Remineralisation capability of silver diamine fluoride in artificial enamel lesions on smooth surfaces using quantitative light-induced fluorescence measurements in-vitro

Enamel demineralisation can develop on smooth surfaces as an undesirable side effect during orthodontic treatment with fixed appliances. This study aimed to evaluate the ability of 38% silver diamine fluoride in remineralisation (as estimated by fluorescence gain) of artificial initial lesions in smooth surfaces of human enamel. The smooth surfaces of 50 human tooth samples were artificially demineralised and 45 samples were allocated randomly into three groups receiving a single treatment with a varnish: group I: Riva Star (silver diamine fluoride, SDF), group II: Bifluorid 12 (NaF, CaF₂), and group III: Cervitec F (CHX, CPC, NH₄F). Five samples were assigned as a negative control group without treatment. All samples were exposed to pH-cycling for 28 days. Fluorescence behavior was measured using Quantitative light-induced fluorescence before and after demineralisation and up to four weeks on a weekly basis. Analysis of variance (ANOVA) with Tukey–Kramer post-hoc tests and repeated measures ANOVA were used for statistical evaluation (α = 0.05). After demineralisation, all samples showed mean ΔF of − 16.22% ± 4.35, without significance differences between the fluorescence behaviour of the samples (p = 0.251). After 28 days group comparison showed a statistically significant difference (p = 0.034) for ΔF values: the lowest fluorescence values were found in group I (SDF, mean ΔF − 16.47 ± 6.08) with a significant difference compared to group III (Cervitec F, mean ΔF − 11.71 ± 4.83). In group II (Bifluorid 12) mean ΔF value was − 15.55 ± 2.15) without statistically significant differences to groups I and III. The fluorescence behaviour of SDF varnish on smooth surfaces with artificial initial enamel lesions was significantly lower compared to Cervitec F varnish after short time use.

Associations between obesity, dental caries, erosive tooth wear and periodontal disease in adolescents: a case-control study

PURPOSE

To compare oral health [dental caries, periodontal status, and erosive tooth wear (ETW)], diet and oral hygiene habits between obese and normal weight adolescents, and to explore possible risk associations.

METHODS

In this case-control study, a convenience sample of 71 obese adolescents (age range 11-18) from a rehabilitation centre, and 54 age-sex-matched normal weight adolescents were selected for this study. Groups were defined using the Body Mass Index and growth curves for Flemish adolescents. Oral health was measured using DMFT, gingival, plaque and BEWE index. A validated questionnaire was utilized to assess diet and oral hygiene habits. Mann-Whitney U test was used to compare oral health between groups. Multivariate Firth's logistic regression analysis, conditional regression analysis and classification trees were used to detect associations between oral health and potential risk factors.

RESULTS

Prevalence of ETW did not differ significantly between groups, although obese adolescents presented a significantly higher caries experience, gingivitis, presence of plaque and periodontal problems, compared to normal weight adolescents. After adjusting for age and sex, obesity was associated only with the presence of dental plaque (p ≤ 0.001). Obese participants reported a significantly higher intake of sugar-rich and caloric food items than normal weight group. The consumption of acidic drinks, however, was similar.

CONCLUSION

Obese adolescents presented significantly higher caries experience, gingivitis and plaque, although after adjusting, obesity became significantly associated only with the presence of dental plaque.

Child behaviour during dental care under nitrous oxide sedation: a cohort study using two different gas distribution systems

Purpose

Conscious sedation by inhalation of a mixture of nitrous oxide and oxygen (CS) is a technique used in dental care for anxious, handicapped or uncooperative patients. The very special objective of this cohort study is to compare the behaviour of young patients during dental care under CS in two hospitals using different gas distribution systems.

Methods

Young patients were divided into four categories: young child (YC), phobic anxiety (PA), mental disorder (MD), occasional indication (OI). Differences in behaviour scale at various time points according to the sedation system used were established and compared using Mann–Whitney tests.

Results

This study showed that there is no difference in behaviour during dental care in YC after sedation. In PA, a significant difference in behaviour is only observed during local anaesthesia (p = 0.024).

Conclusion

No significant differences detected in children’s behaviour under conscious sedation using different gas administration systems. The delicate stage of local anaesthesia in PA patients can be facilitated with repeated sessions of dental care under conscious sedation.

Electronic supplementary material

The online version of this article (10.1007/s40368-020-00569-z) contains supplementary material, which is available to authorised users.

Social gradient in caries experience of Belgian adults 2010

OBJECTIVE

This study aims to explore the caries experience of the Belgian population in relation to social indicators.

BASIC RESEARCH DESIGN

Data collection (2009-2010) consisted of an oral health questionnaire and examination during a home visit.

PARTICIPANTS

Representative sample of the Belgian population (⟩5 years old). Only the economically active population was included for final analyses.

MAIN OUTCOME MEASURES

ANOVA and multivariable regression analyses were used to reveal associations between social indicators, oral hygiene, untreated decay, DMFT and edentulousness.

RESULTS

2742 participants completed the questionnaire, of whom 2563 were examined clinically. Most (53%) were female and mean age was 43.3 years (95% CI= 41.2-45.4). In the total population, 11.1 % were caries-free (DMFT = 0) and mean DMFT was 10.8 (95% CI = 10.0-11.5). In the analysed subsample, higher educated participants had lower DMFT scores than those with low or no educational qualifications (p = 0.003). Employment status was associated with the presence of untreated tooth decay, especially in the youngest age group (p = 0.015), and with edentulousness (p = 0.02), with a higher risk among unemployed women of being completely edentulous (OR = 5.32; 95% CI = 1.75-16.12). Untreated tooth decay was related to frequency of tooth brushing and plaque index (p ⟨ 0.002 and ⟨ 0.001 respectively).

CONCLUSIONS

Caries experience in Belgium, expressed as mean DMFT and proportion of untreated tooth decay, is more associated with level of education and employment status than with family income, which is still the main criterion for larger government allowances for healthcare in Belgium.

Comparison of micro-CT imaging and histology for approximal caries detection

Histological sectioning is a generally accepted in vitro validation method for caries detection techniques. However, it requires cumbersome sample preparation and induces irreversible sample destruction. Micro-Computer Tomography (micro-CT) allows non-destructive imaging of tooth structure. The aim of this study was to compare the performance of histological sectioning and micro-CT imaging in detecting approximal carious lesions. Unlike previous studies, evaluation is objectified by comparing visual appearance of exactly corresponding anatomical regions. Sixty extracted human teeth were scanned with a desktop micro CT system. Axial histological slices were prepared and photographed. Sample preparation, combined with dedicated image processing, ensured selection of identical anatomical regions on radiographic and histological images. Evaluation of the presence and extent of carious lesions was performed by four dentists using custom-designed software. Each section was scored independently (histo or micro CT). Scores of approximal surfaces were retained for further analysis. Spearman’s correlation coefficients (0.738 to 0.829, p < 0.0001) showed a good agreement between signs of carious lesions in the identical region obtained with both methods. Bland-Altman plots showed that 90.76% of the data points were within the limits of agreement. Micro-CT imaging was shown to provide an interesting alternative to histological sectioning as detection method for carious lesions.

Comparison of occlusal caries detection using the ICDAS criteria on extracted teeth or their photographs

BACKGROUND

Using photographs of occlusal surfaces instead of extracted teeth for the detection of caries can be useful in multicenter studies or education. Using a panel of observers, ICDAS scores on teeth or photographs were evaluated against the histological gold standard. The hypothesis was that both outcomes were equivalent.

METHODS

Four examiners with different experience in ICDAS scored photographs of occlusal surfaces of 100 extracted teeth on a monitor using ICDAS criteria. Two of the examiners had previously scored extracted teeth prior to photography. Digital images of histological sections of the teeth were observed by all examiners and consensus scores were given for each investigation site (gold standard). Kappa statistics and Spearman correlation coefficients as well as repeated measure ANOVA were performed. ROC curves were constructed for each examiner and the areas under the ROC-curves (AUC) of both scoring techniques (extracted teeth, digital images) were compared (α = 0.05).

RESULTS

Intra- and inter-rater kappa for ICDAS on teeth were 0.81-0.94 and on photographs 0.54-0.88, respectively. Correlation with histology was 0.58- 0.61 for the teeth and 0.50-0.62 for the photographs. AUC of ICDAS scores of extracted teeth (mean 0.89) were slightly higher than those for photographs (mean 0.84). However, both AUC values were not statistically significant (p = 0.38).

CONCLUSION

Using photographs to assess occlusal surfaces with the ICDAS criteria was not statistically different from scoring the extracted teeth.

Validation of the Oral Survey-B System for Electronic Data Capture in National Oral Health Surveys

The aims of the present study were to incorporate and to validate the electronic capture of participant-related outcomes into the Oral Survey-B System, which was originally developed for the electronic capture of clinical data. The validation process compared the performances of electronic and handwritten data captures. The hypothesis of noninferiority would be established if participants performed electronic data capture of the questionnaire survey with an effectiveness of at least 95% of that of handwritten data capture. In this multicenter, randomized, one-period crossover study design, participants (n = 261) were allocated to start with either electronic or handwritten data capture. The incorporation of the electronic self-completed questionnaire into the Oral Survey-B System was successful. The validation of the electronic questionnaire was performed by participants aged from 18 to 75 years. The interrater reliability of participants performing electronic and handwritten data capture of nonclinical assessments per questionnaire and per entry showed a kappa value of 0.72 (95% CI: 0.53-0.94). The noninferiority of electronic data capture in relation to that of the handwritten data capture and transfer was shown (p < 0.0001; 95% CI: 1.47-2.99). In conclusion, the electronic capture of participant-related outcomes with the Oral Survey-B System, originally designed for capture of clinical data, was validated. The electronic data capture was accurate and limited the number of errors. The participants were able to perform electronic data capture effectively, supporting its implementation in further National Oral Health Surveys. With the consideration of participant preference and time savings, this could lead to the implementation of electronic data capture worldwide in National Oral Health Surveys.

Longevity of posterior composite restorations: a systematic review and meta-analysis

The aim of this meta-analysis, based on individual participant data from several studies, was to investigate the influence of patient-, materials-, and tooth-related variables on the survival of posterior resin composite restorations. Following Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines, we conducted a search resulting in 12 longitudinal studies of direct posterior resin composite restorations with at least 5 years' follow-up. Original datasets were still available, including placement/failure/censoring of restorations, restored surfaces, materials used, reasons for clinical failure, and caries-risk status. A database including all restorations was constructed, and a multivariate Cox regression method was used to analyze variables of interest [patient (age; gender; caries-risk status), jaw (upper; lower), number of restored surfaces, resin composite and adhesive materials, and use of glass-ionomer cement as base/liner (present or absent)]. The hazard ratios with respective 95% confidence intervals were determined, and annual failure rates were calculated for subgroups. Of all restorations, 2,816 (2,585 Class II and 231 Class I) were included in the analysis, of which 569 failed during the observation period. Main reasons for failure were caries and fracture. The regression analyses showed a significantly higher risk of failure for restorations in high-caries-risk individuals and those with a higher number of restored surfaces.

Decision-making and preventive non-surgical therapy in the context of a European Core Curriculum in Cariology

This paper is part of a series of papers towards a European Core Curriculum in Cariology for undergraduate dental students. The European Core Curriculum in Cariology is the outcome of a joint workshop of the European Organisation for Caries Research (ORCA) together with the Association for Dental Education in Europe (ADEE), which was held in Berlin from 27 to 30 June 2010. The present paper covers decision-making and non-surgical treatment. In particular, it will provide some background information on this part of the European core curriculum. The dentist, on graduation, must be competent at applying the principles of prevention of dental hard tissue disease processes (primary prevention) and progression when it has manifested itself (secondary prevention). The competences should apply in differing ways to patients of all ages. Goals of prevention should be clearly defined in order for outcomes to be evaluated, and a dentist should be competent at determining these outcomes. Although this concept is recognised by many academics and experts, clinical teaching, practice and health insurance coverage frequently emphasise surgical treatment. There are many reasons and obstacles that might account for this, and this paper suggests some reasons why this might be and makes suggestions for how these can be addressed in the future. One factor that is essential in the provision of a preventive, non-surgical approach is that of communication with the patient. However, this unfortunately takes less space in the dental curricula compared with technical skills aimed at restorative procedures; this weighting needs to be more equally balanced.

Comparison of salivary fluoride concentrations after administration of a bioadhesive slow-release tablet and a conventional fluoride tablet

The in-vitro and in-vivo fluoride release of bioadhesive, slow-release tablets prepared from a mixture of polyethylene glycol polymers, containing 0·1 mg of fluoride as NaF was studied, and their ability to sustain fluoride levels in saliva were compared with conventional fluoride tablets with the same fluoride content. In-vitro release experiments showed that the bioadhesive tablets needed 8 h to release all their fluoride compared with &lt; 1 h for the conventional fluoride tablets. In-vivo, the bioadhesive tablets had a retention period of 6 h and could sustain a salivary fluoride level of more than 10 μm above the baseline for 7 h. The conventional fluoride tablets achieved a peak concentration of 0·5 Mm directly after dissolution in the mouth, but the fluoride level could not be sustained for longer than 1 h. A good agreement was found between the in-vitro swelling behaviour of the bioadhesive tablets and their in-vitro and in-vivo release characteristics and their in-vivo retention time.

Novel information theory based method for superimposition of lateral head radiographs and cone beam computed tomography images

OBJECTIVES

The aim was to introduce a novel alignment criterion, focus mutual information (FMI), for the superimposition of lateral cephalometric radiographs and three dimensional (3D) cone beam computed images as well as the assessment of the alignment characteristics of the new method and comparison of the novel methodology with the region of interest (ROI) approach.

METHODS

Implementation of a FMI criterion-based methodology that only requires the approximate indication of stable structures in one single image. The robustness of the method was first addressed in a phantom experiment comparing the new technique with a ROI approach. Two consecutive cephalometric radiographs were then obtained, one before and one after functional twin block application. These images were then superimposed using alignment by FMI where the following were focused on, in several ways: (1) cranial base and acoustic meatus, (2) palatal plane and (3) mandibular symphysis. The superimposed images were subtracted and coloured. The applicability to cone beam CT (CBCT) is illustrated by the alignment of CBCT images acquired before and after craniofacial surgery.

RESULTS

The phantom experiment clearly shows superior alignment when compared to the ROI approach (Wilcoxon n = 17, Z = -3.290, and P = 0.001), and robustness with respect to the choice of parameters (one-sample t-test n = 50, t = -12.355, and P = 0.000). The treatment effects are revealed clearly in the subtraction image of well-aligned cephalometric radiographs. The colouring scheme of the subtraction image emphasises the areas of change and visualizes the remodelling of the soft tissue.

CONCLUSIONS

FMI allows for cephalometry without tracing, it avoids the error inherent to the use of landmarks and the interaction of the practitioner is kept to a minimum. The robustness to focal distribution variations limits the influence of possible examiner inaccuracy.

Approximal Caries Diagnosis after Data Import from Different Digital Radiography Systems: Interobserver Agreement and Comparison to Histological Hard-Tissue Sections

<i>Aims:</i> To evaluate the agreement of approximal caries diagnosis obtained with different types of digital radiography systems after image import into a reference system. <i>Methods:</i> Digital radiographs were taken from 30 extracted human premolars with 60 diagnostic surfaces using a reference and two test systems from which images were imported as TIFF files. Four observers evaluated the radiographs using the reference software. Teeth were sectioned for histology. Agreement between histology and each technique was calculated using receiver operating characteristic (ROC) statistics. <i>Results:</i> The areas under the ROC curves were not significantly different between reference and test systems. <i>Conclusions:</i> Importing files from different programs did not affect diagnostic accuracy.

A prospective randomised clinical trial of one bis-GMA-based and two ormocer-based composite restorative systems in class II cavities: Three-year results

OBJECTIVES

Ormocer composites, consisting of a silicon-based polymer, have been developed recently as a tooth-coloured restorative material. The purpose of this prospective randomised clinical trial was to evaluate the performance of two small-particle hybrid ormocer-based restorative systems (AD, Admira/Admira Bond, VOCO; DE, Definite/Etch & Prime 3.0, Dentsply) and one small-particle hybrid bis-GMA-based composite restorative system (TC, Tetric-Ceram/Syntac, Ivoclar-Vivadent) in occlusal stress-bearing restorations.

METHODS

One hundred and twenty-eight occlusal-proximal restorations (44 AD, 43 DE and 41 TC) were placed according to the manufacturer's instructions in thirty-two adult patients. Their clinical performance was scored according to the USPHS criteria and evaluation of bite-wing radiographs.

RESULTS

After 3 years, four AD, five DE and four TC restorations had failed due to fracture or marginal gap formation. Surface roughness improved significantly when compared to the baseline in AD and TC (Friedman test, p<0.05) during the first year but returned to baseline values after 3 years. DE had a significant tendency towards discolouration (p<0.05). Bite-wing radiographs showed two AD and one TC restorations with internal porosities. ANOVA showed that larger restorations (> or = 3 surfaces) showed significantly more degradation than smaller ones.

CONCLUSIONS

In a group of class II restorations, there was no significant difference in failures after 3 years between ormocer-based and bis-GMA-based restorative systems.

[Inter-university cooperation in Flanders--an academic point of view on peer review]

Peer review as a possibility for discussion among practising dentists was introduced in Belgium in 1998 in the framework of a quality ensuring program. The 'Interuniversitary Cooperation', an initiative of Flemish universities active in teaching, research and patient treatment in dentistry has been involved in this program since its beginning to set up a dialogue between academia and dental practitioners and to gather information on scientific and educational matters. In this article the principles and organisation are described and thought is given to the attitude of the participants and future possibilities.

Prevalence and Determinants of Enamel Fluorosis in Flemish Schoolchildren

As part of an epidemiological study on the oral health of Flemish schoolchildren, fluoride use was studied together with risk factors (medical history, tap water fluoride concentration, use of fluoride supplements, toothpaste and brushing habits). Fluorosis was scored according to the Thylstrup-Fejerskov index (TFI) in children aged 11 years (4,128 children examined). Explanatory variables were recorded yearly, starting at the age of 7. Earliest toothpaste use was reported at the age of 1. By age 7, 99.7% of the children reported the use of toothpaste (90% fluoride-containing), but only 13.9% reported using a pea-sized amount. At age 7, 66% of the children had received systemic fluoride supplements during at least part of their childhood. At 11 years, 92% of the children used a fluoride-containing toothpaste and 6% still received systemic fluoride supplements. Fluorosis was present in about 10% of all the children examined, mainly TFI score 1 (7.3% in upper central incisors). Logistic regression established tooth brushing frequency and fluoride supplement use, in addition to tap water fluoride concentrations above 0.7 mg/l, as significant risk factors when the presence of fluorosis on at least one tooth was used as outcome variable. Children having fluorosis had a lower risk of caries, both in the primary (median dmft 1, range 0-10 vs. 2, range 0-12) and permanent dentition (median DMFT 0, range 0-5 vs. 0, range 0-11).

In vitro evaluation of the marginal seal of four restoration materials on deciduous molars

The aim of this study was to compare the marginal microleakage of Fuji II LC (A), composite resin Z250 (B), Fuji IX GP (C), and Dyract AP (F) in class V cavities and at the Fuji II LC/Z250 (D) and Fuji IX GP/composite resin Z250 (E) interfaces of an open sandwich technique on deciduous teeth. After thermocycling the mean marginal dye penetration at the enamel junction was 21.6 microns +/- 14.2 for group A; 83.6 microns +/- 32.3 for group B; 7.5 microns +/- 7.5 for group C; 38.7 microns +/- 27.5 for group D, and 0 micron for groups E and F. Mean dye penetration at the cementum junction was 37.1 +/- 20.2 (A); 123 +/- 42.1 (B); 28.7 +/- 17.1 (C); 0 (D); 14.4 +/- 14.4 (E); and 0 (F) microns. No leakage was seen at the junction between Fuji II LC and Z250 (0 micron), whereas a mean leakage of 184 microns between Fuji IX and Z250 was measured. In enamel the best seal was obtained with Dyract AP, but with differences at the limit of significance (P = 0.07). Sealing was significantly worse with Z250 (p = 0.03 versus Fuji II LC; p = 0.006 versus Fuji IX GP; and p = 0.003 versus Dyract AP). In cementum, the comparison between the grouped data Z250-Fuji II LC versus Fuji IX GP-Dyract AP was highly significant (p < 0.001), while there was no detectable difference between Z250 and Fuji II LC.

A survey of endodontic practice amongst Flemish dentists

AIM

The purpose of this study was to gather information on routine endodontic treatment performed by Flemish (Dutch-speaking Belgian) dentists.

METHODOLOGY

A postal questionnaire was sent to all the 4545 Dutch-speaking dentists registered in Belgium. The questionnaire was made up of 38 questions with multiple-choice answers. Results from 32 questions are presented, covering subjects, such as demographic and professional activity, root-canal preparation and instrumentation, emergency procedures and postoperative complications, choice of irrigants and disinfectants, and choice of obturation techniques.

RESULTS

A total of 1143 questionnaires (25.1%) were returned. Approximately 94% of the respondents were general practitioners. The results indicate that there are discrepancies between daily practice and academic teaching, especially regarding the use of rubber dam (only 3.4% report using it as a standard procedure) and the detection and preparation of a second mesiobuccal canal in maxillary first molars (70% never or seldom). Most GDPs reported that they completed treatment in two visits. The majority of practitioners used manual instruments manipulated with a filing technique; 38.9% of the respondents prepared root canals 1 mm short of the radiographic apex. The most popular emergency procedure for acute pain was pulpectomy (40.2%); 48% performed pulpectomy, prescribed analgesics and antibiotics for acute apical periodontitis. Approximately 35% reported complications after cases with chronic apical periodontitis were treated. The first-choice root-canal irrigant was sodium hypochlorite and approximately 65% used intracanal medication. The most popular obturation technique was cold lateral condensation (60%) with 29% using AH26 as a sealer. A high proportion of GDPs (80%) performed re-treatments.

CONCLUSIONS

The results of this study confirm that many Flemish general practitioners are not following quality guidelines for endodontic treatment.

[Fluorosis: diagnosis, risk assessment and epidemiology]

Fluorosis is the most widespread side-effect of fluoride use and appears as discrete white spots on the enamel up to severe enamel dysplasia. There are different techniques for scoring fluorosis in epidemiological surveys. In the literature there is no uniform way of selection of teeth and data processing. Fluorosis risk is determined by environmental factors such as water and food fluoride content as well as individual factors such as use (or misuse) of fluoride supplements and fluoridated oral hygiene products. In a group of Flemish schoolchildren, fluorosis prevalence is low and mainly related to use of fluoride supplements and toothpaste in childhood.

Microhardness changes in surface enamel after application of bioadhesive fluoride tablets in situ

The effect of fluoride released by bioadhesive tablets was evaluated in an in situ model in human volunteers. Eight volunteers carried four to six polished human enamel samples in a lower lingual device for a period of 5 days without fluoride supplements (control) and 5 days using one bioadhesive tablet (0.5 mg F) per day, placed in the lower buccal sulcus. Changes in mineral content were measured in terms of surface microhardness indentation length (load 0.98 N, Knoop diamond indenter). Some enamel samples were analyzed for their fluoride content by means of a surface etch biopsy. The indentation length increased significantly in both experiments, but demineralization was less pronounced with fluoride (indentation length increased from 44 +/- 7 to 48 +/- 13 microns) than in the control (44 +/- 7 to 58 +/- 13 microns). The fluoride concentration and the amount of calcium in the acid etch biopsy specimens of the enamel samples did not differ significantly between the two groups. Bioadhesive, fluoride-releasing tablets have therefore demonstrated the potential to reduce demineralization by elevating salivary and plaque fluoride concentration for a period of several hours. This self-administered device can be a supplementary means for prevention of caries.

[What fluoride compound has the greatest effect in the fight against dental caries?]

There is a wide range of fluoride compounds that can be used in the prevention of caries. Mineral salts, monofluorophosphate or amino fluoride are most currently used and their efficacy is supported by scientific evidence. Next to the prevention of mineral dissolution, some fluoride compounds have more pronounced antimicrobial properties. Clinically, all fluoride compounds are equivalent if they are presented in a compatible formulation.

Distribution of fluoride in the oral cavity after application of a bioadhesive fluoride-releasing tablet

Bioadhesive fluoride tablets are fluoride-releasing devices that can be applied to the oral mucosa by the patient and release fluoride for several hours. From earlier research, it is known that a single fluoride source in the mouth can lead to an uneven distribution of fluoride in the oral cavity. In this study, fluoride concentrations were determined at different sites of the oral cavities of 13 healthy human volunteers after the application of a bioadhesive fluoride tablet containing 0.5 mg fluoride. The sites were: (1) labial surfaces of the upper central incisors, (2) lingual surfaces of the lower central incisors, (3) labial surface of the first upper left molar, and (4) labial surface of the lower right first molar. The tablet was fixed either centrally on the palate or in the lower labial sulcus in two consecutive experiments. Saliva was sampled with polyethylene sponges 5, 10, 20, 30, 60, 120, 180, and 240 minutes after tablet insertion. Fluoride was determined electrochemically. It could be shown that the area under the curve (AUC) values were significantly (p < 0.05) higher after tablet insertion in the lower labial sulcus at sampling site 1, a trend (p = 0.06) could be calculated for sampling sites 2 and 3, and no difference was found at sampling site 4. Fluoride could be detected in concentrations above 0.01 mmol.L-1 at all sampling sites after tablet insertion in the lower labial sulcus. This location seems to be a more appropriate tablet location than the palate.

Penetration of etching agents and its influence on sealer penetration into fissures in vitro

OBJECTIVES

This study was designed to assess: 1) the ability of several commercially available and laboratory-made acid etchants to penetrate occlusal fissures when used for pit and fissure sealing, and 2) the influence of adding a surfactant to the etchant on penetration of the sealer. Viscosity, surface tension and contact angle to enamel of the etchants were determined for each treatment, and these properties were related to the etchant's ability to penetrate fissures.

METHODS

Penetration was assessed in an acrylic fissure model having a deep-narrow fissure using a microscope and a chronometer. Penetration depth was expressed as percentage of total fissure depth and was measured in intervals up to 90 s. Commercially available etching agents with different viscosities and two solutions of phosphoric acid (37%), one with and one without a surfactant, were tested. The etch pattern obtained on the fissure wall enamel of extracted teeth with some of these products was evaluated using scanning electron microscopy. Eventually, the penetration depths of a composite sealer in fissures treated with a conventional etchant were compared to those after application of a surfactant-containing etchant on sections of extracted teeth.

RESULTS

None of the commercially available etchants studied were able to penetrate farther than 17% of the total fissure depth in the fissure model. The surfactant-containing etchant showed complete penetration within about 1 min and had a significantly lower surface tension and contact angle than the other products tested. Only the surfactant-containing etchant could produce a retentive pattern on the entire wall enamel of the fissure with the exception of locations blocked by debris and plaque. Fissures treated with this product prior to sealing showed a significantly deeper penetration of the sealer in deep-marrow fissures.

SIGNIFICANCE

Surfactant-containing etchants with a low viscosity can penetrate completely into fissures and can produce an increased retentive and wettable surface which significantly increased sealant penetration into deep fissures.

[The use of fluoride from the viewpoint of toxicology and ecology]

Although the effectiveness of fluoride against dental caries seems to be established, criticism about its safety has never ceased. Its dual role as a (potentially beneficial) drug as well as a (potentially malignant) environmental pollutant have contributed to this controversy. Although Belgium does not allow the fluoridation of drinking water, many sources of air and water contamination exist due to industrial activities. The role of the dentist is to know about these regional fluoride sources when prescribing fluoride for caries control in order to obtain an optimal effect together with maximum safety.

Development and testing of bioadhesive, fluoride-containing slow-release tablets for oral use

The bioadhesive characteristics of tablets for oral use made from modified starch, polyacrylic acid (PAA), polyethylene glycol (PEG) and sodium carboxymethylcellulose (CMC) were investigated. Adhesion force and energy were determined in-vitro and maximal adhesion time was evaluated in-vivo in human subjects. In-vitro, PAA showed the best bioadhesive properties, followed by modified maize starch and PEG with a mol. wt of 300,000-400,000 daltons. The presence of 0.1 mg of fluoride as NaF did not lead to significant differences in adhesion force and energy for the same formulation. The in-vivo bioadhesion was not strongly correlated to the in-vitro data. PAA, despite its excellent adhesion, proved to be irritating to the mucosa. PEG with a mol, wt of 200,000 daltons was subject to erosion. CMC showed good bioadhesive properties but the mechanical strength of the tablets was low. Modified maize starch tablets containing 5% (w/w) PAA and PEG with a mol. wt of 300,000 daltons proved to be the most suitable formulations for a fluoride-slow-release tablet with bioadhesive properties. In-vitro, the tablets released all of the fluoride within the 8 h period, with a high initial release. The release rate was related to the water absorption rate of the tablets. The PAA-containing formulations and the CMC formulations had the fastest release. In-vivo, fluoride levels with a minimum of 150 and a maximum of 1000 micrograms mL-1 were maintained for 8 h in the oral cavity. These fluoride levels were sustained significantly longer than those obtained with the administration of fourfold the amount of fluoride in the form of a fluoride-containing toothpaste. The release characteristics in-vivo exhibited a high variation. The use of bioadhesive polymers in oral pharmacotherapy seems promising.

Study of lead and cadmium content of surface enamel of schoolchildren from an industrial area in Belgium

The amount of lead and cadmium was determined in surface enamel from permanent teeth of schoolchildren by means of an acid etch surface enamel microbiopsy method. Lead and cadmium levels were calculated on the amount of etched enamel. A comparison of the concentrations of these heavy metals was made between children (7 and 11 yr) from a school close to a non-ferrous metal plant and children from the same age group from a school situated nearby the same plant but in a zone polluted to a lesser degree. The lead concentrations in enamel biopsies from the first group were significantly higher than those from the second group. Cadmium shows the same trend but on a much lower level. A significant correlation between lead and cadmium was also found in both groups.

In vivo use of a dual acid etch biopsy for the evaluation of lead profiles in human surface enamel

Two successive acid etch biopsies were performed on the permanent maxillary right central incisors of two age-groups of children resident in an urban area in Belgium. Lead was determined in the biopsy solutions and the concentrations were related to etch depths which were calculated from the calcium and phosphorus concentrations in the biopsy solutions. The mean lead concentration of the first enamel biopsy layer was five times higher than in the second biopsy layer. A strong relation was observed between the two biopsies. It was shown that calibration of the lead values with respect to etch depths and Ca/P ratios was desirable and that a robust regression analysis approach was needed instead of classic least-squares regression analysis. However, the second biopsy provided more reliable lead estimates. In this study no increase in lead concentration in surface enamel could be demonstrated with age. Therefore, it was concluded that for these children the presence of lead in surface enamel had to be attributed primarily to preeruptive uptake.

[Position of preventive dentistry in Belgium: overview of private and public aspects]

The authors provide a summary of the situation with regard to preventative dental medicine in Belgium, with special emphasis on the health insurance system, the attitude of Belgian dentists to prophylaxis, the status of preventative dentistry at universities, and the estimated requirements with respect to prevention together with some initiatives in this area.

Penetration of fluoride-containing self-gelling liquids into human molar occlusal fissures in vitro

In this in vitro study the ability and speed of self-gelling liquid compositions to penetrate into fissures were evaluated. Two formulations containing either tetraethylsilicate, ammonium fluoride, and sodium lauryl sulfate or tetraethylsilicate, sodium fluoride, and cetylpyridinium chloride at different concentrations were used. It is shown that fissure penetration occurs when a certain minimum content of surface-active agent is present. Fissure penetration is achieved within 3-4 s, according to the fissure morphology.