Evaluation of marginal gap of Ni-Cr copings made with conventional and accelerated casting techniques.

CONTEXT: Conventional casting techniques following the manufacturers' recommendations are time consuming. Accelerated casting techniques have been reported, but their accuracy with base metal alloys has not been adequately studied. AIM: We measured the vertical marginal gap of nickel-chromium copings made by conventional and accelerated casting techniques and determined the clinical acceptability of the cast copings in this study. SETTINGS AND DESIGN: Experimental design, in vitro study, lab settings. MATERIALS AND METHODS: Ten copings each were cast by conventional and accelerated casting techniques. All copings were identical, only their mold preparation schedules differed. Microscopic measurements were recorded at ×80 magnification on the perpendicular to the axial wall at four predetermined sites. The marginal gap values were evaluated by paired t test. RESULTS: The mean marginal gap by conventional technique (34.02 µm) is approximately 10 µm lesser than that of accelerated casting technique (44.62 µm). As the P value is less than 0.0001, there is highly significant difference between the two techniques with regard to vertical marginal gap. CONCLUSION: The accelerated casting technique is time saving and the marginal gap measured was within the clinically acceptable limits and could be an alternative to time-consuming conventional techniques.

Flexible resins in the rehabilitation of maxillectomy patient.

Surgical resection is an established and common method for treatment of maxillofacial tumors. Such intervening surgery in this region may involve the destruction of antral, nasal, or orbital contents and jaws. Normally, the end result is a defect which may affect speech, swallowing, mastication and facial appearance. Prosthodontic restoration of functions and facial form is an excellent method in the replacement of missing parts and restoration of contour. Pertinent research in materials, designs and methods have resulted in whole array of possible prosthess that can be provided to meet specific patient needs. This case report describes the fabrication of definitive obturator prosthesis made of flexible acrylic resin on a chrome cobalt base.

Condylar guidance: correlation between protrusive interocclusal record and panoramic radiographic image: a pilot study.

PURPOSE: The purpose of this study was to compare the sagittal condylar angles set in the Hanau articulator by use of a method of obtaining an intraoral protrusive record to those angles found using a panoramic radiographic image. MATERIALS AND METHODS: Ten patients, free of signs and symptoms of temporomandibular disorder and with intact dentition were selected. The dental stone casts of the subjects were mounted on a Hanau articulator with a springbow and poly(vinyl siloxane) interocclusal records. For all patients, the protrusive records were obtained when the mandible moved forward by approximately 6 mm. All procedures for recording, mounting, and setting were done in the same session. The condylar guidance angles obtained were tabulated. A panoramic radiographic image of each patient was made with the Frankfurt horizontal plane parallel to the floor of the mouth. Tracings of the radiographic images were made. The horizontal reference line was marked by joining the orbitale and porion. The most superior and most inferior points of the curvatures were identified. These two lines were connected by a straight line representing the mean curvature line. Angles made by the intersection of the mean curvature line and the horizontal reference line were measured. The results were subjected to statistical analysis with a significance level of p < 0.05. RESULTS: The radiographic values were on average 4° greater than the values obtained by protrusive interocclusal record method. The mean condylar guidance angle between the right and left side by both the methods was not statistically significant. The comparison of mean condylar guidance angles between the right side of the protrusive record method and the right side of the panoramic radiographic method and the left side of the protrusive record method and the left side of the panoramic radiographic method (p= 0.071 and p= 0.057, respectively) were not statistically significant. CONCLUSION: Within the limitations of this study, it was concluded that the protrusive condylar guidance angles obtained by panoramic radiograph may be used in programming semi-adjustable articulators.