The state of systemic immunity in congenital cleft lip and palate patients with diseases of oral cavity tissues.

OBJECTIVE: Aim: To determine the state of dental health and the state of systemic immunity in patients in congenital cleft lip and palate patients. PATIENTS AND METHODS: Materials and Methods: The dental status and immunologic tests of 74 patients age 8-18 years old with congenital cleft lip and palate was analyzed: 43 children with unilateral and 31 children with bilateral complete combined cleft lip, alveolar process, hard and soft palate. RESULTS: Results: Indicators of the prevalence and intensity of the caries process in patients with congenital congenital complete cleft lip, alveolar process, hard and soft palate were high, especially in children with bilateral cleft lip and palate - the decompensated course of caries was determined in 41.93% patients, with unilateral - 23.25%. Сhronic catarrhal gingivitis was the most common in both groups of patients - the average severity of gingivitis prevailed - 51.16% with congenital unilateral cleft lip and palate and 51.61% - with bilateral. Atopic cheilitis, glossitis and chronic recurrent aphthous stomatitis were common. This patients have significant changes in the cellular chain of the immune system with a deficiency of the main phenotypes of lymphocytes - CD4+ CD8+ and inflammatory bacterial changes in blood serum. CONCLUSION: Conclusions: Patients of unilateral and bilateral complete combined cleft lip, alveolar process, hard and soft palate have significant changes in the dental status and in the cellular chain of the immune system. The level of manifestation of these changes is directly proportional to the extent of localization of the pathology - unilateral or bilateral.

Centrifugal Microfluidic Cell Culture Platform for Physiologically Relevant Virus Infection Studies: A Case Study with HSV-1 Infection of Periodontal Cells.

Static well plates remain the gold standard to study viral infections in vitro, but they cannot accurately mimic dynamic viral infections as they occur in the human body. Therefore, we established a dynamic cell culture platform, based on centrifugal microfluidics, to study viral infections in perfusion. To do so, we used human primary periodontal dental ligament (PDL) cells and herpes simplex virus-1 (HSV-1) as a case study. By microscopy, we confirmed that the PDL cells efficiently attached and grew in the chip. Successful dynamic viral infection of perfused PDL cells was monitored using fluorescent imaging and RT-qPCR-based experiments. Remarkably, viral infection in flow resulted in a gradient of HSV-1-infected cells gradually decreasing from the cell culture chamber entrance towards its end. The perfusion of acyclovir in the chip prevented HSV-1 spreading, demonstrating the usefulness of such a platform for monitoring the effects of antiviral drugs. In addition, the innate antiviral response of PDL cells, measured by interferon gene expression, increased significantly over time in conventional static conditions compared to the perfusion model. These results provide evidence suggesting that dynamic viral infections differ from conventional static infections, which highlights the need for more physiologically relevant in vitro models to study viral infections.

Macrophage Polarization during MRONJ Development in Mice.

Macrophages are important regulators of bone remodeling, and M1 polarization is observed in the setting of medication-related osteonecrosis of the jaws (MRONJ). Here, we characterize the phenotype of macrophages during early stages of MRONJ development in zoledronate (ZA)-treated mice with periodontal disease and explore the role of rosiglitazone, a drug that has been reported to lower the M1/M2 macrophage ratio, in MRONJ burden. Mice received ZA, and experimental periodontal disease (EPD) was induced around their second left maxillary molar. The mice were euthanized 1, 2, or 4 wk later. Micro-computed tomography and histologic and immunohistochemical analyses were carried out. In a separate experiment, mice were treated with ZA in the absence or presence of rosiglitazone, EPD was induced for 5 wk, and the MRONJ burden was assessed. An M1 predilection was noted in ZA versus vehicle (Veh) mice at 1, 2, or 4 wk after ligature placement. M1 cells were found to be positive for MMP-13, and their presence coincided with disruption of the surrounding collagen network in ZA mice. Rosiglitazone caused a reversal in the M1/M2 polarization in Veh and ZA mice. Rosiglitazone did not cause significant radiographic changes 5 wk after EPD in Veh or ZA animals. Importantly, percentage osteonecrosis and bone exposure were decreased in the rosiglitazone-treated versus nontreated ZA sites 5 wk after EPD. Our data point to an important role of M1 macrophage polarization with an overexpression of MMP-13 in the early phases of MRONJ development and provide insight into the use of interventional approaches promoting an M2 phenotype as a preventative means to alleviate MRONJ burden.

Condition of oral tissues in children with congenital cleft lip and palate.

OBJECTIVE: Aim: To study the condition of oral tissues in children with congenital complete cleft lip, alveolar process, hard and soft palate. PATIENTS AND METHODS: Materials and Methods: From the examined 470 children National Specialized Children's Hospital "OKHMATDYT" (Kyiv, Ukraine) with congenital cleft lip and palate was analyzed: 302 patients aged 8-18 years were subject to in-depth analysis for clinical and radiological - 192 with unilateral and 110 with bilateral complete cleft lip, alveolar process, hard and soft palate. RESULTS: Results: The average value of primary adention in patients with unilateral and bilateral complete combined cleft is 69.53%, but in females this indicator is higher and in unilateral cleft 92.18% for female against 53.17% for male. In females with unilateral cleft retention - 40.62% and overcomplete - 10,93%. The same high indicators in bilateral cleft: retention - 36.58% and overcomplete - 12.19%. Retention and overcomplete have higher values for men - 44.93% and 23.19%, respectively. Chewing efficiency in females with bilateral cleft as a result of primary dentition is below 80%. Affected by caries - 90.73% in both groups. Inflammatory processes in the periodontal tissues are revealed (80,75%): chronic catarrhal gingivitis, chronic hypertrophic gingivitis, chronic generalized periodontitis. Manifestations of atopic and angular cheilitis in 39.09% and 23.63% with bilateral cleft lip and palate, glossitis in 29.09%. CONCLUSION: Conclusions: Patients with congenital complete cleft lip, alveolar process, hard and soft palate have high rates of adentia, retention, overcomplete dentition and a wide range of diseases of the oral cavity, which negatively affects surgical and orthodontic rehabilitation.

Characteristics of HIF-1Α and HSP70 MRNA Expression, Level, and Interleukins in Experimental Chronic Generalized Periodontitis.

OBJECTIVES: Periodontal diseases are a rather complex problem of modern dentistry and do not have only medical but also social significance. The objective of this study is to weigh the effect of a mixture of Thiotriazoline and L-arginine (1:4) on the parameters of the system of endogenous cytoprotection of blood and periodontal illness in rats with experimental chronic generalized periodontitis and substantiate further study of this blend. MATERIALS AND METHODS: The study aimed to evaluate the impact of a combination of Thiotriazoline and L-arginine (in a ratio of 1:4) on the parameters of the endogenous blood cytoprotection system and periodontium in rats with experimental chronic generalized periodontitis. A group of outbred rats weighing 190-220 g and sourced from the vivarium of the Institute of Pharmacology and Toxicology of the Academy of Medical Sciences of Ukraine were divided into four groups, each consisting of 10 animals. (1) Intact group, animals that were injected intragastrically with a solution of sodium chloride to chloride 0.9% for 30 days. (2) control, animals with experimental CGP who intragastrically sodium chloride solution 0.9% for 30 days. (3) animals with experimental CGP were injected intramuscularly with Thiotriazoline + L-arginine (1:4) in a dosage of 200 mg/kg (30 days). (4) animals with experimental CGP, for which daily intragastric reference drug Mexidol, in dosage 250 mg/kg (30 days). In this study, we utilized two substances: Thiotriazoline and L-arginine hydrochloride. The combination of Thiotriazoline and L-arginine (in a ratio of 1:4) was prepared at the Department of Pharmaceutical Chemistry of ZSMU. At the conclusion of the experiment, the rats were carefully removed from the study while under thiopental-sodium anesthesia, and administered at a dosage of 40 mg/kg. RESULTS: We have found that the administration of a combined preparation of Thiotriazoline with L-arginine to rats with CGP leads to a significant decrease in the blood concentration of pro-inflammatory cytokines IL-1b and TNF-a by 56.1% and 71%, respectively. CONCLUSION: The administration of Mexidol at a dosage of 250 mg/kg, as well as the combination of Thiotriazoline and Larginine in a ratio of 1:4 at a dosage of 200 mg/kg, resulted in a significant reduction in gingival pocket depth in animals with CGP. Specifically, the gingival pocket depth was reduced to 6 mm (p < 0.05) with Mexidol and further reduced to 4 mm (p < 0.05) with the combination of Thiotriazoline and L-arginine. Additionally, the animals exhibited minimal bleeding, swelling, and tooth mobility when treated with the combination of Thiotriazoline and L-arginine. The administration of a combination of Thiotriazoline and L-arginine (in a ratio of 1:4) at a dosage of 200 mg/kg to animals with CGP resulted in a noteworthy reduction in the blood concentration of pro-inflammatory cytokines IL-1b and TNF-a. Specifically, there was a significant decrease of 56.1% (p < 0.05) in IL-1b and 71% (p < 0.05) in TNF-a levels. The course administration of a combination of Thiotriazoline and L-arginine (1:4) (200 mg/kg) to animals with CGP led to an increased expression of HSP70 mRNA (p < 0.05) in the periodontium by 8.2 times and HIF-1a mRNA by 8.2 times. 2.8 times (p < 0.05) against the background of an increase in the blood concentration of HSP70 by 95% (p < 0.05). Also, in the periodontium of animals in this group, a decrease in the expression of c-Fos mRNA by 36.7% (p < 0.05) was found compared to the control group.

Fibroblast growth factor signalling regulates the development of tooth root.

Fibroblast growth factor (FGF) signalling plays a crucial role in the morphogenesis of multiple tissues including teeth. While the role of the signal has been studied in tooth crown development, little is known about root development. Of several FGF ligands involved in hard tissue formation, we suggest that FGF18 regulates the development of murine tooth roots. We implanted FGF18-soaked heparin beads into the lower first molar tooth buds at postnatal day 6 (P6), followed by transplantation under the kidney capsule. After 3 weeks, FGF18 significantly facilitated root elongation and periodontal tissue formation compared to the control. In situ hybridisation showed that Fgf18 transcripts were initially localised in the dental pulp along Hertwig's epithelial root sheath at P6 and P10 and subsequently in the dental follicle cells at P14. Fgf receptors were expressed in various dental tissues during these stages. In vitro analysis using the dental pulp stem cells revealed that FGF18 inhibited cell proliferation and decreased expression levels of osteogenic markers, Runx2, Alpl and Sp7. Consistently, after 1 week of kidney capsule transplantation, FGF18 application did not induce the expression of Sp7 and Bsp, but upregulated Periostin in the apical region of dental mesenchyme in the grafted molar. These findings suggest that FGF18 facilitates molar root development by regulating the calcification of periodontal tissues.

Effect of piezocision-assisted lower second molar protraction on periodontal tissues, alveolar bone height, and lower second molar root resorption.

OBJECTIVES: To assess the effect of piezocision on periodontal tissues and alveolar bone height and to detect lower second molar root resorption in piezocision-assisted mandibular second molar protraction compared to no-piezocision molar protraction. MATERIALS AND METHODS: Twenty-one subjects (four males, 17 females, aged 22.43 ± 2.83 years) who presented with bilateral extraction of lower first molars were included. The patients were divided into two groups; Group 1: Piezocision-assisted molar protraction (right or left side of subjects) in which piezocision was performed immediately before lower second molar protraction and, Group 2: No-piezocision molar protraction in which lower second molar protraction was not surgically assisted. Plaque index (PI), gingival index (GI), periodontal pocket depth (PPD), width of keratinized gingiva (WKG), gingival recession (GR), lower second molar mesial root resorption, alveolar bone height, and mandibular bone height were recorded at T1 (immediately before molar protraction) and at T2 (after second molar space closure). RESULTS: In the piezocision-assisted molar protraction group, significant changes were detected in the WKG (P < .001), GR (P < .05), and the mandibular bone height (P < .001). Compared to the no-piezocision group, piezocision-assisted molar protraction resulted in an increased WKG (P < .001) and less second molar mesial root resorption (P < .01). CONCLUSIONS: Piezocision does not have any detrimental effect on the periodontium and produces less root resorption.

[The study of a diagnostic model of mucogingival deformities using high-frequency ultrasound dopplerography]. / Primenenie vysokochastotnoi ul'trazvukovoi dopplerografii u patsientov s mukogingival'nymi deformatsiyami.

OBJECTIVE: The aim of the study is to increase the effectiveness of diagnostics of microhemocirculatory changes in periodontal tissues in anatomical and functional disorders of the mucogingival complex, based on the use of the method of discriminant analysis of ultrasound opplerography. MATERIAL AND METHODS: 187 patients aged 18-44 years (young age according to WHO) were examined without concomitant somatic pathology with various variants of anatomical structures of the mucous-gingival complex, which included an assessment of blood flow in periodontal tissues by ultrasound dopplerography at rest and during a functional test of the tension of the soft tissues of the upper and lower lip, cheeks using an opt-out. After qualitative and quantitative analysis of dopplerograms, an automated assessment of the microhemocirculation of the studied structures was performed, identifying differences between groups using step-by-step discriminant analysis with the study of several variables. RESULTS: Depending on the type of reaction to the sample, a model of the distribution of patients into separate groups based on the application of the discriminant analysis method is proposed. It was found that patients of all groups were classified statistically significantly (p<0.05) and the possibility of distributing patients according to the described criteria (the ratio of the maximum systolic blood flow rate along the mean velocity curve, Vas) to a specific class corresponding to the highest value of the function was proved. CONCLUSION: The proposed method for assessing the functional state of periodontal tissue vessels allows classifying patients with high accuracy and a minimum of the probability of false results, reliably assess the degree of existing functional disorders, determine the prognosis and further tactics of therapeutic and preventive measures and can be recommended for use in clinical practice.

The clinical efficacy of periodontally accelerated osteogenic orthodontics in patients with bone fenestration and dehiscence: a retrospective study.

PURPOSE: The objective of the study was to explore the effect of periodontally accelerated osteogenic orthodontics (PAOO) in orthodontic patients with bone dehiscence and fenestration in the anterior alveolar region of the mandible. METHODS: A retrospective study was performed in 42 patients with bone dehiscence and fenestrations in the anterior alveolar region of the mandible who underwent the PAOO technique. The bleeding index (BI), probing depth (PD), keratinized gingiva width (KGW), gingival recession level (GRL), and gingival phenotype were recorded and assessed at baseline and 6 and 12 months postoperatively. Cone-beam computerized tomography was used to measure bone volume in terms of root length (RL), horizontal bone thickness at different levels, and vertical bone height at baseline and 6 months and 12 months after surgery. RESULTS: The sample was composed of 42 patients (22 males and 20 females; mean age, aged 25.6 ± 4.8 years) with 81 teeth showing dehiscence/fenestrations and 36 sites presenting gingival recessions. There was no significant difference in BI, PD, or KGW (between baseline and 6 or 12 months postoperatively) based on the clinical evaluations (P > 0.05). Gingival recession sites demonstrated a significant reduction in the GRL after surgery (P < 0.05). Furthermore, the proportion of teeth with a thick gingival phenotype increased from 33.61% at baseline to 53.13% at the end of the follow-up. In addition, the bone thickness measurements at the mid-root and crestal levels were markedly increased compared with the baseline values (P < 0.05), although the increase in thickness at the apical level was not statistically significant (P > 0.05). CONCLUSIONS: Within the limitations of the study, the results show that the PAOO technique is beneficial to periodontal conditions in terms of soft and hard tissue augmentation. The PAOO procedure may represent a safe and efficient treatment for orthodontic patients with bone dehiscence and fenestration. TRIAL REGISTRATION: This study was approved by the ethics committee of the stomatological hospital affiliated with Xi'an Jiaotong University (xjkqll [2019] No. 016) and registered in the Chinese Clinical Trial Registry (ChiCTR2100053092).

The Effects of 5% 5-Aminolevulinic Acid Gel and Red Light (ALAD-PDT) on Human Fibroblasts and Osteoblasts.

This study aimed to evaluate the effects of a new photodynamic protocol (ALAD-PDT), consisting of 5% 5-aminolevulinic acid-gel and 630 nm-LED, already used for antibacterial effects in the treatment of periodontitis, on human gingival fibroblasts (HGF) and primary human osteoblasts (HOB). HGF and HOB were incubated with different ALAD concentrations for 45 min, and subsequently irradiated with 630 nm-LED for 7 min. Firstly, the cytotoxicity at 24 h and proliferation at 48 and 72 h were assessed. Then the intracellular content of the protoporphyrin IX (PpIX) of the ROS and the superoxide dismutase (SOD) activity were investigated at different times. Each result was compared with untreated and unirradiated cells as the control. Viable and metabolic active cells were revealed at any concentrations of ALAD-PDT, but only 100-ALAD-PDT significantly enhanced the proliferation rate. The PpIX fluorescence significantly increased after the addition of 100-ALAD, and decreased after the irradiation. Higher ROS generation was detected at 10 min in HGF, and at 30 min in HOB. The activity of the SOD enzyme augmented at 30 min in both cell types. In conclusion, ALAD-PDT not only showed no cytotoxic effects, but had pro-proliferative effects on HGF and HOB, probably via ROS generation.

The Role of Oral Health in the Acquisition and Severity of SARS-CoV-2: A Retrospective Chart Review.

Objective: Studies have shown that gingival crevices may be a significant route for SARS-CoV-2 entry. However, the role of oral health in the acquisition and severity of COVID-19 is not known. Design: A retrospective analysis was performed using electronic health record data from a large urban academic medical center between 12/1/2019 and 8/24/2020. A total of 387 COVID-19 positive cases were identified and matched 1:1 by age, sex, and race to 387 controls without COVID-19 diagnoses. Demographics, number of missing teeth and alveolar crestal height were determined from radiographs and medical/dental charts. In a subgroup of 107 cases and controls, we also examined the rate of change in alveolar crestal height. A conditional logistic regression model was utilized to assess association between alveolar crestal height and missing teeth with COVID-19 status and with hospitalization status among COVID-19 cases. Results: Increased alveolar bone loss, OR = 4.302 (2.510 - 7.376), fewer missing teeth, OR = 0.897 (0.835-0.965) and lack of smoking history distinguished COVID-19 cases from controls. After adjusting for time between examinations, cases with COVID-19 had greater alveolar bone loss compared to controls (0.641 ± 0.613 mm vs 0.260 ± 0.631 mm, p < 0.01.) Among cases with COVID-19, increased number of missing teeth OR = 2.1871 (1.146- 4.174) was significantly associated with hospitalization. Conclusions: Alveolar bone loss and missing teeth are positively associated with the acquisition and severity of COVID-19 disease, respectively.

Use of Hyaluronic Acid in Periodontal Disease Treatment: A Systematic Review.

AIM: The main purpose of the present study was to investigate the potential benefit of local use of hyaluronic acid as an adjunct to periodontal therapy, since commercial products of hyaluronic acid (HA), due to its anti-inflammatory and anti-bacterial actions and its significant role in wound repair, have been proposed as adjuncts to either nonsurgical or surgical periodontal therapy. MATERIALS AND METHODS: A total of 19 electronic databases were searched and the appropriate studies were identified with the use of specific eligibility criteria, according to PRISMA guidelines. Two reviewers independently screened and selected the studies and made the data extraction and the assessment of risk of bias, by using the Cochrane risk of bias tool. RESULTS: Out of 3,186 papers, 38 randomized clinical trials (8 related to gingivitis therapy, 20 related to nonsurgical periodontal therapy, and 10 related to surgical periodontal therapy) were finally included in the review. The outcomes were categorized as primary (that answered the focus question) and secondary (regarding additional quality characteristics). The adjunct use of HA combined to all treatment modalities shows improvement of patients' postoperative course, in terms of decreased inflammatory reactions, and changes in periodontal pocket depth and clinical attachment level. No side effects were reported in any of the included studies. Among the secondary outcomes were the variety of HA formulations and chemical forms, the variety in application, follow-up protocol and blinding design, the uneven geographic distribution of the studies, and the low bibliometric characteristics of most studies. CONCLUSION: Overall and despite the positive effects reported, further research is needed to define the ideal HA compound, formulation, and regimen characteristics for periodontal disease treatment. CLINICAL SIGNIFICANCE: The adjunct use of HA may lead in the reduction of the prescription of nonsteroid anti-inflammatory drugs and achieve improved clinical parameters, including periodontal probing depth, periodontal inflammation, and clinical attachment level.

Development and regeneration of periodontal supporting tissues.

Periodontal tissues, including gingiva, cementum, periodontal ligament, and alveolar bone, play important roles in oral health. Under physiological conditions, periodontal tissues surround and support the teeth, maintaining the stability of the teeth and distributing the chewing forces. However, under pathological conditions, with the actions of various pathogenic factors, the periodontal tissues gradually undergo some irreversible changes, that is, gingival recession, periodontal ligament rupture, periodontal pocket formation, alveolar bone resorption, eventually leading to the loosening and even loss of the teeth. Currently, the regenerations of the periodontal tissues are still challenging. Therefore, it is necessary to study the development of the periodontal tissues, the principles and processes of which can be used to develop new strategies for the regeneration of periodontal tissues. This review summarizes the development of periodontal tissues and current strategies for periodontal healing and regeneration.

THE ROLE OF ADAPTIVE-STRESS RESPONSE IN THE PATHOGENESIS OF PERIODONTAL DISEASES.

OBJECTIVE: The aim: The purpose of this work is to analyze the literature data of scientific research of Ukrainian and foreign scientists to assess the pathogenetic mechanisms of the adaptive stress response to the condition of periodontal tissues. PATIENTS AND METHODS: Materials and methods: Bibliosematic and analytical methods were used in the trial. The materials of the trial are international experience in studying the pathogenetic mechanisms of the interaction of psycho-emotional disorders and the development of periodontal lesions. CONCLUSION: Conclusions: Chronic stress and depression suppress the immune system, cause the hormonal imbalances, lead to metabolic disorders in tissues and increase the risk of dystrophic and inflammatory processes in periodontal tissues, which in turn lead to reduced masticatory function, tooth loss, severe emotional instability and significant reduction in quality of life. Psycho-emotional disorders in patients slow down the treatment of inflammatory processes in periodontal tissues and contribute to the early recurrence. Thus, the problem of studying the adaptive stress response of the organism requires further research for deeply understaningits role in the etiology and pathogenesis of dental diseases and justify effective treatment and prevention measures for its correction.

Effect of Bacterial Infection on Ghrelin Receptor Regulation in Periodontal Cells and Tissues.

The effect of bacterial infection on the expression of growth hormone secretagogue receptor (GHS-R) was investigated in periodontal cells and tissues, and the actions of ghrelin were evaluated. GHS-R was assessed in periodontal tissues of rats with and without periodontitis. Human gingival fibroblasts (HGFs) were exposed to Fusobacterium nucleatum in the presence and absence of ghrelin. GHS-R expression was determined by real-time PCR and immunocytochemistry. Furthermore, wound healing, cell viability, proliferation, and migration were evaluated. GHS-R expression was significantly higher at periodontitis sites as compared to healthy sites in rat tissues. F. nucleatum significantly increased the GHS-R expression and protein level in HGFs. Moreover, ghrelin significantly abrogated the stimulatory effects of F. nucleatum on CCL2 and IL-6 expressions in HGFs and did not affect cell viability and proliferation significantly. Ghrelin stimulated while F. nucleatum decreased wound closure, probably due to reduced cell migration. Our results show original evidence that bacterial infection upregulates GHS-R in rat periodontal tissues and HGFs. Moreover, our study shows that ghrelin inhibited the proinflammatory actions of F. nucleatum on HGFs without interfering with cell viability and proliferation, suggesting that ghrelin and its receptor may act as a protective molecule during bacterial infection on periodontal cells.

The Impact of mRNA Technology in Regenerative Therapy: Lessons for Oral Tissue Regeneration.

Oral tissue regeneration following chronic diseases and injuries is limited by the natural endogenous wound-healing process. Current regenerative approaches implement exogenous systems, including stem cells, scaffolds, growth factors, and plasmid DNA/viral vectors, that induce variable clinical outcomes. An innovative approach that is safe, effective, and inexpensive is needed. The lipid nanoparticle-encapsulated nucleoside-modified messenger RNA (mRNA) platform has proven to be a successful vaccine modality against coronavirus disease 2019, demonstrating safety and high efficacy in humans. The same fundamental technology platform could be applied to facilitate the development of mRNA-based regenerative therapy. While the platform has not yet been studied in the field of oral tissue regeneration, mRNA therapeutics encoding growth factors have been evaluated and demonstrated promising findings in various models of soft and hard tissue regeneration such as myocardial infarction, diabetic wound healing, and calvarial and femoral bone defects. Because restoration of both soft and hard tissues is crucial to oral tissue physiology, this new therapeutic modality may help to overcome challenges associated with the reconstruction of the unique and complex architecture of oral tissues. This review discusses mRNA therapeutics with an emphasis on findings and lessons in different regenerative animal models, and it speculates how we can apply mRNA-based platforms for oral tissue regeneration.

Functional Adaptation of LPS-affected Dentoalveolar Fibrous Joints in Rats.

INTRODUCTION: The functional interplay between cementum of the root and alveolar bone of the socket is tuned by a uniquely positioned 70-80 µm wide fibrous and lubricious ligament in a dentoalveolar joint (DAJ). In this study, structural and biomechanical properties of the DAJ, periodontal ligament space (PDL-space also known as the joint space), alveolar bone of the socket, and cementum of the tooth root that govern the biomechanics of a lipopolysaccharide (LPS)-affected DAJ were mapped both in space and time. METHODS: The hemi-maxillae from 20 rats (4 control at 6 weeks of age, 4 control and 4 LPS-affected at 12 weeks of age, 4 control and 4 LPS-affected at 16 weeks of age) were investigated using a hybrid technique; micro-X-ray computed tomography (5 µm resolution) in combination with biomechanical testing in situ. Temporal variations in bone and cementum volume fractions were evaluated. Trends in mineral apposition rates (MAR) in additional six Sprague Dawley rats (3 controls, 3 LPS-affected) were revealed by transforming spatial fluorochrome signals to functional growth rates (linearity factor - RW) of bone, dentin, and cementum using a fast Fourier transform on fluorochrome signals from 100-µm hemi-maxillae sections. RESULTS: An overall change in LPS-affected DAJ biomechanics (a 2.5-4.5X increase in tooth displacement and 2X tooth rotation at 6 weeks, no increase in displacement and a 7X increase in rotation at 12 weeks; 27% increase in bone effective strain at 6 weeks and 11% at 12 weeks relative to control) was associated with structural changes in the coronal regions of the DAJ (15% increase in PDL-space from 0 to 6 weeks but only 5% from 6 to 12 weeks compared to control). A significant increase (p < 0.05) in PDL-space between ligated and age-matched control was observed. The bone fraction of ligated at 12 weeks was significantly lower than its age-matched control, and no significant differences (p > 0.05) between groups were observed at 6 weeks. Cementum in the apical regions grew faster but nonlinearly (11% and 20% increase in cementum fraction (CF) at 6 and 12 weeks) compared to control. Alveolar bone revealed site-specific nonlinear growth with an overall increase in MAR (108.5 µm/week to 126.7 µm/week after LPS treatment) compared to dentin (28.3 µm/week in control vs. 26.1 µm/week in LPS-affected) and cementum (126.5 µm/week in control vs. 119.9 µm/week in LPS-affected). A significant increase in CF (p < 0.05) in ligated specimens was observed at 6 weeks of age. CONCLUSIONS: Anatomy-specific responses of cementum and bone to the mechano-chemo stimuli, and their collective temporal contribution to observed changes in PDL-space were perpetuated by altered tooth movement. Data highlight the "resilience" of DAJ function through the predominance of nonlinear growth response of cementum, changes in PDL-space, and bone architecture. Despite the significant differences in bone and cementum architectures, data provided insights into the reactionary effects of cementum as a built-in compensatory mechanism to reestablish functional competence of the DAJ. The spatial shifts in architectures of alveolar bone and cementum, and consequently ligament space, highlight adaptations farther away from the site of insult, which also is another novel insight from this study. These adaptations when correlated within the context of joint function (biomechanics) illustrate that they are indeed necessary to sustain DAJ function albeit being pathological.

Orthodontic tooth movement alters cementocyte ultrastructure and cellular cementum proteome signature.

Cementum is a mineralized tissue that covers tooth roots and functions in the periodontal attachment complex. Cementocytes, resident cells of cellular cementum, share many characteristics with osteocytes, are mechanoresponsive cells that direct bone remodeling based on changes in loading. We hypothesized that cementocytes play a key role during orthodontic tooth movement (OTM). To test this hypothesis, we used 8-week-old male Wistar rats in a model of OTM for 2, 7, or 14 days (0.5 N), whereas unloaded contralateral teeth served as controls. Tissue and cell responses were analyzed by high-resolution micro-computed tomography, histology, tartrate-resistant acid phosphatase staining for odontoclasts/osteoclasts, and transmission electron microscopy. In addition, laser capture microdissection was used to collect cellular cementum, and extracted proteins were identified by liquid chromatography coupled to tandem mass spectrometry. The OTM model successfully moved first molars mesially more than 250 µm by 14 days introducing apoptosis in a small number of cementocytes and areas of root resorption on mesial and distal aspects. Cementocytes showed increased nuclear size and proportion of euchromatin suggesting cellular activity. Proteomic analysis identified 168 proteins in cellular cementum with 21 proteins found only in OTM sites and 54 proteins only present in control samples. OTM-down-regulated several extracellular matrix proteins, including decorin, biglycan, asporin, and periostin, localized to cementum and PDL by immunostaining. Furthermore, type IV collagen (COL14A1) was the protein most down-regulated (-45-fold) by OTM and immunolocalized to cells at the cementum-dentin junction. Eleven keratins were significantly increased by OTM, and a pan-keratin antibody indicated keratin localization primarily in epithelial remnants of Hertwig's epithelial root sheath. These experiments provide new insights into biological responses of cementocytes and cellular cementum to OTM.

Effects of Active Vitamin D or FGF23 Antibody on Hyp Mice Dentoalveolar Tissues.

Mutations in the PHEX gene lead to X-linked hypophosphatemia (XLH), a form of inherited rickets featuring elevated fibroblast growth factor 23 (FGF23), reduced 1,25-dihydroxyvitamin D (1,25D), and hypophosphatemia. Hyp mutant mice replicate the XLH phenotype, including dentin, alveolar bone, and cementum defects. We aimed to compare effects of 1,25D versus FGF23-neutralizing antibody (FGF23Ab) monotherapies on Hyp mouse dentoalveolar mineralization. Male Hyp mice, either injected subcutaneously with daily 1,25D or thrice weekly with FGF23 blocking antibody from 2 to 35 d postnatal, were compared to wild-type (WT) controls and untreated Hyp mice. Mandibles were analyzed by high-resolution micro-computed tomography (micro-CT), histology, and immunohistochemistry. Both interventions maintained normocalcemia, increased serum phosphate levels, and improved dentoalveolar mineralization in treated versus untreated Hyp mice. 1,25D increased crown dentin volume and thickness and root dentin/cementum volume, whereas FGF23Ab effects were limited to crown dentin volume. 1,25D increased bone volume fraction, bone mineral density, and tissue mineral density in Hyp mice, whereas FGF23Ab failed to significantly affect these alveolar bone parameters. Neither treatment fully attenuated dentin and bone defects to WT levels, and pulp volumes remained elevated regardless of treatment. Both treatments reduced predentin thickness and improved periodontal ligament organization, while 1,25D promoted a more profound improvement in acellular cementum thickness. Altered cell densities and lacunocanalicular properties of alveolar and mandibular bone osteocytes and cementocytes in Hyp mice were partially corrected by either treatment. Neither treatment normalized the altered distributions of bone sialoprotein and osteopontin in Hyp mouse alveolar bone. Moderate improvements from both 1,25D and FGF23Ab treatment regimens support further studies and collection of oral health data from subjects receiving a newly approved anti-FGF23 therapy. The inability of either treatment to fully correct Hyp mouse dentin and bone prompts further experiments into underlying pathological mechanisms to identify new therapeutic approaches.