Comparative evaluation of tooth enamel abrasion induced by different toothpastes

Tooth brushing along with a toothpaste is the most frequent and important method in managing a healthy oral hygiene. However, using such products also has its side-effects and shortcomings. Considering the large range of toothpastes available and the insufficiency of proper researches in this area in Iran, this study was designed to evaluate the abrasiveness of a toothpaste for sensitive teeth and a whitening one with two similar Iranian brands. This was an invitro experimental study. Four groups of enamel samples consisting of each 6 specimens were prepared and embedded in acrylic blocks. The initial surface profile for each specimen was calculated using a profilometer. The samples undertook the wear phase in a V8 Cross Brushing machine using toothbrushes and a toothpaste solution. The samples were then dried and the surface profile was again calculated. The variation of the first and second profilometer calculations demonstrate the amount of wear for each specimen. Data was analyzed using the SPSS program by means of One way ANOVA and Repeated Measure ANOVA tests. The amount of wear recorded for the 4 experimental groups was significantly different [p=0.039]. However, the two by two comparision tests showed that the Iranian brands did not appear to have a significant difference with their foreign counterparts [p>0.05]. The only difference was apperant between the two Iranian brand groups. According to the present study, it seems that there is no significant difference in the abrasive properties of the Iranian and foreign made toothpastes. However, similar researches considering different effects of toothpastes and especially in more clinical conditions and by utilizing different measurement methods appears to be necessary in Iran

[Evaluation of criteria for successful periodontal therapies in the posterior teeth using delphi technique in Iran]

Statement of Problem: Periodontists use different criteria to assess the success of periodontal treatments so that there is no consistent approach regarding the important parameters to be used for successful treatment

Purpose: The aim of this study was to determine success criteria of periodontal treatment using Delphi method based on the experience of expert panel of periodontists

Materials and Method: In this cross-sectional study using Delphi method, 15 periodontitists in Iran determined the level of importance of attachment level, probing depth, furcation involvement, mobility, plaque, inflammation and patient satisfaction following periodontal treatment of the posterior teeth in a patient with moderate to severe chronic periodontitis. The periodontists were questioned concerning the relative importance of each outcome measure, a minimally acceptable level for success for each criterion and the length of time for these parameters to remain stable

Results: Following two rounds of Delphi surveys, the periodontists considered the attachment level, bone loss and plaque to be a ''very important'' parameter for successful periodontal treatment. Probing depth, furcation involvement, inflammation, function, esthetics, mobility and patient satisfaction were considered to be" important" factors for successful periodontal treatment. The panelists agreed that a minimal of 1mm attachment gain, 1mm reduction in probing depth, Glickman grade I furcation involvement, Miller degree I mobility, and no change in the bone level are acceptable outcomes following 1 year of treatment. Finally, the periodontists considered that 1 year results of treatment should remain stable for a minimum of 5 years

Conclusion: These studies suggest that Delphi method is a practical approach which can establish minimal standards for successful therapy of the posterior teeth based on the opinions of expert periodontists

[ finite-element analysis of stress distribution around dental implant in different bar-attachment systems]

When implants are used to support an over denture, the optimal stress distribution is desirable to minimize the forces on the implants. The purpose of this study was to compare stress patterns generated around implant supported over denture with two different bar attachment systems ITI [Dolder] and OT with finite element method. In this descriptive study, the stress distribution around dental implants in an edentulous mandible with two different bar attachment systems [OT without spacer and ITI [Dolder] with spacerl was calculated by means of three-dimensional, finite-element model of an entire lower jaw. This model was provided with two endosseous implants in the canine region. The implants were connected to a 2 mm bar height and a vertical force was applied to the first left molar and gradually increased from 0 to 50N. Then, resultant stress distribution was evaluated. In OT and ITI [Dolder] bar attachments, the maximum von Mises stress values were observed in the cortical bone adjacent to the implant neck and this value was higher for OT bar [6.114Mpa] than ITI [Dolder] bar attachment [3.896 Mpa]. This 3-D FE study suggested that the use of ITI [Dolder] bar attachment with spacer is more advantageous than OT bar attachment for implant-supported overdenture with regard to optimizing stress distribution

Comparative evaluation of dentine surface changes following Nd:YAG laser irradiation by SEM

Dentine hypersensitivity is a common clinical problem in dental practices. So several methods such as, Nd: YAG laser have been used to treat this problem. Previous studies reported that Nd:YAG laser irradiation on root surface makes some thermal changes, like dentine melting and some other side effects which are related to power of laser irradiation. The aim of our study was to compare two different settings of Nd: YAG laser to evaluate their efficacy in occluding dentinal tubules and their side effects by means of SEM. 15 newly extracted mandibular molars were selected and the specimens with certain dimensions from buccal surface and below CEJ were prepared. Specimens were divided in 3 groups: group 1 [control], were not irradiated by laser; group 2, irradiated by Nd: YAG laser [0.5w, 10Hz, 60Sec, 2 times]; and Group 3, irradiated by Nd: YAG laser [1w, 10Hz, 60Sec, 2 times]. After preparation and gold coating of specimens, the photomicrographs were seen by SEM in magnification of 100 and 1500. Finally, the number and diameter of dental tubules, crater and microcraks were determined in each group. After that, the data was analyzed using ANOVA test. Results of this study showed that diameter of dentinal tubules were reduced in Nd: YAG irradiated groups, compared with control group. Also there were no significant differences in the mean number of open dentinal tubules between Nd: YAG [0.5 watt] and control group. On the contrary, there were significant differences between Nd: YAG [1 watt] and the other groups. Meanwhile, no group showed micro cracks or craters. The results of this study show that Nd:YAG laser irradiation can cause thermal effects such as decrease in dentinal tubules diameter or their occlusion. Also 1 watt power Nd:YAG laser is more effective than 0.5 watt power in tubules occlusion which is a necessary factor in dentine desensitization