Vol 10, No 1 (2013)
Proceeding Abstracts
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Interleukin-1β (IL-1β) is one of the most important cytokines which seems to have an important role in the inflammatory process in gingival and peri-implant tissues. The aim of this split-mouth study was to investigate the relationship between the concentration of IL-1β in gingival crevicular fluid (GCF) and peri-implant crevicular fluid (PICF) and clinical parameters such as plaque index (PI), gingival index (GI), pocket depth (PD) and bone loss (BL).In 32 patients, PICF and GCF samples of 41 implants and 41 contralateral teeth were collected and IL-1β was determined by enzyme-linked immunosorbent assay (ELISA). PI,GI,PD and BL were recorded for each of the samples.The positive correlation between the level of IL-1β and PI, GI, PD and BL in both groups was observed (P<0.0001). In similar conditions, the level of IL-1β was greatly higher in PICF than GCF (75.26 pg/μl and 45.71 pg/μl, respectively) (P=0.001).The findings of the present study indicated that the level of IL-1β may be an important supplement to clinical findings in measuring the health status of gingival or peri-implant tissues.
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Honey has antibacterial activity. The aim of this study was to evaluate the antibacterial activity of honey on Streptococcus mutans and Lactobacillus.In this in vitro study, solutions containing 0%, 5%, 10%, 20%, 50% and 100%(w/v) of natural Hamadan honey were prepared. Each blood (nutrient) agar plate was then filled with dilutions of the honey. The strains of bacteria were inoculated in blood agar for 24 hours at 37°C and were adjusted according to the McFarland scale (10×10 cfumcl(-1)). All assays were repeated 10 times for each of the honey concentrations. Data were analyzed by non parametric Chi-Square test. Statistical significance was set at α=0.05.Significant antibacterial activity was detected for honey on Streptococcus mutans in concentrations more than 20% and on Lactobacillus in 100% concentration (P<0.05).It seems that antibacterial activity of honey could be used for prevention and reduction of dental caries.
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Non-steroidal anti-inflammatory drugs (NSAIDs) have shown antibacterial activity in some recent studies. The aim of this study was to evaluate the antibacterial effect of diclofenac against Enterococcus faecalis (E. faecalis) as a resistant endodontic bacterium in comparison with ibuprofen, calcium hydroxide and amoxicillin.The antibacterial activity of materials was evaluated using agar diffusion test and tube dilution method. Mixtures of 400 mg/ml of materials were prepared. The bacteria were seeded on 10 Muller-Hinton agar culture plates. Thirty microliter of each test material was placed in each well punched in agar plates. After incubation, the zone of bacterial inhibition was measured. Minimum inhibitory concentration (MIC) of the test materials was determined by agar dilution method. One-way Analysis of Variance (ANOVA) followed by Sidak post hoc test was used to compare the mean zone of microbial growth in the groups.There were significant differences between the two groups (p< 0.05). Results of the agar diffusion test showed that antibiotics (amoxicillin, gentamycin) had the greatest antibacterial activity followed by NSAIDs (ibuprofen, diclofenac). Ca(OH)2 failed to show antibacterial activity. Diclofenac and ibuprofen showed distinct antibacterial activity against E. faecalis in 50 μg/ml and above concentrations.Within the limitations of this in vitro study, it is concluded that diclofenac and ibuprofen have significantly more pronounced antibacterial activity against E. faecalis in comparison with Ca(OH)2.
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The T helper 17 (Th17) cells have been suggested to have osteoclast activating effects while T helper 2 (Th2) cells are considered to have an osteoprotective role in periodontitis. This study was to compare the markers of Th17 cells (RORC2 and IL-17 genes) with that of Th2 cells (IL-4 and GATA-3 genes) between healthy and periodontitis tissues.The samples were obtained from patients with periodontitis and healthy tissues. The mRNA expression levels of IL-17, RORC2, IL-4 and GATA-3 were measured in both groups using quantitative RT-PCR. The results were compared using SPSS 11.0. Correlation coefficient was analyzed by Spearman's rho test. Mann-Whitney was used to measure the difference between IL-17 and IL-4 as well as RORC2 and GATA-3.In periodontal lesions, the expression levels of all markers were significantly higher than the healthy tissue (p≤ 0.001). The results showed a significant increase in the number of markers of Th17 (RORC2 and IL-17 genes) compared to markers of Th2 (GATA-3, IL-4) in patients with periodontitis compared to controls (p≤0.002). A positive correlation between IL-17 and RORC2 (p≤0.05) and between IL-4 and GATA-3 (p≤0.001) was found.The results show that expression levels of IL-4, GATA-3, IL-17 and RORC2 increase significantly in periodontal lesions compared with the controls. In periodontal lesions, IL-17 levels are significantly greater than IL-4, which plays a protective role against alveolar bone loss.
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In recent years, newly developed solvent-free dental adhesives have been introduced. The aim of this study was to evaluate the marginal integrity of a new one-step solvent-free self-etch adhesive and to compare it with a commonly used two-step self-etch adhesive as the gold standard.Class V cavities (2×4×1.5 mm) were prepared on the buccal aspects of 28 human premolars. The cervical margins of the cavity preparations were placed 1 mm apical to the CEJ. Clearfil SE Bond (CSEB) (two-step self-etch adhesive) and Bond 1SF (B1SF) (one-step self-etch adhesive) were applied to the cavities in groups 1 and 2 (n=14), respectively. Then, the specimens were restored with A2 shade of APX composite resin. Each group was evaluated for dye penetration under a stereomicroscope at ×32 after 24 hours and 500 rounds of thermocycling. Statistical analyses were carried out using Mann Whitney test (α=0.05). In addition, in each experimental group, two specimens were prepared for analysis under SEM.There were no significant differences in enamel margin microleakage between the two adhesives used (P=0.24(; whereas, there were significant differences in dentin margin microleakage between CSEB and B1SF (P=0.004). Dentin microleakage of B1SF was higher than that of CSEB.Results showed that the enamel marginal integrity of B1SF as a newly developed one-step solvent-free self-etch adhesive was similar to that of CSEB as a commonly used two-step self-etch; however, dentinal sealing of CSEB was better than that of B1SF.
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High variability in delivering the target torque is reported for friction-style mechanical torque limiting devices (F-S MTLDs). The effect of aging (number of use) on the accuracy of these devices is not clear. The purpose of this study was to assess the effect of aging on the accuracy (±10% of the target torque) of F-S MTLDs.Fifteen new F-S MTLDs and their appropriate drivers from three different implant manufacturers (Astra Tech, Biohorizon and Dr Idhe), five for each type, were selected. The procedure of peak torque measurement was performed in ten sequences before and after aging. In each sequence, ten repetitions of peak torque values were registered for the aging procedure. To measure the output of each device, a Tohnichi torque gauge was used.Before aging, peak torque measurements of all the devices tested in this study falled within 10% of their preset target values. After aging, a significant difference was seen between raw error values of three groups of MTLDs (P<0.05). More than 50% of all peak torque measurements demonstrated more than 10% difference from their torque values after aging.Within the limitation of this study, aging as an independent factor affects the accuracy of F-S MTLDs. Astra Tech MTLDs presented the most consistent torque output for 25 Ncm target torque.
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Tooth/implant supported fixed prostheses may present biomechanical design problems, as the implant is rigidly anchored within the alveolus, whereas the tooth is attached by the periodontal ligament to the bone allowing movement. Many clinicians prefer tooth/implant supported fixed prosthesis designs with rigid connectors. However, there are some doubts about the effect of attachment placement in different prosthesis designs. The purpose of this study was to examine the stresses accumulated around the implant and natural teeth under occlusal forces using three dimensional finite element analysis (3D FEA).In this study, different connection designs of tooth/implant fixed prosthesis in distal extension situations were investigated by 3D FEA. Three models with various connection designs were studied; in the first model an implant rigidly connected to an abutment, in the second and third models an implant connected to abutment tooth with nonrigid connector in the distal part of the tooth and mesial part of the implant. In each model, a screw type implant (5×11mm) and a mandibular second premolar were used. The stress values of these models loaded with vertical forces (250N) were analyzed.There was no difference in stress distribution around the bone support of the implant. Maximum stress values were observed at the crestal bone of the implant. In all models, tooth movement was higher than implant movement.There is no difference in using a rigid connector, non rigid connector in the distal surface of the tooth or in the mesial surface of an implant.
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Cephalometry and its related analyses have an important role in the evaluation of orthodontic patients. Access to an analysis that gives maximum information in the least possible time is an effective way to indicate craniofacial disharmony; therefore, craniofacial templates are very useful tools. The purpose of the present study was to provide orthodontic craniofacial templates for 8-14-year-old Iranian girls.One thousand two-hundred and nine girls (age range, 8-14 years) were examined. Eighty of these cases were finally chosen for the study and their lateral cephalograms were traced. Both Basion-Nasion (Ba-N) and Sella-Nasion (S-N) lines were selected for superimposition in this study. Based on these two mentioned lines, a template for each age was designed. Simple linear regression and multivariant regression analysis were used to evaluate the angles and to landmark the vectors, respectively.Findings show that most points change significantly at different ages in the S-N method. In the Ba-N method, all points except for S and Ba have significant changes at different ages.Templates that resulted from both methods were the same and alteration in the reference line and points does not change the total form of the average tracings of each age.
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Successful endodontic therapy depends on adequate mechanical and chemical debridement of the canal which requires knowledge of the canal morphology. Conventional radiography has been used to evaluate the canal type; however, direct digital radiography has recently been practiced for this purpose due to the shortcomings of conventional radiography. The aim of the present study was to compare the accuracy of digital and conventional radiography taken at 0° and 30° angles in the diagnosis of the canal type of extracted maxillary premolars.This diagnostic study was performed on 90 extracted maxillary premolars. Conventional and digital radiographies were taken of all teeth at 0° and 30° horizontal angles. The images were assessed by an oral and maxillofacial radiologist. The clearing technique was used as the gold standard. The canal type was determined using Weine classification. The agreement between each one of the 4 radiographic modalities and gold standard was determined by kappa statistics.The kappa values for the agreement of parallel conventional, 30° conventional, parallel digital and 30° digital modalities with the clearing technique were 0.059, 0.215, 0.043 and 0.391, respectively. Parallel modalities were unable to determine the tooth canal type. Radiographic images taken at 30° significantly determined the canal type, although only a poor level of agreement was noted between the two modalities and the clearing technique.All modalities had limited value to determine the root canal type in maxillary premolars. However, direct digital imaging taken at 30° angle showed the highest accuracy for canal type assessment.
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This study aimed to evaluate enamel roughness after adhesive removal using different burs and an Er:YAG laser.The buccal surfaces of forty human premolars were sealed by two layers of nail varnish, except for a circular area of 3 mm in diameter on the middle third. The enamel surfaces were initially subjected to profilometry analysis and four parameters of surface irregularity (Ra, Rq, Rt and Rz) were recorded. Following bracket bonding and debonding, adhesive remnants were removed by tungsten carbide burs in low- or high- speed handpieces (group 1 and 2, respectively), an ultrafine diamond bur (group 3) or an Er:YAG laser (250 mJ, long pulse, 4 Hz) (group 4), and surface roughness parameters were measured again. Then, the buccal surfaces were polished and the third profilometry measurements were performed.The specimens that were cleaned with a low speed tungsten carbide bur showed no significant difference in surface irregularity between the different treatment stages (p>0.05). Surface roughness increased significantly after clean-up with the diamond bur and the Er:YAG laser (p<0.01). In comparison between groups, adhesive removal with tungsten carbide burs at slow- or high-speed handpieces produced the lowest, while enamel clean-up with the Er:YAG laser caused the highest values of roughness measurements (P<0.05).Under the study conditions, application of the ultrafine diamond bur or the Er:YAG laser caused irreversible enamel damage on tooth surface, and thus these methods could not be recommended for removing adhesive remnants after debonding of orthodontic brackets.
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The effects of closely adapting a prefabricated fiber to the post space remain unknown. The purpose of this study was to quantify the microleakages of a custom adapted fiber-reinforced post, a prefabricated quartz fiber post and a cast post using nondestructive methods.Sixty-five extracted human premolars were endodontically treated and randomly divided into three groups (n=15), which were restored using a cast post-and-core, a custom adapted fiber post (Refropost) with a microhybrid microfiller resin composite (Gradia), or a prefabricated quartz fiber post (DT light post) and two groups of control (n=10). All groups were cemented using a dual polymerizing resin cement (Panavia F2.0). A composite core (Z100) was used for the fiber posts. The microleakage was calculated for the experimental and control groups before and after thermal cycling and cycling loading using a radiotracer solution (thallium 201 chloride) and a gamma counter device. Data were subjected to statistical analysis of ANOVA and Tukey HSD at significant level of P< 0.05.Significantly lower microleakage values were found for the cast post-and-core (mean value =16.04 ×10(4)) and custom adapted fiber post groups (mean value=14.36×10(4)). Thermal cycling and cyclic loading had no significant effect on the microleakage value of any tested group.Post systems with improved adaptation showed similar microleakage to casting posts.
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Based on the evidence regarding the relationship between inflammatory processes and stress responses, the present study investigated the association between psychological stress and elevation of inflammatory mediators related to periodontal disease in adult patients.The study consisted of 50 patients including 25 patients with chronic periodontitis and 25 cases with aggressive periodontitis. Twenty-five healthy subjects without any evidence of periodontal disorder were also randomly selected as the control group. The clinical parameters including plaque index (PI), bleeding on probing (BOP), probing depth (PPD) and clinical attachment loss (CAL) were recorded and GCF samples were collected for analysis of GCF contents of IL-6 and IL-1β levels. The Kettle stress questionnaire was also used to determine stress severity.IL-1β was significantly higher, but IL-6 was only slightly higher(marginal p-value=0.058)The median score of stress was higher in aggressive periodontitis than the chronic disorder and also in the two periodontal disease groups than the healthy subjects. Among studied clinical parameters, CAL and PPD were positively correlated with the GCF IL-1β level. No significant correlations were found between clinical parameters and GCF IL-6 level. There were strong positive relationships between stress severity and in both aggressive and chronic periodontitis; however stress did not influence GCF contents of IL-6.Psychological stress has a pivotal role in the stimulation of inflammatory processes via IL-1β increase in aggressive and chronic periodontitis.
