Fracture resistance of soft tissue level implants after cyclic loading and external modification.

Area of Science:

• Dental Implantology
• Biomaterials Science
• Mechanical Engineering

Background:

• Exposed implant collars in the esthetic zone present a clinical challenge in implant dentistry.
• Preparation of the implant collar to accommodate restorative materials can compromise abutment/implant assembly strength.

Purpose of the Study:

• To evaluate the impact of preparing a 0.5-mm chamfer finish line on implant collars at varying apical depths on the failure load.
• To determine the mechanical consequences of implant collar modification for esthetic zone restorations.

Main Methods:

• Thirty solid abutments and 30 implants were tested in vitro at a 30-degree angle.
• Groups included an intact control (IN), 0.5-mm chamfer preparation 1 mm apical (P1), and 2 mm apical (P2) to the implant/abutment interface.
• Specimens underwent fatigue loading followed by load-to-failure testing, with mean fracture load (MFL) analyzed using ANOVA and Tukey tests.

Main Results:

• Significant differences in MFL were observed between the intact group and both preparation groups (P<.001).
• The intact group (IN) had a mean fracture load of 3825 N.
• Prepared groups P1 (2944 N) and P2 (2553 N) exhibited significantly lower mean fracture loads.

Conclusions:

• Implant collar preparation, even with a 0.5-mm chamfer, significantly decreases the mean load required to fracture the abutment/implant assembly.
• The extent of preparation influences the reduction in fracture strength, with deeper preparation leading to lower MFL.
• These findings highlight the mechanical trade-offs associated with esthetic implant collar management.