A dental bridge is a fixed prosthetic appliance that replaces missing tooth or teeth and is permanently attached to one or more teeth in the mouth. This appliance is not removable by the patient and hence its called a fixed prosthetic appliance.
These devices or appliances are called bridges because they bridge the gap between teeth, that has been created by missing or extracted teeth. Let’s have a look at who the perfect candidate is, for dental bridges.
Who Needs a Dental Bridge?
Following individuals are considered the perfect candidates for dental bridges.
People with a missing single tooth or two or more teeth where aesthetics(appearance) is of prime concern may go for a bridge.
Individuals with missing posterior (back) tooth or teeth may also need to go for a bridge because getting a bridge can help restore the normal functions of the teeth.
A bridge can also help to prevent adjacent natural teeth from drifting, supra-eruption of opposing teeth and tilting. Supra eruption is a process where the tooth continues to grow out of the gingiva or the gum when the opposing tooth is absent.
Dental Bridge: Important Things to Consider
Your dentist may perform your complete clinical assessment based on the following criteria, before deciding whether you are a perfect candidate for a bridge or not.
Patient assessment plays a very important role in this treatment.
The dentist may consider the age of the individual, oral hygiene condition, and the condition of the remaining natural teeth.
Patient motivation is necessary as the procedure is expensive, time-consuming, and involves tooth preparation of the adjacent teeth. So only after the individual is completely convinced about the treatment, the dentist will proceed with the treatment.
The area of the missing tooth which is also called saddle needs to be taken into consideration before the treatment as it plays an important role.
The adjacent teeth also called the abutment teeth, need assessment. If the teeth are tilted, decayed, or are with a severe periodontal problem, they are not suitable to be used as an abutment.
Individuals with deep bites, teeth grinding habits or bruxism, over erupted opposite tooth into the saddle area, are not suited for bridgework.
Dental Bridge Parts
A typical bridge used in dentistry has the following parts.
- Abutment tooth – A tooth which provides attachment and supports the bridge.
- Retainer – The part of the bridge which is cemented to an abutment tooth.
- Pontic – The artificial tooth which replaces the lost tooth in the bridge.
- Saddle – The area of the missing tooth where the pontic will lie.
- Connector – The part which connects the pontic to the retainer.it can be rigid or non-rigid (with limited movement).
- Unit – Number of pontics + number of retainers/abutments.
Types of Dental Bridges
Fixed -fixed bridge
In this type of bridge, the framework has rigid connectors connecting the pontic to the retainers in one piece. The abutments provide support and retention. The single path of insertion in this type makes it different from the others. So the abutment preparation needs to be parallel to each other in this type of bridge framework.
This type of bridge allows joints with limited movements between the pontic and the retainer.
In the case of the tilted tooth, the design allows for limited movement and the preparation of the abutment tooth need not be parallel.
In this type, the pontic is connected to a retainer at one end only. In places of less occlusal load, especially in the individuals with the front missing tooth, it can be used.
For eg; missing lateral incisor can be replaced by using canine as an abutment.
Spring Cantilever Bridge
In this type of bridgework, the pontic and the retainer are at a distance from each other connected by a metal bar which runs along the palatal mucosa.
For eg; When the upper central incisor is replaced with the retainers placed on premolar /molar. These typed of dental bridges are rarely used now.
Resin Bonded/Adhesive bridge
Composite resins are used as retainer material to bond on to the abutment.
This type of bridge work is done in cases where the individual has
- Good enamel thickness for the etching and bonding process.
- Favorable occlusion with no overbites.
- No bruxism
These bridges are also used in the following ways.
- When splinting teeth.
- As an intermediate restoration.
- Can also be used in young patients with large pulp where tooth preparation for abutment tooth becomes difficult.
Types of Adhesive Bridges
- Maryland bridge
- Rochette bridge.
Hybrid or Compound Bridges
This is a combination of more than one type of bridge mentioned above.
The Complete Process of Dental Bridge Preparation: Step By Step
Selection of Abutment Teeth
There are certain factors which need to be taken into account when selecting the abutment teeth, such as caries status, periodontal health, any previous fillings which are present, root structure and bony support.
There is a law called Ante’s Law which states that ‘The combined pericemental area of the abutment teeth should be equal or greater than the pericemental area of the tooth or teeth to be replaced.’
This rule used to be followed in the earlier days while selecting the abutment teeth. But nowadays it is no longer used in bridgework designs. Presently it is quality of the bone support that matters rather than the quantity.
Pontic design is very important for good aesthetics and maintenance of good oral hygiene.
Types of pontic
Ridge Lap and Modified Ridge Lap – This is the most popular type of pontic design. In this type, pontic should make contact with the buccal aspect of the ridge. This gives good aesthetics.
Hygienic- This type does not contact the saddle. This design is not aesthetically pleasing so preferred in molar regions .it is very easy to clean.
Bullet – This type makes point contact with the tip of the ridge.
Saddle- This design extends over the ridge buccally and lingually, hence difficult to clean. Ideally should not be used.
There are many types of retainers used in a dental bridge.
Depending on the different factors the choice of retainers vary. These factors are
- Existing fillings in the tooth
- The amount of retention required
- Quantity and the quality of dentine remaining after tooth preparation.
Types of retainers
- Full coverage crown(posterior teeth)
- Metal-ceramic crown(anterior teeth)
- Adhesive crown
- Porcelain veneers
- Porcelain jacket crowns(porcelain bridges)
- Three-quarter crowns(rarely used)
- Inlays/ Onlays
- Telescopic or milled crowns (for tilted teeth)
The dentist may follow the protocol below while planning and preparing a dental bridge for you.
1. Patient assessment and history taking is very important before proceeding into the clinical steps. Taking a detailed medical and dental history is important. Patient’s expectations need to be assessed and whether the individual is suited for a bridge or not has to be determined. The individual needs to be motivated as well because the procedure is expensive and time-consuming.
2. Clinical examination of the mouth needs to be done. Oral health and hygiene need to be assessed. The area of the lost tooth/teeth, the abutment teeth health, the occlusion, need to be checked thoroughly. Diagnostic radiographs may be taken if necessary. This will give an idea of the type of bridge work that will be needed.
3. The diagnostic mounting– Primary impression of both the arches needs to be made for diagnostic purpose. A proper face-bow record and study casts are made and mounted for future references.
4. Diagnostic wax-up– This is a mock process for the final restoration on the study casts. Wax is added to the teeth to simulate the final effect. This can also be used as a template for the temporary bridge by taking a putty impression of the wax-up. The final design of the bridge work has to be made at this stage.
5. Abutment teeth preparation – Before proceeding into tooth cutting, the old fillings in the abutment teeth need to be replaced if necessary. Teeth preparations are carried out as per the requirement of the design. Tooth cutting is done accordingly to achieve a single path of insertion with minimum tooth tissue loss, well-defined margins and good clearance in occlusion.
6. Impressions– A good impression of the preparation is made using elastomeric impression material. In cases of subgingival preparations, there will be a need for gingival retraction cords, and the gingival tissue management before making the impression to get accurate margins of the preparation. The impression of the opposing arch will also be needed.
7. Occlusal registration – This needs to be recorded using wax or polyvinylsiloxane especially in bigger unit bridgeworks. Casts are mounted in semi-adjustable articulators using face-bow registrations.
8. Shade selection – Teeth shade selection needs to be done using the given manufacture shade guide in accordance with the material chosen.
9. Temporary bridge – This can be made either in the clinic or laboratory. But bridges done in the lab are stronger and better as they are made up of heat cured acrylic material.
10. Try in of metal work -In case of long-span bridges/bigger unit, it is better to do a try-in of the metal casting to check for the fitting and occlusion. Sometimes it may need sectioning and try-in done with the parts secured in the new positions with acrylic resin and then sent back to the lab for further procedures.
11. Trial cementation – The final finished prosthesis is tried-in and checked for occlusion, marginal fit, aesthetics, contact points, access to oral hygiene measures and speech. Then the bridge is cemented temporarily for 1-2 weeks or a month to check if any further adjustments need to be made.
12. Permanent cementation– If the patient is satisfied during the trial period, then the bridge is removed and finally cemented back with the permanent luting cement.
13. Follow up– Follow up will be needed to check up on the functioning of the bridge and any other related issues such as oral hygiene, detection of any caries in the abutment teeth, periodontal health or debonding of retainers, etc.
Maintenance of oral hygiene is very important with the dental bridge in the mouth. Regular follow up may be required for dental scaling purposes and also for the detection of any dental caries.
With good maintenance, the dental bridge usually lasts for a period of at least 7-10 years or longer.