Secondary endpoint
The need for orthodontic care provisions can be derived from the orthodontic indication group severity classifications. The following definitions were applied [
14], resulting in the following percentages:
KIG grade 1: 2.5% of study participants were classified as KIG grade 1.
This also included the 0.7% of study participants who has no tooth misalignment and no orthodontic findings (eugnathic dentition). In these cases, there is absolutely no orthodontic treatment indicated. Classification as grade 1 can be justified solely by the fact that the physiological step in indication group D (sagittal overjet up to 3 mm) is defined as KIG grade 1.
A total of 1.8% of study participants displayed slight tooth misalignment and treatment may be desirable from an esthetic perspective, but not in the sense of a medical indication.
KIG grade 2: 57.0% of study participants had mild tooth misalignment that requires correction for medical reasons, but the cost of which will not be covered by the health insurance provider.
KIG grade 3: 10.0% of study participants had pronounced tooth misalignment that requires correction for medical reasons.
KIG grade 4: 25.5% of study participants had very pronounced tooth misalignment that requires treatment for medical reasons as soon as possible.
KIG grade 5: 5.0 of study participants had extremely pronounced tooth misalignment; it is imperative that they receive treatment for medical reasons.
The percentage of study participants requiring orthodontic treatment in accordance with the guidelines from the statutory health insurance providers is 40.4%. The percentage of study participants for whom, in principle, orthodontic treatment is indicated for medical reasons is 97.5%. Systemic differences in the need for care provision relating to gender, region, or social status were not observed. However, associations with the self-assessment of their own health status, habits, dyskinesias, and dysfunction arose. It was discovered that subjects requiring orthodontic treatment systematically rated their overall health and oral health status worse. Subjects requiring orthodontic treatment were more likely to systematically display mouth breathing (instead of nasal breathing), twice as likely to display incompetent lip sealing, and more likely to display other habits (mentalis habit, biting on their tongue, lip sucking, and fingernail biting), as well as sleep disorders and snoring.
Craniofacial abnormalities were rare. In this study, only 0.4% of study participants were diagnosed with this type of disease. All diagnosed cases were male.
Hypodontia, as described in the system to classify the need for orthodontic treatment, can only be definitively identified with the aid of X‑ray diagnostics. Therefore, orthodontic indication group U cannot be evaluated as part of DMS 6 because no X‑ray images are available. However, space maintainers (fixed) or replacement teeth (removable, e.g., child dentures) were clinically recorded. 0.4% of study participants had been fitted with a space maintainer following the loss of a tooth, and a further 0.2% had replacement teeth in the form of child dentures. For the reasons mentioned above, it is not possible to draw conclusions about the prevalence of indication group U based on this information.
Tooth retention and tooth displacement, as described in the KIG system to classify the need for orthodontic treatment, can only be definitively identified with the aid of X‑ray diagnostics. Therefore, orthodontic indication group S cannot be evaluated as part of DMS 6 because no X‑ray images are available. For this reason, a survey of these findings did not take place. An exception is ankylosis/partial retention of the 6‑year molars in the surveyed age group, which can be assessed without the aid of a radiological diagnostic scan. Despite the limitations, this parameter was recorded. None of the subjects displayed partial retention of the 6‑year molars, and 0.5% of study participants displayed partial retention affecting other permanent teeth (lateral incisors and second premolars). For the reasons mentioned above, it is not possible to draw conclusions about the prevalence of indication group S based on this information.
A distal bite position malocclusion of the incisors was frequent and affected 88.9% of study participants. Only 0.8% of study participants displayed no related findings. No tooth misalignment (sagittal overjet up to 3 mm, grade 1) was observed in 11.1% of subjects, and low-grade tooth misalignment (grade 2) was seen in the vast majority of study participants (69.2%). Systematic gender-related or regional differences were not observed. It is noticeable that distal bite cases requiring treatment were found more frequently in those with a higher social status.
In comparison with the distal findings, a mesial bite position malocclusion of the incisors was rather rare and affected only 4.0% of study participants; 96.0% of study participants displayed no related findings. All registered cases displayed pronounced (grade 4) or extremely pronounced (grade 5) tooth misalignment. Overbite was more prevalent among boys than girls. There were also differences in regional distribution. Overbite was more frequent in participants with a lower social status.
Discernible vertical open bite malocclusions were observed in 7.1% of study participants, while 92.9% of study participants displayed no related findings or low-grade findings. Less pronounced tooth misalignment (grade 2) was observed in 4.6% of participants, pronounced tooth misalignment (grade 3) in 1.6%, and extremely pronounced tooth misalignment (grade 5) in 1.0% of study participants. No systematic differences relating to gender, region, or social status were observed.
Vertical deep bite malocclusions were observed in 94.3% of the study participants. Only 5.7% of study participants displayed no related findings. Slight tooth misalignment (grade 1) was observed in one-third of participants and somewhat pronounced tooth misalignment (grade 2) in 51.2%. 9.8% of study participants displayed pronounced tooth misalignment with traumatic gingival contact (grade 3). No systematic differences relating to gender, region, or social status were observed.
Transversal malocclusions in the form of buccal or lingual occlusions were rare; they were observed in only 0.3% of study participants. All those affected displayed very pronounced tooth misalignment (grade 4). 99.7% of study participants displayed no related findings. No systematic differences relating to gender, region, or social status were observed.
Transversal malocclusions in the form of unilateral or bilateral crossbite were observed in 8.4% of study participants; 91.6% of study participants displayed no related findings. Somewhat pronounced tooth misalignment (grade 2) was observed in 2.7% of study participants in the form of end-to-end bite. Pronounced crossbite (grade 3) was observed in 0.4% of study participants and very pronounced crossbite (grade 4) in 5.3%. End-to-end bite and crossbite were more prevalent in girls. There were also differences in regional distribution. End-to-end bite and crossbite were more common in those of lower social status.
Discernible vertical open bite malocclusions were observed in 60.9% of study participants; 39.1% of study participants displayed no related findings or very low-grade findings. Somewhat pronounced tooth misalignment (grade 2) was displayed in 51.7% of study participants, pronounced tooth misalignment (grade 3) in 8.4%, and extremely pronounced tooth misalignment (grade 4) in 0.7%. No systematic differences relating to gender, region, or social status were observed.
Lack of space was observed in 30.3% of study participants; 69.7% of study participants displayed no related findings. Somewhat pronounced tooth misalignment (grade 2) was observed in 23.5% of study participants, 3.1% of study participants displayed pronounced (grade 3) findings, and 3.6% of study participants displayed extremely pronounced (grade 4) tooth misalignment. Lack of space was observed more frequently in boys than girls. There were also differences in regional distribution. No other differences related to social status were observed.