FIELD OF THE INVENTION

This invention relates to a system and method for providing feedback information that facilitates and that may provide guidance for prosthodontic procedures in the intra oral cavity, i.e., procedures involving the installation and definition of dental prostheses. In particular, the invention relates to such systems and methods that are computerized.

BACKGROUND

Prosthodontics is the dental specialty concerned with artificial replacements of missing parts of the mouth and jaws, in particular of teeth and parts thereof.

In prosthodontic procedures designed to implant a dental prosthesis in the intra oral cavity, the dental site at which the prosthesis is to be implanted in many cases needs to be measured accurately and studied carefully, so that a prosthesis such as a crown or bridge, for example, can be properly designed and dimensioned to fit in place. A good fit is of the highest importance to enable mechanical stresses to be properly transmitted between the prosthesis and the jaw, and to prevent infection of the gums and so on via the interface between the prosthesis and the dental site.

mechanical stresses to be properly transmitted between the prosthesis and the jaw, and to prevent infection of the gums and so on via the interface between the prosthesis and the dental site.

In the prior art, the dental site is prepared by the dental practitioner, and a positive model of the site is constructed using known methods. Alternatively, the dental site may be scanned to provide 3D data of the site. In either case, the virtual or real model of the site is sent to the dental lab, which manufactures the prosthesis based on the model. However, if the model is deficient or undefined in certain areas, or if the preparation is not optimal for receiving the prosthesis, the dental technician has a more difficult job ahead than otherwise, and may result in less than optimal design for the prosthesis. In some circumstances, the model is rejected and the dental practitioner must re-scan the dental site, or must rework the preparation, so that a suitable prosthesis may be produced.

SUMMARY OF THE INVENTION

Herein, “dental material” refers to any material associated with dental structures of the intra oral cavity, including but limited to natural dental materials such as for example enamel, dentine, pulp, dental roots, and non-natural dental materials such as for example metallic and non-metallic filings, restorations, crowns, bridges, copings, preparations, and so on.

Herein, “dental clinic” refers to the interface between a dental practitioner and a patent, and thus includes any physical entity, in particular a clinic, in which there is interaction between a dental patient and a dental practitioner. While “dental practitioner” typically refers to a dentist, doctor or dental technician, it also includes herein all other caregivers that may interact with a dental patient during the course of a dental treatment. While “dental patient” typically refers to a person requiring the dental services of a dental practitioner, it also includes herein any person regarding whom it is desired to create a 3D numerical model of the intra oral cavity thereof, for example for the purpose of practicing the same or for carrying out research.

The term “prosthesis” is herein taken to include any restoration or veneering, including any onlays, such as crowns and bridges, for example, and inlays, such as caps, for example, and any other artificial partial or complete denture.

While the term “preparation” typically refers to the stump (including the finish line and shoulder) that is left of the tooth that is to be replaced by the prosthesis—typically a crown—and on which the crown is to be mounted, the term herein also includes artificial stumps, pivots, cores and posts, or other devices that may be implanted in the intraoral cavity in such a position or in a position that is optimal for implanting the crown.

The term “prosthodontic procedure” refers, inter alia, to any procedure involving the intraoral cavity and directed to the design, manufacture or installation of a dental prosthesis at a dental site within the intraoral cavity, or a real or virtual model thereof, or directed to the design and preparation of the dental site to receive such a prosthesis.

The term “numerical entity” is used herein synonymously with virtual model and other such terms, and relates to a virtual representation of a real object, typically a dentition or at least a part of intraoral cavity, or of a real model thereof, for example.

The present invention, in a first aspect thereof, relates to a method for providing feedback data useful in at least one prosthodontic procedure associated with the intra oral cavity, comprising:

(a) providing at least one numerical entity representative of the three-dimensional surface geometry of at least part of the intra-oral cavity;

(b) manipulating said entity to provide desired data of a type useful in at least a first said procedure;

(c) determining at least one relationship between said desired data and said first procedure; and

(d) generating feedback data representative of said at least one relationship.

Typically, in the said prosthodontic procedure, dental material has been previously removed from said part of the intra-oral cavity by means of a second procedure.

Optionally, step (c) comprises testing an adequacy of said desired data for performing said first procedure according to at least one predetermined parameter, and step (d) comprises generating feedback data representative of said adequacy.

The method is typically directed at a said first procedure comprising mounting at least one dental prosthesis with respect to a dental preparation comprised in said intraoral cavity and provided prior to step (a).

In a first embodiment of the invention, said desired data relates to the geometry of a finish line associated with said dental preparation. Step (c) comprises determining whether or not the said finish line geometry is suitable for receiving a prosthesis according to predetermined parameters; said feedback data in step (d) comprises a suitable message advising whether or not said finish line geometry is suitable, according to said determination in step (c). In step (c) it may be determined that the said finish line geometry is not suitable for receiving a prosthesis according to predetermined parameters, and in such a case the method may further comprise the step:

(e) providing suggested changes to said finish line geometry such as to provide a new finish line geometry that is suitable for receiving a prosthesis according to predetermined parameters.

The suggested changes may be calculated according to predetermined rules. Further, the suggested changes may be displayed on a two-dimensional representation of said dental preparation, wherein said new finish line geometry is superimposed over said representation. The location of said existing finish line geometry may be highlighted with respect to said new finish line geometry.

The method may further comprise repeating steps (a) to (d) after further material has been removed from the preparation to conform a finish line thereof to said new finish line geometry.

The method may further comprise repeating steps (a) to (d) concurrently with each step of a material removal operation, said material removal operation being adapted to conform a finish line of said preparation to said new finish line geometry, wherein step (e) is performed at each step of said material removal operation.

In a second embodiment, the desired data relates to an insertion path geometry for said prosthesis with respect to said dental preparation and surrounding dental tissues. Step (c) comprises determining whether or not the said insertion path geometry is suitable for enabling said prosthesis to be mounted with respect to said dental preparation. The feedback data may comprise a suitable message advising whether or not said insertion path geometry is suitable, according to said determination in step (c). In step (c) it may be determined that the said insertion path geometry is not suitable for receiving a prosthesis according to predetermined parameters, and the method may then further comprise the step:

(f) providing suggested changes to said dental preparation such as to provide a new insertion path geometry that is suitable for receiving a prosthesis according to predetermined parameters.

The suggested changes may be determined on the basis of identifying overlapping areas between the prosthesis and the preparation, and providing guidance as to corresponding changes required in at least one of said prosthesis and said preparation. Further, the suggested changes may be displayed on a two-dimensional representation of said dental preparation, wherein said new insertion path geometry is superimposed over said representation.

The method may further comprise repeating steps (a) to (d) after further material has been removed from the preparation to conform said preparation to said new insertion path geometry.

The method may further comprise repeating steps (a) to (d) concurrently with each step of a material removal operation, said material removal operation being adapted to said preparation to said new insertion path geometry, wherein step (e) is evaluated at each step of said material removal operation.

The prosthesis in the second embodiment of the invention is typically a crown or bridge.

In a third embodiment of the invention, the desired data relates to at least one predetermined dimension between said dental preparation and said prosthesis. Step (c) comprises determining whether or not the said at least one dimension is suitable for enabling a prosthesis to be received according to predetermined parameters. The at least one dimension typically relates to a characteristic thickness of said prosthesis. The said prosthesis may comprises a ceramic cap that is mountable over a metal coping bonded to said preparation, or a porcelain fused to metal (PFM) cap, for example.

The feedback data typically comprises a suitable message advising whether or not said at least one dimension is suitable, according to said determination in step (c). In step (c) it may be determined that the said at least one dimension is not suitable for receiving a prosthesis according to predetermined parameters, and further comprises the step:

(e) providing suggested changes to preparation geometry such as to provide a dimension that is suitable for receiving a prosthesis according to predetermined parameters.

The suggested changes may be determined taking into consideration the type of prosthesis to be implanted at said preparation. The suggested changes may be displayed on a two-dimensional representation of said dental preparation, wherein said changes to preparation geometry are superimposed over said representation.

Optionally, the method may further comprise repeating steps (a) to (d) after further material has been removed from the preparation to conform said preparation to said new preparation geometry.

Optionally, the method may further comprise repeating steps (a) to (d) concurrently with each step of a material removal operation, said material removal operation being adapted to conform said preparation to said new preparation geometry, wherein step (e) is evaluated at each step of said material removal operation.

For all embodiments, step (a) is typically performed by scanning said at least part of said intra oral cavity using a suitable 3D surface scanner.

According to a second aspect of the invention, in step (c) said relationship may be insufficiently determined due to incomplete definition of numerical entity provided by step (a). The method may then further comprise the step of determining the location of at least one area of said intra oral cavity where 3D definition thereof is required for enabling step (c) to be performed. Said determination of the location of said at least one area may be performed by suitable algorithms. The said at least one area is displayed on a two-dimensional representation of said dental preparation, wherein said at least one area is superimposed over said representation.

The prosthesis typically comprises any one of an inlay, onlay, crown, bridge or restoration.

Optionally, step (b) comprises simulating said procedure first with respect to said numerical entity to provide said desired data.

According to the second aspect of the invention, step (a) comprises the steps of:

scanning a part of said intra-oral cavity to provide a 3D numerical entity thereof;

determining whether a definition of said 3D numerical entity is sufficient for enabling step (c) to be performed;

if said definition is insufficient, advising a user to continue scanning a different part of said intra-oral cavity, and repeating step (ii) until said definition is sufficient, wherein step (v) is performed;

if said definition is sufficient in step (ii), proceeding with step (v);

advising a user that said definition is sufficient, and proceeding with steps (b) to (d).

Optionally, in step (a), said numerical entity further comprises color data of said part of the intra oral cavity, and step (b) comprises differentiating parts of said entity according to whether the said color associated therewith is correlated with soft tissues or hard tissues of the intra oral cavity.

Optionally, step (a) may be performed in one location, and at least one of steps (b) to (d) may be performed in at least one different location.

Optionally, step (d) is provided substantially in real-time with respect to step (a), or within a short time period thereof, typically in the order of seconds or fractions of a second.

According to the second aspect of the invention, a method of providing feedback data useful in at least one prosthodontic procedure associated with the intra oral cavity, comprises:

(i) providing at least one numerical entity representative of the three-dimensional surface geometry of at least part of the intra-oral cavity that has been previously modified by means of a first part of said procedure;

(ii) manipulating said entity to provide desired data useful in at least a second part of said procedure;

(iii) testing adequacy of said desired data for performing said second part of said procedure; and

(iv) generating feedback data representative of said adequacy.

Typically, the first part of said procedure comprises a dental material removal operation in said intra-oral cavity. Further typically, step (ii) comprises manipulating said entity to determine sufficiency of definition of said numerical entity in step (i) with respect to said first said procedure, and providing sufficiency data representative of said sufficiency, and step (iii) comprises determining at least one relationship between said sufficiency data and said first procedure. In one application of the method according to the second aspect of the invention, the desired data may relates to a measure of surface data definition of said entity.

In the third aspect of the invention, the feedback data is essentially used in an interactive manner together with a material removing process to facilitate the performance of a procedure with respect to the intraoral cavity.

The present invention also relates to a system for providing feedback data useful in at least one prosthodontic procedure associated with the intra oral cavity comprising:

(A) scanner means for providing at least one numerical entity representative of the three-dimensional surface geometry of at least part of the intra-oral cavity;

(B) microprocessor means for manipulating said entity to provide desired data of a type useful in at least a first said procedure, and for determining at least one relationship between said desired data and said first procedure; and

(C) output means for outputting feedback data representative of said at least one relationship generated by said microprocessor means.

The scanner may comprises a confocal scanner, for example. Preferably, the scanner comprises a capability for providing color data as well as geometrical data of a surface. Typically, the output means comprises a visual and/or audio display means. The microprocessor means is adapted for operation according to the method of the invention.

