Introduction
The objective of this research was to evaluate and compare the effectiveness of microabrasion and resin infiltration for white spot lesions (WSLs).
Methods
Patients with postorthodontic WSLs were enrolled and randomly assigned to the control, microabrasion, and resin-infiltration groups. Intraoral photographs were taken before and after (6 months later) treatment. WSL sizes were determined through ImageJ (Wayne Rasband, Kensington, Md). Integrated optical density (IOD) was determined for a WSL and its surrounding normal enamel through Image-Pro Plus (version 6.0; Media Cybernetics, Rockville, Md), and their differences of IOD were considered as the IOD surrogate for that WSL. The color change of WSL were measured through ΔE.
Results
A total of 27 eligible patients were enrolled; 9 subjects were assigned to each group, resulting in 56 teeth in the control group, 72 in the microabrasion group, and 58 in the resin-infiltration group. The ratios of WSL size (after/before) were similar between the microabrasion and resin-infiltration group (43.94 ± 0.03% vs 45.02 ± 0.03%; P = 0.96 > 0.05), but those of the 2 groups were significantly lower than those of the control group (92.15 ± 0.02%) ( P <0.001). Moreover, the ratios of IOD (after/before) were significantly lower in the resin-infiltration group (22.94 ± 0.02%) than in the microabrasion (78.11 ± 0.03%) and control (83.79 ± 0.02%) ( P <0.001) groups. The highest ΔE improvement was obtained by infiltration, but there was no significant difference between microabrasion and control group.
Conclusions
Resin infiltration and microabrasion are comparably effective in reducing the sizes of WSL, but resin infiltration enjoys an esthetic advantage over microabrasion.
Highlights
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Postorthodontic white spot lesions warrant appropriate interventions.
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Resin infiltration and microabrasion are comparably effective for white spot lesions.
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Resin infiltration enjoys an esthetic advantage over microabrasion.
White spot lesion (WSL), an early carious lesion characterized by increased enamel opacity, is a common sequela of orthodontic treatment. It has been reported that 25%-75% of orthodontic patients developed WSL at the end of active orthodontic treatment. , It severely jeopardizes patients’ satisfaction toward orthodontic treatment outcomes. Excessive enamel demineralization, the hallmark of WSL, is caused mainly by bacterial accumulations and acid formations that are due to inadequate oral hygiene. , Unfortunately, natural regression of WSL after orthodontic treatment is limited, , warranting appropriate interventions.
Currently, several techniques have been developed for the postorthodontic WSL: fluoride treatment, application of remineralization reagents, microabrasion, and resin infiltration. Among them, fluoride and remineralization reagents have been reported to be effective for only prevention but not for treatment, , while microabrasion and resin infiltration are able to treat WSL. , The mechanism of microabrasion is believed to be removing the superficial hypermineralized enamel and promoting the remineralization of underlying demineralized enamel, while resin infiltration acts through filling the micro-cavities and masking the opaque appearance. However, to date, it is largely unknown which approach is more effective. Therefore, we aimed to evaluate the effectiveness of microabrasion and resin infiltration for WSL and to compare their effectiveness in treating postorthodontic WSL.
Material and methods
Consecutive patients who developed WSL after active orthodontic treatments in Department of Orthodontics were prospectively enrolled in this study from Sept 2014 to Aug 2016. The informed consents were obtained from all the participants or their guardians before their participations in this study. The inclusion criteria were permanent dentition, patients receiving labial fixed orthodontic treatments, presence of WSL on at least one anterior tooth after active orthodontic treatments, both genders and ages between 12 years and 30 years. The exclusion criteria included presence of WSL before orthodontic treatments, severe caries, smoking habits, previous bleaching treatments, enamel defects, and dental anomaly. Sample size was calculated based on 2 previous studies , where we calculated a difference in mean between microabrasion and resin infiltration (21.2%; WSL area change in percentage) and a standard deviation of 23.9%. The minimum tooth number is 21 teeth in each group.
We established the diagnosis of WSL through clinical examinations on the day of finishing active orthodontic treatments. Specifically, after the removal of brackets and remaining adhesive materials, anterior teeth were brushed, air-dried, and visually examined for the presence of WSL. Eligible patients were randomly assigned to the following 3 groups through dice-throwing: control group, microabrasion group, and resin-infiltration group. The patients in the control group received fluoride-containing toothpaste that had an effective sodium-fluoride content of 0.1%, and they were instructed to brush their teeth with the Bass Method after meals; those in the microabrasion group received 3 microabrasion treatments (1 week after removal of orthodontic appliances, 2 months later, and 4 months later); those in the resin-infiltration group received ICON (DMG, Redgefield Park, NJ) resin infiltration treatment 1 week after the removal of orthodontic appliances.
Microabrasion was conducted according to the methods described previously. In brief, semiliquid microabrasive reagent was prepared by mixing 18% hydrochloric acid with fine pumice powder. After washing and cleaning the affected teeth thoroughly, we mounted rubber dams to protect gingival tissues and other unaffected teeth. Then, after the microabrasive reagent was applied onto the lesion surfaces for 30 seconds, we performed the microabrasion by using rubber cups mounted on a contraangle handpiece for 30 seconds and washed off the microabrasive reagent with water-air spray. This cycle was repeated for 3 times for each affected lesion surface.
Icon resin infiltration was performed strictly according to manufacturer’s protocol. Briefly, after teeth were thoroughly washed and cleaned, rubber dams were mounted to protect gingival tissues and avoid moisture. Then, we etched the enamel surfaces of WSL, applied the Icon infiltrant onto the lesion and light-cured for 40 seconds.
The extent of WSL was evaluated through intraoral photography at 2 time points: before WSL treatment (immediately after debonding) and after WSL treatment (6 months later). All the patients were instructed to sit on the same dental chair and their affected teeth were thoroughly brushed, washed, and dried. Then, standardized intraoral photographs were taken perpendicular to the lesion surfaces of affected teeth through using a digital camera (Nikon D80; Nikon, Minato City, Tokyo, Japan) setting with the parameters as follows: Shutter Speed 1/200, F22, ISO 400, Auto White Balance. Considering that the severity of WSL comprises the extent and opacity, the severity of WSL was evaluated through the following 3 indexes: area, optical density, and color change. Through using intraoral photographs, the area of the lesion on each affected tooth was calibrated by its mesio-distal width and measured in ImageJ software (Wayne Rasband, Kensington, Md). Moreover, integrated optical densities of a WSL lesion and its surrounding normal enamel were determined by using Image-Pro Plus (version 6.0; Media Cybernetics, Rockville, Md) , and the integrated optical density (IOD) difference between a WSL lesion and its surrounding normal enamel was calculated and considered as the IOD surrogate for that lesion. The color change of the lesion was measured according to Commission International de l’Eclariage L∗a∗b∗ system. With the help of Photoshop software (Adobe Inc, San Jose, Calif), the value of L∗ ∖a∗∖ b∗ could be observed and ΔE was calculated as follows:
ΔE = [(L 1 ∗-L 2 ∗) 2 +(a 1 ∗-a 2 ∗) 2 +(b 1 ∗-b 2 ∗) 2 ] 1/2
After the affected teeth were thoroughly brushed, washed, and dried, all visible part of the WSL were divided into 3 × 3 sections and then calculated ΔE of the 9 parts to get the average ΔE. It is reported that when ΔE exceeded 3.7 units, the color change could be clinically visible. ,
To determine the intraobserver reliability of the measurements, data were reevaluated by the same operator 1 week after the first assessment. The reproducibility of the measurements was tested by intraclass correlation coefficient.
The comparisons between before-treatment and after-treatment were analyzed through Student’s paired t test. Analysis of variance (ANOVA) with post-hoc Turkey test was used to compare the 3 groups. The sample size calculation was performed based on difference in mean and standard deviation reported previously. , All the statistical analyses and the sample size calculation were performed in SPSS (version 16.0; SPSS, Chicago, Ill) and StatsDirect (version 2.7.2; StatsDirect Ltd, Merseyside, UK). A P value less than 0.05 was considered as statistical significance.
Results
A total of 27 consecutive patients with postorthodontic WSL were recruited in this study and randomly divided into the following three groups: control group (n = 9), microabrasion group (n = 9), and resin-infiltration group (n = 9). As displayed in Table I , all the demographic data were well-balanced across the three groups. For the ease of analysis, we regarded teeth, rather than patients, as our study unit. This resulted in 56 teeth in the control group, 72 in the microabrasion group, and 58 in the resin-infiltration group. As presented in Table II , the baseline data were similar among the 3 groups except for the IOD ( P <0.001). The intraclass correlation coefficients were 0.998 for sizes of WSL value, 0.996 for IOD, and 0.896 for ΔE. There is no side-effects reported from the patients.
| Item | Control (n = 9) | Microabrasion (n = 9) | ICON (n = 9) | P value | |||
|---|---|---|---|---|---|---|---|
| Mean + SEM | Range | Mean + SEM | Range | Mean + SEM | Range | ||
| Age (y) | 17.9 ± 1.0 | 15.0-23.0 | 17.7 ± 0.9 | 15.0-21.0 | 17.2 ± 0.9 | 15.0-22.0 | 0.87 |
| Gender (male/female) | 3/6 | 2/7 | 5/4 | 0.48 | |||
| Treatment duration (months) ∗ | 38.4 ± 3.5 | 28.0-58.0 | 39.8 ± 5.0 | 17.0-63.0 | 37.7 ± 2.5 | 24.0-48.0 | 0.93 |
| Affected teeth, mean | 6.2 ± 1.2 | 1.0-12.0 | 8.0 ± 0.7 | 4.0-11.0 | 6.4 ± 1.0 | 2.0-11.0 | 0.41 |
| Affected teeth, total | 56 | 72 | 58 | – | |||
∗ It refers to the duration of active orthodontic treatment; data were presented as mean ± SEM.
| WSL | Control (n = 56) | Microabrasion (n = 72) | ICON (n = 58) | P value | |||
|---|---|---|---|---|---|---|---|
| Mean + SEM | Range | Mean + SEM | Range | Mean + SEM | Range | ||
| Area | 8.0 ± 0.8 | 1.22-28.08 | 10.1 ± 0.8 | 0.74-34.49 | 9.9 ± 1.4 | 1.02-60.16 | 0.30 |
| IOD | 28.0 ± 1.3 | 6.19-57.03 | 22.8 ± 1.0 | 4.46-49.43 | 33.1 ± 1.8 | 8.36-61.97 | <0.001 |
| Tooth type | 0.99 | ||||||
| Maxillary central incisor | 10 | 16 | 11 | ||||
| Maxillary lateral incisor | 13 | 18 | 14 | ||||
| Maxillary canine | 12 | 15 | 12 | ||||
| Mandibular central incisor | 2 | 1 | 3 | ||||
| Mandibular lateral incisor | 6 | 9 | 7 | ||||
| Mandibular canine | 13 | 13 | 11 | ||||
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