No Evidence That High-Viscosity Glass-Ionomers Are Inferior to Current Gold Standards in Restorative and Preventive Dentistry

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SYSTEM Initiative: Systematic review evidence indicates no clinical meaningful difference between glass-ionomer and gold-standards in the placement of load-bearing tooth restorations, as well as the sealing of pit and fissures to prevent dental caries.

No difference in the clinical efficacy between glass-ionomers and gold-standards when placed as load-bearing tooth restorations or preventive fissure sealants

New findings have indicated an absence of clinical evidence in support of the notion that high-viscosity glass-ionomers are inferior in their failure rate to silver amalgam as the current gold standard when placed as load bearing single- or multiple surface cavity restorations in posterior teeth.

The findings also suggest an absence of evidence in support of the long held ideal that glass-ionomers are inferior in their caries preventive effect to resin composites as standard for the placement of dental pit and fissure sealants.

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 and sealants, the SYSTEM Initiative of the Faculty of Health Sciences, University of the Witwatersrand, Johannesburg, has conducted several systematic reviews of randomised control trials and a meta-epidemiological study.

The systematic review of the current dental literature 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 difference beyond the play of chance 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.

During the systematic review of the current dental literature concerning fissure sealants, 16 trials were accepted as evidence, comprising the investigation of more than 7 000 placed fissure sealants. The review outcome highlights the difficulty in regarding glass-ionomers as inferior to resin, as again no overall difference beyond the play of chance was found in the caries occurance rate between glass-ionomer and resin sealed teeth after follow-up periods ranging from six months to seven years.

Throughout the systematic review all clinical trials were assessed and subsequently accepted or rejected according to criteria related to study validity. All clinical evidence was closely examined for risk of systematic errors and several trials were excluded on the basis of high bias risk and low precision of results.

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 incorrect 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.

Furthermore, the overall outcome offered no evidence to support the notion that glass-ionomer cements are inferior to the current gold standard when sealing pit and fissure to prevent the development of tooth caries. As the original systematic review was conducted in 2008 a subsequent investigation conducted in 2013 established that the review conclusion remain current and valid.

The published full reports of the new findings are available online:
(1) 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.

(2) 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.

(3) Mickenautsch S, Yengopal V. Caries-preventive effect of glass ionomer and resin-based fissure sealants on permanent teeth: An update of systematic review evidence. BMC Res Notes 2011; 4: 22.

(4) Mickenautsch S, Yengopal V. The modified Ottawa method to establish the update need of a systematic review: Glass-ionomer versus resin sealants for caries prevention. J Appl Oral Sci 2013; 21: 482-9.

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