Pulpitis is inflammation of dental pulp tissue. The pulp contains the blood vessels, the nerves, and connective tissue inside a tooth and provides the tooth's blood and nutrients. Pulpitis is mainly caused by bacterial infection which itself is a secondary development of caries (tooth decay). It manifests itself in the form of a toothache.
Signs and symptoms
Increased sensitivity to stimuli, specifically hot and cold, is a common symptom of pulpitis. A prolonged throbbing pain may be associated with the disease. However, pulpitis can also occur without any pain.
Reversible pulpitis is characterised by intermittent, brief discomfort initiated by a hot, cold or sweet stimulus. The pain evoked is of short duration and there is no lingering or spontaneous pain. The pain ceases within a short period after removal of the stimulus. With a reversible pulpitis, sleep is usually not affected and no analgesics are necessary. Usually, no atypical change is evident on the radiograph. Pulp vitality tests are positive and it is possible to preserve a healthy vital pulp.
Irreversible pulpitis, in contrast, is characterised by a constant severe pain that arises without provocation. Characteristics may include sharp pain upon thermal stimulus, lingering thermal pain, spontaneity, and referred pain. Sometimes, the pain may be accentuated by postural changes such as lying down or bending over. If a stimulus is applied, the pain persists for minutes or hours after removal of the stimulus. Sleep may be disturbed and over-the-counter painkillers are often taken in an attempt to provide relief, but are usually ineffective.
Causes
Pulpitis may be caused by bacteria from dental caries that penetrate through the enamel and dentin to reach the pulp, or it may be mechanical, a result of trauma, such as physical damage to the tooth.
Inflammation is commonly associated with a bacterial infection but can also be due to other insults such as repetitive trauma or in rare cases periodontitis. The inflammation of dental pulp is mainly caused by an opportunistic infection of the pulp by a commensal oral microorganism. To reach the pulp, the most common route of the microorganism is through dental caries as well as from trauma, dentinal cracks and exposed dentin. Exposed dentin gives the microorganisms access to the pulp of the tooth through the dentinal tubules. In the case of penetrating decay, the pulp chamber is no longer sealed off from the environment of the oral cavity.
When the pulp becomes inflamed, pressure begins to build up in the pulp cavity, exerting pressure on the nerve of the tooth and the surrounding tissues. Pressure from inflammation can cause mild to extreme pain, depending upon the severity of the inflammation and the body's response. Unlike other parts of the body where pressure can dissipate through the surrounding soft tissues, the pulp cavity is very different. It is surrounded by dentin, a hard tissue that does not allow for pressure dissipation, so increased blood flow, a hallmark of inflammation, will cause pain.
The infection can also come from the apical foramen of the root. Cells in the dental pulp trigger an immune response from the invasion of foreign microorganisms. The inflammation of the pulp is a side effect of the immune response and causes pain.
Pulpitis can often create so much pressure on the tooth nerve that the individual will have trouble locating the source of the pain, confusing it with neighboring teeth, called referred pain. The pulp cavity inherently provides the body with an immune system response challenge, which makes it very difficult for a bacterial infection to be eliminated.
If the teeth are denervated, this can lead to irreversible pulpitis, depending on the area, rate of infection, and length of injury. This is why people who have lost their dental innervation have a reduced healing ability and increased rate of tooth injury. Thus, as people age, their gradual loss of innervation leads to pulpitis.
Innate immunity in the pulp is not specific but uses receptors to recognize molecular patterns common to microbes to initiate bacterial killing (phagocytosis). The components of the innate response of the dentin/pulp complex to caries include at least the following six: (1) outward flow of dentinal fluid; (2) odontoblasts; (3) neuropeptides and neurogenic inflammation; (4) innate immune cells, including immature dendritic cells (DCs), natural killer (NK) cells, and T cells, as well as (5) their cytokines and (6) chemokines. Although the first two items are not classic components of innate immunity, they are uniquely involved in the initial inflammatory response to caries.
A variety of cytokines have been observed in the pulp. Patients with symptomatic and asymptomatic irreversible pulpitis have been shown to have an almost 23-fold increase in the cytokine IL-8 in the pulp. Cytokines in the pulp interact with each other. The ultimate effect on pulpal inflammation and healing is dependent upon the integrated actions of these inflammatory mediators.
In addition to the lymphocytes, macrophages also provide defense against certain intracellular pathogens. Activated macrophages can function as class II antigen-presenting cells, similar to pulpal dendritic and B cells. In addition, activated macrophages secrete many inflammatory mediators.
Macrophages in the pulp become activated after receiving two signals. The first is a priming stimulus and the second is an activating signal. The priming stimulus is secreted by activated T-helper cells. The activating stimulus may include bacterial lipopolysaccharides, muramyl dipeptide, and other chemical mediators. According to neuronal studies, 70-80% of pulpal axons are unmyelinated. Highly myelinated Aδ-fibers, which allow for fast conduction, are responsible for the sharp, shooting pain.
The pain mechanisms associated with pulpitis are similar to those of the rest of the body (i.e. receptors, intracellular signaling, transmitters, etc.). The inflammatory mediators act on specific receptors relating to nociceptive neurons, leading to the production of second messengers and activation of phospholipases and protein kinases. The second messengers regulate receptors ion channels that deal with sensitization. The ion channels open based on pain stimuli propagating action potentials in sensory neurons.
In order for excitability and conduction to occur, voltage-gated sodium channels must be activated. Changes in sodium channel (NaCH) expression occur after inflammatory lesions, which may generate different pain states seen when neuronal fibers are activated. Studies have been done on major NaCh isoforms to examine expression patterns. Nav1.6 nodal accumulations do not vary in size or immunofluorescence staining activity in typical or atypical nodal sites; however, the proportion of typical nodal sites decreases and increase in atypical nodes in painful tooth samples compared to normal tooth samples. Nav1.7 has an increased expression in typical and atypical nodal sites in painful samples. As a result, an increased co-expression of multiple isoforms at demyelinating nodal sites in painful dental pulp. This isoforms of sodium channels may be a main factor in pain sensations due to their production of axonal excitability properties.
Neuropeptides are increasingly being researched for having a role in molecular mechanisms involved with pain, including ion channels and inflammation. Substance P (SP) is a neuropeptide produced by capsaicin neuron cell bodies (localized in trigeminal ganglia and dorsal root) and plays a major role in dental pain and inflammation. Other peptides include cGRP, galanin, somatostatin, and neurokinin A-B. The biological effects of SP are expressed by the binding of specific G protein-coupled NK receptors. Interaction with SP receptors induces vasodilation and allows for plasma extravasation and mastocyte degranulation. SP is highly expressed in dental pulp and dentin. When pain, thermal, and/or chemical stimulation is present, SP production and release increases. Current studies focus on whether controlling Substance P expression may control tooth pain.
Possible explanations for false-positives include:
- Response caused by conduction of the current because of periodontal or gingival issues
- Breakdown products associated with pulp necrosis may be able to conduct electric current next to infected and hypersensitive pulp tissue
- Inflamed pulp tissue may still be present
- Metallic restorations or orthodontic gear are still present
Studies have indicated that there is little correlation between histopathological status of the pulp and clinical information. A negative EPT response showed localized necrosis in 25.7% of cases and 72% of cases. Thus, 97.7% of cases with a negative response to EPT indicated that a root canal treatment should be carried out. water and touch. The pulp is still considered to be vital. This means that once the irritant is eliminated, usually by removal of decay and the placement of a restoration, that the pulp will return to its normal, healthy state. and local anesthetic may not work as well.
Irreversible
This is the condition where the pulp is irreversibly damaged. The pulp cannot recover from the insult and damage. For example, decay that has reached the pulp of the tooth introduces bacteria into the pulp. The pulp is still alive, but the introduction of bacteria into the pulp will not allow the pulp to heal and it will ultimately result in necrosis, or death, of the pulp tissue.
Clinical signs may include reduced response to electronic pulp testing and painful response to thermal stimuli.