Enamel Caries Lesion Depth Obtained by Optical Coherence Tomography and Transverse Microradiography: A Comparative Study.

INTRODUCTION: Visual imaging of subsurface caries lesions is of vital interest in dentistry, which can be obtained by invasive radiography technique as well as by available non-destructive imaging approaches. Thus, as a first step toward the development of a new innovative approach, Spectral-domain optical coherence tomography (SD-OCT) was applied to detect the lesion depth in comparison to the established reference technique (transverse microradiography [TMR]). METHODS: Bovine enamel specimens were demineralized for 5 days, following previous studies. For OCT, the resulting artificial lesions were scanned three-dimensionally (SD-OCT) and semi-automated measured (CarLQuant). For TMR, specimens were sectioned and the lesion depth was manually determined (Inspektor Research System). RESULTS: The range of lesion depth detected with OCT was 24.0-174.0 µm (mouth rinse study), 18.0-178.0 µm (toothpastes study) and with TMR 59.2-198.0 µm (mouth rinse study), 33.2-133.4 µm (toothpastes study). We found a strong correlation between both methods in terms of lesion depth (Spearman rankwith outlierp < 0.001, Rho = 0.75, Spearman rankwithout outlierp = 0.001, Rho = 0.79). The two methods produce similar results (Passing-Bablok regression, 1.16). As deeper is the lesion, the smallest is the difference between both methods as indicated by Bland-Altman-plots. CONCLUSION: Especially in the case of deep lesions, the values obtained by both methods are in agreement, and OCT can potentially substitute TMR to detect and assess lesion depth with the benefit of being non-destructive.

Comparison of calcium-based technologies to remineralise enamel subsurface lesions using microradiography and microhardness.

Assessment of enamel subsurface lesion remineralisation is essential for the evaluation of novel remineralisation technologies. The gold standard to assess subsurface mineral gain of enamel lesions is transverse microradiography (TMR). However, some studies have utilised surface microhardness (SMH) to evaluate efficacy of remineralisation agents. The aim of this study was to assess remineralisation of enamel subsurface lesions using TMR and SMH after in vitro treatment with calcium-containing technologies, and to test correlation between the TMR and SMH measurements. The parameters obtained from the TMR and SMH analyses of enamel subsurface remineralisation were not significantly correlated. Furthermore, the enamel subsurface remineralisation as measured by TMR was significantly correlated with the water-soluble calcium concentration of the remineralisation products. Scanning electron microscopy revealed surface precipitates formed by specific remineralisation treatments obfuscated accurate assessment of remineralisation by SMH. It was concluded that TMR is a more appropriate method for analysis of enamel subsurface remineralisation, and that SMH values of remineralised enamel should be interpreted with caution. Using TMR the level of remineralisation (%R) by the different technologies was CPP-ACP/F (31.3 ± 1.4%); CPP-ACP (24.2 ± 1.4%); CaSO4/K2HPO4/F (21.3 ± 1.4%); f-TCP/F (20.9 ± 1.0%); Nano-HA/F (16.3 ± 0.3%); Nano-HA (15.3 ± 0.6%) and F alone control (15.4 ± 1.3%).

Influence of salivary conditioning and sucrose concentration on biofilm-mediated enamel demineralization.

INTRODUCTION: The acquired pellicle formation is the first step in dental biofilm formation. It distinguishes dental biofilms from other biofilm types. OBJECTIVE: To explore the influence of salivary pellicle formation before biofilm formation on enamel demineralization. METHODOLOGY: Saliva collection was approved by Indiana University IRB. Three donors provided wax-stimulated saliva as the microcosm bacterial inoculum source. Acquired pellicle was formed on bovine enamel samples. Two groups (0.5% and 1% sucrose-supplemented growth media) with three subgroups (surface conditioning using filtered/pasteurized saliva; filtered saliva; and deionized water (DIW)) were included (n=9/subgroup). Biofilm was then allowed to grow for 48 h using Brain Heart Infusion media supplemented with 5 g/l yeast extract, 1 mM CaCl2.2H2O, 5% vitamin K and hemin (v/v), and sucrose. Enamel samples were analyzed for Vickers surface microhardness change (VHNchange), and transverse microradiography measuring lesion depth (L) and mineral loss (∆Z). Data were analyzed using two-way ANOVA. RESULTS: The two-way interaction of sucrose concentration × surface conditioning was not significant for VHNchange (p=0.872), ∆Z (p=0.662) or L (p=0.436). Surface conditioning affected VHNchange (p=0.0079), while sucrose concentration impacted ∆Z (p<0.0001) and L (p<0.0001). Surface conditioning with filtered/pasteurized saliva resulted in the lowest VHNchange values for both sucrose concentrations. The differences between filtered/pasteurized subgroups and the two other surface conditionings were significant (filtered saliva p=0.006; DIW p=0.0075). Growing the biofilm in 1% sucrose resulted in lesions with higher ∆Z and L values when compared with 0.5% sucrose. The differences in ∆Z and L between sucrose concentration subgroups was significant, regardless of surface conditioning (both p<0.0001). CONCLUSION: Within the study limitations, surface conditioning using human saliva does not influence biofilm-mediated enamel caries lesion formation as measured by transverse microradiography, while differences were observed using surface microhardness, indicating a complex interaction between pellicle proteins and biofilm-mediated demineralization of the enamel surface.

Influence of salivary conditioning and sucrose concentration on biofilm-mediated enamel demineralization

Abstract The acquired pellicle formation is the first step in dental biofilm formation. It distinguishes dental biofilms from other biofilm types. Objective To explore the influence of salivary pellicle formation before biofilm formation on enamel demineralization. Methodology Saliva collection was approved by Indiana University IRB. Three donors provided wax-stimulated saliva as the microcosm bacterial inoculum source. Acquired pellicle was formed on bovine enamel samples. Two groups (0.5% and 1% sucrose-supplemented growth media) with three subgroups (surface conditioning using filtered/pasteurized saliva; filtered saliva; and deionized water (DIW)) were included (n=9/subgroup). Biofilm was then allowed to grow for 48 h using Brain Heart Infusion media supplemented with 5 g/l yeast extract, 1 mM CaCl2.2H2O, 5% vitamin K and hemin (v/v), and sucrose. Enamel samples were analyzed for Vickers surface microhardness change (VHNchange), and transverse microradiography measuring lesion depth (L) and mineral loss (∆Z). Data were analyzed using two-way ANOVA. Results The two-way interaction of sucrose concentration × surface conditioning was not significant for VHNchange (p=0.872), ∆Z (p=0.662) or L (p=0.436). Surface conditioning affected VHNchange (p=0.0079), while sucrose concentration impacted ∆Z (p<0.0001) and L (p<0.0001). Surface conditioning with filtered/pasteurized saliva resulted in the lowest VHNchange values for both sucrose concentrations. The differences between filtered/pasteurized subgroups and the two other surface conditionings were significant (filtered saliva p=0.006; DIW p=0.0075). Growing the biofilm in 1% sucrose resulted in lesions with higher ∆Z and L values when compared with 0.5% sucrose. The differences in ∆Z and L between sucrose concentration subgroups was significant, regardless of surface conditioning (both p<0.0001). Conclusion Within the study limitations, surface conditioning using human saliva does not influence biofilm-mediated enamel caries lesion formation as measured by transverse microradiography, while differences were observed using surface microhardness, indicating a complex interaction between pellicle proteins and biofilm-mediated demineralization of the enamel surface.

Accuracy of the DIAGNOcam and bitewing radiographs in the diagnosis of cavitated proximal carious lesions in primary molars.

AIMS: To evaluate the diagnostic abilities of near-infrared light transillumination (using the DIAGNOcam) and bitewing radiographs in detecting cavitated proximal carious lesions in primary molars. SUBJECTS AND METHODS: The study was a cross-sectional analytical, clinical study. The proximal surfaces of primary molars of healthy 5- to 8-year-old children were radiographically screened for the presence of carious lesions in the enamel or outer third of dentin (D1). Two trained and calibrated examiners evaluated the depth of caries in bitewing radiographs and DIAGNOcam images and then verified the presence of cavitation by direct visual examination using the "International Caries Detection and Assessment System" after temporary tooth separation. RESULTS: A total of 236 proximal lesions were included in the study. Most of the clinically cavitated lesions (51.9%) were D1 radiographically and in outer dentin lesions (scores 3 and 4) by the DIAGNOcam (37% and 48.1%, respectively). Although DIAGNOcam showed higher sensitivity (0.852) compared to the radiographs (0.519), it showed slightly less specificity (0.569) compared to the radiographs (0.579). However, DIAGNOcam showed higher value of the area under the curve (AUC = 0.722; P < 0.001) compared to the radiographic method (AUC = 0.561; P = 0.308). CONCLUSIONS: The DIAGNOcam showed higher sensitivity and better accuracy than bitewing radiographs in diagnosing cavitated proximal lesions in primary molars and can be generally considered as an alternative to radiographs to detect cavitation without the hazards of ionizing radiation in children.

Role of Candida albicans on enamel demineralization and on acidogenic potential of Streptococcus mutans in vitro biofilms.

There is growing evidence that C. albicans is associated with dental caries, but its role on caries development needs to be better clarified. Label="OBJECTIVE">To evaluate at the hard tissue level the effect of C. albicans on the cariogenic potential of S. mutans biofilms focusing on the mineral profile of induced carious lesions. This study also aimed to evaluate the effect of C. albicans on the acidogenic potential of S. mutans biofilms. METHODOLOGY Dual-species (CA+SM) and single-species biofilms (CA or SM) were grown on the surface of enamel slabs in the presence of glucose/sucrose supplemented culture medium for 24, 48 and 72 hours. Demineralization was evaluated through percentage of surface microhardness change (%SMC) and transversal microradiography analysis (ILM and LD) and pH of the spent medium was recorded daily. Data were analyzed by two-way ANOVA followed by Bonferroni correction. RESULTS%SMC was statistically different among the biofilms at each time point being the highest for SM biofilms and the lowest for CA biofilms which also differed from CA+SM biofilms [SM (24 h: 47.0±7.3; 48 h: 66.3±8.3; 72 h: 75.4±3.9); CA (24 h: 7.3±3.3; 48 h: 7.1±6.4; 72 h: 6.6±3.6); CA+SM (24 h: 35.9±7.39.1; 48 h: 47.2±9.5; 72 h: 47.6±9.5)]. pH of spent medium was statistically lower for SM biofilms compared to the other biofilms at each time point and remained constant over time while pH values increased from 24 to 72 h for both CA and CA+SM biofilms [SM (24 h: 4.4±0.1; 48 h: 4.4±0.1; 72 h: 4.5±0.1); CA (24 h: 6.9±0.3; 48 h: 7.2±0.2; 72 h: 7.5±0.2); CA+MS (24 h: 4.7±0.2; 48 h: 5.1±0.1; 72 h: 6.1±0.6)]. IML and LD for SM biofilms increased over time while no difference was observed from 24 to 72 h for the other biofilms. CONCLUSIONS The present data suggest that C. albicans has low enamel demineralization potential and the presence of C. albicans can reduce both the cariogenic and acidogenic potentials of S. mutans biofilms.

Effects of soy and bovine milk beverages on enamel mineral content in a randomized, double-blind in situ clinical study.

Soy beverages are promoted as healthy alternatives to bovine milk even though they can contain added sugar. OBJECTIVES: To compare enamel mineral content after consumption of bovine milk or a soy beverage in a double-blind, randomized, cross-over in situ clinical study. MATERIALS AND METHODS: Human enamel slabs with subsurface lesions were prepared and inserted into intra-oral appliances worn by volunteers who consumed 200 ml of either bovine milk or a soy beverage over a 60 s period once a day for 15 days. Enamel lesion depth and mineral content were measured using transverse microradiography. Saliva samples were collected immediately after consuming the beverages and calcium, inorganic phosphate and fluoride levels analysed. Data were statistically analysed using a linear mixed model. RESULTS: Depth of the enamel subsurface lesions increased by 7.1 ±â€¯2.0 µm and mineral content decreased by 47 ±â€¯22 vol% min.µm after consumption of the soy beverage indicating demineralization. However, after consumption of bovine milk the depth of the lesions decreased by 7.6 ±â€¯3.5 µm and mineral content increased by 202 ±â€¯43 vol% min.µm indicating remineralization. The changes were significantly different (p < 0.001) between the two beverages. Fluoride levels were similar in the saliva samples for both beverages, however the calcium and inorganic phosphate levels for the bovine milk group were significantly higher (p < 0.02) than those for the soy beverage group. CONCLUSIONS: In this randomized, double-blind in situ clinical trial consumption of a soy beverage demineralized enamel whereas bovine milk produced remineralization. CLINICAL SIGNIFICANCE: Although soy beverages are promoted as healthy alternatives to bovine milk the added sugar and low calcium bioavailability of the soy drink makes frequent consumption a caries risk. (Trial registration no. ISRCTN19137849).

Effect of hydroalcoholic extract of Myracrodruon urundeuva All. and Qualea grandiflora Mart. leaves on the viability and activity of microcosm biofilm and on enamel demineralization.

OBJECTIVES: The aim of this study was to assess the effect of Myracrodruon urundeuva All. and Qualea grandiflora Mart. leaves hydroalcoholic extracts on viability and metabolism of a microcosm biofilm and on enamel demineralization prevention. METHODOLOGY: Microcosm biofilm was produced on bovine enamel using inoculum from pooled human saliva mixed with McBain saliva, under 0.2% sucrose exposure, for 14 days. The biofilm was daily-treated with the extracts for 1 min. At the end, it was analyzed with respect to viability by fluorescence, CFU counting and extracellular polysaccharides (phenol-sulphuric acid colorimetric assay) and lactic acid (enzymatic assay) production. The demineralization was measured by TMR. The data were compared using ANOVA or Kruskal-Wallis (p<0.05). RESULTS: M. urundeuva All. at 100, 10 and 0.1 µg/mL and Q. grandiflora Mart. at 100 and 0.1 µg/mL reduced biofilm viability similarly to positive control (chlorhexidine) and significantly more than the negative-vehicle control (35% ethanol). M. urundeuva at 1000, 100 and 0.1 µg/mL were able to reduce both lactobacilli and mutans streptococci CFU counting, while Q. grandiflora (1000 and 1.0 µg/mL) significantly reduced mutans streptococci CFU counting. On the other hand, the natural extracts were unable to significantly reduce extracellular polysaccharides and lactic acid productions neither the development of enamel carious lesions. CONCLUSIONS: The extracts showed antimicrobial properties on microcosm biofilm, however, they had no effect on biofilm metabolism and caries protection.

Quantitative X-Ray Imaging of Mouse Bone by Faxitron.

This chapter describes the use of point projection digital microradiography for rapid imaging and quantitation of bone mineral content in mice.

Scanning Electron Microscopy of Bone.

This chapter describes methods for preparing samples of bone and bone cells for scanning electron microscopy (SEM). Backscattered electron (BSE) imaging is by far the most useful in the bone field, followed by secondary electrons (SE) and the energy dispersive X-ray (EDX) analytical modes. Samples may have 3D detail in a 3D surface, or be topography-free, polished or micromilled, resin-embedded block surfaces, or resin casts of space compartments surrounded by bone matrix. Methods for cells include fixation, drying, looking at undersides of bone cells, and metallic conductive coating. Maceration with alkaline bacterial pronase, hypochlorite, hydrogen peroxide, and sodium or potassium hydroxide to remove cells and unmineralized matrix is described in detail. Attention is given especially to methods for 3D BSE SEM imaging of bone samples. Recommendations are made for the types of resin embedding for BSE SEM imaging. Correlated confocal and SEM imaging of PMMA embedded bone requires the use of glycerol to coverslip. Cathodoluminescence (CL) mode SEM imaging is an alternative for visualizing fluorescent mineralizing front labels such as calcein and tetracyclines. Making spatial casts from PMMA or other resin-embedded samples is an important use of this material. Correlation with other imaging means, including microradiography and microtomography is important. Shipping wet bone samples between labs is best done in glycerol. Control of the vacuum pressure in the SEM sample chamber (now generally available) can be used to eliminate "charging" problems which were common, for example, with large, complex, cancellous bone samples.

Effect of hydroalcoholic extract of Myracrodruon urundeuva All. and Qualea grandiflora Mart. leaves on the viability and activity of microcosm biofilm and on enamel demineralization

Abstract Objectives: The aim of this study was to assess the effect of Myracrodruon urundeuva All. and Qualea grandiflora Mart. leaves hydroalcoholic extracts on viability and metabolism of a microcosm biofilm and on enamel demineralization prevention. Methodology: Microcosm biofilm was produced on bovine enamel using inoculum from pooled human saliva mixed with McBain saliva, under 0.2% sucrose exposure, for 14 days. The biofilm was daily-treated with the extracts for 1 min. At the end, it was analyzed with respect to viability by fluorescence, CFU counting and extracellular polysaccharides (phenol-sulphuric acid colorimetric assay) and lactic acid (enzymatic assay) production. The demineralization was measured by TMR. The data were compared using ANOVA or Kruskal-Wallis (p<0.05). Results: M. urundeuva All. at 100, 10 and 0.1 μg/mL and Q. grandiflora Mart. at 100 and 0.1 μg/mL reduced biofilm viability similarly to positive control (chlorhexidine) and significantly more than the negative-vehicle control (35% ethanol). M. urundeuva at 1000, 100 and 0.1 μg/mL were able to reduce both lactobacilli and mutans streptococci CFU counting, while Q. grandiflora (1000 and 1.0 μg/mL) significantly reduced mutans streptococci CFU counting. On the other hand, the natural extracts were unable to significantly reduce extracellular polysaccharides and lactic acid productions neither the development of enamel carious lesions. Conclusions: The extracts showed antimicrobial properties on microcosm biofilm, however, they had no effect on biofilm metabolism and caries protection.

Role of Candida albicans on enamel demineralization and on acidogenic potential of Streptococcus mutans in vitro biofilms

Abstract There is growing evidence that C. albicans is associated with dental caries, but its role on caries development needs to be better clarified. Objective: To evaluate at the hard tissue level the effect of C. albicans on the cariogenic potential of S. mutans biofilms focusing on the mineral profile of induced carious lesions. This study also aimed to evaluate the effect of C. albicans on the acidogenic potential of S. mutans biofilms. Methodology: Dual-species (CA+SM) and single-species biofilms (CA or SM) were grown on the surface of enamel slabs in the presence of glucose/sucrose supplemented culture medium for 24, 48 and 72 hours. Demineralization was evaluated through percentage of surface microhardness change (%SMC) and transversal microradiography analysis (ILM and LD) and pH of the spent medium was recorded daily. Data were analyzed by two-way ANOVA followed by Bonferroni correction. Results: %SMC was statistically different among the biofilms at each time point being the highest for SM biofilms and the lowest for CA biofilms which also differed from CA+SM biofilms [SM (24 h: 47.0±7.3; 48 h: 66.3±8.3; 72 h: 75.4±3.9); CA (24 h: 7.3±3.3; 48 h: 7.1±6.4; 72 h: 6.6±3.6); CA+SM (24 h: 35.9±7.39.1; 48 h: 47.2±9.5; 72 h: 47.6±9.5)]. pH of spent medium was statistically lower for SM biofilms compared to the other biofilms at each time point and remained constant over time while pH values increased from 24 to 72 h for both CA and CA+SM biofilms [SM (24 h: 4.4±0.1; 48 h: 4.4±0.1; 72 h: 4.5±0.1); CA (24 h: 6.9±0.3; 48 h: 7.2±0.2; 72 h: 7.5±0.2); CA+MS (24 h: 4.7±0.2; 48 h: 5.1±0.1; 72 h: 6.1±0.6)]. IML and LD for SM biofilms increased over time while no difference was observed from 24 to 72 h for the other biofilms. Conclusions: The present data suggest that C. albicans has low enamel demineralization potential and the presence of C. albicans can reduce both the cariogenic and acidogenic potentials of S. mutans biofilms.

Assessment of root caries under wet and dry conditions using swept-source optical coherence tomography (SS-OCT).

The purpose of this study was to compare optical properties of root caries under two observing conditions using swept-source optical coherence tomography (SS-OCT). In vitro and natural root caries were observed by SS-OCT under wet and dry conditions, followed by confocal laser scanning microscope (CLSM) and transverse microradiography (TMR). Signal intensity (SI), distance between SI peaks (SI-distance) and optical lesion depth were obtained from OCT. Lesion depth was measured from CLSM; lesion depth (LDTMR) and mineral loss (ML) were obtained from TMR. In vitro root caries under wet and dry conditions showed different OCT images and SI patterns. Lesion depth of OCT and that of CLSM, SI-distance and LDTMR, LDTMR and ML significantly correlated. Under dry conditions, half natural root caries showed similar OCT images and SI patterns as in vitro root caries. The base of demineralized dentin could be detected more clearly under dry conditions than under wet conditions.

Effect of phytate and zinc ions on fluoride toothpaste efficacy using an in situ caries model.

OBJECTIVES: To compare and explore the dose-response of phytate-containing 1150 ppm fluoride toothpastes on model caries lesions and to determine the impact of zinc ions. METHODS: This was a single-centre, randomised, blinded (examiner/laboratory analyst), six-treatment, four-period crossover, in situ study in adults with a removable bilateral maxillary partial denture. Study treatments were toothpastes containing: 0.425% phytate/F; 0.85% phytate/F; 0.85% phytate/Zn/F; F-only; Zn/F and a 0% F placebo. Where present, F was 1150 ppm as NaF; Zn was 0.3% as ZnCl2. Human enamel specimens containing early-stage, surface-softened (A-lesions) or more advanced, subsurface (B-lesions) caries lesions were placed into the buccal flanges of participants' modified partial denture (one of each lesion type per side). A-lesions were removed after 14 days of twice-daily treatment use; B-lesions were removed after a further 14 days. A-lesions were analysed for surface microhardness recovery. Both lesion types were analysed by transverse microradiography and for enamel fluoride uptake, with B-lesions additionally analysed by quantitative light-induced fluorescence. Comparison was carried out using an analysis of covariance model. RESULTS: Statistically significant differences between 1150 ppm F and the placebo toothpastes (p < 0.05) were shown for all measures, validating the model. No differences between fluoride toothpastes were observed for any measure with little evidence of a dose-response for phytate. Study treatments were generally well-tolerated. CONCLUSIONS: Results suggest phytate has little impact on fluoride's ability to promote early-stage lesion remineralisation or prevent more advanced lesion demineralisation in this in situ caries model. Similarly, results suggest zinc ions do not impair fluoride efficacy. CLINICAL SIGNIFICANCE: Toothpastes may contain therapeutic or cosmetic agents that could interfere with fluoride's caries prevention efficacy. The present in situ caries study has demonstrated that phytate, added to provide enhanced extrinsic stain removal/prevention, and zinc, added to inhibit malodour, do not impair fluoride efficacy.

In vitro performance of the DIAGNOcam for detecting proximal carious lesions adjacent to composite restorations.

OBJECTIVES: To assess the accuracy of near-infrared-light transillumination (DIAGNO) compared to visual-tactile (VT) and radiographic (RA) evaluation of proximal carious lesions adjacent to composite restorations in vitro. METHODS: Two hundred extracted posterior permanent human teeth with occluso-proximal composite restorations were allocated to 50 groups of four posterior teeth, and mounted in a pilot-tested diagnostic model in a dummy head. The teeth were independently assessed by two examiners. Transverse microradiography and visual assessment served as reference tests to detect any lesions (prevalence 24%) and cavitated lesions (18%), respectively, adjacent to restorations. Sensitivity, specificity, positive and negative predictive values and the area under the receiver-operating-characteristics curve (AUC) were calculated. RESULTS: To detect any proximal carious lesions adjacent to composite, the mean sensitivity/specificity were 0.63/0.95 for DIAGNO, 0.70/0.88 for RA when lesions radiographically extending into enamel and dentin were considered, 0.26/0.98 for RA when only lesions extending into dentin were considered, and 0.31/0.96 for VT. For cavitated lesions adjacent to proximal composite restorations, these values were RA (enamel and dentin) 0.84/0.88, RA (dentin) 0.34/0.99, DIAGNO 0.69/0.94 and VT 0.40/0.97. AUC did not differ significantly between RA and DIAGNO, while VT showed significantly lower values (p < 0.05). CONCLUSION: Within the limitations of this study, DIAGNO seems useful for detecting proximal carious lesions adjacent to restorations. CLINICAL RELEVANCE: Near-infrared-light transillumination could be used as a radiation-free adjunct or alternative to RA for detecting carious lesions adjacent to composite restorations.

Natural enamel caries in quinoline: Volumetric data and the pattern of infiltration.

This study aimed to test the hypotheses that (i) a parameter related to permeability, αd (ratio of squared water volume by the nonmineral volume) is, among all major component volumes (mineral, water, and organic volumes) the best predictor of quinoline infiltration in natural enamel caries (NEC), and (ii) the pore volume fraction infiltrated by quinoline (Vqui ) in NEC is much lower than previous estimates that neglected water and organic enamel volumes. Mineral and nonmineral volumes and αd were measured at 341 histological points (from 20 approximal NEC lesions), and transport of quinoline was tracked by orientation-independent polarizing microscopy. R2 values of Vqui were 0.596 (αd ), 0.033 (mineral volume), 0.474 (water volume), and 0.011 (organic volume). Vqui values were 23% (body of the lesion), 7% (dark zone), and 9% (translucent zone), lower than previous estimates (with high effect size). Transport of quinoline occurred both parallelly and perpendicularly to prism paths, and dark zones were seen where only transport parallel to prisms occurred. In conclusion, αd was the main predictor of quinoline infiltration, but it differed from the water volume with a small effect size, and the pore volume fraction with quinoline was much lower than previous estimates.

Correlation between ICDAS and histology: Differences between stereomicroscopy and microradiography with contrast solution as histological techniques.

Detection of occlusal caries with visual examination using ICDAS correlates strongly with histology under stereomicroscopy (SM), but dentin aspects under SM are ambiguous regarding mineral content. Thus, our aim was to test two null hypotheses: SM and microradiography result in similar correlations between ICDAS and histology; SM and microradiography result in similar positive (PPV) and negative predictive values (NPV) of ICDAS cut-off 1-2 (scores 0-2 as sound) with histological threshold D3 (demineralization in the inner third of dentin). Occlusal surfaces of extracted permanent teeth (n = 115) were scored using ICDAS. Undemineralized ground sections were histologically scored using both SM without contrast solution and microradiography after immersion in Thoulet's solution 1.47 for 24 h (MRC). Correlation between ICDAS and histology differed from SM (0.782) to MRC (0.511) (p = 0.0002), with a large effect size "q" of 0.49 (95% CI: 0.638/0.338). For ICDAS cut-off 1-2 and D3, PPV from MRC (0.56) was higher than that from SM (0.28) (p< 0.00001; effect size h = 0.81), and NPV from MRC (0.72) was lower than that from SM (1,00) (p < 0.00001; effect size h = 1.58). In conclusion, SM overestimated the correlation between ICDAS and lesion depth, and underestimated the number of occlusal surfaces with ICDAS cut-off 1-2 and deep dentin demineralization.

The association between loading of restorations and secondary caries lesions is moderated by the restoration material elasticity.

OBJECTIVES: Secondary caries limits the longevity of restorations and is thought to be associated with faulty restorations, e.g. dentin-restoration interfacial gaps. Recent evidence indicates that loading of restorations might aggravate the effects of gaps on interfacial mineral loss. It is unclear if this effect of loading is dose-dependent or not, and if restoration material properties like elasticity moderate the association between load and mineral loss. We hypothesized that mineral loss of secondary lesions increases with increasing load, and that this association is moderated by the elastic modulus of the placed restoration material. METHODS: Dentin-restoration specimens with simulated interfacial gaps were submitted to cariogenic Lactobacillus-rhamnosus-biofilms for 10days, and concurrently loaded with different loads (0/42/84/126g per specimen, n=12/group). Two different composites (LEC: low elastic-modulus composite, HEC: high elastic-modulus composite) were employed. Transversal microradiography was used to evaluate the superficial and interfacial (wall) lesion mineral loss. Generalized linear modeling (GLM) was used to evaluate the association between loading, material and their interaction on mineral loss. RESULTS: Surface mineral loss was not significantly associated with loading, material, or their interaction (p-values ranged between p=0.062 and 0.526). For deep interfacial (wall) lesions, the applied load (p=0.023) but not the material (p=0.382) showed a significant effect. The interaction between both significantly affected mineral loss (p=0.01). Loads of ≥84g per specimens were associated with higher wall lesion mineral loss. CONCLUSIONS: Loads above a certain threshold significantly increased interfacial (wall) lesion mineral loss. This association was moderated by the elasticity of the placed restoration materials. CLINICAL SIGNIFICANCE: The clinical relevance of our findings remains unclear, as future studies are needed to understand how exactly both load and material elasticity affect secondary lesion induction.

Reliability of Cone Beam Computed Tomography in Determining Mineralized Tissue in Augmented Sinuses.

PURPOSE: The aim of this study was to analyze cone beam computed tomography (CBCT) densitometries of maxillary sinuses augmented with human bone allograft. In addition, previously obtained microradiographic specimens were used to verify the diagnostic potential of CBCT. MATERIALS AND METHODS: A two-stage protocol was conducted in 21 consecutive patients, all with a crestal bone height < 2 mm. Mineralized human bone allograft particles were used to augment sinuses using a lateral window approach. A succession of CBCT scans of the maxilla were taken before surgery, immediately after sinus augmentation, and 6, 10, and 18 months after implant placement. Using virtual probes, CBCT images taken at 6, 8, and 10 mm from the crestal surface were processed with medical imaging software and expressed as gray level (GL). RESULTS: A total of 24 sinus augmentation procedures were performed in 21 patients. The average values of CBCT-GL ranged from 571 to 654, presenting the maximum value at 8 mm immediately after implant placement and the minimum value at 6 mm after 10 months. Furthermore, it was found that the graft mineral content decreased over time, completely disappearing between 10 and 11 months. CONCLUSION: CBCT and the medical imaging software employed for imaging visualization are reliable tools to study biomaterial behavior after sinus augmentation procedures. In addition, results from this study demonstrate that a complete resorption of human bone allograft is possible. Due to the limited sample size, further clinical and morphometric studies are needed.

X-Ray Micro- and Nanodiffraction Imaging on Human Mesenchymal Stem Cells and Differentiated Cells.

Adult human mesenchymal stem cells show structural rearrangements of their cytoskeletal network during mechanically induced differentiation toward various cell types. In particular, the alignment of acto-myosin fibers is cell fate-dependent and can serve as an early morphological marker of differentiation. Quantification of such nanostructures on a mesoscopic scale requires high-resolution imaging techniques. Here, we use small- angle x-ray scattering with a spot size in the micro- and submicrometer range as a high-resolution and label-free imaging technique to reveal structural details of stem cells and differentiated cell types. We include principal component analysis into an automated empirical analysis scheme that allows the local characterization of oriented structures. Results on freeze-dried samples lead to quantitative structural information for all cell lines tested: differentiated cells reveal pronounced structural orientation and a relatively intense overall diffraction signal, whereas naive human mesenchymal stem cells lack these features. Our data support the hypothesis of stem cells establishing ordered structures along their differentiation process.