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A randomized controlled trial of the effectiveness of a one-step conditioning agent in fissure sealant placement: 12 month results.


Aim: To compare the retention of fissure sealants (FS) placed on occlusal surfaces following use of a self etching priming agent and traditional acid etch and to compare the caries incidence of occlusal surfaces sealed using the two techniques over 12 months. Study Design: A randomised controlled trial set in NHS Dental Service and Dental Hospital clinics (UK). Materials and Methods: Subjects (60) were recruited by 7 dental professionals who placed FS on mandibular permanent molar pairs. The technique used for enamel preparation prior to FS placement on the right and left side of the mandible was randomised. On one side of the mandible Xeno[R] III (Dentsply, Germany) was used to prepare the occlusal enamel and on the other side phosphoric acid etch together with Prime and Bond[R] (Dentsply, Germany) was used. Opaque Delton[R] (Dentsply, USA) was used to seal all surfaces. Subjects were blinded to the techniques used. Subjects and operators recorded on individual questionnaires their impressions of the techniques used. Statistics: Results were analysed using the SPSS statistics package. Results: Thirty eight (63%) subjects were seen for review by the principal researcher 12 months after FS placement. The retention was significantly better in the etch group (P = 0.003). No statistically significant difference in caries incidence was found between the test and control groups at 12 months. Conclusions: The best practice for placement of sealants remains enamel preparation with acid etch and use of an intermediate bonding layer.

Key words: Fissure sealant, retention, caries incidence, one step conditioning agent


Fissure sealants (FS) were introduced into dentistry for protecting susceptible occlusal surfaces from dental caries over 30 years ago following work by Takeuchi [1964] and Cueto and Buonocore 1965]. A recent Cochrane review [Ahovuo-Saloranta et al., 2004] has confirmed the effectiveness of resin based FS on occlusal surfaces of permanent molars. Most children accept this procedure with no difficulty [Gordon et al., 2003]. There are however a number of children who find the procedure difficult and it is often the taste, rinsing and suction associated with the phosphoric acid etching stage that patients find unpleasant [Feigal and Quelhas, 2003].

Traditionally FS are placed after cleansing and phosphoric acid etching of the fissure enamel. Phosphoric acid etching removes contaminants and creates an irregular microporous enamel surface that is infiltrated by the resin based FS material. The technique of including a bonding primer between etched enamel and FS resin has gained popularity since the early 1990's. Hitt and Feigal [1992] described the technique as a means of overcoming the negative effects of salivary contamination of etched enamel surfaces by using hydrophilic materials that contained water, applied under FS, in order to improve FS retention rates.

New non-rinse conditioning systems are now becoming available which enable composite resin to enamel bonding without previous phosphoric acid etching of the enamel surface. These new materials have been hailed as clinically the most promising approach in terms of both user-friendliness and technique sensitivity [Van Meerbeek et al., 2003]. The etch-and-rinse phase is no longer required which reduces clinical application time and also reduces the risk of making errors during application and manipulation. It is also possible that this technique is more forgiving of mild salivary contamination. Salivary contamination of the tooth surface after acid etching compromises the ultimate bond between resin and enamel and has been implicated in FS failure [Thomson et al., 1981; Gwinnett et al., 1982].

The volume of literature which exists at present on the subject of FS only includes limited documentation comparing conventional acid etch systems with non-rinse conditioning acid etch systems in vivo. Feigal and Quelhas [2003] reported on a clinical trial of a self-etching adhesive for FS application over 24 months. They showed equivalent FS retention on occlusal and buccal/lingual surfaces of permanent molars using a self etching primer/adhesive system (Prompt-L-Pop[R], 3M ESPE) compared with conventional etch and seal methods on contra-lateral teeth over this time period. It is likely that this study was underpowered and therefore conclusions drawn and clinical relevance of this research are limited due to the small number of subjects reported upon.

Venker et al. [2004] retrospectively compared a self-etching primer (Prompt L-Pop[R]) and phosphoric acid etch in a school based FS program over a one year period. They found that FS retention with the use of the self-etching primer was poorer than with phosphoric acid etch. In a recently published systematic review [Muller-Bolla et al., 2006] the authors could not determine the best clinical procedure for placement of resin based FS because of the insufficient number of clinical studies.

Xeno[R] III is a single step self-etching dental adhesive designed to bond light cured restoratives to enamel and dentine. The single step bonding system treats enamel and dentine simultaneously with acid-conditioning, priming and bonding functions. The aim of this study was, therefore, to compare the clinical effectiveness of a non-rinse conditioner with conventional acid etch bonding for enamel preparation prior to FS placement. Results of this investigation at six months following FS placement have been presented elsewhere [Burbridge et al., 2006]. The specific research questions at twelve month review were:

* Is there still a significant difference in retention of FS following placement on occlusal surfaces of permanent molar teeth between the two techniques?

* Is there still a significant difference in caries incidence following FS placement on occlusal surfaces of permanent molar teeth between the two techniques?

* What was the status of FS in the test group at 12 month review that had not been replaced?

Materials and Methods

Subjects. Ethical approval for this study was granted by the Lothian Research Ethics Committee, Edinburgh, Scotland. Written informed consent for the involvement in the trial was obtained from an adult with parental responsibilities and rights having also gained the consent of each subject. Subjects were recruited from regular patients attending Dental Hospital and Community Dental Service clinics in the Lothian area of Scotland and were eligible for inclusion in the trial if FS sealant placement on contra-lateral mandibular permanent molar teeth was indicated according to British Society of Paediatric Dentistry recommendations [Nunn et al., 2000] and the Scottish Intercollegiate Guideline Network guideline 47 [SIGN, 2000], i.e. those at high caries risk. Paired mandibular permanent molars were assessed by individual operators who required them to be erupted enough to isolate teeth sufficiently for placement of FS and to be caries free. Children who were felt not to have sufficient cooperation to allow sealant placement were excluded. Sealants were placed on maxillary molars as part of the trial if clinically indicated, however the paired mandibular molar teeth were the principal unit of analysis due the effect of clustering.

Feigal [1998] reported in a review of FS clinical trials a failure rate (FS needing repair, replacement or restoration) of sealants of between 5% and 10% each year. A power calculation based on these figures indicated that a sample of 80 would give a 90% power of detecting a difference in effectiveness between the two systems assuming a significance level of 5%. To allow for drop out of subjects over the duration of the study, at the outset the aim was to recruit 50% more subjects in the first instance giving a total of 120 subjects.

Operators. A total of 9 operators were recruited to place FS for this clinical trial; all routinely worked with an assistant. Dentists and therapists were involved from the Hospital Dental Service as well as dentists and hygienists from the Community Dental Service. All operators were fully qualified clinicians. The operators received written and verbal training in the two FS techniques to be used from the principal researcher. These were identical to those issued by the manufacturer for each product.

Operators were instructed to always place FS on the mandibular right molar tooth first. Randomization of the FS technique to be used on the mandibular right molar tooth was achieved by computer generation of a random number sequence.

Sealant placement. Light curing unit efficacy was measured in all clinics where FS were placed using an Optilux[R] radiometer (Demetron Research Corporation, Danburg, CT, USA). Readings between 300 and 800mW/nm2 were considered acceptable. Before placement of FS, prophylaxis of each molar tooth was undertaken using a dry prophylaxis brush only. Individual teeth were isolated using cotton wool rolls and/or narrow bore suction (saliva ejector) and surfaces washed and dried with a 3-in-1 tip.

Control group: Phosphoric acid 37% was applied to molar occlusal surfaces in the usual manner and left for 20 seconds for etching to occur. Teeth were rinsed with water for 20 secs and then air dried using 3 in 1 tip. Prime and Bond[R] was applied, left for 20 secs, air dried as per manufacturers instructions and light cured for 10 secs. Delton[R] opaque light curing FS was applied to fissures and cured for 20 secs.

Test group: Equal quantities of Xeno[R] III liquids were mixed together in a dappens pot for 5 secs. This liquid was then applied to occlusal surface of the molar tooth, left for 20 secs; air dried using 3 in 1 tip and light cured for 10 secs. Delton[R] opaque light curing FS was applied to fissures and cured for 20 secs.

Outcome measures. These used at 12 month review were retention of FS and presence of caries. Sealants were assessed according to a modified version of the CCC FS evaluation system described by Deery et al. [2001] as summarized in table 1. If FS had been replaced since the first phase of the investigation, this was recorded. The integrity of FS was reviewed and recorded at between 12 and 15 months following placement by an independent clinician (LB) who was blind to the techniques used for tooth preparation prior to FS placement in all cases. This clinician received training and calibration in assessment of the integrity of FS and caries diagnosis at the D1 (enamel and dentine caries) and D3 (dentine caries) diagnostic thresholds [Pitts and Fyffe, 1988; Deery et al., 2001] from an experienced epidemiologist (CD).

Reliability. Intra-examiner reproducibility was calculated by re-examination of 4 subjects (10%) by the principal researcher at a subsequent appointment. Inter-examiner reproducibility was calculated by examination of 11 subjects (29%) by both the principal researcher (LB) and another independent clinician (CD). Data collected in this investigation were analyzed using the SPSS statistics package.


Of the 7 operators who placed sealants, 3 were dental surgeons, 3 were dental hygienists and one was a dental therapist. At baseline a total of 60 subjects were recruited to the study by the 7 operators. There were 81 pairs of FS placed on permanent molar teeth of which 60 pairs were on mandibular permanent molars and 21 pairs on maxillary permanent molars. Of the 60 subjects recruited to the study 28 were male and 32 female. The mean age of subjects at the time of sealant placement was 9.15 years (range 5 to 13 years).

Finally, 38 subjects (63%) were seen 12 months following FS placement for review by the principal researcher. These subjects had a total of 50 pairs of sealants placed as part of the trial; 38 pairs on mandibular permanent molar teeth and 12 pairs on maxillary permanent molar teeth. Of these 38 subjects, 28 had FS placed on paired first permanent molars and the remaining 10 subjects had FS placed on pairs of second permanent molar teeth. Of the 38 subjects reviewed at least 12 months following sealant placement, 30 (79%) had also been seen for review at six months.

Replaced sealants: The number of FS that had been replaced over the 12 month period in the subjects reviewed was 43 (43%). The distribution of replaced FS between groups was in the etch group 8 mandibular and 4 maxillary, while for the Xeno[R] III group the numbers were 23 and 8 respectively. A McNemar test, Table 2, shows that FS placed using the Xeno[R] III system were more likely to be replaced within the 12 months than those in the control group (P<0.001). Of the subjects reviewed there were 18 who had not had either the test or control FS replaced.

Sealant coverage scores: These were recorded blind at review by the principal researcher. Results for FS that had not been replaced on the mandibular (n=45 teeth) and maxillary (n=12 teeth) permanent molars are shown in Table 3. The FS coverage scores on mandibular permanent molars at 12 month review are illustrated in Figure 1. Of the original FS placed in the Etch (control) group in both the mandibular and maxillary arches (n=38 teeth), at 12 month review, score A (complete FS coverage) was recorded for 26% teeth. In the same group, 87% teeth were given an A or B FS coverage score.


When comparing all permanent molar pairs seen at review, where neither FS had been replaced, the Wilcoxon Signed Ranks test showed that the coverage was significantly better (P = 0.003) in the control group than for the Xeno[R] III group. This test showed that use of etch and Prime and Bond[R] was significantly more likely to result in placement of a FS which remained covering more of the pit and fissure system over a 12 month period than use of Xeno[R] III for enamel preparation.

Caries scores: Three teeth had developed dentine caries to the point of cavitation (2 in the etch group and 1 in the Xeno[R] III group. When comparing caries scores for both maxilla and mandible at either the D1and D3 caries diagnostic thresholds, using the Wilcoxon signed ranks test, no significant difference is seen in decay levels between those surfaces sealed with etch together with Prime and Bond or Xeno[R] III at the12 month review.

Reproducibility: Both intra-examiner and inter-examiner reproducibility were analysed and Kappa values determined for both. The Kappa values were interpreted using Landis and Koch's [1977] six point scale. For teeth seen at 12 month review there was complete intra-examiner agreement (Kappa = 1.0) between the FS coverage scores at visit 1 and visit 2. The intra-examiner Kappa value for caries scores at visit 1 and visit 2 at 12 month review was 0.78 (almost perfect agreement). Teeth seen at 12 month review had an interexaminer agreement Kappa value of 0.73 (almost perfect agreement) for FS coverage scores. There was complete inter-examiner agreement (Kappa =1) for caries scores at 12 month review.


Subject follow up: As in most clinical trials, at the outset, it was anticipated that a percentage of subjects recruited to the investigation would be lost to follow up. In this study, at 12 month review, 22 of 60 patients (37%) recruited did not attend for examination by the principal researcher. This compares with successful follow up of 46 of 60 subjects (77%) at six month review. Given the significant difference between the two interventions the power of the study even with the reduced sample size was adequate.

It is possible that the relatively high drop out rate may have influenced the results. There is no reason, however, to think that either product would have performed differently in the patients who failed to re-attend.

Retention: The teeth in the etch group were significantly more likely to have a FS coverage score that reflected a greater percentage of the fissure system remained covered by FS at 12 month review. This result is consistent with what was found six months following placement of FS in this investigation.

Caries incidence: No significant difference between the caries scores recorded in teeth reviewed at 12 months between the etch group and the Xeno[R] III group was identified. This differs from the result found at six month review where teeth in the Xeno[R] III group were found more likely to show early enamel caries than the etch group. Failed FS in this study were repaired using the control method and not left to allow caries to develop. Therefore, long term follow-up to permit assessment of caries incidence as an outcome measure is not possible. These results suggest that development of occlusal surface caries is independent of the material used to bond FS to a tooth prior to failure of a sealant or the sealant material used and that the critical factor is adequate sealant retention and coverage.

Reproducibility: Both intra-examiner and inter-examiner Kappa agreement were high in this study. The high Kappa agreement scores in this investigation reflect the pre-study 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 [Deery et al. 2001].

Retention. The result for FS retention of 87% (when combining sealant scores A and B) in the control group in this investigation at review compares reasonably favourably to previously published figures for FS retention in clinical trials. In a review of clinical trials [Feigal, 1998] an average failure rate of between 5% and 10% per year was reported.

This study has produced results at both 6 and 12 months that are in contrast to those of Fiegal and Quelhas [2003] who had concluded that use of Prompt-L-Pop[R] was as effective as use of etch alone for FS placement in their 24 month clinical study.

The results of our investigation at 6 and 12 months support the results of the in vitro study undertaken by Hannig et al. [2004] and the retrospective analysis of FS application techniques carried out by Venker et al. [2004]. The conclusions of both these investigations were that the use of self-etching adhesives could not be recommended for enamel preparation prior to FS placement and that further work on this subject was required.

An in vitro study by Atash and Van den Abbeele [2005] investigated bond strengths of a number of adhesives to bovine enamel and dentine including Xeno[R] III. In this study Xeno[R] III performed better than some self-etch adhesives on the dental market but did not perform as well as the products that used separate etching and bonding steps. The results of this randomised controlled trial would appear to support the results that this group of workers achieved in vitro.

Celiberti and Lussi [2005] have reported on an in vitro study in which FS were placed following phosphoric acid etching both with and without subsequent use of Xeno[R] III. They concluded that the additional use of Xeno[R] III did not improve FS under the conditions of their study.

Xeno[R]III is considered to be an intermediary strong one step conditioning agent as the pH of this product is less than 1. By comparison Promt-L-Pop, which has been used with variable results in other studies [Feigal and Quelhas, 2003; Venket et al., 2004] and has a pH of approximately 1.0. Generally, the lower the pH of a self-etching adhesive the better will be the bonding occurring to enamel. However, this is not the only factor. For example, work by Perdigao and Geraldeli [2003] has shown that self-etching adhesives performed better on prepared enamel than on unprepared enamel. The presence of residual protein such as plaque in the fissures may also be a factor, effecting bonding. In a recent in vitro investigation [Perdiago et al., 2005] it was found that when using some self etching adhesives higher bond strengths to sealant materials were achieved with the application of two layers of the adhesive product. It is possible that the use of two layers of Xeno" III may have produced different results in this clinical investigation. The additional step of applying a layer of bonding resin subsequent to etching enamel is not a universally adopted technique and is not referred to in guidelines relating to FS placement at present. However, it was chosen as the control in this study because of local practice and work suggesting better retention than direct application of resin, particularly where contamination has occurred [Feigal et al., 1993].

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 self-etching adhesives.

This present study appears to be the first clinical trial to investigate use of Xeno[R] III for this application over 12 months. In view of the findings of this investigation, best practice for placement of FS remains enamel preparation with acid etch and use of an intermediate bonding layer such as Prime and Bond[R].


Enamel preparation with etch and Prime and Bond[R] is a superior method over 12 months when measured using retention to the use of Xeno[R] III when placing FS. This is in addition to results collected at 6 months in the same clinical trial which also found enamel preparation with etch and Prime and Bond[R] to be the more effective technique.


We would like to thank all clinicians, supporting staff and patients in the Lothian region involved in this clinical investigation for their time and commitment to this study. We would also like to thank Dentsply for providing the Xeno[R] III.


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L. Burbridge *, Z. Nugent **, C. Deery ***

* Dept Paediatric Dentistry, Edinburgh Dental Institute, Scotland; ** Cancer Care, University of Manitoba, Winnipeg, Canada; *** Dept. Paediatric Dentistry, School of Clinical Dentistry, Sheffield, England.

Postal address: Prof. C. Deery, Dept. Paediatric dentistry, School of Clinical Dentistry, Claremont Crescent, Sheffield, England. S10 2TA.

Table 1 Summary of CCC fissure sealant evaluation system criteria
in a study to test the effectiveness of a one-step conditioning
agent in sealant placement.

Sealant Coverage Clinical Appearance

A Sealant covering all of fissure system
B Sealant present on >50% fissure system
C Sealant present on <50% fissure system
D No sealant present

Caries Score Clinical appearance

0 Surface sound, no caries
1W Initial enamel caries - white spot lesion
1B Initial enamel caries - brown spot lesion
2 Enamel caries
3P Caries into dentine - cavity <0.5mm
3L Caries into dentine - cavity >0.5mm
4 Caries with probable pulpal involvement

Table 2 Data used for McNemar test comparing the retention
of the Etch and Xeno[R]III groups at 12 months for mandibular
first permanent molars showing a significant difference between
etch and no etch (P<0.001) in a study on fissure sealants.


 No Yes Total

Etch No 18 20 38
 Yes 1 11 12
Total 19 31 50

Table 3 Frequency of fissure sealant coverage CCC scores
by group in a study to test the effectiveness of a one-step
conditioning agent in fissure sealant placement

Sealant coverage score Etch group Xeno[R]III group

(Mandible n = 45)

A 9 0
B 17 3
C 4 2
D 0 10

(Maxilla n = 12)

A 1 0
B 6 0
C 1 2
D 0 2
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Author:Burbridge, L.; Nugent, Z.; Deery, C.
Publication:European Archives of Paediatric Dentistry
Article Type:Clinical report
Geographic Code:4EUUK
Date:Mar 1, 2007
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