Background Equity in health is an important consideration for policy makers particularly in low and middle income developing country. The area of oral and dental health is not an exception. This study is conducted to explore the main determinants that make inequality in oral and dental health area in developing countries. Methods This was a scoping review applying the framework enhanced by Levac et al. Four databases of Scopus, PubMed, WOS and ProQuest were systematically searched applying to related keywords up to 27.11.2020. There restriction was placed in the English language but not on the study design. All the related studies conducted in the low or middle income developing countries were included. A qualitative thematic analysis was applied for data analysis and a thematic map was presented. Results Among 436 articles after excluding duplications, 73 articles were included that the number of publications from Brazil was greater than other developing countries (33.33%). Thematic analysis of the evidence has led to 11 determinants that may result in inequality in oral and dental health services in developing countries including personal characteristics, health status, health needs and health behaviours, social, economic, cultural and environmental factors, as well as insurance, policies and practices and provided related factors. Conclusion The policymakers in the low and middle income developing countries should be both aware of the role of inequality determinants and also try to shift the resources to the policies and practises that can improve the condition of population access to oral and dental services the same as comprehensive insurance packages, national surveillance system and fair distribution of dentistry facilities. It is also important to improve the population’s health literacy and health behaviour through social media and other suitable mechanisms according to the countries’ local contexts.