[Effect of ultrasonic scaler on the microleakage of ClV tooth colored restorations]

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. 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. 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]. The ultrasonic scaler should be used with caution around class V cavities filled with tooth colored restorations because of the possible microleakage effect

[ effect of chlorine - dioxide on reduction of bacterial contamination of dental unit water systems]

Dental unit water Systems [DUWS] have been demonstrated to be contaminated with biofilms. This biofilm could be a site for growth and colorization of pathologic microorganisms. The aim of this research was to measure the Total Cultivable Flora [TCF] in DUWS of Khorasgan dental school and the effect of stabilized chlorine dioxide on its reduction. In this research, 60 samples of water from high speed turbines, air-water syringes, cabitrons and wash basins were collected. The samples were cultured in agar nutrition media and incubated for 5 days. After the incubation period, colonial counting was done by HPC method. In the next stage, stabilized chlorine dioxide was added in a container for each unit and ethic samples were taken from air-water syringes, cabitrons and turbine outlets. As for the first stage, after 5 days of culture and incubation, the samples were observed under microscope for counting the bacterial colonies. Kruskal-Walis and Mann-Whitney tests were used for statistical analysis. A high level of bacterial contamination [more than 200 CFU] was observed in high speed turbines, air-water syringes, cavitrons and wash basins. The highest colonial count was observed from cavitron and the lowest from washbasin outlets but the difference was not statistically significant. After using chlorine dioxide, the amount of bacterial colonies was significantly reduced [p < 0.05]. The amount of bacterial contamination in DUWS of Khorasgan dental school was higher than the accepted level. These bacteria were mainly opportunistic. The addition of an anti-bacterial agent in the DUWS will significantly reduce the bacterial count to an acceptable level

prevalance and risk factors of gingivitis among the children referred to Isfahan Islamic Azad University [Khorasgan Branch] dental school, In Iran

The effects of periodontal diseases observed in adults have earlier inception in life period. Gingival diseases in a child may progress to jeopardize the periodontium in adulthood. Therefore, periodontal diseases must be prevented and diagnosed early in the life. Periodontal diseases risk factors must also be identified. The aim of this research was to find the prevalence and identify the risk factors of gingivitis among the children referred to Isfahan [Khorasgan] Azad University Dental School Clinic, Isfahan, Iran. In this research, the prevalence of gingivitis and its related risk factors were determined in 360 school children referred to Isfahan Azad University Dental School clinic. A questionnaire was filled for each student in which some information regarding their parent's education level, family income, and their school results were obtained. The habit of mouth breathing was also assessed. Then gingival, plaque, and oral hygiene indices were determined and recorded for each student. The prevalence of gingivitis was 73% among the children. With increasing the age from 6 to 11, the severity of gingivitis was increased. In all age groups, level of oral hygiene was superior in girls. Poor oral hygiene, mouth breathing, lower family income, and lower level of mother's education had negative effects on gingival health. The high prevalence of gingivitis observed in this research showed that comprehensive educational, preventive, and therapeutic oral hygiene programmes are needed to be planned from early school years

[Comparison of abrasiveness of different powders used in prophy-jet]

Prophy-jet is a device which is used for removal of extrinsic stains and cleaning of implant surfaces. However, some reports showed that sodium bicarbonate used in prophyjet has abrasive effects. The aim of this research was to compare the abrasive effects of 3 different powders namely, Air flow [standard sodium-bicarbonate], Soda [not purified sodium bicarbonate- which is cheap and is used for polishing porcelain crowns] and [Jet fresh] aluminum trihydroxide.Sixty extracted teeth were divided in 3 equal groups. In first, second and third group, Air flow, Soda and Jet fresh were used as powder in prophy jet. Then slurry of prophyjet [EMS-piezone] was sprayed from 2 millimeters on each tooth surface for 60 seconds. Defects formed on tooth surfaces were measured under electron microscope.Soda was less abrasive than standard Air flow and Jet fresh. Average cavity depths were 0.25, 1.33 and 1.75mm accordingly. Powders used in prophyjet could have abrasive effects. Soda may be safer to be used in prophyjet. However, due to its crystal sizes, it often causes blockage of prophyjet tubes