Use of Virtual Reality in Removable Prosthodontics

 Use of Virtual Reality in Removable Prosthodontics

            Virtual reality is a three dimensional (3D) environment that is stimulated to provide the user with a sensation of being inside, controlling, and interact with it ⁽¹⁾. Simply put, it is an immersive, interactive, multi-sensory, viewer-centered, 3D computer-generated environments, and the mixture of technologies needed to create these environments. According to Joda ⁽⁴⁾, virtual reality allows the user to navigate and view a world of three dimensions in real-time. Essentially, it is a clone of physical reality that establishes a virtual habitat to replace the environment of the real world ^{(1), (12)}. In prosthetic and restorative dentistry, the virtual dental articulator integrates the use of virtual reality to the dental practice for the evaluation of multifaceted static and dynamic occlusal relations.  The virtual articulator refers to software that combines virtual reality technology to improve clinical outcomes ⁽¹⁰⁾.  It should be noted that the virtual articulator needs digital 3D representations of the jaws and particular data of the patients regarding the movements of jaws. This device then stimulates the movements of jaws and gives a quick visualization of the occlusal contacts.

The Glossary of Prosthodontics terms eighth edition defines an articulator as a mechanical device that represents the temporomandibular joints and jaws that attaches the maxillary and mandibular casts to simulate the movements of mandibular ⁽¹¹⁾. With the application of semi-adjustable mechanical articulators, it is difficult for a person to reproduce the mandibular movements with related timeframes ^{(10), (11)}. The solution to these dilemmas involves the replacement of mechanical articulator with its computerized replication such as virtual articulator. This instrument can indicate and quantify the effects of soft tissue resilience on a time-dependent basis during muscular movements. 

That is why virtual articulator can demonstrate the actual time dynamics of the occlusion. Its primary function is to generate mandibular movements according to the input data and calculate the occlusion points ⁽⁶⁾. This device is essential in removable prosthodontics because it provides effective communication between the dental technician and the dentist; acts as a 3D navigator; simulates specific data of the real patient; and evaluates static and dynamic occlusions ^{(5), (6),(7)}

Virtual reality is also applied in prosthodontics to assist in planning for prosthodontics surgery. A 3D virtual surgery and mandibular reconstruction after cancer resection are the primary applications of VR in prosthodontics. Virtual planes for maxillary and mandibular reconstruction can be attained as an excellent match. A study by Huang et al. ⁽²⁾demonstrated 30 cases if the complex head and neck reconstruction including the resection planes, the segmental defect length and the distance between the remaining bone and the transplanted segment and found a perfect match between the virtual plans and the achieved outcomes⁽⁶⁾. In dental implantology, the precise placement of dental implants is significant in achieving functional and aesthetic requirements.

Virtual reality is extensively applied using the preoperative Cone-beam Computed Tomography (CBCT) to identify the size, direction, position, and proximity of the implant to the vital structures⁽⁵⁾.  CBCT or digital volume topography is a 3D radiographic imaging of the craniofacial imaging. The virtual planning of dental implants is done using various software packages ⁽⁶⁾. The 3D virtual plan is the movement to the surgical field through a static guide or the dynamic navigated approach.  The static transfer relies on virtual designing and the fabrication of the surgical guide that used CAM/CAD to simplify the insertion of dental implants. Dynamic navigation enables the real-time adjustment of the dental implant direction during surgery. ⁽⁸⁾

One of the primary benefits of the dynamic navigation is the flexibility of the operator to change the position of the implant for the avoidance if compromised bony foundation and anatomical structures that the surgeon may fail to detect during the pre-surgical stage. ⁽⁴⁾  Researchers have reported increased accuracy with the image guide implantology (IGI) system. Nonetheless, it must be noted that this technology needs costly hardware and a rigorous orientation process. Moreover, a disrupted surgical process may occur as a result of the blockage of the sensors during the navigation procedure⁽⁹⁾. Undoubtedly, Virtual reality technology has created a new skyline in the management of critical cases where the anatomy of the jawbones has been changed due to pathology. ⁽¹²⁾  Simply put, it improves the anatomy of implant placements that requires minimal surgery. Navigation within the virtual environment has been used successfully during prosthodontics surgery for the relocation of the maxilla.

In removable prosthodontics, the virtual articulator increases integrated with CAM/CAD technology provides a high possibility in treatment planning with dental implants because it affords high precision and reduces the duration of implant treatment. ⁽¹¹⁾  With the help of the VR, the virtual articulator has been related to mechanical articulator in prosthodontics surgery as it creates an ideal maxillary position and prepares surgical splints. Therefore, the VR can correctly produce conventional planning and help surgeons obtain excellent results.

The differentiation between structures and the speed of the instrument is possible with the help of haptic. Haptic is a sensing and manipulating technology that stimulates the senses of touch and motion. ^{(7), (8)} It enables the user to touch and feel the force needed for each practice (force feedback) and provide a realistic tactile sense ⁽⁸⁾. In dental surgery, haptic devices allow prosthodontics to touch and feel objects like surgical tools and human organs in a virtual environment. They also will enable the surgeon to conduct operations such as pulling, pushing, and cutting soft or hard tissues with the force feedback. ⁽⁹⁾

A 3D haptic technology of VR has introduced dental simulators that provide a reliable mechanism to efficiently inform prosthodontics about dental procedures while improving their hand-skills needed for dental procedures. ⁽¹⁰⁾  Repetitive procedures like instrument usage and placement and proper hand are the primary targets that prosthodontists must know on dental simulators. There are two types of dental simulators that are presently available. They include manikin-based simulators and haptic-based simulators ^{(4), (6)}. Manikin-based simulators provide a physical model of the head and mouth of the patient where specific dental can be carried out using real dental instruments such as DentSim ⁽⁸⁾. In contrast, haptic-based simulators utilize a PHANToM haptic device and virtual models of the tooth or mouth of a person to facilitate dental practices.

Instead of using real dental devices, the prosthodontists hold the haptic instrument to manipulate virtual instruments displayed on the monitor screen. The tactile feedback generates clinical sensations in the operator’s hand ⁽¹¹⁾. VR simulators are also programmed to detect errors and evaluate performance quality. As such, prosthodontists use them to determine the mistakes and the best performances, which form the foundation for the comparison and analysis. The system can record and replay the user’s performances, thus, enabling them to identify their weaknesses and fix them. ^{(3), (5)}

The significant application of VR in removable prosthodontics is used in computer-aided-design/Computer-aided manufacturing (CAD/CAM) restorations and esthetic planning. It assists in designing the restorations. Haptic-based first touch-enabled virtual articulator provides dental labs even more choice and increases the performance and flexibility of prosthodontists to fabricate various dental restorations. Besides, intellift’s unique 3D virtual touch interface combined with integrated touch-enabled articulator enables surgeons to feel how the teeth will fit together in the mouth of the patient. Articulators help in testing the occlusion of every kind of dental restoration. During treatment, prosthodontists use them to determine whether restoration will enable the patient to operate with the correct amount of contact and excursive movements.

Besides, VR is used in dental implantation, temporomandibular joint motion analysis, maxillofacial surgery, and prosthetic surgery.  Its application in oral and maxillofacial surgery is in the visualization of deep masked structures ⁽²⁾.  Before surgery, the operator maps the surgical plan on the 3D image of the site and determine any significant modification.  During operation, the prosthodontist views and follows the mapped model using specialized glasses. ⁽³⁾

Conclusion

Virtual reality is a useful technology for prosthodontists as it helps them to successfully diagnose and treat dental patients with the help of virtual articulator. The virtual articulator is specific software that deals with the operational aspects of occlusion to avoid errors in dental care. VR technology has opened for prosthodontists towards successful diagnosis and treatment planning with the help of virtual articulator in everyday dental procedures. Haptic-based virtual reality system’s touch-enabled virtual articulators’ enables prosthodontics to feel how the teeth will fit in the mouth. In removable prosthodontics, VR is also used to predict treatment realistically. The navigation systems help in obtaining improved results in implantology and maxillofacial surgery. VR assists in exact diagnosis and calibration or dental procedures. Prosthodontists prefer it because it saves time.

Reference List

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