Accuracy of the registration of a digital dental cast or intraoral scan into a stereophotogrammetric image of the face: a systematic review.

Background Recent technological advances enable integration of digital dental casts or intraoral scans with 3D facial stereophotogrammetry. However, evidence on the accuracy of this integration remains limited.Objectives To assess the level of evidence regarding the accuracy of the integration of a digital dental cast or intraoral scan into a 3D-facial image, in comparison to a full face CBCT scan in healthy growing and nongrowing patients.Search Methods MEDLINE (PubMed), EMBASE, Web of Science, Cochrane Library were searched. A manual search was performed of reference lists of included articles.Selection Criteria Inclusion criteria were studies investigating the integration of a digital dental cast or intraoral scan into a 3D stereophotogrammetric picture of the face, with a full face CBCT as a comparator. All study designs except case reports were included.Data Collection And Analysis A pilot assessment was conducted, to synchronize the reviewers' criteria for data extraction. After data extraction, a Risk of bias (RoB) assessment was performed using the Quality assessment of diagnostic accuracy studies (QUADAS-2) tool. Certainty of the evidence was assessed by the Grading of Recommendations, Assessment, Development and Evaluation (GRADE) tool.Results Four eligible studies were identified and two more after updating the literature search. All reviewed studies confirmed feasibility of integrating intraoral scans with 3D facial images. The QUADAS-2 assessment revealed a high risk of bias for all included studies. Certainty of evidence concerning the accuracy was very low (GRADE). Due to heterogeneity concerning registration procedures and anatomical landmarks between the included studies, a qualitative description analysis of the results was made.Conclusions The accuracy of the registration of a digital dental cast or intraoral scan into a facial scan is clinically acceptable. Most, but not all outcomes met the 2 mm or 2 degree threshold, depending on anatomical region, image acquisition, and measurement method. A 3D image of the face with an integrated digital dental cast or intraoral scan may be a promising radiation-free method for orthodontic diagnostics and treatment planning. However, due to the inconsistency in different registration methods and small sample sizes, the accuracy is yet to be further investigated.Clinical Trials Registration INPLASY (INPLASY202420038).