sealing occlusal dentin caries in permanent molars: 7-year … · 2017-01-19 · vol. 2 • issue 1...

Vol. 2 • Issue 1 Sealing Occlusal Dentin Caries in Permanent Molars

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© International & American Associations for Dental Research 2016

Original repOrt: epidemiOlOgic research

Abstract: The purpose of this study was to investigate the possibility of postponing restorative intervention of manifest occlusal caries in young, permanent dentition by non-invasive sealing. This RCT-designed study included 521 occlusal lesions in 521 patients aged 6 to 17 y. Based on clinical and radiographic assessments, all lesions required restorative treatment. After randomization (ratio 2:1), 368 resin sealings and 153 composite–resin restorations were performed by 68 dentists in 9 municipalities. The primary aims were to 1) analyze survival of sealings until replacement by restoration, 2) compare longevity of sealings and restorations until retreatments, and 3) compare effectiveness of sealings and restorations to halt caries progression in sealed lesions and beneath restorations. Furthermore, we aimed to identify factors influencing longevity and the effectiveness of sealings and restorations. Treatments

were annually controlled, clinically and radiographically. After 7 y, the drop out rate was 8%, and 54% of the treatments were completed due to age. Of the sealings, 48% were retreated, including 31% replaced by restorations; 12% were still functioning. Of the restorations, 7% were repaired/renewed and 20% were still functioning. No endodontics was performed. Kaplan–Meier and Cox regression survival analyses were performed on 341 sealings and 152 restorations in first and second molar teeth. The 7-y survival was 37% (CI, 29% to 45%) for sealings and 91% (CI, 85% to 96%) for restorations (P < 0.001). The median survival time for sealings not replaced by restorations was 7.3 y (CI, 6.4 y to NA). Survival of sealings was increased in patients with low caries risk and/or excellent oral hygiene, second molars compared with first molars, and lesions not extending the middle one-third of the dentin. Survival of sealings was not influenced

by municipality, sex, eruption stage or clinical surface cavitation. The results underline that it is possible to postpone or avoid restorative intervention of occlusal dentin caries lesions in young permanent teeth by non-invasive sealing.

Knowledge Transfer Statement: The first restoration can ultimately be fatal for a young permanent tooth. A restoration may not be the final treatment but the start of an ongoing treatment with still more loss of tooth substance. The present study shows the possibility of treating occlusal dentin caries lesions with non-invasive resin sealings instead of conventional resin composite restorations in children and adolescents. Improved oral health can be expected.

Keywords: clinical trial, survival, effectiveness, fissure sealant, composite resin restoration, pediatric dentistry

JCTXXX10.1177/2380084416680191JDR Clinical & Translational ResearchSealing Occlusal Dentin Caries in Permanent Molarsresearch-article2016

DOI: 10.1177/2380084416680191. 1Department of Odontology, Faculty of Health and Medical Sciences, University of Copenhagen, Denmark; 2Public Dental Health Service, Aarhus, Denmark; 3Public Dental Health Service, Gentofte, Denmark; 4Public Dental Health Service, Hørsholm, Denmark; 5Department of Public Health, Faculty of Health and Medical Sciences, University of Copenhagen, Denmark. Corresponding author: V. Qvist, Department of Odontology, Faculty of Health and Medical Sciences, University of Copenhagen, Denmark. Email: [email protected]

A supplemental appendix to this article is published electronically only at http://jdrctr.sagepub.com/supplemental.

Sealing Occlusal Dentin Caries in Permanent Molars: 7-Year Results of a Randomized Controlled TrialV. Qvist1, M.K. Borum2, K.D. Møller3, T.R. Andersen4, P. Blanche5, and A. Bakhshandeh1

JDR Clinical & Translational Research January 2017

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Introduction

Diagnosis and management of occlusal caries is of special importance in children and adolescents. Approximately half of all caries lesions in young permanent teeth are located occlusally (Carvalho 2014; Nørrisgaard et al. 2016), even though occlusal surfaces constitute only 12.5% of all surfaces. Occlusal surfaces are continuously treated for caries and caries sequelae from childhood and during adulthood, and this leads to very few sound surfaces in elderly patients (Kongstad et al. 2013). It has been documented that caries and its traditional restorative treatment have an adverse effect on the dental health of the population because the longevity of restorations is limited and continuous retreatment results in loss of tooth tissue and weakened teeth (Qvist 2015). Fissure sealants have been used for preventive measures for decades and significantly reduce occlusal caries in young permanent dentition even after several years (Bhuridej et al. 2005; Beauchamp et al. 2008; Ahovuo-Saloranta et al. 2013). Promising results have also been obtained with therapeutic sealing of early “non-cavitated” enamel lesions in permanent teeth (Beauchamp et al. 2008; Ahovuo-Saloranta al. 2013). There is a major reduction in viable microorganisms beneath an intact sealing (Handelman et al. 1976; Beauchamp et al. 2008). Caries progression may also be arrested beneath tightly sealed dentin lesions (Handelman 1976; Going et al. 1978); however, there is currently limited knowledge on sealing dentin caries (Handelman et al. 1976; Handelman et al. 1981; Mertz-Fairhurst et al. 1998; Bakhshandeh et al. 2012). Over the last decades, there have been developments in fissure sealants, which has resulted in improved longevity and effectiveness of current marketed brands (Simonsen 2002; Simonsen and Neal 2011).

The primary aims of our study were to:

1. Analyze the survival of sealings until replacement by restorations

2. Compare the longevity of sealings and restorations until retreatments

3. Compare the effectiveness of seal-ings and restorations to halt car-ies progression in sealed lesions and beneath restorations.

Furthermore, we aimed to identify patient-, lesion-, and treatment-related factors influencing the longevity and effectiveness of sealings and restorations.

Materials and Methods

The study was designed as a prospective, randomized, controlled clinical trial with two parallel treatment arms: non-invasive resin sealing and conventional composite resin restoration. Randomization was performed to two-thirds of the lesions in the sealing group, and one-third in the restoration group, because we already have sufficient knowledge of Class I restorations (Qvist 2015).

The estimation of sample size was directed to the hypothesis of different longevity of resin sealings and resin restorations. This was based on the following premises: two-thirds of lesions receiving resin sealings and one-third of lesions receiving composite resin restorations; there would be annual failure rates of 10% for sealings and 1.5% for restorations; α = 5% and β = 10% (Qvist 2015). With a follow-up period of 1 y, we required 164 patients (lesions) in the sealing group and 82 in the restoration group. Because our primary focus was to examine the feasibility of the extended use of sealings, we planned a follow-up period of 5 to 10 y, with an estimated annual attrition rate of 5%. Therefore, we doubled the estimated sample size.

For each clinician, computerized randomization between sealing and restoration was made at the University of Copenhagen and saved at the clinic in sequentially numbered, sealed envelopes. Selection bias was prevented by allocation concealment until intervention was assigned. After randomization, two-thirds of the teeth received sealing and one-third received restoration. Blinding was not possible.

The cohort consisted of 521 patients (aged 6 to 17 y) with manifest occlusal

caries (Appendix Table). To be enrolled in the study, each patient must have at least one lesion requiring restorative treatment that has been clinically or radiographically assessed by the dentist; a lesion with a radiographic depth limited to half of the dentin; given written informed consent from the child and parents before treatment; be less than 17 y old, as this would provide a minimum observation period of 1 y before the patient would be discharged from the Public Dental Health Care Service (PDHCS) at the age of 18 y. Patients were excluded when the occlusal lesion had communication with an approximal caries lesion or occlusal/approximal restoration; the tooth was hypomineralized; or when the patient presented with serious chronic diseases that affect caries experience and activity. Treatments were performed by 68 dentists in the PDHCS from 9 Danish municipalities in collaboration with the Department of Odontology, University of Copenhagen, Denmark.

Baseline

Bitewing X-rays were taken before treatment unless available bitewing images were less than 6 mo old. The clinical and radiographical severity of the caries lesion was assessed by the dentist using the severity scales shown in the Appendix Table. The oral hygiene and caries risk of the participants were assessed subjectively (Appendix Table). Allocation to a treatment group was decided in the clinic by opening the sealed envelope with the indication of the randomized treatment choice. The dentists used resin fissure sealant and composite resin restorative of own choice and followed their usual clinical procedures based on instructions from the manufacturers and guidelines from the University of Copenhagen, Denmark.

Follow-up

Treatments were examined annually. The integrity of sealings was assessed clinically as being optimal, in need of repair, in need of replacement by a new sealing, or in need of replacement by a


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restoration. The integrity of restorations was assessed as being optimal, in need of repair, in need of replacement, or in need of extension due to primary caries. The radiographical depth of a lesion was compared with the depth at baseline and assessed as regression, unchanged depth, or progression. Radiographically assessed caries beneath a restoration was registered as lesion progression. Treatments were followed-up until replacement of sealings by restorations and retreatment of restorations. The continued observation stopped if the patient moved, was discharged from PDHCS, or dropped out (Table 1). Reasons for retreatment were registered.

Clinical criteria for retreatment or replacement of sealings and restorations were: part or total loss, caries progression, persistent pulpal symptoms, or primary caries in other part of the tooth requiring treatment involving study sealing or restoration.

Radiographical criteria for evaluation of sealings were: caries regression, unchanged depth, or caries progression; for restorations: unchanged depth, or caries progression. During the follow-up period, 8 of the 9 municipalities changed their conventional radiographic system to digital systems.

Statistical Methods

For the statistical bi- and multivariate analyses, 341 of the 368 sealings and 152 of the 153 restorations were included. Eight sealings and 1 restoration in premolars, and 9 sealings in Delton FS were excluded because of insufficient numbers. Missing information about location of caries lesion and location of sealing caused exclusion of a further 3 and 7 sealings, respectively. Municipality was merged to 3 caries risk categories—Low, Moderate and High—based on average caries experience of 12-y-olds, fluoride concentration in drinking water, and family income in the municipality. Caries risk, oral hygiene, and radiographical assessment were also merged for the statistical analyses (Tables 2 and 3; Appendix Table). To overcome the association between patient age and

tooth type, we developed a variable, “eruption age”, where the age of the patient at treatment was subtracted by the mean age of eruption of the first and second molars according to sex and jaw in Denmark (Koch et al. 2009). Thereafter, eruption age was categorized as less than or equal to 2 y, and over 2 y (Tables 2 and 3; Appendix Table).

Different definitions of failure were used. For Aim 1, sealings were recorded as failures when replaced by a restoration. For Aim 2, sealings were recorded as failures if they were repaired or replaced by a new sealing or restoration, and restorations were recorded as failures if they were repaired or replaced. For Aim 3, sealings and restorations were recorded as failures where radiographic caries progression was observed. The observation period for failed sealings and restorations was defined as the period between the date of treatment and the date of failure. The observation period for censored treatments was defined as the period between the date for treatment and the date when the patient was discharged from PDHCS because of age or, in case of drop outs, the date of the last follow-up. For continued observations, the observation period ranged from the date of treatment to January 31st 2015.

Chi-square test and Fisher exact test were used for analyses of correlation between predictor variables. Kaplan–Meier test was used to estimate survival probabilities of sealings and restorations considering the clustering of treatments performed by the same dentist. Because there were few failures in restorations, only bivariate analyses were performed (Table 3). Cox regression analyses, particularly suitable for survival data that contains censored observations, was used to access the bi- and multivariate influences of categorical predictor variables on survival and effectiveness of sealings (Table 2) (Therneau and Grambsch 2000; Martinussen and Scheike 2006). Residual plots and goodness of fit tests based on the scoring processes were used to assess the assumptions of the Cox regression models. Backward

variable selection was used for the multivariate Cox model. 95% confidence intervals and P values were computed using a sandwich-type variance formula appropriate for clustered data. The significance level was set to 5%. Analyses were conducted using R version 3.2.2 (R Core Team) using packages Survival, prodlim and timereg (R Core Team 2014; Gerds 2015) and SPSS version 22.0 (IBM).

Results

Enrollment began in November 2006 and was completed in June 2009 with 368 resin sealings in 7 marketed brands and 153 composite resin restorations in 8 brands. The treatments were performed in 521 patients by 68 dentists from the 9 participating Danish municipalities.

Overall Results, Baseline

The baseline characteristics of the participants are given in the Appendix Table together with P values for differences between study groups. The mean age of the patients at treatment time was 11.9 (2.2) y. The sealing and restoration groups were balanced at baseline with respect to the predictor variables municipality, sex, oral hygiene, tooth type, side, jaw, eruption age, clinical assessment of caries lesion, radiographical assessment of caries lesion, indication for treatment, and caries location (P = 0.07 to 0.98). There was an overrepresentation of low-risk patients in the restoration group (P = 0.02). The treatment extension mirrored the extension of caries lesion for restorations, whereas 89% of the sealings covered the whole fissure system (P = 0.03). Postoperative sensitivity for a few days to weeks was recorded in 8 sealed and 2 restored teeth, but retreatment was not necessary and no endodontics were performed during the 7-y follow-up period.

Correlation Analyses, Baseline

Various significant correlations between predictor variables were found. Excellent oral hygiene and low caries risk were


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Table 1.Overview of the 521 Patients/Lesions Randomly Assigned for Resin Sealing (n = 368) or Composite Resin Restoration (n = 153), and Annual Follow-ups.

Enrollment and Randomization (n = 521)

Sealing Group Restoration Group

Baseline

Allocated to resin fissure sealing (n = 368) Allocated to resin restoration (n = 153)

Did not receive allocated intervention (n = 0) Did not receive allocated intervention (n = 0)

0 to 1 y Follow-up

Completed – replaced by restoration (n = 15) Completed – replaced restoration (n = 2)

Completed – primary caries (n = 1) Completed – primary caries (n = 0)

Completed – age 18 y old (n = 0) Completed – age 18 y old (n = 0)

Drop out – wish of patient/parents (n = 0) Drop out – wish of patient /parents (n = 0)

Drop out – moved (n = 1) Drop out – moved (n = 0)

Drop out – ortho treatment (n = 0) Drop out – ortho treatment (n = 0)

Continued observation (n = 354) Continued observation (n = 151)

1 to 2 y Follow-up




Drop out – wish of patient/parents (n = 5) Drop out – wish of patient/parents (n = 0)




2 to 3 y Follow-up








3 to 4 y Follow-up

Completed – replaced by restoration (n =20) Completed – replaced restoration (n = 1)





(continued)


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Enrollment and Randomization (n = 521)

Sealing Group Restoration Group



4 to 5 y Follow-up








5 to 6 y Follow-up








6 to 7 y Follow-up








0 to 7 y Follow-up

Completed – replaced by restoration (n = 115) = 31% Completed – replaced restoration (n = 11) = 7%

Completed – primary caries (n = 13) = 3.5% Completed – primary caries (n = 8) = 5.2%

Completed – age 18 y old (n = 168) = 46% Completed – age 18 y old (n = 90) = 59%

Drop out – wish of patient/parents (n = 15) = 4.1% Drop out – wish of patient /parents (n = 3) = 2%

Drop out – moved (n = 12) = 3.3% Drop out – moved (n = 7) = 4.6%

Drop out – ortho treatment (n = 1) = 0.3% Drop out – ortho treatment (n = 2) = 1.3%

Continued observation (n = 44) = 12% Continued observation (n = 32) = 21%

Table 1.(continued)


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Table 2.Bi- and Multivariate Analyses of 341 Resin Sealings after 7 y.

Aim 1 Sealings Replaced by Restorations (n = 109 events)

Variable Category n

Bivariate Multivariate

Hazard Ratio (CI) P Value


Municipality Low caries risk 78 1 – 1 0.26

Moderate caries risk 201 0.9 (0.7 to 1.6) 0.83

High caries risk 62 1.4 (0.8 to 2.5) 0.27

Sex Male 161 1 – 1 0.30

Female 180 0.7 (0.4 to 1.1) 0.12

Caries risk Low 149 1 – 1 0.58

Average/High 192 1.4 (1.0 to 1.9) 0.03

Oral hygiene Excellent 156 1 – 1 –

Average/Poor 185 1.5 (1.0 to 2.1) 0.03 1.6 (1.1 to 2.3) 0.02

Tooth type First molar 253 1 – 1 –

Second molar 88 0.4 (0.3 to 0.8) 0.003 0.4 (0.2 to 0.7) 0.002

Side Right 162 1 – 1 0.13

Left 179 0.7 (0.5 to 1.1) 0.09

Jaw Upper 152 1 – 1 0.14

Lower 189 0.7 (0.5 to 1.0) 0.03

Eruption age < 2 y 64 1 – 1 0.93

>2 y 277 1.5 (0.9 to 2.3) 0.13

Clinical assessment of caries lesion

Sound 15 0.4 (0.1 to 1.0) 0.04 1 0.51

Enamel caries without cavity 22 1.3 (0.7 to 2.6) 0.44

Enamel caries with cavity 134 0.8 (0.5 to 1.2) 0.29

Dentin caries without cavity 90 0.9 (0.6 to 1.4) 0.70

Dentin caries with cavity 80 1 –

Radiographical assessment of caries lesion

Sound/Caries Enamel 31 0.6 (0.3 to 1.1) 0.11 1 0.11

DEJ/Caries <1/3 D 209 0.6 (0.4 to 0.9) 0.02

Caries >1/3 D 101 1 –

Caries location Central fossa 141 1 – 1 0.06

Mesial fossa 32 1.1 (0.4 to 2.8) 0.82

Distal fossa 105 1.7 (1.0 to 2.8) 0.04

Multiple fossae 63 2.0 (1.1 to 3.5) 0.02

Treatment extension As caries lesion 40 1 – 1 0.57

Whole fissure system 301 1.2 (0.6 to 2.2) 0.59

Fissure sealant brand Delton LC 179 1 – 1 0.19

Clinpro Sealant 18 0.9 (0.5 to 1.9) 0.81

Grandio Seal 16 1.1 (0.4 to 2.5) 0.91

Helioseal Clear 34 0.7 (0.4 to 1.1) 0.12

Helioseal F 48 1.1 (0.6 to 2.1) 0.70

UltraSeal XT 46 0.7 (0.4 to 1.4) 0.33

(continued)


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Sex Male 161 1 – 1 0.37

Female 180 0.7 (0.5 to 1.1) 0.10

Caries risk Low 149 1 – 1 –

Average/High 192 1.6 (1.2 to 2.1) 0.003 1.6 (1.2 to 2.1) 0.003

Oral hygiene Excellent 156 1 – 1 0.99

Average/Poor 185 1.4 (1.0 to 1.2) 0.08



Side Right 162 1 – 1 0.64

Left 179 0.8 (0.6 to 1.1) 0.19

Jaw Upper 152 1 – 1 0.45

Lower 189 0.8 (0.6 to 1.0) 0.07

Eruption age < 2 y 64 1 – 1 0.77

>2 y 277 1.2 (0.8 to 1.7) 0.31


Sound 15 0.3 (0.2 to 0.6) 0.001 1 0.08






Sound/Caries Enamel 31 0.7 (0.4 to 1.2) 0.16 0.7 (0.4 to 1.2) 0.21

DEJ/Caries <1/3 D 209 0.6 (0.4 to 0.9) 0.009 0.6 (0.4 to 0.8) 0.002

Caries >1/3 D 101 1 – 1 –

Caries location Central fossa 141 1 – 1 –

Mesial fossa 32 1.4 (0.8 to 2.7) 0.27 1.5 (0.8 to 2.8) 0.18

Distal fossa 105 1.6 (1.1 to 2.5) 0.02 1.8 (1.1 to 2.8) 0.01

Multiple fossae 63 1.7 (1.1 to 2.5) 0.01 2.0 (1.3 to 3.1) 0.003



Fissure sealant brand Delton LC 179 1 – 1 –

Clinpro Sealant 18 0.9 (0.7 to 1.1) 0.17 0.6 (0.5 to 0.8) <0.001

Grandio Seal 16 0.6 (0.2 to 1.3) 0.19 0.5 (0.2 to 1.2) 0.14

Helioseal Clear 34 0.8 (0.6 to 1.1) 0.25 0.6 (0.4 to 0.9) 0.01

Helioseal F 48 1.1 (0.7 to 1.7) 0.57 1.2 (0.8 to 1.7) 0.48

UltraSeal XT 46 0.7 (0.4 to 1.0) 0.05 0.6 (0.4 to 0.9) 0.01

Aim 2 All Kinds of Retreatment of Sealings (n = 165 events)

Variable Category


nHazard Ratio

(CI) P ValueHazard Ratio

(CI) P Value

Table 2.(continued)

(continued)


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Sex Male 161 1 – 1 0.39

Female 180 0.7 (0.4 to 1.1) 0.11

Caries risk Low 149 1 – 1 0.49

Average/High 192 1.7 (1.2 to 2.4) 0.002

Oral hygiene Excellent 156 1 – 1 –

Average/Poor 185 1.7 (1.4 to 2.4) 0.008 1.8 (1.3 to 2.7) 0.001



Side Right 162 1 – 1 0.29

Left 179 0.7 (0.5 to 1.1) 0.10

Jaw Upper 152 1 – 1 0.29

Lower 189 0.7 (0.5 to 1.0) 0.07

Eruption age < 2 y 64 1 – 1 0.81

>2 y 277 1.2 (0.8 to 1.7) 0.17


Sound 15 0.5 (0.2 to 1.3) 0.14 1 0.52






Sound/Caries Enamel 31 0.9 (0.5 to 1.7) 0.76 1 0.38

DEJ/Caries <1/3 D 209 0.7 (0.4 to 1.2) 0.23

Caries >1/3 D 101 1 –

Caries location Central fossa 141 1 – 1 –

Mesial fossa 32 0.9 (0.3 to 2.9) 0.91 0.9 (0.3 to 2.6) 0.79

Distal fossa 105 1.7 (1.0 to 2.8) 0.04 1.8 (1.1 to 2.9) 0.03

Multiple fossae 63 2.0 (1.1 to 3.9) 0.03 2.5 (1.3 to 2.9) 0.009



Fissure sealant brand Delton LC 179 1 – 1 –

Clinpro Sealant 18 0.6 (0.3 to 1.3) 0.23 0.5 (0.3 to 0.7) 0.002

Grandio Seal 16 0.7 (0.2 to 2.1) 0.49 0.6 (0.2 to 2.3) 0.48

Helioseal Clear 34 0.7 (0.4 to 1.2) 0.20 0.5 (0.3 to 0.9) 0.02

Helioseal F 48 1.1 (0.6 to 2.0) 0.83 1.0 (0.6 to 1.8) 0.94

UltraSeal XT 46 0.7 (0.4 to 1.3) 0.20 0.6 (0.4 to 1.1) 0.09

Influences of predictor variables on replacement of sealings by restorations (Aim 1), all kinds of retreatment of sealings (Aim 2), and caries progression beneath sealings (Aim 3). Bold P values indicate P < 0.05. 95% CI, 95% confidence interval; DEJ, dental-enamel junction.

Aim 3 Caries Progression Beneath Sealings (n = 95 events)

Variable Category


nHazard Ratio

(CI) P ValueHazard Ratio

(CI) P Value

Table 2.(continued)


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Table 3.Bi- and Multivariate Analyses of 152 Restorations after 7 y.

Aims 2 and 3All Retreatments of

Restorations (n = 11 Events)Caries Progression Beneath Restorations (n = 5 Events)

Variable Category n

Bivariate Bivariate



Municipality Low caries risk 37 1 – NA NA



Sex Male 71 1 – 1 –

Female 81 1.0 (0.3 to 3.4) 1.00 1.2 (0.2 to 6.9) 0.83

Caries risk Low 86 1 – NA NA

Average/High 66 0.5 (0.1 to 1.8) 0.30

Oral hygiene Excellent 79 1 – NA NA

Average/Poor 73 0.6 (0.2 to 2.3) 0.48



Side Right 61 1 – 1 –

Left 91 0.8 (0.2 to 2.6) 0.70 2.7 (0.3 to 21.8) 0.36

Jaw Upper 55 1 – 1 –

Lower 97 1.0 (0.3 to 4.0) 1.00 2.3 (0.3 to 21.0) 0.46

Eruption age < 2 y 17 0.0 (0.0 to 0.0) <0.001 NA NA

>2 y 135 1 1


Sound 4 1 – NA NA

Enamel caries without cavity 17 1 –


Dentin caries without cavity 40 1 –

Dentin caries with cavity 35 0.5 (0.2 to 1.8) 0.30


Sound/Caries Enamel 12 0.0 (0.0 to 0.0) <0.001 NA NA

DEJ/Caries <1/3 D 89 2.4 (0.6 to 10.0) 0.22

Caries >1/3 D 51 1 –

Caries location Central fossa 54 1 – NA NA

Mesial fossa 14 3.2 (0.5 to 19.3) 0.20

Distal fossa 53 1.8 (0.4 to 7.8) 0.41

Multiple fossae 31 0.6 (0.1 to 5.5) 0.67

Treatment extension

As caries lesion 144 1 1 NA NA

Whole fissure system 8 0.0 (0.0 to 0.0) <0.001

Cavity varnish No 85 1 – NA NA

Yes 67 1.1 (0.4 to 3.2) 0.85

(continued)


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Aims 2 and 3All Retreatments of

Restorations (n = 11 Events)Caries Progression Beneath Restorations (n = 5 Events)

Variable Category n

Bivariate Bivariate



Resin coating No 58 1 – NA NA

Yes 94 0.8 (0.2 to 2.4) 0.64

Composite resin brand

Tetric Evoceram 53 1 – NA NA

Spectrum AB 48 2.5 (0.4 to 17.3) 0.35

Z100 10 6.9 (0.8 to 65.0) 0.09

HFO 11 2.2 (0.1 to 37.8) 0.58

Z250 4 0.0 (0.0 to 0.0) <0.001

Herculite 11 2.3 (0.2 to 26.4) 0.50

Charisma 13 0.0 (0.0 to 0.0) <0.001

The influences of predictor variables on retreatment or replacement of restorations (Aim 2); and caries progression beneath restorations (Aim 3). Bold P values indicate P < 0.05. 95% CI, 95% confidence interval; NA, not available; DEJ, dental-enamel junction.

Table 3.(continued)

Figure 1. Patient case. Registrations at baseline in 2008. Clinical assessment: dentin lesion without cavity formation in distal fossa of tooth #61. No clinical photo available. Radiographical assessment: less than one-third in dentin. Treatment after randomization: resin sealing. Registrations during 6 y follow-ups. Clinical assessments: intact sealing. Radiographical assessments: no caries progression. Treatment: none.

more frequent in females. Caries lesions were most often located in the central fossa in lower jaw molars and in the distal fossa in upper jaw molars. Ninety-

two percent of the 382 first molars v. 51% of the 130 second molars were treated more than 2 y after eruption. As a possible result of this difference, 55%

of first molars but only 35% of second molars were clinically assessed with dentin lesions at baseline (P < 0.001). Also, there was a correlation between the


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radiographical depth of lesions and tooth type (P = 0.003).

Drop Outs

The 40 drop outs were equally distributed among sealings and restorations (P = 0.43), with no significant association to predictor variables (P = 0.21 to 0.95).

Overall Results, 0 to 7 y

The flow chart summarizes the annual numbers and reasons for completions and drop outs in the 2 treatment groups. After an average observation period of 7 y (1.8 to 8.1 y), 31% of the original 368 sealings were replaced by restorations; 46% were completed due to age, and 3% due to primary caries; drop-out accounted for 8%; and 12% were still under observation (Table 1). Of the original 153 restorations, 7% were replaced; 59% were completed due to age, and 5% due to primary caries; drop out accounted for 8%; and 21% were still under observation. The figures for the 27 excluded sealings reflect the figures for the whole sample (P = 0.55) and for the 341 sealings included in the analyses (P = 0.53). No harm or side effects of treatments were reported during the

follow-up period. Figure 1 illustrates a patient case followed for 6 y.

Survival Analyses, 0 to 7 y

Kaplan–Meier survival curves with corresponding CIs are depicted graphically for sealings and restorations. Failure rates are based on results obtained during the first 7 y. For sealings replaced by restorations (Fig. 2a), the 75% survival probability was 3.7 y (CI, 2.9 to 4.4 y), the 50% survival time was 7.3 y (CI, 6.4 y to NA), and the annual failure rate was 6.4% (CI, 5.1% to 7.7%). For retreatment of sealings (Fig. 2b), the 75% survival probability was 2.1 y (CI, 1.9 to 2.5 y), the 50% survival time was 4.9 y (CI, 4.0 to 5.9 y), and the annual failure rate was 9.0% (CI, 7.9% to 10.1%). The 75% and median survival times for retreatments of restorations could not be estimated (>7 y), but the annual failure rate was 1.3% (CI, 0.6% to 2.1%). For caries progression of sealed lesions (Fig. 2c), the 75% survival time was 4.1 y (CI, 3.4 to 5.4 y), the 50% survival time for progression could not be estimated (>7 y), but the annual failure rate was 6.1% (CI, 4.7% to 7.4%). The 75% and median survival times for caries progression beneath restorations could not be

estimated (>7 y), but the annual failure rate was 0.7% (CI, 0.1% to 1.4%).

Bi- and Multivariate Analyses of Sealings, 0 to 7 y

Bivariate analyses of sealings replaced by restorations (109 events) showed a statistically significant influence of caries risk, oral hygiene, tooth type, jaw, clinical assessment, radiographical assessment, and caries location (Table 2). Only oral hygiene and tooth type were of significance in the multivariate analysis with best results seen for patients with excellent oral hygiene and for second molars.

Bivariate analyses of retreatment of sealings in terms of repair/renewal/replacement by restoration (165 events) showed a statistical influence of caries risk, tooth type, clinical assessment, radiographical assessment, caries location, and brand of fissure sealant. The same predictor variables, except clinical assessment, were significant in the multivariate analysis. Patients with average/high caries risk, lesions in first molars, and lesions located in distal fossa or multiple fossae showed increased failure rates. Lesions located around the DEJ and limited to the outer one-third

Figure 2. Cumulative survival curves for (a) sealings replaced by restorations; (b) all types of retreatments of sealings and restorations; and (c) caries progression beneath sealings and restorations. The 7-y survival results with corresponding 95% confidence intervals are marked with arrows on the ordinates. The 75% and 50% survival times with corresponding 95% CIs are marked with arrows on the abscissa. Survival curves for sealings are in green, and restorations in blue.


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of the dentin had the lowest failure rate. The fewest retreatments were recorded for sealings in Clinpro Sealant, Helioseal Clear, and UltraSeal XT.

Caries progression was registered beneath 28% (95 events) of sealed lesions, of which 92% were replaced by restoration and 8% repaired or renewed. Bivariate analyses showed a significance of caries risk, oral hygiene, tooth type, and caries location. The same variables, except for caries risk, were significant in the multivariate analysis. Caries progression was most often recorded in patients with average or poor oral hygiene, lesions in the first molars, and lesions located in the distal fossa or multiple fossae. The fewest cases of caries progression were registered beneath sealings in Clinpro Sealant and Helioseal Clear.

Bivariate Analyses of Restorations, 0 to 7 y

Of the 152 restorations included in the analyses, 7% (11 events) were repaired or replaced by a new restoration (Table 3). Eruption age, radiographical assessment, treatment extension, and brand of composite resin showed a significant effect, with best results seen for treatments performed 2 or less years after tooth eruption, lesions without dentin extension, restorations extended to whole fissure system, and when using Z250 or Charisma composite resins. Caries progression was registered beneath 3% (5 events) of the restorations, and they were all replaced. Only a few predictor variables could be analyzed for the influence on caries progression, and no significant effects were found.

Discussion

The 7-y results of the present study reveal that dentin caries lesions on occlusal surfaces in young permanent teeth can be treated by sealing, such that restorative treatment can be postponed or avoided. The median survival time until restoring sealed lesions was 7.3 y (CI, 6.4 y to NA) even though all lesions were assessed as requiring restorative treatment at baseline. Additionally,

the effectiveness of sealings in halting the progression of dentin lesions was documented, with a median survival more than 7 y. From this perspective, it is interesting that the clinical severity of the lesions, including the presence of cavity formation, had no significant influence on the longevity or effectiveness of the resin sealings. In contrast, the radiographical depth of the lesion significantly influenced the longevity of the sealing, with the best results seen for shallow dentin lesions.

Because of missing observations and low numbers of treatments in specific groups, 27 sealings and 1 restoration had to be excluded in the multivariate and survival analyses. The fate of these 27 sealings was almost identical to the fate of the sealings included in the analyses. Thus, bias from exclusions was controlled, and the results are representative of the whole sample.

Considering the generalization of our results, much effort was put into the study design. We aimed to reflect a broad spectrum of patient-, treatment-, and operator-related variables of significance for caries development and treatment. Therefore, municipalities with different caries experience of 12-y-olds, fluoride concentration in the drinking water, and family income were included. All 68 dentists from the 9 municipalities participated in the study with their diverse patient populations, personal skills, and years of experience. The external validity of the results was further improved because only one treatment was performed in each patient, ensuring independent results. During the recruiting phase, the clinicians participated in discussions concerning diagnostic assessment of caries lesions, appropriate time for operative interventions, suitable procedures for sealing of occlusal fissures, and the use of the designed registration forms, including classification of the clinical and radiographic extension of caries lesions. Thus, the clinicians in this study adhered to the requirements for participating in a controlled clinical trial, although we did not calibrate the dentists’ diagnostics concerning

caries lesions or quality of sealings and restorations. The use of available indices for assessments of oral hygiene and caries risk might have improved the assessments but would also have been time consuming, and calibration would be necessary. Therefore, we chose to rely on the clinical impression of the clinicians, and used a 3-point graduation that highlighted outstanding individuals in both directions. Also, we decided not to interfere with the dentist’s choice of resin sealant and resin restorative. The study design, therefore, implies the benefits of a practice-based setting without compromising the demands and advantages of the classical, randomized, clinical trial. During the follow-up period, we were confronted with a replacement of clinicians and the upgrade of the radiographic equipment from analogue to digital systems. These challenges were discussed at annual meetings, at which preliminary results from the study were presented, and they were met by internal approaches in the PDHCS.

The experience concerning resin sealing of dentin caries is sparse, and previous trials were mostly performed in the last quarter of the 20th century, which implies the use of predecessor types of resin materials and methods (Simonsen and Neal 2011; Kuhnisch et al. 2012). Moreover, present information about factors of significance for the survival of sealings is mostly derived from studies on preventive sealing of sound occlusal surfaces as well as therapeutic sealing of occlusal enamel caries (Llodra et al. 1993; Kuhnisch et al. 2012).

The multivariate analyses used in this study were useful in singling out patient-, lesion-, and treatment-related variables that significantly affected the survival of the sealings (Table 2). The assessments of patients’ caries risk and oral hygiene were subjective and the cut-off points for their categorization might be influenced by the general level in each municipality. However, these patient-related variables showed a significant influence on all 3 survival outcomes for sealings, in accordance with recent findings on the retention of sealings in relation to caries


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risk status of children (Azarpazhooh and Main 2008; Oulis and Berdouses 2009; Splieth et al. 2010; Ahovuo-Saloranta et al. 2013). On the contrary, municipality and sex of the child did not show up among the significant variables in bi- or in multivariate analyses.

A recent Danish field trial of resin-based and glass-ionomer fissure sealants showed that more posterior teeth required higher rates of retreatment (Poulsen et al. 2006). In contrary, a study on sealing caries lesions in adults showed no influence of tooth type (Oulis and Berdouses 2009) and the present study showed significantly better results for second molars as compared with first molars. These divergences are difficult to explain. The age of the patient might be important because of difficulties associated with performing optimal treatment in younger children due to the small work-field and the lack of compliance and maturity. However, the average age of patients for sealing first molars was 12 y, just 2 y less than the average age for sealing second molars. Accordingly, more second molars than first molars were sealed during the 2-y eruption period, where a dry work-field may be difficult to obtain without the use of a rubber dam. So, the worse outcome for first molars might be related to lesion extension rather than tooth type or patient age. This assumption is supported by the significance of clinical and radiographical assessments of caries lesion, whereas eruption age was not associated with the outcomes (Table 2). In accordance with previous studies, the few clinically sound surfaces showed increased retention of sealings as compared with demineralized, carious surfaces (Bakhshandeh et al. 2012), but it is notable that cavity formation had no influence on the results. We did note an influence of the brand of fissure sealant but no difference between transparent and opaque sealants was observed (Table 2). These findings lack support in the literature. Because we did not randomize the choice of material, the ranking of the sealants must be taken with reservation, and these findings need to be confirmed in future clinical trials.

As expected the survival of restorations was markedly better than that of sealings. The annual failure rate was 1.1% for restorations and 8.3% for sealings. These figures correspond well with previous results (Manhart et al. 2004; Simonsen and Neal 2011; Demarco et al. 2012; Kuhnisch et al. 2012; Ahovuo-Saloranta et al. 2013; Qvist 2015). Considering, that all sealings in the present study were performed on caries lesions, which otherwise would have been restored, it is notable that the survival is in line with results from previous studies on sealings used on sound surfaces or enamel caries (Ahovuo-Saloranta et al. 2013).

Due to the few failures of restorations, only bivariate analyses were made, showing that eruption age, radiographical depth of the lesion, treatment extension, and restorative material influenced the need for retreatment. However, the superior survival of restorations performed during the 2-y eruption period and of extended restorations is surprising and not in accordance with previous studies (Manhart et al. 2004; Demarco et al. 2012).

The overall aim of the present study was to improve dental health in children and adolescents by postponing or avoiding restorative intervention of occlusal caries lesions in young permanent teeth. From this perspective, it is important to underline that the 50% of sealed lesions that remained sealed after 7.3 y will not necessarily end up being restored. The positive results concerning the longevity and effectiveness of sealings thus emphasize that criteria for non-invasive sealing of occlusal lesions can be extended to include dentin caries lesions. However, sealing deep dentin lesions often results in replacement by restorations because of caries progression. In the present study, caries progression was assessed subjectively by the clinicians by pairwise comparison of pre- and post-treatment bitewings. Where patients presented with deep lesions, the assessment might have been influenced by a fear of pulpal complications due to rapid progression, because sealing of dentin caries is a new

approach in the PDHCS in Denmark. Therefore, there is an obvious need for verifying the subjective assessments of caries progression using a recently developed method for measuring the radiographical extent of dentin caries lesions (Bakhshandeh et al. 2011).

Conclusion

We conclude it is possible to postpone restorative intervention of occlusal dentin caries lesions in young permanent teeth by non-invasive sealing and thereby improve tooth longevity. Although all lesions required restorative treatment at baseline, more than half of the sealed lesions still did not require restoration after 7 y. However, profound dentin lesions should not be sealed. Other conditions, such as the habits and caries risk of patients and the possibilities of regular follow-ups, will also affect whether sealing is the optimal treatment. The failure rate of sealings is higher than that of restorations, and failed sealings often lead to caries progression. Therefore, clinical and radiographical follow-up of sealed lesions is necessary to evaluate the quality of the sealing and the progression of the lesion, with 1 to 3- and 5-y follow-ups recommended.

Author Contributions

V. Qvist, contributed to conception, design, data acquisition, analysis, and interpretation, drafted and critically revised the manuscript; M.K. Borum, K.D. Møller, T.R. Andersen, contributed to conception, design, and data acquisition, critically revised the manuscript; P. Blanche, contributed to data analysis and interpretation, critically revised the manuscript; A. Bakhshandeh, contributed to data acquisition, analysis, and interpretation, drafted and critically revised the manuscript. All authors gave final approval and agree to be accountable for all aspects of the work.

Acknowledgments

The authors thank biotechnologist Ulla Larsen for her persistent effort in assembling clinical registration forms


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and radiographs and organizing annual meetings for participants. We express our gratitude to associate professor Dennis Pipenbring and associate professor Jakob Hermann for their invaluable contribution in preparing the database and preliminary data analyses. Professor Torben Martinussen is also thanked for his support to the statistical analyses. We express our gratitude to the participating children and adolescents, parents, and to the chief dental officers, dentists and other staff members at the Public Dental Child Health Service in Allerød, Gentofte, Helsingør, Herlev, Hillerød, Høje-Taastrup, Hørsholm, Lyngby-Taarbæk, and Nordfyn municipalities for making this study possible. The authors also acknowledge 3M ESPE, Danish Employees Dentists Organization, Ivoclar Vivadent, Stiftelsen Patentmedelsfonden för Odontologisk Profylaxforskning and VOCO for donation of materials and/or financial support for presentations of preliminary results from the study at annual meetings and congresses. The authors declare no potential conflicts of interest with respect to the authorship and/or publication of this article.

NotesThis trial was registered at ClinicalTrials.

gov (NCT02573090). Ethical approval was obtained from The Research Ethics Committee for Copenhagen and Frederiksberg municipal-ities, Denmark (J.no. KF 03 324580) and the Danish Data Protection Agency (J.no. 2006-41-7099). The full trial protocol can be accessed by contacting the corresponding author.

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