Evaluation of the effect of bracket-periphery treatment on prevention of enamel demineralization by consecutive μCT scans

Comparison of three orthodontic bonding systems in white spot lesion development: a randomized clinical trial

OBJECTIVES

To compare the development of white spot lesions (WSLs) during fixed orthodontic therapy among a conventional three-step bonding system, a self-etching primer bonding system, and a one-step adhesive bonding system.

MATERIALS AND METHODS

Seventy-five patients were randomly allocated into three groups (group 1, conventional bonding system, n = 25; group 2, self-etch primer, n = 25; group 3, primer mixed with adhesive composite, n = 25). Quantitative light-induced fluorescence (QLF) was used to assess WSL parameters. Images were captured and then analyzed before treatment and at 2 months and 4 months after bond up. Lesion area (pixels), mean fluorescence loss (ΔF), and the number of newly developed WSLs were compared within and among the three groups. The significance level was P ≤ .05.

RESULTS

The mean increase in lesion area was 31.3 ± 2.8 pixels, 38.4 ± 4.3 pixels, and 119.5 ± 5.3 pixels for groups 1, 2, and 3, respectively (P ≤ .001). For ΔF, the loss was 3.3% ± 0.3%, 4.4% ± 0.2%, and 6.6% ± 0.2% for groups 1, 2, and 3, respectively. These changes were significantly different (P ≤ .01 to P ≤ .001). The incidence of newly developed lesions was 9.5 WSLs in group 1, 10 WSLs in group 2, and 15.9 WSLs in group 3.

CONCLUSIONS

The lack of primer contributed to the development of a larger number of and more severe WSLs.

In-vivo durability of Pro Seal in patients with fixed orthodontic appliances: A controlled clinical trial

BACKGROUND

This clinical trial aimed at studying the durability of an orthodontic sealant (Pro Seal) used on tooth surfaces for protection against white spot lesions.

METHODS

A total of 35 patients (18 females, 17 males; 17.57 ± 1.36 years) were recruited. Eligibility criteria included healthy patients of both sexes (age > 14 years), absence of labial caries, absence of defective enamel, absence of extensive restorations, and optimum oral hygiene. The participants received a single application of Pro Seal on the bonded teeth. The sealant covered the labial enamel surrounding the brackets. Participants were recalled monthly after sealant application, during which sealant layers were evaluated using an ultraviolet lamp. The assessment was realized using an index similar to the adhesive remnant index (ARI).

RESULTS

A total of 30 participants completed the trial. ARI values dropped significantly (P < 0.001) and reached <1.5 at T₁ on the index used. An ARI value of 2 was chosen as the threshold below which a tooth presented an insufficient sealant layer. The right and left sides of both jaws did not show any statistically significant difference (P > 0.05). ARI values of homolateral teeth revealed few statistically significant differences between upper and lower teeth. No statistically significant difference between the two sexes (P > 0.05) existed. No harm or disturbance was reported by any of the participants.

CONCLUSIONS

This study demonstrated that a single application of Pro Seal is effective for 4 weeks and should be renewed monthly. No interjaw, intrajaw, or intersex significant differences were found.

In vitro surface analysis of the brushing resistance of orthodontic sealants using two different profilometric evaluation methods

The enamel can be protected by applying orthodontic sealants at the bracket base to avoid the development of white spot lesions caused by inadequate oral hygiene. The aim of this study was to investigate the mechanical resistance of five commonly used orthodontic sealants against brushing in comparison to a positive group. Hydroxyapatite discs were bonded with a metal bracket and a piece of arch-wire was ligated in order to simulate a daily clinical situation (n = 48). Samples were divided into 6 groups of respectively 8 specimens. Sealants were applied around the bracket base according to manufacturer's instructions. Following sealants were used: Group 1: Pro Seal (Reliance Orthodontic Products, Itasca, Illinois, USA); 2: Light Bond (Reliance Orthodontic Products, Itasca, Illinois, USA); 3: ClinproXT Varnish (3M ESPE, Seefeld, Germany); 4: ProtectoCaF2 Nano (BonaDent GmbH, Frankfurt am Main, Germany); 5: Fluor Protector and 6: Tetric EvoFlow (both Ivoclar Vivadent AG, Schaan Liechtenstein). Tooth brushing were simulated for 6 weeks and 6 months with an electric toothbrush. The sealant thickness was measured by mechanical (MP) and optical profilometry (OP) at baseline, after 6 weeks and after 6 months of brushing. Statistical analysis was performed according to two mixed linear models and post hoc Tukey-Kramer comparisons. The significance level was set at 5% (α ≤ 0.05). Pro Seal (MP: 9%; OP: 22%) and Light Bond (MP: 19%; OP: 16%) showed the lowest changes in sealant thickness after 6 months of simulated brushing. ClinproXT Varnish and Tetric EvoFlow recorded no statistically significant results (p > 0.05). The fluoride varnishes ProtectoCaF2 Nano and Fluor Protector could not be conclusively evaluated since the thickness of the sealants could not be determined at baseline. The results of both evaluation methods MP and OP are in good agreement. Pro Seal and Light Bond were resistant against tooth brushing and were able to adequately keep the bracket environment sealed even after 6 months. The two different measuring methods, MP and OP, provide a precise impression of the changes in the surface.

Effect of fluoride-releasing 4-META/MMA-TBB resin on enamel demineralization around orthodontic brackets: An in vitro µCT analysis

This study aimed to evaluate the impact of fluoride-releasing 4-META/MMA-TBB resin on the degree of enamel demineralization typically detected around orthodontic brackets using μCT. Enamel-dentin blocks were prepared from bovine teeth. Brackets were attached with either 4-META/MMA-TBB resin (SBC), fluoride-releasing 4-META/MMA-TBB resin (SBF), or fluoride-releasing RMGIC (FLC). The specimens were subjected to demineralization (pH 4.5, 21 days) and scanned by μCT (0, 7, and 21 days). Fluoride ion release under the experimental conditions was measured. The degree of demineralization detected in SBF and FLC was significantly lower than that in SBC; there were no significant differences in the degree of demineralization detected in SBF and FLC. The level of fluoride ion detected in FLC was significantly higher than that detected in SBC. Fluoride-releasing 4-META/MMA-TBB resin protected against enamel demineralization around orthodontic brackets when compared to the results from the fluoride-free resin.

Optical analysis of the behavior of sealants under mechanical, thermal and chemical stress

Regarding their resistance five sealants were tested in vitro after experiencing mechanical, thermal and chemical stress. Included for testing were two fluoride varnishes: Fluor Protector [FP] (Ivoclar Vivadent) and Protecto CaF2 Nano One-Step Seal [PN] (BonaDent) and three fluoride-composite filled sealants (with acid etch technique): Clinpro XT Varnish [CP] (3 M Espe), Pro Seal [PS] & Light Bond [LB] (Reliance Orthodontic Products) and a positive control group [CG] Tetric EvoFlow (Ivoclar Vivadent). The sealants were applied on 180 bovine teeth (n = 10/ sealer) in a standardized manner after bracket bonding. Mechanical pressure and its effect by simulating different time points and standardized electric cleaning protocol was tested first. Followed by thermal burden due to varying thermal stress and thirdly change in pH stress imitating chemical exposure were examined separately. A digital microscope and a grid incisal and apical to the brackets (n = 32 fields) was used to standardize the optical analysis. Material loss due to mechanical stress compared to CG (score 0.00) was CP (1.2%), FP (21.5%), LB (22.2%) and PN (81.1%). No significant difference to CG presented PS. Material loss due to thermal stress was CP (0.5%), PS (2%), FP (2.6%), LB (3.1%) and PN (39.9%). Material loss due to chemical stress was FP (1.8%), PS (2.1%), LB (5.5%) and PN (39.6%). No significant difference to CG presented CP. Only PS and CP had optically provable, good resiliance to mechanical, thermal and chemical stress. Significantly poorer outcomes in particular showed PN.