Comparative Study on the Outcomes of Restoring Untreated and SDF-treated Dentine Caries Lesions in Primary Teeth of Preschool Children
Phase: NA
Conditions: Dental Restoration Failure of Marginal Integrity
Sponsor: The University of Hong Kong

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Study title:  
Comparative study on the outcomes of restoring untreated and SDF-treated 
dentine caries lesions in primary teeth of preschool children 
 
Protocol version:  2 
 
Date: 27 July, 2017 
 
Approved by:  the IRB of the University of Hong Kong and Hong Kong Hospital Authority 
Hong Kong West Cluster on June 6, 2017 
 
 
  Reference number: UW 17-180 
 
 

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Study title 
Comparative study on the outcomes of restoring untreated and SDF-treated dentine caries 
lesions in primary teeth of preschool children 
 
Investigators 
Prof. Edward C. M. Lo (Faculty of Dentistry, University of Hong Kong) 
Prof. May C. M. Wong (Faculty of Dentistry, University of Hong Kong) 
Prof. C. H. Chu (Faculty of Dentistry, University of Hong Kong) 
Dr. M. Jiang (Faculty of Dentistry, University of Hong Kong) 
 
 
 
Summary 
 
Untreated dental caries is common among preschool children in Hong Kong. When the caries 
extends into dentine of the tooth and a carious cavity is formed, removal of the decayed dental 
tissues followed by placement of a dental restoration (filling) is the conventional treatment. 
Atraumatic restorative treatment (ART) is an established practice to place a dental restoration 
using hand instruments only and adhesive filling material. It can be used in outreach dental 
service in a field setting and is appropriate for young children as no injection of local anesthesia 
is needed. Recently, topical application of silver diamine fluoride (SDF) solution is used to halt 
or arrest the progression of dentine caries and to promote remineralization of the caries lesion. 
A disadvantage of this treatment is that the arrested caries lesion will be stained black in colour.  
 
The primary objective of this proposed clinical study is to compare the success rates of ART 
restorations placed in untreated and SDF-treated dentine caries lesions in primary teeth. The 
secondary objective is to describe the change in parents’ satisfaction with the aesthetics of their 
child’s teeth and the change in oral health-related quality of life of preschool children before 
and after placement of ART restorations. 
 
The study population is preschool children attending kindergartens in different districts in 
Hong Kong. It is planned to recruit around 10 kindergartens. All children attending grade 1 in 
these kindergarten will be invited to receive a free dental examination and have their decayed 
primary teeth restored, if possible, in the kindergarten by dentists. Parental informed consent 
will be obtained before the dental examination and treatment. The planned sample size is 152 
children with 396 decayed primary teeth needing restorations. Around half of these teeth, 
assigned randomly will received SDF treatment around 10 weeks before receiving the 
restoration. The restored teeth will be re-examined every 6 months for 24 months to assess the 
treatment outcome. Parents of the study children will be asked to complete a questionnaire at 
baseline, 6 months and 24 months so as to obtain data on their satisfaction with the aesthetics 
of their child’s teeth and the oral health-related quality of life of the study children. 
 
 

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Background 
 
Dental caries of young children is common in both developing and industrialized countries 
(Petersen et al., 2016). In Hong Kong, the prevalence of dental caries among 5-year-old 
children is around 50% (Department of Health, 2013). The adverse effects of dental caries can 
impact on both children and their families, including significant health, social and economic 
consequences (Colak et al., 2013). 
 
Previous studies have shown that topical application silver diamine fluoride (SDF) solution is 
effective  in arresting dental caries in young children (Chu et al., 2002; Yee et al., 2009; Zhi et 
al., 2012; Duangthip et al., 2016). A considerable drawback of SDF application is the black 
stain on the arrested caries lesions, which may cause dissatisfaction of both children and their 
parents with aesthetics of the treated teeth (Gao et al., 2016). It was suggested that by applying 
a saturated solution of potassium iodide (KI) immediately after the application of SDF, would 
minimize the black stain on the dentin caries lesions (Knight et al., 2006). However, a long 
term clinical study on elders has shown that the application of KI cannot reduce the blackening 
of arrested dentine caries lesions from SDF treatment (Li et al., 2016). 
 
Atraumatic restorative treatment (ART), which was first developed in the 1980s, embodies the 
minimal intervention philosophy of dental caries management. The ART procedures involve 
removal of soft carious dental tissues using hand instruments and placement of a restoration 
using adhesive dental material, normally high viscosity glass ionomer cement (GIC) 
(Holmgren et al., 2013). Clinical evidence shows that ART is a patient-friendly and cost-
effective treatment, especially for young children (Tedesco et al., 2016).  
 
Although ART is considered as a satisfactory option for treatment of decayed primary teeth, it 
may still be difficult to obtain good cooperation from young children during operative 
procedures. Using SDF application to arrest active dentine caries in the primary teeth of young 
children may be a more practical management method. When children grow older and become 
more cooperative, the SDF-arrested caries lesion can then be restored with ART, so as to 
improve esthetics of the decayed teeth. Furthermore, it is expected that placement of a 
restoration on an arrested caries lesion is easier and quicker than that on an active caries lesion. 
The amount of demineralized dental tissues which needs to be removed will also be less, and 
the bond strengthen between glass ionomer and remineralized dentine may be higher. Thus, it 
is hypothesized that the success/retention rate of ART restorations placed in decayed teeth 
which has been treated with topical application of SDF is higher than that of restorations placed 
in untreated decayed teeth. 
 
In order to find out and compare the outcomes of restoring active dentine caries lesions and 
those of restoring SDF-treated dentine caries in primary teeth, a well-designed clinical trial is 
needed. Results of the trial will provide high quality evidence to guide dental clinicians in 
treating dentine caries in primary teeth of young children.  
 
 
 
Objectives 
 
1. To describe the success rate of restorations placed using the atraumatic restorative 
technique (ART) in untreated dentine caries lesions in primary teeth 
 

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2. To describe the success rate of ART restorations placed in dentine caries lesions in primary 
teeth previously treated by topical application of silver diamine fluoride (SDF) solution  
 
3. To compare the success rate of ART restorations placed in untreated and SDF-treated 
dentine caries lesions in primary teeth 
 
4. To describe parents’ satisfaction with the aesthetics of their child’s teeth before and after 
placement of ART restorations 
 
5. To describe the change in oral health-related quality of life of preschool children before 
and after placement of ART restorations 
 
 
 
Materials and Methods 
 
Study design 
 
This study is a clinical interventional study with two parallel groups. The ICH-GCP principles 
will be followed. 
 
 
Study subjects and recruitment 
 
The study population of this proposed study is Hong Kong preschool children attending grade 
1 of kindergarten (aged 3-4 years). Around 10 kindergartens in different districts of Hong Kong 
will be selected. All children attending grade 1 in the selected kindergartens will be invited to 
join this study. An invitation letter with information on the purpose and procedures of the study 
will be sent to the parents of the children through the kindergarten. The parents will be asked 
to give written consent for allowing their child to receive a free oral examination and ART 
restorations, if indicated for treating the decayed primary teeth in their child’s mouth, provided 
by dentists in the kindergarten. Parental consent will be obtained before inclusion of a child in 
this study.  
 
Inclusion criteria 
 
Generally healthy children who have at least one decayed primary tooth with a cavity into 
dentine. 
 
Exclusion criteria  
 
Children with serious systemic diseases/conditions or who are uncooperative during treatment 
will be excluded. Teeth with signs of pulpal pathology, such as having an abscess or 
discoloured, will be excluded. Caries lesions which do not have adequate access for hand 
instruments to prepare the cavity for a filling and those that were treated with SDF solution but 
with most parts still being active, i.e. easily penetrated by a blunt probe with light force, will 
also be excluded. 
  
 
Sample size 

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Sample size calculation is based on the primary outcome of this study which is the success of 
ART restorations, defined as restoration present without major defects nor associated active 
caries. According to a recent systematic review, the two-year survival rate of ART restoration 
placed in primary teeth is around 70% (Tedesco et al. 2016). It is anticipated that the survival 
rate of ART restorations placed on arrested caries is slightly higher at 75%. An absolute 
difference of 10% in the success rate of restorations is regarded as clinically significant. In this 
non-inferior clinical trial, using one-tailed test with a statistical significance set at 2.5% and a 
power of 80%, the calculated minimal number of restorations needed in each group is 139 
(http://powerandsamplesize.com/).  
 
Since more than one caries lesion can be found in a child’s mouth, the clustering effect on 
sample size needs to be considered. Results of the latest oral health survey of Hong Kong 5-
year-old children showed that the mean number of untreated decayed primary teeth for children 
who had dental caries was 4.7 (Department of Health, 2013). In this sample size calculation, it 
is anticipated that the number of decayed teeth included per study child is 2.5. A design effect 
of 1.15 is calculated, using an assumed intra-class correlation roh of 0.1. Thus, the necessary 
sample size would need to be multiplied by 1.15 and become 160. Furthermore, to compensate 
for a possible drop-out rate of 15%, the initial sample size is increased to 188 restorations per 
group. Therefore, 76 children in each group children will be recruited at baseline and the total 
number of study children will be 152. 
 
    
Placement of ART restorations 
 
Cavitated caries lesions in the primary teeth of the study children will be restored following 
the ART procedures (Holmgren  et al., 2013). The instruments used are LED illuminated dental 
mirror, sickle probe, tweezers, hatchet, excavators and flat plastic. The dental restorative 
material used is a high-strength chemical-cured glass ionomer (Ketac-molar, 3M ESPE, 
Germany).  
 
The step-by-step ART procedures are briefly described below:  
1. isolate the operation site by cotton rolls 
2. gain adequate access to the cavity, if necessary a hatchet is used to enlarge the opening of 
a small cavity 
3. excavators of different sizes are used in removing soft carious tissues and preparing the 
cavity for a filling 
4. the cavity is cleaned by water and then dried 
5. condition the cavity surface with a weak organic acid, then wash and dry the cavity 
6. the glass ionomer material is mixed according to manufacturer’s instructions 
7. the filling material is placed and pressed into the cavity 
8. excess filling material is removed  
9. contour and shape of the restoration is modified as necessary and occlusion checked 
10. the finished restoration is covered by a layer of varnish or petroleum jelly 
 
 
Baseline and follow-up data collection 
 
At the baseline, all children with parental consent will be clinically examined in the 
kindergarten. Disposable dental mirror attached to a handle with an intra-oral LED light and a 

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ball-ended probe will be used. The status of each tooth will be recorded. Children who have at 
least one decayed primary tooth with a cavity into dentine will be included into the study. All 
decayed teeth in the children will be restored, except those with inadequate access and those 
with signs of pulpal pathology. Around half of these decayed teeth will receive topical 
application of a SDF solution (Saforide, Toyo Chemical, Japan), through simple random 
allocation on a child basis using random numbers, around 10 weeks before receiving the 
restoration. The time used for placement of each restoration will be recorded to the nearest 
minute. 
 
The children will be examined at 6, 12, 18 and 24 months after placement of ART restorations 
by calibrated examiners who are not involved in the placement of the restorations. The same 
instruments used in the baseline examination will be used in the follow-up examinations. The 
status of the restorations and restored teeth will be assessed and recorded using codes and 
criteria commonly adopted in previous clinical studies of ART restorations (Lo et al., 2007): 
0 =  restoration present, no caries, no marginal defects or wear  
1 =  restoration present, no active caries, slight defects or wear not greater than 0.5 mm 
2 =  restoration present, marginal defects greater than 0.5 mm 
3 =  restoration present, wear greater than 0.5 mm 
4 =  restoration present, active caries found associated with the filling 
5 =  restoration missing, no active caries, surface hard to gentle probing 
6 =  restoration missing, active caries found, surface soft to probing allowing penetration 
of the tip of a blunt probe 
7 =  tooth with signs of pulpal pathology 
8 =  tooth missing, extracted due to caries 
9 =  tooth naturally exfoliated  
 
At baseline, information on the children’s oral hygiene practice, snacking habit, oral health 
related quality of life, and parental satisfaction with the appearance of their child’s teeth will 
be collected by a self-completed questionnaire. A validated tool for measuring oral health 
related quality of life of preschool children in Hong Kong, Chinese version of Early Childhood 
Oral Health Impact Scale (ECOHIS), will be used (Lee et al., 2009). The same measurement 
tool will be used at the 6-month and 24-month follow-up.  
 
 
Primary outcome measure 
 
The primary outcome measure in this clinical study is the success of the ART restorations 
placed. A restoration is classified as success when it is retained on the tooth without major 
defects or wear and has no associated active caries (codes 0 and 1). Under this condition, no 
further treatment is necessary. A restoration is classified as failed when it has major defects 
(codes 2 and 3), associated active caries (code 4), is missing (codes 5 and 6) or the tooth has 
signs of pulpal pathology (code 7) or extracted due to caries (code 8). Under these conditions, 
further treatment may be necessary. 
 
 
Secondary outcome measures 
 
The secondary outcome measures in this clinical study are the parental satisfaction with 
aesthetics of their child’s teeth and the oral health related quality of life of the child as measured 
by the ECOHIS before and after placement of ART restorations. 

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Data analysis 
 
The clinical examination record form and parental questionnaires will first be checked for 
completeness and obvious errors. Questionnaires with more than 40% of the questions 
unanswered will be discarded. The collected data will be entered into computer. Data entry and 
logical errors will be corrected before data analysis. 
 
Basic data analysis will be carried out by using the statistical software SPSS for Windows. Chi-
square test and t-test will be performed to assess the comparability between the children in the 
two study groups regarding their demographic background, oral health related behaviours and 
baseline dental caries experience. McNemar's test and paired t-test will be used to assess the 
change in parental satisfaction with aesthetics of their child’s teeth and the change in ECOHIS 
score before and after placement of ART restorations. 
 
Clinical outcome of an ART restoration at each follow-up examination will be classified as 
either success or failed according to the criteria mentioned above. A two-level survival analysis 
for interval-censored data will be adopted. The first level is the caries lesion while the second 
level is the child. This analysis will account for the correlation (clustering) between 
observations of multiple restorations placed in the same child (Wong et al., 2006). This 
analyses will be carried out with the statistical software SAS for Windows (SAS Institute Inc., 
Cary, N.C., USA). The level of statistical significance for all tests will be set at 0.05. 
 
 
References 
 
1. Chu CH, Lo ECM, Lin HC (2002). Effectiveness of silver diamine fluoride and sodium 
fluoride varnish in arresting dentin caries in Chinese pre-school children. Journal of Dental 
Research 81:767-770. 
 
2. Colak H, Dulgergil CT, Dalli M, Hamidi MM (2013). Early childhood caries update: a 
review of causes, diagnoses, and treatments. Journal of Natureal Science, Biology and 
Medicine 4:29-38. 
 
3. Department of Health (2013). Oral Health Survey 2011. Hong Kong: Government Printer. 
 
4. Duangthip D, Chu CH, Lo ECM (2016). A randomized clinical trial on arresting dentine 
caries in preschool children by topical fluorides -18 month results. Journal of Dentistry 
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7. Knight GM, McIntyre JM, Craig GG, Mulyani. (2006). Ion uptake into demineralized 
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