Objectives:
Evaluation of influence of internal-fit, taper and surface-conditioning to tensile resistance to dislodgement (TRD) of ZrO2-crowns on ZrO2-implant-abutments cemented with Telio CS Cem Implant and five different temporary, removable and definitive cements.
Methods:
Two sets of ZrO2-Crowns and ZrO2-implant-abutments were constructed via CAD/CAM and milled analogue Straumann Anatomic IPS e.max Abutment (taper 6°, abutment-height 4mm) with internal-fit 100μm (Set1) or 200μm (Set2). A third set was constructed with 40° taper, 4mm abutment-height and 100μm internal-fit (Set3).
Before cementation, surfaces of Set1 were either left untreated as milled or sandblasted (100μm Al2O3, 1bar), Set2 and Set3 were likewise sandblasted (each N=10).
Crowns were cemented (load 20N) using following cements in self-curing-mode: Telio CS Cem Implant (TCI), Systemp.link (SL), Ivoclar Vivadent; TempBond NE (TB), Kerr; Premier Implant (PI), Premier; Improv (IMP), Alvelogro; Implantlink semi (IS), Detax. After setting, samples were stored (>14h@37°C,<10%RH).
TRDs were determined with universal-testing-machine (Zwick-Roell, 1mm/min cross-head-speed).
Data was analyzed using two-way-ANOVA (Tukey's,p<0.05).
Results:
TRD [N] of crowns:
| TCI | SL | TB | IS | PI | IMP |
Set1, untreated | 33±13a;A | 23±10a;A | 148±64b;B | 44±18a;A | 47±38a;A | 107±50a;A |
Set1, sandblasted | 74±13a;A,B | 24±7a;A | 190±60c;C | 138±46b;B | 157±42b,c;C | 250±55d;B |
Set2 | 86±32a,b;B | 43±13a;B | 105±34b;B | 138±42b;B | 110±22b;B | 328±77c;B |
Set3 | 57±40a;A,B | 37±22a;A,B | 34±10a;A | 46±32a;A | 75±27a,b;A,B | 136±115a,b;A |
Small letters in rows and capital letters in columns indicate equal statistical groups.
Conclusions:
Cements exhibited the strongest influence on TRD-values (p<0.001,η2=0.351) followed by taper (p<0.001,η2=0.281) and surface-conditioning (p<0.001,η2=0.246). Surprisingly, the size of internal-fit had no significant influence on TRD-values (p=0.605,η2=0.001).
In detail, sandblasting didn't increase TRD-values of temporary-cements (SL, TB), but for all others. Flat taper lead to unchanged (SL, TCI) or lower TRD-values (all others). Bigger internal-fit lowered TRD-values for TB and PI, but not for all others.
Compared to earlier investigations with metal-crowns, TB lead to high TRD-values, potentially due to adhesive interactions with zirconia. TRD-values were also high for IMP and partially for PI and IS. The use of those four cements may negatively affect supra-construction-removal of ZrO2-crowns.
In contrast, TCI offers TRD-values providing both, good retention and the option of non-destructive removal of ZrO2-crowns, regardless of surface-treatment, taper or internal-fit.