The characteristics of the children at the baseline and after 2.2-year follow-up are presented in Table 3. At the baseline, 15.6% of the girls and 11.4% of the boys had either overweight (11.4% and 6.7%, respectively) or obesity (4.2% and 4.7%, respectively) and after follow-up 15.3% of the girls and 18.8% of the boys had either overweight (12.5% and 15.2%, respectively) or obesity (2.8% and 3.6%, respectively). However, at both examinations the body fat percent was higher among girls. The most common malocclusions at the baseline and after follow-up were dental crowding (51.7% and 42.8%, respectively), distal molar occlusion (29.5% and 25.4%, respectively) and mandibular retrusion (28.4% and 34.1%, respectively). The proportion of children with decreased palatal width was 11.6% at the baseline and 10.9% after follow-up, while 14.9% had cross bite at the baseline and 8.7% after follow-up. Facial convexity at the baseline and increased lower facial height after follow-up were more frequent among boys.
Defined by the highest educational background of the family member, 18.7% of the families had a vocational school degree or less, 45.4% had a polytechnic degree and 35.9% a university degree. Annual household income was €30,000 in 18.5% of the families, €30,001-€60,000 in 44.0% of the families and >€60,000 in 37.5% of the families.
Table 3.Characteristics of the children at the baseline and after 2.2-year follow-up At baselineAfter 2.2-year follow-up All children (n=491) n (%) Girls (n=236) n (%) Boys (n=255) n (%) pAll children (n=414) n (%) Girls (n=202) n (%) Boys (n=212) n (%)
p Age, years,mean (SD) BMI,mean (SD) BMI-SDS, Finnish reference values, mean (SD) Body fat percentage,mean (SD) Sleep disordered breathing (SDB)
7.6 (0.4) 16.2 (2.2) 0.05 (1.1) 19.9 (8.3) 46 (9.9) 7.6 (0.4) 16.2 (2.2) -0.01 (1.0) 22.5 (7.8) 17 (7.6) 7.7 (0.4) 16.2 (2.1) 0.10 (1.1) 17.4 (8.0) 29 (12.0) 0.247 0.984 0.265 <0.001 0.105 10.1 (0.4) 17.2 (2.7) -0.13 (1.1) 23.4 (9.3) 38 (11.6) 10.1 (0.4) 17.1 (2.6) -0.15 (1.0) 25.3 (8.5) 15 (9.3) 10.1 (0.5) 17.4 (2.8) -0.11 (1.1) 21.5 (9.6) 23 (13.7)
0.242 0.164 0.694 <0.001 0.118 Distal molar occlusion Cross bite Open bite Crowding Scissors bite Convex facial profile Increased lower facial height Mandibular retrusion Decreased palatal width Tonsillar hypertrophy Vertically restricted throat Thick neck Adipose tissue under the chin Mouth breathing Orthodontic treatment
145 (29.5) 73 (14.9) 14 (2.9) 254 (51.7) 4 (0.8) 159 (32.4) 103 (21.0) 139 (28.4) 58 (11.6) 44 (9.0) 211 (43.3) 71 (14.5) 155 (32.3) 47 (9.6) 33 (6.7) 77 (32.6) 33 (14.0) 5 (2.1) 124 (52.8) 1 (0.4) 66 (28.1) 44 (18.7) 58 (24.7) 31 (13.2) 22 (9.4) 100 (42.6) 35(14.9) 72 (31.3) 19 (8.1) 17 (7.2) 68 (26.7) 40 (15.7) 9 (3.5) 130 (51.2) 3 (1.2) 93 (36.6) 59 (23.2) 81 (31.9) 27 (10.3) 22 (8.8) 111 (44.0) 36 (14.2) 83 (33.2) 28 (11.0) 16 (6.3) 0.148 0.596 0.344 0.726 0.625 0.044 0.222 0.077 0.316 0.819 0.821 0.739 0.657 0.270 0.681 105 (25.4) 36 (8.7) 5 (1.2) 177 (42.8) 11 (2.7) 154 (37.3) 94 (22.8) 141 (34.1) 45 (10.9) 35 (8.5) 129 (31.4) 9 (2.2) 71 (17.4) 23 (5.7) 79 (19.5) 60 (29.7) 17 (8.4) 2 (1.0) 85 (42.1) 3 (1.5) 72 (35.8) 35 (17.4) 61 (30.3) 22 (10.9) 19 (9.5) 63 (31.5) 4 (2.0) 33 (16.6) 8 (4.1) 44 (22.4) 45 (21.3) 19 (9.0) 3 (1.4) 92 (43.4) 8 (3.8) 82 (38.7) 59 (27.8) 80 (37.7) 23 (10.8) 16 (7.6) 66 (31.3) 5 (2.4) 38 (18.2) 15 (7.2) 35 (16.7) 0.051 0.844 0.523 0.787 0.126 0.548 0.012 0.114 0.975 0.486 0.962 0.539 0.670 0.187 0.148
Table 4 shows the questions and the distribution of parents´ answers in sleep questionnaire, based on which the children were defined as having SDB, both at the baseline and after follow-up. The most frequent answers were “usually breathing through the mouth” and “snoring quite loudly”. Observed apneas were few in number.
Table 4.Prevalence of single signs indicating SDB in the sleep questionnaire filled out by the parents Does your child breathe through the mouth at night?
never rarely sometimes
usually
always or almost always
95 (20.4) Have you noticed any pauses in your child’s breathing
pattern during sleep?
no rarely
sometimes usually
always or almost always
443 (95.1) How do you describe your child’s snoring best?
no snoring snores rarely
snores in certain positions snores most of the sleeping time snores frequently How loudly does your child snore?
no snoring Alternatives in italics included as having SDB
significant difference in the prevalence between the genders. Of the children, 41 (8.8%) snored in certain positions, 38 (8.2%) had nocturnal mouth breathing, 23 (5.0%) snored loudly, 9 (1.9%) snored frequently and 3 (0.6%) had frequent apneas. After follow-up, 11.6% (n=38) had SDB, with no statistically significant difference between genders.
Compared with the SDB prevalence of the same children at the age of 7, after follow-up in 5.2% (n=17) SDB persisted, in 6.4% (n=21) new cases appeared and in 4.8% (n=16) previous SDB disappeared (Figure 6).
Figure 6. Changes (%) in SDB from 6-8 to 9-11 years of age
no SDB 84 %
appeared unchanged 6 %
5 % disappeared
5 %
The changes in the dentofacial and pharyngeal morphology, mouth breathing and orthodontic treatment during the follow-up time are shown in the Table 5. In parallel with an increase in the number of children with previous or ongoing orthodontic treatment, many dental malocclusions have been corrected. Only the prevalence of mandibular retrusion increased during follow-up time.
Table 5. Dentofacial and pharyngeal abnormalities in children at the age of 7 years and at the age of 10 years, longitudinally
Adipose tissue under the chin Mouth breathing
bDefined as Mallampati et.al. Class III or IV
6.2 RISK FACTORS FOR SLEEP DISORDERED BREATHING AMONG CHILDREN AGED 6-8 AND 9-11- YEARS (STUDY I, IV)
Characteristics of the children with and without SDB at the baseline and after 2.2-year follow-up are presented in Table 6. Children 6-8 years of age with SDB were more likely to have cross bite, convex facial profile, increased lower facial height, mandibular retrusion, hypertrophic tonsils and mouth breathing than those without it. After follow-up, at the age of 9-11 years, children with SDB were more likely to have convex facial profile, mandibular retrusion and mouth breathing. There were no
characteristics between the children with SDB and those without it.
Table 6. Characteristics of the children with SDB and those without it at the baseline and at 2.2-year follow-up
Children examined at baseline
(n=466) Children examined at 2.2-year
follow-up (n=329)
Adipose tissue under the chin 16 (34.8) 133 (32.4) 0.748 11 (28.9) 47 (16.3) 0.056
Body fat percentageb 19.7 (8.8) 20.0 (8.3) 0.829 25.5 (10.1) 23.1 (9.1) 0.135b
Data are numbers (percentages) and p-values are from Chi-Square Test or from Fisher’s Exact Test
aDefined as Mallampati et al. Class III or IV
bData are means (standard deviations) and p-values are from Student’s T-test
The risk factors for SDB at the baseline and after 2.2-year follow-up are presented in Table 7. Children aged 6-8 years with SDB were more likely to have tonsillar hypertrophy, cross bite and convex facial profile than those without it. Children with tonsillar hypertrophy had a 3.7-fold higher risk of suffering SDB than those with normal size tonsils after adjustment for age, sex and body fat percentage. Furthermore, children with cross bite had a 3.3-fold higher risk of having SDB than those without
cross bite, while children with a convex facial profile had a 2.6-fold higher risk of having SDB than those with a normal facial profile. Other craniofacial abnormalities or body fat percentage were not associated with the risk of having SDB among this age group. Children 9-11 years of age with SDB were more likely to have mouth breathing, adipose tissue under the chin and previous or ongoing orthodontic treatment. Children with mouth breathing had a 5.4-fold higher risk of suffering SDB than children with nasal breathing.
Table 7. The risk factors for SDB at the age of 6-8 years and at the age of 9-11 years
Relative risk 95% confidence interval
p-value
Risk factors at the age of 6-8 Tonsillar hypertrophy
Cross bite
Convex facial profile
Risk factors at the age of 9-11 Adipose tissue under the chin Mouth breathing Data are from stepwise logistic regression models, the effect of gender was considered in each step.
Only statistically significant determinants are given
6.3 PREDICTORS OF SLEEP DISORDERED BREATHING IN