Evaluation of solubility of modelling plastic in contiguity of ethanol and plasticizer

In patients with complete denture, some clinicians have used modelling plastic impression compound [MPIC] along tissue conditioner [TC] materials simultaneously. Little information is available on the composition of these materials and the interaction between them. The purpose of this study was to evaluate the influence of two components of MPIC on the structure and chemical composition of TC. In this experimental study, MPIC specimens were provided in 25x2 mm discs. Specimens were randomly divided into three groups and were immersed in ethanol 70%, plasticizer [dibutyl phthalate] and a mixture of them [ethanol 70% and dibutyl phthalate]. All of the discs were weighed with a digital balance before and 2, 4, 6 and 24 hours after immersion. Values were analyzed by non parametric Kruskal-Wallis [alpha= 0.05] and SPSS 16 for Windows [SPSS Inc., Chicago, IL] was used for statistical analysis. Statistical analysis indicated significant differences among all groups [p>.05]. Dibutyl phthalate [DBP] had high impact on the solubility of MP, while the mixture of dibutyl phthalate [DBP] and ethanol demonstrated the highest impact

[Discrepancy measurements of copings prepared by three casting methods and two different alloys, on ITI implants]

An important criterion of success assessment of implant-supported prostheses is marginal fit. Vertical and horizontal discrepancy can result in loosing of the prosthetic screw, crestal bone resorption, peri-implantitis and loss of osseointegration. Despite careful attention to waxing, investing, and casting, marginal discrepancies are inevitable. The aim of this study was to evaluate the marginal gap and overhang in three casting methods with two different alloys in ITI implants. In this experimental in vitro study 48 analog abutments were randomly divided into six groups as follows: 1] burn out cap + BegoStar, 2] impression cap+ BegoStar, 3] conventional wax up + BegoStar, 4] burn out cap + Vearbpond2, 5] impression cap + Verabpond2, 6] conventional wax up+ Verabond2. Waxing was done in 0.7 mm thickness verified by a digital gauge and a putty index was made for all groups. Reamer was used for correction of the finish line after casting in all groups. Castings were seated on analog abutments and embedded in acrylic resin. Specimens were sectioned by isomet instrument and polished and cleaned by ultrasonic cleaner for 10 min. The marginal gap and overextended margins of castings were examined under a Scanning Electron Microscope [SEM] [X200]. The mean gap and margin overextension were calculated for each group. Data were analyzed by multivariate analysis and Bonferroni post-hoc test with p<0.05 as the level of significance. No significant difference in gap size was observed among the three casting methods with two alloys [P=0.56]. The marginal gap was not different in the studied casting methods [P=0.092]. Gold alloy crowns showed lower marginal gaps compared to base metal alloy crown [P<0.001]. No significant difference in overhang size was observed among casting methods with two alloys [P=0.093]. Base metal alloy crowns showed less overhang compared to gold alloy crowns [P<0.001]. There was a significant correlation between overhang and use of impression cap in base metal alloys [P<0.001]. Based on the results of this study, vertical discrepancy of frameworks made with gold alloy were less than those made with base metal alloy. Base metal alloy demonstrated less overhang. Conventional wax up or using burn out caps reduced less horizontal discrepancy

Effects of alfalfa on lipoproteins and fatty streak formation in hypercholesterolemic rabbits

Alfalfa [Medicago sativa] is a leguminous plant with high contents of phytoestrogen and saponin which are both useful in preventing cardiovascular disorders. This study was designed to evaluate the preventive effect of dietary alfalfa on the development and the progression of atherosclerosis in hyperlipidemic rabbits. Twenty male rabbits were obtained and kept under standard conditions. After 2 weeks of accommodation to the new place, the animals were semi-randomly distributed into four groups of five each. Animals in Group 1 received basic diet and the ones in Group 2 received the same diet to which 1% cholesterol was added. Groups 3 and 4 received similar diets as Groups 1 and 2 respectively, but supplemented with alfalfa. Each of the four groups was fed with its respected diet for a period of 12 weeks. Fasting blood samples were collected from all animals at the beginning and at the end of the study and blood factors were measured. At the end of the study samples from the right and the left coronary arteries as well as the aorta were collected from all animals for pathological evaluations. Though dietary alfalfa decreased total cholesterol, LDL and triglyceride and this effect was not significant, but dietary alfalfa significantly increased HDL. The formation of fatty streaks in the aorta, the right and the left coronary arteries were significantly reduced under the influence of dietary alfalfa. The indication that dietary alfalfa may have preventive effects on the progression of fatty streak formation calls for more studies to clarify the mechanisms of the effect

[Photography in dentistry: part IV [object + photography]]

Object photography in dentistry including dental instruments, models, teeth and gross specimens has some special features and needs special consideration. These objects are usually very small, highly usually reflective and often with very bright surfaces. They need special lighting and other accessories for acceptable results. On the other hand, in laboratories and dental clinics we haven't enough time for taking photographs. The purpose of this article is to introduce the principles of object photography in dentistry

Photography in dentistry: Part II [Intraoral photography]

In addition to the camera, other accessories such as retractors and mirrors are necessary for intraoral photography. They enable directly inaccessible subjects, to be viewed and photographed easily. Gaining adequate view, by suitable retractors and mirrors, is the most important step, requiring skill and patient cooperation to achieve successful results. Composition, visualization of the final photograph and a carefully controlled clinical technique must be practiced in order to produce rapid, precise and reproducible clinical photographs. There are many procedures to be followed and precautions to be taken in order to obtain good quality, reproducible dental photographs. Failures can be avoided by following a distinct procedure. This article focuses on clinical equipments such as retractors, mirrors and intraoral photography

Photography in dentistry: Part III [Dental portraits]

Dental portraits are predominantly used for orthodontics, orthognathic surgery and prosthetic dentistry. If these images are to be used for documentation, then the patient must be positioned in accordance with strict guidelines for further references. If the images are to be used to present an aesthetic impression of dental treatment there is more flexibility in positioning the patient. Dental photography is used to make pictures of teeth and surrounding tissues, radiographs, casts and other objects. In this section, standard principles for portrait pictures are explained

Comparing the effect of two different hormonal therapy regimens on the activity coagulation factors VII, VIII, IX and serum lipids in menopausal women

During extrinsic coagulation pathway, a complex is developed between factor VII, calcium and tissue factor [a cell membrane lipoprotein that is exposed after cell injury]. Factor VII needs calcium and vitamin K for its biologic activation. Coronary artery disease [CAD] can be induced by increased level and activity of the coagulation factors VII, VIII and IX. In postmenopausal women, estrogen decreases blood lipids and thereby decreases risk of CAD. However, the exact effects of the estrogen on the other predisposing factors of CAD are unknown. This study was conducted to evaluate the effects of oral hormone therapy regimen on fibrinogen and other coagulation factors. Sixty menopausal women with history of hysterectomy were randomly allocated in 2 groups. One group was treated with conjugated estrogen 0.625 mg/day and the other group was treated with conjugated estrogen 0.625 mg/day and medroxyprogesterone 2.5 mg/day. Serum fibrinogen level and activity of coagulation factors VII, VIII and IX and blood lipids level were checked before and 3 months after treatment. In the group treated with estrogen alone, mean factor VII activity showed significant increase 3 months after treatment as compared to before hormone therapy [P<0.05]. There were no significant changes in mean activities of coagulation factors VIII, IX and serum fibrinogen level in patients treated with estrogen or estrogen/medroxyprogesterone after treatment [P>0.05]. In both groups, hormone therapy significantly decreased serum cholesterol level and LDL-C and increased HDL-C [P>0.00], but serum triglyceride level increased in the group only treated with estrogen. Significant increase of coagulation factor VII and serum triglyceride in estrogen-treated patients is logical. This study confirms that hormone therapy with this protocol does not change mean serum fibrinogen levels and activity of coagulation factor VIII and IX. This may be a genuine finding or may be due to inadequacy of samples, given the wide normal range of coagulation factors and serum fibrinogen. Studies with more prolonged follow-up or more samples are warranted