Preformed mandibular splint

Dentistry – Method or material for testing – treating – restoring – or...

Reexamination Certificate

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C433S018000

Reexamination Certificate

active

06227861

ABSTRACT:

FIELD OF THE INVENTION
This invention relates to a dental appliance, and more particularly to a mandibular splint and method for alignment and stabilization of a fractured mandible.
DESCRIPTION OF THE PRIOR ART
Mandibular fractures have historically been one of the most difficult procedures for the reconstructive surgeon. The slightest damage to this complex structure causes disruption of the relationship between 32 teeth and 2 joints. The most minute operative error during mandibular repair will result in flagrant post-operative morbidities including headaches, TMJ arthralgias, chronic ear and jaw pain, sleepless nights, and anorexia. The principle used by reconstructive surgeons for proper mandibular reduction and repair is based upon the assumption that interdigitation of the maxillary and mandibular arches of teeth will serve to properly align the mandible in it's single, correct position. The mandible is fixed in this position using mandibulomaxillary fixation (MMF). The patient is left in MMF for an average of 6 weeks. This method of correcting mandibular fractures has long been the standard procedure despite it's many shortcomings.
Proper reduction and fixation is possible when the patient has an intact mandibular and maxillary arch of teeth. The patient's teeth serve as an accurate template; they interlock in only one proper position which is consistent and reproducible. However, when the patient does not have ideal dentition due to oral trauma, has prior dental extractions, or an edentulous arch, the surgeon must attempt to estimate the mandibular reduction using direct visualization and TMJ positioning alone. There exists no device in the prior art to aid the surgeon in reapproximation of the mandible.
In the patient whose mandible is fractured, it is extremely important that the mandible is properly aligned and stabilized for repair. Incorrect alignment can lead to morbidity and malocclusion. Repair of a fractured mandible involves two steps: realignient of the dislocated fragments and stabilization of the bone. The current technique for correcting mandibular fractures is to provide alignment and stabilization by interdigitation of the teeth. Prior art methods of mandibular fracture repair use interdigitation accomplished by wiring the mouth closed so that the mandible interacts with the maxilla to align and stabilize the mandible. Afler fracture stabilization, the patient's mouth is left wired shut for a period of six weeks.
This technique, however, has many drawbacks. In order to prepare the patient's mandible for fixation, the surgeon must first begin the long and arduous task of affixing arch bars to the teeth. This process alone takes several hours while the patient is under general anesthesia. Since the surgeon is relying on the patient's teeth as a template, those who are edentulous, or have damaged or missing teeth (which is commonly the case due to the inciting traumatic event) are unlikely to be aligned properly. Furthermore, there are serious problems with long-term fixation of the mandible to the maxilla such as discomfort of the patient, problems clearing oral and respiratory secretions which can lead to airway blockage, increased incidence of dental carries, weight loss, malnutrition, and increased risk of gingival infections and osteomyolitis of the mandible and maxilla. The most significant of the aforementioned complications is airway compromise. There have been a number of reported cases of patients who have died after mandibular wiring because they were unable to clear respiratory secretions or vomitus from their airway. Other deaths have been reported due to postoperative oropharyngeal swelling because of the patients' inability to open their mouths to breath adequately. Thus, there is a need for an accurate method of aligning and stabilizing a fractured mandible without requiring the interdigitation of teeth and the wiring shut of the mouth.
Various splints have been designed for dental use. Splint designs have been reviewed by Clark, Journal of the American Dental Association, 108:359-363 (1984); and Clark, Journal of the American Dental Association, 108:364-368 (1984). Methods of fabricating occlusal splints have also been described by Wright, Journal of the American Dental Association, 117:757-758 (1988). These splints typically cover the teeth of the lower dental arch and interdigitate with the teeth of the opposing upper arch. Such splints are manufactured by an indirect process in which the dentist takes an impression of the patient's teeth and makes a registration of the jaws in the desired therapeutic position. A splint is then indirectly manufactured in a laboratory from the impression and registration obtained by the dentist. The fabricated splint is typically returned to the dentist after a significant period of delay, and the splint is then placed in the patient's mouth. For instance, Summer U.S. Pat. No. 5,173,048 discloses a dental splint that covers the teeth of a lower dental arch and interdigitates with the teeth of a second dental arch to change the bite surface. These splints, however, are not useable for mandibular fractures, but only for other dental problems such as temporomandibular joint (TMJ) disorder. In addition, these splints require taking impressions of the teeth and thus are not quickly available, and are expensive due to the custom fitting that must be performed. Such splints must also rely on interdigitation of the teeth which is not of use in the edentulous patient. There are several significant disadvantages with this indirect fabrication technique. One serious drawback is that indirect fabrication usually requires at least several days to complete because the dentist must send the impression and registration to an outside laboratory. Unfortunately, patients with an injury are often in serious pain and need a splint immediately, particularly after a traumatic joint injury. Any period of delay in placing the finished splint in the patient's mouth can cause unbearable pain during the period of delay.
A further disadvantage with indirect fabrication methods is that they increase the cost of the dental splint. Making impressions and sending them to a laboratory for conversion into a splint is costly. It multiplies the fabrication steps and increases the number of parties involved in the manufacturing chain. The expense associated with these multiple steps sometimes makes the splint more expensive than a patient can afford or an insurer is willing to pay.
Another disadvantage with indirect fabrication is that it is inaccurate because the existing anatomy has been fractured and the mold is therefore of a configuration which is not correct. Bite registration must be very precise to be acceptable and helpful to patients. Unfortunately, a therapeutic bite constructed indirectly in the laboratory seldom fits perfectly in the patient's mouth. The indirectly fabricated splint must be adjusted by the dentist with the patient present. Such adjustments further increase the manufacturing expense and often result in a bite surface which is still not entirely accurate.
Thus, there is a need for a dental splint which may be used for the repair of mandibular fractures, that does not require an impression and can be used on a wide variety of patients, does not require interdigitation of the teeth, and is sufficiently uniform to be readily available in an emergency.
Other prior art methods of fixation consist of a splint of a shape to correspond with the lower jaw, and sufficiently rigid to keep the parts of the fractured bone in place and a head piece formed to fit the top of the head, and serve as a support to the splint; the two parts being connected together by straps, so that the splint will be held in place by the head piece.
Other fracture appliances and bandages for fractures of the maxillary bones have sleeves, a chin cup, means adjustably securing said cup to the sleeves, a head piece extending over the head means securing said sleeves to said head piece at a point co

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