Ellison graduated with a Diploma in Dental Therapy from the Fiji School of Medicine in 1989. Then in 1999 graduated from the Fiji School of Medicine with a Bachelor of Dental Surgery. In 2007, he graduated from the University of Sydney with a Master of Dental Science in Community Oral Health and Epidemiology. His previous positions have included being Head of Population Oral Health, Ministry of Health (2007 -2008), Chief Dental Officer in the Malaita Province(2002-2004), Resident and then Principal Dental Officer at the National Referral Hospital (1999-2001).  Prior to becoming a Dentist, he was a Dental Therapist for 6 years (1990 -1995). Ellison is currently the Director of Dental Services for the Ministry of Health and Medical Services and the Secretary of the Solomon Islands Medical and Dental Board since 2009, which is the Professional Body that regulates the practice of Medicine and Dentistry in the Solomon Islands.  In Addition he is a member of the Solomon Islands National Drugs and Therapeutic Committee and also a Part-Time Lecturer at the Solomon Islands College of Higher Education, School of Nursing and Health Sciences. He gives lectures to the 3rd year Dental Nurse students on basic dentistry particularly in diagnosing oral conditions and making timely referrals to dentists as well as dental health education and oral health promotion.