This research is being done to find out the ideal number of implants/attachments required to provide adequate stability of dentures during function.

The aim of this study is threefold: i) to evaluate within-subject response to complete lower dentures retained by 1 or 2 or 3 implants fitted with independent overdenture attachments; ii) laboratory evaluation of the retention force generated with 1-2 or 3-implants and study its correlation to patients' response; iii) study the wear pattern of the plastic inserts on the overdenture abutments during each retention mode (i.e. the number of implants used to retain the dentures) and correlate its effects to denture stability.

Inclusion Criteria:

• subjects completely edentulous on maxilla and mandible for at least a year (w/out dentures)
• Adult age (25 plus) male or female
• Stable medical health
• Ability to participate in the study for at least 3-4 years
• Able to understand and respond to surveys used in the study
• Adequate amount of bone in the mandible to receive 3 implants.

Exclusion Criteria:

history of drug and alcohol abuse, excessive smoking (more than 1 pack/day)

• surgical limitations:
• uncontrolled systemic disease: diabetes, etc.. that may compromised healing
• irradiated surgical site
• inadequate bone height and width (re: implant size)
• inability to undergo minor oral surgery because of health or personal reasons
• psychological and handicapped conditions that may hinder 4-year involvement (physical handicap conditions)
• Severe TMDs related to joint pathology