Indian Journal of Dental Research

EPIDEMIOLOGICAL WORK
Year
: 2019  |  Volume : 30  |  Issue : 3  |  Page : 455--461

Prevalence and gender distribution of malocclusion among 13–15-year-old adolescents of Kerala, South India


Shobha Sundareswaran, Praveen Kizhakool 
 Department of Orthodontics, Government Dental College, Calicut, Kerala, India

Correspondence Address:
Dr. Shobha Sundareswaran
Department of Orthodontics, Government Dental College, Calicut, Kerala - 673 008
India

Abstract

Objectives: To determine the prevalence and gender distribution of malocclusion in 13–15-year-old adolescents of Dravidian ethnicity, residing in urban and rural areas of Kerala, South India. Materials and Methods: A total of 1554 children (779 males, 775 females), from both urban and rural areas were examined in school settings. Survey proforma for personal details and occlusal registration according to Bjork et al. (1964) were used. Chi-square test was used for analysis. Results: Overall prevalence of malocclusion was 89.9% which included Angle's Class I, Class II (17.6%) and Class III (8%) malocclusions. Other anomalies detected were increased overjet (11.8%), anterior crossbite (27.5%), anterior open bite (1.6%), posterior crossbite (5.1%), scissor bite (4.4%), midline deviation (6.8%), bimaxillary protrusion (BMP-21.3%), crowding (66.6%), spacing (15.3%), rotations (45.4%), ectopic eruptions (11.1%), peg laterals (2.4%) and missing teeth (6.6%). Males showed a higher predilection for increased overjet, deep bite, spacing and missing teeth. Class III, BMP, midline deviations and rotations were found to be more prevalent among the rural group, whereas Class II, increased overjet, deep bite and ectopic eruptions were more prevalent among the urban. Conclusion: Information regarding the detailed pattern of malocclusion prevalence and the high prevalence of BMP among South Indian population of Kerala may provide a baseline data for planning orthodontic services.



How to cite this article:
Sundareswaran S, Kizhakool P. Prevalence and gender distribution of malocclusion among 13–15-year-old adolescents of Kerala, South India.Indian J Dent Res 2019;30:455-461


How to cite this URL:
Sundareswaran S, Kizhakool P. Prevalence and gender distribution of malocclusion among 13–15-year-old adolescents of Kerala, South India. Indian J Dent Res [serial online] 2019 [cited 2021 Mar 1 ];30:455-461
Available from: https://www.ijdr.in/text.asp?2019/30/3/455/264133


Full Text

 Introduction



The ever increasing importance of improved physical appearance has resulted in an increasing demand for orthodontic treatment in most countries. Planning orthodontic treatment within a public health system primarily requires information about the prevalence and distribution of malocclusion. The importance of epidemiological studies is thus obvious.

Numerous published studies have shown wide variations in the overall prevalence of malocclusion in different populations ranging from 45% to 97.6% in Tanzania,[1],[2],[3] 93% in Italy,[4] 92% in Jordan,[5] 92.9% in China,[6] 93% in Latin America,[7] 88% in Colombia [8] and Finland,[1] 77.1% in Iran [9] and 70.4% in Hungary.[10]

Very few authentic studies have been conducted to assess the prevalence of malocclusion and orthodontic treatment needs in a vast country like India with wide variations in ethnicity, language, nutritional status, religious beliefs and dietary habits. One study conducted in Udaipur district of Rajasthan in North India inhabited by people of Aryan race reported a prevalence of 36.42%.[11] South India, racially inhabited by Dravidians, reported a malocclusion prevalence of 19.9%[12] in Karnataka, and 15% in Tamil Nadu [13] using DAI scores. Kharbanda et al.[14] in a Delhi-based school survey of 4500 children in a wide range of 5-13 years has reported the prevalence of Class I molar relation to be 91.6% and Class II 14.6%. Lower anterior crowding was reported to be the most common trait (11.7%).

Many epidemiological studies are based on orofacialindices (IOTN, DAI, TPI). An alternate approach to the use of indices is a representation of measurable occlusal characteristics such as spacing, crowding, deep bite, open bite, rotation and so on.[15]

There is little available epidemiological data on the prevalence of malocclusion in Kerala, the state with the highest literacy in India. The southern states of India including Kerala are populated by people of Dravidian ethnic origin which includes Tamil, Telugu, Kannada and Malayalam speaking people.[16] In every country, it is absolutely important to gain information on the prevalence of malocclusion and different occlusal traits while creating public health plans for orthodontic screening, prevention, treatment and organization of funds. A need-based assessment of malocclusion can provide valuable information during planning and distribution of health amenities and resource allocation.

Calicut is a major city in the northern part of Kerala, also known as the Malabar area. Historically important as the portal of entry for the western world towards the discovery of India in 1498, it is predominantly populated by people of Dravidian ethnic origin.

The aim of this study was, therefore, to determine the prevalence of malocclusion including sagittal molar relationship and individual traits like overjet, deep bite, open bite, crossbite, crowding and spacing in a sample of 13–15-year-old school children of Dravidian ethnicity. A second aim was to assess the gender distribution of individual traits as well as compare differences, if any, among the rural and urban population.

 Subjects and Methods



Approval to conduct the study was obtained from the institutional ethics committee, District Educational Officer and authorities of Calicut city. Permission was also obtained from the school authorities, parents and children themselves.

A minimum sample of 714 was calculated with a prevalence rate of 35% based on a pilot study using the formula z2 pq/l2, with 95% of confidence interval where, z = Value of z in 95% Confidence level = 1.96, P = prevalence rate = 35%, q = (1- p) = (1- 0.35) = 0.65, I = allowable error (10% of P) = 10/100 × 0.35 = 0.035, n = 1.962 × 0.35 × 0.65/(0.035)2 = 714. In order to compensate for a possible clustering effect the sample was doubled.

The source population for the present cross sectional study consisted of 13–15-year-old school children of Calicut district, Kerala in South India. Only consenting children belonging to the Malayalam speaking Dravidian race were included in the study. Children with previous history of orthodontic treatment, craniofacial anomalies and fractured incisors were excluded. From a total of 115 high schools in the district, 10 were selected by simple random sampling, out of which 5 were from the rural areas. Study subjects were selected using cluster sampling procedure. One division was selected from each class based on simple random process. Thus an average of 150-160 students was obtained from each school, totaling a sample size of 1554, comprising of 779 males and 775 females. The study was conducted over a period of 1 year from May 2015 to March 2016.

Training and calibration of examiner

The students were examined by a single examiner to avoid inter-examiner variations. Before the survey, both the examiner and record assistant underwent clinical calibration training in the Orthodontics department of Govt. Dental College Calicut. A pilot study on 40 children was conducted to ensure accuracy and standardize the procedures.

Clinical examination

Intraoral examinations were done using mouth mirror, explorer, metal ruler and sliding digital calliper (MitutoyoDigimatic, Mitutoyo Ltd, Hampshire UK), in the class room itself with natural light as the source of illumination. The assistant recorded all the observations. The interview and examination of single study subject took approximately 3-4 mins. For every child, a survey proforma had been prepared to designate and record the name, age, sex, area, Angle's classification and occlusal traits with the help of WHO oral health assessment form [17] and clinical registration as suggested by Bjork et al. (1964).[15]

Following parameters were qualitatively recorded in this study.

Sagittal relationships

Molar relationship - Angle's Classification was used to define the sagittal molar relationships: Angle's Class I, Class II or Class III [18] Unilateral molar shifts were recorded as subdivisions. Angle's Class II malocclusion was further characterized as Division 1 and Division 2. No registrations were made when first molars were missing.

Overjet was evaluated in millimeters and categorized as 'Normal' [1.0 and 3.0 mm],[19] 'Increased'[>3 mm],[20] 'Edge to edge' [upper and lower incisors at the same level],[19] 'anterior cross bite' [one or two lingually displaced upper anteriors]. A reverse overjet was registered when all four mandibular incisors were in front of the maxillary incisors.[9] The term bimaxillary protrusion was used when both upper and lower incisors were proclined with increased procumbancy of the lips.[21]

Vertical relationships

Overbite was evaluated based on percentage overlap of upper central incisors over crowns of the lower incisors [19] was recorded as normal (between 1/3 and ½ overlap),[18] deep bite (overlap > ½),[18] anterior open bite (no overlap of incisors),[18] posterior open bite (lack of contact between one or more antagonistic buccal teeth).[15]

Transverse relationships

Posterior Crossbite, scissor bite and midline deviation were evaluated based on Bjorks criteria.[15]

Individual occlusal traits

Crowding was recorded in the anterior and posterior regions separately and designated as mild, moderate and severe when the lack of space ranged between 1-3 mm, 4-6 mm or >6 mm, respectively.[15]

Spacing was recorded when there was no approximal contact between 2 teeth in a dental arch.[20]

Supernumeraries/supplemental teeth: It is the supplemental teeth which is present along with the normal series of permanent teeth both in upper and lower arches.[19]

Ectopic eruptions, peg laterals and missing teeth were also recorded as proposed by Bishara.[19]

Statistical analysis

Data were entered into a computer by using EpiInfo7 (version 7.0.9.34) and analyzed using SPSS version 16 (SPSS Inc, Chicago, IL, USA). Differences in proportion among the group were analyzed using Chi-square test. Values less than 0.05 (P < 0.05) were interpreted as statistically significant.

To test intraexaminer reliability, a repeat clinical examination was carried out by the same examiner in a randomly selected subsample of 75 participants after an interval of 4 weeks. Analysis performed thus gave Kappa values of 0.83, 0.80, 0.85, 0.93, 0.92 for midline shift, deep bite, cross bite, crowding and spacing respectively indicating very good intraexaminer reliability.

 Results



The sample of 1554 children examined comprised of 53.2% from the urban and 46.8% from the rural areas. Among them, 1382 had some form of malocclusion showing a prevalence of 89.9% in Dravidian population.

Sagittal

Molar relation

[Table 1] and [Table 2] show the overall prevalence and gender/area wise distribution of sagittal malocclusions based on Angle's classification and inter arch abnormalities. In all, 74.4% of the subjects exhibited a symmetrical Class I molar relationship with the females showing a higher prevalence (594, 76.6%). A symmetrical Class II molar relationship (distocclusion) was present in 9.4% of those examined comprising of 5.9% (92) showing Class II Div1, 1.6% (25) showing Class II Div 2 and 1.9% showing features of neither Div 1 nor Div 2. Class II Div 1 was found to be more in males. The predilection for subdivision was more on the right side in Class II Div 1 (5.9%) as compared to the left (2.3%). Children from the urban area had a higher proportion of right subdivision (7.4%). No subdivisions were recorded in Class II Div 2 category. Class III malocclusion (mesiocclusion) was present in 8% of the subjects, with an increased prevalence among males and rural subjects. Class III subdivision right was seen in 0.2% of the observed children.{Table 1}{Table 2}

Overjet

Overjet was found to be within normal limits in 81.1% (1259) of the adolescents. 11.8% (184) showed an increased overjet, 5.5% had an edge-to-edge relationship and 1.6% displayed complete reverse overjet. Anterior cross bite of one or two teeth was present in 7.3% (114) of subjects. A significantly higher prevalence of anterior crossbite was observed among the rural group (8.8%) as compared to 6% in urban (P < 0.05). The prevalence of increased overjet was significantly higher among males (P < 0.002) and urban population (P < 0.001).

Vertical

Normal overbite was present in 70.5% (1096) of the adolescents; 427 (27.5%) subjects examined had deep bite. The frequency of anterior and posterior openbites was 1.6% (25) and 0.4% (6), respectively. The prevalence of deep bite was significantly higher in males 30.7% (239) as compared with females [P < 0.05]. Study revealed deep bite to be more prevalent in urban population 30.0% (248).

Transverse

Posterior cross bite was observed in 5.1% (80) of the total subjects examined. No statistically significant difference was observed between males and females. Scissor bite was present in 4.4% and midline deviation in 6.8% (105) of the subjects with a significantly higher prevalence among the rural (PIndividual traits and anomalies

The pattern of individual traits and anomalies is given in [Table 3]. The overall prevalence of Class I bimaxillaryprotrusion (BMP) was found to be 21.3% (331) with a statistically higher prevalence among the rural population (24.8%; P < 0.05).{Table 3}

Mild and moderate crowding in the anterior region was observed in 44.7% (694) and 17.5% (272), respectively. Only 4.4% (69) had severe crowding in the anterior region. No significant differences were observed between males and females.

In the buccal segments, mild crowding was present in 15.3% (238) and moderate in 8.9% (138). Severe crowding was present only in 2.4% (38). Crowding in the posterior region was more or less similar between rural and urban subjects.

Spacing was present in 18% (280) of children examined with a significantly higher prevalence among males (20.2% (157), P < 0.05).

Rotations were observed in 706 (45.4%) adolescents examined with a highly significant increase in rural population (52.5% (381), P < 0.001). Ectopic eruptions had a significantly higher prevalence among urban (P < 0.05).

A total of 37 subjects (2.4%) had peg laterals, of which 21 (2.9%) were from the rural area. The distribution pattern of missing teeth is given in [Table 4]. Missing teeth were present in 6.6% (102) of the subjects with a statistically higher prevalence in males (P < 0.001) and urban subjects (P < 0.001). Canines were seen to be the most predominantly missing teeth (40; 2.6%) the predilection being more in the upper arch (26). This was followed by second premolars (28; 1.8%) where the prevalence was more in lower (21); 19 subjects (1.1%) had missing lateral incisors (15 upper/4 lower).{Table 4}

 Discussion



The study represents the first comprehensive epidemiological survey carried out on the South Indian children of Kerala, with the primary aim of documenting the true prevalence of all individual traits of malocclusion, their gender distribution and urban-rural differences, if any. Comparison of the present findings with other studies should be undertaken with caution, as wide variations in prevalence of malocclusion could exist depending on chronological age of the sample, registration methods used, ethnicity and sample size.

The overall prevalence of malocclusion among 13–15-year olds was found to be 89.9%, in agreement with many previous studies.[6],[22] Wide variations have been reported in various populations.[2],[8] In North India, inhabited by people belonging to the Aryan race, the reported prevalence ranges between 23.6% and 36.4%,[11],[23] which is lower than South India [71%-87.79%].[24],[25] However, in studies using DAI scores, the prevalence in south was seen to drop to 19.9% in Davangere [12] and 15% in Tamil Nadu.[13]

Sagittal

Molar occlusion:In accordance with the findings of previous studies,[2],[6],[7],[8] the predominant sagittal molar relationship among South Indian school children was Angle's Class I (74.4%) with 11.1% of them showing no other anomalies. Reported prevalence of Class I in other parts of India show wide variations ranging from 17.8% to 89.4%.[24],[25],[26],[27] The prevalence of Class II malocclusion (17.6%) is consistent with previous investigations [28],[29] but lower than that reported among Brazilian [30] Lithuanian [22] Iranian [9] and Turkish [31] populations. Wide variations in the prevalence of Class II have been reported from other states of India.[14],[24],[27],[32] Prevalence of Division 1 was more among males and among the urban population, in keeping with previous findings.[33] Subdivisions recorded separately in this study was predominant on the right side (5.9%). The prevalence of subdivisions does not seem to have been recorded in previous studies. Angle's Class II Division 2 malocclusion was observed in only 1.6% of cases. The prevalence of an Angle's Class III molar relationship (8%) compares with many previous observations.[9],[10],[28],[29],[32] Lower prevalence rates have also been reported from India [14],[27] and other countries.[2],[8],[22],[29],[33]

Overjet:The prevalence of an increased overjet of 11.8%, (significantly more in the urban population) found in the present study, is in agreement with previous observations.[2],[8],[12],[27] The overall prevalence of anterior crossbite(7.3%) and Class III malocclusion (7.9%) are found to be similar in this study. Males showed a higher predilection for anterior crossbite, edge-to-edge bite and reverse overjet, in keeping with the higher prevalence of Class III relationship seen among them.

Vertical

Overbite Majority of the adolescents examined had a normal overbite (70.5%). Deep bite was more common (27.5%) than anterior open bite (AOB), in keeping with previous observations.[4],[9],[32],[34],[35] Vertical discrepancies may be genetically determined as pointed out by Thilander et al. (2001) who observed that AOB was more prevalent among blacks than white Americans. An increased prevalence of 15% AOB has been reported among Tanzanian school children.[2] A posterior open bite was observed in 0.4% of the subjects examined, similar to a previous study.[36]

Transverse

The prevalence of posterior crossbites(5.1%) was in agreement with previous reports in the literature [1],[2] but higher than that reported from Italy,[4] Iran [9] and other states of India.[24],[32] These variations have been attributed to differences in sucking habits which differ in various populations.[5] Prevalence of scissor bite(4.4%) was found to be higher than other reports [9],[37] but lower than that reported by Mtaya et al. (2009). Prevalence of scissor bite has not been recorded in other studies from India.

Midline deviation of 6.8%, with an increased prevalence among the rural subjects was recorded, which is lower than previous reports.[2],[3],[8],[9] Prevalence of midline deviation has not been recorded in other studies from India.

Individual traits and anomalies

Bimaxillary Protrusion (BMP): Information regarding prevalence of BMP is scant. A perusal of the literature revealed a reported prevalence of 15.3% in Bogotian children.[8] The southern states of India are populated by people of Dravidian ethnicity, who have an affinity for BMP.[36] In the present investigation, the overall prevalence of BMP was found to be 21.3%, with an increased predisposition in the rural sector (24.8%). No study has thus far reported the prevalence of BMP in South India.

Crowding was the most common anomaly, recording an overall 66.6% (mild, moderate and severe), which is in agreement with many studies,[8],[34],[37] but higher than that reported in other publications.[4],[9],[10] No significant gender differences were observed. Previous studies from India have reported prevalences ranging from 28.3% to 58%.[12],[13],[23],[24],[35] The high percentage of crowding may be partly due to the poor dental health observed. The causes of increased prevalence of crowding need to be looked into, so that proper preventive measures and awareness campaigns can be initiated. The overall prevalence of posterior crowding was lesser (26.6%).

Spacing was noted in 18% of the subjects with a significantly higher prevalence among males. This agrees with previous observations.[2],[8],[9],[10] The prevalence of tooth rotation in this study is reported to be very high (45.4%) as compared with other studies.[3],[8]

Very few previous studies have recorded the prevalence of ectopic eruptions.[8] The high prevalence of ectopic eruptions (11.1%) in this population could be on account of increased crowding prevalence.

Clinically observed supernumeraries were present in only two subjects. However, this would not be a true representation of the prevalence of supernumeraries, as roentgenograms were not used to locate further impacted ones.

The overall prevalence of missing teeth was found to be 6.6% (significantly higher in males and among urban population) with upper canines topping the list (26 out of 40). However, this could be due to delayed eruption, considering the age range of population under observation. The prevalence of lower second premolars was found to be the next most common (21 out of 28) followed by the upper lateral incisors (15 out of 19). In Bogotian children also, the lower second premolars were found to be the most frequently missing teeth, followed by the lower and the upper lateral incisors.[8] No information exists regarding prevalence and pattern of missing teeth among Indian children.

Sociodemographic variables

Significant differences were not observed between the rural and urban population in this study. This could be due to the fact that Kerala being a developed state in terms of educational and economic factors, fractions of rural and urban population are seen to merge with each other in various regions. However, Class III, BMP, midline deviations and rotations were found to be more prevalent among the rural group whereas Class II, increased overjet, deep bite and ectopic eruptions were more prevalent among the urban.

Limitations

A need-based assessment and stratification using indices was not included here. An evaluation of the subjective need for treatment also needs to be done using the recently introduced Facial Aesthetic Index, which ensures treatment for the circumorally convex BMP cases as well.[38] Another limitation stems from the fact that children with fractured incisors and history of orthodontic treatment were excluded from the study, which may have resulted in an underestimation of the malocclusion prevalence.

 Conclusion



The present study reveals a high prevalence of malocclusion in Dravidian population of Kerala (89.9%). Increased prevalence of BMP (21.3%) among the population is a striking feature of this study. There is paucity of authentic data on the prevalence of different types of malocclusion in this region. This article, hence, provides a baseline data of the malocclusion prevalence, indicating the necessity for a need-based assessment of objective and subjective orthodontic treatment need, which will ultimately help in planning future orthodontic services in the state.

Financial support and sponsorship

Nil.

Conflicts of interest

There are no conflicts of interest.

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