Influence of bone insertion level of the implant on the fracture strength of different connection designs: an in vitro study.

Objective: The aim of the present in vitro study was to assess resistance to static fatigue of implants with different connections at various insertion levels.

Materials And Methods: Sixty implants and abutments were used with the smallest diameter of each model. Four groups (n = 15) were created on the basis of the implant design and connection: cylindrical external hexagon Ø3.30 mm (group 1), cylindrical internal hexagon Ø3.30 mm (group 2), conical internal hexagon Ø3.50 mm (group 3), and conical Morse taper Ø3.50 mm (group 4). Three insertion levels in resin were tested, 0 mm at the platform level (l1), 3 mm (l2), and 5 mm (l3) above the platform of the resin. All groups were subjected to quasi-static loading at 30° to the implant axis in a universal machine.

Results: The mean fracture strengths for group 1 were 1,991 N (l1), 1,020 N (l2), and 767 N (l3); for group 2: 2,119 N (l1), 1,034 N (l2), and 903 N (l3); for group 3: 2,373 N (l1), 1,407 N (l2), and 929 N (l3); and for group 4: 1,710 N (l1), 1,680 N (l2), and 1,182 N (l3).

Conclusions: Resistance to loading decreases significantly with the loss of insertion, and the connection design between the implants and abutments can change the performance and resistance of the system.

Clinical Relevance: When implants are used in areas where there is a possibility of bone loss, the selection of a connection type is an important consideration for the longevity of the system.