Bad bites bite back: a commentary on the impact of malocclusion on oral ingestion

A systematic review following Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines was conducted. PubMed and Cochrane databases were searched. Journal articles published between January 2007 and January 2023 were identified. Studies that assessed malocclusion indices and oral function were included. Non-English articles and irrelevant studies were excluded. A total of 480 articles were identified. Following exclusion, 29 articles were included in the systematic review. Data was compiled using Microsoft Excel. Information from each article was extracted including study design, evaluation criteria of malocclusion and oral function, and findings. Studies were assessed using the STROBE GRADE approach. The results were compiled in a brief narrative review investigating the type and strength of the association between malocclusion and ingestion. Malocclusion was recorded using Index of Treatment Need, Dental Aesthetic Index, Goslon Yardstick Index, Index of Complexity Outcomes and Need, Peer Assessment Rating, Angle’s classification, Specific Severity Score, dental inter-arch relation and cephalometric analysis. Ingestion was measured by bite force, electromyography, mixing ability index, bolus granulometric analysis, video analysis of kinetic parameters during mastication, and subjective questionnaires. Of the 29 articles identified, 20 demonstrated a negative impact of malocclusion on oral ingestion, highlighting impaired masticatory efficiency, bite force and subjective difficulties. Eight studies found no significant association. One study, which used two questionnaires, found a significant relationship between eating and malocclusion using one questionnaire but not the other. Limitations in current research methodologies were identified, particularly the heterogeneity in assessment tools. The indicators used to assess ingestion and malocclusion are flawed, with questionable reliability. No study was able to identify which features or severity of malocclusion impact ingestion. The relationship between ingestion and malocclusion could not be quantified and the need for longitudinal and case report studies was deemed essential to establish causality. This review underscores the importance of considering how malocclusion impacts function in orthodontic treatment planning. Future research should focus on standardised assessment methods for measuring malocclusion and oral ingestion to establish the nature of the relationship between the two. This will ultimately guide orthodontic intervention aiming to enhance oral function.