Article

Wear of ceramic and antagonist-A systematic evaluation of influencing factors in vitro

R&D, Ivoclar-Vivadent, Schaan, Liechtenstein.
Dental Materials (Impact Factor: 3.77). 05/2008; 24(4):433-49. DOI: 10.1016/j.dental.2007.06.016
Source: PubMed

ABSTRACT

(1) To systematically review the existing literature on in vitro assessments of antagonist wear of ceramic materials; (2) To systematically evaluate possible influencing factors on material and antagonist wear of ceramic specimens.
The database MEDLINE was searched with the terms "enamel," "wear" and "antagonist." The selected studies were analyzed with regard to wear parameters, type of antagonist and outcome. In the laboratory study, three ceramic materials were selected with different compositions and physical properties: IPS d.SIGN low-fusing metal ceramic, IPS Empress leucite ceramic, e.max Press lithium disilicate ceramic. These materials were subjected to the Ivoclar wear method (Willytec chewing simulator, 120,000cycles, 5kg weight) by systematically modifying the following variables which resulted in 36 tests with 8 specimens in each group: (1) configuration (flat, crown specimen), (2) surface treatment (polish, glaze), (3) type of antagonist (ceramic, two types of enamel stylus). Furthermore, the enamel styluses were cut to measure the enamel thickness and cusp width. Wear of both the material and the antagonist was quantified by scanning plaster replicas of the specimens with a laser scanner (etkon es1) and matching baseline and follow-up data with the Match 3D software (Willytec). The data were log-transformed to stabilize the variance and achieve near normality. To test the influence of specific test parameters, a four-way ANOVA with post hoc tests and Bonferroni correction was applied.
The systematic review revealed 20 in vitro studies in which a material and the antagonist wear of the same material was examined. However, the results were inconsistent mainly due to the fact that the test parameters differed widely. Most studies used prepared enamel from extracted molars as the antagonist and flat polished ceramic specimens. The test chamber was filled with water and some sort of sliding movement was integrated in the wear generating process. However, there was a huge variation in relation to the applied force, the used force actuator, the number of cycles, and the frequency of cycles per time as well as the number of specimens. The results of the systematic laboratory tests revealed that the following factors strongly influence the wear: configuration (more material wear of flat versus crown specimens), surface treatment (more antagonist wear of glazed versus polished specimens), the antagonist system (more material wear and less antagonist wear for ceramic stylus versus enamel stylus), and enamel thickness (less wear for thicker enamel). Material wear was not very much different between the materials. However, e.max Press generally caused more antagonist wear than the other two materials, which were quite similar. However, the main influencing factors did not yield consistent results for all the subgroups and there was a huge variability of results within the subgroups especially in those groups that used enamel as antagonist.
As far as consistency and correlation with clinical studies is concerned, the set-up that consists of unprepared enamel of molar cusps against glazed crowns seems to be the most appropriate method to evaluate a ceramic material with regard to antagonist wear. However, due to the high variability of results large sample sizes are necessary to differentiate between materials, which calls the whole in vitro approach into question.

Download full-text

Full-text

Available from: Siegward Heintze, May 06, 2015
    • "Admittedly, in the Table 3. Results of the single crown evaluations according to the modified USPHS criteria (Table 2) at the delivery of the final restoration and the follow-upsmajority of cases even a major roughness can be polished and can therefore be considered reversible. However, until the appointment at which the roughness is detected and removed, opposing enamel or restorative materials might be subject to an increased wear (Heintze et al. 2008;Saiki et al. 2014). Furthermore, surface flaws are known to be liable for an decrease in strength of ceramic materials (Rashid 2014). "
    [Show abstract] [Hide abstract]
    ABSTRACT: Objective: To determine the survival and success rate of CAD/CAM-fabricated monolithic lithium-disilicate crowns supported by zirconia oral implants after 3 years. Material and methods: Twenty-four patients in need of a single tooth replacement received a zirconia implant and were finally restored with 24 single crowns (SCs) ground out of pre-crystallized lithium-disilicate blanks. The restorations were adhesively cemented and evaluated using modified United States Public Health Service (USPHS) criteria. In case of clinically relevant defects that could be repaired to an acceptable level, SCs were regarded as surviving. Restorations with minor chippings, a small-area roughness (ø <2 mm), slightly soundable marginal gaps, minimal under-/overcontours, and tolerable color deviations (<1 Vitashade) were regarded as success. The Kaplan-Meier method and log-rank tests were used for the success/survival analyses and the calculation of potential group differences (gender, location, jaw). Additionally, several patient-reported outcome measures (PROMs) were evaluated. Results: Twenty-three patients were seen 3 years after implant placement. No SC had to be replaced, resulting in 100% survival. No chippings were observed. As one SC showed a major occlusal roughness, the Kaplan-Meier success rate after a mean observation period of 31 months was 95.7%. No group differences could be calculated. Compared with the pre-treatment surveys, the further PROMs showed a permanently improved perception of function, esthetics, sense, and speech. Conclusion: Monolithic lithium-disilicate SCs supported by zirconia implants showed promising survival and success rates after an observation period of 3 years. It remains to be seen whether the further observation period confirms this positive results.
    No preview · Article · Oct 2015 · Clinical Oral Implants Research
    • "Fig. 3 – Attrition–corrosion wear loss by volume with different lubricants under 5 N. The error bars represent standard deviations. of reciprocating cycles was characterized by a run-in stage with an increasing value followed by a steady state phase (Heintze et al., 2008). As the initial run-in is a stage during which the two contacting surfaces may undergo rapid changes and is relatively short, the steady state phase is more representative of the wear process. "
    [Show abstract] [Hide abstract]
    ABSTRACT: Attrition–corrosion is a synthesized human enamel wear process combined mechanical effects (attrition) with corrosion. With the rising consumption of acidic food and beverages, attrition–corrosion is becoming increasingly common. Yet, research is limited and the underlying mechanism remains unclear. In this study, in vitro wear loss of human enamel was investigated and the attrition–corrosion process and wear mechanism were elucidated by the analysis of the wear scar and its subsurface using focused ion beam (FIB) sectioning and scanning electron microscopy (SEM). Human enamel flat-surface samples were prepared with enamel cusps as the wear antagonists. Reciprocating wear testing was undertaken under load of 5 N at the speed of 66 cycle/min for 2250 cycles with lubricants including citric acid (at pH 3.2 and 5.5), acetic acid (at pH 3.2 and 5.5) and distilled water. All lubricants were used at 37 °C. Similar human enamel flat-surface samples were also exposed to the same solutions as a control group. The substance loss of enamel during wear can be linked to the corrosion potential of a lubricant used. Using a lubricant with very low corrosion potential (such as distilled water), the wear mechanism was dominated by delamination with high wear loss. Conversely, the wear mechanism changed to shaving of the softened layer with less material loss in an environment with medium corrosion potential such as citric acid at pH 3.2 and 5.5 and acetic acid at pH 5.5. However, a highly corrosive environment (e.g., acetic acid at pH 3.2) caused the greatest loss of substance during wear.
    No preview · Article · Apr 2015 · Journal of the Mechanical Behavior of Biomedical Materials
  • Source
    • "Several parameters were varied among testing protocols, including the force, testing medium and antagonist [20]. Of the testing variables, the composition and preparation of the antagonist material seemed to be a critical factor for ceramic wear testing [20] [21]. "
    [Show abstract] [Hide abstract]
    ABSTRACT: This paper reviews the conditions of in vivo mastication and describes a novel method of measuring in vitro wear. Methods: parameters of intraoral wear are reviewed in this analysis, including chewing force, tooth sliding distance, food abrasivity, saliva lubrication, and antagonist properties. Results: clinical measurement of mastication forces indicates a range of normal forces between 20 and 140 N for a single molar. During the sliding phase of mastication, horizontal movement has been measured between 0.9 and 2.86 mm. In vivo wear occurs by three-body abrasion when food particles are interposed between teeth and by two-body abrasion after food clearance. Analysis of food particles used in wear testing reveals that food particles are softer than enamel and large enough to separate enamel and restoration surfaces and act as a solid lubricant. In two-body wear, saliva acts as a boundary lubricant with a viscosity of 3 cP. Enamel is the most relevant antagonist material for wear testing. The shape of a palatal cusp has been estimated as a 0.6 mm diameter ball and the hardest region of a tooth is its enamel surface. pH values and temperatures have been shown to range between 2–7 and 5–55 °C in intraoral fluids, respectively. These intraoral parameters have been used to modify the Alabama wear testing method.
    Full-text · Article · Sep 2013 · Journal of Physics D Applied Physics
Show more