Association of Abo Blood Groups and Rh Factor with Sagittal and Vertical Skeletal Malocclusion- An Observational Study
Correspondence Address :
Sampath Aravind,
No 26, 6th Cross, Kumaran Nagar, Lawspet, Puducherry, India.
E-mail: arvindsam100@gmail.com
Introduction: Various studies have proved the association between several disease including dental crowding, malocclusion and craniofacial deformities with blood group. Certain skeletal problems in sagittal plane are heritable and the skeletal muscle volume and strength, a heritable trait varies with different facial patterns.
Aim: To evaluate the association between ABO blood groups and Rhesus (Rh) factor with skeletal malocclusions in sagittal and vertical plane.
Materials and Methods: An observational study was conducted with a sample of 240 participants who reported to Department of Orthodontics in SRM Dental College and Hospital, Chennai, Tamil Nadu, India seeking orthodontic treatment over a period of two years from September 2018 to December 2020. Participants were assessed for skeletal malocclusion in sagittal and vertical plane and for their ABO and Rh blood grouping. Chi-square test was used for determining the association between sagittal and vertical skeletal malocclusion with ABO and Rh blood grouping. The association of the gender and the malocclusion was determined as a secondary outcome of the study.
Results: A total of 240 participants (mean age: 19.81±5.95 years; 95 males and 145 females) were observed and data was analysed. A significant association was found between Rh positive blood group and skeletal class II malocclusion with high angle (p-value 0.025). Skeletal class I malocclusion with high angle was found to be associated significantly with O+ group (p-value <0.001). The female gender was found to be associated significantly with sagittal skeletal class II malocclusion with high angle (p-value 0.049).
Conclusion: There is an association between the ABO blood groups and skeletal sagittal malocclusion and vertical skeletal pattern. Skeletal class II malocclusion with high angle pattern was associated significantly with Rh+ blood group and class I skeletal malocclusion with high angle pattern was significantly associated with O+ blood group.
Heritability of malocclusion, Rhesus factor, Sagittal skeletal malocclusion, Vertical skeletal pattern
In 1901, Karl Landsteiner defined and characterised the ABO antigens that are present in cell membrane of the Red blood cells that determine the blood group (1). The chromosome 9 bears the genes that code these antigen and is inherited in an autosomal co-dominant fashion (2). Malocclusions can be acquired or hereditary and the knowledge on the relative contribution of genetics and environmental factors in the aetiology of malocclusion is of paramount importance to an orthodontist (3),(4),(5). Skeletal malocclusion due to prognathic or a retrognathic mandible, facial height and vertical skeletal pattern is strongly influenced by the familial genetic pattern and are heritable (3),(6). A complex relationship exist between the mandibular muscles and underlying vertical facial patterns (7),(8). Difference in muscle structure and strength has been demonstrated between low angle and high mandibular plane angle cases, with brachyfacial types demonstrating a strong muscular environment (7).
Various studies in the past have shown association between prevalence of salivary gland tumours, malaria, cholera, oral cancer, dental caries, haematological malignancies, chicken pox, ischaemic heart disease with certain blood group [9-23]. A recent report on incidence of Coronavirus Disease-2019 (COVID-19) infection among different ABO blood groups showed highest incidence in B group and least with O group (24),(25).
Studies have proved the association between different malocclusion including dental crowding, and craniofacial deformities with different ABO blood groups (26),(27). A study conducted by Rathi A et al., showed a highest prevalence of malocclusion in O group and a significant correlation between certain malocclusion and ABO blood groups. Angle’s class I malocclusion was found to be more in O blood group, class II in A and class III was most common in B blood group (26). Another study by Sharma R et al., revealed a strong association between blood groups and malocclusions with prevalence of malocclusions being highest in blood group B, followed by A, O and AB in Jaipur population (28).
A recent study evaluating the association of skeletal malocclusion with blood group in Kerala population showed a strong association of B and O blood group with YEN (developed at Yenepoya Dental College) angle and no association between vertical parameters of malocclusion with any of the blood groups (29). There is no study in the literature evaluating the association of ABO blood groups and Rh factor with sagittal and vertical skeletal malocclusion in Chennai city population.
Keeping that lacunae in mind, the present study was designed with a null hypothesis, that, there is no association between ABO and Rh blood groups with skeletal malocclusions in sagittal and vertical plane. Hence, the aim was to find any prevalent association.
An observational study was conducted from September 2018 to December 2020 in the Department of Orthodontics, SRM Dental College and Hospital, Ramapuram, Chennai, Tamil Nadu, India, to evaluate the association of ABO blood groups and Rh factor with sagittal skeletal and vertical skeletal malocclusions. The protocol for the present study was approved by Institutional Review Board and Ethics Committee of SRM university (approval number of SRMDC/IRB/2018/MDS/No.109). The study was registered in The Clinical Trials Registry India (CTRI) with the registration number of CTRI/2020/09/027588.
Informed consent was obtained from the participants about determination of the blood group and utilisation of lateral cephalogram for the present study from the routine records taken for their orthodontic treatment.
Sample size calculation: Sample size was calculated using “N master software” with power 80% and a error 5% the calculated sample size was 240 participants and statistical significance is considered to be at p<0.05 level.
Inclusion criteria: Those patients seeking orthodontic treatment in Department of Orthodontics of the study centre, 15 years to 55 years and who were willing to give written consent to participate in the study were recruited in the study.
Exclusion criteria: Patients affected with craniofacial syndromes, maxillofacial deformities like cleft lip and palate, with history of oral habits such as mouth breathing, digit sucking, tongue thrusting and previous history of orthodontic treatment were excluded from the study.
Study Procedure
Lateral cephalogram of the patients were obtained and manual tracing was performed to assess the sagittal and vertical relationship. ANB angle (2°±2°) and Wits appraisal (2 mm) was used for determining the sagittal skeletal pattern and Go-Gn to SN (31°±3°), FMA - Frankfort Mandibular plane Angle (25°±3°) and Jarabak ratio (62%-65%) was used for determining the vertical skeletal pattern. Class I was considered to be having an ANB angle of 0° to 4°. Class II was considered to be having an ANB angle of greater than 4°. A high vertical angle can be defined as those individuals with Go-Gn to Sn greater than 34°, FMA greater than 28° and Jarabak ratio lesser than 62%. An average vertical angle can be defined as those individuals with Go-Gn to Sn 34°±3, FMA 28°±3 and Jarabak ratio 62% - 65%. A low vertical angle can be defined as those individuals with Go-Gn to Sn lesser than 31°, FMA lesser than 25° and Jarabak ratio greater than 65% (30). The procedure for blood group determination used includes ABO system and Rhesus system as explained in the study of Sharma R et al., (28).
Statistical Analysis
The association between blood groups and skeletal malocclusions was determined using Chi-square test using Statistical Package for Social Sciences (SPSS) software version 2.0. The p-value <0.05 was considered statistically significant.
The mean age of the participants was 19.81±5.95 years. The distribution of gender, sagittal skeletal relation, blood group and vertical skeletal relation among the sample was calculated (Table/Fig 1). Males contributed to 95 (39.6%) of the total sample and the distribution of skeletal class I and class II malocclusion was 109 (45.4%) and 131 (54.6%) respectively. When the blood group was analysed based on ABO system, majority of the participants were B+ 39% followed by O+ 37.5%. The B- constituted 3.2% of the sample with AB+ and AB- constituting 4.4% and 0.8% respectively. When the blood group was analysed based on the Rh system, Rh+ constituted 225 (93.75%) and Rh- constituted 15 (6.25%). High mandibular plane angle was noticed in 94 (39.2%) of the participants, average and horizontal vertical skeletal relation was seen in 78 (32.5%) and 68 (28.3%) of the sample size.
The frequency distribution of sagittal skeletal pattern and vertical skeletal pattern in ABO and Rh blood groups were not statistically significant (Table/Fig 2). The association of skeletal pattern with ABO blood groupings also showed no statistical significance (Table/Fig 3). A statistically significant association was found between Rh positive blood group and skeletal class II high angle malocclusion with frequency distribution of 65.9%. When Rh Blood group among various skeletal pattern was analysed with Chi-square test, Rh positive blood group was found to be associated significantly with skeletal class II high angle malocclusion with p-value=0.025 and with Chi-square value of 7.392 (Table/Fig 4),(Table/Fig 5).
A statistically significant association was found between sagittal skeletal class I vertical mandibular pattern and O+ blood group with frequency distribution of 100%. When blood groups and Rh blood groups among various skeletal patterns were analysed with Chi-square test, sagittal skeletal class I vertical mandibular pattern was found to be associated significantly with blood group O+ with p-value <0.001 and Chi-square value of 31.00 (Table/Fig 6),(Table/Fig 7). A statistically significant association was found between female gender and sagittal skeletal class II high mandibular plane angle with a frequency distribution of 56.3% and when gender distribution among the various skeletal patterns were analysed with Chi-square test, the female gender was found to be associated significantly with sagittal skeletal class II high mandibular plane angle with p-value 0.049 and Chi-square value of 5.751 (Table/Fig 8),(Table/Fig 9).
Majority of the participants in the present study, belonged to B+ blood group and 54.6% comprised of skeletal class II malocclusion, 39.2% comprised of high mandibular plane angle and skeletal class II high angle comprised of 26.25%. Association of skeletal class II high mandibular plane angle malocclusion with Rh+ blood group was found to statistically significant at p-value <0.05 and association of sagittal skeletal class I vertical mandibular pattern with O+ blood group was also found to be statistically significant at p<0.001.
(Table/Fig 10) describes about various studies conducted previously regarding association of various oral pathology and blood groups (6),(31),(32),(33),(34),(35). Studies in medicine showed significant association of significant association of Rh+ blood group with skeletal class II high mandibular plane angle malocclusion but when the malocclusions were considered separately, Rh+ blood group showed insignificant association with skeletal class II or class I malocclusion or vertical skeletal pattern malocclusion. The results of the present study further showed that the association of skeletal class I vertical malocclusion was significant with the blood group O+.
Significant association between Rh+ blood group and skeletal class II vertical skeletal pattern malocclusion was found in this study. Thus, rejecting the null hypothesis considered for the present study. The possibility of such an association of Rh+ blood group with skeletal class II high mandibular plane angle malocclusion may be suggestive that the gene(s) controlling the Rh+ blood group might also control the phenotype skeletal class II high mandibular plane angle malocclusion. The possibility of such an association might also be due to increased incidence of Rh+ blood group in the recruited population. Hence, future studies with still larger population could reveal more specific associations between such phenotypes which would be of immense benefit for the scientific community pursuing the genetic research.
Limitation(s)
The results of the present study should be interpreted with caution as the representative sample showed a large incidence of Rh+ blood group. More specific association could be revealed by increasing the sample size of different ethnic origins.
There is an association between the ABO blood groups and skeletal sagittal malocclusion and vertical skeletal pattern. Skeletal class II malocclusion with high angle pattern was associated significantly with Rh+ blood group and class I skeletal malocclusion with high angle pattern was significantly associated with O+ blood group. Future genetic studies in the direction of determining the common gene for the expression of multiple phenotype would be beneficial and studies evaluating the association of blood group and oral habits in causing the malocclusion would help in determining the heritability of oral habits, if any.
DOI: 10.7860/JCDR/2022/53495.16563
Date of Submission: Nov 30, 2021
Date of Peer Review: Jan 08, 2022
Date of Acceptance: Apr 08, 2022
Date of Publishing: Jul 01, 2022
AUTHOR DECLARATION:
• Financial or Other Competing Interests: None
• Was Ethics Committee Approval obtained for this study? Yes
• Was informed consent obtained from the subjects involved in the study? Yes
• For any images presented appropriate consent has been obtained from the subjects. NA
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