Meet The Doctors

Dr. Michael Greding, DDS, is originally from Thousand Oaks, California. He graduated with a bachelor’s degree in biology from BYU in 1997 and graduated from UOP Dental School in 2001 with honors. In 2001, he moved to Arizona. Dr. Greding has been married 23 years to wife, Carlie. They have 5 children, a daughter in law, a son in law and four grandchildren. Two girls and twin boys! In his spare time, he enjoys the gym, exercise, playing competitive baseball, water skiing, snowboarding, and surfing. Dr. Greding loves to travel with his family.

He has been a pioneer in CEREC dentistry and has been using the CEREC technology (same day crowns) since 2002; being one of the most experienced dentists in all of Arizona. In April of 2018, he joined the OnCall Dental family. Now, he has purchased the Tempe location and is incorporating all aspects of family, restorative, and cosmetic dentistry to the practice—while still not forgetting emergency patients and relieving same-day pain.

Dr. Ryan Cullinan, DDS, is a seasoned professional with over 20 years of experience in general dentistry, specializing in dental implants and full-mouth reconstructions. He advocates a patient-centered approach, emphasizing education and open communication. Dr. Cullinan holds a Doctor of Dental Surgery and an undergraduate degree in Pharmacy from the University of Iowa. His skills encompass general dentistry, dental implants, full-mouth reconstructions, patient education, and advanced dental technologies. He believes in a collaborative patient-provider effort and focuses on personalized, compassionate care.

On a personal note, Dr. Cullinan is family-oriented and married, with three daughters and two dogs. He is an outdoor enthusiast who enjoys hiking and skydiving and is committed to community service and continuous learning. He aims to provide exceptional dental care that meets each patient's unique needs.

Dr. Heyrend is an Idaho native that grew up in the Midwest. He moved to Arizona in 2020 and has been practicing in the valley since. Before becoming a dentist, Dr. Heyrend served as a volunteer missionary in Italy, where he became fluent in the language and fell in love with the Italian culture and cuisine. In 2012, he graduated from Brigham Young University-Idaho, where he earned his Bachelor’s of Science degree in Exercise Science and a Minor in Chemistry. In 2017, he graduated from Western University of Health Sciences, College of Dental Medicine, with his Doctor of Dental Medicine degree.

Following dental school, in 2018, he completed an Advanced Education in General Dentistry (AEGD) post-graduate residency with NYU Lutheran and Roseman University of Health Sciences in Utah.

With a particular focus on dental emergencies, dental implants, surgical extractions and wisdom teeth removals, cosmetic dentistry, and root canal treatments, he ensures that his patients receive comprehensive care tailored to their unique needs. Dr. Heyrend invests his time in continuing education with the latest CEREC CAD/CAM technology, cutting-edge materials, techniques, and any advancements in the field to offer his patients exceptional care.

His goal is to help patients overcome their fear of going to the dentist. In his free time, Dr. Heyrend enjoys traveling, the outdoors, anything Italian, and spending time with his wife and 5 children,