Efficacy of Pre formed Metal Crowns Vs. Amalgam Restorations in Primary Molars: A Systematic Review.

Meghan Sullivan Walsh November 28, 2010

Literature Review - St. Joseph/LMC Pediatric Dentistry

Efficacy of Pre formed Metal Crowns Vs. Amalgam Restorations in Primary Molars: A Systematic Review.

Resident: Meghan Sullivan Walsh

Program: Lutheran Medical Center- Providence

Article Title: Efficacy of Pre formed Metal Crowns Vs. Amalgam Restorations in Primary Molars: A Systematic Review

Authors: Ros C. Randall, B.CH.D., M.PHIL; Matthias M. A. Vrijhoef, PH.D; Nairn H.F. Wilson, PH.D,

Journal: JADA

Volume (number), Year, Page #’s; 131, March 2000, pages 337-343.

Major Topic: Efficacy of pre formed metal crowns vs. amalgam restorations in primary molars.

Overview of Method of Research: Literature review and meta-analysis were used to provide data regarding PMC and amalgam restorations. The data collected ranged from 1.5 to 10 years. A table of outcomes was constructed comparing successful and failed restorations. Using this data, the odds ratio, (OR), and 95 percent confidence interval, (CI) was calculated to estimate the treatment effect.

Findings: A total of 10 studies were available for quantitative analysis. True and false failure rates were discussed in 6 of these articles. False failures were classified as teeth requiring orthodontic extractions, extractions due to pulp pathology unrelated to the restoration and caries in a restored tooth remote from the restoration. True failures were loss of a PMC leading to need for recementation and secondary caries and fracture in the case of an amalgam. Across all of these studies, PMC’s consistently had a lower failure rate as compared to amalgam varying between 1.5 to 9 failed amalgam for every failed PMC. Should you understand the meta analysis math used in this article the OR and CI were calculated as ORmh = 0.23; 95 percent. CImh = 0.19-0.28.

Key Points: Summary: Despite the differences in the date used for this study, PMC’s consistently showed the same positive effect when compared to amalgam. One of the longest and largest studies used in this analysis recorded the lowest failure rate for PMC and amalgam restorations. Amalgams in this study were used for minimal tooth preparation and the remainder were restored with a PMC. The failure rate of an amalgam reported as 11.6 while the failure rate of a PMC was 1.9 over 10 years. Another study performed by Braff showed the highest failure rate for both restorations. However, the average age of his patients were 4.2 years old. In addition, failure rates of many of the PMC were contributed to pulp inflammation. There is difficulty establishing correct cause of failure of a PMC when pulp pathology is involved as it may be multifactiorial in origin. The majority of the articles were retrospective which can often creates difficulty relying on the accuracy of patient records and documentation. Despite all the differences in these articles, PMC’s still remain and statistically show that they are the restoration of choice for a primary molar with multi surface cavities.

Assessment of the Article: The authors do mention how in many of these studies the decision process by which a tooth would be restored with a PMC or an amalgam was not discussed. This may create a bias leading to the success of a PMC when we are aware that a PMC is the restoration of choice for a tooth with multi surface decay. In addition they understand the difficulty behind a well-designed clinical trial which would justify treating a child’s tooth randomly with either a PMC or an amalgam. The article was well written, the results were carefully evaluated and I thought it was a great comparison of the two materials. In addition, it is confirmation that, when in doubt, a PMC is the restoration of choice for a primary tooth when considering the longevity of the restoration.