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Biomedical subjects

C van Loveren

Publications and source records attributed to C van Loveren.

At least 37 records · Page 2Linked to original sources
PubMed1998

Colonization with mutans streptococci and lactobacilli and the caries experience of children after the age of five.

Some authors suggest that there is a "window of infectivity" for mutans streptococci (MS) at an early age, after which colonization is not likely to occur. Moreover, children with low or non-detectable levels of MS at an early age are at lower risk for caries. It was our aim to study caries experience and colonization with MS and lactobacilli in a group of children at 11 years of age who had been documented to have been MS-free until 5 years of age. For this group, the mfs and MFS values at 11 years of age were found to be 1.12+/-2.81 and 0.44+/-0.88, respectively. These values are much lower than those of a control group of 11-year-old children who had always been MS-positive since the age of 2, being 3.10+/-3.43 and 1.20+/-1.91, respectively. Of the 30 children without detectable MS up to the age of 5, 22 had acquired MS at 11 years of age, but their MS counts were significantly lower than those of the control group. No correlation was observed between the levels of MS of the children and the mothers. In children at 11 years of age, no differences were found in the numbers of lactobacilli and sugar intakes per week between the children MS-free and the children MS-colonized at 5 years of age. The present study indicates that the acquisition of MS is still possible after the so-called "window of infectivity" and that a delayed acquisition of MS may reduce the caries experience in the primary and permanent dentition at a later age.

Age Factors↗
PubMed1998

Transmission of mutans streptococci between mothers and children with cleft lip and/or palate.

OBJECTIVE: The aim of this study was to investigate the transmission of Streptococcus mutans between children with cleft lip and/or palate and their mothers. DESIGN: Saliva samples of 21 mother-child pairs were collected and cultured on plates containing a selective growth medium for mutans streptocci. At least five separate colonies of each colony morphotype were isolated. A polymerase chain reaction (PCR) with randomly chosen primers was used to type the isolates. RESULTS: The number of morphotypes and PCR types was significantly lower in the children than in the mothers. Significant correlations were found between the number of morphotypes and PCR types, in the children as well as in the mothers. In only 38% of the mother-child pairs were the same PCR types found in mother and child. CONCLUSIONS: This suggests that S. mutans had been transmitted from mother to child in one-third of the population studied. No correlations were found among the number of colony-forming units, the number of colony-colony-morphotypes, and the number of PCR types of the mothers and transmission. Similar PCR types in mother and child were found significantly more often in children who had more than one PCR type. The results indicate that transmission of S. mutans from mother to child is not frequent in children with oral cleft. This may have consequences for preventive treatment of cleft lip and/or palate children and their mothers.

Chi-Square Distribution↗
PubMed1998

[Dental caries, dental fluorosis and use of fluoride tablets. Results of survey by 8, 14, and 20 year old insurance patients].

OBJECTIVE: To assess the prevalence of fluorosis at the age of 8, 14 and 20 years; to evaluate the prevalence of caries and fluorosis at the age of 8 and 14 years in relation tot the use of fluoride tablets during the first 5 years of age. DESIGN: Retrospective study. SETTING: The investigation was carried out in four cities in the Netherlands. METHODS: Caries and fluorosis data were obtained in 8-, 14- and 20-year-old persons by clinical examination. For 8- and 14-year-olds results were compared with data about the use of fluoride tablets during the first 5 years of life. These data were obtained by questionnaires completed by the parents when the child was 5 years old. RESULTS: Prevalence of fluorosis in permanent teeth of 8-, 14 and 20-year-olds was 16%, 31% and 26% respectively. Univariate analysis revealed a statistically significant relation between the frequency of the use of fluoride tablet and caries prevalence in deciduous and permanent teeth on the age of 8. Prevalence of fluorosis and fluoride tablet use did not show such a relation. These findings were confirmed by logistic regression analysis, using frequency of tooth brushing on the age of 5 as possible confounding factor. CONCLUSION: In this group of children the use of fluoride tablets during the first 5 years of life does not seem to increase the prevalence of fluorosis.

Administration, Oral↗
PubMed1997

Progression of radiopacities and radiolucencies under amalgam restorations on bite-wing radiographs.

Radiolucent and radiopaque areas in the dentine under amalgam fillings represent demineralized tissue. The aim of this study was to investigate whether caries progresses in radiolucent and radiopaque areas under amalgam fillings, by assessing their enlargement longitudinally on bite-wing radiographs. Bite-wings from dentitions of persons aged 17, 20 and 23 years were compared. For a 3-year evaluation, 365 teeth with class I and class II amalgam restorations were available on bite-wings; 16 radiopacities, 46 radiolucencies and 28 combinations could be followed longitudinally. All radiopacities remained the same size, 14 radiolucencies enlarged and 8 combinations enlarged. For a 6-year evaluation, 236 filled teeth were available; 10 radiopacities, 30 radiolucencies and 11 combinations could be compared longitudinally. All radiopacities remained the same size, 12 radiolucencies enlarged and 6 combinations enlarged. Because the radiopaque areas had not enlarged visibly on bite-wing radiographs over 3 or even 6 years, it was concluded that radiopacities may be non-progressing caries. A substantial number of radiolucent areas, with or without concomitant radiopacities, did not enlarge while radiolucent areas are considered as progressing caries.

Adolescent↗
PubMed1997

Validity of radiographs for diagnosis of secondary caries in teeth with class II amalgam restorations in vitro.

In the present in vitro study, the validity was determined of bite-wing radiographs for the diagnosis of secondary caries in approximal parts of teeth with class II amalgam restorations in vitro. The study was performed on 47 molars and 49 premolars providing 68 and 69 filled approximal surfaces, respectively. The teeth were radiographed in a buccolingual direction to obtain images comparable to bite-wings. Radiolucencies and radio-opacities were scored as caries. Subsequently the teeth were sectioned (700 microns) in transverse or sagittal direction and then the sections were radiographed. Validation was performed against these radiographs of sections, on which also radiolucencies and radio-opacities were scored. Statistical analysis of the results revealed significant differences between the validity parameters for molars and premolars, being for sensitivity 73 and 80%, respectively, for specificity 90 and 95%, for positive predictive value 95 and 92%, and for negative predictive value 58 and 86%. For molars, the results did not differ significantly from the results of our previous study on caries diagnosis in teeth with occlusal fillings. The present experiment showed that bite-wing radiographs are useful for the diagnosis of secondary caries under approximal parts of class II amalgam restorations, just as for secondary caries diagnosis adjacent to class I restorations.

Bicuspid↗
PubMed1997

[Caries treatment strategy. 'Tip the balance'--drilling or not drilling].

Traditionally caries treatment strategy has been based on the detection of caries lesions, and directed to a restorative procedure whereby the detected defects were filled. However, the detection of lesions is not synonymous to caries diagnosis. The main purpose of caries diagnosis should be the determination of the caries activity. The diagnosis is based on several parameters, which are evaluated by an intellectual process in a dentally trained mind. The treatment should be confined, in the first instance, to stopping the caries process, and to tipping the balance in the right direction, so that the caries can cure or anyway is prevented from extending. The treatment philosophy has to be pointed to a general approach of the disease caries in the patient who it concerns on the one side, and to a local approach of individual lesions on the other hand. In the second case a lesion can be treated in a symptomatic, invasive manner or, even better, by causal, not-invasive treatment.

Child↗
PubMed1997

[Prevention of caries in children].

There is a stagnation in the previously ongoing improvement of the dental health of children. Therefore, an evaluation of the guidelines for dental care is necessary. Prevention should be based on an improvement of home care. It is advised to use a dentifrice with 500 to 750 ppm fluoride till the age of five. Professional applications in the dental office are most beneficial when early signs of decay are observed. Indications for professional applications are proposed.

Child↗
PubMed1997

[The new fight against mutant streptococci].

Mutans streptococci are an important factor in the aetiology of dental caries. New ways of combating these bacteria have become available with the development of molecular biological techniques. One of these strategies involves the genetic modification of mutans streptococci to develop less cariogenic mutants. Acid production and the production of intracellular polysaccharides have been eliminated. But it is not clear yet whether these less cariogenic mutant strains are able to replace the normal mutans streptococci in dental plaque. Immunization is another possibility to suppress mutans streptococci. Antibodies against proteins involved in adherence of mutans streptococci have been raised by active immunization. It is also possible to raise antibodies in cow serum and milk, in eggs of chickens and even in tobacco plants. After isolation, these antibodies are to be applied topically. In the future, these new strategies may prevent or reduce caries. However, further research is necessary to resolve the obstacles on the way to commercial application.

Antibodies, Bacterial↗
PubMed1996

Protection of bovine enamel and dentine by chlorhexidine and fluoride varnishes in a bacterial demineralization model.

In an in vitro demineralization model, the protective effect of two chlorhexidine varnishes, Cervitec (1% w/w chlorhexidine diacetate and 1% w/w thymol) and EC40 (40% w/w chlorhexidine diacetate), was compared with that of Fluor Protector, a varnish containing 0.1% w/w F. The demineralization model comprised an acidogenic Streptococcus mutans suspension in agarose placed on enamel or dentine specimens. The experiments extended over three serial 22-hour demineralization periods with fresh S. mutans suspensions for each period. To determine whether the varnishes released enough demineralization-inhibiting compounds, approximately 10 microliters of the varnishes was applied adjacent to the enamel and dentine specimens just before the first application of the S. mutans suspensions and left during the serial experiments (release study). In a separate series of experiments, the effect of the pretreatment of the enamal and dentine specimens with the various varnishes was tested (pretreatment study). In the release study the protective effect for enamel decreased in the order: EC40 = Fluor Protector >> Cervitec = no treatment. For dentine this order was: EC40 >> Fluor Protector = Cervitec > no treatment. In the pretreatment study, the enamel specimens were best protected by Fluor Protector (Fluor Protector >> Cervitec = EC40 > no treatment), while the dentine specimens were best protected by the chlorhexidine treatments (Cervitec = EC40 > Fluor Protector > no treatment). A 1:1 mixture of Cervitec and Fluor Protector was as effective as the most effective component alone. It is concluded that a varnish containing both fluoride and chlorhexidine may be useful, since it could give optimal protection to both enamel and dentine.

Animals↗
PubMed1996

Grey discoloration for the diagnosis of secondary caries in teeth with class II amalgam restorations: an in vitro study.

Grey discolouration around occlusal amalgam restorations has been found to be useful for the diagnosis of secondary caries. The aim of the present in vitro study was to establish the validity of grey discolouration of buccal and lingual enamel next to the approximal amalgam of class II restorations for the diagnosis of secondary caries. One hundred buccal and lingual areas next to the approximal parts of a class II filling in molars and premolars were included in the study. Fifty-one areas showed grey discolouration. Validation was performed against radiographs of transverse sections. Both radiolucencies and radiopacities were scored as being caries. The results were: sensitivity 92%, specificity 55%, positive predictive value 22% and negative predictive value 98%. It was concluded that grey discolouration of the approximal walls next to class II amalgam fillings is not useful for the detection of secondary caries, but the absence of grey discolouration gives a good prediction for the absence of secondary caries. This is in contrast to grey discolouration around occlusal amalgam restorations, which was considered to be useful for the diagnosis of secondary caries.

Bicuspid↗
PubMed1996

Prevalence of Streptococcus mutans and lactobacilli in 18-month-old children with cleft lip and/or palate.

The prevalence of Streptococcus mutans and lactobacilli was determined in 62 18-month-old Dutch children with a cleft lip and/or palate. Plaque and saliva samples were collected, a dental examination was performed, and the parents were interviewed with a structured questionnaire regarding general health, dietary habits, fluoride exposure, and socioeconomic class. Appropriate dilutions of the plaque and saliva samples were cultured on selective media to count all viable bacteria, S. mutans and lactobacilli. S. mutans was detected in the saliva of 45% of the children, and lactobacilli was detected in 16%. Also, S. mutans was detected in 48% of the plaque samples and lactobacilli in 8%. Of all of the variables examined, consumption of more than three snacks and beverages between main meals was significantly associated with presence of S. mutans in saliva. Preoperative infant orthopedic treatment (i.e., wearing an acrylic plate from shortly after birth) was significantly associated with presence of lactobacilli in saliva. The presence of S. mutans in the plaque samples was also significantly associated with presence of lactobacilli in saliva. These results indicate that children with oral cleft are at an increased risk of being infected by S. mutans and lactobacilli at a very early age. Such early colonization indicates a high risk for caries in the primary dentition.

Analysis of Variance↗
PubMed1995

Plaque composition, fluoride tolerance and acid production of mutans streptococci before and after the suspension of the use of fluoride toothpastes.

Although fluoride toothpastes are widely used for caries prevention, little is known about the impact of fluoride dentifrices on plaque composition. Also the issue of adaptation of mutans streptococci to grow in vivo in a fluoride environment has received little attention. Such an adaptation may be of interest as it has been suggested that adapted mutans streptococci may show reduced glycolytic activity thereby being less cariogenic. In the present experiments the impact of the suspension of the use of fluoride toothpastes on plaque composition, fluoride tolerance and acid production of mutans streptococci was studied. Pooled plaque samples from the lingual surfaces of the lower incisors were collected from individuals (n = 13) just before and 7 weeks after they had replaced their fluoride toothpastes (0.1-0.15% F) with a non-fluoride one. The samples were analysed for fluoride and the numbers and proportions of streptococci, Streptococcus mutans, Streptococcus sobrinus, Actinomyces species, and lactobacilli, respectively. The fluoride tolerance of the mutans streptococci was estimated by culture of the plaque samples on TYCSB agar supplemented with of 0, 1, 2, 3, 4, and 5 mmol/l fluoride (NaF) at pH 7.2. From each plaque sample six S. mutans strains were isolated for the measurement of the rate of acid production (Vap) at pH 7 in the presence of 0, 5, and 10 mmol/l F. The overnight final pH was measured in cultures of the S. mutans strains with excess of glucose and 0, 5, and 10 mmol/l F. The results showed that the removal of the fluoride pressure from plaque did not affect the numbers or proportions of the various species and genera of bacteria. The fluoride tolerance of the mutans streptococci, and the Vap or the overnight final pH of the isolated strains had not changed. These results suggest that the use of fluoride toothpaste had not affected plaque composition, nor fluoride tolerance or acidogenicity of mutans streptococci. Probably the amount of fluoride delivered by fluoride dentifrices to dental plaque is too low to induce such adaptations.

Adaptation, Physiological↗
PubMed1994

[The electric toothbrush. Present situation].

During the last decade several electric toothbrushes have been introduced with an innovative brushing technique. Scientific research indicates that after proper oral hygiene instruction these toothbrushes can be more effective than a manual toothbrush. This increased efficacy is mainly caused by an improved plaque removal from the proximal surfaces. Besides effectiveness, reasons such as facility and boosting of motivation can be reasons to advise the use of an electric toothbrush. However, these secondary arguments have sofar not been supported by scientific data.

Dental Plaque↗
PubMed1994

[Prevention of dental caries with chlorhexidine].

The presence of > or = 10(6) mutans streptococci per ml saliva may indicate a high caries risk or activity. Individuals exhibiting these high levels of mutans streptococci are ironically called 'millionaires'. It has been demonstrated that the reduction of the mutans streptococci with a series of chlorhexidine gel treatments, reduces the caries incidence in millionaire children. Recently, two chlorhexidine varnishes have been shown to reduce the mutans streptococci in plaque and saliva significantly. It may be expected that the application of these chlorhexidine varnishes may reduce caries incidence in 'millionaires'. It may also be possible to treat individual sites of the teeth that are at risk.

Chlorhexidine↗
PubMed1994

[Efficient preventive dentistry. Concluding article].

In this concluding article by the Dutch Advisory Council on Prevention of Oral Diseases, the relative importance of various aspects of prevention is sorted out. A guideline is presented to dentists, dental hygienists and oral health educators, regarding the contents of an efficient and comprehensive package of basic preventive measures. Subsequently, supplementary measures of prevention are discussed, which should be considered for certain age categories and high-risk groups. Top priority is attributed to regular mechanical cleansing of the dentition, combined with daily administering of fluoride.

Fluorides↗
PubMed1993

Protective effect of topically applied fluoride in relation to fluoride sensitivity of mutans streptococci.

The aim of the present in vitro experiments was to determine whether the protection of enamel by topically applied fluoride against demineralization by bacterial acids would depend on the fluoride sensitivity of the bacteria. Glucose-agarose gel suspensions of fluoride-sensitive and fluoride-resistant mutans streptococci were placed on bovine enamel specimens with different amounts of fluoride. One group of specimens was untreated, a second group had been pretreated with a F-lacquer, and a third group had been pretreated with the F-lacquer and rinsed subsequently with a KOH-solution, to remove deposited CaF2. After 22-hour incubations at 37 degrees C, the amounts of calcium and lactate and the pH of the agarose gels were determined. This procedure was repeated on three consecutive days. Two parent S. mutans strains, one parent S. sobrinus strain, and five fluoride-resistant derivatives were tested. Both pretreatments gave a significant protection to the enamel specimens. For the S. mutans strains, the degree of protection did not depend on the fluoride sensitivity of the strains. For the S. sobrinus strains, the results suggested a reduced protection against demineralization by the fluoride-resistant derivatives. Only from the second group of enamel specimens was enough fluoride released for inhibition of bacterial metabolism. Presumably, it was released by the dissolution of CaF2. It is concluded that a possible adaptation of mutans streptococci in dental plaque to frequent exposures to fluoride will not necessarily decrease the caries-preventive effects caused by topically applied fluoride agents.

Adaptation, Biological↗
PubMed1992

[Saliva, caries and diagnostics].

During the last decades the proportion of children without tooth decay and dental restorations has strongly increased. Yet, some patients show rampant caries or a sudden progression of decay into the dentin. In order to intervene adequately in such cases, it is of importance to determine first of all the underlying causes. Indicators have been developed to predict the progression of caries. By determining the amount of fluoride in the dental plaque one gets insight into the fluoride regime of the patient. One may also determine numbers of caries-pathogenic bacteria in saliva samples, as can now be done with commercially available kits for S. mutans and lactobacilli. The buffering capacity of saliva can also be determined. Although none of these tests have a high predictive value, they are useful in explaining sudden changes in caries activity and to formulate preventive schemes.

Adult↗