WO2001032096A2

WO2001032096A2 - Method and device for taking measurements in a patient's fully edentulous jaw

Info

Publication number: WO2001032096A2
Application number: PCT/ZA2000/000202
Authority: WO
Inventors: Zakaria Gordon-Fatagodien
Original assignee: Technikon Pretoria
Priority date: 1999-11-02
Filing date: 2000-10-26
Publication date: 2001-05-10
Also published as: AU1108001A; WO2001032096A3

Abstract

This invention relates to a method of taking measurements in apatient's fully edentulous jaws for use in the manufacture of dentures. The method includes the step of, with the jaws at 180°, measuring the distance from a central position between the lips to at least one externally visible landmark on the patient's face corresponding to a predetermined position on one of his jaws. This invention extends to a dental registration device (10) for use in the manufacture of dentures. The device (10) includes an elongate reference member (14) which can be positioned in register with a point which is between a patient's lips. The device further includes at least one landmark registration element (16, 18) which is displaceable relative to the reference member (14) in order that it may be brought into register with an externally visible landmark on the patient's face and the distance between the reference member (14) and the landmark registration element (16, 18) measured.

Description

A METHOD OF TAKING MEASUREMENTS IN A PATIENT'S FULLY EDENTULOUS JAWS

THIS INVENTION relates to dentistry. More particularly it relates to a method of taking measurements in a patient's fully edentulous jaws and to a method of determining the correct placement of teeth in a set of dentures. It also relates to a dental registration device and to upper and lower measuring means.

When manufacturing dentures for a patient it is important that certain dimensions of the dentures are accurate and consistent with the configuration of the patient's mouth. However, difficulties are encountered when taking measurements of the jaws of a fully edentulous patient since limits on jaw movements imposed by a person's natural teeth are no longer present.

It is an object of this invention to provide means which the Inventor believes will at least alleviate this problem.

According to one aspect of the invention there is provided a method of taking measurements in a patient's fully edentulous jaws for use in the manufacture of dentures, which method includes the step of, with the jaws at 1 80 degrees, measuring the distance from a central position between the lips to at least one externally visible landmark on the patient's face corresponding to a predetermined position on one of his jaws. The jaws are regarded as being at 1 80 degrees when the muscle groups controlling the opening and closing of a patient's jaws and lips are in a relaxed state. In this position the natural teeth of a patient, were they present, would be spaced apart. This space between the natural teeth is referred to as the "freeway" space and is typically of the order of 3 mm.

Preferably, the method includes measuring the distance from between the lips to at least two externally visible landmarks, one of which corresponds to a predetermined position on the patient's upper jaw and the other of which corresponds to a predetermined position on the patient's lower jaw.

The measurements then permit the incisal height of the upper and lower jaws to be calculated and for those measurements to be transferred to upper and lower bite blocks used in the manufacture of dentures.

The one landmark may be the base of the nose, which corresponds to the sulcus area on the upper jaw.

The other landmark may be the base of the indentation between the lower lip and the chin, which corresponds to the sulcus area on the lower jaw.

The method may include measuring the angle of the Ala- tragus line thereby permitting dentures to be manufactured with a slope which would correspond generally with a slope of a patient's natural teeth were they present. According to another aspect of the invention there is provided a method of determining the correct placement of anterior teeth in a set of upper dentures which includes the step of measuring the distance from an inner surface of a patient's upper lip to the incisive papilla and transferring this information to an upper bite block.

According to still another aspect of the invention there is provided a method of determining the correct placement of the lower anterior teeth in a set of dentures which includes the step of measuring the distance between an inner surface of a patient's lower lip and the anterior part of the lower ridge and transferring the measurement to a lower bite block.

According to another aspect of the invention there is provided a dental registration device for use in the manufacture of dentures, which device includes an elongate reference member which can be positioned in register with a point which is between a patient's lips; and at least one landmark registration element which is displaceable relative to the reference member in order that it may be brought into register with an externally visible landmark on the patient's face and the distance between the reference member and the landmark registration element measured.

In a preferred embodiment to the invention, at least part of the reference member is receivable between a patient's lips and the device includes two landmark registration elements which are relatively displaceable to and positioned on opposite sides of the reference member. The device may include an elongate spine from which the reference member and landmark registration elements protrude generally parallel to one another, the landmark registration elements being longitudinally displaceable along the spine. The device may include locking means, e.g. in the form of set screws, whereby the landmark registration elements are releasably lockable to the spine.

The spine may include a graduated linear scale from which the spacing between the reference member and the landmark registration elements can be read off.

The device may include a chin engaging member which protrudes from the spine.

The device may include a level, e.g. a spirit level. The level may be mounted on the chin engaging member.

The device may include Ala-tragus measuring means. The Ala-tragus measuring means may include an angularly displaceable pointer which is connected to and angularly displaceable relative to the spine. The pointer may be telescopic in order that its length is adjustable. The device may include an angular scale whereby the angular spacing of the pointer relative to a reference plane can be read off.

The reference member may be connected or connectable to the pointer for angular displacement together with the pointer. The reference member may be longer than the landmark registration elements such that, in use, a portion of the reference member is positionable or positioned in a patient's mouth. At least part of at least that portion of the reference member which is intended to be positioned in patient's mouth may have a thickness of about 3 mm.

The device may include a bite fork which is disconnectably connectable to the reference member.

The device may further include upper measuring means for measuring the distance between an inner surface of a patient's upper lip and his incisive papilla, the upper measuring means being dismountably mountable on the reference member.

The upper measuring means may include a base which is dismountably mountable on the reference member, an upper lip engaging formation and an incisive papilla engaging member mounted on the base such that the spacing therebetween is adjustable.

The upper lip engaging formation may be formed integrally with the base and the incisive papilla engaging member may be slidably mounted thereon.

The device may include a lower measuring means for measuring the distance between an inner surface of a patient's lower lip and the anterior part of his lower ridge, the lower measuring means being dismountably mountable on the reference member.

The lower measuring means may include a base which is dismountably mountable on the reference member, a lower lip engaging formation and a lower ridge engaging member mounted on the base such that their relative spacing is adjustable. The lower lip engaging formation may be formed integrally with the base and the lower ridge engaging member may be slidably mounted thereon.

According to still another aspect of the invention there is provided upper measuring means, for measuring the distance between an inner surface of a patient's upper lip and his incisive papilla, which includes mounting means for dismountably mounting the upper measuring means on a dental registration device.

According to yet another aspect of the invention there is provided lower measuring means, for measuring the distance between an inner surface of a patient's lower lip and the anterior part of his lower ridge, which includes mounting means for dismountably mounting the lower measuring means on a dental registration device.

The mounting means may be configured so that the measuring means is dismountably mountable on the reference member of a dental registration device of the type described above.

The invention will now be described, by way of example, with reference to the accompanying diagrammatic drawings.

In the drawings, Figure 1 shows a three-dimensional partially exploded view of a dental registration device in accordance with the invention;

Figure 2 shows schematically the device of Figure 1 in use; Figure 3 shows a three-dimensional exploded view of upper and lower measuring means mountable on a reference member of a dental registration device in accordance with the invention; and

Figure 4 shows a three-dimensional view of a bite fork which is disconnectably connectable to the reference member of the device of Figure 3.

In Figures 1 and 2 of the drawings, reference numeral 10 refers generally to a dental registration device suitable for use in a method of taking measurements in a patient's fully edentulous jaws in accordance with the invention.

The device 1 0 includes an elongate spine 1 2 and an elongate reference member 1 4 which protrudes from the spine 1 2. In addition, the device 10 includes an upper landmark registration element

1 6 and a lower landmark registration element 1 8 which are slidably mounted on the spine 1 2 on opposite sides of the reference member 14.

The upper landmark registration element 1 6 includes a collar 20 which extends snugly around the spine 1 2 such that it is longitudinally slidable relative thereto. A set screw 22 is mounted in a threaded hole (not shown) in the collar 20 whereby the collar 20 is releasably lockable at a desired position on the spine 1 2.

Similarly, the lower landmark registration element 1 8 includes a collar 24 and a set screw 26 whereby the collar 24 is releasably lockable at a desired position on the spine 1 2. A pair of linear graduated scales 28, 30 extend in opposite directions from the reference member 1 4 on the spine 1 2.

The device 1 0 includes a chin engaging member 32. The chin engaging member 32 includes a first horizontal part 34, which is connected at its one end to and protrudes perpendicularly from the spine 1 2, a vertical part 36, which extends downwardly from the free end of a first horizontal part 34, and a second horizontal part 38 which extends outwardly from the lower end of the vertical part 36 generally perpendicular to the spine 1 2. A level 40 is mounted on the second horizontal part 38. Once again, the chin engaging member 32 is longitudinally displaceable relative to the spine 1 2 and releasably lockable in a desired position by means of a set screw 42.

The device 10 includes Ala-Tragus measuring means, generally indicated by reference numeral 44. The Ala-Tragus measuring means 44 includes a telescopic pointer 46 which is connected to the collar 20 by means of a connecting arm 48 such that the pointer 46 lies in a vertical plane which is generally parallel with a plane in which the reference member 14, upper and lower landmark registration elements 1 6, 1 8 and chin engaging member 32 are positioned. The pointer 46 is angularly displaceable and an angular scale (not shown) is provided whereby the angular spacing of the pointer 46 relative to a reference plane can be read off. The pointer 46 may be linked to the reference member 1 4 such that they are angularly displaceable together.

As can clearly be seen in the drawings, the reference member 1 4 is longer than the upper and lower landmark registration elements 1 6, 1 8.

Referring now to Figure 2 of the drawings. In use, the reference member 14 is positioned between a patient's lips. With the muscle groups controlling the opening and the closing of the patient's jaws and lips in a relaxed state, i.e. with the jaws at 1 80 degrees, the chin engaging member 32 is positioned such that the second horizontal part 38 is in light abutment with the under surface of the patient's chin and the vertical part 36 is in light abutment with the front of the patient's chin as shown in Figure 2.

The upper landmark registration element 1 6 is then displaced along the spine 1 2 until it is positioned in register with the base of the patient's nose, which corresponds to the sulcus area on the upper jaw of the patient. The upper landmark registration element 1 6 is then secured in position by means of the set screw 22. Similarly, the lower landmark registration element 1 8 is displaced along the spine 1 2 until it is in register with the base of the indentation or recess between the lower lip and the chin, which corresponds to the sulcus area on the lower jaw of a patient. The lower landmark registration element 1 8 is then secured in position by the set screw 26. The spacing between the reference member 1 4 and the upper and lower landmark registration elements 1 6, 1 8 can then be read off the scales 28, 30 and noted .

At the same time, the position of the pointer 46 is adjusted until it is parallel with the Ala-Tragus line, i.e. an imaginary line extending from the nose to the ear of a patient that runs generally parallel with the occlusal height of a patient's natural teeth and which is generally indicated by reference numeral 60 in Figure 2 of the drawings. The angle of the pointer relative to a reference plane can then be read off the angular scale. The device 10 is then removed.

Impressions of the edentulous jaws are taken and, from the impressions, plaster models are made. These, together with the information obtained from the device 1 0 enables a dental technician to manufacture special trays, each having a handle, with the desired height of the handle on the maxillary and mandibular special trays being optimized. Similarly, bite blocks are manufactured with the desired incisal height of the upper and lower jaws using the anterior sulcus area as a reference point to the edge of the bite rim for both the upper and lower bite blocks.

A further development of the invention is shown in Figure 3 of the drawings, in which reference numeral 50 refers to the reference member of another device in accordance with the invention. In this embodiment, the reference member 50 is provided with a centrally disposed longitudinally extending slot 52 therethrough and is used in substantially identical fashion to the reference member 14.

In Figure 3 of the drawings, reference numerals 54 and 56 refer to upper and lower measuring means, respectively, in accordance with the invention.

The upper measuring means 54 includes an L-shaped base 58 defining an upper lip engaging formation defining a lip engaging surface 60. A slot 62 extends through the base 58 and an incisive papilla engaging member in the form of a slide member 64 is mounted on and longitudinally displaceable along the slot 62. The base 58 is releasably lockable to the reference member 50 by means of screws 66.

The lower measuring means 56 is substantially identical to the upper measuring means 54 and, unless otherwise indicated, the same reference numerals used above are used to designate similar parts. In Figure 4 of the drawings, reference numeral 80 refers generally to a bite fork in accordance with the invention which is releasably mountable on the reference member 50 by means of a locking screw 82 which extends through the slot 52 into screw-threaded engagement with the bite fork 80. The bite fork 80 includes retaining means in the form of a plurality of spikes 86 to grip bite blocks and retain them in position on the bite fork 80 as described in more detail herebelow. Naturally, instead of the spikes 86, the bite block retaining means can take any suitable form.

As a further refinement, in addition to the measurements taken above, the upper and lower measuring means 54, 56 can be used to take additional measurements. In particular, the upper measuring means 54 is positioned on the reference member 50 and positioned in the mouth of a patient such that the lip engaging surface abuts lightly against an inner surface of the patient's upper lip. The slide member 64 is longitudinally displaced in the slot 62 until it is in register with the incisive papilla, i.e. the anterior part of the upper ridge, and the distance between the incisive papilla and the inner surface of the patient's lip is measured. Similarly, the lower measuring means 56 is used to measure the distance from an inner surface of a patient's lower lip to the anterior part of the lower ridge. This information is conveyed to a dental technician which assists in the correct positioning of upper maxillary and lower anterior teeth in a set of dentures.

In use, the measurements mentioned above are taken and supplied to a dental technician who manufacturers bite blocks and special trays if required . The bite blocks and special trays are returned to the dentist who checks the bite registration by placing the bite blocks in the patient's mouth and ensuring that when the mouth is closed and in a rest or relaxed position the bite surfaces of the bite blocks touch lightly.

Subsequently, the patient opens his mouth and the dentist positions the bite fork 80 when mounted on the reference member 50 in the patient's mouth between the bite blocks. The patient then bites down onto the bite fork causing the bite blocks to be secured to the bite fork. The bite blocks are then removed from the patient's mouth whilst mounted on the bite fork.

The reference member 50 is then mounted on the remainder of the device at the same angle as the pointer 46 and the information is transferred to an articulator permitting dentures to be manufactured which correspond accurately to the configuration of the patient's natural teeth.

The Inventor believes that the method and the device will permit simple but accurate measurements to be taken which will result in a reduction in the time which a dentist must spend with a patient and a concomitant increase in productivity. The Inventor further believes that the invention will lead to a reduction in material waste and hence a reduction in the cost of the material used when manufacturing dentures.

Claims

CLAIMS:

1 . A method of taking measurements in a patient's fully edentulous jaws for use in the manufacture of dentures, which method includes the step of, with the jaws at 1 80 degrees, measuring the distance from a central position between the lips to at least one externally visible landmark on the patient's face corresponding to a predetermined position on one of his jaws.

2. A method as claimed in claim 1 , which includes measuring the distance from between the lips to at least two externally visible landmarks, one of which corresponds to a predetermined position on the patient's upper jaw and the other of which corresponds to a predetermined position on the patient's lower jaw.

3. A method as claimed in claim 2, in which one of the said landmarks is the base of the nose, which corresponds to the sulcus area on the upper jaw.

4. A method as claimed in claim 2 or claim 3, in which one of the said landmarks is the base of the indentation between the lower lip and the chin, which corresponds to the sulcus area on the lower jaw.

5. A method as claimed in any one of the preceding claims, which includes the step of measuring the angle of the Ala-tragus line.

6. A method of determining the correct placement of anterior teeth in a set of upper dentures which includes the step of measuring the distance from an inner surface of a patient's upper lip to the incisive papilla and transferring this information to an upper bite block.

7. A method of determining the correct placement of the lower anterior teeth in a set of dentures which includes the step of measuring the distance between an inner surface of a patient's lower lip and the anterior part of the lower ridge and transferring the measurement to a lower bite block.

8. A dental registration device for use in the manufacture of dentures, which device includes an elongate reference member which can be positioned in register with a point which is between a patient's lips; and at least one landmark registration element which is displaceable relative to the reference member in order that it may be brought into register with an externally visible landmark on the patient's face and the distance between the reference member and the landmark registration element measured .

9. A device as claimed in claim 8, in which at least part of the reference member is receivable between a patient's lips and which includes two landmark registration elements which are relatively displaceable to and positioned on opposite sides of the reference member.

1 0. A device as claimed in claim 8 or claim 9, which includes an elongate spine from which the reference member and the or each landmark registration element protrude generally parallel to one another, the or each landmark registration element being longitudinally displaceable along the spine.

1 1 . A device as claimed in claim 1 0, which includes locking means whereby the or each landmark registration element is releasably lockable to the spine.

1 2. A device as claimed in claim 1 0 or claim 1 1 , in which the spine includes a graduated linear scale from which the spacing between the reference member and the or each landmark registration element can be read off.

1 3. A device as claimed in any one of claims 1 0 to 1 2, inclusive, which includes a chin engaging member which protrudes from the spine.

1 4. A device as claimed in claim 1 3, which includes a level.

1 5. A device as claimed in claim 14, in which the level is mounted on the chin engaging member.

1 6. A device as claimed in any one of claims 1 0 to 1 5, inclusive, which device includes Ala-tragus measuring means.

1 7. A device as claimed in claim 1 6, in which the Ala-tragus measuring means includes an angularly displaceable pointer which is connected to and angularly displaceable relative to the spine.

1 8. A device as claimed in claim 1 7, in which the pointer is telescopic in order that its length is adjustable.

1 9. A device as claimed in claim 1 7 or claim 1 8, which includes an angular scale whereby the angular spacing of the pointer relative to a reference plane can be read off.

20. A device as claimed in any one of claims 1 7 to 1 9, inclusive, in which the reference member is connected or connectable to the pointer for angular displacement together with the pointer.

21 . A device as claimed in any one of claims 8 to 20, inclusive, in which the reference member is longer than the or each landmark registration element such that, in use, a portion of the reference member is positionable or positioned in a patient's mouth.

22. A device as claimed in claim 21 , in which at least part of at least that portion of the reference member which is intended to be positioned in patient's mouth has a thickness of about 3 mm.

23. A device as claimed in any one of claims 8 to 22, inclusive, which device includes a bite fork which is disconnectably connectable to the reference member.

24. A device as claimed in any one of claims 8 to 23, inclusive, which device includes upper measuring means for measuring the distance between an inner surface of a patient's upper lip and his incisive papilla, the upper measuring means being dismountably mountable on the reference member.

25. A device as claimed in claim 24, in which the upper measuring means includes a base which is dismountably mountable on the reference member, an upper lip engaging formation and an incisive papilla engaging member mounted on the base such that the spacing therebetween is adjustable.

26. A device as claimed in claim 25, in which the upper lip engaging formation is formed integrally with the base and the incisive papilla engaging member is slidably mounted thereon.

27. A device as claimed in any one of claims 8 to 26, inclusive, which includes lower measuring means for measuring the distance between an inner surface of a patient's lower lip and the anterior part of his lower ridge, the lower measuring means being dismountably mountable on the reference member.

28. A device as claimed in claim 27, in which the lower measuring means includes a base which is dismountably mountable on the reference member, a lower lip engaging formation and a lower ridge engaging member mounted on the base such that their relative spacing is adjustable.

29. A device as claimed in claim 28, in which the lower lip engaging formation is formed integrally with the base and the lower ridge engaging member is slidably mounted thereon.

30. Upper measuring means, for measuring the distance between an inner surface of a patient's upper lip and his incisive papilla, which includes mounting means for dismountably mounting the upper measuring means on a dental registration device.

31 . Lower measuring means, for measuring the distance between an inner surface of a patient's lower lip and the anterior part of his lower ridge, which includes mounting means for dismountably mounting the lower measuring means on a dental registration device.

32. A method of taking measurements in a patient's fully edentulous jaws as claimed in claim 1 , substantially as herein described and illustrated.

33. A method of determining the correct placement of anterior teeth as claimed in claim 6, substantially as herein described and illustrated.

34. A method of determining the correct placement of the lower anterior teeth as claimed in claim 7, substantially as herein described and illustrated.

35. A dental registration device as claimed in claim 8, substantially as herein described and illustrated .

36. Upper measuring means as claimed in claim 30, substantially as herein described and illustrated.

37. Lower measuring means as claimed in claim 31 , substantially as herein described and illustrated .

38. A new method, a new dental registration device, or new measuring means, substantially as herein described.