pH Landscapes in a Novel Five-Species Model of Early Dental Biofilm

Despite continued preventive efforts, dental caries remains the most common disease of man. Organic acids produced by microorganisms in dental plaque play a crucial role for the development of carious lesions. During early stages of the pathogenetic process, repeated pH drops induce changes in microbial composition and favour the establishment of an increasingly acidogenic and aciduric microflora. The complex structure of dental biofilms, allowing for a multitude of different ecological environments in close proximity, remains largely unexplored. In this study, we designed a laboratory biofilm model that mimics the bacterial community present during early acidogenic stages of the caries process. We then performed a time-resolved microscopic analysis of the extracellular pH landscape at the interface between bacterial biofilm and underlying substrate.-grown dental plaque. We employed the pH-sensitive ratiometric probe C-SNARF-4 to perform real-time microscopic analyses of the biofilm pH in response to salivary solutions containing glucose. Anaerobic glycolysis in the model biofilms created a mildly acidic environment. Decrease in pH in different areas of the biofilms varied, and distinct extracellular pH-microenvironments were conserved over several hours.-grown bacterial biofilms

Monitoring of extracellular pH in young dental biofilms grown in vivo in the presence and absence of sucrose

Background and objective: pH in dental biofilms is of central importance for the development of caries. We used the ratiometric pH-sensitive dye C-SNARF-4 in combination with digital image analysis to monitor extracellular pH in dental biofilms grown in situ with and without sucrose supply. Design: Dental biofilms (48 h) from 10 individuals were collected on glass slabs mounted on intra-oral appliances. During growth, appliances were immersed extra-orally in either physiological saline or 4% sucrose for 2 min, eight times per day. Fluorescence emissions of C-SNARF-4 in deep layers of the biofilms were recorded ex vivo with confocal microscopy for 15 min or for 1 h after exposure to 0.4% glucose. Extracellular pH was determined ratiometrically using digital image analysis. Results: Extracellular pH dropped rapidly in most examined sites after addition of glucose. Distinct pH microenvironments were observed within single biofilms. The variation in pH was similar between sites within the same biofilm and sites from different individuals. pH drop patterns did not differ between biofilms exposed to sucrose-free and sucrose-rich environments. Conclusion: The present study is the first of its kind to apply the combination of pH ratiometry and digital image analysis to systematically record extracellular pH in intact dental biofilms from several individuals for up to 1 h. We observed highly heterogeneous pH landscapes and the presence of acidogenic microenvironments – ‘acidogenic hotspots’ – within the biofilms. The data suggest that pH drops in young (48 h) dental biofilms are independent of the sucrose supply during growth

Occlusal Caries: Biological Approach for Its Diagnosis and Management.

The management of occlusal caries still remains a major challenge for researchers as well as for general practitioners. The present paper reviews and discusses the most up-to-date knowledge and evidence of the biological principles guiding diagnosis, risk assessment, and management of the caries process on occlusal surfaces. In addition, it considers the whole spectrum of the caries process on occlusal surfaces, ranging from the molecular ecology of occlusal biofilms to the management of deep occlusal caries lesions. Studies using molecular methods with focus on biofilms in relation to occlusal caries should explore the relationship between the function and the structural composition of these biofilms to understand the role of occlusal biofilms in caries development. State-of-the-art measures to evaluate risk for occlusal caries lesion activity, caries incidence, and progression should include the assessment of the occlusal biofilm and the stage of tooth eruption. Careful clinical examination of non-cavitated lesions, including assessment of the lesion activity status, remains the major tool to determine the immediate treatment need and to follow on the non-operative treatment outcome. Even medium occlusal caries lesions in the permanent dentition may be treated by non-invasive fissure sealing. By extending the criteria for non-invasive treatments, traditional restoration of occlusal surfaces can be postponed or even avoided, and the dental health in children and adolescents can be improved. Selective removal (incomplete) to soft dentin in deep carious lesions has greater success rates than stepwise excavation. Selective (complete) removal to firm dentin has a lower success rate due to increased pulp exposure

Randomized Clinical Trials on Deep Carious Lesions : 5-Year Follow-up

Deep caries presents a dilemma in terms of which treatment that will render an optimal prognosis by maintaining pulp vitality with absence of apical pathology. Previously, 2 randomized clinical trials were performed testing the short-term effects of stepwise carious tissue removal versus nonselective carious removal to hard dentin with or without pulp exposure. The aim of this article was to report the 5-y outcome on these previously treated patients having radiographically well-defined carious lesions extending into the pulpal quarter of the dentin but with a well-defined radiodense zone between the carious lesion and the pulp. In this long-term study, 239 of 314 (76.2%) patients were analyzed. The stepwise removal group had a significantly higher proportion of success (60.2%) at 5-y follow-up compared with the nonselective carious removal to hard dentin group (46.3%) ( P = 0.031) when pulp exposures per se were included as failures. Pulp exposure rate was significantly lower in the stepwise carious removal group (21.2% vs. 35.5%; P = 0.014). Irrespective of pulp exposure status, the difference (13.3%) was still significant when sustained pulp vitality without apical radiolucency and unbearable pain was considered (95% confidence interval, 3.1-26.3, P = 0.045). After pulp exposure, only 9% ( n = 4) of the analyzed patients were assessed as successful, indicating that the prognosis is highly dubious following conventional pulp-capping procedures (direct pulp capping or partial pulpotomy) in deep carious lesions in adults. In conclusion, the stepwise carious removal group had a significantly higher proportion of pulps with sustained vitality without apical radiolucency versus nonselective carious removal of deep carious lesions in adult teeth at 5-y follow-up (ClinicalTrials.gov NCT00187837 and NCT00187850)

Treatment of deep caries lesions in adults : randomized clinical trials comparing stepwise vs. direct complete excavation, and direct pulp capping vs. partial pulpotomy

Less invasive excavation methods have been suggested for deep caries lesions. We tested the effects of stepwise vs. direct complete excavation, 1 yr after the procedure had been carried out, in 314 adults (from six centres) who had received treatment of a tooth with deep caries. The teeth had caries lesions involving 75% or more of the dentin and were centrally randomized to stepwise or direct complete excavation. Stepwise excavation resulted in fewer pulp exposures compared with direct complete excavation [difference: 11.4%, 95% confidence interval (CI) (1.2; 21.3)]. At 1 yr of follow-up, there was a statistically significantly higher success rate with stepwise excavation, with success being defined as an unexposed pulp with sustained pulp vitality without apical radiolucency [difference: 11.7%, 95% CI (0.5; 22.5)]. In a subsequent nested trial, 58 patients with exposed pulps were randomized to direct capping or partial pulpotomy. We found no significant difference in pulp vitality without apical radiolucency between the two capping procedures after more than 1 yr [31.8% and 34.5%; difference: 2.7%, 95% CI ()22.7; 26.6)]. In conclusion, stepwise excavation decreases the risk of pulp exposure compared with direct complete excavation. In view of the poor prognosis of vital pulp treatment, a stepwise excavation approach for managing deep caries lesions is recommended

Biofilms in chronic infections – a matter of opportunity – monospecies biofilms in multispecies infections

Appeal from Judgment in the Third Judicial District Court in Summit County, Honorable Homer Wilkinson, Judg

Terminology of Dental Caries and Dental Caries Management: Consensus Report of a Workshop Organized by ORCA and Cariology Research Group of IADR

A 2-day workshop of ORCA and the IADR Cariology Research Group was organized to discuss and reach consensus on definitions of the most commonly used terms in cariology. The aims were to identify and to select the most commonly used terms of dental caries and dental caries management and to define them based on current concepts. Terms related to definition, diagnosis, risk assessment, and monitoring of dental caries were included. The Delphi process was used to establish terms to be considered using the nominal group method favored by consensus. Of 222 terms originally suggested by six cariologists from different countries, a total of 59 terms were reviewed after removing duplicates and unnecessary words. Sixteen experts in cariology took part in the process of reaching consensus about the definitions of the selected caries terms. Decisions were made following thorough “round table” discussions of each term and confirmed by secret electronic voting. Full agreement (100%) was reached on 17 terms, while the definitions of 6 terms were below the agreed 80% threshold of consensus. The suggested terminology is recommended for use in research, in public health, as well as in clinical practice