Lip, tongue, airway changes after first premolar extraction and incisor retraction in orthodontically treated bimaxillary protrusion

Introduction:In cases of bimaxillary proclination, orthodontic treatment often involves retraction of the incisors to correct the protrusion of the lips.This can have a significant impact on the oral and pharyngeal structures, particularly the tongue and airway dimensions.Aim & Objectives: To investigate post orthodontic lip position, tongue position and pharyngeal airway changes after all first premolars extraction with retraction of the incisor teeth in patients with bimaxillary protrusion.Materials and Methods: Twenty patients fulfilling the criteria was selected.Two lateral cephalometric headfilms of the patients, one at the beginning of treatment (T0) and other at the end of treatment (T1), was obtained.Parameters assessed for lip position was: Basic upper lip thickness (BULT) upper lip thickness (ULT), basic lower lip thickness (BLLT), lower lip thickness (LLT), upper lip length (ULL), lower lip length (LLL).Parameters used to assess tongue, pharyngeal airway was: Tongue length (TGL), tongue height (TGH), superior posterior airway space (SPAS) (mm), middle airway space (MAS) (mm), inferior airway space (IAS) (mm), vertical airway length (VAL).Result: This study showed significant decrease in BULT, LLT, TGL (P <0.05), while there was no significant changes SPAS and MAS (p<0.005).On the contrary, an increase in TGH, IAS and VAL (p<0.05) was seen.Conclusion: Extraction of the first premolars for the treatment of bimaxillary proclination does not affect upper airway dimensions despite there was significant reduction in TGL, BULT, LLT and significant increase in TGH, IAS, VAS.