Environmental impact of dental amalgam and alternative restorative materials: a systematic review

Concern about the environmental impact of dental restorative materials has grown in recent years. The most common material for dental restorations has historically been amalgam, but this has seen a decline due to concerns about the health and environmental impact of mercury. Alternative dental restorative materials include resin-based composite (RBC) and glass-ionomer cement (GIC), but both have uncertain environmental impacts. This systematic review aimed to compare the environmental impact of dental amalgam versus other restorative materials used for direct restorations.

We undertook a systematic review which followed established guidance and prospectively registered our protocol on PROSPERO (CRD42024608563). Searches of bibliographic databases included Environment Complete, GreenFILE, Science Citation Index, CAB Abstracts, MEDLINE and CINAHL. These were supplemented with checking reference lists and forward citation searching of included studies. Retrieved records were screened by two independent reviewers at title and abstract and full text using pre-defined inclusion criteria. Data extraction and quality appraisal were undertaken by one reviewer and checked by a second. Findings were narratively synthesised.

Twenty-one studies (n = 22 study reports) were included. Eleven were in a clinic setting, three were in a lab setting, five were in both clinic and lab settings and two were in a crematorium setting. Six studies included a comparison between different restorative materials, the remainder only measured environmental impact of one material (or multiple without comparison). Some studies were framed as potential environmental impact due to limited data. Materials included dental amalgam, RBC and GIC. Studies were highly heterogenous which limited the scope for synthesis of findings. All materials were associated with environmental impact.

Whilst the evidence included in this review indicates that both amalgam and non-amalgam dental materials are associated with environmental impacts, confidence in these findings is limited due to the heterogeneity of study designs, outcome measures, and limited comparative data. Further research is needed to inform future policies which aim to reduce the environmental impact of restorative dental activities.