The Prevalence of Temporomandibular Disorders in Patients Referred to the Prosthodontics Department of Shahid Beheshti Dental School in Fall 2010

Objective: Temporomandibular disorders (TMDs) are among the most common disorders of the maxillofacial region and are often characterized by pain and dysfunction of the temporomandibular joint(TMJ) and muscles of mastication. Due to the presence of several diagnostic criteria for such disorders, the reported prevalence rates for TMDs have been variable in different communities. The aim of this study was to determine the prevalence of TMDs in patients presenting to the Prosthodontics Department of Shahid Beheshti Dental School (SBDS) in fall 2010.Methods: In this descriptive study, 150 patients presenting to the Prosthodontics Department of SBDS (86 females and 64 males) were randomly selected and evaluated by using a questionnaire (subjectively) and clinical examinations (objectively). Presence and prevalence of various symptoms of TMDs such as clicking and tenderness on palpation in the muscles of mastication and the TMJ were evaluated in patients. Statistical comparisons were carried out using chi-square test.Results: Clicking, masticatory muscle and joint tenderness, TMDs, and limitation of mouth opening were found in 21.3%, 18.7%, 5.3%, 18.7% and 1.3% of patients, respectively. Despite the higher prevalence of TMDs in females, the difference in this regard between males and females was not statistically significant (39.3% in men versus 60.7% in women).Conclusion: Based on the obtained results, the prevalence of TMDs and its related symptoms was 18.7% in patients presenting to the Prosthodontics Department of SBDS in fall 2010. This value was lower than the rates reported in the literature

The Effect of Aging on the Accuracy of Spring-Style Mechanical Torque Limiting Devices for Dental Implants

Objective: Recently, a wide variation has been reported in delivery of the target torque by spring- style mechanical torque limiting devices (MTLDs) but the effect of aging on their accuracy has not been independently evaluated. The purpose of this study was to determine the effect of aging on the accuracy of spring-style MTLDs.Methods: In this in-vitro experimental study, 15 new spring-style MTLDs were selected of three different manufacturers. To measure their accuracy, the peak torque was measured in 10 sequences by a Tohnichi torque gauge before and after 1000 times of use. In each sequence, 10 repetitions of peak torque values were registered. The intra-class correlation coefficient (ICC) was calculated and Repeated Measures ANOVA and two-way ANOVA were applied to calculate and compare the absolute error values between the three understudy groups.Results: The absolute error value was in the range of -3.5(-3) Ncm for 3i group, -2.5 (1) Ncm for ITI and -4-+2 Ncm for Nobel Biocare group. The latter value showed a significant difference with the two former values (p<0.05). All samples in the ITI group had error values within 10% of the clinically acceptable range. About 5% of measurements (maximum of 11.4%) in Nobel Biocare and 9% of measurements (maximum of 14.53%) in the 3i group showed error values greater than the 10% range.Conclusion: Aging decreased the accuracy of spring-style MTLDs. The magnitude and trend of reduction in accuracy were variable among different groups

The Accuracy of Four Impression-making Techniques in Angulated Implants Based on Vertical Gap

Statement of the Problem: Precision of the impression taken from implant positions significantly determines accurate fit of implant-supported prostheses. An imprecise impression may produce prosthesis misfit. Purpose: This study aimed to evaluate the accuracy of four impression-making techniques for angulated implants by stereomicroscope through measuring the vertical marginal gaps between the cemented metal framework and the implant analog. Materials and Method: A definitive cast with two 15° mesially angulated implants served as the standard reference for making all the impressions and later for accuracy evaluation. Four groups of five samples were evaluated: (1) closed-tray snap-fit transfer, (2) open-tray nonsplinted impression coping, (3) metal splinted impression coping, and (4) fabricated acrylic resin transfer cap. A gold-palladium framework was fabricated over the angulated implant abutments, the fit of which was used as reference. The gaps between the metal framework and the implant analogs were measured in sample groups. Corresponding means for each technique and the definitive cast were compared by using ANOVA and post hoc tests. Results: The mean marginal gap was 38.16±0µm in definitive cast, 89±19.74µm in group 1, 78.66±20.63µm in group 2, 54.16±24.29µm in group 3, and 55.83±18.30µm in group 4. ANOVA revealed significant differences between the definitive cast and groups 1 and 2, but not with groups 3 and 4 (p< 0.05). Conclusion: Vertical gap measurements showed that metal splinted impression coping and fabricated acrylic resin transfer cap techniques produced quite more accurate impressions than closed-tray snap-fit transfer and open-tray nonsplinted impression coping techniques do. The fabricated acrylic resin transfer cap technique seems to be a reliable impression-making method

Covering the screw-access holes of implant restorations in the esthetic zone: a clinical report.

Screw-retained implant restorations have an advantage of predictable retention as well as retrievability, and obviate the risk of excessive sub-gingival cement commonly associated with cement retained implant restorations. Screw-retained restorations generally have screw access holes, which can compromise esthetics and weaken the porcelain around the holes. The purpose of this study is to describe the use of a separate overcasting crown design to cover the screw access hole of implant screw-retained prosthesis for improved esthetics

The effect of inter-implant distance on retention and resistance to dislodging forces for mandibular implant-tissue-supported overdentures.

The effect of inter-implant distance on retention and resistance of implant-tissue-supported overdentures is lacking in the literature. An in vitro study was performed to evaluate this effect for mandibular implant-tissue-supported overdentures retained by two ball attachments.An acrylic cast of an edentulous mandible was fabricated. Three pairs of implants were symmetrically placed at both sides of the midline. The inter-implant distance was 10, 25, and 35 millimeters in positions A, B and C, respectively. A framework simulating the overdenture was fabricated on the cast. Six attachment housings were placed within the overdenture. For each sample, two ball abutments were screwed onto the implant pairs and two pink nylon inserts were seated in their respective attachment housings. The samples were tested in three groups of 15 (A, B, and C). The testing machine applied tensile dislodging forces and peak loads were measured in three directions: vertical, oblique, and anterior-posterior. A one-way ANOVA followed by Tukey's HSD was used to determine groups that were significantly different. Tests were carried out at 0.05 level of significance.Peak loads for the anterior-posteriorly directed dislodging forces were significantly the highest for group C (P0.05).Inter-implant distance did not affect the vertical retention and oblique resistance of mandibular implant-tissue-supported overdentures; however, it affected anterior-posterior resistance

Electrochemical Recognition of Metalloproteins by Bromide-modified Silver Electrode- A New Method

Abstract: A bromide–modified silver electrode is reported, in the present study, to catalyze the redox reactions of metalloproteins. This study describes that the bromide ions show very good redox behavior with silver electrode. The cathodic and anodic peak potentials were related to the concentration of bromide ions involved in making bromide-modified silver electrode. The electrode reaction in the bromine solution was a diffusion-controlled process. Positive potential shift of the bromide ions was seen when different proteins were added to the solution using a silver electrode. New cathodic and anodic peaks were observed at different potential ranges for myoglobin, cytochrome c and catalase. A linearly increasing cathodic peak current of bromide ions was seen when the concentration of superoxide dismutase was increased in the test solution. However, no change for albumin was observed when its concentration was increased in the test solution. Present data proves our methodology as an easy-to-use analysis for comparing the redox potentials of different metalloproteins and differentiating the metallo- from non-metalloproteins. In this study, we introduced an interesting method for bio-electrochemical analyses