J Korean Acad Prosthodont.  2018 Jan;56(1):17-24. 10.4047/jkap.2018.56.1.17.

Comparison of internal adaptation of removable partial denture metal frameworks made by lost wax technique and printing technique of pattern using CAD

• Choi W
• Woo YH
• Kim HS
• Paek J

• KMID: 2402983
• DOI: http://doi.org/10.4047/jkap.2018.56.1.17

Abstract

Lost wax technique of casting wax patterns has been used principally to make metal frameworks of removable partial dentures. Since the development of digital technology and CAD, metal frameworks can be built through digital surveying and framework designing. Many cases proved that resin patterns made by CAD printing method were well adapted to internal oral structure and final metal frameworks also showed good internal adaptation as well. The metal frameworks of a removable partial denture were made by both lost wax technique and CAD technique and were applied to a patient with severe alveolar bone loss. Using CAD data and fit checker, internal adaptation of both metal frameworks were evaluated by comparing the gap between surveyed crown and its structure. This study is to prove that metal frameworks by both techniques showed adaptation that can be applied in clinical field.

Keyword

Removable partial denture; Metal framework; Lost wax technique; Computer aided design

MeSH Terms

Alveolar Bone Loss
Computer-Aided Design
Crowns
Denture, Partial, Removable*
Humans
Methods

Figure

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  Fig. 1 Pre-operative intraoral view showing diastema and supra eruption. (A) Occlusal view of maxilla, (B) Lateral view (right side), (C) Frontal view, (D) Lateral view (left side), (E) Occlusal view of mandible.

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  Fig. 2 Pre-operative panoramic view.

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  Fig. 3 Removable partial denture framework designed by CAD. (A) Scan data opening, (B) Undercut check, (C) Block out, (D) Mesh coverage setting, (E) Shape adjustment of major connector, (F) Clasp design, (G) Finish line setting, (H) Final framework design.

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  Fig. 4 Resin pattern of RPD framework. (A) Resin pattern of maxillary RPD framework was fabricated through rapid prototyping, (B) Metal framework fitted the model well, (C) Resin pattern of mandibular RPD framework was fabricated through rapid prototyping, (D) Metal framework fitted the model well.

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  Fig. 5 Discrepancy measurement between rest and rest seat. (A) Section line of #13, #23 cingulum rest of maxilla, (B) Section line of #32, 43 cingulum rest and #46 occlusal rest of mandible.

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  Fig. 6 (A) Occlusal rest; 1 measurement for center of rest (thick arrow), 2 for peripheries of rest (thin arrow), (B) Cingulum rest; 1 measurement for center (thick arrow), 2 for peripheries (thin arrow).

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  Fig. 7 Measurement of gap between model and framework. (A) Overlapping the cast and the scan data of framework by using exocad Dental CAD, (B) Measuring the distance between framework and surveyed crown by slicing scan data of #46 occlusal rest, (C) Partial denture, including internal registration material, removed with alginate impression material, (D) Section line of replica, (E) Measuring the thickness of fit checker by magnifying cingulum rest.

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  Fig. 8 Mean internal discrepancy under 2 types of rests according to measure position.

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  Fig. 9 Definitive prostheses. (A) Maxillary occlusal view, (B) Lateral view (right), (C) Frontal view, (D) Lateral view (left), (E) Mandibular occlusal view.

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  Fig. 10 Panoramic radiographs at 1 month after delivery.

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