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Post-and-core assemblies made with an accelerated pattern elimination technique
1College of Dentistry, Ohio State University, Columbus.
Summary
Accelerated pattern elimination significantly alters casting dimensions compared to conventional methods. Phosphate investments require specific setting times for optimal results in dental casting procedures.
Area of Science:
- Materials Science
- Dental Technology
- Manufacturing Processes
Background:
- Accelerated pattern elimination offers potential productivity gains in dental casting.
- Phosphate-bonded investments are commonly used in dental laboratories.
- Evaluating new techniques is crucial for improving efficiency and accuracy.
Purpose of the Study:
- To evaluate the accelerated pattern elimination technique.
- To assess its performance with three common phosphate-bonded investments.
- To compare dimensional accuracy with conventional casting techniques.
Main Methods:
- Determined exothermic setting times for investments using thermocouples.
- Measured dimensional reproduction of standardized patterns and castings.
- Compared accelerated technique (specific setting time + 15 min furnace) with conventional (1-hour bench time + furnace ramp).
Main Results:
- Significant differences in exothermic setting times were observed across investments (P < .01).
- Accelerated technique resulted in dimensional increases from 0.11% to 4.80%.
- Conventional technique showed dimensional changes from -0.04% to 3.65%, with significant differences compared to the accelerated method (P < .01).
Conclusions:
- Phosphate investments necessitate specific recommended setting times before furnace introduction.
- Carbon-containing investments exhibited the least dimensional change with both techniques.
- The accelerated technique significantly impacts casting dimensions, requiring careful consideration of investment material and setting parameters.