Dental Implant vs Dental Bridge

Two Ways to Replace a Missing Tooth

When a single tooth is lost, a fixed replacement can be built in two common ways: a dental implant or a dental bridge. Both are fixed and both restore chewing and appearance. The difference lies in where the new tooth takes its support from.

An implant rebuilds the missing root. A titanium post is placed into the jawbone, the bone grows onto its surface over the following months, and the new crown is fixed to that post. The teeth on either side are left as they are. A bridge leaves the root space empty. The two teeth next to the gap are trimmed down and covered with crowns, and a false tooth is suspended between them, so the bridge borrows its support from healthy neighbours.

That structural difference shapes almost everything else. The implant needs surgery, enough bone and a healing period, but it spares the adjacent teeth. The bridge needs no surgery and can be finished in a few appointments, but it permanently removes tooth structure from two teeth and depends on their health for as long as it stays in place. The right trade-off depends on those neighbouring teeth, the bone at the site and the time available.

How an Implant Is Built and Placed

A dental implant has three parts. The titanium post sits in the bone and acts as the root. The abutment is the connector that screws into the post and rises through the gum. The crown is the visible tooth, made of porcelain or zirconia and fixed to the abutment.

Treatment starts with an examination and a three-dimensional scan. The scan shows the height and width of bone at the gap and the position of the nerve canal in the lower jaw or the sinus in the upper jaw, so the length, width and angle of the post can be planned. The post is placed under local anaesthesia. The bone then needs time to grow onto the implant surface, typically two to four months, before the abutment and the final crown are attached.

Mild pain and swelling after surgery are expected and usually settle within a few days. If bone is insufficient, grafting or a different implant position may be planned first, and that adds its own healing time. The implant leans on no other tooth; the price is a surgical step and a waiting period.

How a Bridge Is Built and Its Types

A conventional dental bridge has three units: two crowns on the teeth either side of the gap and a false tooth, called a pontic, joined between them. The pontic has no root, so the whole chewing load passes through the two supporting teeth. Their roots and gums need to be sound for the bridge to last. The steps, materials and cost of a bridge are set out on the dental bridge page.

The procedure has no surgery. Under local anaesthesia the supporting teeth are reduced all the way round so crowns can fit over them, an impression is taken and a temporary bridge is placed while the final one is made. At the next visit the final bridge is cemented. Temporary sensitivity is common afterwards.

Several designs exist. A traditional bridge rests on a tooth at each end of the gap. A cantilever bridge is held from one side only, and its long-term figures are weaker, as the survival data below shows. A Maryland bridge is bonded to the back of the neighbouring teeth with small wings and removes far less tooth structure, but it suits specific situations, mainly front teeth with light bite forces.

Survival Over Five and Ten Years

Measured survival is closer than the common belief that an implant simply lasts longer. A meta-analysis of cohort studies estimated 5-year survival at 94.5% for implant-supported single crowns and 93.8% for conventional tooth-supported bridges (PubMed 17594374). At 10 years the estimates were 89.4% for implant-supported single crowns and 89.2% for conventional bridges (PubMed 17594374).

Over a decade, then, the chance that each restoration is still in the mouth is almost identical. The picture changes for the less favoured designs. In the same analysis the 10-year survival of cantilever bridges fell to 80.3%, and the authors recommended conventional bridges, solely implant-supported prostheses or implant-supported single crowns as the first options, with cantilever bridges and designs combining teeth and implants kept as second choices (PubMed 17594374).

What happens after a failure differs more than the survival rates do. When a conventional bridge fails, it is often because one of the supporting teeth has decayed or lost its nerve, so the next restoration has to deal with a weakened tooth and a larger gap. When an implant crown fails, the neighbouring teeth are usually untouched. Survival figures count only whether the restoration is still present; how often it needed repair is a separate question, covered next.

Complications on Each Side

Complications are more frequent on the implant side, even though survival is similar. In the same meta-analysis, 38.7% of patients with implant-supported fixed prostheses had some complication within 5 years, against 15.7% of patients with conventional tooth-supported bridges (PubMed 17594374).

The types of problems differ by design. On conventional bridges the most frequent complications were biological: decay in the supporting teeth and loss of pulp vitality, meaning the nerve of a supporting tooth dies and may need root canal treatment. On implant restorations technical problems dominated: fracture or chipping of the veneering porcelain, loosening of the abutment or screw, and loss of retention (PubMed 17594374).

A separate meta-analysis of 46 studies of implant single crowns put the cumulative 5-year incidence of screw loosening at 8.8%, making it the most frequent technical problem in that group (PubMed 23062124). The same review reported a cumulative 5-year soft tissue complication rate of 7.1% (PubMed 23062124).

Most technical problems are repairable. A loose screw can be tightened or replaced and a chipped crown can be repaired or remade without losing the implant. Biological problems on a bridge are often harder to reverse because they affect natural teeth. Regular check-ups catch loosening, chipping, early decay and gum inflammation while the fix is still small.

Bone, Gums and Appearance

After a tooth is removed, the bone that held its root gradually remodels. An implant sits in that bone and carries chewing load into it. A bridge leaves the bone under the false tooth without a root, so the ridge beneath the pontic can continue to shrink over the years, and a small gap may appear between the pontic and the gum.

Both options can look natural. What decides the aesthetic result is the material and the condition of the gum. All-ceramic or zirconia crowns remove the risk of a grey metal edge at the gum line. With a bridge, gum recession around the supporting teeth can expose the crown margins over time. With an implant, the same happens if the gum and bone around the post are not maintained.

The health of the gums affects the survival of both. Plaque that collects around the supporting teeth of a bridge or around an implant can cause inflammation that, left untreated, damages the bone. A history of gum disease needs to be treated and stable before either restoration is placed.

Comfort, Chewing and Daily Cleaning

Chewing feels close to a natural tooth with an implant, because the load passes through its own root into the bone. A bridge also handles firm foods, but the load of the missing tooth is shared between the two supporting teeth, which carry it in addition to their own.

Once finished, both should feel comfortable, and persistent pain in either case is a reason to be seen.

Daily cleaning is where patients notice the difference most. An implant crown stands on its own and is brushed and flossed like a natural tooth. A bridge cannot be flossed in the normal way because the false tooth is joined to its neighbours and rests on the gum. The area under the pontic and the margins of the supporting crowns need a floss threader, special bridge floss or an interdental brush every day. When that area is neglected, plaque builds up at the edges of the supporting teeth and causes decay and gum inflammation. Many bridges are replaced because a supporting tooth is lost, while the bridge itself is still intact. A bridge can also come loose if its cement weakens.

Findings That Decide Between Implant and Bridge

The choice follows from what the examination shows. An implant makes sense when the teeth on either side of the gap are healthy, the scan shows enough bone height and width, and the patient can accept a healing period of a few months. In that situation a bridge would mean trimming two sound teeth to fill one gap, which cannot be undone.

A bridge makes sense when the neighbouring teeth already have large fillings or crowns, or will need crowns anyway, since covering them also closes the gap. It also suits patients who prefer to avoid surgery, need the tooth replaced within weeks, or whose bone would need extensive grafting.

Some situations call for delaying an implant. Uncontrolled diabetes, active gum infection, severe bone loss and heavy smoking all interfere with healing. Most can be treated first.

At the consultation the useful questions are whether the teeth next to the gap have fillings, crowns or root canal treatment, whether their roots and gums could carry a bridge, how much bone the three-dimensional scan shows at the site, and whether any health condition would affect healing. With those answers the two options can be compared for the specific mouth.