OCT evaluation of orthodontic surface sealants: a 12-month follow-up randomized clinical trial

Abstract

Objectives: The aim of this single-center randomized controlled trial (NCT03753256) was to assess orthodontic surface sealant layer thickness and integrity in vivo during a 12-month follow-up by optical coherence tomography (OCT).

Materials and methods: Using a split-mouth design, quadrants of 20 patients treated with fixed orthodontic appliances were included. Quadrants were randomly assigned to the sealants Pro Seal® (PS) or Opal® Seal™ (OS). OCT scans were performed immediately after the application of the sealants and after 3, 6, 9, and 12 months. Sealant layer thicknesses and their integrity were determined at 5 regions of interest (ROIs) known for high risks of demineralization. Sealant integrity loss was determined using a self-developed scale.

Results: A total of 16 patients successfully completed the study. The studied sealants showed significant differences in initial layer thickness. Mean layer thickness was significantly lower for PS (67.8 μm, (95% CI, 56.1-79.5)) than for OS (110.7 μm, (95% CI, 97.3-124.1)). Layer thickness loss was significant after 3 months for PS and after 6 months for OS. Sealant integrity was compromised in more than 50% of the ROIs already after 3 months for both sealants.

Conclusions: Patients treated with fixed orthodontic surface sealants lost the integrity of the protective layer in more than 50% of cases after 3 months, and the layer thickness of the sealants was significantly reduced after 3-6 months.

Clinical relevance: The protective effect against demineralization lesions of orthodontic sealants in patients treated with fixed appliances appears to be limited in time. Further preventive measures should be investigated.

Trial registration: ClinicalTrials.gov (NCT03753256).

Keywords: Abrasion; Demineralization; Orthodontic treatment; Surface sealants; Tooth cleaning procedures.

Conflict of interest statement

The authors declare that they have no conflict of interest.

Figures

Fig. 1

Study outcomes by OCT evaluation. A OCT measurements in a clinical setting: Patients rested their chin and forehead or glabella against the supporting surfaces of the device during the OCT image acquisition. A retractor for the cheek and lips was used to expose the scanning area. A cotton roll was used to uncover the teeth of the lower jaw. B Sealant thickness measurements on the bracket bonded central incisors. Left: 5 regions of interests (ROI) on the labial tooth surface with high risks of demineralization were examined―1 mm from the gingival margin (1) and 1 mm from the bracket in four directions, gingival (2), mesial (3), distal (4), and incisal (5). Right: Exemplified surface sealant layer thickness measurement using cross-sectional OCT images (b-scans) perpendicular to the labial tooth surface. The b-scans were oriented parallel to the bracket slots and four b-scans (b1–b4) were chosen to capture 5 ROIs. C A schematic representation of the criteria established for the scoring of sealant integrity loss based on cross-sectional OCT images. Sealant integrity loss on all cross sections was determined using the following scale: 0 (no integrity loss), 1 (< 50% integrity loss), 2 (> 50% integrity loss), and 3 (100% integrity loss). Left column: Illustration of the integrity loss scale. For better visualization sealants are depicted in yellow, tooth structures in white and gap formation in red. Right column: representative OCT cross-sectional images

Fig. 2

Flowcharts of patients and outcome measures

Fig. 3

Boxplots and a schematic illustration of initial material layer thickness. A Box plots comparing initial sealant layer thicknesses between the sealant groups at the different ROIs. Localization of the ROIs (1–5) is schematically depicted on the right. A significant difference between PS and OS was detected at the most gingival measurement point (ROI 1), and apparent differences between the sealants at the other ROIs. B Box plots comparing initial sealant layer thicknesses at different ROIs () within the sealant groups. PS (left), OS (right)

Fig. 4

Longitudinal view of sealant layer thickness during the 12-month observation period. Layer thickness reduction of Pro Seal® (a) and Opal® Seal™ (b) during the 12-month observation period thick midlines in the graphs represent the smoothed local mean with point wise 95% confidence intervals (yellow and green areas)

Fig. 5

Representative OCT images for both sealants during the 12 months of observation at different ROIs. The four cross-sectional OCT scan images (b-scans, b1–b4) are oriented in parallel to the bracket slots to capture 5 ROIs (numbers in circles 1–5, see also Figs. 1B and 3A for details). Layer thickness reduction and integrity loss of both sealants show the substantial functional loss of both materials

Fig. 6

Representative OCT images for both sealants showing different levels of impaired integrity (score 0–3) including up to 100% loss of surface sealant