Objective:

To evaluate the aesthetic outcome by varying the duration allowed for infiltrant penetration when treating white spot lesions with resin infiltration.

Design:

An in vitro, experimental randomised study.

Methods:

Artificially created white spot lesions (WSLs) were induced on 100 extracted anterior teeth (T1). Teeth were divided into enamel and dentine groups depending on the extent of the lesion and then randomly assigned into different treatment protocol groups: penetration times of 3, 6 and 9 min. Resin infiltration treatment was applied according to the treatment protocol assigned (T2). Samples were thermocycled for 10,000 cycles (1 clinical year) (T3). The samples from the 3-min enamel and dentine groups were then randomly assigned into either a repeat treatment or no additional treatment group (T4). Samples were then thermocycled for an additional 10,000 cycles (T5). Spectrophotometric analysis was measured colour change (ΔE) for all groups.

Results:

Mean ΔE values equal to or greater than the critical value (3.7) indicate a detectable clinical difference in colour of the treated WSL when compared to before WSL formation. Mean ΔE values, for the enamel groups, were slightly above or significantly below the critical value, and for the dentine groups, were significantly above the critical value. Mean ΔE values within the enamel and dentine groups both demonstrated a downward trend with increasing time allowed for resin infiltrant penetration (P < 0.05). No significant mean ΔE difference (P = 0.53) was found between groups that received a single or repeat treatment. After the first thermocycling event, no significant difference in colour change was observed in all groups except for the deep dentine lesion treated for 3 min. There was a significant difference in colour change for all groups except the enamel group that received a single treatment following thermocycling after a single or repeat treatment.

Conclusion:

Increasing the resin infiltrant penetration time to at least 9 min is advised as the most optimised treatment protocol. Resin infiltration treatment should be done only once to treat a particular white spot lesion as subsequent treatment for the same lesion results in marginal colour improvement. The colour improvement of WSLs resulting from the resin infiltration treatment can be expected to last for at least 1 year. Resin infiltration treatment of shallow lesions with a single and optimised infiltration technique can be expected to last an additional year.