David L. Harnett D.D.S.

Ashley A. Harnett-Smegal D.D.S.


All our professionals at Cortland Dental Technology Center maintain the highest levels of accreditation and pursue ongoing education to stay abreast of the latest trends in dentistry.


Dr. David L. Harnett

Dr. Harnett graduated from The Ohio State University College of Dentistry in 1974 and returned to Trumbull County to set up his dental practice. Born and raised in this area he resides in Kinsman with his wife, Shayne, and their dog, Fifi. He has four grown children whom are all married and have thirteen grandchildren. Dr. Harnett is trained to administer Botox and dermal fillers and is utilizing the use of our latest technology the CO2 laser.  His most recent educational training has been in sleep disorder and customizing oral sleep appliances which improves overall health. Dr. Harnett is passionate about advancing  in Dental education.

Dr. Ashley Harnett-Smegal


Dr. Smegal had the privilege to join the practice in July of 2009 and is the daughter of Dr. Harnett. She graduated from The Ohio State University with a Bachelors degree in Business and in 2009 earned her professional degree of doctor of dental surgery.  Her most recent educational training has been in placing implants and sleep apnea.   Dr. Smegal spent her childhood and most of her adult life in Trumbull County where she plans to stay with her husband Matt and raise their now growing family of three daughters, Evy Jean, Ruby Rose and Shea Ireland and their boxer, Mr. Moose.



Paul Hetherington


You will see Paul at the front desk when you leave the office. Paul has worked at the office since 1985 and will engage in sports talk if you'd like! He has lived in the area since 1984. He and his wife Kelly, who also works at the front desk, live in Howland with their two children, Alisha and Brandon.


Tammy Siekkinen

Tammy has been a member of the staff since 1990. She is the office manager and also oversees the office. She mainly works with the front staff but from time to time you will see her assisting in the back as needed. Tammy and her husband Bill and their two children, Judah and Lydia live locally.


Kelly Hetherington


Kelly works at the front desk, you will see her as you sign in.  She has worked for Dr. Harnett since 1997. She is happy to be able to work side by side with her husband Paul. She lives in Howland with her husband and two children, Alisha and Brandon.


Chelsea Kinter

Chelsea is located at the front desk where she assists in patient relations regading insurance and scheduling. Chelsea has her Associates Degree in Business Management. She lives in Ravenna with her husband Ryan and their dog Chewy. 






Kari Clark


Kari is an Expanded Function Dental Auxiliary and a Certified Dental Assistant with a Radiology License. She is trained to perform restorative work including fillings, bonding, repairing broken teeth and all cosmetic dentistry. She received her EFDA education at Case Western Reserve University. She has been on staff here since 1990.  Kari now resides in Cortland with her husband Bryan. They have three grown children Sheena, Ashley and Brandon.  Her newest family addition is her grandson Jaxxon. 

Amy Ray


Amy has been a Certified Dental Assistant with Dr. Harnett since 1996. One of her specialties is in facilitating the doctors with invisalign patients. She is a life time resident of Trumbull County. Currently, Amy lives in Howland with her husband Ted and their son Donavan, daughter Hilary and  Bandit.


Char Miller


Char has been at Dr. Harnett's office since June 2005 and been in the dental field since 1990. She received her education at Warren School of Dental Technology. Char is our lab guru and is the expert in assisting Dr. Harnett with implant placement. Char was born and raised in the local area where she plans to stay.


Heather Garner


Heather joined the practice in July 2009. Heather received her license as a certified dental assistant and radiology license in 2002. She also received her Extended Functions Dental Auxillary license from Case Western Reserve University in 2004. Heather lives in the area with her husband Cameron (who also works for Dr. Harnett) and their children.


Jessica Starcher


Jessica started working at Dr. Harnett's office in May of 2009. Jessica received her training at Northeast Ohio Dental Assisting School. She lives in the area with her children Brett and Bailey and her boxer Fiona.



Cameron Garner

Cameron has been an employee since 2011.  Cameron is a Dental Assistant to all the doctors.  He has lived in the area all his life.  Cameron lives in the area with his wife Heather (who works for Dr. Harnett) and their children.




LAURA Grzelak

Laura has been an employee since June 2015.  Laura is a graduate of Choffin Career and Technical Center receiving her certificate as a Certified Dental Assistant.  She lives in the area with her husband Joe, son Liam and daughter Allie.





Susan Butler


Sue is a licensed Dental Hygienist. She attended Youngstown State University to achieve an associate's degree in dental hygiene in 1980. In 1983 she began working for Dr. Harnett. Born and raised in the Cortland area, Sue still resides here. She has two grown daughters.


Erna Weber


Erna is a Registered Dental Hygienist. She attended Youngstown State University to achieve an associates degree in dental hygiene. Erna has worked for nearly twenty years at Dr. Harnett's. She and husband Ken have been married since 1978 and have lived in this area ever since. Erna and Ken have enjoyed raising two children, Kenny and Heidi.


Illa Vitto


Illa has been a friendly, familiar face here in Dr. Harnett's office working as a Dental Hygienist since 1997. She graduated from Choffin Career Center as a certified dental assistant in 1989 and later returned to school to graduate with an Associates Degree in Dental Hygiene in 1996 from Youngstown State University. She and husband Frank settled in Hubbard with their children Danielle and Elisha.

Patti Miller


Patti has been a dental hygienist with Dr. Harnett since the first day he opened his practice and currently works part-time. Patti received her Dental Hygiene Degree from The Ohio State University. She and husband, Rob, settled in the Gustavus area to raise their three children Abbey, Sarah and Ben whom are all grown and married with children living in the area.

Rachel Elliott


Rachel earned her Registered Dental Hygiene Degree from Youngstown State University in 2005. She also earned her Bachelor Degree in Allied Health in 2006. She started working at Dr. Harnett's in June 2005.  She will also be seen greeting patients at the front desk. She resides in the area with her husband, Shannon, and their 3 children.