Maxillary constriction is a relatively common condition. Various treatment modalities have been proposed for this condition such as rapid maxillary expansion (RME). Although RME can significantly expand the suture in a relatively short period of time, it has a number of drawbacks, mainly a lengthy retention period. The primary objective of this study was to assess the efficacy of the supplementary methods used in conjunction with RME for new bone formation (NBF) at the midpalatal suture (MPS). Relapse, bone healing, and root resorption were also studied as the secondary outcomes.

The PubMed, Embase, and Cochrane library online databases were searched according to the PRISMA-ScR guideline. Animal studies on the effects of non-surgical supplementary methods other than laser therapy on NBF in RME were included and reviewed.

Thirty-eight articles met the inclusion criteria. The supplementary methods were categorized into 6 groups: hormones, chemical agents, drugs, vitamins, proteins, and some other substances, which could not be assigned to any group. All the aforementioned substances enhanced NBF. Drugs such as bisphosphonates also increased bone resorption. The oestrogen hormone was shown to reduce treatment relapse. Lastly, stem cell application accelerated bone healing at the expanded MPS.

Administration of hormones, chemical agents, drugs, vitamins, herbs, and proteins may improve the outcomes of RME, shorten the retention period and consequently, reduce relapse in animals. However, the generalizability of these findings is limited due to the insubstantial number of studies published on each substance.