An overdenture is a removable prosthetic appliance which is fabricated by taking support from one or more remaining natural teeth, the root of the tooth or a dental implant. This is done by enclosing them beneath the fitting surface of the prosthesis. These types of denture prosthesis can either be complete dentures or partial dentures.
An overdenture also has the following names.
- Overlay denture
- Onlay or inlay denture
- Hybrid denture
- Tooth supported denture
- Telescopic denture
- Superimposed denture
When is an Overdenture Recommended?
An overlay denture may be recommended in the following cases or for the following individuals.
- For an individual with a cleft lip and palate.
- For anyone with surgical or traumatic defects in the mouth.
- In people with hypodontia (developmental dental anomaly with the absence of one or more teeth).
- In case of severe tooth wear conditions.
- As a preventive approach, in people with few remaining teeth, an overdenture can be used to elongate the process of being completely edentulous and to prevent the bone resorption.
- The overlay dentures can be better in terms of retention and stability and can withstand increased occlusal load in cases where the conventional partial dentures may be difficult to fabricate.
- In people with bone resorption or ridge defects where the conventional method would be difficult, overdenture may be recommended.
- People with poor lower denture retention and stability with conventional dentures may be suited for an overdenture. This may due to the hyperactive tongue or poor muscle balance
- People who are completely edentulous(toothless) in one arch or one jaw and have teeth in the other arch.
- For young individuals.
Advantages of Overdentures
Following are some of the unique advantages of using these dentures.
- The overlay dentures help maintain the alveolar bone health around the retained tooth or teeth.
- Since few natural teeth are still intact, the proprioceptive property of the periodontal ligament is preserved in this treatment.
- The retention, stability, and support are better than conventional dentures.
- It helps the individual psychologically in the easy transition from partially edentulous to completely edentulous stage.
Although there are many advantages to the use of overdentures, there are many drawbacks too. Here are some of the important ones.
- There may be a possibility of dental caries (high caries index) or periodontal problem with the retained tooth or teeth.
- These dentures require more maintenance than conventional dentures.
- The abutment tooth or teeth may require a root canal treatment.
The overdentures are expensive.
- The process may be clinically challenging for the dentist as well.
Selection of the ideal patient for an overdenture is a crucial part for the dentist. History taking and a thorough clinical examination are needed while choosing a patient.
The patient’s expectation has to be assessed by the dentist. An individual who can maintain good oral hygiene is a better candidate.
Types of Overdentures
The overdenture design has to be decided depending on the various factors discussed earlier.
There are two types of overdentures based on the type of abutment. An abutment is a structure built to support the lateral pressure of an arch or span.
- Tooth supported
- Implant supported.
The tooth supported overdenture may be constructed using precision attachments or copings (metal coverings) or non-coping (conventional fillings) over the abutment teeth.
If an individual has a sufficient amount of bony ridge on the arch an implant supported overdenture may be recommended. As these things can be expensive, the individual’s financial status may also need to be taken into consideration while opting for implant supported overdentures.
Implant supported overdentures may be costlier than the conventional overdentures but are more cost-effective than the fixed implant prosthesis. The implant based overdentures are also better aesthetically and are great for young individuals with good bone status and with good overall health.
The number of implants needed and the attachment system needs to be decided by the dentist.
The implants placed within the bone will need time to heal, maybe around 3-6 months depending on the patient.
Then the overdenture is fabricated according to the type of implant used and type of attachments used using the methods mentioned below.
The overdenture has 2 units.
One is the male unit which consists of the abutment teeth and the copings or the restorations. The denture base unit is the female part.
Abutment Teeth Selection
The Abutment teeth selection will be done by the dentist based on certain criteria.
- The abutment tooth should have sufficient tooth substance.
- The periodontal health of the tooth should be favorable with no or limited mobility, healthy gingiva, good periodontal support.
- The abutment teeth should be spaced around the arch, bilateral, symmetrical with adequate inter-arch space.
- The tooth should be endodontically favorable if in case it needs root canal treatment.
- Preferable tooth of choice for use as abutments, in order, are canines, molars, premolars or incisors.
Abutment Tooth Preparation
The preparation of the tooth depends on the type of material used or technique followed for overdentures.
In the conventional method with no copings, the abutment teeth selected are cut around 2-3 mm to a dome shape. The teeth may need an endodontic treatment(RCT) which will be followed by the fillings either using amalgam or composite restorations.
The abutment teeth with copings are metal coverings over the prepared and root canal treated abutment tooth.
Another method is abutments with precision attachments, such as studs/anchor, bars, magnets, and hollow posts. These attachments are either prefabricated by the manufacturer or attached to the abutment through a metal coping.
These attachments are used to increase the retention of the overdentures.
But the disadvantages of the attachments are, they are expensive, difficult to repair and may increase the load on the abutment tooth.
The procedures followed by the dentist in the clinic, for the fabrication of overdentures, are similar to the ones followed in the case of complete denture prosthesis.
- The primary impressions of the prepared abutments are made with elastomeric impression material.
- Then special trays are fabricated in the laboratory for border molding procedure and then final impressions are made and sent to the laboratory for jaw relations.
- Once the jaw relations and occlusal registrations are done, teeth are selected and sent over to the lab for further process.
- The try-in is done by the dentist to verify the record done in jaw relation. The dentist also checks for the speech of the patient, aesthetics.
- Once the dentist and patient are satisfied by the results achieved in the try in, it is sent over to the laboratory for final denture base fabrication.
- Finally, the denture fit in is done in the clinic.
- The dentist will check for any overextension of the denture base or sharp edges.
- The post-insertion advice will be given by the dentist as the overdentures need very good maintenance.
- The abutment teeth require good care.
- Oral hygiene regime has to be followed properly to preserve the abutment teeth.
- The denture needs to be removed at night and placed in a box of water.
- The denture needs to be cleaned regularly with soap, brush, and water.
- The abutment teeth need to be cleaned and the use of fluoride-containing toothpaste may be recommended.
- Follow up to the dentist is a must to check for the status of the abutment teeth.
The success of overdenture to a greater extent depends on you, on how well you maintain your oral hygiene measures and regular follow up protocol.