Simultaneous Virtual Planning Implant Surgical Guides and Immediate Laboratory-Fabricated Provisionals: An Impressionless Technique

The virtual planning platform is created by merging the New Tom Cone Beam CT DICOM data with the iTero intraoral digital scan Standard Tessellation Language files. The file merge is completed with software from Glidewell Laboratories. In an online meeting format, the surgeon and laboratory technician simultaneously design both the surgical guide and a virtual wax-up of the provisional restoration. Once the guide and provisional restoration designs are completed with the 3-Shape software, a 3D printer is used to directly print the surgical guide. The provisional bridge is fabricated by computer-aided design/computer-aided manufacturing milling, and the abutments are incorporated into the bridge, to allow fixation of the provisional directly onto the implants platforms with nonengaging screws through the abutments' conical connection. The provisionals are hand torqued. This process is currently in the beta testing stage.

The patient was a 58-year-old Caucasian woman who had suffered a ground-level fall in her 20s with resultant avulsion and permanent loss of her mandibular left canine and the 4 incisors (Figure 1). After a discussion of treatment options with the patient, she elected reconstruction of the bony defect followed by placement of implant-supported fixed prosthesis. This was achieved in 3 phases as outlined below.

An anterior vestibular incision was made 10 mm from the mucogingival junction followed by reflection of A full-thickness mucoperiosteal flap. Next, a titanium mesh was adapted to the area and was trimmed to leave approximately a 1- to 2-mm free margin around the periphery,¹⁰  which will help prevent wound edge dehiscence.¹¹ 

A mixture of 3 mL of mineralized freeze-dried bone graft (Puros, Zimmer Biomet, Carlsbad, Calif) and BMP-2 (Infuse, Medtronic, Dublin, Ireland) 50:50 was inserted onto the defect under the titanium mesh,^12,13  which was secured with 3 mini-screws^14–17  (Figure 2). The flap was repositioned with several interrupted 4-0 polytetraflouroethylene (PTFE) sutures.

Multiple follow-up visits showed that there was uncomplicated healing, confirmed 6 months after the procedure with a CBCT showing improved ridge dimensions (Figure 3).^18–20 

Virtual implant placement and wax-up allowed the “trial” placement of several different versions of the restoration. The most esthetic and functional solution was determined to be 4 anterior teeth (Figure 4). Using the virtual rendering and CBCT information, it was determined that there was adequate room for only 2 implants: at sites of teeth 23 and 25. Using this information, the final surgical guide was designed (Figure 5) as well as a 4-unit screw-retained fixed prosthesis.

A midcrestal incision was performed in the edentulous area extending to the mesiobuccal line angle of the adjacent teeth bilaterally, and the tissue was reflected (Figure 6).^21,22  Next, the mesh and 3 screws were removed, and the tooth-borne surgical guide was seated (Figure 7). At this point, the implant sites osteotomies were performed at sites 22 and 24 through the guide, which was designed to guide not only the angulation but also the depth of the osteotomies, which was followed by the use of the bone profiler to remove any potential bony interference with seating of the provisional. The preselected depth allowed for the proper biologic width of 2 mm to allow for the proper emergence of the 4-unit provisional bridge. The 2 implants were placed also through the guide, and they were both 3.7 × 13 mm. The bridge was then seated passively and secured with the retention screws by hand torque (Figures 8 and 9). The occlusion was evaluated, and no adjustment was necessary.⁸  The case was planned for final restoration after 4 months of healing.

The patient was a 27-year-old Caucasian man who was involved in a bicycle accident. The patient sustained fractures to teeth 7, 8, and 9 that indicated extractions. Also, the patient had a preexisting dental implant at site 10, of which its crown was fractured; furthermore, the implant was angled and at an unfavorable direction and could not be used to help restore the remaining injured teeth; therefore, it was also planned for removal. After discussion of the different treatment options with the patient, he elected to have an implant-supported fixed restoration, which would be accomplished in the phases as outlined below:

Teeth 7, 8, and 9 were extracted using a careful forceps technique to maintain all the bony walls. The preexisting implant at site 10 was also removed by torqueing it with forceps. Next, a resorbable collagen membrane (BioMet 3i OsseoGuard Flex, Collagen Matrix, Allendale, NJ) was adapted palatally, between the alveolus and the palatal flap, and all of the sockets were packed with a mixture of 70% mineralized freeze-dried bone (Puros) and 30% hydroxyapatite xenograft (Endobon, BioMet, Sarl, France) to provide bulk to the graft.⁹  The membrane was then adapted labially under the flap, and the site was closed with PTFE sutures. BMP was not used as in case 1, because it was felt that the BMP cost cannot be justified for this particular case. Extraction socket grafting has been frequently successful without additional growth factors, such as BMP. An Essex-type provisional was delivered to the patient to wear during the graft-healing phase.

After 4 months of uneventful healing (Figure 10), the patient presented to the clinic for a CBCT scan and an intraoral iTero scan (Figure 11a and b). The file merge, guide fabrication, and restoration design were completed with software from Glidewell Laboratories following the same method as in case 1. Virtual planning identified the location of the implant fixtures to be best at sites 7, 8, and 9 (Figure 12), and the planned restoration was a 4-unit prosthesis spanning from teeth 7–10 and where 10 is cantilevered.

A crestal incision was made across the center of the edentulous ridge, and labial and palatal full-thickness mucoperiosteal flaps were reflected. The surgical guide was seated, and the implants osteotomies were performed at sites 7, 8, and 9. Next, the 3 implants were all size 3.7 × 13 mm and were placed through the guide (Figure 13a and b). Next, the provisional restoration, which already has the laboratory incorporated abutments in it, was seated directly on the implant platforms and noted to be passive. Then the bridge was secured to the implants with 3 screws (Figure 14). The prosthesis was free of occlusal contacts. The soft-tissue flaps were then closed with chromic sutures after the prosthesis was fixed in place. The screw access holes were sealed with Teflon tape and Cavit material. The postoperative radiograph showed proper implant placement and alignment (Figure 15). The patient returned for a 3-week follow-up visit, showing a well-healed soft tissue, except at the papilla between sites 9 and 10, where there was preexisting vertical bone loss from the previous No. 10 implant (Figure 16a and b). This defect will be addressed at the time of final restoration if necessary. The patient returned for the final restoration 8 months postimplant placement and at the time had excellent soft tissue response to the provisional (Figure 17a and b).

Patients' expectations and demands have become greater than ever to reestablish esthetics, form, and function quickly and efficiently. The 3D evaluation of patients for dental implants has opened new avenues to clinicians for accurate and predictable diagnosis and treatment planning in a multidisciplinary patient-based approach to meet the patients' expectations without compromising the treatment outcome.^21,22 

The technology described in this article facilitates dental implant placement and immediate provisionalization without the inconvenience of conventional dental impressions. This offers the precision and predictability of guided implant placement as well as a custom, passively fitting, immediate provisional restoration.

Abbreviations

3D

3-dimensional

CBCT

cone beam computerized tomography

PTFE

polytetraflouroethylene