Relative nasopharyngeal patency index as possible objective indication for adenoidectomy in children with orthodontic problems

Abstract Objectives Although the harmful influence of nasopharyngeal obstruction on the facial skeleton has been demonstrated, clear criteria to qualify children with adenoid hypertrophy and malocclusion for adenoidectomy have not been established yet. Methods Retrospective analysis of 148 patients qualified for orthodontic treatment (77 females and 71 males) at the age of 9–11 years (the average age was 10 years and 3 months). X-ray images performed with the use of a cephalostat were scanned and submitted for cephalometric assessment. The study investigated the correlation between standard cephalometric parameters and the value of relative nasopharyngeal flow defined as the ratio of the nasopharyngeal flow to the dimension of the entire nasopharynx. In statistics Bartlett's test, Tukey's test and Pearson's correlation coefficients were used. Results The value of relative nasopharyngeal lumen ranged from 0.0943 to 0.5532 with no significant differences between genders. The subjects were divided into decile groups for investigating the correlation with cephalometric parameters. The study demonstrated statistically significant negative correlations between relative nasopharyngeal flow and the following parameters: the angle between lines NA and NB (ANB), the angle between lines SN and ML (SN/ML), the posterior/anterior facial height ratio (Post.Fac.H./Ant.Fac.H.), the difference between the maxillary and mandibular length (difference maxillary/mandibular), the mandibular length (Co-Gn) and the lower anterior facial height (Sn-Me). The correlations generally referred to middle deciles: from the 40th to 80th decile. An apparent lack of significant correlations in patients located below the 40th decile, which corresponded to the value of relative nasopharyngeal flow up to 18%, may indicate, that this value constitutes a threshold and further decreasing it exceeds adaptive capabilities of the body. Conclusions Relative nasopharyngeal flow below 38% should constitute an indication for adenoidectomy, due to the exceeded adaptive capabilities of the body.