GB2527020A

GB2527020A - An impression device and its methods to manufacture oral appliances

Info

Publication number: GB2527020A
Application number: GB1400433.7A
Authority: GB
Inventors: Gert Petrus Visser
Original assignee: O LAB INTERNAT Ltd
Current assignee: THE O LAB INTERNATIONAL, LTD
Priority date: 2014-01-10
Filing date: 2014-01-10
Publication date: 2015-12-16
Also published as: GB2537313A; GB2537313B; GB201400433D0; WO2015104683A2; WO2015104683A3

Abstract

An impression device of the type used in simultaneous recording of the upper and lower jaw positions relative to each other. Also disclosed are methods of manufacturing of types of individual appliance for patients using the impression device. The impression device comprises a tray capable of accepting impression material for use in recording an occlusion between an upper and lower jaw, whereby, when inserted in a subject's mouth. A locator is adapted to displace relative to the upper and lower jaws thereby obtaining a measurement of misalignment of the upper jaw with respect to the lower jaw.

Description

An Impression device and its methods to manufacture oral appliances

Field of Invention

The present invention relates to an impression device of the type used in simultaneous recording of the upper and lower jaw positions relative to each other.

The invention also relates to methods of manufacturing of types of individual appliance for patients using the impression device.

Background

It is standard practice in dentistry to study occlusion. In a dental context this means simply the contact between teeth or more technically, it is the relationship between the maxillary (upper) and mandibular (lower) teeth when they approach each other, as it occurs during chewing or at rest.

Malocclusion is the misalignment of teeth and jaws often resulting in a "bad bite".

Malocclusion can cause a number of health and dental problems. Signs and symptoms of malocclusion or dysfunction that may cause pain, but may also affect the way we chew, swallow, breath, speak, sing, sleep and this dysfunction may affect people in many other different ways.

The occlusal and spatial relationship of the teeth and that of the upper and lower jaw can be observed and recorded manually by a clinician, noting how individual teeth meet and by describing the bite' of a patient by identifying position of teeth during opening and closing of the jaw. However, there is often a desire to determine optimal position of the jaws in relation to the skull and its skull bones, so that it is possible to understand the amount of deviation from this optimal position and therefore provide treatment for possible associated problems caused by this deviation.

Traditional orthodontists and prosthodontists often involves straightening of teeth to improve function and aesthetics. However, straightening of the teeth without the consideration and the ability to record jaw alignment/misalignment may be problematic and can lead to, or cause, other problems such as Temperomandibular Dysfunction (TMD) and relapse of teeth. Occlusion of teeth has previously been determined by creating models of the upper and lower teeth and gums by taking impressions in order to consider it further. Additionally the jaws can be x-rayed' to observe their position. Viewing the models, photographs and x-rays can help identify misalignment of the jaws. On identification of the misalignment, an appliance may be developed to be held in the mouth, worn on the teeth or over the teeth in order to correct or improve the misalignment.

However, current methods of obtaining an exact measurement of deviation of upper and lower jaws from an optimal position are often calculated based upon position of the teeth or rely on skill and experience of a clinician to palpate and observe a patient in order to determine deviation. Such methods of recording and the standardisation of bite/occlusal registration techniques and impression taking lack universal consensus with little or no clear standardisation of processes and recordings of patient data and diagnostics.

Deviation of the jaw in relation to the teeth can be considered undesirable as positioning of the teeth is not a true primary indicator of optimal symmetry in comparison to embryonic markers such as the frenulum, which can be considered a true midline indicator.

The present invention will help clinicians record the occlusion and jaw position of patients in a systematic and reproducible manner.

Prior Art

Accordingly a number of devices have been developed in an attempt to resolve the problem or similar, including the following: European Patent Application EP-A-O 439 889, Innovex Inc, describes a jaw exerciser for guiding the mandible along an anatomically correct, non-deviated pathway during both opening and closing movements in order to encourage ideal motion.

The website http://hodentalcompany.comlharmony/ discloses a dual arch tray with alignments sticks for capturing teeth, the opposing arch, bite registration and with alignments sticks for obtaining facial midlines.

The Correct Bite' DVD clip at: http://www.youtube. com/watch'?v=ohhfus9RRHO by David Hornbrook reveals a technique of correcting bite.

Tekscan (RTM) have developed an analysis tool, 1-Scan' (RTM) which shows a computerised occulsal analysis using sensor technology. The T-Scan is a diagnostic device that records your patient's bite force dynamics, including occlusal force, location and timing. http://www.tekscan.com/occlusal-analysis-system Kerr Dental discloses a Kwik Tray' that is an adjustable, perforated, aluminium tray for crowns, bridges and inlay quadrant impressions.

SomnoDent (RTM) discloses the George Gauge comprising a body, lower incisor clamp and a bitefork for use in obtaining a bite registration.

http:Hwww,somnomed.cornIFor Denta Frofessonalsffhe George Gauge.asox Glidewelldental.com disclose the si-protrusion gauge discloses an elastic framework for use in bite registration. e.pdf

The present invention provides an impression device that can be used to create an imprint using fiduciary markers, suitable for use in the creation of an appliance.

Summary of Invention

According to a first aspect of the present invention, there is provided an impression device comprising: a tray capable of accepting impression material for use in recording an imprint from a jaw wherein the tray includes visual fiduciary markers for measuring and recording jaw alignment and/or misalignment.

The device can be used (although not exclusively) for determining occlusion and making a record of an upper and lower jaw position using fiduciary markers to correct and align the jaws.

In this way the impression device can be used to take an imprint that records and reveals contours of teeth as well as one that is capable of being used to establish measurements of jaw alignment/misalignment. The results of such an impression can be used for jaw correcting and in particular the creation of an occlusal splint or appliance.

In preferred embodiments the impression device is adapted to be bitten by a user and comprises: a tray having an upper and a lower bite surface whereby, when inserted in a subject's mouth, a locator is adapted to displace relative to the upper and lower jaws thereby obtaining a measurement of alignment of the upper jaw with respect to the lower jaw using fiduciary markers.

In this way the impression device can be used to obtain a measurement of anterior/posterior alignment of the jaws that can be used to reveal misalignment. For example measurement of position of an upper and a lower jaw position can be taken and compared, or position of the jaw in a natural position can be measured and compared to a measurement taken when the jaw is moved to a corrected position.

In preferred embodiments the tray comprises a body for positioning within a mouth, in use, and a handle that protrudes from the mouth when the tray is held in the mouth. In this way the device can be positioned and supported in the mouth whilst allowing the clinician to manoeuvre the device by means of the handle.

Preferably the body has a substantially planar, arcuate body for positioning between the upper and lower jaw thereby having an upper and lower bite surface. Therefore the body is U-shaped so as to match standard location of the teeth on the jaw.

In some alternative embodiments the wall may be contoured to accommodate different subjects mouths. For example the outer wall if the tray may be stepped in order to widen distally.

Ideally the body is sized to receive the full dentition, preferably at least six teeth on each side of the mouth, therefore the body is preferably capable of receiving twelve or more teeth in total for each of the upper and lower jaw teeth.

The body is planar so as to provide a flat bite surface onto which the teeth are received and for which in some uses receives impression material for taking a registration. The arcuate shape of the body enables the tray to fit around teeth on the upper and/or lower jaw.

In preferred embodiments the planar portion of the body may be formed from a mesh or netting that is capable of flexure when receiving the teeth. Current methods of aligning the lower jaw are by consideration of the lower arch against a flat surface, however this may introduce a canting of the occlusal plane since the three highest points on the arch determine the occlusal plane.

The impression device allows clinicians to reposition the jaw and bypass these occlusal interferences. The fiduciary markers are used in conjunction with the impression device helping the clinician to find the correct jaw position.

In some preferred embodiments the bite surface may be formed from a mesh therefore allowing deformation to occur during the bite registration. Advantageously the use of mesh can prevent canting and interference that can be associated when using a solid material instead of a mesh surface. For example a wire or synthetic plastic mesh may be provided as the bite surface.

In a particularly preferred embodiment, the body has a front wall and a rear wall between which a user's teeth are positioned during use. The walls define an area between which the teeth are located and wherein the impression material is received so as to obtain a registration.

Preferably the walls extend both sides of the bite surface to have an upper wall and lower wall, thereby defining an area on both an upper and lower face of the tray so that imprints can be taken simultaneously of both jaws.

In preferred embodiments the lower wall that extends toward the lower jaw is thicker at a distal end of the tray so as to limit spreading of impression material in the mouth whilst taking the bite registration. This prevents excessive spreading of the impression material about the lower jaw due to the effects of gravity. Impression material placed on an upper face of the tray is less liable to spreading.

Preferably the a lower wall height increases gradually so as to provide a smooth, curved wall that does not cause discomfort to a subject.

In some embodiments faces of the wall that receive impression material are ribbed so as to aid with removal of the imprint after use. The ribbed walls also serve to prevent the impression material from separating from the tray when the clinician removes the device from the subject's mouth.

In preferred embodiments the tray includes a channel for accepting the locator.

Typically the channel is arranged through the body and handle so that the locator is accessible in use exterior the subjects mouth. Therefore the channel causes there to be a break in the wall. Ideally the locator includes a raised portion that corresponds to and is capable of being aligned with the outer wall so as to provide a continuous barrier comprising the outer wall of the tray and raised portion of the locator.

Advantageously the locator is longitudinal having at least one perpendicular groove for receiving teeth on both and upper and lower face of the locator. In this way the locator can be adjusted by being slid along the channel or by the tray being slid relative to the locator in order to align the groove with either the teeth of the upper jaw, teeth of the lower jaw or both. Typically the process of alignment is guided by fiduciary markers such as those in the anterior/posterior symmetrical dimension.

The grooves traverse width of the locator is so as to allow the grooves to be aligned with and to accept incisor teeth. Ideally the groove is arranged to be proud of the tray so as to engage with the teeth without interruption caused by the tray. In this way the teeth engage with the locator before engaging with any other part of the device.

Typically the grooves are arranged posterior to the raised portion thus further aiding with location of teeth with the area defined by the walls and raised portions.

In preferred embodiments raised portion includes a notch for use in aligning with a fiduciary marker that indicates a midline from which deviation from can be determined.

The fiduciary markers include various reference points on the body.

Preferably the notch is aligned with the frenulum labii superioris inside the upper lip, or the frenulum labU inferioris inside the lower lip, hereon in described as the frenulum. The frenulum is one such natural midline marker of the body and by determining location of this, the clinician can observe deviation of the teeth and or jaw from this midline, therefore measuring and/or observing medial/lateral deviations.

The frenulum sometimes referred to as the soft tissue position, is described as an embryonic primary marker and is therefore recognised as a true midline. Whereas markers such as the teeth do not necessary indicate a true midline and growth of the teeth often does not match the frenulum.

Typically the device is aligned with the fiduciary markers in order to determine variation of the teeth and/or jaw from these fiduciary markers.

Preferably the notch is aligned with the frenulum. Typically the subject's lips are displaced in order to reveal the frenulum and the locator and the tray is moved in a lateral plane in order to align the notch with the frenulum. Ideally both the locator and the tray have a notch for alignment with the frenulum so as to help the clinician to guide the subject's jaw into the correct alignment.

In this way when the device is aligned with the frenulum it is also possible to observe where the teeth midline sits in comparison to this fiduciary marker.

Ideally an outward facing face of the outer wall includes increments to allow the clinician to measure the distance between the fiduciary marker, the frenulum, and the observed midline of the teeth, therefore revealing lateral deviation. For example millimetre increments may be included on the outer face. Ideally the increments may include a range of at least 5mm, ideally at least 10mm to the left and 10mm to the right.

These same increments may additionally be used when observing jaw mechanics, in particular dynamics of the jaw during opening and closing, and for example lateral excursion of the jaw to the left or right during opening of the mouth.

Preferably in use the locator may be inserted into the mouth initially without the tray so as to allow the subject to bite on to the groove. The subject is asked to bite down on the locator so that the front incisors are located in a groove; the subject's lips are retracted so that the notch can be visually aligned with the frenulum by augmentation of the jaw.

This method serves to familiarise the subject with the correct position of the jaw so that when taking an impression, the subject is more readily able to correctly position the jaw.

Proprioceptors in and around the periodontal ligament are activated when biting about the locator and aid the subject to find the correct position. Evidence has shown that there is a natural "neuromuscular" protective feedback mechanism that exists between the periodontal ligaments supporting the teeth and the motor centres of the brain that control the muscular contractions of the primary muscles of mastication (chewing muscles).

This reflex is seen most clearly for example when chewing meat with a small fragment of bone in the meat. As the teeth come together with force they encounter the bone fragment before they expect to meet the opposing teeth and this feedback mechanism is triggered due to the sudden overloading of the nerve endings in the ligament (proprioceptors). A message is immediately sent to the motor centre responsible for the contraction of chewing muscles and immediately the nerve stimuli to those muscles cease, thus contraction is halted and instead the muscles responsible for opening the mouth are stimulated. This process is designed to prevent damage occurring to the teeth. This useful neuro-muscular feedback response can be used to stop and/or control clenching thereby helping the clinician to find the correct position to be recorded.

Once this is achieved the same procedure may be repeated with the locator and the tray.

A second method of implementation comprises use of the tray and locator in unison wherein the impression device is used to determine deviation of occlusion of the upper and lower jaws from correct alignment having the steps of: adding impression material to the impression device, positioning the impression device in the mouth so as to have the front and rear walls either side of the teeth, peeling back the subjects lips, laterally adjusting the tray in a horizontal plane to align the locator notch with a fiduciary marker; augmenting the jaw to align with the fiduciary marker, having the subject clench their jaws about the impression material to record and imprint on the impression material.

Alternatively or additionally an imprint of the jaws may be taken without augmentation of the jaw.

Typically this second method may be a secondary step to having already undertaken the first method of use. In this way the subject has an understanding of corrected jaw alignment and therefore the imprint obtained has greater accuracy.

In some uses it may be envisaged that once the locator has been positioning so that the subject is biting down on a groove that the tray can be slid forwards or backwards until the raised portions are aligned with the wall. Therefore a measurement can be taken of anterior/posterior positioning of the teeth on the jaw relative to a set position on the device.

In some embodiments the channel may include increments so that the position of the locator in the channel can be measured thereby providing a measurement of anterior/posterior positioning. Alternatively or additionally the position of the locator in the tray may be marked for example with a pen.

Therefore the locator is displaceable from the tray and can be used to identify and correct lateral deviation of the jaw from the midline but in use can also be arranged to be slidable along the channel in one plane in order to record anterior/posterior position of the teeth relative to the barrier formed by the walls and raised portion.

Fiduciary markers can be used to determine various deviations in the jaw and are preferably used to identify three planes of deviation, medial/lateral, anterior/posterior and superior/inferior.

The fiduciary markers are mainly postural and positional such as for example; the frenulum, the anterior nasal spine, mid line of the frontal bone or midpoint of the mandible. All can be use in relation to restoring and repositioning symmetry of the jaw and recording the occlusion in this position.

By determining deviation of the jaw in relation to fiduciary markers the results can aid clinicians in: 1. The Planning and Construction of various occlusal splints/appliances, 2. The Study and Treatment planning of patients 3. To design restorative, surgical, orthodontic prototypes prior to definitive and final restorations and surgery.

4. The recording and planning of diagnostic setups and moulds (Physical and Digital) of patient occlusion.

In preferred embodiments the tray is capable of accepting impression material so as to record a registration of a subject's bite. It may be envisaged that the device may be used to obtain a registration of the jaw in a natural position, a corrected position, an offset position or any other positions between, typically based on the fiduciary markers.

Preferably the tray is capable of accepting impression material adapted to record an imprint of a subject's upper and lower jaws wherein the tray includes a displaceable locator to locate the upper and lower jaws in a preferred relative alignment. In this way the anterior/posterior measurement can be recorded before taking the imprint.

The anterior/posterior measurement is converted into an alignment by using one or more of the six tests below.

The locator preferably has a plurality of grooves in which the incisor teeth can be located. In this way the lower jaw can be guided forward or backwards by small increments defined by the grooves.

The sizing of the increments or fiduciary markers used to determine optimal jaw position may be gathered from but are not limited to one or a combination of the following: 1. The Jefferson x-ray analysis 2. The s-sound test 3. The 3d Profile analysis 4. Airway and position of the hyoid 5. A percentage of protrusion, for example 60% of protrusion 6. Applied kinesiology testing Alternatively or additionally the jaw can be manipulated to a corrected position based on the measurement obtained in order that the imprint taken is of corrected bite not natural bite. In this way the clinician uses the displaceable locator to locate the upper and lower jaws in a preferred relative alignment prior to an impression being taken so that the upper and lower jaws are properly aligned when forming the impression.

In some embodiments the impression device is used in recording an occlusion between an upper and lower jaw, whereby, when inserted in a subject's mouth, a locator is adapted to cause relative displacement of the subject's upper and lower jaws thereby enabling alignment of the upper and lower jaws.

In this way occlusal between the upper jaw and lower jaws, and therefore superior/inferior displacement in the corrected alignment can be determined. The displacement can be established in relation to fiduciary markers, for example those may be obtained from but not limited to one or a combination of: 1. The Jefferson and Posterior Anterior skull x-ray analysis 2. The s-sound test 3. The 3d Profile analysis and TMJ condular position from radiographs 4. Airway and position of the hyoid 5. A percentage of protrusion, for example 60% of protrusion 6. Applied kinesiology testing The device may be produced in a number of physical sizes in order to take into consideration the variance in size of the human upper and lower jaw anatomy. For example the device may be provided in a small, a medium and a large version in order to accommodate various sized mouths from paediatric to adult.

Advantageously by providing sized devices the practitioner is more easily able to obtain a full impression of jaw occlusal by ensuring all teeth form an imprint in the impression material as the device is correctly dimensioned to best fit an individual's mouth.

In some embodiments the impression device may accept discs inserted by a clinician to correct uneven vertical height of the occlusal support of the jaw. Typically the discs may be inserted into the tray and the subject then asked to clench their jaw so that the clinician can observe symmetry with the disc.

Ideally the discs are disc shaped formed from a lightweight, strong, durable synthetic material. Typically the discs are of predetermined sizes so that the clinician can record amount of alteration caused by insertion of the discs. For example discs may be provided with a one millimetre and two millimetre depth. Number and size of discs is recorded.

In some embodiments the disc may be shaped so as to be accepted by the ribbed surface of the walls, for example the disc may include a pair of projections for fitting into a pair of opposite ribs. In this way the discs can be specifically located and will not move during use.

In preferred embodiments the device can be used to determine measurements of the jaw in more than one anatomical plane and preferably in at least three anatomical planes for consideration of jaw alignment.

Preferably the measurements are made in relation to the following anatomical planes: anterior/posterior, medial/lateral and superior/inferior ranges.

Ideally separate measurements and/or absolute readings are taken to record measurements in each plane wherein the readings may be taken before, during or after augmentation of the jaw.

In preferred embodiments the device is used in conjunction with fiduciary markers in order to take a measurement or reading.

In some embodiments the handle has tapered edges for abutting or aligning with incisor teeth. Advantageously the tapered are rounded so as not to expose any sharp edges to the subject so there is less risk of cutting or injuring the subject.

Typically the point at which full thickness of the handle is reach may be marked with a visual indicator for aligning of the handle with a particular tooth. Typically the area between the tapered edges may be marked with increments so as to be suitable for obtaining a measurement. These measurements can be recorded and used in patient management of care and education.

Typically the visual indicator may be aligned with an incisor and during opening and closing of the mouth the alignment of this indicator in relation to the tooth is observed jaw opening and closing dynamics that may reveal abnormal movement of the jaw such as lateral excursion to one side. In this way the jaw dynamics can be recorded in order to provide further insight to a subject's pathology.

There are a number of ways in which the device can be used in order to obtain different readings, impressions and/or measurements. The readings, measurements and imprint taken provide data that is typically used to reveal any misalignments of the jaw. This data can also be used in the process of creating an appliance which is a corrective item worn by the subject to correctly align the jaws.

Typically the data obtained is used in conjunction of models of the jaws. Such models may be obtained by taking jaw impressions or scans and using these as moulds to create physical replicas of the jaws, x-rays and/or digitally scanning the jaw. In this way it can be possible to observe and manipulate the model jaws to better understand subject pathology and to clearly demonstrate this to the subject.

Where manual models of the jaws are taken by impressions these may then be subsequently scanned so as to provide a computerised model of the jaw.

Often the models created must also be mounted to recreate actual position of the jaw which can add a margin of error. Current laboratory methods for producing occlusal splints/appliances and recording jaw position and occlusion use several fabrication, articulation, and manual trimming methods. For unmounted models, models have to be mounted on an articulator to allow the opening to be adjusted and to simulate the dynamics/ excursions needed to design centric relation splints. This can introduce error since a mechanical jig is typically used to "level" the lower occlusal plane.

Preferably data obtained by the impression device and optionally in combination with other information such as x-rays, palpation, neurological testing, diagnosis is analysed in order to establish correct jaw alignment and augmentation required in order to achieve this in a tangible manner that can be applied to the models either manually or digitally.

This information can then be translated in order to provide the dimensions required to create an appliance or occlusal splint. Such items facilitate correction of the jaws in a non invasive manner.

Typically the imprint obtained from a bite in the correct alignment proves the core shape of the appliance with the additional measures obtained by the device aiding to define thickness of the appliance in order to fully align the jaw.

A process of making an appliance from the impressions taken using the impression device includes the steps of: using the impression to model the upper and lower jaw, the jaws models being used to reveal exact jaw occlusion, measured deviations used to correct jaw model position and forming an appliance based on occlusion at the corrected position.

The impression device reduces margin of error by enabling the clinician to take measurements and to aid with guiding the subject's jaw into the required position using the fiduciary markers on the locator.

Current methods of aligning the lower jaw by consideration of the lower arch against a flat surface may introduce a canting of the occlusal plane since the three highest points on the arch determine the occlusal plane. The impression device allows clinicians to reposition the jaw and bypass these occlusal interferences. The judiciary markers used in conjunction with the impression device helping the clinician to find the correct jaw position.

Further errors may also be introduced during fabrication and manufacture of the appliance for example if produced from a wax-up, or directly by curing acrylic between the arches. Traditionally the final contact surfaces may rely too much on the result of a technician's subjective determination of smoothness and the absence of tooth impressions.

In preferred embodiments the impression device is made from a lightweight, strong, durable synthetic plastic such as a medically safe acrylonitrile butadiene styrene (ABS) plastic, polystyrene and/or nylon Ideally the device is disposable being suitable for use during a single treatment wherein the device may be used more than once for the same subject to obtain different information, for example to obtain measures and to obtain an imprint.

In some embodiments the impression device may include sensors that allow digital readings to be taken and recorded during use, by providing digital spatial positioning/measurement without requirement for manual recording. Preferably digital motion sensors track the jaw movements and align these with fiduciary markers obtained from 3D models of the subjects skull, jaws and teeth. These sensors will be embedded into the locator and also into the tray and where required the appliance will be manufactured and calibrated to achieve the correct positional relationships.

For example, a reading may be taken form the various offsets in the X-X', Y-Y' and Z-Z' planes and used to provide an automatic manufacturing process to produce a replica of an oral appliance.

One way in which this is achieved is to use a digital data file(s) for example StereoLithography files (STL files) of an impression(s). Such files can then be imported into compatible software for the purposes of design and articulation before being passed to a further compatible system in order to produce the final patient appliance, utilising a 3D printing process.

Brief Description of Figures

Figure 1A shows a rear, top isometric view of one embodiment for the impression device; Figure 1 B shows a front, top isometric view of one embodiment for the impression device; Figure 2 shows one embodiment a top view of the impression device shown in figures 1A and 1 B including the tray and locator; Figure 2B shows a top view of the tray shown in Figure 2A; Figure 3A shows a rear, top isometric view of the tray; Figure 3B shows a front, top isometric view of the tray; Figure 4A shows a rear view of the impression device; Figure 4B shows a rear view of the tray without the locator; Figure SA shows a left side view of the impression device; Figure 5B shows a left side view of the tray without the locator; Figure 6A shows a rear, top view isometric of the locator; Figure 6B shows a front, top view isometric of the locator; Figure 7A shows a top view of the locator; Figure 7B shows a side view of the locator; Figure 8 shows a flow chart with the steps required to obtain data such as measurements of the mouth and an imprint which can be used to create an appliance; Figure 9 shows an impression device having a stepped outer wall; Figure 10 shows an alternative embodiment of the tray Figure 11 shows a small sized impression device; Figure 12 shows a medium' sized impression device, and Figure 13 shows a large' sized impression device.

Detailed Description of Figures

The figures show a preferred embodiment of the impression device which can be used for obtaining an imprint of the upper and lower jaws as well as obtaining measurements of the mouth and positions of the jaw relative to fiduciary markers.

Figure 1A and lB show an overview of the impression device 100 wherein the impression device 100 comprises a tray 200 and a locator 300. The locator 300 fits into a channel 210 provided on the tray 200.

The locator 300 is capable of being slid along the channel 210 for the tray 200.

The tray 200 comprises a body 220 and a handle 230. The body 220 is planar having an arcuate shape so as to wrap around the teeth in use. The body is sized to encompass 12 teeth.

The body 220 includes an inner wall 240 and an outer wall 245 that define an area in which the teeth are located in use. The area defined is also capable of receiving impression material for taking an imprint, the walls 240,245 serving as a barrier to prevent escape of impression material.

The walls 240, 245 extend both sides of a bite surface 250 having an upper wall 240A, 245A and lower wall 24DB, 245B, thereby defining an area on both an upper and lower face of the tray so that imprints can be taken simultaneously of both jaws.

Figure 1 and Figure 5 shows the lower walls 24DB and 245B having a greater height at a distal end of the tray in order to prevent impression material spreading excessively in the mouth beyond the device. Preferably the lower walls gradually increase in height so as to have a smooth increase in height.

The other wall 245 is broken by the channel and therefore has two halves, one either side of the channel 210.

Inner faces of the walls are ribbed 280 to aid with removal of the impression material from the device 100.

The tray bite surface 250 is flat so as to provide a flat surface for receiving the teeth.

The bite surface 250 is also smooth so as prevent impression material from becoming stuck to the base 250. The mesh bite surface is advantageous because it prevents canting and interference which can occur when using a solid surface.

Edges of the handle 230 are tapered so as to have a smooth rounded finish that will not cause discomfort to the subject.

The walls 240, 245 extend from the tray bite surface2so.

The handle 230 is substantially planar extending from the body 220 so as to be project from the mouth in use. The handle tapers from the body.

The locator 300 is longitudinal having a front end 310 received by the mouth in use and a rear end 320 that is exterior the mouth in use. The locator 300 is substantially rectangular in shape.

The rear end 320 includes ridges 330 on an upper surface so as to aid the clinician to grip the locator 300 and move it during use. The ridges 330 are arranged to traverse the width of the locator 300, being positioned adjacent to one another.

The front end 310 of the locator 300 is narrower than the rear end 320 and is therefore not in contact with the channel 210. The front end 310 includes a plurality of grooves 340 on both upper and lower faces of the locator 300. The grooves 340 receive incisor teeth in use so as to locate the subjects bite. The grooves 340 are arranged to traverse the locator 300. The grooves 340 are also arranged to be project proud of the tray 200 when in use so that the subjects teeth can be located into the groove 340 without being obstructed by the tray 200.

The locator 300 includes a raised portion 360 pad way along its length. The raised portion 360 can be aligned with the walls so as to provide a continued barrier that defines an area for locating the teeth and receiving impression material.

The raised portion 360 includes a notch 265 that is aligned with a fiduciary marker in use. The notch is V-shaped and in use is visually aligned with the frenulum (a natural midline). Once aligned deviation of the jaw from this midline can be observed by comparing the frenulum location at the perceiving teeth midline.

In Figure 2B the channel 210 has recessed sections 215 on an upper face of the handle for receiving the locator 300 allowing it to slot into the channel 210 rather than merely resting on top.

The locator 300 is shaped so as to fit in the recess have a stepped 325 rear end 320 as shown on Figure 7B wherein pad of the locator 300 sits within the channel 210 and part sits upon the channel 210.

Central portions of the locator 300 are hollow 390 allowing the clinician to peer through the hollow 390 to view the lower wall 245B and parts of the mouth such as teeth, inferior frenulum and gums. The hollows 390 also allow the locator 300 to be lighter in weight and cheaper to manufacture.

In Figures 3A and 3B the break in the wall is visible. The wall is only broken on an upper surface of the device 100. On the lower surface the outer wall remains continuous.

The lower, outer wall 245B includes a notch 270 for aligning with a fiduciary marker.

The notch 270 performs the same function as notch 365, being used for aligning with the inferior frenulum. Therefore the device is used in one orientation and capable of taking both upper and lower teeth impressions and measurements.

Figures 11-13 show three different sizes of the impression device, small, medium and large. The impression devices shown in figures 11-13 have the following dimensions given in millimetres (mm): Small (mm) Medium (mm) Large (mm) Tray length (1) 48 55 60 Tray Width (2) 62 66 74 Bite surface width (3) 17 20 23 Bite surface depth at locator (4) 18 21 25 Tray distal end to mid-point (5) 58 64 68 The invention has been described by way of examples only and it is appreciated that variation may be made to the aforementioned examples without departing from the scope of the invention.

Claims

Claims 1. An impression device comprising: a tray capable of accepting impression material for use in recording an occlusion between an upper and lower jaw, whereby, when inserted in a subject's mouth, a locator is adapted to cause relative displacement of the subject's upper and lower jaws thereby enabling alignment of the upper and lower jaws.
2. An impression device adapted to be bitten by a user comprising: a tray having an upper and a lower bite surface whereby, when inserted in a subject's mouth, a locator is adapted to displace relative to the upper and lower jaws thereby obtaining a measurement of misalignment of the upper jaw with respect to the lower jaw.
3. An impression device comprising: a tray capable of accepting impression material adapted to record an imprint of a subject's upper and lower jaws wherein the tray includes a displaceable locator to locate the upper and lower jaws in a preferred relative alignment.
4. An impression device comprising: a tray capable of accepting impression material adapted to record an imprint of a subject's upper and lower jaws wherein the tray includes a displaceable locator to locate the upper and lower jaws in a preferred relative alignment prior to an impression being taken so that the upper and lower jaws are properly aligned when forming the impression.
5. An impression device according to any preceding claim wherein separate measurements and/or absolute readings are taken.
6. An impression device according to any preceding claim wherein the tray includes a body for positioning within the subject's mouth and wherein a handle is arranged to protrude from the mouth.
7. An impression device according to any of claims 1 to 3 wherein the tray has a planar, arcuate body for positioning between the upper and lower jaw.
8. An impression device according to any of claims 1 to claim 3 wherein the device has a front wall and a rear wall between which a subject's teeth are positioned during use.
9. An impression device according to claim 8 wherein the front and rear walls extend perpendicularly above and below the bite surface providing an upper wall and a lower wall corresponding to the upper and lower jaw.lOAn impression device according to claim 9 wherein the lower wall has a greater height than the upper wall.hAn impression device according to any preceding claim wherein the handle has tapered edges for abutting teeth.12.An impression device according to any preceding claim wherein the handle includes increments to measure jaw dynamics including deviation/lateral excursion.13.An impression device according to any preceding claim wherein the tray includes a channel for accepting the locator.14.An impression device according to any preceding claim wherein the locator includes at least one groove/channel/recess for receiving teeth.15.An impression device according to any preceding claim wherein the locator is capable of movement in at least one plane so as to position the groove/channel/recess to receive a patient's teeth.16.An impression device according to any preceding claim wherein the locator includes a raised portion that forms a displaceable part of an outer wall of the body.17.An impression device according to claim 16 wherein the raised portion includes a notch for aligning with a fiduciary marker.18.A method of using the impression device described in claims 1-17 to record/determine deviation of occlusion of the upper and lower jaws from an optimal alignment comprising the steps of: introducing impression material into a tray of the impression device, positioning the impression device in the mouth so as to receive a patient's teeth; adjusting the tray so as to align a locator notch with a fiduciary marker; displacing the locator so as achieve optimal alignment of upper and lower jaws; and aligning the groove with a tooth prior to the subject closing the jaws about the impression material to record occlusion of the upper/lower jaws on the impression material.19.A method of using the impression device described in claims 1-17 includes the steps of: adding impression material to the impression device, positioning the impression device in the mouth so as to have the front and rear walls either side of the teeth, reveal the subjects frenulum, laterally adjusting the tray in a horizontal plane to align the locator notch with a fiduciary marker; augmenting the jaw to align with the fiduciary marker, having the subject clench their jaws about the impression material to record and imprint on the impression material.20. A process of making an appliance from impressions obtained using the device described in claims 1-17 Comprises the steps of: using the impression to replicate a patient's upper and lower teeth, the replicated teeth being used to reveal jaw occlusion; measuring deviations of jaw offset and correcting jaw model position and forming an appliance based on occlusion at the corrected position.21.A measuring tool comprising: a tray capable of accepting an impression material for use in recording occlusion of an upper and lower jaw, wherein a locator is adapted to permit relative displacement of the upper and lower jaw thereby enabling alignment the upper with respect to the lower jaw and to record misalignment of the jaws along three axes.22.A measuring tool according to claim 21 wherein there are three axes and these are orthogonal.23.A system for manufacturing an oral appliance includes the impression device according to any of claims 2 to 17, comprises: a means for receiving data indicative of measurement of misalignment of the upper jaw with respect to the lower jaw and a fabricator, operating under control of an automated means, the fabricator is arranged to manufacture the appliance.24.A system for manufacturing an oral appliance according to claim 1 to 15 includes a rapid prototyping device for producing a facsimile of an indentation formed from teeth on an upper and a lower jaw.25.A system for manufacturing an oral appliance according to claim 1 to 15 wherein the rapid prototyping device includes a 3-D printer.26.A system for manufacturing an oral appliance according to claim 1 to 15 includes a stereo lithographic device for producing a facsimile of an indentation formed from teeth on an upper and a lower jaw.27.A system for manufacturing an oral appliance according to claim 26 includes a stereo lithographic processes employing a curable resin.28.A system for manufacturing an oral appliance according to claim 1 to 15 wherein an injection moulding process is employed to obtain a facsimile of the impression formed from the teeth.29.A method of manufacturing an oral appliance comprising the steps of: obtaining an impression of teeth from a patient's upper and lower jaws; obtaining data indicative of the patient's jaw misalignment, forming a facsimile of the impression of the patient's teeth and displacing the upper and lower impression by an amount to compensate the misalignment so proving an appliance which, when worn so as to correct the misalignment.30.A method of correcting a misaligned upper and lower jaw using the device according to any of claims ito 17.31. An impression device substantially as herein described with reference to the Figures.32.An oral appliance manufactured according to any of claims 23-28 33.A database adapted to store data derived from the system data indicative of patient identity and data measurements indicating misalignment of the upper jaw with respect to the lower jaw according to claim 23-28 and a fabricator, operating under control of an automated means, the fabricator is arranged to manufacture the appliance.34.A method of correcting a misaligned upper and lower jaw substantially as herein described with reference to the Figures.35.A measuring tool substantially as herein described with reference to the Figures.36.An oral appliance substantially as herein described with reference to the Figures.37. A system for manufacturing an oral appliance substantially as herein described with reference to the Figures.