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Title Zirconia Crowns Are Less Abrasive on Opposing Enamel Compared to Metal-Ceramic Crowns
Clinical Question In patients requiring a full-coverage crown opposing the natural dentition, is an all-ceramic zirconia crown less abrasive to opposing enamel compared to a metal-ceramic crown?
Clinical Bottom Line For patients requiring full-coverage crowns opposing natural dentition, all-ceramic zirconia crowns are less abrasive to opposing enamel than metal-ceramic crowns.
Best Evidence (you may view more info by clicking on the PubMed ID link)
PubMed ID Author / Year Patient Group Study type
(level of evidence)
#1) 25985742Mundhe/2015 10 participants between the ages of 18-35 yearsRandomized Controlled Trial
Key resultsEach of the 10 patients received a zirconia and a metal ceramic crown on opposite sides of the dental arch opposing natural dentition. After 1 year the occlusal wear of opposing enamel by metal-ceramic crowns was 69.20 ± 4.10 μm for premolar teeth and 179.70 ± 8.09 μm for molar teeth. With zirconia, the enamel wear was 42.10 ± 4.30 μm for premolar teeth and 127.00 ± 5.03 μm for molar teeth. The Bonferroni post hoc test revealed that the occlusal wear of antagonist enamel 1 year after the cementation of a metal-ceramic crown was significantly higher (P<.001) than that of enamel opposing a zirconia crown or natural enamel.
#2) 22892464Kim/2012100 specimens (20 per group)Laboratory study
Key resultsOne hundred natural teeth were abraded against one of three types of monolithic zirconia, E.max Press lithium disilicate, or feldspathic porcelain. Feldspathic porcelain led to the greatest amount of enamel wear followed by E.max Press and the three brands of monolithic zirconia. The wear values for human enamel were significantly greater than those for feldspathic porcelain, regardless of the surface roughness of the ceramic specimens (p < 0.05).
Evidence Search ("dental enamel"[MeSH Terms] OR ("dental"[All Fields] AND "enamel"[All Fields]) OR "dental enamel"[All Fields] OR "enamel"[All Fields]) AND ("Wear"[Journal] OR "wear"[All Fields]) AND ("zirconium oxide"[Supplementary Concept] OR "zirconium oxide"[All Fields] OR "zirconia"[All Fields]) AND ("crowns"[MeSH Terms] OR "crowns"[All Fields])
Comments on
The Evidence
Validity: The Mundhe randomized control trial tested a small group of 10 patients between ages 18 and 35 years old. While utilizing a split mouth design limits confounding variables, the sample size of the group is still fairly small; however, the study was still able to obtain statistically significant results comparing the wear of opposing enamel by zirconia and metal-ceramic crowns. The control group, enamel opposing enamel, showed statistically significant less enamel wear than both experimental groups. Kim’s laboratory study was done in vitro to compare the enamel abrasion done by different types of porcelain and monolithic zirconias. Twenty specimens per group were placed through 300,000 wear cycles against recently extracted teeth in a heat-controlled environment. Worn surfaces were evaluated by electron microscopy. All three brands of monolithic zirconia caused significantly less wear on enamel compared to feldspathic and E.max press porcelain. Both of these studies showed that zirconia has significantly less wear against opposing enamel compared to porcelain. However these studies had multiple limitations such as small sample sizes and limited time periods. There were no conflicts of interests listed in any of the publications, and bias was minimized by treating all control and experimental groups the same. Perspective: The general consensus is that the enamel wear from opposing zirconia is less than porcelain but still not similar to that of enamel opposing enamel. There is still not very much information on the effect of zirconia on enamel wear over longer periods of time. Most of the papers on this topic are short-term clinical studies or laboratory studies. Studies on the wear of zirconia against opposing enamel also need to be done in patients exhibiting bruxism.
Applicability This study is applicable to general dentists, restorative dentists, and prosthodontists interested in different options for restorative dentistry. It is also applicable to the patient group requiring full-coverage crowns opposing natural dentition.
Specialty/Discipline (General Dentistry) (Prosthodontics) (Restorative Dentistry)
Keywords All-ceramic zirconia crowns, metal-ceramic crowns, enamel wear
ID# 3310
Date of submission: 02/07/2018spacer
E-mail Sarrami@livemail.uthscsa.edu
Author Shayda Sarrami
Co-author(s) e-mail
Faculty mentor/Co-author E. Penn Jackson, DDS
Faculty mentor/Co-author e-mail JacksonEP@uthscsa.edu
Basic Science Rationale
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