Antibacterial Property and Mechanisms of Au@Ag Core-Shell Nanoparticles with Near-Infrared Absorption Against E. faecalis Infection of Dentin.

Background: Enterococcus faecalis (E. faecalis) is one of the main pathogens responsible for refractory root canal infections in the teeth and shows resistance against various antibacterial managements. Effective control of E. faecalis infection is a prerequisite for successful treatment of refractory apical periodontitis. This study aimed to analyze the antibacterial activity and mechanisms of Au@Ag nanoparticles (NPs) combined with photothermal therapy (PTT) against the original and Ag+-resistant E. faecalis. Methods: Au@AgNPs with optimal shell thicknesses were synthesized and characterized. The antibacterial activity of Au@AgNPs with PTT against the original or Ag+-resistant E. faecalis was evaluated, and the antibiofilm activity was tested on E. faecalis biofilm on the dentin of teeth. The potential antibacterial mechanisms of Au@AgNPs combined with PTT against E. faecalis have also been studied. Moreover, its influence on dentin microhardness and cytotoxicity was assessed. Results: This study revealed that Au@AgNPs combined with PTT showed enhanced antibacterial and antibiofilm effects, no negative effects on dentin microhardness, and low cytotoxicity toward human periodontal ligament cells (hPDLCs). Moreover, Au@AgNPs combined with PTT effectively inhibited the growth of Ag+-resistant E. faecalis. Its antibacterial effects may be exerted through the release of silver ions (Ag+), destruction of the cell membrane, production of reactive oxygen species (ROS) and inhibition of adenosine triphosphate (ATP) production. Hyperthermia generated by Au@AgNPs with PTT reduced membrane fluidity and enhanced Ag+ sensitivity by downregulating fabF expression. The upregulated expression of heat shock genes demonstrated that the Ag+ released from Au@AgNPs compromised the heat adaptation of E. faecalis. Conclusion: PTT significantly enhanced Ag+ sensitivity of the original and Ag+-resistant E. faecalis. Au@AgNPs combined with PTT may have the potential to be developed as a new antibacterial agent to control E. faecalis infections in teeth.

Bone or Tooth dentin: The TGF-ß signaling is the key.

To investigate the cell linkage between tooth dentin and bones, we studied TGF-ß roles during postnatal dentin development using TGF-ß receptor 2 (Tgfßr2) cKO models and cell lineage tracing approaches. Micro-CT showed that the early Tgfßr2 cKO exhibit short roots and thin root dentin (n = 4; p<0.01), a switch from multilayer pre-odontoblasts/odontoblasts to a single-layer of bone-like cells with a significant loss of ~85% of dentinal tubules (n = 4; p<0.01), and a matrix shift from dentin to bone. Mechanistic studies revealed a statistically significant decrease in odontogenic markers, and a sharp increase in bone markers. The late Tgfßr2 cKO teeth displayed losses of odontoblast polarity, a significant reduction in crown dentin volume, and the onset of massive bone-like structures in the crown pulp with high expression levels of bone markers and low levels of dentin markers. We thus concluded that bones and tooth dentin are in the same evolutionary linkage in which TGF-ß signaling defines the odontogenic fate of dental mesenchymal cells and odontoblasts. This finding also raises the possibility of switching the pulp odontogenic to the osteogenic feature of pulp cells via a local manipulation of gene programs in future treatment of tooth fractures.

Impaired Tertiary Dentin Secretion after Shallow Injury in Tgfbr2-Deficient Dental Pulp Cells Is Rescued by Extended CGRP Signaling.

The transforming growth factor ß (TGFß) superfamily is a master regulator of development, adult homeostasis, and wound repair. Dysregulated TGFß signaling can lead to cancer, fibrosis, and musculoskeletal malformations. We previously demonstrated that TGFß receptor 2 (Tgfbr2) signaling regulates odontoblast differentiation, dentin mineralization, root elongation, and sensory innervation during tooth development. Sensory innervation also modulates the homeostasis and repair response in adult teeth. We hypothesized that Tgfbr2 regulates the neuro-pulpal responses to dentin injury. To test this, we performed a shallow dentin injury with a timed deletion of Tgfbr2 in the dental pulp mesenchyme of mice and analyzed the levels of tertiary dentin and calcitonin gene-related peptide (CGRP) axon sprouting. Microcomputed tomography imaging and histology indicated lower dentin volume in Tgfbr2cko M1s compared to WT M1s 21 days post-injury, but the volume was comparable by day 56. Immunofluorescent imaging of peptidergic afferents demonstrated that the duration of axon sprouting was longer in injured Tgfbr2cko compared to WT M1s. Thus, CGRP+ sensory afferents may provide Tgfbr2-deficient odontoblasts with compensatory signals for healing. Harnessing these neuro-pulpal signals has the potential to guide the development of treatments for enhanced dental healing and to help patients with TGFß-related diseases.

Engineering Interfacial Integrity with Hydrolytic-Resistant, Self-Reinforcing Dentin Adhesive.

The leading cause of composite restoration failure is secondary caries, and although caries is a multifactorial problem, weak, damage-prone adhesives play a pivotal role in the high susceptibility of composite restorations to secondary caries. Our group has developed synthetic resins that capitalize on free-radical polymerization and sol-gel reactions to provide dental adhesives with enhanced properties. The resins contain γ-methacryloxypropyltrimethoxysilane (MPS) as the Si-based compound. This study investigated the properties of methacrylate-based resins containing methacryloxymethyltrimethoxysilane (MMeS) as a short-chain alternative. The degree of conversion (DC), polymerization kinetics, water sorption, mechanical properties, and leachates of MMeS- and MPS-resins with 55 and 30 wt% BisGMA-crosslinker were determined. The formulations were used as model adhesives, and the adhesive/dentin (a/d) interfaces were analyzed using chemometrics-assisted micro-Raman spectroscopy. The properties of the 55 wt% formulations were comparable. In the 30 wt% BisGMA formulations, the MMeS-resin exhibited faster polymerization, lower DC, reduced leachates, and increased storage and loss moduli, glass transition (Tg), crosslink density, and heterogeneity. The spectroscopic results indicated a comparable spatial distribution of resin, mineralized, and demineralized dentin across the a/d interfaces. The hydrolytically stable experimental short-chain-silane-monomer dental adhesive provides enhanced mechanical properties through autonomous strengthening and offers a promising strategy for the development of restorative dental materials with extended service life.

[Transcription factor activator protein 2C contribute to molar development in mice].

Objective: Explore the expression pattern of transcription factor activator protein 2C (TFAP2C) and identify the roles of Tfap2c during tooth development. Methods: Real-time fluorescence quantitative PCR (RT-qPCR) was used to analyze the relative expression level of Tfap2c in various organs of embryonic day(E)14.5 mouse embryos and mouse molar germs at E12.5-E18.5 and postnatal day (P)0-P7. The expression position of Tfap2c in mouse molar germs was demonstrated by frozen section immunofluorescence staining. Cultured mandibular molar germs were transfected with control small interfering RNA (siRNA) or Tfap2c siRNA to evaluate the effect of Tfap2c on tooth molar germs development, and RT-qPCR was used to detect the relative expression level of genes related to odontoblast expression. Dental mesenchymal cells were isolated from E14.5 molar germs and transfected with control siRNA or Tfap2c siRNA, cell counting kit 8 (CCK-8) and scratch healing test were applied to detect dental mesenchymal cell viability and migration. Results: Tfap2c was highly expressed in the early development period of mouse molar germs. Tfap2c was expressed in the epithelial and mesenchymal tissues of E13.5 mouse molar germs and there was no significant difference of relative expression of Tfap2c between them (t=1.06, P=0.472). Tfap2c was expressed in mesenchymal tissues of E14.5 mouse molar germs and the relative expression of Tfap2c in mesenchymal tissues was significantly higher than epithelial tissues (t=37.29, P<0.0001). For molar germs transfected with Tfap2c siRNA, the relative height of cusps (0.708±0.171) and the ratio of cusp height and crown height (0.321±0.068) was significantly lower than control group (1.000±0.287 and 0.483±0.166) (t=2.79, P=0.012; t=2.85, P=0.015). But there was no significant difference in relative height (1.078±0.206, 0.993±0.254, t=0.83, P=0.419)and relative width (1.000±0.116, 0.999±0.122, t=0.01, P=0.992) of crowns between two groups. The relative expression level of genes related to odontoblast expression was decreased (Dspp: t=15.33, P<0.001; Dmp1: t=13.81, P<0.001). Tfap2c siRNA hinders cell migration in dental mesenchymal cells (t=29.86, P=0.001), but there was no significant difference in CCK-8 absorbance value between two groups. The relative expression level of genes related to odontoblast expression was also decreased in dental mesenchymal cells transfected with Tfap2c siRNA (Dspp: t=3.86, P=0.031; Dmp1; t=4.36, P=0.022). Conclusions: Tfap2c highly expressed in the early morphogenesis period of mouse molar germs, mainly in mesenchymal tissues. Tfap2c affected the cusps formation of mouse molar germs and migration of dental mesenchymal cells.

Advances in Regenerative Dentistry: A Systematic Review of Harnessing Wnt/ß-Catenin in Dentin-Pulp Regeneration.

Dentin pulp has a complex function as a major unit in maintaining the vitality of teeth. In this sense, the Wnt/ß-Catenin pathway has a vital part in tooth development, maintenance, repair, and regeneration by controlling physiological activities such as growth, differentiation, and migration. This pathway consists of a network of proteins, such as Wnt signaling molecules, which interact with receptors of targeted cells and play a role in development and adult tissue homeostasis. The Wnt signals are specific spatiotemporally, suggesting its intricate mechanism in development, regulation, repair, and regeneration by the formation of tertiary dentin. This review provides an overview of the recent advances in the Wnt/ß-Catenin signaling pathway in dentin and pulp regeneration, how different proteins, molecules, and ligands influence this pathway, either upregulating or silencing it, and how it may be used in the future for clinical dentistry, in vital pulp therapy as an effective treatment for dental caries, as an alternative approach for root canal therapy, and to provide a path for therapeutic and regenerative dentistry.

Complete versus incomplete caries removal procedures and their effects on dental pulp in primary teeth - An in vivo study.

INTRODUCTION: Dental caries results from an ecologic shift within the dental biofilm from a balanced population of microorganisms to an acidogenic, aciduric, and cariogenic microbiological population developed and maintained by frequent consumption of fermentable dietary carbohydrates. Total caries removal (TCR) of deep lesion may result in pulpal exposure requiring more invasive treatment. Hence, current pediatric dentistry has shifted to minimally invasive treatment that avoids more complex, time-consuming procedure, and the child's discomfort. AIM: The aim of this study is to evaluate and compare clinical performance and radiographic changes after complete and incomplete caries removal procedures. MATERIALS AND METHODS: The study was conducted on 60 primary molars in children aged 6-9 years. Selected 60 primary molars were randomly divided into two groups. Group 1 (PCR): infected dentin was removed, while the affected dentin was maintained on the pulpal wall. Group 2 (TCR): both infected and affected dentin were removed through low-speed carbide bur and hand excavator. Teeth were evaluated at 4 and 6 months clinically and radiographically. RESULTS: The proportion was compared using Fisher's exact test. The Statistical Package for the Social Sciences version 21 was used for analysis. The level of significance was kept at 5%. CONCLUSION: The clinical and radiographic success rates of ICR and CCR in primary teeth with deep carious lesions were high and did not differ significantly, indicating that the retention of carious dentin does not interfere with pulp vitality. Thus, ICR is a reliable minimally invasive approach that might replace the CCR in primary teeth when correctly indicated.

Effect of herbal irrigants on surface roughness of intraradicular dentin using quantitative method of 3D surface texture analysis.

Replacing the conventional endodontic irrigants with herbal agents could avoid complications associated with using sodium hypochlorite (NaOCl). Endodontic irrigants alter the surface roughness of the dentinal wall surface, which affects sealer mechanical retention. This study aimed to assess the effect of experimental herbal Moringa oleifera and orange peel extract irrigant on intraradicular dentin (IRD) surface roughness using quantitative 3D surface analysis by scanning electron microscopy (SEM) regarding the smear layer assessment. Sixty human root sections were divided into four groups (n = 15): NaOCl combined with 17% ethylenediaminetetraacetic acid (EDTA); negative control (saline); moringa extract (MO); and orange oil (OO). SEM images were assessed quantitatively for surface roughness (Ra) in the coronal, middle, and apical IRD. The data were analysed by Kruskal-Wallis, Friedman, and Dunn's tests. All groups showed statistically significant differences (P = 0.007). MO exhibited significantly greater Ra values at the coronal, middle, and apical root levels than OO (P = 0.007, 0.009, and 0.046, respectively). There was no significant change in Ra values at various root levels within each group at P = 0.091, 0.819, 0.819, and 0.549 for the EDTA, saline, MO, and OO groups. Considerable (IRD) surface roughness analysis makes Moringa extract a promising herbal endodontic irrigant alternative to the NaOCl plus EDTA regimen.

Evaluation of Monomer-containing Isocyanate Groups on Stabilizing Demineralized Dentin Matrix Against Bond Interface Degradation.

PURPOSE: To evaluate the effect of urethane methacrylate precursor (UMP) on the enzymatic resistance of demineralized dentin (DD) matrices. MATERIALS AND METHODS: Experimental treatments containing 0 (control), 1, and 5 mmol/L UMP dissolved in an acetone (Ace) solution were formulated. Dentin matrix specimens were demineralized in vitro and immersed in the experimental treatments for 1 h. The treated specimens were then stored in 0.1 mg/mL collagenase solution for 24 h, after which their dry mass loss and hydroxyproline (HYP) release were assessed. The swelling ratios of specimens in each group were also evaluated. The interaction between UMP and the dentin matrix was observed using field-emission scanning electron microscopy (FE-SEM). Endogenous enzyme activity in dentin was evaluated using confocal laser scanning microscopy (CLSM). RESULTS: Compared with the other treatment groups, treatment with 1 mM and 5 mM UMP-Ace significantly decreased the dry mass loss, HYP release and swelling ratio of the DD matrix (p < 0.05). FE-SEM and CLSM observations showed that treatment with UMP-Ace protected the structure of the dentin matrix and decreased porosity within the dentin-collagen network. CONCLUSION: Treatment with 1 mM and 5 mM UMP-Ace protects DD matrix against collagenase degradation and may be clinically useful for improving the durability of the hybrid layer.

Assessment of the Efficacy and Bond Strength of Different Dentin-bonding Agents with Adhesives on Primary Teeth: An In Vitro Study.

AIM: The purpose of this study was to evaluate the effectiveness and strength of three various dentin-bonding agents used with adhesives on primary teeth. MATERIALS AND METHODS: The study used 80 recently extracted, healthy human maxillary anterior primary teeth that had undergone physiologic resorption, or over-retention. Teeth were cut to expose a flat dentin surface at a depth of 1.5 mm. All samples were divided into four groups (20 samples in each group) as follows: Group I-Control group, Group II-Primary teeth bonding with 6th-generation bonding agent, Group III-Primary teeth bonding with 7th-generation bonding agent, Group IV-Primary teeth bonding with 8th-generation bonding agent. All of the samples' dentinal surfaces were covered with composite resin using a Teflon mold after adhesive had been applied. A universal testing machine (INSTRON) was used to assess the shear bond strength. Data were collected and statistically analyzed. RESULTS: The maximum mean shear bond strength was found in 8th-generation bonding agent (30.76 ± 0.16), followed by 7th-generation bonding agent (26.08 ± 0.21), 6th-generation bonding agent (25.32 ± 0.06), and control group (6.18 ± 0.09). Statistically significant difference was found between the three different bonding agents (p < 0.001). CONCLUSION: On conclusion, the 8th-generation bonding agent demonstrated a greater shear bond strength to dentin than the 7th and 6th-generation bonding agent. CLINICAL SIGNIFICANCE: The emergence of different bonding techniques to the market improves the durability and quality of restorations. An effective bonding to the tooth would also reduce bacterial penetration, marginal microleakage, possibility of pulpal inflammation preserve tooth structure, and postoperative sensitivity by allowing less cavity preparation. How to cite this article: Alqarni AS, Al Ghwainem A. Assessment of the Efficacy and Bond Strength of Different Dentin-bonding Agents with Adhesives on Primary Teeth: An In Vitro Study. J Contemp Dent Pract 2024;25(4):342-345.

Impact of Pericervical Dentin on Fracture Resistance of Endodontically Treated Posterior Permanent Teeth: A Systematic Review and Meta-analysis.

OBJECTIVE: The main aim of this present systematic review is to evaluate if the preservation of pericervical dentin (PCD) increases the fracture resistance of endodontically treated permanent posterior teeth. MATERIALS AND METHODS: Two independent reviewers conducted a comprehensive review of all published studies from 2007 (1/1/2007) to 2023 (31/5/23) since the concept of PCD first appeared in the literature in 2007. Searches were conducted in multiple electronic database engines: PubMed, Scopus, EBSCO (Dentistry and oral health sciences), Web of Sciences (WOS), Cochrane, Google Scholar and Open Grey, Ovid and Shodhganga, in addition to cross-references and hand search. Articles were chosen according to a certain inclusion and exclusion criteria, which, in brief, are laboratory-based studies published in English that assess the impact of PCD on fracture resistance of endodontically treated permanent posterior teeth. Using domains, such as sample size, sample dimensions, and control group as quality assessment criteria, evaluated the selected articles and classified them according to their risk of bias into low, moderate, and high. A meta-analysis was conducted using random effects modeling at a significance level of p < 0.05. RESULTS: A total of studies 6,043 were retrieved from 10 different electronic search databases and hand searches, but only 12 laboratory-based studies were selected after removing duplicates and applying the eligibility criteria. Of the included 12 studies, nine studies showed low risk of bias and three studies showed moderate risk of bias. Two studies showed related data for meta-analysis, the difference observed between the two studies is statistically non-significant. CONCLUSION: Based on the results of the study, there is evidence to support that PCD preservation offers fracture resistance to the endodontically treated posterior teeth. CLINICAL SIGNIFICANCE: The practice of conservative cavity preparation and avoiding the usage of instruments with high taper increases the fracture resistance of the tooth by retaining the PCD. How to cite this article: Haridoss S, Rajendran M, Swaminathan K, et al. Impact of Pericervical Dentin on Fracture Resistance of Endodontically Treated Posterior Permanent Teeth: A Systematic Review and Meta-analysis. J Contemp Dent Pract 2024;25(4):372-385.

Sandblasting increases the microtensile bond strength between resin and sclerotic dentin in noncarious cervical lesions.

PURPOSE: To evaluate the effect of sandblasting on the microtensile strength between sclerotic dentin and resin composite. METHODS: 32 premolars with noncarious cervical lesions (NCCLs) were collected, and the teeth were randomly assigned to the control group (C group) and the sandblasted group (S group). Teeth in the S group were sandblasted with 110 µm Al2O3 particles at a pressure of 75 psi, while those in the C group received no further treatment. The characteristics of the tooth surface were observed by scanning electron microscopy (SEM), and the relative area of open dentin tubules (OTs) was calculated by IPP6.0 software. Surface roughness (Ra) was also assessed. The noncarious cervical lesions of all teeth were restored with a resin composite and subsequently sectioned into sticks to measure the microtensile bond strength (µTBS). RESULTS: The mean ± SD µTBS (in MPa) of the sandblasted group was 17.9 ± 0.69 and 14.23 ± 0.44 in the control group (P< 0.05). The relative area of OTs at the gingival wall of the sandblasted group was 69.74 ± 5.23%, and 47.24 ± 7.67% in the control group (P< 0.05). The average surface roughness (µm) was 1.01 ± 0.05 in the sandblasted group and 0.16 ± 0.03 in the control group. Sandblasting could increase the bond strength of sclerotic dentin and resin restorations. CLINICAL SIGNIFICANCE: After sandblasting, the microtensile strength of sclerotic dentin on the surface of noncarious cervical lesions increased, prolonging the resin adhesion longevity. Sandblasting could also alleviate the pain of patients during the treatment process and achieve a minimally invasive treatment.

Ultrasonic activation of adhesive systems increases bond strength and intratubular penetration of resin cement in root dentin subjected to radiation therapy.

OBJECTIVE: This study aimed to evaluate the effect of ultrasonic activation of etch-and-rinse and self-etch adhesive systems on the bond strength of resin cement to irradiated root dentin. MATERIALS AND METHODS: Eighty human maxillary anterior teeth were distributed into 8 groups (n = 10), according to the type of adhesive system used (etch-and-rinse and self-etch), the ultrasonic activation of the adhesive systems, and the dentin condition (irradiated or non-irradiated - 70 Gy). Endodontic treatment was performed followed by fiberglass post-space preparation. After fiberglass posts' luting, the roots were transversely sectioned on dentin discs and submitted to the push-out bond strength test (0.5 mm/min). The fractured specimens were analyzed under a stereomicroscope and Scanning Electron Microscope (SEM) for failure mode classification. One of the dentin discs was analyzed under SEM to evaluate the characteristics of the adhesive interface. RESULTS: Irradiated specimens had lower bond strength than non-irradiated specimens (P < 0.0001). Ultrasonic activation of both adhesive systems increased the bond strength of the resin cement to irradiated dentin (P < 0.0001). Radiotherapy significantly affected the failure mode in the middle (P = 0.024) and apical thirds (P = 0.032) (adhesive failure). CONCLUSION: Non-irradiated specimens had a more homogeneous adhesive interface. When ultrasonically activated, both adhesive systems showed a greater number of resinous tags, regardless of the dentin condition. CLINICAL RELEVANCE: Ultrasonic activation of adhesive systems is a feasible strategy to enhance fiberglass posts retention in oncological patients.

Evergrowing incisors of diprotodont marsupials record age and life history.

OBJECTIVE: Tooth growth and wear are commonly used tools for determining the age of mammals. The most speciose order of marsupials, Diprotodontia, is characterised by a pair of procumbent incisors within the lower jaw. This study examines the growth and wear of these incisors to understand their relationship with age and sex. DESIGN: Measurements of mandibular incisor crown and root length were made for two sister species of macropodid (kangaroos and wallabies); Macropus giganteus and Macropus fuliginosus. Histological analysis examined patterns of dentine and cementum deposition within these teeth. Broader generalisability within Diprotodontia was tested using dentally reduced Tarsipes rostratus - a species disparate in body size and incisor function to the studied macropodids. RESULTS: In the macropodid sample it is demonstrated that the hypsodont nature of these incisors makes measurements of their growth (root length) and wear (crown length) accurate indicators of age and sex. Model fitting finds that root growth proceeds according to a logarithmic function across the lifespan, while crown wear follows a pattern of exponential reduction for both macropodid species. Histological results find that secondary dentine deposition and cementum layering are further indicators of age. Incisor measurements are shown to correlate with age in the sample of T. rostratus. CONCLUSIONS: The diprotodontian incisor is a useful tool for examining chronological age and sex, both morphologically and microstructurally. This finding has implications for population ecology, palaeontology and marsupial evolution.

Antimicrobial Efficacy and Dentin Collagen Damage Caused by Calcium Hypochlorite and Sodium Hypochlorite.

This study aimed to evaluate the antimicrobial activity of calcium hypochlorite (Ca (OCl)2) and sodium hypochlorite (NaOCl) using confocal laser scanning microscopy (CLSM) and dentin organic matrix alteration by picrosirius staining and light microscopy (LM). Samples of human extracted teeth were infected with Enterococcus faecalis by centrifugation of the bacterial suspension and were treated with Ca(OCl)2 or NaOCl at 0.5%, 2.5%, and 6% for 15, 30, and 60 seconds. CLSM and viability staining were used to quantitatively analyze the proportions of dead/live bacteria in the canal lumen and border of the root canal. The data were analyzed by ANOVA and Fisher test. For LM analysis, one hundred bovine teeth were randomly divided into 10 test groups (n=10): G1- Without treatment; G2- 17% EDTA; G3- 6% NaOCl; G4- 6% NaOCl + EDTA; G5- 0.5% Ca(OCl)2; G6- 0.5% Ca(OCl)2 + EDTA; G7- 2.5% Ca(OCl)2; G8- 2.5% Ca(OCl)2 + EDTA; G9- 6% Ca(OCl)2; G10- 6% Ca(OCl)2 + EDTA. The samples were fragmented and stained with Picrosirius. Data were analyzed by Kruskal-Wallis and Dunn (P<0.05). There was a strong correlation between the results of the canal lumen and the border of the root canal (r=0.962). Both hypochlorites at a concentration of 0.5% showed less microbial reduction compared to 2.5% and 6% (P<0.05). There was less antimicrobial activity at 15 seconds compared to 30 and 60 seconds (P<0.05). Ca(OCl)2 and NaOCl showed similar results at the same concentrations (P>0.05). In conclusion, Ca(OCl)2 caused fewer alterations to the dentin organic matrix at concentrations of 0.5% and 2.5%. Ca(OCl)2 presents antimicrobial activity similar to NaOCl, and collagen damage is concentration-dependent.

Comparison of remineralization ability of tricalcium silicate and of glass ionomer cement on residual dentin: an in vitro study.

OBJECTIVE: This study aimed to compare the remineralization effects of a calcium silicate-based cement (Biodentine) and of a glass ionomer cement (GIC: Fuji IX) on artificially demineralized dentin. METHODS: Four standard cavities were prepared in dentin discs prepared from 34 extracted sound human third molars. In each disc, one cavity was covered with an acid-resistant varnish before demineralization (Group 1). The specimens were soaked in a chemical demineralization solution for 96 h to induce artificial carious lesions. Thereafter, one cavity each was filled with Biodentine (Group 2) and GIC (Group 3), respectively, and one carious lesion was left unrestored as a negative control (Group 4). Next, specimens were immersed in simulated body fluid (SBF) for 21 days. After cross-sectioning the specimens, the Ca/P ratio was calculated in each specimen by using scanning electron microscopy-energy-dispersive X-ray spectroscopy (SEM-EDX). Finally, data were analyzed using repeated-measures ANOVA with post-hoc Bonferroni correction. RESULTS: Both cement types induced dentin remineralization as compared to Group 4. The Ca/P ratio was significantly higher in Group 2 than in Group 3 (p < 0.05). CONCLUSION: The dentin lesion remineralization capability of Biodentine is higher than that of GIC, suggesting the usefulness of the former as a bioactive dentin replacement material. CLINICAL RELEVANCE: Biodentine has a higher remineralization ability than that of GIC for carious dentin, and its interfacial properties make it a promising bioactive dentin restorative material.

Effect of mineralized dentin matrix on the prognosis of bone defect and retained root after coronectomy.

OBJECTIVE: To investigate the impact of mineralized dentin matrix (MDM) on the prognosis on bone regeneration and migration of retained roots after coronectomy. MATERIALS AND METHODS: Patients were divided into three groups based on the type of bone graft after coronectomy: Group C (n = 20, collagen), Group T (n = 20, tricalcium phosphate (TCP) + collagen), and Group D (n = 20, MDM + collagen). CBCT scans, conducted immediately and 6 months after surgery, were analyzed using digital software. Primary outcomes, including changes in bone defect depth and retained root migration distance, were evaluated 6 months after surgery. RESULTS: After 6 months, both Groups D and T exhibited greater reduction of the bone defect and lesser retained root migration than Group C (p < 0.001). Group D had greater regenerated bone volume in the distal 2 mm (73 mm3 vs. 57 mm3, p = 0.011) and lesser root migration (2.18 mm vs. 2.96 mm, p < 0.001) than Group T. The proportion of completely bone embedded retained roots was also greater in Group D than in Group C (70.0% vs. 42.1%, p = 0.003). CONCLUSIONS: MDM is an appropriate graft material for improving bone defect healing and reducing retained root migration after coronectomy. CLINICAL RELEVANCE: MDM is an autogenous material prepared chairside, which can significantly improve bone healing and reduce the risk of retained root re-eruption. MDM holds promise as a routine bone substitute material after M3M coronectomy.

Dual- or single rinse? The tubular sealer penetration of endodontic chelating agents.

INTRODUCTION: In this study, we aimed to compare the effectiveness of various chelating agents, ethilenediaminetetraacetic acid (EDTA), citric acid (CA), and etidronic acid (HEDP) mixed in two different forms, in removing the smear layer and promoting the penetration of an endodontic sealer into the dentinal tubules of extracted single-rooted teeth. METHODS: The study used 75 teeth divided into five groups: 17% EDTA, 10% CA, 9% HEDP + NaOCl, 9% HEDP + distilled water (DW), and a control (DW) group. Scanning electron microscopy was used to assess smear layer removal and confocal laser microscopy was used to evaluate tubular sealer penetration at different depths from the apical tip. RESULTS: Sealer penetration was highest with 17% EDTA and 10% CA as compared with the other agents (p<0.001). At the cervical third, the sealer penetration for EDTA, HEDP + NaOCl, and HEDP + DW groups were significantly different than those in DW (p = 0.020). For the middle third, EDTA, CA, and HEDP + NaOCl groups were significantly higher than those of the DW group (p<0.001). Cervical-level values were significantly higher than apical-level values for HEDP + NaOCl, HEDP + DW, and DW (p<0.001). Smear layer removal was lower with 9% HEDP + DW than with 17% EDTA and 10% CA at all depths (p<0.001). A significancy in smear layer removal was observed between 10% CA and control (p = 0.015) in middle depth. CONCLUSION: Within the limitations of this study, highest values were seen in EDTA and CA in terms of sealer penetration and smear layer removal. In the light of these findings, the use of strong chelating agents highlights better clinical efficiency than dual-rinse or single HEDP irrigation.

Fatigue and failure mode analyses of glass infiltrated 5Y-PSZ bonded onto dentin analogues.

The purpose of this study was to evaluate the fatigue survival of 5Y-PSZ zirconia infiltrated with an experimental glass and bonded onto dentin analogues. Disc-shaped specimens of a 5Y-PSZ (Katana UTML Kuraray Noritake) were cemented onto dentin analogs (NEMA G10) and divided into four groups (n = 15): Zctrl Group (control, without infiltration); Zglz Group (Glaze, compression surface); Zinf-comp Group (Experimental Glass, compression surface); Zinf-tens Group (Experimental Glass, tension surface). Surface treatments were varied. Cyclic fatigue loading, oblique transillumination, stereomicroscope examination, and scanning electron microscopy were performed. Fatigue data were analyzed (failure load and number of cycles) using survival analysis (Kaplan-Meier and Log-Rank Mantel-Cox). There was no statistically significant difference in fatigue survival between the Zglz, Zctrl, and Zinf-comp groups. The Zinf-tens group presented a significantly higher failure load when compared to the other groups and exhibited a different failure mode. The experimental glass effectively infiltrated the zirconia, enhancing structural reliability, altering the failure mode, and improving load-bearing capacity over more cycles, particularly in the group where the glass was infiltrated into the tensile surface of the zirconia. Glass infiltration into 5Y-PSZ zirconia significantly enhanced structural reliability and the ability to withstand loads over an increased number of cycles. This approach has the potential to increase the durability of zirconia restorations, reducing the need for replacements and save time and resources, promoting efficiency in clinical practice.

Does dynamic navigation system preserve more dentine? - A systematic review.

OBJECTIVE: This systematic review aims to comparatively analyse the amount of dentin removal by free hand and static guided endodontics with dynamic navigation system (DNS) in endodontic access cavity preparation. METHODS: The systematic review was conducted according to Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) 2020 guidelines. Based on the structured PICO framework of "Comparative evaluation of dynamic navigation system (I) to freehand (C) and static guided endodontics (C) in endodontic access cavity preparation on the preservation of tooth structure (O) when assessed on permanent human teeth (P)", the keywords were formulated and the articles were retrieved from three databases namely PubMed, Scopus and Embase, based on the keywords from the time of inception of DNS till June 2023. The risk of bias assessment was done using a modified Joanne Briggs Institute checklist, which evaluated domains such as randomisation, sample size, image acquisition using CBCT, angulation, accuracy and time taken. As the data was heterogenous, a quantitative meta-analysis was not performed. RESULTS: Initially, 174 articles were retrieved from the three databases, 30 duplicates were removed, after title check 108 articles were excluded and following abstract check only 10 articles qualified for full text analysis. On reviewing the 10 full text articles, 5 articles were excluded and the remaining 5 articles were subjected to the risk of bias analysis which showed that 2 articles displayed low risk of bias and three articles showed high risk of bias. The RoB analysis revealed that only 2 studies evaluated the preservation of dentin in terms of accuracy, angulation and time taken proving the increased precision with minimal loss of tooth structure using DNS. In both the studies, DNS proved to be superior to free hand technique in terms of precision, accuracy and efficiency in locating the canals during access cavity preparation with maximal preservation of tooth structure. CONCLUSION: With the minimal literature evidences, the present systematic review highlights maximal preservation of dentin using DNS. However, further invitro and invivo studies comparing the free hand, static guided endodontics to DNS must be carried out for its translation into clinical practice. CLINICAL SIGNIFICANCE: Dynamic navigation system provides maximal preservation of dentin during access cavity preparation.