Carlos A. Jurado, DDS, MS/Akimasa Tsujimoto, DDS, PhD/Kenko Tanaka, DDS, PhD/Hidehiko Watanabe, DDS, MS/Nicholas G. Fischer, BS/Wayne W. Barkmeier, DDS, MS/Toshiki Takamizawa, DDS, PhD/Mark A. Latta, DDS, MS/Masashi Miyazaki, DDS, PhD
Digital dentistry has been evolving rapidly over the last 30 years with restorative techniques in the forefront of the field.1 Novel technologies have been used in both the clinic and laboratory.2 The goals of these new technologies and methods are to manufacture restorations quickly, easily, and more accurately.3 In addition, patients are more attracted to the digital workflow than to the conventional techniques.4 Digital workflows have been described with several different approaches, from a combination of conventional and novel techniques to fully digital techniques.5 Simple subtractive techniques were introduced with the first commercial computer-aided design/computer-assisted manufacture (CAD/CAM) system designed by Dr Marco Brandestini in 1985.6 This was followed by several other commercial systems, and then more complex approaches, such as milling of provisional restorations and dentures, that were introduced in the early 1990s.6 Current reports have shown better marginal adaptation in digitally fabricated final restorations than in those made by conventional techniques.7,8 Recently, additive techniques have been applied in restorative dentistry to provide more restorative options for the clinician.9 The accuracy of printing techniques allows the clinician to expand the application of CAD to initial diagnostic models, surgical guides, complete removable dentures, and provisional restorations.10 Printed techniques for fixed prostheses may become very common. The use of a three-dimensional (3D) printed coping to check the marginal adaptation of the final restoration is a good option due to reproducibility, quick treatment, and low cost. 3D printing techniques for printed diagnostic models for orthodontic treatments have been widely described.11 However, there have been no reports of 3D printed copings for intraoral try-in before milling of final restorations. The aim of this case report is to exemplify advantages of printed wax-ups for intraoral try-in before milling of a final restoration.
Clinical report
A 61-year-old man presented with the chief complaint of dissatisfaction with his smile. After a detailed evaluation, the findings were missing posterior teeth, worn dentition, secondary caries, periodontal disease, and defective restorations (Fig 1). The patient received an explanation of his dental needs and was offered several treatment options. Although implant therapy to restore the edentulous areas was offered, due to financial constraints and the treatment term, removable dental prostheses were chosen to remedy his partial edentulism, with fixed prostheses in the maxillary anterior area. Traditional techniques including a facebow record and polyvinyl siloxane impressions (Aquasil Ultra, Dentsply Sirona) were used for a diagnostic mounting. A conventional diagnostic wax-up was performed to achieve the desired function and esthetics. A silicone putty matrix was made using the diagnostic wax-up for the mandibular teeth. The matrix was placed on the mandibular teeth and this segment was restored with a composite resin (Filtek Supreme Ultra, 3M Oral Care). The intraoral condition was digitally acquired using a scanner (D900L, 3Shape) and a STL file of the overall design was created with patient consent. The digital file (DCM, 3Shape) was modified to create a uniform preparation with a minimal cutback. Subsequently, conventional final impressions were made with polyvinyl siloxane (Aquasil Ultra) and master casts were made (Resin Rock, Whip Mix) and mounted, and dies were trimmed. The master casts were then digitally scanned. Final restorations were designed according to the desired contours. A wax-up was printed (Form 2 SLA, Formlabs) (Fig 2) and physical margin adaptation was checked in the master cast (Fig 3). A conventional surveyor was used to evaluate the contours (Fig 4). The printed coping was then placed in the mouth in order to evaluate the fit and contours (Fig 5). By requesting the patient to lightly close his mouth, occlusal evaluation was conducted (Fig 6). No modifications were needed and the final restorations were milled out of monolithic zirconia with a milling machine (DWX-51D, Roland DGA). Intraoral comparison of the printed coping and milled final ceramic restorations was completed (Fig 7). All final restorations were tried in and the patient approved prior to cementation (RelyX Luting Plus Cement, 3M Oral Care) (Fig 8).
Discussion
Advanced technology in dentistry can improve conventional techniques for clinicians, and additive techniques are one of the most novel approaches in restorative treatments.12 Dental 3D printing is a cornerstone of modern dentistry, because it provides endless new opportunities ranging from initial diagnosis to final restorations.13 Additive manufacturing in restorative dentistry allows the clinician to print diagnostic models, diagnostic wax-ups, provisional restorations, and complete and partial dentures. The present case report illustrates some of the benefits of this technique. In this case, the patient placed great importance on the esthetic qualities of the restoration, but also wanted efficient treatment and restoration placement. Financial constraints limited the treatment alternatives that could be considered. Finally, the situation of his dentition meant that the required restoration was complex. Long term provisionalization may have been ideal, but efficiency, speed, and finances impacted treatment. The complexity of the case and the need for an esthetic restoration made it essential to conduct an intraoral evalu ation of a mock-up of the restoration. Although this could also be done with a temporary restoration by provisional restorative materials, or with a handmade wax-up, neither of these approaches was suitable in this case. Long-term provisional restorations are costly, due to both fabrication time and the cost of materials, and would have exceeded the patient’s budget. In contrast, a 3D printed coping is based directly on the digital model that is used to create the final restoration, so there is no additional design cost and the printing materials are inexpensive. On the other hand, a handmade wax-up is fragile. If occlusion is checked with the restoration in place there is a risk of damaging the handmade wax-up, which limits the extent to which the esthetics can be confirmed in advance. A 3D printed coping is less fragile and can be checked in the mouth with a gentle bite to confirm occlusion. The costs of handmade wax-ups are higher than those for 3D printing and must be prepared by a skilled dental technician. Many copies of a 3D printed coping can easily be made. Considering all of these factors, 3D printing was the only technique that allowed the properties of the restoration to be confirmed before creating the final restoration without exceeding the patient’s budget. In this case, the patient and clinician agreed that there was no need to modify the first wax-up, but it is worth noting that scanning and 3D printing makes it very easy to generate new waxups if it is modified in the mouth. The availability of such options allowed both the dental practitioner and patient to embark on this course of treatment with confidence. The patient was happy with the result, which demonstrates that the use of 3D printing to create a coping allows complex cases to be treated quickly and at low cost without compromising patient satisfaction.
Conclusions
The use of 3D printed copings allows complex and esthetically important restorations to be thoroughly tested at relatively low cost without introducing large delays into the process. This ensures that such restorations are available to a wider range of patients.
Acknowledgment
The authors thank the technician Sean Park, who fabricated the restorations for this case.