Association of malocclusion and functional occlusion with signs of temporomandibular disorders in adults: results of the population-based study of health in Pomerania

The objective of this study was to determine whether associations exist between occlusal factors and signs of temporomandibular disorders (TMD) in adults using the population-based Study of Health in Pomerania (SHIP), Germany. A representative sample of 4310 men and women aged 20 to 81 years (response 68.8%) was investigated for TMD signs, malocclusions, functional occlusion factors, and sociodemographic parameters. Multiple logistic regression analysis, adjusted for sex, age, and socioeconomic status, was used. The results were compared with other population-based studies identified by a systematic review. Few malocclusions and no factors of functional occlusion except socioeconomic parameters were associated with TMD signs, and these associations were mostly weak. Only bilateral open bite up to three mm appeared to be clinically relevant and was associated with TMD signs (odds ratio [OR] = 4.0). This malocclusion, however, was of rare occurrence, with a prevalence of 0.3% (n = 9), and this finding was not confirmed by other representative studies. Occlusal factors examined in this study explained only a small part of the differences between normal subjects and those with TMD signs. This and other population-based studies indicate that malocclusions and factors of functional occlusion surveyed should be seen as merely cofactors in the sense of one piece of the mosaic in the multifactorial problem of temporomandibular dysfunction. Single occlusal factors that showed significant effects throughout several studies could not be detected. In view of the large number of occlusal variables already investigated, other variables including nonocclusal ones probably also play a role and should be looked at more intensely.