No Evidence That High-viscosity Glass-Ionomers Are Inferior to Current Gold Standard in Restorative Dentistry

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SYSTEM Initiative: New findings indicate absence of clinical evidence that high-viscosity glass-ionomers are inferior in their failure rate to silver amalgam as current gold standard when placed as load bearing single- or multiple surface cavity restorations in posterior teeth.

Placing High-viscosity Glass-ionomer Restorations May Offer an Alternative to Placing Restorations with Silver Amalgam

The current consensus that glass-ionomers are clinically inferior to silver amalgam when placing restorations in posterior teeth is widely acknowledged as truth. For decades, experts have spoken out against the choice of glass-ionomers instead of silver amalgam or composite resin materials for load bearing posterior tooth restorations, based on clinical evidence that, when closely examined, holds little scientific weight.

In an effort to appraise the current clinical evidence regarding the merits of placing glass-ionomers as tooth restorations, the SYSTEM Initiative of the Faculty of Health Sciences, University of the Witwatersrand, Johannesburg, has conducted a systematic review of randomised control trials and a meta-epidemiological study.

The systematic review included a literature search in 17 global and regional databases, as well as databases for open access journals and ‘grey’ literature. Besides searching the global databases PubMed/Medline and the Cochrane library, the searched additional regional English databases comprised of the scientific dental literature from Africa, Europe, India and North America, whilst regional non-English databases comprised of the dental literature from China and Latin-speaking American countries.

In total, 38 trials were accepted as evidence, comprising the investigation of more than 10 000 placed tooth restorations. The outcome shows that new generation, high viscous glass-ionomers cannot be regarded as inferior to amalgam, since no overall statistically significant difference was found in the clinical failure rate between load bearing high-viscosity glass-ionomer and amalgam restorations after follow-up periods ranging from one to six years.

The results of SYSTEM’s meta-epidemiological study show that statements concerning glass-ionomer’s inferiority to amalgam and other types of materials are based on incorrect statistical comparison methods. Such methods include the still common naïve-indirect comparison of restoration failure rates from uncontrolled clinical longitudinal studies. Simply put, the traditional argument against the use of glass-ionomers in modern dentistry is based on the wrong assumption that results from unrelated clinical trials with differing clinical settings and patient groups can be directly compared to one another. Instead, statements concerning the merits of clinical interventions should rest on the direct comparison of competing treatment options via randomised control trials.

High-viscosity glass-ionomer restorations do not require provison of macro-retention by high-speed drilling, thus they offer the dental profession a more patient friendly approach for placing tooth restorations. Placing glass-ionomer restorations also reduces the likelihood of a repeated restoration cycle, because repair of failed restorations does not require the removal of remaining filling material from the tooth cavity.

The new findings suggest that placing high-viscosity glass-ionomer restorations may offer an alternative to placing restorations with silver amalgam in load bearing posterior cavities of permanent teeth.

The published full reports of the new findings are available online:
Mickenautsch S, Yengopal V. Failure rate of high-viscosity GIC based ART compared to that of conventional amalgam restorations - evidence from a systematic review update. S Afr Dent J 2012; 67: 329-31.

(Text of the full systematic review report: ) )

Mickenautsch S, Yengopal V. Direct contra naïve-indirect comparison of clinical failure rates between high-viscosity GIC and conventional amalgam restorations. An empirical study. PLOS One 2013; 8: e78397.

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Dr S Mickenautsch
SYSTEM Initiative, Univ. of the Witwatersrand, Johannesburg
+27 823363214
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