Occurrence of kissing molars in a population

Introduction: Aim of the study was to examine the occurrence of kissing molars from the nationwide Health 2000 Survey carried out on the Finnish adult population aged 30 years and older. Kissing molars refer to impaction of a mandibular third molar and a neighboring molar with occlusal surfaces facing towards each other. At present, prevalence of kissing molars at a national level is unknown. Methods and materials: From the two-staged stratified cluster-sample of 8028 subjects, panoramic radiographs and clinical oral examinations were carried out for 5989 subjects (46% men, 54% women; mean age 52.5 years; SD 14.6; range 30‒97). Radiographs were examined for presence of third molars and kissing molars. Clinical measurements included total number of clinically visible teeth and total number of molars. From the demographic data, age, gender, place of residence, and level of education were included. Statistical significances were evaluated with Fisher’s exact test and Mann-Whitney U test. SAS Callable SUDAAN software was used to obtain weighted distributions of kissing molars representative of the population aged 30 years and older, and separately of people with third molars. Results: Kissing molars occurred in 0.05% of the adult population (5 per 10000 adult inhabitants) and in 0.1% of those subjects with third molars (10 per 10000 such subjects). In subjects with kissing molars, the mean numbers of clinically visible teeth (p = 0.021) and molars (p = 0.016) were smaller compared to those without kissing molars. The demographic features analyzed, showed no statistically significant association with the occurrence of kissing molars. Conclusion: This is the first study published to date on the prevalence of kissing molars at the population level. The prevalence of kissing molars in the population was very small. For the sake of comparison, kissing molars are not seen as often as supernumerary teeth in third molar region.