A Case of Fitting a Zirconia Crown on the Inner Surface of the Metal Frame of a Denture
- 1. School of Dentistry, Showa University, Tokyo, Japan
Abstract
Implant treatment is also a highly effective treatment for tooth defects, but the number of patients receiving prosthesis treatment with plate dentures has not decreased due to existing bone mass, systemic diseases, and financial problems. While the risk of troubles with teeth adjacent to the denture increases when a patient wears a plate denture, methods for dealing with the trouble of the denture abutment becomes important since the lifespan of patients is extended due to super-aging, the period of time required to wear dentures is extended and the possibility of worsening oral cleaning due to the need for nursing care increases. In addition, the patient is not always able to adapt to a new denture that is manufactured. This report provides an overview of a full zirconia crown that was fitted on the inner surface of the metal frame of a denture, which we manufactured by using CAD/CAM instead of manufacturing a new plate denture for a patient who needed the dental crown to be repaired after developing caries in the abutment tooth for the denture.
Keywords
• CAD/CAM
• Zirconia crown
• Removable partial denture
INTRODUCTION
Japanese society is suffering extreme population aging, and its rate of aging, which was estimated to be 28.4% in 2019 [1], is expected to continue to rise. According to the Survey of Dental Diseases in 2016, only 50.2% of Japanese people still have 20 or more teeth at age 80 [2]. Implant treatment is also a highly effective treatment for tooth defects, but the number of patients receiving prosthesis treatment with plate dentures has not decreased due to existing bone mass, systemic diseases, and financial problems [3]. While the risk of troubles with teeth adjacent to the denture increases when a patient wears a plate denture [4], methods for dealing with the trouble of the denture abutment becomes important since the lifespan of patients is extended due to super-aging, the period of time required to wear dentures is extended and the possibility of worsening oral cleaning due to the need for nursing care increases. In addition, the patient is not always able to adapt to a new denture that is manufactured. This report provides an overview of a full zirconia crown that was fitted on the inner surface of the metal frame of a denture, which we manufactured by using CAD/CAM instead of manufacturing a new plate denture for a patient who needed the dental crown to be repaired after developing caries in the abutment tooth for the denture.
Citation
Isobe A, Sato Y, Kuwazawa M (2020) A Case of Fitting a Zirconia Crown on the Inner Surface of the Metal Frame of a Denture. JSM Dent 8(3): 1134.
CASE PRESENTATION
A 79-year-old man visited our clinic in October 2019 with the main complaint of a piece of food pushed inside the mandibular right molar part and pain. His medical history revealed that he had gastric cancer, hepatitis B, spinal canal stenosis, diabetes, and high blood pressure. He had regular follow-up appointments with his physician and prescribed Bisoprolol Fumarate tablet, Lixiana tablet, Nesina tablet, Feburic tablet, Loxoprofen Sodium tablet. Observation of the oral cavity revealed that the buccal side of the ceramic crown on tooth 45 had become damaged, and that it was also carious. Since communication with dental pulp was observed when the caries was pursued under infiltration anesthesia in November 2019, we implemented pulp extirpation, followed by root canal filling in December (Figure 1). At that time, we offered three possible future treatment methods to the patient: 1) Fitting of a full zirconia crown on the mandibular right first premolar tooth and re-manufacture of the mandibular partial denture, 2) Manufacture of a metal crown fitted to the mandibular partial denture, and 3) Manufacture of a full zirconia crown fitted to the mandibular partial denture, and explained the advantages, disadvantages and expense of each method. The patient eventually chose the third option. After conducting tooth surface treatment (E-Lize, Pentron Japan, Tokyo, Japan) in January 2020, we constructed the abutment using Fiber Post (FibreKor, Pentron Japan, Tokyo, Japan) and a construction resin (Build-It FR, Pentron Japan, Tokyo, Japan), and formed the abutment tooth. We took the impression using an addition curing silicone impression material (Imprint 4, 3M ESPE, Minnesota, USA) on the mandibular right first premolar tooth on a later day. After manufacturing the plaster cast, we manufactured the resin cap using Pattern Resin (PATTERN RESIN XF, GC, Tokyo, Japan). We fitted the resin cap onto the abutment tooth, and built up the Pattern Resin so that it fitted the metal frame of the denture (Figure 2). We corrected the pattern form at the tip on the model (Figure 3), and read the forms of the abutment tooth and pattern on the model using a scanner for dental purposes (3Shape SCANNER CAD D900, Copenhagen, Denmark) (Figure 4). By confirming the form on the computer and shaping the zirconia block (KATANA Zirconia STML, Kuraray Noritake dental, Tokyo, Japan) with a milling machine (CORiTEC 250i touch, imes-icore GmbH, Land Hessen, Germany), we conducted sintering with an exclusive furnace (Zyrcomat 6000 MS, Vita Zahnfabrik, BadenWürttemberg, Germany). We conducted trial insertion of the completed zirconia crown in the oral cavity, and cemented it with a resin cement (RelyXTM Unicem 2, 3M ESPE, Minnesota, USA) after occlusal adjustment and polishing, as it fitted well with the abutment tooth and the metal frame (Figure 5).
DISCUSSION
In this case, a zirconia crown was manufactured by laying a pattern resin on a resin cap that had been manufactured in advance on the inner surface of a denture with a metal frame, and reading the pattern by CAD/CAM on the side of the technician.
While the method of manufacturing a crown that is fitted to the inner surface of a denture metal frame by using Pattern Resin has been reported previously [5], metal crowns had been used as the pattern that needed to be cast. It was possible to manufacture a crown with full zirconia, which is more esthetic and sanitary than metal, by using digital techniques as we did in the method we adopted. Furthermore, the method of taking an optical impression directly within the oral cavity after forming the abutment tooth [6], which has been reported previously, has potential disadvantages such as the need for very expensive equipment at the side of the chair, need to replace entirely including the clasp, difficulty in taking an impression under the gingival margin, and tendency for errors to occur due to insufficient moisture-proofing. However, if the patient can visit the clinic, an intraoral scanner is present on the chair side, and a provisional crown adapted to the inner surface of the denture is attached with the abutment on the gingival margin, the abutment An intraoral scan with the teeth and provisionally attached may be able to produce a zirconia crown similar to this method. As the scenes of care outside dental clinics for patients receiving visiting dental care and so forth are expected to increase in the future with the extreme aging of the population, we consider that this indirect method may be useful.