Objective: To evaluate whether delaying treatment with a twin block appliance affects treatment outcomes, in terms of skeletal and dental change and psychological disadvantage.
Design: Multicentre, two-arm parallel randomised controlled trial.
Setting: Three UK hospital orthodontic units.
Methods: A total of 75 participants were randomly allocated into an Immediate Treatment Group (ITG) (n= 41) and an 18-month delayed Later Treatment Group (LTG) (n=34).
Outcomes: Dentofacial changes were recorded from lateral cephalograms and study models, psychological impact was measured using a child perception questionnaire (CPQ11-14) and an Oral Aesthetic Subjective Impact Score (OASIS) at registration (DC1), 18 months (DC2) and 3 years (DC3).
Results: The ITG initial effect was a mean ANB reduction was 1.6° (P<0.001) (95% confidence interval [CI] = 0.89-2.29), and an overjet reduction of 5.06 mm (P<0.001) (95% CI = 3.96-6.16) (boys: aged 12 years 8 months; girls: aged 11 years 8 months). There were no statistically significant differences between the ITG and LTG for twin block treatment outcomes, but the ITG active treatment time was longer (P=0.004) (ITG: 13.1 months; LTG: 9.8 months). There was insufficient evidence to state that patients were psychologically disadvantaged by waiting 18 months for active twin block treatment (P>0.05).
Conclusion: Participants achieved similar clinical and psychological outcomes irrespective of whether they started their twin block at the age of referral (ITG) or 18 months later (LTG). This suggests that boys aged 12 years 8 months and girls aged 11 years 8 months, on average, are not disadvantaged by waiting 18 months for active twin block treatment.
Keywords: Class II skeletal pattern; clinical outcome; orthodontic waiting lists; psychological outcome; randomised controlled trial; twin block appliance.