The inflammation may be acute or chronic because just like other tissues in the body, the pulp will react to irritants with innate and/or adaptive immune responses.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.Odontoblasts, (the cells that form dentin) have cellular processes that extend into dentinal tubules and are the first to encounter the caries bacterial antigens. They express low levels of interleukin 8 (IL-8) and genes related to chemokines and chemokine receptors. The odontoblasts have been shown to attract immature dendritic cells.Dendritic cells (DCs) are a heterogeneous leukocyte (white blood cell) population. DCs in healthy peripheral tissues (steady state) are in an immature state. The cells are capable of sensing microbes as well as antigen capture and processing capabilities. A rapid accumulation of pulpal DCs has been observed beneath cavity preparations, and an increased number of DCs accumulated under caries.
There are 3 general types:

Thermal: Agents are applied to increase or decrease the temperature of a tooth and stimulate a pulp sensory response.Cold tests: Most commonly, ethyl chloride is sprayed onto a small ball of cotton wool and is applied to the tooth, which produces intense cold. Alternatively, CO2 snow and other refrigerants such as dichlorodifluoromethane (DDM) have been shown to be effective. Heat tests: Gutta percha can be heated and directly applied to the tooth to produce heat. Electrical pulp test: Electric pulp testing (EPT) has been available for over a century and is used by dentists worldwide. It is used to determine the health of the pulp and pulp-related pain.EPT is based on the stimulation of sensory nerves in the pulp. It does not provide information on vascular supply to the pulp. The probe tip of the test device is placed directly onto the tooth surface and an electrical stimulus is produced. This stimulus causes an ionic change across the neural membrane, inducing an action potential in the myelinated nerves. The threshold of pain is determined by increasing the voltage. A tingling sensation is felt once the voltage reaches the pain threshold. This threshold level varies between patients, and is affected by factors such as age, pain perception, tooth surface conduction and resistance. The requirements of an EPT are appropriate application method, careful interpretation of the results, and an appropriate stimulus. EPT must be done with tooth isolation and conduction media.