Apicoectomy (root-end surgery): who is it for, and how successful is it?

The aim of root canal treatment is to clean out the bacteria inside the tooth and fill the canal so that it is sealed. When the treatment does not work, inflammation continues in the bone around the root tip (apical periodontitis): the tooth hurts when you bite, a discharging bump appears on the gum, or the dark area at the root tip on the X-ray does not get smaller. The American Association of Endodontists (AAE) describes two routes in this situation: reopening the canal from above and cleaning it (root canal retreatment), or reaching the root tip directly through the gum (apicoectomy).

In the AAE's publication for dentists, the situations in which root-end surgery comes to the fore are listed as follows: a lesion at the root tip that persists even though the root canal treatment was done properly; a tooth with a large post and a completed crown, especially upper front teeth; calcified canals that cannot be opened from above; an instrument that has broken and remained in the apical half of the root; root filling material extruding beyond the root tip; sharp root curvatures that cannot be reached from above; and a previous root-end surgery done with the old technique that has failed.

What these situations have in common is this: reopening the canal from above either cannot reach the source of the problem or carries a risk of damaging the tooth. For example, the AAE writes that while trying to remove a broken instrument from above, the dentine that supports the root can be worn away, and that this increases the risk of a vertical crack in the root that cannot be repaired. The AAE also lists teeth with a large post and a completed crown among the situations where surgery comes to the fore. In these situations, root-end surgery reaches the site of the problem directly, leaving the crown and post in place.

Today's root-end surgery is different from the procedure done with the old technique. In the old technique, a large window was opened in the bone, the root tip was cut at an angle and amalgam was placed in the root tip. In the modern technique (endodontic microsurgery), the procedure is done under a microscope through a small bone window about 3 to 4 mm across; the last 3 mm of the root is cut off, and the end of the canal is prepared to a depth of 3 mm with ultrasonic tips and filled with a biocompatible material (usually MTA). The AAE reports that cutting 3 mm off the root tip removes 98% of the branches at the root tip and 93% of the lateral canals.

This difference in technique is reflected directly in success. In a 2010 meta-analysis, the pooled success rate was 59% for root-end surgery done with the old technique and 94% for microsurgery. In an updated meta-analysis from 2013, success with the modern technique was 89% after 1 year; using a microscope or endoscope was associated with better results than magnifying loupes, and MTA with better results than other root-end filling materials. That is why it makes sense to ask your dentist whether they do the procedure with a microscope and which material they will place in the root tip.

The long-term picture is more cautious. In a study following 191 teeth in Switzerland, the healing rate was 83.8% at 1 year but fell to 75.9% at 5 years; in other words, some of the success was lost over time. Two factors stood out in the same study: the bone level at the sides of the tooth (if bone loss exceeded 3 mm, healing fell to 52.9%) and the root-end filling material (86.4% with MTA, 67.3% with SuperEBA). In a cohort of 309 teeth followed for 10 to 17.5 years in South Korea, 80.5% of teeth were still in the mouth after 10 years, while the proportion of teeth meeting the criterion for complete success was 63.4%.

In the Korean study, the factors determining the long-term outcome were the type of tooth, its mobility, the size of the lesion before surgery, the ratio of crown to root length, and whether there was a full crown on the tooth during follow-up. A 2020 review also listed smoking, the position and type of tooth, dentine defects such as cracks in the root, the bone level between the teeth and the root-end filling material as factors affecting the outcome. Because the root is shortened after surgery, the balance of the crown-to-root ratio becomes particularly important in teeth whose bone support is already reduced.

The evidence comparing it with retreatment is limited. The 2016 Cochrane review writes that neither method has a clear advantage over the other for healing at 1, 4 and 10 years of follow-up, but that the evidence is of very low quality. In the same review, markedly more people in the group that had surgery reported pain in the first week. No evidence was found that preventive antibiotics reduce infection after surgery.

The breakdown below becomes clear after a clinical examination, an X-ray and often a three-dimensional CBCT scan. The situations in the second list do not mean that the tooth will definitely be lost, but that the prospects for surgery are lower.

The steps below are the general course of modern root-end surgery done with a microscope. The details vary with the position of the tooth and the dentist's technique.

1. 1

   Planning and imaging

   The dentist looks at the quality of the tooth's root canal treatment, the size of the lesion at the root tip, the bone level and nearby structures. In the lower jaw, the jaw nerve and the exit point of the nerve that gives feeling to the lip, and in the upper jaw the sinus cavity, may be close to the root tips; that is why a three-dimensional CBCT scan is often requested.

2. 2

   Anaesthetic and lifting the gum

   The procedure is done under local anaesthetic. The gum is lifted through a small incision so as to expose the bone over the root tip. According to the Cochrane review, the type of gum incision can affect whether the triangle of gum between the teeth (the papilla) is preserved.

3. 3

   The bone window and cleaning out the inflamed tissue

   A small window about 3 to 4 mm across is opened in the bone over the root tip. The inflamed tissue surrounding the root tip is cleaned out; if needed, it is sent to pathology for examination.

4. 4

   Cutting off and examining the root tip

   The last 3 mm of the root is cut off straight or with a very slight bevel. The cut root surface is examined under the microscope; a missed canal, a connection between canals or a crack can be seen here.

5. 5

   Preparing and filling the root tip

   The end of the canal is prepared to a depth of about 3 mm with ultrasonic tips and filled with a biocompatible material, usually MTA. In one study in the Cochrane review, placing MTA in the root tip was associated with better healing at 1 year than only smoothing the old root filling.

6. 6

   Stitches and follow-up

   The gum is laid back in place and closed with fine stitches. The dentist tells you when the stitches will be removed and gives the schedule for check-up X-rays. Healing of the bone takes months, and the result is assessed with a check-up X-ray.

For a tooth where root canal treatment has failed, the options are usually retreatment, root-end surgery and extraction. Which is tried first is determined by the structure of the tooth and its bone support.

Root-end surgery is a minor surgical procedure, but like every surgical procedure it has risks. It will help you to discuss the points below with your dentist beforehand.

Healing has two layers: the gum and soft tissue recover within a few days, while healing of the bone at the root tip takes months. The care instructions your dentist gives you take priority.

1. The first few days

   There may be pain, swelling and sometimes bruising; in the Cochrane data, pain in the first week was more frequent with surgery than with retreatment. Take the painkiller your dentist recommends, apply cold to the outside of the area on the first day, and do not disturb the stitches with your tongue or fingers.

2. The first week

   Choose soft food, try not to chew on the side of the surgery, and clean the area gently as your dentist describes. The stitches are removed during this period or on the date your dentist gives.

3. The first few months

   The bone cavity at the root tip gradually fills in. Even if the tooth is comfortable during this period, the real indicator of healing is the check-up X-ray.

4. 1 year and beyond

   Most studies first assess the outcome at 1 year; the Swiss study showed that at 5 years some teeth had moved back into the not-healed group. Keep up check-ups at the interval your dentist recommends, and make sure there is a sound crown on the tooth.

We do not give figures here, because the scope varies greatly with the position of the tooth and the difficulty of the surgery. The items that determine the price are:

Position of the tooth and number of roots

Reaching a single-rooted front tooth is much easier than reaching a multi-rooted molar close to the sinus or a nerve.

Imaging

Whether a three-dimensional CBCT scan is needed affects the total.

Technique and material

Use of a microscope and the root-end filling material (for example MTA) are items linked both to success and to cost.

Bone graft or additional procedures

If a graft or membrane needs to be placed in the bone cavity with a large lesion, the scope widens.

The next step if it fails

If the surgery does not work, extraction and an implant or bridge in its place may come up; make the decision taking this possibility into account too.