Dental and orthopedic densitometry modeling system

Description of equivalent WO 0139667 A1

DENTAL AND ORTHOPEDIC DENSITOMETRY MODELING

SYSTEM AND METHOD

Background of the Invention

1. Field of the Invention

The present invention relates generally to dental and orthopedic diagnosis and

treatment, and in particular to a densitometry modeling system and method.

2. Description of the Related Art

The field of dental diagnostics is generally concerned with locating pathologies in

the dental structure, i.e. the teeth and surrounding tissue and bone. Three of the most

common pathologies are: 1) caries associated with decay; 2) fractures; and 3) apical

abscesses. The system and method of the present invention are primarily, but not

exclusively, concerned with detecting these pathologies and with orthopedics. Early detection of dental pathologies is very important in minimizing damage.

Conventional diagnosis procedures are generally performed using dental X-rays (both

fixed beam and scanning beam), explorers, and other conventional equipment. Incipient caries, particularly those located beneath the enamel surface, often go undetected with conventional equipment. When such caries are finally found, considerable damage to tooth structure may have already occurred. Subsurface, incipient

caries are located almost entirely within the enamel layer of the teeth. They are sometimes referred to as "smooth surface" caries and are particularly difficult to locate

using conventional diagnostic equipment and procedures. By the time such incipient

caries are located, the extent of the damage is often 17% to 23% greater than it would appear to be on a conventional X-ray negative.

Dental fractures can result from bruxism (teeth grinding), trauma, etc. Dental

structure which is weakened by various causes, such as decalcification, is particularly

susceptible to fractures. Fractures can assume various configurations, including craize

line patterns. Fracture patterns and configurations can be particularly difficult to locate

using conventional X-ray equipment and procedures. For example, fractures which are

generally parallel to the X-ray beam are often undetectable on an X-ray negative.

Undetected, and hence untreated, fractures can provide direct paths through the enamel

layer of the teeth whereby bacteria can invade the dentin and pulp layers. Pathologies in

the dentin and pulp layers are often associated with considerable pain and tooth loss.

Apical abscesses comprise yet another dental condition which can be difficult to

diagnose with conventional equipment, particularly in the early stages. Advanced apical

abscesses can cause considerable pain because they involve the neurovascular bundles

located in the root canals. Early detection of apical abscesses can lead to appropriate,

early-stage treatment, thus avoiding advanced disease processes with resultant pain, swelling, and/or space involvement which left untreated could ultimately result in death.

Tomography or sectional radiography techniques using scanning X-ray beams have previously been employed for dental applications. For example, U.S. Patents No. 4,188,537; No. 4,259,583; No. 4,823,369; No. 4,856,038; and No. 5,214,686 all relate to

dental X-ray diagnosis utilizing scanning techniques and are incorporated herein by

reference.

In the medical field, densitometry procedures are used for measuring bone

moφhology density (BMD) by utilizing scanning X-ray beam techniques. Examples are

shown in U.S. Patents No. 5,533,080; No. 5,838,765; and Re. 36,162, which are

incorporated herein by reference. Medical applications of densitometry include the

diagnosis and treatment of such bone diseases as osteoporosis.

The availability of relatively fast computers with large memories at reasonable

costs has led to the digitalization of X-ray images for mapping BMD models in various

formats. For example, BMD images use color to identify varying densities. Digital BMD

patient models are also used for comparison purposes with standard models and with

patients' own prior BMD histories. Age correction factors can be applied to patients'

models for diagnosing and monitoring the onset and progress of such medical conditions

as osteoporosis and the like. The present invention utilizes such densitometry modeling

and mapping techniques for dental applications.

In addition to pathology detection and diagnosis, the present invention has

applications in monitoring osseointegration. Osseointegration occurs at the interface between bone structures and prostheses, such as implants and replacement joints. For

example, dental implants osseointegrate with patients' dental structure. The application

of tomographical densitometry techniques to osseointegration monitoring can provide the dental or medical practitioner with important information in evaluating the effectiveness of implant procedures.

Heretofore there has not been available a system or method for applying the

technology of densitometry to dental and medical applications such as the detection of

caries and decalcification and the monitoring of osseointegration in connection with dental and medical prostheses.

Summary of the Invention In the practice of the present invention, a dental and orthopedic densitometry

modeling system utilizes a controller with a microprocessor and memory. An input

device inputs data to the microprocessor for controlling the operation of the modeling

system and for providing a database including densitometry parameters for comparison

with a patient's densitometry model. The controller controls the operation of X-ray

equipment, which is adapted for scanning patients' dental and orthopedic structures along

preprogrammed scan paths. The X-ray output is processed by the microprocessor for

creating a densitometry model, which can be output in various formats. In the practice of

the method of the present invention, a patient and the X-ray equipment are positioned

relative to each other. A controller is preprogrammed with a scan path and with data corresponding to the patient. The X-ray equipment emits and detects X-ray beams at first

and second energy levels to provide densitometry output. The densitometry output is

digitized and merged to provide a tomographic model, which can be compared to predetermined parameters unique to the patient. The model can be output in various formats, including a visual image color-coded to depict varying dental and orthopedic structure densities.

Principle Objects and Advantages of the Invention The principle objects and advantages of the present invention include: providing a dental and orthopedic diagnostic application for densitometry; providing such an application which includes a method for modeling dental and orthopedic structure using densitometry; providing such a method which includes dual-energy, X-ray emission and detection; providing such a method which includes providing a color-coded output model showing dental density; providing such a method which detects incipient caries; providing such a method which is adapted for detecting decalcification beneath the surface of the dental enamel layer; providing such a method which employs scanning X- ray techniques; providing such a method which utilizes commercially available tomography equipment; providing such a method which detects dental fractures; providing such a method which detects dental apical abscesses; providing such a method which detects dental pathologies at the micron level; providing such a method which facilitates the monitoring of decalcification in dental structures for determining appropriate treatment; providing such a method which is adaptable for monitoring osseointegration; providing such a method which can be practiced with relatively minor changes to existing densitometry equipment; and providing such a method which is

economical in operation and particularly well adapted for the proposed usage thereof.

Other objects and advantages of this invention will become apparent from the

following description taken in conjunction with the accompanying drawings wherein are

set forth, by way of illustration and example, certain embodiments of this invention.

The drawings constitute a part of this specification and include exemplary

embodiments of the present invention and illustrate various objects and features thereof.

Brief Description of the Drawings

Fig. 1 is a schematic, block diagram of a dental and orthopedic densitometry

modeling system embodying the present invention. Fig. 2 is a flowchart of a dental and orthopedic densitometry modeling method

embodying the present invention.

Detailed Description of the Preferred Embodiments

I. Introduction and Environment As required, detailed embodiments of the present invention are disclosed herein;

however, it is to be understood that the disclosed embodiments are merely exemplary of

the invention, which may be embodied in various forms. Therefore, specific structural

and functional details disclosed herein are not to be inteφreted as limiting, but merely as a basis for the claims and as a representative basis for teaching one skilled in the art to

variously employ the present invention in virtually any appropriately detailed structure.

II. Dental Densitometry Modeling System 2

Referring to the drawings in more detail, the reference numeral 2 generally

designates a dental and orthopedic densitometry modeling system embodying the present

invention. The system 2 includes a controller 4 with a microprocessor 6 connected to a

digital memory device 7. The hardware components of the controller 4, i.e. the microprocessor 6 and the memory device 7, can comprise any of a number of suitable

hardware devices which are commercially available and are suitable for this application.

In addition to various programable logic devices (PLDs) and special-puφose

microprocessors, general puφose, commercially available personal computers can be

utilized in the controller 4. The controller 4 can be programmed in any suitable manner

utilizing any of a variety of commercially available programming languages and software

development systems.

The microprocessor 6 is adapted to receive input from one or more input devices

8, such as a keyboard, a pointing device (e.g., a mouse), a communications link, or

another computer. Without limitation on the generality of useful data which can be input

via the input device(s) 8, such data can include: 1) a patient's dental and orthopedic records, including previous tomographical densitometry models; 2) baseline

tomographical densitometry models, which can be adjusted to accommodate for such factors as age, gender, size, weight, etc.; and 3) a preprogrammed scan path for the X-ray

equipment.

The microprocessor 6 controls a positioning motor 10 which is operably

connected to X-ray equipment 12 and is adapted for moving same through three axes of

movement. Examples of X-ray equipment adaptable for use with the present invention

are disclosed in U.S. Patents No. 5,533,080; No. 5,838,765; and No. Re. 36,162, which

are incoφorated herein by reference. The X-ray equipment 12 includes an X-ray beam

source 14 and a detector array 16. The X-ray beam can suitably collimated to assume any

suitable configuration, such as fan, pencil, cone, etc. With the scanning technique

disclosed, a restricted (i.e. collimated) beam is preferred. The source and the detector

array 14, 16 are adapted for positioning on either side of a patient's dental/orthopedic

structure 18. Analog signals from the detector array 16 are output to an analog-to-digital (A D)

convertor 20, from which digitized signals are transmitted to a merger device 22 for

merging into formats suitable for processing and analyzing by the microprocessor 6. The

microprocessor 6, using data from the merger device 22, creates a tomographical

densitometry model 24 which is transmitted to an output device or devices 26. Without limitation on the generality of useful output devices 26, it can comprise a monitor, a

display, a printer, a communications link, and/or another computer. For example, a color

printer can be utilized to provide a color-coded graphical representation of the

tomographical densitometry model 24. The color coding can correspond to densities, thus identifying potential problem areas where decalcification has occurred and resulted

in lower density. The tomographical densitometry model 24 can also be useful for

monitoring osseointegration, since the density of the dental/orthopedic structure 18 (tissue

and bone) in the vicinity of an implant 28 or other prostheses can provide an important

diagnostic tool for the use of the dental or medical practitioner in assessing the

effectiveness of an implant or prosthetic procedure. The tomographical densitometry model 24 is also entered into the computer's memory device 7.

III. Dental and Orthopedic Densitometry Modeling Method

Fig. 2 is a flow chart of a dental and orthopedic densitometry method embodying

the present invention. The method steps include positioning a patient and positioning the

X-ray equipment relative to the patient, i.e. with the patient's dental/orthopedic structure

to be examined located between the X-ray source 14 and the detector array 16.

Diagnostic parameters are input to the system and can comprise, for example, the

patient's prior tomographical densitometry models and standardized models. The

tomographical densitometry models can be corrected and/or adjusted to account for

patients' age, gender, physical characteristics, etc. The input diagnostic parameters can

be stored in the computer's memory device. A scan path for the X-ray equipment is

preprogrammed in the computer.

The scanning procedure is commenced by collimating a first energy band beam,

detecting emissions from same with a detector array, and converting the analog output of the detector array to a digital signal. The digital signal is output for storage in the computer. The steps of collimating the energy band beam and detecting, digitizing and

storing same are repeated for a second energy band beam. The Bisek et al. U.S. Patent

No. Re. 36,362 discloses the use of dual-energy X-ray beams in medical densitometry

applications. As discussed therein, dual-energy densitometry can result in a more

accurate patient model.

The X-ray equipment then traverses the preprogrammed scan path and the first/second energy band steps are repeated until the scanning procedure is complete. The

digitized detector array output is merged and compared to the diagnostic parameters

which are stored in the computer's memory. The dental/orthopedic densitometry is

tomographically modeled and output, for example to a monitor or printer for converting

the model to a visual image. The visual image is output in a visible form for use by

dental and medical practitioners.