AIM: The purpose of this study was to assess the long-term influence of gingival inflammation on tooth loss.

MATERIAL AND METHODS: The data originated from a 26-year longitudinal study of Norwegian males, who practiced adequate daily oral home care and received "state-of-the-art" dental care. The initial examination in 1969 included 565 individuals aged between 16 and 34 years. Subsequent examinations took place in 1971, 1973, 1975, 1981, 1988 and 1995. Thus, the study covers the age range of 16-59 years. The teeth were divided into three tooth groups (I-III) reflecting the history of inflammation of the surrounding gingiva (gingival index (GI) scores) over 26 years: (I) teeth with surrounding gingival units scoring a minimum of one site with GI=0 and a maximum of three sites with GI=1, (II) teeth with surrounding gingival units scoring a minimum of one site with GI=1 and a maximum of three sites with GI=2 over the observation periods and (III) teeth with surrounding gingival units always scoring a minimum of GI=2 (bleeding on probing) at all sites over the observation period.

RESULTS: At baseline (1969), out of possible 15,820 teeth (565 x 28), 15,383 teeth were present. Four hundred and thirty-seven teeth had already been missing for unknown reasons. By 1995, 13,159 teeth were reexamined, i.e. over the 26-year observation period only 126 (0.95%) teeth were lost. Only 16 (0.28%) of 5793 teeth belonging to GI-Severity Group I were lost. In the GI-Severity Group II, however, 78 (2.28%) out of 3348 teeth were lost, and 13 (11.21%) of 103 teeth with GI-Severity Group III were lost. Teeth with GI-Severity Group III yielded an odds ratio for tooth loss that was 46 times higher than that of teeth with GI-Severity Group I, and five times higher than that of teeth with GI-Severity Group II over 26 years. Furthermore, teeth with the GI-Severity Group II had a nine times higher risk for tooth loss than teeth with the GI-Severity Group I. The GI-Severity Group I retained 99.5% of the teeth after a tooth age of 51 years. The GI-Severity Group II retained 93.8% of the teeth after a tooth age of 50 years. However, in the GI-Severity Group III, 63.4% of the teeth were retained for a tooth age of 47 years.

CONCLUSIONS: Teeth surrounded with inflammation-free gingival tissues were maintained for a tooth age of 51 years, while teeth consistently surrounded with inflamed gingivae yielded a 46-times higher risk to be lost. Only two-thirds of such teeth were maintained throughout the 26-year observation period. This documents the role of gingival inflammation as a risk factor for future tooth loss.