# Restorative Space Analysis by Jaw Motion Tracking Using a Template in Completely Edenulous Patients
###### Abstract  
Improvements in computer-aided design/computer-aided manufacturing technologies have led to multiple attempts being made to simplify and improve the workflow of prosthesis fabrication for completely dedentulous patients. However, most attempts still involve the conventional methods of impression-making and recording the maxillomandibular relationships using alginate, rubber impression materials, and wax materials. In the case of a completely dedentulous arch, the presence of movable tissues and the absence of stable landmarks make it difficult to perform direct digitization using an intraoral scanner and to digitally determine the vertical dimension. In the alternative technique described herein, data are obtained by scanning a template such as the patient's existing old dentures and jaw movement data using target materials and an optical scanner, and an appropriate maxillomandibularul relationship that has the desired restorative space is determined on the basis of the obtained trajectory of mandibular movements while opening and closing the mouth. After designing dentures on the basis of the newly established maxillomandibularul relationships and performing a try-in process, the final dentures can be manufactured. This alternative technique can reduce the need for multiple visits and complex procedures, improving the workflow for fabricating prostheses with the correct maxillomandibularul relationships for individual patients.  
target tracking; completely dedentulous patient; digital dentistry; CAD/CAM; complete removable denture; vertical dimension; restorative space analysis +
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artificial teeth on the basis of both muscular and phonetic considerations [4]. Various types of commercial workflow systems for applying digital methods to treat completely edentulous patients were introduced in the 2010s as solutions to the considerable hindrances in the digital fabrication of complete removable dentures, including the AvaDent Digital Denture (Global Dental Science, Scottsdale, AZ, USA), Dentca CAD/CAM System (Dentca, Los Angeles, CA, USA), and Baltic Denture System (Merz Dental, Lutjenburg, Germany) [5]. These methods can produce complete removable dentures with fewer patient visits [6], but they are primarily based on conventional impression-making procedures using impression materials. In addition, since the maxillomandibular relationship could not be determined digitally, the traditional method using record bases and wax occlusion rims was used before scanning the edentulous models and their relationships [7].  
Various methods for tracking jaw movements utilizing mechanical, electromagnetic, and ultrasonic devices have been introduced recently [8; 9; 10; 11]. Although several methods for transferring jaw movement data into digital software have been suggested [12], they require the patient to wear bulky equipment, which interferes with natural jaw movements and is also uncomfortable, restricting their clinical application. A target-tracking method has been described to overcome these limitations, wherein target materials and an optical scanner are used to scan jaw movements, and the data are overlaid onto a full arch model using reference points [13; 14; 15; 16]. This approach is more rapid than conventional methods, is conducive to patient comfort and natural movements, and does not involve exposure to ionizing radiation [13; 14; 15; 16]. However, within the limits of the author's knowledge, no technical note has yet been reported that analyzed the restoration space of a complete edentulous patient using the jaw motion tracking technique and attempted vertical dimension alteration.  
The present study applied a technique in which target materials attached to the anterior teeth and an optical scanner for target tracking are used to record the trajectory of mandibular movements while opening and closing the mouth--the envelope of function--in completely edentulous patients for the evaluation of restorative space and its use in the subsequent prosthetic treatment plan.