|Year : 2022 | Volume
| Issue : 1 | Page : 48-54
Correlation and comparative evaluation of nasal index and nasal cavity volume in nasal and mouth breathers: A preliminary cone-beam computed tomographic study
Ritesh Kalaskar1, Shruti Balasubramanian1, Ashita Kalaskar2
1 Department of Pediatric and Preventive Dentistry, Government Dental College and Hospital, Medical College Premises, Nagpur, Maharashtra, India
2 Department of Oral Medicine and Radiology, Government Dental College and Hospital, Medical College Premises, Nagpur, Maharashtra, India
|Date of Submission||06-Nov-2021|
|Date of Decision||03-Feb-2022|
|Date of Acceptance||05-Feb-2022|
|Date of Web Publication||13-Apr-2022|
Dr. Shruti Balasubramanian
Department of Pediatric and Preventive Dentistry, Government Dental College and Hospital, Medical College Premises, Medical Square, Nagpur - 440 003, Maharashtra
Source of Support: None, Conflict of Interest: None
| Abstract|| |
Introduction: Mouth breathing is one of the most deleterious oral habits with a prevalence of 4%–6% among children. Due to the wide range of comorbidities associated with mouth breathing, early diagnosis and prompt treatment is indispensable. At present, there are very few objective methods available for the diagnosis of mouth breathing. The present study was planned to evaluate a possible correlation between nasal index (NI) and nasal cavity volume (NCV) among nasal and mouth breathers (MB). In addition, the average NCV of nasal and MB was also computed. The foresight of this research was to establish the significance of NI as an objective diagnostic tool for mouth breathing. Methods: This cross-sectional study was conducted among 8–11-year-old children. The NI was determined using a digital Vernier caliper and NCV was calculated using dolphin imaging Results: There was a significant difference in NCV and nasal width (NW) in both groups, but no difference was seen in nasal height and NI. There was no statistically significant correlation between NCV and other parameters in both groups. Conclusion: The present study was a baseline analysis in this line. Even though this study did not reveal any significant correlation between both parameters, future studies are recommended to explore a plausible correlation.
Keywords: Cone-beam computed tomography, cross-sectional studies, mouth breathing, nasal cavity
|How to cite this article:|
Kalaskar R, Balasubramanian S, Kalaskar A. Correlation and comparative evaluation of nasal index and nasal cavity volume in nasal and mouth breathers: A preliminary cone-beam computed tomographic study. J Indian Soc Pedod Prev Dent 2022;40:48-54
|How to cite this URL:|
Kalaskar R, Balasubramanian S, Kalaskar A. Correlation and comparative evaluation of nasal index and nasal cavity volume in nasal and mouth breathers: A preliminary cone-beam computed tomographic study. J Indian Soc Pedod Prev Dent [serial online] 2022 [cited 2022 May 23];40:48-54. Available from: https://www.jisppd.com/text.asp?2022/40/1/48/343018
| Introduction|| |
Respiration is a vital function of the body which under normal physiologic conditions takes place through the nose. When the nose is supplemented by the mouth, this mixed breathing pattern is referred to as mouth-breathing syndrome. It is one of the most deleterious oral habits with a prevalence of 4%–6% among children., The etiology of mouth breathing ranges from local to systemic which are namely enlarged adenoids and tonsils, engorged turbinate, nasal and pharyngeal constriction, nasal polyp, deviated nasal septum, congenital choanal atresia, allergic rhinitis, and sinusitis.
Due to the wide range of comorbidities associated with mouth breathing, early diagnosis and prompt treatment is indispensable. It requires a multidisciplinary approach for management which includes otolaryngologist, pediatric dentist, orthodontist, pediatrician, psychologist, and speech pathologist. Even though the pediatric dentist may not be in a position to ameliorate the problem alone, they undoubtedly play a fundamental role in its early diagnosis and correction. At present, there are very few objective methods available for the diagnosis of mouth breathing.
It is a well-established fact that nasal breathing is essential for proper growth and development of the craniofacial complex. According to the functional matrix theory given by Melvin Moss, the bone grows in response to the functional demands of soft tissues that operate in association with that same bone. Hence, nasal airflow works as a continuous stimulus aiding the lateral growth of maxilla and lowering of the palate. This indicates a close relationship between nasal breathing and craniofacial morphology. The commonly observed dental and skeletal malocclusions associated with mouth breathing such as transverse maxillary deficiency and lowered tongue posture also influence the upper airway due to its intimate anatomic relationship. Hence, in addition to hampering craniofacial growth, it is also known to influence the upper airway morphology. These changes include nasal constriction, increase in nasal resistance, reduced nasal flow, recurrent ear and nasal infections, nasopharyngeal constriction, and lowered tongue posture causing narrowing of oropharynx.,
Just like nasal cavity volume (NCV) could be considered representative of internal nasal dimension, correspondingly, nasal index (NI) is representative of external nasal dimension. NI is a crucial anthropometric parameter of the external nose which exhibits ethnic, racial, gender, and climatic variations. It is the ratio of the greatest width of nasal aperture to the nasal height (NH) multiplied by 100. Therefore, the present study was planned to evaluate a possible correlation between NI and NCV among nasal and mouth breathers (MB). In addition, the average NCV of nasal and MB was also computed. The foresight of this research was to establish the significance of NI as an objective diagnostic tool for mouth breathing. In case, a significant difference in the NCV and NI between nasal and MB and a possible correlation between the two parameters could be established, this could aid as a stepping stone in determining the significance of NI as a diagnostic tool for mouth breathing.
| Methods|| |
After obtaining approval from the Institutional Ethics Committee (GDCHN/SS/7521/2018), the present cross-sectional (observational) study was conducted among 8–11-year-old children. Based on the Pearson correlation coefficient between NI and perimeter/area (-0.26) as derived by Yokley, the sample size was estimated to be 64. This study comprised two groups: nasal breathers (NB) and MB with each comprising 32 children. In both groups, males in the height range of 126–143 cm and weight 25–35 kg and females in the height range of 125–144 cm and weight 24–36 kg were included. Patients with a history of allergic rhinitis, sinusitis, moderate to severely deviated nasal septum, intranasal tumor and polyps, craniofacial anomalies, cases of midfacial trauma, and anterior and posterior crossbite and subjects not willing to participate were excluded from the study. Informed consent was obtained from parents in their vernacular language.
Based on the initial clinical examination, history elicited from parents, and the diagnostic assessment tests for mouth breathing, children were distributed into either of the two groups. First, the nasal width (NW) and NH were recorded using a digital Vernier caliper. NW was the interalar distance and NH was the distance from nasion to subnasale [Figure 1].
Thereafter, NI was calculated based on the following formula:,
Following this, cone-beam computed tomography (CBCT) scans were obtained as (DICOM) To be mentioned as DICOM files and the NCV was calculated using the Dolphin Imaging software version 11.95 (Dolphin Imaging and Management Solutions, Patterson Dental Supply, USA). Foremost, the orientation of the scans was set by adjusting the sagittal plane to the midline, i.e., mid-sagittal plane and the axial plane were adjusted to the center of the nasal cavity and the sinus/airway tool was used to calculate the airway volume. The sagittal draft was selected and the four points were marked based on the predetermined reference points, [Table 1] and [Figure 2]. These points were modified from the existing literature in order to ensure the exclusion of the paranasal sinuses. In addition, boundaries were marked on coronal and axial sections as well. The airway sensitivity was adjusted at 75 and this was standardized for every scan.
After data collection, a compilation was done on MS Office Excel Sheet (v 2019, Microsoft Redmond Campus, Redmond, Washington, United States). Thereafter, data were subjected to statistical analysis using Statistical Package for the Social Sciences SPSS (International Business Machines Corporation (IBM), Armonk, New York, USA). Normality of numerical data was checked using the Shapiro–Wilk test and was found that the data followed a normal curve; except for a single variable in a group; hence, parametric tests were used for comparison. The intergroup comparison between NB and MB was done using t-test, whereas the comparison of frequencies of categories of variables with groups was done using Chi-square test. The bivariate correlations were carried out to evaluate the correlation.
| Results|| |
The present study was conducted on 64 children (38 males and 26 females) with a mean age (years) of 9.78 (±1.099) NB and 9.75 (±1.270) in MB. The mean NCV, NW, NH, and NI were evaluated in both groups and intergroup comparisons were made at first. There was a statistically highly significant difference (p=0.000) in NCV in both groups, with the mean volume being 19637.94 (±2096.31) mm3 in NB [Figure 3]a and 14958.09 (±2287.52) mm3 in MB [Figure 3]b. NW also showed a significant difference in both groups, with the mean NW being 29.52 (±2.79) mm in NB [Figure 4]a and 27.91 (±3.19) mm in MB (P = 0.036) [Figure 4]b. However, NH and NI did not show any difference. The mean NH and NI were 44.03 (±3.41) mm and 67.32 (±7.24) and 44.31 (±3.31) mm and 63.38 (±8.99) in NB and MB, respectively [Table 2] and [Figure 5]a and [Figure 5]b.
|Figure 3: (a) Nasal cavity volume (mm3) in nasal breathers. (b) Nasal cavity volume (mm3) in mouth breathers|
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|Figure 4: (a) Nasal width (mm) in nasal breathers. (b) Nasal width (mm) in mouth breathers|
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|Figure 5: (a) Nasal height (mm) in nasal breathers. (b) Nasal height (mm) in mouth breathers|
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Based on the values obtained for NI, the children were dived into five categories based on the morphology of their nose. Among 64 children, majority presented with a leptorrhine type followed by mesorrhine and hyperleptorrhine type. None of the children in the present study portrayed platyrrhine and hyperplatyrrhine type of nose. Intergroup comparison showed a significant difference in nose type with a relatively higher frequency of leptorrhine in NB and hyperleptorrhine in MB (p=0.019).
The correlation of NCV with NW, NH, and NI did not show a significant correlation in the entire sample as well as in individual groups [Table 3] and [Figure 6]a and [Figure 6]b.
|Table 3: Correlation of nasal cavity volume (mm3) in nasal and mouth breathers|
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|Figure 6: (a) Correlation of nasal index with nasal cavity volume in nasal breathers. (b) Correlation of nasal index with nasal cavity volume in mouth breathers|
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| Discussion|| |
Nasorespiratory function and its relationship with craniofacial growth is of great interest from the 1980s to the present. It not only endorses the basic biologic relationship of form and function but is also of great practical concern to various disciplines of healthcare. Mouth breathing is basically inhalation and exhalation through the mouth and when it is chronically practiced, it constitutes an abnormal respiratory function. It leads to several deleterious consequences on the physical, physiochemical, cognitive, and behavioral aspects and hampers the overall quality of life of the child. Furthermore, it also manifests into long-term complications in adulthood as well. Milanesi et al. assessed the effect of childhood mouth breathing on the ventilatory function of adults and reported a reduction in lower respiratory muscle strength and functional exercise capacity.
According to Fujimoto et al., mouth breathing is a result of impediment of nasal breathing which may be due to anatomical predisposition or obstructive causes such as allergic rhinitis, sinusitis, nasal polyp, adenoid and tonsillar hypertrophy, deleterious buccal habits, and generalized muscular hypotonicity to name a few. However, in certain cases, the habit continues to persist despite the removal of these mechanical causes. This could be attributed to maxillary as well as upper airway constriction.
Impaired nasal breathing has been frequently associated with a transverse maxillary deficiency in as high as 47% of cases. Few researchers have established a correlation between impaired nasal breathing and maxillary constriction, with one being the cause as well as consequence of the other. Mouth breathing forces an open mouth posture which may be responsible for transverse maxillary deficiency. Furthermore, since a constricted maxilla leads to a narrower dimension of nasal cavity, it may cause an impaired breathing. Warren et al. conducted a study on adults to assess the relationship between nasal impairment and breathing and to determine the switching range from nasal to mouth breathing in order to quantify mouth breathing. They concluded that nasal airway with cross-sectional area <0.4 cm2 was constituted as impairment and 97% of adults in this category were noted to be MB to a certain extent.
The present study aimed to primarily explore the correlation between NI and NCV in nasal and MB. Franciscus and Long proposed that the width and breadth of the external nose may be related to the internal nasal dimensions, but this proposition had to be tested. A systematic review was conducted by Leong and Eccles. which attempted to evaluate whether the shape and size of nose (NI) were merely a matter of esthetics or did they truly have any physiological significance. They observed that there existed little evidence to support the influence of NI on nasal physiology and disease. In our study, NCV did not show a significant correlation with NW, NH, and NI in both groups. The findings of our study were in accordance with Yokley who reported a negative correlation of P/A (proxy of SA/V) with NI and NH which were not statistically significant. This can be inferred as NCV showing a weak positive correlation with NI and NH which were not statistically significant, similar to our results of NB. However, they reported a significant weak correlation between NCV and NW which was not seen in our study. Another study was conducted by Gupta et al. who attempted to find a correlation between nasal airway volume and craniofacial morphology using CBCT in 18–28-year-old adults. They observed that NCV did not have a significant correlation with facial index (width/length ratio) but significantly correlated with width of the face.
Similar studies have been conducted in the past which have attempted to establish a correlation between external nasal morphology and nasorespiratory function. Majority of these studies have correlated NI with nasal airway resistance (NAR). Literature has proven a close relationship between NAR and NCV as well. Zhang et al. conducted a cross-sectional study among adults with nasal obstruction. They observed that NAR and NCV showed a negative correlation in majority of subgroups. This relationship is relevant for this research.
Spalding and Vig correlated external nasal morphology with nasal function in randomly chosen subjects aged 14–46 years with no prior assessment of nasal function. The external nasal morphological measurements were limited to the orifice and they concluded that none of the external morphologic parameters correlated with nasal respiratory function. Another interesting research was conducted by Doddi and Eccles. wherein they aimed to explore the correlation between NI and total NAR. They hypothesized that narrow leptorrhine noses may have greater resistance to airflow than the broader platyrrhine noses, but they also failed to derive any correlation between NI and NAR.
In addition, the present study also attempted to evaluate the difference in NCV and NI among NB and MB. In this study, there was a statistically highly significant difference in NCV between both groups with lesser volume among MB. Literature search revealed very few studies which attempted to compare the airway volumes between nasal and MB. Zavras et al. used AR to determine whether there existed any difference in nasal geometry between NB and MB. They observed a statistically significant difference in total nasal volumes in both groups with lower values in MB. This finding was in accordance with our study. The present study utilized CBCT for evaluation of NCV owing to its good accuracy, reproducibility, reliability, and isotropic CBCT voxels., Tikku et al. compared the overall maxillary sinus volume in normal and MB aged 12–14 years using CBCT. The mean volume was significantly different in both groups, i.e., 12.712 (±1.619) cm3 and 11.598 (±1.520) cm3 in NB and MB, respectively. A similar study was performed in adults by Agacayak et al. and they also observed a statistically significant difference between both groups with lower values in MB. Alves et al. attempted to assess the pharyngeal airway in nasal and MB and concluded that volume was significantly higher in NB. Another study conducted by Lione et al. compared the palatal surface area and volume in NB and MB with a mean age of 8.5 years. They also reported a significantly lesser palatal surface area as well as volume in MB. These findings regarding the difference in airway volume between NB and MB which are documented in the literature were confirmed in the present research.
The mean NI in this study was 67.32 (±7.24) in NB and 63.38 (±8.99) in MB. There was no statistically significant difference in NI between both groups. However, there was a significant difference in nose types in both groups with a relatively higher frequency of leptorrhine in NB and hyperleptorrhine in MB. Cappellette et al. assessed the effects of rapid maxillary expansion (RME) on transverse and vertical dimensions of the nasal cavity. The sample comprised MB with a mean age of 9.6 years and children with enlarged adenoids and tonsils, intranasal tumors, or polyps were excluded from the study (exclusion criteria similar to the present study). The authors concluded that there was a significant increase in NW, NH, and nasal area post RME. This showed that there could be a significant difference in NW in nasal and MB, which was seen in the present study. However, no difference in NH was observed in the present study. A similar study was conducted by Badreddine et al. wherein they retrospectively evaluated the effect of RME on skeletal and soft-tissue structures of nose of MB. They observed that the experimental group showed a significant increase in both NW and NH, whereas the control group showed no change. A photographic analysis of facial changes post RME was performed by Berger et al. and they observed a significant increase in NW but NH did not show any enduring changes.
In the present research, NCV showed a positive correlation with NI in NB, whereas MB showed a negative correlation. However, these correlations were not statistically significant. But if NB and MB show different relationships between these two parameters, then it would negate the applicability of NI as a diagnostic tool for mouth breathing. Hence, this warrants further research to firstly establish this correlation in normal breathers followed by MB.
Limitations and future perspective
The aforementioned literature and the findings of this study show that there is no correlation between NI and NCV. However, there are few limitations in this research which are low sample size, no standardization of nose type, and ethnic groups. Hence, we recommend that in future, such studies should first be conducted in a larger set of normal breathers by standardizing the nose type at first so that we can assess the range of volume obtained for a single nose type. This design would aid in a better understanding of a plausible correlation between NI and NCV.
| Conclusion|| |
The results of this study showed that there was no statistically significant correlation between NCV and NI, NW, and NH. There was a statistically significant difference in NCV and NW between NB and MB. However, NH and NI did not show any difference between both groups. In addition, comparison of nose types between both groups revealed a statistically significant difference with a relatively higher frequency of leptorrhine in NB and hyperleptorrhine in MB.
The present research was a baseline analysis in this line with few limitations. We recommend that in future, studies should first be conducted in a larger set of normal breathers alone by standardizing the nose type. This design would aid in a better understanding of a plausible correlation between NI and NCV.
Declaration of patient consent
The authors certify that they have obtained all appropriate patient consent forms. In the form the patient(s) has/have given his/her/their consent for his/her/their images and other clinical information to be reported in the journal. The patients understand that their names and initials will not be published and due efforts will be made to conceal their identity, but anonymity cannot be guaranteed.
We duly acknowledge Dolphin Imaging and Management Solutions, USA, and Essential Dental Products, New Delhi, for allowing usage of Dolphin Imaging software.
Financial support and sponsorship
Conflicts of interest
There are no conflicts of interest.
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[Figure 1], [Figure 2], [Figure 3], [Figure 4], [Figure 5], [Figure 6]
[Table 1], [Table 2], [Table 3]