Contrast-Enhanced Micro-CT Imaging of Murine Mandibles: A Multi-Method Approach for Simultaneous Hard and Soft Tissue Analysis.

AIM: To develop and evaluate a novel multi-method micro-computed tomography (µCT) imaging protocol for enhanced visualization of both hard and soft tissues in murine mandibles, addressing the limitations of traditional imaging techniques in dental research. MATERIALS AND METHODS: We employed a contrast-enhanced (CE) µCT imaging technique using Lugol's iodine as a contrast agent to visualize the intricate structures of murine mandibles. The protocol involved the combination of conventional µCT imaging as well as CE-µCT, including decalcification with EDTA, allowing for simultaneous assessment of hard and soft tissues. The method is compared with standard imaging modalities, and the ability to visualize detailed anatomical features is discussed. RESULTS: The CE-µCT imaging technique provided superior visualization of murine mandibular structures, including dental pulp, periodontal ligaments and the surrounding soft tissues, along with conventional µCT imaging of alveolar bone and teeth. This method revealed detailed anatomical features with high specificity and contrast, surpassing traditional imaging approaches. CONCLUSION: Our findings demonstrate the potential of CE-µCT imaging with Lugol's iodine as a powerful tool for dental research. This technique offers a comprehensive view of the murine mandible, facilitating advanced studies in tissue engineering, dental pathology and the development of dental materials.

Ultrastructural evaluation of adverse effects on dentine formation from systemic fluoride application in an experimental mouse model.

AIM: Fluoride is widely used in dentistry for its caries prevention. To reduce dental caries, the optimal fluoride concentration of public water supplies in the United States is 0.7 ppm. However, excessive systemic fluoride consumption can lead to dental/enamel fluorosis. Numerous studies have explored the effects of fluoride on enamel and enamel-forming cells. However, research on systemic fluoride's impact on dentine is limited, particularly the effect of fluoride on the structure of the dentine-pulp complex. Therefore, this study aimed to identify how excessive fluoride affects dentine microstructure using an experimental mouse model. METHODOLOGY: C57BL6/J male mice (6-9 weeks old) were randomized into four groups (Fluoride at 0, 50, 100, or 125 ppm in drinking water) (n = 4/group). Mice were provided water ad libitum for 6 weeks along with fluoride-free food. Thereafter, mandibular incisors were analysed. Enamel phenotypes were evaluated using light microscopy and quantitative light-induced fluorescence (QLF) to measure fluorosis levels. Dentine morphology was evaluated using micro-CT, scanning electron microscopy (SEM), SEM-EDX (energy-dispersive X-ray), microhardness test and histological imaging. Data were analysed using one-way ANOVA with Dunnett's multiple comparisons as a post hoc test and the Kruskal-Wallis test with Dunn's multiple comparisons post hoc test (p < .05). RESULTS: Mice treated with fluoride at 50-125 ppm developed enamel hypoplasia in their erupting incisors and micro-CT imaging revealed that fluoride 125 ppm caused external resorption of the growing incisor. Dentine mineral density, dentine volume decreased compared with the 0 ppm control, while pulp volume increased compared with the 0 ppm control group. SEM showed wider predentine layer and abnormalities in calcified matrix vesicles derived from odontoblasts in fluoride 100 and 125 ppm groups. Vickers microhardness of dentine significantly decreased in the high-dose group. Fluoride-induced dentine hypoplasia in a dose-dependent manner. Histological evaluation showed excessive fluoride 125 ppm induced micro abscess formation and inflammatory cell infiltration. Fluoride induced dentine dysplasia with a dentine microstructure resembling hypophosphatasia. CONCLUSIONS: High doses of systemic fluoride can cause dentine dysplasia. Both three-dimensional and microstructural analyses showed the structural, chemical and mechanical changes in the dentine and the mineralized tissue components, along with external resorption and pulp inflammation.

Effect of Low- and High-Level Laser Therapy on the Treatment of Dentin Hypersensitivity: An Umbrella Review.

Introduction: Dentin hypersensitivity (DH) is a prevalent unpleasant condition which might affect quality of life. Laser therapy is one of the non-invasive treatments for dentin hypersensitivity. The aim of this umbrella review was to assess the effect of lasers on the treatment of dentin hypersensitivity by analyzing the previously published systematic reviews and meta-analyses. Methods: Electronic databases (PubMed, Embase, Scopus, Cochrane, and ISI) were searched to identify relevant systematic reviews and meta-analyses based on the keyword search strategy. Two independent reviewers carried out the selection of studies, extraction of data, and assessment of methodological quality. The actual overlap of primary studies was measured through the visual tool known as the citation matrix and three indices of % overlaps, covered area (CA), and corrected covered area (CCA). The reviews were appraised for methodological quality through A Measurement Tool to Assess Systematic Reviews (AMSTAR)-2, and the risk of bias was evaluated using the Risk of Bias in Systematic Reviews (ROBIS) tool. Results: Following eliminating duplicates, a total of 2,768 articles were found, and of them, 9 systematic reviews met the inclusion criteria. Six of them included a meta-analysis as well. The actual overlap of primary studies was low. The AMSTAR 2 tool classified one systematic review as high quality, three as moderate quality, three as low quality, and the remaining two as critically low quality. The results of the included reviews generally showed that all types of lasers reduced dentin hypersensitivity compared to placebo/no treatment. Conclusion: Lasers are effective in treating dentin hypersensitivity.

An in vitro assessment of the influence of dentinal pretreatment with chlorhexidine, nonthermal atmospheric plasma, chitosan, and proanthocyanidins on shear bond strength to composite.

Context: Dentin biomodification has been emphasized as a means of improving the bond between composite resin and tooth surface, consequently enhancing its longevity. Aim: To evaluate the shear bond strength (SBS) of dentin after pretreatment with 2% chlorhexidine (CHX), 2% chitosan, nonthermal atmospheric plasma (NTAP), proanthocyanidins (5% pine bark ((PB) and 5% bromelain). Settings and Design: The study was designed as an in vitro investigation. Materials and Methods: Sixty extracted mandibular molars (n = 60) were gathered for this in vitro research. The teeth were decoronated to expose the dentinal surface. All samples have been etched with 37% phosphoric acid and then pretreated with respective dentin biomodifiers. Group I (control): No pretreatment was done, Group II: 2% CHX, Group III: NTAP, Group IV: 5% PB, Group V: 2% chitosan, Group VI: 5% bromelain. Specimens were evaluated for the SBS test, which was done under the instron universal machine at a speed of 1 mm/min after a bonding agent and composite build-up were applied. Results: While Group I had the lowest SBS (10.391.59Mpa), Group V had the highest SBS (30.111.53 Mpa). Pretreatment of the dentin enhanced the SBS of dentin to composite. Conclusion: When utilized after etching, dentin biomodification increased all experimental group's bond strength in contrast to the control. The highest SBS values were recorded with 2% chitosan, followed by NTAP.

Forensic International Dental Database (FIDBv2) for adult age-at-death estimation in multiple forensic contexts: Strengthening the operationalization of the Lamendin criteria in a global scope model.

The aim of this study is to validate the FIDBv2 online procedure for adult age-at-death estimation using root dentine translucency (RDT) and periodontal retraction (PR) of single-rooted teeth in a worldwide sample. The sample includes 4810 teeth of 2559 individuals from 16 countries of America, Europe and Asia. Bias and inaccuracy between documented (DA) and estimated ages (EA) were calculated. Pearson and Intraclass Correlation Coefficients were computed to assess the strength of agreement between pairs of data, while Kolmogorov-Smirnov Z was used to evaluate the statistical significance of the differences. The percentages of correctly estimated cases within different age ranges were obtained to find trends in the reliability of the results. Most of the biases (-4.61-1.31 years) and inaccuracies (4.81-9.72 years) are low. The dispersion of EA increases with age and almost all the DA-EA correlations are above 0.75. DA-RDT and DA-PR correlations are positive, most of the former being high (0.74-0.91), and the latter being low (0.11-0.54). The highest percentages of correct estimations are identified for the ±7.5 and ±10 years ranges, and most comparisons of bias and inaccuracy between countries are non-significant. The high correlations between DA and EA suggest that the method is robust and reliable for a global application. Mean errors are low, with the best results found in the 30-69-year-old cohort. This research supports that the method is effective and accurate for age estimation in forensic contexts worldwide, thus reaffirming it is a generalizable procedure locally and internationally.

Why don't patients with dentine hypersensitivity discuss the condition with their dentist?

OBJECTIVES: This qualitative study aimed to develop an understanding of patients' barriers and facilitators of conversations about dentine hypersensitivity (DH) with their dentist. METHODS: The Theoretical Domains Framework shaped the topic guide for 26 participants who were troubled (High H) or not particularly troubled (Low L) by DH. Inductive thematic analysis of anonymised, transcribed, online focus group conversations was undertaken to identify reasons for non-discussion of DH during dental consultations. RESULTS: Participants reported that dentists did not routinely discuss DH, nor did participants feel they could bring it up. There was a perception among participants that DH was not a 'proper' condition and DH pain was not worthy of dentists' attention. Participants reported dealing with DH through lifestyle changes, and had little faith that dentists could offer more than 'just toothpaste' and voiced a need for a 'miracle cure'. Dental anxiety was a reported barrier to conversations. A positive attitude to DH by a dental team that normalised the condition and acknowledged its impacts on patients was voiced as a potential facilitator to DH discussions. CONCLUSIONS: DH conversations do not routinely take place in dental practice because patients believe DH is not serious, DH pain is not legitimate and there is no credible solution dentists can offer. Patients and dental teams need to be supported through behavioural science tools to change these perceptions for DH conversations to take place more routinely. CLINICAL SIGNIFICANCE: As DH cannot be diagnosed by visual inspection of teeth, patients cannot be managed unless they raise the issue of their DH with their dentist. The paper helps clinicians manage patients who are reticent to discuss DH with them and suggests how dentists may intervene to help.

Prevalence of dentine hypersensitivity, erosive tooth wear, gingival recession and periodontal health in seven European countries.

OBJECTIVES: To determine the prevalence and associated risk indicators for dentine hypersensitivity (DH), erosive tooth wear (ETW), gingival recession (GR), and gingival inflammation (bleeding on probing, BOP), with clinical and questionnaire data from seven European countries. METHODS: A cross-sectional, observational, seven-European country, epidemiological study in systemically healthy adults. Participants completed a questionnaire regarding oral hygiene, diet and lifestyle factors. A clinical examination, by calibrated examiners, measured DH (Schiff; participant yes/no), ETW (basic erosive tooth wear examination, BEWE), GR (mm), and BOP (yes/no). RESULTS: 3551 participants completed the study, mean age 44 ± 17.4, 43.6 % male, 26.1 % rural dwellers. DH (Schiff ≥ 1) was seen in 75.9 % of participants, ETW (BEWE ≥ 1) in 97.6 %, GR (≥1 mm) in 87.9 %. 65.7 % participants had BOP ≥ 10 % sites, 34.3 % BOP<10 % with probing depths ≤3 mm. DH, ETW, GR and BOP increased markedly during young adult life. Thereafter, GR and ETW continued to increase, DH declined after around age 38-47, and BOP plateaued after age 48. DH was significantly associated with ETW (p < 0.001) and GR (p < 0.01); GR was significantly associated with BOP on lingual surfaces (p = 0.017). There were significant associations between increased full mouth BOP ≥ 10 % and reduced brushing duration and exercise frequency (p < 0.001); increased DH and heartburn (p < 0.001); decreased DH (p < 0.001), ETW (p < 0.001) and BOP ≥ 10 % (p = 0.002) with powered toothbrush use. CONCLUSIONS: Prevalence of oral conditions assessed was high, greater than in the majority of the GR, DH and ETW literature. Periodontal health was seen in a third of sampled individuals. All these conditions varied markedly by country and age. CLINICAL SIGNIFICANCE: Oral diseases and conditions were highly prevalent throughout the seven European countries investigated. For the majority, these conditions are eminently preventable and treatable by changing behaviours. Upstream policy changes are needed to address these health challenges, to raise awareness and to empower individuals with oral health education and support.

Animal models and related techniques for dentin study.

The intricate and protracted process of dentin formation has been extensively explored, thanks to the significant advancements facilitated by the use of animal models and related techniques. Despite variations in their effectiveness, taking into account factors such as sensitivity, visibility, and reliability, these models or techniques are indispensable tools for investigating the complexities of dentin formation. This article focuses on the latest advances in animal models and related technologies, shedding light on the key molecular mechanisms that are essential in dentin formation. A deeper understanding of this phenomenon enables the careful selection of appropriate animal models, considering their suitability in unraveling the underlying molecular intricacies. These insights are crucial for the advancement of clinical drugs targeting dentin-related ailments and the development of comprehensive treatment strategies throughout the duration of the disease.

Evaluation of Surface Topography and Biomimetic Remineralization Capacity of Dendrimers in Comparison With Calcium Silicate Cement: An In Vitro Study.

INTRODUCTION: Biodentine, a calcium silicate-based material, is known for its biocompatibility and ability to promote dentin regeneration. With their unique branching structure, polyamidoamine (PAMAM) dendrimers have shown promise in facilitating biomimetic remineralization processes. AIM: This study investigates the synergistic effects of combining PAMAM with Biodentine on root dentin remineralization, aiming to develop a novel bioactive compound that offers superior protective and regenerative properties. METHODS: The following predictions were made: (1) In a cyclic artificial saliva/acid regimen, among the test groups, the combination of Biodentine and PAMAM would cause the most root dentin remineralization (2). Biodentine alone would increase Ca and P concentrations, neutralize acid, and promote root dentin remineralization (3). PAMAM, on the other hand, can remineralize the demineralized root dentin. RESULTS: Minimal mineral regeneration was accomplished in demineralized root dentin when treated with Biodentine or PAMAM alone. Root dentin remineralization was most pronounced when Biodentine and PAMAM were used together, and the hardness of demineralized root dentin was raised to an equivalent level to that of healthy root dentin. DISCUSSION: The study demonstrated the exceptional ability of PAMAM + Biodentine to promote root dentin remineralization. In an acid-challenging environment, PAMAM + Biodentine promoted full and efficient root dentin remineralization. Restorations made using innovative PAMAM + Biodentine technology show promise in remineralizing and protecting tooth structures.

Mind the gap-What is the appropriate time interval between sequential dentine stimuli to elicit a dentine hypersensitivity pain response in clinical studies?

OBJECTIVES: To determine the time interval required for a tooth diagnosed with DH to recover from a stimulus (cold air-blast/tactile) and respond with a similar elicited pain response to a repeat stimulus. METHODS: A single-centre, non-randomised, clinical study in healthy adult volunteers. Eligible participants with ≥1 tooth with either a qualifying Schiff score ≥2 following cold air-blast or tactile Yeaple score of ≤20 g were allocated to tactile or air-blast group. Following primary stimulation, the designated tooth was restimulated 10, 5, 2 min and immediately after initial pain cessation. Pain was recorded with participant VAS and investigator Schiff for air-blast. RESULTS: 40 participants completed the study per group. There was a significant difference in VAS scores for tactile 4 delay intervals (p < 0.001) but not air-blast stimulus, and a significant difference in mean change in VAS score from immediate to two-minute delay between stimuli (8.0 tactile vs 0.8 air-blast, p = 0.011). VAS scores in response to either stimulus showed very wide variation between participants, but changes over delay intervals within participants were relatively slight. There was a significant progressive decrease in mean Schiff score with shortening delay intervals from 10 min (2.38) to stimulation immediately after pain cessation (2.15), p = 0.018. CONCLUSIONS: The findings suggest healthy teeth recover after DH stimulation more quickly following an air-blast than tactile stimulus, with around 2 min allowing recovery from both. Many factors including habituation and pain measurement subjectivity need to be considered. It would be prudent for future studies to use of ≥3 min delays. CLINICAL SIGNIFICANCE: No clinical study has attempted to determine the appropriate interval between successive stimuli in DH patients. The results will impact directly on the conduct of DH trials. These findings suggest the interval could be reduced to around 2-min, but the current standard of 5-min is sufficiently long to give valid results.

Effect of Calcium Hydroxide as an Intracanal Medication on Dentine Fracture Resistance: A Systematic Review and Network Meta-Analysis.

INTRODUCTION: Bacterial infections necessitate effective root canal disinfection during endodontic therapy. Calcium hydroxide (CH), a widely used intracanal medication, shows conflicting effects on dentine fracture resistance in different studies. This study aimed to perform a comprehensive systematic review and network meta-analysis to evaluate the effects of CH on the fracture resistance of dentine in human teeth across different periods. METHODS: PubMed, EMBASE, MEDLINE (EBSCO), Cochrane Library, Scopus, Google Scholar, and ProQuest databases were exhaustively searched to identify studies published until February 29, 2024, with no language restrictions. Laboratory studies that investigated dentine fracture resistance in human permanent teeth following intracanal CH exposure were included. The risk of bias was evaluated using modified criteria derived from previous studies. Network meta-analysis was performed using the frequentist method. Prespecified subgroup analyses focused on simulating immature teeth. RESULTS: The search yielded 2,265 studies from all databases, and 27 met the inclusion criteria, involving 3,879 teeth or roots. The overall results from network meta-analysis indicated that CH affected the fracture resistance of human dentine. Subgroup analysis revealed that the duration influencing fracture resistance was ≥4 weeks for mature teeth, but no specific time limitation for immature teeth. The overall quality of the evidence showed a moderate to high risk of bias. CONCLUSIONS: Short-term use of CH does not compromise human root dentine strength, supporting its routine application in clinical practice. CH remains a viable treatment strategy for over 4 weeks of medication needs but requires carefully considering the associated risks and benefits emphasizing on preservation and disease resolution. REGISTRATION: PROSPERO database (CRD 42024513199).

A comparison of different cleaning approaches for blood contamination after curing universal adhesives on the dentine surface.

OBJECTIVE: This study compared the effectiveness of various cleaning approaches, including spray rinsing, repreparing with diamond burs, and using phosphoric acid or sodium hypochlorite alone or with polyphenols (resveratrol or myricetin), in removing blood contamination from the dentine after adhesive light-curing. METHODS: The contact angles of the treated surfaces were measured and scanning electron microscopy/ energy dispersive X-ray spectroscopy observation was performed. The bond strength and nanoleakage were assessed, and in situ zymography was performed before and after aging. Interactions between matrix metalloproteinase (MMP)-9 and polyphenols were evaluated using molecular dynamics and rhMMP-9 inhibition analyses. The destruction of sodium hypochlorite on collagen and the resistance of polyphenols-treated dentine collagen to enzymolysis were evaluated using the hydroxyproline (HYP) assay. The effect of polyphenols on dentine collagen crosslinking was assessed by Fourier Transform Infrared Spectroscopy. RESULTS: The repreparation group had the lowest contact angle compared to the other groups. The spray rinsing group had the lowest bond strength and highest amounts of nanoleakage. Cleaning with phosphoric acid or sodium hypochlorite alone removed the blood contaminants and parts of the adhesive; moreover, applying polyphenols further improved the bond strength and decreased nanoleakage and MMP activity after aging. Both polyphenols inhibited rhMMP-9 activity and promoted collagen crosslinking. Sodium hypochlorite showed the maximum HYP release when used alone, which was decreased after adding polyphenols. SIGNIFICANCE: Phosphoric acid or sodium hypochlorite cleaning can remove blood contamination from the dentine surface after adhesive curing, and the addition of polyphenols can improve the durability of dentine bonding.

Influence of azathioprine on healing of exposed dogs' dental pulp capped with three different materials.

Background: Azathioprine is one of the earliest immunosuppressants prescribed for several autoimmune diseases. Yet there is a lack of research on the impact of azathioprine on pulp healing following the pulp capping procedure. Aim: This study aimed to investigate the effect of azathioprine on the healing ability of mechanically exposed dogs' dental pulps following direct pulp capping with mineral trioxide aggregate (MTA), bio-aggregates (BA), and Calcium hydroxide (Ca(OH)2). Methods: Four mongrel dogs were randomly assigned to two groups (two dogs/30 teeth in each group): immunosuppressed (group I) and control (group II). Group I received azathioprine for two months before surgical treatments and until the dogs were euthanized. Fifteen class V buccal cavities were performed in each dog. Each group was randomly divided into three subgroups (10 teeth each) based on the pulp capping substance. The pulps in subgroups A, B, and C were immediately capped with MTA, BA, and Ca(OH)2, respectively. Inflammation and dentine bridge development were histopathologically evaluated and scored at one and two months. The data were statistically analyzed. Results: The immunosuppressed group exhibited statistically greater inflammatory cell count and decreased dentine bridge thickness, compared to the control group in all subgroups (p < 0.05). Conclusion: Azathioprine has an adverse effect on the healing of exposed dogs' dental pulp following direct pulp capping with MTA, BA, and Ca(OH)2. Therefore, patients using azathioprine as an immunosuppressive medication may experience delayed healing of mechanically exposed pulps following capping with MTA, BA, or Ca(OH)2.

Diffusion of Silver Diamine Fluoride Solution in Dentine: An In Vitro Study.

OBJECTIVES: The aim of this research was to assess the diffusion dynamics of silver and fluoride ions after 38% silver diamine fluoride (SDF) solution application on dentine of varying thicknesses over 24 weeks. METHODS: Bovine dentine discs of 5.5 mm in diameter were prepared and separated into 3 groups with thicknesses of 0.5 mm (group 1), 1.0 mm (group 2), and 1.5 mm (group 3). The diameter and number of dentinal tubules of discs were assessed. Each disc received a topical application of 0.05 mL 38% SDF solution. The deionised water in the tube was collected weekly for 24 weeks. The silver and the fluoride ion concentrations in the collected deionised water were determined. Generalised estimating equations was used to explore the potential effects of the key factors on the silver/fluoride diffusion. RESULTS: The amount of silver and fluoride ion diffusion through dentine almost levelled off after 4 weeks and showed a decline trend over 24 weeks. The mean (SD) 24-week cumulative ion diffusion through dentine in groups 1, 2, and 3 was as follows: 20 (4) µg, 10 (2) µg, and 5 (1) µg for silver (P < .05) and 18 (2) µg, 13 (2) µg, and 7 (1) µg for fluoride (P < .05), respectively. CONCLUSIONS: Silver and fluoride ion diffusion through dentine showed a decline trend over 24 weeks. The diameter and the number of dentinal tubules on dentine with different thicknesses affects the ion diffusion dynamics. This study provides indications on the pattern of silver/fluoride ions diffusion through dentine to pulp after 38% SDF application. An increased amount of silver/fluoride diffuses through dentine into the pulp with decreased remaining dentine thickness.

Heterogeneity in experiences of vitamin D deficiency in an early to mid-19th century population from Montreal, Quebec.

OBJECTIVE: To use the prevalence of prenatal/infancy interglobular dentine (IGD) as a proxy for suboptimal vitamin D status and explore its link to mortality, biological sex, cultural behaviours and environmental factors during the end of the pre-industrial/ beginning of the industrial period. MATERIALS: 50 skeletons from the St. Antoine cemetery (1799-1854), Montreal, Quebec with a well-preserved first mandibular molar. METHODS: Thin sections were prepared for histological examination of IGD in crown dentine. RESULTS: IGD prevalence was 74 % (37/50) and not significantly correlated statistically to sex and age-at-death. Most IGD occurred at birth and up to 3 years-old, six individuals were affected in utero, 54 % of the sample (27/50) presented longstanding IGD and six individuals displayed multiple IGD episodes. CONCLUSIONS: Prenatal IGD episodes revealed suboptimal maternal vitamin D levels, which, alongside a high frequency of IGD episodes around birth/from birth until a certain age, suggest cultural influences. Multiple and longstanding IGD episodes might also reflect suboptimal seasonal vitamin D attainment. SIGNIFICANCE: This study provides in-depth data on IGD within a relatively large archaeological North American sample, proving relevant to epidemiological studies on suboptimal vitamin status in 19th century Montreal. LIMITATIONS: The total number of IGD episodes is underestimated due to methodological biases; first-generation migrants in this study could not be identified and excluded from the sample. SUGGESTIONS FOR FURTHER RESEARCH: Use of a larger sample with a wider age-at-death range; further research on infants and children to investigate links between growth and lesion formation and visibility.

Developing a novel antibacterial copper tetraamine fluoride.

OBJECTIVE: To develop a novel and biocompatible copper tetraamine fluoride (CTF) with antibacterial and nondiscolouring properties. METHOD: This study used copper fluoride and ammonia solution to develop CTF solution. The CTF was characterized by X-ray photoelectron spectroscopy (XPS). Cytotoxicity was evaluated by stem cells from human exfoliated deciduous teeth (SHED) and human gingival fibroblasts (HGF-1). The fluoride concentration was determined using ion-selective electrode. The alkalinity was measured by a pH electrode. The human dentine blocks were treated with CTF and then incubated with Streptococcus mutans to evaluate the antimicrobial and discolouring effects. The silver diamine fluoride (SDF) was employed as the positive control, and water was the negative control. The colony-forming units (CFUs) and confocal laser scanning microscopy (CLSM) were used to examine the kinetics and viability of the biofilm. The discolouring property on dentine was assessed by spectrophotometry. One-way analysis of variance with the Bonferroni post hoc test was performed to assess and compare the data. RESULTS: XPS confirmed synthesis of CTF solution. The half-maximal inhibitory concentration of CTF on SHED and HGF-1 was 195±16 ppm and 137±11 ppm. The fluoride concentration was 121,000±5,000 ppm. The pH value was 9. Log10 CFU of the CTF, SDF and water group were 5.0 ± 0.2, 4.9 ± 0.1 and 7.4 ± 0.1 (p < 0.001, CTF, SDFWater). Spectrophotometry showed that the ΔE of the CTF, SDF and water group were 5 ± 2, 6 ± 3 and 45±2 (p < 0.001, CTF, Water

Resin tags formation by modified Renewal MI formulations in a carious dentine model.

Objectives: To determine which components in a new restorative material (Renewal MI) improve its ability to form resin tags within demineralized dentine. Methods: Varied components included polylysine (PLS), monocalcium phosphate (MCP), powder to liquid ratio (PLR), 4-methacryloyloxyethyl trimellitate anhydride (4META), and polypropylene glycol dimethacrylate (PPGDMA). Urethane dimethacrylate (UDMA), containing PPGDMA (24 wt%) and 4META (3 wt%), was mixed with glass filler with MCP (8 wt%) and PLS (5 wt%). PLR was 3:1 or 5:1. Reducing MCP and/or PLS to 4 and 2 wt% respectively or fully removing MCP, PLS, 4META or PPGDMA gave 16 formulations in total. Renewal MI, Z250 (with or without Scotchbond Universal adhesive) and Activa were used as commercial comparators. Collagen discs were obtained by totally demineralizing 2 mm thick, human, premolar, coronal dentine discs by immersion in formic acid (4M) for 48 h. The restorative materials were then applied on top (n = 3), before dissolving the collagen in sodium hypochlorite (15%). SEM/EDX was employed to determine resin tags length, composition, and surface coverage. Results: Tags were >400, 20 and 200 µm and covered 62, 55 and 39% of the adhesion interface for Renewal MI, Scotchbond and Activa, respectively. With experimental formulations, they were 200 and >400 µm long with high vs. low PLR and composed primarily of polymerized monomers. Percentages of the adhesion interface covered varied between 35 and 84%. Reducing PLS or MCP caused a decline in coverage that was linear with their concentrations. Reducing MCP had lesser effect when PLS or PLR were low. Removal of 4META caused a greater reduction in coverage than PPGDMA removal. Conclusion: PLS, MCP, 4META, PPGDMA and low PLR together enhance Renewal MI tags formation in, and thereby sealing of, demineralized dentine.

Silicon impacts collagen remodelling and mineralization by human dental pulp stem cells in 3D pulp-like matrices.

OBJECTIVES: Silicon-releasing biomaterials are widely used in the field of dentistry. However, unlike bone, very little is known about the role of silicon on dental tissue formation and repair. This study investigates the influence of silicic acid on the survival, differentiation and mineralizing ability of human dental pulp stem cells (hDPSCs) in 3D pulp-like environments METHODS: Dense type I collagen hydrogels seeded with hDPSCs were cultured over 4 weeks in the presence of silicic acid at physiological (10 µM) and supraphysiological (100 µM) concentrations. Cell viability and proliferation were studied by Alamar Blue and live/dead staining. The collagen network was investigated using second harmonic generation imaging. Mineral deposition was monitored by histology and scanning electron microscopy. Gene expression of mineralization- and matrix remodeling-associated proteins was studied by qPCR. RESULTS: Presence of silicic acid did not show any significant influence on cell survival, metabolic activity and gene expression of key mineralization-related proteins (ALP, OCN, BSP). However, it induced enhanced cell clustering and delayed expression of matrix remodeling-associated proteins (MMP13, Col I). OPN expression and mineral deposition were inhibited at 100 µM. It could be inferred that silicic acid has no direct cellular effect but rather interacts with the collagen network, leading to a modification of the cell-matrix interface. SIGNIFICANCE: Our results offer advanced insights on the possible role of silicic acid, as released by pulp capping calcium silicates biomaterials, in reparative dentine formation. More globally, these results interrogate the possible role of Si in pulp pathophysiology.

Biomimetic pulp scaffolds prepared from extracellular matrix derived from stem cells from human exfoliated deciduous teeth promote pulp-dentine complex regeneration.

AIM: To evaluate the role of biomimetic pulp scaffolds derived from the extracellular matrix derived of stem cells from human exfoliated deciduous teeth (SHED-ECM-PS) in promoting pulp-dentine complex regeneration. METHODOLOGY: SHED-ECM-PS was prepared through cell aggregation and decellularization techniques. Histological and immunofluorescence analyses, scanning electron microscopy, and DNA quantification assays were used to characterize the SHED-ECM-PS. Additionally, a tooth slice implantation model was established to evaluate the effects of SHED-ECM-PS on regeneration of the pulp-dentine complex in vivo. Extraction medium for SHED-ECM-PS was prepared, and its effect on bone marrow mesenchymal stem cells (BMMSCs) was assessed in vitro. Cell counting kit-8 and Ki-67 staining assays were performed to determine cell proliferation. The rate of apoptosis was evaluated by flow cytometry. Wound healing and transwell assays were conducted to evaluate cell migration. Alizarin red S staining was performed to examine mineralized nodule formation. Western blotting was used to detect the expression of osteogenic and odontogenic markers. The results were analysed using an independent two-tailed Student's t-test. p < .05 was considered statistically significant. RESULTS: SHED-ECM-PS was successfully constructed, exhibiting a striped dental pulp-like shape devoid of nuclear structures or DNA components, and rich in fibronectin, collagen I, DMP1 and DSPP. Notably, SHED-ECM-PS showed no impact on the proliferation or apoptosis of BMMSCs. Histological analysis revealed that dental pulp fibroblasts formed an interwoven mesh in the root canal, and angiogenesis was observed in the SHED-ECM-PS group. Moreover, a continuous, newly formed tubular dentine layer with polarized odontoblast-like cells was observed along the inner wall of the root canal. SHED-ECM-PS promoted the migration, polar alignment and mineralized nodule formation of BMMSCs and specifically elevated the expression levels of odontogenic markers, but not osteogenic markers, compared with the control group in vitro. CONCLUSION: SHED-ECM-PS exhibited no cytotoxicity and promoted pulp-dentine complex regeneration in vivo as well as cell migration and odontogenic differentiation of BMMSCs in vitro. These findings provide evidence that SHED-ECM-PS, as a novel biological scaffold, has the potential to improve the outcomes of REPs.

In Vitro Evaluation of Remineralization Potential of Five Toothpastes on Soft Drink-Eroded Human Enamel and Dentine.

OBJECTIVE: The purpose of this in vitro study was to evaluate the potential remineralization of enamel and dentine erosion lesions after the application of five different toothpastes. METHODOLOGY: A total of 104 enamel and dentine samples were prepared from maxillary third molars. Each group was divided according to the toothpaste application mode (topical = 56; brushing = 48) and the toothpaste used seven topical groups and six brushing groups (n = 8). The groups included negative control (NC), positive control (PC), Sensodyne Pronamel (SP), Regenerate (R), Regenerate with boosting serum (R+), Colgate Duraphat 5000 (CD), and tooth mousse (TM). RESULTS: The statistical analysis showed significant surface microhardness (SMH) change. All enamel groups showed a significant decrease in SMH compared to NC for both application modes. However, no significance was recorded between test groups. Similar results were observed between dentine groups and their relevant controls for both application modes, except brushed R and R+ groups, which were insignificant to their NC. For topical groups, TM showed a significant increase in SMH. While R and R+ showed lower loss than SP and CD. CONCLUSIONS: All tested agents offered a degree of remineralization in both enamel and dentine with no significant difference between agents in enamel groups while R, R+, and TM offered better results in dentine groups. CLINICAL SIGNIFICANCE:  For dentine groups, similar findings were observed with superior tooth surface protection with the application of TM over other agents. Tooth surface remineralization was achieved when agents were either applied topically or brushed over the surface.