In vitro biofilm models to study dental caries: a systematic review.

The aim of this systematic review is to characterize and discuss key methodological aspects of in vitro biofilm models for caries-related research and to verify the reproducibility and dose-response of models considering the response to anti-caries and/or antimicrobial substances. Inclusion criteria were divided into Part I (PI): an in vitro biofilm model that produces a cariogenic biofilm and/or caries-like lesions and allows pH fluctuations; and Part II (PII): models showing an effect of anti-caries and/or antimicrobial substances. Within PI, 72.9% consisted of dynamic biofilm models, while 27.1% consisted of batch models. Within PII, 75.5% corresponded to dynamic models, whereas 24.5% corresponded to batch models. Respectively, 20.4 and 14.3% of the studies reported dose-response validations and reproducibility, and 32.7% were classified as having a high risk of bias. Several in vitro biofilm models are available for caries-related research; however, most models lack validation by dose-response and reproducibility experiments for each proposed protocol.

An in vitro dynamic microcosm biofilm model for caries lesion development and antimicrobial dose-response studies.

Some dynamic biofilm models for dental caries development are limited as they require multiple experiments and do not allow independent biofilm growth units, making them expensive and time-consuming. This study aimed to develop and test an in vitro dynamic microcosm biofilm model for caries lesion development and for dose-response to chlorhexidine. Microcosm biofilms were grown under two different protocols from saliva on bovine enamel discs for up to 21 days. The study outcomes were as follows: the percentage of enamel surface hardness change, integrated hardness loss, and the CFU counts from the biofilms formed. The measured outcomes, mineral loss and CFU counts showed dose-response effects as a result of the treatment with chlorhexidine. Overall, the findings suggest that biofilm growth for seven days with 0.06 ml min(-1) salivary flow under exposure to 5% sucrose (3 × daily, 0.25 ml min(-1), 6 min) was suitable as a pre-clinical model for enamel demineralization and antimicrobial studies.

[A PhD completed 5. Restoration survival in the composite resin age]. / Hora est 5. Levensduur van composietrestauraties in posterieure gebitselementen.

The article describes studies aimed at investigating factors that can influence composite restoration survival in posterior teeth, focusing on the main reasons for failure of direct restorations - fracture and secondary-caries. Since direct composite resin restaurations seem to be more prone to secondary caries when compared to amalgam, one study was performed to evaluate the influence of materials on secondary caries lesion formation in situ. Also, in most clinical studies evaluating restoration survival, there is a tendency to focus on materials factors. Two retrospective clinical investigations, a meta-analysis with primary data of clinical studies and a systematic review were performed to assess the influence of patient-, materials-, and tooth-related variables in posterior composite restoration survival. Composite resins were not related with higher mineral loss when compared to amalgam. Tooth type, number of restored surfaces and patient-related factors like a high caries risk and occlusal wear were consistently found to influence composite resin restoration survival in posterior teeth, whereas materials factors were not consistently implicated with the survivalrate.

Correlation between the cariogenic response in biofilms generated from saliva of mother/child pairs.

This study aimed to correlate the cariogenic responsiveness of biofilms generated from the saliva of mothers and children. The mother-child pairs were classified according to the children's caries levels: caries-free, early childhood caries (ECC) or severe ECC. Microcosm biofilms were grown on enamel discs for 10 days. Factors under evaluation were caries experience levels, inoculum source (mothers and children) and growth conditions including cariogenic challenge (growth medium provided with and without sucrose) and no cariogenic challenge (growth medium sucrose-free). Statistical analysis was performed with ANOVA and Tukey's test, and the Spearman correlation test. Regular sucrose exposure resulted in a higher surface hardness change (%SHC). The correlation between biofilms formed from saliva of mother-child pairs was significant regarding pH, total aciduric microorganisms and lactobacilli counts under cariogenic challenge. Biofilm growth originating from mother-child pairs under regular sucrose exposure promoted the same cariogenic response independently of caries experience and the microbiological profile of the donors.

Diagnostic Strategies for Restorations Management: A 70-Month RCT.

We aimed to evaluate the impact of 2 visual diagnostic strategies for assessing secondary caries and managing permanent posterior restorations on long-term survival. We conducted a diagnostic cluster-randomized clinical trial with 2 parallel groups using different diagnostic strategies: (C+AS) based on caries assessment, marginal adaptation, and marginal staining aspects of the FDI (World Dental Federation) criteria and (C) based on caries assessment using the Caries Associated with Restorations or Sealants (CARS) criteria described by the International Caries Detection and Assessment System (ICDAS). The treatment for the restoration was conducted based on the decision made following the allocated diagnostic strategy. The restorations were then clinically reevaluated for up to 71 mo. The primary outcome was restoration failure (including tooth-level failure: pain, endodontic treatment, and extraction). Cox regression analyses with shared frailty were conducted in the intention-to-treat population, and hazard ratios (HRs) and 95% confidence intervals (95% CIs) were derived. We included 727 restorations from 185 participants and reassessed 502 (69.1%) restorations during follow-up. The evaluations occurred between 6 and 71 mo. At baseline, C led to almost 4 times fewer interventions compared with the C+AS strategy. A total of 371 restorations were assessed in the C group, from which 31 (8.4%) were repaired or replaced. In contrast, the C+AS group had 356 restorations assessed, from which 113 (31.7%) were repaired or replaced. During follow-up, 34 (9.2%) failures were detected in the restorations allocated to the C group and 30 (8.4%) allocated to the C+AS group in the intention-to-treat population, with no significant difference between the groups (HR = 0.83; 95% CI = 0.51 to 1.38; P = 0.435, C+AS as reference). In conclusion, a diagnostic strategy focusing on marginal defects results in more initial interventions but does not improve longevity over the caries-focused strategy, suggesting the need for more conservative approaches.

Self-etching dental adhesive containing a natural essential oil: anti-biofouling performance and mechanical properties.

This study assessed the anti-biofouling performance of an experimental adhesive system containing a naturally occurring essential vegetable oil and examined the following physical and mechanical properties: water sorption (WS) and solubility (SL), microtensile bond strength to dentin (µTBS), and degree of conversion. The following six groups were tested: a self-etching experimental adhesive containing refined essential oil from the seeds of the Butia capitata tree (EAO); an oil-free version of the experimental adhesive (EANO); one group without adhesive as the control (C); and the three following commercial self-etching adhesives: Clearfil Protect Bond (CPB), Clearfil SE Bond, and Adper SE Plus. The antibacterial effect was estimated by microbiological culture on selective/non-selective media, and the results expressed as colony-forming units per unit weight of dry biofilm (CFU mg(-1)). The data were submitted to ANOVA and Tukey's post hoc test (α = 0.05). After 24 h, pH changes were similar in the storage medium of all tested adhesive systems. EAO showed similar levels of antimicrobial activity in a model biofilm microcosm as the commercial self-etching adhesive CPB. Both were effective against total microorganisms, aciduric bacteria, lactobacilli, and Streptococcus mutans. WS and SL were not affected by the presence of the essential oil; the values of EAO were similar to or less than those of commercial equivalents. The incorporation of an essential oil into an experimental adhesive did not influence its monomer conversion result. Immediate µTBS values of EAO and EANO were similar and were greater than those of commercial equivalents. After storage for 6 months, the µTBS of the EAO decreased significantly and became similar to the values of commercial equivalents, while the strength of the EANO was not affected.

An in vitro biofilm model for enamel demineralization and antimicrobial dose-response studies.

Microcosm biofilms formed in microplates have demonstrated complex community dynamics similar to natural dental biofilm. No simplified microcosm models to evaluate enamel demineralization and dose-response effect to anticariogenic therapies have yet been established, thus this study was designed to develop a pre-clinical model fulfilling this purpose. Experiments were carried out to establish the time of biofilm formation and the sucrose concentration and exposure regimen. Biofilms were initiated from saliva and grown for up to 10 days on bovine enamel discs in 24-well plates, with a saliva analogue medium. Data were collected as pH readings and the percentage enamel surface hardness change. A dose-response evaluation was performed with chlorhexidine, which significantly affected the pH and mineral loss. Overall, the established model parameters, 5 days of biofilm growth with intermittent 1% sucrose exposure of 6 h per day, was suitable as a pre-clinical model for enamel demineralization and dose-response studies.

Microcosm biofilms originating from children with different caries experience have similar cariogenicity under successive sucrose challenges.

OBJECTIVES: The source of saliva inocula and the individual characteristics of saliva donors could affect the cariogenic activity of in vitro biofilms, but this could also be modulated by environmental determinants, such as the frequency of sugar consumption. Therefore, the aim of this study was to compare the cariogenicity of microcosm biofilm growths from the saliva of caries-free (CF) children, children with early childhood caries (ECC) and with severe ECC (S-ECC), under regular sucrose exposure. METHODS: Microcosm plaque biofilms were initiated from the saliva of CF, ECC and S-ECC children. Biofilms were grown in 24-well microplates on bovine enamel discs for up to 10 days in artificial saliva, which was replaced daily. Growth conditions comprised cariogenic challenge (artificial saliva supplemented with 1% sucrose 6 h/day) or no cariogenic challenge. Daily pH was obtained from the artificial saliva, and after the experimental period, the biofilm formed on the enamel discs was collected for microbiological analyses. Mineral loss in enamel discs was estimated by percentage of surface hardness change. RESULTS: Overall, no statistically significant differences were found among saliva sources (p > 0.05). Streptococcus mutans and lactobacilli counts increased in the biofilms grown under cariogenic challenge (p < 0.05), while a substantial decrease in the artificial saliva pH was detected under the same condition (p < 0.001). Higher demineralization (p < 0.001) was observed under sucrose exposure regardless of caries experience of children. CONCLUSIONS: While the sucrose exposure determined the cariogenicity of the biofilms, the caries experience of children who provided the inocula did not affect mineral loss associated with these biofilms.

[Cystatin C as estimator of glomerular filtration rate in patients with advanced chronic renal disease]. / Cistatina C como estimador de la función renal en estadios avanzados de enfermedad renal crónica.

Serum cystatin C (CysC) has been shown to be more accurate than serum creatinine (Cr) in estimating renal function, especially in patients with mildmoderate chronic renal failure. However, it is unknown whether CysC provides or not any advantage over Cr in severe chronic renal failure. The aim of this study was to establish the accuracy of CysC in estimating the glomerular filtration rate (GFR) in advanced chronic renal failure patients. The study group consisted of 94 patients (57 females, mean age 61 +/- 16 years) with advanced chronic renal failure. None of them had thyroid dysfunction or was on corticoid treatment. CFR was measured by TC99mDTPA, and simultaneously, serum CysC (particle enhanced immunonephelometry) and Cr (modified Jaffe's kinetic reaction) were also determined. Serum Cr and CysC levels were correlated with GFR, and the influences of age, sex and diabetes on these correlations were analyzed. The predictive value of CysC and Cr to estimate a GFR less than 15 ml/min/1.73 m2 was analyzed by measuring the crea-under-the-curve (AUC) with Receiver-Operating Characteristics (ROC) plots. The mean CFR was 16.49 +/- 4.65 ml/min/1.73 m2. The mean concentrations of Cr and CysC were 4.19 +/- 1.19 mg/L and 3.44 +/- 0.73 mg/L, respectively. Both Cr and CysC correlated significantly with GFR (R = 0.49, p < 0.0001 and R = 0.52, p < 0.0001, respectively). Age and sex influenced on the correlation between Cr and GFR, but these demographic characteristics did not influence on the correlation between CysC and GFR. The AUC for the prediction of a GFR less than 15 ml/min/1.73 m2 with serum Cr was 0.675 (p = 0.004), while with CysC was 0.633 (p = 0.030). In conclusion, both serum Cr and CysC are highly inaccurate markers of renal function in advanced chronic renal failure patients.

Restoration Survival: Revisiting Patients' Risk Factors Through a Systematic Literature Review.

A literature review was conducted to investigate the influence of patient-related factors on restoration survival in posterior permanent teeth as well as to report the methods used to collect these factors. The selection of articles on longitudinal clinical studies investigating the survival of posterior restorations (except full crowns and temporary fillings) and including patient-related factors was performed by applying predefined criteria. The review was organized into two parts, the first describing how patient factors were assessed in the studies (n=45) and the second presenting the statistical significance (n=27) and size of the effect (n=11) of these factors on restoration survival. Patient-related factors mentioned in the studies included age; gender; caries risk; caries activity/severity; decayed, missing, filled teeth; number of restorations; oral hygiene; and bruxism, among others. Sixteen studies included the patient age or age range in the analysis, which was found to be significant in 47% of the studies. Regarding gender, four of 17 reports found a significant effect on survival, showing more failures for men in three studies. The caries risk profile or related variables were included in the analysis of 15 studies, and a significant effect on survival was reported for high-caries-risk individuals (or related variables) in 67% of these studies. Bruxism was also found to influence restoration survival in three of six studies where this variable was investigated. Some issues were found regarding the reporting of methods used to classify patients according to risk and were thoroughly discussed. In view of the information gathered in this review, the assessment of patient factors along with other variables should become part of clinical studies investigating restoration survival, since several of these factors were shown to influence the failure of restorations, regardless of the material type.

Restoration materials and secondary caries using an in vitro biofilm model.

This in vitro study investigated whether restoration materials and adhesives influence secondary caries formation in gaps using a short-term in vitro biofilm model. Sixty enamel-dentin blocks were restored with 6 different restoration materials with or without adhesives (n = 10 per group) with a gap: 1) Clearfil AP-X composite, 2) Clearfil AP-X composite + SE Bond, 3) Clearfil AP-X composite + ProtectBond, 4) Filtek Silorane composite, 5) Filtek Silorane composite + Silorane System adhesive, or 6) Tytin amalgam. Specimens were subjected to an intermittent 1% sucrose biofilm model for 20 days to create artificial caries lesions. Lesion progression in the enamel-dentin next to the different materials was measured in lesion depth (LD) and mineral loss (ML) using transversal wavelength independent microradiography (T-WIM). A regression analysis was used to compare the LD and ML of the different restoration materials at 4 measurement locations: 1 location at the surface of the enamel, 1 location at the wall of the enamel, and 2 locations at the wall of the dentin. A statistically significant effect of AP-X composite with Protect Bond was found for LD and ML at the WallDentin1 location, leading to less advanced wall lesions. An additional finding was that gap size was also statistically significant at the 2 wall locations in dentin, leading to increasing lesion progression with wider gaps. In conclusion, adhesives can influence wall lesion development in gaps. Protect Bond showed significantly less caries progression compared to bare restoration materials or other adhesives in this short-term in vitro biofilm model.

Low protein concentration in cirrhotic ascites is related to low ascitic concentrations of immunoglobulins G and A.

OBJECTIVE: To analyse the differences in ascitic and serum levels of immunoglobulins and albumin between two groups of cirrhotic patients (with ascitic total protein levels higher and lower than 10 g/l). DESIGN: A prospective study. PATIENTS AND METHODS: We studied 39 cirrhotic patients with sterile ascites. The patients were classified into two groups: group A (18 patients) comprised those with an ascitic total protein level less than 10 g/l and group B (21 patients) those with an ascitic total protein level higher than 10 g/l. Ascitic and serum levels of albumin and immunoglobins G, A and M were analysed. RESULTS: Ascitic immunoglobulin G and A levels in group B were higher than ascitic immunoglobulin G and A levels in group A. Ascitic levels of these immunoglobulins correlated linearly with ascitic total protein levels. The serum levels of immunoglobulins G and A in groups A and B were not significantly different. Ascitic and serum immunoglobulin M concentrations in the two groups were similar. Transfer of immunoglobulins G and A and albumin from plasma to ascites seemed to be similar in group B. Transfer of immunoglobulins G and A seemed to be impaired in group A. Differences in ascitic immunoglobulin levels between groups A and B were also observed in the presence of diuretic treatment. Differences in ascitic immunoglobulin levels were related to the Child-Pugh score. CONCLUSION: Patients with a low ascitic total protein level show low ascitic immunoglobulin G and A concentrations. The low ascitic immunoglobulin G and A levels could be related to an impairment in the transfer of these immunoglobulins from plasma in those patients who have poor liver function. Ascitic immunoglobulin M is not related to ascitic total protein, and its origin is not clear. The putative transfer of immunoglobulin M to the peritoneal cavity is not related to the mechanism of transfer of albumin or of immunoglobulins G and A from serum. The physiological significance of ascitic immunoglobulin M is unclear.

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.

Patient risk factors' influence on survival of posterior composites.

This practice-based retrospective study evaluated the survival of resin composite restorations in posterior teeth, focusing on the influence of potential patient risk factors. In total, 306 posterior composite restorations placed in 44 adult patients were investigated after 10 to 18 yrs. The history of each restoration was extracted from the dental records, and a clinical evaluation was performed with those still in situ. The patient risk status was assessed for caries and "occlusal-stress" (bruxism-related). Statistical analysis was performed by the Kaplan-Meier method and Cox-regression multivariate analysis. In total, 30% of the restorations failed, of which 82% were found in patients with 1 or 2 risk factors. Secondary caries was the main reason of failure within caries-risk patients, whereas fracture was the main reason in "occlusal-stress-risk" patients. The patient variables gender and age did not significantly affect survival, but risk did (p < .001). Tooth type (p < .001), arch (p = .013), and pulpal vitality (p = .003) significantly affected restoration survival. Within the limits of this retrospective evaluation, the survival of restorations is affected by patient risk factors, which should be included in survival analyses of restorations.