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Title Zirconia Based FDP May Be An Alternative to Conventional PFM with Veneers That are More Compatible in Terms of Co-Efficient of Thermal Expansion
Clinical Question Are Zirconia based FDPs a viable alternative to conventional PFM FDPs?
Clinical Bottom Line Zirconia–ceramic FDPs are a promising alternative to conventional PFM FDPs, however, literature reports high level of ceramic veneer chipping resulting in compromised prostheses or failures.
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) 21209982Heintze/201013 clinical studies on Zirconia FPD’s and 2 studies with both PFM and Zirconia were included. These involved 595 Zirconia and 127 PFM FDP’s. Mean follow up period – 3 years. Literature review
Key resultsThe author's conclusions are: “If all grades of veneer chippings were taken into account, the survival rate of PFM FDPs was 97% while the survival rate of Zirconia FDP was 90% after 3 years for a typical study. Veneer chipping was significantly less frequent in pressed materials than in hand layered materials, both for zirconia and PFM FDPs (P= .04). The frequency of core fracture was less than 1% in the zirconia group and 0% in PFM group. The studies differed extensively with regard to veneer chipping of zirconia. If only studies that evaluated both types of core materials were included, the frequency of chipping was 54% for zirconia supported FDPs and 34% for PFM FDPs. When adjusting the survival rate for study effect, the difference between zirconia and PFM FDPs was statistically significant for all grades of chipping (P= .001)as well as for chipping grade 3 (P=.02).”
#2) 22385693 Raigrodski/201212 studies based on zirconia, framework design, porcelain veneering technique were included. Of the studies identified, 1 was a randomized Controlled trial with 3 year follow up results and the others were cohort prospective studies. Systematic review of non-randomized trials
Key resultsThe authors' conclusions are as follows: “Survival rates ranged from 73.9% to 100% within 12 studies. 5 studies reported 100% survival rates during observations period. One study reported 73.9% survival of frameworks and the rest (6 studies) had survival rates ranging between 88.2% and 96.6%."
Evidence Search "Denture, Fixed"[Mesh] AND “Human”[Mesh] AND "Zirconia"[Mesh] AND "PFM"[Mesh] AND “Survival” [Mesh]
Comments on
The Evidence
For both included reviews, all studies dealing with implant-supported prostheses were excluded. In the article by Heintze et al., 13 studies on zirconia FDP’s and 2 studies on both zirconia and PFM FDP were used. This study formulated four hypotheses, but the only one that could be confirmed was that “zirconia FDPs exhibited more chipping than PFM FDP’s.” This study described a chipping index or grading based on severity and noted that the frequency of chipping was varied across studies reviewed. In the systematic review by Raigrodski, 11 prospective cohort studies and 1 randomized controlled trial was included. All the included studies were grouped by connector dimension and application of veneering porcelain (layered vs pressed). The sample sizes were low, so no meta analysis was done. Technical and biological complications were used to determine the failures. The authors noted differences in reporting criteria for failure/chipping between studies. The most prevalent technical complication was chipping of the veneering porcelain, followed by framework fracture. Although the data is limited, authors concluded that pressed to Zirconia resulted in better clinical outcomes than conventional layering technique.
Applicability Clinicians are searching for alternatives to conventional PFM FDPs because of esthetic reasons and the rising cost of gold and other precious metals. Zirconia has a slight esthetic advantage over PFM, but the rate of chipping is significantly higher. Zirconia also possesses a property called transformation toughening that involves a change from tetragonal to monoclinic form – this prevents crack propagation. Further research and evaluation is indicated regarding Zirconia FDPs for it to be a viable alternative.
Specialty/Discipline (General Dentistry) (Prosthodontics) (Restorative Dentistry)
Keywords Zirconia, FDP, Survival, Human, PFM.
ID# 2802
Date of submission: 01/22/2015spacer
E-mail azmaahmed@gmail.com
Author Azma Ahmed
Co-author(s) e-mail
Faculty mentor/Co-author Alan Sutton, DDS
Faculty mentor/Co-author e-mail alan.sutton@ucdenver.edu
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