Methylmercury exposure of the sponge O. lobularis induces strong tissue and cell defects.

Mediterranean marine biota suffers from various anthropogenic threats. Among them, pollutants such as mercury (Hg) represent important environmental issues that are exacerbated by bioaccumulation and bioamplification along food webs via its organic form, monomethylmercury (MMHg). To date, very little is known regarding the impact of mercury on Porifera and the few available studies have been exclusively focused on Demospongiae. This work studies the effect of MMHgCl at different biological levels of Oscarella lobularis (Porifera, Homoscleromorpha). Bioaccumulation assays show that MMHgCl significantly accumulated in sponge tissues after a 96-h exposure to 0.1 µg L-1. Toxicity assays (LC5096h) show a sensibility that depends on life-stage (adult vs bud). Additionally, we show that the exposure to 1 µg L-1 MMHgCl negatively impacts the epithelial integrity and the regeneration process in buds, as shown by the loss of cell-cell contacts and the alteration of osculum morphogenesis. For the first time in a sponge, a whole set of genes classically involved in metal detoxification and in antioxidant response were identified. Significant changes in catalase, superoxide dismutase and nuclear factor (erythroid-derived 2)-like 2 expressions in exposed juveniles were measured. Such an integrative approach from the physiological to the molecular scales on a non-model organism expands our knowledge concerning sensitivity and toxicity mechanisms induced by MMHg in Porifera, raising new questions regarding the possible defences used by marine sponges.

Hyper-accumulation of vanadium in animals: Two sponges compete with urochordates.

Vanadium (V) concentrations in organisms are usually very low. To date, among animals, only some urochordate and annelid species contain very high levels of V in their tissues. A new case of hyper-accumulation of V in a distinct animal phylum (Porifera), namely, the two homoscleromorph sponge species Oscarella lobularis and O. tuberculata is reported. The measured concentrations (up to 30 g/kg dry weight) exceed those reported previously and are not found in all sponge classes. In both Oscarella species, V is mainly accumulated in the surface tissues, and in mesohylar cells, as V(IV), before being partly reduced to V(III) in the deeper tissues. Candidate genes from Bacteria and sponges have been identified as possibly being involved in the metabolism of V. This finding provides clues for the development of bioremediation strategies in marine ecosystems and/or bioinspired processes to recycle this critical metal.

The Effectiveness of the Addition of Platelet-Rich Fibrin to Bovine Xenografts in Sinus and Bone Ridge Augmentation: A Systematic Review.

Dental implants sometimes need bone augmentation to recreate an adequate bone height and volume. Numerous bone augmentation techniques have been described, and, currently, the most commonly used bone graft procedure is xenografts with deproteinized bovine bone mineral (DBBM). The addition of platelet-rich fibrin (PRF) to DBBM has already shown better performance than DBBM alone in restoring intrabony periodontal defects, but the role of PRF in preimplantation bone grafts is still not clear. The objective of this systematic review was to evaluate the efficacy of the adjunction of PRF or L-PRF to DBBM in bone ridge augmentation procedures. Clinical randomized controlled studies using PRF associated with DBBM were included. In April 2023, three electronic databases (PubMed, Cochrane, and Web of Science) were searched. The search strategy was performed according to PRISMA guidelines. The risk of bias assessments were performed using the Cochrane Collaboration tool. A total of seven articles were included and analyzed. The results show no statistically significant effect of PRF added to DBBM compared to DBBM alone in the sinus lift procedure but do show an effect in the reduction in bone graft resorption in one study of mandibular guided bone regeneration.

The compact genome of the sponge Oopsacas minuta (Hexactinellida) is lacking key metazoan core genes.

BACKGROUND: Explaining the emergence of the hallmarks of bilaterians is a central focus of evolutionary developmental biology-evodevo-and evolutionary genomics. For this purpose, we must both expand and also refine our knowledge of non-bilaterian genomes, especially by studying early branching animals, in particular those in the metazoan phylum Porifera. RESULTS: We present a comprehensive analysis of the first whole genome of a glass sponge, Oopsacas minuta, a member of the Hexactinellida. Studying this class of sponge is evolutionary relevant because it differs from the three other Porifera classes in terms of development, tissue organization, ecology, and physiology. Although O. minuta does not exhibit drastic body simplifications, its genome is among the smallest of animal genomes sequenced so far, and surprisingly lacks several metazoan core genes (including Wnt and several key transcription factors). Our study also provides the complete genome of a symbiotic Archaea dominating the associated microbial community: a new Thaumarchaeota species. CONCLUSIONS: The genome of the glass sponge O. minuta differs from all other available sponge genomes by its compactness and smaller number of encoded proteins. The unexpected loss of numerous genes previously considered ancestral and pivotal for metazoan morphogenetic processes most likely reflects the peculiar syncytial tissue organization in this group. Our work further documents the importance of convergence during animal evolution, with multiple convergent evolution of septate-like junctions, electrical-signaling and multiciliated cells in metazoans.

The Effectiveness of Calcium Phosphates in the Treatment of Dentinal Hypersensitivity: A Systematic Review.

Dentin hypersensitivity (DH) pain is a persistent clinical problem, which is a common condition known to affect patients' quality of life (QoL), but no treatment has ever been agreed upon. Calcium phosphates, available in different forms, have properties that allow sealing the dentinal tubules, which may relieve dentin hypersensitivity. The aim of this systematic review is to evaluate the ability of different formulations of calcium phosphate to reduce dentin hypersensitivity pain level in clinical studies. The inclusion criterion was as follows: clinical randomized controlled studies using calcium phosphates in treating dentin hypersensitivity. In December 2022, three electronic databases (Pubmed, Cochrane and Embase) were searched. The search strategy was performed according to Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines. The bias assessment risks results were carried out using the Cochrane Collaboration tool. A total of 20 articles were included and analyzed in this systematic review. The results show that calcium phosphates have properties that reduce DH-associated pain. Data compilation showed a statistically significant difference in DH pain level between T0 and 4 weeks. This VAS level reduction is estimated at about -2.5 compared to the initial level. The biomimetic and non-toxic characteristics of these materials make them a major asset in treating dentin hypersensitivity.

The sponge Oscarella lobularis (Porifera, Homoscleromorpha) as a suitable biomonitor of metallic contamination in Mediterranean coastal ecosystems.

The biomonitoring of metallic contamination in marine ecosystems is often focused on animal species of commercial interest and in lesser extent on non-model marine invertebrates. The aim of this study was to compare the metal concentrations (Li, Al, Ti, Cr, Fe, Ni, Cu, Zn, As, Ag, Cd, Hg, Pb) in seven marine sponges with a particular interest in the homoscleromorph sponge Oscarella lobularis at different sites of the Bay of Marseille, France. Inter-species variabilities suggest that the seven sponge species studied accumulate metals differently. In O. lobularis, a multi-site analysis shows different bioaccumulation between the eight sampled populations. These inter-site differences may reflect differences in the hydrodynamic features and in past and present industrial activities. Because Oscarella lobularis shows a homogeneous metal accumulation pattern in comparison with the other tested species, it appears to be suitable for metal contamination biomonitoring in Mediterranean coastal waters, in particular of the coralligenous communities.

Current Data on Oral Peri-Implant and Periodontal Microbiota and Its Pathological Changes: A Systematic Review.

The 5- and 10-year implant success rates in dentistry are nearly 90%. Prevalence of peri-implant diseases is 10% for peri-implantitis and 50% for peri-implant mucositis. To better understand these inflammatory pathologies of infectious origin, it is important to know if the composition of the peri-implant microbiota is comparable with the periodontal microbiota in healthy and pathological conditions. New generation sequencing (NGS) is a recent metagenomic method that analyzes the overall microorganisms present in an ecological niche by exploiting their genome. These methods are of two types: 16S rRNA sequencing and the shotgun technique. For several years, they have been used to explore the oral, periodontal, and, more specifically, peri-implant microbiota. The aim of this systematic review is to analyze the recent results of these new explorations by comparing the periodontal and peri-implant microbiota in patients with healthy and diseased sites and to explore the microbiological characteristics of peri-implantitis. A better knowledge of the composition of the peri-implant microbiota would enable us to optimize our therapeutic strategies. An electronic systematic search was performed using the medical databases PubMed/Medline, Cochrane Library, and ScienceDirect, and Periodontology 2000. The selected articles were published between January 2015 and March 2021. Inclusion criteria included clinical studies comparing healthy and pathological periodontal and peri-implant microbiota exclusively using 16S rRNA sequencing or shotgun sequencing, with enrolled populations free of systemic pathology, and studies without substantial bias. Eight articles were selected and reviewed. All of them used 16S rRNA sequencing exclusively. The assessment of these articles demonstrates the specific character of the peri-implant microbiota in comparison with the periodontal microbiota in healthy and pathological conditions. Indeed, peri-implant diseases are defined by dysbiotic bacterial communities that vary from one individual to another, including known periodontopathogens such as Porphyromonas gingivalis (P.g.) and genera less mentioned in the periodontal disease pattern such as Filifactor alocis. Examination of peri-implant microbiota with 16S rRNA sequencing reveals differences between the periodontal and peri-implant microbiota under healthy and pathological conditions in terms of diversity and composition. The pattern of dysbiotic drift is preserved in periodontal and peri-implant diseases, but when comparing the different types of pathological sites, the peri-implant microbiota has a specificity in the presence of bacteria proper to peri-implantitis and different relative proportions of the microorganisms present.

Modulators of Wnt Signaling Pathway Implied in Dentin Pulp Complex Engineering: A Literature Review.

The main goal of vital pulp therapy (VPT) is to preserve the vitality of the pulp tissue, even when it is exposed due to bacterial invasion, iatrogenic mechanical preparation, or trauma. The type of new dentin formed as a result of VPT can differ in its cellular origin, its microstructure, and its barrier function. It is generally agreed that the new dentin produced by odontoblasts (reactionary dentin) has a tubular structure, while the dentin produced by pulp cells (reparative dentin) does not or has less. Thus, even VPT aims to maintain the vitality of the pulp. It does not regenerate the dentin pulp complex integrity. Therefore, many studies have sought to identify new therapeutic strategies to successfully regenerate the dentin pulp complex. Among them is a Wnt protein-based strategy based on the fact that Wnt proteins seem to be powerful stem cell factors that allow control of the self-renewal and proliferation of multiple adult stem cell populations, suitable for homeostasis maintenance, tissue healing, and regeneration promotion. Thus, this review outlines the different agents targeting the Wnt signaling that could be applied in a tooth environment, and could be a potential therapy for dentin pulp complex and bone regeneration.

Evolution of mechanisms controlling epithelial morphogenesis across animals: new insights from dissociation-reaggregation experiments in the sponge Oscarella lobularis.

BACKGROUND: The ancestral presence of epithelia in Metazoa is no longer debated. Porifera seem to be one of the best candidates to be the sister group to all other Metazoa. This makes them a key taxon to explore cell-adhesion evolution on animals. For this reason, several transcriptomic, genomic, histological, physiological and biochemical studies focused on sponge epithelia. Nevertheless, the complete and precise protein composition of cell-cell junctions and mechanisms that regulate epithelial morphogenetic processes still remain at the center of attention. RESULTS: To get insights into the early evolution of epithelial morphogenesis, we focused on morphogenic characteristics of the homoscleromorph sponge Oscarella lobularis. Homoscleromorpha are a sponge class with a typical basement membrane and adhaerens-like junctions unknown in other sponge classes. We took advantage of the dynamic context provided by cell dissociation-reaggregation experiments to explore morphogenetic processes in epithelial cells in a non-bilaterian lineage by combining fluorescent and electron microscopy observations and RNA sequencing approaches at key time-points of the dissociation and reaggregation processes. CONCLUSIONS: Our results show that part of the molecular toolkit involved in the loss and restoration of epithelial features such as cell-cell and cell-matrix adhesion is conserved between Homoscleromorpha and Bilateria, suggesting their common role in the last common ancestor of animals. In addition, sponge-specific genes are differently expressed during the dissociation and reaggregation processes, calling for future functional characterization of these genes.

Evaluation of Pulp Repair after BiodentineTM Full Pulpotomy in a Rat Molar Model of Pulpitis.

Dental pulp is a dynamic tissue able to heal after injury under moderate inflammatory conditions. Our study aimed to evaluate pulp repair under inflammatory conditions in rats. For this purpose, we developed a rat model of controlled pulpitis followed by pulpotomy with a tricalcium silicate-based cement. Fifty-four cavities were prepared on the occlusal face of the maxillary upper first molar of 27 eight-week-old male rats. E. coli lipopolysaccharides at 10 mg/mL or phosphate-buffered saline PBS was injected after pulp injury. Non-inflamed molars were used as controls. Levels of inflammation-related molecules were measured 6 and 24 h after induction by enzyme-linked immunosorbent assay of coronal pulp samples. Pulp capping and coronal obturation after pulpotomy were performed with tricalcium silicate-based cement. Four and fifteen days after pulpotomy, histological and immunohistochemical analysis was performed to assess pulp inflammation and repair processes. Our results showed significantly higher levels of innate inflammatory proteins (IL-1ß, IL-6, TNF-α and CXCL-1) compared with those in controls. Moderate residual inflammation near the capping material was demonstrated by histology and immunohistochemistry, with the presence of few CD68-positive cells. We showed that, in this model of controlled pulpitis, pulpotomy with BiodentineTM allowed the synthesis at the injury site of a mineralized bridge formed from mineralized tissue secreted by cells displaying odontoblastic characteristics. Analysis of these data suggests overall that, with the limitations inherent to findings in animal models, pulpotomy with a silicate-based cement is a good treatment for controlling inflammation and enhancing repair in cases of controlled pulpitis.

Staining and Tracking Methods for Studying Sponge Cell Dynamics.

To better understand the origin of animal cell types, body plans, and other morphological features, further biological knowledge and understanding are needed from non-bilaterian phyla, namely, Placozoa, Ctenophora, and Porifera. This chapter describes recent cell staining approaches that have been developed in three phylogenetically distinct sponge species-the homoscleromorph Oscarella lobularis, and the demosponges Amphimedon queenslandica and Lycopodina hypogea-to enable analyses of cell death, proliferation, and migration. These methods allow for a more detailed understanding of cellular behaviors and fates, and morphogenetic processes in poriferans, building on current knowledge of sponge cell biology that relies chiefly on classical (static) histological observations.

In Situ Hybridization Techniques in the Homoscleromorph Sponge Oscarella lobularis.

The Porifera are one of the best candidates as the sister group to all other metazoans. Studies on this phylum are therefore expected to shed light on the origin and early evolution of key animal features. Transcriptomic or genomic data acquired during the last 10 years have highlighted the conservation of most of the main genes and pathways involved in the development of the other metazoans. The next step is to determine how similar genetic tool boxes can result in widely dissimilar body plan organization, dynamics, and life histories. To answer these questions, three main axes of research are necessary: (1) conducting more gene expression studies; (2) developing knockdown protocols; and (3) reinterpreting sponge cell biology using modern tools. In this chapter we focus on the in situ hybridization (ISH) technique, needed to establish the spatiotemporal expression of genes, both on whole mount individuals and paraffin sections, and at different stages of development (adults, embryos, larvae, buds) of the homoscleromorph sponge Oscarella lobularis.

Post-operative discomforts in children after extraction of primary teeth.

OBJECTIVES: This prospective observational study aimed to evaluate discomfort after extraction of deciduous teeth under local anesthesia. The primary objective was to describe the prevalence of post-extraction pain (PEP), post-extraction bleeding (PEB), post-extraction biting injury (PEBI), and analgesic usage in children. The secondary objective was to define whether it is possible to determine a profile of patients or a type of extraction procedure predictive to PEP, administration of analgesics, PEB, or PEBI. METHODS: One hundred and twenty-five children, aged 3-13 years, with indications of at least one deciduous tooth extraction, were included. Immediately after extraction, information concerning the patient and the extraction were collected. Eighteen to 32 hr after extraction, parents were called by phone to request reports concerning the onset and intensity of PEP assessed using the Wong-Baker Faces (WBF) scale, the administration of paracetamol (acetaminophen) to their children, and the appearance of PEB and/or PEBI. RESULTS: Of the children, 37.3% reported PEP (WBF ≥2), but 23.3% of these children did not receive any analgesic drugs to help relieve pain. Pain appeared before 3 hr after extraction in 69% of the children. Higher incidences of PEP and usage of analgesics were found both in the group of children with unfavorable socioeconomic level compared to favorable level and in the group with pre-operative pain compared to no pre-operative pain (p < .05). CONCLUSIONS: About a third of the children reported pain after extraction, but the instructions for pain relief were not followed by all parents. The socioeconomic level of the young patient and the pain felt during the extraction were important predictors of discomfort. Therefore, our study could help the dentist to provide information on predicted post-operative discomfort and to allow suitable care depending on the patient's profile or procedure.

Understanding Animal Evolution: The Added Value of Sponge Transcriptomics and Genomics: The disconnect between gene content and body plan evolution.

Sponges are important but often-neglected organisms. The absence of classical animal traits (nerves, digestive tract, and muscles) makes sponges challenging for non-specialists to work with and has delayed getting high quality genomic data compared to other invertebrates. Yet analyses of sponge genomes and transcriptomes currently available have radically changed our understanding of animal evolution. Sponges are of prime evolutionary importance as one of the best candidates to form the sister group of all other animals, and genomic data are essential to understand the mechanisms that control animal evolution and diversity. Here we review the most significant outcomes of current genomic and transcriptomic analyses of sponges, and discuss limitations and future directions of sponge transcriptomic and genomic studies.

New genomic data and analyses challenge the traditional vision of animal epithelium evolution.

BACKGROUND: The emergence of epithelia was the foundation of metazoan expansion. Epithelial tissues are a hallmark of metazoans deeply rooted in the evolution of their complex developmental morphogenesis processes. However, studies on the epithelial features of non-bilaterians are still sparse and it remains unclear whether the last common metazoan ancestor possessed a fully functional epithelial toolkit or if it was acquired later during metazoan evolution. RESULTS: To investigate the early evolution of animal epithelia, we sequenced the genome and transcriptomes of two new sponge species to characterize epithelial markers such as the E-cadherin complex and the polarity complexes for all classes (Calcarea, Demospongiae, Hexactinellida, Homoscleromorpha) of sponges (phylum Porifera) and compare them with their homologues in Placozoa and in Ctenophora. We found that Placozoa and most sponges possess orthologues of all essential genes encoding proteins characteristic of bilaterian epithelial cells, as well as their conserved interaction domains. In stark contrast, we found that ctenophores lack several major polarity complex components such as the Crumbs complex and Scribble. Furthermore, the E-cadherin ctenophore orthologue exhibits a divergent cytoplasmic domain making it unlikely to interact with its canonical cytoplasmic partners. CONCLUSIONS: These unexpected findings challenge the current evolutionary paradigm on the emergence of epithelia. Altogether, our results raise doubt on the homology of protein complexes and structures involved in cell polarity and adhesive-type junctions between Ctenophora and Bilateria epithelia.

Animal multicellularity and polarity without Wnt signaling.

Acquisition of multicellularity is a central event in the evolution of Eukaryota. Strikingly, animal multicellularity coincides with the emergence of three intercellular communication pathways - Notch, TGF-ß and Wnt - all considered as hallmarks of metazoan development. By investigating Oopsacas minuta and Aphrocallistes vastus, we show here that the emergence of a syncytium and plugged junctions in glass sponges coincides with the loss of essential components of the Wnt signaling (i.e. Wntless, Wnt ligands and Disheveled), whereas core components of the TGF-ß and Notch modules appear unaffected. This suggests that Wnt signaling is not essential for cell differentiation, polarity and morphogenesis in glass sponges. Beyond providing a comparative study of key developmental toolkits, we define here the first case of a metazoan phylum that maintained a level of complexity similar to its relatives despite molecular degeneration of Wnt pathways.

The Conservation of the Germline Multipotency Program, from Sponges to Vertebrates: A Stepping Stone to Understanding the Somatic and Germline Origins.

The germline definition in metazoans was first based on few bilaterian models. As a result, gene function interpretations were often based on phenotypes observed in those models and led to the definition of a set of genes, considered as specific of the germline, named the "germline core". However, some of these genes were shown to also be involved in somatic stem cells, thus leading to the notion of germline multipotency program (GMP). Because Porifera and Ctenophora are currently the best candidates to be the sister-group to all other animals, the comparative analysis of gene contents and functions between these phyla, Cnidaria and Bilateria is expected to provide clues on early animal evolution and on the links between somatic and germ lineages. Our present bioinformatic analyses at the metazoan scale show that a set of 18 GMP genes was already present in the last common ancestor of metazoans and indicate more precisely the evolution of some of them in the animal lineage. The expression patterns and levels of 11 of these genes in the homoscleromorph sponge Oscarella lobularis show that they are expressed throughout their life cycle, in pluri/multipotent progenitors, during gametogenesis, embryogenesis and during wound healing. This new study in a nonbilaterian species reinforces the hypothesis of an ancestral multipotency program.

Retracing the path of planar cell polarity.

BACKGROUND: The Planar Cell Polarity pathway (PCP) has been described as the main feature involved in patterning cell orientation in bilaterian tissues. Recently, a similar phenomenon was revealed in cnidarians, in which the inhibition of this pathway results in the absence of cilia orientation in larvae, consequently proving the functional conservation of PCP signaling between Cnidaria and Bilateria. Nevertheless, despite the growing accumulation of databases concerning basal lineages of metazoans, very few information concerning the existence of PCP components have been gathered outside of Bilateria and Cnidaria. Thus, the origin of this module or its prevalence in early emerging metazoans has yet to be elucidated. RESULTS: The present study addresses this question by investigating the genomes and transcriptomes from all poriferan lineages in addition to Trichoplax (Placozoa) and Mnemiopsis (Ctenophora) genomes for the presence of the core components of this pathway. Our results confirm that several PCP components are metazoan innovations. In addition, we show that all members of the PCP pathway, including a bona fide Strabismus ortholog (Van gogh), are retrieved only in one sponge lineage (Homoscleromorpha) out of four. This highly suggests that the full PCP pathway dates back at least to the emergence of homoscleromorph sponges. Consequently, several secondary gene losses would have occurred in the three other poriferan lineages including Amphimedon queenslandica (Demospongiae). Several proteins were not retrieved either in placozoans or ctenophores leading us to discuss the difficulties to predict orthologous proteins in basally branching animals. Finally, we reveal how the study of multigene families may be helpful to unravel the relationships at the base of the metazoan tree. CONCLUSION: The PCP pathway antedates the radiation of Porifera and may have arisen in the last common ancestor of animals. Oscarella species now appear as key organisms to understand the ancestral function of PCP signaling and its potential links with Wnt pathways.

ROCK inhibition abolishes the establishment of the aquiferous system in Ephydatia muelleri (Porifera, Demospongiae).

The Rho associated coiled-coil protein kinase (ROCK) plays crucial roles in development across bilaterian animals. The fact that the Rho/Rock pathway is required to initiate epithelial morphogenesis and thus to establish body plans in bilaterians makes this conserved signaling pathway key for studying the molecular mechanisms that may control early development of basally branching metazoans. The purpose of this study was to evaluate whether or not the main components of this signaling pathway exist in sponges, and if present, to investigate the possible role of the regulatory network in an early branching non-bilaterian species by evaluating ROCK function during Ephydatia muelleri development. Molecular phylogenetic analyses and protein domain predictions revealed the existence of Rho/Rock components in all studied poriferan lineages. Binding assays revealed that both Y-27632 and GSK429286A are capable of inhibiting Em-ROCK activity in vitro. Treatment with both drugs leads to impairment of growth and formation of the basal pinacoderm layer in the developing sponge. Furthermore, inhibition of Em-Rock prevents the establishment of a functional aquiferous system, including the absence of an osculum. In contrast, no effect of ROCK inhibition was observed in juvenile sponges that already possess a fully developed and functional aquiferous system. Thus, the Rho/Rock pathway appears to be essential for the proper development of the freshwater sponge, and may play a role in various cell behaviors (e.g. cell proliferation, cell adhesion and cell motility). Taken together, these data are consistent with an ancestral function of Rho/Rock signaling in playing roles in early developmental processes and may provide a new framework to study the interaction between Wnt signaling and the Rho/Rock pathway.

Dental Pulp Defence and Repair Mechanisms in Dental Caries.

Dental caries is a chronic infectious disease resulting from the penetration of oral bacteria into the enamel and dentin. Microorganisms subsequently trigger inflammatory responses in the dental pulp. These events can lead to pulp healing if the infection is not too severe following the removal of diseased enamel and dentin tissues and clinical restoration of the tooth. However, chronic inflammation often persists in the pulp despite treatment, inducing permanent loss of normal tissue and reducing innate repair capacities. For complete tooth healing the formation of a reactionary/reparative dentin barrier to distance and protect the pulp from infectious agents and restorative materials is required. Clinical and in vitro experimental data clearly indicate that dentin barrier formation only occurs when pulp inflammation and infection are minimised, thus enabling reestablishment of tissue homeostasis and health. Therefore, promoting the resolution of pulp inflammation may provide a valuable therapeutic opportunity to ensure the sustainability of dental treatments. This paper focusses on key cellular and molecular mechanisms involved in pulp responses to bacteria and in the pulpal transition between caries-induced inflammation and dentinogenic-based repair. We report, using selected examples, different strategies potentially used by odontoblasts and specialized immune cells to combat dentin-invading bacteria in vivo.