Full-Arch Zirconia Screw-Retained Prosthesis

Drs. Delia Tuttle and Gregori M. Kurtzman


The full-arch, all-ceramic, implant-supported, screw-retained prosthetic option is gaining in popularity among clinicians, replacing prostheses that previously were being fabricated using metal substructures. Although some cases are immediately loaded, a delayed approach enables practitioners to work out aesthetics, phonetics, and the vertical dimension of occlusion (VDO) in a traditional removal prosthesis prior to implant placement. This is especially helpful when there has been a severe breakdown of the dentition that has compromised the VDO and the aesthetics due to the drifting of any remaining teeth related to periodontal disease. The transitional denture may be utilized as a guide to determine implant placement. This is done via a CBCT stent that allows the clinician to plan implant positions that correspond to the osseous anatomy and tooth positions as worked out intraorally and accepted by the patient.

Diagnosis and Treatment Planning

A 65-year-old female presented with pain and mobility in the maxillary dentition. The radiographs and clinical exam showed periodontal issues with significant bone loss on the remaining maxillary teeth. The maxillary bridges demonstrated 70% to 80% bone loss of the abutment teeth with corresponding mobility (Figure 1). The mandibular dentition presented with slight bone loss but no mobility.

Figure 1. Periapical radiographs, taken when the patient first presented, demonstrating significant bone loss and a failing dentition.

Following a discussion with the patient regarding her treatment desires, a plan was presented to have an immediate maxillary full denture as a transitional prosthesis at the extraction appointment, socket grafting, and scaling/root planing on the mandibular teeth. Following a healing period to allow the socket grafts to convert to host bone, implants would be placed. The patient would continue to wear a relined transitional maxillary prosthesis, and, after implant integration, the implants would be uncovered and impressions would be taken. A lab-fabricated, screw-retained transitional implant bridge would then be inserted. The transitional prosthesis would be worn to verify that the VDO, aesthetics, and phonetics were acceptable to the patient and the practitioner. The interim prosthesis would then be converted to the final implant-supported screw-retained zirconia bridge.

Full-arch impressions and interocclusal records were taken and sent to the dental laboratory team for the fabrication of a full-arch removable transitional prosthesis. First, the lab team mounted the casts using the interocclusal record provided. Then the remaining maxillary teeth were removed from the cast and denture teeth were set up in wax, processed and finished, and returned to the office.

Stage 1: Extractions, Socket Grafting, and the Transitional Prosthesis
Local anesthetic (4% Septocaine with 1:100,000 epinephrine [Septodont]) was administered to the maxillary arch. The maxillary teeth were atraumatically extracted and the sockets were curetted to remove any possible apical pathology present. The sockets were then filled with a porous equine-derived bone graft substitute (Equimatrix [Osteohealth]) that closely resembles human bone. Equimatrix was chosen due to its osteoconductive properties. A resorbable collagen membrane (Collatape [Zimmer Biomet]) was placed over each socket and secured with a figure 8 suture using 4-0 nylon monofilament (LOOK [Henry Schein]). Next, the denture was relined with a soft-tissue conditioner (Visco-Gel [Dentsply Sirona]), and the patient was dismissed.

The patient returned 10 days later for suture removal and an evaluation of the healing progress. The soft tissues were healing well, with a lack of inflammation at the extraction sites.

Stage 2: Implant Planning and Placement
Radiographs at 6 months showed that the socket grafts blended with the surrounding bone. A duplicate of the transitional prosthesis was made (Lang Denture Duplicator [Lang Dental]). Alginate was mixed and placed into half of the duplicator, and then the transitional prosthesis was inserted teeth-side down until the alginate reached the edges of the denture flanges. After the alginate set, another batch was mixed and placed into the tissue side of the denture, and the duplicator was closed. Upon setting, the duplicator was opened, and the denture was removed and returned to the waiting patient. A barium sulfate acrylic (JetXR [Lang Dental]) was mixed and poured into the mold created with the duplicator and then closed. Upon setting, the radiopaque duplicate was removed and trimmed.

Figure 2. Implant planning with Anatomage (Invivo) of a CBCT (i-CAT) scan of the patient.
Figure 3. The surgical stent was fabricated based on virtual planning of the implants using Anatomage software. Lateral pins are used to lock the guide to the arch to ensure the accuracy of the implant placement, replicating the virtual planning. Figure 4. A tissue punch was used through the surgical guide prior to lateral pin engagement to remove soft tissue over each site planned. The circular pieces of tissue were retained for site closures following placement of the implants.
Figure 5. A CAD/CAM surgical guide was placed onto the arch. Lateral pins were engaged to secure the guide and to avoid displacement of the guide during osteotomy preparation. Figure 6. Implants have been placed and fixture mounts can be observed on each implant, demonstrating parallelism between the fixtures.
Figure 7. A panoramic radiograph at the implant placement, documenting implants as related to osseous anatomy present. Figure 8. The circular pieces of gingiva created with the tissue punch were repositioned over each implant cover screw and then sutured in place using a figure 8 suture with 6-0 polypropylene monofilament.

A CBCT (i-CAT) was taken with the radiopaque denture replica to allow visualization of the needed tooth position for aesthetics and phonetics in relation to the available bone. Then the CBCT data was converted using Anatomage (Invivo) planning software. The treatment plan required 7 implants to support a full-arch, 14-unit fixed prosthesis. Implants were virtually placed based upon available bone, and horizontal fixation pins were placed to stabilize the guide during surgery (Figure 2). Implants (InterActive [Implant Direct]) with SBActive surfaces were chosen for all the selected tooth positions in the following sizes: No. 3 (4.3 x 8 mm), No. 4 (3.7 x 11.5 mm), No. 7 (3.2 x 10 mm), No. 9 (3.2 x 10 mm), No. 11 (4.3 x 13 mm), No. 13 (3.7 x 10 mm), and No. 14 (4.3 x 8 mm). A surgical guide was then ordered from Anatomage (anatomage.com) (Figure 3).

Local anesthetic (Septocaine) was administered. The surgical guide was inserted intraorally, and a 4.0-mm disposable tissue punch (Salvin Dental Specialties) was introduced through each guide hole on the surgical stent to mark the soft tissue corresponding to the preplanned implant positions. The guide was removed, and the tissue punch was utilized to core a piece of soft tissue at each site. The gingival pieces were then set aside (Figure 4). The surgical guide was reinserted, and horizontal fixation pins were engaged to lock the guide to the arch for the guided surgery (Figure 5).

Implant osteotomies were created with the guide and following the implant manufacturer’s protocol (Implant Direct). The horizontal fixation pins and the guide were then removed. The implants were placed into each osteotomy and demonstrated the parallelism that is a result of using guided surgery (Figure 6). A panoramic radiograph was taken to document implant position (Figure 7). Next, fixture mounts were removed and cover screws placed. Tissue-punched gingival circles were positioned over each cover screw and fixated with a figure 8 suture using 6-0 polypropylene monofilament (Henry Schein) (Figure 8). The denture was relined with Visco-Gel and the patient was dismissed. The patient returned after 7 days to have the sutures removed.

At 7 weeks post-implant placement, the patient had a complaint of tenderness in the area of the No. 7 implant. A perimucositis was noted. Patient blood was drawn and centrifuged following the Choukroun protocol for injectable platelet-rich fibrin (i-PRF), placed into a syringe, and injected into the tissue around the mucositis. The patient returned the following day to check the healing progress, and it was noted that the inflammation at the site had resolved.

Step 3: Provisional Prosthetics
At 6 months, after allowing for implant integration, the patient returned for implant uncovery. The surgical stent was inserted, and local anesthetic (Septocaine) was administered at each guide hole. An explorer was introduced through the guide to mark each implant site, and the guide was removed. A No. 12C scalpel blade was utilized to uncover the cover screw over each implant. Healing abutments were placed (Figure 9), and a new denture soft reline (Visco-Gel) was done.

The soft tissue was allowed to mature for 2 weeks before the patient returned again. Local anesthetic was administered (Septocaine), and the healing abutments were removed. A coarse football diamond (Maxima #900-7054, [Henry Schein]), in a highspeed handpiece with water, was used to flatten the crestal soft tissue between the implants to avoid food retention under the final prosthesis and allow better homecare by the patient. The thickness and quantity of keratinized tissue made this step possible (Figure 10).

The lab team, using the surgical stent and analogs, created a stone verification model. Open tray impression abutments were placed onto the verification model, and a resin verification stent was created using PATTERN RESIN LS (GC America). Upon setting, a thin disk was used to section the verification stent between each abutment to relieve any polymerization shrinkage created during the setting of the resin. This was returned to the office, and each segment was inserted intraorally. Radiographs were taken to verify abutment seating on the implant. GC Pattern resin was utilized to lute the segments together intraorally to verify the inter-implant relationship (Figure 11).

Figure 9. Following a 6-month healing period for integration, the implants were uncovered and healing abutments placed, allowing for soft-tissue maturation at the exposed sites. Figure 10. Soft tissue at the crest was modified with a diamond in a high-speed handpiece to level the tissue to create a better mating surface with the prosthesis (elimination of papilla to improve hygiene and decrease potential food traps under the prosthesis).
Figure 11. The lab-fabricated verification stent, sectioned between fixtures and with open-tray impression abutments, has been individually inserted to verify passive fit. Markings on the segments were used to confirm alignment of segments to adjacent segments. Figure 12. A custom tray with occlusal holes corresponding to the positions of the open tray impression abutments was used to pick up the verification stent intraorally as the master impression.
Figure 13. The lab team returned a one-piece verification stent fabricated on the soft-tissue master cast to verify passive fit and to confirm accuracy of the master impression. Figure 14. Panoramic radiograph with verification stent to verify full mating of the abutments to the implants, confirming accuracy of the master cast.
Figure 15. Denture teeth and an acrylic provisional screw-retained prosthesis were fabricated and inserted as a trial prosthesis to verify the vertical dimension of occlusion, aesthetics, and phonetics. Figure 16. The trial provisional bridge, demonstrating natural aesthetics.

A previously fabricated custom tray (Custom Tray Material #102-7977 [Henry Schein]) was tried in over the verification stent to check that each open-tray impression pin emerged through the tray. Tray adhesive (Henry Schein) was applied, and, after drying, the tray was filled with a heavy body regular set vinyl polysiloxane (VPS) impression material (Henry Schein). A VPS light body fast set impression material (Henry Schein) was injected around the gingival aspects of the verification stent as well as under the resin stent. The filled custom tray was inserted and allowed to fully polymerize (Figure 12). Upon setting, the open-tray impression pins were unscrewed, and the tray was removed. The healing abutments were reinserted, and a new soft reline (Visco-Gel) was placed in the denture.

A soft-tissue master model was created, and the lab team returned a stone verification stent that was fabricated using the open-tray impression abutments and model stone (GC FUJIROCK EP [GC America]). The patient returned to the office, and the healing abutments were removed. Then the stone verification stent was tried-in to check the accuracy of the master model (Figure 13). A panoramic radiograph was taken to verify passive fit of the stone verification stent (Figure 14).

The lab team mounted the casts, and titanium temporary abutments were placed, with the height adjusted to fit the available space established. Denture teeth (SR Phonares II [Ivoclar Vivadent]) were set in wax, and the screw-retained provisional prosthesis was processed using the IvoBase Injector (Ivoclar Vivadent) and denture base material (SR Ivocap High Impact [Ivoclar Vivadent]). The provisional prosthesis was finished and polished. A final coat of GC Optiglaze (GC America) was applied to the prosthesis to improve the durability and aesthetics. Healing abutments were removed and the provisional screw-retained prosthesis was inserted and the fit verified by radiographs. Fixation screws were tightened to 30 Ncm with a torque wrench, and screw access holes were filled with polytetrafluoroethylene (PTFE) tape and sealed with Telio CS Onlay (Ivoclar Vivadent) temporary filling material. The occlusion was then checked and adjusted as needed (Figure 15).

Step 4: Final Prosthesis
The patient functioned with the trial provisional prosthesis for 6 months to confirm satisfaction with the aesthetics. The provisional prosthesis provided a natural appearance, and the patient was satisfied with the aesthetic results (Figure 16).

The patient returned to the office, and the prosthesis was removed and placed onto the implant cast containing analogs. The screw access holes on the prosthesis were filled with the Telio CS Onlay temporary filling material and then light cured. GI-MASK (COLTENE) was injected between the provisional prosthesis and the cast to form a soft-tissue replication of the gingiva. The model with the prosthesis was then placed into the bottom half of the anaxFORM (anaxDENT) metal-flask filled with MATRIX FORM 60 (anaxDENT) addition silicone and allowed to set.

Next, MATRIX FORM 70 (anaxDENT), an addition silicone with the ability to capture greater marginal detail, was mixed and adapted over the provisional prosthesis, and additional MATRIX FORM 60 was placed into the upper half of the anaxFORM flask. The flask was then assembled and allowed to set. Upon setting, the flask was separated (Figure 17). The provisional prosthesis was reinserted, and the patient was dismissed.

The lab team then injected polyurethane (Set Frame [Zirkonzahn USA]) into the mold created by the anaxFORM flask and allowed it to set, creating a replica of the provisional bridge (Figure 18). The facial surfaces of the polyurethane teeth were cut back to provide space for the ceramic that would overlay the zirconia frame. The polyurethane replica was copy milled to create a zirconia replica in its green state (unfired) in HT zirconia (GC HT Initial Zirconia [GC America]). The zirconia was characterized with diamond disks and stains in various shades and hues (Copran Monolith Color PaintOn [WhitePeaks Dental Solutions]) applied to infiltrate the zirconia during firing to create life-like effects. The HT zirconia was sintered according to the manufacturer’s instructions (Figure 19).

GC Intial Zr-FS (GC America) was applied in various tooth shades (high chromatic dentin, enamel, and incisal) on the facial surfaces to provide multichromatic aesthetics. Gingival tone (GC Intial Zr-FS Gum Shades) was applied to gingival aspects of the prosthesis. The ceramic was fired, a final glaze was applied, and final firing was done (Figure 20). GC METALPRIMER II (GC America) was applied to the Ti bases and luted to the zirconia prosthesis with resin cement (G-CEM LinkAce [GC America]). A light-cured, micro-filled hybrid resin composite (GRADIA DIRECT [GC America]) in shade GO13 (gingival opaque) was applied to the gingival aspect of the Ti bases, where they merged with the zirconia to finalize the emergence contours. The prosthesis was then returned by the lab team for delivery to patient.

Figure 17. Replication of the trial provisional bridge in the anaxFORM (anaxDENT) flask. Figure 18. A polyurethane replica of the provisional bridge is shown on the model with soft tissue removed, articulated with the lower cast.
Figure 19. The milled and sintered monolithic zirconia screw-retained bridge framework. Figure 20. The occlusal view of the completed zirconia and ceramic overlay bridge on the master model, demonstrating screw access holes in the prosthesis for the screw-retained bridge.
Figure 21. The completed monolithic zirconia implant-supported screw-retained bridge. Figure 22. The patient was happy with the natural aesthetics of the final prosthesis.

The provisional prosthesis was removed, the zirconia screw-retained prosthesis was tried-in, and the screws were tightened by hand. Radiographs were taken to verify the full mating of the prosthesis to the implants. Fixation screws were tightened with a torque wrench to 35 Ncm, per manufacturer’s directions. Screw access holes were filled with PTFE tape and then sealed with composite (Estelite Sigma Quick [Tokuyama Dental America]) (shade A1) and light-cured. The occlusion was checked, and the patient was dismissed (Figure 21). She returned a week later to check and adjust the occlusion as needed. At this time, she expressed her satisfaction with the aesthetic results (Figure 22).

From a material standpoint, implant-supported prostheses have evolved from prostheses utilizing metal substructures to zirconia prostheses without metal frameworks. The benefits of the zirconia approach are more natural aesthetics, as any potential graying of the ceramic due to metal substructure is eliminated. Additionally, overlaying ceramics to the zirconia following a cutback of the prosthesis allows a multichromatic result that overcomes the opaque potential associated with monolithic zirconia, providing more lifelike aesthetics. Planning these cases to achieve the patient’s desired results utilizes a provisional screw-retained prosthesis where occlusion, aesthetics, and phonetics can be worked out and tested until the patient is satisfied. The provisional prosthesis then acts as the blueprint to duplicate for the fabrication of the final prosthesis.

Laboratory work for the case shown was done by Bill Marais, RDT, at Disa Dental Studio (Portland, Ore).

Dr. Tuttle is a dual-trained dental professional who practiced as a physician before she fell in love with dentistry. Her passion for medicine led her toward the medical aspect of dentistry, and she devoted herself to soft-tissue engineering using the patient’s own blood derivatives. Dr. Tuttle is in private practice in California. An international speaker, she educates dentists and specialists on the Gum Drop Technique (GDT) root-coverage procedure using biological factors advanced platelet-rich fibrin (A-PRF) and injectable platelet-rich fibrin (i-PRF). Dr. Tuttle developed an international movement empowering women in the dental field called Divas in Dentistry. She can be reached via email at tuttledelia@yahoo.com.

Disclosure: Dr. Tuttle has a financial interest in Implant Direct.

Dr. Kurtzman is in private general practice in Silver Spring, Md, and is a former assistant clinical professor at the University of Maryland in the department of endodontics, prosthetics, and operative dentistry. He has earned Fellowships in the AGD, American College of Dentists, International Congress of Oral Implantologists (ICOI), Pierre Fauchard Academy, and Academy of Dentistry International, as well as a Mastership in the AGD and ICOI and a Diplomate status in the ICOI and American Dental Implant Academy. He has lectured internationally on restorative dentistry, endodontics, implant surgery, prosthetics, removable and fixed prosthetics, and periodontics, and he has published more than 575 articles. He is privileged to be on the editorial board of numerous dental publications, a consultant for multiple dental companies, and a former assistant program director for a university-based implant maxi-course. He can be reached via email at drimplants@aol.com.

Disclosure: Dr. Kurtzman reports no disclosures.

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