Abstract
This thesis describes an investigation into the effects of infant orthopaedics (IO) on speech and language development in children with unilateral cleft lip and palate (UCLP). The study was performed within the framework of the three-centre prospective randomised clinical trial 'Dutchcleft'. Two groups of children with UCLP were followed in this trial: one group received infant orthopaedics (IO group) in the first year of life, while the other group did not (non-IO group). Speech and language development was assessed from age 1 to age 3 and subsequently in a follow-up study at age 6. The study comprised an investigation of sounds produced in babbling (at age 1 and 1.5), an assessment of phonological development (at age 2, 2.5, and 3), a perceptual evaluation of speech quality characteristics (at age 2.5), and an investigation of the language skills (at age 2, 2.5, 3, and 6). The results of the analyses showed that the children treated with infant orthopaedics presented enhanced production of alveolar contoids in babbling at age 1. Furhtermore, their phonological development from age 2 to 3 was closer to normal when compared to the non-IO group. A perceptual evaluation of the speech at the age of 2.5 years showed that the IO group received higher ratings for speech intelligibility. At age 2.5 and 3, children in the IO group also produced more complex sentences with a larger mean length of utterance. At 6 years of age, there were no differences in language development between the groups. Concluding can be stated that treatment with infant orthopaedics had positive effects on the development of speech and language until age 3
