This new critical summary from the ADA-Center for Evidence Based Dentistry looks at a 2010 review from Mickenautsch et al. The aim of that review was to compare the pulpal responses to resin-modified glass ionomer cement (RM-GIC) and calcium hydroxide when placed in deep cavities.
The review only included six trials (one randomized and five non-randomized) evaluating 923 permanent and 27 primary teeth. The appraiser noted that randomized and non-randomized trials, primary and permanent teeth, and carious and non-carious teeth were combined into a meta-analysis.
Overall then, the original review was only able to find a small number of low quality studies addressing the question. This means that until more definitive evidence is available clinicians may consider both materials when restoring deep lesions.
Mickenautsch S, Yengopal V, Banerjee A. Pulp response to resin-modified glass ionomer and calcium hydroxide cements in deep cavities: A quantitative systematic review. Dent Mater. 2010 Aug; 26(8): 761-70. Epub 2010 May 7. Review. PubMed PMID: 20452013.