Classifications

• • A—HUMAN NECESSITIES
  • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
  • A61C—DENTISTRY; APPARATUS OR METHODS FOR ORAL OR DENTAL HYGIENE
  • A61C13/00—Dental prostheses; Making same
  • A61C13/08—Artificial teeth; Making same
  • A61C13/09—Composite teeth, e.g. front and back section; Multilayer teeth
• • A—HUMAN NECESSITIES
  • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
  • A61C—DENTISTRY; APPARATUS OR METHODS FOR ORAL OR DENTAL HYGIENE
  • A61C13/00—Dental prostheses; Making same
  • A61C13/08—Artificial teeth; Making same
  • A61C13/083—Porcelain or ceramic teeth
• • A—HUMAN NECESSITIES
  • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
  • A61C—DENTISTRY; APPARATUS OR METHODS FOR ORAL OR DENTAL HYGIENE
  • A61C13/00—Dental prostheses; Making same
  • A61C13/20—Methods or devices for soldering, casting, moulding or melting

Definitions

• the present invention relates to ceramic dental prostheses intended to be placed in the mouth of a patient.
• Such dental prostheses consisting of a metal screed coated with ceramic cemented on the patient's dentine stump, while respecting the cervical size limit made by the dental surgeon.
• this kind of prosthesis has an imperfect aesthetic because of the opaque presence of the metal, and often a gingival retraction due to the non-biocompatibility of the metal in the body.
• the patient can endure severe thermal irritation of the gums.
• the dental surgeon When producing a ceramic-ceramic prosthesis, the dental surgeon prepares the tooth for which a prosthesis is to be made, by pruning it appropriately to receive an inlay-onlay, a crown or a facet. Once the size is achieved, the dental surgeon makes an impression of the dentition of the patient, which impression will be transmitted to the dental technician for the realization of the dental prosthesis.
• the dental technician then realizes a dental ceramic prosthesis intended to come on or in the size made by the dental surgeon.
• the dental technician is all the more constrained that the slightest error, in one of the many stages of the process can lead to everything. start again from the beginning. This results in a great loss of time by the dental technician, coupled with a great stress that does not contribute to the success of the dental prosthesis.
• a first problem proposed by the invention is to considerably simplify the process for producing a satisfactory natural-looking ceramic dental prosthesis, without requiring the dentist to make the tooth size too restrictive, and without requiring heavy investments. on the part of the dental technician in a very expensive specific material.
• the invention aims to significantly reduce the time of completion of a dental prosthesis by the dental technician.
• the invention aims to improve the dimensional accuracy of prostheses made, particularly in the areas of contact points and in the peripheral prosthesis area corresponding to the limit of preparation of the tooth to be treated.
• the invention aims to make it possible, in the event of breakage of a first prosthesis in a patient's mouth, the even faster and more exact realization of a second dental prosthesis for the patient. ⁇ .
• the invention provides a method of manufacturing a ceramic dental prosthesis, made from a negative jaw impression of a patient having at least one working cavity, of inner surface conforming to the intrados of the prosthesis to be produced and left by at least one tooth prepared by the dental surgeon to be prosthetic, comprising the following successive steps: a) producing a unitary wax model by casting a wax in said cavity working the jaw impression in negative, and forming a waxing root portion in wax above the working cavity; b) fix a burnout rod on the top of the root portion of the unit wax model; c) coating the unit wax model and the burnout rod in a coating device, for example in a cylinder usually used by dental technicians; d) producing a unit metal model identical to the unit wax model by casting a metal alloy in place of the unit wax model and the calcinable rod in the coating, the unit metal model thus comprising a root rod, a part radicular protruding and an extrados surface corresponding in positive to the intrados of the
• the unitary metal model thus produced comprises an extrados surface corresponding in positive to the intrados of the tooth to be produced. This means that the upper part of the unitary metal model is the exact replica of the tooth prepared by the dentist in the patient's mouth.
• the unitary metal model is realized by a classic process of lost wax, which allows to realize parts with very precise dimensions. ⁇
• This method according to the invention also has the advantage of being much faster and more reliable than the known processes mentioned above. It was thus possible to achieve ceramic prostheses according to the invention in less than two hours, generally in an hour and a quarter or an hour and a half, without waste.
• the ceramic may advantageously be mounted conventionally by applying a ceramic paste to the brush on the unit metal model, after the unit metal model has been covered with the release product.
• the dental technician can easily give the desired shape to the dental prosthesis.
• this allows the dental technician to choose and apply different ceramic tints, in areas of surface that can be distinct, to get as close as possible to what will appear natural in the mouth of the patient.
• the dental technician can adapt the color of each layer of ceramic paste constituting the prosthesis, which gives him the greatest opportunity to reproduce the aesthetic rendering of a natural tooth.
• the demolding product applied to the extrados surface of the unitary metal model makes it possible to detach the ceramic produced by the dental technician from the unitary metal model after passing through the oven for firing the ceramic on the unit metal model. It is important that the separation of the ceramic and the unit metal model is as gentle as possible so as not to damage the fired ceramic.
• the metal alloy may be a dental alloy with a melting temperature higher than the firing temperature of the ceramic, and with a coefficient of thermal expansion close to that of the ceramic.
• the unit metal model is not affected by its passage through the oven when firing the ceramic thereon.
• the fact that the metal alloy has a coefficient of thermal expansion close to that of the ceramic makes it possible to make a ceramic dental prosthesis free of breaks or cracks and whose dimensions will correspond exactly to those of the tooth prepared by the dentist in the patient's mouth. Indeed, if the thermal expansion coefficients of the metal alloy and the ceramic were very different, the ceramic could break or crack, or the unitary metal model and the ceramic made by the dental technician would not fit exactly with a good fit effortlessly, which would mean that the ceramic would not fit exactly on the tooth prepared by the dentist in the patient's mouth. ;
• the metal alloy may comprise nickel and chromium.
• the unit metal model after step d can be carefully cleaned, for example by sandblasting, to remove any coating.
• a good cleaning on the outer surface of the unit metal model - is useful so that it corresponds exactly to the tooth prepared by the dentist in the patient's mouth.
• the presence of coating left on the outer surface of the unitary metal model would not achieve a ceramic dental prosthesis to fit exactly on the tooth prepared by the dentist in the patient's mouth.
• the demolding product to prevent the adhesion of the ceramic to the metal during a firing of the ceramic on the unit metal model, may be a powder-based mixture quartz.
• the quartz powder may have a particle size of about 40 to 50 microns.
• the demolding product, to prevent the adhesion of the ceramic on the metal during a firing of the ceramic on the unit metal model may be the product ToothPCS marketed by the French company JBC LOGiDIS.
• the demolding product applied to the extrados surface of the unitary metal model makes it possible, once the ceramic is baked on the unit metal model, to separate the ceramic from the unitary metal model without any effort or stress likely to damage the fired ceramic. .
• a dehydration step may be added, during which the unit metal model coated with the demolding product is passed through a ceramic oven, for example at approximately 400 ° C. about a minute.
• This dehydration step makes it possible to impart to the demolding product applied to the surface, extrados of the unitary metal model, a powdery character.
• the very slightly adhesive powdery product on the extrados surface of the unitary metal model will prevent it. ceramic to remain adhered to the unit metal model after firing the ceramic on the unit metal model.
• the application of the demolding product to the unit metal model can be done by slightly projecting beyond the cervical limit of the extrados surface of the unitary metal model.
• the dental technician produces a mass of ceramic covering the entire surface of the extrados of the unit metal model and slightly exceeding the cervical limit, thus obtaining the correct size after shrinkage of the ceramic due to cooking on the unit metal model.
• a working model that may comprise the following steps: d1) engaging the unitary metal model in the working cavity of the jaw impression; d2) making a working model by casting plaster into and on the jaw footprint in which the unitary metal model is held; d3) Unmold the working model and remove the unit metal model.
• a plaster work model is thus produced in which the unit metal model is inserted according to its root-root portion.
• the unitary metal model is then easily extractable from the working model, leaving then the working model with a cavity in which can be reinserted very easily and very precisely the unitary metal model.
• the working model thus produced and equipped with the unitary metal model is the faithful replica of the patient's dentition.
• the working model is thus usable by the dental technician to perform an aesthetic ceramic assembly in harmony with the other teeth of the patient. In addition, this allows the dental technician to adjust the contact points of the prosthesis with the neighboring teeth when mounting the ceramic brush.
• the removal and / or insertion of the unit metal model into the working model is facilitated by the low oxidation thereof (due to the presence of nickel and chromium in the metal alloy used) and the high accuracy with which it was made by lost wax casting. Indeed, an oxidation of the unit metal model would lead to a variation of its external dimensions and / or its surface state, making its insertion and / or removal of the working model complicated.
• the working model and the unitary metal model will be conserved later in the laboratory of the dental technician; which can easily ', thanks to these elements, manufacture in a very short time a new dental prosthesis for the patient if he ever accidentally broke the first dental prosthesis.
• the dental technician thus benefits from the work that was previously done during the realization of the first dental prosthesis for a patient, by gaining considerable time when making a second dental prosthesis identical to the first.
• the final presentation model makes it possible to carry out final checks of the adequacy of the ceramic dental prosthesis made with the dentition of the patient prepared by the dentist. We can for example check the aesthetics, but also the contact points of the prosthesis with the neighboring teeth.
• step g) of firing the ceramic can be performed in two times, with an intermediate step of grinding a withdrawal of the periphery of the ceramic in contact with the unit metal model.
• the dental prosthesis is fired on the unit metal model in a conventional ceramic furnace, which has the advantage of not requiring the dental technician to invest in a specific expensive furnace.
• the intermediate step of rectifying the shrinkage of the periphery of the ceramic in contact with the unit metal model can be effected by the addition of collar masses at the level of the shrinkage.
• the ceramic is thus along its periphery perfectly contiguous with the cervical limit of the extrados surface of the unit metal model, which subsequently ensures a perfect interlocking of the ceramic dental prosthesis on the tooth prepared by the dental surgeon in the mouth of the patient.
• the shape finish of the ceramic of step h) can be performed by grinding in combination with any control on the presentation model.
• the realization of a dental prosthesis according to the invention thus requires no specific and very expensive equipment that is not already in possession of a conventional dental technician.
• the raw materials used can also be of a conventional type and in no way differ from the materials usually used by a dental technician, apart from the mold release product.
• the method of manufacturing a ceramic dental prosthesis described here can be used for producing a dental prosthesis of the inlay-onlay, crown, facet or bridge type.
• a dental ceramic prosthesis obtained by a method according to the invention can be recognized in particular by the fact that, in the ceramic mass, there are surface areas having successive thin layers of stackings, generally more than three layers, each layer resulting from the application of brush material, and distinct areas of surface may have different thicknesses and colorations of layers.
• the successive layers can be distinguished by different hues, but generally without a clear interface as a result of the firing of the ceramic.
• FIG. 1 is a diagrammatic cross-sectional view of a negative jaw impression of a patient in which a unit wax model is made;
• Figure 2 is a schematic sectional view of the investment of the unit wax model of Figure 1;
• FIG. 3 is a perspective view of the unitary metal model
• FIG. 4 is a schematic sectional view illustrating the realization of a working model
• FIG. 5 is a perspective view of a working model according to the invention.
• Fig. 6 is a perspective view of a final presentation template
• FIG. 7 is a sectional view of a unit metal model on which is engaged a ceramic dental prosthesis in progress;
• FIG. 8 is a diagrammatic sectional view of the finish of a ceramic dental prosthesis on a unitary metal model.
• FIG. 9 is a schematic sectional view of an inlay-onlay ceramic dental prosthesis engaged on a unitary metal model.
• FIG. 1 represents the realization of a unitary wax model 1 from a negative jaw impression 3 which has been previously executed by a dental surgeon after preparation of the tooth to receive a prosthesis.
• the impression 3 comprises a working cavity 2 reproducing in negative form of the prepared tooth.
• a dental wax is poured into the working cavity 2 of the impression 3 in negative jaw.
• a radicular portion 4 extending above the working cavity 2 is waxed.
• the dental wax used for producing the unitary wax model 1 must not be a wax that is too hard to strongly shrink, so that it comes to marry at best the shape of the working cavity 2.
• the root portion 4 rises above the working cavity 2 with a substantially conical shape.
• a burnout rod 5 is attached to the top of the root portion 4 of the unit wax model 1. The fixation of the burnt out rod 5 is carried out by simply depressing it by about 1 to 2 mm in the root portion 4.
• Figure 2 is shown the investment of the unit wax model 1 in a conventional coating device 6.
• the coating device
• the coating of the unitary wax model 1 and the calcinable rod 5 is then carried out by casting a coating 11 in the cylinder 8 by the upper face 8b open of the coating device 6.
• the coating 11 used may be a conventional coating used by dental technicians for the investment.
• the coating device 6 is placed in a temperature oven selected according to the coating manufacturer's indications. , to calcine the calcinable rod 5 and evacuate the wax. The coating device 6 is then turned over and placed on the upper face 8b of the cylinder 8. The base 7 is then directed upwards and will serve as a casting cone for the metal alloy.
• the molten metal alloy then takes the place of the calcinable rod 5 and the wax in the coating 11 in the solid state, taking the exact form of the wax model 1. This is a lost wax process well known to dental technicians.
• Figure 3 is shown the unit metal model 16 obtained by the method. It comprises an extrados surface 12, a root surface 13 and a root rod 14.
• the extrados surface 12 of the unit metal model 16 corresponds in positive to the intrados of the tooth prosthesis to be produced.
• FIG. 3 also illustrates the application by brush, on the extrados surface 12 of the unitary metal model 16, of a demolding product 17 making it possible to prevent the ceramic from adhering to the unit metal model 16 after baking of the ceramic on the unit metal model 16.
• the application of the demolding product 17 on the unit metal model 16 is overflowing slightly from the extrados surface 12 of the unitary metal model 16.
• the root surface 13 is very slightly coated with demolding product 17 on an upper periphery 18 of low height h. This will allow the dental technician to then mount ceramic with a brush on the unit metal model 16 coated with demolding product 17, projecting very slightly from the extrados surface 12 on the root surface 13 so that the extrados surface 12 is covered ceramics certainly.
• the demolding product 17 may be a mixture based on quartz powder.
• the quartz powder may have a particle size of about 40 to 50 microns.
• the demolding product 17 can also be advantageously a mixture sold under the name ToothPCS by the French company JBC LOGIDIS.
• FIG. 4 shows the production of a working model 21.
• the unitary metal model 16 is inserted along its extrados surface 12 in the working cavity 2 of the jaw cavity 3.
• a first plaster layer 19 of class IV is then poured and then a second plaster layer 20 of class III, as is commonly practiced by dental technicians.
• the metal alloy used for the realization of the unit metal model 16 may comprise nickel and chromium. The presence of nickel avoids excessive oxidation of the unit metal model 16 which would hinder its re-insertion into the working model 21.
• wax 22 is applied around the base of the root surface 13, slightly protruding over the surface. jaw impression 3 at the periphery of the working cavity 2.
• This wax 22 makes it possible to maintain the unitary metal model 16 in the jaw impression 3 during casting of the plaster, and to prevent the plaster 19 of class IV from penetrating under the unitary metal model into the working cavity 2.
• a piece of wax 23 is applied to the free end 24 of the root rod 14.
• the dental technician will remove the wax 23 to clear the end 24 of the root rod 14. It can thus help to clear the unit metal model 16 of the working model 21 by applying a slight pressure on the end 24 of the root rod 14 and a slight traction on the extrados surface 12 of the unit metal model 16.
• FIG. 5 is illustrated a working model 21 once made, in which the unit metal model 16 can be freely inserted or removed.
• the working model 21 can then be used by the dental technician to hold the unit metal model 16 as it is coated with release agent 17, and then as it mounts the ceramic on the unit metal model 16 to give it the desired external shape for the prosthesis to be made.
• the dental technician can then remove from the working model 21 the unit metal model 16 on which he mounted the ceramic, and he can complete to mount the ceramic overflowing very slightly on the root surface 13 of the unit metal model 16 as previously said.
• Figure 6 is shown a final presentation model 35, made in a conventional manner using the jaw footprint 3.
• the final presentation model 35 is the exact plaster replica of the patient's dentition after preparation by the dentist. It comprises in particular a replica of cut tooth 36, and a replica of adjacent teeth 37 and 38.
• the final presentation model 35 is used to control the contact points of the ceramic prosthesis which cap the replica of cut tooth 36. It is important to be able to verify the contact points of the ceramic prosthesis disposed on the cut tooth replica 36 with the replicas of adjacent teeth 37 and 38.
• the gingiva of the patient will not be injured by any beyond the ceramic prosthesis, it controls the contact between the ceramic prosthesis and the gum replica 39 of the final presentation model 35. This ensures a perfect match of the ceramic prosthesis on the replica of cut tooth 36.
• the final presentation model 35 will serve as a support for the ceramic dental prosthesis for sending it to the dentist.
• FIG. 7 illustrates the rectification of a withdrawal 25 of the periphery 26 of the ceramic prosthesis 27 in contact with the unit metal model 16. This is an intermediate step between two successive firings of the ceramic prosthesis 27.
• This rectification of the shrinkage 25 is effected by adding collar mass 28 to the shrinkage 25 by means of a brush 29.
• Figure 8 is illustrated the shape finish of the ceramic prosthesis 27, made by grinding with a rubber grinder 30.
• the masses 31 and 32 of the ceramic prosthesis 27 are removed in order to be able, on the one hand, to easily separate the ceramic prosthesis 27 from the unitary metal model 16, on the other hand, to give the ceramic prosthesis 27 the shape necessary to a perfect fit in the patient's mouth with the tooth prepared by the dentist.,,,
• FIG. 9 illustrates the production of a ceramic prosthesis 27 for a dental prosthesis in place on its unitary metal model 16.
• the ceramic prosthesis 27 represented here is of a type different from that shown in the figures until then : this is a dental prosthesis type inlay-onlay.
• step f) where the dental technician raises the ceramic 27 with a brush on the unitary metal model 16, the latter adds an excrescence 33 to the top of the ceramic 27.
• This excrescence 33 allows the dental technician grasping the ceramic 27 for separating the ceramic 27 away from the unitary metal model 16.
• This protrusion 33 will then be ground along the dotted line 34 so as to give the ceramic prosthesis 27 the final shape that it must have in the patient's mouth.
• the method according to the invention is thus usable for all the different types of existing dental prostheses.
• the resulting prosthesis consists entirely of a mass of ceramic in which can be distinguished where appropriate thin layers of different hues or appearance.
• the dental technician may be required, during the assembly of the ceramic, to stack with the brush successive layers of different ceramics having different characteristics of hue, transparency.
• the thickness of the layers corresponds to the usual thickness of a layer of ceramic deposited with the brush.

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• Health & Medical Sciences (AREA)
• Oral & Maxillofacial Surgery (AREA)
• Dentistry (AREA)
• Epidemiology (AREA)
• Life Sciences & Earth Sciences (AREA)
• Animal Behavior & Ethology (AREA)
• General Health & Medical Sciences (AREA)
• Public Health (AREA)
• Veterinary Medicine (AREA)
• Chemical & Material Sciences (AREA)
• Engineering & Computer Science (AREA)
• Ceramic Engineering (AREA)
• Dental Prosthetics (AREA)

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• 2005
  • 2005-03-31 FR FR0503387A patent/FR2883720B1/fr not_active Expired - Fee Related
• 2006
  • 2006-03-31 CA CA002603413A patent/CA2603413A1/fr not_active Abandoned
  • 2006-03-31 US US11/909,864 patent/US7754115B2/en not_active Expired - Fee Related
  • 2006-03-31 WO PCT/FR2006/000706 patent/WO2006103357A1/fr not_active Application Discontinuation
  • 2006-03-31 EP EP06726155A patent/EP1874220A1/de not_active Withdrawn

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