Abstract
Aim
The aim of this study is to deduce the cephalometric norms for orthognathic surgery in Chhattisgarh population by comparing with the analysis given by Burstone et al. for hard tissue and Legan and Burstone for soft tissue.
Materials and Methods
Lateral cephalograms of 70 subjects (35 male and 35 female) aged between 18 and 25 years having class I malocclusion, acceptable facial profile were recorded and traced for the analysis and interpretation using landmarks and values given by Burstone’s analysis were obtained and further comparison was done for the values obtained for the Chhattisgarh population with that of Caucasians.
Results
Findings of our study were statistically significant as considerable skeletal differences were found between men and women of Chhattisgarh origin compared to Caucasian origin. Many contrasting findings were discovered in our study group from that of the Caucasian population with respect to the maxillo-mandibular relation, vertical hard tissues parameters. Less differences were found in horizontal hard tissue parameters and dental parameters among the two study populations.
Conclusion
The differences found must be kept in consideration during analysis of cephalogram for orthognathic surgeries. Values obtained can be considered to assess deformities and surgical planning to achieve optimal results for Chhattisgarh population.
Clinical Significance
The understanding of normal human adult’s facial measurements are important to assess craniofacial dimensions and facial deformities and to monitor postoperative results in orthognathic surgeries. Cephalometric norms can be a beneficial abet to clinicians in ascertaining the patient abnormalities. Norms define the ideal cephalometric measurements for patients based on factors such as age, sex, size and race. It has become apparent over years that significant variations do occur among and between the individuals of different racial origins.
Keywords: Cephalometric norms for Chhattisgarh population, Caucasians, Burstone, Legan and Burstone, Orthognathic surgery
Introduction
The proficiency of standard dentofacial pattern of adults from the different ethnicity is essential for the clinical and research purpose [1]. The disparities of the facial skeleton can be dealt with the sub-specialty of oral and maxillofacial surgery [2]. To aid in the orthognathic surgery, numerous methods and different types of analysis have been reported in the literature [3]. The cephalometric norms from the specific region and racial origin help us to provide specific values for diagnosis and treatment planning for orthognathic surgery. Cephalometric norms can be a beneficial abet to clinicians in ascertaining the patient abnormalities. Norms define the ideal cephalometric measurements for patients based on factors such as age, sex, size and race. It has become apparent from several studies conducted over years that significant variations do occur among and between the individuals of different racial origin [4]. The most readily and widely accepted analysis norms are the ones deduced by Burstone et al. [5] and Legan and Burstone [6] for the hard and soft tissues, respectively. As these were done on the Caucasian population and so the use of developed norms may be inadequate for the Indian population. So, the norms were deduced for the Indians too from different regions such as south India [7], north India [2], and Central India [3]. Central India itself being a diverse region with number of races and ethnicity and thus several dentofacial patterns requires specialized cephalometric appraisal for orthognathic surgery (COGS). Chhattisgarh which is located in the east-central India has immense diversity as it comprises of tribal community; the majority of tribal population is Gonds or Adivasi group who have descended from Indus valley civilization with several sub-tribal population who mostly live in woods or forests and hills. Therefore, this study is designed to deduce the norms for Chhattisgarh population since no such norms have been developed for this population till date. Norms are deduced by employing the cephalometric landmarks, dental and skeletal measurements given by Burstone that can be utilized for better understanding and management of dentofacial deformities for those belonging to Chhattisgarh state.
Materials and Methods
The study was carried out in the Department of Oral and Maxillofacial Surgery, Chhattisgarh Dental College and Research Institute, Rajnandgaon Chhattisgarh, after obtaining the due ethical approval from instituitional review board. A total of 70 lateral cephalograms (35 male and 35 female) who met with the inclusion and exclusion criteria were obtained. Lateral cephalograms were taken in Standard head position with teeth in occlusion. All the lateral cephalograms obtained were of normal adults from the different parts of Chhattisgarh state. The films were then traced manually on 0.25 mm lead acetate sheets with 3H pencil. Cephalometric landmarks were identified and marked according to the one given by Burstone et al. [5] and Legan and Burstone [6] in their articles. Analysis was performed and values for several hard tissue and soft tissue parameters were recorded keeping the Burstone et al. [5] and Legan and Burstone [6] values as basis.
Inclusion criteria
People with Chhattisgarh Ethnicity.
Age group 18–25 years.
Class-I occlusion.
Minimal crowding, rotations and spacing that can be neglected.
Presence of all permanent dentition with proper intercuspation.
Exclusion criteria
Major Skeletal or dental discrepancy.
Previous maxillofacial trauma.
Any relevant history of orthodontic or orthognathic interventions or plastic surgery of oral and maxillofacial region.
Statistical Analysis
Statistical analysis was carried out using IBM SPSS software version 23 by Student’s t test. A value of p < 0.05 was considered statistically significant.
Result
The mean values with standard deviation of hard tissue of Chhattisgarhi male and female, respectively, along with their comparative results with that of Caucasians are tabulated in Tables 1 and 2. The soft tissue analysis including their mean values, standard deviation and the comparative results with Caucasians is tabulated in Table 3.
Table 1.
Hard tissue analysis—MALE comparison-Caucasians and Chhattisgarh ethnic group
| Variables | Caucasians | Chhattisgarhis | p value | t value | ||
|---|---|---|---|---|---|---|
| Mean | SD | Mean | SD | |||
| Cranial base | ||||||
| Ar–Ptm (llHp) | 37.1 | 2.8 | 36.7609 | 6.1633 | 0.8349 | 0.2095 |
| Ptm–N (llHP) | 52.8 | 4.1 | 48.6066 | 9.0824 | 0.0848 | 1.7593 |
| Horizontal | ||||||
| N–A–Pg (angle) | 3.9 | 6.4 | 5.8351 | 6.5517 | 0.3291 | 0.9856 |
| N–A (llHP) | 0.0 | 3.7 | 3.6289 | 7.1561 | 0.0623 | 1.9079 |
| N–B (llHP) | − 5.3 | 6.7 | − 2.383 | 9.897 | 0.2902 | 1.0693 |
| N–Pg (llH P) | − 4.3 | 8.5 | − 0.4391 | 10.4888 | 0.2033 | 1.2894 |
| Vertical | ||||||
| N–ANS (Prp–Hp) | 54 | 3.2 mm | 49.5006 | 8.9581 | 0.0576 | 1.9441 |
| ANS–Gn | 68.6 | 3.8 mm | 65.3126 | 11.7317 | 0.2811 | 1.0898 |
| PNS–N (Prp–HP) | 53.9 | 1.7 mm | 50.6497 | 7.2064 | 0.0825 | 1.7726 |
| MP–HP | 24 | 5 | 19.3574 | 7.665 | 0.0317 | 2.2108 |
| UI–NF (Prp–HP) | 30.5 | 2.1 mm | 28.9769 | 4.756 | 4.756 | 1.2225 |
| U6–NF (Prp–HP) | 26.2 | 2 mm | 23.3023 | 3.9079 | 0.0074 | 2.7928 |
| L1–MP (Prp–HP) | 45 | 2.1 mm | 42.6026 | 8.7372 | 0.2864 | 1.0779 |
| L6–MP (Prp–HP) | 35.8 | 2.6 mm | 33.892 | 6.9699 | 0.2957 | 1.057 |
| Maxilla-Mandible | ||||||
| PNS–ANS (llHP) | 57.5 | 2.5 mm | 54.286 | 9.096 | 0.173 | 1.3828 |
| Ar–Go (linear) | 52.0 | 4.2 mm | 54.6977 | 15.1691 | 0.0001 | 16.4832 |
| Go–Pg (linear) | 83.7 | 4.6 mm | 76.5811 | 13.7029 | 0.0492 | 2.0171 |
| B–Pg (ll MP) | 8.9 | 1.7 mm | 6.5034 | 2.8028 | 0.0027 | 3.1551 |
| Ar-Go_Gn (angle) | 119.1 | 6.5 | 121.086 | 10.5863 | 0.4928 | 0.691 |
| Dental | ||||||
| OP–HP (angle) | 6.2 | 5.1 | 11.4594 | 23.8464 | 0.3893 | 0.8686 |
| A–B (Op) | − 1.1 | 2.0 | 3.0449 | 4.1771 | 0.0838 | 1.7651 |
| UI–NF (angle) | 111 | 4.7 | 124.2403 | 13.2726 | 0.0003 | 3.8629 |
| L1–MP (angle) | 95.9 | 5.7 | 98.666 | 13.976 | 0.451 | 0.7599 |
The values in bold define the significant p values (p < 0.05) for the given parameters
ll parallel, Prp perpendicular, Ar Articulare, PTM Pterygomaxillary fissure, N Nasion, A Subspinale, B Supramentale, Pg Pogonion, Go Gonion, Gn Gnathion, HP Horizontal plane, MP mandibular plane, OP occlusal plane, ANS anterior nasal spine, PNS posterior nasal spine, NF nasal floor, U1 long axis of upper incisors, L1 long axis of lower incisors, Upper 6 mesiobuccal cusp tip of maxillary first molar, Lower 6 mesiobuccal cusp tip of mandibular first molar
Table 2.
Hard tissue analysis–FEMALE comparison-Caucasians and Chhattisgarh ethnic group
| Variables | Caucasians | Chhattisgarhis | p value | t value | ||
|---|---|---|---|---|---|---|
| Mean | SD | Mean | SD | |||
| Cranial base | ||||||
| Ar–Ptm (llHp) | 32.8 | 1.9 | 36.6 | 5.882 | 0.0153 | 2.5128 |
| Ptm–N (llHP) | 50.9 | 3 | 49.58 | 5.646 | 0.3848 | 0.877 |
| Horizontal | ||||||
| N–A–Pg (angle) | 2.6 | 5.1 | 5.817 | 4.904 | 0.0368 | 2.1471 |
| N–A (ll HP) | − 2 | 3.7 | 2.049 | 4.974 | 0.0055 | 2.9032 |
| N–B (ll HP) | − 6.9 | 1.3 | − 9.571 | 21.417 | 0.6223 | 0.4957 |
| N–Pg (ll HP) | − 6.5 | 5.1 | − 5.149 | 8.675 | 0.5665 | 0.5771 |
| Vertical | ||||||
| N–ANS (Prp–Hp) | 50 | 2.4 mm | 49.291 | 6.499 | 0.6752 | 0.4215 |
| ANS–Gn | 61.3 | 3.3 mm | 62.971 | 8.712 | 0.4629 | 0.7399 |
| PNS–N (Pr–HP) | 50.6 | 2.2 mm | 49.674 | 6.039 | 0.556 | 0.5929 |
| MP–HP | 23 | 5 | 24.1 | 6.85 | 0.568 | 0.5748 |
| UI–NF (Prp–HP) | 27.5 | 1.3 mm | 28.38 | 3.717 | 0.3634 | 0.9174 |
| U6–NF (Prp–HP) | 23 | 1.3 mm | 23.183 | 2.386 | 0.7754 | 0.2869 |
| L1–MP (Prp–HP) | 40.8 | 1.8 mm | 38.969 | 5.39 | 0.1932 | 1.3193 |
| L6–MP (Prp–HP) | 32 | 1.9 mm | 30.354 | 3.805 | 0.1088 | 1.6334 |
| Maxilla-Mandible | ||||||
| PNS–ANS (llHP) | 52.6 | 3.5 mm | 52.646 | 6.239 | 0.9782 | 0.0275 |
| Ar–Go (linear) | 46.8 | 2.5 mm | 49.509 | 7.484 | 0.1661 | 1.4057 |
| Go–Pg (linear) | 74.3 | 5.8 mm | 75.6 | 7.716 | 0.5515 | 0.5996 |
| B–Pg (ll MP) | 72 | 1.9 mm | 6.18 | 3.036 | 0.0001 | 79.6368 |
| Ar–Go–Gn (angle) | 122 | 6.9 | 159.294 | 210.671 | 0.4847 | 0.704 |
| Dental | ||||||
| OP–HP (angle) | 7.1 | 2.5 | 8.36 | 5.739 | 0.4056 | 0.839 |
| A–B (Op) | − 0.4 | 2.5 | 1.4 | 3.954 | 0.1014 | 1.6697 |
| UI–NF (angle) | 112 | 5.3 | 120.714 | 9.048 | 0.3449 | 0.9537 |
| L1–MP (angle) | 95.9 | 5.7 | 97.423 | 15.252 | 0.7015 | 0.3855 |
The values in bold define the significant p values (p < 0.05) for the given parameters
ll parallel, Prp perpendicular, Ar Articulare, PTM Pterygomaxillary fissure, N Nasion, A Subspinale, B Supramentale, Pg Pogonion, Go Gonion, Gn Gnathion, HP horizontal plane, MP mandibular plane, OP occlusal plane, ANS anterior nasal spine, PNS posterior nasal spine, NF nasal floor, U1 long axis of upper incisors, L1 long axis of lower incisors, Upper 6 mesiobuccal cusp tip of maxillary first molar, Lower 6 mesiobuccal cusp tip of mandibular first molar
Table 3.
Soft tissue analysis—MALE and FEMALE comparison-Caucasians and Chhattisgarh ethnic group
| Variables | Caucasians | Chhattisgarhis | p value | t value | ||
|---|---|---|---|---|---|---|
| Mean | SD | Mean | SD | |||
| Facial form | ||||||
| Facial convexity angle (G–Sn–Pg′) (angle) | 12 | 4 | 13.7859 | 5.9415 | 0.0934 | 1.6928 |
| Maxillary prognathism (G–Sn) (II HP) | 6 | 3 | 6.6481 | 4.6184 | 0.4278 | 0.7959 |
| Mandibular prognathism (G–Pg′) (II HP) | 0 | 4 | 9.2826 | 5.4925 | 0.0001 | 9.357 |
| Vertical height ratio (G–Sn/Sn–Me′) (Perp. HP) | 1 | – | 1.0714 | 0.8643 | 0.6031 | 0.5214 |
| Lower face throat length (Sn–Gn′–C) (angle) | 100 | 7 | 112.5129 | 27.5383 | 0.0058 | 2.8171 |
| Lower vertical height depth ratio (Sn–Gn′/C–Gn′) | 1.2 | – | 8.1616 | 27.5569 | 0.1137 | 1.5946 |
| Lip position and form | ||||||
| Nasolabial angle (Cm–Sn–Ls) (angle) | 102 | 8 | 95.4344 | 17.4173 | 0.0265 | 2.2491 |
| Upper lip protrusion Ls–(Sn–Pg′) | 3 | 1 | 6.0937 | 2.9609 | 0.0001 | 6.3923 |
| Lower lip protrusion Li–(Sn–Pg′) | 2 | 1 | 6.0309 | 4.3498 | 0.0001 | 5.7638 |
| Mentolabial sulcus Si–(Li–Pg′) | 4 | 2 | − 0.2666 | 5.8981 | 0.0001 | 4.4245 |
| Vertical lip chin ratio (Sn–Stms/Stmi–Me) (Prp. HP) | 0.5 | – | 0.44987 | 0.06421 | 0.0001 | 4.9279 |
| Maxillary incisor exposure (Stms-1) | 2.0 | 2 | 3.6564 | 2.9261 | 0.0019 | 3.1781 |
| Interlabial gap (Stmi–Stms) (Perp HP) | 2.0 | 2 | 4.3377 | 3.3877 | 0.0001 | 3.9811 |
The values in bold define the significant p values (p < 0.05) for the given parameters
ll parallel, Prp perpendicular, HP horizontal plane
Discussion
The orthognathic surgical procedures are primarily aimed at enhancing the facial appearance and achieving the normalcy of the dentofacial deformities and improving the functions [3, 4, 7]. Several methods [8] and different types of analysis [9, 10] have been devised in the literature for the planning of orthognathic surgery. The cephalometric analysis provides the clinical understanding of the abnormal dento-skeletal pattern and helps in planning an appropriate surgical intervention to achieve the desired results [5]. The cephalometric norms used for India population are the ones that have originated in White population from the Northern America [5, 11]. Variation do exist in the cephalometric norms among different ethnic groups [4]. The differences in cephalometric values of various ethnic groups have been studied extensively [12, 13] and the literature reveals the necessity for the establishment of norms for different population. Since there is diversity and dispersion of different ethnic groups in India, we conducted a study to acknowledge the differences or similarities in the cephalometric values for the Chhattisgarh population with the values developed for the Caucasian by Burstone et al. [5] and Legan and Burstone [6] for the hard and soft tissue measurements. The details of the finding of our study have been discussed under two different headings hard and soft tissues.
Hard Tissue Findings
Several similarities in the Chhattisgarh population with the Caucasian have been found, whereas some significant differences in respect to the hard tissue parameters are noticeable. Comparative study revealed that the cranial base length in male Chhattisgarh population was same as that of Caucasians, whereas in females the cranial base length especially the Ar-Ptm value (Articulare to Pterygomaxillary fissure which is measured parallel to horizontal plane) value was more than those given for the Caucasian population. This is because the position of the mandible in relation to posterior surface of maxilla which was greater in our study group. A similar finding has been shown by Yadav et al. [3], Garg et al. [2], Arunkumar et al. [7], Bishara et al. [14] in their study, although Chhattisgarh is in the center of India. The study by Yadav et al. in the year 2018 found that the cranial base length in the central Indian population was greater especially in females as compared to Caucasians.
Pertaining to the horizontal hard tissue parameters given by Burstone et al. [5], the findings for the males of Chhattisgarh ethnicity have similarities with the Caucasian. On the other hand, the female Chhattisgarh population showed an increase in the angle of skeletal convexity, i.e., N-A-Pg which is the angle formed between N-A (nasion to Subspinale) and A-Pg (nasion to Pogonion) and increased N-A (nasion perpendicular to subspinale to A, parallel to HP) values defining the position of the apical base of maxilla in relation to nasion. This is in accordance with the studies of Bishara [14], Kalha [15], Connor [16], Park [17]. Therefore, it can be stated that the females in Chhattisgarh have convex facial profile and prognathic maxilla as compared to Caucasians.
When the vertical skeletal hard tissues parameters were analyzed, significant differences were evident among the males of Chhattisgarh population and the measurements in females population were similar to the ones proposed for the Caucasian. There was decreased divergence of the mandible posteriorly in Chhattisgarh male population which is analyzed by measuring the MP-HP (mandibular plane to horizontal plane), it is suggestive of decreased posterior facial divergence and the upper posterior dental height was also reduced in this population. This finding is contradictory to those found for north Indian [2] and Japanese [13] population, wherein they found increase in the vertical skeletal parameters. The females in our study had similar vertical skeletal parameters with Caucasians.
Many contrasting findings were discovered in our study group from that of the Caucasian population with respect to the maxillo-mandibular relation. The final mandibular measurements that describes the chin prominence in relation to mandibular denture base [5] was statistically significant in both the sexes, i.e., reduced chin prominence was evident but the mandibular ramal length, mandibular body length were significantly different in only the male population of Chhattisgarh origin. They had increased ramal length and decreased body length of mandible thereby denoting skeletal class-II tendency. These findings are not so in accordance with those found for north Indian [2], South Indian [7], Central India [3] and other ethnic groups [16, 17] specifically in respect to both the gender.
All the dental parameters in Chhattisgarh ethnic groups were similar to that of the Caucasians except for the inclination of upper incisors in relation to the palatal plane. Males in our study group showed proclined upper incisors, whereas females were similar to Caucasians in all the dental aspects which is again dissimilar to the different studies [4, 18–20].
Soft Tissue Findings
The skeletal hard tissues, i.e., the underlying bone and teeth, are concealed by the soft tissue and hence the disparity in this can produce undesirable facial characteristics. Therefore, the soft tissue considerations must be kept in mind before any planned orthognathic surgery to achieve normative standards and desirable face [11, 21–27].
On comparing the soft the soft tissue values of our study group with the Caucasians, enormous differences were evident. The facial convexity angle and the maxillary prognathism were alike Caucasians, but the mandibular prognathism and lower face throat length were greater than the White population. This implies that the Chhattisgarh population have more prognathic mandible with obtuse chin. Studies on North Indian population [2], South Indian [15] are different from ours in terms of facial convexity, maxillary and mandibular prognathism whereas similar to the lower face throat angle. On the other hand, the study on Central Indian [3] demonstrated the similarities with our study for the mandibular prognathism and lower face throat angle along with the different findings in respect to the facial convexity.
The nasolabial angle, mentolabial sulcus and vertical lip chin ratio values for our study group were lesser than the ones proposed for the American-White population. It means that our study population had acute nasolabial angle which is again suggestive of maxillary protrusion in the literature but we did not find any such uncovering. All the above-mentioned findings of the soft tissue parameters were contradictory to the ones studied in Central Indian [3], North Indian [2], Japanese [27], Korean [28] and Black [29] population.
Apart from the above statistically significant findings, the values for upper and lower lip protrusion, maxillary incisor exposure and the inter-labial gap were also very significant. All of these parameters were in the upper range than the one given by Legan [6]. This means that both the sexes in Chhattisgarh have more protruded upper and lower lips which is also supported by the study on Central Indian population [3] for different ethnicities. The study by Yadav [3] found similar maxillary incisor exposure with that of Caucasians. However, our study again contradicts to this, as both the genders in our study group had statistically more upper incisor exposure than Caucasian which is similar to North Indians [2]. On the other hand inter-labial gap in the aforesaid study [2] is shorter with more of incisal exposure when compared to Caucasians but we found increased interlabial gap which means more of the incisor exposure.
Conclusion
To summarize the study, we found that the Chhattisgarh ethnic group had many soft tissue dissimilarities and few hard tissue dissimilarities in both the sexes in comparison with Caucasians. Therefore, we conclude that the above results can be used in Chhattisgarh population for orthognathic evaluation and treatment planning; however, further studies with larger sample size are recommended for definite and conclusive results.
Clinical Significance
In order to achieve satisfactory outcomes of the orthognathic surgery, proper understanding of the different hard tissue and soft tissue parameters is essential and appropriate planning of the same is required. Cephalometric analysis for orthognathic surgery serves as a helpful tool in planning of the procedure. As it is an unavoidable fact that significant variations do occur among and between the individuals of different racial origins therefore norms need to be developed for individual population.
Acknowledgements
We would like to thank Dr. Pramod Sharma, Reader in the Department of Oral and Maxillofacial Pathology, Chhattisgarh Dental College and Research Institute for immense help and guidance in the statistical analysis of the study. I would also like to extend my acknowledgement to Dr. Ritika Motghare and Dr. Akash Swarnkar for the encouragement and support.
Declarations
Conflict of interest
The authors declare that they have no conflict of interest.
Footnotes
Publisher's Note
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