Objective This study compared the marginal gap, internal fit, fracture strength, and mode of fracture of CAD/CAM provisional crowns with that of direct provisional crowns.Material and Methods An upper right first premolar phantom tooth was prepared for full ceramic crown following tooth preparation guidelines. The materials tested were: VITA CAD-Temp®, Polyetheretherketone “PEEK”, Telio CAD-Temp, and Protemp™4 (control group). The crowns were divided into four groups (n=10), Group1: VITA CAD-Temp®, Group 2: PEEK, Group 3: Telio CAD-Temp, and Group 4: Protemp™4. Each crown was investigated for marginal and internal fit, fracture strength, and mode of fracture. Statistical analysis was performed using GraphPad Prism software version 6.0.Results The average marginal gap was: VITA CAD-Temp® 60.61 (±9.99) µm, PEEK 46.75 (±8.26) µm, Telio CAD-Temp 56.10 (±5.65) µm, and Protemp™4 193.07(±35.96) µm (P<0.001). The average internal fit was: VITA CAD-Temp® 124.94 (±22.96) µm, PEEK 113.14 (±23.55) µm, Telio CAD-Temp 110.95 (±11.64) µm, and Protemp™4 143.48(±26.74) µm. The average fracture strength was: VITA CAD-Temp® 361.01 (±21.61) N, PEEK 802.23 (±111.29) N, Telio CAD-Temp 719.24 (±95.17) N, and Protemp™4 416.40 (±69.14) N. One-way ANOVA test showed a statistically significant difference for marginal gap, internal gap, and fracture strength between all groups (p<0.001). However, the mode of fracture showed no differences between the groups (p>0.05).Conclusions CAD/CAM fabricated provisional crowns demonstrated superior fit and better strength than direct provisional crowns.

The mechanical properties of temporary crowns are considered to be crucial in order to achieve successful definite restorations. This study compared marginal fit, internal fit, fracture strength and mode of fracture of CAD/CAM temporary crowns to direct chairside counterparts. An upper left first premolar Frasaco tooth was prepared for all-ceramic crown. The materials used for comparison were VITA CAD-Temp, ArtBlocTemp, PMMA DISK and Acrytemp (control group). The crowns were divided into four groups (n=10). Each crown was investigated for the above parameters. Statistical analysis was performed using SPSS v.20. The average marginal gap, internal gap and fracture strength showed statistically significant difference between groups (p<0.01). The fracture mode showed statistically non-significant difference (p>0.05) among experimental groups. The CAD/CAM temporary crowns demonstrated superior mechanical properties compared to direct handmade counterparts.

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