Evaluation of nasolacrimal canal morphology in different facial skeletal relationships

BACKGROUND

Abnormal morphological variations of nasolacrimal canal (NLC) and its lack of understanding contributes to acquired injuries during craniomaxillofacial surgical procedures which leads untoward postoperative complications like nasolacrimal obstruction (NLO) and epiphora.

PURPOSE

The purpose of this study was to determine dimensional and volumetric morphological variations of nasolacrimal canal in various facial skeletal relationships which aid in performing a precise and safe surgery.

MATERIALS AND METHODS

This retrospective cohort study involved dimensional and volumetric analysis of nasolacrimal canal procured from computed tomography scans of 47 individuals grouped as ClassI, Class II and Class III, and unilateral cleft lip and palate (UCLP) groups. The outcome variables included length of NLC, volume of NLC, distance between the inferior orifice of the NLC to nasal floor, distance between inferior orifice of NLC to canine apex and distance between inferior orifice of NLC to central incisor apex. The objectives were to analyse morphological variation of NLC in different facial skeletal relationships and to evaluate the variation with change in facial sides and its relationship with surrounding structures.

RESULTS

Volume of the NLC was found significant in Class I and UCLP population (p < 0.05) with the greatest volume in the UCLP group. The mean linear and volumetric measurements between the right and left sides were found insignificant among all groups. Inferior orifice of NLC from canine apex were farthest in Class III and nearest in the UCLP group (p < 0.05). There was no significant association between outcome variables and skeletal base configuration.

CONCLUSION

NLC demonstrates dimensional and anthropometric variations between different skeletal relationships and this study is inevitable in understanding the probability of NLC injury during maxillofacial surgeries.

Correlation of transverse mandibular dimension with naso-pharyngeal and oro-pharyngeal airway using computed tomographic analysis - A retrospective observational study

PURPOSE

The aim of the study was to investigate changes in the naso-pharyngeal and oro-pharyngeal airway with varying degrees of mandibular flare.

METHODS

The investigators implemented a retrospective, observational study including CT data from patients fitting the inclusion criteria. Linear and angular measurements were used to assess the flare and transverse dimension of the mandible, while standard reference planes were used for assessment of airway dimensions. The primary outcome measures were to correlate and quantify the naso-pharyngeal and oro-pharyngeal volumes with mandibular flare. Secondary outcome measures were to study the intra-variable correlation. Significance level was fixed at 5% (α = 0.05).

RESULTS

The sample included CT data from 30 individuals with apparently normal craniofacial skeleton (53% males and 46.7% female with a mean age of 29.53 years). Both nasopharyngeal and oropharyngeal volumes demonstrated moderate positive correlations with inter-condylar width (p = 0.020 and p = 0.038) and inter-condylar angles (p = 0.041 and p = 0.005) respectively. Linear regression modelling demonstrated that for every millimetre increase of the Inter-condylar width, the naso-pharyngeal and oro-pharyngeal airway volume increased by 0.423 cm³ (p = 0.020) and 0.381 cm³ (p = 0.038) respectively, and every degree increase of inter-condylar angle produced an increase the nasopharyngeal and oropharyngeal volumes by 0.376cm³ (p = 0.041) and 0.496cm³ (p = 0.005) respectively.

CONCLUSION

Parameters of mandibular flare demonstrate statistically significant correlation to pharyngeal airway volume, which may be a relevant predictor to evaluate airway in patients undergoing corrective skeletal surgery.