Enamel Structure Research Articles

Hierarchically mimicking outer tooth enamel for restorative mechanical compatibility

Tooth enamel, and especially the outer tooth enamel, is a load-resistant shell that benefits mastication but is easily damaged, driving the need for enamel-restorative materials with comparable properties to restore the mastication function and protect the teeth. Synthesizing an enamel analog that mimics the components and hierarchical structure of natural tooth enamel is a promising way to achieve these comparable mechanical properties, but it is still challenging to realize. Herein, we fabricate a hierarchical enamel analog with comparable stiffness, hardness, and viscoelasticity as natural enamel by incorporating three hierarchies of outer tooth enamel based on hierarchical assembly of enamel-like hydroxyapatite hybrid nanowires with polyvinyl alcohol as a matrix. This enamel analog possesses enamel-similar inorganic components and a nanowire-microbundle-macroarray hierarchical structure. It exhibits toughness of 19.80 MPa m1/2, which is 3.4 times higher than natural tooth enamel, giving it long-term fatigue durability. This hierarchical design is promising for scalable production of enamel-restorative materials and for optimizing the mechanical performance of engineering composites.

The Harmful Effects of Welding Fumes on Human Dental Enamel-A Microhardness Analysis.

Introduction: Over the years, welding fumes' harmful effects have been demonstrated countless times in the scientific literature. Recently, studies in the field have shown an increasing interest in the negative consequences that these fumes may have on the tissues of the oral cavity. Materials & method: The current study aimed to investigate the impact that welding fumes have on the structure of human dental enamel by analyzing the microhardness of the dental enamel in 15 extracted human teeth, after various exposure times, using the Vickers method. Results: The results obtained after 48, 96, 168, and 336 h of direct exposure of the extracted specimens to the welding fumes show a statistically significant increase in the depreciation of the dental enamel's microhardness, related to the duration of exposure (p < 0.05). An average of 305 Vickers units was observed at the longest exposure time, 336 h, in the present study, whereas in the control group, the microhardness analysis showed an average of 327 Vickers units.

Energy-dispersive Laue diffraction analysis of the influence of statherin and histatin on the crystallographic texture during human dental enamel demineralization.

Energy-dispersive Laue diffraction (EDLD) is a powerful method to obtain position-resolved texture information in inhomogeneous biological samples without the need for sample rotation. This study employs EDLD texture scanning to investigate the impact of two salivary peptides, statherin (STN) and histatin-1 (HTN) 21 N-terminal peptides (STN21 and HTN21), on the crystallographic structure of dental enamel. These proteins are known to play crucial roles in dental caries progression. Three healthy incisors were randomly assigned to three groups: artificially demineralized, demineralized after HTN21 peptide pre-treatment and demineralized after STN21 peptide pre-treatment. To understand the micro-scale structure of the enamel, each specimen was scanned from the enamel surface to a depth of 250 µm using microbeam EDLD. Via the use of a white beam and a pixelated detector, where each pixel functions as a spectrometer, pole figures were obtained in a single exposure at each measurement point. The results revealed distinct orientations of hydroxyapatite crystallites and notable texture variation in the peptide-treated demineralized samples compared with the demineralized control. Specifically, the peptide-treated demineralized samples exhibited up to three orientation populations, in contrast to the demineralized control which displayed only a single orientation population. The texture index of the demineralized control (2.00 ± 0.21) was found to be lower than that of either the STN21 (2.32 ± 0.20) or the HTN21 (2.90 ± 0.46) treated samples. Hence, texture scanning with EDLD gives new insights into dental enamel crystallite orientation and links the present understanding of enamel demineralization to the underlying crystalline texture. For the first time, the feasibility of EDLD texture measurements for quantitative texture evaluation in demineralized dental enamel samples is demonstrated.

A Literature Review of Adhesive Systems in Dentistry: Key Components and Their Clinical Applications

The central aim of adhesive dentistry is to improve the compatibility between current adhesives and a range of substrates by employing diverse application techniques. Therefore, the overarching objective of this review is to offer a comprehensive analysis of dentin bonding systems, starting with an introduction to adhesion and a detailed overview of enamel and dentin structures, their histology, and the impact of dentin structure on resin–dentin bonding. It covers the mechanisms of resin–dentin bonding, including resin adhesive application, bonding mechanisms, and factors influencing efficacy. Further, this review explores the composition of resin adhesive systems, including acidic components, cross-linking monomers, solvents, and other critical elements. It also examines various adhesive strategies—etch-and-rinse, self-etch, and universal adhesives—highlighting their applications and advantages. The review extends to clinical applications of dental adhesion, including direct restorations, indirect restorations, and immediate dentin sealing (IDS), demonstrating the practical implications of adhesive systems in enhancing restoration longevity and performance. In conclusion, despite significant advancements, no gold-standard method for optimal adhesion exists. Each adhesive system has distinct strengths and limitations. The review emphasizes the importance of evaluating methods for achieving durable adhesion and staying current with technological advancements in adhesive systems. Summary: This review provides a thorough analysis of dentin bonding systems, delving into the structures and bonding mechanisms of both enamel and dentin. By exploring various adhesive systems and their components, it highlights the ongoing challenges in achieving optimal resin–dentin adhesion. The review also addresses the clinical applications of dental adhesion, including direct restorations, indirect restorations, and immediate dentin sealing (IDS), illustrating how different adhesive techniques impact clinical outcomes. It underscores the necessity for continuous innovation and assessment of adhesive systems to enhance long-term bonding effectiveness in clinical practice.

Fragment Reattachment For Complicated Crown Root Fracture – A Case Report

Complicated crown-root fractures are challenging dental injuries that involve both enamel and dentin structures and extend into the root. They often necessitate a multifaceted approach to achieve successful reattachment and functional restoration. This case report describes the management and outcomes of a complicated crown-root fracture using a reattachment technique

Evaluating the effectiveness of color changing adhesives versus ultraviolet absorbent dye additive adhesives in the removal of adhesive remnants after orthodontic debonding

The fixed orthodontic treatment initiates with bonding and ends up with debonding of brackets which alters the enamel surface. The adhesive remnants present on the enamel surface after debonding are removed with the help of various aids but alters the enamel surface to an extent and there is no alternative material or instrument for removing the adhesives. The aim of the study was to compare the effectiveness of color changing orthodontic bonding adhesives versus ultraviolet absorbent dye additive orthodontic bonding adhesives in the removal of adhesive remnants after orthodontic debonding.: 40 extracted human premolars were procured and metal brackets were bonded to the buccal surface with Group 1 – Enlight, Group 2 – Grengloo, Group 3 - Brace Paste &amp; Group 4 – Enlight + UV dye additive. Debonding of brackets were done in INSTRON and evaluated for ARI score in stereo microscope and photo micrographs were taken to analyze the surface area in ImageJ software with conventional and UV light source. Then the adhesive remnants were removed with tungsten carbide bur at low speed with appropriate illumination and the enamel surface is assessed under scanning electron microscope for EDI score. This study resulted with time taken for the removal of adhesive remnants between the 4 groups and indicates statistically significant difference (p&amp;#60;0.05). Group 3 (Brace Paste) possesses the less time taken for the removal of adhesive remnants between the other three groups and shear bond strength reveals a statistically significant difference (p&amp;#60;0.05) between the three adhesive groups. This current study concluded that the color changing adhesives with the fluorescence property were significantly different when compared with other adhesives due to the reduction in time taken for the removal of adhesive remnants from the enamel surface with minimal damage. Additionally the introduction of a UV dye additive for the visual distinction between the enamel structure and adhesive remnant also proves to be a valuable aid in the assessment of adhesive remnant index and removal.

The Relationship Between Maternal Nutrition During Pregnancy and Primary Tooth Caries in Stunted Toddlers: A Study at Umbulsari

Particularly during the 5th week of gestation when primary tooth enamel begins forming. Disruptions during this crucial period can lead to suboptimal enamel structure, increasing susceptibility to cavities in toddlers. A study conducted observed dental examinations of 10 stunted toddlers, all of whom exhibited dental caries. This prompted an investigation into whether maternal nutrition during pregnancy correlates with primary tooth caries in stunted toddlers. The research, a retrospective case-control study using purposive sampling of 90 respondents, utilized maternal BMI data and assessed primary tooth caries incidence. Analysis using Spearman's non-parametric correlation test indicated a significant relationship (p=0.001, r=0.351) between maternal nutritional status and primary tooth caries. Findings from the Umbulsari Community Health Center revealed that most mothers had below-normal nutritional status during pregnancy, and stunted toddlers averaged 7.3 dental caries. It was concluded that there was a relationship between maternal nutritional status during pregnancy and primary tooth caries in stunted toddlers at the Umbulsari Community Health Center with a weak correlation coefficient and the direction of correlation between variables was negative or inversely proportional.

Histological Analysis of Enamel Microstructure in Response to Dietary Habits: Comparative Study A cross Different Populations

Background: The protective role of enamel against physical and chemical injury is well documented. Despite being classified as connective tissue, with its composition and microstructure dominated by hydroxyapatite crystals it is the hardest in the human body Objective: The purpose of this study is to investigate the histological changes in enamel microstructure that occur when distinct populations follow different food habits. Study Design: This study employs a comparative cross-sectional design. Duration and Place of the Study: This study was conducted at Department of pathology Watim medical and dental college, Rawat , from 3rd June 2022 to 2nd May 2023. Material and Methods: A sum of 300 dental examples were acquired from members having a place with one or the other, High Carbohydrate Diet Group (n=95): people accounting their principle dietary consumption high-carb nourishments like grains/pay/aries and starches. High-Proteins Diet Group (n=108): participants who had the highest consumption of protein-rich foods, such as meat products, legumes and dairy. Mixed Diet Group (n=97): People with intermediate consumptions of carbohydrates, proteins and fats Subsequently, study participants were determined to best represent the two diet groups based on dietary surveys and medical histories. Results: In total, 300 participants are considered in this research, with the mean age of the group on HC totals 3.5 ± 1.3 years, HP group 3.4 ± 9.2 years, and MD group 3.6 ± 1.1 years. The gender distribution also shows similar characteristics, males are 55.8% in HC group, 46.3% in HP group, and 52.6% in MD group; females are 44.2%, 53.7%, and 47.4%, respectively. Concerning the age range, the major cluster is 26-35 years old and 36-45 years old cohorts, which proves the majority of the middle ages. Conclusion: Our results indicate that decomposition is a major factor affecting the surface morphology, structure and health of enamel.

Unraveling the orientation-dependent mechanics of dental enamel in the red-necked wallaby

Dental enamels of different species exhibit a wide variety of microstructural patterns that are attractive to mimic in bioinspired composites to simultaneously achieve high stiffness and superior toughness. Non-human enamel types, however, have not yet received the deserved attention and their mechanical behaviour is largely unknown. Using nanoindentation tests and finite element modelling, we investigate the mechanical behaviour of Macropus rufogriseus enamel, revealing a dominating influence of the microstructure on the effective mechanical behaviour and allowing insight into structural dependencies. We find a shallow gradient in stiffness and low degree of anisotropy over the enamel thickness that is attributed to the orientation and size of microstructural features. Most notably, M. rufogriseus’s modified radial enamel has a far simpler structural pattern than other species’, but achieves great property amplification. It is therefore a very promising template for biomimetic design. Statement of significanceThe diversity of dental enamel structures in different species is well documented, but the mechanical behaviour of non-human enamel types is largely unknown. In this work, we investigate the microstructure and structure-dependent mechanical properties of marsupial enamel by nanoindentation and finite element simulations. Combining these methods gives valuable insights into the performance of modified radial enamel structures. Their stiffness and toughness stems from a unique structural design that is far less complex than well-studied human enamel types, which makes it a uniquely suitable template for biomimetic design.

Immune System of Dental Pulp in Inflamed and Normal Tissue.

Teeth are vulnerable to structural compromise, primarily attributed to carious lesions, in which microorganisms originating from the oral cavity deteriorate the mineralized structures of enamel and dentin, subsequently infiltrating the underlying soft connective tissue, known as the dental pulp. Nonetheless, dental pulp possesses the necessary capabilities to detect and defend against bacteria and their by-products, using a variety of intricate defense mechanisms. The pulp houses specialized cells known as odontoblasts, which encounter harmful substances produced by oral bacteria. These cells identify pathogens at an early stage and commence the immune system response. As bacteria approach the pulp, various cell types within the pulp, such as different immune cells, stem cells, fibroblasts, as well as neuronal and vascular networks, contribute a range of defense mechanisms. Therefore, the immune system is present in the healthy pulp to restrain the initial spread of pathogens, and then in the inflamed pulp, it prepares the conditions for necrosis or regeneration, so inflammatory response mechanisms play a critical role in maintaining tissue homeostasis. This review aims to consolidate the existing literature on the immune system in dental pulp, encompassing current knowledge on this topic that explains the diverse mechanisms of recognition and defense against pathogens exhibited by dental pulp cells, elucidates the mechanisms of innate and adaptive immunity in inflamed pulp, and highlights the difference between inflamed and normal pulp tissue.

The Effect of Carbamide Peroxide Bleaching Gel with and without Remineralizing Agents on Microtensile Bond Strength of Resin Composites to Enamel

Introduction: Carbamide peroxide bleaching gel, along with remineralizing agents, can induce changes in the structure and mineral content of enamel, potentially leading to a decrease in the bond strength of resin composite to the enamel. Therefore, this laboratory study aimed to determine the effect of carbamide peroxide bleaching gel with and without remineralizing agents on the microtensile bond strength (µTBS) of resin composites with microhybrid and nanofill structures to enamel. Materials and Methods: Thirty extracted third molar teeth were randomly divided into five groups, each group subdivided into two equal subgroups: Group 1: Control group, Group 2: Bleaching gel without fluoride, Group 3: Bleaching gel containing fluoride, Group 4: Bleaching gel containing CPP-ACP, and Group 5: Bleaching gel containing fluoride and CPP-ACP. In the first subgroups, nanofilled resin composite Filtek Z350, while in the second subgroups, microhybrid resin composite Filtek Z250 were bonded to enamel surface. After specimen preparation, µTBS was measured using a universal testing machine. Data were analyzed using parametric tests (P value&lt;0.05). Results: The highest µTBS of resin composite to enamel was observed in the control group, while the lowest bond strength was seen in the fluoride-containing bleaching group. Comparisons of µTBS between the study groups pairwise, except for the comparison between the control group and the bleaching group, the bleaching group with (CPP-ACP+Fluoride), and the (CPP-ACP) group with the fluoride group, showed significant differences in bond strength. Although, the mean µTBS of the Filtek Z250 composite was higher than the Filtek Z350 composite in all groups, but this difference was not statistically significant. Conclusion: The use of carbamide peroxide bleaching gel with remineralizing agents leads to a decrease in µTBS of the resin composite to the enamel.

Evaluation of Ilex guayusa and Piper marginatum Extract Cytotoxicity on Human Dental Pulp Mesenchymal Stem Cells.

Amelogenesis imperfecta is a hereditary disorder affecting dental enamel. Among its phenotypes, hypocalcified AI is characterized by mineral deficiency, leading to tissue wear and, consequently, dental sensitivity. Excessive fluoride intake (through drinking water, fluoride supplements, toothpaste, or by ingesting products such as pesticides or insecticides) can lead to a condition known as dental fluorosis, which manifests as stains and teeth discoloration affecting their structure. Our recent studies have shown that extracts from Colombian native plants, Ilex guayusa and Piper marginatum, deposit mineral ions such as phosphate and orthophosphate into the dental enamel structure; however, it is unknown whether these extracts produce toxic effects on the dental pulp. To assess cytotoxicity effects on human dental pulp stem cells (hDPSCs) exposed to extracts isolated from I. guayusa and P. marginatum and, hence, their safety for clinical use. Raman spectroscopy, fluorescence microscopy, and flow cytometry techniques were employed. For Raman spectroscopy, hDPSCs were seeded onto nanobiochips designed to provide surface-enhanced Raman spectroscopy (SERS effect), which enhances their Raman signal by several orders of magnitude. After eight days in culture, I. guayusa and P. marginatum extracts at different concentrations (10, 50, and 100 ppm) were added. Raman measurements were performed at 0, 12, and 24 h following extract application. Fluorescence microscopy was conducted using an OLIMPUS fv1000 microscope, a live-dead assay was performed using a kit employing a BD FACS Canto TM II flow cytometer, and data analysis was determined using a FlowJo program. The Raman spectroscopy results showed spectra consistent with viable cells. These findings were corroborated using fluorescence microscopy and flow cytometry techniques, confirming high cellular viability. The analyzed extracts exhibited low cytotoxicity, suggesting that they could be safely applied on enamel for remineralization purposes. The use of nanobiochips for SERS effect improved the cell viability assessment.

Morphological features of enamel in fluorosis of different degrees of severity

The occurrence of dental fluorosis is facilitated by a violation of enamel mineralization caused by fluorides, which enter the human body in excess during its development and formation and have a toxic effect on enamel blasts. However, the molecular mechanisms involved in the pathogenesis of fluorosis are not fully understood. Enamel formation is a complex process involving cell proliferation and differentiation through epithelial-mesenchymal sequential secretion of matrix proteins, tissue-specific transport of ions including calcium and fluoride, and precipitation and alignment of enamel crystals through interactions between organic and inorganic molecules. Understanding the morphological features of enamel changes during fluoride intoxication of the human body in the endemic region allows us to clearly understand the need for a comprehensive solution to this medical and social problem. The aim was to study the morphological features of enamel in fluorosis in residents of the endemic region of Ukraine, in particular the Poltava region. The work examines different groups of teeth (both intact and affected by fluorosis) removed for orthodontic or clinical indications in men and women aged 17 to 40 years. Morphological signs were studied first on native, and later on histochemically stained sections. It was established that the violation of the structure of the enamel layer of the teeth in mild and severe fluorosis is characterized by both partial and complete violation of the movement of the enamel prisms with signs of destruction. Fragmentation and homogeneity throughout the entire thickness were found in some areas of the enamel. When evaluating histochemically stained sections of teeth affected by fluorosis, it was established that dystrophic changes in the enamel structure and accumulation of acidic glycosaminoglycans in the lesions are more characteristic of mild and moderate forms. Under the conditions of a severe form of fluorosis, complete destruction of the prisms, fragmentation of the lamella, homogenization of areas on the entire enamel layer, which is due to the uneven distribution of acidic mucopolysaccharides, have been established. Morphologically and histochemically dystrophic changes in the areas of the affected enamel are confirmed by uneven distribution and accumulation of acidic glycosaminoglycans. An assessment of the effect of fluoride intoxication on the state of tooth enamel was carried out, which will allow to expand the possibilities of preventive measures for related specialists, as well as to create and develop additional treatment methods that will contribute to the improvement of physical and aesthetic indicators of teeth. dental health.

Bottom-Up Assembling Hierarchical Enamel-Like Bulk Materials with Excellent Optical and Mechanical Properties for Tooth Restoration.

Enamel has good optical and mechanical properties because of its multiscale hierarchical structure. Biomimetic construction of enamel-like 3D bulk materials at nano-, micro-, mesh- and macro-levels is a challenge. A novel facile, cost-effective, and easy large-scale bottom-up assembly strategy to align 1D hydroxyapatite (HA) nanowires bundles to 3D hierarchical enamel structure with the nanowires bundles layer-by-layer interweaving orientation, is reported. In the strategy, the surface of oleate templated ultralong HA nanowires with a large aspect ratio is functionalized with amphiphilic 10-methacryloyloxydecyl dihydrogen phosphate (MDP). Furtherly, the MDP functionalized HA nanowire bundles are assembled layer-by-layer with oriented fibers in a single layer and cross-locked between layers at a certain angle at mesoscale and macroscale in the viscous bisphenol A-glycidyl methacrylate (Bis-GMA) ethanol solution by shear force induced by simple agitation and high-speed centrifugation. Finally, the excessive Bis-GMA and ethanol are removed, and (Bis-GMA)-(MDP-HA nanowire bundle) matrix is densely packed under hot pressing and polymerized to form bulk enamel-like materials. The composite has superior optical properties and comparable comprehensive mechanic performances through a combination of strength, hardness, toughness, and friction. This method may open new avenues for controlling the nanowires assembly to develop hierarchical nanomaterials with superior properties for many different applications.

CLINICAL AND MORPHOLOGICAL ASSESSMENT OF THE EFFECTIVENESS OF THE APPLICATION INNOVATIVE THERAPEUTIC AND PROPHYLACTIC TOOTHPASTE IN THE COMPLEX TREATMENT OF PATIENTS WITH MAJOR DENTAL DISEASES

The social and economic development of a society is largely determined by the level of health of its young population. The objective of this study was to increase the effectiveness of preventive and comprehensive treatment of young patients with major dental diseases using an innovative therapeutic and preventive toothpaste based on organic gel. A group of 32 volunteers participated in the study. All patients underwent a complex dental examination that included basic and additional methods (determination of indices of caries intensity, indicators of oral hygiene (simple hygiene index OHI-S, Silnes-Low index), evaluation of periodontal tissue status (papillary-limbal alveolar abscess index PMA, gingival bleeding in inflammatory periodontal disease index BI Müllmann), evaluation of pain (hypersensitivity) to stimuli using a visual analog scale (VAS), measurement of the electrical conductivity of tooth enamel using the Dentest electrodiagnostic device (ZAO Geosoftident), clinical evaluation of enamel remineralization rate, spectrophotometer "VITA (Easy Shade) (VITA) to evaluate tooth discoloration, oral fluid immunoassay, and cytomorphometric studies of the buccal epithelium. The results of the clinical trials showed that the therapeutic and prophylactic toothpaste has excellent consumer characteristics, has no allergic or local irritant effects on the oral mucosa, improves the natural protection of the oral cavity, effectively cleans up to 100% of the oral cavity, provides anti-inflammatory effects, eliminates gum swelling and bleeding from the first use, reduces tooth sensitivity, reduces tooth enamel structure, and was shown to have no toxic effect on the cells of the buccal epithelium. The results of the clinical trial suggest that the innovative therapeutic and prophylactic dentifrice can be recommended for daily use in a wide range of individuals, as well as in patients with low tooth enamel resistance, various periodontal diseases, and oral mucosa.

On elastoplastic behavior of porous enamel–An indentation and numerical study

The micro/nano pores in natural mineralized tissues can, to a certain extent, affect their responses to mechanical loading but are generally ignored in existing indentation analysis. In this study, we first examined the void volume fraction of sound and caries lesion enamels through micro-computed tomography (micro-CT). A Berkovich indentation study was then carried out to characterize the effect of porous microstructure on the mechanical behavior of the human enamels. The indentation tests were also modeled using the nonlinear finite element analysis technique to simulate indentation load-displacement curves, which showed reasonable agreement with the experimental measurements. From the simulation results, the extent of densification in the plastic zone was identified and the corresponding stress and contact pressure evolutions were quantified. Further, a conventional elastic-perfectly plastic material model without considering micropores was also developed to investigate the compaction effect of the porous structure. The simulation results reveal that conventional elastic perfect-plastic constitutive models become less reliable to model the mechanical behavior of carious lesion enamel with increasing loss of mineral content as it underestimates the yield stress and plastic energy dissipation. This study divulges the importance of compaction of porous enamel structure beneath the indented area. Note that understanding the effect of porous microstructures on plastic behavior is vital as the involved inelastic deformation mechanism associated with irreversible processes, such as wear and localized microcracking, has a significant bearing on wear and fatigue behavior of enamel. Statement of significanceBased on micro-CT and nano-indentation characterization, a numerical model was developed aiming to precisely describe the deformation behavior of naturally porous enamel. Inelastic properties and energy dissipation characteristics of porous enamel were investigated in detail. This work demonstrated that the existence of micro-pores in White Spot Lesions (WSLs) contributes to mechanical stability, which can mitigate the reduction in Young's modulus and fracture toughness resulting from loss of mineral components. The knowledge gained from this study can be used to explain the mechanisms related to irreversible processes, such as contact induced cracking and wear, and strengthen understanding of the mechanical behavior of porous mineralized tissues.

Efficacy of the Probiotic L. brevis in Counteracting the Demineralizing Process of the Tooth Enamel Surface: Results from an In Vitro Study.

Enamel plays an essential role in protecting the underlying layers of the human tooth; therefore, preserving it is vital. This experimental study aimed to evaluate the potential ability of L. brevis to counteract the action of a demineralizing agent on dental enamel morphology and mineral composition in vitro. The sample consisted of 12 healthy human posterior teeth. The coronal portion of each tooth was subdivided into two equal parts longitudinally. The specimens were randomly divided into four groups: artificial saliva, L. brevis suspension, demineralizing agent (DA), and DA plus L. brevis. Scanning electron microscopy (SEM) and energy-dispersive X-ray spectroscopy (EDS) were used to evaluate the surface micromorphology and the mineral content, respectively. The statistical analysis was conducted using a one-way ANOVA, followed by Tukey's post hoc test. SEM analysis did not highlight significant changes in the enamel microstructure of L. brevis-treated specimens compared to the control. DA-induced damage to the enamel structure was drastically reduced when the specimens were contextually exposed to the probiotic. The treatment with DA substantially reduced the weight % of crucial enamel minerals, i.e., Ca and P. Notably, the probiotic was able to reverse the demineralization process, bringing Ca and P weight % back to basal levels, including the Ca/P ratio. The findings indicate that L. brevis is able to efficiently protect the dental enamel surface from the damage caused by DA and increase the enamel resistance to demineralization. Overall, L. brevis confirms its efficacy in preventing or counteracting the action of carious lesions through a novel mechanism that protects the tooth surface under a chemical challenge that mimics the caries process.

Structural and Color Alterations of Teeth following Orthodontic Debonding: A Systematic Review.

The objective of this study was to explore the effects of fixed orthodontic appliances on enamel structure by assessing microfractures, surface roughness, and alterations in color. This review followed the Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines. A systematic search of online databases was conducted using the keywords 'enamel' AND 'orthodontic debonding'. Eligibility criteria included both in vivo and ex vivo clinical trials conducted on human teeth. A total of 14 relevant papers were analyzed. Various instruments and techniques were utilized across different studies to assess surface roughness, color change, and surface fractures. The findings of this study suggest that ceramic brackets may lead to an increase in enamel fractures, particularly during bracket removal. The surface roughness of enamel exhibits variability depending on the adhesive substance and polishing methods used post-removal. Fixed orthodontic appliances could induce changes in enamel color, which may be alleviated by the use of nano-hydroxyapatite or specific polishing techniques. Further research is necessary to identify effective strategies for managing these color changes and improving the overall outcomes of fixed orthodontic treatment.

A novel mutation in GPR68 causes hypomaturation amelogenesis imperfecta

ObjectivesTo identify the genetic cause of a Chinese family with hypomaturation amelogenesis imperfecta (AI) and to characterize the structure of GPR68 mutated enamel in order to develop a deeper understanding of the role of the GPR68 protein during the intricate process of amelogenesis. DesignOne Chinese family with generalized hypomaturation AI was recruited. Two of the third molars from the proband were subjected to scanning electron microscopy (SEM) and energy dispersive X-ray spectroscopy (EDX). Whole exome sequencing (WES) was performed, and the identified mutation was confirmed by Sanger sequencing. Bioinformatics studies were further conducted to analyze the potential deleterious effects of the mutation. ResultsThe proband presented with a hypomaturation AI phenotype, characterized by fragile and discolored enamel surface. The AI enamel showed prismatic structure, which was sporadically obscured by areas of amorphous material and porous structure. EDX analysis showed the proband’s enamel demonstrated a significant decrease in calcium and phosphorus content and a significant increase in oxygen compared with normal enamel. A novel homozygous mutation of G protein-coupled receptor 68 (GPR68) (c .149 T > A, p.Ile50Asn) was identified in the proband. Bioinformatics analysis indicated that the mutation site displayed a high level of evolutionary conservation among species, and the mutation might impact the stability and conformation of the protein. ConclusionThe novel homozygous GPR68 mutation resulted in hypomaturation AI. We first described the effect of GPR68 mutation on enamel structure. Our results provide new genetic evidence that mutations involved in GPR68 contribute to hypomaturation AI.

ИЗУЧЕНИЕ СТРУКТУРЫ ПОВЕРХНОСТИ ЭМАЛИ ЗУБОВ ПОСЛЕ ОБРАБОТКИ ВОЗДУШНО-ПОРОШКОВЫМИ СИСТЕМАМИ РАЗЛИЧНЫХ ПОКОЛЕНИЙ

Subject. Today, there are many different air-powder systems (APS) for professional oral hygiene (PAH). The problem of selecting a powder for performing PPGP is still relevant. Objectives. The aim of the study was to evaluate the effect of different air-powder systems on the structure of tooth enamel. Matodology. The study consisted of 2 parts: experimental and clinical-laboratory. The experimental part of the study consisted in the allocation of experimental groups, their subsequent processing depending on the active component of the UPP (sodium bicarbonate, calcium carbonate, their mixture, glycine, trehalose) and study by scanning electron microscopy. Clinical and laboratory research is aimed at studying the time spent on the removal of soft pigmented plaque; the degree of cleaning of the tooth surface; the amount of powder required to perform PGPR; as well as the atomization of powder during the procedure; the traumatic effect of these systems on the structure of tooth enamel by interpreting the index of tooth sensitivity of L.Yu. Orekhova – S.B. Ulitovsky (TS-O-U index, %); and studying the average linear (Vas) velocity of blood flow in periodontal tissues using the method of Doppler ultrasound. Results. Powders with a mixture of sodium bicarbonate and calcium carbonate have the greatest damaging effect on tooth enamel structure, and powders with trehalose and glycine have the least damaging effect. On the basis of clinical study it was revealed that powders based on trehalose and glycine have less damaging effect both on tooth enamel and periodontal tissues, which is confirmed by the index of tooth sensitivity of L.Yu. Orekhova – S.B. Ulitovsky and the results of ultrasound Dopplerography. Conclusions. The conducted research allows recommending therapeutic dentists, periodontists, as well as dental hygienists to use glycine- and trehalose-based UPDs in their clinical practice due to their effective, safe and ergonomic use.