Stability of screw‐retention in two‐piece zirconia implants: An in vitro study

Abstract

ObjectivesTo compare the stability of a screw‐retained connection in a novel two‐piece zirconia implant to a conventional titanium‐based connection in an in vitro chewing simulation including artificial ageing.Material and methodsIncisor (I) and molar (M) shaped monolithic zirconia crowns were screw‐retained on either two‐piece zirconia (test) or two‐piece titanium (control) implants resulting in 4 groups of 8 samples (titanium implants with incisor‐shaped crowns (T‐I), titanium implants with molar‐shaped crowns (T‐M), zirconia implants with incisor‐shaped crowns (Z‐I) and zirconia implants with molar‐shaped crowns (Z‐M). These were subjected to artificial ageing by thermal cycling (TC: 2 × 3000 × 5°C/55°C cycles of 2 min) and mechanical loading (ML: 1.2 × 106 cycles of 50 N, f = 1 Hz). Surviving samples additionally underwent a fracture force test. Kaplan–Meier plots were drawn, and two‐way ANOVA was calculated taking anatomical localisation and material variables as factors.ResultsThe mean corresponding survival times were lower for T‐M (0.86 × 106 ± 0.31 × 106 cycles) and Z‐I (0.84 × 106 ± 0.21 × 106 cycles) compared to T‐I (1.14 × 106 ± 0.10 × 106 cycles) and Z‐M (1.20 × 106 ± 0.10 × 106 cycles). In one‐way ANOVAs for survival time dependent on either location or material, no statistically significant differences could be found (location: p = .31; material: p = .62) in one‐way ANOVAs. The interaction of location and material showed significant differences (F = 21.3, p < .001).ConclusionThe connection of the tested screw‐retained zirconia crowns in two‐piece zirconia implants is comparable to standard titanium implants in the specific in vitro testing.

Failure Load and Fatigue Behavior of Monolithic Translucent Zirconia, PICN and Rapid-Layer Posterior Single Crowns on Zirconia Implants

“…Dynamic loading and accelerated aging tests are a reliable method to provide essential information on limitations and lifetime predictions of ceramic restorations [ 29 ]. The applied fatigue protocol with 1.2 million cycles and simultaneous thermocycling corresponds to a clinical exposure time of 5 years and is a well-accepted method [ 27 , 28 , 30 , 31 , 32 ]. In the present study, all specimens survived exposure to an artificial oral environment with thermomechanical loading.…”

“…In vitro studies reported loading capacities for 3Y-TZP monolithic zirconia crowns (Vita YZ T) above 6000 N [ 30 ] on one-piece zirconia implants from the same manufacturer (vitaclinical) and between 4700 and 6350 N for 3Y-TZP monolithic implant crowns (Lava Plus) on one-piece zirconia implants (PURE Ceramic Implant, Straumann) [ 31 ] and 6310 N for 3Y-TZP monolithic zirconia crowns (Zerion LT) on two-piece zirconia implants (PURE two-piece implant, Straumann) [ 32 ]. Identical fatigue protocols simulating 5 years of clinical service was applied in the aforementioned studies to further stress the restorative-implant complex [ 30 , 31 , 32 ]. Different ranges in failure loads can be explained by different implant diameters (4.1 mm), two-piece design [ 32 ], abutment height (4.0 mm) [ 31 ] and choice of adhesive cements [ 30 ], as well as the crown design itself.…”

“…Identical fatigue protocols simulating 5 years of clinical service was applied in the aforementioned studies to further stress the restorative-implant complex [ 30 , 31 , 32 ]. Different ranges in failure loads can be explained by different implant diameters (4.1 mm), two-piece design [ 32 ], abutment height (4.0 mm) [ 31 ] and choice of adhesive cements [ 30 ], as well as the crown design itself. Furthermore, it must be noted that the small geometry of the one-piece implant abutment results in an increased wall thickness of the restoration and, consequently, leads to higher failure loads compared to restorations based on individually designed or prefabricated abutments [ 30 ].…”

Thermal effects of various drill materials during implant site preparation—Ceramic vs. stainless steel drills: A comparative in vitro study in a standardised bovine bone model

“…Although long‐term results for zirconia implants are still missing and elevated heat generation was reported in vitro during implant insertion with zirconia implants when compared to titanium implants (Zipprich et al., 2019), promising clinical data investigating the outcome of one‐piece zirconia implants after an observation period of 5 years have been recently obtained (Balmer et al., 2020). Newly developed two‐piece zirconia implants, which are supposed to overcome problems caused by challenging abutment angulations (Wenz et al., 2008), showed a similar screw‐retained stability in vitro (artificial ageing process) when compared to a conventional titanium‐based connection (Joos et al., 2020).…”

Comparative finite element analysis of mandibular posterior single zirconia and titanium implants: a 3-dimensional finite element analysis

“…In most clinically commercialized zirconia implant systems, one-piece implants are preferred over two-piece ones. 13 14 In some studies, one-piece zirconia implants showed good tissue response and a satisfactory degree of biocompatibility. 15 16 17 In 3-year follow-up studies on the success and survival of one-piece zirconia implants, survival rates ranged from 97.5% to 98.5%, which are almost identical to those of titanium implants.…”