Center for Periodontology;
The Forsyth Institute;
Boston;
USA;
College of Dental Medicine;
Roseman University of Health Sciences;
Henderson;
USA;
Department of Epidemiology and Biostatistics;
University of Georgia;
Athens;
USA;
Department of Epidemiology;
Boston University School of Public Health;
Boston;
USA;
Department of General Dentistry;
Boston University School of Dental Medicine;
Boston;
USA;
Department of Periodontics;
Creighton University School of Dentistry;
Omaha;
USA;
Institute of Dentistry;
University of Helsinki and Helsinki University Central Hospital;
Helsinki;
Finland;
Satakunta Central Hospital and Turku University;
Turku;
Finland;
Twins; Birth; Weights; Oral; Health; Correlated; Data; Linear; Mixed; Effect; Models;