COMPLETE DENTURES There are two types of appliances: conventional and immediate. A conventional appliance is made and placed in the patient’s mouth after the remaining teeth are removed and tissues have healed. It is a process that can take several months. An immediate appliance, on the other hand, is inserted as soon as the remaining teeth are removed. With an immediate appliance, the patient does not have to be without teeth during the healing period. An immediate appliance may require basing or relining to fit properly during the healing period (6-8 weeks) due to bone and gum shrinkage. After the healing period, a conventional appliance is then made.

Fabricating a Complete Denture

There are many factors involved when designing this type of appliance and if one factor is overlooked, it can lead to failure of the case. In many instances, the appliance should fit comfortably soon after being inserted. One of the most critical aspects of the process is that the impression must be perfect and with a flawless technique, used to make a model of the patient's gums. The dentist must use a process called border molding to insure that the denture edges do not hit aggressively into the edges of the mouth. An endless array of never-ending problems with this appliance may occur if the final impression is not properly made. Designing it takes a considerable amount of patience.

The full upper appliance is usually easier to design so that it is stable without slippage. The lower appliance tends to be more difficult because there is no "suction" holding it in place. For this reason, most dentists have come to strongly recommend that a lower denture be supported by 2-4 implants placed in the lower jaw for support. This is a far superior product than a lower appliance without implants that is held in place with weak lower mouth muscles. The ability to bite into an apple or corn-on-the-cob with a lower appliance anchored by implants is possible. The ability to bite into this same apple or corn on the cob with a lower appliance that is not supported with implants, is a difficult, if not impossible task to achieve.

Some patients, believing full denture appliances are in their best interest, extract all of their teeth and have the appliance inserted. Yet, statistics show that the majority of patients who received the appliance in this manner come to regret their decision. They come to find that there is a decrease in their chewing ability (full dentures have only 10% of the chewing power of natural teeth) and they experience difficulty with the appliance sitting properly. They do not realize that while a full upper tends to be very stable, the lower appliance needs as much help from the natural teeth as possible for stability to be successful. If one tooth is retained on the lower area of the mouth, that tooth can contribute to the appliance's stability. It is advised that patients keep their natural teeth as long as possible, especially the lower teeth.

Problems with Complete Dentures

Some of the problems associated with removable appliances include an overproduction of saliva, sore spots, gagging, gingivitis and movement.

Saliva

The brain senses this appliance as "food" and sends messages to the salivary glands to produce more saliva and to secrete it at a higher rate. Patients must become accustomed to having an appliance inside their mouth that is not food.

Sore Spots

Newly installed appliances may cause sore spots in many individuals as they tend to rub and press on the mucus membranes of the mouth. Subsequent adjustments for the weeks following their insertion should take care of this problem.

Gagging

Gagging is another issue encountered by some patients. The cause of this may be due to a loose fitting or to a appliance that is too thick or not extended far enough back on the palate. Some suggest that at times, the gagging may be attributed to some sort of psychological denial of the appliance. And since the psychosis is difficult to treat by the dentist, as it is beyond the scope of their expertise, both a psychologist referral or an implant supported palate less may be offered as alternative to helping a patient.

Gingivitis

Gingivitis can develop underneath the appliance, a result of accumulating dental plaque. Gingivitis can involve gum inflammation and mouth sores. The condition is generally reversible. Denture wearers are advised to clean the thoroughly. The removal of plaque and calculus is usually not painful, and the inflammation of the gums should be gone between one and two weeks. A dentist or dental hygienist can also perform a thorough cleaning of the teeth and gums areas of the mouth. Following a professional service, patients must be persistent with their oral hygiene care. Oral hygiene including proper brushing and flossing is required to prevent the recurrence of gingivitis. Anti-bacterial rinses or mouthwash may reduce the swelling and local mouth gels which are usually antiseptic and anesthetic can also help with the problems associated with gingivitis.

Movement: Support, Stability and Retention

Some patients experience problems with keeping their appliances in place. There are three rules which dictate the existence of removable oral appliances: support, stability and retention.

Support

Support describes how well the underlying oral tissues keeps the appliance from moving. Recently, dentists have been looking to increase the stability of this appliance by using implants. After many years of wearing dentures, the ridges upon which the appliance rests deteriorates and can easily all but disappear. The insertion of implants into the bone below the appliance can help to keep it from occurring. The implants are strategically placed to bear the brunt of the pressure when the appliance is used for chewing, keeping the bone from melting away. When implants are integrated into treatment, the appliance is now referred to as being an implant supported overdenture and the implants are referred to as overdenture abutments.

Stability

Stability describes how well the appliance base is prevented from  sliding side to side or front and back. The more the base runs in smooth and continuous contact with the ridge area upon which the teeth used to reside, the better the stability.

Retention

Retention describes how well the appliance is prevented from moving in the opposite direction of insertion. The better the inside surface of the base to the surface of the underlying mucus membranes, the better the retention will be. The most critical element in the retentive design of a full upper appliance is a complete and total border seal in order to achieve 'suction'.

Complete Dentures and Implants

There has been an increase in dental practitioners incorporating the use of full dentures with implants. The use of implants when designing a full denture appliance has increasingly shown to improve a patient's denture wearing experience by increasing its stability, as well as saving the patient's bone from wearing away. Implants used with full appliances has also been shown to help with appliance retention.

Conclusion

The fabrication of a complete denture appliance is a challenge for any dentist, including those who are experienced. At least two follow up visits for an adjustment to remove sore spots will also be necessary. The upper appliance is fabricated to work in harmony with the lower appliance. If the only variables in the equation are the patient's ridges and two full appliances, the dentist sets the teeth to help prevent dislodgement during opening, closing and swallowing. But once food enters into the picture, the stability of the appliances can be disrupted. During chewing, the appliance bases will sometimes move. In a perfect world, a patient with a perfect edentulous ridge with a perfectly fitting appliance would require no adhesive, as the actual form of the appliance base should work without moving in any way, shape or form. But alas, this is not a perfect world. Therefore, an adhesive is recommended as a way to provide additional retention for well-fitting appliances.

Denture adhesive products should not be used for old, ill-fitting dentures. A poorly fitting appliance can cause constant irritation over a long period of time, and contribute to the development of sores. The appliance may need to be relined or replaced. If, at any point, your dentures begin to feel loose, or cause pronounced discomfort, contact your dentist for a consultation.

Over time, dentures will need to be relined, rebased, or remade due to normal wear. To reline or rebase the appliance, the dentist uses the existing teeth on the denture and refits or makes a new base. The appliances may need to be replaced if they become loose and the teeth show signs of significant wear. This usually occurs as a natural progression of aging. Bone and gum ridges can recede or shrink, causing jaws to align differently. Shrinking ridges causes dentures to fit less securely, making chewing more difficult and changing facial features. Loose appliances can also contribute to sores and infections. Therefore, it is important to replace worn or poorly-fitting appliances before they cause serious health problems.