Delivering a Zirconia Resin-Bonded Fixed Partial Denture

Single-wing prosthesis provides an esthetic solution for a patient too young to receive an implant

Melissa Seibert, DMD, MS

A 19-year-old male patient first presented to his periodontist seeking implant placement at the site of tooth No. 10 (Figure 1). After an evaluation, however, it was determined that he was not done growing and thus not a suitable candidate for an implant. The patient was then referred to the author for alternative restorative treatment to replace the missing lateral incisor until such a time that an implant could be placed. After being presented with several treatment options, the patient elected a zirconia resin-bonded fixed partial denture. It should be noted that a zirconia resin-bonded fixed partial denture is not the same as a Maryland bridge, which utilizes porcelain fused to metal, although the two terms are inadvertently used interchangeably.

With zirconia resin-bonded fixed partial dentures, case selection and occlusal analysis are critical for success. The ideal occlusal scheme for this type of prosthesis is one in which the patient has a shallow overbite and the tooth selected for the retainer, or "wing," is not mobile. In this case, the patient's occlusal scheme was also evaluated to ensure that he would not be guiding off of the pontic (Figure 2). It was determined that this patient was an excellent candidate for this prosthesis because of his shallow overbite and the lack of guidance that would be associated with the pontic when it became tooth No. 10.

Tooth No. 11 was selected for the retainer due to the ease with which the connector between the retainer and pontic could be hidden (Figure 3). Because tooth No. 9 was rotated facially, if the retainer was placed on it, the connector would be readily exposed and reveal that tooth No. 10 was in fact a prosthesis. Canines also generally have more enamel than central incisors, so they can be prepared with less risk of exposing dentin.

To begin, the lingual and mesial surfaces of tooth No. 11 were prepared to a depth of approximately 0.5 mm (Figure 4). The purpose of preparing tooth No. 11 was to facilitate a positive stop for when the prosthesis was finally delivered. The design included the use of a rounded shoulder on the apical margins and a feather-type finish line on the incisal aspect, and facial contact was never broken when the mesial surface was prepared. Alternatively, a "jig" could have been fabricated by the laboratory to enable delivery.

A final impression was made using an optical scanner (Primescan^®, Dentsply Sirona), and the final restoration was then designed (DentalCAD, exocad). Because only the enamel was prepared and the lingual part of the preparation was not visible, tooth No. 11 did not require a temporary restoration. The laboratory was asked to fabricate a resin-bonded fixed partial denture with a 3Y-TZP zirconia substructure (Katana^™ Zirconia HTML, Kuraray Noritake) and then stack feldspathic porcelain over the facial surface of the pontic to enhance the esthetics. In effect, the connector and retainer would be entirely 3Y-TZP zirconia with a thickness of 0.8 to 1.0 mm (Figure 5).

On the day of delivery, a gingivoplasty of the edentulous ridge at the tooth No. 10 site was completed to create a natural-looking emergence profile for the pontic. The gingiva was prepared to exhibit a saucer-like morphology with a depth of 1.5 mm using a fine diamond bur without irrigation (Figure 6). At the time of delivery, the resin-bonded fixed partial denture demonstrated excellent esthetics (Figure 7), which were further improved after the gingiva was allowed to heal for 2 weeks (Figure 8).

About the Author

Melissa Seibert, DMD, MS
Creator and Host
Dental Digest Podcast
US Air Force Dentist
Deputy AEGD Program Director
Langley Air Force Base
Hampton, Virginia

Clinical Instructor
Creighton University
School of Dentistry
Omaha, Nebraska

DISCLAIMER
The views expressed in this article are those of the author and do not reflect the official views or policy of the US Department of the Air Force, the US Department of Defense, or the US Government. No federal endorsement of a manufacturer is intended.