3. Effects of cyclic loading on loss of abutment screw torque of angled screw channel single implant crowns on narrow diameter implants.
Bhumpattarachai S, Kan JYK, Goodacre CJ, et al. J Prosthet Dent. 2023 7:S0022-3913(23)00507-3.
This in vitro study by Prof. Bhumpattarachai and colleagues from California compares the loss of abutment screw torque after thermocycling and the cyclic loading of angulated screw channels (ASCs) from three different companies connected to narrow-diameter implants. A total of 40 narrow-diameter NobelReplace® Conical Connection 3.5×11.5 mm were mounted in acrylic resin blocks, divided into four groups, and restored with:
- Screw-retained zirconia crowns fabricated on Nobel Biocare angulated screw channel (ASC) at 0°
- Screw-retained zirconia crowns fabricated on Nobel Biocare ASCs at 25°
- 20° Atlantis Custom Base Solution with angulated screw access from Dentsply Sirona
- 20° Dynamic TiBase® from Dynamic Abutment Solutions
The corresponding titanium base insert and screw were tightened to the manufacturer's recommended torque with a digital torque gauge. After each specimen underwent thermocycling and then cyclic loading at 0 to 100 N at 10 Hz for 1 million cycles to simulate one year of functional loading, the percentage screw torque loss among all groups after cyclic loading was significantly different (P<.001).
– The percentage of torque loss in the Atlantis Custom Base Solution group was 51.4%, and significantly higher than Nobel Biocare ASCs with 0° or 25° (22.2% and 29.2%, P=.010).
– No significant difference was found in the percentage of torque loss among other groups (P>0.05). The NB-25 group demonstrated the lowest percentage torque loss. Torgue loss in Dynamic TiBase was 44.9%.
This study suggests crowns with an angled screw channel on a narrow-diameter implant with original components may perform better than those with non-original components. A high percentage of abutment screw torque loss was observed with non-original parts, which may increase the need for periodic recall of the restoration to check for loosening.
Check out the full manuscript in PubMed.