Journal of Isfahan Dental School
Year:2018 | Volume:13 | Issue:4 |Papers Count:12

Introduction: Despite all efforts and various studies on reasons for and factors affecting a lack of success in inferior alveolar nerve block, profound pulpal anesthesia is often difficult in mandibular molars during endodontic treatment. The aim of this study was to investigate the effect of pain experienced during previous endodontic treatment on success rate of inferior alveolar nerve block (IANB).Materials& Methods: In this cross-sectional study, 100 healthy adult patients with a diagnosis of symptomatic pulpitis in their first mandibular molar were selected and questioned about experience of pain during previous root canal therapy. Each patient received two mandibular nerve block injections by one operator. If lip numbness happened after 15 minutes, endodontic treatment was initiated. During the treatment, the patients were asked to rate the pain during access cavity preparation or upon insertion of the initial file into the root canal on Heft-Parker visual analog scale (VAS). Success was defined as no or mild pain during treatment. The initial pain was analyzed with Mann-Whitney test; age was analyzed with t-test; and success of anesthesia and gender were analyzed with chi-squared test. Statistical significance was set at p value<0.05.Results: The success rate for the IANB was 30% in the group with pain experience and 74.3% in the group without pain experience during previous endodontic treatment, with significantly higher success rate in the group with no previous pain experience (p value<0.001).Conclusion: There was a significant relationship between pain experienced during previous endodontic treatment and failure rate of IANB.

Introduction: MTA is one of the most commonly used materials in endodontics. Antimicrobial effect is one of the ideal properties of a root-end filing material. The aim of this study was to evaluate the antimicrobial activity of MTA mixed with 1%, 2% and 4% IKI with the use of direct and indirect methods.Materials& Methods: In this experimental study, direct contact test (DCT) was used to evaluate the antimicrobial effect of set MTA, mixed with different concentrations of IKI and distilled water against Enterococcus faecalis, Staphylococcus aureus and Candida albicans, in 30-minute, 1-hour and 24-hour intervals. Colony forming units (CFU/mL) were determined. The agar diffusion test (ADT) (the indirect technique) was used to assess the antimicrobial activity of fresh MTA mixed with 1%, 2% and 4% IKI and distilled water against the microorganisms above. The diameter of the zone of inhibition was measured by calipers. Data were analyzed with SPSS 17, using oneway ANOVA and Kruskal-Wallis, Mann-Whitney and Tukey tests (a=0.05).Results: DCT method showed that the antimicrobial activity of MTA mixed with 2% and 4% IKI against E. faecalis, S. aureus and C. albicans at 24-hour interval was significantly higher than other concentrations (p value=0.021). Antimicrobial activity of MTA mixed with 1% IKI was the same as that of MTA mixed with distilled water, with no significant difference (p value=951). In the indirect method, the antimicrobial effects of MTA mixed with 4% IKI against C. albicans (p value=0.038) and S. aureus (p value =0.042) were significantly higher than other concentrations. Various concentrations of IKI mixed with MTA did not exhibit significant antimicrobial properties against E. faecalis compared to mixing with distilled water (p value=0.864).Conclusion: IKI at 1% and 4% concentrations in the direct method and 4% IKI in the indirect method exhibited higher antimicrobial activity than other concentrations.

Introduction: Considering the importance of glass-ionomer cements (GICs) in dentistry and their poor mechanical properties, the aim of this study was to improve their mechanical properties by manufacturing a glass-ionomer‒carbon nanotube‒baghdadite nanocomposite by adding carbon nanotubes and baghdadite nanoparticles.Materials& Methods: In the present experimental study, carbon nanotubes with 0.5 wt% and baghdadite nanoparticles in 1, 3 and 5 wt% were added to the cement component of a commercial glass-ionomer cement (Fuji ІІ GC) for preparing glass-ionomer‒carbon nanotube‒ baghdadite nanocomposite. Then the mechanical properties of the samples were evaluated by the cold compressive strength (CCS), three-point flexural strength (FS) and diametral tensile strength (DTS) tests. In addition, the fractured sample surfaces were evaluated after the compressive strength test under a scanning electron microscope. Data were analyzed with one-way ANOVA at a significance level of p value<0.05. A total of three samples were evaluated (n=3).Results: Based on the results of mechanical tests, the composite containing 0.5 wt% of carbon nanotubes and 1 wt% of baghdadite nanoparticles exhibited the highest compressive strength, diametral tensile strength and flexural strength. In addition, SEM micrographs indicated a decrease in pores in the composite structure and a decrease in stress concentration and propagation of cracks, resulting in an increase in the mechanical strength of samples.Conclusion: According to the results, the most appropriate sample for dental and orthopedic applications in load-bearing areas is glass-ionomer cement containing 0.5 wt% carbon nanotubes and 1 wt% baghdadite.

Introduction: Extraction of premolars as a part of orthodontic treatment is one of the controversial topics in current dentistry. According to some theories, extraction of first premolars results in a decrease in facial height. The aim of this study was to evaluate the effect of extraction of four first premolars on facial height in patients with class I malocclusion undergoing fixed orthodontic treatment.Materials& Methods: This retrospective study was conducted on 20 patients (17 females and 3 males) with a mean age of 26.6 years. As a part of orthodontic treatment, the four first premolars had been extracted. Pre- and post-treatment lateral cephalometric radiographs of the patients were digitized. Image analyses were conducted by View Box 3.1.1. Paired t-test was used to compare each variable before and after treatment (a=0.05).Results: Mean changes in cephalometric angles in the vertical and sagittal dimensions were not significant, and linear cephalometric variables did not exhibit any significant changes before and after treatment, except for FMA angle which increased significantly (p value<0.05).Conclusion: In the treatment of patients with class I malocclusion in association with extraction of four first premolars, there were no changes in the facial height. Therefore, orthodontic treatment with extraction of the four first premolars does not result in unfavorable skeletal changes.

Introduction: Dimensional stability of alginate impression materials is affected by several factors such as storage time, storage conditions and type of the impression material. This study was conducted to assess the effect of storage time on dimensional stability of two different alginates: Tropicalgin and Chromogel.Materials& Methods: In this experimental study, impressions were made of a master model with four metal cones on the occlusal surfaces of lower first premolars and third molars on both sides (teeth #1, #5, #12 and #16). The Impressions were divided into five groups in terms of the storage time in wet paper towels within a closed plastic bag before pouring the casts (15 min, 30 min, 60 min, 120 min and 24 h). For each group, 20 impressions and a total of 100 impressions were made. The impressions were poured with type III stone (Parsdental, Iran). Six dimensions (D1 to D6) between 4 cones were considered as the gold standard in order to compare with the same dimensions on the stone casts. Distances were measured by a digital caliper and data were statistically analyzed by MANOVA and one-sample t-test.Results: Dimensional changes increased over time for both alginates except for one sample (Tropicalgin at 30-min interval for D1, p value=0.4). There were significant differences between the two materials at all the time intervals except for the first fifteen minutes. Dimensional changes were within the clinically acceptable limits (a change of 1.5% relative to the master model) up to 120 min for both alginates.Conclusion: The dimensional stability of Tropicalgin and Chromogel alginate impression materials was affected by storage time before pouring in stone and the material type.

Introduction: The uncinate process is a key landmark, which is removed at the beginning of endoscopic sinus surgery. In addition, it has a great role in the ventilation of the middle meatus and sinuses. The aim of this study was to visualize and classify anatomic variations of the uncinate process using multiplanar reconstructed CBCT images.Materials& Methods: In this cross-sectional/descriptive study, the CBCT images of paranasal areas of 120 patients (63 males and 57 females)>18 years of age were analyzed. The superior attachment of the uncinate process was observed and classified according to Landsberg and Friedman classification. Pneumatization of the uncinate process and its deviation toward the orbit’s floor were also noted. Data were analyzed with chisquared test and kappa coefficient (a=0.05).Results: No-attachment (blunt) type exhibited the highest prevalence rate (40.4%), followed by attachment to agger nasi cell (Type 2, 33.3%), to lamina papyracea (Type 1, 12.5%), to the middle concha (Type 6, 4.5%), and to the skull base (Type 5, 4.1%). Bifurcation of the uncinate process and concomitant attachment to lamina papyracea and the junction of the middle concha and the cribriform plate (Type 3) exhibited a prevalence rate of 2.9%. Attachment to the junction of the middle concha and cribriform plate (Type 4) were seen in 1.6% of cases. Attachment to the lower rim of the orbit was seen in 2.9% of the cases. The uncinate process pneumatization was seen in 7% of the cases; 3% of the cases exhibited atelectatic and hypoplastic maxillary sinuses.Conclusion: Evaluation of anatomical variations of the uncinate process and its pneumatization before surgery is essential to prevent damage to the surrounding structures during surgery.

Introduction: Biocompatibility of dental materials is one of the most important features that should be studied. The aim of this study was to compare the cytotoxicity of two new endodontic cements and MTA on human gingival fibroblasts.Materials& Methods: In this experimental study, CAAC (calcium aluminateα-aluminate cement), WOLCA (a mixture of wollastonite and CAAC) and MTA were prepared at concentrations of 0.1, 0.01 and 0.001 gr/mL. C165 fibroblasts were added to the culture medium and the cements at concentrations above were added. Cell survival was measured at 24-hour, 48-hour and 7-day intervals. To evaluate the cytotoxicity of cements, the cells were stained with trypan blue solution and viable cells were counted. Data were analyzed with Kruskal-Wallis and Mann-Whitney tests (a=0.05).Results: The control group (with no cement added) exhibited the highest optical density. MTA exhibited higher optical density compared to the two other cements at all the concentrations and at all the time intervals.Conclusion: Both new cements exhibited acceptable cytotoxicity at low concentrations. The results of trypan blue staining showed that the cytotoxicity of CAAC cement at the lowest concentration was not significantly different from that of MTA.

Introduction: Diabetes mellitus and chronic periodontitis are common worldwide disorders and since periodontal diseases are more common and more severe in diabetic patients, the aim of present study was to investigate the relationship between HbA1C serum levels and chronic periodontitis.Materials& Methods: In this case‒control, descriptive/analytical study, the HbA1C levels were evaluated in 55 subjects, 35‒45 years of age, in two groups with and without periodontitis, who were healthy otherwise. Thirty subjects had chronic periodontitis (PPD>2 mm) and 25 subjects had healthy gingiva. HbA1C levels were determined by means of Ichroma equipment. Data were analyzed with independent t-test using SPSS 18 (a=0.05).Results: Independent t-test showed significantly higher serum levels of HBA1C in patients with periodontitis compared to healthy subjects (p value=0.021).Conclusion: Based on the results of the present study, inflammation in chronic periodontitis disturbs the metabolism of glucose, possibly resulting in periodontitis in the long term. Therefore, a definitive diagnosis and treatment of chronic periodontitis along with proper oral health is emphasized.

Introduction: The fitness of a restoration is essential for its longevity, which is affected by different factors, including the type of the alloy used. Due to the production of Minalux nickel-chromium, beryllium-free, alloy in Iran, the aim of this study was to compare vertical margin discrepancy between Supercast and Iranian Minalux alloys.Materials& Methods: In this experimental/observational study, 60 coping wax patterns were fabricated on a metal die which was prepared for porcelain-fused metal crown (PFM) with chamfer finishing line and divided into 2 groups of 30. In the first group, Supercast alloy and in the second group Minalux alloy were used. Castings were prepared and seated on the metal die after minimal internal surface adjustment. The vertical margin discrepancies were measured at four locations (buccal, lingual, mesial and distal) of the die and casting. Then the vertical margin discrepancy in each group was statistically analyzed with SPSS 22, using t-test (a=0.05).Results: Mean vertical margin discrepancy in first group (Supercast alloy) was 117.35 mm, with 137.57 mm in the second group (Minalux alloy). The castings with Supercast alloy were significantly different (p value=0.031) from the Minalux alloys.Conclusion: The results show that the Supercast alloy, due to lower vertical marginal discrepancy compared to Minalux, is better for fabrication of dental restorations.

Introduction: The most fundamental factor in shaping every organization is human resources. The success of any organization depends on the efforts and job satisfaction of its personnel. Therefore, the aim of this study was to assess job satisfaction among Dental School personnel in Isfahan University of Medical Sciences.Materials& Methods: This descriptive/analytical study was conducted on 111 personnel in the Dental School of Isfahan University of Medical Sciences in 2015. Data were collected using a questionnaire on demographic characteristics and a questionnaire on job satisfaction, categorized into five fields, including the nature of work, supervisors, partners, job promotion and payments. Statistical analyses were carried out with SPSS 22, using Mann-Whitney test and Spearman’s correlation coefficient. Statistical significance was set at p value=0.05.Results: This study demonstrated that 68.5% of the personnel exhibited a moderate rate of job satisfaction. The most frequent (63.1%) satisfaction was satisfaction with the nature of the work and the most frequent dissatisfaction (55%) was dissatisfaction with salaries. There were no significant relationships between job satisfaction and age, gender, work experience and educational level (p value>0.05).Conclusion: The majority of the personnel were relatively satisfied with their job and further studies are necessary to solve the existing problems to increase job satisfaction.

Introduction: Amalgam is a safe and effective restorative material in direct restorations. One of the conservative methods for the repair of a fractured amalgam restoration is the use of adhesive materials like composite resin. Therefore the aim of this study was to evaluate the bond strength of composite resin to amalgam with the use of different bonding agents.Materials& Methods: In this in vitro study, 52 acrylic cylinders were made and amalgam containing 43% Ag was condensed into these cylinders. After keeping the amalgam samples at room temperature for 24 hours, the amalgam surfaces were abraded with a diamond bur and all the samples were immersed in an ultrasonic bath. Then the specimens were divided into 4 groups of 13 samples, and each group was treated with different boding agents as follows: group (1), amalgam alloy+primer+total etch (Single Bond); group (2), amalgam alloy+primer+self-etch (G Bond); group (3), amalgam+G Bond; and group (4), amalgam+Single Bond. Composite resin was bonded to prepared amalgam specimens with the use of translucent polyethylene mold and cured by LED Turbo, followed by testing with an Instron machine for shear bond strength. Finally data were analyzed with one-way ANOVA and LSD tests.Results: In this study, the highest bond strength value was recorded in specimens bonded with G Bond bonding agent (9.06 MPa) and the lowest value was recorded in specimens bonded with Single Bond bonding agent (5.14 MPa). The mean shear bond strength values in 4 groups exhibited statistically significant differences (p value=0.001).Conclusion: G Bond bonding agent yielded higher bond strength between amalgam and composite resin than other bonding agents used in this research.