From The Columbian:
Widespread malicious software attacks locking up computer systems have forced some local dental offices to cancel or reschedule appointments over the last week.
The July 3 attacks affected customers of PM Consultants, a Portland-area IT consulting and support company, including Lower Columbia Oral Health. Arbor Dental in Longview and Vancouver and Longview Family Dental also were cyberattacked, but it was unknown if they are PM customers.
If I am reading this right it seems the dental offices were infected with ransomware through their IT support company. The article is nor very clear and the affected parties have not responded.
Ransomware continues to be a major problem for healthcare facilities. One reason, as may be the case here, is that healthcare facilities have insufficient IT support.