February 01, 2021
Dentures made it possible for humans to get back their lost teeth. The innovations in dentures, especially in terms of the materials used to fabricate them have made it possible for us to retain our routine functions of speech and chewing even in the absence of our natural teeth.
Dentures are constructed directly on the soft tissues of the mouth. It has been a challenge for dentists over the years to ensure that the denture fits in the oral cavity in the presence of the moist field created by the saliva, an opposing denture, natural teeth, forces of the tongue and neuromuscular disorders present in the patient (if any). An ill-fitting denture caused by these factors is likely to cause inflammation in the lining of the skin that supports the denture. It can be painful and might hamper the normal functionality of the oral cavity. The advent of implant dentistry has led to an upgrade in denture treatment planning as well. Implants placed in certain areas of the arch act as abutments who would receive the denture. These implant-retained dentures are called overdentures.
Just like a sandwich has its main fillings in between two pieces of breads, an overdenture can be imagined in the same way. Here, the implants are sandwiched between the soft tissue and the denture. This design reduces the chances of irritation in the patient's mouth and is sturdier and resistant to forces. However, the way these dentures attach to the implant systems vary in each patient. These attachment systems make it possible for the denture to seat on the implant securely. We will be discussing about two of these attachment systems here - bar overdentures and locator overdentures.
Bar overdentures as the name suggests, involves a bar and a metal clip that secures the implants. The metal clips can be activated and reactivated in order to adjust the position of the bar overdenture. Plastic clips are often recommended as they are easier to manipulate and are less technique sensitive. The bar overdenture is firm and resilient. A lot of thought goes behind the procedure of installing a bar overdenture. The reason for this is that the condition of the bone, the material with which the bar is made, the height of the bar and the normal masticatory (chewing) load of the patient. It is also constructed only in specific cases where the length of the bar is at least 20 to 22 mm between the implants. A shorter bar length cannot provide the needed strength for the denture. This makes bar overdenture the more preferred type of attachment in cases where a patient has lost all his/her teeth. It is a challenge for the patient to maintain his or her oral hygiene under the bar. Hence, the chances of developing a periodontal condition is higher in this type of overdenture.
At the turn of the 21st century, locator overdentures were introduced. These attachment systems consist of a stud (metal knobs) which act as a universal hinge for the dentures. The locator overdentures consist of a male and a female component. The male component is made of nylon that braces the implants. The female component is slightly oversized, placed in the denture and is received by the male component. These overdentures are used in cases where the arch size is small. The nylon component is less resistant and hence these overdentures are not used in cases where a rigid support of the denture is recommended. At the same time, in patients where the bone condition is weak, these attachment systems can be used as they are less hard on the underlying tissues.
Patients often decide opt for their chosen type of overdenture based on the cost of these attachment systems. The bar type is usually more expensive than locator attachments. However, the patient should be educated about the pros and cons of each attachment system. It is important to explain the patient about the number of implants placed and the type of attachment system that would go best with it considering his or her bone condition and status of oral hygiene.
Bar overdenture and locator overdentures have long been in use. Some other commonly used attachment systems are magnetic and telescopic overdenture. Implant dentistry has thus added a layer of ease when it comes to denture delivery as overdentures go easy on the soft tissues and stand against the intraoral forces from all directions.