Stitch-free (flapless) implants: who are they suitable for, and what are the risks?

In conventional implant surgery, the gum is lifted together with the membrane covering the bone beneath it. This is called a flap. The surgeon can then see with their own eyes the width and shape of the bone and any hollows in it; they place the implant in the middle of the bone, add bone if needed and close the gum with stitches. In the flapless method, this flap is not lifted. A round piece the width of the implant is removed from the gum, or the drill goes straight through the gum, and the implant is placed into the bone through this opening. Stitches are often not needed; this is where the name 'stitch-free implant' comes from.

There is no visible difference in survival. A meta-analysis pooling 24 studies, 1,025 patients and 1,873 implants found no significant difference between the flapless and conventional methods in implant survival, bone loss or complication rate; mean follow-up was about 22 months. In an earlier meta-analysis of 12 studies, mean survival was 97.0% with the flapless method and 98.6% with the conventional method, and the difference was not statistically significant. These two results point in the same direction, but both have short follow-up, and long-term comparative data are still scarce.

The gain is measured on the patient's side. In a meta-analysis pooling randomised studies that compared computer-planned, fully guided flapless surgery with the conventional method, surgery in the flapless group was on average 24 minutes shorter, pain after surgery was about 17 points lower on a 100-millimetre scale, and less discomfort during surgery was reported too. For swelling, the direction also favours flapless surgery, but the certainty of that result is very low. In other words, the claim of 'less pain' is backed up; the claim of 'no pain' is not.

The price is the loss of sight. In a model study, even though CBCT images were available and the neighbouring teeth were in place, when the artificial gum on the model was removed, perforation of the bone wall was seen in 59.7% of the flapless placements done freehand and without a guide by 18 clinicians. This is a laboratory study and does not show the rate in real patients; but what it says is clear: the direction of an implant placed without seeing the bone strays more easily than the surgeon expects.

This is why flapless surgery today is largely discussed together with guided surgery. The CBCT scan and an intraoral scan are combined on the computer, the position of the implant is planned virtually and a surgical guide that sits in the mouth is produced according to this plan. The drill passes through the ring in the guide. In a meta-analysis, fully guided flapless placement shows less deviation than conventional freehand placement, particularly in angle; the mean difference is about 3.9 degrees. But a guide does not reduce deviation to zero either: even in the guided group, the mean deviation from the plan was 0.76 millimetres in depth, 2.57 degrees in angle and 1.68 millimetres at the tip of the implant. The authors recommend correct case selection and leaving a safety margin.

The same meta-analysis sets out one more limit in figures: with the fully guided flapless protocol, the complication rate during surgery was 12%, and in 7% of cases the implant could not be placed with this protocol. In other words, in some patients the gum has to be opened or the plan changed partway through surgery. A good plan states this possibility from the outset; a patient should not lie down in the chair on the promise that 'there will definitely be no stitches'.

There is a similar picture in full-mouth cases. A review of computer-guided flapless surgery in jaws with no teeth found implant survival of 97.2% and mean bone loss of 1.45 millimetres at 1 to 4 years of follow-up. The same review reports that complications such as implant loss, fracture of the prosthesis or the guide, and weak initial stability of the implant were often reported, and that the technique has a learning curve.

Then there is the gum side. In the flapless method, the round piece of gum over the implant is often removed and discarded. If the firm, attached gum around the implant is already narrow, this loss can become significant. A meta-analysis examining whether the width of this tissue is a risk factor for disease around implants finds the evidence weak; in areas with at least 2 millimetres of attached gum, only less plaque build-up was seen. There is no firm threshold, but it makes sense for the surgeon to measure this tissue and, if needed, look for a way to preserve it.

Flapless surgery calls not for a type of patient but for a type of bone. The distinction below shows which situations make this method easier, and in which seeing the bone is indispensable.

The sequence below describes the general course of guided flapless surgery. In flapless placement done freehand without a guide, the planning steps are more limited.

1. 1

   CBCT scan and intraoral scan

   The width and height of the bone and its distance from the nerve and the sinus are measured on a three-dimensional image. In flapless surgery, this measurement stands in for everything the surgeon will not be able to see during the operation.

2. 2

   Virtual planning and a safety margin

   The position, angle and depth of the implant are planned on the computer. Because deviation occurs even with guided surgery, a safety margin is left between the implant and the nerve, the sinus and the bone wall.

3. 3

   Making the surgical guide and trying it in the mouth

   A guide that sits in the mouth according to the plan is printed or milled. Before surgery it is checked that it sits fully in the mouth without moving; a guide that moves transfers the plan to the mouth wrongly.

4. 4

   Local anaesthetic and opening the gum

   The gum is not lifted; a round piece is removed at the point where the implant will go in, or the drill passes straight through the gum. Surgery usually takes less time than with the conventional method.

5. 5

   Drilling through the guide and placement

   The drills are passed through the rings in the guide to prepare the bone, and the implant is placed. If the bone turns out to be insufficient, the hold is weak or the guide breaks, the surgeon may decide to open the gum in the same session.

6. 6

   Check image and the loading decision

   The position of the implant is confirmed with a check image. When the teeth will be fitted is decided by the implant's initial stability and the planned protocol; being flapless does not change this on its own.

The choice is not simply a question of 'incision or no incision'; between the size of the incision and how the plan is transferred to the mouth, there are several routes in between.

The risks of flapless surgery are added to those of conventional implants; they do not replace them. The following are the ones that stand out as specific to this method.

Because the gum is not lifted, the wound is smaller; but the fusion of the bone with the implant takes the same time with the flapless method too.

1. The first day

   A mild ache is to be expected once the anaesthetic wears off. In studies, pain is reported to be lower with the flapless method, but it is not zero. The painkiller and cold compress your dentist recommends are usually enough.

2. The first few days

   Because there are no stitches, an appointment to remove them is often not needed. The area is protected with soft foods, and you do not chew directly on the implant.

3. The first few weeks

   The gum closes and takes shape around the implant. Cleaning of the area continues as your dentist has shown you.

4. The fusion period

   The fusion of the implant with the bone does not change according to whether it was flapless or not. Check-ups and the timing of loading are planned around this process.

You will not find figures here. In flapless surgery, the items that affect the cost are mostly on the planning side.

CBCT scan and digital planning

The safety of flapless surgery rests largely on planning. Ask whether the CBCT scan, the intraoral scan and the virtual plan are included in the quote.

Making the surgical guide

A guide is made separately for each patient. Do not compare flapless surgery done without a guide and guided surgery as if they were the same job.

The chance of the plan changing

In some cases, the gum may need to be opened or bone added during surgery. Discuss in advance what would happen in that situation.

Number of implants and the prosthesis

Regardless of the surgical method, the total cost is determined above all by the number of implants and the teeth that will be made on top of them.