WO2016077902A1

WO2016077902A1 - Improvement made to a block for production of fixed prosthesis restorations

Info

Publication number: WO2016077902A1
Application number: PCT/BR2015/050220
Authority: WO
Inventors: Dalton MATOS RODRIGUES
Original assignee: Matos Rodrigues Dalton
Priority date: 2014-11-18
Filing date: 2015-11-18
Publication date: 2016-05-26
Also published as: BR202014028680U2

Abstract

"Improvement made to a block for production of fixed prosthesis restorations", comprising a single body formed by prefabricated blocks made from leucite-reinforced glass ceramic, glass-reinforced alumina, densely sintered alumina, Y-TZP zirconia (yttria-tetragonal zirconia polycrystal) with (partial or total) sintering, titanium, precious alloys, non-precious alloys, reinforced-strength acrylics, aluminium oxide, zirconia, lithium disilicate ceramic, cobalt-chrome metallic alloy, resin, feldspathic porcelain, porcelain-based vitrious ceramic or a resin- or porcelain-based composite, provided with a fastening pin that is inserted in the base of the modelling machine (not shown), characterized in that said prefabricated blocks are provided with a through-hole arranged transversally to the fastening pin, the through-hole being formed on the basis of a restraining hole provided with a key channel, immediately followed by a conical hole located in a support wall that delineates a cylindrical hole, for coupling of a prosthetic component (not shown), arranged in the lower section of the restorer element.

Description

IMPROVEMENT IN BLOCK FOR PRODUCTION OF FIXED PROSTHESIS RESTORATIONS

This utility patent application refers to a "PERFORMANCE INTRODUCED IN BLOCK FOR PRODUCTION OF FIXED PROSTHESIS" that was developed to provide a through hole in the block for installation of the so-called prosthetic component, enabling coupling and subsequent cementation of the prosthetic component, facilitating the fixation of the restorative element in the fixed prosthesis, through the implant screw, this hole is arranged transversely to the block hitch pin in the CAD-CAM machine, besides recommending the drilling of blocks of the various types of materials used (aluminum oxide, zirconia, lithium disilicate ceramics, cobalt-chromium alloy, resin, feldspar porcelain, porcelain-based or resin-based or porcelain-based glass ceramics), for use in CAD software and obtaining of pillars or crowns. Specifically, the present invention provides time savings, laboratory work and materials.

State of the Art

CAD-CAM refers to the design of a prosthetic structure on a computer (Computer Aided Design) followed by its manufacture by a milling machine (Computer Aided Manufacturing). It is a technology widely used in many industries and due to its introduction in Dentistry, in the late 70's and early 80's of the last century, Bruce Altschuler, USA, François Duret, France, and Werner Mormann and Marco Brandestini, in Switzerland. The main objectives of this technology were then to automate a manual process to obtain high quality material, standardize manufacturing processes and reduce production costs. In 1977, Young, Altschuler29 presented the idea of using laser holography for intraoral mapping. In 1984 Duretl developed the "Duret System" for making single crowns. According to this author, the main advantages of this technique were to reduce the heavy manual dependence on the manufacture of prosthetic restorations and, at the same time, to reduce costs. However, Duret's device was too complex and expensive. The first system to be used and commercially viable was CEREC (CEramic REConstruction), developed by Morman and Brandestini in 1980 at the University of Zurich, Switzerland.

CAD-CAM technology has been used in dentistry mainly in the production of fixed denture restorations such as crowns, bridges and veneers. Several companies have developed high-tech CAD-CAM systems, which are based on three key components: scanning readiness, prosthetic restoration design (CAD) software, and prosthetic framework milling (CAM). ). There are currently two types of CAD-CAM systems depending on the availability of assigning CAD files: open CAD-CAM systems or closed CAD-CAM systems. The advantage of an open system is that you can choose the CAM system that best suits your purpose because you can transmit the CAD file to another computer. Closed CAD-CAM systems offer the entire production system.

These systems can also be classified according to where they are used: clinic or laboratory. The vast majority of systems work in the laboratory; However, the CEREC system is the only one that has both modes: Chairside, especially for the clinic, and inLab, essentially for the laboratory. Prior to the digitalization of the structure, there are some considerations regarding dental preparation.

Apart from the usual assumptions regarding the thickness of the cut and the material to be used, the remaining dental structure cannot have sharp angles. The structures are made of ceramic, and the presence of sharp angles would induce fracture lines of the material. Furthermore, the machining system of the prosthetic part, especially the shape of the drill tip and its thickness, cannot reproduce such angles. Typically, the ideal finishing line in these systems is the wide bevel or rounded internal angle shoulder.

Dental preparation can be digitized outside the oral cavity, on the cast model (changed), or inside the oral cavity, by an intraoral scanning system. Although more practical and faster to apply, intraoral scanning systems still do not allow sufficiently accurate images of spatial relationships, especially when multiple teeth are involved in prosthetic rehabilitation. According to Tinschert et al., In the current state of CAD-CAM technology, extraoral methods are preferable. However, these methods have some disadvantages, such as the time taken and the fact that they require an impression of dental preparation, which also introduces error factors in this process.

After the dental preparation has been digitized, the image is transferred to a computer-aided design program, whereby the operator can then virtually design the prosthetic structure. Eventually, if necessary, a waxing can be performed, which is then scanned and handled by the software. In this phase, the finishing lines, spacing and thickness of the restoration to be machined are defined. Despite the evolution of prosthetic restoration design programs to a easier design, especially with the introduction of 3D and prosthetic structure databases, it is assumed that the operator has some computer skills.

The materials used for milling the prosthetic structure are prefabricated blocks of the following materials: leucite-reinforced glass ceramics, glass-reinforced alumina, densely sintered alumina, Y-TZP Zirconia (Yttrium-tetragonal polycristal zirconia) with sintering (partial or total), titanium, precious alloys, non-precious alloys and strengthened acrylics. One of the great advantages of using these systems is the ability to work with very resistant materials such as zirconia, which, as far as manual manufacturing is concerned, is very limited.

Currently, zirconia is the toughest ceramic available for use in dentistry, which is why it was highlighted in this paper.

This material has the potential to allow the construction of bridges in high tension sectors, for example in the posterior areas of the mouth, as it reveals a very high fracture resistance, three to four times higher than the largest masticatory load. In a 2004 review article, Raigrodsky reports that a flexural strength of 900 Mpa-1,200 Mpa (1 MPA = 1 n / mm2) in Y-TZP bars has been demonstrated in in vitro studies; 1,800-2,000 N in fixed partial dentures with different connectors (static loads); and 1,457 N in a simulation of a five-year cyclic load on a fixed three-element partial denture. Although there are no long-term studies yet, there are studies with one, two and three years of duration in which a single failure of the infrastructures has not yet been found. This high strength of zirconia derives from its formulation, known as Y-TZP Zirconia. Zirconia (Zr02) is an oxidized form of zirconium metal, as alumina refers to aluminum metal. Yttrium oxide is an agent that is added to pure zirconia to provide stability at room temperature and to produce a multiphase material known as yttrium partially stabilized zirconia (Y-TZP). This material has a property known as "transformation toughening": under stress, the material undergoes dimensional change, with volumetric increase of 3 to 4%, generating compression stresses that inhibit the propagation of fracture lines so frequent in ceramics. For this reason, zirconia is known as "Intelligent Ceramics". It is a feature similar to the action of the dentin-junction on the natural tooth. On the other hand, it should also be noted that regarding biocompatibility and aesthetics, zirconia has a higher value compared to metalloceramic restorations. For use in CAD-CAM milling machines, zirconia comes in two forms:

• Fully sintered zirconia (hard) - implies a long working time (2 to 4 hours for a unit) and heavy wear with drills. According to Luthardt et al., The wear of this zirconia with diamond drills can damage the material, compromising its strength and viability, which is why the author advises the more favorable use of partially sintered zirconia;

• Partially sintered zirconia (soft zirconia) - allows for easier and faster processing. However, due to its partially sintered condition, it needs 6 to 8 hours in a special ceramic oven to complete sintering. Due to this process, there is a dimensional change that must be compensated during the initial virtual drawing of the structure.

Once the material has been selected, the prefabricated blocks are then subjected to a subtractive milling process according to the number of axes (3 to 6 axes), depending on the system in question. To finish the structure, besides the insertion test, the polishing and the individualization of the structures with cosmetic ceramics are required.

Developed at the University of Zurich, the CEREC system was the first CAD-CAM system to achieve clinical and commercial success. This system makes an optical reading without contact with the dental preparation. The measurement method used is active triangulation, with a resolution of 25 μπι. The generated 3D image is then transferred to a computer on which the The system CAD program allows the structure to be designed. The finishing line is automatically detected and can also be modified manually and is subsequently executed on the same system milling machine (CAM). This unit features two diamond drills that cut the frame on four working axes and with a cutting reproducibility of approximately 30 μπι17. The fact that the ceramic block is secured on one side prevents the action of the drill in that area, which is subsequently milled manually. The system allows the production of hoods, incrustations, partial crowns, facets and full crowns for fore and aft regions in a single session.

According to the information provided by the brand, CEREC® currently stands for Chairside Economical Restorations Esthetic Ceramic5. In fact, this is the only system that has a version for clinical use (CEREC Chairside®), which makes it very practical and less dependent on laboratory work and can also translate into some financial savings (Economical). The launch of new products, such as CEREC 3D®, CEREC Chairside® and Triluxe® ceramic blocks, compensated for defects in previous CEREC® models and enabled the construction of more aesthetic ceramic restorations. The introduction of CEREC 3D® allows the clinician to capture multiple images more accurately and then create a virtual model, for example for a complete quadrant. However, according to Tinschert et al., This technology of the CEREC system is not yet sufficiently accurate to permit its approval to construct fixed prostheses of various elements.

Triluxe® is a new three-color ceramic block model that replaces the old mono-chromatic blocks and is reflected in an improved aesthetic potential of the system. CEREC InLab® is a laboratory system whereby the dental preparation plaster model is subjected to a laser scanning, and the computer infrastructure (CAD) was then designed and the ceramic block machined. Once the infrastructure is prepared and verified, the laboratory completes it with cosmetic ceramics. Procera®

To date, the Procera / AllCeram® system has produced more than 5 million prosthetic units, thus proving to be one of the most successful CAD / CAM systems. Due to this technology, the plaster model is digitized by contact using a Procera® scanner (Piccolo® - for single crowns, veneers and abutments; Forte® - also for 2 to 4 element prostheses). The "digitizing tip" exerts a small pressure of 20 g on the model to ensure accurate contact.

Although 50,000 readings are taken in one preparation by this procedure, the process takes approximately 30 seconds. The scanned image (3D CAD) is then sent to a Procera® processing center (Sweden - Karlskoga and Stockholm; U.S. - New Jersey) via a modem connection. In this plant, replicas of the wider plaster model are made to compensate for the ceramic contraction when sintering. Despite the high technical difficulty of this last procedure, a marginal adaptation of the Procera crowns with spacing between 54 μπι and 64 μπι is within clinically acceptable parameters. The hoods can then be produced in high purity alumina (0.4 mm thick in cases requiring accurate aesthetics or 0.6 mm in other indications) or zirconium (0.7 mm when higher material strength is required) . Within 48 hours, the hood is back in the lab to place the ceramics.

The strength of the materials used reaches high values, which, in the case of alumina, are 687 MPa and zirconia 1,200 Mpa2. Dental preparation also requires an appropriate technique, with the execution of guidelines cervical finish in broad chamfer, cervical-occlusal stump height of 3 mm and lower pontics there mm, when in alumina.

The Lava® system enables the fabrication of front and rear ceramic crowns and bridges. The cervical finishing line of dental preparations may be a bevel or a shoulder with a rounded internal angle. In this system, the various finishing lines of dental preparations and the edentulous ridge are digitized by an optical laser that transmits the images to a computer, where the system's assisted design program automatically determines the finishing lines and suggests the pontics. . Due to the shrinkage of the ceramic during sintering, as described in the Procera® system, the infrastructures are designed with a 20% increase in volume.

Subsequently, pre-sintered zirconia blocks are used for milling, noting that the system is capable of producing up to 21 hoods or bridge structures without any manual intervention. The zirconia blocks used can be colored with seven shades of color prior to the final sintering, which can give high aesthetic levels. To complete sintering, the LAVA® system includes a special high temperature oven.

And a system that includes a scanning machine, CAD software, a milling machine and a ceramic sintering oven. The plaster (anti-glare) model is digitized by an optical reading through a CCD camera (1: 1 real dimension and 20 μπι precision), and the 3D image is created through 15 projection sequences. The prosthetic restoration is then designed in CAD software and then milled using five-axis cutting movements in blocks of various types of materials: partially sintered zirconia - ZS-Blanks; fully sintered zirconia (ZH-Blanks), titanium (Grade 2 - T-Blanks) and leucite-reinforced glass ceramics. The number of axes of the milling unit is one of the parameters that most influences the geometric detail of restorations. Larger number of spindles allow drills to assume more positions according to the block and thus produce greater detail. It should be noted that the way to support the block in CAM units will also influence the number of axes. For example, in the CEREC system, blocks are always held by a support element on one side of the block, which prevents drill action in that zone. The Everest® system introduced the concept of support using acrylic resin, thus allowing complete freedom of movement of the drills around the restoration.

Although this is an advantage in terms of geometrical capacity, it slows the system as it requires manual intervention in the middle of the milling process to reposition support acrylic resin. The milling machine allows the fabrication of structures with a maximum dimension of 45 mm. Milling of the structures can take 2 to 4 hours for the crown for hard zirconia and about 20 minutes for soft zirconia, with subsequent 8-hour sintering.

Today's dentistry demands quality standards far superior to those found in the last century, under two fundamental levels: functionality and aesthetics. The implementation of CAD-CAM technology, with its various systems, will help to achieve this effect, not in the sense of "serial production" (rather the opposite), but in improving the production of restorations by using design and design. computer-aided clothing. The fact that they are essentially computerized technologies requires the clinician and laboratory to adapt their work dynamics in order to make the most of their investment. These systems will also allow to work with very resistant materials, such as zirconia, because the studies presented throughout this work provide good scientific and clinical indications that zirconia can completely replace metal in infrastructures. prosthetic However, there should be some caution in the case of posterior prostheses, as although there are favorable studies, they are very recent.

Some prosthetic components (abutments), such as those produced by the manufacturing companies, have limited conditions for modification and adaptation according to each patient's clinical case. This process is not industrially viable, the customization of the abutment is very costly as its production respects very tight tolerances and very high accuracy. CAD software has a tool for manufacturing custom ceramic abutments on a specific abutment. The blocks have a hole for coupling to the prosthetic component of the implants. The prosthetic component at its bottom has a connection according to the geometry of each specific implant mark.

Aiming at perfecting the clinical procedure in the fixation of dental restorations, the inventor after studies developed the "FIXTURE IMPROVEMENT FOR PRODUCTION OF FIXED PROSTHESIS" comprised of a single body formed by prefabricated blocks made of glass ceramic reinforced with leucite, glass-reinforced alumina, densely sintered alumina, Y-TZP Zirconia (Yttrium-tetragonal zirconia polycristal) with sintering (partial or total), titanium, precious alloys, non-precious alloys, strengthened acrylic, aluminum oxide, zirconia , lithium disilicate ceramics, cobalt-chrome alloy, resin, feldspar porcelain, porcelain-based or resin-based or porcelain-based glass ceramics, with clamping pin that is inserted into the base of the shaping machine (not shown), characterized said prefabricated blocks are provided with a through hole disposed transverse to the fixing pin, the through hole being formed from a locking hole provided with a keyway, followed immediately by a tapered hole ending in a back wall projecting a cylindrical hole for coupling a prosthetic component (not shown) arranged in the lower section of the restorative element.

To give a perfect understanding of what has been developed, illustrative drawings are attached to which numerical references are made together with the following detailed description where:

Figure 1 shows a perspective view of the block.

Figure 2 shows a side view of the block.

Figure 3 shows a cross-sectional view of the block alluding to the coupling hole of the prosthetic component.

Figure 4 shows a side view of the block alluding to the securing pin. As illustrated by the figures and in their details, the "PERFORMANCE INCLUDED IN BLOCK FOR PRODUCTION OF FIXED PROSTHESIS" comprised of a single body (1) consisting of prefabricated blocks (2) made of leucite-reinforced glass ceramics, alumina reinforced glass, densely sintered alumina, Y-TZP Zirconia (Yttrium-tetragonal zirconia polycristal) with sintering (partial or total), titanium, precious alloys, non-precious alloys, strengthened acrylic, aluminum oxide, zirconia, lithium disilicate, cobalt-chromium alloy, resin, feldspar porcelain, porcelain-based or resin-based or porcelain-based glass ceramics, with clamping pin (3) that is inserted into the base of the shaping machine (not shown), characterized said prefabricated blocks (2) have a through hole (4) disposed transversely to the fixing pin (3), the through hole (4) being from a locking hole (5) provided with a keyway (6), immediately followed by a tapered hole (7) that ends in a back wall (8) that projects a cylindrical hole (9) for coupling prosthetic component (not shown) arranged in the lower section of the Restorative element.

Based on what is described and illustrated, it can be seen that the "PERFORMING BLOCK INTRODUCTION FOR FIXED PROSTHESIS RESTORATION" has enormous advantages, as the CADEC CAM type block drilling system for coupling and subsequent cementation of prosthetic component. It consists essentially of making holes for installation of the so-called prosthetic component. The hole is perfectly designed for a perfect fit between the hole and the component. The hole is made in the lower part for fitting the prosthetic component and continues a 2.6 mm hole through which a screw will pass. This system makes it possible to obtain screw-based restorations on implants performed by the CAD-CAM system.

Because they meet all the requirements that define the utility model patent, because it combined and modified known elements, giving them a general innovative and industrializable aspect, and modifications that can be made without departing from the spirit and scope of the present patent, they are the following your claims.

Claims

CLAIM

1- "BLOCK-INPRODUCED IMPROVEMENT FOR PRODUCTION OF FIXED PROSTHESIS" "comprised of a single body (1) consisting of prefabricated blocks (2) made of leucite-reinforced glass ceramics, densely sintered alumina , Y-TZP Zirconia (Yttrium-tetragonal polycristal zirconia) with sintering (partial or total), titanium, precious alloys, non-precious alloys, strengthened acrylics, aluminum oxide, zirconia, lithium disilicate ceramics, chromium cobalt, resin, feldspar porcelain, porcelain-based glass ceramic or resin-based or porcelain-based composite, provided with a clamping pin (3) that is inserted into the base of the shaping machine (not shown), characterized by said prefabricated blocks ( 2) be provided with a through hole (4) disposed transversely to the fixing pin (3), the through hole (4) being formed from a locking hole (5) provided of keyway (6), followed immediately by a tapered bore (7) that ends in a back wall (8) that projects a cylindrical bore (9), for coupling a prosthetic component (not shown) disposed in the lower section of the restorative element.