WO2022043911A1

WO2022043911A1 - Dental scanner apparatus

Info

Publication number: WO2022043911A1
Application number: PCT/IB2021/057828
Authority: WO
Inventors: Laszlo Rajmund HAVASI; Attila Balogh
Original assignee: Dental Scanner Solutions Kft.
Priority date: 2020-08-28
Filing date: 2021-08-26
Publication date: 2022-03-03

Abstract

A dental scanner apparatus for scanning three sides of a tooth, comprising a head unit (4) and a control unit (3). The head unit (4) comprises at least one imaging sensor (1) and a plurality of lighting units (2); the imaging sensor (1) and the lighting units (2) are electrically connected to the control unit (3). The head unit (4) is approximately U-shaped comprising a bottom element (17) and two side elements (18) such that the elements (17, 18) at least partially surround at least one tooth from three sides. It is characterized in that the head unit (4) comprises at least one head unit piece; each head unit piece comprises at least one imaging sensor (1) and at least three reflective surfaces (10) configured to provide a folded light ray path (19) for a light ray travelling from the tooth to the imaging sensor (1) such that the apparatus can scan the three sides of the at least one tooth from a single position.

Description

Dental scanner apparatus

TECHNICAL FIELD

The disclosure relates to a dental scanner apparatus for scanning three sides of a tooth.

BACKGROUND

The first step toward preventing dental problems is proper oral and dental care. Continuous diagnostics constitutes the basis of preventive dentistry. Dental problems need to be detected quickly and easily, and instant imaging of such problems is also required. However, it is often difficult to examine and scan small objects that may be difficult to access. To this end, oral scanning needs to be developed in order to diagnose dental problems as painlessly and as conveniently as possible.

The state of the art includes the following solutions.

U.S. patent document No. US7099732 B2 describes a dental scanner that is fitted with three mirrors and uses different wavelengths of light.

South Korean publication document No. KR102096612 describes a 3D oral scanner that is equipped with a prism and is thus capable of generating a spatial image of a tooth with a camera. International patent document No. WO2019021285 Al describes is a dental device with a prism and/or a mirror which simultaneously takes several images of several parts in one position, without moving the scanner head, and generates a complete image of a part of the denture.

Russian patent document No. RU2715986C1 discloses a dental diagnostics aid that is fitted with a detachable U-shaped head and uses infrared radiation. The device is capable of examining the side of a tooth only.

In summary, the above inventions use mirrors because the tooth is far away from the sensor. (The tooth is in the mouth, and the sensor is in the handle of the scanner.) This way, the light that is reflected from the tooth is guided to the sensor by mirrors. However, if the sensor is far from the object under examination (e.g. a tooth), it is not possible, or it is very difficult and expensive, to use a diagnostic device that is fitted with a movable head. Thus, one of the problems is that cameras with short focal lengths and wide angles operate with considerable distortion. In the context of dental scanning, distortion should be avoided at all costs, as proper diagnostics work and the diagnosis of dental problems is not possible without high quality imaging. Proper diagnostics requires the device to be located close to the tooth (or teeth) under examination. In such a situation, the angle of view creates difficulties as, on the one hand, fisheye optics (extremely wide angle) is required when the object under examination is close; however, such solutions are highly distorting. On the other hand, smaller-angle cameras need to be placed farther away, which would increase the size of the device, so that they would not fit in the head of a scanner that is supposed to be used comfortably and painlessly. Thus, conventional lenses produce a distorted view when used at wide angles. The required wide viewing angle could only be achieved with the nearly 180-degree fisheye optics, which in turn reduces the quality of imaging significantly. It is also a disadvantage of the solutions forming part of prior art that the depth of field of the lens is good only in a narrow range, at a distance of approximately 6 to 9 mm; the sharpness of the image deteriorates drastically at a distance outside this range. A further disadvantage of the existing solutions, which aim to increase the path of light within the smallest possible space, is the use of free-form prisms or free-form mirrors. These are more expensive to use, and calculations also indicate that they do not provide a better solution given the quality of imaging.

A further disadvantage of the known devices of conventional design is that they could not be used for self-diagnosis. Most dental scanners can only be operated in a dental office by qualified operators. None of the known devices could be used by a person to scan all his teeth from from all directions, so they are not suitable for home use. Furthermore, the device includes only one camera in many inventions; or, where several cameras are implemented, they are not able to examine the tooth from three (i.e. all) directions and sides at the same time. Although some known inventions are fitted with a U-shaped head, those are still not able to see all sides of a tooth, as doing so would require more sensors or other forms of implementation.

The purpose of the invention is to eliminate the shortfalls of the known solutions and to provide a device in which the sensor can be placed close to the tooth; and it can generate high-resolution and distortion-free images. Another objective is to keep production costs low. It is also an important goal that the device can see and scan all three sides of one or more tooth from a single position at the same time. This will make the scanner suitable for home use.

The inventive step is based on the recognition that a solution, which is more advantageous than the previous ones, may be created by implementing the apparatus according to claim 1. It is also part of the recognition that, when using a suitable optical arrangement, e.g. prisms, it is enough to use only one, two or three sensors to see, examine, and diagnose all three sides of a tooth at the same time, and also to generate distortion-free images of it even when from a wide angle. A result of the applied optical arrangement is that it produces a distortion-free image even with a wide viewing angle, and that its depth of field is excellent: it produces a sharp image even at a distance of 1 to 10 mm. When version with two-sensors is used, due to its implementation form, each sensor can see the outside or inside of a tooth and somewhat more than half of the upper grooved part. It is also part of the recognition that, due to the shape of a tooth, using a U-shaped head unit is ideal.

SUMMARY

It is an object to provide an improved dental scanner apparatus. The foregoing and other objects are achieved by the features of the independent claims. Further implementation forms are apparent from the dependent claims, the description, and the figures.

According to a first aspect, there is provided a dental scanner apparatus for scanning three sides of a tooth, comprising a head unit and a control unit; the head unit comprising at least one imaging sensor and a plurality of lighting units; the imaging sensor and the lighting units being electrically connected to the control unit, the head unit being approximately U-shaped comprising a bottom element and two side elements such that the elements at least partially surround at least one tooth from three sides; the head unit comprises at least one head unit piece; each head unit piece comprises at least one imaging sensor and at least three reflective surfaces configured to provide a folded light ray path for a light ray travelling from the tooth to the imaging sensor such that the apparatus can scan the three sides of the at least one tooth from a single position.

In a possible implementation form of the first aspect, the head unit comprises one, two or three head unit pieces, each head unit piece comprising one imaging sensor.

In a possible implementation form of the first aspect, the head unit is fitted with two head unit pieces, and each head unit piece comprises at least one sensor; and the head unit pieces are at least approximately L-shaped. In a possible implementation form of the first aspect, each head unit piece comprises at least two reflection elements, each reflection element having at least one reflective surface; the reflection element being a prism or a mirror.

In a possible implementation form of the first aspect, the apparatus is fitted with a shaft, the shaft being connected to the head unit.

In a possible implementation form of the first aspect, the shaft is connected to the head unit through a centre of rotation so that it can turn around at least one rotation axis Al; the rotation axis Al being perpendicular to the longitudinal axis A2 of the shaft.

In a possible implementation form of the first aspect, the lighting units are LEDs; the sensor is a camera or a CCD sensor or a CMOS sensor; and the lighting units are placed around the sensor.

In a possible implementation form of the first aspect, the control unit is connected to a motor, said motor being configured to move the head unit.

In a possible implementation form of the first aspect, the control unit is located in the shaft, and the control unit is in electronic connection with the sensor and the lighting units through a cable.

In a possible implementation form of the first aspect, the apparatus is in wired or wireless connection with an external processing unit and/or power source.

This and other aspects will be apparent from the embodiments described below.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention is presented in more detail below using a drawing of a possible implementation form.

In the attached drawings,

Figure 1 shows a spatial drawing of an implementation form of the apparatus, Figure 2 shows a spatial drawing of an implementation form of the apparatus, with the apparatus mounted on a handle with a cable,

Figure 3 shows a spatial drawing of the implementation form of the apparatus as shown on Figure 2, with an exploded section of the handle,

Figure 4 shows a spatial drawing of another implementation form of the apparatus, with the apparatus integrated into an electric toothbrush,

Figure 5 shows a spatial drawing of another implementation form of the apparatus, with the apparatus mounted onto the handle of an electric toothbrush of a different design, Figure 6 shows a spatial drawing of a possible implementation form of the apparatus, Figure 7 shows a spatial drawing of the implementation form of the apparatus as shown on Figure 6 from another angle,

Figure 8 a spatial drawing of a possible, L-shaped implementation form of the head unit piece of the apparatus,

Figure 9 shows a spatial drawing of the L-shaped head unit piece without a cover,

Figure 10 shows a spatial drawing of the arrangement of the optical elements of the head unit piece shown on Figures 8 and 9,

Figure 11 shows a spatial drawing of another possible straight implementation form of the head unit piece of the apparatus,

Figure 12 shows a spatial drawing of the head unit piece shown on Figure 11 from another angle,

Figure 13 shows a side view of the arrangement of the optical elements of the head unit piece shown on Figures 11 and 12,

Figure 14 shows a spatial drawing of the arrangement of the optical elements of the head unit piece shown on Figures 11 and 12,

Figure 15 shows a spatial drawing of another possible implementation form of the apparatus, where the head unit is based on the head unit piece shown on Figures 11 and 12, and

Figure 16 shows a spatial drawing of another possible implementation form of the apparatus, where the head unit is based on the head unit piece shown on Figures 8 and 9.

Figure 1 shows a spatial drawing of an implementation form of the apparatus. The apparatus is fitted with a U-shaped head unit 4, which can surround a tooth from three directions. However, the U-shaped head unit 4 can be implemented in various ways; for example, it may include multiple sections. For our purposes, having a U-shape means that the apparatus surrounds, at least in part, at least one tooth from three sides, so that it can produce an image of all three sides at the same time. The U-shape may be realized in an angled or arched shape. The head unit 4 comprises a bottom element 17 and two side elements 18, the three elements together completing a U shape.

The head unit 4 includes at least 1 imaging sensor. The optical arrangement is realized in a way that enables the apparatus to scan all sides of a tooth from a single position at the same time, meaning that it can produce an image of all three sides of at least one tooth. Thus, it is not necessary to go through a dental arch more than one time, and it is not necessary to turn the apparatus, as the apparatus can produce an image of all sides of a tooth at the same, or nearly at the same, time. The apparatus may be made fit for producing 3D images by integrating suitable 3D imaging sensors and/or technology. The head unit 4 is connected to the shaft 5. In this implementation form, the centre of rotation 6 is located at the junction of the head unit 4 and the shaft 5, and the rotation axis Al passes through it. The centre of rotation 6 is a junction unit between the head unit 4 and the shaft 5, and it may be implemented as a point, an axis, a mounting component, a ball-joint, or another suitable joint. Rotatability is merely optional. The centre of rotation 6 is not necessarily realized at the centre of the head unit 4, as asymmetric solutions are also feasible. The head unit 4 can turn around the rotation axis Al, so that it can follow the dental arch automatically. In this implementation form, the rotation axis Al is perpendicular to the longitudinal axis of the shaft 5. The rotation may also be driven by a motor. Rotation takes place around at least this one axis, but, in other possible implementation forms, the head unit 4 may turn or rotate around more than one axes; for example, turning is possible in any direction where the centre of rotation 6 is implemented as a ball-joint. When turning is possible around the rotation axis Al only, a short axis may be used at the centre of rotation 6 to connected the head unit 4 to the shaft 5.

The apparatus may be mounted onto various devices by way of the shaft 5; e.g. to electric toothbrushes, central panels of dentist chairs, or handles that may be purchased separately. Thus, the apparatus may be connected in a wired manner to external power sources, processing units, computing units, or motors. A wireless connection may also be used to establish a connection to a processing unit or a computing unit. Thus, it is not indispensable to integrate all of these into the apparatus, as, as noted above, the apparatus may be easily mounted onto an external device where such scenarios are easy to implement. Thus, an apparatus may be implemented that is simpler and cheaper, and also more easily accessible to consumers. Naturally, using a built-in processing unit 13, power source 14 (e.g. accumulator, battery), or motor 15 is also feasible. In such a situation, these parts are typically built into the shaft 5. The apparatus may also connect to external devices, e.g. to smartphones, tablets, laptops, or computers, possibly in a wireless manner, through its control unit 3 that is typically located in the shaft 5 of the apparatus. As described above, various forms of wired or wireless connection may be used to connect the apparatus to an external display, so that the user may view the images produced. For example, a smartphone, tablet, laptop, or computer screen may be used as an external display.

The diagnostics apparatus includes at least one sensor 1 and a lighting unit 2, and it relies on using those. These are built into the head unit 4. For adequate measuring, all sides, i.e. the outside, the inside, and the grooved part of the tooth or teeth, needs to be seen. The sensor 1 is, for example, a CCD sensor (Charge-Coupled Device) or a CMOS sensor (Complementary Metal Oxide Semiconductor). Advantageously, the number of sensor 1 in an apparatus is two; one sensor in each head unit piece 4a, 4b. Naturally, two-two or even more sensors 1 may be built into the head unit pieces 4a, 4b, but doing so increases the costs unnecessarily. Suitably, only two sensors 1 are built into the head unit 4; each sensor 1 can see the outside or inside of a tooth and somewhat more than half of the upper grooved part. The optimal size of the internal distance between the side elements 18 is 12 to 20 mm. Suitably, the greatest distance between the external points is 25 to 35 mm.

The functioning of the apparatus is based, among others, on the use of lighting units 2 having different features, as they offer a means of examining teeth that is the simplest and free of any danger. Due to its composition, a tooth responds to each different frequency in a different manner. Thus, different lighting units 2 can show the mineral content, external colouring, internal damages, and cracks of a tooth. The lighting units 2 are illuminating light sources, typically LEDs, that can be switched on and off independently, and their luminosity can also be adjusted freely and also independently. These are controlled by the control unit 3 that is built into the shaft 5. Advantageously, the lighting units 2 are located in the head unit 4 around the sensors 1 as shown on the Figures, possibly so that each sensor 1 is surrounded by as many unit as possible. Among others, the possible types of lighting units 2 include white light, IR (infrared), and UV (ultraviolet) units. White lighting units 2 show the extent of and changes to the discoloration of a tooth, so that it can provide feedback on the thoroughness of washing the teeth. When using IR lighting units 2, the light needs to pass through a tooth, as the light passing through the tooth provides the information, and its intensity correlate to the internal structure of the tooth. For this reason, it needs to be taken into consideration regarding the placement of the lighting units 2 that an IR lighting unit 2 may not be located on the plane of the sensor 1, but it should be located on the opposite side or the side closing a 90-degree angle. As explained above, the reason for this is that the light needs to pass through the tooth to provide information on any possible internal defect or damage of the tooth. UV lighting units 2 may be located on the plane of the sensor 1, next to the sensor 1, because, when such measurements are performed, information is conveyed by the light that is reflected from the tooth, and it can show any contamination or thinning that may affect the surface of the tooth. UV light triggers luminescence radiation in a tooth, and such radiation corresponds to the internal mineralisation (mineral and moisture content) of a tooth. A weak or dead tooth emits considerably less such light.

The exposure of the sensor 1 and the lighting units 2 is synchronized in a controlled manner. Thus, imaging can be accelerated and consumption may be reduced considerably, as the lighting units 2 flash only at the time of exposure. Suitably, at least one sensor 1 and the lighting units 2 are placed so that the apparatus can measure and illuminate a tooth all around. During measurement, the lighting units 2 are to be switched on and off in the appropriate order. The sensor 1 may be capable of taking 25 to 90 images per second. It is not necessary to move the apparatus over the teeth for each spectrum when different types of lighting units 2 are used, i.e. when different kinds of dental problems are diagnosed. The control unit 3 can be used to switch on different lighting units 2 when different frames are taken, so that a tooth or the teeth can be exposed to different types of lighting even within a fraction of a second. The operation of the sensor 1 and the lighting units 2 is synchronised by the control unit 3. Optionally, the control unit 3 may also receive feedback during the measurement. For example, the control unit 3 may be an MCU (microcontroller unit), an FPGA (Field-programmable gate array), a DSP (digital signal processor), or another device that is known to a professional.

Imaging and the quality of measurement is influenced by the intensity of illumination and the sensitivity of the sensor (exposure time), which factors may be adjusted to the teeth of the user. The mineral composition (density) and the size of teeth is different for each and every person. In order to facilitate such adjustments, the sensor 1 can provide feedback, i.e. control signals, to the control unit 3 after an image is processed, for the purpose of finding the optimum of each factor that has an impact on imaging. As a supplementary feature, the apparatus may also be used to examine the gums, making it fit for indicating various problems, e.g. for the early diagnosis of gingival atrophy. For the purpose of examining the gums, it is suitable to use UV and white lighting units 2.

Figures 2 and 3 show an implementation form of the apparatus where it is mounted onto a handle 16 fitted with a cable 11. As noted above, the apparatus may be mounted onto various kinds of handles. The handle 16 does not necessarily form part of the invention, but there are possible implementation forms where the apparatus is fitted with a handle. On this drawing, the apparatus does not have a built-in processing unit or power source, but it is connected to an external processing unit 13 and a power source 14 using wires, which, for example, may be built into the handle 16, form part of a dentist chair, or belong to a mobile phone, tablet, laptop, or computer, or even software running on such devices and even background (e.g. cloud) services may also be used as a processing unit. Thus, either of the above may provide the resources required for data processing. In this example, the cable 11 is typically required for the purpose of connecting to a power source and power supply. The other end of the cable 11 may be implemented as a USB connector, so that the apparatus can be connected to various devices and/or power sources easily. Where a cloud service is used, a mobile phone, for example, may be used to compress and transmit data through an online connection.

Figure 3 shows that the shaft 5 of the apparatus may be slid into the handle 16.

Figures 4 and 5 show another possible implementation form where the apparatus is mounted onto an electric toothbrush or the handle 16 thereof. In such a situation, it is advantageous that the toothbrush includes a power source and electric connection points (e.g. Philips Sonicare). Thus, the power source of the electric toothbrush can be used, and it is sufficient for the apparatus to implement measurement and data transmission functions only. In such an implementation form, the shaft 5 of the apparatus is mounted onto the handle 16 of an electric toothbrush that may be purchased separately. In such a situation, the apparatus may also be connected to a cloud service, a tablet, a computer, or a mobile phone, in a wireless manner advantageously. Data transmission is typically performed through such a wireless connection. The user may monitor the recorded images and other information on the smartphone, tablet, or computer screen. Figure 4 shows the apparatus where it is integrated into a toothbrush, and the implementation form shown on Figure 5 shows that the apparatus may be connected to the handle 16 of an electric toothbrush quickly and easily. In the implementation form shown on Figure 5, the handle 16 includes a processing unit 13, a power source 14, and a motor 15. Thus, the apparatus connected to the handle 16 can use all of these parts, meaning that the apparatus becomes simpler as it becomes unnecessary to integrate all these parts into the apparatus. Thus, in this implementation form, the handle 16, the processing unit 13, the power source 14, and the motor 15 does not form part of the apparatus. In the implementation form shown on Figure 5, the U- shaped head unit 4 includes two L-shaped head unit pieces 4a, 4b, each of which is fitted with a sensor 1.

Figure 6 shows a spatial drawing of a possible implementation form of the apparatus. Figure 7 also illustrates the implementation form shown on Figure 6, but from a different angle. The apparatus is rather small, as it must be able to move among the teeth comfortably. The small and limited size has an impact on the internal design of the apparatus. The essence of the solution according to the invention is that the path of light is folded using various reflection elements, such as mirrors and/or prisms. Thus, the optics system is arranged within a small space, so that the longer distance of the object is broken multiple times. Thus, the light travels a long path, and the apparatus can be used to take pictures as if the focal distance were larger. The arrangement makes it possible to take distortion-free and high-quality pictures even if the sensor 1 is placed into the head unit 4, close to the tooth under examination. As the sensor 1 is close to the tooth under examination, the head unit 4 of the apparatus can even turn, thereby making its use and self-diagnosis easier. Rotation can be performed around the rotation axis Al, typically in both directions at a 45 or even 90 degree angle, but complete rotation may also be possible if the cables are arranged in a suitable manner. In a possible implementation form, the rotation axis Al is perpendicular to the longitudinal axis A2 of the shaft 5.

In this implementation form, the head unit 4 shown on Figure 6 includes two L-shaped head unit pieces 4a, 4b. Naturally, the head unit 4 and the head unit pieces 4a, 4b may also be implemented in a different shape; for example, in a possible implementation form, there might be three straight head unit pieces, and the entry plane of light forms a rectangle. The L-shaped part may be implemented in an angled or arched manner; where an arched form is used, the shape of a head unit piece is similar to a J shape. The head unit piece 4a, 4b is protected by a cover 12, which protects the sensor 1 and other optical parts against external impacts, and which also makes it easier to clean and disinfect the apparatus. The cover 12 may include multiple parts, which, in this implementation form, are connected to each other by screws.

The apparatus is suitably fitted with a support structure and/or a shaft 5. In the implementation form shown on Figures 6 and 7, the apparatus may be mounted onto various devices by way of the shaft 5; e.g. to electric toothbrushes, central panels of dentist chairs, or handles that may be purchased separately. Thus, the apparatus may be connected in a wired manner to an external power source 14, processing unit 13, computing unit, or motor. A wireless connection may also be used to establish a connection to a processing unit or a computing unit. Thus, these parts are not necessarily built into the apparatus itself, as they can be connected as external devices, as described above.

Figure 7 shows the implementation form shown on Figure 6 viewed from below. It shows the centre of rotation 6 located at the junction and meeting point of the head unit 4 and the shaft 5, and, when implemented in a certain form, the head unit 4 can turn around the rotation axis Al that passes through it. Rotation takes place around at least this one axis, but, in other possible implementation forms, the head unit 4 may turn or rotate around more than one axes; for example, turning is possible in any direction where the centre of rotation 6 is implemented as a ball-joint. When turning is possible around the rotation axis Al only, a short axis may be used at the centre of rotation 6 to connected the head unit 4 to the shaft 5. The centre of rotation 6 is not necessarily realized at the centre of the head unit 4, as asymmetric solutions are also feasible. The head unit 4 can turn around the rotation axis Al at a +-90 degree angle, and in other possible implementation forms, the head unit 4 can make a full turn around the rotation axis Al. In this implementation form, the rotation axis Al is perpendicular to the longitudinal axis A2 of the shaft 5. In other possible implementation forms, the head unit 4 is also able to turn around additional axes, provided that the centre of rotation 6 is implemented suitably (e.g. as a ball-joint). The feature that the head unit 4 is able to turn makes it possible to follow the curve of the denture easily, comfortably, and without the user having to twist his arm or wrist. The head unit 4 can turn only if the sensor 1 is located in the head unit 4, and not, for example, in the more distant handle. On this drawing, the two head unit pieces are slightly pushed apart from each other, so that the shorter elements of the two L-shaped head unit pieces are shown next to each other. As an optional solution, this design can save space. Figure 8 shows a head unit piece 4a. Advantageously, the head unit 4 includes two parts, which may have any shape. In the implementation form shown on Figure 8, the head unit piece 4a is L-shaped. Two such L-shaped head unit pieces can be rotated towards each other, so that, for example, a shape that is similar to that shown on Figure 6 or 7 is achieved. One sensor 1 is located in the L-shaped head unit piece 4a, which may be covered by a transparent and translucent cover sheet. In fact, the cover sheet constitutes the entry surface of light. The surface may have any size. Lighting units 2, typically LEDs, are placed around the sensor 1. They may even fully surround the cover sheet. This Figure shows that they do not form a full circle. The reason for this is that the cover may be less thick this way. Thus, the two head unit pieces take up less space when they are placed next to each other. Advantageously, and because of the design of the head unit piece 4a, the sensor 1 can see the at least half of a tooth, i.e. one side (outside or inside) of the tooth, and (somewhat more than half of) its upper grooved part. Figure 8 also shows the cable 11 through which the sensor 1 and the lighting units 2 communicate with the control unit 3 and the external devices, e.g. the processing unit. Suitably, the cable 11 is a flexible cable. Typically, a head unit piece 4a shown on Figure 8 has the following dimensions: dl length, i.e. the height of the L element, is approximately 10 to 30 mm, typically 15 to 25 mm, and 15 to 20 mm in the most advantageous situation. D2 length, i.e. the shorter element of the L-shape: typically 3 to 15 mm, and 5 to 10 mm in the most advantageous situation. The d3 width of the L-shape is suitably 2 to 10 mm, advantageously 4 to 8 mm, and 4 to 6 mm in the most advantageous situation.

Figure 9 shows the L-shaped head unit piece 4a shown on Figure 8 from a different angle and without a cover. The drawing shows the sensor 1, the lighting units 2, the reflection elements 9 next to the sensor 1, and the cable 11. When measured from the sensor 1, the typical d4 width of the head unit piece 4a (from the end of the shorter element of the L-shape to the sensor) is approximately 10 to 30 mm, typically 12 to 25 mm, and 14 to 18 mm in the most advantageous situation. The stated dimensions may be reduced even further by reducing the examined area and/or by reducing the size of the sensor 1.

Figure 10 shows the internal optical units of the L-shaped head unit piece 4a shown on Figures 8 and 9. It is clear that three reflection elements 9 are located next to the sensor 1 in the head unit piece 4a, one of which is a prism 7 and two of which are mirrors 8 typically. It is noted here that the vertical larger reflection element 9 shown on Figure 10 is the prism 7. In another possible form of the head unit, for example, one prism 7 and one mirror is in the path of the light ray. In this implementation form, the extra mirror has the advantage that it allows the sensor 1 to detected the grooved part of the tooth as well. Thus, the surface of the mirror that detects the side of the tooth is reduced, and the freed surface is transferred to the mirror that detects the grooved part. However, all reflection element 9 can be implemented as prisms 7, so that the parts can be placed into the same space in a compact manner more easily, and they are also easier to clean. The reflection elements 9 need to be fitted to each other in an optical quality. This requires careful adhesion, which must be taken into account during planning and modelling.

In the implementation form shown on Figure 10, the light ray path is broken or folded four times by four reflective surfaces 10. In this implementation form, the four reflective surfaces 10 are provided by three reflection elements 9, one of which is a prism 7 and two of which are mirrors 8. Because of the optical design, the head unit 4 is able to see and scan a tooth from the same position and without any movement or rotation, as the folded light ray path connects the sensor 1 to the tooth.

In a possible implementation of the head unit piece 4a, four reflection elements 9 (e.g. one prism 7 and three mirrors 8) are built into the head unit piece 4a. Thus, it is possible to create a U-shaped head unit piece, which can see all three sides of a tooth using a single sensor 1. In such a situation, another head unit piece is not even necessary, as it is enough for the head unit 4 to have only a single head unit piece 4a. Because of its characteristics arising from its resolution and size, the technical parameters of this U-shaped arrangement differ from those of an apparatus that includes two L-shaped head unit pieces 4a.

Figure 11 shows a straight head unit piece 4a. Typically, one sensor 1 is located in the head unit piece 4a, meaning that an apparatus has two sensors 1, if it is fitted with a head unit 4 that includes two head unit pieces. Moreover, the head unit piece 4a shown on this drawing can be mounted onto and built into different handles, moving devices, or diagnostic devices in and of itself. Thus, the head unit 4 does not require two head unit pieces to operate. The transparent or translucent surface or cover sheet before the sensor 1 forms the entry surface of light, and it also determines the approximate size of the sensitive area of the sensor. The dimensions of this (width and length) can be adjusted. However, changes to these dimensions may also increase the total volume. In the possible implementation form shown on this drawing, the ratio of the detected image results in an elongated image (approximately 20:5 ratio). Such a straight head unit piece 4a with a single sensor is mostly advantageous because it is highly cost-efficient.

Figure 12 shows a spatial drawing of the head unit piece 4a shown on Figure 11, with the head unit piece 4a seen from below, so that the cover 12 and the cable 11 become visible. Figure 12 shows only one possible implementation form, where the upper and bottom parts are separate parts. The upper part (where the light entry area and the lighting units 2 are located) holds all the optical components and the sensor 1. The other bottom part of the cover 12 (its bottom) only serves to cover the internal parts. Naturally, it is also possible to implement a cover 12 of a different kind that includes less or more parts. If the head unit piece 4a is fixed onto the holding structure directly, the bottom cover part may even be left out.

Figures 13 and 14 shows the internal parts and implementation of the straight head unit piece 4a also shown on Figures 11 and 12. Figures 13 and 14 show the sensor 1, the reflection elements 9, and the light ray path 19 from a side view and on a spatial drawing, respectively. The light ray path 19 is indicated as a dotted line; the drawing indicates as the light ray reflected from the object, e.g. a tooth (the outer world), is broken multiple times before it reaches the sensor 1. Its path is broken by multiple reflection elements 9. Typically, a straight head unit piece 4a includes two reflection elements 9, one of which is suitably a prism 7, and the other is a mirror 8. A prism 7 has more than one reflective surfaces 10. In this implementation form, the light ray path 19 is broken, folded three times by three reflective surfaces 10. In this implementation form, the three reflective surfaces 10 are provided by two reflection elements 9. Because of the optical design, the head unit 4 is able to see and scan a tooth from the same position and without any movement or rotation, as the folded light ray path 19 connects the sensor 1 to the tooth. The lens of the sensor 1 is selected and implemented according to its task. It is important to adjust the focal distance and the depth of field appropriately.

Figures 15 and 16 show other possible implementation forms of the apparatus on spatial drawings. The head unit 4 shown on Figure 15 includes three straight head unit pieces; the straight head unit pieces may also be similar or identical to the head unit pieces shown on Figures 11 and 12. The apparatus shown on this drawing is typically fitted with three sensors 1. The three head unit pieces are located in the same cover as shown. Figure 16 shows an implementation form that is similar to Figures 6 and 7. In this implementation form, the head unit 4 is modified as the head unit pieces 4a, 4b fall into the same line, meaning that the shorter elements of the two L-shaped head unit pieces are located in front of each other. The apparatus shown on this drawing is typically fitted with two sensors 1. Each sensor 1 can see the outside or inside of a tooth and somewhat more than half of the upper grooved part. Using the two sensors 1, the apparatus can see and take high-quality images of all sides of a tooth at the same time, thereby it can be used for diagnostics. This is due to its optical arrangement, which is presented on Figures 9 and 10.

The head unit 4 may comprise one, two or three head unit pieces. For one piece, see Fig. 1 and 2; for two pieces, see Figs. 5-7 and Fig. 16; for three head unit pieces, see Fig. 15. The head unit is approximately U-shaped that means that it has a bottom element 17 and two side elements 18. The bottom 17 and side elements 18 may constitute a head unit 4 having a single head unit piece, or a head unit 4 having two head unit pieces 4a, 4b, both pieces 4a, 4b having approximately an L or J shape, or a head unit 4 having three head unit pieces. In the embodiments with two L-shaped or J-shaped head unit pieces 4a, 4b, the two L-shaped or J- shaped head unit pieces meet in the bottom element 17 such that the bottom element 17 is divided into two parts. In this embodiment, the side elements 18 preferably belong to different head unit pieces 4a, 4b. See for example Fig. 16. In the embodiments with three head unit pieces, the bottom 17 and side elements 18 are all different head unit pieces. See Fig. 15 for illustration.

Preferably, a head unit piece may comprise two, three or four reflection elements 9. Accordingly, a full head unit 4 may comprise altogether four or six reflection elements 9.

The apparatus described above has numerous advantages. One of the advantages of the apparatus is that it makes it possible to scan a tooth all around using only one, two or three sensors, as the apparatus makes it possible to image and diagnose all sides of a tooth at the same time using only two or three scanners. The use of two sensors means low production costs, and a significant part of the technical problems can also be reduced this way. Advantageously, the use of flat-sided prisms reduces manufacturing costs even further and even when the apparatus is produced in small series. Additional important advantages from the technical design of the sample include low distortion and good depth of field; that is, it is possible to maximize the path of light inside of a minimal space. An additional advantage of the apparatus is that it allows continuous home diagnostics, thus detecting the most common problems and preventing more serious dental problems. It is also an advantage that the apparatus uses the simplest and most safe method of examining teeth, and it uses light sources and illuminators with different properties. An advantage is that the apparatus can be mounted onto various external devices (e.g. electric toothbrush), and that it can be used without special expertise or qualification, as this does not affect the result. Furthermore, it does not require any operator staff, as self-diagnosis can also be performed without involving any other person. Another advantage is that it can be used painlessly, comfortably, and easily, and imaging is performed quickly. Another advantage is that the apparatus can also be integrated into a scanner with a rotating head, which can make it even more simple to use the apparatus and follow the dental arch, while also ensuring that the user can comfortably guide the head on the dental arch without turning his hand or wrist. The movement of the rotating head can even be motorized. Another advantage is that the lighting units (e.g. LEDs) can be arranged in countless ways, and each unit can be switched on and off separately. Another advantage is that there is no need to go over the same tooth or teeth more than once, or over each side of a tooth separately, as all sides of the tooth are seen by the head unit at the same time. “Same time” are important words here, as this feature makes the use of the apparatus very fast, which is yet another advantage. Thus, it is not necessary to run the device along the dental arch over and over again for each LED spectrum, and there is no need to wait for the lighting units to illuminate each side of the tooth separately or for the sensor to switch. Another advantage is that the apparatus can be customized, i.e. the intensity of illumination and the sensitivity of the sensor (exposure time) can be adjusted to the user's teeth individually. (This is because the size, density and mineral composition of teeth vary from person to person.) Another advantage is that the apparatus can also be used to examine the gums, and it is suitable, for example, for the early diagnosis of gum diseases (e.g. gingival atrophy). As measurement may be available at different times, the extent of gum retraction can be examined and an unfavourable trend can be predicted. Another advantage is that the apparatus can be produced in different sizes, and it can even be supplemented with different optical filters. It can also be made fit for 3D imaging. Another important advantage is that the apparatus can be connected wirelessly to a tablet, smartphone, computer, or cloud service, so that all recordings can be monitored, images can be saved, and previous scan results can be traced. The display of a connected device can also be used, so that recordings may be watched live. Finally, an important advantage is that the sensors and lighting units operate in full synchronization. At a time of pandemia, it is particularly advantageous that the apparatus makes home diagnostics possible, so that the results can be analysed in a dental office. In addition to the above examples, the invention can be implemented in other forms within the scope of protection.

Typically, the invention may be used on the field of dentistry and dental mechanics.

Other variations than those described above can be understood and effected by a person skilled in the art. In the claims, the word “comprising” does not exclude other elements or steps, and the indefinite article “a” or “an” does not exclude a plurality. A single processor or other unit may fulfill the functions of several items recited in the claims. The mere fact that certain measures are recited in mutually different dependent claims does not indicate that a combination of these measured cannot be used to advantage. The reference signs used in the claims shall not be construed as limiting the scope. Unless otherwise indicated, the drawings are intended to be read (e.g., cross-hatching, arrangement of parts, proportion, degree, etc.) together with the specification, and are to be considered a portion of the entire written description of this disclosure. As used in the description, the terms “horizontal”, “vertical”, “left”, “right”, “up” and “down”, simply refer to the orientation of the illustrated structure as the particular drawing figure faces the reader.

Claims

1. Dental scanner apparatus for scanning three sides of a tooth, comprising a head unit (4) and a control unit (3); the head unit (4) comprising at least one imaging sensor (1) and a plurality of lighting units (2); the imaging sensor (1) and the lighting units (2) being electrically connected to the control unit (3), the head unit (4) being approximately U-shaped comprising a bottom element (17) and two side elements (18) such that the elements (17, 18) at least partially surround at least one tooth from three sides; characterized in that the head unit (4) comprises at least one head unit piece; each head unit piece comprises at least one imaging sensor (1) and at least three reflective surfaces (10) configured to provide a folded light ray path (19) for a light ray travelling from the tooth to the imaging sensor (1) such that the apparatus can scan the three sides of the at least one tooth from a single position.

2. The apparatus according to claim 1, wherein the head unit (4) comprises one, two or three head unit pieces, each head unit piece comprising one imaging sensor (1).

3. The apparatus according to claim 1 or 2, wherein the head unit (4) is fitted with two head unit pieces (4a, 4b), and each head unit piece (4a, 4b) comprises at least one sensor (1); and the head unit pieces (4a, 4b) are at least approximately L-shaped.

4. The apparatus according to any of claims 1 to 3, wherein each head unit piece comprises at least two reflection elements (9), each reflection element (9) having at least one reflective surface (10); the reflection element (9) being a prism (7) or a mirror (8).

5. The apparatus according to any of claims 1 to 4, wherein it is fitted with a shaft (5), the shaft (5) being connected to the head unit (4).

6. The apparatus according to claim 5, characterized in that the shaft (5) is connected to the head unit (4) through a centre of rotation (6) so that it can turn around at least one rotation axis (Al); the rotation axis (Al) being perpendicular to a longitudinal axis (A2) of the shaft (5).

7. The apparatus according to any of claims 1 to 6, characterized in that the lighting units (2) are LEDs; the sensor (1) is a camera or a CCD sensor or a CMOS sensor; and the lighting units (2) are placed around the sensor (1).

8. The apparatus according to any of claims 1 to 7, characterized in that the control unit (3) is connected to a motor, said motor being configured to move the head unit (4).

9. The apparatus according to any of claims 5 to 8, characterized in that the control unit (3) is located in the shaft (5), and the control unit (3) is in electronic connection with the sensor (1) and the lighting units (2) through a cable (11).

10. The apparatus according to any of claims 1 to 9, characterized in that it is in wired or wireless connection with an external processing unit (13) and/or power source (14).