Apical periodontitis occurs after irreversible pulpitis. After pulp necrosis, bacteria invade the pulp space. There are no white blood cells from a vital pulp for protection and no hydrostatic pressure from the dentinal fluid which is thought to prevent bacteria travelling down dentinal tubules into the pulp.
The bacteria and toxins can only be contained for so long inside the pulp but then as the numbers increase/multiply, eventually this causes an inflammatory reaction of the periodontal ligament at the apex of the tooth. This is known as periapical periodontitis or apical periodontitis.
The progression of periapical periodontitis depends on the different paths that bacteria take and this depends on the ability/strength of host defence, the virulence of the microorganisms and the quantity of the microorganisms.
Initially only toxins ( from the infected pilp) cause periapical periodontitis but eventual infection at the apex of the tooth does arise and results either in an abscess or cellulitis.
An abscess is a collection of pus and can cause soft tissue swelling. The amount of pus increases and causes pressure which causes perforation of the cortical plate. Clinically, this will be apparent as there will be a swelling in the buccal sulcus. This perforation can even reach the oral mucosa or the skin of the face or drain through the gingival sulcus via the PDL.
A Cellulitis is a diffuse erythematous swelling and infection spreads in the connective tissues along tissue planes. Unlike an abscess, it cannot be incised as it is not within a confined space so not much drainage occurs.
With periapical infections, the host still does not give up so easily and a chronic lesion can occur such as either a periapical granuloma, a discharging sinus or a cyst. Depending on the balance of host defences and the bacteria, a chronic lesion can interchange both ways with an acute lesion. So an acute lesion can become chronic and a chronic lesion can suddenly turn acute. The terms acute and chronic are usually used to describe the clinical situation.
The management of periapical infection is usually hampered with the patient being anxious and having an increased pain sensitivity.
Frequently, dentists will find it difficult to administer effective local anaesthesia.
In the lower jaw, an inferior dental the block will be more effective than a local infiltration but it must be remembered that inserting more volumes of local anaesthetic is not much point. If a patient has a “numb lip” indicating the inferior dental nerve block has worked but the patient is still feeling pain, then instead of inserting more ID blocks with greater quantities of anaesthetic, you should look elsewhere:
Using Articaine is the preferred anaesthetic in these acute cases and can even be surprisingly effective as a buccal infiltration only.
It is important however to avoid injecting in acutely inflamed tissue due to risk of spreading infection and in any case it will be painful.
Intra-ligamentary injections are extremely valuable in these situations. For this, a special syringe designed for this purpose is required such as a Paraject. A paraject syringe does not look like an ordinary syringe and therefore it is more amenable to nervous patients. The pressure that can be attained using a Paraject is much greater and easier to develop than an ordinary anaesthetic syringe. The technique of using the Paroject does require using the extra short needle and some Parajects do not accept 2.2 ml cartridges but 2ml cartridges only. It is also important to have suction present so that the patient does not swallow any excess local anaesthetic fluid which oozes out during administration of the injection but which will not be harmful however it tastes very bitter. The final thing to remember when using a project is not to be tempted to use excessive pressure. Excessive pressure can damage the periodontal ligament that causes pain afterwards even though the PDL does recover.
Evidence also shows that a preoperative course of nonsteroidal anti-inflammatory medication such as 400 to 800 mg of Ibuprofen and taken an hour before the appointment also definitely helps.
In a few occasional cases, the procedure is abandoned and the patient book back in. This tends to happen when the patient is becoming increasingly nervous or the dentist is running out of time.
In the case of reversible pulpitis, the pulp will recover after removal of the stimulus which is caries.
However in irreversible pulpitis, the dental pulp is severely inflamed and damaged beyond recovery.
Treatment for reversible pulpitis involves pulp capping which may be direct or indirect. Antibiotics are not much of use here as the antibiotics in the blood cannot reach with significant quantities into the pulp.
The Localised antibiotic and a corticosteroid medicament in the form of Ledermix is extremely useful due to its multiple properties.
Ledermix is also extremely useful when you are going to carry out a root canal treatment anyway but you want to be able to calm down the patient’s symptoms first.
Apical periodontitis is the inflammation of the periapical tissues. At first, it only responds to the toxins produced by bacteria inside the pulp.
However, bacteria within the pulp does eventually infiltrate into the periapical tissues.
An abscess can therefore form as bacteria multiply and the host cannot deal with it and then which has to be treated through drainage and/or incision.
Antibiotics are useful here in order to use prevent the infection from spreading.
If the infection spreads into the surrounding tissues this causes clinical symptoms of pain, facial swelling, swelling of the lymph nodes, pain on swallowing and an increased temperature.
Here, antibiotics are required. The choice of antibiotic and dosage and duration is somewhat clinician -dependent.
The perio-endo lesion is one where the infection from the periapical periodontitis drains through the periodontal ligament into the gingival sulcus. Initially, the dentist may think that it is a periodontal infection due to the periodontal pocket that has formed.
Pulpitis leading to a Periapical periodontitis
Pulpitis causes inflammation and a rise in the intra-pulpal pressure which strangulates the blood vessels causing death of the pulp.
The necrotic pulp becomes infected as there are no white blood cells.
The bacteria within the pulp space release toxins which cause the periapical tissues to become inflamed.
On a periapical radiograph this is characterised by the loss of lamina dura and widening of the periodontal ligament space.
The results of periapical periodontitis can be
an acute periapical abcess or a chronic periapical abscess, cellulitis, cyst or a granuloma.
A useful mnemonic is “ acute caries causes continuing grief.”
A granuloma contains granulation tissue. The granulation tissue forms as a chronic inflammatory response.
An area circumcised by dense sclerotic bone appears as the host tries to put up a defence.
With chronic lesions, root resorption can also occur.
A cyst contains epithelial rests of Malassez located in the periodontal tissue and is stimulated by the immunological response to proliferate.
The Periapical abscess.
A periapical abscess is a collection of pus formed by pyogenic bacteria. The anatomical constraints cause a pressure build up in the limited periodontal ligament space. As the pus continues to accumulate and pressure increases, eventually the cortical plate is perforated.
Histologically a periapical periodontitis is classified as an abscess, granuloma or cyst.