WO2008050372A2

WO2008050372A2 - Odonto-navi-robot for precision positioning implants in the oral cavity

Info

Publication number: WO2008050372A2
Application number: PCT/IT2007/000749
Authority: WO
Inventors: Guido A. Danieli; Francesco Giuzio; Demetrio Moschella
Original assignee: Calabrian High Tech Srl
Priority date: 2006-10-27
Filing date: 2007-10-26
Publication date: 2008-05-02
Also published as: EP2111178A2; WO2008050372A3

Abstract

The present invention describes a guiding system for precision positioning of the implants in the oral cavity. Presently implant positioning is performed manually by the doctor and requires high skill, having to take into account both position in which the implant should be placed for optimal prosthesis support, but also, even more importantly, of the amount of bone stock available. Purpose of the present invention is to supply a guide to precision position in predetermined positions on the base of a CAT scan, in order to insure reaching both objectives. The equipment integrates a Navigator-Robot system which is able to move along the denture's plane in order to detect the denture's CAD model, and allows to rotate in two directions a slide made for guiding the micro motor in the direction pre-established, being placed on the same planar 2 DOF system quoted above, able to be used both in active and passive mode, and being the entire 2 + 2 DOF system fixed to the head or the jaw of the patient using a 6 DOF self balanced system. Finally such 2 DOF system to control inclination may consist both in a serial or in a parallel robot, being the last probably preferable for its greater rigidity and precision control.

Description

Odonto-Navi-Robot for precision positioning implants in the oral cavity General description of the field of interest.

Presently, dental implant positioning is generally performed manually by the dental surgeon, and requires a great ability and experience, since it is necessary to take into account both of the optimal position for the correct support of the prosthesis, and, even more importantly, of the amount of bone stock available in the position selected for positioning the implant. This is usually obtained by a CAT scan or by an orthopantomograph The surgery is in any case difficult and not always successful. The present invention is aimed to supply the doctor the possibility to preliminarily determine, navigating in a CAD representation of the patient mouth, which should display the positions of the teeth, of the gums, and of bone stock, the best inclination with respect to the denture plan in which implants should be fixed. To this end it is necessary to utilize a self balanced system, and of a and a system to fix it to the superior or inferior denture (an adjustable mask which can rest on some of the teeth or on the gums being strapped to the head or the chin, defining a plane parallel to the denture), on which a second mechanism is posed, able to move both in active and passive mode along the plane of the teeth, on which a third mechanism is placed that allows to control the angle of drilling in two directions, while penetration is controlled by the doctor that drives the micro motor along a slide in the predetermined position. Description of the preferred embodiment.

In particular the system for precision positioning implants in the oral cavity will be composed, in the preferred embodiment, by a self balanced serial/parallel structure (Figure 1) composed by a sequence of constrains in which the first hinge of horizontal axis (1) is part of a plane four bar link in which the upper link extends on the opposite side with respect to the four bar link to support a counterweight (7), while the second (2), third (3) further hinge (5) having horizontal axis, whose axis is divided in two semi axes that connect the joint's fork to the sixth member, hollow, that hosts the axis of the sixth joint, generating a spherical hinge (last three axes meet in a single point). However the presence of this system is not compulsory in order to produce this equipment. As far as the system of connection to the dental arcade (upper or lower) it is made by a mask (9 of Figure 2) sitting through wires to the top of the denture (10) or through special supports on the gum's surface, and blocked with straps to the head or the chin, so defining a plan parallel to the dental arcade. The anterior part of the mask (11) is to be fixed to the 7^th link of the self balancing structure. Passing to the following characterizing element, the Navigator Robot on the horizontal plane (x, y), in each of the two directions it will be made by two perpendicular prismatic joints (12 and 13 of figure 3) having each in parallel both a position measuring device (14) and a threaded bar (15), (16 of Figure 4), activated by a step motor, and whose angular position may be determined by an incremental encoder with reference trigger (17), and whose female screw (18), composed by a single element, can be pressed between two planar surfaces (19) rotating a cam (20) which can be activated rotating a motor. Fundamental is to use a system allowing to vary the inclination of the implant with respect to the plane of the dental arcade, in order to optimize both bone stock utilization, taking also into account the prevailing directions of the load. To this purpose it is necessary to have the possibility to rotate in a controlled way the direction of the implant along two perpendicular directions laying on the oral cavity plane (the x and y axes quoted above). In order to do so two mechanisms to control the inclination of the micro motor axis have been proposed in the two patent applications of which priority is claimed, that can substantially be considered a serial and a parallel robot, both having two degrees of freedom. The first of these mechanisms (figure 5) is a four bar link with opposed parallel bars (21), mounted on an axis (22) rotating on hinges (23), whose rotation in the plane (x, z) is controlled by a first step motor, while rotation of the four bar link in the plane (y, y') is controlled by a second step motor positioned on a parallel axis (24) through two pair of gears the second of which is conical (25). The second non horizontal bar of the four bar link contains a slide (26) driving perforation using the implant micro motor, while motion on the slide is surgeon's responsibility.

The second mechanism proposed, shown in figure 6 as seen from the top and the side, is a three member system, beside the frame. Main advantage of a parallel robot is its greater rigidity. Many are the possible configurations of a DOF robot, but it is easy to propose other configurations. In any event it is claimed that any two DOF parallel robot applied to implant positioning derives from the present invention. Passing to the preferred configuration, the first member (28) is a platform supporting the slide (29) driving the micro motor constrained by a double hinge (30) having perpendicular axes (a universal joint), that allows rotating the platform in two directions. On the other side the platform is hinged to two spherical hinges (31, 32) coupled to two bars, each constrained to a slider whose position is controlled by a threaded bar moved by step motors (33, 34). As in the previous case, the slide (29) guides the micro motor (35) which is driven by the surgeon. The implantation procedure is the following: starting from a CAT scan operating in virtual reality the optimal position of the implants is determined. Then the mask is installed on the patient denture, is fixed with straps and the equipment connected. At this point, with the prismatic joints (x, y) in navigation mode and the 2 DOF robot in vertical position, the doctor, with a probe substituting the micro motor touches pre-selected repere points on the denture, identifying the in the CAD representation of the mouth. From this the correspondence between reality and virtual model is established, and the system is able to drive, in robot mode, implant installation in the pre selected positions.

Claims

Claims:

1. Equipment for precision positioning of the implants in the oral cavity, composed by a system that allows moving along the plane of the denture, in two directions both in passive mode (Navigator) and active (Robot), on which a further micro-robot able to change in a controlled way inclination of the implanter micro motor in order to guide the hole preparation and the following fixation of the implant exactly in the predetermined position, being the equipment positioned on an arm and fixed to the patient head, being this supporting arm possibly self balanced and able to move following the head's motion.

2. hi particular the equipment described in claim 1, will be moved, with respect to the patient's mouth, through a pair of threaded bars controlled by step motor, allowing moving the slide in the denture plane along two perpendicular directions, driven by suitable prismatic joints, or by any other system of motion that should be rigid enough.

3. hi particular the equipment described in claim 1, will bear a couple of absolute linear measuring devices, placed on the side of the madreviti, in order to detect the exact relative position of each tooth during the navigation phase, while the position will be controlled by step motors during the robotized phase.

4. hi particular the equipment described in claim 1, will bear a system able to control the angle of drilling of the implanter micro motor in two perpendicular directions, in order to assume the angle desired by the doctor.

5. hi particular the 2 DOF system of regulation described in claim 4 may consist both in a parallel robot and in a serial robot.