# Restorative Space Analysis by Jaw Motion Tracking Using a Template in Completely Edenulous Patients
## 4 Discussion  
The dental technique described herein uses a digital approach to analyze the restorative space and establish a new vertical dimension using the old denture as a target-tracking template for patients whose old dentures have worn out and have a reduced vertical dimension. A previous study proposed a target-tracking method to determine maxill-mandibular relationships in completely edentulous patients, but that method required the patient to wear headgear for recording the jaw relationships, and only static relationships were determined [17]. In contrast, our technique uses a target-tracking method to record the dynamic movements of the jaws and analyze the restorative space after determining the maxillomandibular relationship.  
The present technique of scanning the denture using a table scanner and recording the dynamic jaw movements via a target-tracking method provides various benefits. First,  
Figure 6: Trial denture designed using the denture module of the computer-aided design software with the selected vertical dimension. (**A**) Digital edentulous model. (**B**) Designed trial denture.  
Figure 7: (**A**) Printed versions of the designed trial dentures. (**B**) The patient tried multiple trial dentures, and the one with the most appropriate vertical dimension was selected.  
it reduces the number of patient visits and patient discomfort associated with conventional impression-making and recording of maxillomandibular relationships. Second, the technique records the actual trajectory of mandibular movements while opening and closing the mouth, and hence the maxillomandibular relationship can be accurately ascertained in each patient. Third, since several trial dentures with different vertical dimensions can be designed and fabricated, it is possible to evaluate the restorative space for designing a solitary attachment, bar attachment, or a conventional complete removable denture. The trial denture that best suits the patient requirements can be selected, and the definitive prosthesis can be fabricated on the basis of the associated vertical dimension. Finally, the patient's old dentures are used as a template for tracking, and lip support can be modified and/or occlusion can be established on the basis of the location of teeth in the old denture. This approach can speed up the process of patient adaptation.  
However, there are some limitations to this technique. First, discomfort when wearing the mouth retractor could interfere with natural jaw movements. Second, because target materials are applied to both arches, if the old denture has underextended borders and/or inappropriate fit of the intaglio surface, errors may be introduced owing to movement of the denture during jaw movements. Prescan relining of the intaglio surface of the denture or making conventional impressions to improve the fit and/or using an appropriate tracking template for the tissue surface may improve the accuracy of the workflow.  
The attaching of target materials on the anterior teeth as reference points in this technique enables the reproduction of real-time mandibular movements. This makes the technique useful for determining maxillomandibular relationships in cases of complete mouth rehabilitation where the vertical dimension needs to be altered. Moreover, if optical scanners that can obtain images over a wider spatial range are used to record the 3D facial data, information about anatomical features such as the midline, interpupillary line, lip contour and margin, and Camper's line can be recorded from the patient in order to design accurate prostheses. Further research is needed to determine the accuracy of the tracking and methods for reducing the number of visits and/or chair time.