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Survival of ART and Amalgam Restorations in Permanent Teeth of Children after 6.3 Years
1 WHO Collaborating Centre for Oral Health Care Planning and Future Scenarios, Radboud University Medical Centre, College of Dental Sciences, PO Box 9101, 6500 HB Nijmegen, the Netherlands; Correspondence: * corresponding author, j.frencken{at}dent.umcn.nl
The null hypothesis tested was that there is no difference in the survival percentages of all restorations placed through the Atraumatic Restorative Treatment (ART) approach, with high-viscosity glass ionomer, and those produced through the traditional approach, with amalgam (TA), in the permanent dentitions of children after 6.3 years. Using a parallel group design, we randomly assigned a total of 370 children, aged 6 to 9 years, to the ART group and 311 children, also aged 6 to 9 years, to the TA group. Eight dentists placed a total of 1117 single- and multiple-surface restorations. The cumulative survival percentages for ART glass-ionomer restorations were statistically significantly higher than those of amalgam restorations at all time intervals except the first (p  0.044). After 6.3 years, the cumulative survival percentages of ART and amalgam restorations were 66.1% (SE = 3.1%) and 57.0% (SE = 3.3%), respectively. We concluded that the restorations produced with the ART approach, with high-viscosity glass ionomer, survived longer than those produced with the traditional approach, with amalgam, in the permanent teeth of young children.
Key Words: restorations • atraumatic restorative treatment • amalgam • glass ionomer • survival
In 1991, the school health department in the Ministry of Education in Syria attempted to improve the oral health of schoolchildren by introducing a program that was educational and preventive in orientation. Evaluation of the program after 5 yrs showed that the restorative care service was not functioning correctly (Taifour, 2002). Because the difficulties encountered by the school health department in implementing the traditional restorative care concept at the schools were caused by its high cost and dependency on electricity, it was decided to look for alternative means of providing restorative care. One of the options considered was the Atraumatic Restorative Treatment (ART) approach. This approach uses only hand instruments in combination with an adhesive restorative material, usually an auto-cured glass ionomer, and can be applied on school premises (Frencken et al., 1996). However, at the time when the inclusion of the ART approach into the oral health services was discussed (1996), only one study had been published on the effectiveness of the ART approach in comparison with the traditional approach in permanent teeth (Phantumvanit et al., 1996). Because of the lack of information on the longevity of ART restorations, the Regional WHO Centre in Damascus started a comparative randomized controlled clinical trial. The null hypothesis was that there is no difference in the survival percentages between restorations produced through the ART approach, with high-viscosity glass ionomer, and those produced through the traditional approach, with amalgam, after 6.3 years. This is the first trial comparing the two approaches over a period of more than 6 yrs.
Sampling Procedure The study protocol was approved by both the Ministry of Health and the Ministry of Education. Parental consent was obtained in writing through the school authorities. A convenience sample of grade 2 children who ranged from 6 to 9 yrs of age was taken from 49 schools situated in the vicinity of the WHO Regional Centre in Damascus. Each child was diagnosed for dental caries by three calibrated examiners. The prevalence of dental caries in the children examined was 57.6%. The mean DMFS and DMFT scores were 1.6 and 1.4, respectively. The inclusion criteria for a child to enter the RCT were the presence of a dentinal lesion in a permanent tooth, without suspected pulp involvement, that had an opening wide enough for the smallest excavator to enter (Ø = 0.9 mm). There were no inclusion criteria set for the actual size of the cavity.
Implementation
Treatment Procedure All dentists had previously participated in a related clinical trial studying the survival of ART and TA restorations in deciduous dentitions (Taifour et al., 2002). They had ample experience in applying the ART approach. The TA procedure was known and routinely practiced by all dentists. All eligible children were randomly assigned by the principal investigator (DT) to one of the two treatments (ART or TA) with the use of a gender-stratified class list. In the case of ART, Fuji IX® was allocated in the first part (34%) and Ketac Molar® in the second part (64%) of the implementation period.
Evaluation
The same two Syrian dentists carried out the evaluation at years 1.3 and 2.3. They were unable to participate in the third year of evaluation and were replaced by two experienced evaluators from the Netherlands. The Dutch evaluators had been calibrated with their Syrian colleagues and had participated in a related evaluation (Taifour et al., 2002). One of the Syrian and one of the Dutch evaluators carried out the evaluations at years 4.3 and 6.3. The evaluators were not involved in the planning and treatment provision of the trial. The inter-evaluator consistency test was not carried out at evaluation year 2.3. The quality of the inter-evaluator consistency for assessing restoration failure and diagnosing dental caries, expressed in kappa coefficient values (Landis and Koch, 1977), was calculated (Table 2  ).
Statistical Methods A power calculation for the three-year comparison preceded the sampling procedure (Taifour et al., 2003). The principal investigator, who was not an operator, recorded the data on a case report form; they were later entered into a database at the College of Dental Sciences in Nijmegen. There, the data were checked for errors, and a biostatistician (Mv’tH) analyzed them with SPSS software (Release 6.1 version). The actuarial method was applied for estimation of the survival percentages of the ART and TA restorations over time, with the modification that restorations lost to follow-up during a period did not count in the calculations. The usual method (Greenwood, 1926), used to calculate the standard error (SE) in the cumulative survival percentages, was not appropriate in this situation, with several restorations per child. Instead, we applied the Jackknife method (where one patient is left out) (Efron, 1982), to deal with the dependency of the data and to calculate the standard errors for the survival percentages. The difference between the survival percentages of both types of restorations over 6.3 yrs was tested via the Jackknife SEs of the differences. Statistical significance was set at  = 0.05.
Disposition of Restorations In total, 681 children, 325 boys and 356 girls, with a mean age of 7.5 yrs (range, 6–9 yrs), participated in the trial. The ART group consisted of 370 children and the TA group of 311 children. The eight operators placed a total of 1117 restorations, of which 610 were made according to the ART approach and 507 were made using the TA approach. Eighty-four children with 142 restorations were never evaluated (non-participation). There was no statistically significant difference (p > 0.05) between non-participating and participating children for the background variables age, gender, treatment procedure, restorative material, and operator.
Longitudinal Assessment Series
Handling of Longitudinal Data
Comparison of Treatment Approaches
Single-surface Restorations The modified actuarial cumulative survival percentages and standard errors (SE) for single-surface restorations for both treatment approaches over the 6.3 yrs were calulated (Table 4 ). Higher survival percentages were observed for ART than for TA restorations at all intervals (Table 4). The difference between the survival percentages was statistically significant at all intervals except for the first and the third.
All possible efforts were exercised to trace the participating children at the evaluation periods. Nevertheless, a large number of children had left the primary school for an intermediate school during evaluation intervals from 4.3 to 6.3 yrs, and some had left the city. This resulted in a substantial reduction in the number of restorations evaluated during the last two evaluation intervals. The decision to opt for a parallel group design ensured that the number of restorations placed per treatment modality would differ. However, the difference in numbers of restorations placed per treatment group turned out to be larger than anticipated (NART = 539, NTA = 436). The reason for this was due to the fact that the electricity supply failed on several days. On those days, the principal investigator decided that all of the children, who had been transported to the WHO Centre for treatment, would be treated by the ART approach. We do not think that this decision biased the outcome of the study. The survival percentages were analyzed at the restoration level. This assumed independence of the survival percentages of children. We applied the Jackknife method to deal with the dependency of restoration outcomes within each child; this resulted in higher SE values than those calculated through the commonly used Greenwood (1926) method. The criteria used in the present study have been applied in most other ART studies in the permanent dentition (Frencken and Holmgren, 2004). Usually, the USPHS criteria are used for the assessment of restoration survival. Studies have shown no significant difference in survival outcomes of ART restorations that were evaluated according to both sets of criteria (Holmgren et al., 2000). Further, it has been suggested that the ART criteria are more stringent than the USPHS criteria (Lo et al., 2001). Thus, we may reasonably assume that the results of the present study are comparable with those from non-ART studies. The percentage of restorations that survived after the end of each evaluation period was higher for the ART approach than for the amalgam approach group. Despite the fact that many restorations were lost to follow-up during the last two intervals, thus decreasing the power of the trial, the differences in the percentages of survival of restorations between the two treatment approaches were statistically significant at all intervals but the first. The null hypothesis was rejected: There is a difference in the percentage of restorations that survived produced through the ART approach, with high-viscosity glass ionomer, and those produced through the traditional approach, with amalgam, after 6.3 yrs. Survival percentages for ART restorations were higher than those for amalgam restorations after 6.3 yrs. This was also found to be true with the subset of single-surface restorations that showed higher survival percentages for ART than for amalgam restorations after 6.3 yrs. The present study is the first in which ART restorations with high-viscosity glass ionomer were compared with traditionally produced restorations. The majority of the restorations were placed in single surfaces. There is one other study (in Tanzania) in which the ART approach was compared with the traditional approach, with amalgam in single surfaces in permanent dentitions, after 6 years (Mandari et al., 2003). The latter study reported no significant difference between the two approaches, but amalgam restorations performed better than ART restorations. The ART restorations in the Tanzanian study were placed by one dental therapist, who used a medium-viscosity glass-ionomer cement. Whether these two aspects contributed to the difference in final outcome between the Tanzanian and the present study is uncertain. The cumulative survival percentage (68.9%) of single-surface ART restorations after 6.3 yrs in the present study is equal to that (68.6%) reported from Tanzania (Mandari et al., 2003). In recent years, few studies have reported on the placement of single-surface amalgam restorations by multiple dentists. The median survival of one-surface amalgam restorations, placed by 22 general practitioners, has been reported to be 7.1 yrs (Mjör et al., 1997), whereas the median survival time for Class I amalgam restorations, placed by 73 dentists, has been reported to be 7.4 yrs (Burke et al., 1999). These results are in line with the 6.3-year cumulative survival percentage of single-surface amalgam restorations of 59.7% placed by eight dentists in the present study. We conclude that the restorations produced with the ART approach, with high-viscosity glass ionomer, survived longer than those produced with the traditional approach, with amalgam, in the permanent teeth of young children. We recommend the ART approach as a complement to the preventive activities in the Syrian school oral health programs.
We thank the schoolchildren, their parents, and the staff at the primary schools for their kind assistance in performing this study. We are very grateful to the staff at the WHO Regional Centre in Damascus for their co-operation and dedication to have the study run smoothly. The contributions of Dr. W. El-Sadi, Dr. M. Samman, Prof. Dr. W.H. van Palenstein Helderman, and Prof. Dr. G.J. Truin in the evaluation process are very much appreciated. We thank the Government of the Netherlands, Dental Health International Netherlands, GC Europe, and 3M ESPE (Germany) for financing the study. Received for publication May 19, 2005. Revision received March 5, 2006. Accepted for publication April 23, 2006.
Journal of Dental Research, Vol. 85, No. 7,
622-626 (2006) This article has been cited by other articles:
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