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Evaluation of enamel demineralization in adolescents after rapid maxillary expansion using the quantitative light-induced fluorescence method: A single-center, randomized controlled clinical trial
RANDOMIZED CONTROLLED TRIAL
Evaluation of enamel demineralization in adolescents after rapid maxillary expansion using the quantitative light-induced fluorescence method: A single-center, randomized controlled clinical trial Asli Baysal,a Seher Nazlı Ulusoy,b and Tancan Uysalc Izmir, Turkey
Introduction: The aim of this 2-arm parallel trial was to evaluate enamel demineralization after rapid maxillary expansion (RME) compared with an untreated control group using quantitative light-induced fluorescence. Methods: Thirty-six patients who needed RME as part of their orthodontic treatment were separated randomly into either the control group or the intervention group (RME). Eligibility criteria included crossbite, no previous orthodontic treatment, no systemic disease, and all permanent teeth erupted except second and third molars. The main outcome was quantitative evaluation of demineralization, and assessment of the vulnerability of each tooth to demineralization was the secondary outcome. Randomization was made at the start of the study with preprepared random number tables. Blinding was applicable for outcome assessment only. Patients in the RME group underwent expansion with a bonded acrylic expander; patients in the control group were untreated. Records were taken using quantitative light-induced fluorescence Digital Biluminator (Inspektor Research Systems, Amsterdam, The Netherlands) in pretreatment and posttreatment observation phases. The presence and extent of lesions on the buccal surfaces of all teeth, except the second and third molars, were assessed. The fluorescence loss, lesion area, and percentage of fluorescence loss were determined using the system's software. The numbers of teeth with more than a 5% change in fluorescence loss, were calculated. Data were analyzed with Wilcoxon signed rank, Mann-Whitney U, multivariate analysis of variance, and chi-square tests (P \0.05). Risk and odds ratios were calculated. Results: A total of 36 patients were randomized to either the RME or the control group in a 1:1 ratio. This study was completed with 18 patients in the RME group (8 girls, 10 boys; mean age, 14.2 6 1.0 years) and 18 patients in the control group (10 girls, 8 boys; mean age: 14.1 6 0.8 years). All patients completed the study, and none were lost to follow-up. The area of demineralization decreased in the RME group ( 17.50 mm2), which was a significantly greater decrease than in the control group (0.00) (effect size, 2.63; mean difference, 87.94; 95% confidence interval, 223.7547.86; P 5 0.008). No statistically significant difference was found for fluorescence loss. The numbers of teeth with demineralization and remineralization were higher in the treatment group. According to the risk ratio, the difference between groups regarding demineralization was not significant. No harm was found except gingivitis associated with the bonded appliance. Conclusions: RME therapy using a bonded expander does not increase enamel demineralization. Registration: This trial was not registered. Protocol: The protocol was not published before trial commencement. (Am J Orthod Dentofacial Orthop 2016;150:731-9)
R
apid maxillary expansion (RME) is used to correct posterior crossbites, improve smile esthetics, and increase arch length and airway clearance. With
RME, the midpalatal suture is separated, cell activity increases in the suture area, and bone is gained in the transversal plane.1
From the Department of Orthodontics, Faculty of Dentistry, Izmir Katip Celebi University, Izmir, Turkey. a Associate professor. b Research assistant. c Professor. All authors have completed and submitted the ICMJE Form for Disclosure of Potential Conflicts of Interest, and none were reported. Supported by a research grant from Izmir Katip Celebi University, Scientific Research Projects Unit (project number: 2013-2–TSBP-06).
€ Address correspondence to: Asli Baysal, Izmir Katip Celebi Universitesi, Dis¸ Hekimligi Fak€ ultesi, Ortodonti A.D., Cigli, Izmir, Turkey; e-mail, baysalasli@ hotmail.com. Submitted, October 2015; revised and accepted, June 2016. 0889-5406/$36.00 Ó 2016 by the American Association of Orthodontists. All rights reserved. http://dx.doi.org/10.1016/j.ajodo.2016.06.014
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The appliances used for RME are 2 types: bonded and banded. Bonded RME appliances have been often preferred recently because the rigidity of the bonded RME appliance causes less tipping of the teeth.2 The appliance consists of a screw in the middle of the palate and an acrylic cap that covers the teeth. Because the sutural organization has been affected by RME, reorganization necessitates a long retention period.1 Wearing the appliance during the active treatment period and the retention phase makes it more difficult for patients to establish proper oral hygiene; this causes microbial plaque accumulation. For this reason, expansion seems to increase the demineralization risk.3 Demineralization results in compromised esthetics and may require invasive intervention, with additional financial, emotional, and biologic costs to patients and their families, and a frustrating clinical dilemma for orthodontists. Quantitative light-induced fluorescence (QLF) is a new technique for the detection of early mineral changes in enamel.4 The fluorescence image of enamel with early lesions can be digitized, and the fluorescence loss in the lesion can then be quantified in relation to the fluorescence radiance level of sound enamel.5,6 Recent studies indicate that QLF is suitable for in-vivo monitoring of mineral changes in early enamel lesions.4,6,7 Furthermore, the use of QLF as a method of following caries development during orthodontic treatment has been suggested for quantitative judgment of the same lesion at different times.8 Although there have been many studies in the orthodontic literature to evaluate enamel demineralization around orthodontic brackets, to our knowledge no study in the literature has evaluated the demineralization effect of RME using a bonded acrylic appliance. Because of the limited research available in this area, the aim of this study was to evaluate enamel demineralization after RME using the QLF method in vivo. Specific objectives or hypotheses
In this study, we tested the hypotheses that (1) there is no difference between RME-treated and untreated subjects regarding the amount of demineralization quantitatively, (2) the numbers of teeth showing demineralization do not differ between RME-treated and untreated subjects, and (3) there is no difference between teeth regarding their vulnerability to enamel demineralization. MATERIAL AND METHODS Trial design
This was a 2-arm parallel-group, randomized, controlled trial with a 1:1 allocation ratio.
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Participants, eligibility criteria, and settings
Approval of the medical ethical committee of Izmir Katip Celebi University, Izmir, Turkey was obtained for this study (number 64). The participants were selected from those who needed to be treated with RME and put on the waiting list of the orthodontic department's clinic. The sample comprised 36 patients. The inclusion criteria were as follows: (1) unilateral or bilateral crossbite caused by a transversal maxillary deficiency, (2) no previous orthodontic treatment, (3) no systemic disease, and (4) all permanent teeth erupted except second and third molars. Interventions
In the first group, RME was applied until the palatal cusps of the maxillary molars and the buccal cusps of the mandibular molars were in the same plane transversally. The patients in the control group were not treated in the first phase, and the observation period was 6 months. During the observation period, interceptive treatments were performed in the control group; immediately after that, their orthodontic treatment was initiated. This study was completed with 18 patients in the treatment group (8 girls, 10 boys; mean age, 14.2 6 1.0 years) and 18 patients in the control group (10 girls, 8 boys; mean age, 14.1 6 0.8 years). The flow of the patients through the trial is shown in Figure 1. Orthopedic expansion was performed with a bonded type of RME appliance (Fig 2). A hyrax screw (Dentaurum, Pforzheim, Germany) was placed between the second premolars. The palate was covered with acrylic, which extended to the occlusal and middle thirds of the buccal surfaces of the teeth. This appliance was bonded to the maxillary dentition with glass ionomer cement (Ketac Cem Radiopaque; 3M ESPE Dental Products, Neuss, Germany). The screw activation was a quarter turn twice for the first week and a quarter turn per day after that. When the desired amount of expansion was achieved, the screw was stabilized with a ligature wire and kept in the mouth passively for a month. The patients were instructed to wear a Hawley appliance for the rest of their retention period. At 6 months, the QLF recordings were performed in treatment and control groups. Records were taken using a QLF Digital Biluminator (QLF-D, Inspektor Pro; Inspektor Research Systems, Amsterdam, The Netherlands) in the pretreatment and posttreatment observation phases. The QLF-D is an upgraded version of the first product with a modified filter set (D007; Inspektor Research Systems).9 The system consisted of a special camera connected to a personal computer in which the QLF-D software was installed. Camera settings were optimized for the environment where the photos were taken, and fixed settings
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Fig 1. Flow of patients through the trial.
Fig 2. RME appliance used in the study.
(ISO, 1600; shutter speed, 1/30 second) were then locked in the software. The camera was used with a manual focus at the canines for the front teeth and at the second premolars for the posterior teeth. To ensure standardization, the images were captured with the same camera position and from the same angle. The images were processed with the software using video-repositioning techniques according to the manufacturer's instructions.
using the QLF method. The secondary outcome measures were the assessment of enamel demineralization of individual teeth and the determination of whether any tooth is more vulnerable to demineralization. The presence and extent of lesions on the buccal surfaces of all teeth, except second and third molars, were assessed by the QLF-D software at the pretreatment observation visit and the posttreatment observation visit. Thus, 12 buccal surfaces per subject were assessed at each time point. The analysis of the images involved the placement of an analysis patch in the stained area, ensuring that the borders of the patch fell on sound enamel. The average fluorescence loss, lesion area, and the percentage of fluorescence loss were determined using the system's analysis software to determine the lesion extent. The decrease in fluorescence was determined by calculating the percentage difference between the actual and reconstructed fluorescence surfaces. A threshold value was set at a level of 5% fluorescence loss, which showed a minimum 5% fluorescence loss change between first and second measurements.10 The lesions captured by the QLF-D clinical system were analyzed quantitatively with the QLF-D software. No changes to the methods or no outcome changes were occurred after trial commencement.
Outcomes (primary and secondary) and any changes after trial commencement
Sample size calculation
The primary outcome in this investigation was the quantitative evaluation of enamel demineralization
A multivariate analysis of variance with 2 outcome variables and 1 factor with 2 levels indicated at least
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80% statistical power based on a medium effect size, Cohen's d 5 0.66, (refer to effect size reported in a similar study: Al-Khateeb S, Forsberg CM, de Josselin de Jong E, Angmar-Mansson B. A longitudinal laser fluorescence study of white spot lesions in orthodontic patients. Am J Orthod Dentofacial Orthop 1998;113:595-602; mean difference, 4.02; SD, 3.59) necessitated a minimum sample size of 18 in each group to detect a significant difference between the groups. Interim analyses and stopping guidelines
Not applicable. Randomization (random number generation, allocation concealment, and implementation of the random sequence)
When a patient who fulfilled the inclusion criteria attended the clinic, the patient and parents were informed and invited to participate in the study. If the child and the parents consented, the initial records were taken, and each patient was randomized to receive treatment with a rapid palatal expander or to have treatment delayed for at least 6 months. Randomization was done at the start of the study with random number tables prepared using SPSS software (version 20.0; IBM, Armonk, NY). One researcher (S.N.U.) evaluated the patients, and another author (A.B.) enrolled the patients. The allocation sequence was concealed using numbered and sealed opaque envelopes. Thirtysix patients (mean age, 14.1 6 0.8 years; range, 11.416.5 years) were randomized in a 1:1 ratio to either the treatment or the control group.
Table I. Demographic and clinical characteristics of
participants
Age (y), mean 6 SD Boys (n) Girls (n) Malocclusion (n) Class I Class II Class III White spot lesions (n), mean 6 SD
Treatment group 14.2 6 1.0 10 8
Control group 14.1 6 0.8 8 10
Total 14.1 6 0.8 18 18
4 10 4 3.22 6 2.75
2 11 5 1.33 6 1.91
6 21 9 2.28 6 2.52
The normality test of Shapiro-Wilks and the Levene variance homogeneity test were applied to the data. The data were not normally distributed; thus, nonparametric tests were used. Fluorescence losses and areas of demineralization change were evaluated using MannWhitney U and Wilcoxon signed rank tests for intergroup and intragroup comparisons, respectively. Risk ratios and odds ratios were carried out with statistical methods for new lesion development and lesion remineralization. Confidence intervals (95% CI) were also calculated for relative risks. To compare the percentages of samples that exceeded the 5% fluorescence loss threshold limit in each group, the chi-square test was used. One-way analysis of variance was used to test the differences of fluorescence loss values of each tooth. Statistical significance was set at P #0.05. RESULTS Participent flow
Blinding
Blinding of either patient or operator was not possible. Statistical analysis (primary and secondary outcomes, subgroup analyses)
The data acquired were analyzed statistically to evaluate the possible changes between the treated and control groups. All data were entered into SPSS software for the statistical analysis. To evaluate the cluster effect, the intracluster correlation coefficients (ICC) were calculated for each dependent variable. The ICC values ranged between 9% and 23%, indicating a clustering effect. Although the mixed model takes care of the cluster effect, nonnormal data causes the parametric model to be unreliable. Thus, patient was chosen for unit of analysis instead of the tooth; the mean value per patient was obtained, and these data were analyzed at the patient level.
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This study was completed with 18 patients in the treatment group (8 girls, 10 boys; mean age, 14.2 6 1.0 years) and 18 patients in the control group (10 girls, 8 boys; mean age, 14.1 6 0.8 years). A total of 432 teeth (216 in each group) were evaluated. The analyses were carried out in all patients. Losses and exclusions after randomization
The treatments and observations of all patients were completed without dropouts. Baseline data
The baseline demographic and clinical characteristics of the patients are given in Table I. Follow-up period
The follow-up period for both groups was 6 months.
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2.192 1.447 2.637 Different superscript letters denote statistically significant differences between 2 medians at the 0.05 level. MD, Mean of differences; ES, effect size 5 Z value; P \0.05; T0, pretreatment or first observation visit; T1, posttreatment or second observation visit; NS, nonsignificant.
0.031 NS 0.008 64.97 54.03 47.86 9.37 5.65 223.75 37.17 29.84 87.94 10.90 10.88 98.28 7.81 9.04 14.66 29.83 30.92 202.00 0.00 0.00 259.00 0.21 3.54 0.00 NS 57.00 49.31 265.93 173.50 161.42 739.00
44.98 38.88 73.27
0.011 NS NS 0.67 0.27 1.63 3.83 3.23 0.63 2.25 1.74 0.49
0.00 0.00 610
Median SD Mean RME group (n 5 18)
Table III. Descriptive statistics and intragroup and intergroup comparisons
To present the cluster effect, ICC values were calculated for each dependent variable (Table II). The results of the descriptive statistics and intragroup and intergroup comparisons of the mean changes between pretreatment and posttreatment are given in Table III. Pretreatment fluorescence loss greater for the RME group, and the difference between groups was statistically significant (P 5 0.011). After treatment, there was no statistically significant difference between the groups. The area of demineralization was greater in the RME group before treatment (P 5 0.031). After treatment, the areas of demineralization increased in the control group and decreased in the RME group. Although the posttreatment values were comparable, the changes in demineralization areas between time points (treatment effects) were statistically significant between the groups (P 5 0.008). As assessed by the QLF-D, the lesions on the 432 buccal surfaces of the teeth, except for the second and third molars, were evaluated. In the treatment group, 58 lesions at pretreatment and 49 lesions at posttreatment were detected. In the control group, 24 lesions at the first observation and 26 lesions at the second observation were found. In the treatment group, 16 lesions had disappeared, and 6 lesions had developed in the posttreatment period. In the control group, 6 lesions had disappeared, and 6 had developed. The risk ratio was 1.0 (95% CI, 0.317-3.151). The groups were comparable for new lesion development. The odds ratio was 2.8 (95% CI, 1.07-7.29). Thus, the treatment group had
Control group (n 5 18)
Numbers analyzed for each outcome, estimation and precision, and subgroup analyses
1.06 0.96 0.60
T0, Pretreatment or first observation visit; T1, posttreatment or second observation visit.
0.74 0.83 0.87
0.225
0.00 0.00 1.32
1.47
3.9 3.75 1.09
11
0.23 0.55 0.00 NS
5046.91
3.12 2.94 2.28
5045
2.99 2.58 0.40
0.998
Significance
0.28
Upper
12
Lower
2320.36
MD
2327.96
SD
0.999
Mean
14.63
Maximum
10
Minimum
5097.7
Maximum
5115.23
Minimum
P 0.948 0.996 1
Median Fluorescence loss Pretreatment 1.14 Posttreatment 1.66 Difference (T1-T0) 0.00 Significance NS Area of demineralization Pretreatment 12.07a Posttreatment 17.36b Difference (T1-T0) 17.50 Significance 0.023
Random Random intercept 1 ICC intercept slope (%) F 2489.35 2475.55 23 21.73 2588.22 2576.54 15 18.03 5300.5 5281.28 9 14.57
95% CI
Dependent variables T0 fluorescence loss T1 fluorescence loss T0 demineralization area T1 demineralization area T1-T0 fuorescence loss T1-T0 demineralization area
Intergroup comparison
Type III fixed effects
AIC
0.00 0.66 8.39
intercept plus slope models
10.43 10.6 2.13
ES
Table II. Results of random intercept and random
2.564 1.862 0.683
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Table IV. Comparisons of the groups for numbers of
teeth in the different categories Change 0, no change
Distribution Count % in group 1, fluorescence loss Count (T0-T1) decrease % in group 2, fluorescence loss Count (T0-T1) increase % in group Total Count % in group
Treatment Control group group 152a 186b 70.4% 86.1% 36a 15b 16.7% 28a 13.0% 216 100.0%
6.9% 15b
Total 338 78.2% 51 11.8% 43
6.9% 10.0% 216 432 100.0% 100.0%
Each subscript letter denotes a subset of group categories whose column proportions do not differ significantly from each other at the 0.05 level.
a 2.8-fold remineralizing ratio compared with the control group. The groups were further analyzed for demineralization, with a 5% fluorescence loss change as the threshold limit between the first and second records (Table IV). Three categories were generated as “no change,” “demineralization,” and “remineralization.” If the change did not reach the 5% threshold limit, the teeth were categorized as “no change.” When the change exceeded the threshold limit and the fluorescence loss increased from the first to the second observation, the teeth were recorded in the demineralization category. In the opposite situation, teeth were recorded in the remineralization category. According to the results of the chi-square test, statistically significant differences were found between the groups for all categories (Table IV). No changes were found for 152 of the 216 teeth (70.4%) in the treatment group and 186 of the 216 teeth (86.1%) in the control group. In the treatment group, demineralization was seen in 13.0% of the teeth, and remineralization was recorded in 16.7% of the teeth. These ratios were 6.9% for both categories in the control group. The mean fluorescence loss differences between the 2 observations for each tooth are shown in Figure 3. No statistically significant differences were found between the mean fluorescence loss values of each tooth. The maximum mean fluorescence loss differences were found in the maxillary right lateral incisors and canines, and the maxillary left canines. Harms
No serious harm was observed in the treatment group other than gingivitis associated with the difficulty of plaque removal.
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DISCUSSION Main findings in the context of the existing evidence and interpretation
The purpose of this study was to evaluate tooth demineralization after bonded RME using the QLF method. According to our results, no difference was found between groups regarding demineralization (by means of fluorescence loss). Moreover, the areas of demineralization showed greater improvements (reductions) in the treatment group after 6 months of retention. This finding should be interpreted cautiously because the reduction in the surface area may not mean regression of demineralization. The depth of the lesion may be increasing, while the area is getting smaller. On the other hand, the numbers of teeth in the demineralization and remineralization categories in the treatment group were greater than in the control group. When these factors are taken into account, it is hard to conclude that the changes in the treatment group are solely in the trend of demineralization or remineralization. The greater improvement in the treatment group may be explained in 2 ways. Because the initial demineralization was higher, greater remineralization might have been seen in treatment group. The second factor may be the use of glass ionomer cement for expander cementation. The remineralization potential of the lesions may be improved with glass ionomer cement. Previous studies have indicated that the formation of white spot lesions decreased when orthodontic bands were cemented with glass ionomer cement.11,12 The major favorable feature of glass ionomer cement is the ability to act as a fluoride ion reservoir; therefore, the demineralization risk is decreased.8,13,14 The release of fluoride ions from glass ionomer cement has been shown to inhibit demineralization.15 The researchers showed that ion release begins with mixing glass ionomer cement and the effect remains for about 12 months at a certain level.15-17 Glass ionomer cement not only inhibits demineralization but also demonstrates the ability to remineralize enamel.18 The reduction in white spot lesion formation with glass ionomer cement for bonding in orthodontics can be significant, with an average reduction of 16.5% having been achieved when compared with the use of composite resin cements in a longitudinal study of 60 patients.19 In our study, 16 lesions disappeared, and 6 lesions developed in the treatment group, while 6 lesions were lost, and 6 lesions developed in the postobservation period of the control group. The risk of developing new white spot lesions was comparable between groups (risk ratio 5 1) whereas remineralized lesions were greater in the treatment group (odds ratio 5 2.8). This finding and the disappearance of 16 lesions from the
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Fig 3. Mean fluorescence loss differences between the 2 observations for each tooth. T0, Pretreatment or first observation visit; T1, posttreatment or second observation visit.
treatment group may be the result of the properties of glass ionomer cement. According to epidemiologic studies, maxillary lateral incisors and mandibular first molars have the highest frequencies of white spot lesions.20,21 Mandibular second premolars and maxillary canines are also commonly affected.20,21 According to our results, no significant differences were found between the mean fluorescence loss differences of each tooth. However, the maximum mean fluorescence loss differences were found in the maxillary right lateral incisors and canines, and the left canines. Orthodontists should keep in mind this information during treatment, since the demineralization of anterior teeth more seriously affects a patient's esthetics compared with posterior teeth. New methods for early caries diagnosis have been developed to detect lesions in the early stages before cavitation occurs and restoration is needed.20 This diagnosis is predominantly based on subjective interpretation of visual information: visual inspection, bitewing radiography, fibre-optic transillumination, and transverse microradiography.21 These methods are objective and quantitative, allowing longitudinal monitoring over time of lesion progression. We used QLF, which has been shown to be a precise tool to detect demineralization.21 The best approach to fight enamel demineralization is to prevent white spot lesions.22 There is no way to detect incipient white spot lesions because the RME
appliance covers the teeth. Enamel demineralization was reported to occur over 9 months with bonded RME appliances.23 Therefore, it may be useful not to have a long RME treatment. The gold standard technique for quantifying changes in mineral content of early carious lesions is transverse microradiography.24 However, this technique requires preparation of thin tooth sections and, therefore, cannot be used to monitor white spot lesions undergoing treatment in vivo. It was concluded that QLF-D is suitable for in-vivo longitudinal studies.6,7 The QLF method shows excellent in-vivo repeatability and reproducibility, and could monitor the mineral changes in early enamel lesions and might be useful for clinical trials.6,7,23 Progression, regression, or stability of lesions can now be assessed when a white spot lesion is barely seen, whereas traditional methods show only absence, presence, and type of lesions.22 The disadvantages of this technology are that it is expensive, requires more space in the dental operatory, and requires special technical training for the operator to obtain reliable results. Even though many studies in the literature have used QLF to evaluate demineralization quantitatively, few studies have been performed with QLF-D. In our in-vivo study, QLF was able to detect and longitudinally monitor the demineralization of teeth after bonded RME therapy. On the other hand, some QLF images had to be omitted because of technical errors
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such as dark images, out-of-focus images, or angulation errors. These drawbacks were overcome by taking 2 images for each projection. We were trained before the study, when representative before and after images of patients were sent to the manufacturer, and we received positive feedback regarding the quality of the images. The general expectation of new white spot lesion formation after RME appliance removal was not observed in this study. The use of glass ionomer cement for RME cementation may reduce the occurrence and severity of white spot lesions.
Limitations
Blinding was not feasible during the intervention, but the data evaluation and outcome assessment were blinded. Thus, observation and detection biases were assumed to be low. In this study, the RME appliance was cemented to the maxillary dentition with glass ionomer cement in the treatment group, and all patients were instructed about daily toothbrushing with toothpaste containing fluoride. In the control group, the areas of demineralization and the fluorescence loss were not different between the preobservation and postobservation periods statistically. It was not considered best clinical practice to totally omit the use of fluoride toothpaste in the control group.25 Fluoride toothpastes have been shown to reduce the risk of enamel demineralization.26
Generalizability
This randomized clinical trial was performed in 1 center. Although this strengthens the standardization for all steps, the generalizability of these findings is limited. CONCLUSIONS
Within the limitations of this study, the following conclusions can be drawn. 1.
2. 3.
4.
There were no statistically significant differences in demineralization (fluorescence loss) between the treatment and control groups. The areas of demineralization decreased after RME treatment with a bonded appliance. The numbers of teeth showing demineralization and remineralization increased in the treatment group compared with the control group. No significant differences were found in terms of the frequency of demineralization for each tooth.
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ACKNOWLEDGMENTS
We thank Dr Bulent Ozkan for his help with the statistical calculations. REFERENCES 1. Bishara SE, Staley RN. Maxillary expansion: clinical implications. Am J Orthod Dentofacial Orthop 1987;91:3-14. 2. Uysal M, Toygar Memikoglu U, Iseri H. Non-extraction treatment with acrylic bonded rapid maxillary appliances. Turk J Orthod 1995;8:283-90. 3. Sudjalim TR, Woods MG, Manton DJ. Prevention of white spot lesions in orthodontic practice: a contemporary review. Aust Dent J 2006;51:284-9. 4. van der Veen MH, de Josselin de Jong E. Application of quantitative light-induced fluorescence for assessing early caries lesions. Monogr Oral Sci 2000;17:144-62. 5. Bjelkhagen H, Sundstr€ om F, Angmar-M ansson B, Ryden H. Early detection of enamel caries by the luminescence excited by visible laser light. Swed Dent J 1982;6:1-7. 6. de Josselin de Jong E, Sundstr€ om F, Westerling H, Tranaeus S, ten Bosch JJ, Angmar-Mansson B. A new method for in vivo quantification of changes in initial enamel caries with laser fluorescence. Caries Res 1995;29:2-7. 7. Al-Khateeb S, Exterkate RA, Angmar-M ansson B, ten Cate JM. Light-induced fluorescence studies on dehydration of incipient enamel lesions. Caries Res 2002;36:25-30. 8. McLean JW. Glass ionomer cement. Br Dent J 1988;164:293-300. 9. Ko HY, Kang SM, Kim HE, Kwon HK, Kim BI. Validation of quantitative light-induced fluorescence-digital (QLF-D) for the detection of approximal caries in vitro. J Dent 2015;43:568-75. 10. Pretty IA, Pender N, Edgar WM, Higham SM. The in vitro detection of early enamel de- and re-mineralization adjacent to bonded orthodontic cleats using quantitative light-induced fluorescence. Eur J Orthod 2003;25:217-23. 11. Copenhaver DJ. In vitro comparison of zinc phosphate and glass ionomer cements’ ability to inhibit decalsification under orthodontic bands [abstract]. Am J Orthod 1986;89:528. 12. Fricker JP, McLachan MD. Clinical studies on glass ionomer cements. Part 2—a two year clinical study comparing glass ionomer cement with zinc phosphate cement. Aust Orthod J 1987;10:12-4. 13. McComb D, Sirisko R, Brown J. Scientific comparison of physical properties of commercial glass ionomer luting cements. J Can Dent Assn 1984;9:699-701. 14. Wilson AD. Developments in glass ionomer cements. Int J Prosthodont 1989;2:438-46. 15. Swartz ML, Phillips RW, Clark HE, Norman RD, Potter R. Fluoride distrubition in teeth using a silicate model. J Dent Res 1980;59: 1596-603. 16. Swartz ML, Phillips RW, Clark HE. Long-term F release from glass ionomer cements. J Dent Res 1984;63:158-60. 17. Cook PA, Youngson CC. A fluoride-containing composite resin—an in vitro study of a new material for orthodontic bonding. Br J Orthod 1989;16:207-12. 18. Donley KJ, Istre S, Istre T. In vitro enamel remineralization at orthodontic band margins cemented with glass ionomer cement. Am J Orthod Dentofacial Orthop 1995;107:461-4. 19. Marcusson A, Norevall LI, Persson M. White spot reduction when using glass ionomer cement for bonding in orthodontics: a longitudinal and comparative study. Eur J Orthod 1997;19:233-42. 20. Meyers MJ. Protection of enamel under orthodontic bands. Am J Orthod 1952;38:866-74.
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21. Øgaard B. Prevalence of white spot lesions in 19 year olds: a study on untreated and orthodontically treated persons 5 years after treatment. Am J Orthod Dentofacial Orthop 1989;98: 423-7. 22. Mansson A, Bosch J. Quantitative light-induced fluorescence (QLF): a method for assessment of incipient caries lesions. Dentomaxillofac Radiol 2001;30:298-307. 23. McNamara JA Jr, Brudon WL. Orthodontics and dentofacial orthopedics. Ann Arbor, Mich: Needham Press; 2001. p. 375-87.
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24. Ten Bosch JJ, Angmar-Mansson B. A review of quantitative methods for studies of mineral content of intra-oral caries lesions. J Dent Res 1991;70:2-14. 25. Br€ ochner A, Christensen C, Kristensen B, Tranaeus S, Karlsson L, Sonnesen L, et al. Treatment of post-orthodontic white spot lesions with casein phosphopeptide-stabilised amorphous calcium phosphate. Clin Oral Investig 2011;15:369-73. 26. Øgaard B. White spot lesions during orthodontic treatment: mechanisms and fluoride preventive aspects. Semin Orthod 2008;14:183-93.
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Evaluation of enamel demineralization in adolescents after rapid maxillary expansion using the quantitative light-induced fluorescence method: A single-center, randomized controlled clinical trial Asli Baysal,a Seher Nazlı Ulusoy,b and Tancan Uysalc Izmir, Turkey
Introduction: The aim of this 2-arm parallel trial was to evaluate enamel demineralization after rapid maxillary expansion (RME) compared with an untreated control group using quantitative light-induced fluorescence. Methods: Thirty-six patients who needed RME as part of their orthodontic treatment were separated randomly into either the control group or the intervention group (RME). Eligibility criteria included crossbite, no previous orthodontic treatment, no systemic disease, and all permanent teeth erupted except second and third molars. The main outcome was quantitative evaluation of demineralization, and assessment of the vulnerability of each tooth to demineralization was the secondary outcome. Randomization was made at the start of the study with preprepared random number tables. Blinding was applicable for outcome assessment only. Patients in the RME group underwent expansion with a bonded acrylic expander; patients in the control group were untreated. Records were taken using quantitative light-induced fluorescence Digital Biluminator (Inspektor Research Systems, Amsterdam, The Netherlands) in pretreatment and posttreatment observation phases. The presence and extent of lesions on the buccal surfaces of all teeth, except the second and third molars, were assessed. The fluorescence loss, lesion area, and percentage of fluorescence loss were determined using the system's software. The numbers of teeth with more than a 5% change in fluorescence loss, were calculated. Data were analyzed with Wilcoxon signed rank, Mann-Whitney U, multivariate analysis of variance, and chi-square tests (P \0.05). Risk and odds ratios were calculated. Results: A total of 36 patients were randomized to either the RME or the control group in a 1:1 ratio. This study was completed with 18 patients in the RME group (8 girls, 10 boys; mean age, 14.2 6 1.0 years) and 18 patients in the control group (10 girls, 8 boys; mean age: 14.1 6 0.8 years). All patients completed the study, and none were lost to follow-up. The area of demineralization decreased in the RME group ( 17.50 mm2), which was a significantly greater decrease than in the control group (0.00) (effect size, 2.63; mean difference, 87.94; 95% confidence interval, 223.7547.86; P 5 0.008). No statistically significant difference was found for fluorescence loss. The numbers of teeth with demineralization and remineralization were higher in the treatment group. According to the risk ratio, the difference between groups regarding demineralization was not significant. No harm was found except gingivitis associated with the bonded appliance. Conclusions: RME therapy using a bonded expander does not increase enamel demineralization. Registration: This trial was not registered. Protocol: The protocol was not published before trial commencement. (Am J Orthod Dentofacial Orthop 2016;150:731-9)
R
apid maxillary expansion (RME) is used to correct posterior crossbites, improve smile esthetics, and increase arch length and airway clearance. With
RME, the midpalatal suture is separated, cell activity increases in the suture area, and bone is gained in the transversal plane.1
From the Department of Orthodontics, Faculty of Dentistry, Izmir Katip Celebi University, Izmir, Turkey. a Associate professor. b Research assistant. c Professor. All authors have completed and submitted the ICMJE Form for Disclosure of Potential Conflicts of Interest, and none were reported. Supported by a research grant from Izmir Katip Celebi University, Scientific Research Projects Unit (project number: 2013-2–TSBP-06).
€ Address correspondence to: Asli Baysal, Izmir Katip Celebi Universitesi, Dis¸ Hekimligi Fak€ ultesi, Ortodonti A.D., Cigli, Izmir, Turkey; e-mail, baysalasli@ hotmail.com. Submitted, October 2015; revised and accepted, June 2016. 0889-5406/$36.00 Ó 2016 by the American Association of Orthodontists. All rights reserved. http://dx.doi.org/10.1016/j.ajodo.2016.06.014
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The appliances used for RME are 2 types: bonded and banded. Bonded RME appliances have been often preferred recently because the rigidity of the bonded RME appliance causes less tipping of the teeth.2 The appliance consists of a screw in the middle of the palate and an acrylic cap that covers the teeth. Because the sutural organization has been affected by RME, reorganization necessitates a long retention period.1 Wearing the appliance during the active treatment period and the retention phase makes it more difficult for patients to establish proper oral hygiene; this causes microbial plaque accumulation. For this reason, expansion seems to increase the demineralization risk.3 Demineralization results in compromised esthetics and may require invasive intervention, with additional financial, emotional, and biologic costs to patients and their families, and a frustrating clinical dilemma for orthodontists. Quantitative light-induced fluorescence (QLF) is a new technique for the detection of early mineral changes in enamel.4 The fluorescence image of enamel with early lesions can be digitized, and the fluorescence loss in the lesion can then be quantified in relation to the fluorescence radiance level of sound enamel.5,6 Recent studies indicate that QLF is suitable for in-vivo monitoring of mineral changes in early enamel lesions.4,6,7 Furthermore, the use of QLF as a method of following caries development during orthodontic treatment has been suggested for quantitative judgment of the same lesion at different times.8 Although there have been many studies in the orthodontic literature to evaluate enamel demineralization around orthodontic brackets, to our knowledge no study in the literature has evaluated the demineralization effect of RME using a bonded acrylic appliance. Because of the limited research available in this area, the aim of this study was to evaluate enamel demineralization after RME using the QLF method in vivo. Specific objectives or hypotheses
In this study, we tested the hypotheses that (1) there is no difference between RME-treated and untreated subjects regarding the amount of demineralization quantitatively, (2) the numbers of teeth showing demineralization do not differ between RME-treated and untreated subjects, and (3) there is no difference between teeth regarding their vulnerability to enamel demineralization. MATERIAL AND METHODS Trial design
This was a 2-arm parallel-group, randomized, controlled trial with a 1:1 allocation ratio.
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Participants, eligibility criteria, and settings
Approval of the medical ethical committee of Izmir Katip Celebi University, Izmir, Turkey was obtained for this study (number 64). The participants were selected from those who needed to be treated with RME and put on the waiting list of the orthodontic department's clinic. The sample comprised 36 patients. The inclusion criteria were as follows: (1) unilateral or bilateral crossbite caused by a transversal maxillary deficiency, (2) no previous orthodontic treatment, (3) no systemic disease, and (4) all permanent teeth erupted except second and third molars. Interventions
In the first group, RME was applied until the palatal cusps of the maxillary molars and the buccal cusps of the mandibular molars were in the same plane transversally. The patients in the control group were not treated in the first phase, and the observation period was 6 months. During the observation period, interceptive treatments were performed in the control group; immediately after that, their orthodontic treatment was initiated. This study was completed with 18 patients in the treatment group (8 girls, 10 boys; mean age, 14.2 6 1.0 years) and 18 patients in the control group (10 girls, 8 boys; mean age, 14.1 6 0.8 years). The flow of the patients through the trial is shown in Figure 1. Orthopedic expansion was performed with a bonded type of RME appliance (Fig 2). A hyrax screw (Dentaurum, Pforzheim, Germany) was placed between the second premolars. The palate was covered with acrylic, which extended to the occlusal and middle thirds of the buccal surfaces of the teeth. This appliance was bonded to the maxillary dentition with glass ionomer cement (Ketac Cem Radiopaque; 3M ESPE Dental Products, Neuss, Germany). The screw activation was a quarter turn twice for the first week and a quarter turn per day after that. When the desired amount of expansion was achieved, the screw was stabilized with a ligature wire and kept in the mouth passively for a month. The patients were instructed to wear a Hawley appliance for the rest of their retention period. At 6 months, the QLF recordings were performed in treatment and control groups. Records were taken using a QLF Digital Biluminator (QLF-D, Inspektor Pro; Inspektor Research Systems, Amsterdam, The Netherlands) in the pretreatment and posttreatment observation phases. The QLF-D is an upgraded version of the first product with a modified filter set (D007; Inspektor Research Systems).9 The system consisted of a special camera connected to a personal computer in which the QLF-D software was installed. Camera settings were optimized for the environment where the photos were taken, and fixed settings
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Fig 1. Flow of patients through the trial.
Fig 2. RME appliance used in the study.
(ISO, 1600; shutter speed, 1/30 second) were then locked in the software. The camera was used with a manual focus at the canines for the front teeth and at the second premolars for the posterior teeth. To ensure standardization, the images were captured with the same camera position and from the same angle. The images were processed with the software using video-repositioning techniques according to the manufacturer's instructions.
using the QLF method. The secondary outcome measures were the assessment of enamel demineralization of individual teeth and the determination of whether any tooth is more vulnerable to demineralization. The presence and extent of lesions on the buccal surfaces of all teeth, except second and third molars, were assessed by the QLF-D software at the pretreatment observation visit and the posttreatment observation visit. Thus, 12 buccal surfaces per subject were assessed at each time point. The analysis of the images involved the placement of an analysis patch in the stained area, ensuring that the borders of the patch fell on sound enamel. The average fluorescence loss, lesion area, and the percentage of fluorescence loss were determined using the system's analysis software to determine the lesion extent. The decrease in fluorescence was determined by calculating the percentage difference between the actual and reconstructed fluorescence surfaces. A threshold value was set at a level of 5% fluorescence loss, which showed a minimum 5% fluorescence loss change between first and second measurements.10 The lesions captured by the QLF-D clinical system were analyzed quantitatively with the QLF-D software. No changes to the methods or no outcome changes were occurred after trial commencement.
Outcomes (primary and secondary) and any changes after trial commencement
Sample size calculation
The primary outcome in this investigation was the quantitative evaluation of enamel demineralization
A multivariate analysis of variance with 2 outcome variables and 1 factor with 2 levels indicated at least
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80% statistical power based on a medium effect size, Cohen's d 5 0.66, (refer to effect size reported in a similar study: Al-Khateeb S, Forsberg CM, de Josselin de Jong E, Angmar-Mansson B. A longitudinal laser fluorescence study of white spot lesions in orthodontic patients. Am J Orthod Dentofacial Orthop 1998;113:595-602; mean difference, 4.02; SD, 3.59) necessitated a minimum sample size of 18 in each group to detect a significant difference between the groups. Interim analyses and stopping guidelines
Not applicable. Randomization (random number generation, allocation concealment, and implementation of the random sequence)
When a patient who fulfilled the inclusion criteria attended the clinic, the patient and parents were informed and invited to participate in the study. If the child and the parents consented, the initial records were taken, and each patient was randomized to receive treatment with a rapid palatal expander or to have treatment delayed for at least 6 months. Randomization was done at the start of the study with random number tables prepared using SPSS software (version 20.0; IBM, Armonk, NY). One researcher (S.N.U.) evaluated the patients, and another author (A.B.) enrolled the patients. The allocation sequence was concealed using numbered and sealed opaque envelopes. Thirtysix patients (mean age, 14.1 6 0.8 years; range, 11.416.5 years) were randomized in a 1:1 ratio to either the treatment or the control group.
Table I. Demographic and clinical characteristics of
participants
Age (y), mean 6 SD Boys (n) Girls (n) Malocclusion (n) Class I Class II Class III White spot lesions (n), mean 6 SD
Treatment group 14.2 6 1.0 10 8
Control group 14.1 6 0.8 8 10
Total 14.1 6 0.8 18 18
4 10 4 3.22 6 2.75
2 11 5 1.33 6 1.91
6 21 9 2.28 6 2.52
The normality test of Shapiro-Wilks and the Levene variance homogeneity test were applied to the data. The data were not normally distributed; thus, nonparametric tests were used. Fluorescence losses and areas of demineralization change were evaluated using MannWhitney U and Wilcoxon signed rank tests for intergroup and intragroup comparisons, respectively. Risk ratios and odds ratios were carried out with statistical methods for new lesion development and lesion remineralization. Confidence intervals (95% CI) were also calculated for relative risks. To compare the percentages of samples that exceeded the 5% fluorescence loss threshold limit in each group, the chi-square test was used. One-way analysis of variance was used to test the differences of fluorescence loss values of each tooth. Statistical significance was set at P #0.05. RESULTS Participent flow
Blinding
Blinding of either patient or operator was not possible. Statistical analysis (primary and secondary outcomes, subgroup analyses)
The data acquired were analyzed statistically to evaluate the possible changes between the treated and control groups. All data were entered into SPSS software for the statistical analysis. To evaluate the cluster effect, the intracluster correlation coefficients (ICC) were calculated for each dependent variable. The ICC values ranged between 9% and 23%, indicating a clustering effect. Although the mixed model takes care of the cluster effect, nonnormal data causes the parametric model to be unreliable. Thus, patient was chosen for unit of analysis instead of the tooth; the mean value per patient was obtained, and these data were analyzed at the patient level.
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This study was completed with 18 patients in the treatment group (8 girls, 10 boys; mean age, 14.2 6 1.0 years) and 18 patients in the control group (10 girls, 8 boys; mean age, 14.1 6 0.8 years). A total of 432 teeth (216 in each group) were evaluated. The analyses were carried out in all patients. Losses and exclusions after randomization
The treatments and observations of all patients were completed without dropouts. Baseline data
The baseline demographic and clinical characteristics of the patients are given in Table I. Follow-up period
The follow-up period for both groups was 6 months.
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American Journal of Orthodontics and Dentofacial Orthopedics
2.192 1.447 2.637 Different superscript letters denote statistically significant differences between 2 medians at the 0.05 level. MD, Mean of differences; ES, effect size 5 Z value; P \0.05; T0, pretreatment or first observation visit; T1, posttreatment or second observation visit; NS, nonsignificant.
0.031 NS 0.008 64.97 54.03 47.86 9.37 5.65 223.75 37.17 29.84 87.94 10.90 10.88 98.28 7.81 9.04 14.66 29.83 30.92 202.00 0.00 0.00 259.00 0.21 3.54 0.00 NS 57.00 49.31 265.93 173.50 161.42 739.00
44.98 38.88 73.27
0.011 NS NS 0.67 0.27 1.63 3.83 3.23 0.63 2.25 1.74 0.49
0.00 0.00 610
Median SD Mean RME group (n 5 18)
Table III. Descriptive statistics and intragroup and intergroup comparisons
To present the cluster effect, ICC values were calculated for each dependent variable (Table II). The results of the descriptive statistics and intragroup and intergroup comparisons of the mean changes between pretreatment and posttreatment are given in Table III. Pretreatment fluorescence loss greater for the RME group, and the difference between groups was statistically significant (P 5 0.011). After treatment, there was no statistically significant difference between the groups. The area of demineralization was greater in the RME group before treatment (P 5 0.031). After treatment, the areas of demineralization increased in the control group and decreased in the RME group. Although the posttreatment values were comparable, the changes in demineralization areas between time points (treatment effects) were statistically significant between the groups (P 5 0.008). As assessed by the QLF-D, the lesions on the 432 buccal surfaces of the teeth, except for the second and third molars, were evaluated. In the treatment group, 58 lesions at pretreatment and 49 lesions at posttreatment were detected. In the control group, 24 lesions at the first observation and 26 lesions at the second observation were found. In the treatment group, 16 lesions had disappeared, and 6 lesions had developed in the posttreatment period. In the control group, 6 lesions had disappeared, and 6 had developed. The risk ratio was 1.0 (95% CI, 0.317-3.151). The groups were comparable for new lesion development. The odds ratio was 2.8 (95% CI, 1.07-7.29). Thus, the treatment group had
Control group (n 5 18)
Numbers analyzed for each outcome, estimation and precision, and subgroup analyses
1.06 0.96 0.60
T0, Pretreatment or first observation visit; T1, posttreatment or second observation visit.
0.74 0.83 0.87
0.225
0.00 0.00 1.32
1.47
3.9 3.75 1.09
11
0.23 0.55 0.00 NS
5046.91
3.12 2.94 2.28
5045
2.99 2.58 0.40
0.998
Significance
0.28
Upper
12
Lower
2320.36
MD
2327.96
SD
0.999
Mean
14.63
Maximum
10
Minimum
5097.7
Maximum
5115.23
Minimum
P 0.948 0.996 1
Median Fluorescence loss Pretreatment 1.14 Posttreatment 1.66 Difference (T1-T0) 0.00 Significance NS Area of demineralization Pretreatment 12.07a Posttreatment 17.36b Difference (T1-T0) 17.50 Significance 0.023
Random Random intercept 1 ICC intercept slope (%) F 2489.35 2475.55 23 21.73 2588.22 2576.54 15 18.03 5300.5 5281.28 9 14.57
95% CI
Dependent variables T0 fluorescence loss T1 fluorescence loss T0 demineralization area T1 demineralization area T1-T0 fuorescence loss T1-T0 demineralization area
Intergroup comparison
Type III fixed effects
AIC
0.00 0.66 8.39
intercept plus slope models
10.43 10.6 2.13
ES
Table II. Results of random intercept and random
2.564 1.862 0.683
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Table IV. Comparisons of the groups for numbers of
teeth in the different categories Change 0, no change
Distribution Count % in group 1, fluorescence loss Count (T0-T1) decrease % in group 2, fluorescence loss Count (T0-T1) increase % in group Total Count % in group
Treatment Control group group 152a 186b 70.4% 86.1% 36a 15b 16.7% 28a 13.0% 216 100.0%
6.9% 15b
Total 338 78.2% 51 11.8% 43
6.9% 10.0% 216 432 100.0% 100.0%
Each subscript letter denotes a subset of group categories whose column proportions do not differ significantly from each other at the 0.05 level.
a 2.8-fold remineralizing ratio compared with the control group. The groups were further analyzed for demineralization, with a 5% fluorescence loss change as the threshold limit between the first and second records (Table IV). Three categories were generated as “no change,” “demineralization,” and “remineralization.” If the change did not reach the 5% threshold limit, the teeth were categorized as “no change.” When the change exceeded the threshold limit and the fluorescence loss increased from the first to the second observation, the teeth were recorded in the demineralization category. In the opposite situation, teeth were recorded in the remineralization category. According to the results of the chi-square test, statistically significant differences were found between the groups for all categories (Table IV). No changes were found for 152 of the 216 teeth (70.4%) in the treatment group and 186 of the 216 teeth (86.1%) in the control group. In the treatment group, demineralization was seen in 13.0% of the teeth, and remineralization was recorded in 16.7% of the teeth. These ratios were 6.9% for both categories in the control group. The mean fluorescence loss differences between the 2 observations for each tooth are shown in Figure 3. No statistically significant differences were found between the mean fluorescence loss values of each tooth. The maximum mean fluorescence loss differences were found in the maxillary right lateral incisors and canines, and the maxillary left canines. Harms
No serious harm was observed in the treatment group other than gingivitis associated with the difficulty of plaque removal.
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DISCUSSION Main findings in the context of the existing evidence and interpretation
The purpose of this study was to evaluate tooth demineralization after bonded RME using the QLF method. According to our results, no difference was found between groups regarding demineralization (by means of fluorescence loss). Moreover, the areas of demineralization showed greater improvements (reductions) in the treatment group after 6 months of retention. This finding should be interpreted cautiously because the reduction in the surface area may not mean regression of demineralization. The depth of the lesion may be increasing, while the area is getting smaller. On the other hand, the numbers of teeth in the demineralization and remineralization categories in the treatment group were greater than in the control group. When these factors are taken into account, it is hard to conclude that the changes in the treatment group are solely in the trend of demineralization or remineralization. The greater improvement in the treatment group may be explained in 2 ways. Because the initial demineralization was higher, greater remineralization might have been seen in treatment group. The second factor may be the use of glass ionomer cement for expander cementation. The remineralization potential of the lesions may be improved with glass ionomer cement. Previous studies have indicated that the formation of white spot lesions decreased when orthodontic bands were cemented with glass ionomer cement.11,12 The major favorable feature of glass ionomer cement is the ability to act as a fluoride ion reservoir; therefore, the demineralization risk is decreased.8,13,14 The release of fluoride ions from glass ionomer cement has been shown to inhibit demineralization.15 The researchers showed that ion release begins with mixing glass ionomer cement and the effect remains for about 12 months at a certain level.15-17 Glass ionomer cement not only inhibits demineralization but also demonstrates the ability to remineralize enamel.18 The reduction in white spot lesion formation with glass ionomer cement for bonding in orthodontics can be significant, with an average reduction of 16.5% having been achieved when compared with the use of composite resin cements in a longitudinal study of 60 patients.19 In our study, 16 lesions disappeared, and 6 lesions developed in the treatment group, while 6 lesions were lost, and 6 lesions developed in the postobservation period of the control group. The risk of developing new white spot lesions was comparable between groups (risk ratio 5 1) whereas remineralized lesions were greater in the treatment group (odds ratio 5 2.8). This finding and the disappearance of 16 lesions from the
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Fig 3. Mean fluorescence loss differences between the 2 observations for each tooth. T0, Pretreatment or first observation visit; T1, posttreatment or second observation visit.
treatment group may be the result of the properties of glass ionomer cement. According to epidemiologic studies, maxillary lateral incisors and mandibular first molars have the highest frequencies of white spot lesions.20,21 Mandibular second premolars and maxillary canines are also commonly affected.20,21 According to our results, no significant differences were found between the mean fluorescence loss differences of each tooth. However, the maximum mean fluorescence loss differences were found in the maxillary right lateral incisors and canines, and the left canines. Orthodontists should keep in mind this information during treatment, since the demineralization of anterior teeth more seriously affects a patient's esthetics compared with posterior teeth. New methods for early caries diagnosis have been developed to detect lesions in the early stages before cavitation occurs and restoration is needed.20 This diagnosis is predominantly based on subjective interpretation of visual information: visual inspection, bitewing radiography, fibre-optic transillumination, and transverse microradiography.21 These methods are objective and quantitative, allowing longitudinal monitoring over time of lesion progression. We used QLF, which has been shown to be a precise tool to detect demineralization.21 The best approach to fight enamel demineralization is to prevent white spot lesions.22 There is no way to detect incipient white spot lesions because the RME
appliance covers the teeth. Enamel demineralization was reported to occur over 9 months with bonded RME appliances.23 Therefore, it may be useful not to have a long RME treatment. The gold standard technique for quantifying changes in mineral content of early carious lesions is transverse microradiography.24 However, this technique requires preparation of thin tooth sections and, therefore, cannot be used to monitor white spot lesions undergoing treatment in vivo. It was concluded that QLF-D is suitable for in-vivo longitudinal studies.6,7 The QLF method shows excellent in-vivo repeatability and reproducibility, and could monitor the mineral changes in early enamel lesions and might be useful for clinical trials.6,7,23 Progression, regression, or stability of lesions can now be assessed when a white spot lesion is barely seen, whereas traditional methods show only absence, presence, and type of lesions.22 The disadvantages of this technology are that it is expensive, requires more space in the dental operatory, and requires special technical training for the operator to obtain reliable results. Even though many studies in the literature have used QLF to evaluate demineralization quantitatively, few studies have been performed with QLF-D. In our in-vivo study, QLF was able to detect and longitudinally monitor the demineralization of teeth after bonded RME therapy. On the other hand, some QLF images had to be omitted because of technical errors
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such as dark images, out-of-focus images, or angulation errors. These drawbacks were overcome by taking 2 images for each projection. We were trained before the study, when representative before and after images of patients were sent to the manufacturer, and we received positive feedback regarding the quality of the images. The general expectation of new white spot lesion formation after RME appliance removal was not observed in this study. The use of glass ionomer cement for RME cementation may reduce the occurrence and severity of white spot lesions.
Limitations
Blinding was not feasible during the intervention, but the data evaluation and outcome assessment were blinded. Thus, observation and detection biases were assumed to be low. In this study, the RME appliance was cemented to the maxillary dentition with glass ionomer cement in the treatment group, and all patients were instructed about daily toothbrushing with toothpaste containing fluoride. In the control group, the areas of demineralization and the fluorescence loss were not different between the preobservation and postobservation periods statistically. It was not considered best clinical practice to totally omit the use of fluoride toothpaste in the control group.25 Fluoride toothpastes have been shown to reduce the risk of enamel demineralization.26
Generalizability
This randomized clinical trial was performed in 1 center. Although this strengthens the standardization for all steps, the generalizability of these findings is limited. CONCLUSIONS
Within the limitations of this study, the following conclusions can be drawn. 1.
2. 3.
4.
There were no statistically significant differences in demineralization (fluorescence loss) between the treatment and control groups. The areas of demineralization decreased after RME treatment with a bonded appliance. The numbers of teeth showing demineralization and remineralization increased in the treatment group compared with the control group. No significant differences were found in terms of the frequency of demineralization for each tooth.
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ACKNOWLEDGMENTS
We thank Dr Bulent Ozkan for his help with the statistical calculations. REFERENCES 1. Bishara SE, Staley RN. Maxillary expansion: clinical implications. Am J Orthod Dentofacial Orthop 1987;91:3-14. 2. Uysal M, Toygar Memikoglu U, Iseri H. Non-extraction treatment with acrylic bonded rapid maxillary appliances. Turk J Orthod 1995;8:283-90. 3. Sudjalim TR, Woods MG, Manton DJ. Prevention of white spot lesions in orthodontic practice: a contemporary review. Aust Dent J 2006;51:284-9. 4. van der Veen MH, de Josselin de Jong E. Application of quantitative light-induced fluorescence for assessing early caries lesions. Monogr Oral Sci 2000;17:144-62. 5. Bjelkhagen H, Sundstr€ om F, Angmar-M ansson B, Ryden H. Early detection of enamel caries by the luminescence excited by visible laser light. Swed Dent J 1982;6:1-7. 6. de Josselin de Jong E, Sundstr€ om F, Westerling H, Tranaeus S, ten Bosch JJ, Angmar-Mansson B. A new method for in vivo quantification of changes in initial enamel caries with laser fluorescence. Caries Res 1995;29:2-7. 7. Al-Khateeb S, Exterkate RA, Angmar-M ansson B, ten Cate JM. Light-induced fluorescence studies on dehydration of incipient enamel lesions. Caries Res 2002;36:25-30. 8. McLean JW. Glass ionomer cement. Br Dent J 1988;164:293-300. 9. Ko HY, Kang SM, Kim HE, Kwon HK, Kim BI. Validation of quantitative light-induced fluorescence-digital (QLF-D) for the detection of approximal caries in vitro. J Dent 2015;43:568-75. 10. Pretty IA, Pender N, Edgar WM, Higham SM. The in vitro detection of early enamel de- and re-mineralization adjacent to bonded orthodontic cleats using quantitative light-induced fluorescence. Eur J Orthod 2003;25:217-23. 11. Copenhaver DJ. In vitro comparison of zinc phosphate and glass ionomer cements’ ability to inhibit decalsification under orthodontic bands [abstract]. Am J Orthod 1986;89:528. 12. Fricker JP, McLachan MD. Clinical studies on glass ionomer cements. Part 2—a two year clinical study comparing glass ionomer cement with zinc phosphate cement. Aust Orthod J 1987;10:12-4. 13. McComb D, Sirisko R, Brown J. Scientific comparison of physical properties of commercial glass ionomer luting cements. J Can Dent Assn 1984;9:699-701. 14. Wilson AD. Developments in glass ionomer cements. Int J Prosthodont 1989;2:438-46. 15. Swartz ML, Phillips RW, Clark HE, Norman RD, Potter R. Fluoride distrubition in teeth using a silicate model. J Dent Res 1980;59: 1596-603. 16. Swartz ML, Phillips RW, Clark HE. Long-term F release from glass ionomer cements. J Dent Res 1984;63:158-60. 17. Cook PA, Youngson CC. A fluoride-containing composite resin—an in vitro study of a new material for orthodontic bonding. Br J Orthod 1989;16:207-12. 18. Donley KJ, Istre S, Istre T. In vitro enamel remineralization at orthodontic band margins cemented with glass ionomer cement. Am J Orthod Dentofacial Orthop 1995;107:461-4. 19. Marcusson A, Norevall LI, Persson M. White spot reduction when using glass ionomer cement for bonding in orthodontics: a longitudinal and comparative study. Eur J Orthod 1997;19:233-42. 20. Meyers MJ. Protection of enamel under orthodontic bands. Am J Orthod 1952;38:866-74.
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21. Øgaard B. Prevalence of white spot lesions in 19 year olds: a study on untreated and orthodontically treated persons 5 years after treatment. Am J Orthod Dentofacial Orthop 1989;98: 423-7. 22. Mansson A, Bosch J. Quantitative light-induced fluorescence (QLF): a method for assessment of incipient caries lesions. Dentomaxillofac Radiol 2001;30:298-307. 23. McNamara JA Jr, Brudon WL. Orthodontics and dentofacial orthopedics. Ann Arbor, Mich: Needham Press; 2001. p. 375-87.
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24. Ten Bosch JJ, Angmar-Mansson B. A review of quantitative methods for studies of mineral content of intra-oral caries lesions. J Dent Res 1991;70:2-14. 25. Br€ ochner A, Christensen C, Kristensen B, Tranaeus S, Karlsson L, Sonnesen L, et al. Treatment of post-orthodontic white spot lesions with casein phosphopeptide-stabilised amorphous calcium phosphate. Clin Oral Investig 2011;15:369-73. 26. Øgaard B. White spot lesions during orthodontic treatment: mechanisms and fluoride preventive aspects. Semin Orthod 2008;14:183-93.
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