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 Table of Contents  
ORIGINAL ARTICLE
Year : 2016  |  Volume : 14  |  Issue : 1  |  Page : 4-9

Comparison of effectiveness of traditional acid etching and of the self-etching agent in sealant retention: A randomized controlled trial


1 Department of Public Health Dentistry, Yenepoya Dental College, Mangalore, Karnataka, India
2 Department of Public Health Dentistry, The Oxford Dental College, Bengaluru, Karnataka, India
3 Department of Oral Medicine and Radiology, Yenepoya Dental College, Mangalore, India

Date of Web Publication15-Mar-2016

Correspondence Address:
Imran Pasha Mohammed
Department of Public Health Dentistry, Yenepoya Dental College, Mangalore, Karnataka
India
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Source of Support: None, Conflict of Interest: None


DOI: 10.4103/2319-5932.178719

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  Abstract 

Introduction: The caries-preventive effect of pit and fissure sealants was demonstrated in the 1970s and the 1980s with randomized clinical trials using parallel groups or split-mouth designs. In new self-etching (SE) adhesive systems, rinsing and drying steps are eliminated which have made etching easier and have resulted in more patient acceptability. Aim: To evaluate sealant retention, following application of SE adhesive and traditional acid etching (TAE) were carried out among 6–13 years old schoolchildren in Bengaluru city. Materials and Methods: Lower first molars were allotted to either SE adhesive group or TAE group based on lottery method, using a split-mouth technique. The sealants were evaluated for the retention based on modified color coverage caries criteria at the end of 6-month interval by a blinded examiner. Data were analyzed using Wilcoxon tests (P < 0.05). Results: No statistically significant difference was seen in the retention of fissure sealants placed on occlusal surfaces following the use of an SE bonding agent and traditional phosphoric acid etching technique, after 6 months. Conclusions: SE adhesive used for sealing permanent molars of young children for a limited period, should be reviewed every 6 months.

Keywords: Bonding agent, effectiveness, pit and fissure sealants, retention


How to cite this article:
Mohammed IP, Jaleel BF, Hiremath S S, Manjunath C, Amarah U, Krishnamoorthy A. Comparison of effectiveness of traditional acid etching and of the self-etching agent in sealant retention: A randomized controlled trial. J Indian Assoc Public Health Dent 2016;14:4-9

How to cite this URL:
Mohammed IP, Jaleel BF, Hiremath S S, Manjunath C, Amarah U, Krishnamoorthy A. Comparison of effectiveness of traditional acid etching and of the self-etching agent in sealant retention: A randomized controlled trial. J Indian Assoc Public Health Dent [serial online] 2016 [cited 2024 Mar 29];14:4-9. Available from: https://journals.lww.com/aphd/pages/default.aspx/text.asp?2016/14/1/4/178719


  Introduction Top


The caries-preventive effect of pit and fissure sealants was demonstrated in the 1970s and the 1980s with randomized clinical trials using parallel groups or split-mouth designs.[1] According to Ripa, the occlusal surface of a tooth represents 12.5% of the total surface of a permanent tooth but accounts for nearly 50% of caries in schoolchildren.[2] Dental caries in schoolchildren is a disease of the pits and fissures with 83% or more of caries found in these areas. The development of caries on occlusal surfaces of both primary and permanent dentitions soon after eruption indicated the need for early intervention, i.e., pit and fissure sealant application.[3] The American Dental Association expert panel concluded, based on all the evidence reviewed and presented, that reduction of caries incidence in children and adolescents after placement of resin-based sealants ranged from 86% at 1 year to 78.6% at 2 years and 58.6% at 4 years.[4]

Innovations in prevention of fissure caries continue today, with new materials and technologies being tested.[5] Preventive measures such as control of bacterial plaque and topical applications of fluoride solutions have little effect on fissure surfaces.[6] More effective measures, therefore, are necessary, such as the application of occlusal sealants.[7] Dental sealants can be an effective preventive measure against pit and fissure decay. When sealants placed with care and then routinely maintained, they represent an exceptional preventive service.[8] Increasing sealant retention is the key to caries prevention.

Bonding agents have been recommended to increase sealant retention.[9] A clinical study of sealant retention on salivary contaminated-etched enamel showed that sealant retention improved with inclusion of a bonding agent between contaminated-etched enamel and sealant resin.[10] A study by Bottenberg etal. stated that none of the tested commercially available etchants were able to penetrate farther than 17% of the total fissure depth in a fissure model.[11] Therefore, the use of self-etching (SE) adhesive systems may be a valid and promising alternative to acid etching with phosphoric acid. These new SE adhesive systems are user-friendly since the enamel/dentin acid etching; rinsing and drying steps are eliminated. Having less operative steps and a shorter chair time is particularly interesting when treating pediatric patients.[12] The aim of this study was to compare the clinical effectiveness of an SE agent (7th generation bonding agent) with conventional acid-etch technique for enamel preparation before sealant placement. The specific research question was: Is there a difference between the two techniques with regard to retention of fissure sealant following its placement on the occlusal surfaces of permanent molar teeth?


  Materials and Methods Top


The study was conducted at The Oxford Dental College, Bengaluru. Ethical clearance for the present study was obtained from the Institutional Review Board and written informed consent for the involvement in the trial was obtained from the parents; the consent of each subject was also obtained. Intraexaminer reproducibility was calculated by re-examination of ten subjects by the principal investigator at subsequent appointments and these subjects were not included in the main study.

Based on the review of literature of the previous articles, the retention rate for traditional acid etching (TAE) was 90% and SE was 67%; a sample of 12 children was derived.[13],[14] However, the sample size has been increased to 30 children keeping in view of attrition. Children having sound permanent first molars or second molars were included in the study, and children who were felt not cooperative were excluded from the study.

A total of 120 children were screened by the investigator and 80 subjects fulfilled the eligibility criteria for the study; the list of these student names was tabulated and using computer-generated table of random numbers, 30 subjects were selected randomly. A split-mouth study design was used. The techniques (SE and TAE) used for enamel preparation prior to sealant placement on the right and left side of the lower arch were randomized using the lottery method fish bowl technique by the investigator (allocation ratio 1:1).

A single operator carried out scaling procedures for each child, followed by prophylaxis using slurry of pumice and a rotating brush to ensure removal of debris from the fissures before sealant application for both SE adhesive and traditional phosphoric acid etching (PAE) groups.[15]

In the SE adhesive group (SE) (7th generation bonding agent), SE liquid was applied to the occlusal surface of the molar tooth, left for 20 s, air-dried using a 3-in-1 tip, and light cured for 10 s. Delton ® opaque light-curing fissure sealant was applied to fissures and cured for 20 s.

In the PAE group, phosphoric acid 35% was applied to molar occlusal surfaces in the usual manner and left for 20 s for etching to occur. Teeth were rinsed with water for 20 s and then air-dried using a 3-in-1 tip. Delton ® (Dentsply, Tulsa, OK, USA) opaque light-curing fissure sealant was applied to fissures and cured for 20 s.

Isolation of the permanent first molars was done using the cotton rolls.[15] Starlight Pro (Mectron s.p.a.) cordless LED curing lamp was used in this study for both SE and PAE groups. Sealed area was evaluated with an explorer for complete coverage and retention by the supervising staff. Occlusion was checked with articulating paper and adjusted if necessary with a finishing bur.

Questionnaires were given to the study subjects, immediately following the placement of fissure sealants to score ease of placement by both techniques, using a visual analog scale (VAS). The mean time used in applying the pit and fissure sealants using both the techniques was assessed by a stopwatch. Evaluation of the pit and fissure sealants was done at the end of 6 months by an investigator who was blinded for the method of application of the sealant using the modified color coverage caries (CCC) criteria by Burbridge et al. [Table 1].[13]
Table 1: Summary of color coverage caries sealant evaluation system criteria

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Data collected in this investigation were analyzed using the SPSS statistical computer program (SPSS version 14, Statistical Software). The retention sealants and caries scores were analyzed by Wilcoxon test as these were in the ordinal scale. The mean time taken for sealant and ease of placements as assessed by subjects was analyzed using t-test.


  Results Top


The participant flow diagram is shown in [Figure 1].
Figure 1: Participant flow diagram

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Of the 30 subjects recruited to this study, the mean age of subjects was 9·3 years (range = 7–13 years), 16 (53.3%) subjects were belonging to 8 years, 5 (16.7%) were belonging to 9–12 years, 3 (10%) were belonging to 13 years, and one subject (3.3%) was belonging to 7 years. Mean decayed missing filled teeth/decayed missing filled surfaces (dmft/dmfs) scores of the study subjects at baseline were 1.03 and 1.70, respectively. Mean DMFT/DMFS scores of the study subjects at baseline were 0.27 and 0.27, respectively.

The fissure sealants placed in the TAE group in the lower permanent molar teeth (n = 30 teeth); score A (complete sealant coverage) was recorded for 20 (66.7%) teeth, score B (sealant present on >50% of fissure system) for 7 of (23.3%) teeth, score C (sealant present on <50% of fissure system) for one (3.3%) tooth, and score D (no sealant present) for 2 (6.7%) teeth at 6-month follow-up visit. In the same group, on the whole, 27 (90%) teeth were given together A and B sealant coverage score.

The fissure sealants placed in the SE group in the lower permanent molar teeth (n = 30 teeth); score A (complete sealant coverage) was recorded for 20 (66.7%) teeth, score B (sealant present on >50% of fissure system) for 5 (16.7%) teeth, score C (sealant present on <50% of fissure system) for 2 (6.7%) teeth, and score D (no sealant present) for 3 (10%) teeth at 6-month follow-up visit. In the same group, on the whole, 25 (83.4%) teeth were given together A and B sealant coverage score.

There was no statistically significant difference between the two groups at 6 months (P = 0.083) [Table 2].
Table 2: Distribution of teeth according to sealant coverage scores over 6 months, using two etching techniques

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Caries scores in the CCC criteria were as follows: Score 0 (surface sound, no caries) was recorded for 27 (90%) teeth, score 1W (initial enamel caries-white spot lesion) for 2 (6.7%) teeth, score IB (initial enamel caries-brown spot lesion) for 1 (3.3%) tooth at 6-month follow-up visit for the TAE group, whereas score 0 (surface sound, no caries) was recorded for 24 (80%) teeth, score 1W (initial enamel caries-white spot lesion) for 5 (16.7%) teeth, score IB (initial enamel caries-brown spot lesion) for 1 (3.3%) tooth at 6-month follow-up visit for the SE group.

No statistically significant difference was seen in decay levels between those surfaces sealed with control or test group at the 6 months follow-up visit (P = 0.358) [Table 3].
Table 3: Distribution of teeth according to caries scores over 6 months, using two etching techniques

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Mean VAS score as assessed by subjects was 4.63 ± 2.48 and 1.27 ± 1.17 for the TAE and SE procedures, respectively [Figure 2]. Statistically significant differences (P = 0.000) were seen between the ease of placement by SE and TAE procedures.
Figure 2: Ease of placement of sealant assessed by subjects using visual analog scale

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The mean time taken for the TAE and SE procedures from the time of isolation to completion was 3.27 min (3.27 ± 0.277) and 2.12 min (2.12 ± 0.218), respectively [Figure 3]. Statistically significant differences (P = 0.000) were seen between the mean time taken for SE and TAE procedures.
Figure 3: Mean time taken for traditional etch and self-etch procedures

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  Discussion Top


This clinical study evaluated the sealant retention following application of SE adhesive and TAE among 6–13 years old schoolchildren in Bengaluru city. Effectiveness was measured using sealant retention. A systematic review of retention of resin-based fissure sealants by Muller-Bolla et al., 2006, concluded that it is still necessary to carry out well-designed randomized clinical trials focused on sealant retention considering different clinical procedures, particularly new enamel preparation techniques. This study adds to the evidence regarding enamel preparation using SE adhesives.[1]

Limited use of sealants has been attributed to lack of confidence in their adhesion to enamel and to the difficulty in achieving adequate salivary control and dry field isolation.[16] The benefits of adding a bonding agent layer between the etched enamel and the sealant to increase the bond strength in case of moisture and salivary contamination have been demonstrated.[17],[18] Other studies have found that the use of bonding agents beneath sealants placed on saliva-contaminated enamel can reduce microleakage.[19] The literature is still scarce in studies investigating the use of SE adhesives systems before sealant placement, and the existing works have shown controversial results.[9],[13],[14],[20],[21],[22],[23]

Mean age group in this study was 9.8 years which was similar to a study done by Mascarenhas et al.[9] and Burbridge et al.[13] The mean DMFT/DMFS and dmft/dmfs scores at baseline in this study were 0.27 and 0.27 and 1.03 and 1.70 in the permanent and deciduous teeth, respectively. This is relatively less when compared to Burbridge et al. study which reported it to be 3.27.[13] The 27 (90%) teeth of TAE group and 25 (86.7%) teeth of SE group were given a sealant coverage score of A and B at the end of 6 months. This is similar to that seen in other sealant studies [9],[21] which reported 88% of sealant retention for TAE and 79% of sealant retention for SE group. Further, dos Santos et al. showed that penetration (tags) of adhesive materials into enamel was greater when applied on enamel etched with phosphoric acid compared with an SE adhesive.[24] This could explain the higher retention rates seen in the TAE group compared to the SE group. It is now recognized that sealants require regular maintenance and repair or replacement to assure success in caries prevention.

No significant differences were seen in sealant retention in sealants placed by TAE and SE. These findings are comparable with those performed by Boksman et al. that showed no differences in sealant retention rates when Scotch Bond 2 and Universal Bond were used,[25] also Pinar et al. when one coat bond was used,[21] and Peng et al. in their study of Adper prompt SE adhesive and PAE system also reported no significant differences between the two groups at 12 months.[22] These results are in contrast to the studies by Feigal et al., who reported increased sealant retention in teeth sealed using a primer and bond.[20],[26]

Sealant score D (no sealant present), were more likely to be recorded in the SE group at 6 months (10%), when compared to the TAE group (6.7%) refl ecting that sealants were more likely to have been lost when Self etching system had been used. These findings are comparable with those performed by Burbridge et al.[13] and Salem et al.[27]

This study also found no differences in caries scores in teeth sealed with TAE and SE at 6 months (P < 0.36). Subjects of the SE group were more likely to show early enamel caries than those in the TAE group. This result can be explained by the sealants being significantly more likely to be lost in the SE group and the pit-and-fissure system no longer being protected by the sealant. This is similar to one reported by Burbridge et al. at 12-month follow-up [28] and in contrast to one reported by Salem et al.[27] Yazici et al. reported in his study that there was no new caries formation throughout the 24-month recall period.[29]

Mean VAS score was lesser in the SE (1.27 ± 1.17) group when compared to the TAE (4.63 ± 2.48) group. This is in contrast to Burbridge et al. study which reported low mean scores for both the groups.[13],[28] SE adhesives are the latest generation of enamel and dentin bonding materials. These products combine acid etch primer and adhesive in one solution to offer a simplification of the bonding procedure by eliminating the rinsing step. This shortens treatment time and reduces treatment complexity. Hence, lower mean scores reported by most of the subjects in this study.

The operating time using SE system was 2.12 ± 0.21 min, which was shorter than 3.27 ± 0.27 using TAE. These results are comparable to the one reported by Peng et al., who reported operating time using SE system was 122 ± 13 s, shorter than 219 ± 13 s using phosphate acid system [22] and Feigal and Quelhas reported much lesser time for the treatment time for SE which is 1.8 min compared to 3.1 min for traditional etching when compared to our study.[20]

Intraexaminer reliability was high in this study. The high kappa agreement scores in this investigation reflect the prestudy training of the examiner and may reflect the ease of use of the CCC system, which has previously been reported to be both valid and reliable.[13],[28],[30]

Possible limitations of this study are the sample size of 60 teeth and the short duration of the study. However, power of the study was 80% which is acceptable. Another limitation is that only one SE agent (Xeno V) was used as the bonding agent in this study. It is possible that other bonding agents and systems have better outcomes. Feigal et al. in their study showed that the single-bottle dentin bonding agents performed better.[20],[26]

The split-mouth design used in the current study is the strength, and our study measured the effectiveness of the sealant by its ability to prevent caries in the sealed surfaces of permanent first molars in children considered to be at high risk for dental caries. The primary reason that sealants are placed is to prevent caries. It is recommended if SE adhesive is used for sealing permanent molars of young children for a limited period; it should be reviewed every 6 months.


  Conclusions Top


  • No significant difference was seen in the retention of fissure sealants placed on occlusal surfaces following the use of an SE bonding agent and traditional PAE technique, after 6 months
  • Of the fissure sealants placed in the SE group in the lower permanent molar teeth (n = 30 teeth), score A (complete sealant coverage) was recorded for 66.7% at 6 months
  • Of the fissure sealants placed in the TAE group in the lower permanent molar teeth (n = 30 teeth), score A (complete sealant coverage) was recorded same for 66.7% teeth at 6 months.


Financial support and sponsorship

Nil.

Conflicts of interest

There are no conflicts of interest.

 
  References Top

1.
Muller-Bolla M, Lupi-Pégurier L, Tardieu C, Velly AM, Antomarchi C. Retention of resin-based pit and fissure sealants: A systematic review. Community Dent Oral Epidemiol 2006;34:321-36.  Back to cited text no. 1
    
2.
Ripa LW. The current status of pit and fissure sealants. A review. J Can Dent Assoc 1985;51:367-75, 377-80.  Back to cited text no. 2
[PUBMED]    
3.
Ripa LW, Leske GS, Varma AO. Longitudinal study of the caries susceptibility of occlusal and proximal surfaces of first permanent molars. J Public Health Dent 1988;48:8-13.  Back to cited text no. 3
    
4.
Beauchamp J, Caufield PW, Crall JJ, Donly K, Feigal R, Gooch B, et al. Evidence-based clinical recommendations for the use of pit-and-fissure sealants: A report of the American Dental Association Council on Scientific Affairs. J Am Dent Assoc 2008;139:257-68.  Back to cited text no. 4
    
5.
Braham RL, Morris ME. Textbook of Pediatric Dentistry. 2nd ed. New Delhi,: CBS Publishers and Distributors; 1990.  Back to cited text no. 5
    
6.
Ripa LW. Occlusal sealants: Rationale and review of clinical trials. Int Dent J 1980;30:127-39.  Back to cited text no. 6
[PUBMED]    
7.
Gandini M, Vertuan V, Davis JM. A comparative study between visible-light-activated and autopolymerizing sealants in relation to retention. ASDC J Dent Child 1991;58:297-9.  Back to cited text no. 7
    
8.
Feigal RJ. Sealants and preventive restorations: Review of effectiveness and clinical changes for improvement. Pediatr Dent 1998;20:85-92.  Back to cited text no. 8
    
9.
Mascarenhas AK, Nazar H, Al-Mutawaa S, Soparkar P. Effectiveness of primer and bond in sealant retention and caries prevention. Pediatr Dent 2008;30:25-8.  Back to cited text no. 9
    
10.
Feigal RJ, Hitt J, Splieth C. Retaining sealant on salivary contaminated enamel. J Am Dent Assoc 1993;124:88-97.  Back to cited text no. 10
    
11.
Bottenberg P, Gräber HG, Lampert F. Penetration of etching agents and its influence on sealer penetration into fissures in vitro. Dent Mater 1996;12:96-102.  Back to cited text no. 11
    
12.
Gomes-Silva JM, Torres CP, Contente MM, Oliveira MA, Palma-Dibb RG, Borsatto MC. Bond strength of a pit-and-fissure sealant associated to etch-and-rinse and self-etching adhesive systems to saliva-contaminated enamel: Individual vs. simultaneous light curing. Braz Dent J 2008;19:341-7.  Back to cited text no. 12
    
13.
Burbridge L, Nugent Z, Deery C. A randomized controlled trial of the effectiveness of a one-step conditioning agent in sealant placement: 6-month results. Int J Paediatr Dent 2006;16:424-30.  Back to cited text no. 13
    
14.
Venker DJ, Kuthy RA, Qian F, Kanellis MJ. Twelve-month sealant retention in a school-based program using a self-etching primer/adhesive. J Public Health Dent 2004;64:191-7.  Back to cited text no. 14
    
15.
Waggoner WF, Siegal M. Pit and fissure sealant application: Updating the technique. J Am Dent Assoc 1996;127:351-61.  Back to cited text no. 15
    
16.
Feigal RJ, Hitt J, Splieth C. Retaining sealant on salivary contaminated enamel. J Am Dent Assoc 1993;124:88-97.  Back to cited text no. 16
    
17.
Simonsen RJ. Pit and fissure sealant: Review of the literature. Pediatr Dent 2002;24:393-414.  Back to cited text no. 17
    
18.
Feigal RJ. The use of pit and fissure sealants. Pediatr Dent 2002;24:415-22.  Back to cited text no. 18
    
19.
Nogourani MK, Javadinejad S, Talakub N. Effect of bonding agent on sealant microleakage in saliva-contaminated enamel. J Dent Shiraz Univ Med Sci 2009;10:128-35.  Back to cited text no. 19
    
20.
Feigal RJ, Quelhas I. Clinical trial of a self-etching adhesive for sealant application: Success at 24 months with prompt L-Pop. Am J Dent 2003;16:249-51.  Back to cited text no. 20
    
21.
Pinar A, Sepet E, Aren G, Bölükbasi N, Ulukapi H, Turan N. Clinical performance of sealants with and without a bonding agent. Quintessence Int 2005;36:355-60.  Back to cited text no. 21
    
22.
Peng SM, Zhao W, Lin JC, Ling JQ. Clinical effect of pit and fissure sealant used in combination with self-etching adhesive on permanent teeth. Shanghai Kou Qiang Yi Xue 2006;15:571-4.  Back to cited text no. 22
    
23.
Zhang S, Qin M, Li J. A comparison study on the effect of self-etching adhesive and phosphoric acid fissure sealant in children. Hua Xi Kou Qiang Yi Xue Za Zhi 2008;26:630-2.  Back to cited text no. 23
    
24.
dos Santos KT, Sundfeld RH, Garbin CA, de Alexandre RS, Sundefeld ML, Ceolim BN. Length of resin tags in pit-and-fissure sealants: All-in-one self-etching adhesive vs phosphoric acid etching. Compend Contin Educ Dent 2008;29:186-92.  Back to cited text no. 24
    
25.
Boksman L, McConnell RJ, Carson B, McCutcheon-Jones EF. A 2-year clinical evaluation of two pit and fissure sealants placed with and without the use of a bonding agent. Quintessence Int 1993;24:131-3.  Back to cited text no. 25
    
26.
Feigal RJ, Musherure P, Gillespie B, Levy-Polack M, Quelhas I, Hebling J. Improved sealant retention with bonding agents: A clinical study of two-bottle and single-bottle systems. J Dent Res 2000;79:1850-6.  Back to cited text no. 26
    
27.
Salem K, Shahsavari F, Anisian A, Moradi M. Comparison of two bonding systems: Self etch versus etch and rinse in effectiveness of fissure sealants on newly erupted fi rst permanent molars. J Mashhad Dent Sch 2011;185:194. Available from: http://www.mums.ac.ir/shares/dental_journal/dental%20journal/90/autumn/5.pdf. [Last cited on 2015 Jul 10].  Back to cited text no. 27
    
28.
Burbridge L, Nugent Z, Deery C. A randomized controlled trial of the effectiveness of a one-step conditioning agent in fissure sealant placement: 12 month results. Eur Arch Paediatr Dent 2007;8:49-54.  Back to cited text no. 28
    
29.
Yazici AR, Karaman E, Baseren M, Tuncer D, Yazici E, Unlüer S. Clinical evaluation of a nanofilled fissure sealant placed with different adhesive systems: 24-month results. Oper Dent 2009;34:642-7.  Back to cited text no. 29
    
30.
Deery C, Fyffe HE, Nugent ZJ, Nuttall NM, Pitts NB. A proposed method for assessing the quality of sealants – The CCC sealant evaluation system. Community Dent Oral Epidemiol 2001;29:83-91.  Back to cited text no. 30
    


    Figures

  [Figure 1], [Figure 2], [Figure 3]
 
 
    Tables

  [Table 1], [Table 2], [Table 3]


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