We understand. Many adults are scared of the dentist too! Starting early can help with this fear. They’ll get to know an office and staff at an early age and will view this as a normal experience.
Be careful not to provide too many details. You definitely want to answer their questions, but providing too much information about the upcoming treatment could result in some anxiety.
And finally, be careful about the words you use! “Scary”, “painful”, “anxious” are not ones to say in front of your kids!. That too will increase their anxiety level.