Converting a Complete Denture Into an Implant-Supported Provisional Restoration

Restoring a full maxilla or mandible with an implant-supported restoration involves a complex series of procedures that often require advanced competency.¹ These steps include the extraction of any remaining teeth, placement of implants, provisionalization of the implants, and final restoration of the implants. Commonly, the provisionalization step is performed at the time of implant placement if sufficient insertion torque is achieved.^2,3

The provisionalization of a full arch of implants may be accomplished with a denture conversion procedure, by 3D printing a provisional restoration, or by conventionally relining a prepared provisional restoration.^4,5 Using a 3D printer to fabricate a provisional restoration requires accurate digital capture of the implant positions, preparation of a virtual restoration in an STL file, a 3D printer, and time.^6,7 Although denture conversion procedures and conventional reline techniques can also be time-consuming, the use of an existing or preprepared denture with established and maintainable vertical dimension and centric occlusion greatly simplifies the provisionalization process. The materials commonly used to fabricate dentures are relatively strong and durable. However, the conventional denture conversion process requires some expertise and can create a weak prothesis due to the large holes that need to be made in the denture to accommodate the relining of components (Figure 1).⁸

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The following case report presents a new technique for denture conversion that significantly reduces the time and expertise required for converting a preprepared denture (or the patient's existing denture) into an implant-supported full-arch provisional restoration. The workflow and procedures are similar to the conventional ones that are well-known to restorative dentists; however, instead of making large holes in the denture to accommodate the components, the denture is merely relieved to accommodate them, and then once relined, the screw access holes are drilled through the copings from both the intaglio and occlusal aspects with specialized drills and guides. This not only increases efficiency but also results in a stronger and more esthetic provisional prosthesis.

Case Report

A 56-year-old female patient presented to the practice requesting to have her mandible restored with a fixed full-arch prosthesis (Figure 2). She had been wearing an ill-fitting removeable prosthesis, which was partially retained by two remaining mandibular teeth that were failing (Figure 3 and Figure 4). After the patient was presented with a treatment plan and accepted it, a surgical plan was created using cone-beam computed tomography (CBCT) with a dual-scanning technique and implant surgical planning software (3Shape Implant Studio, 3Shape) (Figure 5). In addition, an immediate denture with the desired tooth positions, centric relation, and vertical dimension was fabricated using conventional techniques (Figure 6 and Figure 7).

Extraction and Implant Placement

On the day of surgery, local anesthesia was administered, and the two remaining teeth were extracted without flap reflection. The immediate denture was then tried in, and a bite registration material (Blu-Mousse^®, Parkell) was used to record its correct seating (Figure 8 and Figure 9). After flap reflection, the immediate denture would become unstable. The prerecorded registration of the correct denture position would assure correct positioning of the immediate denture during conversion.

The implant surgical procedure was performed with a guided surgery technique (Fully Guided Surgical Kit, Keystone Dental Group). Prior to soft-tissue reflection, the surgical guide was placed intraorally and stabilized with lateral pins (Figure 10). Pilot osteotomies were created through the surgical guide, after which it was removed, and the soft tissue was reflected. The surgical guide was then reinserted and secured into position with the lateral pins. The implant surgical procedure was completed through the surgical guide using contra-angle guidance, including preparation of the osteotomies and insertion of the implants (Paltop Dynamic Implant, Keystone Dental Group).

Once the implants were placed, multi-unit abutments (Paltop Premium Multi-Unit Abutments, Keystone Dental Group) were affixed to them. These multi-unit abutments featured concave tissue cuffs that allowed for subcrestal implant placement. Straight multi-unit abutments were used for the anterior implants and angled multi-unit abutments were used for the posterior ones (Figure 11). They were all torqued to
30 Ncm.

Simplified Denture  Conversion

The simplified denture conversion technique was now initiated (EasyPro^™ Denture Conversion System, Keystone Dental Group). This system features individual sterile "delivery units" that consist of a titanium base coping, a titanium coping, and a base coping screw-all with a PEEK handle on top to make insertion easier (Figure 12). The base copings and copings feature a friction fit that facilitates multiple try-ins, occlusal corrections, and relines without retaining screws. For this case, delivery units with 6-mm tall copings were selected for all of the multi-unit abutments. The units were inserted intraorally using their attached handles and secured with the captured base coping screws (Figure 13). Inserting them prior to suturing ensures that no soft tissue is caught under the base copings. The PEEK handles were then removed by gently tilting them to the side, and the soft tissues were sutured back into place using the copings as multi-unit healing abutments (Figure 14). Next, the system's O-rings were placed over each of the copings to retract the soft tissues, expose the retentive elements of the copings, and protect the multi-unit abutments from excess reline material. The screw access holes were then blocked with a silicon putty impression material without the catalyst (Figure 15). A denture marking stick was used to mark the copings, and the denture was seated over them to mark their positions. The intaglio of the denture was then relieved in those positions so that it would seat passively over the copings in the correct position.

With the preparations for denture conversion complete, a denture reline material (Luxatemp^®, DMG America) was placed into the denture (Figure 16) as well as injected with a syringe around the copings intraorally (Figure 17). The denture was then placed intraorally, and the patient was guided to close her maxillary teeth into the occlusal registration, which ensured correct positioning (Figure 18). Following complete curing of the reline material, the denture was removed by first lifting one of its posterior sides and then lifting the opposing side. The copings were captured and securely retained in the denture along with the O-rings (Figure 19), and the base copings were left retained on the multi-unit abutments and continued to serve as healing abutments (Figure 20).

Completion and Delivery of the Provisional Prosthesis

The simplified denture conversion system's laboratory kit (EasyPro^™ Laboratory Kit, Keystone Dental Group) was now used to complete the conversion extraorally. After the O-rings were lifted out of the acrylic with an explorer, any voids around the picked-up titanium copings were filled with the reline material (Figure 21 and Figure 22). A drill guide from the laboratory kit was inserted into the first of the titanium copings on the intaglio surface of the denture, and then an intaglio drill was used through the drill guide to create a screw access hole through the titanium coping to the occlusal surface of the denture (Figure 23). This was repeated for each of the copings. Next, the system's occlusal drill was inserted into the screw access holes from their occlusal aspects and used to widen them to accommodate the final retaining screws (Figure 24). To complete the conversion and finalize the implant-supported provisional prosthesis, the flanges were removed, and the prosthesis was finished and polished (Figure 25 through Figure 27).

After the provisional prosthesis was finalized, it was ready for delivery. First, the base copings were removed from the multi-unit abutments intraorally by removing the base coping screws, and then they were press-fitted into the copings retained in the denture (Figure 28). Inserting the base copings after finishing and polishing has been completed ensures that there is a pristine machined surface that is unmodified to secure the converted denture to the multi-unit abutments. The provisional prosthesis was then inserted into the patient's mouth, and the system's final retaining screws were inserted and tightened to secure the prosthesis to the multi-unit abutments (Figure 29). The occlusion was checked and adjusted, and final radiographs were acquired to confirm complete seating (Figure 30).

Conclusion

The technique for converting an existing or preprepared denture into an implant-supported provisional prosthesis presented in this case report uses a novel denture conversion system that relies on known techniques but simplifies the workflow when compared with conventional techniques. By eliminating much of the complexity, this solution saves time and makes denture conversion for full-arch implant cases less technique sensitive and more within the capabilities of both restorative and surgical clinicians to execute with optimal results. Moreover, this solution results in stronger and more esthetic provisional prostheses for patients, improving outcomes and patient satisfaction.

About the Authors

Michael Klein, DDS
Diplomate
American Board of Oral
Implantology/Implant Dentistry
Fellow
Greater NY Academy of Prosthodontics
Chief Technology Officer
Keystone Dental Group
Private Practice
Cedarhurst, New York

Allon Waltuch, DDS
Private Practice
Cedarhurst, New York

Figures and Images

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Michael Klein, DDS

Allon Waltuch, DDS

Fig. 1

Occlusal view of an implant-supported provisional restoration that was fabricated using conventional denture conversion techniques, Note the large holes that were required to be made to accommodate the temporary components, which are unesthetic and can compromise denture strength.

Fig. 2

Pretreatment smile view.

Fig. 3

Close-up views of the patient’s mandibular arch, with and without her existing traditional denture, which was being partially retained by two remaining mandibular teeth that were failing.

Fig. 4

Close-up views of the patient’s mandibular arch, with and without her existing traditional denture, which was being partially retained by two remaining mandibular teeth that were failing.

Fig. 5

Software view of the surgical plan, which was created using a dual-scanning CBCT technique.

Fig. 6

Extraoral frontal and intaglio views of a new immediate denture that was fabricated using conventional techniques.

Fig. 7

Extraoral frontal and intaglio views of a new immediate denture that was fabricated using conventional techniques.

Fig. 8

Following extraction of the two remaining mandibular teeth, the immediate denture was tried in, and an occlusal registration for denture positioning was made using bite registration material.

Fig. 9

Following extraction of the two remaining mandibular teeth, the immediate denture was tried in, and an occlusal registration for denture positioning was made using bite registration material.

Fig. 10

Intraoral view of the surgical guide, which was fixed into position with lateral pins prior to soft-tissue reflection for the pilot osteotomies.

Fig. 11

Multi-unit abutments with a concave design were placed subcrestally and torqued to final position prior to suturing.

Fig. 12

Extraoral view of the simplified denture conversion system’s delivery unit, which consists of a titanium base coping, a titanium coping, and a base coping screw—all with a PEEK handle on top for easier insertion.

Fig. 13

The delivery units were individually placed onto the multi-unit abutments using their handles and then secured by tightening the base coping screws.

Fig. 14

Following removal of the handles by gently tilting them to the side, the soft tissue was sutured back into place with the copings acting as multi-unit healing abutments.

Fig. 15

The system’s O-rings were placed over each of the copings to retract the soft tissues, expose the retentive elements of the copings, and protect the multi-unit abutments from excess reline material, and the screw access holes were blocked with a silicon putty impression material without the catalyst.

Fig. 16

After the intaglio surface of the denture was appropriately relieved to accommodate the copings, it was filled with a denture reline material.

Fig. 17

Denture reline material was also injected around all of the copings intraorally.

Fig. 18

With the denture placed onto the copings, the patient was guided to close her maxillary teeth into the bite registration to ensure correct positioning while the reline material cured.

Fig. 19

Intaglio view of the picked-up copings and O-rings after the denture reline material cured and the denture was removed from the mouth.

Fig. 20

View of the screw-retained base copings serving as healing abutments after the copings were picked up in the denture.

Fig. 21

The O-rings were lifted out of the acrylic with an explorer, and any voids around the picked-up titanium copings were filled with the reline material.

Fig. 22

The O-rings were lifted out of the acrylic with an explorer, and any voids around the picked-up titanium copings were filled with the reline material.

Fig. 23

The system’s intaglio drill guide and intaglio drill were used to create screw access holes through the titanium copings to the occlusal surface of the denture.

Fig. 24

The system’s occlusal drill was used to widen the screw access holes from the occlusal aspect to accommodate the final retaining screws.

Fig. 25

Extraoral intaglio, frontal, and occlusal views, respectively, of the implant-supported provisional prosthesis after finishing and polishing.

Fig. 26

Extraoral intaglio, frontal, and occlusal views, respectively, of the implant-supported provisional prosthesis after finishing and polishing.

Fig. 27

Extraoral intaglio, frontal, and occlusal views, respectively, of the implant-supported provisional prosthesis after finishing and polishing.

Fig. 28

The base copings were removed from the multi-unit abutments intraorally by removing the base coping screws, and then, they were press-fitted into the copings retained in the denture.

Fig. 29

View of the completed provisional prosthesis seated on the multi-unit abutments and secured in place with the system’s final retaining screws.

Fig. 30

Final radiographs acquired to confirm complete seating of the provisional prosthesis.

Fig. 30

Final radiographs acquired to confirm complete seating of the provisional prosthesis.

Fig. 30

Final radiographs acquired to confirm complete seating of the provisional prosthesis.

Fig. 30

Final radiographs acquired to confirm complete seating of the provisional prosthesis.

Michael Klein, DDS

Allon Waltuch, DDS