WO2009121920A1

WO2009121920A1 - Root pin for the endodontic care of a root-stump

Info

Publication number: WO2009121920A1
Application number: PCT/EP2009/053908
Authority: WO
Inventors: Detlef Behrend; Klaus-Peter Schmitz; Katrin Sternberg; Wolfram Schmidt
Original assignee: Universität Rostock
Priority date: 2008-04-02
Filing date: 2009-04-01
Publication date: 2009-10-08
Also published as: DE102008017385A1

Abstract

In order to improve a root pin (10) for the endodontic care of a root-stump, in particular combined with occlusal caps, said root pin has a one-piece base body (14) made from a plastic matrix material and it offers increased safety in relation to pin and root fractures. According to the invention, said one-piece base body (14) is helical and is designed to taper from the proximal to the distal end.

Description

Root post for endodontic post-butt restoration

The invention relates to a root post for the endodontic pin-butt supply.

In the dental care, d. H. in the reconstruction of lost coronal tooth substance, there is a steadily growing demand, in particular with special consideration of demographic shifts within the age pyramid. This has led to the development of new materials, constructive solutions and adhesive techniques in this area, so that traditional treatment principles are increasingly called into question.

Basically, a reliable anchorage for definitive restorations is required, while sparing healthy hard tooth substance. With the Adhäsivtechnik is the

Mastery of many clinical situations while avoiding conventional ones

Although root canals are possible, the teeth are built up directly with a central access cavity by means of plastic composite materials, so that in the case of low and medium destruction of the hard tooth substance, a crowning can be avoided in most cases. However, severely damaged teeth, the one

Root canal treatment, which subsequently has too little substance to be crowned, must be stabilized by a post assembly that provides sufficient retention for a crown. The basic

The procedure has meanwhile become a clinically established method, which is used on millions of patients worldwide every year. The construction of endodontically treated teeth is a prerequisite for their long-term preservation and for the

Implementation of a forward-looking therapeutic overall concept.

The physical properties of dentin are not significantly altered by the endodontic treatment. A weakening is but as a result of

Tooth hard tissue loss through the access cavity, the removal of the Kavumdaches and caused by pilot holes for root canal pins. Metallic and ceramic root canal pins are space consuming and are unable to increase the stability of the endodontically treated tooth mostly. A preparation of the root canal for filling or pin anchoring is possible without increased risk directly after the application of the root filling. The duration of a temporary restoration, especially in combination with temporary pens, is kept as short as possible due to the fracture risk and the increased risk of reinfection of the root canals.

A major disadvantage is the failure rates present in conventional conventional techniques. As a result of root fractures, pen breakages and loss of retention of post abutments, these are estimated to be between 5.2 and 13.6%. After the preparation of a root canal, it is first provided with a Endo-Sealer for a definitive root filling and subsequently filled with gutta-percha. For the purpose of root canal filling a wide variety of material classes are used. In many cases, methacrylate-based materials are used. In addition, zinc oxide / eugenol and glass ionomer cements but also silicone materials are used.

If, after preparation, there is insufficient tooth hard tissue for adhesive retention of the abutment, root canal posts are used. The largest proportion of the currently used root posts is made of metal or alloys or ceramics. However, the material properties of these material classes are very different from those of the hard tooth substance. Unadjusted hardness and structural moduli are increasingly blamed for subsequent root fractures. A common cause of failure of these supplies is also in the pen break.

Recently, however, research in the field of fiber-reinforced plastic materials for use as a root canal pen is also being researched. This composite

Materials show a much more favorable potential with regard to a post construction as metals and ceramics. A major disadvantage of the root posts used hitherto in clinical use is the high structural stiffness and the "splicing" in the region of the highest bending moment in fiber-reinforced pins.

To improve the retention in the root canal, it is known to structure the surface of root posts. For example, threads or circumferential ribs are provided with metallic pins. However, stress peaks in the hard tissue of the treated tooth are thereby induced, which can cause further damage to the tooth. In addition, a rib structure makes it more difficult to remove again. In the case of fiber-reinforced pins, on the other hand, rounded ribbed structures are predominantly used for production reasons, which also make the removability more difficult.

In addition, root posts require displacement channels to reduce hydraulic pressure during insertion using cement or the like, otherwise there is a risk of cement leakage from the root apex. Such displacement channels are problematic in fiber-reinforced pins, as they cause sharp edges on the pin, which in turn lead to splittings.

It is therefore an object of the invention to provide a root post for endodontic post-butt restoration, which provides increased security against pin and tooth root fractures compared to the prior art.

This object is solved by the features of claim 1.

It is provided according to the invention that the root post has a one-piece body of a plastic matrix, which is preferably fiber-reinforced, wherein the one-piece body is coiled in and tapers from proximal to distal. Advantageously, the surface of the coiled base body is designed rounded, so that splices can be safely avoided. In addition, no stress peaks in the hard tissue of the tooth are induced and ensures a gentle removability due to this special design.

In this case, the root pin has at least two, preferably three deformation zones with a different bending and torsional stiffness from the rest of the body, which are arranged consecutively from proximal to distal.

This embodiment of a root post with at least one deformation zone based on the helix or the taper prevents the root post and, if necessary, the treated root from breaking under load or splitting in these areas, which ultimately can also lead to breakage. In several deformation zones, the risk of breakage over the entire length of the root post is improved. The increased lifespan of the root posts also significantly reduces costs.

Preferably, the flexural and torsional stiffness of the three preferred deformation zones from proximal to distal is in the ratio 1: 2/3: 1/3.

Alternatively, the flexural and torsional stiffness of the post may also decrease continuously from proximal to distal, with the flexural and torsional stiffness at the proximal end to that at the distal end preferably in the ratio 1: 1/3.

In particular, the root post is suitable for the endodontic post stump in combination with occlusal caps.

The spiraling of the base body is formed by axial displacement elements or channels and / or grooves, which ultimately gives a rhizome-like configuration. This design prevents safe Splitting of the root post and ensures safe removability by Rotationsbegungen under axial tension (unscrewing). In addition, the hydraulic pressure is reduced during insertion, so that the root tips are spared.

In a preferred embodiment, the spiraling can be designed in such a way that a "cavity" results along the longitudinal axis of the root pin, comparable to a corkscrew with "soul". This then provides a channel for discharging cement displaced upon insertion of the pin so that hydraulic pressure is minimized resulting in no damage to the root tip. A derivation of the cement is also ensured in the other embodiments, but provides a vertical channel, which can also be designed differently sized, depending on different viscosities of the cement even greater security.

The post has a retention head or setting head at the proximal end, which ensures an optimal bond between the post and the body and easy removability.

The plastic matrix consists of an organic polymer, which is preferably epoxy, methyl methacrylic or Polyurethanangießharz and preferably having a reinforcement of organic and / or mineral fibers and / or filler particles.

In order to effect a reinforcement of the matrix, short fibers, preferably following the main stress direction, and / or round knitted fabrics, which may be present in one or more layers, are introduced into these.

Preference is given to carbon nanotubes, which are designed as a single wall or double wall. Also preferred are carbon fibers, silanized glass fibers and / or ceramic fibers, preferably carbon-fiber or carbon fibers.

Furthermore, nano-disperse materials and / or X-ray contrast agents may be introduced as fillers, preference being given to carbon nanotubes, tin-coated SiO 2, nanodispersed Ag and / or Au, CeO, SnO 2, WO 3.

The fibers and fillers are preferably present in a proportion of 50-90 vol.% In the matrix.

To set the root pin, the setting head is designed such that it can be screwed into the root via a corresponding application instrument. Preferably, the setting head has, in plan view, a semicircular configuration which corresponds to a recess in the application instrument for positive temporary seating.

Further advantageous embodiments of the root post according to the invention are characterized in the subclaims.

The invention will be explained in more detail with reference to a drawing. It shows

Fig. 1. in a side view a root pin with retention head according to the invention.

The illustrated in Fig. 1 root pin 10 for the endodontic pin-butt restoration is introduced into a prepared root canal 11 of a partially illustrated tooth 12, wherein also in the root canal 11, a filling material 13 is located. The root post 10 has a one-piece main body 14 made of a plastic matrix, at the proximal end 15 of which a retention head or setting head 16 is located. In the distal direction, the base body 14 tapers. In addition, the base body 14 has a spiral 17, which by axial Displacement elements 18 and channels 19 is formed. Due to the spiraling 17 and the tapered main body 14 of the root post 10 has deformation zones 20, 21 with a different bending and torsional stiffness from the rest of the main body 14.

LIST OF REFERENCE NUMBERS

Root post 10

Root canal 11

Tooth 12

Filling material 13

Base 14 proximal end 15th

Retention head or setting head 16

Spiraling 17

Displacement elements 18

Channels 19

Deformation zones 20, 21

Claims

claims

1. root post for the endodontic pin-butt restoration, comprising a one-piece base body of a plastic matrix, characterized in that the one-piece base body (14) is coiled in and tapers from proximal to distal.

2. root post according to claim 1, characterized in that the surface of the coiled base body (14) has a rounded shape.

3. root post according to claim 1 or 2, characterized in that the root pin (10) has at least two, preferably three deformation zones (20, 21) with a different base body (14) different bending and torsional stiffness, the proximal to distal to each other are arranged following.

4. root post according to claim 3, characterized in that the bending and torsional stiffness of the deformation zones (20, 21) from proximal to distal in the ratio 1: 2/3: 1/3 stands.

5. root post according to claim 1 or 2, characterized in that the bending and torsional stiffness of the post (10) decreases continuously from proximal to distal.

6. root post according to claim 5, characterized in that the bending and torsional stiffness of the root post (10) at the proximal end to the distal end in the ratio 1: 1/3.

7. root post according to one of claims 1 to 6, characterized in that the spiraling (17) of the base body (14) by axial displacement elements (18) or channels (19) and / or grooves is formed.

8. root post according to one of claims 1 to 7, characterized in that the spiraling (17) leaves a cavity along the longitudinal axis of the post (10).

9. root post according to one of claims 1 to 8, characterized in that the base body (14) proximally has a retention head or setting head (16).

10. root post according to one of claims 1 to 9, characterized in that the base body (14) comprises a hollow or solid plastic matrix having a reinforcement of organic and / or mineral fibers and / or filler particles.

11. root post according to one of claims 1 to 10, characterized in that the matrix consists of an organic polymer, preferably of an epoxy, methyl methacrylic or Polyurethanangießharz.

12. root post according to claim 10 or 11, characterized in that the gain in the matrix is a short fiber and / or Rundgewirkverstärkung, which is present in one or more layers.

13. root post according to claim 10 or 11, characterized in that the reinforcement in the matrix are carbon nanotubes, which are formed as a single wall or double wall.

14. A root post according to any one of claims 10 to 13, characterized in that the fibers are carbon fibers, silanized glass fibers and / or ceramic fibers, preferably carbon-fiber or carbon fibers, the Main stress direction are introduced following, preferably in the form of tubular circular knitted fabrics.

15. A post according to any one of claims 10 to 14, characterized in that are introduced as fillers nanodisperse materials and / or X-ray contrast agent.

16. root post according to claim 15, characterized in that the fillers are carbon nanotubes, tin coated SiO2, nanodispersed Ag and / or Au, CeO, SnO ₂ , WO3.

17. A post according to any one of claims 10 to 16, characterized in that the fibers and fillers are present in a proportion of 50-90 vol.% In the matrix.