The valid consent process for medical intervention requires the disclosure of information in a format that is easily understandable by the patient. The aim of this investigation was to assess the readability of orthognathic surgery informed consent forms (OSICFs).

An online search methodology was conducted to identify OSICFs for analysis. The forms that satisfied inclusion/exclusion criteria were evaluated according to a standardised protocol. The readability of the content was assessed using three validated tools: the Simple Measure of Gobbledegook (SMOG) score, Flesch-Kincaid Grade-Level (FKGL) score and Flesch Reading Ease (FRE) score.

Most of the 26 evaluated OSICFs were sourced from websites within the United States (69.2%) and from oral and maxillo-facial surgery practices (76.9%). Two of the assessed forms were template OSICFs available from oral and maxillo-facial professional societies to its members. The scores from the three tools found that the content of 84.6% to 92.3% of the forms were “difficult” to read. The mean (SD) SMOG score for all evaluated OSICFs was 12.31(2.22) [95% CI: 11.42 to 13.21]. The SMOG and FKGL scores were closely correlated (r=0.99, P < 0.0001; 95% CI: 0.9864 to 0.9973). There was no association between SMOG scores and the number of words contained within each consent form (r=−0.047;95% CI: −0.44 to 0.36).

The OSICFs surveyed in this investigation failed to meet recommended readability levels. A significant number of patients are not likely to understand the information contained within the forms. Orthodontists are advised that poor literacy skills of their patients may preclude them from validly consenting to orthognathic surgery treatment procedures.