Subjects

This study was prospectively designed for screening and follow-up of one entire age cohort of children of a rural community, who were to be treated according to a preplanned protocol with an emphasis on early treatment. With the approval of the communal authorities, casts were obtained from the whole group throughout the study including the children with no treatment need. The subjects consisted of all children born in 1987 and living in the municipality of Kälviä, a rural district in western Finland. All the 89 children attended the first examination at age eight years. After the first examination, one subject moved out and another was excluded because of starting treatment without fulfilling the study criteria. The final number of total subjects was 87 (49 boys and 38 girls).

Methods

Treatment need was evaluated with two indices, ie, the DHC component of the IOTN,19 and the 10-Grade Scale based on the TPI.1 The esthetic component of the IOTN was not applied because of the young age of the subjects.

DHC grades 1–2 and 10-Grade Scale scores 1–4 represented no/slight need, DHC grade 3 and 10-Grade Scale scores 5–6 moderate/borderline need, and DHC grades 4– 5 and 10-Grade Scale scores 7–10 definite need for treatment.

All assessments were done on casts. As modifications of the DHC, a crossbite with any recorded lateral shift scored always for DHC grade 4, and crossbites of primary molars and canines were also recorded. Overjet and overbite were not recorded if the incisors were not fully erupted.

All subjects were examined at the ages of eight, 10, and 12 years. The subjects' mean age at the first examination was 8.3 years (SD 0.35) and in the following examinations 10.3 years (SD 0.29) and 12.4 years (SD 0.29). A consultant orthodontist (Dr Väkiparta) examined all subjects aged eight years. Two general dentists took alginate impressions at ages eight, 10, and 12 years. The bite was registered in centric relation, and the casts were trimmed accordingly. The consultant orthodontist assessed the treatment need of all subjects at ages eight, 10, and 12 years on the casts.

After the first examination at age eight years, orthodontic treatment was started in subjects diagnosed with both DHC grade 4–5 and scores 7–10 in the 10-Grade Scale, if the subject was considered to benefit from early treatment. The following malocclusions were included in that category:

1. Crossbite (anterior or lateral);

2. Increased overjet (greater than six mm);

3. Deep overbite with palatal contact;

4. Severe crowding.

Two subjects, who had their posterior crossbite treated with a quad helix (QH) before the first examination, were scored according to their initial casts before age eight years. The consultant orthodontist made all treatment plans based on casts and radiographs. Two experienced general practitioners carried out the orthodontic treatments according to the plan. A QH was preferred for correction of posterior crossbite, and a headgear was usually the appliance of choice for the correction of sagittal relationships. No multibonded fixed appliances were used at this stage. Lingual/ palatal arches were used for space maintenance and retention.

After the next examination at age 10 years, the same criteria for starting treatment (DHC 4–5 and 10-Grade Scale 7–10) were applied, and treatments were started accordingly. Treatment need was not assessed during the phase of active treatment, but occlusions in retention were assessed. Data on examinations, dental visits, orthodontic treatment, and the appliances used were carefully recorded.

Data analysis

The data were analyzed in SPSS for Windows 8.0 (SPSS Inc, Chicago, Ill). Cohen's kappa20 was used to test the agreement between the treatment need indices. Pearson's chi-square test was used to test the differences between the sexes. Nonparametric related samples Wilcoxon signed ranks test was used to test the change in treatment need from eight to 12 years.

For intraexaminer reliability, the same examiner (Dr Väkiparta) reassessed after eight years the DHC scores of 38 randomly selected original casts. Intraexaminer agreement was substantial, a kappa value of 0.76.20 In 32 of 38 cases, there was complete agreement, and in the remaining six cases the error did not exceed one category.

Agreement between indices

The agreement between the indices was good at ages eight and 12 years and moderate at age 10 years. At the age of eight years, the agreement between the indices was found in 76 of 87 subjects (87%) (Table 1). In the other cases, the 10-Grade Scale score was higher than the DHC score in seven subjects and lower in four subjects.

TABLE 1.  Distribution of Assessments of Treatment Need Using the 10-Grade Scale (10-GS) and the DHC Component of IOTN. DHC Scores 1–2 and 10-GS Scores 1–4 Represent No/Slight Need, DHC 3 and 10-GS Score 5–6, Moderate Need, DHC 4–5 and 10-GS 7–10, Definite Need^a

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Treatment need

The distribution of treatment need did not significantly differ between boys and girls (P > .05) at any age; therefore, the results of both sexes were combined. A highly significant change in treatment need occurred from eight to 12 years (Wilcoxon signed ranks test, P < .001). The change of DHC category indicated diminished treatment need in 34 subjects, increased need in 15 subjects, and no change in 34 subjects. The majority of the no-change group consisted of subjects with no need for treatment at any age during the follow-up period (Figure 1).

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At the age of eight years, 29 subjects (33%) had a definite treatment need according to both indices (Table 1). The number of subjects with a definite treatment need markedly decreased during the study period. Correspondingly, the number of subjects with no treatment need increased during the same period, whereas the number of subjects with moderate treatment need remained approximately the same (Table 1). The most common reasons for starting treatment at age eight years were crossbite (12 subjects) and increased overjet (seven subjects) (Table 2).

TABLE 2.  Occlusal Traits Determining for Definite Treatment Need (DHC 4–5) at Age 8 Years^a

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Of the children having no treatment need at age eight years (38%), only two subjects showed definite need for treatment at age 12 years (Figure 1). In the definite treatment need group, two of 29 subjects had the same treatment need at age 12 years despite the early treatment and three subjects were still in active treatment (Figure 2). The shift from one treatment need category to another during the follow-up period was least predictable among subjects with moderate/optional treatment need at age eight years. Half of them moved into the no-need category, whereas the other half either remained unchanged or developed definite need for treatment (Figure 3).

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Orthodontic treatment up to 12 years of age

One-third (31 subjects) of the 87 subjects received some orthodontic treatment during the follow-up period. One of them had only extractions, and three (3%) had only space maintainers as treatment. After the eight-year examination, active treatment was started on 26 of the 29 subjects with definite treatment need, and at the 10-year examination, seven of those started were still in treatment. Between the 10- and 12-year examinations, treatment was started on two subjects only. Five children (6%) discontinued their treatment, and three were still having treatment at age 12 years.

Apart from the screening visit, most of the subjects (77%) visited the consultant orthodontist twice or less during their treatment (mean 1.8, SD 1.6). During their treatment the subjects visited the general dentist 11 times in average, and only two subjects had more than 16 visits (Table 3). The mean duration of treatment was two years (24 months), not including the space maintainers. Treatment time ranged from one to 61 months, but 59% of treatments lasted for two years or less. QH and headgear were the most common treatment options, and no separate retention appliances were used (Table 3).

TABLE 3.  Duration of Treatment and Number of Visits to the General Dentist Per Patient During Treatment With Different Orthodontic Appliances

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Treatment need

The clear reduction in treatment need from eight to 12 years reflects the favorable effect of early treatment on the target group. Marked improvement of malocclusion with early treatment has also been reported previously.627–29 However, our study subjects were clearly younger compared with the subjects of most previous early-treatment studies.61329

The no-treatment-need group showed least change during the dental development in our study and having no need at the age of eight years favored no treatment need at the age of 12 years. Among subjects who had moderate/optional treatment need in early mixed dentition, the pattern of moving from one category to another during the follow-up period was less predictable. A spontaneous decrease of treatment need was seen in one half of the cases, whereas in the other half, the need either increased or remained unchanged. This seems to support our policy of starting early treatment only in subjects with a definite need for treatment and to follow-up those with moderate/optional need to give time for eventual spontaneous correction and avoid overtreatment.

Treatment

The average duration of treatment was two years, which can be considered reasonable, particularly regarding the subjects, who improved from definite need to no-need category by the age of 12 years and who may therefore not need any other treatment. In our study the average duration of treatments was only half of that reported recently for treatments in some Finnish health centers.15 Both the duration of treatment and the number of dental visits varied significantly in our study, one probable reason being patient compliance. The prolonged treatments often ended in discontinuation because of the lack of compliance. Treatments with one appliance only, generally either with headgear or QH, were generally noncomplicated and commonly lasted for less than two years.

Random clinical trials on early treatment have focused on Class II treatment and concluded that the benefit of early treatment is not in preventing phase 2 treatment but perhaps in reducing the time and difficulty of the second phase.1213 In our study, crossbite was the most common single reason for early treatment, and its treatment concept is different. Second-phase treatment with fixed appliances cannot be considered to follow automatically, particularly in subjects whose treatment need index after early treatment indicates only mild need.

If the resources are limited, as they usually are in public health care, elimination of definite treatment need from a population by correction of severe malocclusions could be regarded as the primary aim of free of cost orthodontic treatment. The second phase for alignment of mild dental irregularities may often have to be ruled out as less important. Our results suggest that, in a number of cases, there may be a good chance to reach functionally and esthetically acceptable occlusion with early treatment only.