“…In other studies, poor metabolic control has been found to relate to more AL (Seppälä et al 1993, Bridges et al 1996), bone loss (Seppälä et al 1993, Taylor et al 1998) and advanced periodontal disease (Collin et al 1998). However, many studies have failed to reveal any conclusive association between metabolic control and the severity of periodontitis (Barnett et al 1984, Rylander et al 1986, Bačić et al 1988, Hayden & Buckley 1989, Sastrowijoto et al 1989, De Pommereau et al 1992, Pinson et al 1995, Thorstensson et al 1996, Kawamura et al 2001). At the background of these contradictory results, there may be variation in the classification of metabolic control or a failure to control the confounding factors.…”