The Effect of Core and Veneering Design on the Optical Properties of Polyether Ether Ketone.

This study aimed to evaluate the effect of core shade and core and veneering thickness on color parameters and translucency of polyether ether ketone (PEEK). Sixty PEEK discs (0.5 and 1 mm in thickness) with white and dentine shades were veneered with A2 shade indirect composite resin with 0.5, 1 and 1.5 mm thickness (n=5). Cores without the veneering material served as controls for translucency evaluation. Color parameters were measured by a spectroradiometer. Color difference (ΔE00) and translucency parameters (TP) were computed. Data were analyzed using one-way ANOVA and Tukey's test (for veneering thickness) and independent t-test (for core shade and thickness) via SPSS 20.0 (p⟨0.05). Regarding the veneering thickness, white cores of 0.5 mm thickness showed significant differences in all color parameters. In white cores of 1 mm thickness and dentine cores of 0.5 and 1 mm thickness, there were statistically significant differences only in L∗, a∗ and h∗. The mean TP was significantly higher in all white cores of 1 mm thickness than dentine cores of 1 mm. Considering ΔE00=3.7 as clinically unacceptable, only three groups had higher mean ΔE00 values. Core shade, core thickness, and the veneering thickness affected the color and translucency of PEEK restorations.

Effect of iron containing supplements on rats' dental caries progression.

OBJECTIVE: Iron deficiency is the most common form of malnutrition in developing countries. Iron containing supplements have been used effectively to solve this problem. In children, because of teeth staining after taking iron drops, parents have the idea that iron drops are the cause of tooth decay; therefore, they limit this vital supplement in their children's diet. Hereby, we evaluate the histologic effect of iron containing supplements on tooth caries in rice rats with cariogenic or non-cariogenic diet. MATERIALS AND METHODS: Twelve rats were selected and divided into four groups for this interventional experimental study. Four different types of dietary regimens were used for four months; group A, cariogenic diet with iron containing supplements; group B, cariogenic diet without iron containing supplements; group C, non-cariogenic diet with iron containing supplements; group D, non-cariogenic diet without iron containing supplements. After sacrificing the rats, 20-micron histological sections of their posterior teeth were prepared using the Ground Section method, then they were studied under polarized light microscopy. In order to compare the progression of caries in different samples, the depth of the lesions in the enamel was measured as three grades I, II and III. RESULTS: The mean grade value of A, B, C and D groups were 1.61, 2.61, 1.37 and 1.80, respectively. Statistical analysis revealed that significantly fewer caries were seen in the group which had received iron containing supplements and cariogenic diet compared with cariogenic diet without iron supplements (p<0.05). CONCLUSION: Ferrous sulfate reduces the progression of dental caries in the cariogenic dietary regimen.

New software: comparison between three software programs for root canal length measurement.

OBJECTIVES: The purpose of this study was to design a software program to estimate the curved root canal working length by using curved line software and comparing its accuracy with Trophy and Cygnus software programs. METHODS: 120 simulated curved canals were divided into 12 groups based on the radius and the angle of the curvature. The true canal length was measured from the orifice to the terminus. Canals were filled with urographin and were imaged by a digital radiographic system. Canal length was measured with newly developed software that uses a curved line, as well as with Cygnus and Trophy software, both of which use a sequence of straight lines, and their accuracies were compared. RESULTS: The proposed software was significantly more accurate than other software with respect to the gold standard (P < 0.001). However, the error was less than 0.5 mm in over 99% of the cases with all software with three clicks, and over 96% of the cases with six clicks in Trophy, which was not statistically significant (P = 0.99). CONCLUSIONS: The studied software programs were not significantly different and their statistically significant difference compared with the gold standard is not clinically significant. The suggested software has to be studied more regarding its capabilities in the utilization of curved lines in measuring curved canals and calibration of the measurements.

Results of dermal patch graft in the treatment of Peyronie's disease.

PURPOSE: To investigate the efficacy of "dermal patch graft" in surgical management of Peyronie's. MATERIALS AND METHODS: Eighteen of Peyronie's disease cases, with a mean age of 49 and a history of penile curvature and painful erection were enrolled in this study. Diagnosis was made clinically by plaque palpation. All of them were in the chronic stage of disease with symptom duration of at least 6 months. We also evaluate their potency through Brief Sexual Function Inventory (BSFI) questionnaire before and after the operation, meanwhile the degree of penile curvature was measured with goniometry while artificial erection status was induced. RESULTS: Mean penile curvature, before and after the operation (58 and 5 degrees respectively), showed significant improvement (p<0.001). The improvement of curvature was irrespective of the plaque size. All of our patients suffered from inability to intercourse due to significant penile curvature but after the procedure 11 of them (66.1%) could do so. Also the BSFI score improved significantly in this subgroup (p<0.05). The remaining 7 cases (39%) already suffered from erectile dysfunction despite of operation; however, the penile curvature improved significantly in them. Six of this latter group had a plaque size greater than 4 cm2 and BSFI score was not significantly improved. CONCLUSION: Dermal patch graft as a cost effective method in the management of Peyronie's disease significantly corrects the curvature irrespective of plaque size and curvature severity. We found that if the fibrous plaque is less than 4 cm2 and the patient has no severe erectile dysfunction, this procedure will significantly improve his potency; however, if the patient suffers from a plaque sized greater than 4 cm2 and/or severe erectile dysfunction, to reach satisfactory erection, implantation of penile prosthesis or applying other methods of artificial erection in addition to dermal patch graft is suggested.