A new laboratory procedure has been developed to evaluate subgingival access efficacy (SAE) of toothbrush bristles using clinical toothbrushing motions and pressure-sensitive paper placed around simulated tooth shapes and gingival tissues under wet brushing conditions. Subgingival access is determined by measuring the maximum distance of the bristle marks from the brushing stroke on the pressure-sensitive paper under the simulated gingival tissues. Four manual toothbrushes (Reach Tooth & Gum Care, Colgate Total Design, Mentadent and Oral-B Advantage) with differing designs, bristle feathering or outside row dimensions were evaluated. Each toothbrush design was evaluated for 28 assessments on anterior and posterior tooth shapes. On overall assessments for subgingival access, the Reach Tooth & Gum Care toothbrush was significantly (p < 0.05-0.001) superior to the other three commercially available toothbrushes tested.