Context: Dental students commonly face the problem of overhanging proximal margins and unsatisfactory proximal contact points (PCPs) while restoring Class II cavities in posterior teeth. Various matrix band systems are used in dental clinics to avoid such problems., Aims: The aim of this study is to compare the effects of two matrix band systems, circumferential matrix system and sectional matrix system on the PCPs and contours when restoring Class II cavities in posterior teeth., Settings and Design: This was a randomized controlled clinical trial done at College of Dentistry, Qassim University, Saudi Arabia., Subjects and Methods: Total 1200 Class II cavities in teeth were selected for this study. Treatment was done by senior undergraduate students. Cavities were randomly divided into two groups. Group 1: Total 600 cavities were restored using circumferential band system. Group 2: Total 600 cavities were restored using sectional band system. Teeth were restored either with the composite or the amalgam restoration. Contact points were evaluated. The presence or absence of proximal overhangs was assessed. Overhanging margins were categorized as positive overhangs, negative overhangs, and absent overhangs., Statistical Analysis Used: To identify the relationship between matrix band systems and other factors, Chi-square tests (χ 2 -tests) and Z-tests were used. Pearson correlation coefficient was computed and logistic regression analysis was carried out to assess variables that can affect proximal margins and contact points of final restorations., Results: All optimum contacts 389 (100%) were found in restorations done using sectional band system. A highly significant association was found between open contact points and negative overhanging margins with the use of circumferential matrix band system (P < 0.00)., Conclusion: Sectional matrix band system has been found superior to circumferential matrix band system., Competing Interests: There are no conflicts of interest