Subphenotyping and classification of cleft lip and alveolus in adult unoperated patients: A new embryological approach

Objective: Previously, a new embryological classification was introduced subdividing oral clefts into fusion and/or differentiation defects. This subdivision was used to classify all subphenotypes of cleft lip with or without alveolus (CL±A). Subsequently, it was investigated whether further morphological grading of incomplete CLs is clinically relevant, and which alveolar part is deficient in fusion/differentiation defects. Design: Observational cohort study. Setting: Three hundred fifty adult unoperated Indonesian cleft patients presented themselves for operation. Cephalograms, dental casts, and intraoral and extraoral photographs-eligible for the present study-were used to determine morphological severity of CL±A. Patients: Patients with unilateral or bilateral clefts of the primary palate only were included. Main Outcome Measures: Clefts were classified-according to developmental mechanisms and timing in embryogenesis-as fusion and/or differentiation defects. Grades of incomplete CLs were related to the severity of alveolar clefts (CAs) and hypoplasia, and permanent dentition was used to investigate which alveolar part is deficient in fusion/differentiation defects. Results: One hundred eight adult patients were included. All subphenotypes-96 unilateral and 12 bilateral clefts-could be classified into differentiation (79%), fusion (17%), fusion-differentiation (2%), or fusion and differentiation (2%) defects. The various grades of incomplete CLs were related to associated CAs and hypoplasia, and all alveolar deformities were located in the premaxillae. Conclusions: This study showed that all CL±A including the Simonart bands can be classified, that further morphological grading of incomplete CLs is clinically relevant, and that the premaxilla forms the deficient part in alveolar deformities.