Clinical application of stereolithographic crown prototypes of milled ceramic restorations
Computer-aided design and manufacturing (CAD/CAM) techniques, such as stereolithographic (SLA) rapid prototyping, have been developed to aid in multiple aspects of dentistry. These areas include: production of surgical guides for dental implants, production of physical models for prosthodontics, orthodontics and surgery, manufacturing of dental, craniomaxillofacial and orthopaedic implants, and the fabrication of copings and frameworks for implant and dental restorations. Some of the advantages of stereolithography are: a) rapid fabrication, b) ability to create complex shapes with high resolution, c) relatively inexpensive. These advantages make stereolithography an excellent option to fabricate crown prototypes for evaluation by the patient. By doing this, we allow the patient to actively participate in the evaluation/modification of the crown proposals and we can make those modifications in real time. Once the contours have been confirmed, the modified prototypes can be used to fabricate the final milled ceramic restorations. This case report presents additive manufacturing technology crown proposals to be used as an esthetic try-in in order to manage a patient with high esthetic expectations. Step-by-step techniques as well as the final result of the treatment are presented.
A 67-year-old female patient, and former dental technician, presents to our clinic needing full coverage crowns on teeth #6-#11 and #22-#27, due to moderate-severe attrition caused by a reduced horizontal overlap and bruxism. In order to achieve a result that would satisfy her expectations, a novel approach using CAD/CAM 3D printed prototype crowns was used to allow the patient to participate in the evaluation and modification of her proposed final restorations. The step-by-step technique used in this case is presented as well as the outcomes of the treatment.
1. Teeth were prepared for all-ceramic restorations, using diamond burs and a modified shoulder margin
2. Teeth were impressed using heavy and light body PVS material (Extrude) and double cord retraction technique.
3. Impressions were poured with Type IV stone (Whip-mix, Resin Rock).
4. Master casts were scanned using Straumann CARES CS2 Scanner, and the prototype restorations were designed using the Straumann CARES design software (Dental Wings DWOS).
5. The STL files of the restorations were exported and printed with the FormLabs 3D Printer with using white resin.
6. The tissues and tooth preparations were coated with a thin layer of petroleum jelly.** Crown prototypes were tried-in intraorally and were evaluated and modified by the clinician, taking into account the patient’s opinion at all times. The factors that were evaluated were: proximal contacts, teeth length and width, axial contours, and external finish.
7. The designs of the restorations were modified (using Straumann CARES CS2 with DWOS design software) by closely following the annotations made on the resin prototypes. The annotations were used to guide us in determining the proper length and line angle positions as well as anatomical features.
8. Crowns were sent to Stramann USA milling facility for milling.
9. Restorations were tried in at the precrystallization stage for proximal and occlusal adjustments. A cutback was made for porcelain layering to increase aesthetics.
10. Final restorations were tried-in and cemented with Rely X Ultimate translucent resin cement.
The approach presented using sterolithographic crown prototypes of milled ceramic restorations to perform an esthetic try-in
, is an inexpensive and practical method to treat patients with high expectations in a predictable way.