The Influence of Mandibular Third Molar Position on Distal Caries in Mandibular Second Molar


Introduction: Distal caries of mandibular second molars has been documented to be associated almost exclusivelywith impacted third molars. The level of involvement of second molars in distal caries is influenced by the angulationof the occlusal surface of mandibular third molars and third molars depth. In spite of the importance of these factors onthe occurrence of distal caries, their influence on prophylactic extraction decision of asymptomatic impacted molars forIraqi population did not get enough attention.Aim: of the study: To determine the influence of mandibular third molar impaction, as identified by panoramicradiograph, on distal caries incidence in second molar in Iraqi population.Materials and Methods: Panoramic radiographs of impacted mandibular third molars prior to surgical extraction wereretrieved from the database of Al-Karamah Secondary Dental Care Centre in the period 2004-2013. Demographic datawere collected for all cases. Each panoramic radiograph was examined for the presence of distal caries of mandibularsecond molar and for the level of depth and degree of angulation of adjacent impacted mandibular third molar.Results: One hundred forty-eight panoramic radiographs of 214 pre-surgically extracted impacted mandibular thirdmolars were reviewed. Eighty-four (56.8%) of the cases were for males and sixty-four (43.2%) were for females. ChiSquareTest showed significant relationship between age group, impaction angulation, impaction depth and incidenceof mandibular second molar distal caries. It also showed highly significant relationship between angulation and depthof impaction.Conclusion: Horizontally impacted mandibular third molars close to the level of occlusion increases the chance ofdistal caries incidence in adjacent mandibular second molars. Close monitoring for such cases would be a suitableoption. Further prospective studies should be conducted to study the influence of other factors on distal caries incidence.