The wide variation in infant maxillary morphology and cleft size of children with unilateral cleft lip and palate (UCLP) and isolated cleft palate (CP) raise concerns about their possible influences on treatment outcome. The studies in this thesis aimed to investigate the relation between cleft size in infancy and crossbite at 5 years of age (Paper I); the impact of primary surgery on cleft size and maxillary arch dimensions from infancy to 5 years of age (Paper II); associations between cleft size, maxillary arch dimensions and facial growth in both UCLP and CP children (Paper III); and, to evaluate the relation between infant cleft size and nasal airway size and function in adults treated for UCLP (Paper IV). In homogenously treated groups of children with UCLP and CP, dental casts were used to measure cleft size and maxillary arch dimensions from infancy up to 5 years of age, and for crossbite recording at 5 years. Serial lateral cephalometric radiographs taken between 5 and 19 years of age in the same groups were used to study facial growth. Nasal airway size and function were evaluated by acoustic rhinometry, rhinomanometry, peak nasal inspiratory flow and odour test in a group of adults treated for UCLP. The main findings were: crossbite was a frequent malocclusion at 5 years of age in children with UCLP and large cleft widths at the level of the cuspid points in infancy were associated with less anterior and posterior crossbite in this group (Paper I). Cleft widths decreased after lip closure and/or soft palate closure in both UCLP and CP children. Initially, UCLP children had wider maxillary arch dimensions, but after hard palate closure, the transverse growth was reduced, and at 5 years, they had smaller maxillary arch widths than CP children had (Paper II). Maxillary arch depths and cleft widths in infancy were correlated with maxillary protrusion and sagittal jaw relationships in both UCLP and CP children (Paper III), but cleft width in infancy was not correlated with nasal airway size and function in adults treated for UCLP (Paper IV).

Background. The treatment of patients born with cleft lip and palate has been gradually modified over the years as the surgical procedures have developed and improved. Multidisciplinary team care has evolved and provided improved care with enhanced results. Clefts in the alveolus can be reconstructed by alveolar bone grafting or by periosteoplasty. The main goal is to repair and close the alveolar cleft and create a continuous alveolar processes so that the teeth can erupt. Aims. This thesis has several aims: to investigate the impact of dental status and initial cleft width on the outcome of Secondary alveolar bone grafting (SABG) in patients born with unilateral cleft lip and palate (UCLP) at the 10-year follow-up (Studies I and II); to compare the outcomes of primary periosteoplasty (PPP) with those of SABG in patients born with unilateral cleft lip and alveolus (CLA) (Study III); to evaluate clinical and radiographic conditions and identify factors important for the final treatment outcomes after SABG ( Study IV); to evaluate two radiographic methods, i.e. occlusal radiographs and cone beam tomography (CBCT)) for assessing alveolar bone height ( study IV). Results. In UCLP patients, SABG achieved excellent results in terms of bone height; tended to reduce with time, correlated with dental status and dental restoration factors. Occlusal radiographs correspond well with the CBCT, for evaluating alveolar bone height in cleft area. The width of the initial cleft does not seem to affect the success of SABG. Finally, patients with CLA treated with PPP at the time of lip repair have inferior bone formation outcomes in the cleft area compared with patients treated with SABG at the time of mixed dentition. Conclusion.  Poor dental status and malpositioning negatively affect the long-term survival of bone in the alveolar cleft. The initial cleft width affects certain dental status factors. In adults with UCLP, the alveolar bone height in the cleft was correlated to the presence of gingival inflammation and restorations at 20 years follow-up. Specially designed maintenance therapy is beneficial, after complex dental restorations in the cleft area. SABG is preferred to PPP for the reconstruction of alveolar clefts.