The active form of vitamin D is the hormonally active 1,25(OH)2D3 (Vit D) vitamin, which plays an important role in bone biology and host immunity. The vitamin D receptor (VDR) is a nuclear ligand-dependent transcription factor expressed by many cells. Ligation of VDR by VitD regulates a wide plethora of genes and physiologic functions through the formation of the complex Vit D-VDR signaling cascade. The influence of Vit D-VDR signaling in host immune response to microbial infection has been of interest to many researchers. This is particularly important in oral health and diseases, as oral mucosa is exposed to a complex microbiota, with certain species capable of causing disruption to immune homeostasis. In this review, we focus on the immune modulatory roles of Vit D in the bone degenerative oral disease, periodontitis.

OBJECTIVE:Although a standard treatment guideline has not been established to date, various treatment modalities have been described in the literature based on the staging of medication-related osteonecrosis of the jaw (MRONJ). The aim of this case series was to describe the outcomes of surgical intervention of MRONJ cases with the adjunctive use of platelet-rich fibrin (PRF).MATERIALS AND METHODS:Thirteen patients under therapy with zoledronic acid, seven of them underwent surgical removal of necrotic bone with debridement, followed by placement of three to four PRF membranes and achieving primary closure. In six patients, PRF was used preventively to avoid MRONJ.RESULTS:The surgical treatment outcomes were successful in all patients, with a follow-up range of 12-48 months. In the presented cases, the intraoral evaluation showed excellent soft tissue healing except for one patient secondary wound healing was reported. Additionally, there was no recurrence of bone exposure in all cases. PRF membranes were comparatively effective in postsurgical pain control.CONCLUSION:The use of PRF could represent a valuable adjunct in the surgical management for advanced stages of MRONJ cases.CLINICAL RELEVANCE:This clinical case series describes the use of PRF membranes as a valuable adjunct in the surgical management of MRONJ patients, especially when treating advanced MRONJ cases. Moreover, PRF demonstrates usefulness in preventing such difficult complications from occurring.

BackgroundPartial edentulism in growing children due to aplasia or trauma poses a difficult situation to manage. We present a case of horizontal ridge augmentation in a growing patient who had trauma in childhood when it was too early to place implants. Methods and ResultsThis patient had a history of trauma, at age 13, that resulted in mandibular fracture and loss of teeth #23-27. The definitive restorative treatment plan was postponed due to the patient's continued growth. At age 18, horizontal bone augmentation was performed in a severely resorbed anterior mandible. After 7 months of healing, 7-8 mm ridge augmentation was achieved, and three implants were placed. Soft tissue augmentation by free gingival graft was performed at implant second stage surgery 4 months later. ConclusionsWhen considering the timing of implant placement in adolescents, the clinician walks a fine line between waiting as long as possible to place the implants and racing against continued resorption of the edentulous alveolar ridge. 70/30 mineralized/demineralized cortical bone allograft and injectable platelet-rich fibrin mix combined with tenting screws and resorbable membranes are useful measures for horizontal ridge augmentation in growing patients. Key pointsWhy is this case new information? There are insufficient data available when considering implant treatment in younger patients. The present case was managed with a variation of the sausage technique described by Urban. The use of allograft, I-PRF, and tenting screws replaced the use of autogenous bone and resulted in exceptional results.What are the keys to the successful management of this case? Delaying treatment until after the critical growth period has passed. Adequate flap release, tension-free primary flap closure, and space maintenance through the use of tenting screws and tacking the membranes using tacking pins provided support for the grafted site.What are the primary limitations to success in this case? The continued growth may cause infra occlusion of the implant-supported bridge.

Periodontitis is the most common chronic, inflammatory oral disease that affects more than half of the population in the United States. The disease leads to destruction of the tooth-supporting tissue called periodontium, which ultimately results in tooth loss if uncured. The interaction between the periodontal microbiota and the host immune cells result in the induction of a non-protective host immune response that triggers host tissue destruction. Certain pathogens have been implicated periodontal disease formation that is triggered by a plethora of virulence factors. There is a collective evidence on the impact of periodontal disease progression on systemic health. Of particular interest, the role of the virulence factors of the periodontal pathogens in facilitating the evasion of the host immune cells and promotion of carcinogenesis has been the focus of many researchers. The aim of this review is to examine the influence of the periodontal pathogens Aggregatibacter actinomycetemcomitans (A. actinomycetemcomitans), Porphyromonas gingivalis (P. gingivalis), and Fusobacterium nucleatum (F. nucleatum) in the modulation of the intracellular signaling pathways of the host cells in order to evade the host immune response and interfere with normal host cell death and the role of their virulence factors in this regard.

Three recent advances in immunology, genetics, and microbiology have ushered in a new era in the continued efforts to better understand and treat oral diseases, moving ever closer to the three Ps of modern healthcare: personalized, predictive, and preventive medicine (PPPM). The discovery of now 15 subtypes of innate lymphoid cells, the refinement of DNA sequencing, and culture-independent characterization of the entire microbial community begin to reveal this complex adaptive network. All these advances warrant a systematic review as they have changed and will continue to change dental medicine. We will update dental professionals on these advances as related to oral diseases and associated pathologies in other organ systems such as premature labor, arthrosclerosis, and cancer. The five objectives are:Introduce the concept of microbiota and microbiomeExplain how we study microbiota and microbiomeDescribe the types and functions of innate lymphoid cellsInventory the unique demands of the oral cavityProvide a heuristic model to integrate the aboveConclusions and expert recommendations.

Human histology provides critical information on the biological potential of various regenerative protocols and biomaterials, which is vital to advancing the field of periodontal regeneration, both in research and clinical practice. Outcomes of histologic studies are particularly valuable when interpreted considering additional evidence available from pre-clinical and clinical studies. One of the best-documented growth factors areproven to have positive effects on a myriad of oral regenerative procedures is recombinant human platelet-derived growth factor-BB (rhPDGF-BB). While a systematic review of clinical studies evaluating rhPDGF in oral regenerative procedures has been recently completed, a review article that focuses on the histologic outcomes is needed. Hence, this communication discusses the histologic effects of rhPDGF-BB on oral and periodontal regenerative procedures, including root coverage and soft tissue augmentation, intrabony defects, furcation defects, peri-implant bone augmentation, and guided bone regeneration. Studies from 1989 to 2022 have been included in this review.

Background: Artificial intelligence (AI) has received enormous attention and has gone through a transition stage from being a pure statistical tool to being one of the main drivers of modern medicine. The purpose of this systematic review was to determine the use of this technology in dental specialties. Types of studies reviewed: This systematic review was conducted according to the PRISMA protocol and the Cochrane Handbook for Systematic Reviews of Interventions. Online databases (PubMed, Ovid via Medline, and web of Science) and manual retrieval of cross references were searched. The selection process yielded 28 studies investigating the acceptability, effectiveness, or feasibility of AI models in various dental subspecialties. The methodological quality and risk of bias of the included studies were analyzed and appraised using the Prediction Study Risk of Bias Assessment Tool (PROBAST). Results: The authors included 28 studies that investigated the use of AI in the dental fields. Six studies in periodontics reported 480 training data sets and 171 test data sets. Eight studies in orthodontics reported 1336 training and 80 test data sets. Five studies in prosthodontics reported 4659 training and 1759 test data sets. Five studies in oral medicine and pathology reported 1151 training and 68 test data sets. Two studies in maxillofacial surgery reported 47 training data sets. Three studies in endodontics reported 142 training and 103 test data sets. Conclusions and practical implications: AI represents an effective approach to analyze clinical dental data. Further studies, including randomized clinical trials, are needed to confirm the value of this concept in dental practice with the goal of providing data-driven, high performance dental care that can rapidly improve the science, economics, and delivery of optimum treatment options for patients.

Periodontitis is a disease originating from bacteria in a susceptible host, in which a nonprotective, chronic inflammatory process results in the destruction of supporting soft and hard tissues surrounding the teeth, eventually causing the loss of dentition over time. The ultimate goal of periodontal treatment is to control the progression of periodontal disease. This is achieved by removing the causative factors and stopping progression of clinical attachment loss and ultimately preventing loss of teeth. Osseous resective surgery (ORS) is one of the treatment modalities used to gain access to the root surfaces and boney defects, visualize removal of plaque and calculus from the root surfaces, and reestablish proper bone and soft tissue contours in order to facilitate removal of plaque by the patient as well as dental professionals. Osseous resective surgery fiber retention (FibReORS) is another less commonly used variation of this resective approach. Although it has shown promising results, little research exists comparing the two approaches. The aim of this review is to revisit the dogma of traditional ORS and highlight the differences between the two surgical approaches in regard to clinical procedures, clinical outcomes, and patient's reported outcomes.

Extensive research in humans and animal models has begun to unravel the complex mechanisms that drive the immunopathogenesis of periodontitis. Neutrophils mount an early and rapid response to the subgingival oral microbiome, producing destructive enzymes to kill microbes. Chemokines and cytokines are released that attract macrophages, dendritic cells, and T cells to the site. Dendritic cells, the focus of this review, are professional antigen-presenting cells on the front line of immune surveillance. Dendritic cells consist of multiple subsets that reside in the epithelium, connective tissues, and major organs. Our work in humans and mice established that myeloid dendritic cells are mobilized in periodontitis. This occurs in lymphoid and nonlymphoid oral tissues, in the bloodstream, and in response to Porphyromonas gingivalis. Moreover, the dendritic cells mature in situ in gingival lamina propria, forming immune conjugates with cluster of differentiation (CD) 4+ T cells, called oral lymphoid foci. At such foci, the decisions are made as to whether to promote bone destructive T helper 17 or bone-sparing regulatory T cell responses. Interestingly, dendritic cells lack potent enzymes and reactive oxygen species needed to kill and degrade endocytosed microbes. The keystone pathogen P. gingivalis exploits this vulnerability by invading dendritic cells in the tissues and peripheral blood using its distinct fimbrial adhesins. This promotes pathogen dissemination and inflammatory disease at distant sites, such as atherosclerotic plaques. Interestingly, our recent studies indicate that such P. gingivalis-infected dendritic cells release nanosized extracellular vesicles called exosomes, in higher numbers than uninfected dendritic cells do. Secreted exosomes and inflammasome-related cytokines are a key feature of the senescence-associated secretory phenotype. Exosomes communicate in paracrine with neighboring stromal cells and immune cells to promote and amplify cellular senescence. We have shown that dendritic cell-derived exosomes can be custom tailored to target and reprogram specific immune cells responsible for inflammatory bone loss in mice. The long-term goal of these immunotherapeutic approaches, ongoing in our laboratory and others, is to promote human health and longevity.

BackgroundThis study aimed to evaluate the effect of scaling and root planing (SRP) on levels of plasma C-reactive protein (CRP). MethodsA total of 30 patients with advanced periodontitis as determined by Clinical Periodontal Sum Score (CPSS) were recruited. Venous whole blood samples were drawn to obtain serum samples from all participants at baseline and 1 month after SRP (post-SRP). High-sensitivity CRP (hs-CRP) was measured by highly sensitive immunoturbidimetric assay. Wilcoxon signed-rank test was used for data analysis. Spearman rank correlation analysis was conducted to test the correlations between CPSS and hs-CRP at baseline and post-SRP. ResultsThere was a statistically significant reduction in the post-SRP CPSS values from the baseline values (z = 4.783, p < 0.0001). Similarly, there was a statistically significant reduction in the post-SRP hs-CRP levels from the baseline levels (z = 4.782, p < 0.0001). Moreover, there was positive association between the baseline levels of CPSS and hs-CRP (rho = 0.5703) and the post-SRP values of CPSS and hs-CRP (rho = 0.7507). ConclusionThe present study suggests that SRP can significantly reduce the levels of CRP.

Porphyromonas gingivalis (P. gingivalis) is a unique pathogen implicated in severe forms of periodontitis (PD), a disease that affects around 50% of the US population. P. gingivalis is equipped with a plethora of virulence factors that it uses to exploit its environment and survive. These include distinct fimbrial adhesins that enable it to bind to other microbes, colonize inflamed tissues, acquire nutrients, and invade cells of the stroma and immune system. Most notable for this review is its ability to invade dendritic cells (DCs), which bridge the innate and adaptive immune systems. This invasion process is tightly linked to the bridging functions of resultant DCs, in that it can disable (or stimulate) the maturation function of DCs and cytokines that are secreted. Maturation molecules (e.g., MHCII, CD80/CD86, CD40) and inflammatory cytokines (e.g., IL-1b, TNFa, IL-6) are essential signals for antigen presentation and for proliferation of effector T-cells such as Th17 cells. In this regard, the ability of P. gingivalis to coordinately regulate its expression of major (fimA) and minor (mfa-1) fimbriae under different environmental influences becomes highly relevant. This review will, therefore, focus on the immunoregulatory role of P. gingivalis fimbriae in the invasion of DCs, intracellular signaling, and functional outcomes such as alveolar bone loss and immune senescence.

(1) Background: The aim of this study was to test whether matrix-bound zoledronate (zol) molecules enhanced the oral biofilm colonization of a mineralized matrix, rendering the alveolar bone more susceptible to medication-related osteonecrosis of the jaw (MRONJ) following invasive dental procedures. (2) Methods: We tested the effect of matrix-bound zol on the growth and attachment of Porphyromonas gingivalis (Pg), Fusobacterium nucleatum (Fn) and Actinomyces israelii (Ai), and whether the nitrogen-containing component of zol contributed to such effect. The role of oral bacteria in the induction of osteonecrosis was then tested using an extra-oral bone defect model. (3) Results: The attachment of biofilm to hydroxyapatite discs increased when the discs were pre-treated with zol. Bacterial proliferation was not affected. Matrix-bound zol was more potent than non-nitrogen-containing etidronate in enhancing the colonization. Stimulation was dampened by pre-treating the bacteria with histidine. The delivery of oral biofilm to a tibial defect caused osteonecrosis in zol-treated rats. (4) Conclusions: We conclude that matrix-bound zol enhances the oral biofilm colonization of hydroxyapatite. This enhancement depended on the presence of the nitrogen-containing group. The oral biofilm rendered the extra-oral bone susceptible to medication-related osteonecrosis, suggesting that it has an important role in the induction of MRONJ.

Dendritic cells are an important link between innate and adaptive immune response. The role of dendritic cells in bone homeostasis, however, is not understood. Osteoporosis medications that inhibit osteoclasts have been associated with osteonecrosis, a condition limited to the jawbone, thus called medication-related osteonecrosis of the jaw. We propose that disruption of the local immune response renders the oral microenvironment conducive to osteonecrosis. We tested whether zoledronate (Zol) treatment impaired dendritic cell (DC) functions and increased bacterial load in alveolar bone in vivo and whether DC inhibition alone predisposed the animals to osteonecrosis. We also analyzed the role of Zol in impairment of differentiation and function of migratory and tissue-resident DCs, promoting disruption of T-cell activation in vitro. Results demonstrated a Zol induced impairment in DC functions and an increased bacterial load in the oral cavity. DC-deficient mice were predisposed to osteonecrosis following dental extraction. Zol treatment of DCs in vitro caused an impairment in immune functions including differentiation, maturation, migration, antigen presentation, and T-cell activation. We conclude that the mechanism of Zol-induced osteonecrosis of the jaw involves disruption of DC immune functions required to clear bacterial infection and activate T cell effector response.

Chronic bone degenerative diseases represent a major threat to the health and well-being of the population, particularly those with advanced age. This study isolated exosomes (EXO), natural nano-particles, from dendritic cells, the "directors" of the immune response, to examine the immunobiology of DC EXO in mice, and their ability to reprogram immune cells responsible for experimental alveolar bone loss in vivo. Distinct DC EXO subtypes including immune-regulatory (regDC EXO), loaded with TGFB1 and IL10 after purification, along with immune stimulatory (stimDC EXO) and immune "null" immature (iDCs EXO) unmodified after purification, were delivered via I.V. route or locally into the soft tissues overlying the alveolar bone. Locally administrated regDC EXO showed high affinity for inflamed sites, and were taken up by both DCs and T cells in situ. RegDC EXO-encapsulated immunoregulatory cargo (TGFB1 and IL10) was protected from proteolytic degradation. Moreover, maturation of recipient DCs and induction of Th17 effectors was suppressed by regDC EXO, while T-regulatory cell recruitment was promoted, resulting in inhibition of bone resorptive cytokines and reduction in osteoclastic bone loss. This work is the first demonstration of DC exosome-based therapy for a degenerative alveolar bone disease and provides the basis for a novel treatment strategy.

Mucosal health and disease is mediated by a complex interplay between the microbiota ("spark") and the inflammatory response ("flame"). Pathobionts, a specific class of microbes, exemplified by the oral microbe Porphyromonas gingivalis, live mostly "under the radar" in their human hosts, in a cooperative relationship with the indigenous microbiota. Dendritic cells (DCs), mucosal immune sentinels, often remain undisturbed by such microbes and do not alert adaptive immunity to danger. At a certain tipping point of inflammation, an "awakening" of pathobionts occurs, wherein their active growth and virulence are stimulated, leading to a dysbiosis. Pathobiont becomes pathogen, and commensal becomes accessory pathogen. The local inflammatory outcome is the Th17-mediated degenerative bone disease, periodontitis (PD). In systemic circulation of PD subjects, inflammatory DCs expand, carrying an oral microbiome and promoting Treg and Th17 responses. At distant peripheral sites, comorbid diseases including atherosclerosis, Alzheimer's disease, macular degeneration, chronic kidney disease, and others are reportedly induced. This review will review the immunobiology of DCs, examine the complex interplay of microbes and DCs in the pathogenesis of PD and its comorbid inflammatory diseases, and discuss the role of apoptosis and autophagy in this regard. Overall, the pathophysiological mechanisms of DC-mediated chronic inflammation and tissue destruction will be summarized.

We have previously shown that deletion of the mitochondrial isoform of the ureahydrolase enzyme (A2) protected against obesity‐induced metabolic dysregulation in “male” mice fed high fat high sucrose diet (HFHS) for 16 weeks. Additionally, A2 expression was upregulated 1.5‐fold in visceral adipose tissue (VAT) of WT "male" mice fed HFHS vs WT fed normal chow diet (ND). Interestingly, A2 expression was elevated 3‐fold in VAT of WT HFHS "female" mice vs WT ND. In the current study, we determined the consequences of global A2 deletion in “female” mice on the same diet protocol. Body weight was measured weekly, adiposity was measured using nuclear magnetic resonance and metabolic activity was assessed using indirect calorimetry. Increases in body weight in WT HFHS female mice, VAT weight and total adiposity were abrogated in A2−/− HFHS mice by 24, 84 and 54%, respectively (p<0.05). Glucose tolerance tests showed a significantly reduced area under the curve in A2−/− HFHS mice vs WT (p<0.05). The leaner phenotype observed in A2−/− mice was in line with the improved metabolic activity as evidenced by increased energy expenditure, volume of O2 consumed and CO2 produced in A2−/− mice fed HFHS vs WT HFHS. Obesity‐induced VAT inflammation and vascular rarefaction contribute to unhealthy expansion of adipose tissue resulting in disrupted metabolic and endocrine functions. VAT sections from WT HFHS stained with isolectin B4 revealed reduced vascular density which was preserved in A2−/− HFHS. Flowcytometry analysis of stromal vascular fraction isolated from VAT of WT HFHS mice showed an increase in proinflammatory M1 macrophages (F4/80+CD11c+) (p=0.06) and a significant decrease in antiinflammatory M2 macrophages (F4/80+CD206+) (p<0.05), the latter was not affected in male mice. These effects were blunted in A2−/− HFHS female mice, reducing the M1/M2 ratio towards a favorable, less inflammatory state. Given the role of A2 in polarizing macrophages to an inflammatory state in vivo, we wished to determine the specific effect of macrophage A2 on inflammatory responses. Peritoneal macrophages from WT and A2−/− female mice were isolated, cultured in vitro and treated with 100 ng/ml lipopolysaccharide (LPS) or vehicle for 24 hr. WT macrophages exposed to LPS showed an activated inflammasome pathway (increased expressions of NLRP3 and pro‐IL‐1β) compared to control group (p<0.05). These effects of LPS were blunted in isolated A2−/− macrophages, indicating that A2 promotes inflammatory macrophage responses in female mice. Collectively, our data show that A2 is a critical mediator of obesity‐induced metabolic dysregulation, VAT vascular rarefaction and increased macrophage inflammatory responses in female mice.Support or Funding InformationR01 HL070215, R01 EY01176 & AHA17PRE33660321

Objective To compare the myeloid and plasmacytoid DC counts and maturation status among subjects with/without generalized periodontitis (GP) and type 2 diabetes mellitus (T2DM). Methods The frequency and maturation status of myeloid and plasmacytoid blood DCs were analyzed by flow cytometry in four groups of 15 subjects: healthy controls, T2DM with generalized CP (T2DM + GP), prediabetes with GP (PD + GP), and normoglycemics with GP (NG + GP). RT-PCR was used to determine levels of Porphyromonas gingivalis in the oral biofilms and within panDCs. The role of exogenous glucose effects on differentiation and apoptosis of healthy human MoDCs was explored in vitro. Results Relative to controls and to NG + GP, T2DM + GP showed significantly lower CD1c + and CD303 + DC counts, while CD141 + DCs were lower in T2DM + GP relative to controls. Blood DC maturation required for mobilization and immune responsiveness was not observed. A statistically significant trend was observed for P. gingivalis levels in the biofilms of groups as follows: controls <NG+GP < PD+GP < T2DM+GP. Moreover, significantly higher P. gingivalis levels were observed in blood DCs of NG + GP than controls, whereas no differences were observed between controls and PD + GP/T2DM + GP. In vitro differentiation of MoDCs was significantly decreased, and apoptosis was increased by physiologically relevant glucose levels. Conclusion Type 2 diabetes mellitus appears to inhibit important DC immune homeostatic functions, including expansion and bacterial scavenging, which might be mediated by hyperglycemia.

Objectives Vitamin D deficiency/insufficiency is a worldwide public health issue that has been linked to numerous inflammatory disorders, including periodontitis. There is increasing support for a role for adequate vitamin D levels in overall health. Populations with darker skin color have a higher prevalence of vitamin D deficiency/insufficiency and periodontitis. The purpose of this small pilot study was to investigate the influence of 12 weeks of 25(OH)D vitamin D supplementation (VDS) on mediators of systemic inflammation in dark-skinned, periodontitis patients. Materials and Methods A total of 23 patients with moderate to severe periodontitis were randomly assigned to the vitamin D group or placebo group and received intensive single visit scaling and root planning to elicit a systemic inflammatory response. Results Vitamin D supplementation increased serum 25(OH)D levels approximately 2-fold over baseline levels; moreover, VDS group had reduced peripheral blood CD3 and CD3+CD8+ cytotoxic T lymphocyte (CTLs) counts and reduced pro-inflammatory salivary cytokines. In contrast, VDS group had higher levels of the autophagy-related proteins and other proteins crucial for anti-microbial autophagy in whole blood PBMCs. Conclusion In conclusion, VDS has multiple benefits for reducing systemic inflammation and promoting induction of autophagy-related proteins related to anti-microbial functions.

Years of human microbiome research have confirmed that microbes rarely live or function alone, favoring diverse communities. Yet most experimental host-pathogen studies employ single species models of infection. Here, the influence of three-species oral microbial consortium on growth, virulence, invasion and persistence in dendritic cells (DCs) was examined experimentally in human monocyte-derived dendritic cells (DCs) and in patients with periodontitis (PD). Cooperative biofilm formation by Streptococcus gordonii, Fusobacterium nucleatum and Porphyromonas gingivalis was documented in vitro using growth models and scanning electron microscopy. Analysis of growth rates by species-specific 16s rRNA probes revealed distinct, early advantages to consortium growth for S. gordonii and F. nucleatum with P. gingivalis, while P. gingivalis upregulated its short mfa1 fimbriae, leading to increased invasion of DCs. F. nucleatum was only taken up by DCs when in consortium with P. gingivalis. Mature consortium regressed DC maturation upon uptake, as determined by flow cytometry. Analysis of dental plaques of PD and healthy subjects by 16s rRNA confirmed oral colonization with consortium members, but DC hematogenous spread was limited to P. gingivalis and F. nucleatum. Expression of P. gingivalis mfa1 fimbriae was increased in dental plaques and hematogenous DCs of PD patients. P. gingivalis in the consortium correlated with an adverse clinical response in the gingiva of PD subjects. In conclusion, we have identified polymicrobial synergy in a three-species oral consortium that may have negative consequences for the host, including microbial dissemination and adverse peripheral inflammatory responses.