Adverse Effects of 'Two-by-Four Fixed Orthodontic Appliance' in Mixed Dentition Period - A Systematic Review.

Malocclusion is a global public dental health problem with higher prevalence and treatment needs. However, there is a perplexing literature regarding early orthodontic intervention in the mixed dentition stage. '2 × 4 orthodontic appliances' have been highlighted in the literature as versatile appliances for the effective correction of various malocclusions in children. However, dental clinicians and researchers should also have updated knowledge about the negative aspects of '2 × 4 orthodontic appliances', which are reported in the exiting literature. Hence, this systematic review aimed to find out the evidence about the adverse effects/complications of 2 × 4 orthodontic appliance therapy in mixed dentition phase of paediatric patients by extensively exploring and critically appraising the pertinent literature. This systematic review was performed as per the Preferred Reporting Items for Systematic Reviews and Meta-analyses (PRISMA) guidelines. Its protocol was registered in International Prospective Register of Systematic Reviews. Literature was searched comprehensively in six databases and also manually. After the screening of the records (n = 1234) as per the eligibility criteria, finally, nine (n = 5) articles were included and critically analysed using different Joanna Briggs Institute critical appraisal tools. Eligible studies including Randomized Controlled Trial (RCT) (n = 1), non-RCT (n = 2), retrospective study (n = 1), case-report (n = 1) published from 1999 to 2023 in which 82 patients with mean-age of 10-year, mostly with pseudo class-III malocclusion, anterior cross-bite and crowding treated using 2 x 4 appliance were found. The literature-based evidence related to the adverse effects of 2 × 4 orthodontic appliances was found to be inadequate in quantity, but majority was of high quality (low risk of bias). However, various negative aspects/complications of this particular fixed orthodontic therapy were reported by the included primary studies.