Objectives: The purpose of this study was to assess the impact of photopolymer resin type, arch locat ion, and postprocessing techniques on the trueness and precision of three-dimensionally printed (3DP) f ull-arch surgical implant guides. Methods: St ereolithography reference images (STL) of an upper and lower surgical guide with six drill holes were used for printing the samples using a digital light processing 3D printer (MAX UV, Asiga Max). Samples assessed were printed using two different resins, DentaGuide (n=35) and DentaClear (n=20). These were subdivided and measured based on the post processing technique used: handwashing (n=20), sonication (n=25), or a mix of handwashing and sonication (n=l0), postcuring using 385nm UVA light with nitrogen (n=50) or without nitrogen (n=5). The diameter of each drill hole per guide was measured using a coordinate measuring machine (Absolute Arm 7- Axis, Hexagon) and compared versus the STL to calculate each sample's trueness (median error) and precision (interquartile range). Mann-Whitney and Kruska l-Wallis tests were used for st atistical analyses. Results: All samples demonstrated a dimensional error of <70μm. No significant differences (p>0.05) were observed between upper and lower arches and between postprocessing techniques using nit rogen, irrespective of the use of hand or ultrasonic washing. In contrast, DentaClear resin was significantly (p<0.001) more accurate with a trueness of 26 μm and precision of 12 to 34 μm versus the DentaGuide at -31 μm and -54 to -17 μm, respectively. Samples post-cu red without nitrogen were significantly (p<0.05) the least accurate of all surgical guides, with a trueness of - 42 μm and precision of -68 to -39 μm. Conclusion: Resin type and nitrogen postprocessing are parameters that can sign ificantly impact the accuracy of surgical guides. The tolerance of 3DP surgical guides needs to account for the dimensional changes occurring during the manufacturing process to minimise implant positioning errors.