JOURNAL OF ISLAMIC DENTAL ASSOCIATION OF IRAN (MAJALLAH-I-DANDANPIZISHKI)
Year:2012 | Volume:23 | Issue:4 (81)|Papers Count:12

Background and Aim: Consumption of acidic carbonated beverages is the most important etiologic factor for dental erosion. The aim of this study was to determine the changes in microhardness of enamel in sound deciduous canine exposed to cola (Zamzam), lemon soft beer (Behnoosh) and tap water.Materials and Methods: This experimental study was performed on 30 sound deciduous canines without caries and cracks. The teeth were divided into three groups and primary microhardness was determined. Microhardness was 359.2±33.1 in Delster, 371.97±25.5 in ZamZam Cola and 325.77±52 in water. Specimens were taped to leave the 4mm² window of exposed enamel. Then the specimens in each group were exposed randomly into tap water, lemon soft beer and cola for 5 minutes. Finally, secondary microhardness of the enamel was measured by the Vickers method. The enamel microhardness change in each group was studied with the Paired T test and between the groups with ANOVA test.Results: The results showed that secondary microhardness of deciduous enamel after exposure to tap water was 98.2% of primary microhardness. Secondary microhardness for carbonated beverage and soft beer was 81.9% and 86.7% of the original microhardness, respectively. The changes were statistically significant in the beverage and soft beer groups (P=0.001), but not significant for tap water (P=0.07).Conclusion: Zamzam Cola and Delester decreased the microhardness of deciduous tooth enamel. The decrease of microhardness was less for Delster compared to Zamzam Cola.

Background and Aim: Extensive caries in the primary anterior teeth is one of the highly prevalent dental issues in primary dentition. On the other hand, special considerations for restoring these teeth are a challenge for the dental practitioner. The aim of this in vitro study was to compare the tensile bond strength of a new method of Reverse Metal Post Technique (RMPT) with two conventional methods.Materials and Methods: Eighty-four extracted primary canines were assigned to three equal groups. The crowns were cut-off 1 mm coronal to CEJ and the root canals were prepared for the next stage. The teeth were restored according to the groups they were assigned to; Group 1 with composite posts; Group 2 with alpha-shaped orthodontic wires; and Group 3 with the RMPT. The specimens were then subjected to tensile force by a mechanical testing machine. Data were analyzed using ANOVA, tukey post hoc, Chi-square and student t test (a=0.05).Results: The mean tensile bond strength for groups 1, 2 and 3 were 6.26± 2.40, 7.35±1.60 and 9.88±2.60MPa, respectively. A significant difference was observed between group 3 and the two other groups (p<0.001). However, the difference between groups 1 and 2 was not statistically significant (p>0.05).Conclusion: The tensile bond strength was significantly higher in RMPT than the two conventional methods used for restoring severely destroyed primary anterior teeth.

Background and Aim: The antimicrobial activity of silver nanoparticles has been investigated in medical fields in recent years, but its effect on dental plaque micro-organisms has not been studied. The aim of the present study was to evaluate the in vitro antimicrobial properties of nanosilver on two dental plaque microorganisms and to compare it with chlorhexidine.Materials and Methods: In this experimental study, antibacterial effects of silver nanoparticles and chlorhexidine against Streptococus sanguis and Actinomyces viscosus were determined by minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) using microdilution method. Each experiment was repeated at least five times to ensure the accuracy of testing.Results: Results showed that the MIC of soluble silver nanoparticles and chlorhexidine for Streptococcus sanguis were 16 and 256 μg/ml, respectively. Soluble silver nanoparticles had an MIC of 4 and chlorhexidine had an MIC of 64 µg/ml for Actinomyces viscosus. The MBC of soluble silver nanoparticles and chlorhexidine for Streptococcus sanguis were 64 and 512 µg/ml, respectively and for Actinomyces viscosus these figures were 16 and 102 µg/ml, respectively.Conclusion: Silver nanoparticles have strong antibacterial activity against Streptococus sanguis and Actinomyces viscosus which was achieved by lower doses in comparison to chlorhexidine mouthwash.

Background and Aim: Accurate determination of working length in root canal therapy is very important for success of the process. Different methods such as electronic apex locators have been introduced for determination of working length. The aim of this in vitro study was comparison of the accuracy of two electronic apex locators, Foramatron V and Ipex, in determination of working length in human single root teeth.Materials and Methods: In this in vitro study, 100 human single root, single canal maxillary incisors with developed apex without curve were used. The teeth were cleaned after extraction and stored in normal salin. After preparing access cavity, the actual length of each canal was determined by an anatomic method placing a k-file into the canal so that the file tip touched the apical foramen. After preparing the experimental environment, the teeth were placed in the model at the level of CEJ and the lengths of the teeth were determind with Ipex and Formatron V according to their code. The acceptable limitation was ±0.5 millimeter to the actual working length. After collection of data, Mac Nemar and Paired t-test were used for statistical analysis.Results: According to the results of this study, the accuracy of length determination was 64% and 63% for Foramatron V and ipex, respectively in the range of canal length±0.5 mm. There was no significant statistical difference between these two devices.Conclusion: There was no significant difference between Ipex and Foramatron V. Therefore, Foramatron V may be used for working length determination.

Background and Aim: Class V cavities are mostly filled with tooth colored restorations. Microleakage is an important problem with tooth colored restorations. Some studies show that ultrasonic scalers could cause microleakage. The aim of this study was to examine the effects of ultrasonic scaling on three different tooth colored restorations; namely, composite resin, glass-ionomer and comboglass.Materials and Methods: In this in-vitro study, sixty extracted premolars were randomly divided into three groups of 20 teeth. In all the teeth the same size class V cavity was prepared. First, second and third group teeth were filled with composite, gloss inomer and compoglass, respectively. After thermocycling, half of the teeth in each group were scaled with ultrasonic (test group); whereas, the other half were used as control. Then, all the specimens were kept in 2% fuchsin for dye penetration testing for approximately 24 hours. After sectioning, the specimens' microleakage was quantified with steriomicroscope. The data were analyzed statistically by Kruskal-Wallis analysis and Mann-Whitney U-tests with Bonferroni's correction.Results: In the first (composite) and third (compoglass) groups ultrasonic scaling had no effect on microleakage (P>0.05); whereas, in the second group (glass-ionomer) ultrasonic scaling caused more microleakage than the control group. The difference was statistically significant (P<0.001).Conclusion: The ultrasonic scaler should be used with caution around class V cavities filled with tooth colored restorations because of the possible microleakage effect.

Background and Aim: It has been suggested that delivering ozone into a carious lesion might reduce the number of cariogenic bacteria. This possibly could arrest the progress of the lesion and in the presence of fluoride perhaps allow remineralization. This study investigated the effect of ozone on leathery primary root caries.Materials and Methods: The study was a clinical trial using a split mouth design. A total of 23 pairs of bilateral leathery primary root caries were selected from Shahid Beheshti Dental School. After brushing, DIAGNODENT values of the samples were recorded in three points. Half of the samples which had been randomly selected were treated for 12 seconds using OZOTOP (MECTRON SWISS Inc.) The opposite arch was selected as the control group. Fluoride therapy was performed on both groups and DIAGNODENT values were measured again. This process was repeated a month later and DIAGNODENT values were recorded. Three months after the initial treatment DIAGNODENT values were measured again. Results were evaluated by using paired t test. The statistical significance level was set at P<0.05.Results: The highest reduction was observed within the group of combined use of fluoride and ozone after 3 months (2.0439). Comparisons between 3 months from baseline in the intervention group and the control group using paired t-test determined statistically significant differences (P value<0.001(.Conclusion: In a 3-month period, the combined effect of fluoride and ozone in reducing the DIAGNODENT value was higher than using fluoride alone.

Background and Aim: There are several factors which play an important role in the retention of resin bonded retainers (RBRs) such as prothesis design, type of alloy and thickness of retainers. The purpose of this study was to compare the retention of wings made up of Vera bond, Super cast and Ticonium alloys.Materials and Methods: In this experimental study, the samples consisted of fifteen RBR made on 15 metal central incisors and canines (mounted with a distance equal to a lateral incisor tooth) on an acrylic block. The samples were divided into three groups of five with retainers with thicknesses of 0.2mm consisting of three different alloys; namely, Vera bond, Super cast and Ticonium. They were cemented with resin cement panavia F. Samples were then placed in instron machine for determining the force needed to separate the retainers. Data were analyzed by one way ANOVA test.Results: Vera bond wings had a tensile bond strength of 35.2440 Kgf; whereas Supercast and Ticonium had a tensile bond strength of 24.8520 Kgf and 21.0860 Kgf, respectively.Conclusion: Results showed that the mean retention of RBRs with wings made up of Vera bond alloy was significantly higher than that of Super cast and Ticonium. In addition, the difference between the mean retention of wings made up of Super cast and Ticonium was not statistically different.

Background and Aim: Solubility is one of the shortcomings of dental materials that causes decreased physical and mechanical properties and longevity of the restoration. The aim of this in vitro study was to compare the solubility of the resin modified glass ionomer cement and a base containing hydroxyapatite.Materials and Methods: This experimental study was carried out according to ISO4049:2000(E) and ISO 9917-1:2007(E). Ten samples of each of the two materials including resin modified glass ionomer and a base containing hydroxyapatite were evaluated for solubility in distilled water and artificial saliva. Evaluation of acid solubility was performed in lactic acid with pH=2.7±0.02 for 24 hrs. The data were analyzed by two-way ANOVA test.Results: The mean values of solubility in distilled water for RMGIC and base containing hydroxyapatite were 0.6 (±0.3) and -1.6 (±1.4), respectively. The means of saliva solubility were 0.007 (±0.8) and 1.07 (±1.4), respectively for the mentioned materials. The mean value of acid solubility was 0.000474 (±0.000784) for RMGIC and 0.000334 (±0.000221) for Lime-lite. There was no significant difference between values of water sorption and solubility of the two materials (p>0.05).Conclusion: The solubility of the two tested materials in distilled water, artificial saliva and acid was very little and there was no significant difference between them in this regard.