Age Factors Aged Aged, 80 and over Aging--psychology Caregivers Cognition Dental Plaque--microbiology Dental Plaque Index Denture Cleansers--therapeutic use Dentures--microbiology Female Finland Geriatric Assessment Home Care Services Humans Male Mouthwashes--therapeutic use Nurses, Community Health Oral Health Oral Hygiene--instrumentation Quality of Life Risk Factors Time Factors Toothbrushing Treatment Outcome