Purpose: To create and validate size guides for fitting Denovo® plain molar bands and bands with tubes to 3M™ ESPE™ stainless steel crowned primary molars. Methods: Two size guides were created for fitting these bands to corresponding crown sizes, with an additional pre-existing guide available for comparison. Eight volunteer dentists chose their best-fit band sizes for stainless steel crowned typodont teeth, with each seeing a subset of clinical conditions as determined by a randomized factorial experiment. Comparisons of dentists' best fits and each guide individually were evaluated for over 96 fits for robustness of clinical condition in an analysis of variance and agreement using intraclass correlation. Savings in attempted fits using size guides were estimated. Results: No significant differences over clinical conditions were observed when evalua- ting size guides and dentists' best fits. Intraclass correlations between plain band, plain band with tubes, and the pre-existing plain band with tubes guides and observed fits were 0.997, 0.998 and 0.998, respectively, with corresponding expected savings of 1.1, 0.7 and 0.5 attempts per fit, respectively. Conclusion: Size guides created for fitting plain bands and bands with tubes to stainless steel crowned primary molars were validated by volunteer dentists and showed promise for decreasing waste and increasing efficiency during dental visits.).