[Impact of ultrasonic scaling on abutment screw torque in implant restorations]

To investigate the effect of ultrasonic scaling on the torque of implant prosthetic abutment screws and to compare the differences in torque influence between ultrasonic tips of two different materials.

In this study, a total of 22 implants were selected, and two distinct primary torque values (PTV) 15 N·cm and 35 N·cm were applied to the temporary and definitive restorations mounted on each implant, respectively. Subsequently, ultrasonic scaling was performed for one minute using either a traditional metal scaling tip (metal tip) or a carbon fiber scaling tip (fiber tip), followed by measurement of the removal torque value (RTV). Paired t-tests were used to compare the torque changes in the same prosthesis before and after ultrasonic scaling (significance level α=0.05, two-tailed) to evaluate the effect of ultrasonic scaling on torque. Under the same PTV condition, paired t-tests were also conducted to compare the RTV after scaling with different tips to analyze the influence of the tip material on RTV.

The RTVs in all the four groups were significantly lower than the corresponding PTVs after ultrasonic scaling (P < 0.05). At a PTV of 15 N·cm, the RTV of the fiber tip group was (14.1±1.27) N·cm, significantly higher than that of the metal tip group (12.3±1.56) N·cm, (P < 0.05). At a PTV of 35 N·cm, the RTV of the fiber tip group was (34.0±1.29) N·cm, while that of the metal tip group was (33.1±1.70) N·cm, with no statistically significant difference between the two groups (P>0.05).

Ultrasonic scaling can lead to significant attenuation of torque in implant prosthetic abutment screws. Under a lower primary torque condition (15 N·cm), carbon fiber scaling tips significantly reduce torque attenuation compared with traditional metal scaling tips. However, under a higher primary torque condition (35 N·cm), no significant difference in the effect on screw torque was observed between the two tip types. These findings suggest that screw torque should be checked after clinical peri-implant maintenance to reduce the risk of screw loosening.