Mechanical properties of human oral mucosa tissues are site dependent: A combined biomechanical, histological and ultrastructural approach

Machine learning to mechanically assess 2D and 3D biomimetic electrospun scaffolds for tissue engineering applications: Between the predictability and the interpretability

Currently, the use of autografts is the gold standard for the replacement of many damaged biological tissues. However, this practice presents disadvantages that can be mitigated through tissue-engineered implants. The aim of this study is to explore how machine learning can mechanically evaluate 2D and 3D polyvinyl alcohol (PVA) electrospun scaffolds (one twisted filament, 3 twisted filament and 3 twisted/braided filament scaffolds) for their use in different tissue engineering applications. Crosslinked and non-crosslinked scaffolds were fabricated and mechanically characterised, in dry/wet conditions and under longitudinal/transverse loading, using tensile testing. 28 machine learning models (ML) were used to predict the mechanical properties of the scaffolds. 4 exogenous variables (structure, environmental condition, crosslinking and direction of the load) were used to predict 2 endogenous variables (Young's modulus and ultimate tensile strength). ML models were able to identify 6 structures and testing conditions with comparable Young's modulus and ultimate tensile strength to ligamentous tissue, skin tissue, oral and nasal tissue, and renal tissue. This novel study proved that Classification and Regression Trees (CART) models were an innovative and easy to interpret tool to identify biomimetic electrospun structures; however, Cubist and Support Vector Machine (SVM) models were the most accurate, with R2 of 0.93 and 0.8, to predict the ultimate tensile strength and Young's modulus, respectively. This approach can be implemented to optimise the manufacturing process in different applications.

Development of Cerium Oxide-Laden GelMA/PCL Scaffolds for Periodontal Tissue Engineering

This study investigated gelatin methacryloyl (GelMA) and polycaprolactone (PCL) blend scaffolds incorporating cerium oxide (CeO) nanoparticles at concentrations of 0%, 5%, and 10% w/w via electrospinning for periodontal tissue engineering. The impact of photocrosslinking on these scaffolds was evaluated by comparing crosslinked (C) and non-crosslinked (NC) versions. Methods included Fourier transform infrared spectroscopy (FTIR) for chemical analysis, scanning electron microscopy (SEM) for fiber morphology/diameters, and assessments of swelling capacity, degradation profile, and biomechanical properties. Biological evaluations with alveolar bone-derived mesenchymal stem cells (aBMSCs) and human gingival fibroblasts (HGFs) encompassed tests for cell viability, mineralized nodule deposition (MND), and collagen production (CP). Statistical analysis was performed using Kruskal-Wallis or ANOVA/post-hoc tests (α = 5%). Results indicate that C scaffolds had larger fiber diameters (~250 nm) compared with NC scaffolds (~150 nm). NC scaffolds exhibited higher swelling capacities than C scaffolds, while both types demonstrated significant mass loss (~50%) after 60 days (p < 0.05). C scaffolds containing CeO showed increased Young's modulus and tensile strength than NC scaffolds. Cells cultured on C scaffolds with 10% CeO exhibited significantly higher metabolic activity (>400%, p < 0.05) after 7 days among all groups. Furthermore, CeO-containing scaffolds promoted enhanced MND by aBMSCs (>120%, p < 0.05) and increased CP in 5% CeO scaffolds for both variants (>180%, p < 0.05). These findings underscore the promising biomechanical properties, biodegradability, cytocompatibility, and enhanced tissue regenerative potential of CeO-loaded GelMA/PCL scaffolds for periodontal applications.

Pilot Evaluation of Silicone Surrogates for Oral Mucosa Simulation in Craniofacial Surgical Training

Surgical simulators are crucial in early craniofacial and plastic surgical training, necessitating synthetic materials that accurately replicate tissue properties. Recent critiques of our lab's currently deployed silicone surrogate have highlighted numerous areas for improvement. To further refine our models, our group's objective is to find a composition of materials that is closest in fidelity to native oral mucosa during surgical rehearsal by expert craniofacial surgeons. Fifteen platinum silicone-based surrogate samples were constructed with variable hardness and slacker percentages. These samples underwent evaluation of tactile sensation, hardness, needle puncture, cut resistance, suture retention, defect repair, and tensile elasticity. Expert craniofacial surgeon evaluators provided focused qualitative feedback on selected top-performing samples for further assessment and statistical comparisons. An evaluation revealed surrogate characteristics that were satisfactory and exhibited good performance. Sample 977 exhibited the highest performance, and comparison with the original surrogate (sample 810) demonstrated significant improvements in critical areas, emphasizing the efficacy of the refined composition. The study identified a silicone composition that directly addresses the feedback received by our team's original silicone surrogate. The study underscores the delicate balance between biofidelity and practicality in surgical simulation. The need for ongoing refinement in surrogate materials is evident to optimize training experiences for early surgical learners.

Pain-related analysis on a resorbed ridge with various denture occlusal schemes using finite element method

Resorbed alveolar ridges, particularly in the lower jaw, have a small denture supporting area, which may cause the stress distribution of mastication load to exceed the pressure-pain threshold (PPT) and induce pain in the mucosa or potentially worsen the ridge resorption. Thus, choosing the ideal occlusal scheme among bilateral balanced (BBO), lingualized (LO), and monoplane (MO) for such conditions becomes crucial. The experiment was conducted using the finite element method on a modeling of a resorbed alveolar ridge in the lower jaw with three dentures placed on top, each of which was given different loading points according to the tooth arrangement of BBO, LO, and MO. The axial load was 100 N, and the resultant oblique loads on BBO and LO were 119 N and 106 N, respectively. The von Mises stresses for BBO, LO, and MO were observed in nine denture-supporting areas, and the results showed that the axial load did not produce stresses that exceeded the PPT value (0.64925 MPa) for BBO, LO, and MO with the highest value on area H, 0.43229 MPa, 0.39715 MPa, and 0.31576 MPa, respectively. However, the oblique load direction showed that the BBO had more areas (area E 0.80778 MPa and area H 0.76256 MPa) that exceeded the PPT than LO (area E 0.64394 MPa). The lingualized occlusal scheme is ideal for patients with resorbed alveolar ridge conditions, especially in terms of limiting interferences when the denture is functioning while maintaining comfort but still providing good masticatory performance and satisfactory esthetics.

Biofabrication Strategies for Oral Soft Tissue Regeneration

Gingival recession, a prevalent condition affecting the gum tissues, is characterized by the exposure of tooth root surfaces due to the displacement of the gingival margin. This review explores conventional treatments, highlighting their limitations and the quest for innovative alternatives. Importantly, it emphasizes the critical considerations in gingival tissue engineering leveraging on cells, biomaterials, and signaling factors. Successful tissue-engineered gingival constructs hinge on strategic choices such as cell sources, scaffold design, mechanical properties, and growth factor delivery. Unveiling advancements in recent biofabrication technologies like 3D bioprinting, electrospinning, and microfluidic organ-on-chip systems, this review elucidates their precise control over cell arrangement, biomaterials, and signaling cues. These technologies empower the recapitulation of microphysiological features, enabling the development of gingival constructs that closely emulate the anatomical, physiological, and functional characteristics of native gingival tissues. The review explores diverse engineering strategies aiming at the biofabrication of realistic tissue-engineered gingival grafts. Further, the parallels between the skin and gingival tissues are highlighted, exploring the potential transfer of biofabrication approaches from skin tissue regeneration to gingival tissue engineering. To conclude, the exploration of innovative biofabrication technologies for gingival tissues and inspiration drawn from skin tissue engineering look forward to a transformative era in regenerative dentistry with improved clinical outcomes.

High-Frequency Optical Coherence Elastography for Gingival Tissue Characterization: Variability in Stiffness and Response to Physiological Conditions

Accurate measurement of gingiva's biomechanical properties in vivo has been an active field of research but remained an unmet challenge. Currently, there are no noninvasive tools that can accurately quantify tensile and shear moduli, which govern gingival health, with sufficiently high accuracy. This study presents the application of high-frequency optical coherence elastography (OCE) for characterizing gingival tissue in both porcine models and human subjects. Dynamic mechanical analysis, histology studies, and strain analysis are performed to support the OCE result. Our findings demonstrate substantial differences in tissue stiffness between supra-dental and inter-dental gingiva, validated by dynamic mechanical analysis and OCE. We confirmed the viscoelastic, nearly linear, and transverse-isotropic properties of gingiva in situ, establishing the reliability of OCE measurements. Further, we investigated the effects of tissue hydration, collagen degradation, and dehydration on gingival stiffness. These conditions showed a decrease and increase in stiffness, respectively. While preliminary, our study suggests OCE's potential in periodontal diagnosis and oral tissue engineering, offering real-time, millimeter-scale resolution assessments of tissue stiffness, crucial for clinical applications and biomaterial optimization in reconstructive surgeries.

Does Maxillomandibular Fixation Technique Affect Occlusion Quality in Segmental LeFort I Osteotomy?

BACKGROUND

Segmental maxillary osteotomies require precise occlusal control due to variability in individual segment positioning. The role of maxillomandibular fixation (MMF) technique on occlusal control has not been validated.

PURPOSE

The purpose is to measure and compare the accuracy of occlusal positioning among MMF techniques.

STUDY DESIGN, SETTING, SAMPLE

This was a double-blinded in vitro study on experiment models to simulate a 3-piece LeFort I osteotomy. The models were constricted posteriorly and expanded using 3 different MMF techniques and compared to the unaltered baseline occlusion. Based on sample size calculation, 32 separate attempts were made for each MMF technique.

PREDICTOR VARIABLE

The predictor variable was MMF technique (brackets, MMF screws, and embrasure wires).

MAIN OUTCOME VARIABLES

The primary outcome variable was the visual occlusal analysis score, a 1.00 to 4.00 continuous scale measuring the similarity of the achieved occlusion to the planned (control) occlusion assessed by an oral and maxillofacial surgeon and an orthodontist. High visual occlusal analysis score indicated greater occlusal accuracy, with 3.50 defined as the threshold for accuracy. The secondary outcome variable was the linear error of the achieved occlusion at the canine and first molar teeth, with lower error indicating greater accuracy. An a priori accuracy threshold of 0.5 mm was set for this variable.

COVARIATES

None.

ANALYSES

Kruskal-Wallis test with post hoc testing was used to analyze the difference in the outcome variables of interest. P value < .05 was considered statistically significant.

RESULTS

Thirty-two attempts for each technique showed that brackets had higher VAOS than MMF screws and embrasure wires (median differences 1.49 and 0.48, P < .001), and had lower linear occlusal error (median differences 0.35 to 0.99 mm, P < .001).

CONCLUSION AND RELEVANCE

MMF technique influences the quality of occlusal control, with greater visual rating scores and lower linear errors seen with brackets than with embrasure wires or MMF screws.

Advances in 3D bioprinting for urethral tissue reconstruction

Urethral conditions affect children and adults, increasing the risk of urinary tract infections, voiding and sexual dysfunction, and renal failure. Current tissue replacements differ from healthy urethral tissues in structural and mechanical characteristics, causing high risk of postoperative complications. 3D bioprinting can overcome these limitations through the creation of complex, layered architectures using materials with location-specific biomechanical properties. This review highlights prior research and describes the potential for these emerging technologies to address ongoing challenges in urethral tissue engineering, including biomechanical and structural mismatch, lack of individualized repair solutions, and inadequate wound healing and vascularization. In the future, the integration of 3D bioprinting technology with advanced biomaterials, computational modeling, and 3D imaging could transform personalized urethral surgical procedures.

Emerging polymeric materials for treatment of oral diseases: design strategy towards a unique oral environment

Oral diseases are prevalent but challenging diseases owing to the highly movable and wet, microbial and inflammatory environment. Polymeric materials are regarded as one of the most promising biomaterials due to their good compatibility, facile preparation, and flexible design to obtain multifunctionality. Therefore, a variety of strategies have been employed to develop materials with improved therapeutic efficacy by overcoming physicobiological barriers in oral diseases. In this review, we summarize the design strategies of polymeric biomaterials for the treatment of oral diseases. First, we present the unique oral environment including highly movable and wet, microbial and inflammatory environment, which hinders the effective treatment of oral diseases. Second, a series of strategies for designing polymeric materials towards such a unique oral environment are highlighted. For example, multifunctional polymeric materials are armed with wet-adhesive, antimicrobial, and anti-inflammatory functions through advanced chemistry and nanotechnology to effectively treat oral diseases. These are achieved by designing wet-adhesive polymers modified with hydroxy, amine, quinone, and aldehyde groups to provide strong wet-adhesion through hydrogen and covalent bonding, and electrostatic and hydrophobic interactions, by developing antimicrobial polymers including cationic polymers, antimicrobial peptides, and antibiotic-conjugated polymers, and by synthesizing anti-inflammatory polymers with phenolic hydroxy and cysteine groups that function as immunomodulators and electron donors to reactive oxygen species to reduce inflammation. Third, various delivery systems with strong wet-adhesion and enhanced mucosa and biofilm penetration capabilities, such as nanoparticles, hydrogels, patches, and microneedles, are constructed for delivery of antibiotics, immunomodulators, and antioxidants to achieve therapeutic efficacy. Finally, we provide insights into challenges and future development of polymeric materials for oral diseases with promise for clinical translation.

Three-dimensional finite element analysis on stress distribution after different palatoplasty and levator veli palatini muscle reconstruction

OBJECTIVES

To establish a three-dimensional finite element model of the upper palate, pharyngeal cavity, and levator veli palatini muscle in patients with unilateral complete cleft palate, simulate two surgical procedures that the two-flap method and Furlow reverse double Z method, observe the stress distribution of the upper palate soft tissue and changes in pharyngeal cavity area after different surgical methods, and verify the accuracy of the model by reconstructing and measuring the levator veli palatini muscle.

MATERIALS AND METHODS

Mimics, Geomagic, Ansys, and Hypermesh were applied to establish three-dimensional finite element models of the pharyngeal cavity, upper palate, and levator veli palatini muscle in patients with unilateral complete cleft palate. The parameters including length, angle, and cross-sectional area of the levator veli palatini muscle etc. were measured in Mimics, and two surgical procedures that two-flap method and Furlow reverse double Z method were simulated in Ansys, and the area of pharyngeal cavity was measured by hypermesh.

RESULTS

A three-dimensional finite element model of the upper palate, pharyngeal cavity, and bilateral levator veli palatini muscle was established in patients with unilateral complete cleft palate ; The concept of horizontal projection characteristics of the palatal dome was applied to the finite element simulation of cleft palate surgery, vividly simulating the displacement and elastic stretching of the two flap method and Furlow reverse double Z method during the surgical process; The areas with the highest stress in the two-flap method and Furlow reverse double Z method both occur in the hard soft palate junction area; In resting state, as measured, the two flap method can narrow the pharyngeal cavity area by 50.9%, while the Furlow reverse double Z method can narrow the pharyngeal cavity area by 65.4%; The measurement results of the levator veli palatini muscle showed no significant difference compared to previous studies, confirming the accuracy of the model.

CONCLUSIONS

The finite element method was used to establish a model to simulate the surgical procedure, which is effective and reliable. The area with the highest postoperative stress for both methods is the hard soft palate junction area, and the stress of the Furlow reverse double Z method is lower than that of the two-flap method. The anatomical conditions of pharyngeal cavity of Furlow reverse double Z method are better than that of two-flap method in the resting state.

CLINICAL RELEVANCE

This article uses three-dimensional finite element method to simulate the commonly used two-flap method and Furlow reverse double Z method in clinical cleft palate surgery, and analyzes the stress distribution characteristics and changes in pharyngeal cavity area of the two surgical methods, in order to provide a theoretical basis for the surgeon to choose the surgical method and reduce the occurrence of complications.

Engineering periodontal tissue interfaces using multiphasic scaffolds and membranes for guided bone and tissue regeneration

Periodontal diseases are one of the greatest healthcare burdens worldwide. The periodontal tissue compartment is an anatomical tissue interface formed from the periodontal ligament, gingiva, cementum, and bone. This multifaceted composition makes tissue engineering strategies challenging to develop due to the interface of hard and soft tissues requiring multiphase scaffolds to recreate the native tissue architecture. Multilayer constructs can better mimic tissue interfaces due to the individually tuneable layers. They have different characteristics in each layer, with modulation of mechanical properties, material type, porosity, pore size, morphology, degradation properties, and drug-releasing profile all possible. The greatest challenge of multilayer constructs is to mechanically integrate consecutive layers to avoid delamination, especially when using multiple manufacturing processes. Here, we review the development of multilayer scaffolds that aim to recapitulate native periodontal tissue interfaces in terms of physical, chemical, and biological characteristics. Important properties of multiphasic biodegradable scaffolds are highlighted and summarised, with design requirements, biomaterials, and fabrication methods, as well as post-treatment and drug/growth factor incorporation discussed.

Ultrasonography-Derived Elasticity Estimation of Live Porcine Oral Mucosa

OBJECTIVES

To investigate the biomechanical properties of porcine oral tissues with in vivo ultrasonography and to compare the difference between oral alveolar mucosa and gingival tissue concerning compressional and tensile mechanical strain.

MATERIALS AND METHODS

Sinclair minipigs (6 females and 4 males, 6 to 18 months of age) were anesthetized for ultrasonography. In vivo high-frequency tissue harmonic ultrasound (12/24 MHz) cine-loops were obtained while inducing mechanical tissue stress (0 to 1 N). Post-processing strain analysis was performed in a cardiac speckle tracking software (EchoInsight®). Region of interest (ROI) was placed for gingival and alveolar mucosa tissues for longitudinal (compressional) and tensile strain analyses. A calibrated gel pad was employed to determine the absolute force (pressure) for the measured tissue strain response function. The resulting elasticity data was statistically analyzed using custom Matlab scripts.

RESULTS

In total, 38 sonography cine-loops around the third premolars were included in the investigation. The longitudinal strain of alveolar mucosaε AM L was found to be significantly (P < .05) larger than that of gingivaε G L . Across the measured force range,ε AM L  ~ 1.7 × ε G L . Significant differences between alveolar mucosa and gingiva tissues were found for all forces. The tensile strain of the alveolar mucosaε AM T was found to be ~2 × ε G T (on the epithelial surface of the gingiva). Both were statistically significantly different for forces exceeding ~0.08 N. At depth, that is, 500 and 1000 μm below the epithelial surface, the gingiva was found to have less ability to stretch contrary to the alveolar mucosa. Gingival tissue at 500 μm depth has significantly less tensile strain than at its surface and more than at 1000 μm depth. In contrast, the tensile strain of alveolar mucosa is largely independent of depth.

CONCLUSION

Ultrasonography can reveal significant differences in oral alveolar mucosal and gingival elastic properties, such as compressional and tensile strain. Under minute forces equivalent to 10 to 40 g, these differences can be observed. As dental ultrasound is a chairside, and noninvasive modality, obtaining real-time images might soon find clinical utility as a new diagnostic tool for the objective and quantitative assessment of periodontal and peri-implant soft tissues in clinical and research realms. As ultrasound is a safe modality with no known bioeffects, longitudinal monitoring of areas of concern would be particularly attractive.

All-in-one porous membrane enables full protection in guided bone regeneration

The sophisticated hierarchical structure that precisely combines contradictory mechanical and biological characteristics is ideal for biomaterials, but it is challenging to achieve. Herein, we engineer a spatiotemporally hierarchical guided bone regeneration (GBR) membrane by rational bilayer integration of densely porous N-halamine functionalized bacterial cellulose nanonetwork facing the gingiva and loosely porous chitosan-hydroxyapatite composite micronetwork facing the alveolar bone. Our GBR membrane asymmetrically combine stiffness and flexibility, ingrowth barrier and ingrowth guiding, as well as anti-bacteria and cell-activation. The dense layer has a mechanically matched space maintenance capacity toward gingiva, continuously blocks fibroblasts, and prevents bacterial invasion with multiple mechanisms including release-killing, contact-killing, anti-adhesion, and nanopore-blocking; the loose layer is ultra-soft to conformally cover bone surfaces and defect cavity edges, enables ingrowth of osteogenesis-associated cells, and creates a favorable osteogenic microenvironment. As a result, our all-in-one porous membrane possesses full protective abilities in GBR.

Electrospun methacrylated natural/synthetic composite membranes for gingival tissue engineering

New functional materials for engineering gingival tissue are still in the early stages of development. Materials for such applications must maintain volume and have advantageous mechanical and biological characteristics for tissue regeneration, to be an alternative to autografts, which are the current benchmark of care. In this work, methacrylated gelatin (GelMa) was photocrosslinked with synthetic immunomodulatory methacrylated divinyl urethanes and defined monomers to generate composite scaffolds. Using a factorial design, with the synthetic monomers of a degradable polar/hydrophobic/ionic polyurethane (D-PHI) and GelMa, composite materials were electrospun with polycarbonate urethane (PCNU) and light-cured in-flight. The materials had significantly different relative hydrophilicities, with unique biodegradation profiles associated with specific formulations, thereby providing good guidance to achieving desired mechanical characteristics and scaffold resorption for gingival tissue regeneration. In accelerated esterase/collagenase degradation models, the new materials exhibited an initial rapid weight loss followed by a more gradual rate of degradation. The degradation profile allowed for the early infiltration of human adipose-derived stromal/stem cells, while still enabling the graft's structural integrity to be maintained. In conclusion, the materials provide a promising candidate platform for the regeneration of oral soft tissues, addressing the requirement of viable tissue infiltration while maintaining volume and mechanical integrity. STATEMENT OF SIGNIFICANCE: There is a need for the development of more functional and efficacious materials for the treatment of gingival recession. To address significant limitations in current material formulations, we sought to investigate the development of methacrylated gelatin (GelMa) and oligo-urethane/methacrylate monomer composite materials. A factorial design was used to electrospin four new formulations containing four to five monomers. Synthetic immunomodulatory monomers were crosslinked with GelMa and electrospun with a polycarbonate urethane resulting in unique mechanical properties, and resorption rates which align with the original design criteria for gingival tissue engineering. The materials may have applications in tissue engineering and can be readily manufactured. The findings of this work may help better direct the efforts of tissue engineering and material manufacturing.

Recent trends and perspectives in reconstruction and regeneration of intra/extra-oral wounds using tissue-engineered oral mucosa equivalents

Many conditions, including cancer, trauma, and congenital anomalies, can damage the oral mucosa. Multiple cultures of oral mucosal cells have been used for biocompatibility tests and oral biology studies. In recent decades, the clinical translation of tissue-engineered products has progressed significantly in developing tangible therapies and inspiring advancements in medical science. However, the reconstruction of an intraoral mucosa defect remains a significant challenge. Despite the drawbacks of donor-site morbidity and limited tissue supply, the use of autologous oral mucosa remains the gold standard for oral mucosa reconstruction and repair. Tissue engineering offers a promising solution for repairing and reconstructing oral mucosa tissues. Cell- and scaffold-based tissue engineering approaches have been employed to treat various soft tissue defects, suggesting the potential clinical use of tissue-engineered oral mucosa (TEOMs). In this review, we first cover the recent trends in the reconstruction and regeneration of extra-/intra-oral wounds using TEOMs. Next, we describe the current status and challenges of TEOMs. Finally, future strategic approaches and potential technologies to support the advancement of TEOMs for clinical use are discussed.

Effect of polydeoxyribonucleotide with xenogeneic collagen matrix on gingival phenotype modification: a pilot preclinical study

PURPOSE

To investigate the effect of xenogeneic collagen matrix (XCM) with polydeoxyribonucleotide (PDRN) for gingival phenotype modification compared to autogenous connective tissue graft.

METHODS

Five mongrel dogs were used in this study. Box-type gingival defects were surgically created bilaterally on the maxillary canines 8 weeks before gingival augmentation. A coronally positioned flap was performed with either a subepithelial connective tissue graft (SCTG) or XCM with PDRN (2.0 mg/mL). The animals were sacrificed after 12 weeks. Intraoral scanning was performed for soft tissue analysis, and histologic and histomorphometric analyses were performed.

RESULTS

One animal exhibited wound dehiscence, leaving 4 for analysis. Superimposition of STL files revealed no significant difference in the amount of gingival thickness increase (ranging from 0.69±0.25 mm to 0.80±0.31 mm in group SCTG and from 0.48±0.25 mm to 0.85±0.44 mm in group PDRN; P>0.05). Histomorphometric analysis showed no significant differences between the groups in supracrestal gingival tissue height, keratinized tissue height, tissue thickness, and rete peg density (P>0.05).

CONCLUSIONS

XCM soaked with PDRN yielded comparable gingival augmentation to SCTG.

Intraoral medical devices for sustained drug delivery

OBJECTIVES

The oral cavity constitutes an attractive organ for the local and systemic application of drug substances. Oromucosal tablets, gels, or sprays are examples of the formulations applied. Due to the elution through the saliva, the residence time of the formulation at the application site is relatively short. Medical devices placed in the oral cavity, with a reservoir for an active substance, play an important role in solving this problem.

MATERIALS AND METHODS

In this review, we discuss the devices described in the literature that are designed to be used in the oral cavity, highlighting the advantages, disadvantages, and clinical applications of each of them.

RESULTS

Among the intraoral medical devices, special types are personalized 3D-printed devices, iontophoretic devices, and microneedle patches.

CONCLUSION

We anticipate that with the development of 3D printing and new polymers, the technology of flexible and comfortable devices for prolonged drug delivery in the oral cavity will develop intensively.

CLINICAL RELEVANCE

The presented review is therefore a useful summary of the current technological state, when in fact none of the existing devices has been widely accepted clinically.

The Impact of the Addition of Vitamins on a Silicone Lining Material to the Oral Mucosa Tissue-Evaluation of the Biocompatibility, Hydrolytic Stability and Histopathological Effect

Background and Objectives: One's quality of life depends on overall health, and in particular, oral health, which has been and continues to become a public health issue through frequent manifestations in various forms, from simple oral stomatitis (inflammations of the oral cavity) to the complicated oral health pathologies requiring medical interventions and treatments (caries, pulp necrosis and periodontitis). The aim of this study focused on the preparation and evaluation of vitamins (vitamin A, B1 and B6) incorporated into several silicone-based lining materials as a new alternative to therapeutically loaded materials designed as oral cavity lining materials in prosthodontics. Materials and Methods: Silicone-based liners containing vitamins were prepared by mixing them in solution and becoming crosslinked, and then they were characterized using Fourier-transform infrared (FT-IR) spectroscopy to confirm the incorporation of the vitamins into the silicone network; scanning electron microscopy (SEM) to evidence the morphology of the liner materials; dynamic vapor sorption (DVS) to evaluate their internal hydrophobicity, swelling in environments similar to biological fluids and mechanical test to demonstrate tensile strength; MTT to confirm their biocompatibility on normal cell cultures (fibroblast) and mucoadhesivity; and histopathological tests on porcine oral mucosa to highlight their potential utility as soft lining materials with improved efficiency. Results: FT-IR analysis confirmed the structural peculiarities of the prepared lining materials and the successful incorporation of vitamins into the silicone matrix. The surface roughness of the materials was lower than 0.2 μm, while in cross-section, the lining materials showed a compact morphology. It was found that the presence of vitamins induced a decrease in the main mechanical parameters (strength and elongation at break, Young's modulus) and hydrophobicity, which varied from one vitamin to another. A swelling degree higher than 8% was found in PBS 6.8 (artificial saliva) and water. Hydrolytic stability studies in an artificial saliva medium showed the release of low concentrations of silicone and vitamin fragments in the first 24 h, which increased the swelling behavior of the materials, diffusion and solubility of the vitamins. The microscopic images of fibroblast cells incubated with vitamin liners revealed very good biocompatibility. Also, the silicone liners incorporating the vitamins showed good mucoadhesive properties. The appearance of some pathological disorders with autolysis processes was more pronounced in the case of vitamin A liners. Conclusions: The addition of the vitamins was shown to have a beneficial effect that was mainly manifested as increased biocompatibility, hydrolytic stability and mucoadhesiveness with the mucosa of the oral cavity and less of an effect on the mechanical strength. The obtained lining materials showed good resistance in simulated biological media but caused a pronounced autolysis phenomenon, as revealed by histopathological examination, showing that these materials may have broad implications in the treatment of oral diseases.

Undergraduate medical student perceptions and learning outcomes related to anatomy training using Thiel- and ethanol-glycerin-embalmed tissues

Anatomical dissection is known to serve as an integral tool in teaching gross anatomy, including postgraduate training. A variety of embalming techniques exist, resulting in different haptic and optical tissue properties. This study aimed to objectify learning outcomes and medical student perceptions related to the use of two widely used embalming techniques, namely Thiel and ethanol-glycerin embalming. Between 2020 and 2022, first- and second-year medical students enrolled in the course on topographic anatomy participated in this study. Objective structured practical examinations were carried out for the head, neck, thorax, abdomen, pelvis, and extremity regions following regional dissection just before the oral examinations began. Six to ten numbered tags were marked in prosections of each region in Thiel- and ethanol-glycerin-embalmed specimens. Following the examinations, the students were surveyed regarding the suitability of the two embalming techniques with respect to preservation, colorfastness, tissue pliability, and the suitability in preparing for their anatomy examinations. Consistently higher scores were achieved for the thoracic and abdominal regions in ethanol-glycerin-embalmed specimens when compared to Thiel. No benefit was found for Thiel-embalmed upper or lower extremities. Tissues embalmed with ethanol-glycerin were rated higher for preservation and suitability to achieve the learning objectives, tissue pliability was rated higher for Thiel-embalmed tissues. Ethanol-glycerin embalming appears to offer certain advantages for undergraduate students in recognizing visceral structures, which may align with students' ideas on tissue suitability for their learning. Consequently, the benefits reported for Thiel embalming for postgraduate study unlikely reflect its suitability for novices.

Biomaterials derived from hard palate mucosa for tissue engineering and regenerative medicine

Autologous materials have superior biosafety and are widely used in clinical practice. Due to its excellent trauma-healing ability, the hard palate mucosa (HPM) has become a hot spot for autologous donor area research. Multiple studies have conducted an in-depth analysis of the healing ability of the HPM at the cellular and molecular levels. In addition, the HPM has good maneuverability as a donor area for soft tissue grafts, and researchers have isolated various specific mesenchymal stem cells (MSCs) from HPM. Free soft tissue grafts obtained from the HPM have been widely used in the clinic and have played an essential role in dentistry, eyelid reconstruction, and the repair of other specific soft tissue defects. This article reviews the advantages of HPM as a donor area and its related mechanisms, classes of HPM-derived biomaterials, the current status of clinical applications, challenges, and future development directions.

Can we achieve biomimetic electrospun scaffolds with gelatin alone?

Introduction: Gelatin is a natural polymer commonly used in biomedical applications in combination with other materials due to its high biocompatibility, biodegradability, and similarity to collagen, principal protein of the extracellular matrix (ECM). The aim of this study was to evaluate the suitability of gelatin as the sole material to manufacture tissue engineering scaffolds by electrospinning. Methods: Gelatin was electrospun in nine different concentrations onto a rotating collector and the resulting scaffold's mechanical properties, morphology and topography were assessed using mechanical testing, scanning electron microscopy and white light interferometry, respectively. After characterizing the scaffolds, the effects of the concentration of the solvents and crosslinking agent were statistically evaluated with multivariate analysis of variance and linear regressions. Results: Fiber diameter and inter-fiber separation increased significantly when the concentration of the solvents, acetic acid (HAc) and dimethyl sulfoxide (DMSO), increased. The roughness of the scaffolds decreased as the concentration of dimethyl sulfoxide increased. The mechanical properties were significantly affected by the DMSO concentration. Immersed crosslinked scaffolds did not degrade until day 28. The manufactured gelatin-based electrospun scaffolds presented comparable mechanical properties to many human tissues such as trabecular bone, gingiva, nasal periosteum, oesophagus and liver tissue. Discussion: This study revealed for the first time that biomimetic electrospun scaffolds with gelatin alone can be produced for a significant number of human tissues by appropriately setting up the levels of factors and their interactions. These findings also extend statistical relationships to a form that would be an excellent starting point for future research that could optimize factors and interactions using both traditional statistics and machine learning techniques to further develop specific human tissue.

Viscoelastic behavior of oral mucosa. A rheological study using small-amplitude oscillatory shear tests

The purpose of this work was to determine the viscoelastic behavior of porcine and human oral mucosa under physiological conditions of temperature, hydration and chewing. The linear elastic and viscous shear moduli of these soft tissues were determined by small-amplitude oscillatory shear (SAOS) tests at masticatory frequency using a stress-controlled rheometer equipped with an immersion cell on punched biopsies 8 mm in diameter. Non physiological conditions of temperature were also used to access other parameters such as the denaturation temperature of collagen. First, the different parameters such as normal force, frequency and maximal strain were adjusted to obtain reliable data on porcine mucosa. The optimal normal force was 0.1N and the linear viscoelastic limit was found for a strain amplitude of 0.5% for both 0.1 and 1 Hz. The storage moduli of porcine mucosa, ranging from 5 to 16 kPa, were in the same range as cutaneous tissues determined by SAOS at equivalent frequencies. The storage modulus, superior to the loss modulus G″, indicates a predominant elastic contribution to shear stress in chewing conditions. Second, this protocol evidenced an influence of the anatomic site of the mouth on the viscoelastic behavior of porcine mucosa, mandibular biopsies having higher storage moduli than maxillary biopsies. Temperature scans showed the mechanical manifestation of collagen denaturation in the 60-70 °C range as previous calorimetric analyses. Finally, this mechanical protocol was successfully adapted to characterize human mucosa in an elderly population. It was shown that the elastic modulus is impacted by local inflammation (gingivitis), decreasing significantly from 6 ± 1.4 kPa to 2.5 ± 0.3 kPa.

Incorporation of Magnesium and Zinc Metallic Particles in PLGA Bi-layered Membranes with Sequential Ion Release for Guided Bone Regeneration

Guided bone regeneration (GBR) membranes are commonly used for periodontal tissue regeneration. Due to the complications of existing GBR membranes, the design of bioactive membranes is still relevant. GBR membranes with an asymmetric structure can accommodate the functional requirements of different interfacial tissues. Here, poly(lactic acid-glycolic acid) (PLGA) was selected as the matrix for preparing a bi-layered membrane with both dense and porous structure. The dense layer for blocking soft tissues was incorporated with zinc (Zn) particles, while the porous layer for promoting bone regeneration was co-incorporated with magnesium (Mg) and Zn particles. Mg/Zn-embedded PLGA membranes exhibited 166% higher mechanical strength in comparison with pure PLGA membranes and showed suitable degradation properties with a sequential ion release behavior of Mg²⁺ first and continuously Zn²⁺. More importantly, the release of Zn²⁺ from bi-layered PLGA endowed GBR membranes with excellent antibacterial activity (antibacterial rate > 69.3%) as well as good cytocompatibility with MC3T3-E1 (mouse calvaria pre-osteoblastic cells) and HGF-1 (human gingival fibroblast cells). Thus, the asymmetric bi-layered PLGA membranes embedded with Mg and Zn particles provide a simple and effective strategy to not only reinforce the PLGA membrane but also endow membranes with osteogenic and antibacterial activity due to the continuous ion release profile, which serves as a promising candidate for use in GBR therapy.

Epidermal Potentiation of Dermal Fibrosis: Lessons from Occlusion and Mucosal Healing

Fibrotic skin conditions, such as hypertrophic and keloid scars, frequently result from injury to the skin and as sequelae to surgical procedures. The development of skin fibrosis may lead to patient discomfort, limitation in range of motion, and cosmetic disfigurement. Despite the frequency of skin fibrosis, treatments that seek to address the root causes of fibrosis are lacking. Much research into fibrotic pathophysiology has focused on dermal pathology, but less research has been performed to understand aberrations in fibrotic epidermis, leading to an incomplete understanding of dermal fibrosis. The literature on occlusion, a treatment modality known to reduce dermal fibrosis, in part through accelerating wound healing and regulating aberrant epidermal inflammation that otherwise drives fibrosis in the dermis, is reviewed. There is a focus on epidermal-dermal crosstalk, which contributes to the development and maintenance of dermal fibrosis, an underemphasized interplay that may yield novel strategies for treatment if understood in more detail.

Finite element analysis of stress in oral mucosa and titanium mesh interface

BACKGROUND

The stiffness of titanium mesh is a double-blade sword to repair larger alveolar ridges defect with excellent space maintenance ability, while invade the surrounding soft tissue and lead to higher mesh exposure rates. Understanding the mechanical of oral mucosa/titanium mesh/bone interface is clinically meaningful. In this study, the above relationship was analyzed by finite elements and verified by setting different keratinized tissue width in oral mucosa.

METHODS

Two three-dimensional finite element models were constructed with 5 mm keratinized tissue in labial mucosa (KM cases) and 0 mm keratinized tissue in labial mucosa (LM cases). Each model was composed of titanium mesh, titanium screws, graft materials, bone, teeth and oral mucosa. After that, a vertical (30 N) loadings were applied from both alveolar ridges direction and labial mucosa direction to stimulate the force from masticatory system. The displacements and von Mises stress of each element at the interfaces were analyzed.

RESULTS

Little displacements were found for titanium mesh, titanium screws, graft materials, bone and teeth in both LM and KM cases under different loading conditions. The maximum von Mises stress was found around the lingual titanium screw insertion place for those elements in all cases. The keratinized tissue decreased the displacement of oral mucosa, decreased the maximum von Mises stress generated by an alveolar ridges direction load, while increased those stress from labial mucosa direction load. Only the von Mises stress of the KM cases was all lower than the tensile strength of the oral mucosa.

CONCLUSION

The mucosa was vulnerable under the increasing stress generated by the force from masticatory system. The adequate buccal keratinized mucosa width are critical factors in reducing the stress beyond the titanium mesh, which might reduce the titanium exposure rate.

Full-Thickness Oral Mucoperiosteal Defects: Challenges and Opportunities

Regenerative engineering strategies for the oral mucoperiosteum, as may be needed following surgeries, such as cleft palate repair and tumor resection, are underdeveloped compared with those for maxillofacial bone. However, critical-size tissue defects left to heal by secondary intention can lead to complications, such as infection, fistula formation, scarring, and midface hypoplasia. This review describes current clinical practice for replacing mucoperiosteal tissue, including autografts and allografts. Potentially paradigm-shifting experimental regenerative engineering strategies for mucoperiosteal wound healing, such as hybrid grafts and engineered matrices, are also discussed. Throughout the review, the advantages and disadvantages of each replacement or regeneration strategy are outlined in the context of clinical outcomes, quality of life for the patient, availability of materials, and cost of care. Finally, future directions for research and development in the area of mucoperiosteum repair are proposed, with an emphasis on identifying globally available and affordable solutions for promoting mucoperiosteal regeneration. Impact statement Unassisted oral mucoperiosteal wound healing can lead to severe complications such as infection, fistulae, scarring, and developmental abnormalities. Thus, strategies for promoting wound healing must be considered when mucoperiosteal defects are incident to oral surgery, as in palatoplasty or tumor resection. Emerging mucoperiosteal tissue engineering strategies, described in this study, have the potential to overcome the limitations of current standard-of-care donor tissue grafts. For example, the use of engineered mucoperiosteal biomaterials could circumvent concerns about tissue availability and immunogenicity. Moreover, employment of tissue engineering strategies may improve the equity of oral wound care by increasing global affordability and accessibility of materials.

A Novel Alveolar Distractor Incorporating Nickel-Titanium Alloy Springs: A Preliminary In Vitro Study

A new design of an alveolar distractor using nickel−titanium (NiTi) open-coil springs was developed and investigated to produce distraction forces against the tensile forces of porcine attached gingiva to simulate human gingiva. We subjected 15 mm long NiTi open-coil springs (Highland and ORMCO) with three levels of forces (light, medium and heavy) to mechanical testing in a 37 ± 1 °C water bath. Ten strips of porcine mandibular attached gingiva were subjected to tensile tests to determine the resistance force. The forces from the springs were compared with the tensile forces from the porcine attached gingiva. Data between groups were analyzed with independent-samples T-tests (p-value < 0.05). The tensile strength and the Young modulus were greater in buccal compared to lingual porcine attached gingiva. Compared to other spring dimensions and companies, forces generated from 0.014 × 0.036″ ORMCO springs were the highest and could overcome the tensile resistance from porcine attached gingiva over the longest distraction range of 1.6 mm. This preliminary in vitro study introduced a new design of an alveolar distractor incorporated with NiTi open-coil springs that could generate light and continuous forces to overcome the resistance from porcine attached gingiva.

Numerical study of the stress state on the oral mucosa and abutment tooth upon insertion of partial dentures in the mandible

The introduction of a removable partial denture onto the dental arch significantly influences the mechanical stress characteristics of both the jawbone and oral mucosa. The aim of this study was to analyze the stress state caused by biting forces upon insertion of partial dentures into the assembly, and to understand the influence of the resulting contact pressure on its retention behavior. For this purpose, a numerical model of a removable partial denture is proposed based on 3D models developed using computer tomography data of the jawbone and the removable partial denture. The denture system rests on the oral mucosa surface and three abutment teeth. The application of bite forces on the denture generated a stick condition on the loaded regions of the denture-oral mucosa interface, which indicates positive retention of the denture onto the oral mucosa surface. Slip and negative retention were observed in the regions of the contact space that were not directly loaded. The contact pressures observed in the regions of the oral mucosa in contact with the denture were below the clinical pressure pain threshold value for soft tissue, which potentially lowers the risk of pain being experienced by denture users. Further, the variation of the retention behavior and contact pressures across different regions of the denture assembly was observed. Thus, there is a need for adhesives or restraining mechanisms for the denture system in order to avoid bending and deformation of sections of the denture as a consequence of the applied bite force.

The Structure and Function of Next-Generation Gingival Graft Substitutes-A Perspective on Multilayer Electrospun Constructs with Consideration of Vascularization

There is a shortage of suitable tissue-engineered solutions for gingival recession, a soft tissue defect of the oral cavity. Autologous tissue grafts lead to an increase in morbidity due to complications at the donor site. Although material substitutes are available on the market, their development is early, and work to produce more functional material substitutes is underway. The latter materials along with newly conceived tissue-engineered substitutes must maintain volumetric form over time and have advantageous mechanical and biological characteristics facilitating the regeneration of functional gingival tissue. This review conveys a comprehensive and timely perspective to provide insight towards future work in the field, by linking the structure (specifically multilayered systems) and function of electrospun material-based approaches for gingival tissue engineering and regeneration. Electrospun material composites are reviewed alongside existing commercial material substitutes', looking at current advantages and disadvantages. The importance of implementing physiologically relevant degradation profiles and mechanical properties into the design of material substitutes is presented and discussed. Further, given that the broader tissue engineering field has moved towards the use of pre-seeded scaffolds, a review of promising cell options, for generating tissue-engineered autologous gingival grafts from electrospun scaffolds is presented and their potential utility and limitations are discussed.

Accuracy evaluation of 3D-printed noninvasive adhesive marker for dynamic navigation implant surgery in a maxillary edentulous model: An in vitro study

Dynamic computer-aided implant surgery (DCAIS) can improve dental implantation accuracy and reduce surgical risks. In the registration procedure of DCAIS, the type and the number of registration markers significantly impact the accuracy of DCAIS. One problem of DCAIS in clinical application is that only invasive screw markers can be used for implantation in edentulous patients. It could cause additional trauma, scar formation and usually increase patient discomfort. In this experiment, a personalized 3D-printed edentulous maxillary model was used for simulating clinical situations, and a 3D-printed noninvasive adhesive marker (3D-PNAM) was designed to figure out the above problem. In this research, six target screws were implanted into the model's maxillary alveolar ridge as targets for accuracy analysis. This study used target registration error (TRE) as an index to evaluate the accuracy of invasive screw makers and noninvasive adhesive markers. Results showed that 3D-PNAMs had the same accuracy as screw markers, and placing at least six registration markers in the maxilla was needed for good registration accuracy. The registration markers should be further improved and designed according to application areas' clinical needs and anatomical characteristics in future clinical studies.

Predicting thickness perception of liquid food products from their non-Newtonian rheology

The "mouthfeel" of food products is a key factor in our perception of food quality and in our appreciation of food products. Extensive research has been performed on what determines mouthfeel, and how it can be linked to laboratory measurements and eventually predicted. This was mainly done on the basis of simple models that do not accurately take the rheology of the food products into account. Here, we show that the subjectively perceived "thickness" of liquid foods, or the force needed to make the sample flow or deform in the mouth, can be directly related to their non-Newtonian rheology. Measuring the shear-thinning rheology and modeling the squeeze flow between the tongue and the palate in the oral cavity allows to predict how a panel perceives soup "thickness". This is done for various liquid bouillons with viscosities ranging from that of water to low-viscous soups and for high-viscous xanthan gum solutions. Our findings show that our tongues, just like our eyes and ears, are logarithmic measuring instruments in agreement with the Weber-Fechner law that predicts a logarithmic relation between stimulus amplitude and perceived strength. Our results pave the way for more accurate prediction of mouthfeel characteristics of liquid food products.

Mechanical properties of whole-body soft human tissues: a review

The mechanical properties of soft tissues play a key role in studying human injuries and their mitigation strategies. While such properties are indispensable for computational modelling of biological systems, they serve as important references in loading and failure experiments, and also for the development of tissue simulants. To date, experimental studies have measured the mechanical properties of peripheral tissues (e.g. skin)in-vivoand limited internal tissuesex-vivoin cadavers (e.g. brain and the heart). The lack of knowledge on a majority of human tissues inhibit their study for applications ranging from surgical planning, ballistic testing, implantable medical device development, and the assessment of traumatic injuries. The purpose of this work is to overcome such challenges through an extensive review of the literature reporting the mechanical properties of whole-body soft tissues from head to toe. Specifically, the available linear mechanical properties of all human tissues were compiled. Non-linear biomechanical models were also introduced, and the soft human tissues characterized using such models were summarized. The literature gaps identified from this work will help future biomechanical studies on soft human tissue characterization and the development of accurate medical models for the study and mitigation of injuries.

Comprehensive Evaluation of PAXgene Fixation on Oral Cancer Tissues Using Routine Histology, Immunohistochemistry, and FTIR Microspectroscopy

The choice of tissue fixation is critical for preserving the morphology and biochemical information of tissues. Fragile oral tissues with lower tensile strength are challenging to process for histological applications as they are prone to processing damage, such as tissue tear, wrinkling, and tissue fall-off from slides. This leads to loss of morphological information and unnecessary delay in experimentation. In this study, we have characterized the new PAXgene tissue fixation system on oral buccal mucosal tissue of cancerous and normal pathology for routine histological and immunohistochemical applications. We aimed to minimize the processing damage of tissues and improve the quality of histological experiments. We also examined the preservation of biomolecules by PAXgene fixation using FTIR microspectroscopy. Our results demonstrate that the PAXgene-fixed tissues showed significantly less tissue fall-off from slides. Hematoxylin and Eosin staining showed comparable morphology between formalin-fixed and PAXgene-fixed tissues. Good quality and slightly superior immunostaining for cancer-associated proteins p53 and CK5/6 were observed in PAXgene-fixed tissues without antigen retrieval than formalin-fixed tissues. Further, FTIR measurements revealed superior preservation of glycogen, fatty acids, and amide III protein secondary structures in PAXgene-fixed tissues. Overall, we present the first comprehensive evaluation of the PAXgene tissue fixation system in oral tissues. This study concludes that the PAXgene tissue fixation system can be applied to oral tissues to perform diagnostic molecular pathology experiments without compromising the quality of the morphology or biochemistry of biomolecules.

Biomechanical Properties of Bone and Mucosa for Design and Application of Dental Implants

Dental implants’ success comprises their proper stability and adherence to different oral tissues (integration). The implant is exposed to different mechanical stresses from swallowing, mastication and parafunctions for a normal tooth, leading to the simultaneous mechanical movement and deformation of the whole structure. The knowledge of the mechanical properties of the bone and gingival tissues in normal and pathological conditions is very important for the successful conception of dental implants and for clinical practice to access and prevent potential failures and complications originating from incorrect mechanical factors’ combinations. The challenge is that many reported biomechanical properties of these tissues are substantially scattered. This study carries out a critical analysis of known data on mechanical properties of bone and oral soft tissues, suggests more convenient computation methods incorporating invariant parameters and non-linearity with tissues anisotropy, and applies a consistent use of these properties for in silico design and the application of dental implants. Results show the advantages of this approach in analysis and visualization of stress and strain components with potential translation to dental implantology.

Investigation of dental elastomers as oral mucosa simulant materials

Objective

To measure mechanical properties of dental soft liners in tensional stress to identify their suitability as human oral mucosa simulant materials.

Methods

Eleven different dental elastomers were subjected to tensile testing to obtain their tensile strength and elastic moduli (n = 15/group) according to the ISO‐527 method. Fractured surfaces of one specimen per sample group were examined under the light microscope and scanning electron microscope (SEM). Energy‐dispersive X‐ray spectroscopy (EDS) was performed for the elemental analysis or chemical characterization of each sample group. The obtained data were quantitatively and qualitatively analysed. They were also statistically analysed using SPSS version 25.

Results

The tensile strength of dental elastomers ranged from 0.43 MPa (±0.09) to 7.41 MPa (±1.11) and had statistically significant differences between tested groups (p = 0.001). Vertex soft heat‐cure soft liner, GC impression silicones and Silagum soft liners were found to have tensile strengths close to that of the oral mucosa reported by previous studies. SEM analysis revealed that the elastomers with higher filler contents showed rough fractured surface with plucking of particles after tensile fracture.

Conclusion

This is the first study assessing the suitability of dental elastomers as human oral mucosa simulant materials which can be used for in vitro, mathematical modeling and finite element analysis (FEA) to study masticatory force distribution in oral mucosa. Out of 11 studied, six (Vertex Soft, GC heavy and Light body, Molloplast B, Algin X Ultra and Exaclear) dental elastomers showed similar mechanical properties to the Theil embalmed gingival tissues. Vertex Soft, GC Light body, and Molloplast B may be used for the majority of oral mucosal model when considering tensile strength as the primary factor for mechanical stimulation.

Modern view on mechanisms of epithelium differentiation of the oral mucosa in normal and pathological processes

Background:In everyday clinical practice, patients who seek dental care in case of oral mucosa diseases are one of the most difficult categories of patients due to difficulties in diagnosis and treatment. Materials and methods: The review and analysis of scientific and medical literature based on the Scopus, Web of Science, MedLine, PubMed, NCBI databases, the study of which does not exceed 5 years, including literature reviews and the results of clinical trials. Results: Changes in the oral mucosa can be clearly specific. Clinicians can make the correct diagnosis and determine the tactics of treatment by appearance. However, in most cases the diagnosis of diseases with this anatomical location is complicated, because the clinical picture is nonspecific and often burdened with additional local and general adverse factors. A detailed clinical examination and additional research methods are required to establish the correct diagnosis. Diagnosis of oral mucosa diseases is based on a careful assessment of clinical and laboratory data. Conclusions: Taking into account the prevalence of diseases of the oral mucosa, of particular interest is the question of the course of the process of differentiation of the epithelium of various anatomical zones in the norm and the mechanisms of restructuring of the cellular composition in pathological processes, with the cops of objectifying the diagnosis, predicting the course of the disease and pathogenetically substantiated treatment.

Mechanical properties of human oral mucosa tissues are site dependent: A combined biomechanical, histological and ultrastructural approach

Aim

To investigate load‐deformation properties of Thiel‐embalmed human oral mucosa tissues and to compare three different anatomical regions in terms of mechanical, histological and ultrastructural characteristic with focus on the extracellular matrix.

Materials and Methods

Thirty specimens from three different regions of the oral cavity: attached gingiva, buccal mucosa and the hard palate were harvested from two Thiel‐embalmed cadavers. Mechanical properties were obtained, combining strain evaluation and digital image correlation in a standardised approach. Elastic modulus, tensile strength, strain at maximum load and strain to failure were computed and analysed statistically. Subsamples were also analysed using scanning electron microscopy (SEM) and histological analysis.

Results

The highest elastic modulus of 37.36 ± 17.4 MPa was found in the attached gingiva group, followed by the hard palate and buccal mucosa. The elastic moduli of attached gingiva differed significantly to the buccal mucosa (p = .01) and hard palate (p = .021). However, there was no difference in the elastic moduli between the buccal mucosa and hard palate (p > .22). The tensile strength of the tissue samples ranged from 1.54 ± 0.5MPa to 3.81 ± 0.9 MPa, with a significant difference between gingiva group and buccal mucosa or hard palate (p = .001). No difference was found in the mean tensile strength between the buccal mucosa and hard palate (p = .92). Ultrastructural imaging yielded a morphological basis for the various mechanical properties found intraorally; the attached gingiva showed unidirectional collagen fibre network whereas the buccal mucosa and hard palate showed multi‐directional network, which was more prone to tension failure and less elasticity.

Conclusion

This is the first study assessing the various morphological‐mechanical relationships of intraoral soft tissues, utilising Thiel‐embalmed tissues. The findings of this study suggest that the tissues from different intraoral regions showed various morphological‐mechanical behaviour which was also confirmed under the SEM and in the histological analysis.