| Summary: | 碩士 === 國立臺灣大學 === 臨床牙醫學研究所 === 106 === Objective: The purpose of this in vitro study was to compare the denture base adaptation of conventionally manufactured (Pack & Press, injection molding), 3D printing and CAD/CAM milled techniques for fabricating complete dentures to determine which process produces the most accurate adaptation.
Materials and Methods: Two edentulous maxillary and mandibular models were fabricated by cobalt-chrome alloy. Three reference spheres (4mmx4mmx4mm) were added on the bilateral tuberosities, anterior crest at the midline at maxillary ridge and on the bilateral posterior crests, anterior crest at the midline at mandibular ridge respectively. The models were scanned by 3Shape D900 scanner (3Shape, Copenhagen, Denmark) and designed with a 2mm thickness denture base (3Shape CAD Design Software). Denture bases were fabricated by four different manufacturing techniques and materials: CAD/CAM milled (POLYWAX & YAMAHACHI), 3D printing (BV005 & NextDent), injection molding and Pack & Press. Denture base adaptation was assessed by both conventional and digital method. In conventional way, coated the internal surface of each denture base with silicone impression material and placed onto the master model under a 5 kgf axial load. Adaptation of the reference location was assessed by measuring the thickness of intervening layer of silicone impression material with the dial thickness gauge (547-400S, Mitutoyo Corp., Tokyo, Japan) between the base and the master model. In digital way, the trueness of the intaglio surface was assessed by superimposition of the test and reference scanning data.
Results: At maxilla, according to conventional method, no matter which technique was used the bilateral tuberosities showed the minimum thickness and the post dam area showed the maximum thickness. The CAD/CAM milled technique had the most accurate adaptation on the reference area. The 3D printing group showed larger gap than conventional group.
At mandible, according to conventional method, 3D printing (BV005) group showed the best adaptation, followed by CAD/CAM (POLYWAX) group. Heat cured resin method had the least adapted result among all techniques.
According to digital superimposition, the overall results showed that there was no significant difference in the trueness of the intaglio surfaces between CAD/CAM milled, injection molding and pack & press groups. 3D printing group showed the lowest trueness among all groups.
Conclusions: Within the limitation of the study, the conclusions are
The CAD/CAM milled and conventional heat cured methods were more accurate denture fabrication techniques when compared with 3D printing denture base processing technique.
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