Effects of taper and space settings of telescopic Ce-TZP/A crowns on retentive force and settling

Abstract

The aim of this study was to investigate the effect of the taper and space setting of using Ce-TZP/A on retentive force and secondary crown settling. The taper were 2°, 4°, and 6°, and the space settings were 0 and 10 μm. The applied loads were 50 and 100 N. The taper had a significant effect on retentive force and settling at both loads (p<0.05). The space settings did not have a significant effect on retentive force or settling at either load (p<0.05). The taper of the telescopic crowns and the load affected the retentive force and the settling.

Influence of the number of insertions and removals of telescopic zirconia/alumina crowns on retentive force and settling

“…According to Körber's equation 14) , that result suggests that the taper of telescopic crowns using Ce-TZP/Al 2O3 should be smaller than that adopted when using dental alloys. In a previous study 5) , retentive force did not develop with a 6º taper but was stable at tapers of 2º and 4º. Therefore, 2º and 4º were adopted in the present study.…”

“…The retentive force of telescopic crowns is influenced by many factors, including taper and the load applied to the secondary crown [10][11][12] . In a previous study, it was reported that the initial retentive force of telescopic crowns using Ce-TZP/Al 2O3 was also influenced by both taper and load 5) . In clinical practice, telescopic crowns that have become likely to get dislodged are often encountered.…”

“…Figure 4 depicts the measurement of retentive forces. Previously described methods utilizing microfocus X-ray computed tomography (SMX-130CT, Shimadzu) and 3D volume rendering software (VG Studio Max 1.2, Volume Graphics, Heidelberg, Germany) 5) were used to assess settling. Measurements were performed after every 2,500 insertion and removal cycles.…”

“…This is thought to be due to a "wedge effect" caused by settling of the secondary crown. In a previous study investigating telescopic crowns using Ce-TZP/Al 2O3, initial retentive force and settling were influenced by both taper and load 5) . However, while suitable retentive force must be maintained over an extended period for successful clinical use, it is unclear how retentive force and secondary crown settling change after repeated crown insertion and removal.…”

“…With conventional telescopic crowns that use dental alloys, an experienced dental technician must check that the axis surfaces of the primary and secondary crowns are tightly fitted and adjust the retentive force accordingly. However, a previous study has shown that telescopic crowns using zirconia can be manufactured using a CAD/CAM system, and a stable retentive force can be applied easily 5) . It is thought that using a CAD/ CAM system to manufacture telescopic crowns may improve the dental technician's labor efficiency and reduce technical errors.…”