Oral disorders are often cumulative, i.e. destruction of oral tissues and loss of function accumulate in time. Therefore, aging is positively associated with reduced oral functions. Oral diseases have great impact on mastication, lubrication, speech, taste and aesthetics. Maintaining or restoring oral health and function have therefore a significant impact on quality of life parameters. Oral diseases, e.g. periodontitis is not only a local chronic inflammatory oral infectious disorder but the disease has systemic effects. Positive associations have been established between oral health and cardiovascular diseases and auto-immune diseases notably diabetes, rheumatoid arthritis and thyroid disorders. Oral diseases can have an impact on the onset and progression of these diseases. Also, treatment of these diseases can be hampered in subjects with oral infections. Reduction of the total inflammatory status including reduction or elimination of chronic oral infections in susceptible individuals can therefore contribute to reduction of medical and economic burden.
Tooth loss still increases with age, and demographic trends indicate that the population of older individuals is increasing in size. As a result, the number of edentulous people and the demand for complete dentures will continue to be high for several decades. Edentulous patients often experience problems with removable complete dentures. Lack of stability and retention of their dentures, together with pain, decreased chewing ability, and speech problems, are common obstructing complaints reported by these patients. Clinical studies revealed that these denture-related complaints seriously affect the patients’ quality of life. For example, masticatory performance in complete denture wearers is less than 20% of masticatory performance in subjects with a natural dentition. As a result many denture wearers face problems when eating food, and particularly when eating hard or tough food. This inconvenience forces patients to change their diets, often resulting in poorer nutrition compared with patients who have their natural teeth. Therefore, it is not uncommon for many denture wearers to report gastrointestinal problems. Implant-retained overdentures improve edentulous patients' nutritional status, general health, and quality of life.