IADR Abstract Archives
Retentive strength of zircona crowns to one-piece zirconia implants with reduced abutment height
Objectives: While the regular abutment height of the implants under examination is 5mm, some clinical situations raise the need for shorter abutments. This in-vitro study was conducted to test the retentive strength of CAD/CAM-made zirconia crowns luted to the abutment portion of a one-piece zirconia implant. A special mounting device for the crown retention test was developed.
Methods: The mounting device (Ulm University, GER) for a universal testing machine (Z010, Zwick/Roell, GER) encased the crowns, which were constructed with an enlarged marginal thickness. Two series of 10 implants (Z-Lock3 Evo SLM, Z-Systems, CH) with either 4mm or 5mm abutment height were tested. Twenty monolithic crowns were CAD/CAM-made of zirconia (Joachim Maier Dental Design, Oraldesign Center Bodensee, GER) and luted with a dual cure resin cement (Panavia V5, Kuraray Europe, GER). The crown implant complex was pulled apart at a speed of 1mm/min. The maximum force [N] at the time of debonding was recorded.
Results: The 4mm and 5mm abutments debonded at a mean force of 91N (SD 24.6; minimum 53.8N; maximum 137N) and 104.1N (SD 60.5; minimum 46.9N; maximum 257N), respectively. The one-way analysis of variance (IBM SPSS statistics 24, USA) revealed no statistically significant differences between the two groups (p=0.426).
Conclusions: The avoidance of shearing stress during the dislodgement of crowns is an important factor for comparability of different study results, which was the rational for the construction of the mounting device.
Results cannot easily be compared with other studies in the field as the total surface area of the abutments influences the measured maximum load at decementation.
Based on clinical experience with 5mm abutments showing sufficient crown retention and within the limitations of this in-vitro study, 4mm abutment implants could be an option for cases with limited vertical space.
Methods: The mounting device (Ulm University, GER) for a universal testing machine (Z010, Zwick/Roell, GER) encased the crowns, which were constructed with an enlarged marginal thickness. Two series of 10 implants (Z-Lock3 Evo SLM, Z-Systems, CH) with either 4mm or 5mm abutment height were tested. Twenty monolithic crowns were CAD/CAM-made of zirconia (Joachim Maier Dental Design, Oraldesign Center Bodensee, GER) and luted with a dual cure resin cement (Panavia V5, Kuraray Europe, GER). The crown implant complex was pulled apart at a speed of 1mm/min. The maximum force [N] at the time of debonding was recorded.
Results: The 4mm and 5mm abutments debonded at a mean force of 91N (SD 24.6; minimum 53.8N; maximum 137N) and 104.1N (SD 60.5; minimum 46.9N; maximum 257N), respectively. The one-way analysis of variance (IBM SPSS statistics 24, USA) revealed no statistically significant differences between the two groups (p=0.426).
Conclusions: The avoidance of shearing stress during the dislodgement of crowns is an important factor for comparability of different study results, which was the rational for the construction of the mounting device.
Results cannot easily be compared with other studies in the field as the total surface area of the abutments influences the measured maximum load at decementation.
Based on clinical experience with 5mm abutments showing sufficient crown retention and within the limitations of this in-vitro study, 4mm abutment implants could be an option for cases with limited vertical space.
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