The aim of the study is to evaluate the efficacy of radicular dentin removal, risk of perforation, and shape of the canal on using manual and rotary instruments in primary teeth. Sixty primary teeth selected were divided into three groups; all the teeth were then embedded into resin and sectioned for examination before and after instrumentation. H-files were used for manual technique, and 2% taper and 4% taper I-Race files were used for rotary. Dentin removal was calculated using stereomicroscope-assisted digital image viewing software. Manual instrumentation has removed overall more dentin compared with 2% and 4% taper rotary instrumentation. No statistical differences were found between 2% and 4% instrumentation with respect to the amount of dentin removed. In few specimens, root perforations were observed in areas coinciding with largest root resorption. In primary teeth without significant root resorption, the use of nickel-titanium-rotary
files with 2% and 4% taper up to size 30 revealed to be safe and had prepared the root canals with greater conservation of tooth structure than manual instrumentation. However, 4% taper instrumentation had an additional advantage of providing more funnel-shaped canal desired for ideal compaction of obturating material.