Zoledronate treatment exerts sex-independent effects on bone and dental physicochemical properties in mice jaw necrosis.

INTRODUCTION: Bisphosphonate (BF) therapy is strongly related to the occurrence of medication-related osteonecrosis of the jaw (ONJ). However, no previous study has evaluated if there are sex-related differences on the ONJ establishment together with bone biomechanical alterations, and if they could have a synergy with the ZA treatment. MATERIALS AND METHODS: This study aimed to analyze the physicochemical properties of mineralized tissues in a zoledronate (ZA)-related osteonecrosis mouse model, by a 2 × 2-factorial design, considering sex (female/male) and treatment (ZA/Saline) factors (n = 8/group). After three ZA (1.0 mg/kg) or saline administrations (days 0, 7, 14), the lower left second molar was extracted (day 42). Further ZA administration (day 49) and euthanasia (day 70) were conducted. After confirmation of ZA-induced jaw necrosis (histologic and microtomographic analysis), spectroscopic and mechanical parameters were assessed. RESULTS: ZA-treated groups presented lower bone density due to impaired healing of tooth extraction socket. Sex-related alterations were also observed, with lower bone density in females. Regarding biomechanical parameters, sex and treatment exerted independent influences. ZA, although decreasing flexural modulus and yield stress, increases stiffness mainly due to a higher bone volume. Females show less resistance to higher loads compared to males (considering dimension-independent parameters). Additionally, ZA increases crystallinity in bone and dental structure (p < 0.05). In summary, although strongly related to osteonecrosis occurrence, ZA modifies bone and dental mineral matrix, improving bone mechanical properties. CONCLUSION: Despite sex-dependent differences in bone biomechanics and density, osteonecrosis was established with no sex influence. No synergistic association between sex and treatment factors was observed in this study.

Influence of carbonated acid beverage on fracture resistance and marginal gap formation in different restorative approaches to non-carious cervical lesions.

OBJECTIVE: This study is to evaluate fracture resistance, failure mode, and gap formation at the restorative interface of unrestored or restored non-carious cervical lesions (NCCLs) submitted to a short-term erosive environment. MATERIALS AND METHODS: Artificial NCCLs were produced in vitro in bovine incisors, and were randomly divided into four restorative resins groups (n = 22): nanohybrid-NR; bulk-fill-BR; flow with a nanohybrid layer-FNR; bulk-fill with a nanohybrid layer-BNR; and a group unrestored-UR (n = 16). Half of the specimens were submitted to an erosive challenge (per 5 min, 3 × a day for 7 days, before and after restoration), and the other half, was immersed in artificial saliva. After, all teeth undergone thermal (5 ºC, 37 ºC, and 55 ºC, 3600 cycles) and mechanical (50 N, 2 Hz, 300,000 cycles) aging. Eighty teeth were subjected to compressive loading, and resistance and failures were analyzed, while 24 teeth were evaluated for gaps by microcomputed tomography. Statistical tests were performed (p < 0.05). RESULTS: The restorative approaches affected fracture resistance (η2p = 0.14, p = 0.023), and gap formation (η2 = 0.18, p = 0.012) and so did the immersion medium (fracture η2p = 0.09, p = 0.008; gap η2 = 0.09, p = 0.017). BNR showed the highest resistance, while UR the lowest. FNR showed the highest gaps in both immersion media. Neither the resin groups nor the immersion media were associated with failure mode. CONCLUSIONS: The erosive immersion medium based in acid beverages has been shown to affect NCCLs with or without restoration, but when Bulk-Fill resin is covered by nanohybrid resin, the performance is good. CLINICAL RELEVANCE: Erosion negatively affects restorations, but unrestored NCCL shows worse biomechanical performance in stress-bearing situations.

Organic volume and permeability variations in the surface layer of artificial and natural enamel carious lesions.

OBJECTIVES: Test the hypothesis the type of enamel caries (natural, artificial induced by gel, and artificial induced by acid solutions) affect the organic volume and the permeability of the surface layer in enamel caries lesions. DESIGN: Artificial enamel caries, induced by either acidic solution (organic-poor; Group 1) or acidic gel (organic-rich; Group 2), and natural non-cavitated inactive approximal enamel caries lesions (NEC; Group 3) were obtained, from which longitudinal ground sections were prepared. Measurements of the mineral (Vmin) (by microradiography), and water (α) and organic (ß) volumes (by optical birefringence) were obtained at three points in the surface layer (n = 30/group). RESULTS: The main outcomes were the ratio between experimental ß by predicted ß (ß Ratio) and the ratio between experimental and predicted permeabilities (αd Ratio). ß Ratio in Group 1 was lower than in Groups 2 (Cohen's d: -1.81; 95% CI:-1.45,-2.32; p < 0.001) and 3 (Cohen's d: -0.71; 95% CI:-0.27,-1.18; p = 0.004), and Group 2 surpassed Group 3 (Cohen's d: 0.49; 95% CI:0.07,0.94; p = 0.03). αd Ratio in Group 1 was higher than in Groups 2 (Cohen's d: 1.86; 95% CI:1.49,2.33; p < 0.001) and 3 (Cohen's d: 0.60; 95% CI:0.18,1.14; p = 0.01), and Group 3 surpassed Group 2 (Cohen's d: 0.61; 95% CI:0.23,1.07; p = 0.01). CONCLUSIONS: The highest organic volume and the lowest permeability occurred at the surface layer of gel-induced artificial enamel caries lesions, which should be preferred in in vitro studies on de- and remineralization and resin infiltration.

Improved mineralization of dental enamel by electrokinetic delivery of F- and Ca2+ ions.

This in vitro study evaluated the effects of the infiltration of F- and Ca2+ ions into human enamel by electrokinetic flow (EKF) on the enamel microhardness and F- content. Sound human enamel ground sections of unerupted third molars were infiltrated with de-ionized water by EKF and with F- ion by EKF respectively. All samples were submitted to two successive transverse acid-etch biopsies (etching times of 30 s and 20 min) to quantify F- ion infiltrated deep into enamel. Remarkably, sound enamel showed a large increase in microhardness (MH) after infiltration of NaF (p < 0.00001) and CaCl2 (p = 0.013) by EKF. Additionally, NaF-EKF increased the remineralization in the lesion body of artificial enamel caries lesions compared to controls (p < 0.01). With the enamel biopsy technique, at both etching times, more F- ions were found in the EKF-treated group than the control group (p << 0.05), and more fluoride was extracted from deeper biopsies in the NaF-EKF group. In conclusion, our results show that EKF treatment is superior in transporting Ca2+ and F- ions into sound enamel when compared to molecular diffusion, enhancing both the mineralization of sound enamel and the remineralization of artificial enamel caries.

New Theory Illustrates the Formation of Enamel CUP-Shaped Lesions on Occlusal Surfaces.

We propose a new theory for enamel cupping lesions formation. At early stages, naturally formed cupping lesions showed increased porosity at two structural prismatic traits: the central cone extending into the enamel-dentine junction and the type-I Hunther-Schreger bands (HSB), suggesting them to be the main drivers for cupping lesion formation and development. In addition, these lesions were circumscribed by type-II HSBs, which present lower surface porosity and higher resistance to wear. This theory was verified in in vitro observations, where both the central cone and the type-I HSB of cuspal enamel showed higher susceptibility to wear, potentially elucidating the mechanisms involved on cupping lesion formation.

Structure and Chemical Composition of ca. 10-Million-Year-Old (Late Miocene of Western Amazon) and Present-Day Teeth of Related Species.

Molecular information has been gathered from fossilized dental enamel, the best-preserved tissue of vertebrates. However, the association of morphological features with the possible mineral and organic information of this tissue is still poorly understood in the context of the emerging area of paleoproteomics. This study aims to compare the morphological features and chemical composition of dental enamel of extinct and extant terrestrial vertebrates of Crocodylia: Purussaurus sp. (extinct) and Melanosuchus niger (extant), and Rodentia: Neoepiblema sp. (extinct) and Hydrochoerus hydrochaeris (extant). To obtain structural and chemical data, superficial and internal enamel were analyzed by Scanning Electron Microscopy (SEM) and Energy Dispersive Spectroscopy (SEM-EDS). Organic, mineral, and water content were obtained using polarizing microscopy and microradiography on ground sections of four teeth, resulting in a higher organic volume than previously expected (up to 49%). It is observed that both modern and fossil tooth enamel exhibit the same major constituents: 36.7% Ca, 17.2% P, and 41% O, characteristic of hydroxyapatite. Additionally, 27 other elements were measured from superficial enamel by inductively coupled mass spectrometry (ICP-MS). Zinc was the most abundant microelement detected, followed by Pb, Fe, Mg, and Al. Morphological features observed include enamel rods in the rodent teeth, while incremental lines and semiprismatic enamel were observed in the alligator species. The fossil enamel was in an excellent state for microscopic analyses. Results show that all major dental enamel's physical, chemical, and morphological features are present both in extant and extinct fossil tooth enamel (>8.5 Ma) in both taxa.

Shaping efficiency of XP-endo shaper and Mtwo instruments in long oval root canals: A micro-CT study.

This study evaluated the shaping ability of XP-endo Shaper and Mtwo systems in long-oval-shaped canals of extracted human mandibular molars using micro-computed tomography (micro-CT). Images recorded before and after preparation were evaluated for morphometric measures regarding increase in canal volume, dentin removed, surface area, untouched walls and structure model index (SMI). Data were statistically analysed using the Mann-Whitney test with 5% of significance. On both groups, the root canal preparation significantly increased all analysed parameters (P > 0.05). There was no statistical difference between XP-endo Shaper and Mtwo systems in the increase of the canal volume (30.50%-27.82%), in volume of dentin removed (2.77%-2.40%), in the increase of the canal surface area (11.30%-8.86%), in canal untouched surfaces (9.57%-8.51%) and in the SMI (2.59%-2.68%), respectively. XP-endo Shaper and Mtwo systems showed similar shaping efficiency and were not able to completely prepare the walls of long-oval-shaped canals of extracted human mandibular molars.

The effect of high concentration of zoledronic acid on tooth induced movement and its repercussion on root, periodontal ligament and alveolar bone tissues in rats.

Zoledronic acid (ZA) is often prescribed for osteoporosis or resorptive metabolic bone disease. This study aims to evaluate the effect of ZA on orthodontic tooth movement (OTM) and root and bone resorption and its repercussion on root, periodontal ligament and alveolar bone tissues. The experimental group consisted of 72 Wistar rats divided in four subgroups: Naive, Saline and Zoledronic Acid groups at the concentration of 0.2 mg/kg [ZA (0.2)] or 1.0 mg/kg [ZA (1.0)]. The animals were subjected to i.v (dorsal penile vein) administrations of ZA or saline solution, on days 0, 7, 14 and 42. Under anesthesia, NiTi springs were installed in the first left maxillary molar with 50gf allowing the OTM, except for the negative control group (N) for mesial movement of the left first maxillary teeth. The animals were sacrificed and maxillae were removed for macroscopic and histopathological analyzes, scanning electron microscopy, computerized microtomography and confocal microscopy. Treatment with ZA decreased the OTM and the number of osteoclasts and loss of alveolar bone when compared to the naive and saline groups. Reduction of radicular resorption, increased necrotic areas and reduced vascularization in the periodontal ligament were observed in the ZA groups. ZA interferes with OTM and presents anti-resorptive effects on bone and dental tissues associated with a decreased vascularization, without osteonecrosis.

Comparative Analysis of Continuous versus Reciprocating Instruments in Retreatment of Flat-oval Root Canals.

Introduction: Flat-oval root canals of incisors can be problematic in retreatments. This study assessed the efficacy of continuous and reciprocating rotation instruments in retreatment of flat-oval root canals in lower incisors via micro-computed tomography (micro-CT). File systems studied were ProTaper universal retreatment rotary system associated with ProTaper Next (PTUR+PTN), D-RaCe associated with iRaCe (DR+iR), Reciproc (REC), and WaveOne (WO). Materials and Methods: Thirty-two mandibular incisors with flat root canal were divided into 4 groups (n=8). The groups were initially prepared with PTN, iRaCe, REC, and WO, then instrumented, filled, and subjected to micro-CT analyses. All the canals were then retreated with the PTUR+PTN, DR+iR, REC, and WO, and then subjected to new micro-CT analysis which allowed quantification of residual filling material volume and change in the diameter of the root canal apical third. Endodontic retreatment time was also quantified. Data were analyzed with One-Way ANOVA and post hoc t tests. Results: None of the systems completely removed the filling material. The groups differed in terms of remnant filling material volume (PTUR+PTN=2.9±1.1 mm3; DR+iR=3.6±3.1 mm3; REC=4.9±1.9 mm3; WO=3.1±1.9 mm3) and retreatment time (PTUR+PTN=1:36±0:12 sec; DR+iR=0:57±0:13 sec; REC=2:10±0:44 sec; WO=2:03±0:31 sec), but had similar values in terms of change in apical root canal diameter (P>0.05). Conclusions: Based on this in vitro study, the type of endodontic instrument did not affect the diameter of the root canal apical third. However, PTUR with ProTaper Next had the lowest residual filling material volume and second lowest retreatment time, in flat-oval root canals in mandibular incisors.

Microtomographic analysis of the effect of sodium alendronate on orthodontic movement in rats.

OBJECTIVE: To evaluate the effect of sodium alendronate on orthodontic tooth movement in rats using microtomographic analysis. SETTINGS AND SAMPLE POPULATION: Thirty male Wistar rats (Rattus norvegicus) were divided into three groups of 10 rats and administered saline (control), 1 mg/kg sodium alendronate or 6 mg/kg sodium alendronate, respectively. MATERIALS AND METHODS: The drug was administered once per week for 5 weeks by gavage. Orthodontic movement was induced during the last 2 weeks of medication administration by inserting a closed nickel-titanium spring between the left upper first molar and central incisors. The opposite side served as the control. Tooth movement and bone trabeculation in the furcation region were evaluated by microtomographic analysis in the first (moved) and third (static) molars. The data were subjected to one-way or two-way ANOVA and Bonferroni test (P < .05). RESULTS: The microtomographic images of the group that received 6 mg/kg sodium alendronate demonstrated significantly less tooth movement (P = .048), less space between the trabeculae (P = .031) and greater number of bone trabeculae (P = .033) compared to the other groups. There were no statistically significant differences in bone volume and mean trabecular thickness between the three groups. The static teeth did not show the same alterations (P > .05). CONCLUSION: Sodium alendronate treatment reduced tooth movement in rats.

Susceptibility of Dental Enamel of Different Ages to Caries-Like Lesion Development.

This study investigated the impact of estimated age, anatomical location, and the presence of wear facets on the susceptibility of enamel to develop caries-like lesions. Extracted human premolars (n = 261) had their age estimated between 10 and 93 years old, using established forensic methods. Specimens of enamel (4 × 4 mm) were prepared from the middle of the buccal surfaces, preserving the outer surface layer. The central area of the block (4 × 1 mm) was protected with nail polish and used as an internal control. The specimens were demineralized for 8 days (with 0.1 M acetic acid, 1.28 mM Ca, 0.74 mM Pi, and 0.03 µg F/mL, pH 5.0), to simulate caries-like lesion development. They were then scanned individually using microtomography, and digital 2D images were used to calculate the outcomes of integrated mineral concentration loss (ΔZ in µm/g/cm3) and lesion depth (LD in µm) at 3 locations, i.e., the cervical, middle, and occlusal thirds. The presence of natural surface wear facets was considered in the analysis. Data were evaluated using a linear mixed-effects models (α = 0.05). ΔZ increased significantly as a function of estimated tooth age at all 3 locations, and this increase was greater after the age of 30 years (p < 0.001), when a higher ΔZ was found in the occlusal third than in the middle and cervical thirds (p < 0.001). LD increased only in the occlusal third before the age of 30 years (p = 0.039) and this increase was significantly greater after 30 years at all 3 locations (p < 0.01), with no differences among them (p > 0.15). The presence of wear facets significantly increased ΔZ and LD (p < 0.001 for both). Overall, we concluded that the susceptibility of enamel to developing caries-like lesions increased with estimated dental age. This effect was more pronounced after the estimated age of 30 years and in the presence of natural tooth wear facets.

Variation in mineral, organic, and water volumes at the neonatal line and in pre- and postnatal enamel.

OBJETIVES: The neonatal line (NNL) in enamel is hypomineralized, but quantitative data on the enamel component volumes of the NNL are lacking. This study aimed at quantifying the variation in the mineral, organic, and water volumes at the NNL and in pre- and postnatal enamel. MATERIALS AND METHODS: In buccal enamel longitudinal ground sections of exfoliated primary incisors (upper and lower; n = 17), the enamel component volumes were quantified at five histological sites (located at 40 µm intervals along a transversal line): the NNL, two sites in prenatal enamel, and two sites in postnatal enamel. Mineral volume was quantified using microradiography, and non-mineral volumes were quantified using polarizing microscopy. RESULTS: Differences in component volumes between the NNL and pre- and postnatal enamel had high effect sizes (Hedge's G ranging from 0.89, for the water volume, to 1.88, for the mineral volume; power > 90 %). The distance from the NNL correlated with the normalized component volume: r = 0.459, 95 % CI = 0.274/0.612 (mineral); r = -0.504; 95 % CI= -0.328/-0.647 (organic), and r = -0.294; 95 % CI= -0.087/-0.476 (water). Approaching the NNL from postnatal enamel, the percentage differences in component volumes were: -1.93 to -3.22 % for the mineral volume, +21.26 to +35.42 % for the organic volume, and +3.86 to +6.03 % for the water volume. Towards postnatal enamel, the percentage differences had the opposite trend. CONCLUSIONS: The enamel NNL is slightly hypomineralized with an increased organic volume one order of magnitude higher than the percentage differences in both mineral and water volumes.

Morphologic Changes of Apical Foramen and Microcrack Formation after Foraminal Enlargement: A Scanning Electron Microscopic and Micro-computed Tomographic Analysis.

INTRODUCTION: The aim of the present study was to evaluate the morphologic changes on the apical foramen and the formation of dentinal microcracks after foraminal enlargement in straight and curved root canals using scanning electron microscopic (SEM) and micro-computed tomographic (micro-CT) analyses. METHODS: Sixty teeth were selected and divided into 2 experimental groups: GI (incisors/straight group, n = 30) and GM (molars/curved group, n = 30). Each group was divided into 2 subgroups (n = 15) according to the analysis performed: SEM or micro-CT analysis. The incisors and mesiobuccal canal of molars were instrumented with Reciproc Blue R25 instruments (VDW, Munich, Germany) using standardized shaping procedures in the apical foramen and 1 mm beyond. The occurrence of foraminal deformation was analyzed by scanning electron microscopy. The z test was used for statistical analysis (P < .05). Micro-CT imaging was used to observe the presence of microcracks in the root apical third. Afterward, pre- and postoperative cross-sectional images were screened to identify the presence of dentinal defects. RESULTS: The curvature of the canal did not influence the occurrence of foraminal deformation either for instrumentation in the foramen or for instrumentation beyond the foramen (P > .05). It was also observed that the increase in the working length did not influence the appearance of new deformations in the GI/SEM and GM-SEM groups (P > .05). Qualitative micro-CT analysis showed the presence of dentinal defects in 0.8% (112) and 1.5% (208) of the cross sections of incisors and molars, respectively, from a total of 13,987 slices. All dentinal defects identified in the analysis of any postoperative scans were already present in the corresponding preoperative images. Therefore, no new microcracks were observed after root canal preparation. CONCLUSIONS: The preparation of straight and moderately curved root canals with Reciproc Blue, regardless of the working length, did not influence the occurrence of apical foramen deformations and did not cause the formation of dentinal microcracks.

Enhanced teeth whitening by nanofluidic transport of hydrogen peroxide into enamel with electrokinetic flows.

Tooth whitening, a routine procedure in dentistry, is one of the examples of medical procedures that are limited by the challenge of delivering molecules into various types of nanoporous tissues. Current bleaching methods rely on simple diffusion of peroxides into enamel nano channels, therefore requires sufficient contact time with peroxides. In-office treatments often involve enamel etching or light activation which often results in patient sensitivity and potential soft tissue damage. OBJECTIVE: To demonstrate a robust method to transport hydrogen peroxide to greater depths into enamel nanopores through nanofluidic flows driven by electrokinetics, with the intention to increase efficacy while reducing treatment time. METHODS: Freshly extracted human teeth were subjected to electrokinetic flow treatment with hydrogen peroxide under different electric fields with varying operation times. Pre- and post-operative shade matching was done using a photospectrometer. RESULTS: It is demonstrated that the operation time for the same concentration of hydrogen peroxide can be shortened by 10 times. The proposed method showed significant improvements in whitening effects over control groups and thus offers promising clinically-viable chairside applications with efficacy. SIGNIFICANCE: The demonstrated nanofluidic transport of hydrogen peroxide into enamel has a potential to be applied for enhancing tooth whitening, compared to simple diffusion, without heating the hard dental tissues.

Influence of infiltrant application time on the reduction of opaqueness of proximal enamel caries.

INTRODUCTION: Infiltrant resins were developed to hamper carious lesion progression and mask the whitish appearance of first evidence of caries. OBJECTIVE: This study aimed at testing the hypothesis that a long application time of resin infiltrant in proximal enamel caries improves esthetic outcome compared to the commercially recommended time. MATERIALS AND METHODS: Twenty teeth with uncavitated inactive proximal white enamel caries lesions (selected by two calibrated examiners; inter-examiner κ = 0.87) were divided into two groups (experimental and control group; n = 10) that agreed regarding lesion surface area. Lesions were infiltrated following the protocol recommended by the manufacturer (two applications, 3 min application first and another 1 min application later; control) and by the protocol tested in this study (one application of 30 min; experimental). Enamel opaqueness (esthetic outcome) was measured by a calibrated examiner (intra-class coefficient of 0.9) before and after infiltration using fluorescence microscopy. RESULTS: Reduction of enamel opaqueness was significantly higher in the experimental group (40.0% ± 18.5%) than in the control group (18.6% ± 14.9%) (P = 0.0105, one-tailed t-test; Hedge's g of 1.28, 95% confidence interval of 0.43/2.13, and power of 86%). CONCLUSIONS: It can be concluded that the application time of 30 min provides a greater reduction in opaqueness of proximal enamel lesion compared to the application time recommended by the manufacturer. The high effect size could stimulate patients to comply with the treatment time.

Natural enamel caries, dentine reactions, dentinal fluid and biofilm.

It is believed that penetration of dentinal fluid into natural enamel caries (NEC) is negligible because of the barrier created by underlying sclerotic dentine, but there are conflicting evidences on whether dentine subjacent to NEC is sclerotic or demineralized. This study aimed at investigating the relationship between NEC, subjacent dentine reactions, modification of dentinal fluid, and composition of cariogenic biofilm formed on the NEC surface. Proximal NEC (PNEC) lesions of human permanent posterior teeth were included in five experiments. Histologically, microradiographic analysis with contrast solution (MRC) in dentine revealed a decreased proportion of sclerotic dentine and an increased proportion of deep dentine demineralization compared to the classical stereomicroscopic histological analysis based on dentin color and translucency. Real-time MRC and 3D optical profilometry, and 3D microtomographic analysis evidenced a facilitated transport of modified dentinal fluid towards PNEC lesions. Cariogenic biofilm formed in vitro on the PNEC surface presented lower amounts of insoluble and soluble matrix polysaccharides when 2% chlorexidine was inserted in the pulp chamber. In conclusion, this study evidenced that dentine subjacent to PNEC is mostly demineralized, providing facilitated pathway for dentinal fluid to penetrate into PNEC and alter the composition of the biofilm formed on the PNEC surface.

High Amount of Organic Matter during Caries Formation Reduces Remineralization and Resin Infiltration of Enamel Caries.

The amount of organic material in the cariogenic environment correlates with the amount of organic material incorporated in carious enamel. The incorporated organic material may be expected to reduce the pore volumes available for remineralization and resin infiltration, but these expected outcomes have not yet been quantified. We tested the effect of the amount of organic content in the cariogenic agent on remineralization and the resin-occluded pore volume in artificial subsurface enamel caries. An acid gel (organic-rich; G1) and an aqueous solution (organic-poor; G2) were used to induce subsurface lesions in human enamel. Undemineralized histological sections were prepared, microradiographed, and then submitted to resin infiltration in vitro. The enamel component volumes (mineral, organic, remineralizable [total water volume], loosely and firmly bound water volumes, and resin-occluded volume) were measured (by microradiography and polarizing microscopy) at histological sites (n = 38, G1; n = 34, G2). The main outcomes were the differences between the experimental and the predicted volumes (Δremineralizable and Δresin-occluded volumes). Resin infiltration was confirmed by confocal scanning laser microscopy. Compared to G2, G1 presented more incorporated organic volume and lower Δremineralizable volume (p = 0.003; Hedges g = 0.66; power = 0.87), a lower increase in loosely bound water volume (p = 0.0013; Hedges g = 0.74; power = 0.93), a lower remineralization volume in the surface layer (p = 0.017; Hedges g = 0.68; power = 0.8), and a lower Δresin-occluded volume (p = 0.0015; Hedges g = 0.73; power = 0.92). In conclusion, the higher amount of organic matter in the cariogenic gel negatively affected remineralization and the resin-occluded volume in subsurface lesions.

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

[This corrects the article DOI: 10.1371/journal.pone.0183432.].

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.