For patients missing an anterior tooth, the treatment options available include a dental implant, a removable partial denture, or a bridge. Some patients may not desire an implant due to the surgical nature, the limited bone available or the high cost. Removable partial dentures are relatively inexpensive but are undesirable for many patients due to the limited esthetics, trouble speaking and annoyance of an oral prosthesis. Traditional bridges use adjacent teeth as abutments and replace the missing tooth. However, these require the removal of 1-2 mm of tooth structure on adjacent teeth provide room for the porcelain of the bridge.
Decades ago, the option for a conservative bridge was primarily found in the Maryland bridge, which had two metal wings that were cemented or bonded on to two abutments. Though conservative, the Maryland Bridge did not enjoy a high reputation because of the high rate of debonding (falling off).
A systematic review published in 2017 in the British Dental Journal indicated that the five-year survival rate of the Maryland Bridge was around 83.6% and ten-year rate at 64.9%. Debonding of the restoration (78%) is the most common type of failure followed by porcelain fracture (13%). (Balasbramaniam, G.R. (2017-06-09). "Predictability of resin bonded bridges-a systematic review." British Dental Journal. 222 (11): 849-858. Found through wikipedia).
In the last several decades, the use of zirconia as a restorative material in dentistry has dramatically risen due to its toughness, resemblance in color to natural teeth, and affordability. Also, composite resin bonding agents (adhesive for dental fillings) have increased in strength and effectiveness. With these two advancements, the possibility of overcoming the some of the previous shortcomings with the Maryland Bridge is more of a reality.
The type of zirconia-wing bridge we are researching in this study has two wings which generally have three countersunk holes (meaning that the circumference of the outer portion of the hole is larger than the inner part of the hole). Composite resin (dental filling material) is placed in the holes as well as under and around the wings.
A retrospective study published in 2018 in the Australian Dental Journal indicated that Anterior Resin Bridges had a survival rate of 98% at 5 years and 95.1% at 12 years (onwards). A significant number of the prostheses were in place between 13 and 21 years. (M Abuzar, et al. "Longevity of anterior resin-bonded bridges: survival rates of two tooth preparation designs." Australian Dental Journal 2018; 63: 279-284). In this particular study, however, the clinicians used a more aggressive preparation design (2-3 grooves drilled into the teeth) than the preparations performed with the bridges at Roseman University, which only have one small hole drilled into the tooth.
In summary, the zirconia-wing bridge presents a desirable alternative to traditional options for missing anterior teeth. With the advancements in resin-bonding and zirconia, this study seeks to examine how these combined elements can be used in the zirconia-wing bridge to maximize durability and retention in clinical scenarios.
