The most common clinical signs present in a tooth with a necrosed pulp would be a grey discoloration of the crown and/or periapical radiolucency.
[2] Sequelae of a necrotic pulp include acute apical periodontitis, dental abscess or radicular cyst and discolouration of the tooth.
[citation needed] The dental pulp is located in the centre of a tooth, made up of living connective tissue and cells.
[3] It is surrounded by a rigid, hard and dense layer of dentine[3] which limits the ability of the pulp to tolerate excessive build up of fluid.
[4] The rise in pressure is commonly associated with an inflammatory exudate causing local collapse of the venous part of microcirculation.
[5] Further stages of destruction of pulp necrosis often leads to periapical pathosis, causing bone resorption (visible on radiographs) following bacterial invasion.
These inflammatory mediators include histamine, bradykinin, serotonin, interleukins (IL) and metabolites of arachidonic acid.
Once this tissue damaging process reaches the pulp it results in irreversible changes – necrosis and pulpal infection.
Furthermore, if the tooth is severely damaged, it could lead to inflammation of the apical periodontal ligament, and subsequently pulp necrosis.
[11] Pulpal necrosis can also occur as a result of dental treatments such as iatrogenic damage due to overzealous crown preparation – this may be due to excessive thermal insult and close proximity to the pulp during tooth preparation – or rapid orthodontic work causing excessive force.
In some cases, the pain presents as a long dull ache as this is due to necrosis of the apical nerves being the last part of the pulp to necrose.
[16] Teeth with said discolouration need to be treated with special care and further investigations are required before pulp necrosis can be diagnosed.
The diagnosis of pulp necrosis can be based on the following observations: negative vitality, a periapical radiolucency, a grey tooth discoloration and even peri-apical lesions.
The clinical study done by Gopikrishna indicated the tooth to be diagnosed as having necrotic pulp if subjects felt no sensation after two 15-second applications every two minutes.
[21] This method involves taking measurements of blood oxygen saturation levels, making it non-invasive and an objective way to record patient response regarding pulpal diagnosis.
[22] For the purposes of evaluating pulp vitality, it is imperative that the probes fit the anatomical contours and shape of the measured teeth.
[20] Another critically appraised topic[24] also suggests that a pulse oximeter is more accurate than cold testing in diagnosing pulp necrosis, however comments raised regarding the validity of the evidence stated that the pulse oximeter adaptors were built by the respective authors causing some degree of bias in the experiments.
[24] MRI scans have been used to detect and evaluate several head and neck regions including the Temporomandibular Joint, salivary glands, floor of the mouth, etc.
In the clinical study completed by Alexandre T. Assaf, MRI scans were used to detect pulp vitality after trauma in children.
In this study, MRI scans prove to be a promising tool to avoid excessive root treatment on traumatized teeth.
A systematic review conducted by Kahler, et al. (2017) showed similar clinical outcomes for teeth treated with REPs versus calcium hydroxide apexification/MTA apical barrier technique.
They did state that a thorough discussion with the patient would be necessary as teeth treated with REP's can show variable root maturation and adverse outcomes.