Oral Health of Rural Cameroonian Children: A Pilot Study in Bamendou.

Access to dental care in Cameroon is a public health issue, particularly for children living in rural areas. Given the lack of recent data, the investigation of children's oral health along with their oral hygiene behavior, needs in terms of care, and access to oral hygiene materials were investigated. This cross-sectional pilot study was conducted in Bamendou, Western Region of Cameroon. The study population included 265 children aged 3-18 years who completed a questionnaire about their oral hygiene practices. A clinical examination assessed dental caries, calculus, gingivitis, and oral hygiene. The Chi-squared test was used to identify potential factors influencing caries prevalence rates (significance threshold: p < 0.05). Among the 265 children (females: 41.5%, mean age 9.3 years), caries prevalence (ICDAS ≥ 2) was 78.5% and significantly increased with age: 62.2% (3-6 years), 80.9% (7-11 years) and 84.1% (12-18 years, p = 0.01). Virtually no children (95.1%) had ever visited a dentist. While only 23.4% of children brushed their teeth at least twice a day, 14% worryingly reported the use of products other than toothpaste (ash, soap, salt, or bicarbonate) and 13.6% no brushing product. The present study revealed a high prevalence of dental caries in this population and inadequate toothbrushing habits, which highlights the need for preventive oral health education and intervention to address these issues.

Assessment of guide fitting using an intra-oral scanner: An in vitro study.

OBJECTIVES: The aim of this study was to evaluate the capacity of an intra-oral scanner (IOS) to assess the position of an endodontic guide in vitro. METHODS: Fourteen extracted human teeth were placed into a maxillary model and scanned using computed tomography and a reference laboratory scanner. An ideal endodontic guide was then created and modified by adding defects of different thicknesses to simulate incorrect positions: 50 µm, 150 µm, 400 µm, and 1000 µm. For each thickness, guides were printed three times and each guide was scanned by three experimented operators using a Trios 4 IOS (3Shape, Copenhagen, Denmark). The 36 scans were compared using a best-fit alignment to the master model without defect to define the accuracy of the method and the positioning error. RESULTS: The IOS presented a mean trueness of 1.28 µm (SD= 12.70) and a mean precision of 11.52 µm (SD= 62.17). Considering all sizes of defect, the mean measured position of the endodontic guide was highly correlated (R>0.99) with the expected position. Compared to the ideal guide, there was a mean linear deviation of 46.11 µm (SD= 23.21) and a mean angular deviation of 5.9° (SD= 1.2); this deviation was not influenced by the operator. CONCLUSION: The present study found that an IOS had good performance to detect a positioning error of the endodontic guide in vitro. CLINICAL SIGNIFICANCE: This new application of IOS has a promising potential in clinical practice to assist practitioners during the fitting of guides.

The Medical, Clinical, and Radiographic Aspects of Multiple Idiopathic Tooth Resorption: A Systematic Review.

BACKGROUND: Many causes of resorption remain unclear and are thus identified as idiopathic. In such cases, management is difficult, especially when multiple teeth are involved. The aim of the present study was to assess the literature regarding the medical, clinical, and radiographic aspects of multiple idiopathic resorptions (MIR) and to examine the factors associated with the risk of extraction. METHODS: The title and protocol were registered a priori in PROSPERO (CRD42020191564), and the study followed the PRISMA methodology. Four electronic databases were searched to include reviews and case reports on MIR in permanent dentition. RESULTS: Among the 1035 articles identified, 31 case reports were included. The mean age of the patients was 32 years (SD = 16.4). MIR were consistently diagnosed after radiographic evaluation and were undetected during intra-oral examination in 62% of cases. The treatment involved extraction in 77% of cases. The risk of extraction increased in the presence of periodontal inflammation. CONCLUSIONS: MIR are aggressive forms of resorption requiring routine visits. MIR mostly involve extraction and lead to a challenging prosthetic rehabilitation due to severely damaged abutment teeth. However, the current knowledge on MIR remains fragmental and based on a limited number of case reports.

Multifactorial Analysis of Endodontic Microsurgery Using Finite Element Models.

BACKGROUND: The present study aimed to classify the relative contributions of four biomechanical factors-the root-end filling material, the apical preparation, the root resection length, and the bone height-on the root stresses of the resected premolar. METHODS: A design of experiments approach based on a defined subset of factor combinations was conducted to calculate the influence of each factor and their interactions. Sixteen finite element models were created and analyzed using the von Mises stress criterion. The robustness of the design of experiments was evaluated with nine supplementary models. RESULTS: The current study showed that the factors preparation and bone height had a high influence on root stresses. However, it also revealed that nearly half of the biomechanical impact was missed without considering interactions between factors, particularly between resection and preparation. CONCLUSIONS: Design of experiments appears to be a valuable strategy to classify the contributions of biomechanical factors related to endodontics. Imagining all possible interactions and their clinical impact is difficult and can require relying on one's own experience. This study proposed a statistical method to quantify the mechanical risk when planning apicoectomy. A perspective could be to integrate the equation defined herein in future software to support decision-making.

Sol-gel bioglasses in dental and periodontal regeneration: A systematic review.

Due to their osteoconductive and osteoinductive abilities, bioglasses (BGs) have attracted attention in tissue engineering, especially for mineralized tissue. The aim of this study is to review the current state of the art on the effects of BGs produced by sol-gel on cells for dental and periodontal regeneration. The study also discusses associated antibacterial properties. The research was performed by considering the Preferred Reporting Items for Systematic Reviews and the Meta-Analyses (PRISMA) statement. The research ranged 5 years' window time (from January, 01, 2012, to August, 31, 2017) and the relevant studies were identified based on the inclusion/exclusion criteria. A total of 45 articles were selected from 244 initial returns, plus seven further articles coming from other sources were selected for the same purpose. From this systematic study, it is revealed that only 13 of the 52 articles have proved both the ability of BGs to differentiate dental cells at genetic level and their ability of triggering cell-mediated mineralization, but only six of them showed, along with cells, the antibacterial properties of the glasses. This review shows that sol-gel BGs are not toxic, can sustain cell proliferation and differentiation at a genetic level, and can keep the bacterial population under control. Moreover, a standard methodology and an ideal material are suggested. © 2018 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater 107B: 1210-1227, 2019.

Bioactivity evaluation of collagen-based scaffolds containing a series of Sr-doped melt-quench derived phosphate-based glasses.

Phosphate-based glasses have been attracting attention due to their possible medical applications arising from unique dissolution characteristics in the human body leading to the possibility of new tissue regeneration. In this study, the leaching kinetics of a series of melt-quenched Sr-doped phosphate glasses are presented. Regardless of the presence of Sr, all the glasses have an initial linear and sustained release of the ions followed by a plateau. To guarantee proper nutritional support to the growing tissue during regeneration and to mimic the 3-dimensional architecture of tissues, organic scaffold systems have been developed. However, their poor mechanical strength has limited their application. To overcome this problem, cross-linkers can be used although this then limits the solubility of the materials. To succeed in dealing with such a limitation, in this paper, by freeze-drying, the aforementioned soluble melt-quenched phosphate glasses were combined as powders with collagen fibres from bovine achilles tendon to make degradable scaffolds. The scaffolds were characterized by SEM, EDX and BET. Changes to the dissolution behaviour of the glasses arising from the presence of collagen interacting with the ions leached were reported. Furthermore, the ability of the scaffolds to induce hydroxyapatite (HA) formation was evaluated: one the elaborated scaffold could grow an HA-like layer after a week in SBF. Based on the results obtained, a possible application in restorative dentistry is proposed for one or more materials.

Improvements in Resolution of Additive Manufacturing: Advances in Two-Photon Polymerization and Direct-Writing Electrospinning Techniques.

In recent years, additive manufacturing (AM) technologies have attracted significant interest in many industrial and research fields, particularly in tissue engineering. Printed structures used as physical and bioactive supports for tissue regeneration are becoming increasingly complex so as to mimic natural tissues in order to answer future medical needs. Reproducing the biological environment of a native tissue from the microscopic to the macroscopic scale appears to be the best strategy for effective regeneration. Recent advances in AM have led to the production of scaffolds designed with a high precision. This Review presents results concerning two AM technologies which enable the highest accuracy of scaffold design to be obtained, with a precision down to the nanoscale. The first technique is based on a two-photon polymerization (TPP) process, while the other is based on a direct-writing electrospinning (DWES) system. Here, we present an overview of the fabrication mechanisms, the final scaffold properties, and their applications in tissue engineering. The production of highly resolved structures offers new possibilities for studying cell behavior in a controlled environment and also for adjusting the desired scaffold properties to address current and future needs in tissue engineering. The current technical limitations and future challenges are thus also discussed in this Review.

The use of FDI criteria in clinical trials on direct dental restorations: A scoping review.

OBJECTIVES: A scoping review was conducted to explore the use of FDI criteria 10 years after their introduction. The first aim was to compare the amount of studies using the FDI and/or the modified USPHS criteria. The second aim was to analyse the use of the FDI criteria in clinical trials evaluating direct dental restorations. DATA: Listing of studies using FDI and/or USPHS criteria per year since 2007. Clinical studies related to the assessment of direct restorations using FDI criteria. SOURCE: Two systematic searches - regarding the use of FDI and modified USPHS criteria - were carried out on Medline/Pubmed in order to identify the studies published between 2007 and 2017. Authors of the included articles were contacted to clarify their choice of FDI criteria in their studies. ClinicalTrials.gov database was also queried for the on-going studies that use FDI and modified USPHS criteria. STUDY SELECTION: In the first review, all the clinical trials (randomized/non-randomized, controlled, prospective/retrospective studies) that used FDI criteria to evaluate direct restorations on primary or permanent teeth were included. CONCLUSIONS: 16.3% of the studies used FDI criteria. The percentage of studies using them increased from 4.5% in 2010 to 50.0% in 2016. In average, 8.5 FDI criteria were used. The most employed criteria were: marginal adaptation (96.7%), staining (90.0%), fracture of material and retention (90.0%), recurrence of caries/erosion/abfraction (90.0%), post-operative sensitivity/tooth vitality (86.7%) and surface luster (60.0%). In addition, among the 27 on-going studies from ClinicalTrials.gov database, 51.9% use FDI criteria (including 87.5% with an open recruitment status). CLINICAL SIGNIFICANCE: FDI criteria were reported as practical (various and freely selectable), relevant (sensitive as well as appropriate to current restorative materials and clinical studies design), standardized (making comparisons between investigations easier). Investigators should go on using them for a better standardization of their clinical judgment, allowing comparisons with other studies.

[Odontoblast: a key cell involved in the perception of dentinal pain]. / L'odontoblaste - Un acteur incontournable de la perception de la douleur dentinaire.

Dentinal sensitivity is a clinical condition daily encountered by practitioners and constitutes the symptoms of dentinal hypersensitivity, a common dental pain affecting on average 30% of the population. However, the management of this pathology is not always effective due to the lack of knowledge particularly concerning the means by which dental nociceptive signals are transduced. The mechanisms underlying dentin sensitivity still remain unclear probably due to the structural and functional complexity of the players including odontoblasts, nerve endings and dentinal fluid running in the dentinal tubules. The unique spatial situation of odontoblasts, ciliated cells in close relationship with nerve terminals, suggests that they could play a pivotal role in the transduction of sensory events occurring within the dentin tissue. Our studies have identified mechano-thermosensitive transient receptor potential ion channels (TRPV1-4, TRPA8, TRPM3, KCa, TREK-1, PC1, PC2) localised on the odontoblastic membrane and at the base of the cilium. They could sense temperature variations or movements of dentinal fluid within tubules. Moreover, several voltage-gated sodium channels confer excitable properties to odontoblasts in response to injection of depolarizing currents. In vivo, these channels co-localize with nerve endings at the apical pole of odontoblasts, and their expression pattern seems to be correlated with the spatial distribution of stretch-activated KCa channels. All these data strengthen the hypothesis that odontoblasts could act as sensor cells able to transmit nociceptive signals. However, how cells sense signals and how the latter are transmitted to axons represent the main issue to be solved.

Topical review. Dental pain and odontoblasts: facts and hypotheses.

Dental pain arises from exposed dentin following bacterial, chemical, or mechanical erosion of enamel and/or recession of gingiva. Thus, dentin tissue and more specifically patent dentinal tubules represent the first structure involved in dentin sensitivity. Interestingly, the architecture of dentin could allow for the transfer of information to the underlying dental pulp via odontoblasts (dentin-forming cells), via their apical extension bathed in the dentinal fluid running in the tubules, or via a dense network of trigeminal sensory axons intimately related to odontoblasts. Therefore, external stimuli causing dentinal fluid movements and odontoblasts and/or nerve complex responses may represent a unique mechanosensory system bringing a new role for odontoblasts as sensor cells. How cells sense signals and how the latter are transmitted to axons represent the main questions to be resolved. However, several lines of evidence have demonstrated that odontoblasts express mechano- and/or thermosensitive transient receptor potential ion channels (TRPV1, TRPV2, TRPV3, TRPV4, TRPM3, KCa, TREK-1) that are likely to sense heat and/or cold or movements of dentinal fluid within tubules. Added to this, voltage-gated sodium channels confer excitable properties of odontoblasts in vitro in response to injection of depolarizing currents. In vivo, sodium channels co-localize with nerve terminals at the apical pole of odontoblasts and correlate with the spatial distribution of stretch-activated KCa channels. This highlights the terminal web as the pivotal zone of the pulp/dentin complex for sensing external stimuli. Crosstalk between odontoblasts and axons may take place by the release of mediators in the gap space between odontoblasts and axons in view of evidence for nociception-transducing receptors on trigeminal afferent fibers and expression of putative effectors by odontoblasts. Finally, how axons are guided to the target cells and which kind of signaling molecules are involved is extensively discussed in this review.

Microtubule-associated protein 1b, a neuronal marker involved in odontoblast differentiation.

INTRODUCTION: Map-1B belongs to the family of proteins that govern the dynamic state and organization of microtubules within cells. MAP-1B is a microtubule-associated protein highly expressed during the development of the nervous system. Its expression, regulated by the fragile X mental retardation protein (FMRP), is essential to stabilize microtubules during the elongation of dendrites and neurites. Other microtubules-associated molecules such as tau or MAP2 seem to act similarly. The aim of this work was to identify the MAP-1B expression in in vitro and in vivo human odontoblasts during development and carious processes. The expression of MAP2 and tau was also studied. MATERIALS AND METHODS: In cultured cells, MAP-1B expression was analyzed by real-time polymerase chain reaction, flow cytometry, and Western blot. Its distribution was visualized by in situ hybridization and immunochemistry both in vitro and in vivo. The expression of FMRP, MAP2, and tau was identified by real-time polymerase chain reaction and immunochemistry. RESULTS: MAP-1B is specifically expressed in odontoblasts from adult third molars as well as incisor germs from human embryos. In adult carious teeth, it is also expressed in newly differentiated dentin-forming cells. In vitro, MAP-1B expression is related to the differentiation state of odontoblasts. MAP-1B clearly underlines the cellular architecture of cell bodies and processes of differentiated cells. FMRP, MAP2, and tau are also detected in vivo. CONCLUSION: On the basis of these data, MAP-1B could be considered as a new protein involved in the terminal differentiation of odontoblasts.

Odontoblast: a mechano-sensory cell.

Odontoblasts are organized as a single layer of specialized cells responsible for dentine formation and presumably for playing a role in tooth pain transmission. Each cell has an extension running into a dentinal tubule and bathing in the dentinal fluid. A dense network of sensory unmyelinated nerve fibers surrounds the cell bodies and processes. Thus, dentinal tubules subjected to external stimuli causing dentinal fluid movements and odontoblasts/nerve complex response may represent a unique mechano-sensory system giving to dentine-forming cells a pivotal role in signal transduction. Mediators of mechano-transduction identified in odontoblast include mechano-sensitive ion channels (high conductance calcium-activated potassium channel--K(Ca)--and a 2P domain potassium channel--TREK-1) and primary cilium. In many tissues, the latter is essential for microenvironment sensing but its role in the control of odontoblast behavior remains to be elucidated. Recent evidence for excitable properties and the concentration of key channels to the terminal web suggest that odontoblasts may operate as sensor cells.

Voltage-gated sodium channels confer excitability to human odontoblasts: possible role in tooth pain transmission.

Odontoblasts are responsible for the dentin formation. They are suspected to play a role in tooth pain transmission as sensor cells because of their close relationship with nerve, but this role has never been evidenced. We demonstrate here that human odontoblasts in vitro produce voltage-gated tetrodotoxin-sensitive Na(+) currents in response to depolarization under voltage clamp conditions and are able to generate action potentials. Odontoblasts express neuronal isoforms of alpha2 and beta2 subunits of sodium channels. Co-cultures of odontoblasts with trigeminal neurons indicate a clustering of alpha2 and beta2 sodium channel subunits and, at the sites of cell-cell contact, a co-localization of odontoblasts beta2 subunits with peripherin. In vivo, sodium channels are expressed in odontoblasts. Ankyrin(G) and beta2 co-localize, suggesting a link for signal transduction between axons and odontoblasts. Evidence for excitable properties of odontoblasts and clustering of key molecules at the site of odontoblast-nerve contact strongly suggest that odontoblasts may operate as sensor cells that initiate tooth pain transmission.

Tensile and shear bond strength evaluation of a total-etch three-step and two self-etching one-step dentin bonding systems.

PURPOSE: The aim of this study was to compare the bond strengths of two new self-etching one-step (Prompt L-Pop 2 and Adper Prompt L-pop) to a total-etch three-step dentin bonding system (Scotchbond Multipurpose Plus). MATERIALS AND METHODS: One hundred twenty human molars were randomly divided into 3 groups of 40 specimens each. Dentin surfaces of each group were bonded with either Scotchbond Multipurpose Plus (SMP), a three-step system, Prompt L-Pop 2 (PLP), or Adper Prompt L-Pop (APLP), two one-step bonding systems--according to manufacturers' recommendations. After adhesive application, a composite resin cylinder was incrementally built in a Teflon mold (5 mm high and 5 mm in diameter). The samples of each group were randomly divided into 2 subgroups of 20 samples each and were tested in a shear bond or in a tensile bond strength mode (crosshead speed 5 mm/min). Statistical analyses were performed with one-way ANOVA and Student's t-test. RESULTS: The significantly lowest shear and tensile bond strength values were obtained with APLP. PLP revealed higher shear bond strengths than APLP and SMP. There were no differences in tensile bond strengths between PLP and SMP (p < 0.05). CONCLUSION: The results of this in vitro study showed that the chemical modifications (adjunction of monomers and copolymers) of the self-etching all-in-one system APLP did not improve its mechanical properties.

Odontoblast expression of semaphorin 7A during innervation of human dentin.

Semaphorin 7A (SEMA 7A) is a membrane-anchored member of the semaphorin family of guidance proteins, previously identified in the immune system. Expressed in central and peripheral nervous system during embryonic and post-natal stages, it can mediate neuronal functions by promoting axonal growth. We show here that SEMA 7A is expressed in human odontoblasts in vivo and in vitro and that its expression is correlated with the establishment of dentin-pulp complex terminal innervation . Co-cultures of trigeminal ganglion (TG) with COS cells overexpressing SEMA 7A demonstrate that SEMA 7A can promote the growth of trigeminal nerve fibers. Finally, by RT-PCR and immunochemistry, we show that beta1-integrin, a SEMA 7A putative receptor, is expressed in pulpal nerve fibers but we failed to detect a co-localization between nerves and odontoblasts through these molecules. On the basis of these data, we suggest that SEMA 7A might be a molecule involved in the terminal innervation of the dentin-pulp complex.

Expression and localization of reelin in human odontoblasts.

Reelin is a large extracellular matrix (ECM) glycoprotein strongly expressed during embryonic development in the central nervous system and involved in architectonic brain development. It could participate in axon plasticity processes or adhesion-recognition between nerve fibers in adulthood. Previously identified from a subtractive cDNA library of fully differentiated human odontoblasts, reelin might be involved in the relationship between dental nerves and odontoblasts in as so far the latter are in close association with pulpal nerve fibers. Here, we show by in situ hybridization and immunohistochemistry that reelin is specifically expressed by human odontoblasts in vivo and in vitro and that an intense expression of the reelin gene is detected in odontoblasts in comparison with pulpal cells (PC). Co-cultures of rat trigeminal ganglion (TG) and odontoblasts allow to mimic odontoblast innervation and demonstrate that neurites contact these cells with reelin molecules as observed in vivo in human dental pulp. Moreover, by RT-PCR, we show that both reelin receptors (namely apolipoprotein E receptor [ApoER-2], very low density lipoprotein receptor [VLDLR] and cadherin-related neuronal receptor [CNR]) and the cytoplasmic adapter Disabled-1 implicated in the reelin signal transduction, were expressed by trigeminal ganglion. On the basis of these data, we suggest that reelin might be an extracellular matrix molecule involved in the terminal innervation of the dentin-pulp complex, promoting adhesion between dental nerve endings and odontoblasts.