The patent's assignee for patent number 8628326 is
News editors obtained the following quote from the background information supplied by the inventors: "Nowadays, the mounting and dismounting of any dental prosthesis of the aforementioned type is performed exclusively by an axial insertion, that is, through a vertical insertion.
"There are numerous situations in which implants of the dental arch are in unfavourable conditions, such as due to excess inclination, for being out of the natural space of the tooth or for not being subgingival (deep under the gum), among others. All these situations are not only highly problematic for the patient, who suffer all the discomfort without getting the desired aesthetic results, but they are also notably detrimental to dentists and dental technicians. In this sense, screwed and cemented prostheses are a clear example of these inconveniences.
"As regards screwed prostheses, they have the advantage that they can be removed at any time by simply loosening the screws that keep them fixed to the implants, to which they are mounted and dismounted by axial insertions. However, the elaboration of this type of prostheses is quite complex, presents multiple adjustment difficulties and even aesthetic problems. The chimneys used to do the holes through dental pieces to allow screw access to the implants are greatly responsible for this. For example, any small variation in the final position of the chimney in the prosthesis with respect to its original position in the mouth can cause serious adjustment problems. It is also frequent that the holes drilled by chimneys are in highly visible areas of the dental piece, due to a faulty placement of implants, which results in undesired aesthetic results. Another very important aspect is the possibility of chimneys being located in highly occluded areas (cuspids o pits), which produces failures in the prosthesis function.
"As regards cemented prostheses, these are also mounted and dismounted by axial insertions, yet they do not have as many elaboration and mounting inconveniences as screwed prostheses since they do not use chimneys. In this case, the joining with the implants is performed through stumps, which are actually mechanical connections, between a first piece screwed to the implant and a second piece located in the prosthesis. In spite of the apparent simplicity of this type of prosthesis, its elaboration and mounting still produces some of the aforementioned problems. Particularly, wrong implant placement can cause important inconveniences such as, for example difficulties placing the first pieces which can seriously hinder the fitting with second pieces placed in the prostheses. It may also be the case that there exist small variations in the final position of the second pieces on the prosthesis in relation with their original position in the mouth, which causes serious adjustment problems.
"The present invention solves the aforementioned problems in a highly satisfactory manner thanks to an easily mounted and dismounted dental prosthesis of vestibular insertion, much less dependent on the right or wrong implant placement, with a highly aesthetic finish and which does not exclude any of the advantages and features of the previous prostheses."
As a supplement to the background information on this patent, VerticalNews correspondents also obtained the inventor's summary information for this patent: "In order to solve the aforementioned problems, the dental prosthesis of the present invention is of the type that is fixed on a plurality of implants arranged in a completely or partially edentulous dental arch. Such prosthesis comprises: a primary structure configured to be screwed over the implants of the dental arch and which has primary insertion means; and a secondary structure configured to support a reproduction of the teeth and of the gum of the dental arch and which has secondary insertion means.
"Also, the primary insertion means and the secondary insertion means are configured to work collaboratively and allow the coupling of the secondary structure on the primary structure by a vestibular insertion. Vestibular refers to the outer side of teeth, that is to say the one seen when someone smiles. Vestibular insertion is equivalent to a horizontal insertion.
"The primary structure comprises: a frontal wall configured to use a front space, totally or partially, corresponding to the location of incisors and canines of the dental arch; and at least one lateral wall connected with the frontal wall which is configured to occupy a lateral space, partially or totally, corresponding to the location of molars and premolars of one of the dental arch sides.
"Preferably, the frontal wall has a conic shape which is closed towards the dental arch and which is very helpful for orienting and facilitating its fixing to the implants, while the lateral wall is placed in a perpendicular position with respect to an occlusal plane. The term 'occlusal' refers to the masticatory surface of molars and premolars. The frontal wall shape and the lateral wall shape follow the lingual or palatine morphology whether it is the lower or upper arch respectively, so as to provide a better adjustment. The frontal and lateral walls comprise, each of them, at least one fixing pillar oriented so as to facilitate the fixing of the implants. Each of these fixing pillars comprises: one end coinciding with one of the implants of the dental arch and which is configured to fit with such implant; and a through hole which is configured to receive a fixation screw which is connected with the implant.
"Also, the secondary structure comprises: a frontal covering wall configured to attach with the outer face of frontal wall of primary structure and cover it; and at least one lateral covering wall attached to the frontal covering wall, configured to fit with the outer face of the lateral wall of primary structure and cover it.
"The formation of said walls is adjusted to avoid cracks and holes between the primary and secondary structures, and thus, leftover food accumulation zones or zones where air can be accumulated are also avoided.
"Preferably, the frontal covering wall and the lateral covering wall comprise a plurality of protuberances configured to withstand the reproduction of dental pieces and gum of the dental arch and to facilitate its formation. Such reproduction can be performed by means of any existing techniques or a combination thereof, including sinterization and mechanization by means of computer-aided design and computer-aided manufacturing (CAD-CAM). These protuberances will be adapted to the applied technique, as well as the convenience of its use.
"The prosthesis of the present invention offers a solution to a certain number of different rehabilitations, although one of the most suitable ones is the one that solves the issue of patients with one or both totally edentulous dental arches. In these cases, the prosthesis covers the whole toothless dental arch, be it the upper or lower one, so its primary structure has a frontal wall joined to two lateral walls, while its secondary structure has a frontal covering wall joined to two lateral covering walls.
"However, there can be other situations where the primary and secondary structures have a different configuration. For example, a patient who has all their molars and premolars in one side of the dental arch, or even some canine or incisors next to them, whether they be natural dental pieces or screwed prostheses. In this case a frontal wall is configured so as to partially occupy the space of incisors and canines of the dental arch, joined to only one lateral wall which partially occupies the space of molars and premolars. The secondary structure is configured following the same guidelines in order to obtain a hybrid prosthesis.
"Thus, there exists a certain number of cases which allow the use of hybrid prostheses applying the same aforementioned principles of configuring the frontal and lateral walls to occupy the space of dental pieces missing in the dental arch, to comply with basic above defined requirements of the primary structure. Another example can be a patient who still has the third and second canines in both sides of the dental arch.
"The primary and secondary insertion means comprise respectively primary support means and secondary support means which allow the occlusal support of the secondary structure over the primary structure. That is to say, a perpendicular or axial support with respect to the molars and premolars masticatory surface. Preferably, the primary and secondary support means comprise respectively an occlusal external flat surface on the primary structure and an internal flat occlusal surface on the secondary structure. In this way, the secondary structure support over the primary structure is an absolutely flat support which helps distribute axial forces and represents an insertion guiding plane during vestibular insertion as it will be seen hereinafter.
"Additionally, the primary insertion means and secondary insertion means respectively comprise primary guiding means and secondary guiding means configured to guide the secondary structure over the primary structure during the vestibular insertion. Preferably, the primary guiding means comprise a plurality of horizontal recesses or protrusions mechanized in a staggered manner along the outer face of the lateral wall. While the secondary insertion means comprise a plurality of horizontal protrusions or recesses mechanized along the inner face of the lateral covering wall, configured to fit with the horizontal recesses or protrusions respectively of the primary guiding means, and slide along them until the secondary structure is completely supported over primary structure. The terms 'horizontal' mentioned in the present paragraph are also equivalent to 'parallel to the occlusal plane'. Preferably, recesses are located in the primary structure, while protrusions are located in the secondary structure, although they can be distributed in the opposite way. Recesses can be obtained by milling in the form of staggered rails on the corresponding face, while the protrusions can be obtained by adding material on the corresponding face to create a particular thickness or volume with complementary dimensions thereto. Besides facilitating the guidance during the vestibular insertion, the primary guiding means and secondary guiding means also counteract axial and non-axial stress.
"Additionally, the primary insertion means and the secondary insertion means respectively comprise primary fitting means and secondary fitting means configured to assemble the secondary structure with the primary structure during the vestibular insertion. Preferably, the primary fitting means comprise a plurality of marks or horizontal reliefs mechanized with a half-moon shape on the outer occlusal face of the frontal wall. While the secondary fitting means comprise a plurality of marks or horizontal reliefs mechanized on the occlusal inner face of the frontal covering wall, configured to fit with the marks or horizontal reliefs of the primary fitting means respectively. The terms 'horizontal' mentioned in the present paragraph are also equivalent to 'parallel to the occlusal plane'. Preferably, the marks are located in the primary structure, while the reliefs are located in the secondary structure, although they can be distributed in the opposite way. The marks can be obtained by milling with a half-moon shape on the corresponding face, while the protrusions can be obtained by adding material on the corresponding face to create a particular thickness or volume with complementary dimensions thereto. Besides facilitating the assembling during the vestibular insertion, the primary fitting means and the secondary fitting means also counteract axial and non-axial stress.
"According to a second preferred embodiment, the primary fitting means comprise a rail-like front extension of the frontal wall upper part. While the secondary fitting means comprise a fastening notch mechanized over the inner occlusal face of the frontal covering wall configured to fit with the primary fitting means front extension.
"Both embodiments of the primary and secondary fitting means described above offer different uses. In this sense, the first embodiment of the fitting means is ideal for class II occlusion compensations. Specifically, thanks to the 'platform-type' design they have, the incisor position of the corresponding secondary structure can be moved backwards to the maxilla arch, even behind the location of the implants, until reaching the desired aesthetic degree. Also, the second embodiment of the fitting means is ideal for class III occlusion compensation. Specifically, thanks to the 'claw-type' design that they have, the incisor position of the corresponding secondary structure can be moved forward to the arch of the maxilla, even behind the location of the implants, until reaching the desired aesthetic degree. Also, the second embodiment of the fitting means is ideal for class III occlusion compensation. Specifically, thanks to the 'claw-type' design that they have, the incisor position of the secondary structure corresponding to the maxilla arch can be moved forward, until reaching the desired aesthetic degree.
"Additionally, the primary insertion means and the secondary insertion means respectively comprise primary retention means and secondary retention means configured to fix the secondary structure on the primary structure after the vestibular insertion. Having a primary structure fixed on the implants, regardless of the secondary structure, enables to adopt working modes which greatly simplify the dentist's o dental technician's work and they increase patients comfort. For example, in case of having to fix any definitive prosthesis, said prosthesis can be easily replaced by a provisional prosthesis, since it is only necessary to release the secondary structure from the primary structure, which is permanently attached to the implants. The primary retention means and the secondary retention means are also designed to facilitate these tasks. In this sense, we contemplate different solutions that can be used independently or jointly.
"In the first solution, the primary retention means and the secondary retention means comprise a plurality of lateral orifices respectively located on the lateral wall and on the lateral covering wall, suitable for the use of retention pins. Even though screws can also be used, retention pins have the advantage of faster mounting and dismounting.
"According to a second solution, the primary retention means and the secondary retention means comprise a plurality of axial orifices respectively located on the primary external occlusal surface and on the secondary internal occlusal surface, suitable for the use of retention screws.
"According to a third solution, the primary retention means comprise a primary end orifice placed at the end of the recess or horizontal protrusion furthest from the frontal wall. While the secondary retention means comprise an axis arranged at the end of the recess or horizontal protrusion furthest from the frontal wall, which fits with the primary end orifice. Said primary end orifice can have any needed geometric configuration such as circular, square, triangular, among others, according to the axis geometric configuration.
"According to a fourth solution, the primary retention means comprise a primary fitting orifice located in at least one of the marks or reliefs of the frontal wall. While the secondary retention means comprise a secondary fitting orifice located in at least one of the reliefs or marks of the frontal covering wall coinciding with the primary fitting orifice suitable for the use of fitting screws.
"The present invention can be manufactured with any of the most widely used materials in this sector such as, Ti, Cr--Ni, Cr--Co, Au, Pd, Zi, among others."
For additional information on this patent, see: Rubio Cebria, Justo Manuel. Dental Prosthesis. U.S. Patent Number 8628326, filed
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