Development of Autonomous Robot Osteotomy for Mandibular Ramal Bone Harvest and Evaluation of Its Accuracy: A Phantom Mandible-Based Trial  
[PERSON]  
1 Department of Oral and Maxillofacial Surgery, School of Dentistry and Dental Research Institute, Seoul National University, Seoul 03080, Korea; [EMAIL_ADDRESS]  
[PERSON]  
1 Department of Oral and Maxillofacial Surgery, School of Dentistry and Dental Research Institute, Seoul National University, Seoul 03080, Korea; [EMAIL_ADDRESS]  
[PERSON]  
2 Dental Research Institute, Seoul National University, HJS Dental Clinic for Oral and Maxillofacial Surgery, Seoul 06626, Korea 2222-2231  
First-generation surgical robots consisted mainly of robotic arms designed to assist the primary surgeon by holding and positioning instruments such as a laparoscopic camera or retractor. Surgical robots have transcended the role of assistant to become the primary surgeon's hands through a computer interface [3]. The representative model, da Vinci Surgical System (Intuitive Surgical, Inc., Sunnyvale, CA, USA), incorporates three-dimensional (3D) stereoscopic vision with two or three robotic slave arms equipped with instruments that have six degrees of freedom and wrist-like motions. The direct control robots, which are represented by da Vinci, were controlled manually while viewing the screen directly by the operator, so the robots do not need to automatically determine the position of the patient. However, in the autonomous robot, the robot determines the patient coordinates, and the operation is performed based on these coordinates. Therefore, how to effectively register the patient's coordinates is an important issue for autonomous robots. In this study, we used a robot arm guided registration technique, which is one of a direct coordinate determination system by three points. Because osteotomy is the most commonly used technique for various operations in oral and maxillofacial surgery [4], the osteotomy design was selected for our study design. Among the many osteetomies, osteotomy for ramal bone graft (RBG) is relatively difficult to approach with good visibility. Moreover, osteotomy for RBG includes cutting in various directions using various instruments [5]. Long-bone osteotomy, such as for a fibula free flap or Le Fort I osteotomy have better accessibility for the robot than the osteotomy for RBG, and are simple one-direction osteotomy examples [6; 7]. Therefore, we needed to evaluate RBG osteotomy accuracy in various directions and categories. Autogenous bone harvesting from the mandibular ramus is the first choice for reconstruction of maxillofacial defects. The mandibular ramus area has many advantages over other donor sites in the oral cavity [5]. Although the incidence of donor site complications is rare in RBG, clinicians have made efforts to reduce potential side effects. Side effects include sensory disturbances or mandibular fractures, and can lead to unnecessary patient suffering as well as significant stress for the operating surgeons. The use of robots in an osteotomy of a RBG could lead to a more accurate osteotomy and less complications, resulting in greater patient and surgeon satisfaction. However, currently, there are no commercially available robots in the field of oral and maxillofacial surgery, and there are not many ongoing studies. Autonomous robots have not yet been developed to cut the jaw bone with burs or saws. Various instruments such as rotary motor, laser, piezoelectric device [8] and waterjet [9] can be used during jaw osteotomy. Among these, the basic tools commonly used include a rotary motor with bur or saw. There are various bur types including round burs, diamond burs and fissure burs. Also, there are various types of saws, such as reciprocating and oscillating. In this study, osteotomy was performed with a fissure bur and disc saw because of the convenience for cutting bone. It is not easy to compare an osteotomy performed by a robot and one performed manually.