Dental S-corporation: Exempt or non-exempt in W-9?

Folks,



I am confused about this topic. The W-9 form says S-corps that provide medical or healthcare services are non-exempt from backup withholding. Do dental services provided by dentist fall under the medical category?



Can I use or not use the exempt code '5' for my S-corp while filling the W-9 form? If I don't use this, will insurance payments for the S-corp services have taxes withheld before being paid to the corporation?



Thanks for clarification.