ORAL HEALTH EVIDENCE-BASED PRACTICE PROGRAM
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Title Zirconia Crowns Show Similar Failure Rate But More Extensive Occlusal Wear Than Gold Crowns
Clinical Question In an adult needing a posterior crown how does a zirconium crown compare to a gold crown in terms of failure and opposing tooth wear?
Clinical Bottom Line There is no significant difference between gold and zirconia crowns in failure rates, but occlusal is was more extensive with zirconia crowns. (See Comments on the CAT below)
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) 18976267Enchke/2009224 Randomly divided into 2 treatment groupsRandomized Controlled Trial
Key resultsTwo treatment groups of 224 patients were randomly assigned to have zirconia restorative crowns or gold restorative crowns. After 6, 12 and 24 months, the survival rates for the crowns were observed. The survival rates for zirconia crowns were 97.9%, 95.1% and 89.8%. In addition, the gold crown survival rates were 100%, 94,8% and 92.7%. A p-value of 0.2 revealed that there were no significant differences between the two groups. Failure rates at 1- year were 5.2% for gold crowns and 4.9% for zirconia crowns. Also, a cumulative risk was done that assessed 1 year crowns that analyzed secondary caries, loss of crown and abutment, fractures, loss of vitality and extraction for ziconia were 0%, 1.1%, 0%, 8.9%, 0% while gold crowns were 0%, 0%, 4.7%, 2.8% and 0.9%.
#2) 19410068Ghazal/2009NoneIn vitro study
Key resultsThree sets of 16 zirconia ceramic balls with different surface roughness values were tested against 3 groups of 8 nanofilled composite resin teeth and 3 groups of 8 human teeth for 300,000 cycles in a simulator that emulated mastication. There was a significant (P<0.001) increase in the wear of composite resin and human enamel when increasing the antagonistic surface of zirconia against the surface. In addition, there was a significant relationship (r=0.667, P<0.001) between the antagonistic surface roughness and volume loss.
Evidence Search Two searches were performed 1. (("Tooth"[Mesh]) AND "Zirconium"[Mesh]) AND "Gold"[Mesh]2.((("Zirconium"[Mesh]) AND "Dental Restoration Wear"[Mesh]) AND "Dental Enamel"[Mesh]) AND "Hardness"[Mesh]
Comments on
The Evidence
The first article looked at 224 patients in a randomized controlled study that assessed the durability and longevity of zirconia versus gold crowns. These studies had a decent sample size that was tested over a 5 year period. The second study used 3 groups of 8 human teeth and 3 groups of 8 nanofilled composite resin teeth against 16 zirconia ceramic balls each with a different surface roughness. This review was a in vitro study that did not use human subjects.
Applicability Using zirconia could be a very appealing alternative to the patient because of esthetics. For the dentist, it allows more flexibility when treatment planning a patient. However, the dentist must take into consideration that zirconia crowns produces more tooth wear to opposite teeth when compared to gold crowns.
Specialty/Discipline (General Dentistry) (Prosthodontics) (Restorative Dentistry)
Keywords Zirconia, Gold crowns, Tooth Wear, Failure rates
ID# 2260
Date of submission: 04/25/2012spacer
E-mail Shinta@llivemail.uthscsa.edu
Author Mustafa Shinta
Co-author(s)
Co-author(s) e-mail
Faculty mentor/Co-author Mark Littlestar, DDS
Faculty mentor/Co-author e-mail littlestarm@uthscsa.edu
Basic Science Rationale
(Mechanisms that may account for and/or explain the clinical question, i.e. is the answer to the clinical question consistent with basic biological, physical and/or behavioral science principles, laws and research?)
post a rationale
None available
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Comments on the CAT
(FOR PRACTICING DENTISTS' and/or FACULTY COMMENTS ON PUBLISHED CATs)
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by Vishnu Raj (San Antonio, TX) on 05/22/2014
A recently published RCT( PMID: 23745725) evaluating the 5-year follow-up of the original study reported a drastic drop in survival probability of Zr crowns, from 99 percent at year one to 73.2 percent at year five. Survival rate of gold crowns at year five was 92 percent. Based on these findings, the use of single unit CAD-CAM Zr crowns in the posterior region should be re-evaluated.
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