K.L. Weerheijm

Bacterial Counts in Carious Dentine under Restorations: 2–Year in vivo Effects

Little is known about the long–term effects of fluoride–releasing materials on carious dentine in vivo. The aim was to investigate the 2–year influence of a resin–modified glass ionomer cement (RM–GIC) and amalgam on the bacteriological counts of carious dentine that remained under class I restorations. To enable a split–mouth design, 33 molar pairs in 33 patients (mean age 15.1 years, SD 1.4) were selected, based on clinically and radiographically diagnosed occlusal dentine caries. The enamel of the carious molars was removed, and the carious dentine was sampled under aseptic conditions just beneath the dentinoenamel junction. The molars were alternately restored with RM–GIC or amalgam without further removal of carious dentine. The samples were processed for microbiological determination of total viable counts (TVC), mutans streptococci (MS), and lactobacilli (LB). The molar pairs of 25 patients were reevaluated after 2 years using the same clinical techniques and were permanently restored after complete caries removal. Both materials showed a substantial decrease in numbers of TVC and LB of the carious dentine after the 2–year period. Compared to amalgam, the decrease in the numbers of LB was significantly more pronounced for RM–GIC. No microorganisms were detected in only 11 molars (6 RM–GIC and 5 amalgam) after the 2–year period. Based on this study, we suggest that complete removal of carious dentine is still the best conservative treatment, irrespective of the restorative material used.

Dyract versus Tytin Class II Restorations in Primary Molars: 36 Months Evaluation

Due to the changed treatment approach of proximal caries and the amalgam controversy, clinicians are in search for new materials. The aim of the present study was to compare amalgam with an adhesive material in deciduous molars in a clinical, split–mouth design study. At baseline 30 polyacid modified composite (Dyract®) and 30 amalgam (Tytin®) restorations were placed in primary molars, of which 24 and 17 could be evaluated after 24 and 36 months, respectively. Modified USPHS criteria were used for clinical evaluation every 6 months. Annual bite–wing radiographs were taken for evaluation of recurrent caries and cervical gap formation. In the present study, for Dyract as well as for Tytin restorations, low rates of recurrent caries were found, while Dyract restorations showed a better marginal adaptation and surface texture compared to Tytin restorations. In the Dyract group more radiolucencies were found at baseline. In both groups no patient complaint or pain was reported related to the radiolucencies. After 3 years the colour of Dyract was not comparable to the original. For Dyract no excessive wear was noticed compared to enamel. During the study one Dyract (recurrent caries: 18 months) and two Tytin (pulpal aetiology: 6 months, recurrent caries: 36 months) restorations had to be replaced. Even though the restorations were placed in caries risk children, at the 36 months’ evaluation of this clinical study, the results indicate that Dyract can be an alternative for Tytin in the primary dentition.

The Effect of Glass-Ionomer Cement on Carious Dentine: An in vivo Study

The effect of a glass-ionomer cement sealant on carious dentine was investigated clinically and bacteriologically. The study group consisted of 24 molar teeth, with small clinical visible occlusal dentine lesions, in 13 children (aged 7-18 years). Twenty of these molars were filled and sealed with a glass-ionomer cement (Fuji Ionomer Type III) and 4 with a resin sealant (Delton). From each molar, two dentine samples were collected aseptically with a time interval of 7 months. The first sample was taken after opening the lesion just beneath the dentino-enamel junction before application of the filling material (sample A), and the second beneath the removed filling material (sample B) 7 months later. Before collecting sample B the sealant was clinically evaluated and impressions were prepared in order to (re)evaluate the sealants later by scanning electron microscopy (SEM). After taking the second sample, the remaining fissures were opened to a standard depth, the caries which was still present was removed, and a composite resin restoration was applied. In all teeth, more glass-ionomer cement material was found by SEM compared to the clinical evaluation. In both the glass-ionomer- and the resin sealant-treated group, the median value of the total number of microorganisms (CFU) on blood agar was 100 times smaller in the B sample. Microorganisms were found in 90% of the B samples in the group treated with glass-ionomer cement; hard dentine was also found in 45% of the B samples from this group.(ABSTRACT TRUNCATED AT 250 WORDS)

The Effect of Fluoridation on the Occurrence of Hidden Caries in Clinically Sound Occlusal Surfaces

It has been suggested that the diagnosis of occlusal dentine carious lesions has become more difficult due to the influence of fluoride on the character of pit and fissure surfaces. The issue pertains to the occurrence of hidden caries exemplified by occlusal surfaces judged as clinically sound but showing a radiolucency on the bite-wing radiograph. The aim of this study was to investigate the influence of water fluoridation on the occurrence of hidden caries in clinically sound occlusal surfaces in young people. The data of 515 persons (15 years of age) collected in 1968/1969 as part of the Dutch longitudinal epidemiological Tiel/Culemborg study were used. The participants in Tiel (F) were exposed to artificially fluoridated drinking water (F-concentration 1.1 ppm F) from birth until the end of the data collection. The participants in Culemborg (NF) were not exposed to extra fluoride (F-concentration 0.1 ppm F). In 1994 the status of occlusal surfaces of the first and second molars, as read from bite-wings made in 1968/1969, were judged by 2 investigators. (Cohens Kappa intra- and inter-examiner agreement 0.90, 0.83 and 0.85, respectively). The original clinical data of 270 inhabitants of Tiel (F) and 245 of Culemborg (NF) were compared with the radiographic judgements. The children examined in Tiel (F) had a mean of 2.54 clinically sound occlusal surfaces in first and second molars (including surfaces with an enamel demineralization only) of which bite-wing radiographs detected 0.43 surfaces (16.9%) with a radiolucency into dentine. In Culemborg (NF) the children had a mean 0.65 clinically sound judged surfaces of which 0.16 (24.6%) showed a radiolucency on the bite-wing films. The results of the investigation show a proportional reduction of surfaces with hidden caries among clinically sound surfaces in the fluoridated area compared to the control.

In vivo cariostatic effect of resin modified glass ionomer cement and amalgam on dentine

Fluoride-releasing materials have been reported to be bactericidal in vitro. This may be of benefit to modern dentistry, which is directed to the preservation of tooth tissue during restorative treatment. Little is known about in vivo effects. The aim is to investigate the influence of a resin-modified glass ionomer cement (RM-GIC) on carious dentine that remains under restorations, compared to amalgam. Using a split month design, 40 molar pairs in 40 patients (mean age 14.9 years) were selected, based on clinically and radiographically diagnosed occlusal dentine caries. Under aseptic conditions, the enamel was removed and the carious dentine was sampled just beneath the dentino-enamel junction using a round bur. Without further removal of carious dentine, the molars of a pair were alternately restored with RM-GIC or amalgam. The colour and the consistency of the carious dentine were assessed. The samples were processed for microbiological determination of total viable counts (TVC), mutans streptococci (MS), and lactobacilli (LB). After 6 months the molars were reopened, similarly sampled and evaluated, and then permanently restored after complete caries removal. For both materials a substantial decrease in the numbers of TVC, MS and LB was found after the 6-month period. Also a positive effect was observed on the colour and the consistency of the remaining carious dentine, which was comparable for the two materials. RM-GIC showed a significantly larger decrease in counts of MS and LB than amalgam, but not for TVC. Since in only few cavities the number of bacteria decreased under the level of detection, it is still considered essential to remove all carious dentine during restorative treatment.

Effects of Dental Treatment and Single Application of a 40% Chlorhexidine Varnish on Mutans Streptococci in Young Children under Intravenous Anaesthesia

Clinical studies suggest that application of a highly concentrated chlorhexidine varnish results in a decrease in the number of mutans streptococci and thereby a decrease in the caries risks. The aim of this study was to determine the effect of dental treatment on the levels of mutans streptococci (MS) and lactobacilli (LB) and the additional effect of a single application of 40% chlorhexidine varnish (EC40) on the level of MS. Twenty–three children under the age of 5 years scheduled for full dental treatment were selected. Of these 23 children (mean dmf–s 27.1, SD 19.3), 11 children had nursing bottle caries. The mean sugar exposure was 6.4. Subjects were randomly distributed into two groups of approximately equal size. One group received an EC40 application after dental treatment, while the other group received only full dental treatment, both with intravenous anaesthesia with propofol as a single drug. An unstimulated saliva sample and a plaque sample were taken prior to dental treatment. The saliva and plaque sampling of the subjects was repeated after 6 weeks. MS and LB were isolated and counted. The number of children harbouring more than 106 MS in a pooled plaque sample decreased significantly from 8 to 2 children 6 weeks after dental treatment. No additional effect of EC40 was found. The number of salivary MS did not change significantly between the groups or before and after treatment. The figures for LB remained at a high level of more than 104/ml saliva before (21 children) and 6 weeks after treatment (17 children). The results of this study indicate that dental treatment results in a significant suppression of plaque MS, while a single application of EC40 showed no significant additional suppression after 6 weeks.

A comparison of the microbial flora in carious dentine of clinically detectable and undetectable occlusal lesions.

It is not known whether the aetiology of occlusal hidden caries lesions (HCL) is identical to that of small visible lesions (SVL). Previous studies of the microflora of HCL suggest that relatively few species can be isolated. The aim of the present study was to compare the bacterial composition of dentine from 10 HCL and 17 SVL in a population of children aged 8-18 years. The following bacteria were identified: Actinomyces spp., mutans streptococci, Streptococcus sanguis, Streptococcus oralis, Streptococcus gordonii. Streptococcus mitis, and Lactobacillus spp. Streptococcus mutans was found more often in the HCL group (p = 0.03), while Streptococcus sobrinus was found more often in the SVL group (p = 0.05). However, proportions of both species were lower in the SVL group as compared with the HCL group (S. mutans p = 0.07; S. sobrinus p = 0.03). Lactobacilli and Actinomyces spp. were found at similar levels in both groups. A more diverse range of streptococcal species and Veillonella was found in the SVL group (p = 0.001). These results show a less complex microflora in HCL as compared with SVL, indicating that the aetiology of hidden caries might be different from that of open caries.