Efficacy of three hygienic protocols in reducing biofilm adherence to removable thermoplastic appliance

Abstract

Objectives: To examine the ability of a removable thermoplastic appliance (RTA) to adsorb hygienic solutions and inhibit bacterial growth and to examine the efficacy of three hygiene protocols in reducing bacterial biofilm adherence to RTA.

Materials and methods: Solution adsorption and bacterial growth inhibition were examined in vitro using paper vs RTA discs. Subsequently, 11 patients treated with RTA (mean age, 29.1 ± 4.7 years) were assigned into a sequence of three hygiene protocols: regular RTA brushing (baseline), immersion RTAs in chlorhexidine mouthwash (CHX), and using a vibrating bath with cleaning solution (VBC). For each patient, 12 upper RTAs were examined (2 baseline RTAs, 5 CHX RTAs, and 5 VBC RTAs), for a total of 132 RTAs. All RTAs were stained with gentian violet, and biofilm presence was measured using a photodensitometer.

Results: The RTA discs did not adsorb CHX or cleaning solution. The later agent did not show antibacterial features. Baseline RTAs showed significant biofilm adherence (P < .001) on the posterior palatal side of the aligner and on the anterior incisal edge. CHX and VBC hygienic protocols significantly (P < .001) reduced baseline biofilm adherence by 16% and 50%, respectively. Hygienic improvement was maintained over 140 days when CHX and VBC were used. However, VBC was three times more efficient than CHX.

Conclusions: This study highly recommends the use of a VBC protocol. Biofilm deposits on the RTA, especially on incisal edges and attachment dimples, could lead to inadequate tooth/RTA and attachment/RTA overlap and consequently impair tooth alignment.

Figure 1.

(a) Schematic presentation of the in vitro part of the study. (b) Schematic presentation of the in vivo part of the study.

Figure 2.

(a) Right, an unused unstained aligner. Left, used aligner after staining with gentian violet. R1–R6 are the sites that were scanned and measured in the TINA software. (b) Top, unused, unstained aligner's segment used to calibrate background noises. Bottom, a used aligner's segment. In each tooth, the three sites were delineated in the TINA software for photodensitometric measurements.

Figure 3.

Mean adherent biofilm level in optical density per mm² (OD/mm²) per patient, for each of the three treatment protocols: baseline (B), chlorhexidine (CHX), and vibrating bath with Cleaning-Crystals solution (VBC). The triangle bold curve represents the mean of all 11 patients.

Figure 4.

Baseline group, mean adherent biofilm level per tooth in optical density per mm² (OD/mm²), buccal vs palatal side.

Figure 5.

(a) Baseline group, mean adherent biofilm level (OD/mm²) per site (incisal, middle, gingival) for the buccal side. (b) Baseline group, mean adherent biofilm level (OD/mm²) per site (incisal, middle, gingival) for the palatal side.

Figure 6.

(a) Mean adherent biofilm level in the three hygienic protocol groups (baseline [B], chlorhexidine [CHX], and vibrating bath with cleaning solution [VBC]) for the buccal side. (b) Mean adherent biofilm level in the three hygienic protocol groups (baseline [B], chlorhexidine [CHX], and vibrating bath with cleaning solution [VBC]) for the palatal side.

Figure 7.

Change over time in mean adherent biofilm level during sequential wear of 10 aligners (ie, 5 aligners treated with the CHX protocol, followed by 5 aligners treated with the VBC protocol).