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Comparison of accuracy between compression- and injection-molded complete dentures
S S Nogueira1, R E Ogle, E L Davis
1School of Dental Medicine, State University of New York at Buffalo, Buffalo, NY, USA. nogueira@foar.unesp.br
The Journal of Prosthetic Dentistry
|September 9, 1999
Summary
The new injection molding technique for dentures significantly reduces incisal pin opening compared to traditional compression molding. This method offers improved accuracy in denture fabrication with no significant difference in laboratory working time.
Area of Science:
- Dental prosthetics
- Materials science in dentistry
- Biomaterials engineering
Background:
- Compression molding of complete dentures can lead to clinically significant incisal pin opening.
- This defect necessitates time-consuming occlusal adjustments, potentially damaging artificial tooth anatomy.
- A novel injection molding process aims to minimize post-processing adjustments.
Purpose of the Study:
- To compare incisal pin opening between injection and compression molding techniques.
- To evaluate dimensional accuracy of dentures fabricated by both methods.
- To assess laboratory working time for each technique.
Main Methods:
- Two groups of six maxillary and six mandibular dentures were fabricated using Lucitone 199.
- Group 1: Conventional compression molding with a long cure cycle.
- Group 2: New injection molding with a long cure cycle. Measurements included incisal pin opening, 3D dimensional accuracy via coordinate measuring machine, and laboratory time.
Main Results:
- A statistically significant difference in incisal pin opening was observed between the groups.
- No significant differences in horizontal dimensional changes were found.
- Significant differences were noted in vertical dimensional changes, favoring the injection method. Laboratory working time was comparable for both techniques.
Conclusions:
- The injection molding technique resulted in significantly less incisal pin opening than compression molding.
- Injection molding demonstrated superior accuracy for processing polymethyl methacrylate dentures.
- Both injection and compression molding techniques exhibited comparable laboratory working times.