Digital workflow for predictable immediate loading in the mandible by using a shape memory dental implant abutment system: A clinical report

Abstract

Digital surgical planning for immediately loaded dental implants can be a predictable and accurate procedure, with the interim prosthesis also designed digitally. If the planning and execution are meticulous, chairside adjustments can be minimized because the outcome should be closely matched to the proposed digital plan. A novel dental implant abutment system made from a shape memory metal could be an answer to the cement versus screw controversy as it uses neither. This new system can provide patients with better esthetics and is biologically favorable.

If certain criteria are met, including primary stability and cross-arch stabilization, the results of immediate loading in the edentulous mandible can be predictable. Through careful patient selection, the immediate loading of implants can provide significant advantages for patients and clinicians in terms of increased comfort and reduced treatment time.

Recent advances in digital technology have enabled dentists to be more efficient and more accurate. The clinician is now able to render treatment from start to finish with a completely digital workflow.

One of the debates in implant dentistry has been the choice between screw-retained and cement-retained implant restorations. While screw-retained restorations are traditionally favored at many institutions, there are situations where cement-retained prostheses are indicated. Thus, the best way to restore implants remains controversial among dentists. A new dental implant abutment system, promoted as both screwless and cementless, may offer clinicians the best of both worlds. Prosthesis retention is provided by a shape memory metal sleeve (Smileloc; RODO Medical Inc) that fits over the implant abutment (RODO abutment; RODO Medical Inc) ( Fig. 1 ). In addition to being easily retrievable, this newly developed system eliminates concerns over cement-induced peri-implantitis and unesthetic occlusal screw channels. The transmission of energy for the shape transformation comes from a noncontact induction heating element (Smilekey; RODO Medical Inc).

Figure 1
Dental implant abutment system consists of coping and prosthesis, shape memory metal sleeve, and abutment.

The purpose of this clinical report was to describe the application of digital technology and a novel implant abutment system in the immediate placement and loading of a mandible. Intraoral scanning and cone beam computed tomography (CBCT) were used for virtual surgical planning; 3D printing was used to fabricate surgical guides and analog casts; and milling was used to create an interim prosthesis that is attached intraorally by means of this shape memory implant abutment system.

Clinical report

A 62-year-old white man presented with a maxillary tooth-supported overdenture opposing a complete-arch fixed dental prosthesis (FDP). Although the patient was satisfied with his maxillary overdenture, his main reason for seeking treatment was the fracture of the mandibular FDP ( Fig. 2 ). Because of compromised periodontal support, the anterior segment of the FDP was mobile and caused the patient significant discomfort. The patient wanted to address the problem as soon as possible but stressed that he did not want to go through a removable complete-denture phase in the mandibular arch during treatment.

Figure 2
Pretreatment situation. A, Occlusal view of fractured mandibular fixed dental prosthesis. B, Panoramic radiograph showing reduced periodontal support and root resorption. C, Full smile.

A review of the patient’s medical status was noncontributory and did not reveal contraindications to surgical or prosthetic treatments. After discussions, the patient opted for immediate implant placement followed by immediate loading with an interim prosthesis opposed by the existing maxillary overdenture. The patient understood that once the implants were osseointegrated, the maxillary prosthesis would require a remake along with the definitive mandibular prosthesis. The decision to use the new abutment system was also discussed with the patient. The patient’s approval and informed consent were subsequently obtained.

The patient’s existing overdenture and mandibular FDP were evaluated. Despite signs of previous repair and wear, the occlusal vertical dimension (OVD), esthetics, and phonetics provided by the existing prostheses were found to be satisfactory for virtual surgical planning.

Digital scans of the patient’s existing maxillary and mandibular prostheses were obtained by using an intraoral scanner (TRIOS; 3shape). Eight fiducial markers (CT Mark; Suremark) were placed onto the maxillary overdenture, and a device was fabricated to index the patient in centric relation (CR) at his existing OVD during the CBCT scan. Digital imaging and communications in medicine (DICOM) data were then obtained after a dual scan protocol.

The DICOM data were converted into 3D casts and merged with digital scans of the existing prostheses by using a surgical planning software program (coDiagnostiX; Dental Wings Inc), enabling the implants to be planned in prosthetically driven positions. Despite the alveoloplasty required for restorative space, adequate bone volume was available to house 6 regular-sized implants (Bone Level Tapered Implant; Straumann) ( Fig. 3 ). The standard tessellation language (STL) files of the maxillary overdenture, the mandibular FDP, and the reshaped mandible with digital scan bodies were then exported in the same 3D spatial relationship.

Jan 12, 2020 | Posted by in Prosthodontics | Comments Off on Digital workflow for predictable immediate loading in the mandible by using a shape memory dental implant abutment system: A clinical report
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