The object of the invention is a dental inlay according to the preamble to claim 1. A particular object of the invention is a modular inlay suitable for the filling of canines, bicuspids and molars.

Traditionally, teeth are filled directly into a cavity made in the crown of the tooth. When the aim is a durable and more long-term inlay, it is usually either ordered from a dental technician for the next visit or the tooth area in question is imaged with a scanning device and the filling is milled from a larger blank to fit the cavity. In this case, the costs are clearly higher due to the dental technician’s bill or the acquisition costs for the devices required at the dentist’s office and the inlay manufacturing time.

Prefabricated inserts of different sizes and shapes are known from the publications US 5098300 A, US5695340, US 6022217 A and US 4234310, which are pressed into a dental inlay made from filling material to be edge parts in a cavity. The single inlay blank of publication US 2003170593 A1 is ground to be smaller so that it can fill the entire cavity.

All of these have significant deficiencies. None of them provides a finished inlay for the cavity, which inlay would, when assembled from parts, be both integrally uniform and suitably tightly in contact with one or two adjacent teeth. The separate external spring, lever instrument or spreading device used in some of the prior art does not guarantee sufficiently tight contact, which is also not achieved with a filling ground from a single inlay blank. That is why when chewing, food fibres get past the contact surface to press on the area’s gum and the patient must separately clean between their teeth after eating. In the solution presented above, more problems are caused by the variation of the cavity’s bottom shape and depth due to the removal of carious dental tissue. In this instance, the modified blank may partly sink too deep into the cavity and no longer be in contact with the antagonist at its biting surface. At the same time, on the biting surface a step is formed at the seam point of the blank and the tooth.

The purpose of this invention is to achieve a dental inlay that overcomes the above- mentioned drawbacks. Furthermore, the purpose of the invention is to achieve a new modular inlay, which is different compared to known solutions in structure and in function, and offers an efficient and advantageous solution to most dental restoration problems. The invention is characterised in what has been presented in the characteristics section of claim 1 and in the other claims. A particular object of the invention is a modular inlay suitable for the filling of canines, bicuspids and molars, the contact areas of which with the adjacent tooth or both adjacent teeth can always be made suitably tight using the structure of the modular inlay. According to the invention, the dental inlay is a modular inlay, which is assembled from three essential parts, with which a suitably tight contact is always achieved with the adjacent tooth or both adjacent teeth. The modules, partial crowns and other parts of the modular inlay can be prefabricated industrially, ensuring the consistent quality of the modular inlays. The modules can be manufactured from any material in use that is suitable for the mouth and medically approved or a mixture thereof. The filling material with which the modular inlay’s parts are attached to one another and/or the modular inlay is attached to the tooth to be filled, can consist of one or more different types of filling materials and/or dental prosthetics materials or mixtures thereof, whose characteristics such as wear- resistance, tensile strength and thermal expansion are compatible with the teeth. The modules and/or other parts of the modular inlay to be manufactured in this way can be cured at a high temperature and pressure, whereby they do not have any internal stress or partially cured ingredients, and they cannot cause an allergy even after several years. Also essential for the invention is the shape of the modular inlay’s modules and the structure and choice of material of the final uniform modular inlay consisting of the modules. Using these, the intention is to make the modular inlay’s adherence to the cement or filling material at the attachment stage as good as possible and the adherence to all of the edges of the cavity as good as possible.

The modules of the dental inlay according to the invention can be formed to resemble an intact tooth as well as possible and to be a size so that the healthy crown of the tooth needs to be ground as little as possible. A modular inlay assembled from parts does not put a strain on the adjoining crown part after cementation, i.e. attachment to the cavity, whereby the resulting dental inlay according to the invention withstands bite stress well. Modules of different sizes and/or shapes can be combined with one another and thus their combinations can be used to fill different types of cavities. This is why each cavity shape and/or size does not require its own individual modular inlay.

The dental inlay according to the invention differs from known dental filling methods also in that the final modular inlay that is assembled from parts and still uniform fits well into the cavity made in the tooth, always forming a suitably tight contact with the adjacent teeth. Using the modular inlay’s internal, mechanical structure, it is possible to ensure tight contact with the adjacent tooth or adjacent teeth. The structure of the modular inlay according to the invention does not have a spring or tightening device to be connected to the support tube projecting outward from the biting surface as used in known solutions. In the modular inlay according to the invention, a suitably tight contact with the adjacent teeth simultaneously prevents the modular inlay from sinking too deep into the tooth to be filled. In connection with the description of the figures is a more detailed presentation of the embodiments of the structure of the modular inlay according to the invention. According to a preferred embodiment, in the module essentially located in the middle of the modular inlay, i.e. the basic module, is a support tube protruding from the basic module and a tapered shaft resting on the support tube with a thread. When the tapered shaft resting on the support tube with a thread is rotated, its sharp tip moves the modules or parts adjacent to the basic module located in the middle of the modular inlay apart from one another. According to the invention, the tapered shaft can also be made such that it moves the modules or parts adjacent to the basic module apart from one another for example with a joint mechanism. After the installation of the modular inlay, the support tube protruding from the basic module is removed and the tip of the tapered shaft remains part of the biting surface of the modular inlay.

In the structure of a modular inlay according to the invention, channels can be made in the modules and other parts, through which the cementing material, adhesive or bonding material can move in the modular inlay’s structure. The basic module’s feeding grooves ensure that the gaps forming between the modules are filled with liquid cementing material, such as adhesive and/or bonding material. According to a preferred embodiment, the adhesive and/or bonding material travels into the gaps while the tapered shaft operates as a piston shaft of a filling syringe. The cementing material injection pressure ensures that even the smallest seam gaps of the modular inlay are filled from the inside. A detailed explanation of this embodiment is presented in connection with the figures.

According to the invention, it is advantageous that the suitable tightness of the modular inlay’s contacts directed at the neighbouring tooth or both neighbouring teeth can be tested by rotating the tapered shaft before the cementation stage of the modular inlay. At the cementation stage, the modular inlay assembled from modules is supported by holding on to the support tube such that the modular inlay is in the correct position in the cavity. Thus, the modular inlay does not sink too deep in relation to the biting surface, in which case it could form a step in the seam of the inlay. In this case, also the modular inlay’s biting surface coincides with the antagonist when biting down. According to a preferred embodiment of the invention, the modular inlay includes a basic module, in which the support tube and the tapered shaft resting on it with a thread are located. The parts or side modules located on each side of the basic module are connected to the basic module such that a connector peg or similar part penetrates into the connector hole formed in the basic module, which connector hole forms a guideway for the connector peg or corresponding part. This allows the connector peg or other part to move in the guideway formed by the connector hole such that the distance of the side module or similar part from the basic module can be adjusted. Most advantageously, the support tube located in the basic module of the modular inlay protruding outward from the biting surface is perpendicular to the basic module’s connector pegs in the connector hole. According to the invention, the support tube is thus used for many different functions, such as a grasping point when moving the modular inlay or grinding some part of it. In connection with cementation, it functions as the frame of the feeding hollow and as the counterpiece of the tapered shaft’s threads. In addition, the modular inlay can be kept, if needed, at a suitable depth and position in the cavity using the support tube until it has adhered to the tooth in the final cementation.

Financially, modular filling is inexpensive for both the patient and the dentist because the dentist does not need to make any expensive investments in equipment. The selection of modular inlay modules available is enough in itself. The patient, on the other hand, saves both time and costs, as a single visit to the dentist achieves a completed inlay that is durable and tightly in contact with the adjacent tooth or both adjacent teeth. It is also advantageous that the industrial production of modular inlays is inexpensive after the initial investments.

According to the invention, a dental inlay is a modular inlay formed from three essential modules or corresponding parts, placed in the cavity of a tooth to be filled, in which dental inlay the distance between the modules or corresponding parts can be adjusted. Thereby, the size of the modular inlay can be adjusted to fit the cavity formed in the tooth being filled and to achieve a suitably tight contact with the adjacent neighbouring tooth or both adjacent neighbouring teeth.

The modular inlay can include a basic module equipped with an adjustment device and a side module and adjustment part located on its opposite sides, which are connected to the basic module such that the distance of the side module and/or adjustment part from the basic module can be adjusted with the adjustment device belonging to the basic module. Thereby, the modular inlay is made to fit the cavity formed in the tooth being filled and, at the same time, a suitably tight contact is achieved with one neighbouring tooth or both neighbouring teeth.

According to a preferred embodiment, the modular inlay includes a basic module that is in the middle, whose side modules located on each side are the front edge module and the back edge module. The side modules are connected to the basic module such that the distance of at least one of the side modules from the basic module is adjustable or the distances of both side modules from the basic module are adjustable. Thereby, by adjusting the distance of the front edge module and/or back edge module from the basic module, the size of the modular inlay can be adjusted to fit the cavity formed in the tooth being filled and to achieve a suitably tight contact with the neighbouring teeth.

According to the invention, the basic module adjustment device, with the help of which the distance of the side module or similar part from the basic module is adjustable, includes a tapered shaft which can be pressed against the inclined surface in conjunction with the side module or corresponding part such that the corresponding module or similar part moves away from the basic module. An alternative course of action is for the distances from the basic module of the side modules or similar parts located on each side of the basic module to be adjustable simultaneously using the tapered shaft belonging to the basic module adjustment device. Thereby, both of the parts located on opposite sides of the basic module can be side modules or other corresponding parts. On the other side of the basic module there can also be a side module and on its opposite side another part.

In the basic module adjustment device there can be a support tube equipped with a thread part and a knob equipped with a thread to which the tapered shaft is connected. The knob equipped with a thread is located in connection with the support tube’s thread part so that the knob can be turned in the thread part. The tip of the tapered shaft connected to the knob is located inside the basic module such that it is against the inclined surface in conjunction with the side module and/or adjustment part such that when the knob is rotated, the side module and/or other adjustment part can be made to move away from the basic module. Thereby, the size of the modular inlay can be adjusted to fit the cavity formed in the tooth being filled and to achieve a suitably tight contact with one neighbouring tooth or both neighbouring teeth. According to the invention, the basic module’s support tube forms a feeding hollow through which the cement cementing the modules or other parts to one another can be injected between the modular inlay’s modules or corresponding parts. The cement can be injected through the basic module’s support tube between the modular inlay’s modules or other parts after the size of the modular inlay has been adjusted to be suitable with the adjustment device belonging to the basic module. The cement can be also injected through the basic module’s support tube between the modular inlay’s modules or other parts at the same time as the size of the modular inlay has been adjusted to be suitable by pushing the modules or corresponding parts away from one another with the adjustment device belonging to the basic module. Also stiff cementing material that cures chemically and/or with light can be spread on the bottom and/or side walls of the tooth cavity. The part of the basic module’s adjustment device above the biting surface is removed from the dental inlay after the cement injected between the modules of the modular inlay has cured and the dental inlay has cemented into place in the cavity.

In the following, the invention is described using examples with reference to the appended drawings, in which

LIST OF FIGURES

Figure 1 shows a diagonal top view of the parts of a modular inlay according to the invention.

Figure 2 shows a diagonal top view of the parts of another modular inlay according to the invention.

Figure 3 shows a diagonal top view of the parts of a third modular inlay according to the invention. Figure 4 shows a modular inlay according to the invention, which is assembled from the modules and parts of the modular inlay shown in Figure 1.

Figure 5 shows a top view of the modular inlay of Figure 4. Figure 6 shows a vertical sectional view of the modular inlay in Figure 5 taken along the line A-A. Figure 7 shows a vertical sectional view of the modular inlay in Figure 5 taken along the line B-B.

Figure 8 corresponds with the sectional view of the modular inlay of Figure 6 in a situation in which the modules’ distance from one another has been changed using an adjustment device.

Figure 9 shows a vertical sectional view of the parts of another modular inlay according to the invention. Figure 10 shows a vertical sectional view of a third modular inlay according to the invention.

Figure 11 shows a vertical sectional view of a fourth modular inlay according to the invention. Figure 12 corresponds with Figure 7 and shows another situation in which the tapered shaft of the adjustment device has been moved to adjust the modules’ distance.

Figure 13 shows a diagonal top view of three adjacent teeth, of which the middle one has had a cavity or depression formed in it, which is formed in the tooth after the removal of caries.

Figure 14 shows a sectional side view of the fitting of the modular inlay of Figure 8 into the tooth cavity before cementation.

Figure 15 shows a schematic view of the initial stage of cementation of the modular inlay of Figure 14, in which cementing material is injected with a filling syringe into the modular inlay.

Figure 16 shows a sectional view of the fitting of the modular inlay into the tooth cavity after the cementing material has been injected into the modular inlay as shown in Figure 15.

Figure 17 shows a vertical sectional view of the fitting of the modular inlay of Figure 10 into the tooth cavity.

Figure 18 shows a schematic vertical sectional view of the cementation stage, in which the modular inlay of Figure 16 is cemented in the tooth cavity.

Figure 19 shows a schematic view of the cementation stage of the modular inlay of

Figure 17, in which cementing material is injected with a filling syringe into the modular inlay.

Figure 20 shows a vertical sectional view of the modular inlay of Figure 18 cemented into the tooth cavity.

Figures 21-25 show a diagonal top view of various embodiments of the modular inlay’s modules.

Figures 26 and 27 show a top view and side view of the modular inlay of Figure 22, situated in the crown of the tooth drawn with a dotted line.

Figure 26 shows a top view of a modular inlay according to the invention.

Figure 27 shows a side view of the modular inlay of Figure 25.

Figure 28 shows a top view of another modular inlay according to the invention.

Figure 29 shows a side view of the modular inlay of Figure 28.

Figures 30-34 show a diagonal top view of various cavities in the crowns of teeth, which can be filled with modular inlays according to the invention. DESCRIPTION OF THE FIGURES

The figures show examples of embodiments of modular inlays according to the invention, with which a modular inlay for canines, bicuspids and/or molars is achieved, the contact areas of which with the adjacent tooth or adjacent teeth are always suitably tight. The modular inlay includes an adjustment device according to the invention, in which the suitable tightness of the contact area is achieved through the joint operation of a support tube and a tapered shaft inside it. Prefabricated industrially, the modular inlay’s parts are durable, tooth shaped and tooth coloured. Figures 1-20 of the drawings show the structure of an MOD-type prefabricated inlay, i.e. forming the mesial, occlusal and distal tooth surface, and cementation stages in the left mandible molar’s cavity between the adjacent teeth. Drawings 21-34 also show alternatives also for filling another type of cavity, whereby the structure of the modular inlay according to the invention used has been fitted to fit the cavity.

Figure 1 shows a diagonal projection and a disassembled view of an MOD-type modular inlay according to the invention, which fits into the tooth cavity shown in Figure 13. The modular inlay of Figure 1 has three main parts, which are the basic module 1 in the middle of the modular inlay and the side modules 14 and 15 on both sides of it, which are a mesial module 15, i.e. the front edge module, extending to the side of the crown of the tooth, and the distal module 14, i.e. the back edge module, extending to the side of the crown of the tooth. These three main parts of the modular inlay also form the occlusal surface, i.e. biting surface, of the modular inlay. The modular inlay of Figure 1 has in both the back edge module 14 and the front edge module 15 fixed connector pegs 16 of the same size, which form a single piece together with the module.

The adjustment device of the modular inlay of Figure 1 has, upright in the basic module 1, a support tube 2 with a thread part 3 made in its upper part. A hole 4 inside the support tube acts as a feeding hollow, through which part of the cementing material at the final attachment stage of the modular inlay is fed into the connector hole 5 inside the basic module 1. The connector hole 5 acts as a guideway for the connector pegs 16 of the mesial module 15 and the distal module 14. There is a marker ring 6 over the support tube, with the help of which the precise depth of the tapered shaft 7 to be pressed into the cementing material in the feeding hollow inside the support tube 2 is known. Onto the tapered shaft 7, a separate ring-like piston 8 is threaded, with the help of which liquid cementing material can be pressed into the feeding hollow 4. The taper-like end of the tapered shaft 7 rests on the inclined surfaces at the ends of the connector pegs 16. By pressing the taper-like end of the tapered shaft 7 against the inclined surfaces of the connector pegs 16, the connector pegs 16 and the side modules 14 and 15 connected to them can be moved sideways, whereby the distance of the modular inlay’s modules 14 and 15 from one another can be adjusted. The side modules 14 and 15 of the modular inlay can thus be pressed against both adjacent teeth and, at the same time, the modular inlay’s contacts can be adjusted to be suitably tight against the adjacent teeth. As presented below, in the modular inlay according to the invention, instead of the side modules 14 and 15 shown in Figure 1 , also other types of parts can be used which can rest on, for example, the wall of the cavity of the tooth to be filled instead of on the adjacent teeth.

In the adjustment device of the modular inlay of Figure 1 , on the end of the support tube 2 a knob 9 is placed, to which the tapered shaft 7 has been attached. The knob 9 has a thread that has been fitted to fit the thread on the end of the support tube 2. By rotating the knob 9 it rotates in the thread part 3 of the support tube 2 until the lower edge of the knob coincides with the upper edge of the marker ring 6. On the surface of the knob 9 is a coloured marker line 10, which shows the current position of the knob 9 being rotated. On top of the knob 9 are holes 11 , into which can be fitted the piston pusher’s 12 pusher pegs 13 which are parallel to one another. The pusher pegs can be used to press the ring-like piston 8 in order to feed the cementing material into the modular inlay.

The modular inlay of Figure 1 is assembled such that the side modules 14 and 15 are connected to the basic module 1 through the connector pegs 16. The distal module 14 and mesial module 15 have angular connector pegs 16 which fit into the corresponding angular connector holes 5 of the basic module 1, preventing the mutual rotation and loosening of the modules at the fitting stage. Part of the angles of the side edges of the connector pegs 16 have been chamfered away so that they form feeding grooves 17, whereby the small gaps remaining between the connector pegs and connector holes 5 form side feeding channels for the liquid cementing material. The side feeding channels start at the inclined tapered surfaces at the ends of the connector pegs 16, the shape of the surfaces being concave, corresponding to the tip of the tapered shaft 7. The tapered surface can also be level, however. Figure 1 also shows an oval contact area 18, drawn with dotted lines, coinciding with the adjacent tooth seen in the mesial module 15.

Figure 2 shows a diagonal projection and a disassembled modular inlay according to the invention. In the basic module 1 in the middle of the upper surface is a support hole 42, in whose inner edges are the corresponding threads to the thread part 3 of the external surface of the tapered shaft 7. The support hole leads into the connector hole 5 inside the basic module 1. The tapered shaft 7 is rotated onto the thread part of the support hole 42 and the inner hole 44 of the knob acts as a feeding hollow 21 and it can be closed with a piston 8 that fits it. The feeding hollow narrows in the tapered shaft 7 into a main feeding channel 22, which is in conjunction with the connector hole 5. On top of the tapered shaft there is a marker ring 6 under the knob 9.

Figure 3 shows a modular inlay according to the invention, in which the tapered shaft 7 with its knob 9 is solid without an inner hole and piston. This solution can be used when the modular inlay is cemented in two stages. The first stage is described in Figure 17 and the second stage in Figure 19.

Figure 4 shows a modular inlay according to the invention, which is assembled from the modules and parts of the modular inlay presented in Figure 1. The essentially three-part modular inlay shown as a diagonal projection consists of a distal module 14, a mesial module 15 and a basic module 1, which are pressed against one another. In the basic module 1 there is a marker ring 6 on top of the support tube 2 and on the support tube is a knob 9 attached to the thread part of the support tube with the tapered shaft 7 remaining hidden inside the support tube 2.

Figure 5 shows the modular inlay of Figure 4 assembled and seen from above.

Figure 6 shows a vertical sectional view of the modular inlay of Figure 5 along the line A-A. In the modular inlay of Figure 6 the tapered shaft 7 has been moved to the initial position by rotating the knob 9. In this case, the connector pegs 16 of the mesial module 15 and the distal module 14 are still in contact with one another inside the basic module 1. The tip of the tapered shaft 7 inside the basic module 1 touches the inclined surfaces of the ends of the connector pegs 16 without yet at this point moving the distal 14 and mesial 15 modules away from one another. On top of the support tube 2 is a marker ring 6, which the lower edge of the knob 9 thereby coincides with. The ring-like piston 8 around the tapered shaft 7 is in the hole 4 inside the support tube 2 inside the knob 9, resting on the base of the tapered shaft 20. Figure 7 shows a vertical sectional view of the modular inlay of Figure 5 along the line B-B.

Also in the modular inlay of Figure 7 the tapered shaft 7 is in the initial position. Around the tapered shaft 7 in the hole 4 inside the support tube a feeding hollow 21 is formed from which main feeding channels 22 lead to the end of the connector peg 16 shown in the connector hole in the basic module 1. Between the angles of the connector peg’s feeding grooves 17 and the connector hole are shown four small side feeding channels 23. Figure 8 shows a vertical sectional view corresponding to Figure 6, in which the distance of the modular inlay modules from one another has been changed using the tapered shaft 7. The knob 9 of the modular inlay has been rotated such that the tapered shaft 7 has moved deeper in the support tube 2. Thereby, the sharp tip of the tapered shaft 7 has sunk between the ends of the connector pegs 16 against the inclined surfaces at the ends of the connector pegs 16. Thereby, the tapered shaft 7 penetrating between the ends of the connector pegs 16 pushes the side modules, i.e. distal module 14 and mesial module 15, away from one another, adding to the total length of the modular inlay and simultaneously pressing the modules 14 and 15 against the neighbouring teeth. At the same time, the marker ring 6 around the support tube 2 and the piston 8 around the tapered shaft 7 have moved, by being pressed by the lower edge of the knob 9 and the base of the tapered shaft 20 towards the basic module 1. According to the invention, this adjustable characteristic that increases the inlay module’s total length always guarantees tight contacts for the modular inlay with the adjacent teeth. At the same time, the tight contact prevents the modular inlay from sinking too deep into the tooth to be filled.

Figure 9 shows a modular inlay which is assembled from parts of the modular inlay presented in Figure 2. In this modular inlay, instead of a support tube, a tapered shaft with its knob 9 equipped with a hole inside it has been rotated into the support hole of Figure 2. The feeding hollow 21 inside the knob 9 continues in the tapered shaft as a main feeding channel 22. In the situation of Figure 9, the knob 9 of the tapered shaft has been rotated in the counter thread of the support hole 42, whereby the tapered shaft 7 has partially sunk between the connector pegs 16 in the basic module 1, against the inclined surfaces at their ends. At the same time, the marker ring 6 touching the basic module 1 has moved, by being pressed by the basic module 1, around the tapered shaft away from the basic module 1. Thereby, all of the functions of the modular inlay can be carried out as in Figure 8.

Figure 10 shows a modular inlay which is assembled from parts of the basic module presented in Figure 3. In this inlay module, the support tube has been removed and in its stead is a tapered shaft 7 with its knob 9 rotated into the support hole 42 shown in Figure 3. The tapered shaft is solid without an inner hole. Figure 11 shows an inlay module in which the tapered shaft is blunt without the taper. Thereby, the tapered shaft rests against the connector pegs via a V-shaped lever mechanism. The support tube 2 in the middle of the basic module 1 opens up into the connector hole 5 such that the end of the blunt tapered shaft coincides with the hinge point of the lever mechanism 43, which connects two levers. When the end of the blunt tapered shaft presses on the hinge point, the lever mechanism opens up to become longer in the connector hole 5 and the ends of the lever mechanism push the connector pegs 16 with their modules further away from one another. The same mechanism can also be used if in the middle of the basic module 1 instead of a support tube there is a support hole 42, onto whose thread the tapered shaft 7 can be rotated.

Figure 12 shows a sectional view corresponding to Figure 7, in which the tapered shaft 7 has been moved for the adjustment of the side modules. As shown in Figure 6, the tapered shaft 7 has moved deeper into the connector hole 5, whereby at the same time the sharp tip of the tapered shaft 7 pushes the side modules 14 and 15 away from one another. Thereby, also the feeding hollow 21 has become somewhat shallower and its volume has thus decreased. The sharp tip of the tapered shaft 7 is also deeper in the connector hole at the inclined surface at the end of the connector peg 16. Figure 13 shows a diagonal top view of three teeth, of which the middle one, i.e. the left mandible molar to be filled 24 has had formed in it an MOD-type cavity 25, i.e. depression, partly drawn with a dotted line, which remains in the tooth after the removal of caries. Figure 13 shows the bottom 26 and the side wall 27 of the cavity. The length of the cavity determines the total length of the required modular inlay from the contact point of the first neighbouring tooth 28 of the mandible molar 24 to the corresponding contact point 30 of the edge of the second neighbouring tooth, i.e. the tooth 29 on the opposite side of the mandible molar 24.

Figure 14 shows as a vertical sectional figure from the side the fitting of the assembled three-part modular inlay into the cavity 25 of the tooth to be filled 24 between the neighbouring teeth 28 and 29 before the final cementation. This enables the checking of the fit of the modular inlay in the cavity 25 of the tooth and the grinding of the module to a suitable size if needed. At the initial stage of the fitting, different-sized modular inlay replicas can be used.

In the situation shown in Figure 14, the nob 9 has been rotated such that the sharp tip of the tapered shaft 7 has sunk between the connector pegs 16 against the inclined surfaces at their ends and, at the same time, moved the distal module 14 and medial module 15 away from one another adding to the total length of the modular inlay. At the same time, seam gaps 31 have formed in the spaces between the basic module 1 and the distal module 14 and medial module 15.

In Figure 14, the rotating of the knob 9 is continued until the contact areas of the modules 14 and 15 are pressed sufficiently tightly into the contact points of the neighbouring teeth 28 and 29. The tightness can be tested if needed using dental floss. At the same time, the marker ring 6 has slid, by being pressed by the lower edge of the knob 9, along the support tube 2 towards the basic module 1. The direction of the coloured marker line 10 of the knob 9 thereby indicates the precise rotational position of the knob 9. It is memorised so that the same contact tightness can be achieved when filling. According to the invention, this characteristic that increases the modular inlay’s total length always guarantees the pre-tested modular inlay’s suitably tight contact with the neighbouring teeth. Finally, the modular inlay is detached from the neighbouring teeth by detaching the tapered shaft 7 from the connector pegs 16 by rotating the knob 9 until the modular inlay can easily be removed from the cavity 25. Thereby, the gap left between the marker ring 6 and the knob 9, together with the direction of the knob’s coloured marker line 10, indicate the desired contact tightness.

Figure 15 shows a vertical sectional view of the initial stage of cementation of the assembled three-part modular inlay of Figure 14 outside of the mouth. The knob 9 of the modular inlay with its tapered shaft 7 and piston 8 has been disconnected and into the hole 4 located inside the support tube 2, with a filling syringe 40 that fits it tightly, so much highly liquid chemically or light-cured cementing material 32 has been injected that it overflows out of the seam gaps of modules 1, 14 and 15.

After that, while holding on to the knob 9, the tapered shaft 7 with its piston 8 is pressed into the cementing material in the hole of the support tube 2 and rotated in the thread part so that the lower edge of the knob 9 does not coincide with the marker ring 6. This ensures that the assembled modular inlay fits between the neighbouring teeth 28 and 29. Thereby, the liquid cementing material is in the seam gaps of all of the modular inlay’s parts, in the connector hole, feeding channels and feeding hollow.

Figure 16 shows a sectional view of the fitting of the assembled modular inlay of Figure 15 back into the tooth cavity, onto the bottom 26 and sidewalls 27 of which a chemically curing stiff cementing material 33 has been spread. The tapered shaft 7 with its knob 9 is attached to the thread part of the support tube 2. The modular inlay is pressed into place holding on to the support tube 2 and knob 9. If needed, a thin matrix band 34 supported with wedges 35 can be placed between the tooth to be filled and the neighbouring teeth beforehand to prevent the build-up of cementing material on the edges of the cavity.

Figure 17 shows a sectional view of the final placing of the modular inlay of Figure 10 back into the tooth cavity, onto the bottom 26 and side walls 27 of which a chemically curing stiff cementing material 33 has been spread. In contrast to the measures required in connection with the modular inlay shown in Figure 16, in Figure 17 the cementation stages can easily be carried out in two stages so that in the first stage no liquid cementing material 32 has been injected inside the modular inlay outside the mouth. The modular inlay is pressed into the cavity’s cementing material 33, holding on to the tapered shaft’s knob 9 and by rotating the knob, a pre-tested suitably tight contact with the neighbouring teeth is adjusted. The cement is allowed to cure and attach all of the modular parts 1, 14 and 15 to the cavity. In this figure, the tapered shaft 7 with its knob 9 is solid without an inner hole. Otherwise, the procedure is as in connection with the modular inlay shown in Figure 16.

Figure 18 shows a vertical sectional view of the final stage of cementation of the assembled three-part modular inlay of Figure 16, whereby the three-part modular inlay is cemented in its final position in the cavity 25 of the tooth to be filled 24. The side modules 14 and 15, moved by the tapered shaft 7, have now been made to be in tight contact with the neighbouring teeth 29 and 28 by rotating the knob 9 on the thread part of the support tube 2 until the knob 9 is in contact with the top edge of the marker ring 6 and the direction of the knob’s coloured marker line 10 corresponds with the position of the modular inlay’s fitting stage.

When moving the modules 14 and 15 of the tapered shaft 7 of Figure 18 away from one another, liquid cementing material 32 is absorbed between them through the side and main feeding channels due to the pressure differential exerted on the connector hole 5. As the seam gaps 31 expand, it may be absorbed deeper away from the biting surface and away from the feeding hollow 21 as the piston 8 glides along the tapered shaft 7 as air flows above the piston 8 through the holes 11 in the knob. Finally, the pusher pegs 13 of the piston pusher 12 have been fitted into the holes 11 of the knob and with its help, the ring-like piston 8 has been pressed to the bottom of the feeding hollow 21. Thereby, the highly liquid cementing material is forced as by an injection syringe to travel from the feeding hollow through the main and side feeding channels to the seam gaps of the connector pegs 16 and connector holes 5.

If the liquid and/or stiff cementing material in the situation of Figure 18 does not extend to the external surface of the tooth to be filled in the modular inlay’s seam gaps or some wall of the cavity, cementing or filling material can be injected immediately into the remaining areas even before final curing. After that, the cementing or filling material cures or is cured and the support tube 2 with the tapered shaft 7 is removed from above the biting surface by cutting. Thus, part of the tapered shaft 7 remains inside the inlay module between the parts. Finally, all excesses are removed and the occlusion is checked.

Figure 19 shows a vertical sectional view of the modular inlay parts of Figure 17 cemented to the cavity 25 of the tooth 24. At the second stage of cementation, the tapered shaft with its knob is detached from the basic module 1 and liquid cementing material 32 is injected directly into the support hole 42, until it fills the modular inlay’s internal parts and also the seam gaps 31 fill. Finally, the tapered shaft with its knob is fitted back into the support hole 42 and by rotating the knob, the tip of the tapered shaft can be made to coincide with the connector pegs 16. At the same time, liquid cementing material in the support hole penetrates into the seam gaps and once it cures the modular parts are tightly attached to one another. Otherwise the procedure in connection with the modular inlay shown in Figure 19 is the same as described in connection with Figure 18.

Two-stage cementation avoids the risk of, when placing the modular inlay into the cavity, the liquid cementing material 32 already injected inside it curing too quickly, thus preventing the tapered shaft from moving the modular parts apart from one another. Thereby, suitably tight contacts cannot be made with the neighbouring teeth. Also stiff cementing material 33 may cure before the modular inlay is in the desired position in the cavity. Two-stage cementation can be used also in other modular inlays according to the invention presented above.

Figure 20 shows a vertical sectional view of the final cementation of the modular inlay of Figure 18 seen from another direction. The tip of the tapered shaft 7 does not yet coincide with the bottom of the connector hole 5 because the modular inlay in this example is already in contact with the adjacent teeth 28 and 29. The pusher pegs 13 of the piston pusher 12 have moved the piston 8 to the bottom of the feeding hollow 21 and, at the same time, almost all of the liquid cementing material has moved along the main feeding channels 22 to the connector hole 5 around the tip area of the tapered shaft 7. Figures 1-20 show the structure of an MOD-type prefabricated inlay, i.e. forming the mesial, occlusal and distal tooth surface, whereby a modular inlay that fits it is used for filling it. Figures 21-29 show alternative modular inlay structures and Figures 30-34 show diagonal top view examples of teeth in the crown of which are formed various cavities in which the alternative modular inlay structures can be used. The modular inlays shown in Figures 21-25 fit these cavities such that modular inlay 21 fits the cavity 30, modular inlay 22 fits the cavity 31 , modular inlay 23 fits the cavity 32, modular inlay 24 fits the cavity 33 and modular inlay 25 fits the cavity 34.

Not described in the modular inlay examples shown in Figures 21-25 are the parts belonging to the adjustment and filling device of the modular inlay’s basic module, such as the tapered shaft 7, the piston 8 and the knob 9. The shown examples indicate that a large number of different modular inlays according to the invention can be assembled from just a few different coloured and different types of modules.

In the cavity of the tooth to be filled according to the invention is always achieved a suitably tight contact using a modular inlay, which essentially includes three essential parts. It depends on the shape and size of the tooth cavity to which surface the modular inlay’s suitably tight contact applies. This surface can be the surface of the adjacent tooth, but it can also be the vertical wall of the cavity.

The main parts of the basic structure of the modular inlay according to the invention are the middle part, i.e. the basic module, and the side modules located on both sides of it. In the basic module is an adjustment device with which the side modules can be adjusted so that the side modules move away from one another. With the help of the side module adjustments, the size of the modular inlay can be adjusted such that the opposite edges of the modular inlay form a suitably tight contact with the opposing surface on both sides of the modular inlay. The opposing surfaces are different depending on what kind of cavity has been formed in the tooth to be filled, whereby also the assembly of the modular inlay according to the invention used for filling varies correspondingly.

In the structures shown in Figures 1-20, the modular inlay according to the invention includes a basic module 1 and side modules 14 and 15. For the assembly of the modular inlay, the side modules 14 and 15 are equipped with connector pegs 16, which are pushed from opposite sides into the basic module 1 into the connector hole 5 in the basic module 1. At the end of the connector pegs 16 are inclined surfaces against which the tapered shaft inside the basic module 1 is pressed so that the side modules 14 and 15 move away from one other. Depending on the shape and size of the cavity formed in the tooth to be filled, the modular inlay according to the invention can, however, also be assembled from other types of parts according to the invention.

When a cavity that extends through the whole tooth as shown in Figure 13 is made in the tooth to be filled, the modular inlay is formed from the basic module 1 located in the middle and the side modules 14 and 15 located on both of its sides, which are the mesial module 15, i.e. front edge module, extending to the side of the crown of the tooth to the surface of the adjacent tooth, and the distal module 14, i.e. back edge module, extending to the side of the crown of the tooth to the surface of the opposite adjacent tooth. With the basic module adjustment device, the size of the modular inlay can be adjusted to be suitable so that both of its opposite ends form a suitably tight contact with the teeth adjacent to the tooth to be filled.

However, if in the tooth to be filled 24 a cavity 25 has been made, which also opens to the side of the tooth to the tongue or cheek side as is shown in Figure 30, the basic module 1 , which has a protrusion 36 directed sideways as is shown in Figure 21, is used as the middle module of the modular inlay. The protrusion 36 of the basic module 1 can be formed such that it fits the opposite sides of the tooth simply by rotating the basic module on the support tube. In Figures 22 and 25 in the modular inlays there is only a module on one side in the basic module. In this instance, the connector hole 5 drawn with dotted lines is closed at the other end with a loose connector peg 19. It is needed when filling to fill the second opening of the basic module’s 1 connector hole 5 so that the tapered shaft spreads the connector pegs away from one another whereby the modular inlay rests one of its edges on the adjacent tooth and the other edge on the vertical wall of the cavity.

The cavity 25 made in the tooth to be filled 24 is not always so large that it extends from one edge to the other edge of the tooth to be filled 24, as shown in Figure 13. If the cavity 25 made in the tooth to be filled 24 only extends to one edge of the tooth, as shown in

Figure 32, a modular inlay shown in Figure 32 is used. In the modular inlay shown in Figure 32, on the first side of the basic module 1 as a side module is the front edge module 15, which rests on the adjacent tooth’s surface when filling. As, on the other side of the basic module 1, instead of the adjacent tooth to the tooth to be filled, there is the cavity’s vertical wall, so on this side the side module is the biting surface module 41 that rests on the cavity’s vertical wall. In the biting surface module 41 is a corresponding connector peg 16 as in the side modules, so the biting surface module 41 is connected to the basic module 1 connector hole 5 using the connector peg 16. In this instance, the distance of the front edge module 15 and the biting surface module 41 from one another can be adjusted using the basic module 1 adjustment device, whereby a suitably tight contact can be achieved between the adjacent tooth surface and the cavity’s vertical wall.

When the cavity 25 made in the tooth to be filled 24 is only a pit in the middle of the crown of the tooth, as shown in Figure 33, a modular inlay as shown in Figure 24 is used. In the modular inlay shown in Figure 24, on both sides of the basic module 1 are biting surface modules 41, which have connector tabs 16 for connecting the modules 41 to the basic module 1. The distance of both biting surface modules 41 from one another is adjusted using the basic module 1 adjustment device, whereby a suitably tight contact is achieved between the cavity’s opposite vertical walls.

In the situation shown in Figure 31, a cavity has been made in the tooth to be filled 24 which extends to one end of the tooth and to one side wall. In this type of case, an inlay module as shown in Figures 22, 26 and 27 can be used. In the inlay module on the first side of the basic module 1 as a side module is the front edge module 15, which rests on the adjacent tooth’s surface when filling. As in this case there is no room for a side module on the other side of the basic module 1 , so in its stead there is only a loose connector peg 19 corresponding to the side module connector peg 16. The distance between the front edge module 15 resting on the adjacent tooth and the loose connector peg 19 resting on the cavity’s vertical wall can be adjusted using the basic module 1 adjustment device, whereby a suitably tight contact can be achieved between the adjacent tooth surface and the cavity’s vertical wall.

The cavity’s vertical wall can be too far from the loose connector peg 19, not providing support when the tapered shaft pushes it and, on the other hand, the biting surface module is too large to replace the loose connector peg 19. In that case, the modular inlay according to the invention works such that some point of the edge on the side of the loose connector peg of the basic module 1 rests on the vertical wall of the cavity when the tapered shaft spreads the connector pegs apart from one another. The modular inlay works even if there were only two adjacent parts that rest on the adjacent tooth and the cavity’s vertical wall. In Figures 21 , 23 and 24, the modular inlays are three-part and consist of, in addition to the basic module 1, the mesial module 15 and the distal module 14 in Figure 21. In Figure 23, the modular inlay consists of the basic module, mesial module 15 and the biting surface module 41. In Figure 24, the modular inlay consists of the basic module and two biting surface modules. The modular inlay of Figure 24 consists of parts such that it can be made to rest on the cavity’s front and back edge at the cementation stage. This support prevents the modular inlay from sinking too deep in the cavity into the cementing material placed at its bottom. This ensures the evenness of the biting surface without differences in height at a seam.

The tooth to be filled 24 can also have a partial crown. Figures 25, 28 and 29 show a modular inlay which has a partial crown and the modules are attached to one another with a connector peg 16 and one or more additional connector pegs 37. The corner module 38 of the partial crown of Figure 25 can be moved on the connector peg 16 and the parallel additional connector peg 37 in the basic module connector hole 5 and the additional connector peg’s counter hole 39. Figures 28 shows a top view of the modular inlay of Figure 25, drawn with a dotted line, situated in the crown of the tooth, which has a partial crown 38. Figure 29 shows a side view of the same modular inlay.

LIST OF REFERENCE NUMBERS

I Basic module 2 Support tube

3 Thread part

4 Hole inside the support tube

5 Connector hole

6 Marker ring 7 Tapered shaft

8 Piston

9 Knob

10 Coloured marker line

I I Hole 12 Piston pusher

13 Piston pusher peg

14 Distal module or back edge module

15 Mesial module or front edge module

16 Connector peg 17 Feeding groove

18 Contact area

19 Loose connector peg 21 Feeding hollow 22 Main feeding channel 23 Side feeding channel 24 Tooth to be filled

25 Cavity

26 Bottom of the cavity

27 Side wall of the cavity

28 First neighbouring tooth 29 Second neighbouring tooth

30 Tooth contact point

31 Seam gap

32 Liquid cementing material

33 Stiff cementing material 34 Matrix band

35 Wedge

36 Basic module protrusion

37 Additional connector peg

38 Partial crown’s corner module 39 Additional connector peg’s counter hole

40 Filling syringe

41 Biting surface module

42 Support hole

43 Lever mechanism

Inner hole of the knob