Angle’s classification (1899) has been used in malocclusion surveys to report the prevalence and distribution of the different types of malocclusion. Angle’s classification groups all malocclusion into three distinct classes: class I, class II and class III. Although Angle’s classification is the most used method for population surveys of malocclusion for its simplicity, it was primarily not designed for the purpose.

There are obvious limitations in recording malocclusion with Angle’s classification.

• 1.

  Angle classification does not reveal the severity of the malocclusion class, nor does it consider the patient’s profile and skeletal relationship.

• 2.

  Dr Angle considered the malocclusion only in the sagittal/anteroposterior plane.

• 3.

  Intra- and inter-investigator errors are usually large when recording Angle’s classification. Significant intra- and inter-examiner errors may nullify population differences.

• 4.

  The unilateral class recording is difficult, particularly in mutilated dentitions.

Several researchers have added documenting more traits of malocclusion in three planes of space, such as tooth rotations, crowding, open bite, close bite, crossbite and arch constriction.

The method of recording malocclusion developed by Bjork et al. is based on defined items of the recorded symptoms. The registration of the malocclusion was divided into three parts:

• 1.

  Anomalies in the dentition: Tooth anomalies, abnormal eruption and misalignment of individual teeth.

• 2.

  Occlusal anomalies: Deviations in the positional relationship between the upper and the lower dental arches in the three planes.

• 3.

  Deviation in space conditions: Spacing and crowding.

This comprehensive method of recording malocclusion was used in many surveys and had the advantage of data analyses through computer systems ( Table 4.1 ).

The technique for recording malocclusion developed by Bjork et al. underwent several modifications by the working groups of FDI between 1969 and 1972. The method was tested in the field from 1973 to 1976 and underwent further modifications. ^, The final version was improved in collaboration with WHO, and the recording form was named ‘Dentofacial anomalies assessment form’. This form was made available through the WHO publication ‘Oral Health Surveys’ in 1979.

The criteria for recording malocclusion were based on the principles of agreeing on individual traits to be grouped in a simplified manner. This recording system serves as an essential reference tool in developing methods to assess the need and demand for orthodontic treatment. Figs 4.1 and 4.2 .

Codes for anteroposterior molar relationships.

The scale refers to the relative position of the upper left molar. The arrows indicate anteroposterior molar relations in a normal occlusion situation (codes 0) and at lower-class limits of codes 1–4 (no upper-class limits are defined for codes 2 and 4).

Source: Based on Bezroukov V, Freer TJ, Helm S, Kalamkarov H, Sardo IJ, Solow B. Basic method for recording occlusal traits. Bull World Health Organ 1979;57(6):955–61. PubMed PMID: 317023; PubMed Central PMCID: PMC2395850 .

Buccal and lingual posterior crossbite.

Source: Based on Bezroukov V, Freer TJ, Helm S, Kalamkarov H, Sardo I J, Solow B. Basic method for recording occlusal traits. Bull World Health Organ 1979;57(6): 955–61. PubMed PMID: 317023; PubMed Central PMCID: PMC2395850.9 .

Each trait was grouped based on the degree of deviation from the norm or severity. Codes and criteria are listed on the recording form to simplify recording and minimise the time involved in the examination.

Assessment of dentofacial anomalies and status of occlusion were suggested to be recorded on permanent dentition in three parts:

• 1.

  Dental examination: Anomalies of development, congenitally missing teeth, supernumerary teeth, malformed teeth, impacted teeth, missing teeth due to trauma or extraction and retained deciduous teeth.

• 2.

  Intra-arch examination: Crowding, spacing, anterior irregularities and upper midline diastema.

• 3.

  Inter-arch examination: The molar relationship, posterior open bite, posterior crossbite, overjet, overbite, midline deviation, anterior open bite and soft tissue impingement.

The sociopsychological effects of occlusal features on an individual, their family and peers were not considered because of a lack of objective methods of measuring these factors.

In the past, accurate comparisons of malocclusion from different studies were difficult for several reasons as listed listed in Table 4.2 . The reasons included a lack of uniform criteria for registration of malocclusion and its traits, faulty sampling techniques and errors in examinations and data recording.

Only a few surveys on children and young adults have been done to record malocclusion on a sample representative of the population for their size or distribution of age groups. Populations sampled from different age groups, particularly those from early mixed and mixed dentition, where occlusion in a state of flux leads to inaccurate recordings and makes comparisons difficult with those of permanent dentition. Therefore, a malocclusion survey is recommended during the late mixed or early permanent dentition stage. By this stage of development, the growth of the face is close to completion; moreover, permanent teeth up to the second molars will have erupted in the oral cavity, while maxillary canines have fully erupted or are near completion of eruption. Adult occlusion or malocclusion is close to or nearly established by this age ( Table 4.3 ). The sample size of a target population, for example, the school-going population, can be calculated based on a known prevalence of the disease/malocclusion using the formula given in Table 4.4 .

Variations in the prevalence of malocclusion have been found between different races or ethnic groups. The prevalence of malocclusion varies significantly in different parts of the world, in different ethnic groups, and among people of different races.

In general, the prevalence of malocclusion is reported to be higher among Whites than Blacks and more in urban than rural children.

Individual races are known for specific traits of malocclusion like bimaxillary protrusion is more common in Negroes, while Polynesians of Pukapuka Island and Mongoloids of China, Japan, Taiwan and Korea have a high prevalence of skeletal class III malocclusion.

The prevalence of class II malocclusion is found to be high among Caucasians. In the United States of America, it was found to be 34% in Whites and 18% in Blacks. It has been reported that the prevalence of class II malocclusion was 31% in the Danish children population while it was as low as 8% in Johannesburg, 11% in Kenya, 16.4% in Saudi Arabia and 14.6% in Delhi, India.

Proffit et al. published findings on the prevalence of malocclusion and orthodontic treatment needs in the United States. The findings were based on the National Health and Nutrition Estimates Survey III, conducted from 1989 to 1994 on 14,000 subjects aged 8–50 years, representing 150 million subjects. Angle’s classification, irregularity index and occlusal contact discrepancies were recorded. Findings were presented for age groups 8–11, 12–17 and 18–50 years. Among 8–17 years age group, 70% of children had malocclusion, of which 50%–55% were class I, 15% were class II and 1% were class III. More than 50% of children had crowding in the maxilla and/or mandible or both.

Earlier estimates of the prevalence, severity and need for treatment of malocclusion in youths of 12–17 years of age in the United States were published by the Division of Health Examination Statistics in 1977.

The report is based on data obtained from oral examinations conducted in 40 scientifically selected locations across 25 states, covering specific sections of the country. The statistical findings were drawn from 90% of a probability sample of 7514 youths, which represents roughly 22.7 million non-institutionalised children in the United States. About 54% of those examined were found to have neutrocclusions. Proportionately, more Black (62%) than White youths (52%) were found to have neutrocclusion. Neutrocclusions are characterised, among other deviations, by crowding, rotations, spacing, ectopic eruptions and loss of teeth. Distocclusion was found more in White youths (34%) than in Black youths (18%). About 14% of children in the sample studied were reported to have mesiocclusion. Over 10% were estimated to have severe overbites of 6 mm or more of the incisor teeth. Crossbites of varying severity were found in 12%, and 38% had up to three displaced teeth, with the remainder having four or more displaced teeth ( Table 4.5 ).

About 25% were found to have definite malocclusion for which treatment was considered to be ‘elective’. Treatment was considered ‘highly desirable’ for 13% and ‘mandatory’ for an additional 16%. An estimated 10.2 million youths/adults had specific occlusal defects such as severe incisor overbites or open bites, which required ‘evaluation by orthodontists to determine the need for treatment’.

Payette and Plante, in 1201 Quebec school children (13- and 14-year-old) using Grainger’s orthodontic treatment priority index (TPI), reported that 32% of the children were in Angle’s class II molar relation; 18% had an overjet of 5 mm and more than 50% had one or more teeth in minor or a major displacement. Treatment was mandatory or highly desirable for 13.7%, and only 2.9% of the students were under treatment. According to Harrison and Davis, 61% of native children of British Columbia in the age group 7–15 years had malocclusion ( Table 4.5 ).

A survey of 4724 children (age 5–17 years) randomly selected from a population that attended Dental Health Services was conducted in Bogotá, Columbia. Based on their dental development, these were grouped into four developmental stages (DS Stage I–IV).

Registration of malocclusion was performed according to the method suggested by Bjork et al., and the need for orthodontic treatment was evaluated according to the index used by the Swedish National Board of Health. A large percentage (88%) of children had some form of dental and or occlusal anomaly from mild to severe type; half of which, that is, 44%, had occlusal anomalies and one-third, that is, 30%, as space discrepancies. Urgent need for orthodontic treatment was recorded in 3% of subjects examined, and great need was recorded in 20%. Little need was recorded in 35% of subjects, and moderate need was recorded in 30% of subjects.

A large proportion of the population (nearly 80% or more) studied among European countries has some form of occlusal anomalies. Although these observations do not truly represent the true need for orthodontic treatment, a high prevalence of malocclusion suggests a widespread existence of the problem and perhaps is an outcome of a strict recording protocol. It is also evident that the prevalence of class II malocclusion is high in Europe among the Caucasian population. The prevalence of class II malocclusion in Danish children was 31%, and in Hungary, 47.2% ( Table 4.6 ).

These observations on class II malocclusion in Europe are considerably high compared to the prevalence of class II malocclusion in Africa, Arabia and India.

The prevalence of malocclusion in Kenya, Nigeria and Tanzania is recorded to be high ranging from 72% to 86% of the sample surveyed, though most constitute class I type of malocclusion. Class II malocclusion among children in Kenya is 7.9%, while in Nigeria, it is only 1.7%. Studies on children in Africa have shown that the proportion of class II malocclusion is much lower compared to a high prevalence of class II malocclusion prevalent in Caucasian population groups (up to 50%) ( Table 4.7 ).

Specific malocclusion traits were highest for crowding, rotations, posterior crossbite and maxillary overjet. Interestingly, the frequency of frontal open bite was 2.3% in children from Libya , and 19.5% of children from Benin City in Nigeria have midline diastema. ( Table 4.7 )

According to Fu et al., the prevalence of malocclusion among Chinese children was 67.82%. A study by Lew et al. on 1050 Chinese school children (aged 12–14 years) reported a high incidence of class III malocclusions in Chinese compared to Caucasians. However, the incidence of class II malocclusions was similar to those reported in Caucasians. Crowding occurred in about 50% of cases ( Table 4.8.i ).

TABLE 4.8.i

Prevalence of malocclusion in the Indian subcontinent, China and Iran

Country/population	Author/year	Subjects	Age (years)	Method of recording	Malocclusion
Pakistan	Gul-e-Erum and Fida	156 Orthodontic patients	8 years 1 month to 39 years and 6 months	Angle’s classes, and traits	Frequency distribution of malocclusion Class I—18.6% Class II—70.5% Class III—10.9% Crowding >2 mm Maxillary—64.7% Mandibular—81.8% Increased overjet >2 mm—79.5% Anterior crossbite—4.5% Increased overbite—71.8% Open bite—2.6% Crossbite—22.4%
Nepal	Sharma	350 Orthodontic patients	8–36	Angle’s classes, traits, frequency, distribution	Frequency distribution of malocclusion Class I—62.28% Class II—29.4% Class III—8.2% Midline diastema—16% Incisor crowding—52.9% Spacing—30% Increased overjet >4 mm—42.3% Anterior open bite—5.1% Deep bite >4 mm—40%
Eastern Nepal	Singh and Sharma	2074 M: 1149 F: 925	12–15	Angle’s classes	Class I—48.5% Class II—32.68% Class III—4.32%
China	Lew et al.	1050	12–14	Foster and Day	92.9%
China	Fu et al.	25,392			67.82%
Iran	Borzabadi-Farahani et al.	502 M: 249 F: 253	11–14	Angle’s classes	Class I—41.8% Class II div 1—24.1% Class II div 2—3.4% Class III—7.8 Increased overjet—31.7% Reverse overjet—4.2 % Deep bite—36.7 Anterior open bite—1.6% Scissors bite—2% Anterior crossbite—8.4% Posterior cross-bite—12.4% Midline deviation—23.7% Crowding— Maxilla—16.7% Mandibular—10.8% Spacing— Maxilla—18.9% Mandible—20.7%

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