Is it ok to get 9 years old sons teeth cleaned professionally or is it too early?

You're already late. He should have been seen professionally many years ago. Children are not immune to dental caries or malocclusions. Although the primary teeth are eventually lost, they help guide the secondary teeth into position. Please make an appointment.

You're very late. Standard of Care is that all children have 1st Dental Examination no later than 1st b'day, 1st Orthodontic Examination no later than 7th b'day. Early discovery of dental disease and/or donate-facial anomalies allows for better treatment, Have byoiur child seen immediately by both General Dentist or Pedodontist and by Orthodontist.