Comparing the Healing Potential of Late-Stage Periodontitis and Peri-Implantitis

Evaluation of Bone Loss in Implants Adjacent to a Tooth or Edentulous Area in Peri-Implantitis and Control Murine Models

Peri-implantitis (PI) is an inflammatory disease that affects supportive tissues around dental implants, and its progression eventually leads to bone loss and implant failure. However, PI effects may be different based on the presence or absence of adjacent teeth. The objective was to investigate the differences in bone loss and inflammation between implants placed adjacent to a tooth or edentulous area in a ligature-induced PI model. Materials and methods include the following: Three-week-old C57BL/6J male mice underwent maxillary first (AT; n = 12) or first and second (AE; n = 8) left molar extractions. In both groups, implants were placed in the first molar region 8 weeks after tooth extraction. Each group was further divided into control (C) or ligature (PI) 4 weeks after osseointegration. The mice were euthanized 12-14 days after ligature placement. The samples were analyzed using micro-computed tomography and histology. Statistical analysis was performed using analysis of variance and Tukey multiple comparison test (P < .05). Radiographic linear analysis revealed no statistically significant differences in bone levels between the two C and PI groups. Linear bone loss was significantly greater in the PI group than in the C group. Volumetric analysis yielded similar results. Histologically, hematoxylin and eosin staining revealed no notable differences between the two C and PI groups. The PI groups showed increased levels of inflammatory infiltrates and bone resorption. Qualitative assessment of collagen through picrosirius red staining demonstrated increased collagen disorganization in the PI group compared with that in the C group. No notable differences were observed between the AT and AE groups. The presence or absence of an adjacent tooth does not influence PI-induced soft and hard tissue alterations.

Chamomile Tincture and Lidocaine Hydrochloride Gel Ameliorates Periodontitis: A Preclinical Study

Background/Objectives: Periodontitis is a common oral disease marked by gingival inflammation and alveolar bone loss. This study evaluated the efficacy of chamomile tincture and lidocaine hydrochloride (CLH) gel in mitigating periodontal inflammation and bone loss and uncovered the molecular mechanisms involved, both in vitro and in vivo. Methods: A periodontitis model was induced in Sprague Dawley rats by ligating the mandibular first molars. Sixty rats were divided into four groups: control (C), periodontitis (PD), periodontitis + CLH gel once daily (G1), and periodontitis + CLH gel thrice daily (G3). Clinical, micro-computed tomography (micro-CT), biological, and histological evaluations were performed, focusing on osteoclastogenesis, osteogenesis, and inflammatory cytokine production. The effect of CLH gel on inflammatory responses in RAW264.7 cells was also assessed through co-culture assays under Porphyromonas gingivalis (P. gingivalis) infection, with RNA-sequencing, qPCR, and Western blot analyses to explore underlying mechanisms. Results: CLH gel significantly reduced gingival and systemic inflammation and mitigated bone loss by enhancing the bone volume to tissue volume ratio and trabecular thickness via the RANKL/OPG axis in rats. The G3 group showed marked reductions in osteoclasts and increases in osterix-positive cells compared to other groups. In vitro, CLH gel reduced the inflammatory phenotype of macrophages in the periodontitis microenvironment by modulating Type II interferon (IFN-γ) networks. Conclusions: CLH gel reduced inflammation and bone loss in rat periodontitis, promoting osteogenesis and inhibiting osteoclastogenesis. It also suppressed macrophage inflammation via Type II interferon networks under P. gingivalis stimulation. These findings suggest that CLH gel has potential as an adjunctive therapy for periodontitis.

Single-cell RNA-seq reveals a resolving immune phenotype in the oral mucosa

The oral mucosa is the interface between the host immune response and the oral microbiota. In periodontal disease, the microbial plaque elicits a tissue-destructive immune response. Removal of the microbial stimulus initiates active resolution of inflammatory. Here, we use single-cell RNA-sequencing (scRNA-seq) to characterize the immune response within the oral mucosa across three distinct conditions of periodontal health, disease, and resolution in mice. We report gene expression shifts across the three conditions are driven by macrophage and neutrophils and identify a unique gene signature that characterizes resolution of disease. Macrophage subgroups are identified that demonstrate differential expansion across conditions, including a subgroup that expands during resolution with an immunoregulatory gene signature and enriched for surface marker Cd74. We validate expansion of this subgroup during resolution via flow cytometry. This work presents a robust single-cell dataset of immunological changes in the oral mucosa and identifies a resolution-associated macrophage phenotype in mucosal immunity.

Therapeutic delivery of CCL2 modulates immune response and restores host-microbe homeostasis

Many chronic inflammatory diseases are attributed to disturbances in host-microbe interactions, which drive immune-mediated tissue damage. Depending on the anatomic setting, a chronic inflammatory disease can exert unique local and systemic influences, which provide an exceptional opportunity for understanding disease mechanism and testing therapeutic interventions. The oral cavity is an easily accessible environment that allows for protective interventions aiming at modulating the immune response to control disease processes driven by a breakdown of host-microbe homeostasis. Periodontal disease (PD) is a prevalent condition in which quantitative and qualitative changes of the oral microbiota (dysbiosis) trigger nonresolving chronic inflammation, progressive bone loss, and ultimately tooth loss. Here, we demonstrate the therapeutic benefit of local sustained delivery of the myeloid-recruiting chemokine (C-C motif) ligand 2 (CCL2) in murine ligature-induced PD using clinically relevant models as a preventive, interventional, or reparative therapy. Local delivery of CCL2 into the periodontium inhibited bone loss and accelerated bone gain that could be ascribed to reduced osteoclasts numbers. CCL2 treatment up-regulated M2-macrophage and downregulated proinflammatory and pro-osteoclastic markers. Furthermore, single-cell ribonucleic acid (RNA) sequencing indicated that CCL2 therapy reversed disease-associated transcriptomic profiles of murine gingival macrophages via inhibiting the triggering receptor expressed on myeloid cells-1 (TREM-1) signaling in classically activated macrophages and inducing protein kinase A (PKA) signaling in infiltrating macrophages. Finally, 16S ribosomal ribonucleic acid (rRNA) sequencing showed mitigation of microbial dysbiosis in the periodontium that correlated with a reduction in microbial load in CCL2-treated mice. This study reveals a novel protective effect of CCL2 local delivery in PD as a model for chronic inflammatory diseases caused by a disturbance in host-microbe homeostasis.

Development and applications of peri-implantitis mouse models

OBJECTIVE

Peri-implantitis is one of the most common complications of implants. However, its pathogenesis has not been clarified. In recent years, mouse models are gradually being used in the study of peri-implantitis. This review aims to summarize the methods used to induce peri-implantitis in mice and their current applications.

METHOD

Articles of peri-implantitis mouse models were collected. We analyzed the various methods of inducing peri-implantitis and their application in different areas.

RESULTS

Most researchers have induced peri-implantitis by silk ligatures. Some others have induced peri-implantitis by Pg gavage and LPS injection. Current applications of peri-implantitis mouse models are in the following areas: investigation of pathogenesis and exploration of new interventions, comparison of peri-implantitis with periodontitis, the interaction between systemic diseases and peri-implantitis, etc. CONCLUSION: Silk ligature for 2-4 weeks, Pg gavage for 6 weeks, and LPS injection for 6 weeks all successfully induced peri-implantitis in mice. Mice have the advantages of mature gene editing technology, low cost, and short time to induce peri-implantitis. It has applications in the study of pathogenesis, non-surgical treatments, and interactions with other diseases. However, compared with large animals, mice also have a number of disadvantages that limit their application.

Peri-implantitis increases the risk of medication-related osteonecrosis of the jaws associated with osseointegrated implants in rats treated with zoledronate

This study evaluated the peri-implant tissues under normal conditions and under the influence of experimental peri-implantitis (EPI) in osseointegrated implants installed in the maxillae of rats treated with oncologic dosage of zoledronate. Twenty-eight senescent female rats underwent the extraction of the upper incisor and placement of a titanium dental implant (DI). After eight weeks was installated a transmucosal healing screw on DI. After nine weeks, the following groups were formed: VEH, ZOL, VEH-EPI and ZOL-EPI. From the 9th until the 19th, VEH and VEH-EPI groups received vehicle and ZOL and ZOL-EPI groups received zoledronate. At the 14th week, a cotton ligature was installed around the DI in VEH-EPI and ZOL-EPI groups to induce the EPI. At the 19th week, euthanasia was performed, and the maxillae were processed so that at the implanted sites were analyzed: histological aspects and the percentage of total bone tissue (PTBT) and non-vital bone tissue (PNVBT), along with TNFα, IL-1β, VEGF, OCN and TRAP immunolabeling. ZOL group presented mild persistent peri-implant inflammation, higher PNVBT and TNFα and IL-1β immunolabeling, but lower for VEGF, OCN and TRAP in comparison with VEH group. ZOL-EPI group exhibited exuberant peri-implant inflammation, higher PNVBT and TNFα and IL-1β immunolabeling when compared with ZOL and VEH-EPI groups. Zoledronate disrupted peri-implant environment, causing mild persistent inflammation and increasing the quantity of non-vital bone tissue. Besides, associated with the EPI there were an exacerbated inflammation and even greater increase in the quantity of non-vital bone around the DI, which makes this condition a risk factor for medication-related osteonecrosis of the jaws.

Clinical diagnostic value of IL-14, 1L-16 and SAA in periodontitis

OBJECTIVES

Periodontitis is a chronic infectious disease, which leads to inflammatory destruction of periodontal supporting tissues. Interleukin 14 (IL-14), Interleukin 16 (IL-16) and serum amyloid A (SAA) have been demonstrated to be abnormally expressed in inflammatory diseases. Therefore, this study was performed to analyzed the expression and potential clinical values of IL-14, 1L-16 and SAA in periodontitis.

MATERIALS AND METHODS

A total of 100 periodontitis patients and 100 healthy volunteers were recruited and the saliva and serum samples were collected. Then the C-reactive protein (CRP), procalcitonin (PCT), IL-14, 1L-16 and SAA levels in the saliva and serum of periodontitis patients were measured by Elisa kits. Besides, the significance of CRP, PCT, IL-14, 1L-16 and SAA in periodontitis patients were analyzed by receiver operating characteristic (ROC) analysis.

RESULTS

The results showed that CRP, PCT, IL-14, 1L-16 and SAA levels were significantly increased in the the saliva and serum of the periodontitis patients. Additionally, the area under the curve (AUC) of saliva CRP, PCT, IL-14, 1L-16 and SAA for the diagnosis of periodontitis were 0.9035, 0.9435, 0.9508, 0.9500 and 0.9467, respectively. The AUC of serum CRP, PCT, IL-14, 1L-16 and SAA for the diagnosis of periodontitis were 0.9035, 0.9435, 0.9508, 0.9500 and 0.9467, respectively. What's more, the diagnostic value of IL-14, 1L-16 and SAA were enhanced when combining with CRP and PCT.

CONCLUSION AND CLINICAL RELEVANCE

This study demonstrated that IL-14, IL-16 and SAA expressions were upregulated in periodontitis patients and exhibited a significant significance for periodontitis diagnosis.

Single-cell Transcriptional Analysis of the Cellular Immune Response in the Oral Mucosa of Mice

Periodontal health is dependent on a symbiotic relationship of the host immune response with the oral microbiota. Pathologic shifts of the microbial plaque elicit an immune response that eventually leads to the recruitment and activation of osteoclasts and matrix metalloproteinases and the eventual tissue destruction that is evident in periodontal disease. Once the microbial stimulus is removed, an active process of inflammatory resolution begins. The goal of this work was to use scRNAseq to demonstrate the unique cellular immune response across three distinct conditions of periodontal health, disease, and resolution using mouse models. Periodontal disease was induced using a ligature model. Resolution was modeled by removing the ligature and allowing the mouse to recover. Immune cells (Cd45+) were isolated from the periodontium and analyzed via scRNAseq. Gene signature shifts across the three conditions were characterized and shown to be largely driven by macrophage and neutrophils during the periodontal disease and resolution conditions. Resolution of periodontal disease was characterized by the differential regulation of unique gene subsets. Clustering analysis characterized multiple cellular subpopulations within B Cells, macrophages, and neutrophils that demonstrated differential expansion and contraction across conditions of periodontal health, disease, and resolution. Interestingly, we identified a transcriptionally distinct macrophage subpopulation that expanded during the resolution condition and demonstrated an immunoregulatory gene signature. We identified a cell surface marker for this resolution-associated macrophage subgroup (Cd74) and validated the expansion of this subgroup during resolution via flow cytometry. This work presents a robust immune cell atlas for study of the immunological changes in the oral mucosa during three distinct conditions of periodontal health, disease, and resolution and it improves our understanding of the cellular and molecular markers that characterize health from disease for the development of future diagnostics and therapies.

Evaluation of morphological, histological, and immune-related cellular changes in ligature-induced experimental periodontitis in mice

Background/purpose

The ligature-induced periodontitis model is an effective approach to induce inflammation and bone loss similar to that of human periodontitis. Previous clinical and in vitro studies have shown the involvement of lymphocytes in periodontitis, while, the local and systemic profile of immune cells associated with periodontitis in the ligature-induced periodontitis model in mice remains unclear.

Materials and methods

Experimental periodontitis was constructed in mice by ligating around the maxillary second molars for 14 and 28 days, respectively. Alveolar bone loss was assessed by micro-computed tomography (micro-CT). Hematoxylin and eosin (H&E) and tartrate-resistant acid phosphatase (TRAP) staining were used to evaluate the histological changes in the periodontal tissues. B and T cells in the cervical lymph nodes, spleen, and peripheral blood were analyzed by flow cytometry.

Results

The 14-day ligation effectively induced significant periodontal inflammation and alveolar bone loss in C57BL/6J mice, which were progressive and maintained for a relatively long-term period until day 28. In addition, CD3+ T cells and CD19+ B cells were the dominant population in both health and disease, and the B cell population within the cervical lymph nodes (LN) increased significantly under periodontitis condition, while, no significant differences of the T and B cell population among the spleen and peripheral blood were observed.

Conclusion

The ligature-induced periodontitis mice model was established to perform a longitudinal assessment of changes in periodontal tissues morphologically and histologically, meanwhile, explore the local and systemic changes of the predominant immune-associated cells.

Induction of Periodontitis Using Bacterial Strains Isolated from the Human Oral Microbiome in an Experimental Rat Model

Periodontal disease is that condition resulting in the destruction of periodontal tissues, bone resorption, and tooth loss, the etiology of which is linked to immunological and microbiological factors. The aim of this study was to evaluate the potential trigger of periodontal disease in a rat model using bacterial species incriminated in the pathology of human periodontitis and to establish their optimal concentrations capable of reproducing the disease, with the idea of subsequently developing innovative treatments for the condition. In this study, we included 15 male Wistar rats, aged 20 weeks, which we divided into three groups. In each group, we applied ligatures with gingival retraction wire on the maxillary incisors. The ligature and the gingival sac were contaminated by oral gavage with a mixture of fresh cultures of Aggregatibacter actinomycetemcomitans (A.a), Fusobacterium nucleatum (F.n) and Streptococcus oralis (S.o) in concentrations of 108, 109, and 1010 CFU/mL each for 5 days a week for 4 weeks. During the clinical monitoring period of 28 days, overlapped with the period of oral contamination, we followed the expression of clinical signs specific to periodontitis. We also monitored the evolution of body weight and took weekly samples from the oral cavity for the microbiological identification of the tested bacteria and blood samples for hematological examination. At the end of the study, the animals were euthanized, and the ligated incisors were taken for histopathological analysis. The characteristic symptomatology of periodontal disease was expressed from the first week of the study and was maintained until the end, and we were able to identify the bacteria during each examination. Hematologically, the number of neutrophils decreased dramatically (p < 0.0001) in the case of the 109 group, unlike the other groups, as did the number of lymphocytes. Histopathologically, we identified neutrophilic infiltrate in all groups, as well as the presence of coccobacilli, periodontal tissue hyperplasia, and periodontal lysis. In the 109 group, we also observed pulpal tissue with necrotic bone fragments and pyogranulomatous inflammatory reaction. By corroborating the data, we can conclude that for the development of periodontal disease using A.a, F.n, and S.o, a concentration of 109 or 1010 CFU/mL is required, which must necessarily contaminate a ligature thread applied to the level of the rat's dental pack.

Clinical efficacy of adjunctive methods for the non-surgical treatment of peri-implantitis: a systematic review and meta-analysis

BACKGROUND

The aim of this systematic review (SR) was to evaluate the clinical efficacy of different adjunctive methods/therapies to the non-surgical treatment (NST) of peri-implantitis.

MATERIALS AND METHODS

The protocol of the review was registered in PROSPERO database (CRD42022339709) and was designed according to PRISMA statement. Electronic and hand searches were performed to identify randomized clinical trials (RCTs) comparing non-surgical treatment of peri-implantitis alone versus NST plus any adjunctive method/treatment. The primary outcome was probing pocket depth (PPD) reduction.

RESULTS

Sixteen RCTs were included. Only 2 out of 1189 implants were lost and follow-up ranged from 3 to 12 months. PPD reduction across the studies varied from 0.17 to 3.1 mm, while defect resolution from 5.3% to 57.1%. Systemic antimicrobials were associated to higher PPD reduction (1.56 mm; [95% CI 0.24 to 2.89]; p = 0.02) with high heterogeneity, and treatment success (OR = 3.23; [95% CI 1.17 to 8.94]; p = 0.02), compared to NST alone. No differences were found with adjunctive local antimicrobials and lasers for PPD and bleeding on probing (BoP) reduction.

CONCLUSIONS

Non-surgical treatment with or without adjunctive methods may reduce PPD and BoP even if complete resolution of the pocket is unpredictable. Among possible adjunctive methods, only systemic antibiotics seems to provide further benefits, but their usage should be considered with caution.

Determination of immune factor levels in serum and local hematoma samples of osteoporotic fracture patients and clinical study of the effect of active vitamin D3 treatment on immune factor levels

OBJECTIVE

The aim of this study was to investigate changes in systemic and local immune factors, namely, interleukin (IL)-1β, IL-6 and tumor necrosis factor (TNF)-α, in patients with and without osteoporotic fractures and to explore the effects of active vitamin D3 treatment on immune function and fracture prognosis in patients with osteoporotic fractures.

METHOD

The mRNA expression levels of IL-1β, IL-6 and TNF-α were measured before the operation. After the operation, the patients in the control group were treated with conventional fracture treatment and calcium supplementation, and the patients in the treatment group were treated with calcium plus active vitamin D3 in addition to conventional fracture treatment. The serum of each patient was collected on the seventh day after the operation.

RESULTS

The expression levels of the three immune factors (IL-1β, IL-6 and TNF-α) in the fracture end hematoma samples were significantly positively correlated with those in the serum samples (P < 0.05). The mean values of the serums of IL-1β, IL-6 and TNF-α in the osteoporosis group were significantly higher than those in the non-osteoporosis group (P < 0.05). The average number of hematomas in the osteoporosis group was significantly higher than that in the non-osteoporosis group (P < 0.05). The results for the active vitamin D3 treatment group were significantly lower than those for the control group (P < 0.05). The mean wrist function score of the active vitamin D3 treatment group was significantly better than that of the control group (P < 0.05). The average fracture healing time of the treatment group was significantly shorter than that of the control group (P < 0.05).

CONCLUSION

The relative expression of IL-1β, IL-6, and TNF-α in the fracture end hematoma samples was positively correlated with the corresponding levels of these immune factors in the serum samples. The levels of IL-1β, IL-6 and TNF-α in the serum and fracture end hematoma samples of the osteoporotic fracture patients were higher than those of the non-osteoporotic fracture patients. Active vitamin D3 treatment promoted fracture healing by affecting the levels of these immune factors.

Rodent peri-implantitis models: a systematic review and meta-analysis of morphological changes

PURPOSE

Rodent models have emerged as an alternative to established larger animal models for peri-implantitis research. However, the construct validity of rodent models is controversial due to a lack of consensus regarding their histological, morphological, and biochemical characteristics. This systematic review sought to validate rodent models by characterizing their morphological changes, particularly marginal bone loss (MBL), a hallmark of peri-implantitis.

METHODS

This review was conducted following the Preferred Reporting Items for Systematic Reviews and Meta-Analysis (PRISMA) guidelines. A literature search was performed electronically using MEDLINE (PubMed), and Embase, identifying pre-clinical studies reporting MBL after experimental peri-implantitis induction in rodents. Each study's risk of bias was assessed using the Systematic Review Center for Laboratory animal Experimentation (SYRCLE) risk of bias tool. A meta-analysis was performed for the difference in MBL, comparing healthy implants to those with experimental peri-implantitis.

RESULTS

Of the 1,014 unique records retrieved, 23 studies that met the eligibility criteria were included. Peri-implantitis was induced using 4 methods: ligatures, lipopolysaccharide, microbial infection, and titanium particles. Studies presented high to unclear risks of bias. During the osseointegration phase, 11.6% and 6.4%-11.3% of implants inserted in mice and rats, respectively, had failed to osseointegrate. Twelve studies were included in the meta-analysis of the linear MBL measured using micro-computed tomography. Following experimental peri-implantitis, the MBL was estimated to be 0.25 mm (95% confidence interval [CI], 0.14-0.36 mm) in mice and 0.26 mm (95% CI, 0.19-0.34 mm) in rats. The resulting peri-implant MBL was circumferential, consisting of supra- and infrabony components.

CONCLUSIONS

Experimental peri-implantitis in rodent models results in circumferential MBL, with morphology consistent with the clinical presentation of peri-implantitis. While rodent models are promising, there is still a need to further characterize their healing potentials, standardize experiment protocols, and improve the reporting of results and methodology.

TRIAL REGISTRATION

PROSPERO Identifier: CRD42020209776.

Physicochemical, Antibacterial Properties, and Compatibility of ZnO-NP/Chitosan/β-Glycerophosphate Composite Hydrogels

In this study we aimed to develop novel ZnO-NP/chitosan/β-glycerophosphate (ZnO-NP/CS/β-GP) antibacterial hydrogels for biomedical applications. According to the mass fraction ratio of ZnO-NPs to chitosan, mixtures of 1, 3, and 5% ZnO-NPs/CS/β-GP were prepared. Using the test-tube inversion method, scanning electron microscopy and Fourier-transform infrared spectroscopy, the influence of ZnO-NPs on gelation time, chemical composition, and cross-sectional microstructures were evaluated. Adding ZnO-NPs significantly improved the hydrogel's antibacterial activity as determined by bacteriostatic zone and colony counting. The hydrogel's bacteriostatic mechanism was investigated using live/dead fluorescent staining and scanning electron microscopy. In addition, crystal violet staining and MTT assay demonstrated that ZnO-NPs/CS/β-GP exhibited good antibacterial activity in inhibiting the formation of biofilms and eradicating existing biofilms. CCK-8 and live/dead cell staining methods revealed that the cell viability of gingival fibroblasts (L929) cocultured with hydrogel in each group was above 90% after 24, 48, and 72 h. These results suggest that ZnO-NPs improve the temperature sensitivity and bacteriostatic performance of chitosan/β-glycerophosphate (CS/β-GP), which could be injected into the periodontal pocket in solution form and quickly transformed into hydrogel adhesion on the gingiva, allowing for a straightforward and convenient procedure. In conclusion, ZnO-NP/CS/β-GP thermosensitive hydrogels could be expected to be utilized as adjuvant drugs for clinical prevention and treatment of peri-implant inflammation.

Application of Ligature-Induced Periodontitis in Mice to Explore the Molecular Mechanism of Periodontal Disease

Periodontitis is an inflammatory disease characterized by the destruction of the periodontium. In the last decade, a new murine model of periodontitis has been widely used to simulate alveolar bone resorption and periodontal soft tissue destruction by ligation. Typically, 3-0 to 9-0 silks are selected for ligation around the molars in mice, and significant bone loss and inflammatory infiltration are observed within a week. The ligature-maintained period can vary according to specific aims. We reviewed the findings on the interaction of systemic diseases with periodontitis, periodontal tissue destruction, the immunological and bacteriological responses, and new treatments. In these studies, the activation of osteoclasts, upregulation of pro-inflammatory factors, and excessive immune response have been considered as major factors in periodontal disruption. Multiple genes identified in periodontal tissues partly reflect the complexity of the pathogenesis of periodontitis. The effects of novel treatment methods on periodontitis have also been evaluated in a ligature-induced periodontitis model in mice. This model cannot completely represent all aspects of periodontitis in humans but is considered an effective method for the exploration of its mechanisms. Through this review, we aimed to provide evidence and enlightenment for future studies planning to use this model.

Morphological and Molecular-Biological Features of Inflammatory and Regeneratory Processes in Peridont Tissues with Periimplantitis and Periodontitis

A morphological and immunohistochemical study of periodontal tissues was performed in patients with chronic generalized periodontitis who underwent dental implantation. We studied 44 biopsy specimens from 21 patients (13 women and 8 men) aged 35-60 years with a diagnosis of periimplantation mucositis (7 patients), periimplantitis (8 patients), and severe chronic generalized periodontitis (6 patients). It was established that periimplantitis differs from periimplantation mucositis by a more pronounced inflammatory reaction with a clear predominance of plasma cells in the infiltrate, which captures the fibrous capsule around the implant, destroys it and further spreads to the bone tissue. Based on the immunohistochemical differences in SMA, VEGF, and Ki-67, it is concluded that periimplantation mucositis and periimplantitis are successive stages of progression of the same process. When comparing chronic generalized periodontitis and periimplantitis, the latter shows much more pronounced inflammatory and destructive processes in the area of the implant, due to the addition of immune inflammation, impaired regeneration processes, and destruction of bone tissue.

Q-Switch Nd:YAG Laser-Assisted Elimination of Multi-Species Biofilm on Titanium Surfaces

(1) Background: The relatively high prevalence of peri-implantitis (PI) and the lack of a standard method for decontamination of the dental implant surface have pushed us to conduct further research in the field. Bacterial biofilms were found to play a primordial role in the etiology of PI. Therefore, the aim is to evaluate the efficacy of a laser-assisted elimination of biofilm protocol in the removal of a multi-species biofilm on titanium surfaces. (2) Methods: In total, 52 titanium discs (grade 4) were used. The study group consisted of 13 titanium disks contaminated with multi-species biofilms and subsequently irradiated with the laser (T + BF + L). The control groups consisted of the following types of titanium disks: 13 contaminated with multi-species biofilms (T + BF), 13 sterile and irradiated (T + L), 13 sterile and untreated (T). Q-Switch Nd:YAG laser Irradiation parameters were the following: energy density equal to 0.597 J/cm² per pulse, power equal to 270 milliwatt per pulse, 2.4 mm of spot diameter, and 10 Hz repetition rate for pulse duration of six nanoseconds (ns). The laser irradiation was made during 2 s of total time in non-contact and at 0.5 mm away from the titanium disc surface. After treatment, presence of biofilms on the disks was evaluated by staining with crystal violet (CV), which was measured as optical density at six hundred thirty nm, and statistical analyses were done. (3) Results: the optical density values were 0.004 ± 0.004 for the study group T + BF + L, 0.120 ± 0.039 for group T + BF, 0.006 ± 0.003 for group T + L, and 0.007 ± 0.007 for group T. For the study group, laser treatment resulted in a total elimination of the biofilm, with mean values statistically significantly lower than those of contaminated titanium surfaces and similar to those of sterile titanium surfaces. (4) Conclusions: Our irradiation protocol provided a significant elimination of the multi-species biofilm on titanium surfaces. Laser treated titanium surfaces were biofilm-free, similar to the sterile ones.

Characterization of ligature-induced experimental periodontitis

We sought to better characterize the progression of periodontal tissue breakdown in rats induced by a ligature model of experimental periodontal disease (PD). A total of 60 male Sprague-Dawley rats were evenly divided into an untreated control group and a PD group induced by ligature bilaterally around first and second maxillary molars. Animals were sacrificed at 1, 3, 5, 7, 14, and 21 days after the induction of PD. Alveolar bone loss was evaluated by histomorphometry and microcomputed tomography (μCT). The immune-inflammatory process in the periodontal tissue was assessed using descriptive histologic analysis and quantitative polymerase chain reaction (qPCR). This ligature model resulted in significant alveolar bone loss and increased inflammatory process of the periodontal tissues during the initial periods of evaluation (0-14 days). A significant increase in the gene expression of pro-inflammatory cytokines, interleukin-1β (IL-1β), interleukin-6 (IL-6), and tumor necrosis factor-α (TNF-α), and proteins involved in osteoclastogenesis, receptor activator of nuclear factor-k B ligand (RANKL) and osteoprotegerin (OPG) was observed in the first week of analysis. In the later periods of evaluation (14-21 days), no significant alterations were noted with regard to inflammatory processes, bone resorption, and expression of cytokine genes. The ligature-induced PD model resulted in progressive alveolar bone resorption with two different phases: Acute (0-14 days), characterized by inflammation and rapid bone resorption, and chronic (14-21 days) with no significant progression of bone loss. Furthermore, the gene expressions of IL-6, IL-1β, TNF-α, RANKL, and OPG were highly increased during the progress of PD in the early periods. RESEARCH HIGHLIGHTS: Ligature-induced bone resorption in rats occurred in the initial periods after disease induction The bone resorption was characterized by two distinct phases: Acute (0-14 days), with pronounced inflammation and alveolar bone loss Chronic phase (14-21 days): No further disease progression Several pro-inflammatory cytokines were increased during the progress of periodontitis.