Introduction: Coffin-Siris Syndrome (CSS) is a rare genetic disorder of unknown etiology. It combines digital-ungual abnormalities, facial dysmorphism, developmental and intellectual delay, and other organ-system abnormalities. Oral and dental anomalies are rarer.
Case report: 8-year-old boy with clinical diagnosis of CSS presented facial dysmorphism, sparse hair, a flat and wide nose, absence of nails on 3rd and 5th fingers of the right hand and 3rd and 4th fingers of the left hand, malformation of the feet, toes with nail hypoplasia. Oral and dental anomalies included : bilateral complete cleft lip and palate, delayed eruption of permanent teeth, presence of supernumerary tooth and taurodontism in the first permanent molars.
Conclusion: Early diagnosis of oral problems and regular follow-up in dentist are necessary to promote good oral health and improve the patient's quality of life.