Objectives: Short sintering cycles enable high productivity and flexibility during processing zirconia dental restorations. In this study clinically relevant properties of a translucent zirconia material processed with standard sintering cycle and fast sintering cycle have been compared.
Methods: A translucent zirconia material (Lava Plus, 3M ESPE) was sintered (Lava Furnace 200) with standard sintering protocol 1450°C for 2h dwell time and a faster sintering cycle at 1500°C for 30 min dwell time . Biaxial fracture strength, contrast ratio and color match were analyzed for both sintering cycles. Initial strength was determined according ISO 6872 in a punch-on-three-balls test mode (discs thickness 1.2 mm, diameter 14mm) for n = 30 each group. Contrast ratio respectively opacity was investigated on 1.0 mm polished discs (n=6) with spectrophotometer (Color i7, X-Rite) in remission mode. Color match was investigated visually with three different operators at five different shaded (Lava Plus dying liquids) standardized anterior crowns (n = 3) and compared to each other in a light cabinet (D65, Spectralight lll, X-Rite). Data were analyzed with one-way ANOVA and Tukey's t-test (p<0.05).
Results: Total sintering time, mean fracture strength, contrast ratio and color match results are summarized in following table.
Standard sintering cylce
| Speed sintering cylce
| |
Sintering time without cooling (min)
| 225
| 90
|
Mean fracture strength (MPa)
| 1160±159
| 1127±135
|
Contrast ratio (%)
| 66.4±0.3
| 66.6±0.1
|
Color match
| No visible difference
| |
Conclusions: The speed sintering cycle allows a time reduction of more than 2h compared to the standard sintering cycle. No statistical significant difference in fracture strength, contrast ratio and color match was observed between groups sintered with standard and speed sintering cycle. The investigated speed sintering cycle has no impact on clinical relevant material properties of Lava Plus zirconia.