Malocclusions in adolescents may affect oral health related quality of life. The study aims at;

1. Evaluating two instruments measuring oral health related quality of life; "Child Perceptions Questionnaire 11-14" (CPQ 11-14) short form and "Psychosocial Impact of Dental Aesthetics Questionnaire" (PIDAQ).

2. Comparing differences in oral health related quality of life in;

   1. adolescents with different types of malocclusion and without malocclusions
   2. individuals of different genders and socioeconomic status

3. Longitudinally evaluating differences in oral health related quality of life;

   1. before, during and after orthodontic treatment
   2. in untreated individuals (without malocclusion) over time

The individuals that are to be recruited to the study are;

Malocclusion group; 500 12-19 year olds with malocclusion, examined at their specialist orthodontic clinic.

No malocclusion group; 175 12-19 year olds without malocclusion, examined at their general dentistry clinic.

All patients will also answers two questionnaires (in Swedish) measuring oral health related quality of life; CPQ 11-14 short form (Jokovic 2006, Dimberg 2019) and PIDAQ (Klages 2006, Göranson 2020). Randomization will ensure that half of the study participants will begin with CPQ 11-14 short form and then PIDAQ, while half of the participants will answer the questionnaires in the reverse order. The questionnaires will be answered in a calm environment in the dental clinic.

All patients will have five standardized intraoral photographs taken. These photographs are already routinely taken at the specialist orthodontic clinics, but is taken in addition to routine procedure at the general dentistry clinic. To determine presence of malocclusion and orthodontic treatment need, two orthodontic indices will be used; ICON (Daniels 2000) and IOTN (Brook 1989). Assessments will be based on intraoral photographs, clinical measurements and pre-existing dental x-rays.

Also, patients will be grouped based on their type of malocclusion using the following diagnoses;

• Enlarged overjet (≥ 6 mm) with or without incomplete lip closure
• Anterior cross bite (One or more incisors)
• Deep bite (≥ 2/3 lower incisor coverage)
• Frontal open bite (≤0 mm)
• Lateral cross bite (two or more teeth, with our without lateral guidance)
• Upper or lower arch anterior spacing (largest gap between two neighbouring teeth between canine and canine ≥ 2 mm)
• Upper or lower arch anterior crowding (≥ 3 mm lack of space canine to canine)

As the study is of longitudinal design, the questionnaires will be answered and the photographs will be taken on several occasions. For the malocclusion group, the time points will be as following;

• T0- at the initial examination at the specialist orthodontic clinic, before orthodontic treatment is begun
• T2- One year into the orthodontic treatment
• T3- Two months after the orthodontic treatment has been completed
• T4- One year after the orthodontic treatment has been completed.

The no malocclusion group will be examined the same number of times and at the same time intervals as the malocclusion group.

Information about DMFT/S (decayed, missing, filled, teeth/surfaces will be gathered from the dental records. Orthodontic extractions will be noted. To be able to determine socioeconomic differences, information about socioeconomic status of the individual study participants will be gathered from the Statistics Sweden.

Inclusion Criteria:

• Adolescents 12-19 years of age with malocclusion (IOTN grade 4 and 5) referred to specialist orthodontic clinics
• Adolescents 12-19 years of age without malocclusion (IOTN grad 1, 2 or 3) at general dentistry clinics

Exclusion Criteria:

• Previous orthodontic treatment
• Cleft lip and palate
• ASA ≥ III
• Intellectual and/or physical inability to answer questionnaires

Malocclusion group 500 12-19 year olds with malocclusion, defined as IOTN-DHC grade 3, 4 or 5. The adolescents are consecutively recruited new patients at three orthodontic centers; Center for Orthodontics and Pediatric Dentistry, Norrköping, Public Dental Service Östergötland; Department of Orthodontics, Folktandvården Stockholms län AB, Folktandvården Eastmaninstitutet, Stockholm, Sweden and Department of Orthodontics, Malmö University, Malmö, Sweden. Patients are examined at the initial examination at the orthodontic department, before any orthodontic treatment is begun.

No malocclusion group 175 12-19 year olds without malocclusion, defined as IOTN-DHC grade 1 or 2. Patients are consectively recruited adolescents examined at their general dentistry clinic.