The aim of the present study was to investigate the caries-preventive effect of sealants produced with a high-viscosity glass-ionomer with an elevated powder-liquid ratio (ART), of having energy added to this glass-ionomer, and that of glass-carbomer, in comparison to that of resin composite sealants.
The randomized controlled trial covered 407 children, with a mean age of 8 years. At a school compound three dentists placed sealants in pits and fissures of high caries-risk children. Evaluation by two independent evaluators was conducted after 0.5, 1 and 2 years. The Kaplan–Meier survival method, ANOVA and t -test were used in analyzing the data.
1352 first permanent molars were sealed. 6.6% of children and 6.8% of sealants dropped out within 2 years. 27 re-exposed pits and fissures, 20 in occlusal and 7 in smooth surfaces, in 25 children, developed a dentin carious lesion. The cumulative survival of dentin carious lesion-free pits and fissures in the glass-carbomer sealant group was statistically significantly lower (97.4%) than those in the high-viscosity glass-ionomer with energy supplied (99%) and the resin-composite (98.9%) sealant groups. There was no statistically significant difference in the cumulative survival of dentin carious lesion-free pits and fissures, between the high-viscosity glass-ionomer with (99%) and without (98.3%) energy supplied sealant groups, after 2 years.
The survival of dentin carious lesion-free pits and fissures was high in all sealant types. More dentin carious lesions were observed in the glass-carbomer sealant group.
In the permanent dentition of young children, carious lesions most frequently develop in pits and fissures of 1st molars. Sealing those pits and fissures is considered the most effective way of interfering with the development of carious lesions over a long period . In a well-structured oral health service system, failed sealants can be resealed and thus continue to exercise their caries-preventive action for an indefinite period . In contrast, in low and developing market economies, where a recall system is usually unavailable, sealants, once placed, continue to function without the possibility of repair if this is needed. To ensure a high level of sealant effectiveness over long periods in such countries, a sealant material should be used that bonds to the enamel surface longer than those currently used.
Resin- and glass-ionomer-based materials are used for sealing pits and fissures. Glass-ionomer-based sealant materials have evolved from a low-viscosity type used in the seventies and eighties, to a high-viscosity type used since the mid-nineties . Not too long ago, a high-viscosity glass-ionomer with an elevated powder-liquid ratio was marketed. This was assigned higher physical–mechanical properties, including a higher level of adhesion to enamel, than the previous ones . Changing the application procedure by adding heat to the setting high-viscosity glass-ionomer through the use of a high energy curing light, was also found to increase the retention, and consequently the longevity, of sealants . An additional option for a sealant material with increased retention was introduced through the marketing of a novel glass-ionomer-based material, fluorapatite-containing glass-carbomer, with powder particles reduced to nano size .
China is a country in transition. Its economy has increased tremendously over the last decades. Although the caries prevalence and severity in permanent dentition of young children has been relatively low and stable for decades , there are signs that caries severity is increasing in 1st molars of young children . The National Association of Preventive Oral Health, recently recommended, as part of a wider program, that caries prevention in children in China should focus on the application of sealants and on self-care through plaque control with a toothbrush and fluoride-containing toothpaste.
The aim of the present study was to investigate the caries-preventive effects of high-viscosity glass-ionomer sealants with an elevated powder-liquid ratio, of having energy added to this glass-ionomer, and that of glass-carbomer, in comparison with those of resin-composite sealants. The hypotheses tested were: (1) the cumulative survival rate of caries-free pits and fissures of glass-carbomer sealants is higher than those of high-viscosity glass-ionomer sealants, with and without energy supplied, and of resin-composite, after 2 years; (2) the cumulative survival rate of caries-free pits and fissures, of high-viscosity glass-ionomer sealants with energy supplied is higher than that of high-viscosity glass-ionomer sealants without energy supplied, after 2 years.
Materials and methods
Study population and treatment allocation
The present study was conducted in 5 public schools in the urban area of Wuhan, the capital of Hubei province, China. Wuhan has a population of about 8 million people. The average income of its citizens increased from US$ 89.- in 1978, to US$ 2777.- in 2009.
The sample of subjects for the present investigation resulted from data derived from an oral health epidemiological survey of grade 2 children attending the primary schools. The sampling procedure was based on the caries experience of the children, assessed according to the ART caries criteria ( Table 1 ), and on the morphology of pits and fissures in 1st permanent molars, assessed according to the criteria described by Symons et al. . The inclusion criteria for enrolment in the treatment study were: a fully erupted first permanent molar, no dentin caries lesion in pits and fissures of these molars, deep and/or intermediate pits or fissures, and a dmft ≥ 2. For a child to be eligible for inclusion in the study, all these criteria needed to be present.
|1||B||Early enamel lesion. White/opaque or brownish/dark lesion in enamel only, including loss of tooth surface; considered as being active or inactive|
|2||C||Carious lesion involving the dentin slightly; lesion cannot be penetrated with CPI probe|
|3||D||Dentinal lesion: lesion can be penetrated with CPI probe|
|4||E||Dentinal lesion: pulp possibly or definitely exposed|
|7||H||Missing due to caries|
|8||8||Unerupted permanent tooth|
|9||9||Unable to make diagnosis|