample storage environment.

Background: Stafne bone defect is a rare asymptomatic finding in radiographs. Parotid Stafne cysts are very scarce and can be located on buccal or lingual aspect of mandibular ramus.Case report: Two well-defined radiolucent lesions were found incidentally on the panoramic radiograph of a 37 year old man. The lesions were located on the buccal side of left mandibular ramus above the lower jaw angle. CBCT showed buccal cortical plate perforation and involved more than half diameter of bone structure. No change in the size of lesion was noticed in the six-month and one-year follow-ups.Conclusions: Infrequent Stafne bone defect appearances (especially parotid related Stafne cysts) should be considered to prevent misdiagnosis.