J Dent Rehabil Appl Sci.  2020 Jun;36(2):95-103. 10.14368/jdras.2020.36.2.95.

Joint stability of internal conical connection abutments with or without hexagon indexes: an in vitro study

  • 1Department of Dentistry, Gangneung Asan Hospital, University of Ulsan, College of Medicine, Gangneung, Republic of Korea
  • 2Department of Prosthodontics and Research Institute of Oral Science, Gangneung-Wonju National University, Gangneung, Republic of Korea


The purpose of this study was to compare the axial displacement of the hexagonal and conical abutment in internal conical connection implant after screw tightening and cyclic loading.
Materials and Methods
Internal conical connection implants were divided into two groups (n = 10): group HEX, hexagonal abutment; and group CON, conical 2-piece abutments. The axial displacement and removal torque values were measured after 30 Ncm torque tightening and 250N loading test of 100,000 cycles. The Student t test with 5% significance level was used to evaluate the data.
HEX group demonstrated significantly higher axial displacement values after 30 Ncm tightening in comparison to the CON group (P < 0.05). No significant difference was found in axial displacement after cyclic loading (P = 0.052). Removal torque loss before and after the cyclic loading both revealed no significant difference between groups (P = 0.057 and P = 0.138). Removal torque value decreased after cyclic loading in both groups (P < 0.05).
Overall, both abutment with or without hexagon index presented similar biomechanical performance except HEX group demonstrated significantly more axial displacement after applying tightening torque.


morse taper dental implant-abutment interface; dental abutment; hexagon index; axial displacement; removal torque value
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