NexxZr (1 yr)
The purpose of this study was to determine the clinical performance of NexxZr full-contour zirconia restorations at one year after cementation. The restorations were fabricated by Apex Dental Milling, Ann Arbor, Michigan.
Clinical Evaluation Protocol:
At one year, 173 full-contour NexxZr crowns of 298 restorations that were placed were recalled. The restorations included 154 posterior single crowns; three, three-unit posterior bridges; one, eight-unit anterior bridge; and two implant crowns (Figure 1). The restorations were cemented with adhesive resin cement or self-adhesive resin cement.
Results at One Year
One hundred seventy-three NexxZr restorations were recalled over a three-month period. The distribution of recalled restorations is shown in Figure 2.
These restorations were evaluated in the following categories:
• Lack of sensitivity
• Resistance to fracture/chipping
• Resistance to marginal discoloration
• Wear resistance of zirconia and opposing dentition
<p>gt;Restorations were evaluated on a 1-5 rating scale: 1 = poor, 2 = fair, 3 = good, 4 = very good, 5 = excellent.
Lack of sensitivity
Lack of sensitivity was excellent (Figure 3). Seven patients experienced minor to moderate postoperative sensitivity, which subsided within 30 days of cementation.
The esthetics of the crowns cemented was very good to excellent (Figure 3). The majority of these crowns were for posterior teeth. Even the few anterior crowns had acceptable esthetics. Esthetics could be improved by making the zirconia exhibit more translucency.
Resistance to Fracture/Chipping
Resistance to fracture/chipping was excellent (Figure 3). One posterior crown chipped at the margin but did not require replacement.
Resistance to Marginal Discoloration
Resistance to marginal discoloration was excellent (Figure 3). Two posterior crowns exhibited slight staining (microleakage) at the margins.
Wear resistance was excellent (Figure 3). No evidence of wear was noted on the restorations or opposing teeth. NexxZr crowns were the treatment of choice for heavy bruxers.
Retention was excellent with none of the restorations debonding (Figure 3).