Modern methods, microsurgery

Surgery should be a last resort to treat apical periodontitis, but new techniques are producing very good results

Periradicular surgery is an advanced endodontic procedure that aims to treat apical periodontitis. Over the past two decades, periradicular surgery has been transformed by newer techniques, equipment and materials. This has improved the delivery of the procedure and the outcome of treatment. This paper reviews the recent advancements in periradicular surgery.

Apical periodontitis should be treated, when possible, by root canal treatment or retreatment. Periradicular surgery should only be performed in cases with apical periodontitis when non-surgical means are not feasible. Indications for periradicular surgery include:

  • Suspected root fracture which cannot be confirmed without investigation
  • Suspected cyst or sinister lesion which requires biopsy
  • Dismantling a post may damage the remaining tooth structure
  • Persistent disease associated with a good-quality┬ároot canal treatment which cannot be improved by root canal retreatment
  • Intracanal blockage which cannot be retrieved or bypassed e.g. fractured instrument or ledge
  • Perforation which cannot be repaired from within the root canal
  • Root resorption which cannot be managed from within the root canal e.g. external cervical resorption.

Heroic dentistry does no favours for the patient or the clinician. Careful case selection is important to ensure a favourable treatment outcome. Periradicular surgery should not be performed if there is inadequate mouth opening, an inaccessible root, inadequate supporting bone, the restorability of the tooth is questionable, or medical contraindications. In cases deemed to be appropriate for periradicular surgery, valid consent is a prerequisite, including a discussion of the risks involved and alternative treatment options. It should be noted that the widely used term “apicectomy”, literally meaning “cutting off the tip”, does not fully describe the procedure and it is preferable to use “periradicular surgery”.

Preoperative
Preoperatively, patients should be given oral hygiene instruction, including chlorhexidine rinsing, and smoking cessation advice (Duncan & Pitt Ford 2006). This will help to prevent postoperative complications.

Intraoperative
Magnification
Magnification devices, such as dental loupes, dental operating microscopes and endoscopes improve visualisation of the operating site. Without magnification, it would be difficult to see an accessory canal foramen or certain root fractures. Magnification devices should be used with lighting that is in the same plane as the clinician’s vision and a front surface mirror to prevent secondary reflections.

Flap incision, reflection and retraction
Patients now expect to retain good aesthetics after surgery. Contemporary flap management can reduce the risks of severe scarring, gingival recession and loss of interdental papilla. Good soft tissue healing can be achieved by using microblades (Fig. 1) for incisions and using a minimally traumatic technique for reflection and retraction.

There are many different designs of flaps and these can be quite confusing. Flaps can be classified by where the horizontal incision is made and whether there are one or two relieving incisions. A marginal flap has the horizontal incision in the gingival sulcus and, traditionally, the interdental papillae are included in the flap. This usually provides good surgical access; however, gingival recession and loss of interdental papilla may occur postoperatively.

A contemporary marginal flap places the incision in the papilla base (Fig. 2a) to give recession-free healing of the interdental papilla (Fig. 2b) (Velvart 2002).

A sub-marginal flap with a horizontal incision placed in sulcular mucosa (semilunar flap) should be avoided as access will be inadequate and there will be severe scarring. A sub-marginal flap with a scalloped horizontal incision placed in the attached gingiva (Luebke-Ochsenbein flap) reduces the risk of gingival recession and exposure of crown margins. Scarring can be minimised by using microsurgical techniques (Figs. 3a, b, c). This flap should only be performed when there is at least 3-4 mm of attached gingiva and so it is usually limited to the maxillary anterior teeth.

Traditionally, flaps were broad based with diagonal relieving incisions, supposedly to maintain optimal blood flow to the flap. This is no longer advocated as diagonal incisions sever the vertically running blood vessels which supply the gingiva and mucosa. Contemporary flaps have vertical relieving incisions to minimise severing of these blood vessels and optimise soft tissue healing. For the same reason, incisions should be vertical when performing incision and draining of a dental abscess.

Curettage and biopsy
Curettage aims to remove diseased periradicular tissue and any overextended root filling material. It is not sufficient to perform curettage on its own when there is evidence of an intracanal or extracanal infection. Usually root-end management procedures follow curettage.

It is debateable if tissue specimens from every patient should be sent for biopsy. Histological examination should certainly be conducted if the lesion is suspected to be malignant.

Root-end resection
Root-end resection aims to remove microbes within the apical ramifications of the root canal. Traditionally, clinicians bevelled the root-end to give direct vision for root-end cavity preparation and filling. Bevelled resections are no longer encouraged as they expose a large number of dentinal tubules which may harbour microbes. Contemporary root-end resections should be perpendicular to the long axis of the root (Fig. 4). This minimises the number of exposed dentinal tubules and reduces the risk of microbes affecting the periradicular tissues. The root-end may be drilled through at a predetermined level or shaved off in increments until this level is reached. It is recommended that at least 3 mm be resected as most apical ramifications are within this region. Root-end resection may be performed using a surgical high-speed handpiece. This is subject to the air being expelled through the rear of the handpiece and away from the operating site thus reducing the chance of surgical emphysema. These surgical handpieces also have an angled head, giving optimal visibility of the operating site.

Root-end preparation
Root-end preparation aims to clean the apical portion of the root canal and create a space suitable for a filling to be placed. It is no longer advisable to prepare the root-end cavity using a round bur. This carries a risk of causing iatrogenic errors such as transporting the root canal or perforation. In addition, these cavities rarely have any retentive form for a root-end filling. Contemporary root-end preparation is performed using ultrasonic retrotips. Root-end cavities prepared with ultrasonics are cleaner and respect the apical root canal anatomy when compared to those prepared with burs. Ultrasonic retrotips usually prepare a 3 mm cavity within the root canal but preparation of deeper cavities is possible. The root-end can be inspected throughout preparation using a micro-mirror (Fig. 5) under magnification.

Root-end filling
Root-end filling aims to provide an apical seal to prevent any microbes leaking into the periradicular tissues. There are a plethora of root-end filling materials available. It is now widely accepted that amalgam should not be used as a root-end filling material. Contemporary root-end filling materials include MTA (Mineral Trioxide Aggregate) and Intermediate Restorative Material (IRM) (Fig. 6). There is no significant difference between IRM and MTA in terms of healing of apical periodontitis (Chong et al. 2003).

MTA appears ideal as it has an excellent sealing ability and induces hard tissue barrier formation. Disadvantages of using MTA are it is relatively expensive compared to IRM and not as straightforward to handle or compact. Newer tricalcium silicate materials, such as BioDentine, have improved handling and may supersede MTA.

Sometimes it is not possible to prepare a root-end cavity (Fig. 7) and, in these cases, composite may be bonded to the root-end to achieve a good seal.

Management of resorption
In cases of external cervical resorption, trichloracetic acid may be applied repeatedly to the resorptive tissue followed by curettage (Figs. 8a and 8b). This has been recommended as the resulting coagulation necrosis will destroy the resorptive tissue and control bleeding (Heithersay 1999). Once all the resorptive tissue has been removed, the cavity can be restored (Figs. 9a and 9b).

Flap closure
The flap edges should be repositioned and compressed with dampened gauze for at least five minutes. This initial compression aids reapproximation and haemostasis. The flap can then be held in position using micro-sutures (Fig. 10). Further compression after suture placement will reduce the thickness of the blood clot and encourage healing by primary intention.

Postoperative
Postoperatively, patients should be reminded about the importance of good oral hygiene and smoking cessation. Non-absorbable sutures may be removed three days postoperatively by which time reattachment has occurred. If left any longer, the sutures may disappear under new epithelium making removal difficult for the clinician and unpleasant for the patient.

Patients should be reviewed clinically and radiographically to assess the outcome of periradicular surgery.

The European Society of Endodontology recommends that the outcome of surgery should be assessed after one year. Longer periods may be required if there is a persisting radiographic lesion.

Conclusion
Successful treatment can be achieved with periradicular surgery when using contemporary techniques, equipment and materials. The improved healing of soft tissues and periradicular bone ultimately leads to improved patient satisfaction.

Tips for carrying out successful contemporary periradicular surgery include:

  • Select cases wisely and do not perform surgery if a non-surgical approach is feasible
  • Make use of magnification and co-axial illumination
  • Think microsurgery: use microblades, micromirrors, microsutures
  • Use minimally traumatic techniques for soft tissue management
  • Use a biological approach to ensure infection is removed and reinfection is prevented: do not bevel the root-end, prepare and clean the root-end cavity with ultrasonics, and fill the root-end with a material that has a good sealing ability.

To see all the clinical photographs from this article, see our Facebook page: http://on.fb.me/l9qMNL.

Dr Justin Barnes is a specialist in endodontics at Cranmore, Belfast.


References

Duncan HF, Pitt Ford TR (2006). The potential association between smoking and endodontic disease. Int Endod J 39, 843-854.

Velvart P (2002). Papilla base incision: a new approach to recession-free healing of the interdental papilla after endodontic surgery. Int Endod J 35, 453-460.

Chong BS, Pitt Ford TR, Hudson MB (2003). A prospective clinical study of Mineral Trioxide Aggregate and IRM when used as root-end filling materials in endodontic surgery. Int Endod J 36, 520-526.

Heithersay GS (1999) Treatment of invasive cervical resorption: an analysis of results using topical application of trichloracetic acid, curettage, and restoration. Quintessence Int 30, 96-110.