Simplifying Screw-Retained Implant Temporary Crown Fabrication
Implant immediate temporization has become commonplace in dental practice, and it requires a provisional that will be not only esthetic but also durable for an extended time during healing. The temporary can be fabricated either intraorally at the surgical appointment or extraorally for insertion the following day.
Prior to implant placement, a model is fabricated with the teeth to be replaced waxed onto the model in the edentulous space. When an intact tooth is to be extracted for implant placement, the model typically does not require modification. A vacuform stent is made on the study model to act as a mold for the provisional.
Titanium temporary abutments are either affixed to the implants intraorally or to a cast made from an implant impression. These are reduced to the proper height to allow adequate clearance. The previously fabricated vacuform stent is tried in over the abutments and modified as needed to allow the stent to fully seat on the adjacent teeth. A hole is made through the stent to allow access to the retention screw within the abutment. The abutments are removed either intraorally or from the cast and coated up to their collar with a self-adhesive resin, such as Centrix Dental’s AbsoLute™ (Figure 1). Providing a retentive surface to the metal for the provisional material decreases the possibility that the provisional material will separate from the titanium cylinder. The temporary abutments are either reinserted intraorally or on the cast. Centrix Dental’s Tempit® L/C, a light-activated temporary material for inlays and onlays, is placed into the access of the abutments to prevent resin from blocking the screw and making abutment removal difficult during fabrication.
The vacuform stent is filled with Centrix Access Crown Ultra®, a dual-cure provisional resin material (Figure 2); this is where the temporary crowns will be positioned, and the stent is inserted over the abutments either intraorally or on the cast. The provisional resin is allowed to fully set before the vacuform stent is removed, leaving the provisionals in place. The Access Crown Ultra resin is then removed to expose the Tempit L/C that fills the screw-access holes, and an endodontic handfile is threaded into the material and then removed to expose the retention screw. Screws are removed, allowing removal of the provisional.
The provisional resin does not flow subgingivally at this stage of fabrication and will be deficient, requiring building out to establish an emergence profile mimicking the natural dentition desired. If the provisional is being fabricated intraorally it will need to be dried to allow material to bond to the resin present. Centrix Dental’s VersaFlo®, a flowable composite resin matching the shade of the Access Crown Ultra resin, is incrementally applied to the deficient area, creating an emergence profile (Figure 3). Bulk contouring is then performed using lab carbides, and diamond disks are used to contour the provisional. The provisional should be out of occlusion during all movements, therefore reduction of this surface may be required. Additionally, there should be no contact with the adjacent teeth, and the clinician should be able to pull a mylar strip through interproximally to ensure that, during function, the natural teeth are not loading the implants. The provisional is polished with Centrix Min-Identoflex™ cups and points progressing from medium (yellow) to fine (gray), and finishing with extra-fine (white). A polishing agent is incorporated into the cups and points to achieve a glass-like finish over the entire provisional’s surface.
The screw-retained implant provisional is tried in the mouth, and retention screws are tightened to finger tightness. Occlusion is checked and any contacts are removed. Proximals are verified by allowing a mylar strip to slide through without binding. Any necessary adjustments are made, and those surfaces that have been adjusted are repolished extraorally. When the provisionals have been satisfactorily completed, a torque wrench is utilized to tighten the retention screw to the manufacturer’s specified Ncm. Tempit L/C is then placed into the access hole and covered with a thin layer of VersaFlo to complete the implant provisionals. Figure 4 shows completed screw-retained provisional crowns on the maxillary central incisors.
— Gregori M. Kurtzman, DDS, MAGD, DICOI, is in private general practice in Silver Spring, Maryland and is a former Assistant Clinical Professor at the University of Maryland, Department of Endodontics, Prosthetics and Operative Dentistry.
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