INTRODUCTION

Maturation of various tissue systems (ie, bony age, tooth formation, subcutaneous fat thickness, and menarche in girls) has been used in the literature to describe the developmental stages of growing children. So far, there has been no consensus regarding the relationship between skeletal and dental age. Some researchers1 reported a high correlation (r = 0.83), while others23 a much lower one (r = 0.77 and r = 0.46 respectively). Chertkow and Fatti4 examined the relationship between the sesamoid bone and the calcification of the cuspids and found a high correlation (r = 0.8) between them; however, their findings were questioned by others.5

One factor that might explain the different correlations the various studies observed between skeletal maturation and dental maturation or dental eruption could be the difficulty in assessing skeletal maturity, because many of the centers of ossification used to determine skeletal maturity exhibit a considerable variation in the timing of their onset. Sierra5 found a high correlation (r = 0.7 to r = 0.8) between dental calcification and skeletal age by using an eight-ossific-centers-method, while lower associations (r = 0.3 to r = 0.7) were recently reported in a Thai population.6

Hägg and Taranger found a low correlation (r = 0.35) between pubertal growth and dental eruption stages,7 whereas Vallejo-Bolanos and Espana-Lopez8 found a marked positive relationship between dental development and body growth. In addition, Chertkow9 observed a high correlation (r = 0.88) between pubertal age and the calcification stages of the lower canine.

Nanda10 observed some disparity in the timing of the facial adolescent growth spurt between subjects with skeletal open bite and those with deep bite. Subjects with skeletal open bite presented the onset of the adolescent growth spurt in the facial measurements earlier than those with deep bite. He suggested a possibility of delaying orthodontic treatment of patients with a skeletal deep bite because of a later onset of their growth spurt. According to him, the delay might be also beneficial for the retention, as a much shorter retention period might be required.

Janson et al11 conducted the first study to investigate the influence of facial type on dental development in subjects of the same chronological age. They showed that long face subjects presented a tendency to have an advanced dental maturation in comparison to short face subjects, expressed by a mean difference in dental age of 6 months. However, the sample included in his study was rather small, and the two extreme groups were overlapping each other, which might have obscured the results.

The aim of the present study is to investigate the relationship between vertical skeletal pattern and dental maturation in children with long or short anterior facial height.

MATERIALS AND METHODS

Methods

The following cephalometric landmarks and measurements were used to describe the subjects' vertical facial characteristics (Figure 1):

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Landmarks:

• ANS—anterior nasal spine;

• N—nasion;

• Me—menton;

• S—sella;

• Go—gonion;

• Gn—gnathion; and

• Incisal edges of the upper and lower incisor.

Measurements:

• LAFH—lower anterior face height, anterior nasal spine to menton (ANS-Me);

• TAFH—total anterior face height, nasion to menton (N-Me);

• ANS-Me/N-Me—the percentage of lower anterior face height (ANS-Me) to total anterior face height (N-Me);

• Overbite—the vertical distance from the incisal edge of the upper incisor to the incisal edge of the lower incisor;

• Mandibular plane angle according to Steiner—the angle between the S-N plane and the Go-Gn plane; and

• SN/Go-Gn—sella-nasion to gonion-gnathion angle.

Each lateral cephalogram was traced on acetate paper by one examiner. Landmarks defined in x-y coordinate system (Figure 1) were digitized by means of a digitizer.

RESULTS

Based on the total of 312 subjects, the regression analysis did not find a significant relationship between facial height and dental age (P = .6 after correction for sex and chronological age).

The means and standard deviations of the total sample of 312 patients are presented in Table 1.

TABLE 1. Overall Characteristics of Study Sample

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To demonstrate that there is no significant influence of face height on dental age, two extreme groups were compared: short face ratio <56 and long face ratio ≥59. The results of the comparison are presented in Table 2. The age discrepancy, represented by the age difference (ie, the difference between the dental and the chronological age), was almost equal for both groups: 0.6 years for the long face patients and 0.7 years for the short face patients. The above result, therefore, confirmed that there was no significant difference in the dental age between the two extreme groups. The power of the study was 79% (2-sided test) and 87% (1-sided test).

TABLE 2. Comparison of Two Extreme Groups: Ratio <56 and ≥59

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Table 2 also demonstrates a large difference in overbite and SN/Go-Gn angle between the long facial height and the short facial height groups. Regression analysis showed that the facial height ratio can be explained from both the overbite (r = 0.38) and SN/Go-Gn angle (r = 0.46), after correction for sex and age (P < .00005).

When we limited the age range of the two extreme groups from 9–12.9 years to 9–11.0 years, our findings were somewhat different. There was a slight tendency toward more advanced dental age in the short facial height group, which is exactly the opposite to the findings of Janson et al11; however, the results were not statistically significant (Table 3).

TABLE 3. Comparison of Two Extreme Groups: Ratio <56 and ≥59

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The same tendency was observed when we changed the ratio into <55 and ≥60, age range 9– 11.0 years.

DISCUSSION

The method of Demirjian et al1314 is a reliable and convenient method to determine the dental age using a scoring system based on objective criteria. The intraexaminer reliability in dental age assessment in the present study was very high.

The maturity standards of Demirjian are based on a sample of French-Canadian children. It has been shown that different patterns of dental maturation exist between various population groups,1617 so that the standards of dental age determination may need to be adjusted for the specific population studied. However, because in the present study two groups of the same population were compared, possible differences in dental development between Dutch and French-Canadian children would have equally influenced the two groups.

The findings of the present study showed no significant differences in dental development between the short face and the long face skeletal types. This is contrary to previous findings. Although Janson et al11 found statistically significant difference between the two vertical facial types, the sample he used was rather small to draw reliable conclusions. Moreover, the skeletal open bite and deep bite groups included in their study were overlapping each other. Thus, two subjects with exactly the same vertical parameters could have been assigned to two extreme groups: the open bite and the deep bite group. We believe that a clear-cut definition of the short and long face groups, excluding the subjects with hybrid vertical characteristics, is crucial in this type of study.

One might wonder whether the discrepancy between the findings of the present study and those of Janson et al11 might have been caused by the age differences between the samples of both studies. Hägg and Matsson18 showed a high accuracy of the Demirjian method for younger age groups, while the accuracy of the method became less in older children. It is possible that in younger age groups the differences in dental maturity between the two skeletal types are more pronounced; therefore, within a few years, the “catch-up” process would obscure those differences. However, when we limited the sample of the present study to include only the subjects whose age range was 9–11.0 years, the results were contradictory to those quoted in the literature. There was a slight tendency toward a more advanced dental age in the short face group and not in the long face group.

To avoid any possible influence of secular trend,19 care was taken to include only those patients who were seen at our department in the period 1990–2000. However, the sample may have differed from the sample of Janson et al11 in this respect and thus may have influenced the outcome of both studies.

CONCLUSIONS

• No statistically significant differences in dental age were present between the subjects with short anterior facial height and long anterior facial height.

• Subjects with short anterior facial height presented a slight tendency toward a more advanced dental age than those with long anterior facial height.