Accuracy of ringless casting and accelerated wax-elimination technique: a comparative in vitro study.

PURPOSE: The purpose of this study was to determine whether the ringless casting and accelerated wax-elimination techniques can be combined to offer a cost-effective, clinically acceptable, and time-saving alternative for fabricating single unit castings in fixed prosthodontics. MATERIALS AND METHODS: Sixty standardized wax copings were fabricated on a type IV stone replica of a stainless steel die. The wax patterns were divided into four groups. The first group was cast using the ringless investment technique and conventional wax-elimination method; the second group was cast using the ringless investment technique and accelerated wax-elimination method; the third group was cast using the conventional metal ring investment technique and conventional wax-elimination method; the fourth group was cast using the metal ring investment technique and accelerated wax-elimination method. The vertical marginal gap was measured at four sites per specimen, using a digital optical microscope at 100× magnification. The results were analyzed using two-way ANOVA to determine statistical significance. RESULTS: The vertical marginal gaps of castings fabricated using the ringless technique (76.98 ± 7.59 µm) were significantly less (p < 0.05) than those castings fabricated using the conventional metal ring technique (138.44 ± 28.59 µm); however, the vertical marginal gaps of the conventional (102.63 ± 36.12 µm) and accelerated wax-elimination (112.79 ± 38.34 µm) castings were not statistically significant (p > 0.05). CONCLUSIONS: The ringless investment technique can produce castings with higher accuracy and can be favorably combined with the accelerated wax-elimination method as a vital alternative to the time-consuming conventional technique of casting restorations in fixed prosthodontics.

Flabby alveolar ridges: a modified technique to treat this clinical challenge.

Flabby tissues are common clinical finding which poses no problem of pain and discomfort but adversely affect the support, retention and stability of complete dentures. This paper presents a nonsurgical alternative to such cases focusing on a modified impression technique to record the flabby tissue in its undisplaced form. The custom tray was made in two parts, the first part of which contains a "lattice-work", which strengthens the tray followed by a second tray, which adequately supports the final impression. A standard neutral zone technique was additionally employed for the mandibular ridge as it was severely resorbed.

A modified technique and simplified laboratory procedure for ocular prosthesis fabrication.

PURPOSE: In many cases dentist tries to satisfy the patient with stock prosthesis that comes in standard sizes, shapes and colors. However, most of the patients complain of discomfort even after appropriate adjustment because of insufficient adaptation to underlying soft tissues. The rehabilitation of a patient with loss of eye as a result of congenital defect, pathology or accidental trauma is a challenge in terms of re-establishment of the esthetics of the patient. The purpose of this technical procedure is to provide a well fitting prosthesis to the patient, reducing the number of laboratory steps and appointments for fabrication of ocular prosthesis. METHOD: A suitable stock eye shell was modified to fit the eye socket, followed by relining with low fusing compound and making a final impression with polyvinyl siloxane impression material. The impression was poured in die stone, flasking procedure was accomplished. After dewaxing, molten wax was flown in the lower half of the flask followed by repositioning of the upper half. The flask was reopened, the stock eye shell along with the hardened wax on tissue surface was tried in the patient's eye. Finally processing was done. CONCLUSION: This technique describes an impression procedure, followed by a wax pattern try-in in the same appointment and also the detailed laboratory procedure for fabrication of the ocular prosthesis, taking into consideration positioning of iris as a result enhancing the esthetic appearance of the patient.