Participants were selected on the basis of requiring restorations of non-carious cervical lesions. Participants with fewer than 20 teeth were not considered. The participant pool was randomized as much as possible to exclude bias due to age (18 to 80 years old), sex, race, national origin, or other factors such as unusual dietary, habitual, or oral hygiene factors which might affect the results. If the participant pool included these effects, they will be acknowledged in all project reports. Despite our efforts to have close to equal numbers of men and women in the study (ADA Guidelines, 2001), as noted in this report our pool was imbalanced towards women (we enrolled 20 females and 4 males). However, we do not believe this gender imbalance will affect or bias the results.