Abstract: This literature review outlines the current issues and debates relating to the dental health of adults with drug dependence. The dental health of adults with illegal drug dependence (IDD) continues to be under debate throughout dental practice, and the most appropriate model of care suitable to meet the high complex needs of this client group remains uncertain. The study aims to review and critically analyze available research relating to the oral health effects of illegal drug misuse and the dental health needs and status of adults with drug dependence. Second, it aims to identify and critically evaluate current models of dental service/care delivery, including relevant best practice guidance and potential barriers to dental access for adults with IDD. The available literature pertaining to dental health and adults with drug dependence are systematically reviewed and critically analyzed and evaluated in order to execute a rigorous investigation. The oral effects along with general medical complications associated with IDD are increasingly being recognized. There are substantive negative effects of IDD on oral health, particularly for those with opioid dependence; therefore, these clients have high complex dental needs and low use of dental services. Adults with drug dependence comprise a group with special dental needs and therefore need greater access to dental care than most people due to their high level of need. A high awareness of the implications for oral health care for adults with drug dependence is essential. Dental professionals have a key role in supporting the rehabilitation of these patients from potentially severe or fatal addictions. There is a distinct lack of national policy and guidance relating specifically to adults with drug dependence, and therefore, problems persist. Key findings and recommendations are presented to enhance the development of dental services for adults with IDD.