RE: response to: Efficacy of three hygienic protocols in reducing biofilm adherence to removable thermoplastic appliance. The Angle Orthodontist 2014(1) 161–170

To: Editor, The Angle Orthodontist

Thank you for your enlightening remarks and questions regarding our article.

Regarding patient hygiene effect on the experiment protocol:

The study was undertaken for 24 weeks during which time 3 aligner hygiene protocols were examined. If indeed oral hygiene had deteriorated over this time span, aligners from week 0–4 would have accumulated less biofilm than those from week 14–24. Consequently, the VBC (examined from week 14 to 24) should have shown less cleaning efficacy than the regular aligner maintenance (examined during weeks 0–4). However, the opposite was found. This suggests that oral hygiene did not change during the 24 weeks of the study. This might be explained by the age(s) of the patients (29.1 ± 4.7 years), and that the orthodontic appliances were removable, which makes oral hygiene less problematic compared to fixed appliances. Furthermore, biofilm accumulation over time demonstrated that both (CHX, VBC) hygienic protocol provided a fairly constant level of biofilm prevention (Figure 7). Thus, gradual deterioration in aligner maintenance over time was not found.

Regarding male-female differences:

This study was designed to examine biofilm accumulation as measured directly from the removable orthodontic appliances. Sex difference was not deemed to be a confounding factor. Therefore, it was not included as a variable.

Regarding the use of the vibrating bath with water instead of VBC (Invisalign cleaning system-vibrating bath solution):

In the discussion section it was mentioned that ultrasonic vibratory cleaning was found to reduce biofilm accumulation, most likely by a disintegration process. Thus, it might be that doing so while immersing the appliance in water only could produce an acceptable clinical effect. However, the Cleaning Crystals used in the vibrating bath are comprised of Sodium Sulfate (60%), Sodium Carbonate (30%), Sodium Tripolyphosphate (7.5%), Sodium Dichloroisocyanurate (2%) and Sodium lauryl sulfate (0.15%), which act as pH neutralizer (eg, Sodium Sulfate), disinfectant (eg, Sodium Dichloroisocyanurate) and detergent (eg, Sodium lauryl sulfate). These provide added benefits over water alone.

Best wishes,