WO2005013846A1 - Dental implant with an integral structure comprising a stump completely or partially realized in advance - Google Patents

Abstract

A single-phase dental plant with a single structure comprising a stump realized in advance, in the full variant VP, or partially realized in advance in the hollow variant VC, that may be personalized and applied during one single surgical visit; consisting of one single structure and united to the body of the plant to be inserted into the bone-called fixture-already during making, so as to be filed immediately after the operation directly in the mouth of the patient straight away in the full variant, and after having reconstructed the intra-oral stump in the hollow variant, thus resulting suitable for the correct insertion of the prosthesis: in fact, it is the truncate-cone shape-called abutment- of the stump inserted in said fixture, in the full variant, that allows to model, directly in the mouth of the patient with a preparation cutter mounted onto a turbine, a stump provided with the correct inclination of the correct prosthesis rehabilitation, while the shell of the hollow variant, allows the dentist to personalize the stump, making it with a pin out of zirconium fibre and with a compound of polimerized protected from fluids, due to said structure in the shape of a shell that insulated them from the mucosa, so as to obtain a stump with the desired inclination in the desired moment.

Description

DENTAL IMPLANT WITH AN INTEGRAL STRUCTURE COMPRISING A STUMP COMPLETELY OR PARTIALLY REALIZED IN ADVANCE

5 The present invention concerns a dental plant complete with a stump realized in two variants: realized in advance in the full variant, or partially realized in the hollow variant, so as to make it completely personalized and suitable for being applied in one single surgical visit: in-fact, being out of one single structure, no further

10 surgical re-entry is expected. Said stump realized in advance is united to the body of the plant that will be inserted into the bone, usually called 'fixture' since realization and may be filed immediately after the surgical operation already in the mouth of the patient: immediately in the full variant and after the reconstruction

15 of the intra-oral stump in the hollow variant. According to the present invention, a stump may be obtained suitable for the correct insertion of a prosthesis: in fact, it is due to the shape of a truncated cone - called 'abutment' - of the stump inserted into said fixture - in the full variant - that it will be possible to shape, directly in the

20 mouth and with the help of a preparation cutter mounted onto a turbine, a stump having the correct inclination for the correct prosthesis rehabilitation.

Furtliermore, the funnel-shaped shell of the trans-mucous part of the

25 stump, in the hollow variant, allows the dentist to personalize the stump, realizing it with a pin out of zirconium fibre and with a polimerized compound safe from fluids, due to just said funnel shape that insulated them from the mucous membrane, so as to obtain a stump with the desired inclination in the desired moment; in the hollow variant, the plant may be partially covered for the time desired, just surfacing from the mucous membrane and thus behaving like a trans-mucous plant. Furtliermore, once the stump has been filed, it may be obtained that said stump has an axis coinciding or angled with respect to the one of the fixture, according to the needs. Therefore, it will be easy, in the presence of a good primary stability, to construct and cement in the same visit a provisional tooth or a definitive crown (it is suggested to make use of compound or baked clay).

For what concerns the art known up to now, the plants are prosthesis' out of titanium inserted into the bone for replacing or imitating the functions of the missing root of natural teeth. Onto said plant, a prosthesis crown is built in a prosthetic process. Essential condition for performing the implantology is the presence of bone sufficient for their integration with said bone. If there is too little bone, there are a series of techniques provided for bone regeneration.

In the presence of an edentate bony crest with a bone sufficient in quality and quantity, the plant may be inserted after having prepared a periosteal-mucus border or an operculum; now, a hole is performed in the cortical and a housing suitable to the shape of the plant that is to be inserted, mainly cylindrical or conical, with special cutters and imder abundant irrigation or with special osteotomy. The fixture gets inserted by screwing in tlie prepared channel, in tlie case of screw plants, after tapping - if tlie kind of plant provides it - and after having disassembled tlie possibly present 'mouth', tl e head of tlie plant is closed with a sort of cap screw. In the case of impact plants, tlie insertion takes place by means of little strokes with special instruments. It will be tried to position the head of the plant, where tlie cap screw will be screwed, in that aera that allows the best aesthetic and fimctional results, and tlie latter often will coincide with the edge of tl e bony crest. The area will be washed and the border sewed or, in tl e case of an operculum, tlie plant will be left open, or it will be protected with substances like calcium sulphate or collagen.

In tlie case of a post-extraction plant, the tooth or the dental root is pulled out and immediately the plant is inserted, after having prepared the site with special cutters mounted onto a strick and fisiodispenser, or by osteotomy. It will be tried to adjust tlie shape of the alveolus and to get lower beyond the alveolus so as to assure tlie primary retention, which is an essential requirement for tl e success of tlie plant.

It will be tried to insert the plant in tlie shape tlie most similar to tl e shape of tlie dental root that is to be prostlietically replaced. Should tl e bone be insufficient, it will be necessary to turn to vertical and horizontal bone regeneration techniques, like split crest, tlie use of membranes, grafts with alloplastic materials or taking of tlie bone, etc.

If tlie bone is sufficient in quantity and quality, tlie insertion can be performed immediately; otherwise, it is good to leave tlie plant covered and later on perform a surgical re-entry - two to six months later - for inserting the recovery screw that conditions tlie recovering of tlie mucosa or the stump directly.

Now the imprint is taken with transferts and laboratory homologous', that may reproduce tlie same position of the fixture on the models. In the laboratory, a special stump will be prepared with different methods - filed and pre-shaped, that may be calcined ... The technician will realize also the structure of the crown - if it is a crown out of metal and baked clay or metal and resin - that will be covered with baked clay or resin, or even the complete crown, if that crown is out of resin, compound or other compatible materials. Once the different tests have been performed in tl e mouth of the patient, the stump will be cemented or screwed - if the stump is to be cemented or screwed - and its inner hollow space will be filled with some compound and the crown will be cemented with suitable material. Also tlie screwed prosthesis may be used, as it is easier to be managed should there arise any problem with tlie plant. Furthermore, there are other kinds of plants, like tlie Tramonte screws or tlie AT-plants, consisting of one single piece. The correct inclination of tlie extra-bone part fonning tlie stump is obtained by deforøiing with pliers, and directly in Hie mouth of tlie patient, the structure of tlie plant so tliat the area that works as an abutment will be parallel to die contiguous structures, for allowing tlie insertion of the prosthetic crown.

Most of die existing plants - with exception of those having die shape of a blade, of a tripode etc. - consist of a fixture of different possible shapes - cylindrical, conical, with variable conicity - and of a stump tiiat may be cemented or screwed. These two parts are separately supplied and will get united after having chosen tlie suitable stump only in die moment the surgeon performing die plant considers well-timed, and this may be during die same visit in the case of a plant with immediate application, or later on in time in die case of plants with deferred application. The stump, or abutment, may be out of titanium or other materials, among winch zirconium or the compound, pre-shaped, straight or with angles previously shaped with respect to the axis along the fixture, or tiiat may be calcined and realizable in laboratory. Said stump will be fixed to die fixture by means of a device of the male-female kind of different shape - octagon or hexagon, internal or external, widi different indentations, etc - tiiat allows a first primary retention, increasing in a way directly proportional to its lengtli. In die case of the screwed stump, die abutment and die fixture are kept together by a screw passing through the hollow structure inside tlie same. In spite of the supply of a dynamometric key for tightening die screw, it may happen tliat tlie latter loosens, mostly in tlie case of bruxist patients or in case of error in tlie gnatologic planning. This will determine a chronic movement of tlie abutment from which a facture of the passing-through screw, of tlie stump or of the same fixture may derive. This means that the weak ring of the chain is the screw: tlie many tests the surgeon sometimes has to perform, tlie insertion and the removal of the cap screw, of the screw, of tlie transfert, of tlie stump may cause the ftuther wearing and deteriorating of the passing-through screw and of the threading inside the fixture.

It is tlie aim of the present invention to realize a plant consisting of one single piece - in its full and hollow variants - containing inside die fixture (tiiat is to be inserted in the bone and tiiat may be similar, in its outer side, to a screw fixture probably most used at present), and the stump, united already by the maker.

The installation of tlie plant according to tlie present invention comprises a new surgeon teclmique that provides die access to the bone without the preparation of a border, but due to the realization of an operculum performed with a radio-scalpel, a mucotomous, a blade scalpel by means of which a holecan be performed in the bone with a cutter mounted on strick on fisiodispenser or witii osteotomy and/or different scalpels of a dimension similar to the one of die plant to be inserted. By means of tlie analysis of images like Dentascan, an orto-panoramic, indooral x-rays etc., witii external trans-mucous sounding, with needles, files, straight stylets etc., with an internal vision by means of illuminated optics or, even better, by means of a surgical microscope, tiie quantity of bone at disposal may be determined. Tins makes tlie preparation of a periosteal-mucus border useless if not even damaging because if on one side it facilitates a direct vision, on the other hand it takes away nutrition to the tissue that is to be used for the insertion of tiie plant. The consequence will be a worse irroration, a lacking regenerative contribution to the periosteum in the period immediate after tiie operation, an aestiietical damage with possible scars. When tiie border is prepared, also surgical errors are penalized. Witii the use of this teclmique, possible perforations or accidental fractures of tlie cortical may be easily repaired, because tl e periosteum and die soft tissue all around will remain adherent aild will continue to nourish tiie cortical: it will be sufficient to imderstand the error and to insert tiie plant inside said perforated part, which will then repair itself. The performance itself will be facilitated also, as it will not be necessary to engage medical personnel for keeping the border lifted: sometimes it is even possible to insert tiie plant by oneself. This teclmique provides for a success rate of 100% if correctly performed, but it is in contrast with the known ones which provide tliat the plant must be protected by well-sutured mucosa around and over said plant. With tins teclmique the plant may remain exposed to tiie oral ambient, even witii various turns exposed: in fact, die coagulum of die post-operation or a calcium-sulphate compress will prevent the germs from contaminating the plant immediately after tlie operation. It may also happen tiiat in some post-extractive plants tiie alveolus does not bleed as much as to form a considerable coagulum: tiie plant thus inserted will be exposed therefore of a plurality of turns and therefore it will be contaminated by the germs of tiie oral surrounding: a correct oral hygiene, that may be helped by washing witii "chlorexidine" or other antibiotic, and an antibiotic covering will allow tiie complete recovering of the plant. A fundamental condition for this to happen is tiie primary stability of tiie plant. Another advantage of tlie teclmique according to the present invention is tiiat the patient will not show a post-operation edema, nor pain and this makes unnecessary tiie use of cortisone: this is due to the fact tiiat the tissues have suffered only a small trauma and tliat, in any case, tlie liquids drain: in fact, no sutures are used. This implied also reduced costs: tiie only alloplastic material required is calcium sulphate, which is not expensive. Furthermore, the present invention provides tlie application of a sheath projected in such a way tliat it may be divided into two parts: one that must remain sterilized until it is opened - which coincides with tiie moment just before the insertion of tiie plant - and tiiat contains tlie fixture; and one tiiat may be opened before, so as to allow tiie preparation of tlie stump contained therein in a laboratory or directly during operation.

From what described hereinabove, the advantages deriving from the present invention appear evident. Two variants of a single-phase dental plant witii a single structure comprising a stump completely or partially realized in advance, according to tiie present invention, will be shown hereinbelow relating to the enclosed drawings.

Figure 1 shows a single-phase dental plant witii a single structure comprising a stump completely or partially realized in advance, according to ti e present invention, with the stump already realized in tiie frill or VP variant.

Figure 10 shows a single-phase dental plant with a single structure comprising a stump completely or partially realized in advance, according to the present invention, in the hollow or VC variant, so as to be personalized, and shows tiie fixture that must be inserted into the bone.

Once a stump has been obtained suitable for tiie correct insertion of tiie prosthesis, tiie shape of a truncated cone of tiie abutment in tiie VP allows to model, according to figure 4, directly in die patient's moutii witii a preparation cutter mounted onto a turbine M, a stump D as shown in figures 4 and 5, with the correct inclination for the correct prosthesis rehabilitation.

The shell in tlie shape of a funnel D as shown in figure 10 allows the dentist to personalize the stump, realizing tiie same witii a pin G out of a zirconium fibre and a compound H as shown in figure 15, so as to obtain a stump with the desired inclination, as shown in figure 17, and in tiie desired moment, as in the VC tlie plant may remain partially covered for the time desired just surfacing from tlie mucosa, as shown in figures 19 and 20, and thus behaving like a trans-mucous plant. Once it has been filed, a stump may be obtained having a coinciding axis as shown in figure 18, or edged with respect to the axis of the fixture.

In tlie full variant, the fixture A if figures 1 and 2 must have a cylindrical or conic shape so as to be inserted into tiie hole performed by the odontologist in the bone by means of special cutters, ti e last of which must show the shape tiiereof, even if slightly thinner, for allowing a primary retention of tiie fixture. The latter may be obtained also due to turns B shown in figures 1 and 2, whereby the shape and pitch tiiereof may be varied and/or agreed with tlie maker and may be superimposed to the one of an already tested plant, until the passage area between titanium and zirconium, shown in figures 1 and 2, i.e. in the limit area between tiie neck C of ti e plant and the stump D, arrives to tiie limit of tiie bony crest I. The turns are industrially treated so as to show a rough surface for improving ti e bone integration; tlie turns end in tiie area of tiie plant's neck: said area will be smooth, of variable lengtli, preferably 2 mm long and witii a cylindrical shape. The part tiiat works as a stump in turn consists of two parts: the first part D', defined 'trans- mucous', and shown in figures 1, 2, 9 may be cylindrical or in tiie shape of a truncated-cone turned upside down; the second part D" of tiie oral kind, in the shape of a truncated-cone turned upside down as shown in figures 1, 2, 9. If the first one is cylindrical, it will have tiie same diameter of the fixture in tiie area of tiie neck and a height of about 2 mm; if it has the shape of a truncated-cone turned upside down, it will have as its smaller basis a circle, passage point between tiie titanium neck and this area I tiiat will act as a trans-mucosa, and its major basis will be another, greater circle L shown in figure 1, that will mark tiie passage between the first part crossing tlie mucosa and tiie second part projecting from tiie oral cavity; the second part - tiie truncated-cone D" - will have a major conicity than the first one; the two parts may also be made in such a way that the passage is not clean but gradual, shaped with concave or convex walls; tiie second oral part may also have tiie shape of a hemisphere; the first part D' of figure 1 may also be made with different heights for better encountering the fimctional and aesthetic needs of the implantologist: in fact, this is that part of tiie trans-mucous plant for which it will be easy to choose a plant with a low trans-mucous part, e.g. 1.5 mm, if tlie patient has a small adherent gingiva, or a higher part if tiie soft tissues are very thick. The second part will be preferably inserted at least haf a millimetre under tiie level of the mucosa, from tiie part of the smaller base of the truncated-cone L. The trans-mucous and extra-mucous portions may also be made - for better simulating the anatomy of tiie incisor teeth - with an elliptic section D' and D" as shown in figure 3, and with bio-compatible material like zirconimn, with different colouring so as to better simulate the natural tooth even in tiie trans- mucous portion, mainly after a possible mucous recession: in this case, of course, tiie truncated cones turned upside down will have an elliptic shape, except for tiie smaller basis witii which they get connected to tiie titanium of tlie circular fixture, as shown in figures 2 and 3. The stump projecting in the oral cavity and that forms one single piece with tiie trans-mucous portion will therefore be realized out of zirconimn and possibly available in the different colouration of tl e Vita-scale, and will have the shape of a truncated-cone turned upside-down, witii the major roimd base having tiie shape of a crown more that the lower one. In any case, a structure D'" is provided at tiie centre of tlie wider base of the upside-down truncated-cone, out of zirconium, and having a cubic shape as shown in figures 1, 2, 8 and 9. Said structure D'" has die function of a hold: as shown in figure 8, a small key P may be inserted and when said key gets stuck, it makes force onto the internal part of the plant allowing to move it at one's desire and therefore to screw it onto the bone. This means that the hold D'" has a function similar to the Mountii but while the latter may be removed by unscrewing, said hold may be easily filed at tiie end of the visit. A fissure performed in die end of tlie second part of the stump may have ti e same function, because a screwdriver may be inserted therein for screwing tiie plant.

The shape of an upside-down truncated cone of die stump allows to insert die plant in the preferred position, determined by the particular fimctional needs and by the inclination of the bony crest: in fact, it will be possible to obtain from tiiat upside-down truncated-cone a stump witii an axis parallel to tiie one of tiie teeth nearby, after having ground them by means of tiie cutter M shown in figure 4, mounted onto tlie dental turbine shown in figure 4, or directly in the moutii of the patient. This means tiiat it will be possible to obtain a stump witii an inclination of tlie axis suitable for obtaining a correct prosthesis, notwithstanding tiie portion of ti e plant inside tiie bone has an axis witii a different inclination, as shown in figures 4 and 5. It won't be necessary any more to chose each time tiie correct stmnp: it will be sufficient to obtain from this stump realized in advance the stump witii the desired shape, with a cutting performed directly in the mouth, in tiie same way as natural teeth are filed. Now the plants may be personalized, making them ever more similar to tiie natural teeth. Should the dentist provide, already in tiie implantologic project, to insert tiie plant in such a way tiiat tiie fixture is angled with respect to the stump, it will be possible to thin the stump down in laboratory or directly in tiie hand, at the treatment chair witii the cutter mounted on the turbine. This will be possible due to tiie special case shown in figure 7, tiiat seals the plant so as to divide it into two parts by means of a separation membrane or structure Q, e.g. out of plastic, shown in figure 7, placed in die passage area between die fixture and die stump: said membrane has tiie function of sealing tiie area S of the fixture shown in figure 7 during the operations of thinning down, keeping it protected in its stiff case R shown in figure 7, having - e.g. - a cylindrical shape, keeping its sterility. The part of tiie case T covering tlie stmnp - shown in figure 7 - has the purpose of keeping its sterility and safety until it must be used in tiie plant. At this point, tiie two parts of tlie case will be separated, making force witii tlie hands rotating and pulling in tiie direction of tiie arrows of figure 7 bis, in correspondence with tlie area of tiie separation membrane that will show, near the part of the stmnp, a point of less resistance U shown in figures 7 and 7 bis. Thus tiie dentist may firmly hold the plant by tlie case on the part of the fixture, so as to be able to file without fear tlie plant and without that tiie deposit obtained during grinding contaminate the sterilized area of tiie case. Furtiiermore, the plant may remain stable inside the case due to tiie support of tabs V welded to the case from tlie inside and out of tiie same material, as shown in figure 7, e.g. hard transparent plastic or any other cheaper material corresponding to tiie same fimctional principles: special stiffness, elasticity, transparency that allow tiie plant to remain stable in the working phase in the laboratory. This will be possible if they will get into contact with tiie fixture in three or more distal points, towards the end of the fixture, and in three or more proximal points towards the beginning of the fixture from the part of tiie stump. Once the extra-oral thinning down is completed, the case housing tiie fixture may be opened making pressure onto the same along a longitudinal line dividing it as in two halves: this area will be prepared by the maker and will be one point of less resistance for disengaging the case from the plant after having hooked tlie same by means of the small key P shown in figure 8: on tlie holding stmcture D'". This system allows to adapt tiie stump even in those cases when the truncated-cone stiunp realized in advance proves to be too large and does not fit tiie area to prostiiesize, e.g. if it strikes tiie lateral surfaces or tiie teetii contiguous to a post-extractive or teetii less site.

Stumps shaped and filed in advance may be realized, or more or less long stumps and stumps with a more or less pronounced conicity, so as to afford even extreme cases. If a stump must be very angled with respect to the fixture, and if said stump will prove to be very short, due to lack of space between contiguous teetii and after the grinding phase tliat makes it parallel to tiie contiguous teetii for allowing the correct insertion of the prosthesis crown, it will be possible to obtain a primary retention all the same making its lateral surfaces less conic, i.e. more parallel according to die rules of the prosthesis preparation of the stump. Furtiieπnore, said stiunp may be lengthened by adding some compound at its top after having cut a small hole, witii a truncated-cone diamonded cutter mounted onto a turbine tliat will assure a primary retention: tiie whole - the zirconimn or compound stump and tiie compound added to the same - will be polished witii preparation cutters.

The second part may be realized also in such a way that it consists of two upside-down truncated cones, linked one to another so that tlie one witii the greater conicity is nearer to tiie fixture. This will allow tiie stiunp to be longer with respect to tiie inter-dental spaces: a stmnp consisting of one single truncated cone, tiie side whereof is too much angled with respect to tiie greater axis and must necessarily be very low for being inserted between two teeth, because otherwise it will be too large. This inconvenience may be overcome by making a stmnp with one or more portions of truncated cone, with a conicity decreasing while distancing from tiie fixture, and winch allow to make it longer and, at the same time, to obtain therefrom an angled stump, after cutting. If compound crowns are used, cemented with the same kind of compound, an over-gingival Chanfer preparation may be performed: such a prostiiesis will prove to be very realistic, showing a natmal aspect even with trans-illumination, as there is no metal in tiie stiunp. In this way also tiie problems linked to bi-metallism are solved. If there is a good primary retention and a bone of good quality, tiie stump jjnay be filed and an imprint may be taken for the provisional prosthesis out of resin or for tiie definitive prosthesis CP shown in figure 6, during the same visit of the surgical insertion. In tlie case of a compound prosthesis, tlie latter may be made directly after having taken the imprint, so that in about more or less two hours it may be definitely cemented, finished and polished directly in tiie moutii of the patient. By means of said teclmique it will be tiierefore be possible, in some cases, definitely to provide a toothless site with a prostiiesis in one single solution in about three to six hours. If you should not feel sure, the truncated cone part may be used as a recovering screw, possibly filing it lightly so as to better adapt to the site and rounding the edges so that it may be well tolerated by tlie patient, until tiie recovering of the soft and/or hard tissues does not allow to load tlie plant.

For housing the passing-through screw, it is not necessary that tiie fixture is hollow for fixing the stiunp or tiie cementable pin. The plant according to the present invention will not contain hollow spaces, which can become starting points for cracks, if not projected on purpose for making the structure lighter and, in any case if ever present, they should be preferably filled with light inert material, but it will be made out of titanium and zirconimn without continuity solution, as shown in figure 9. From the outside, the fixture will be made out of titanium thus simulating, if necessary, the structure of a plant already existing, but inside tl e hollow area Z will be obtained as shown in figure 9, with a suitable shape and lengtli as to allow tiie connection and tiie primary retention with the zirconimn or compound stiunp. Said groove must be of the correct dimension, so as to assure, at the same time, tiie correct resistance of the titanium walls of tiie fixture. The shape of the groove may be, e.g., of an upside-down truncated cone with a small conicity, with tlie lower base turned towards the oral cavity and the occlusion plane.

Furthermore, tiie part working as a stiunp may be made out of titanium only or have a reinforcing titanium core.

As said plants do no longer need more than one groove inside tlie fixture for allowing tiie housing of the passing-through screw, they may be realized also thinner than tiie conventional plants: tiie plant will be very resistant all tiie same, because it will be full and not empty, thus avoiding the risk of a fracture. Having a smaller diameter, it will be possible to perform tlie insertion into very thin toothless crests without tiie need of making use of an operation for a bone increase.

The fixture may have a cylindrical and/or conical shape and/or the shape most suitable to tiie best fimctional result.

The second variant of the mono-phasic mono-block plant of tlie hollow kind VC consists of a plant formed by a fixture A shown in figures 10, 12 and 14, and by a stump D also shown in figures 10, 12, 14 out of zirconium or compound or other aesthetic and/or transparent material, similar in its external part to the above described one but hollow inside, like a funnel. This allows to insert inside tiie same a transparent pin G, shown in figures 19, 20 and 21, e.g. out of zirconium fibre, cemented with a photo-polimerizable compoimd, due to the transparency of the materials H of zirconimn or compoimd and/or polimerizable, as shown in figures 19, 20 and 21. Thus a mono-block is foπned of the walls of tiie plant, tiie compound and the pin out of zirconium fibre. The compoimd and the pin will project over the edges of tiie funnel-shaped walls shown in figures 10, 20 and 21, tiiat will lie inside die mucosa and tiiat will just project from tiie part opposed to fixture X shown in figures 16, 17 and 18, so as to form die stmnp realized by tlie dentist himself in tlie moutii of tlie patient, and projecting like die stump of a natural filed tooth, so that it will be as suitable as ever possible to tliat situation of angulation between tiie crown and tiie axis of the plant and tiie inter-dental distance. In tins way, ti e plants may be personalized. The plant must be inserted in such a way that tlie funnel-shaped stump projects from tiie mucosa; the part of the fixture will be inserted into tiie bone up to the neck W, as shown in figures 16, 17 and 18, which is a passage area between titaniiun and baked clay in tiie outer part. The titanium fixture and tiie baked clay are mechanically linked as shown in G of figures 10, 12 and 14 in a screwing and, as a hollow area, made or shaped inside die titanium of tiie fixture. The substance out of which tiie stiunp is made will cover said groove D, for a thickness suitable to the resistance of tiie structure and to the diameter of tlie fixture, e.g. one millimetre. The walls of tiie groove may be parallel or slightly diverging as in H' of figures 10, 12 and 14, so as to assure a greater mechanic retention of the material foπning the funnel-shaped stiunp. Said structure may also have holes in tiie walls as well as in tlie bottom, or notches or oilier cuts for increasing tiie retention of the baked clay or of tlie compound or of any other material foπning tiie titanium stiunp or fixture. The length of tiie groove into which the material gets inserted with which tiie funnel of tiie stiunp is realized - e.g. zirconimn - coating the titanium of tiie fixture in its internal hollow part, must be suitable for ti e retention and solidity of said material, e.g. 4 millimetres, and must be detennined together witii tiie maker. The point of passage between tlie metal and said material forming the stmnp, in tiie direction of tiie bottom of tiie hollow, must be clean so tiiat one material rests onto tiie other like a step, as shown in F of figures 10, 12 and 14, so tiiat tiie baked clay does not break under tiie load. The internal surfaces of tiie hollow may be preferably made in such a way tliat there is not continuity solution and tiiat they appear to be continuous, as shown in E of figure 10: this will allow an easy insertion of tlie key out of titaniiun or steel or any other suitable material inside tiie hollow tliat will be used for screwing tiie plant into the bone.

In a variant, the internal surfaces of ti e hollow may also have a cylindrical shape for ending up in a parallelepiped witii a square base E' as shown in figure 12, or tiie shape of a pyramid witii a square base E" as shown in figure 14, with the greater base - in the case of tiie pyramid with square base - inscribed in tiie apical circular base of the hollow cylinder, which is an area for the insertion of the stem of tlie key or mandarin of figures 23 and 24, and preferably it will have titaniiun walls so that the forces applied there won't produce a fracture of tiie walls of tiie funnel-shaped stump, out of zirconimn of a more fragile compound. The key working as the male element must be inserted into the hollow tiiat works as tiie female element. The key may have tiie shape of a parallelepiped Y with a square base, as shown in figure 23, or, even better, tlie shape of a pyramid K witii a square base, as shown in figure 24, or a shape similar to the one of tiie hollow into which it will be inserted, but having dimensions slightly smaller than tiie latter, so as to allow an easy insertion and removing, still in consideration of a retention suitable for the screwing of a plant. The key consists of a stem and of a head. The stem has tiie function of getting inserted from inside in the hollow of tiie fixture for screwing the same into tiie bone, and it may have tlie shape of a parallelepiped Y witii a square base as in said figure 23, or it may end up in tiie truncated cone of a pyramid with a square base, wherein tlie minor square base provided at tiie end tiiereof will get into contact with the bottom of the hollow in the insertion manoeuvres.

The stem in tlie shape of a parallelepiped witii a square base K', shown in figure 24, ending up in a truncated cone of a pyramid, is to be prefeπed, because it facilitates tiie insertion and removing manoeuvres. In case of greater force applied during the screwing operation, as it may happen in the presence of a compact, hard bone, tiie risk of fusion between the surfaces of tiie stem and may be avoided, as a pyramid-shaped body inserted into a similar hollow is much easier to be removed than a body with tiie shape of a parallelepiped inserted into a similar hollow, d e parallel surfaces whereof might cause it to get stuck into it. The shape of a pyramid trancated-cone also suits better to d e morphology of tiie fixture: in tiie case of a conical plant, it allows to have a suitable titaniiun thickness around tiie tπincated-cone pyramid hollow, in tiie direction of tiie smaller surface: in such area, a hollow in tiie shape of a parallelepiped would make tiie walls too thin, especially in tlie fixtures witii a small diameter.

According to die present invention, at die opposite side there is the head of tiie key T shown in figure 24, greater and of such a shape - e.g. cubic or cylindrical - as to allow die insertion of a ratchet tliat favours die screwing manoeuvres - manual or with a suitable support for the counter-edge - of tiie plant. The dimensions of tlie key may be different: the stem may be 2.5 cm, 2 cm, 1.5 cm long or may have other length, so as to favour tlie insertion of the plant in areas difficult to reach; the thickness of tlie stem may vary: suggested is a thickness of 1 mm or 1.5 mm as a side of tlie base square of tiie parallelepiped fonning it, or 2 mm for die side of die major base and 1 mm for d e side of the minor base of the truncated cone pyramid; tiie head may have a radius of 3 mm or other dimensions which may better suit it to the shape of ti e ratchet that is to be used, and more precisely to the one of tiie ratchet's hole where tiie head of die key is housed.

The variant of die hollow plant is useftil in the cases of tl e non alignment between the axis of the fixture and the axis of the crown: the funnel-shaped stump allows the dentist to polimerize witii a lamp of tiie kind of tiie lamp W' shown in figure 25, or with an self- polimerizing compound, the compound inside it, so tiiat a mono- block is fonned between the outer part of the stiunp D of figure 25 - out of zirconium or compound or otiier suitable material - the compoimd H, tlie pin G out of zirconimn fibre, and die metal of die fixture A. If it will be decided to make tiie stmnp immediately, in fact, the outer part of the funnel D of fixture A will get into contact with the tissues lesioned by tiie operation, tiierefore bleeding and exuding, and tiierefore said part will be protecting die polimerization occiuring inside from tiie fluids, however present. Once the compoimd has been polimerized, and once tiie dentist has suitably adapted it to tiie moutii of tiie patient so as to fonn a stump of suitable dimensions, it will be easy to file it to make it ready for taking a print for realizing a crown, preferably out of compound or integral baked clay. The result will be a work of high aesthetic value. If there is primary stability of the fixture, the whole operation may be perforated in a few hours and die patient will be able to make use ot the plant in little time. Time may be considerably reduced if die dentist may use a mechanized computer system, like tlie Cerec III Cad Cam, for tiie realization of tiie crown. If the dentist is a skilled one, he may realize the crown CP shown in figure 26 himself, out of compound, or even realize again die crown out of compoimd directly in the mouth of the patient: it will make easier the choice of tlie colour and die coπect disposition of die layers of the masses. If there is no primary stability, it will be advisable to differ said process for the time necessary for tiie integration of the bone, using the funnel as a recovering screw or as a trans-mucous plant: tiie edges of die funnel will be filed witii a cutter moimted onto a turbine TB as shown in figure 18, rounding tiiem off for making them fitting to the gingiva and not cutting or troublesome, and then tiie concave part of tlie funnel will be sealed with provisory filling material PR shown in figures 16 and 17, and tiien proceed, in tlie right moment, to the realization of tlie stump, projecting from tiie gingiva, and of the coπesponding crown. This is die primary indication for tlie use of tiie hollow variant because if there is no primary retention, the plant may be inserted all tiie same and no noxious intra-oral forces - like chewing or bmxing - may act on die same, destabilizing it: on tiie contrary, tiie plant will be protected inside tlie bone and tiie gingiva, surfacing from tlie same, so as to postpone to the moment of its bone integration tiie reconstraction phase of the stiunp and of tlie crown and tiierefore of tiie load.

For better fitting to tiie anatomy of tiie natural teetii, tiie funnel- shaped stiunp may have different shapes: die section peφendicular to its long axis may be round for canines, premolar, tiie lower incisors and die molars; elliptical, as shown in figure 27, for the upper incisors, or even of the most suitable shape for simulating the roots of ti e molar teetii as shown in figure 28. This may be done because tiie part tiiat will be inserted into the bone, i.e. tiie fixture, is always maintained in a cylindrical or conic shape and therefore always keeps its screwing feature, while tlie trans-mucous funnel- shaped part may assume different shapes, as similar as possible to die anatomy of natural teetii, because tiie soft tissues oppose no resistance and impediment to tlie circular screwing motion necessary for tiie insertion tiiereof. The same operation may be perfonned in the VP, witii tlie stiunp.

A further element of tiie plant according to die present invention consists of a fibre pin G, e.g. out of zirconimn, bent or angled as shown in figure 22, for keeping die core H of tiie compoimd shown in figure 22 for foπning tiie stump projecting into the oral cavity: this is necessary when there is a strong angulation between tiie axis of the fixture and the one of the crown to be reconstmcted. The pin must be out of zirconimn or glass fibre, out of compound or otiier suitable material, of cylindrical shape but bent in the centre: many different pins may be made with different angulation: 10°, 15°, 20°, 25° and 30° so as to meet tlie most different needs. Even if it is conical, it is still bent at about half its length. The conical pin better fits die anatomy of natural teetii, as it requires less dentine sacrifice in the apical portion of tlie roots. It may also have tlie shape of a parallelepiped with a square base, bent at tiie half of its lengtli, and end up in tiie shape of a hτmcated-cone pyramid with a square base, so as to get stuck in tlie hollow of the mono-block plant VC being its homologue print, already offering a primary retention. Each shape will have a standard length, e.g. 1.9 centimetres, and it will be easy to cut it at its ends with a cutter moimted onto a turbine, for fitting it to the system. Said pin may be used also in tiie roots of natural teetii for reconstructing the stump tiiereof.

Claims

1. A dental plant characterized in a stiunp prepared in advance in tlie full variant (VP), and partially realized in tiie hollow variant (VC), so as to make it completely personalized and suitable for being applied in one single surgical visit as, being out of one single structure, no further surgical re-entry is expected; said stiunp realized in advance being imited to the body of the plant tiiat will be inserted into the bone, called 'fixture', since realization and that may be filed immediately after tlie surgical operation already in tiie mouth of the patient: immediately, in the frill variant and after the reconstruction of tiie intra-oral stiunp in tiie hollow variant, thus being suitable for the coπect insertion of a prosthesis: in fact, it is due to tiie shape of a truncated cone - called 'abutment' - of die stiunp inserted into said fixture - in die full variant - tiiat it will be possible to shape, directly in tiie moutii and witii tiie help of a preparation cutter moimted onto a turbine, a stiunp having die coπect inclination for the coπect prosthesis rehabilitation; while tlie funnel-shaped shell of die trans-mucous part of tiie stiunp, in the hollow variant, allows the dentist to personalize die stump, realizing it with a pin out of zirconimn fibre and witii a polimerized compoimd safe from fluids, due to just said funnel shape tiiat insulated them from the mucous membrane, so as to obtain a stiunp with tiie desired inclination in tiie desired moment.

2. A dental plant according to claim 1, characterized in that - in the hollow variant - it remains partially submerged for tlie time requested, just surfacing foπn tiie mucosa and thus behaving like a trans-mucous plant, so tiiat, once it is filed, it allows to obtain a stmnp having an axis coinciding or angled witii respect to tiie one of the plant, according to the needs of the case, so as to allow to realize and cement during the same visit a provisional tooth or a definitive crown, like a crown out of compoimd or baked clay or otiier suitable material.

3. A dental plant according to tlie preceding claims, characterized in a structure consisting of one single piece - mono-litiie or mono-block, and no longer of two fixtures or abutments or a plurality of separate elements that may be screwed or cemented one to die otiier.

4. A dental plant according to claim 1, characterized in a case programmed so as to be divided into two portions: one that must remain sterile until it is opened, which coincides witii tiie moment before tiie insertion of the plant, and tiiat contains tlie fixture; and one tiiat may be opened before, so as to allow to work the stiunp container therein in laboratory or directly during, the visit.

5. A dental plant according to claim 1, characterized in a bent pin that may be used in the hollow variant tliat allows tlie reconstruction of the stiunp with tiie pin at tiie centre tiiereof also in those cases in which tiie long axis of tiie stiunp is bent with respect to tl e one of the fixture of the plant.

6. A dental plant according to claim 1, characterized in that once a stiunp suitable for die coπect insertion of the prostiiesis is obtained, die truncated-cone shape of the abutment in the (VP) allows to model a stump (D) with tiie coπect inclination for tiie coπect prosthesis rehabilitation, directly in the mouth of the patient witii a preparation cutter moimted onto a turbine (M).

7. A dental plant according to claim 1, characterized in a shell having the shape of a funnel (D), that allows to personalize the stiunp making it with a pin (G) out of zirconimn fibre and with compound, so as to obtain a stump with tiie desired inclination in tiie desired moment, because the (VC) plant may remain partially submerged for die time desired just surfacing from die mucosa, thus behaving like a trans-mucous plant.

8. A dental plant according to claim 1, characterized - in tiie (VP) - in a fixture with cylindrical or conical shape so tiiat it may be inserted into the hole provided by the dentist in d e bone with suitable cutters, and the last thereof shows the shape thereof, even if lightly thinner, for allowing a primary retention of tiie fixture tiiat may be obtained also due to turns (B), and tiiat allows to screw the plant, until the area (I) for tiie passage between titanium and zirconium - i.e. on the boundary between neck (C) and tiie plant and tiie stump (D) - reaches the edge of tiie bone crest (F).

9. A dental plant according to claim 1, characterized in said turns industrially treated so as to show a rough surface for nnproving tiie bone integration, and said turns end up in the smooth area of tlie neck, of variable length, preferably of 2 millimetres and of cylindrical shape, while tliat part acting as a stiunp consists in turn of two parts: tiie first part (D'), called trans-mucous, is cylindrical or of an upside-down truncated-cone, or has tiie shape of a pressed funnel in tiie variant witii elliptical section; and a second part (D')₅ of the oral kind, in tiie shape of a trancated-cone turned upside-down.

10. A dental plant according to claim 1, characterized in that once the extra-oral tiiinning down has been completed, die case covering tiie fixture is opened perfonning a pressure onto die same along a longitudinal line dividing it and foπning a point of less resistance for releasing the case from tiie plant after it has been hooked, by means of a small key (P), onto ti e hold (D'")₅ so as to fit tiie stump also in those cases in winch tiie stiunp realized in advance in the shape of a trancated-cone, results to be too large and won't fit the area to be provided with a prostiiesis, when it pushes on tiie lateral surfaces of tiie teetii contiguous to a post-extractive or toothless site.

11. A dental plant according to claim 1, characterized in a fixture (A) and in a stump (D), out of zirconium or compoimd or otiier aesthetic and/or transparent material, hollow inside like a funnel, thus allowing the insertion inside tiie same of a transparent pin (G), out of zirconium fibre, cemented witii a photo- polimerizable or a self-polimerizing compoimd, and due to tiie transparency of tlie components, foπning a mono-block between the walls of tiie plant - compoimd and pin out of zirconium fibre - so tiiat said compound and said pin project beyond tiie edges of tlie funnel-shaped walls which just surface from die mucosa, so as to foπn a stiunp projecting like tiie stiunp of a natural filed tooth, so as to be the most suitable possible to tiiat particular angulation situation between the crown and tlie axis of tiie plant and to die existing inter-dental space.

12. A dental plant according to claim 1, characterized in inner surfaces of the hollow having the shape of a cylinder and ending up in a parallelepiped witii a square base (E'), or in a pyramid witii a square base (E"), with the greater base - in tiie case of the pyramid with the square base - inscribed in die circular apical base of the hollow cylinder, which is an area for ti e insertion of tiie stem of a key or mandarin in tlie shape of a parallelepiped with a square base (Y) or of a trancated-cone pyramid witii a square base (K).

13. A dental plant according to claim 1, characterized in that said key is fonned by a stem having tiie function of insertion inside tiie hollow of the fixture for screwing it into tiie bone, and by a head (T) - cubic or cylindrical - for allowing tlie insertion of a ratchet for the screwing manoeuvres of tiie plant, manual or with a suitable support for counter-angle.

14. A dental plant according to claim 1, characterized in a pin (G) out of zirconimn fibre, bent or angled, for holding die core (H) of tiie compound for foπning tiie stump projecting in tiie oral cavity.