Introduction

For diagnosing and treating morphological and functional abnormalities in the masticatory system and surrounding regions, a better knowledge of the coordinating processes that support normal craniofacial development is crucial. The association between head posture and craniofacial morphology is one element that might be relevant in this context. The anthropological literature has shown a great deal of interest in the issue of whether head morphology and posture are related. The evolutionary implications of the simultaneous development of the human brain, cranial base flexion, and erect posture have received special attention. The evidence of altered craniofacial morphology in animals after intentionally induced changes in body position has provided experimental support for the existence of a link between morphology and posture. 1, 2 As early as 1926, a connection was made between neck position and malocclusion. In a study on the impact of upper airway obstruction in children, Schwartz concluded that malocclusion develops when a youngster is unable to breathe normally. This theory was supported by the observation that individuals with airway blockage exhibited a forward head posture, or a forward cervical inclination along with an extended head position(extended cranio-cervical angle). Not only has the association between head position and malocclusion been shown in patients with airway blockage, but also in those with regular breathing patterns. 3, 4, 5, 6 A pattern of correlation between head and neck posture and malocclusion was shown in research by Solow and Sonnesen 7, which involved individuals with severe malocclusions and no airway issues. They concluded that a more extended cervical inclination or forward-postured neck was seen in those with severe malocclusion. Researchers examining the relationships between NHP, cranio-cervical posture, and craniofacial morphology in various populations have discovered that ethnic origin may have an impact on head and neck position. Given the correlation between the morphology and dimensions of the upper cervical spine and the variations in craniofacial morphology observed among individuals of diverse ethnic backgrounds, it is plausible that there exist variations in upper spine morphology among different ethnic groups. According to a study by Banerjee et al. 8, people of Indian descent differed from people of Asian and European/American descent in a few morphological parameters in the cervical spine area. Furthermore, because earlier research 9, 10, 11, 12, 13, 14 has demonstrated a correlation between the morphology and dimensions of the upper spine and the morphology of the mandible and craniofacial morphology, the purpose of this study was to evaluate this relationship in the Indian population and ascertain how it differs between various growth patterns and classes of skeletal malocclusion.

Materials and Methods

Method of Investigation

With the patient in the natural head position, all radiographs were acquired using a standard focus-film distance and a distance from the film to the medial plane. To reduce inter-examiner variability, the lead investigator manually traced the individuals' lateral cephalograms on acetate paper. The reference points used are described in Table 1. Reference variables used for cephalometric analysis are described in Table 2. Sagittal skeletal discrepancy was assessed with the help of 3 angular and 3 linear measurements.(Table 2 and Figure 1). Growth pattern was evaluated by assessing 3 angular measurements and 1 ratio(Table 2 and Figure 2). 4 angular measurements were used to determine relationship between head and cervical posture.(Table 3 and Figure 3). These variables were then correlated.

Results

Cephalometric analysis was done on 98 patients of Indian ethnicity. The mean SNA of the study population was 81.7 ± 3.10 and the mean SNB 77.04±4.53. The mean ANB angle was 5.04±2.10 and WITS analysis was 2.45±2.06. The mean NA linear was -8.63±4.03 and NB linear was -11.02±6.83. The mean Y axis was 62±4.27 and Gonial angle was 124.5±6.7. The mean FMPA of study population was 25.23±5.99 and Jarabak’s ratio was 60.86±80.70.

The mean NSL/OPT of the study population was 100.72±8.09 and the main NSL/CVT was 107.22±6.80. The relationship between Cranio-cervical Parameters and Sagittal Discrepancies exhibited that there was a Negative association between NSL/OPT and SNA, SNB, NA Linear and NB Linear values whereas there was a positive association between NSL/OPT and ANB, Wits. It was observed that this relationship was statistically significant between NSL/OPT and ANB.

When NSL/CVT were tried to be associated with sagittal discrepancies it exhibited that there was a positive association between NSL/CVT-SNA, NSL/CVT- ANB, NSL/CVT-Wits, NSL/CVT- NA Linear and this relationship was statistically significant between NSL/CVT and ANB. But there was no statistically significant link(p>0.05) between these two variables. Y-Axis, FMPA, and NSL/CVT-Gonial angle showed a positive correlation, but NSL/CVT-Jarabak's Ratio and Gonial angle showed a negative correlation. Nevertheless, the statistical significance of this relationship was maintained at p>0.05.

Figure 1

a. SNA b. SNB c. NA linear d. NB linear e. ANB f.Wits appraisal

Figure 2

a. Y axis b. Gonialangle c. FMPA d. Jarabak’s ratio

Figure 3

Head and cervical postural variables

Figure 4

a.Craniocervical angle(NSL-OPT) increased in a patient having Class IImaxillomandibular relationship(> ANB) b. Craniocervical angle( NSL-OPT)decreased in a patient having prognathic jaw bases c. Craniocervical extensionseen in a patient with vertical growth pattern with increased FMPA and Y- Axis d. Craniocervical flexion seen in a patient with horizontal growth pattern.

Discussion

The current study investigated the connection between sagittal skeletal discrepancies, posture, and craniocervical morphology in the Indian population. The lateral cephalograms of ninety-eight Indian patients were examined. With the patient in the Natural Head Position(NHP), all radiographs were acquired using a standard focus-film distance and a distance from the film to the medial plane. Cooke et al.,(1990) 15 and Lundstrom et al.,(1995) 16 demonstrated the better stability and reproducibility of NHP. The study examined subjects with Class I, Class II, and Class III skeletal patterns that showed average, horizontal, and vertical growth patterns. Only participants who had reached stage 6 of the CVMI, or skeletal growth, as defined by Hassel and Farman 17, were included in the study. A total of six angular, three linear and one ratio was analysed as part of this study for evaluation of growth pattern and sagittal discrepancies. The head and postural variables NSL/OPT, NSL/CVT, NL/OPT, and NL/CVT were examined. Sonessen and Solow's investigation yielded credible and repeatable results for these variables. 7 The association between head posture and the various kinds of malocclusion has been discussed in earlier research. In one study, 61 children with poor neck posture were compared to their controls. The results showed that the children with poor posture had longer faces and a higher prevalence of Angle's Class II malocclusion. In a study conducted by Balters, it was also shown that Class II malocclusion and head posture are related. Class II individuals had more severe spine issues than those in other classes of malocclusion. It has previously been shown that there are correlations between head position and upper airway obstruction in patients with OSA as well as between craniofacial morphology and head posture. Recent research has demonstrated correlations between head posture and cervical vertebral column fusion, between patients with OSA and cervical vertebral column fusion, and between craniofacial morphology, especially the cranial base.

In the current investigation, variations in craniocervical angles were observed among participants with Class I, Class II, and Class III malocclusion. A negative correlation was found between NSL/OPT and SNA, SNB, NA Linear, and NB Linear values, while a positive correlation was found between NSL/OPT with ANB and Wits in the link between Cranio-cervical Parameters and Sagittal Discrepancies.

The correlation between NSL/OPT and ANB was found to be statistically significant. When NSL/CVT was attempted to be linked to sagittal discrepancies, it was shown that NSL/CVT and ANB were positively correlated, as were NSL/CVT-SNA, NSL/CVT-ANB, NSL/CVT-Wits, and NSL/CVT-NA Linear. This relationship between NSL/CVT and ANB was statistically significant. The correlation between cranio-cervical characteristics and growth patterns showed that NSL/OPT-FMPA, NSL/OPT-Y-Axis, and NSL/OPT-Gonial angle were negatively correlated with each other, whereas NSL/OPT-Jarabak's Ratio was positively correlated. This link, however, did not reach statistical significance(p>0.05). Though this relationship was statistically significant(p>0.05), there was a negative association between NSL/CVT-Gonial angle and NSL/CVT-Jarabak's Ratio and a positive association between NSL/CVT-Y-Axis and NSL/CVT-FMPA. Patients presenting with a Class II maxillomandibular connection showed larger cranio-cervical angulation. Maxillary and mandibular prognathism increased with a decrease in craniocervical angles. Referring to (Figure 4), there was a more forward head position and a straighter cervical spine curve in Class III subjects compared to Class I. Huggare and Harkness's(1991) 6 conclusions were consistent with these, but they contradicted those put out by Schwartz(1926) 5 and Rocabado et al.,(1982). 18 Racial differences and differences in sample makeup could be the cause of the disparate results observed in these researches. In contrast to growth patterns, the craniocervical angles increased as the Jarabak's ratio fell, suggesting that patients with vertical growth patterns are more likely to exhibit an extended head posture. As the FMA and Y-axis grew, so did the craniocervical angles. To extrapolate these results to larger populations, more research needs to be done. Further research should consider the significant influence that racial and ethnic diversity have on cephalometric norms.

Conclusion

The following observations were made while examining the connection between sagittal skeletal discrepancies and head posture in the Indian population:

Source of Funding

None.

Conflict of interest

None.