Dentistry – Method or material for testing – treating – restoring – or... – By filling – bonding or cementing
Reexamination Certificate
2000-03-14
2001-09-18
Lucchesi, Nicholas D. (Department: 3732)
Dentistry
Method or material for testing, treating, restoring, or...
By filling, bonding or cementing
C433S080000, C433S082000
Reexamination Certificate
active
06290503
ABSTRACT:
This invention pertains to a dental device for dispensing a slurry-like filling material into a tooth cavity, including a root canal, comprising a plastic sleeve which contains the filling material and a dispensing tip for pushing the filling material into the cavity. The plastic sleeve also forms a seal around the cavity to be filled and prevents undesirable extrusion of filling material onto the surrounding tissues.
Dentists and endodontists use various materials to fill surgically prepared cavities or to seal spaces within a tooth. The consistency of the filling material is highly variable. For example, silver amalgam is a liquid metal of high density which is compressed into the cavity with force. Gutta percha is a rubber material, which is usually heated to increase its plasticity before placing into the cavity. Others, e.g., cements based on zinc oxide eugenol, are viscous and capable of flowing into the cavity. The choice of filling material and dispenser depends on the size and placement of the cavity that needs to be filled. In an orthograde filling process, the tooth cavity is filled through the crown area of the tooth, usually into a relatively large area. In a retrograde filling process, where the tooth is filled through the root-tip area, the surgical opening in the gum and bone to expose the root and the root-tip canal is smaller and requires a precise filling technique.
An effective filling material exhibits various qualities, such as adhering to the walls of the cavity, compatibility with the surrounding tissue, and suitability for moist environments. In a retrograde filling process, biocompatibility is even more important. A filling material that will allow natural tooth tissue, cementum, to grow will more fully protect the root area from bacteria. Many filling materials are not effective as a retrograde filling material because they are not tissue-compatible. For example, amalgam, a commonly used retrograde filling material, does not allow the growth of cementum and allows leakage due to its poor adaptation to the dentinal cavity walls. Amalgam has been shown to corrode after exposure to moisture over time. The zinc oxide eugenol-based cements are moisture-sensitive, irritate tissues, and clinically are difficult to handle.
A new generation filling material that has shown to be more biocompatible is Mineral Trioxide Aggregate (“MTA”), for example ProRoot™ MTA (Dentsply Tulsa Dental, Tulsa, Okla.), described in U.S. Pat. Nos. 5,415,547 and 5,769,638. MTA is useful for both orthograde and retrograde filling. MTA is similar to Portland cement and comprises fine hydrophilic particles of tricalcium silicate, tricalcium aluminate, and tricalcium oxide, which set in the presence of water into a colloidal gel. MTA is packaged as a dry powder and, with the addition of water, forms a slurry with a putty-like consistency, which normally hardens within 4 to 5 hours. MTA is used in a wide variety of dental applications, including as pulp capping material, as root-end filling material, in orifice sealing, in fracture sealing, as repair of root canals as an apical plug, and as repair of root perforations during root canal therapy. See M. Torabinejad et al., “Physical and chemical properties of a new root-end filling material,” Journal of Endodontics, vol. 21, pp. 349-353 (1995). The density of MTA can be increased by tapping the filling material to remove trapped air bubbles and to settle the silica particles. Although MTA is not itself radiopaque, a radiopaque component, for example, bismuth oxide (Bi
2
O
3
), may be added for diagnostic purposes.
The eventual hardening of MTA is not as affected by moisture and blood as are other filling materials. Instead, moisture assists in the hydration reactions responsible for hardening. Additionally, MTA is biocompatible, allowing cementum to grow and increase the seal against bacteria around the tooth. See M. Torabinejad et al., “Tissue reaction to implanted root-end filling materials in the tibia and mandible of guinea pigs,” Journal of Endodontics, vol. 24, pp. 468-471 (1998); M. Torabinejad et al., “Histologic assessment of mineral trioxide aggregate as a root-end filling in monkeys,” Journal of Endodontics, vol. 23, pp. 225-228 (1997); C. F. Bates et al., “Longitudinal sealing ability of mineral trioxide aggregate as a root-end filling material,” Journal of Endodontics, vol. 22, pp. 575-578 (1996); M. Torabinejad et al., “Investigation of mineral trioxide aggregate for root-end filling in dogs,” Journal of Endodontics, vol. 21, pp. 603-608 (1995); M. Torabinejad et al., “Cytotoxicity of four root end filling materials,” Journal of Endodontics, vol. 21, pp. 489-492 (1995); M. Torabinejad et al., “Dye leakage of four root end filling materials: Effects of blood contamination,” Journal of Endodontics, vol. 20, pp. 159-163 (1994); and M. Torabinejad et al., “Sealing ability of a mineral trioxide aggregate when used as a root-end filling material,” Journal of Endodontics, vol. 19, pp. 591-595 (1993).
The primary problem with MTA has been the lack of an effective method to dispense MTA into a tooth cavity. Currently, MTA is applied, by necessity, with dental devices designed to apply other filling materials with different consistencies, such as gutta percha, amalgam, and viscous zinc oxide eugenol cements. These devices do not satisfactorily dispense MTA into a tooth cavity because they often cause an overflow of MTA. For example, the amalgam devices are designed to deliver a set amount of the dense amalgam when sufficient pressure is applied. MTA is less dense and more fluid than amalgam and is delivered much faster than amalgam by the same device. MTA often overfills the cavity and spills into surrounding tissues. The devices designed for the more viscous cements are usually based on a syringe design. These devices become clogged with the slurry-like MTA because the insoluble particles become lodged in the small bore of the syringe. Many also present sterilization problems. Moreover, none of the current devices are of a design that would allow the formation of a seal between the dispenser and the tooth; a seal that would prevent the MTA from extruding into the surrounding tooth area.
U.S. Pat. No. 5,382,161 describes a prefilled, disposable apparatus for placing a thermoplastic material (e.g. gutta percha) into an endodontically-prepared root canal. The apparatus comprises a displacing shaft and a carrier tip of a hollow segment of cylindrical tubing made of thermoconducting material, preferably stainless steel hypodermic needle tubing. After heating the carrier to soften the thermoplastic filling material, the carrier tip is inserted inside the prepared root canal, and the material is advanced by exerting pressure on the displacing shaft. The stickiness of the heated filling material holds the displacing shaft in the carrier and also forms a seal between the displacing shaft and the carrier.
U.S. Pat. No. 5,067,900 describes another apparatus for applying gutta percha. The apparatus can be heated to pre-soften the gutta percha before inserting into the tooth.
U.S. Pat. No. 3,903,605 describes the use of an electrical, manual, or ultrasonic instrument to heat, condense, and pack gutta percha into a root canal; and the use of ultrasonically-activated tips to place filling material into tooth cavities. U.S. Pat. No. 4,306,864 describes a dental implement for dispensing amalgam. The implement includes a handle with at least one amalgam dispenser and a plugger corresponding to each amalgam dispenser for condensing the amalgam dispensed. Each amalgam dispenser consists of a hollow carrier made of metal, a dispensing rod, and a lever mechanism. The amalgam carrier is raised by depressing the lever mechanism, which causes a portion of the dispensing rod to extend beyond the end of the amalgam carrier, thus dispensing all the amalgam into the tooth cavity.
U.S. Pat. No. 4,767,326 describes a device which consists of a cartridge having a tubular body, a piston and a discharge nozzle. Once the filling material is loaded into the cartridge,
Lemon Ronald R.
Luebke Raymond G.
Board of Supervisors of Louisiana State University and Agricultu
Davis Bonnie J.
Lucchesi Nicholas D.
Runnels John H.
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