Clinician-generated torque on abutment screws using different hand screwdrivers.
BACKGROUND
Many clinicians use hand screwdrivers to tighten prosthetic and abutment screws. The impact of the screwdriver type, the location of the implant, and the sex of the practitioner on the generated torque is not well understood.


OBJECTIVE
The purpose of this in vitro study was to compare the torque generated by different hand screwdrivers when used in the anterior and posterior regions and to evaluate the correlation between the applied torque and the sex and body mass index (BMI) of the practitioner.


METHODS
A mandibular typodont with anterior and posterior implants was mounted in a mannequin head. Fifty clinicians (6 prosthodontists, 8 graduate prosthodontic students, and 36 dental students) used their maximum force to tighten the abutment screws in the anterior and posterior regions, using 3 different hand screwdrivers, with handles of different shapes and sizes (small, medium, and large). The torque values generated were measured using torque meters connected to the implants. The generated torque, sex, age, height, and weight were also recorded for each clinician. A generalized linear model was used to find correlations between the different factors and the generated torque (α=.05).


RESULTS
Significant differences were observed among the applied torque values when different screwdrivers were used (P<.001). Higher torque values were generated in the anterior region than in the posterior region (P<.001). The interaction of the sex and BMI of the participants significantly affected the generated torque values (P=.044).


CONCLUSIONS
The type of screwdriver and location of the implant affected the generated torque. Torque values generated by the large screwdriver were higher than those of small and medium screwdrivers. Higher torque was applied in the anterior region.
Associate Professor, Dental Research Center, Department of Prosthodontics, Tehran University of Medical Sciences, Tehran, Iran.
Marzieh
M
Alikhasi
Assistant Professor, Department of Prosthodontics, Tehran University of Medical Sciences, Tehran, Iran.
Mahmoud
M
Kazemi
Assistant Professor, Department of Prosthodontics, Tehran University of Medical Sciences, Tehran, Iran.
Hamid
H
Jalali
Visiting Scholar, Division of Restorative Sciences and Prosthodontics, The Ohio State University College of Dentistry, Columbus, Ohio. Electronic address: shervin.hashemzadeh.89@gmail.com.
Shervin
S
Hashemzadeh
Dentist, Dental Research Center, School of Dentistry, Tehran University of Medical Sciences, Tehran, Iran.
Hamide
H
Dodangeh
Associate Professor, Division of Restorative Sciences and Prosthodontics, The Ohio State University College of Dentistry, Columbus, Ohio.
Burak
B
Yilmaz
D000044:Dental Abutments; D003758:Dental Implantation, Endosseous / Q000295:instrumentation* / Q000379:methods*; D003762:Dental Instruments; D019094:Dental Prosthesis, Implant-Supported; D003813:Dentistry; D005260:Female; D006801:Humans; D008297:Male; D008348:Manikins; D019415:Torque