Mandibular biomechanical behavior of rats submitted to chronic intermittent or continuous hypoxia and periodontitis.

BACKGROUND: The aim of this study was to investigate the effects of exposure to continuous (CH) and intermittent (IH) hypoxia on biomechanical properties of the mandible and periodontal tissue of animals submitted to experimental periodontitis (EP) when applying loads in a hypoxic environment. METHODS: Adult female Wistar rats were exposed during 90 days to IH or CH (simulated high altitude of 4200 m above sea level). Fourteen days prior to the euthanasia, EP was induced to half of the animals of each group. RESULTS: Only in the rats with EP, IH decreased the maximum capacity of the mandible to withstand load and the limit of elastic load. Indicators of intrinsic properties of the bone material were significantly reduced by both types of hypoxia in rats with EP. Hypoxia enhanced the alveolar bone loss induced by EP in the buccal side of the mandible, without showing additional effects in lingual or interradicular bone. Hypoxia increased prostaglandin E2 content in gingival tissue of healthy animals and further elevated the E2 levels increased by EP. CONCLUSIONS: When periodontitis is present, hypoxic stress induces a decrease in mineral properties that ultimately affects the ability of the mandible to resist load, mainly during intermittent exposure to hypoxia. These effects on bone may be related to the higher levels of prostaglandin E2 reached in the surrounding gingival tissue. The findings of this study may stimulate strategies to prevent unwanted effects of hypoxia on periodontal tissues.

Mucina y Enfermedad Periodontal / Mucin and periodontal disease

La enfermedad periodontal (EP) es una patología que afecta principalmente los tejidos que rodean a la pieza dentaria (PD) y se caracteriza, en la mayoría de los casos, por una exposición bacteriana que favorece una respuesta destructiva e inflamatoria del huésped, que conduce a la pérdida de inserción periodontal de la PD, provocando una marcada reabsorción ósea y la posible pérdida de las PD. El diagnóstico de EP implica evaluaciones clínicas y radiográficas, en la actualidad se están realizando diversas investigaciones para evaluar posibles compuestos en los fluidos orales a través de lo cual puede ser posible evaluar la presencia y gravedad de estas enfermedades, como así también el riesgo en los pacientes. Hay evidencias de la interacción de macromoléculas salivales, como las mucinas, con microorganismos específicos. De esta manera las mucinas, junto con otros productos de la saliva, ayudan a modular tanto el número como el tipo de proliferación de ciertos organismos y provocar la disminución de otros. La revisión de la literatura actual concluye que las mucinas salivales pueden servir como un parámetro bioquímico de la inflamación del periodonto (AU)

Periodontal disease (PD) is a pathology that mainly affects the tissues surrounding the tooth (PD) and is characterized, in most cases, by a bacterial exposure that favors a destructive and inflammatory response of the host, which leads to the loss of periodontal insertion of the PD, causing a marked bone resorption and the possible loss of the PD. The diagnosis of PD involves clinical and radiographic evaluations, at present several investigations are being carried out to evaluate possible compounds in oral fluids through which it may be possible to evaluate the presence and severity of these diseases, as well as the risk in patients. There is evidence of the interaction of salivary macromolecules, such as mucins, with specific microorganisms. In this way, mucins, together with other saliva products, help modulate both the number and type of proliferation of certain organisms and cause the decrease of others. The review of the current literature concludes that salivary mucins can serve as a biochemical parameter of inflammation of the periodontium (AU)

Morphofunctional State of the Periodontal Tissues in Humans and Rats with Arterial Hypertension.

We performed comparative analysis of hemodynamic in the periodontal microcirculatory bed in adolescents with arterial hypertension (AH) and morphological changes in the periodontal tissues of in hypertensive ISIAH rats of comparable biological age. In the periodontal tissues of adolescents with hypertension, the blood flow velocity and index of peripheral resistance increased, while pulse pressure decreased. In ISIAH rats, the mean area of periodontal and pulp vessels increased and the area of the connective tissue decreased. These results can be used in the complex assessment of morphofunctional state periodontium during hypertension development.

Enhancement of periodontal tissue regeneration by conditioned media from gingiva-derived or periodontal ligament-derived mesenchymal stem cells: a comparative study in rats.

BACKGROUND: Evidence has demonstrated conditioned medium (CM) from periodontal ligament stem cells (PDLSCs) improved periodontal regeneration. Gingival mesenchymal stem cells (GMSCs) have been considered an alternative strategy for regenerative medicine. To determine whether GMSC-CM could promote periodontal wound healing, we compared the effects of GMSC-CM and PDLSC-CM on periodontal regeneration and the underlying mechanisms in rat periodontal defects. METHODS: Cell-free CMs were collected from PDLSCs, GMSCs, and gingival fibroblasts (GFs) using ultracentrifugation (100-fold concentration). Periodontal defects were created on the buccal side of the first molar in the left mandible of 90 rats by a surgical method. Collagen membranes loaded with concentrated CMs (α-MEM, GF-CM, GMSC-CM, PDLSC-CM) were transplanted into periodontal defects. After 1, 2, and 4 weeks, the animals were sacrificed and specimens including the first molar and the surrounding tissues were separated and decalcified. Hematoxylin-eosin and Masson's trichrome staining were performed to evaluate periodontal regeneration. Immunohistochemical staining for tumor necrosis factor (TNF)-α, interleukin (IL)-1ß, and IL-10 was conducted to analyze inflammation. Immunohistochemistry of BSP-II and Runx2 was performed to analyze osteoblast differentiation. RESULTS: Histological analysis showed the amount of newly formed periodontal tissue was significantly higher in both the GMSC-CM and PDLSC-CM groups than in the other groups, with no significant difference between these two groups. At 1 and 2 weeks, the expression levels of TNF-α and IL-1ß were significantly lower in the GMSC-CM and PDLSC-CM groups than in the other three groups, while there was no significant difference between these two groups. IL-10 expression was significantly higher in the GMSC-CM group than in the PDLSC-CM group and the other three groups. At 1, 2, and 4 weeks, BSP-II and Runx2 expressions were significantly higher in the GMSC-CM and PDLSC-CM groups than in the other three groups, with no significant difference between the two groups. CONCLUSIONS: Our results demonstrate that GMSC-CM transplantation can significantly promote periodontal regeneration in rats and achieve the same effect as PDLSC-CM. The mechanism of periodontal regeneration may involve the regulation of inflammatory factors and the promotion of osteogenic differentiation of bone progenitor cells in the wound region by CMs from MSCs.

Regeneración ósea guiada (ROG): Plasma rico en factores de crecimiento vs. Autoinjerto dental particulado, revisión bibliográfica / Guided bone regeneration (ROG): Plasma rich in growth factors vs. Particulate dental autograft, review

Resumen El objetivo primordial en la terapia de la regeneración ósea guiada viene a ser la restauración de los componentes del periodonto. La racionalidad de esta terapia es dar la preferencia a tipos celulares específicos para repoblar la zona de la herida a formar un nuevo aparato de inserción. De manera clínica esto se logra al colocar una barrera física sobre el defecto periodontal, dejando de lado los tejidos gingivales en las etapas tempranas de reparación. Este trabajo analiza la evidencia científica que existe de los resultados alcanzados mediante la ROG, los factores que influyen con el tipo de materiales utilizados, sus indicaciones, sus componentes, sus contraindicaciones, los mecanismos de evaluación, así como las propiedades de distintas barreras utilizadas desde un punto de vista del biomaterial.

Abstract The primary goal in the therapy of guided bone regeneration is to restore the components of the periodontium. The rationale of this therapy is to give preference to specific cell types to repopulate the wounded area to form a new insertion apparatus. Clinically this is achieved by placing a physical barrier on the periodontal defect, leaving the gingival tissues aside in the early stages of repair. This work analyzes the scientific evidence that exists about the results achieved by the ROG, the factors that influence the type of materials used, their indications, their components, their contraindications, the evaluation mechanisms, as well as the properties of different barriers used since a biomaterial point of view.

RNA sequencing for ligature induced periodontitis in mice revealed important role of S100A8 and S100A9 for periodontal destruction.

Periodontitis is an inflammatory disease caused by pathogenic oral microorganisms that induce the destruction of periodontal tissue. We sought to identify the relevant differentially expressed genes (DEGs) and clarify the mechanism underlying the rapid alveolar bone loss by using ligature-induced periodontitis in mice. A silk ligature was tied around the maxillary left second molar in 9-week-old C57BL/6 J male mice. In-vivo micro-CT analysis revealed that ligation induced severe bone loss. RNA-sequencing analysis, to examine host responses at 3 days post-ligation, detected 12,853 genes with fragments per kilobase of exon per million mapped reads ≥ 1, and 78 DEGs. Gene ontology term enrichment analysis revealed the expression profiles related to neutrophil chemotaxis and inflammatory responses were significantly enriched in the ligated gingiva. The expression levels of innate immune response-related genes, including S100a8 and S100a9, were significantly higher in the ligated side. S100A8 was strongly detected by immunohistochemistry at the attached epithelium in ligated sites. Inhibition of S100A8 and S100A9 expression revealed that they regulated IL1B and CTSK expression in Ca9-22 cells. Thus, innate immune response-related molecules might be associated with the burst-destruction of periodontal tissue in ligature-induced periodontitis. Especially, S100A8 and S100A9 may play an important role in alveolar bone resorption.

Recent Advances of Useful Cell Sources in the Periodontal Regeneration.

BACKGROUND: Periodontitis is an inflammatory disease that can result in destruction of the tooth attachment apparatus. Therefore, periodontal tissue regeneration is currently an important focus of research in the field. Approaches using stem cells and reprogrammed cells, such as induced pluripotent stem cells (iPSCs) or trans-differentiated cells, represent the cutting edge in periodontal regeneration, and have led to many trials for their clinical application. Objectives and Results: In this review, we consider all available stem cell sources, methods to obtain the cells, their capability to differentiate into the desired cells, and the extent of their utilization in periodontal regeneration. In addition, we introduce the new concepts of using iPSCs and transdifferentiated cells for periodontal regeneration. Finally, we discuss the promise of tissue engineering for improving cell therapy outcomes for periodontal regeneration. CONCLUSIONS: Despite their limitations, iPSCs and trans-differentiated cells may be promising cell sources for periodontal tissue regeneration. Further collaborative investigation is required for the effective and safe application of these cells in combination with tissue engineering elements, like scaffolds and biosignals.

Metallic crown-induced occlusal trauma as a protocol to evaluate inflammatory response in temporomandibular joint and periodontal tissues of rats.

OBJECTIVES: The goal of this study is to propose a standard protocol of experimental occlusal trauma to evaluate the inflammatory hyperalgesia induced by metallic crowns on orofacial tissues of rats. MATERIALS AND METHODS: Thirty animals were randomly divided into six groups (n = 5 per group). Detailed methodology on the manufacturing of metallic crowns is described. The inflammatory hyperalgesia induced by occlusal interference was evaluated by intra-articular injection of a low dose of 0.5% formalin (30 µl) or vehicle (saline) into temporomandibular joint, 21 or 28 days after metallic crown cementation. Posteriorly, pro-inflammatory cytokines were evaluated by enzyme-linked immunosorbent assay to assess the effect of occlusal interference on periodontium. RESULTS: The cementation of metallic crowns with dental anatomy on the lower molar of rats does not show signs of stress and lack of feeding. Metallic crown-induced occlusal trauma results in a temporomandibular joint inflammatory hyperalgesia (P < 0.05: ANOVA, Tukey's test). Otherwise, it was observed that occlusal trauma results in the increase of protein level of pro-inflammatory cytokines TNF-alpha and IL-1beta in the gingival tissues (P < 0.05). CONCLUSION: This study demonstrates in detail a methodology of occlusal trauma resulting from the cementation of metallic crowns in the lower molars of rats, mimicking occlusal interferences commonly evaluated in the dental clinic. This methodology makes new studies to better understand the mechanisms involved in the occlusal trauma of orofacial tissues possible. CLINICAL RELEVANCE: The standardization of an experimental occlusal interference model will allow us to understand the deleterious effect and mechanisms that affect the orofacial tissues.

Systematic review of the effects of excessive occlusal mechanical load on the periodontum of rats.

OBJECTIVE: This study aims to systematically evaluate the effects of traumatic occlusion on the periodontal tissue of rats. The set of questions to be answered were-Can traumatic occlusion acting on a healthy and an unhealthy periodontium cause periodontal destruction? DESIGN: The protocols for systematic review were all developed, following the Preferred Reporting Items for Systematic reviews and Meta-Analyses statement and applied to animal research. Reporting of In vivo experiment guidelines for reporting animal research to assess the risk of bias of the studies. MATERIALS AND METHODS: A literature search was conducted using MEDLINE through PubMed and manual search from the reference lists of main articles related to the theme. RESULTS: This search strategy identified 65 references, of which 33 were considered inappropriate. The full texts of 32 articles were read, 31 of which did not meet the eligibility criteria and were excluded. The final selection included 1 article for which data was extracted for further evaluation. The article included shows a strongest reaction in the periodontium in front of a secondary occlusal trauma as inflammation and apical migration of the junctional epithelium, bone degradation, and decrease in the quantity of collagen fiber. However, primary occlusal trauma also presents these alterations, with the exception of apical migration of the junctional epithelium. CONCLUSIONS: Although only one study was included in the systematic review of traumatic occlusion, there is some evidence from experimental studies on animals that shows a coherent picture of the effects of traumatic occlusion on the periodontium. However, new studies are needed to fully answer the questions posed by this systematic review.

Periodontal status and lung function decline in the community: the Hisayama study.

This study aimed to determine whether periodontal status is related to a decline in lung function in a general Japanese population. We followed a total of 1,650 community-dwelling individuals (≥40 years) without chronic obstructive pulmonary disease, with at least one teeth, for 3 years. Periodontal status was assessed at baseline by clinical attachment loss (CAL) and probing pocket depth (PPD) at two sites for each tooth, and the mean values were calculated for each subject. Lung function was measured at baseline and follow-up using spirometry, and longitudinal decline in forced expiratory volume in one second (FEV1) was calculated. Multivariate Poisson regression with robust error variance was used to estimate risk ratio (RR). After adjusting for potential confounders including smoking status, there was a tendency for the adjusted RR of developing rapid lung function decline (≥160 mL/3years, the highest quartile of the distribution of FEV1 declines) to increase as mean CAL levels increased (P trend = 0.039). Likewise, a positive association was observed between mean PPD levels and RR of developing rapid lung function decline (P trend = 0.047). Our findings suggest deterioration of periodontal status could be a risk factor for rapid lung function decline in the general Japanese population.

Cambios morfofuncionales en el periodoncio asociados al movimiento dentario por tratamiento ortodóncico / Morfofunctional changes in the periodontium associated to the teeth movement due to orthodontic treatment

Los cambios morfofuncionales que se producen en las estructuras de soporte dentario durante el movimiento ortodóncico involucran procesos bioquímicos, histológicos y fisiológicos. Desde hace más de un siglo, existen disímiles teorías que tratan de explicarlos; sin embargo, todavía se siguen realizando estudios a fin de comprenderlos más a fondo. En la presente comunicación se ofrece una actualización secuencial y resumida de dichos episodios, con el propósito de incrementar el nivel de conocimientos sobre el tema y mejorar la calidad en la atención ortodóncica.

Morfofunctional changes which take place in the supporting structures during the orthodontic movement involve biochemical, histological and physiologic processes. For more than one century, dissimilar theories exist that try to explain to them; however, studies are still being carried out in order to understand them thoroughly. In the present communication a sequential and summarized updating of these episodes, with the purpose of increasing the knowledge on the topic and improving the quality in the orthodontic care.

Evaluation of a platelet lysate bilayered system for periodontal regeneration in a rat intrabony three-wall periodontal defect.

With currently available therapies, full regeneration of lost periodontal tissues after periodontitis cannot be achieved. In this study, a combined compartmentalized system was tested, composed of (a) a platelet lysate (PL)-based construct, which was placed along the root aiming to regenerate the root cementum and periodontal ligament, and (b) a calcium phosphate cement composite incorporated with hyaluronic acid microspheres loaded with PL, aiming to promote the regeneration of alveolar bone. This bilayered system was assessed in a 3-wall periodontal defect in Wistar rats. The periodontal healing and the inflammatory response of the materials were scored for a period up to 6 weeks after implantation. Furthermore, histomorphometrical measurements were performed to assess the epithelial downgrowth, the formation of alveolar bone, and the formation of new connective tissue attachment. Our data showed that the stabilization of platelet-origin proteins on the root surface increased the overall periodontal healing score and restricted the formation of long epithelial junctions. Nevertheless, the faster degradation of the cement component with incorporated hyaluronic acid microspheres compromised the stability of the system, which hampered the periodontal regeneration. Overall, in this work, we proved the positive therapeutic effect of the immobilization of a PL-based construct over the root surface in a combined compartmentalized system to assist predictable healing of functional periodontium. Therefore, after optimization of the hard tissue analogue, the system should be further elaborated in (pre)clinical validation studies.

Tooth Loss in Patients under Periodontal Maintenance in a Private Practice: A Retrospective Study.

The aim of the present study was to evaluate the incidence and causes of tooth loss in periodontal subjects from a private practice in Brazil. Two trained examiners extracted data from the records of subjects who sought periodontal treatment from 1980 to 2013. Only records of patients who completed the non-surgical periodontal treatment and had at least one visit for maintenance were included. Data were analyzed by chi-square test, Student's t-test, Kaplan-Meier survival curve and Cox regression. A total of 3,319 records were reviewed and 737 records included (58.6% women, mean age of 46.6±13.0 years at the beginning of the treatment). Maintenance period ranged from 1 to 33 years (7.4±6 years). During this period, 202 individuals (27.4%) lost 360 teeth, 47.5% of losses within the first five years (n=171). Non-compliers lost more teeth than compliers (p<0.001), respectively 211 and 149 teeth. Regarding reasons of tooth loss, 84 individuals lost 38% of the teeth from periodontal disease progression (n=137). Survival analysis showed that most patients lost only one tooth from periodontal disease, and differences in the survival rates between compliers and non-compliers were observed following the second tooth loss. Approximately one-third of tooth losses was related to periodontal disease progression, and there was stability in time of the proportion of losses from disease progression and other reasons. Therefore, it is possible to conclude that compliant patients in a private practice lose fewer teeth than do non-compliers. Among compliers, periodontal disease progression was not the main cause of tooth loss.

Orthodontic intrusion of periodontally-compromised maxillary incisors: 3-dimensional finite element method analysis.

BACKGROUND: Loading of the compromised periodontium with orthodontic forces produces different results than those achieved in patients with healthy periodontal support. Determining the force value at a level preventing further deterioration of the patient's periodontal status, thus delivering the most precisely individualized "dose" of loading, seems to be crucial for the successful intrusion of teeth with reduced periodontal support. OBJECTIVES: The aim of the study was to determine the range of force values efficiently intruding maxillary incisors without further compromising the initially-impaired periodontal status. Finite element analysis (FEA), allowing estimation of the stress and strain distribution, was the method of choice. MATERIAL AND METHODS: The CT scans of a periodontally-compromised patient were segmented using InVesalius software. A model - based on NURBS surfaces - was adjusted to the CT scans in order to obtain both smooth and natural curvatures of each model segment. All relevant tissues were modeled as separate volumes. The geometric model was discretized in order to create a numerical model for applying Ansys software (v. 15.07) and using APDL. The central incisors were loaded with external intrusive forces, ranging from 0.1 to 0.4 N. RESULTS: The simulation, performed iteratively, showed that even the lowest force value - 0.1 N - causes stress changes in the alveolus and on the root surfaces, with a tendency of stress increasing towards the bottom of the alveolus and root apex. It is also notable that during the application of forces of equal magnitude, the stress/strain distribution was significantly higher around tooth 21, which displayed the highest range of PDL reduction. Application of the same force level created a higher stress-strain response around tooth 21, and the characteristics were less homogenous. CONCLUSIONS: A force value of 0.1 N applied in vivo might produce the most effective tooth intrusion and bone modeling which favors bone defect regeneration.

Post-Surgical Clinical Monitoring of Soft Tissue Wound Healing in Periodontal and Implant Surgery.

Clinical features of surgical soft tissue wound healing in dentistry have been rarely discussed in the international literature. The aim of the present paper is to highlight both the main clinical findings of surgical wound healing, especially in periodontal and implant dentistry, and the wound healing monitoring procedures which should be followed. Wound inspection after careful food and plaque debridement is the essential part of wound healing monitoring. Periodontal and peri-implant probing should be performed only after tissue healing has been completed and not on a weekly basis in peri-implant tissue monitoring. Telephone follow-up and patient self-assessment scales can also be used the days following surgery to monitor the most common surgical complications such as pain, swelling, bleeding, and bruising. Wound healing monitoring is an important concern in all surgical procedures since it allows to identify signs or/and symptoms possibly related to surgical complications.

Tooth Loss in Patients under Periodontal Maintenance in a Private Practice: A Retrospective Study

Abstract The aim of the present study was to evaluate the incidence and causes of tooth loss in periodontal subjects from a private practice in Brazil. Two trained examiners extracted data from the records of subjects who sought periodontal treatment from 1980 to 2013. Only records of patients who completed the non-surgical periodontal treatment and had at least one visit for maintenance were included. Data were analyzed by chi-square test, Student's t-test, Kaplan-Meier survival curve and Cox regression. A total of 3,319 records were reviewed and 737 records included (58.6% women, mean age of 46.6±13.0 years at the beginning of the treatment). Maintenance period ranged from 1 to 33 years (7.4±6 years). During this period, 202 individuals (27.4%) lost 360 teeth, 47.5% of losses within the first five years (n=171). Non-compliers lost more teeth than compliers (p<0.001), respectively 211 and 149 teeth. Regarding reasons of tooth loss, 84 individuals lost 38% of the teeth from periodontal disease progression (n=137). Survival analysis showed that most patients lost only one tooth from periodontal disease, and differences in the survival rates between compliers and non-compliers were observed following the second tooth loss. Approximately one-third of tooth losses was related to periodontal disease progression, and there was stability in time of the proportion of losses from disease progression and other reasons. Therefore, it is possible to conclude that compliant patients in a private practice lose fewer teeth than do non-compliers. Among compliers, periodontal disease progression was not the main cause of tooth loss.

Resumo O objetivo do presente estudo foi avaliar a incidência e causas de perda dentária em pacientes em manutenção periódica preventiva (MPP) de uma clínica privada. Dois examinadores extraíram os dados de registros de pacientes que procuraram tratamento periodontal entre 1980 a 2013. Os registros de pacientes que completaram o tratamento periodontal não cirúrgico e tiveram ao menos uma visita de MPP foram incluídos. Os dados foram avaliados utilizando os testes chi-quadrado, T de Student, curva de sobrevida de Kaplan-Meier e regressão de Cox. Dos 3.319 prontuários, 737 foram incluídos (58,6% mulheres, 46,6±13,0 anos). O período de MPP variou de 1 a 33 anos (7,4±6 anos). Durante este período, 202 indivíduos (27,4%) perderam 360 dentes, 47,5% das perdas durante os primeiros 5 anos de manutenção (n=171). Indivíduos irregulares nas consultas de MPP perderam mais dentes (p<0.001) do que indivíduos com regularidade, 211 e 149 dentes respectivamente. Oitenta e quatro indivíduos perderam 38% de dentes por progressão de doença periodontal (n=137). A maioria dos indivíduos perdeu 1 dente por doença periodontal, e foram observadas diferenças na sobrevida a partir da segunda perda dentária quando comparados indivíduos regulares e irregulares na MPP. Aproximadamente um terço dos dentes perdidos estava relacionado à progressão de doença periodontal. Foi observada uma estabilidade na proporção de perdas por progressão de doença e outras razões ao longo do tempo. Desta forma, conclui-se que indivíduos com uma frequência regular de MPP perdem menos dentes e a progressão de doença nesses indivíduos não é a principal razão para perda dentária.

Trichomonas tenax and periodontal diseases: a concise review.

Periodontal diseases (gingivitis and periodontitis), result from a disruption of the host-oral microbiome homoeostasis. Whereas the pathological role of some specific bacterial strains during periodontal diseases is well documented, the impact of parasites in periodontium pathophysiology is still under debate. This review aims to collect data about the prevalence and the potential role of Trichomonas tenax during periodontal diseases. Data from 47 studies revealed that T. tenax prevalence in diseased periodontium ranged from 0 to 94·1%. The prevalence of oral protozoan infections was found to be largely greater in patients with periodontal diseases than with healthy periodontium. The parasite detection was mainly performed by direct microscopy. Trichomonas tenax presence was clearly correlated with periodontal disease. The high heterogeneity of its periodontal prevalence may be correlated with the diversity of the population screened (age, sex, systemic diseases), and the methods used for diagnosis. This protozoan seems to have the capacity to be involved in the inflammatory process of gum disease. Animal experimentation, using relevant physiopathological models of periodontitis, needs to be performed to investigate the ability of T. tenax to cause and/or worsen the disease. Further investigations using standardized experimental designs of epidemiologic studies are also needed.

A cross-sectional, clinical study to evaluate mobility of teeth during pregnancy using periotest.

BACKGROUND AND OBJECTIVE: Over a century, an increased prevalence of gingival diseases associated with increasing plasma sex steroid hormone levels has been reported. These situations present unique challenges to the oral health-care professional. It is believed that hormonal fluctuations such as those associated with pregnancy, menstruation, and use of hormonal contraceptives lead to an increase in tooth mobility. However, this effect of female sex hormones on periodontal ligament and tooth-supporting alveolar bone has rarely been investigated. Hence, this study was conducted to understand the effect of hormonal changes during pregnancy on tooth mobility. MATERIALS AND METHODS: Mobility of index teeth 16, 13, 21, 23, 24, 36, 33, 41, 43, and 44 was measured with periotest for fifty pregnant females at first trimester (12th week), second trimester (24th week), and third trimester (35th week). Simplified oral hygiene index, plaque index, Gingival index (GI), and probing depth were also evaluated during the three trimesters of pregnancy for each subject participating in the study. STATISTICAL ANALYSIS: The results of the study were subjected to statistical analysis. Data analysis was done by applying Z-test for comparing difference between two sample means. RESULTS: A small but statistically significant influence on the periotest value was seen during the three trimesters of pregnancy. GI scores significantly increased throughout pregnancy despite no significant change in plaque levels. CONCLUSION: Pregnancy had a significant influence on tooth mobility. Highest value of tooth mobility was seen in the last month of pregnancy. The maximum severity of gingivitis was also seen during the third trimester of pregnancy.

Periodontal Tissue Regeneration Using Syngeneic Adipose-Derived Stromal Cells in a Mouse Model.

Current treatment of periodontitis is still associated with a high degree of variability in clinical outcomes. Recent advances in regenerative medicine by mesenchymal cells, including adipose stromal cells (ASC) have paved the way to improved periodontal regeneration (PD) but little is known about the biological processes involved. Here, we aimed to use syngeneic ASCs for periodontal regeneration in a new, relevant, bacteria-induced periodontitis model in mice. Periodontal defects were induced in female C57BL6/J mice by oral gavage with periodontal pathogens. We grafted 2 × 105 syngeneic mouse ASCs expressing green fluorescent protein (GFP) (GFP+/ASC) within a collagen vehicle in the lingual part of the first lower molar periodontium (experimental) while carrier alone was implanted in the contralateral side (control). Animals were sacrificed 0, 1, 6, and 12 weeks after treatment by GFP+/ASC or vehicle graft, and microscopic examination, immunofluorescence, and innovative bio-informatics histomorphometry methods were used to reveal deep periodontium changes. From 1 to 6 weeks after surgery, GFP+ cells were identified in the periodontal ligament (PDL), in experimental sites only. After 12 weeks, cementum regeneration, the organization of PDL fibers, the number of PD vessels, and bone morphogenetic protein-2 and osteopontin expression were greater in experimental sites than in controls. Specific stromal cell subsets were recruited in the newly formed tissue in ASC-implanted periodontium only. These data suggest that ASC grafting in diseased deep periodontium, relevant to human pathology, induces a significant improvement of the PDL microenvironment, leading to a recovery of tooth-supporting tissue homeostasis. Stem Cells Translational Medicine 2017;6:656-665.

The paradox of painless periodontal disease.

Periodontal diseases, primarily gingivitis and periodontitis, are characterised by progressive inflammation and tissue destruction. However, they are unusual in that they are not also accompanied by the pain commonly seen in other inflammatory conditions. This suggests that interactions between periodontal bacteria and host cells create a unique environment in which the pro-algesic effects of inflammatory mediators and factors released during tissue damage are directly or indirectly inhibited. In this review, we summarise the evidence that periodontal disease is characterised by an accumulation of classically pro-algesic factors from bacteria and host cells. We then discuss several mechanisms by which inflammatory sensitisation of nociceptive fibres could be prevented through inactivation or inhibition of these factors. Further studies are necessary to fully understand the molecular processes underlying the endogenous localised hypoalgesia in human periodontal disease. This knowledge might provide a rational basis to develop future therapeutic interventions, such as host modulation therapies, against a wide variety of other human pain conditions.