Predictable Implant-Supported Partials: A Resin Record Base Technique

Managing partially edentulous patients remains a challenge. Replacing missing teeth with conventional removable partial dentures (RPDs) is the traditional treatmentⁱ.The development of sophisticated narrow diameter implant techniques to produce satisfying results improves prosthetic rehabilitationⁱⁱ . Visible Light Cured (VLC) resins significantly increase the predictability of restoration, contributing to the precise planning of both implant placement and subsequent esthetic and functional rehabilitation. In this case, a patient presenting with anterior mandibular restoration needs was rehabilitated with a reinforced VLC partial denture, supported by locator implants--a clinically predictable and cost effective treatment.

Case Study

The patient presented with three Locator attachments in place.Two of these were in the root canal of anterior mandibular teeth, and the third in the mandible itself (Fig. 1).

Fig. 1: Patient at presentation

A final impression was taken using a VPS material and a disposable tray (Exafast and COE) with locator analogs in place. Putty VPS was placed in the palate to create a box rim analog. The master cast was poured using a fast setting gypsum composite (Earth Stone).The boundaries of the record base were marked on the model (Fig 2), after block out was accomplished using a contrast-colored modeling compound (Play-Doh).

Fig 2:  Marked Master Model

Visible-light-cured resin gel (Triad) was then used to follow the outline (Fig 3). A length of about an inch at a time was laid out following the markings. The Triad Gel was tack-set with a handheld light (Coltolux) to increase stability in handling. While the manufacturer’s directions do not call for this step,it offers a clear boundary to fabricate the record base in the next step.

Fig. 3: Triad Gel Outlining

Fig 4:  Triad Transheet Record Base

Transheet VLC record base material (Triad) was adapted to the boundaries marked by the Triad gel (Fig 4). Note that the record base is kept 2-3mm below the plane of occlusion, and notches are created in it. The record base is then cured according to directions in the Triad 2000 VLC curing unit (Figs. 5 & 6). The cured record base then becomes an effective lab communication toolⁱⁱⁱ.

Fig. 5: Cured Record Base on Model

Fig 6: Gingival Aspect of Record Base

The Triad record base fabricated in the previous step can be enhanced by the addition of a simple bite registration step.

The notches placed in the record base act as mechanical retention. Recall that the record base is fabricated to fit well below the plane of occlusion by 1-2mm (Fig 7).

Fig. 7: Record Base with Retention

The final jaw relation record can then be picked up with a VPS registration material (Fig 8) with a mousse-like viscosity (Access Blue). The bite registration (Fig. 9) can then be transferred into mounted casts (Fig. 10), giving the lab complete information about the case, including all relevant spatial relationships^iv. Overall, this process cuts down a process of 2-3 appointments to 60-90 minutes.

Fig 8:  Final Jaw Relation Record

Fig. 9: Bite Registration with Record Base

Fig 10:  Mounted Casts

Partial Denture Fabrication and Delivery

Given the span of the partial denture and the flexure constraints imposed by the implants, I decided to prescribe a hybrid partial denture – one created of a visible light cured denture base resin (Eclipse) reinforced with a durable chrome-cobalt alloy (Vitallium 2000). The countour and set-up resin areas on this RPD would be fabricated using a conventional high-strength acrylic (Lucitone 199). The design and fabrication of the cast partial framework is illustrated in Figs. 11 & 12. The framework was micro-etched and coated with a primer (Metal Primer II).

Fig. 11: Cast Vitallium Framework

Fig 12: Framework in Mounted Cast

The choice of VLC resin systems for the partial denture base is also significant. Processing of the dentures with traditional methods has been a time-consuming procedure. This normally delays delivery of the finished dentures following the try-in appointment. Utilizing the light-curable system, Eclipse, baseplate processing time can be shortened to less then thirty (30) minutes^v.A further advantage to the system is that the resin is processed directly on to the model, reducing the possibility of distortion in injecting (Figs. 13 & 14).

Fig. 13: Adapting Eclipse to Model

Fig 14: Reinforced  Eclipse Baseplate

The processed Eclipse base plate is used with wax and highly cross-linked acrylic teeth (Portrait IPN) for try-in (Fig 15). The patient was satisfied with the occlusal scheme after minor modification (Fig. 16). Functionality was verified with phonetic excursions^vi.

Fig. 15: Record Base with Wax

Fig 16:  Patient Try-In

A high-impact-strength denture base acrylic (Lucitone 199) was used to create the contour and set-up areas of the partial denture using a conventional flasking process. The finished denture was esthetic, and created an excellent fit (Figs. 17 & 18).

Fig. 17: Finished RPD

Fig 18: Finished RPD – Alternate View

The manufacturer-recommended tool was used to remove the locators. Male locator retention options were evaluated, and straight locators (3-1.5lb torque) were selected. The male locators were inserted into the RPD, and the final result delivered to the patient (Figs. 19 & 20). The patient expressed esthetic and functional satisfaction. He was subsequently instructed in home care and dismissed.

Fig. 19: RPD Insertion

Fig 20:RPD Insertion- Alternate View

Summary

Implant-supported RPDs deliver many of the combined advantages of fixed and removable partial dentures to the patient. The use of an expedited clinical and laboratory sequence, featuring visible light-cured systems enhances efficiencies in delivering patient care. The predictability of the prosthodontic rehabilitation, in the author’s opinion, was significantly increased by use of the VLC record base and final RPD base.

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