Caries control in health service practice.

It is suggested that it makes sense for dentists providing care for individual patients to take account of caries risk (as assessed by presentation of active, non-cavitated lesions) when deciding how to allocate time and effort of themselves and their staff. However, there is a question as to how realistic it is to ask the dental team to provide a full diagnostic assessment and all the preventive treatment required for a patient for the payment provided by 1 UDA. It is to be hoped that one or more of the Steele pilots will come up with a practical solution for controlling caries in NHS practice.

Complete or ultraconservative removal of decayed tissue in unfilled teeth.

BACKGROUND: The treatment of deep dental decay has traditionally involved removal of all the soft demineralised dentine before a filling is placed. However this has been challenged in three groups of studies which involve sealing soft caries into the tooth. The three main groups either remove no caries and seal the decay into the tooth, remove minimal (ultraconservative) caries at the entrance to a cavity and seal the remaining caries in, or remove caries in stages over two visits some months apart to allow the pulp time to lay down reparative dentine (the stepwise excavation technique). OBJECTIVES: To test the null hypothesis of no difference in the incidence of damage or disease of the nerve of the tooth (pulp), progression of decay and longevity of restorations irrespective of whether the removal of decay had been minimal (ultraconservative) or complete. SEARCH STRATEGY: The Cochrane Oral Health Group Trials Register, Cochrane Central Register of Controlled Trials (CENTRAL), MEDLINE, PubMed and EMBASE databases were searched. The reference lists in relevant papers were checked. SELECTION CRITERIA: Randomised controlled trials and controlled clinical trials comparing minimal (ultraconservative) caries removal with complete caries removal in unrestored permanent and deciduous teeth. DATA COLLECTION AND ANALYSIS: Outcome measures recorded were exposure of the nerve of the tooth (pulp) during caries removal, patient experience of symptoms of pulpal inflammation or necrosis, progression of caries under the filling, time until the filling was lost or replaced. Due to the heterogeneity of the included studies the overall estimate of effect was calculated using a random-effects model. MAIN RESULTS: Four studies met the inclusion criteria; two stepwise excavation studies and two ultraconservative caries removal studies. Partial caries removal in symptomless, primary or permanent teeth reduces the risk of pulp exposure. We found no detriment to the patient in terms of pulpal symptoms in this procedure and no reported premature loss or deterioration of the restoration. AUTHORS' CONCLUSIONS: The results of this systematic review reject the null hypothesis of no difference in the incidence of damage or disease of the nerve of the tooth (pulp) irrespective of whether the removal of decay had been minimal (ultraconservative) or complete and accepts the null hypothesis of no difference in the progression of decay and longevity of restorations. However, the number of included studies is small and differ considerably. Partial caries removal is therefore preferable to complete caries removal in the deep lesion, in order to reduce the risk of carious exposure. However, there is insufficient evidence to know whether it is necessary to re-enter and excavate further but studies that have not re-entered do not report adverse consequences.

Effect of withdrawal of fluoride-containing toothpaste on the interproximal plaque microflora.

To compare the effects of fluoride-containing and fluoride-free toothpaste on plaque microflora, 15 subjects were enrolled in a double-blind crossover trial. All subjects used a fluoride toothpaste for 7 days before the trial started. Then, 4 interproximal sites per subject were professionally cleaned and subjects used one of the toothpastes for 5 days. On the 5th day plaque was collected from 2 sites, 12 and 6 h after toothpaste use. There was no difference between the groups in the numbers or proportions of aciduric bacteria (recovered at pH 4.8 or 5.2), or of yeasts, neisseriae, lactobacilli or streptococci (total or individual species, including Streptococcus mutans). However, the numbers and proportions of Gram-positive pleomorphic rods, primarily Actinomyces naeslundii, increased in 6-hour samples from subjects using fluoride toothpaste. The data suggest that the anti-caries effect of fluoride toothpaste is not mediated primarily through effects on the plaque microflora, although effects on plaque physiology could be important.

Phenotypic and genotypic selection of microbiota surviving under dental restorations.

The effects of sealing infected carious dentine below dental restorations on the phenotypic and genotypic diversity of the surviving microbiota was investigated. It was hypothesized that the microbiota would be subject to nutrient limitation or nutrient simplification, as it would no longer have access to dietary components or salivary secretion for growth. The available nutrients would be limited primarily to serum proteins passing from the pulp through the patent dentinal tubules to the infected dentine. Ten lesions were treated, and infected dentine was sealed below dental restorations for approximately 5 months. Duplicate standardized samples of infected dentine were taken at baseline and after the removal of the restorations. The baseline microbiota were composed primarily of Lactobacillus spp., Streptococcus mutans, Streptococcus parasanguinis, Actinomyces israelii, and Actinomyces gerencseriae. None of these taxa were isolated among the microbiota of the dentine samples taken after 5 months, which consisted of only Actinomyces naeslundii, Streptococcus oralis, Streptococcus intermedius, and Streptococcus mitis. The microbiota of the final sample exhibited a significantly (P < 0.001) increased ability to produce glycosidic enzymes (sialidase, beta-N-acetylglucosaminidase, and beta-galactosidase), which liberate sugars from glycoproteins. The genotypic diversity of S. oralis and A. naeslundii was significantly (P = 0.002 and P = 0.001, respectively) reduced in the final samples. There was significantly (P < 0.001) greater genotypic diversity within these taxa between the pairs of dentine samples taken at baseline than was found in the 5-month samples, indicating that the dentine was more homogenous than it was at baseline. We propose that during the interval between placement of the restorations and their removal, the available nutrient, primarily serum proteins, or the relative simplicity and homogeneity of the nutrient supply significantly affected the surviving microbiota. The surviving microbiota was less complex, based on compositional, phenotypic, and genotypic analyses, than that isolated from carious lesions which were also exposed to salivary secretions and pH perturbations.

The microflora of the erupting first permanent molar.

The relationship between microflora, eruption status and caries status in the first permanent molar of young children was investigated in 177 children aged 6-7 years. A significantly greater proportion of fully erupted teeth were classified as sound and plaque-free compared to partially erupted teeth. Fully erupted teeth yielded greater numbers and proportions of mutans streptococci compared with significantly greater numbers and proportions of Actinomyces israelii in partially erupted teeth. Logistical regression analysis showed significant associations between white spot lesions in partially erupted teeth and increased numbers of Streptococcus oralis, mutans streptococci and Streptococcus salivarius whereas the presence of Actinomyces naeslundii was associated with health. Significantly greater numbers and proportions of S. oralis and S. salivarius were isolated from partially erupted teeth with white spot lesions whereas Streptococcus mutans was isolated in significantly greater numbers and proportions from fully erupted molars with white spots. This study suggests that organisms other than mutans streptococci are associated with caries development in erupting permanent molar teeth.

What constitutes dental caries? Histopathology of carious enamel and dentin related to the action of cariogenic biofilms.

Substantial pH fluctuations within the biofilm on the tooth surface are a ubiquitous and natural phenomenon, taking place at any time during the day and night. The result may be recordable in the dental tissues at only a chemical and/or ultrastructural level (subclinical level). Alternatively, a net loss of mineral leading to dissolution of dental hard tissues may result in a caries lesion that can be seen clinically. Thus, the appearance of the lesion may vary from an initial loss of mineral, seen only in the very surface layers at the ultrastructural level, to total tooth destruction. Regular removal of the biofilm, preferably with a toothpaste containing fluoride, delays or even arrests lesion progression. This can occur at any stage of lesion progression, because it is the biofilm at the tooth or cavity surface that drives the caries process. Active enamel lesions involve surface erosion and subsurface porosity. Inactive or arrested lesions have an abraded surface, but subsurface mineral loss remains, and a true subsurface remineralization is rarely achievable, because the surface zone acts as a diffusion barrier. The dentin reacts to the stimulus in the biofilm by tubular sclerosis and reactionary dentin.

How 'clean' must a cavity be before restoration?

The metabolic activity in dental plaque, the biofilm at the tooth surface, is the driving force behind any loss of mineral from the tooth or cavity surface. The symptoms of the process (the lesion) reflect this activity and can be modified by altering the biofilm, most conveniently by disturbing it by brushing with a fluoride-containing toothpaste. The role of operative dentistry in caries management is to restore the integrity of the tooth surface so that the patient can clean. Thus, the question, 'how clean must a cavity be before restoration?' may be irrelevant. There is little evidence that infected dentine must be removed prior to sealing the tooth. Leaving infected dentine does not seem to result in caries progression, pulpitis or pulp death. However, some of the bacteria survive. What is their fate and if they are not damaging, why is this?

Relationships between a clinical-visual scoring system and two histological techniques: a laboratory study on occlusal and approximal carious lesions.

One aim of the present laboratory study was to determine whether a visual scoring system (ERK) developed for occlusal caries could be applied to approximal lesions. A new histological technique (autofluorescence, AF) recognises dentine that is soft and would be removed with an excavator during operative treatment. A second aim was to investigate the relationship between the visual scoring system (ERK) and AF of dentine both occlusally and approximally. The sample comprised 93 extracted teeth chosen to represent the range of visual scores on approximal and occlusal surfaces. After sectioning through the investigation site, the cut faces were examined in a stereomicroscope and the depth of demineralization was scored. Autofluorescence was viewed with a confocal laser scanning microscope. Results showed reasonable correlation between the visual scores and the stereomicroscope histological evaluations for occlusal surfaces and non-cavitated approximal surfaces. However, cavitated approximal surface lesions were less advanced histologically than cavitated occlusal carious lesions. The AF technique indicated that several lesions with intact surfaces would have had soft, excavatable dentine, whereas several with microcavities would not.

The effect of chlorhexidine acetate/xylitol chewing gum on the plaque and gingival indices of elderly occupants in residential homes.

AIM: A randomised, controlled, double-blind, clinical trial was conducted to investigate the effect of a chlorhexidine acetate/xylitol gum (ACHX) on the plaque and gingival indices of 111 elderly occupants in residential homes. A gum containing xylitol alone (X) and a no gum (N) group was included. Participants' opinions about chewing gum were also investigated. METHODS: Subjects chewed 2 pellets, for 15 min, 2x daily for 12 months. RESULTS: In the ACHX group, the plaque and gingival indices significantly decreased (p<0.001) over the 12 months. In the X group, only the plaque score significantly decreased (p<0.05) and in the N control group, both indices remained high and did not change significantly. The acceptance of both chewing gums was high but more participants in the ACHX group felt that the gum kept their mouth healthy (p<0.05). The effect of the ACHX gum on plaque and gingival indices was significantly greater than for the X gum. CONCLUSION: The long-term use of a chlorhexidine acetate/xylitol chewing gum may therefore support oral hygiene routines for an elderly dependent population.

Diagnosis of secondary caries.

A systematic review of the diagnosis of dental caries was produced before the conference. It did not include the diagnosis of secondary or recurrent caries. This was a wise decision because what little literature exists on the subject potentially clouds the issue. Diagnosis is a mental resting place on the way to a treatment decision. A vital part of caries diagnosis is to decide whether a lesion is active and rapidly progressing or already arrested. This information is essential to plan logical management. However, lesion activity should be judged in the patient. Thus, research on the diagnosis of secondary caries must be carried out in vivo and this usually precludes histological validation. Even if such validation is possible, it has its own problems, particularly in distinguishing recurrent from residual caries. The diagnosis of secondary caries is very important since so many restorations are replaced because dentists think there is a new decay. It will be important to establish valid criteria for the diagnosis of active secondary caries, which will be facilitated by the suggestion that secondary caries is no different from primary caries except that it occurs next to a filling. This implies that it can be seen clinically and on a radiograph, next to a restoration.

Dentine caries: take it or leave it?

In modern dentistry the primary aim when excavating carious dentine is to eradicate only the highly infected, irreversibly demineralised and denatured biomass in order to allow effective restoration of the cavity, restoration of the surface anatomy of the tooth and to prevent disease progression. However, the boundary between this superficial zone of dentine requiring excavation and the deeper, affected but repairable tissue is not always obvious either in the clinic or in the research laboratory. The inherent subjectivity in detecting this excavation boundary can result in clinically significant differences in the quality and quantity of dentine removed by different operators and makes the in vitro comparison of newer excavation techniques more difficult. This article discusses the rationale behind carious dentine excavation and the criteria available to the dentist, both clinical and laboratory, to help identify the dentine requiring removal.

A clinical and microbiological study of approximal carious lesions. Part 2: efficacy of caries removal following tunnel and class II cavity preparations.

A randomized controlled clinical study was set up to assess caries removal following tunnel preparation (test group) and class II cavity preparation (control group). Sixty approximal lesions in adult posterior teeth, visible in the outer third of dentine on bite-wing radiographs, were referred for operative treatment. Initial dentine samples were taken on entry to the lesions in both groups. Following cavity preparation dentine samples were taken from beneath the marginal ridge in the tunnel group and at the cervical floor in both groups. Microbiological analysis was carried out to establish the level of infection of the dentine. The bacterial counts were high on entry to the lesions with a median log10 (CFU + 1) per sample of 3.07 (+/-1.24). Following cavity preparation bacterial counts at the cervical floor were significantly reduced in both amalgam and tunnel groups (p<0.00001). In the tunnel group, however, slightly increased bacterial counts were found beneath the marginal ridge compared to the cervical floor (p<0.01).

A clinical and microbiological study of approximal carious lesions. Part 1: the relationship between cavitation, radiographic lesion depth, the site-specific gingival index and the level of infection of the dentine.

A clinical study was carried out to assess relationship between the presence of approximal cavitation, the radiographic depth of the lesion, the site-specific gingival index and the level of infection of the dentine. Adult patients assessed as needing operative treatment and presenting with approximal lesions visible in the outer third of dentine on bite-wing radiographs were included in the study. Direct lesion depth measurements were recorded from the radiographs and the site-specific gingival index adjacent to the lesion was noted. The presence or absence of a cavity was recorded on an impression following tooth separation. During operative treatment samples of dentine were taken on entry to the lesions to ascertain the level of infection of the dentine. Visual evaluation of 54 successfully recorded impressions revealed that 85% were cavitated. Cavitated lesions were found to have higher site-specific gingival index scores compared to non-cavitated lesions (p = 0.03). The probability of cavitation was greater for lesions >0.5 mm from the enamel-dentine junction on bite-wing radiographs (p<0.01). The level of infection of the dentine was significantly higher for cavitated lesions than for non-cavitated lesions (p = 0.02). However, the non-cavitated lesions were still infected.

Occlusal caries: pathology, diagnosis and logical management.

Occlusal caries now accounts for most of the lesions in children aged 8-15 years. This paper presents a ranked visual scoring system for occlusal caries diagnosis. It relates the clinical appearance of the lesion to its activity, the level of infection of the dentine and the histopathology. The appropriate management for each score is suggested.

Relationship between oral hygiene practices and oral status in dentate elderly people living in residential homes.

OBJECTIVES: To investigate the relationship between the oral hygiene practices of dentate elderly people living in residential homes, their requests for assistance and their oral health status. METHODS: 164 people (81.2+/-7.4 years) participated in an interview and oral examination, and provided a stimulated saliva sample. RESULTS: The mean number of coronal decayed surfaces (CDS) was 2.4+/-5.9, stimulated salivary levels (log(10)cfu/ml) of mutans streptococci, lactobacilli and yeasts were 1.6+/-2.1, 3.0+/-2.2, 2.1+/-1.7, respectively, and 53% had root decayed surfaces (RDS). Plaque (PI) and gingival (GI) Indices were 2.3+/-0.7 and 1.6+/-0.4 and denture debris scores (DDS) were high. 31% of the population cleaned their mouths twice daily without requesting help and they had significantly fewer yeasts, RDS, restorations on root surfaces, lower PI, GI (P<0.005) and DDS (P<0.0001) than the 69% who cleaned less often. 50% of those who cleaned less frequently requested assistance with oral hygiene but only 5% said that their carers supported them. Those residents who requested help had significantly higher levels of yeasts, lactobacilli (P<0.001), retained roots, DDS, RDS (P<0.005), PI and GI (P<0.0001). CONCLUSION: The elderly residents' perceived need for assistance with oral hygiene was related directly to oral hygiene status and to clinical indicators of mucosal and dental diseases.

Comparison between visual examination and a laser fluorescence system for in vivo diagnosis of occlusal caries.

This study compared a laser fluorescence (LF) system (DIAGNOdent) with a visual caries scoring system for in vivo detection and diagnosis of occlusal caries under the conditions of an epidemiological study, in 132 mandibular and 38 maxillary first permanent molars in 170 children (mean age: 6.85 +/- 0.58 years). The teeth were cleaned and occlusal caries status in a selected investigation site recorded using both visual and LF systems. The LF readings were interpreted both according to the cut-off points recommended by the manufacturers and those based on laboratory research with histological validation. The percentage agreement of the LF and visual scoring system was better using the cut-off limits recommended by the manufacturer. Histological validation was not possible in this clinical study, but it appeared that either the LF method was overscoring some lesions or the visual method was underscoring them. Since the LF instrument cannot be expected to differentiate caries from hypomineralisation, it should probably be used as an adjunct to a clinical examination.

Genotypic heterogeneity of Streptococcus oralis and distinct aciduric subpopulations in human dental plaque.

The genotypic heterogeneity of Streptococcus oralis isolated from the oral cavity was investigated using repetitive extragenic palindromic PCR. Unrelated subjects harbored unique genotypes, with numerous genotypes being isolated from an individual. S. oralis is the predominant aciduric bacterium isolated from noncarious tooth sites. Genotypic comparison of the aciduric populations isolated at pH 5.2 with those isolated from mitis-salivarius agar (MSA) (pH 7.0) indicated that the aciduric populations were genotypically distinct in the majority of subjects (chi(2) = 13.09; P = 0.0031). Neither the aciduric nor the MSA-isolated strains were stable, with no strains isolated at baseline being isolated 4 or 12 weeks later in the majority of subjects. The basis of this instability is unknown but is similar to that reported for Streptococcus mitis. Examination of S. oralis strains isolated from cohabiting couples demonstrated that in three of five couples, genotypically identical strains were isolated from both partners and this was confirmed by using Salmonella enteritidis repetitive element PCR and enterobacterial PCR typing. These data provide further evidence of the physiological and genotypic heterogeneity of non-mutans streptococci. The demonstration of distinct aciduric populations of S. oralis implies that the role of these and other non-mutans streptococci in the caries process requires reevaluation.

Dentine caries excavation: a review of current clinical techniques.

Since the invention and application of rotary instruments, the operative treatment of carious lesions has often resulted in considerable removal of tooth structure. More recently, newer techniques for removal of carious dentine have been developed in an attempt to minimise this excessive tissue loss. The following article reviews and discusses some of the techniques available to excavate demineralised dentine clinically. These methods can be classified as mechanical and non-mechanical, rotary and non-rotary and include: dental handpieces/burs, manual excavators, air-abrasion, air-polishing, ultrasonication, sono-abrasion, chemo-mechanical methods, lasers and enzymes. The advantages and disadvantages of each technique are discussed.