6 Surgical endodontics
Success rates for contemporary endodontic therapy are in excess of 90%, depending on the skill of the clinician and the teeth involved. Surgical endodontic procedures are usually undertaken when conventional (orthograde) endodontics has failed. However, the chances of successful retreatment of a tooth with a failed root filling are higher when non-surgical endodontics is repeated (wherever possible) rather than by undertaking a surgical approach. Surgical endodontics may therefore not be the first option when conventional root canal treatment fails.
Non-surgical endodontics attempts to eliminate the bacteria by cleaning and shaping the root canal to remove infected dentine, disinfecting the canal and sealing with a root filling. If non-surgical endodontics fails, it is usually because of the persistence of noxious substances (toxins and other by-products of bacteria) within the root canal system. If a root canal therapy fails and the tooth cannot be retreated, surgical endodontics may be indicated to eliminate the noxious substances from the root canal system. Where surgical endodontics is indicated, it is desirable that a root filling has been inserted first to improve the chances of success.
Surgical endodontics may be indicated in the management of a lateral root perforation or a horizontal fracture of the apical third of the root, root resorption or persistent periapical pathosis (e.g. inflammatory cyst or granuloma, or a periapical neoplasm).
Surgical endodontics is usually undertaken under local analgesia, with or without sedation. A patient with a pre-existing extensive inflammatory cyst might be more appropriately managed under general anaesthesia. Prerequisites for surgical endodontics are an experienced dental surgeon and trained assistant, a compliant patient who is medically fit and a range of suitable surgical instruments and root-end filling materials.
The aim of surgical endodontics is to restore the integrity of the supporting tissues of a tooth or teeth with chronic pulpal or periapical disease, where non-surgical endodontics has failed and retreatment cannot be undertaken or is contraindicated.
The principal objective of surgical endodontics is to enhance the lifespan of the tooth by removing causes of chronic periapical or periradicular inflammation. This is achieved by creating an effective seal of the root surface and thereby eradicating noxious substances present within the root canal of a tooth.
Apicectomy is the surgical removal of the apical portion of a tooth. To achieve this, access to the root apex is gained via a mucoperiosteal flap and then bone is removed around the root apex. The aim of apicectomy is to eradicate persistent infection in the periapical tissues.
A root-end filling is a restoration placed into the cut surface of the root after apicectomy of the root apex to occlude the root canal apically. The root-end filling requires a small cavity to be prepared in the root surface with a bur or ultrasonic instrument, and a suitable restorative material is placed in the cavity. The objective of placing a root-end filling is to achieve a satisfactory seal of the root surface.
Apicectomy may be undertaken alone but it is preferable wherever possible to place a root-end filling after apicectomy to improve the chances of gaining a satisfactory apical seal. These techniques may be performed in conjunction with the placement of an orthograde root filling at the time of surgery. This may be necessary if it has not been possible to disinfect the root canal during conventional endodontics and the patient has persistent periapical inflammation (the patient usually complains of pain and swelling that resolves only if the root filling is removed and the tooth is left on open drainage).
The signs and symptoms of chronic pulpal or periapical disease may persist after conventional endodontic treatment. The cause of endodontic failure is sometimes evident on radiographic examination. If it is feasible to retreat a tooth with a failed root filling via an orthograde (coronal) approach, then this should be attempted first. If retreatment by non-surgical endodontics is impracticable or is unlikely to have a successful outcome, then surgical endodontics may be indicated.
Rarely, local anatomical or pathological conditions are a contraindication for surgical endodontics—for example, proximity of the periapical tissues to the maxillary antrum or mental foramen may necessitate removal of the tooth. Psychological conditions might compromise the success of surgical endodontics (e.g. a pronounced gag reflex). Some medical conditions may contraindicate any outpatient oral surgery procedure in general dental practice. Examples include haemorrhagic disorders, previous radiotherapy to the face and jaws, unstable angina, a compromised immunological state (e.g. due to steroids for rheumatoid arthritis, or disease of the immune system). An emerging concern is the patient taking bisphosphonates, in whom there is a risk of osteonecrosis. However, the relative risk of osteonecrosis is uncertain at present. Other medical conditions may be relative contraindications to surgical endodontics—e.g. myocardial or valvular disease. Each case should be judged on its merits. If there is any doubt about the suitability of a patient for surgical treatment, then the patient should be referred to a specialist.
In the presence of an acute apical abscess, there may be erythema or swelling of the soft tissues at the apex of the affected tooth. The periapical soft tissues may be tender to palpate, and the tooth is likely to be tender to percussion. A sinus may be present on the buccal aspect of the affected tooth, although this is not always the case. Occasionally pus from a maxillary incisor may discharge through a pathological sinus into the floor of the nose. Pus from a maxillary premolar or molar may discharge into the maxillary antrum, or rarely, on to the face (see Ch. 7).
A periodontal examination should be undertaken. Healing of the periapical tissues may be compromised if there is coexisting periodontal disease, which may manifest as either horizontal or vertical bone loss around the tooth.
Radiographs demonstrate both anatomical and pathological features at the apex of the tooth (Fig. 6.4). A radiograph may demonstrate an incompletely sealed root canal, or bone loss around the apex of the tooth involved. If there is chronic apical disease, a lesion with the physical characteristics of a cyst may be identified at the apex of the tooth. Rarely, the cause of a failed root filling cannot be established through clinical or radiographic examination but it may become apparent when surgical endodontics is undertaken. For example, a root fracture not detectable clinically or radiographically may be identified on surgical exploration.
The operator should also consider the position of the apex of the tooth in a mesiodistal direction. If the apex of the tooth to be treated is inclined towards an adjacent tooth root, there is a risk of damaging the adjacent root structure.
For optimal results in general practice, surgical endodontics should be confined to the maxillary anterior sextant. Teeth more posteriorly placed pose clinical problems that diminish the chances of success, such as narrow or curved roots in mandibular incisors, or restricted access to the palatal root of maxillary premolars and molars. It may be difficult to seal a lateral root perforation because of restricted access. As experience is gained through graduate training, it becomes possible to undertake more demanding surgery.
Patients are referred for specialist care if the primary care clinician has inadequate experience to undertake the surgery, if there is any doubt about the patient’s medical history or if there are anatomical or pathological features that may complicate surgery. For example, there may be marked root curvature, or the apex of the root may be close to an anatomical structure such as the mental neurovascular bundle.
Extensive bone removal may at times be required to gain access to a retruded root apex, for example a proclined mandibular incisor. Errors in identifying the correct root apex might result in surgery being undertaken in an adjacent tooth root. Identification of the apex of the root can be difficult if a periapical bone defect is small.
Pathological conditions, such as a large (more than 1 cm in diameter) radiolucent lesion (e.g. cyst or granuloma) involving the apices of several teeth, may be difficult to treat under local analgesia; pain control may be inadequate due to the extent of the lesion. General anaesthesia is then considered.
Reported success rates for surgical endodontics vary between 0 and 90%, depending on the criteria for success and the presence of a conventional root filling. Incomplete sealing of root canals may contribute to failure, but the prognosis for successful retreatment is good if an unsealed root canal is identified. However, the success of surgical endodontics without a root filling present is less predictable.
The prognosis should be discussed with the patient preoperatively. However, no guarantee of a successful outcome should be given, because circumstances may change due to factors identified at the time of surgery, such as a root fracture.
Patients should be informed of pain, swelling and bruising of the face arising after surgery. Damage to adjacent teeth may occur through carelessness or difficulty in locating the apex of the tooth to be treated. This latter complication should be anticipated preoperatively. Contraction of the mucoperiosteal flap may occur through scarring as it heals, leading to unsightly recession around the gingival margin (Fig. 6.5). A judicious approach to flap design, reflection, retraction and careful/>