Meeting Implant Challenges with a Patient-Specific Solution

One concept that has undergone something of a renaissance today is the telescopic implant bridge that is removable by the patient. This solution combines the benefits of a rigidly fitting yet passive attachment point to the custom implant abutment, which eliminates micro-movement of the prosthesis, thereby limiting trauma to the mucosa surrounding the implant sites. Additionally, the ability of the patient to clean around free-standing implant abutments is enhanced, unlike screw-retained hybrid prostheses.^1,2

The telescopic implant bridge is also flexible enough in its design phase that it effectively meets even very challenging situations in terms of implant positioning, angulation, and restorative space.

The following case presentation highlights the ability of this type of prosthesis to treat even the most complex cases.

The patient presented with a partially edentulous mandible and four previously osseo-integrated MegaGen implants (PREAT, preat.com) (Figure 1). Adding to the complexity of the case, the patient was found to be in a skeletal Class-III relationship. The challenges became apparent after the initial impression was poured in vacuum-mixed type-IV resin-reinforced die stone (FujiRock IMP, GC America Inc., gcamerica.com), particularly the lack of space between the distal implant sites and teeth Nos. 19 and 30 (Figure 2 and Figure 3).

The lack of space necessitated an altering of the open tray impression copings (Figure 4 and Figure 5) using an analog holder and heatless stone with a handpiece. This allowed enough space to fabricate a verification jig using a light-curing resin (Primosplint, Primotec USA, primotecusa.com) that could preserve the detail of the adjacent dentition and not add tension via contact between the jig and dentition (Figure 6 and Figure 7).

The jig was sectioned, and a buccal port, which communicates with the sectioned gap so that light-curable syringe material can be added via the port and flow into the sectioned gap for ease of clinical use (Figure 8), was added. A custom tray was made to fit over the verification jig and allowed the long screws to remain exposed and accessible for taking impressions (Figure 9).

After luting the verification jig together intraorally (Figure 10), a verified master impression was taken by flowing impression material underneath the luted jig and loading the custom tray. Upon examination, the impression was found to be perfectly intact between the distal implant sites and the mesial walls of teeth Nos. 19 and 30 (Figure 11 and Figure 12), with no exposure of the verification jig.

The verified master cast is an integral part of any implant-assisted prosthesis, so great care was taken to maintain the accuracy of this cast. In order to further protect the implant analogs against the possibility of any movement during the setting of dental die stone, the analogs were prepared by air abrasion with aluminum oxide at 2-bar pressure, and a metal primer was applied (Figure 13). The impression was sprayed with a silicone-based separating agent so that the soft tissue material would not adhere to the impression material. The implant analogs were fastened to the open tray impression copings, and soft tissue material was injected (Figure 14). Bur shank sections were measured, cut, and air-abraded, and metal primer (GC Metal Primer, GC America Inc.) was applied. The sections were then connected using a light-curing resin with a very low shrinkage rate (Jig-Gel, RH Supplies, rhsupplies.com) and cured one section at a time (Figure 15). The master verified cast was boxed and poured in vacuum-mixed resin-reinforced die stone (Figure 16).

The master cast was blocked in wax where desired, and two of the sites were chosen for use in a bilaterally screw-retained base plate and wax rim. Non-engaging temporary titanium cylinders (MegaGen) (Figure 17) were air-abraded with aluminum oxide at 2-bar pressure and placed on the master cast. Marks were made for altering the titanium cylinders (Figure 18). The cylinders were fastened to an extra analog, and the height was adjusted using a fiber cutting disc (Figure 19). Metal primer was applied to the cylinders, and a light-curing resin (Triad Gel, Dentsply Sirona, dentsplysirona.com) was applied to the retentive portion of the cylinder and light-cured (Figure 20). A light-cured base plate material was then shaped and contoured to the edentulous ridge, incorporating the Triad Gel and titanium cylinders. Once cured, a wax rim was measured, cut, and fixed to the baseplate (Figure 21). A wax milling bur was used to provide a clean access hole through the wax to the screw head of the titanium cylinder.

In the dental office, the wax rim was fixed to the two implant sites, ready for bite registration material to be injected (Figure 22 and Figure 23). Once this was completed, the models were articulated (Figure 24). Typically in cases like these, where the patient has a skeletal Class-III relationship, tooth selection is critical, so a wider mold was selected to make up for the distance needing to be covered. The teeth were set into the same screw-retained base plate. Care was taken to replace only the dentition and soft tissues that were lost (Figure 25 and Figure 26). Over the implant sites, the teeth were made to be removable with a wax socket, giving access to the screw heads. When the tooth was reinserted, it was undetectable (Figure 27 and Figure 28).

Once the wax try-in was approved in terms of esthetics, phonetics, and function, it was time to begin the digital process. This portion of the case is covered in the second part of this MasterClass series.

Arian Deutsch, CDT
Owner
Deutsch Dental Arts
Surprise, AZ