Background: Early treatment of malocclusion in primary and early mixed dentition is often carried out by dentists under the supervision of orthodontists. In these treatments, simple appliances are preferred.

Objectives: To analyse which occlusal traits can be corrected with prefabricated eruption guidance appliances (EGAs) in mixed dentitions.

Search methods: Articles written in English and published between January 1990 and March 2023 were searched from Cochrane Library, Clinicaltrials.gov, EMBASE, International Clinical Trials Registry Platform, LILAC, PubMed, and Scopus.

Selection criteria: The inclusion criteria were formed according to the Patient, Intervention, Comparison, Outcomes, and Study design schema (PICOS).

Data collection and analysis: Selection of the articles followed the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines. Risk of bias was evaluated using RoB 2 and ROBINS-I tools. The pooled estimates for the change in clinical and cephalometric measurements were calculated. The overall quality of the outcome was assessed using the Grading of Recommendations Assessment, Development, and Evaluation (GRADE) tool.

Results: Seven articles with 277 patients and 219 controls were included. One was a randomized controlled trial, one was a retrospective study, and three were prospective treatment studies. Two follow-up studies analysed cephalometric data of already included studies. Four prefabricated appliances were used: Education Fonctionnelle, LM-Activator™, Nite-Guide®, and Occlus-o-Guide®. Treatment protocols varied from passive night-time use to combinations of active daytime and passive night-time use. Treatment periods varied from 10 months to 3.3 years. The main findings were reductions in overjet (range 1.1-2.3 mm) and overbite (range 0.6-2.0 mm). Other findings included improvement in crowding and molar relationship and better tooth-to-tooth contacts. Even though most of the changes were dental, significant increases in the length of the mandible were reported in two studies. Four studies were included in the meta-analyses. In these analyses, the changes in overjet, overbite, SNB, and ANB were found statistically significant.

Conclusions: EGAs comprise a group of functional appliances suitable for reduction of excessive overjet and overbite in mixed dentition. However, more studies are needed to elucidate their effects on skeletal structures.

Registration: The protocol for this review was registered at PROSPERO under the ID CRD42023441197.