comparison of changes inmandibular third molar angulationfollowing first/second premolar extraction versus non-extraction orthodontic treatments

objective: extraction of premolars is believed to affect the eruption of third molars. this comparative study aimed to assess the change in angulation of third molars following first/second premolar extraction versus non-extraction orthodontic treatments. methods: this historical cohort study was conducted on patients assigned to three treatment groups: extraction of mandibular first premolars (group a), extraction of mandibular second premolars (group b) and non-extraction orthodontic treatment (group c). each group included 30 third molars. patients were in the age range of 11-19 years and the third molars were in nolla’s6-8 stage of tooth development. pre- and post-treatment panoramic radiographs were analyzed. results: the angle between the long axis of the mandibular third molar and mandibular plane increased by 7±2.2° in group a and 5.2°in group b and the increase in both groups was statistically significant (p<0.05). angular changes in group c were not statistically significant (p>0.05). the angle between the long axes of mandibular first and third molars decreased by 6.83±0.3° in group a. this reduction was statistically significant (p<0.05). conclusion: in extraction orthodontic treatments (versus non-extraction treatments), mandibular third molars tend to straighten up and become upright so the risk of their impaction may be decreased.