[Effects of mouthwashes on color stubitity of hleached teeth]

Background and Aim: Bleached teeth are susceptible to discoloration. The aim of this study was to evaluate discoloration of bleached teeth following short-term use of several mouthwashes.

Materials and Methods: In this In-vitro experimental study, 48 extracted maxillary central incisorswere selected and divided into four groups of 12. All the teeth were subjected to external bleaching with 38% hydrogen peroxide [H2o2]. After bleaching, the teeth were immersed in in distilled water [control group or group 1], chlorhexidine [CIx; group 2], Irsha [group 3] or Persica [group 4] for three, seven and 14 days. The color change was assessed by a spectrophotometer at each time point and reported as INCREMENT El, INCREMENT E2 and INCREMENT E3. The results were analyzed by paired t-test, repeated measures ANOVA, one-way ANOVA and LSD test.

Results: Different mouthwashes [p:0.0a3] and immersion times [p:0.03g] caused significantly variable color change in bleached teeth. After 14 days of immersion, the color change of samples in Persica group had significant differences with that of other goups [p<0.000]. The results of repeated measures ANOVA was only significant for the persica group indicating significant color change over time. Thus, paired t-test was applied for pairwise comparison of the time points, which revealed significant differences between INCREMENT EI and INCREMENT E3 and also INCREMENT E2 and INCREMENT E3 [p<0.0S].

Conclasion: Persica mouthwash would cause significant discoloration in recently bleached teeth.

[Tensile strength analysis of three different restoring techniques in canine primary teeth]

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. 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 [alpha =0.05]. 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]. The tensile bond strength was significantly higher in RMPT than the two conventional methods used for restoring severely destroyed primary anterior teeth

Assessment of balance impairments in patients with knee osteoarthritis

Knee osteoarthritis is one of the most common musculoskeletal problems, can affect on patient's daily activity and produce dependency in their daily activity and functional disability; The aim of present study is to compare static balance in patients with knee osteoarthritis and healthy subjects using force plate. Postural stability in knee OA patients and healthy subjects [each group 20 subjects] were measured by force plate. Two positions were selected double stance with closed or opened eyes. Range of fore/aft [Rfa] and Range of side ways [Rsw], were measured as static postural stability. Rsw increased significantly in the double stance position in patients group [P<0.05]. Also in both groups, Rsw and Rfa in the double stance with closed eyes were more than of open eyes position [P<0.05]. Postural control deficits and increase of center of pressure's sway were identified in participants with knee osteoarthritis. Therefore, one of the most important goals of rehabilitation is to improve balance control in knee OA patients

Affect of age on composite bond strength to dentine using 5[th] and 6[th] generation adhesive system

The mineral content of dentin increases with age and its primary structure is altered. These changes may have unknown effects on efficiency of adhesive systems. The aim of this study was to find the effect of aging on dentin bonding agents. fourty eight extracted human premolars were divided into 2 groups under 15 years old and 2 groups over 45 years old. After exposing surface dentin with wheel type burs and polishing dentin surface with paper disks, dental adhesives, Excite and Prompt L-Pop were used following manufacturer's instructions. Then composite cylinders were bonded to dentin and light cured. Then Shear Bond Strength [SBS] of samples were measured with universal testing device [Dartec]. Fractured specimens were observed under stereomicroscope to determine the type of fracture. The mean SBS for those teeth aged over 45 was 24.15 MPa using Prompt L-Pop, and 18.6 MPa using Excite, and for teeth aged under 15 years old was 21.5 MPa using Prompt L-Pop and 13.99 MPa using Excite. SBS of older teeth was shown to be more than younger teeth, also Prompt L-Pop showed higher SBS than excite. It seems that lower mineral content of dentin in younger teeth results in over demineraliza-tion while etching hence resin is unable to penetrate the collagens fibers resulting in voids in bonding area which reduces the SBS in this group. Also higher SBS of Prompt L-Pop can be explained by the water cone-tent of it, which serves as solvent while Excite has ethanol which is evaporated and reduces the penetration of resin

[Harmony of upper anterior teeth in dental students]

The study for beauty can be traced back to the earliest civilizations. Many factors influence the perception of beauty, and esthetic dentistry continues to grow as a major part of overall dentistry. One of the most important factors in beauty of the teeth is the proportion of them to one another, and golden proportion is determined to be 1.618. The purpose of this study was to determine the average dimensions of the six maxillary anterior teeth in specific population and to evaluate relationship between these dimensions. Casts and photographs were obtained from 100 students of Isfahan Dental School with normal occlusion. Measurements of length and width were made on the casts and photographs using an electronic digital caliper. Average dimensions and ratios were calculated. Dimensions in men were larger than dimensions in women but most ratios in men and women were not different. All values in left and right were approximately equal. In addition the golden proportion was not found in ratios