The present study was conducted with the permission of Institutional Ethics Committee of Sumandeep Vidyapeeth University with protocol number SVIEC/ON/DENT/RP/1526, dated 17/10/2014. The total of 300 voluntary healthy participants, above 18 years of age were included in the study whereas participants with head & neck anomalies, intra-osseous pathologies, history of trauma/surgery, images with positioning errors, magnification or distortion were excluded from the study. After obtaining informed consent form in local language, each participant was subjected to CT scan of head and neck region (sagittal view). The shapes of soft palate was classified according to You M et al., [6] - Type 1: Leaf shape [Table/Fig-1a], Type 2: Rat Tail shape [Table/Fig-1b], Type 3: Butt like shape [Table/Fig-1c], Type 4: Straight line shaped [Table/Fig-2a], Type 5: Distorted/S-shape [Table/Fig-2b] and Type 6: Crooked shape [Table/Fig-2c]. The morphometric analysis for antero-posterior and supero-inferior length of soft palate was performed using mouse driven method i.e. by moving the mouse and drawing lines between the selected points on the sagittal sections of CT scan by using Syngo CT 2009E software [Table/Fig-3a,b].

[Table/Fig-1a-c]:

Shows Sagittal section of computed tomography scan- (a) showing leaf shape, (b) rat-tail shape and (c) butt-like of soft palate (yellow circle)

[Table/Fig-2a-c]:

Shows Sagittal section of computed tomography scan - (a) showing straight line shape, (2) S-shape and (c) crook shape of soft palate (yellow circle)

[Table/Fig-3a,b]:

Shows Sagittal section of computed tomography scan - (a) showing measurements of soft palate antero-posteriorly and (b) supero-inferiorly

The measurements were recorded in millimetres. The collected data was analysed using SPSS software version 16 and the test applied were one-way ANOVA, Independent t-test, Chi-square and Karl Pearson’s co-relation coefficient.

In the present study, the age of participants ranged from 18-80 years with mean of 39.51+14.64. There were total 300 participants including equal number of male (n=150) and female (n=150) participants. The maximum numbers of participants were between the age group of 21-30 years.

Out of all the type of soft palate, the maximum number of participants had Butt type of soft palate (38.7%) [Table/Fig-4] and was seen more or less equal in male (19.7%) and female (19%) participants. Correlation of shape of soft palate with age group and gender were analysed by using Chi-square test and were statistically not significant (p>0.05) [Table/Fig-5,6].

[Table/Fig-4]:

Distribution of frequency of shape of soft palate

It was distinctly noted that the mean values for antero-posterior and supero-inferior length of various shapes of soft palate in both male and female when analysed by using one-way ANOVA test, the values were highly significant (p<0.05) [Table/Fig-7,8].

It was observed that the minimum and maximum mean of antero-posterior length of soft palate was 24.20 mm and 37.80 mm respectively whereas the minimum and maximum mean of supero-inferior length was 06.10 mm and 14.80 mm respectively [Table/Fig-9].

In the present study, when the dimensions were co-related with gender, it was observed that the mean antero-posterior length of soft palate in males (30.69±3.42 mm) was more than females (29.92±3.32 mm), which was statistically significant (p<0.05). But, the mean supero-inferior length of soft palate in males (10.67±1.78 mm) was less than females (10.78±1.64 mm), which was statistically not significant (p>0.05). These values were statistically analysed by using independent t-test [Table/Fig-10].

It was noted that Karl Pearson’s Co-relation Coefficient value when applied between dimensions and different age groups, it was 0.016 and 0.011 respectively for antero-posterior and supero-inferior length. The p-values were statistically not significant (p>0.05) [Table/Fig-11].

Soft palate is formed by interweaving of muscles: tensor veli palatini, levator veli palatini, palatoglossus and palate-pharyngeus [1,2,10]. It plays a significant role in important functions of head and neck region. Soft palate can be studied on lateral or sagittal sections of conventional radiographs and advanced imaging. CT scan is an important and reliable tool for morphometric analysis of soft palate [7,8].

In the present study, the ‘Butt’ like shape of soft palate was the most frequent type (38.7%) and ‘Leaf’ type (28.7%) was the second common type. Various studies on lateral cephalogram have put forward ‘Leaf’ type as the most commonest [3,5,6,13]. This may be due to population related trait and study sample size. With intersex difference in the soft palate, we observed that the percentage of butt-like shape was more or less equal in males (19.7%) and females (19%) which was statistically not significant (p>0.05). Our result did not simulate with the studies of Kumar D et al, Guttal K et al., You M et al., and Kaur S et al., wherein the Leaf type was equally common in males and females [3,5,6,13], but Rat type was the most common type in the study of Praveen B. et al., [11].

The growth of soft palate takes place in antero-posterior and supero-inferior directions. In the early years of life the growth is rapid. The growth curve takes place by the age of 1.5 to 2 years whereas by the age of 4 to 5 years the upward growth ceases [1]. In our study, the age and the morphology of soft palate co-relation was statistically not significant (p>0.05) which proves that there is no significant relationship between age and growth of soft palate. We noted that the overall mean of antero-posterior length (30.31±3.39 mm) was more than the supero-inferior length (10.72±1.71 mm) of soft palate.

In our study, the co-relation of gender with morphology of soft palate gave surprising results. The co-relation of gender with different shape of soft palate was statistically not significant (p>0.05). The co-relation of antero-posterior length and supero-inferior length in different shapes of soft palate was statistically highly significant (p<0.001). The overall mean of antero-posterior length was more in males (30.69±3.42 mm) than females (29.92±3.32 mm), which was statistically significant (p<0.05). But, the overall mean of supero-inferior length was less in males (10.67±1.78 mm) as compared with females (10.78±1.64 mm), which was statistically not significant (p>0.05). These type of observation did not match with the existing studies [3,5,6,11].

The results of our study indicates that soft palate is an important structure in velo-pharyngeal closure and provides information for diagnosis, prognosis and treatment in individuals with cleft palate and in obstructive sleep apnoea syndrome.

The morphometric analysis of soft palate on CT scan has helped us to understand the multiplicity of velar morphology. Our study may help as a reference for research pertaining to cleft palate/ velo-pharyngeal closure and in obstructive sleep apnoea syndrome. The results may differ geographically and depending on the oro-pharyngeal structure.