LAUSR

Background Nostril sill asymmetry is one of the most challenging problems in rhinoplasty. Some studies have been performed regarding nostril shape; however, no studies have been conducted on nostril shape in the Persian population. Additionally, the shape of the nostril in frontal view has rarely been evaluated. This study has two aims. The first is to evaluate nostril shape in Persian patients who were candidates for primary rhinoplasty in basal and frontal views. The second is to assess augmentation silloplasty in patients with different sill heights to resolve nostril asymmetry . Methods This research was performed in two phases. The first phase was a cross-sectional study carried out on the deidentified photographs of 122 patients nominated for rhinoplasty surgery at the facial plastic clinic of a tertiary university hospital. The second phase of the research was an interventional study without a control group consisting of 22 patients. The subjects were categorized as Phase 1. Next, an attempt was made to symmetrize nostril heights by sill augmentation surgery. One year after silloplasty surgical outcome was evaluated by measuring the differences in sill heights. Results In the first phase, classification was performed of the nostril shapes of the patients using two views: frontal and basal. Morphologic study has revealed that there are two types of nostrils in the frontal view and three types in the basal view. In the second phase of this research, augmentation silloplasty was employed for the correction of asymmetric sill heights between the right and left sides. The results show that the height differences in the two sills decreased by 44.26% one year after surgery compared to before surgery (CI: 95%, range  − 20.59 to − 67.93), which is statistically significant ( p =  0.0002) Conclusions Classification of nasal base and nostrils relying on visual inspection is still an important tool for clinical evaluation and communication among physicians. This classification is also crucial in selecting the proper method for correcting nasal base asymmetry. Augmentation silloplasty can help surgeons correct nostril asymmetry due to sill height discrepancy. level of evidence IV This journal requires that authors assign a level of evidence to each article. For a full description of these Evidence-Based Medicine ratings, please refer to the Table of Contents or the online Instructions to Authors www.springer.com/00266 .