Abstract

Orthodontic treatment is a common dental procedure in developed countries. However, the frequency and factors associated with treatment demand are different between countries. The aim of this study was to examine the frequency of orthodontic treatment in German children and adolescents and to analyse the influence of age, gender, and socio-economic status (SES; education and region) on the frequency of treatment. Subjects in a random population sample of 1538 German children and adolescents, aged 11–14 years, were interviewed at home in the autumn of 2008 regarding current orthodontic treatment and associated factors. Approximately one-third (33.5 per cent) of the subjects interviewed were undergoing orthodontic treatment at that time.

In a multivariable logistic regression model, the likelihood of receiving orthodontic treatment was higher for girls [odds ratio (OR) = 1.32, 95 per cent confidence interval (CI): 1.06–1.65], for high school pupils (OR = 1.19, 95 per cent CI: 1.06–1.34), and for children and adolescents living in the western part of Germany (OR = 1.45, 95 per cent CI: 1.00–2.08) and increased with age (OR = 1.13 per year, 95 per cent CI: 1.02–1.25). Subjects undergoing orthodontic treatment more often received prophylactic measures (OR = 2.06, 95 per cent CI: 1.63–2.59) compared with those not currently receiving orthodontic treatment. The frequency of orthodontic treatment in Germany largely depends on gender and SES.

Introduction

Two studies from the 1990’s have reported high rates of children and adolescents in Germany receiving orthodontic treatment at the expense of the public health insurance system [Gesetzliche Krankenversicherung (GKV)]: 52 per cent in one study (Hensel, 2001) and 67 per cent in another (Schopf, 2001). These rates are substantially higher in comparison with international data (Harzer and Wiesner, 1998; Tickle et al., 1999). Depending on age, country, region, and indices used, these authors reported rates of orthodontic treatment in Europe ranging from 15 to 63 per cent (mean 45 per cent). Taken together, these data indicate that Germany has an international leading position in providing orthodontic treatment (Micheelis, 1991). However, given that the available data are 20 years old and numerous changes in the German health care system have occurred over that time, it is likely that the frequency of orthodontic treatment in Germany has also changed.

In 2002, a system of orthodontic indication groups [Kieferorthopädische Indikationsgruppen (KIG)] was introduced in Germany (Schopf, 2004). The KIG system is a derivative of the Index of Orthodontic Treatment Need (IOTN) described by Brook and Shaw (1989) and Shaw et al. (1991b). The KIG is used to regulate access to orthodontic treatment in the public health insurance system (Table 1). Before the introduction of the KIG, access to orthodontic treatment at the expense of the GKV in Germany was nearly unlimited because the need for treatment was determined by the orthodontist. Accordingly, after implementation of this system, it would be expected that the level of orthodontic treatment in Germany would be reduced, perhaps to levels comparable with those seen internationally. In terms of treatment need, recent studies have produced wide ranging results. Using the IOTN, Tausche et al. (2004) reported a 26.2 per cent need for treatment in 6- to 8-year-old children in East Germany. This finding is consistent with those observed for children 9–12 years old in France (21.3 per cent; Souames et al., 2006). Perillo et al. (2010) found a 27.3 per cent treatment need according to the IOTN for 12-year-old schoolchildren in southern Italy. In a recent study of German schoolchildren using the KIG system, a need for treatment in 41.4 per cent of the sample was identified (Glasl et al., 2006).

Table 1

Classification of orthodontic treatment need using German orthodontic indication groups (KIG).

Malocclusion
 
Severity grade
 
1 (mm) 2 (mm) 3 (mm) 4 (mm) 5 (mm) 
Craniofacial anomalies     Cleft palate and syndromes 
Missing teeth    Agenesis or loss  
Disturbance of eruption    Impaction Displacement 
Sagittal discrepancy increased overjet <3 3–6  6–9 >9 
Sagittal discrepancy negative overjet    0–3 >3 
Vertical discrepancy open bite <1 1–2 >2–4 >4 habitually open >4 skeletally open 
Vertical discrepancy deep bite >1–3 >3 with/without mucosal contact >3 with traumatic mucosal impingement   
Transverse discrepancy    Scissor bite  
Transverse discrepancy crossbite  Buccolingually cusp-to-cusp relationship Bilateral crossbite Unilateral crossbite  
Contact point displacement <1 >1–3 >3–5 >5  
Space deficiency  <3 3–4 >4  
Malocclusion
 
Severity grade
 
1 (mm) 2 (mm) 3 (mm) 4 (mm) 5 (mm) 
Craniofacial anomalies     Cleft palate and syndromes 
Missing teeth    Agenesis or loss  
Disturbance of eruption    Impaction Displacement 
Sagittal discrepancy increased overjet <3 3–6  6–9 >9 
Sagittal discrepancy negative overjet    0–3 >3 
Vertical discrepancy open bite <1 1–2 >2–4 >4 habitually open >4 skeletally open 
Vertical discrepancy deep bite >1–3 >3 with/without mucosal contact >3 with traumatic mucosal impingement   
Transverse discrepancy    Scissor bite  
Transverse discrepancy crossbite  Buccolingually cusp-to-cusp relationship Bilateral crossbite Unilateral crossbite  
Contact point displacement <1 >1–3 >3–5 >5  
Space deficiency  <3 3–4 >4  

A severity grade score more than or equal to 3 is the cut-off for orthodontic treatment for children (aged less than 18 years) in the public health insurance system (Schopf, 2004).

However, the frequency of subjects actually receiving orthodontic treatment is not only associated with treatment need based on morphological discrepancies but also with a number of other factors, such as gender (Burgersdijk et al., 1991; Burden 1995; O’Brien et al., 1996; Kerosuo et al., 2000), residence (urban versus rural; Bergström et al., 1998; Drugan et al., 2007), and ethnicity (Josefsson et al., 2005; Bissar et al., 2007). To date, the influence of socio-economic status (SES) on the frequency of orthodontic treatment has not been clearly established. Kenealy et al. (1989) found such a connection, that is, a different rate of orthodontic treatment by families from different social classes, in a study of 1018 children in Wales. In contrast, Burden (1995) reported that familiarity with orthodontic appliances among a subject’s peer group had a greater influence on the uptake of orthodontic treatment than the subject’s social class or gender. Furthermore, the effects of insurance systems (Proffit et al., 1998; Kerosuo et al., 2002) or the density of dentists (O’Mullane and Robinson, 1977) on orthodontic treatment frequency have been observed. Therefore, the aim of the present population-based study was to investigate the frequency of orthodontic treatment in German children and adolescents and to analyse the influence of age, gender, and indicators of SES (region and education) on treatment frequency.

Subjects and methods

The subjects were drawn from the ‘Oral Health Related Quality of Life in Children and Adolescents’ project that was conducted in Germany during 2008. The study protocol was approved by the Institutional Review Board of the University of Leipzig (Registration Number 112–2007).

A market research organization selected a random sample of addresses of families with children and adolescents aged 11–14 years of age. This sample, known as the Arbeitsgemeinschaft Deutscher Marktforschungsinstitute (ADM), was designed as a three-step area sample covering all populated areas of Germany (ADM, 2010). It is based on Germany’s topology, organized by states, counties, and communities, the statistical areas within communities described by public data, and the geographic data created for traffic navigation systems. Combining these data, the area sample is made up of approximately 53 000 areas, each containing at least 350 but on average about 700 private households. Prior to sampling, the areas are first regionally stratified according to counties and the types of communities differentiated according to the number of inhabitants resulting in 1500 strata. Based on this stratification, 128 ‘nets’ are extracted containing 210 areas in former West Germany and 48 areas in former East Germany (first step). These 258 sampling points (= areas) are drawn proportionally to the distribution of private households. In the second step, the private households and within them, the individuals (third step) are selected randomly using systematic selection methods with a random start. The sampling procedure according to the ADM technique actually reaches a response proportion of 69 per cent (Weidner et al., 2009). The aim in this study was to reach a sample with more than 1500 subjects. Overall, 1538 responding families took part and the 11- to 14-year-old children/adolescents (one per family) were interviewed in person by a trained female interviewer at their home. All responding subjects/parents gave their written consent to participate. Subjects were interviewed in the autumn of 2008.

Variables

The outcome of interest was the frequency of orthodontic treatment. The interviewer asked each subject the question ‘Do you have an orthodontic appliance?’, as well as examining the subject for the presence of fixed or removable orthodontic appliances. All types of appliances (or parts of them) were scored as ‘orthodontic treatment yes’. The interviewer also gathered information on age, gender, region, and type of school attended by each subject. Age and gender were assessed as potential factors associated with the frequency of orthodontic treatment. The region (east–west) and type of school (high school and secondary school) were considered indicators for higher or lower SES (Geißler and Meyer, 2008), which was also assessed as a potential factor associated with treatment frequency. The type of school was chosen as a variable to describe SES of the study subjects because more than 65 per cent of high school pupils in Germany come from a family with higher education and income (Geißler and Meyer, 2008). Therefore, the type of school is a good proxy for SES in Germany. In addition, subjects were asked about whether they had participated in prophylactic programmes at their dentist’s office during the previous year.

Statistics

The distribution of orthodontic treatment (treatment yes or no and fixed or removable) in the study population was reported by age and tested for statistical significance using the chi-square test. A t-test for independent samples was used to determine the statistical significance of the continuous variable of age, and the chi-square test to evaluate the statistical significance of the categorical variables (gender, school type, region, and prophylactic measures). The odds ratios (ORs) and 95 per cent confidence intervals (CIs) were estimated to indicate the likelihood of receiving orthodontic treatment and prophylactic treatment by a multivariable logistic regression model, adjusting for age (per year), gender (female versus male), region (West versus East Germany), and education (high school versus secondary school). A P-value of <0.05 was considered statistically significant.

Results

Of the 1538 subjects, approximately one-third (33.5 per cent) were receiving orthodontic treatment. The treatment frequency was significantly different in the various age groups (Table 2). Fixed and removable appliances were observed in 17.5 and 16.0 per cent of the subjects, respectively. No significant difference in the use of fixed or removable appliances was found among the age groups (Table 2) or between East and West Germany (data not presented).

Table 2

Frequency of current orthodontic treatment in German children and adolescents aged 11-14 years in 2008.

Orthodontic treatment All (N = 1538) 11 years (N = 388) 12 years (N = 385) 13 years (N = 380) 14 years (N = 385) P 
% (N)
 
 
No 66.5 (1023) 73.2 (284) 63.9 (246) 66.8 (254) 62.0 (239) 0.006 
Yes 33.5 (515) 26.8 (104) 36.1 (139) 33.2 (126) 38.0 (146) 
Fixed 17.5 (269) 15.7 (61) 21.3 (82) 14.0 (53) 19.0 (73) >0.05 
Removable 16.0 (246) 11.1 (43) 14.8 (57) 19.2 (73) 19.0 (73) 
Orthodontic treatment All (N = 1538) 11 years (N = 388) 12 years (N = 385) 13 years (N = 380) 14 years (N = 385) P 
% (N)
 
 
No 66.5 (1023) 73.2 (284) 63.9 (246) 66.8 (254) 62.0 (239) 0.006 
Yes 33.5 (515) 26.8 (104) 36.1 (139) 33.2 (126) 38.0 (146) 
Fixed 17.5 (269) 15.7 (61) 21.3 (82) 14.0 (53) 19.0 (73) >0.05 
Removable 16.0 (246) 11.1 (43) 14.8 (57) 19.2 (73) 19.0 (73) 

No substantial difference was observed in the mean age of the subjects currently receiving orthodontic treatment compared with those not undergoing orthodontic treatment, although the difference was statistically significant (Table 3). In contrast, a clear difference was found in the proportion of subjects receiving prophylactic treatment (Table 3). The data also showed that subjects undergoing orthodontic treatment were more often females and attended a high school. The proportion of subjects in the sample undergoing orthodontic treatment who came from the western part of Germany was slightly, but not statistically significantly, higher than those from the east (unadjusted data, Table 3). The multivariable model confirmed the observation that the frequency of orthodontic treatment increased with age and was more prevalent in girls and in high school pupils (Table 4). The likelihood of receiving orthodontic treatment for subjects living in the western part of Germany became statistically significant in this model (i.e. the 95 per cent CI of the estimate does not include ‘1’). Subjects currently undergoing orthodontic treatment were more than twice as likely to take part in prophylactic programmes in the dental office (OR = 2.06, 95 per cent CI: 1.63–2.59) compared with those not currently undergoing orthodontic treatment.

Table 3

Sample characteristics stratified according to orthodontic treatment. SD, standard deviation.

Variables All subjects (N = 1538) Orthodontic treatment yes (N = 515) No orthodontic treatment (N = 1023) P 
Mean age in years (SD) 12.5 (1.2) 12.6 (1.1) 12.4 (1.1) 0.004 
Females % (N49.1 (755) 55.1 (284) 46.2 (473) 0.001 
High school % (N30.6 (470) 36.5 (188) 27.6 (282) 0.002 
Prophylaxis participation % (N53.7 (826) 65.8 (339) 47.7 (488) <0.001 
West Germany % (N84.9 (1305) 87.2 (449) 83.7 (856) >0.05 
Variables All subjects (N = 1538) Orthodontic treatment yes (N = 515) No orthodontic treatment (N = 1023) P 
Mean age in years (SD) 12.5 (1.2) 12.6 (1.1) 12.4 (1.1) 0.004 
Females % (N49.1 (755) 55.1 (284) 46.2 (473) 0.001 
High school % (N30.6 (470) 36.5 (188) 27.6 (282) 0.002 
Prophylaxis participation % (N53.7 (826) 65.8 (339) 47.7 (488) <0.001 
West Germany % (N84.9 (1305) 87.2 (449) 83.7 (856) >0.05 
Table 4

Results of the multivariate analysis: likelihood of receiving current orthodontic treatment for German children and adolescents aged 11-14 years in 2008.

Variables Odds ratio Confidence interval P 
Age (per year) 1.13 1.02–1.25 0.017 
Gender (female versus male) 1.32 1.06–1.65 0.013 
Region (West versus East Germany) 1.45 1.00–2.08 0.047 
School type (high school versus secondary school) 1.19 1.06–1.34 0.003 
Variables Odds ratio Confidence interval P 
Age (per year) 1.13 1.02–1.25 0.017 
Gender (female versus male) 1.32 1.06–1.65 0.013 
Region (West versus East Germany) 1.45 1.00–2.08 0.047 
School type (high school versus secondary school) 1.19 1.06–1.34 0.003 

Discussion

The frequency of orthodontic treatment in Germany in approximately one-third of the population of 11–14 years old analysed was high. It was also found that the frequency of orthodontic treatment largely depends on gender and indicators of SES (education and region); that is, high school girls in West Germany were twice as likely to be treated orthodontically compared with boys from the East.

The data presented in this study are recent and, due to the sampling procedure used, representative of all German children and adolescents aged 11–14 years. It is considered that the sample is representative because the proportion of subjects attending a high school (31 per cent) is nearly the same (33 per cent) reported by Geißler and Meyer (2008) for Germany in a national survey. A further advantage of this study in contrast to the research of Whitesides et al. (2008) was that all subjects were interviewed personally, and the trained interviewer had the opportunity to confirm first-hand the presence or absence of orthodontic appliances.

Compared with data from the 1990s that reported on orthodontic treatment frequency before unlimited access to orthodontic treatment at the expense of the GKV was controlled by introduction of the KIG system, the current frequency (33.5 per cent) identified in this study for German children 11–14 years of age represents a decrease of 20–30 per cent. Despite this reduction over the past 20 years, the frequency of orthodontic treatment provision in Germany still exceeds that in other countries for this age group: USA, 18 per cent (Brunelle et al., 1996) and UK, 8–14 per cent (Chestnutt et al., 2006). However, the sample was not assessed for early orthodontic treatment (tooth extractions and interceptive orthodontic treatment) because it was not expected that valid information could be obtained given previous reports that parents/children exhibit poor recall of earlier orthodontic treatment (Baird and Kiyak, 2003). The sample was also not assessed for orthodontic treatment need based on morphological or aesthetic criteria. For this reason, it was not possible to analyse the association between treatment need/demand and treatment frequency, which is a limitation of the study.

In Germany, according to the regulations of the KIG system, most orthodontic treatment is carried out at the end of the second phase of the dentition (i.e. when the age of children is between 11 and 14 years). Fluctuations in the prevalence of orthodontic treatment frequency within the age groups were observed, but in general, a moderate increase between 11 and 14 years of age was present. The data further confirmed previous findings of a higher frequency of orthodontic treatment for girls (Burgersdijk et al., 1991; Burden et al., 1994; Burden, 1995; O’Brien et al., 1996; Kerosuo et al., 2000). This fact seems to be independent of the particular country or health service system and may be an indicator of a higher health care utilization by females in general. According to Perillo et al. (2010), no significant differences in treatment need between genders could be found. Despite this finding regarding treatment need, one reason for a difference in orthodontic treatment frequency might be that the social acceptance of dental deviations is lower for females (Zhang et al., 2010).

The observed influence of SES on orthodontic treatment frequency is not surprising. A high social status of parents is associated with higher education as well as an increased demand for orthodontic treatment for their children (Shaw et al., 1991a; Reichmuth et al., 2005). Moreover, the likelihood of discontinuation of orthodontic treatment in families with low SES is also assumed to be higher (Rölling, 1982; Turbill et al., 2003). The lower proportion of orthodontic treatment of subjects with a lower SES might be due to financial constraints (Page and Thomson, 2005) and a possible higher tolerance for dental deviations in these social groups.

The German system of public health insurance provides free orthodontic treatment for children upon reaching the agreed limits of the KIG classification for a particular dental anomaly. The availability of free medical treatment has an effect on the demand for orthodontic treatment (Kerosuo et al., 2002). A public health insurance system should produce a comparable orthodontic treatment frequency for all patients in all regions. The higher proportion of subjects receiving orthodontic treatment in West Germany observed in this study may be due to a proportion of those subjects in the sample being treated on a private basis, without KIG indication, based on the ability of their parents to finance treatment. This financial ability is directly related to the SES of the parents, which in turn is related to the place of residence (e.g. purchasing power is lower in East Germany; Gesellschaft für Konsumforschung, 2008). However, information regarding private orthodontic treatment was not asked for because valid information was not expected for two reasons: nearly all orthodontic treatments in Germany are linked with an additional payment by the parents, even if the main part of the treatment is provided by the GKV and only a minority (8 per cent) of the population has private health insurance. It could be, however, that the inability to afford the additional payment associated with GKV orthodontic treatment may be a factor for the lower utilization of the GKV orthodontic treatment service in East Germany.

The number of orthodontists per capita in Germany (1:27 779) is higher than that of other European countries (e.g. Spain 1:100 000; UK 1:73 333.; van der Linden et al., 2004). No significant difference exists in the number of orthodontists per capita between the former East and West Germany (Bundeszahnärztekammer, 2009). In a previous study, the number of dentists was found to be correlated with the number of individuals receiving dental treatment (O’Mullane and Robinson, 1977); thus, it was assumed that a similar correlation exists for orthodontists and orthodontic treatment. On the other hand, general dentists also play a key role in determining orthodontic treatment levels (Birkeland et al., 1999).

The high proportion of removable appliances observed in the current sample can be explained through historical context as a higher use of these devices is known to occur in the German-speaking area based on the concepts of Andresen, Häupl, Petrik, Eschler, and Balters (Schmuth, 1983). Another reason for the frequent use of removable appliances is the payment structure in the GKV system in Germany, which favours removable appliances.

Finally, a higher proportion of participation in dental prevention programmes (65.8 per cent) was observed for orthodontically treated children when compared with children who were not receiving orthodontic treatment (47.7 per cent). This participation in prophylactic treatment by orthodontic patients is a positive side-effect of orthodontic treatment as the specific risks of demineralization under conditions of poor oral hygiene in association with fixed appliances can be more regularly monitored.

Conclusions

The data suggest that the frequency of orthodontic treatment in German children and adolescents largely depends on their gender and SES. With the introduction of the KIG system, the number of German children undergoing orthodontic treatment has decreased, although it still exceeded the levels observed for other countries. A free public insurance system that covers orthodontic treatment does not necessarily produce an equal utilization of such treatments, due to differences between girls and boys and the influence of SES on the availability and rate of treatment, as indicated in this study. The higher proportion of prophylactic measures in subjects receiving orthodontic treatment is a positive side-effect of orthodontic care.

Funding

GABA International, Therwil, Switzerland (S-200703X).

References

Arbeitsgemeinschaft deutscher Marktforschungsinstitute (ADM)
2010
 
The ADM-Sampling-System. (http://www.adm-ev.de/index.php?id=2&L=1) (6 December 2010, date last accessed)
Baird
JF
Kiyak
HA
The uninformed orthodontic patient and parent: treatment outcomes
American Journal of Orthodontics and Dentofacial Orthopedics
 , 
2003
, vol. 
124
 (pg. 
212
-
215
)
Bergström
K
Halling
A
Huggare
J
Orthodontic treatment demand—differences between urban and rural areas
Community Dental Health
 , 
1998
, vol. 
15
 (pg. 
272
-
276
)
Birkeland
K
Katle
A
Løvgreen
S
Bøe
OE
Wisth
PJ
Factors influencing the decision about orthodontic treatment. A longitudinal study among 11- and 15-year-olds and their parents
Journal of Orofacial Orthopedics
 , 
1999
, vol. 
60
 (pg. 
292
-
307
)
Bissar
AR
Oikonomou
C
Koch
MJ
Schulte
AG
Dental health, received care, and treatment needs in 11- to 13-year-old children with immigrant background in Heidelberg, Germany
International Journal of Paediatric Dentistry
 , 
2007
, vol. 
17
 (pg. 
364
-
370
)
Brook
PH
Shaw
WW
The development of an orthodontic treatment priority index
European Journal of Orthodontics
 , 
1989
, vol. 
11
 (pg. 
309
-
320
)
Brunelle
JA
Bhat
M
Lipton
JA
Prevalence and distribution of selected occlusal characteristics in the US population, 1988–1991
Journal of Dental Research
 , 
1996
, vol. 
75
 (pg. 
706
-
713
)
Bundeszahnärztekammer
Statistisches Jahrbuch 08/09
 , 
2009
Berlin
BZÄK
(pg. 
82
-
88
)
Burden
DJ
The influence of social class, gender, and peers on the uptake of orthodontic treatment
European Journal of Orthodontics
 , 
1995
, vol. 
17
 (pg. 
199
-
203
)
Burden
DJ
Mitropoulos
CM
Shaw
WC
Residual orthodontic treatment need in a sample of 15- and 16-year-olds
British Dental Journal
 , 
1994
, vol. 
176
 (pg. 
220
-
224
)
Burgersdijk
R
Truin
GJ
Frankenmolen
F
Kalsbeek
H
van ‘t Hof
M
Mulder
J
Malocclusion and orthodontic treatment need of 15-74-year-old Dutch adults
Community Dentistry and Oral Epidemiology
 , 
1991
, vol. 
19
 (pg. 
64
-
67
)
Chestnutt
IG
Burden
DJ
Steele
JG
Pitts
NB
Nuttall
NM
Morris
AJ
The orthodontic condition of children in the United Kingdom, 2003
British Dental Journal
 , 
2006
, vol. 
200
 (pg. 
609
-
612
)
Drugan
CS
Hamilton
S
Naqvi
H
Boyles
JR
Inequality in uptake of orthodontic services
British Dental Journal
 , 
2007
, vol. 
202
 pg. 
E15
 
Geißler
R
Meyer
T
Die Sozialstruktur Deutschlands. Zur gesellschaftlichen Entwicklung mit einer Zwischenbilanz zur Vereinigung
 , 
2008
5th edn
Wiesbaden
Wiesbaden Verlag für Sozialwissenschaften
pg. 
284
 
Gesellschaft für Konsumforschung
Kaufkraft
2008
 
Glasl
B
Ludwig
B
Schopf
P
Prevalence and development of KIG-relevant symptoms in primary school students from Frankfurt am Main
Journal of Orofacial Orthopedics
 , 
2006
, vol. 
67
 (pg. 
414
-
423
)
Harzer
WR
Wiesner
JS
Normale und gestörte Gebissentwicklung bei 8768 Dresdner Schulkindern zwischen 6 und 16 Jahren—Schlussfolgerungen für den optimalen Zeitpunkt kieferorthopädischer Prävention und Therapie
 , 
1998
Roderer, Regensburg
Kieferorthopädische Behandlungsnotwendigkeit. II. Expertensymposium Dresden
(pg. 
44
-
64
)
Hensel
E
Informationen zu dem Artikel von R. Saekel und G. Brodmann “Kieferorthopädie auf dem Prüfstand: Schattendasein und Überversorgung”. Die BDK 2/2001 70–78
 , 
2001
Stellungnahme der DGKFO Okt 2001
 
BDK, Hannover (http://www.kfo.uni-duesseldorf.de/DGKFO/stellung8.html) (6 December 2010, date last accessed)
Josefsson
E
Bjerklin
K
Halling
A
Self-perceived orthodontic treatment need and culturally related differences among adolescents in Sweden
European Journal of Orthodontics
 , 
2005
, vol. 
27
 (pg. 
140
-
147
)
Kenealy
P
Frude
N
Shaw
W
The effects of social class on the uptake of orthodontic treatment
British Journal of Orthodontics
 , 
1989
, vol. 
16
 (pg. 
107
-
111
)
Kerosuo
H
Abdulkarim
E
Kerosuo
E
Subjective need and orthodontic treatment experience in a Middle East country providing free orthodontic services: a questionnaire survey
Angle Orthodontist
 , 
2002
, vol. 
72
 (pg. 
565
-
570
)
Kerosuo
H
Kerosuo
E
Niemi
M
Simola
H
The need for treatment and satisfaction with dental appearance among young Finnish adults with and without a history of orthodontic treatment
Journal of Orofacial Orthopedics
 , 
2000
, vol. 
61
 (pg. 
330
-
340
)
Micheelis
WBJ
Mundgesundheitszustand und -verhalten in der Bundesrepublik Deutschland (DMS II)
 , 
1991
Köln
Deutscher Ärzte-Verlag
O’Brien
KD
McComb
JL
Fox
N
Wright
J
Factors influencing the uptake of orthodontic treatment
British Journal of Orthodontics
 , 
1996
, vol. 
23
 (pg. 
331
-
334
)
O’Mullane
DM
Robinson
ME
The distribution of dentists and the uptake of dental treatment by schoolchildren in England
Community Dentistry and Oral Epidemiology
 , 
1977
, vol. 
5
 (pg. 
156
-
159
)
Page
LAF
Thomson
WM
Malocclusion and uptake of orthodontic treatment in Taranaki 12-13-year-olds
New Zealand Dental Journal
 , 
2005
, vol. 
101
 (pg. 
98
-
105
)
Perillo
L
Masucci
C
Ferro
F
Apicella
D
Bacetti
T
Prevalence of orthodontic treatment need in southern Italian schoolchildren
European Journal of Orthodontics
 , 
2010
, vol. 
32
 (pg. 
49
-
53
)
Proffit
WR
Fields
HW
Moray
LJ
Prevalence of malocclusion and orthodontic treatment need in the United States: estimates from the NHANES III survey
International Journal of Adult Orthodontics and Orthognathic Surgery
 , 
1998
, vol. 
13
 (pg. 
97
-
106
)
Reichmuth
M
Greene
KA
Orsini
MG
Cisneros
GJ
King
GJ
Kiyak
HA
Occlusal perceptions of children seeking orthodontic treatment: impact of ethnicity and socioeconomic status
American Journal of Orthodontics and Dentofacial Orthopedics
 , 
2005
, vol. 
128
 (pg. 
575
-
582
)
Rölling
S
Orthodontic treatment and socioeconomic status in Danish children aged 11-15 years
Community Dentistry and Oral Epidemiology
 , 
1982
, vol. 
10
 (pg. 
130
-
132
)
Schmuth
GP
Milestones in the development and practical application of functional appliances
American Journal of Orthodontics
 , 
1983
, vol. 
84
 (pg. 
48
-
53
)
Schopf
P
Stellungnahme der Deutschen Gesellschaft für Kieferorthopädie zum Gutachten 2000/2001 des Sachverständigenrates für die Konzertierte Aktion im Gesundheitswesen: Bedarfsgerechtigkeit und Wirtschaftlichkeit. Band III, Über-, Unter- und Fehlversorgung 2001
 , 
2001
Stellungnahme der DGKFO Okt 2001
 
BDK, Giessen (http://www.kfo.uni-duesseldorf.de/DGKFO/stellung7.html) (6 December 2010, date last accessed)
Schopf
P
Kieferorthopädische Abrechnung mit Erläuterungen der ab 1.1.2002 gültigen kieferorthopädischen Indikationsgruppen [KIG]
 , 
2004
Berlin
Quintessenz
Shaw
WC
O’Brien
KD
Richmond
S
Quality control in orthodontics: factors influencing the receipt of orthodontic treatment
British Dental Journal
 , 
1991
, vol. 
170
 (pg. 
66
-
68
)
Shaw
WC
Richmond
S
O’Brien
KD
Brook
P
Quality control in orthodontics: indices of treatment need and treatment standards
British Dental Journal
 , 
1991
, vol. 
170
 (pg. 
107
-
112
)
Souames
M
Bassigny
F
Zenati
N
Riordan
PJ
Boy-Lefevre
ML
Orthodontic treatment need in French schoolchildren: an epidemiological study using the Index of Orthodontic Treatment Need
European Journal of Orthodontics
 , 
2006
, vol. 
28
 (pg. 
605
-
609
)
Tausche
E
Luck
O
Harzer
W
Prevalence of malocclusions in the early mixed dentition and orthodontic treatment need
European Journal of Orthodontics
 , 
2004
, vol. 
26
 (pg. 
237
-
244
)
Tickle
M
Kay
EJ
Bearn
D
Socio-economic status and orthodontic treatment need
Community Dentistry and Oral Epidemiology
 , 
1999
, vol. 
27
 (pg. 
413
-
418
)
Turbill
EA
Richmond
S
Wright
JL
Social inequality and discontinuation of orthodontic treatment: is there a link?
European Journal of Orthodontics
 , 
2003
, vol. 
25
 (pg. 
175
-
183
)
van der Linden
FPGM
Schmiedel
WJ
Bijlstra
RJ
European orthodontic specialists in 2002
Progress in Orthodontics
 , 
2004
, vol. 
5
 (pg. 
126
-
140
)
Weidner
K
Richter
J
Bittner
A
Winter
UM
Stöbel−Richter
Y
Brähler
E
A German survey of subjective gynaecological complaints
Psychotherapie, Psychosomatik Medizinische Psychologie
 , 
2009
, vol. 
59
 (pg. 
345
-
353
)
Whitesides
J
Pajewski
NM
Bradley
TG
Iacopino
AM
Okunseri
C
Socio-demographics of adult orthodontic visits in the United States
American Journal of Orthodontics and Dentofacial Orthopedics
 , 
2008
, vol. 
133
 (pg. 
489.e9
-
e14
)
Zhang
Y
Xiao
L
Li
J
Peng
Y
Zaho
Z
Young people’s esthetic perception of dental midline deviation
Angle Orthodontist
 , 
2010
, vol. 
80
 (pg. 
515
-
520
)