JOURNAL OF ISLAMIC DENTAL ASSOCIATION OF IRAN (MAJALLAH-I-DANDANPIZISHKI)
Year:2011 | Volume:23 | Issue:3 (80)|Papers Count:13

Background and Aim: The goal of this study was to investigate the stability of a dental implant which is implanted in clinical models of the mandible and to evaluate the effectiveness of strength, radius and thickness of the bone around a dental implant by using finite element method.Materials and Methods: A 3D wire frame model of the mandible was developed based on computer tomography data of a 25-year-old subject in MIMICS. This model was smoothed in CATIA. Finally, a 3D model of the dental implant was assembled in the mandible and finite element analysis was done on the model with various material properties, loading condition and constraints in ABAQUS.Results: In the clinical models, the highest stress was found in the mandible with a thin layer of cortical bone around the core of the cancellous bone with the lowest density. It was shown that increase of the cortical bone radius resulted in the decrease of stress in the mandible. The 2 mm thickness of the cortical bone around a dental implant was evaluated as the critical thickness of the bone.Conclusion: Increase of stiffness of the cortical or cancellous bones resulted in increase of the stress in that specific part of the bone. In addition, the increase of the bone thickness was more considerable in less than 2 mm thicknesses.

Background and Aim: Based on the attraction of the world society to traditional treatment and the importance of drug extraction of natural material and plants, in this in vitro study the effect of hydroalcoholic extract of Salvia officinalis and Carum copticum which are very useful in the traditional treatment of mouth and teeth disease have been determined against cariogenic bacteria.Materials and Methods: In this experimental study, hydroalcoholic extracts have been prepared after sterilization of the extracts by special filter from Salvia officinalis and Carum copticum using the maceration method (serial dilution of the sample by the method). Their antibacterial activity against Streptococcus mutans, Lactobacillus rhamnosus and Actinomyces viscosus have been evaluated by the broth macrodilution method. Results have been analyzed with Mann-Whitney test.Results: MIC (Minimum Inhibitory Concentration) of Salvia officinalis and Carum copticum for Streptococcus mutans were 6.25 and 12.5 micro gram per milliliter, respectively, These figures were 1.56 and 6.25 micro gram per milliliter for Lactobacillus rhamnosus and 12.5 and 25 micro gram per milliliter for Actinomyces viscosus.Conclusion: Both extracts had inhibitory effects on growth in all three bacterial species. Salvia officinalis had a greater effect on inhibition of growth in all three bacterial species. Salvia officinalis also had a bactericidal effect in the range of concentration.

Background and Aim: In order to improve the bond strength between fiber post and composite core, many surface treatment procedures have been performed on posts. The aim of this study was to investigate the effects of different surface treatments of a quartz fiber post (DT Light Post) on its bond strength with a composite core (Clearfil Photocore) after water storage and thermo cycling. Materials and Methods: In this interventional, in-vitro study, fifty human canine teeth were endodontic ally treated and post spaces were prepared. A total of fifty fiber posts were divided into five groups according to the surface treatment preformed as control (no treatment), silanenized, sandblasted, sandblasted and silanized, etched with hydrofluoric acid and silanized. After cementation of posts with Panavia F2 in the canals, composite cores were built on them. Consequently, the core parts were cut and stored in deionized water at room temperature for three months. Then thermo cycling in 3000 cycles was performed between 5oC and 55oC. Then two 1 mm-diameter slices were obtained from each core. Finally, bond strength was measured by the push out test. Data were analyzed with one-way ANOVA.Results: Data of all five groups followed normal distribution, but there were no significant differences between them. The sandblasted and silanized group had the highest bond strength (11.3±4.6) and the control group had the lowest bond strength (9.6±3.7).Conclusion: In this study, sandblasting, etching with hydrofluoric acid and silanization did not increase the bond strength between fiber post and composite core.

Background and Aim: Surface roughness of dental restorations can reduce the biological properties and wear the opposite. The goal of this investigation was comparing these process effects on the surface roughness of porcelain.Materials and Methods: In this experimental study, 20 Noritake porcelain disks of 1 cm diameter and 2-2.5 mm thickness with non-percious metal base were fabricated. All samples were finished with medium grit silicone disk and then randomly divided into four groups (n=5). In the first group, the samples were self-glazed. In the second group, the samples were polished (EVE Polisher Kit). In the third group, after self-glazing with a coarse grit stone, the self glaze layer was omitted, then reglazed. The fourth group was similar to the third group, but in the end stage a polishing kit was used. Samples were evaluated with Profilometer and then with SEM. As a result of normal distribution of the data, One-Way analysis of variance (ANOVA) was used for statistical analysis. The mean roughness for the glazed group was 1.06±0.0547; the polished group, 0.92±0.1304; the reglazed group, 1.22±1304; and the polished after glaze group 1.14±0.1342.Results: The polished and polished after glaze groups had a round shape in 100%, but the glazed and reglazed groups had a sharp shape in 60%.Conclusion: The polished surface is less rough compared to the glazed surface and in the polish after glaze group, the surface of the porcelain is less rough compared to the reglaze group.

Background and Aim: The eyes are generally the first feature of the face that are noticed. Loss or absence of an eye may be caused by congenital defects, trauma and malignancies that cause stress in the patients' social life. The art of ocular prosthesis fabrication with the appropriate size, color and contour promotes the patient's physical and psychological comfort and satisfaction. Careful treatment planning with meticulous attention to details can enable the maxillofacial prosthodontist to make a major contribution in the rehabilitation of patients who need ocular prosthesis.Case Report: In this article, the fabrication of a custom ocular prosthesis using stock tray impression technique for a 54-year-old man without any systemic problem who had congenital right ocular defect has been described. In clinical examination, the socket and peripheral tissues were healed.

Background and Aim: The extreme vulnerability to decay in pits and fissures on the occlusal surfaces of the teeth has prompted dental scientists to seek methods of caries prevention. Various criteria, such as bond strength, micro leakage and marginal seal are assessed in the evaluation of sealants. Motivated by the role of pit and fissure sealants in caries prevention, the aim of this study was to compare the micro leakage of Enamel Loc sealant, Concise and Concise +Prompt L-pop resin-based sealants.Materials and Methods: An in vitro study was undertaken using thirty extracted third molars. The teeth were divided into three groups; an experimental group using Enamel Loc as a pit and fissure sealant, a group using Concise and a group using Concise +Prompt L-pop. The teeth were kept in methylene blue dye 2% for 4 hours, sectioned samples were observed with stereomicroscope for the extent of dye penetration and scores were based on Williams and Winter criteria. Three groups of data were statistically analyzed using SPSS 18. Non-parametric Kruskal-Wallis test was used to detect differences among groups (p>0.001).Results: The Enamel Loc sealant micro leakage was significantly more than the two other groups (p>0.001). Furthermore, Concise micro leakage was significantly less than Concise +Prompt L-pop group (p>0.001).Conclusion: The Enamel Loc sealant performed worse in terms of sealing ability than the Concise and Concise +Prompt L-pop resin-based sealants.

Background and Aim: Nowadays, application of sealants is introduced as the most effective method for prevention of occlusal caries. However, the outcome of the microorganisms that are sealed by dental sealants is important. We evaluated the effect of fluoride-releasing fissure sealants on the growth of oral Streptococcus.Materials and Methods: Pure cultures of Streptococcus mutans, sanguis and salivarius were prepared. 0.5 McFarland suspension of newly growed bacteria in normal saline was produced and using a swab, an even culture was prepared on the surface of the culture. Then, experimental fissure sealants were separately placed in 6mm diameter holes in the culture. The samples were divided into four groups; namely, plates merely including microorganisms with no changes applied; plates with microorganisms cured for 20 seconds; plates with microorganisms with cured fissure sealants (20 seconds) placed in them; plates with microorganisms and uncured sealants placed in them. After incubation in 37oC, the diameter of absence of microorganism growth was measured with a ruler in each plate. For each microorganism this test was repeated 6 times and finally the data was analyzed with ANOVA test and t-test.Results: The results showed that fluoride-releasing fissure sealant may prevent growth of Streptococcus sanguis and salivarius (p<0.05) and the effect of this fissure sealant in preventing growth of Streptococcus mutans is not significant (p=0.05). Furthermore, the curing process may increase antibacterial properties of fissure sealants.Conclusion: Clinpro-3M (fluoride releasing) may prevent growth of oral Streptococcus (sanguis, salivarius.(

Background and Aim: Saliva plays a crucial role in preserving and maintaining oral health. Hypo salivation due to head and neck radiation therapy may induce changes to the biochemical properties of the saliva. The aim of this study was to analyze and compare saliva properties before and after radiation therapy in patients with head and neck cancers.Materials and Methods: In this quasi experimental study, 18 patients (13 male, 5 female) with head and neck cancers were evaluated regarding the flow rate of saliva, buffering capacity, amylase, total protein, IgM, IgA, IgG and albumin concentration of saliva prior to and following radiotherapy by schirmer test, pH meter, biuret, turbidometry and spectrophotometry. The oral symptoms due to radiotherapy (xerostomia, loss of taste, difficulty in swallowing, eating and speaking) were evaluated according to the patients' complaints. S tatistical analysis of the results was performed with paired t test.Results: There was statistically significant changes in flow rate (28.27±7.8 Vs. 10.94±12.2), salivary buffering capacity (6.47±0.68 Vs. 5.06±0.52), amylase (2536.5±707.9 Vs. 1053.23±343.5) and IgM concentration (0.87±1.8 Vs. 0.04±0.07) before and after radiation therapy (p£0.05). There were no significant changes in total protein, albumin, IgA and IgG concentration after radiotherapy. Clinical manifestations of xerostomia, loss of taste, difficulty in swallowing and eating, and difficult speaking were detected in 100%, 100%, 83.3% and 16.7% of the cases, respectively.Conclusion: Based on the results of this study, head and neck radiation therapy leads to reduction in salivary flow rate, buffering capacity, amylase and IgM concentration.