Fracture load of different crown systems on zirconia implant abutments

Objectives

The purpose of this study was to evaluate the fracture load of single zirconia abutment restorations using different veneering techniques and materials.

Materials and methods

The abutment restorations were divided into 6 groups with 20 samples each: test abutments (control group A), lithium disilicate ceramic crowns bonded on incisor abutments (group B), leucite ceramic crowns bonded on incisor abutments (group C), premolar abutments directly veneered with a fluor apatite ceramic (group D (layered) and group E (pressed)) and premolar abutments bonded with lithium disilicate ceramic crowns (group F). The fracture load of the restorations was evaluated using a universal testing machine. Half of each group was artificially aged (chewing simulation and thermocycling) before evaluating the fracture load with the exception of the test abutments.

Results

The fracture load of the test abutments was 705 ± 43 N. Incisor abutments bonded with lithium disilicate or leucite ceramic crowns (groups B and C) showed fracture loads of about 580 N. Premolar restorations directly veneered with fluor apatite ceramic (groups D and E) showed fracture loads of about 850 N. Premolar restorations bonded with lithium disilicate ceramic crowns (group F) showed fracture loads of about 1850 N. The artificial ageing showed no significant influence on the strength of the examined restorations.

Significance

All ceramic crowns made of lithium disilicate glass-ceramic, adhesively bonded to premolar abutments showed the highest fracture loads in this study. However, all tested groups can withstand physiological bite forces.     

Early bacterial colonization and soft tissue health around zirconia and titanium abutments: an in vivo study in man

Aim: To compare the early bacterial colonization and soft tissue health of mucosa adjacent to zirconia (ZrO₂) and titanium (Ti) abutment surfaces in vivo. Materials and methods: Twenty edentulous subjects received two endosseous mandibular implants. The implants were fitted with either a ZrO₂ or a Ti abutment (non‐submerged implant placement, within‐subject comparison, left‐right randomization). Sulcular bacterial sampling and the assessment of probing pocket depth, recession and bleeding on probing were performed at 2 weeks and 3 months post‐surgery. Wilcoxon matched‐pairs, sign‐rank tests were applied to test differences in the counts of seven marker bacteria and the clinical parameters that were associated with the ZrO₂ and Ti abutments, at the two observation time points. Results: ZrO₂ and Ti abutments harboured similar counts of Aggregatibacter actinomycetemcomitans, Porphyromonas gingivalis, Prevotella intermedia, Tannerella forsythia, Peptostreptococcus micros, Fusobacterium nucleatum and Treponema denticola at 2 weeks and 3 months. Healthy clinical conditions were seen around both ZrO₂ and Ti abutments at all times, without significant differences in most clinical parameters of peri‐implant soft tissue health. Mean probing depths around Ti abutments were slightly deeper than around ZrO₂ abutments after 3 months (2.2 SD 0.8 mm vs. 1.7 SD 0.7 mm, P=0.03). Conclusions: No difference in health of the soft tissues adjacent to ZrO₂ and Ti abutment surfaces or in early bacterial colonization could be demonstrated, although somewhat shallower probing depths were observed around ZrO₂ abutments after 3 month. To cite this article:
van Brakel R, Cune MS, van Winkelhoff AJ, de Putter C, Verhoeven JW, van der Reijden W. Early bacterial colonization and soft tissue health around zirconia and titanium abutments: an in vivo study in man
Clin. Oral Impl. Res. 22 , 2011; 571–577
doi: 10.1111/j.1600‐0501.2010.02005.x     

Fracture force of tooth-tooth- and implant-tooth-supported all-ceramic fixed partial dentures using titanium vs. customised zirconia implant abutments

Objectives: Tooth‐coloured customised implant abutments and full ceramic supraconstructions thereon can be made of zirconia by computer‐aided manufacturing (CAM). The aim of this study was to examine the potential limits of zirconia three‐unit fixed partial dentures made on customised zirconia implant abutments in implant‐tooth supported cases. Material and methods: Rigidly mounted implants (XiVE‐S diameter 3.8 mm; length 11 mm; Friadent, Germany) were placed in PMMA‐moulds pairwise with human molars at a distance of 10 mm in groups #1 and #2. Control group #3 consisted of two molars without implant involvement. Beforehand all molar roots were covered with polyether (Impregum: 3 M Espe, Germany) to simulate periodontal mobility. The abutments in #1 were individually fabricated from CerconBase and luted on experimental titanium bases (both: DeguDent, Germany). In #2, industrially prefabricated titanium abutments (Friadent) were used. All molar teeth were provided with a circumferential chamfer preparation. Three‐unit fixed partial dentures were fabricated from CerconBase/CerconKiss in a CAM‐process (Material/devices: DeguDent) for all test groups (n=8/group). All fixed partial dentures were cemented with RelyXUnicem (3 M Espe), thermomechanically loaded (TCML=1.2 × 10⁶× 50 N; 6000 × 5°/55°) and fracture tested in a Universal Test Machine (UTM 1446: Zwick, Germany). Results: None of the dentures failed during TCML, and the Cercon abutments showed no damage either to the bonding surface to titanium or to the ceramic itself. Two fixation screws in group #1 broke towards the end of TCML. Fracture test result (Median and 25‐/75‐Percentiles) were: #1 1190 (1046/2008), #2 991 (832/1402), #3 1331 (1224/1428). Conclusions: All restoration alternatives showed sufficient fracture resistance for posterior regions.     

Randomized controlled clinical trial of customized zirconia and titanium implant abutments for canine and posterior single-tooth implant reconstructions: preliminary results at 1 year of function

Objectives: The aim of this study was to test whether or not customized zirconia abutments exhibit the same survival rates in canine and posterior regions as titanium abutments, and to compare the esthetic result of the two abutment types. Material and methods: Twenty‐two patients with 40 implants in posterior regions were included and the implant sites were randomly assigned to 20 customized zirconia and 20 customized titanium abutments. All‐ceramic (AC) and metal–ceramic (MC) crowns were fabricated. In all except two cases, the crowns were cemented on the abutments using resin or glass‐ionomer cements. Two zirconia reconstructions were screw retained. At baseline, 6 and 12 months, the reconstructions were examined for technical and biological problems. Probing pocket depth (PPD), plaque (Pl) and bleeding on probing (BOP) were assessed and compared with natural control teeth. Furthermore, the difference of color (ΔE) of the peri‐implant mucosa and the gingiva of control teeth was evaluated by means of a spectrophotometer (Spectroshade). The data were analyzed with Student's unpaired t‐test, ANOVA and regression analyses. Results: Twenty patients with 19 zirconia and 12 titanium abutments were examined at a mean follow‐up of 12.6±2.7 months. The survival rate for reconstructions and abutments was 100%. No technical or biological problems were found at the test and control sites. Two chippings (16.7%) occurred at crowns supported by titanium abutments. No difference was found regarding PPD (meanPPD_ZrO2 3.4±0.7 mm, mPPD_Ti 3.3±0.6 mm), Pl (mPl_ZrO2 0.2±0.3, mPl_Ti 0.1±1.8) and BOP (mBOP_ZrO2 60±30%, mBOP_Ti 30±40%) between the two groups. Both crowns on zirconia and titanium abutments induced a similar amount of discoloration of the soft tissue compared with the gingiva at natural teeth (ΔE_ZrO2 8.1±3.9, ΔE_Ti 7.8±4.3). Conclusions: At 1 year, zirconia abutments exhibited the same survival and a similar esthetic outcome as titanium abutments.     

Load to failure of different zirconia implant abutments with titanium components

Statement of problem

Abutments with a zirconia superstructure and a titanium insert have recently become popular. Although they have been tested under static load, their performance under simulated mastication is not well known.

Randomized-controlled clinical trial of customized zirconia and titanium implant abutments for single-tooth implants in canine and posterior regions: 3-year results

Objectives: The aim was to test whether or not zirconia abutments exhibit the same survival and technical/biological outcome as titanium abutments. Material and methods: Twenty‐two patients receiving 40 single‐tooth implants in canine and posterior regions were included. The implant sites were randomly assigned to 20 zirconia and 20 titanium abutments. All‐ceramic and metal–ceramic crowns were fabricated. At baseline, 6, 12 and 36 months, the reconstructions were examined for technical and biological problems. Probing pocket depth (PPD), plaque control record (PCR) and bleeding on probing (BOP) were assessed at abutments (test) and analogous contralateral teeth (control). Standardized radiographs of the implants were made and the bone level (BL) was measured referring to the implant shoulder on mesial (mBL) and distal sides (dBL). The difference of color (ΔE) of the peri‐implant mucosa and the gingiva of control teeth was assessed with a spectrophotometer. The data were statistically analyzed with Mann–Whitney Rank and Student's unpaired t‐tests. Results: Eighteen patients with 18 zirconia and 10 titanium abutments were examined at a mean follow‐up of 36 months (range 31.5–53.3 months). No fracture of an abutment or loss of a reconstruction was found. Hence, both exhibited 100% survival. At two metal–ceramic crowns supported by titanium abutments chipping of the veneering ceramic occurred. No difference of the biological outcome of zirconia and titanium abutments was observed: PPD ( 3.2 ± 1 mm, mPPD_Ti 3.4 ± 0.5 mm), PCR ( 0.1 ± 0.2, mPCR_Ti 0.1 ± 0.2) and BOP ( 0.4 ± 0.4, mBOP_Ti 0.2 ± 0.3). Furthermore, the BL was similar at implants supporting zirconia and titanium abutments ( 1.7 ± 1, 1.6 ± 1; mBL_Ti 2 ± 1, dBL_Ti 2.1 ± 1). Both, zirconia and titanium abutments induced a similar amount of discoloration of the mucosa compared with the gingiva at natural teeth ( 9.3 ± 3.8, ΔE_Ti 6.8 ± 3.8). Conclusions: At 3 years, zirconia and titanium abutments exhibited same survival and technical, biological and esthetical outcomes.     

种植体数目对支持组织应力分布的影响

目的：了解不同数目骨融合种植体所支持的下颌覆盖义齿,在承受牙合力时其支持组织——牙槽骨及种植体周围的应力分布状况,探讨种植体数目变化对支持组织应力分布的影响规律。方法：应用三维光弹应力冻结切片法,对分别由２、４、６颗种植体所支持的下颌覆盖义齿,在垂直载荷下的应力状况进行冻结,并在相应部位切片观察,以了解在几种不同情况下的覆盖义齿的内部应力分布规律。结果：在不同数目种植体为基牙的覆盖义齿中,牙槽骨及种植体骨界面的应力值随着种植体数目的增加而减少,两者呈负相关关系。结论：在条件允许的情况下,应尽可能多地选用种植基牙。     

Fracture behavior of straight or angulated zirconia implant abutments supporting anterior single crowns

The aim of the study was to evaluate the influence of artificial aging on the fracture behavior of straight and angulated zirconia implant abutments (ZirDesign?; Astra Tech, Mölndal, Sweden) supporting anterior single crowns (SCs). Four different test groups (n?=?8) representing anterior SCs were prepared. Groups 1 and 2 simulated a clinical situation with an ideal implant position (left central incisor) from a prosthetic point of view, which allows for the use of a straight, prefabricated zirconia abutment. Groups 3 and 4 simulated a situation with a compromised implant position, requiring an angulated (20°) abutment. OsseoSpeed? implants (Astra Tech) 4.5 mm in diameter and 13 mm in length were used to support the abutments. The SCs (chromium cobalt alloy) were cemented with glass ionomer cement. Groups 2 and 4 were thermomechanically loaded (TCML?=?1.2?×?10⁶; 10,000?×?5°/55°) and subjected to static loading until failure. Statistical analysis of force data at the fracture site was performed using nonparametric tests. All samples tested survived TCML. Artificial aging did not lead to a significant decrease in load-bearing capacity in either the groups with straight abutments or the groups with angulated abutments. The restorations that utilized angulated abutments exhibited higher fracture loads than the restorations with straight abutments (group 1, 280.25?±?30.45 N; group 2, 268.88?±?38.00 N; group 3, 355.00?±?24.71 N; group 4, 320.71?±?78.08 N). This difference in load-bearing performance between straight and angulated abutments was statistically significant (p?=?0.000) only when no artificial aging was employed. The vast majority of the abutments fractured below the implant shoulder.     

Fatigue fracture resistance of titanium and chairside CAD-CAM zirconia implant abutments supporting zirconia crowns: An in vitro comparative and finite element analysis study

Statement of problemZirconia abutments with a titanium base are promising candidates to substitute for titanium abutments based on clinical studies reporting good short-term survival rates. However, information on the long-term performance of zirconia abutments supporting ceramic crowns is scarce.PurposeThis in vitro comparative and finite element analysis study compared the fatigue life performance of ceramic computer-aided design and computer-aided manufacturing (CAD-CAM) monolithic restorations and zirconia abutments fabricated with a chairside workflow connected to a titanium interface versus titanium abutments.Material and methodsTwenty-two internal connection implants were divided into 2 groups, one with a zirconia abutment and monolithic ceramic zirconia crown (ZZ) and the other with a titanium abutment and zirconia crown (TiZ). They were subjected to a fatigue test to determine the fatigue limit and fatigue performance of each group as per International Organization for Standardization (ISO) 14801. Microstructural analysis of the fracture surfaces was conducted by using a scanning electron microscope (SEM). Simulations of the in vitro study were also conducted by means of finite element analysis (FEA) to assess the stress distribution over the different parts of the restoration.ResultsThe fatigue limit was 250 N for the TiZ group and 325 N for the ZZ group. In both groups, the screw was the part most susceptible to fatigue and was where the failure initiated. In the zirconia abutment models, the stress on the screw was reduced.ConclusionsChairside CAD-CAM zirconia abutments with a titanium base supporting zirconia crowns had higher fatigue fracture resistance compared with that of titanium abutments.     

Influence of preparation depths on the fracture load of customized zirconia abutments with titanium insert

PURPOSE

This study evaluated the fracture load of customized zirconia abutments with titanium insert according to preparation depths, with or without 5-year artificial aging.

MATERIALS AND METHODS

Thirty-six identical lithium disilicate crowns (IPS e.max press) were fabricated to replace a maxillary right central incisor and cemented to the customized zirconia abutment with titanium insert on a 4.5×10 mm titanium fixture. Abutments were fabricated with 3 preparation depths (0.5 mm, 0.7 mm, and 0.9 mm). Half of the samples were then processed using thermocycling (temperature: 5-55℃, dwelling time: 120s) and chewing simulation (1,200,000 cycles, 49 N load). All specimens were classified into 6 groups depending on the preparation depth and artificial aging (non-artificial aging groups: N5, N7, N9; artificial aging groups: A5, A7, A9). Static load was applied at 135 degrees to the implant axis in a universal testing machine. Statistical analyses of the results were performed using 1-way ANOVA, 2-way ANOVA, independent t-test and multiple linear regression.

RESULTS

The fracture loads were 539.28 ± 63.11 N (N5), 406.56 ± 28.94 N (N7), 366.66 ± 30.19 N (N9), 392.61 ± 50.57 N (A5), 317.94 ± 30.05 N (A7), and 292.74 ± 37.15 N (A9). The fracture load of group N5 was significantly higher than those of group N7 and N9 (P<.017). Consequently, the fracture load of group A5 was also significantly higher than those of group A7 and A9 (P<.05). After artificial aging, the fracture load was significantly decreased in all groups with various preparation depths (P<.05).

CONCLUSION

The fracture load of a single anterior implant restored with lithium disilicate crown on zirconia abutment with titanium insert differed depending on the preparation depths. After 5-year artificial aging, the fracture loads of all preparation groups decreased significantly.     

种植体直径和长度对支持组织应力分布的影响

目的：观察种植体直径、长度变化时由种植体支持的下颌种植覆盖义齿,在牙合力作用下其支持组织——牙槽骨及种植体周围的应力分布状况,探讨种植体长度和直径变化对支持组织应力分布的影响规律。方法：用三维光弹应力冻结切片法,对４种不同长度,３种不同直径的种植体支持的种植覆盖义齿,在牙合力作用下的应力状况进行应力冻结,并在相应部位切片观察,以了解各种状况下其支持组织的应力分布状况。结果：种植体长度变化对种植体周围骨界面及牙槽骨应力的大小有较大的影响,两者呈负相关关系;而在临床常用的几种直径种植体中,直径变化对种植体周围骨界面及牙槽骨应力的影响不大。结论：在种植义齿设计时,应着重考虑种植体长度变化对种植体周围骨界面及牙槽骨应力的影响,种植体直径变化可不作考虑。