Recognition and Management of Eruption Problems Dr. Bill Proffit When teeth fail to erupt, the problem can be either mechanical obstruction of eruption (usually the cause) or a failure of the eruption mechanism. In addition to the common examples of mechanical obstruction from primary or permanent teeth, this category includes cleidocranial dysplasia and tongue size/posture problems. Failure of the eruption mechanism can be diagnosed clinically from a clearance of the eruption path with no concomitant eruption. Diagnosis of the unusual condition, now called primary failure of eruption, is important because the periodontal ligament is abnormal. Attempting to pull these teeth into position with orthodontic treatment leads only to displacement of non-affected teeth included within the appliance set-up. Key Points: -mechanical obstruction – remove obstruction and the impacted tooth will move on its own or it can be brought in with orthodontic therapy. -failure of the eruption mechanism or primary failure of eruption Characteristics: involved teeth are not ankylosed but fail to erupt or respond to orthodontic force. Eruption path is cleared but tooth does not follow Posterior teeth involved could be unilateral, or bilateral and any or all quadrants -special thought regarding primary failure of eruption – all teeth distal to the most mesially involved tooth are also involved. -key diagnostic characteristic of primary failure of eruption – eruption path is cleared and the tooth doesn’t follow it. -wandering lower premolars a. #20 and #29 erupt distally to mesial of lower first molars and then comes forward and erupts into occlusion b. If lower first molars are missing #20 and #29 erupts distally to mesial of lower second molars and usually there is a space between lower first and second premolars. c. If lower first and second molars are missing #20 and #29 erupts all the way distal to third molars or occasionally into ramus -If maxillary permanent cuspids are erupting mesially to maxillary primary cuspids it is a bad sign and best to extract primary cuspids.