ABSTRACT
Objective:To investigate the three-dimensional accuracy of four impression materials for fixed denture:silicone(OX),hydrocolloid(HT) and two kinds of alginate impression(FC and ZS).Methods:Ten plaster replication models for each impression materials were made on the same metal master cast respectively, vertical and horizontal dimensions between landmarks on the masters and plaster casts were measured with an optical microscope. ANOVA was used to compare the measurements among the materials.Results:The difference between the masters and casts in horizontal distances measured on ZS produced models was bigger than that on other impression material produced ones (P<0.01) and beyond clinical requirment.The difference between the masters and casts in all measured dimensions on OX produced models was the smallest.Conclusion:Alginate paste is not accurate enough for denture model,while silicone is.The hydrocolloid material is relatively accurate.
ABSTRACT
Objective: To develop a computer-aided three-dimensional design software and laser scanning technique for the restoration of unilateral orbital defect. Method: By laser scanning apparatus plaster face model and the acquired primitive face point data were scanned; with the three-dimensional design software the point data were reconstructed to one smooth face surface image and the data of the defect of the orbital tissue were obtained from the normal contralateral tissue data by software. Results: The face-model data obtained by laser scanning apparatus was distinct and precise; the Digisurf retrograde engineer software succeeded to fulfill the computer-aided design for restoration of unilateral orbital defect. Conclusion: The laser scanning technique and three-dimensional design software can be used in the computer-aided design of the unilateral orbital defect restoration.