Dental bridge. A complete overview
A dental bridge is a fixed dental prosthesis used to replace one or several missing teeth by permanently joining an artificial tooth to adjacent teeth or dental implants.
Dental bridges are also used to protect and reshape teeth that have undergone major destructions and prevent complications that may arise as a result of tooth loss.
There is a wide variety of dental bridges. The type of bridge that is designed for a particular clinical situation depends on many factors such as geographical location, patient desires and financial situation, practitioner preferences etc.
Although in the past years, dental implants tend to replace them, traditional dental bridges (supported by natural teeth) are still widespread throughout the world.
What is the structure of a dental bridge?
A dental bridge consists of two components :
The anchor crowns (also known as retainer crowns) are two (or more) dental crowns that are cemented to the teeth adjacent to the toothless gap to support the bridgework restoration.
The two anchoring teeth are called abutment teeth. A traditional bridge is supported by natural teeth. Bridges supported by dental implants are discussed in a separate chapter.
Anchor crowns hold the bridge in place and provide support for the pontics. If we imagine that a dental bridge is a bridge over a big river, the anchor crowns along with the abutment teeth are the pillars.
Pontics or artificial teeth
The pontic is the part of the bridge that replaces the missing tooth (or teeth). For that reason, it is also called dummy or artificial tooth.
The artificial teeth are placed between the anchor crowns and basically replace the missing tooth or teeth. Most of the times, the pontic is placed between the abutment teeth (with the exception of the cantilever bridge) and is permanently joined to the anchor crowns.
Depending on the clinical situation and the number of missing teeth, a dental bridge can have one or more pontics.
dental bridge with a single pontic
dental bridge with two pontics
During mastication, all chewing forces that act on the pontics are passed to the abutment teeth; the more artificial teeth, the greater the forces acting on the abutment teeth.
Each individual pontic passes the chewing forces to the abutment teeth. That is why the forces that act on the abutments are greater when the bridge has more pontics (image above).
It is not advisable to overextend the pontic. As a general rule, it is considered that a single toothless gap with more than 4 missing teeth cannot be restored with a traditional dental bridge. There are 2 reasons behind this:
- If the pontic is too extended, there is a risk of breaking during the chewing process
- The forces that act on the abutments are extreme and there is a high risk these teeth become loose causing the restoration to fail
Let's take a closer on how a dental bridge is designed :
What are the main benefits of a dental bridge?
Dental bridges have two major benefits:
- Restoring the missing teeth
- Preventing the complications that may occur after one or more teeth are lost
1. Restoring the missing teeth
The primary role of a dental bridge is to restore (or replace) the missing teeth. Besides "bridging" the toothless gap, the bridge will also "crown" the abutment teeth.
As with any type of dental rehabilitation, one of the most important goals is restoring the main oral functions as close as possible to natural teeth. Let's see how a dental bridge can accomplish this objective.
A dental bridge is permanently fixed to the abutment teeth. All chewing forces pass along the abutment teeth to the jawbone.
The amount of pressure that acts on each abutment depends on the extent of the bridge (the number of missing teeth) and abutment teeth characteristics.
Look at the picture above: all chewing forces that act on the pontic are passed to the abutment teeth.
Unlike bridges, some removable dentures rest exclusively on the gums. Consequently, chewing comfort decreases (because the patient will chew on his gums instead of his teeth) and getting used to removable dentures takes a little longer.
Very important: Dental bridges do not pass any chewing forces to the gums. Basically, the whole chewing process is performed by the natural teeth. That is why chewing on dental bridges has a natural comfort.
Tooth loss severely affects aesthetics, especially if the area is visible. Therefore, restoring the aesthetic function is, for many patients, the most important goal.
restoring aesthetics with a porcelain dental bridge; before and after
Phonetics and pronunciation
If front teeth are missing (especially the upper incisors), normal speech is impeded, particularly the pronunciation of consonants. When a new dental restoration is manufactured, it takes time to adapt the speech to the new conditions.
Unlike removable dentures, dental bridges are smaller restorations that are permanently cemented to the abutment teeth. The oral structures (tongue, lips etc) will need less time to get accustomed to the new situation.
2. Preventing the complications that may arise after teeth loss
If a toothless gap is left unrestored, irreversible changes may take place around this area with an adverse effect on oral health. Let's see some of the changes that may occur following a tooth extraction.
Opposite teeth, marked with a, migrate towards the extraction site (over-eruption). The process occurs until the tooth reaches the opposite gum (the edentulous ridge) or another obstacle located on the path.
Adjacent teeth, marked with v, lean toward the edentulous space, in an attempt "to close the gap".
Teeth migration can lead to the disruption of the most important oral processes: mastication, aesthetics, and phonation. Moreover, migrated teeth can suffer from periodontal diseases or cavities.
When the toothless gap is restored with a dental prosthesis (such as a dental bridge or an implant-supported restoration), teeth migration stops.
What are the most important advantages of dental bridges?
Restoring missing teeth with dental bridges has many advantages. Well-executed and properly maintained, bridges ensure high comfort and aesthetics and patients get accustomed to them in a short time.
Bridges are fixed prosthetic restorations that do not require periodic removal for cleaning
Because of this advantage, many patients prefer them against removable dentures. Bridges are permanently fixed by cementing the anchor crowns to the abutment teeth and there is no need for periodic removal.
Many patients are more comfortable with the idea of a fixed restoration rather than a removable one.
Patients get used to dental bridges in a short time
Bridges are small and lightweight dental restorations. After the definitive cementation, getting used to dental bridges takes less time than in case of removable dentures (or other more complex restorations) which are larger and heavier.
removable partial denture
Dental bridges provide excellent chewing comfort
Chewing comfort is excellent because all chewing forces are passed to the abutment teeth and not to the gums underneath. Therefore, teeth perform the mastication, which is the natural way.
By contrast, removable dentures rest exclusively on the gums; therefore, the chewing process (or at least part of it) is performed on the gums.
Aesthetics are very good
When aesthetic demands are high, it is advisable to opt for porcelain or zirconium-based bridges, which are aesthetically superior.
Few appointments are needed
Bridges can be completed in two sessions, while removable dentures need at least 4 appointments to be completed. Dental implants need 3 to 6 months after the surgical insertion to fuse with the bone through a biologic process called osseointegration.
Lifespan and prognosis are good
To ensure this goal, dental bridges need to be properly maintained.
Dental bridges drawbacks
Bridges require the preparation of the abutment teeth
To ensure the bridge support and insertion, the abutment teeth need to be properly prepared. This operation involves permanently removing part of the tooth's original structure, including portions that might still be healthy and structurally sound.
It's the biggest disadvantage as it leads to the loss of large amounts of healthy tooth tissue and sometimes even tooth devitalization and endodontic treatment. Therefore, restorations supported exclusively by dental implants have the big advantage that teeth adjacent to the gap remain untouched.
This disadvantage stands out especially when the abutment teeth are perfectly healthy without any fillings or cavities.
The abutment teeth may show increased sensitivity to external stimuli
Usually, after teeth preparation, one or more temporary crowns are constructed. These devices will protect the abutment teeth until the definitive restoration is completed.
If no temporary restoration was designed, abutment teeth may show an increased sensitivity to hot or cold stimuli until the bridge is definitively cemented.
When may we need a dental bridge?
Traditional dental bridges have many indications.
Restoring a toothless gap
Restoring one ore several toothless gaps are the main function of dental bridges. It is important that enough teeth remain on both sides of the gap, so the bridge is properly supported.
If there are not enough teeth to support the dental bridge, another type of dental restoration has to be designed: removable denture or a type of implant-supported restoration.
restoring a 2 teeth toothless gap with a dental bridge
Restoring teeth with advanced destructions, erosions or large fillings
A dental bridge can be designed when teeth show advanced destructions, large cavities, erosions or old unsightly fillings.
Besides replacing the missing teeth, the designed dental bridge will restore the morphology of the teeth with advance destructions.
tooth bridge indication: teeth with destructions and old fillings
the designed dental bridge
Sometimes, one or more teeth are out of shape, out of place, or may show discolorations, yellowish color or unsightly fillings.
If changes are not too advanced, aesthetic dental bridges may represent viable therapeutic options.
porcelain dental bridge designed to restore aesthetics;
before and after
Restoring teeth with high degrees of tooth-wear
Tooth wear is the term used to describe the progressive loss of a tooth's surface due to actions other than those which cause tooth decay or dental trauma.
Most of the times, excessive tooth wear is caused by teeth grinding but sometimes it may be associated with an incorrect toothbrushing technique.
Regardless of the cause, over time, teeth will become small and unsightly. Unfortunately, such conditions are always difficult to approach.
In some situations, it is possible to restore these teeth by constructing a dental bridge. It is very important to re-establish the appropriate bite; otherwise, the patient may have a permanent discomfort during the chewing process.
dental abrasion; teeth become small and unsightly
Treatment of occlusal disorders
In some clinical situations, for various reasons, the dental occlusion (or bite) becomes inadequate. These conditions are usually accompanied by pain and discomfort in the jaw muscles and/or TMJ (temporomandibular joint), headaches or migraines, eye or sinus pain and, sometimes, other symptoms.
These conditions call for an occlusion readjustment. Sometimes, this can be achieved by manufacturing a complete dental bridge, a bridge that covers all teeth of the dental arch. Ideally, this bridge will have new and proper contacts with the opposite teeth and the pain will gradually disappear.
In practice, these conditions are extremely difficult to treat. They call for many sessions and a lot of patience. Usually, the treatment plan is quite complex and manufacturing a dental bridge may be just one of the many steps.
Replacing old, inadequate restorations
Old restorations that don't meet the functional and aesthetic demands need to be replaced. Generally, after their removal, the dentist will reassess the clinical situation and develop a new treatment plan.
If enough supporting teeth are still present, a dental bridge may be one of the options.
dental bridge indication: replacement of old, unsightly restorations; before and after
When is a dental bridge NOT indicated?
Restoring toothless gaps when there is not enough support
If the number of abutment teeth is not enough to support the bridge or some teeth are unsuitable (show large destructions, are too loose etc.), it is advisable to opt for a different type of prosthetic reconstruction: removable dentures or implant-supported restorations.
Poor oral hygiene
It is not advisable to design a dental restoration (particularly a large one) if the patient does not have a proper oral hygiene. The most sophisticated and expensive restorations will have a very short lifespan in the absence of an accurate and thorough oral hygiene.
Some serious general conditions can make anesthesia and dental procedures inadvisable. Generally, these situations will be evaluated on a case-by-case basis and the treatment will usually resume after some preliminary treatments.
These are bridges designed outside the general standard.
Bridges with special attachments
Because the bridge must be able to fit onto the abutment teeth simultaneously, the taper of the abutment teeth must match, to properly seat the bridge. This is known as requiring parallelism among the abutments.
When this is not possible, an attachment may be used, so that one of the abutments may be cemented first, and the other abutment, attached to the pontic, can then be inserted.
bridge with attachment
Dental bridge anchored by inlays
Instead of retainer crowns, this type of bridge has two inlays attached to the pontic. The inlays will be cemented to the abutment teeth in specially prepared cavities inside the teeth.
Aesthetics is excellent but it lacks strength and stability; thus, it can only be used when a small restoration is designed.
dental bridge attached by inlays
Also known as adhesive bridge, the Maryland bridge is a conservative alternative to a traditional bridge. It is generally used when a single tooth (normally, front tooth) is missing and it can serve both as a permanent or temporary solution.
The Maryland bridge is essentially a crown with "wings" on both sides which enables affixing the crown to the adjacent teeth on the posterior side.
The frame of the bridge can be made from various materials including metal, composite, zirconia and even reinforced porcelain.
The Maryland bridge is a relatively quick solution and no (or minimal) preparation of the adjacent teeth is required. However, it is only supported by the posterior side of the adjacent teeth; therefore, it can be used only in a limited number of situations and correct planning is extremely important.
Last review and update: June 2018