Vital pulp therapy

Details Vital pulp therapy Vital pulp therapy

2000-07-24

2001-11-20

Wilson, John J. (Department: 3732)

Dentistry

Method or material for testing, treating, restoring, or...

Endodontic

Reexamination Certificate

active

06319007

ABSTRACT:

FIELD OF THE INVENTION
The present invention is directed to methods and apparatus for providing hemostasis of dental pulp. In particular, the present invention is directed to electrosurgical methods and apparatus which provide durable hemostasis to exposed dental pulp with little or no damage to the pulp.
A. The Anatomy of the Tooth
Teeth, both primary and permanent, consist of outer enamel, an inner layer of dentin, and a soft tissue component referred to as the dental pulp. The pulp is enclosed by dentin, is continuous with soft tissue in the tooth socket, begins at the tip of the root, traverses through each root and terminates in the pulp chamber of the coronal or visible portion of the tooth. Initially, the dental pulp is responsible for the development of the enamel and dentin and later continues to provide the blood supply, nerve innervation and lymphatic drainage. The pulp responds to insult by depositing reparative and secondary dentin to protect the pulp and initiates an inflammatory process to combat bacterial infection.
B. Injury to the Pulp
The tooth and pulp are typically threatened in a variety of ways: (1) fracture of the tooth exposing the pulp to bacteria normally present in the oral cavity; (2) dental caries (decay) which decalcifies enamel and dentin, exposes the pulp and allows ingress of bacteria and bacterial products, (3) dental restorative procedures which may inadvertently expose the pulp; and (4) failure of dental restorations through fracture or leakage, including microleakage, allowing bacteria or bacterial by-products to reach the pulp. For decades many factors have been blamed for causing inflammation and necrosis (i.e. non-vitality, death) of the dental pulp, including: (1) dental caries and associated bacteria being the most prominent; (2) fracture and exposure to bacteria; (3) excess heat from dental instrumentation; and (4) toxicity of dental materials. More recently, bacterial invasion via microleakage has been attributed as an important cause of pulpal inflammation and necrosis.
Traditionally, when a small exposure of the pulp occurred mechanically, by fracture of the tooth, or while excavating caries, the exposure was promptly ‘capped’ with various dental materials in an attempt to prevent inflammation or necrosis of the pulp. If the exposure was small and capping occurred immediately and with a suitable material, pulpal necrosis could be averted. However, if the exposure was moderate or large in size, or if capping occurred after bacteria developed a foothold, or if the capping material deteriorated leading to microleakage, then inflammation or necrosis would typically occur. Materials (e.g. calcium hydroxide) which stimulated reparative dentin formation were used for capping of the pulp for over half a century in an attempt to stimulate health and to restore the pulpal wall naturally via slow deposition of reparative dentin.
C. Treatment Methods for Exposed Pulp
If the pulp progressed to necrosis, only two options were available to the patient: (1) extraction of the tooth; or (2) extirpation of the necrotic pulp and filling of the pulpal space with a suitable material to prevent microleakage via the pulp space to the surrounding bone. This second alternative is referred to as endodontic therapy (root canal treatment). Inflamed vital dental pulps, however, represent a substantial portion of infected pulps. Additionally, pulps exposed intentionally for therapeutic purposes (e.g. to support a denture) also constitute a significant portion. These latter two groups are currently relegated to extraction or endodontic therapy despite their vitality. Inflamed but vital pulps are considered, under current clinical guidelines, to be untreatable. Even teeth with relatively mild symptoms are diagnosed as ‘irreversible pulpitis’ and condemned to extraction or endodontic therapy.
Over the past seven decades, the research primarily centered around the stimulation of reparative dentin deposition and pulp therapy was limited to small exposures on asymptomatic teeth. A few reported exceptions involved more aggressive pulp therapy but was limited to adolescent and young adult patients. Several developments in the field opened the possibility of more comprehensive pulp therapy. These included: (1) The realization that most pulpal inflammation is due to bacteria invasion and bacterial by-products occurring via microleakage and less due to toxicity of dental materials; and (2) The development of materials that adhere to dentin and which can produce a seal to prevent microleakage (i.e. dentin adhesion products and the ability to create a hybrid layer consisting of collagen and resin). The ability to stimulate the deposition of reparative dentin became a standard for demonstrating re-organization and healing of the pulp after an insult. Despite these developments, only teeth with small exposures or mild clinical symptoms were routinely treated while the great majority of teeth exhibiting pulpal inflammation or periapical inflammation (inflammation of a pulpal origin in the bone around the tip of the root) were treated with endodontic therapy or extraction of the tooth.
One of the obstacles in treating the pulp is the impact of bleeding on the formation of the pulp barrier (sealing of the pulp or the restoration of the missing pulpal wall). Bleeding during any surgical procedure can impact on the success of treatment ranging from (1) being a mere nuisance or compromising visibility to (2) creating a toxic reaction (as in neurosurgery). Bleeding around the retina during eye surgery, for example, is an important concern. In pulp therapy, bleeding compromises visibility, jeopardizes the dentin adhesion, and creates voids or tracts within the barrier material resulting in chronic irritation and failure of the pulp therapy. In a very common situation, pulp therapy cannot be instituted because the hemorrhaging cannot be controlled. In these cases, the teeth are relegated to endodontic therapy or extraction simply due to the uncontrolled bleeding. One might wonder why bleeding cannot be controlled in an exposure approximately 2-4 square mm in area and consisting of very small blood vessels when bleeding is routinely controlled in major surgical procedures where much larger vessels are involved. A good analogy can be made with ophthalmic surgery where even minor amounts of bleeding during the procedure can compromise the overall therapeutic effort. In pulp therapy, minor bleeding contaminates the surface of the dentin preventing adhesion of the pulp barrier and jeopardizing the valuable dentinal seal. Residual blood clots have been reported to prevent healing and even stimulate an inflammatory response by the release of chemotaxic components.
Another important dilemma is that the bleeding must be controlled with little or no injury to the remaining pulp tissue. Furthermore, hemostatic procedures and materials which do not impact on the highly technique-sensitive dentinal adhesion process must be selected. These two factors place severe restrictions on the ability to control bleeding. Furthermore, temporary hemostasis is not sufficient since numerous procedures are required to create the pulp barrier and final restoration—any of which can cause recurring bleeding at a critical moment. Therefore, durable hemostasis is required with minimal or no injury (especially lasting injury) to the pulp. The present invention provides methods and apparatus which satisfy the need in the art for durable hemostasis.
Reported Developments
Most efforts in controlling bleeding of the pulp involved application of a cotton pellet and light pressure until hemorrhaging ceased. This proved fairly effective with very small exposures but was ineffective with larger exposures or hyperemic pulps. Over the past century, pulpotomy procedures were quite common upon exposure of the pulp. Pulpotomy procedures typically remove the chamber portion of the pulp (the part of the pulp enclosed by the clinical crown, the visible portion of the tooth, as opposed to the pulp tissue contained within the root por

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