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Extrusion-mixing compared with hand-mixing of polyether impression materials?
Caroline McMahon1, Daniel Kinsella, Garry J P Fleming
1Materials Science Unit, Division of Oral Biosciences, Dublin Dental School & Hospital, Trinity College Dublin, Dublin 2, Republic of Ireland.
The European Journal of Prosthodontics and Restorative Dentistry
|January 27, 2011
Summary
Altering the base:catalyst ratio in polyether impression materials significantly impacts working time and strain. Extrusion-mixed materials offer comparable properties to optimal hand-mixed ones.
Area of Science:
- Dental Materials Science
- Polymer Chemistry
Background:
- Polyether impression materials are widely used in dentistry for accurate prosthodontic restorations.
- Optimizing the base:catalyst ratio is crucial for achieving desired physical properties.
- Hand-mixing techniques can be prone to inconsistencies, potentially affecting material performance.
Purpose of the Study:
- To investigate the effect of varying the base:catalyst ratio on the working time, elastic recovery, and strain in compression of hand-mixed polyether impression materials.
- To compare the properties of extrusion-mixed polyether impression materials with optimally hand-mixed materials.
Main Methods:
- Polyether impression materials were hand-mixed at the manufacturer's recommended base:catalyst ratio (7:1) and with 25% more or less catalyst.
- Specimens were also prepared using an extrusion-mixing method.
- Working time was measured using a penetrometer assembly.
- Elastic recovery and strain in compression were tested on cylindrical specimens.
Main Results:
- Increasing the catalyst by 25% significantly reduced working time.
- Decreasing the catalyst by 25% significantly increased strain in compression.
- Extrusion-mixed polyether impression materials exhibited similar working time, elastic recovery, and strain in compression compared to optimally hand-mixed materials.
Conclusions:
- Deviations from the recommended base:catalyst ratio in hand-mixed polyether impression materials significantly alter their working time and mechanical properties.
- Extrusion-mixing offers a viable alternative, providing comparable performance to optimal hand-mixing without compromising key physical characteristics.
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