Dentistry – Apparatus – Hand manipulatable implement
Reexamination Certificate
2000-02-17
2001-10-30
Manahan, Todd E. (Department: 3732)
Dentistry
Apparatus
Hand manipulatable implement
C433S165000, C433S215000
Reexamination Certificate
active
06309219
ABSTRACT:
TECHNICAL FIELD
This invention relates to dental exodontia for the extraction of teeth. More specifically, inventive instrument is designed to achieve the cutting of the fibrous attachment of the tooth to bone, formed of thousands of microscopic fibers, collectively referred to as the periodontal Ligaments, or PDL.
BACKGROUND
Teeth generally comprise an upper exposed portion, or crown, which is visible and an underlying root structure which is hidden, being anchored within the bony substructure of the gums. The interface between the root structure of the tooth and the surrounding bone is a fibrous attachment. These fibers are referred to as the periodontal ligaments or PDL. The space occupied by the periodontal ligaments is known as the PDL space, and averages about 0.25 mm in thickness and surrounds the entire root structure of the tooth.
It is necessary to separate the ligamental attachment during various surgical procedures. Such procedures include the extraction of teeth, and the installation of dental implants and common surgery to remove roots broken during extraction or through trauma. While extraction is one of the most common dental procedures it is fraught with difficulty. The great forces employed to dislodge teeth from bone are difficult to control and so, have unpredictable outcomes.
One of the main obstacles in the removal of teeth is to overcome the resistance of the PDL. The most common method used to overcome this resistance is bucco-lingual luxation, which expands the socket by loosening of the tooth by grasping with a forceps and rocking the tooth in all directions in order to compress the proximate, relatively spongy portion of the surrounding bone, and stretch the periodontal ligaments until they break. Great force is needed to accomplish this, and the frequent result is fracture of the tooth or fracture of the surrounding bone that forms the buccal plate. Both of these problems lead to further surgical complications.
In the case of a fractured crown, it is often necessary to resort to a full-surgical extraction, elevating the soft tissue and removing bone, in order to gain access to the retained root. Full surgical procedures are time-consuming, traumatic to the patient, and carry more risk of infection and healing complications. In the case of a fractured buccal plate, the bone loses its blood supply, and will resorb away. Soft tissues will epithelialize faster than the bone will regenerate, and the remaining portion of the gum which formerly supported the tooth, also known as the ridge, will display a depression or defect. Loss of the bony architecture and its replacement by soft tissues, further complicates the prosthetic treatment plan. Indeed, in such a scenario, it is likely that a bone graft will be required. In other words, conventional crown and bridge prosthesis require bony support, and replacement of the tooth with an implant requires healthy surrounding bone. Often, it is necessary to do a separate preliminary surgery (Guided Bone Regeneration) to repair a defect before an implant is placed.
While instruments capable of the cutting the PDL are known to be used in connection with the extraction of teeth, such instruments fail to have the range and configuration necessary to effectively perform this function. In addition, such prior art instruments are clumsy to work with and have limited functionality in connection with such cutting, because they are often too thick, or improperly angled.
SUMMARY OF THE INVENTION
It is an object of the invention to remedy the deficiencies of the prior art heretofore discussed.
It is a further object of the invention to provide an instrument which allows the separation of the ligamental attachment without destroying the buccal plate.
It is a further object of the invention to provide an instrument with two functional tools which function synergistically to allow the user to separate the ligamental attachment and allow teeth to escape the bone occlusally.
It is a further object of the invention to provide a method which allows the separation of the ligamental attachment while minimizing damage to the buccal plate.
The invention is directed to a dental instrument, namely a periotome. The inventive instrument is of particular value because it also comprises a handle having two tools. At one end there is a tool with a thin, flexible, angled blade for insertion to separate the gingival attachment and enter the PDL space. The angulation and length are suited to circumscribe the entire circumference of the root structure, all the way to the root apices. At the other end of the inventive periotome there is a second tool which comprises a larger, spatula-shaped member tapering into a triangular tipped blade having a size and thickness adapted to create space for the introduction of extraction instruments in a controlled manner, after the cutting out the PDL, and at locations dictated by the surgeon. The preservation of bone eliminates the need for follow-up repair of the ridge, simplifying the prosthetic treatment plan. In other words, the invention addresses the inefficiency of destroying the fibrous attachment by tearing apart the periodontal ligaments. Rather, in accordance with the invention, the ligaments are incised, with substantially no trauma to the surrounding bone. The handle is preferably made of hollow stainless steel, aluminum alloy or other lightweight material which makes it comfortable and easy to control.
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Mueller, “Ginival Peritomy”, Dental Cosmos, p. 1037, 1923.
Handal & Morofsky
Karl Schumacher Dental Instrument Company, Inc.
Manahan Todd #E.
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