_Applied_  
_sciences_  
**How to Obtain an Orthodontic Virtual Patient**  
**through Superimposition of Three-Dimensional Data:**  
**A Systematic Review**  
**[PERSON] \({}^{\dagger}\), [PERSON] \({}^{\star,\star}\)\({}^{\text{\textregistered}}\), [PERSON], [PERSON], [PERSON]\({}^{\text{\textregistered}}\) and [PERSON]**  
Postgraduate School of Orthodontics, Fondazione Policlinico Universitario A. Gemelli IRCCS, Universita  
Cattolica del Sacco Cuore, 00168 Rome, Italy; [EMAIL_ADDRESS] (F.M.J.; [EMAIL_ADDRESS] (M.A.Z.);  
[PERSON]] (A.R.); [PERSON].G.); [PERSON]PG.)  
\({}^{\star}\) Correspondence: [PERSON]\({}^{\dagger}\) These authors contributed equally to this work.  
Received: 8 July 2020; Accepted: 27 July 2020; Published: 3 August 2020  
**Featured Application: This systematic review summarizes the available literature about integration of CBCT scans, digital casts, and facial scans.**  
**Abstract:** Background: This systematic review summarizes the current knowledge on the superimposition of three-dimensional (3D) diagnostic records to realize an orthodontic virtual patient. The aim of this study is to analyze the accuracy of the state-of-the-art digital workflow. Methods: The research was carried out by an electronic and manual query effectuated from ISS (Istituto Superiore di Sanita in Rome) on three different databases (MEDLINE, Cochrane Library and ISI WEB OF SCIENCE) up to 31 st January 2020. The search focused on studies that superimposed at least two different 3D records to build up a 3D virtual patient--information about the devices used to acquire 3D data, the software used to match data and the superimposition method applied have been summarized. Results: 1374 titles were retrieved from the electronic search. After title-abstract screening, 65 studies were selected. After full-text analysis, 21 studies were included in the review. Different 3D datasets were used: facial skeleton (FS), extraoral soft tissues (ST) and dentition (DENT). The information provided by the 3D data was superimposed in four different combinations: FS + DENT (13 papers), FS + ST (5 papers), ST + DENT (2 papers) and all the types (FS + ST + DENT) (1 paper). Conclusions: The surface-based method was most frequently used for 3D objects superimposition (11 papers), followed by the point-based method (6 papers), with or without fiducial markers, and the voxel-based method (1 paper). Most of the papers analyzed the accuracy of the superimposition procedure (15 papers), while the remaining were proof-of-principles (10 papers) or compared different methods (3 papers). Further studies should focus on the definition of a gold standard. The patient is going to have a huge advantage from complete digital planning when more information about the spatial relationship of anatomical structures are needed: ectopic, impacted and supernumerary teeth, root resorption and angulations, cleft lip and palate (CL/P), alveolar boundary conditions, periodondually compromised patients, temporary anchorage devices (TADs), maxillary transverse deficiency, airway analyses, obstructive sleep apnea (OSAS), TMJ disorders and orthognathic and cranio-facial surgery.  
**Keywords:** imaging; three-dimensional; orthodontics; intraoral scan; cone-beam computed tomography; extraoral face scan; technology; dental; superimposition; virtual patient