Glass ionomer: Ten years on

This article was first published in the ADA’s News Bulletin December 2021 edition – for the full issue and back issues, go to News Bulletin online

The aim of the randomised, double-blinded and controlled clinical trial was ‘to evaluate the durability of a glass-ionomer restorative material in class I and class II cavities during 10 years compared with a micro filled composite resin’.

Patients who presented for routine dental care and met the following inclusion criteria were invited to participate:

(1) Requiring at least two but not more than four posterior restorations;

(2) the involved teeth were in occlusal contact, symptomless and vital;

(3) had a healthy periodontal status; and

(4) had to be available at recalls.

A total of 87 participants (average age, 24 years) was recruited and 140 restorations (80 class I and 60 class II) placed in 54 premolar and 86 molar teeth, by two experienced clinicians.

Prior to commencing the restorations, the selected teeth were cleaned with a slurry of pumice and water and isolated with cotton rolls and saliva ejectors. The cavity preparations did not involve any cusps and the cervical margins were supra-gingival and within enamel. A calcium hydroxide cavity liner was applied when required, though the authors did not state these situations.

For the glass-ionomer cement restorations (EQUIA Fil; GC, Tokyo, Japan), the enamel and dentine were conditioned with 20% polyacrylic acid for 20 seconds, the cement inserted into the cavity and contoured with a hand instrument. When the material had set, the restoration was finished, and a coating material (EQUIA Coat, GC) was applied, and light cured.

For the resin composite restorations (Gradia Direct Posterior; GC, Tokyo, Japan), the enamel and dentine were conditioned with an all-in-one enamel/ dentine bonding agent (G-Bond, GC), left undisturbed or 10 seconds and dried for five seconds. The resin composite was placed in increments, each increment light cured for 20 seconds and the restoration finished and polished.

At the 10-year recall, 51 patients and 124 restorations (61 glass-ionomer cements, 38 class I and 23 class II, and 63 resin composite, 38 class I and 25 class II) were evaluated with an overall recall rate of restorations of 88.6%. Two class II glass-ionomer cement restorations were lost as a result of margin fracture at the 3rd and 4th-year recall (failure rate of 2.9%). There were no failures of the class I and class II resin composite restorations.

Moderate marginal discolouration was observed in both types of restorations during the 10-year period. Although not statistically significant, the resin composite restorations showed more marginal discolouration and adaptation failures than the glass-ionomer cement restorations. The authors felt that the use of self-etch adhesive and polymerisation shrinkage of the resin composite may have been the reason for the marginal discolouration and adaptation failures of the resin composite restorations. No secondary caries was detected for either material over the 10-year period, and the authors attributed this to their strict selection criteria, that is, patients were low-caries risk, attended a recall visit every year for 10 years and the restorations were small.

The authors concluded that both glass-ionomer cement and microfilled resin composite showed good survival

after 10 years, in their low-risk group, noting there was no significant difference between the two materials in

their durability and clinical performance.

Reference – Gurgan S, Kutuk Z B, Cakir F Y, Ergin E. A randomized controlled 10 years folloup of a glass ionomer restorative material in class I and class II cavities. Journal of Dentistry 2020;94:103175

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