Occlusal traits of 4–5‐year‐old Estonians. Parents' perception of orthodontic treatment need and satisfaction with dental appearance

Abstract This study aims to evaluate the prevalence of occlusal traits and to assess parents'/caregivers' satisfaction with child's dental appearance and perception of orthodontic treatment need in 4–5‐year‐old Estonians. Clinical records and plaster casts of 390 children (190 girls and 200 boys, mean age 4.7 years, range 4 – 5 years) were analyzed. Assessed occlusal traits included deciduous canine and second molar sagittal relationship, overjet, overbite, crowding, midline diastema, crossbite, and scissor bite. Parents'/caregivers' opinions regarding their child's teeth were determined with a questionnaire. The most prevalent occlusal traits were symmetrical sagittal relationship in deciduous canines (78.2%) and molars (75.1%), Class I sagittal relationship in deciduous canines (69.7%) and midline diastema (67.7%). Asymmetrical sagittal canine relationship was registered in 21.8% deciduous canines and in 24.9% second deciduous molars. Parents'/caregivers' perceived orthodontic treatment need was related to Class III sagittal relationship in canines, increased overjet and overbite, negative overbite, and crossbite. Prevalence of most occlusal traits in Estonian children were in line with those reported in neighboring countries. Parents/caregivers were well able to observe occlusal traits that deviated from acceptable occlusion.

has provided a baseline analysis of longitudinal dental development between ages 3 and 18. Cross-sectional studies of occlusal traits in different age groups give an overall picture of dental development in the population and assist in recognizing the individuals in need of closer follow-up (Brunelle, Bhat, & Lipton, 1996;Thilander, Pena, Infante, Parada, & de Mayorga, 2001).
This study is the third in a series of cross-sectional investigations analyzing the prevalence of occlusal traits in Estonians between the ages of 4 and 21 years.
The aims of this study were to evaluate • The distribution of occlusal traits in Estonian 4-5-year-olds.
• Parents'/caregivers' satisfaction with their children's dental appearance and their perceptions on orthodontic treatment need in this age group.
Work hypotheses of this study were that • The prevalence and types of occlusal traits in Estonia do not differ significantly from those in neighboring countries in the age group of 4-5 years.
• Occlusal traits observed by parents/caregivers differ from those observed by orthodontic professionals.

| Registration of occlusal traits
The following occlusal traits were registered clinically in centric occlusion by one orthodontist (Examiner 1): (a) sagittal relationships in deciduous canines and second molars separately for right and left side, To obtain centric occlusion, a child was asked to open mouth only slightly. The orthodontist gently verified that mandible was relaxed, then the child was asked to bite together.
The examination was carried out in the kindergarten's medical office using a dental mirror, probe, pencil (0.3 mm), and millimeter ruler (with 0.5 mm intervals; Dentaurum 042-751 Münchner Modell).
The clinical study was complemented with alginate impressions for plaster casts. Preshaped bite registration wax was softened in warm water bath and placed against the upper dental arch; relaxed mandible was gently guided into centric occlusion to get indentations of cusps of lower teeth into registration wax.
Examiners 1 and 2 registered three features from the plaster casts in consensus: (a) end-to-end relationship of the deciduous canines and second molars, separately for the right and left side, (b) crowding, and (c) diastemas between central incisors.

| Questionnaire
Opinions regarding children's general dental health, tooth alignment, dental appearance, and orthodontic treatment need were collected with a questionnaire filled in at home by parents/caregivers. More

FIGURE 1
The flow chart describing refining of the final sample than one answer per question was allowed. The questionnaire was modified from one used in a previous study (Pietilä & Pietilä, 1996).

| Reliability and statistical analysis
Twenty-two children were reexamined clinically by Examiner 1 after a 1-week interval before the intended study. The reliability was very good (r > 0.99). A total of 122 plaster casts were reexamined for calibration after 1 month by Examiners 1 and 2 together. The

| RESULTS
In the current study, there were a total of 28 children (7.2%) with symmetrical flush terminal plane and Class I in deciduous canines, OJ 1-3 mm and OB 1-3 mm, no crowding, scissor bite or crossbite. Of their parents/caregivers, 23 (85.2%) were satisfied with the alignment of teeth.
Asymmetrical sagittal relationship in deciduous canines was found in 21.8% and in second deciduous molars in 24.9% of the examinees ( Figure 2). Children with asymmetric end-to-end sagittal relationship in canines had statistically significantly more crossbites compared with children with symmetric end-to-end sagittal relationship (p < 0.01).
A statistically significant gender difference was found in OJ. Boys had on average larger OJ than girls (boys 2.2 ± 1.4 vs. girls 1.9 ± 1.4, p < 0.01), and there was a trend of more boys with increased OJ (OJ ≥ 3.5 mm) compared with girls (p = 0.06).  Posterior crossbite was observed in 6.7% on the right side, in 4.3% on the left side, and in 6.4% on both sides. One child had a scissor bite on the right and one on the left side. None of the children had bilateral scissor bite.

| Parents'/caregivers' satisfaction
The children whose parents/caregivers were satisfied with the arrangement of their child's teeth had significantly less scissor bite (p = 0.02), increased OB (p = 0.01), negative OB (p < 0.01), and Class III sagittal relationship in canines (p = 0.05), compared with children whose parents were dissatisfied with the arrangement of their child's teeth (Table 2).
Distribution of symmetric and asymmetric sagittal molar relationships in Estonian children was in line with that of Finnish children (Keski-Nisula et al., 2003).
In our study, the prevalence of posterior crossbite was significantly higher in children with asymmetrical than symmetrical sagittal relationship. Prevalence of bilateral crossbite in Estonians was equal to that of Swedes (Dimberg et al., 2013)   The prevalence of midline diastema in 4-5-year-olds (67.7%) reflected that of 7-10-year-old Estonians (73.0%) (Sepp et al., 2017).
This finding conforms with the idea that the structure of the frenulum influences the position of central incisors.
There was no crowding in any of the studied 4-5-year-old Estonians. This finding is contrary to the situation in Finland, where crowding in the maxilla has been found in 11.6% and in the mandible in 38.9% of children (Keski-Nisula et al., 2003). The difference was clear, although crowding was measured on plaster casts in both of these studies.
Benefit of orthodontic treatment is estimated by a dentist using professional criteria. Patients/parents/caregivers make their own observations, which are equally important in judgment of treatment need and outcome. Therefore, it is important to know how parents/caregivers, as laypersons, observe dentition and how critical they are (Ryan & Cunningham, 2018).
What this paper adds?
• Prevalence of most occlusal traits in Estonian 4-5-year-olds is in line with those reported in neighboring countries, except for negative OB, increased OJ, and lack of crowding.  To improve dental appearance 27 16.9 To improve occlusal function 21 13.1 Other reason 17 10.6 To facilitate cleaning 11 6.9 Total 160 100.0 • The most prevalent occlusal traits in Estonian 4-5-year-olds are symmetrical sagittal relationship in deciduous canines and molars, Class I sagittal relationship in deciduous canines, mesial terminal plane in deciduous second molars, and midline diastema.
• With regard to dental health and appearance, more than four out of five parents/caregivers are satisfied. Dissatisfied parents seem to focus on occlusal traits like negative OB, deep bite, and Class III relationship in canines.
• The hypothesis that parents/caregivers do not pay attention to professionally important traits in their child's dentition is rejected.
Why this paper is important for dentists?
• It is important to know that the majority of 4-5-year-old children have occlusal traits that may develop into malocclusion.
• Dental professionals should appreciate parents'/caregivers' observations regarding their child's occlusal traits and functioning of the masticatory system. They seem to be well able to observe occlusal traits and functions that deviate from the so-called "normal."