Resident memory T cells: Possible players in periodontal disease recurrence.

BACKGROUND/OBJECTIVES: Tissue-resident memory T cells (Trm) represent a new subset of long-lived memory T cells that remain in barrier tissues after previous bacterial or viral infection to support early/immediate defense mechanisms, providing site-specific protection from pathogen challenge. As data on Trm cells in human gingiva are just emerging, the aim of the present study was to explore their presence and distribution in epithelial and connective periodontal tissues in relation to microbial exposure and periodontal damage. MATERIAL AND METHODS: Periodontitis tissue specimens were collected from 20 generalized chronic periodontitis patients at the time of osseous resective surgery. As a control, 18 healthy tissue specimens were harvested each from both the primary flap and the palatal graft in 18 periodontally healthy patients during mucogingival surgeries. As CD69 and CD103 are phenotypic markers associated with tissue residence, intraepithelial and stromal CD103+ and CD69+ cells per high-power field were counted in areas with highest expression. Double immunohistochemistry for CD3 and CD69 was performed to identify T cells. RESULTS: CD69 +and CD103+ cells showed a lymphocytic morphology, and double CD69 and CD3 staining confirmed the T cell phenotype of these cells. CD103 and CD69 expression was significantly enhanced in epithelial and connective tissues from patients with periodontitis compared with healthy controls (P < .001). Significant positive correlation between PD and both CD103 and CD69 epithelial expression was observed in tissue specimens from periodontitis patients (P < .001). CONCLUSION: Within the limits of the present study, these results indicate that Trm cells are higher in periodontitis lesions. They could orchestrate the host response to microbial challenge, leading to a faster reactivation of periodontal disease.

Transglutaminase 2 May Be Associated with Peri-implant Gingival Overgrowth: Preliminary Assessments.

UNLABELLED: Tissue transglutaminase 2 (TG2) is ubiquitously expressed in normal tissues and plays an important role in the pathophysiology of wound healing. An increase in periodontal tissues has been previously reported in cyclosporine-induced gingival overgrowth. PURPOSE: The aim of this study was to explore associations between TG2 expression and the vascularization and maturation processes of peri-implant soft tissues over time. MATERIALS AND METHODS: Edentulous patients proposed for mandibular implant-retained overdentures were included in the study. Biopsies of the peri-implant mucosa were performed at the first surgical stage and at 4, 8, and 12 months after prosthetic load. A follow-up program was directed to record plaque indexes, bleeding on probing data, and pocket probing depth around implants. An evaluation of the vessels' density was carried out by digital virtual microscopy and using an immunohistochemistry approach (antibodies anti-CD31, anti-TG2). A robust multivariable regression model was implemented. RESULTS: According to model results, blood vessel count and probing (as a marker of gingival overgrowth in absence of plaque) significantly decrease over time and are associated with TG2, particularly for values above the median. CONCLUSION: The association of an increased TG2 expression in the extracellular matrix might have a significant impact in the development of gingival overgrowth around a loaded implant.

An alumina toughened zirconia composite for dental implant application: in vivo animal results.

Ceramic materials are widely used for biomedical applications because of their remarkable biological and mechanical properties. Composites made of alumina and zirconia are particularly interesting owing to their higher toughness with respect to the monolithic materials. On this basis, the present study is focused on the in vivo behavior of alumina toughened zirconia (ATZ) dental implants treated with a hydrothermal process. A minipig model was implemented to assess the bone healing through histology and mRNA expression at different time points (8, 14, 28, and 56 days). The novel ATZ implant was compared to a titanium clinical standard. The implants were analyzed in terms of microstructure and surface roughness before in vivo tests. The most interesting result deals with a statistically significant higher digital histology index for ATZ implants with respect to titanium standard at 56 days, which is an unprecedented finding, to the authors' knowledge. Even if further investigations are needed before proposing the clinical use in humans, the tested material proved to be a promising candidate among the possible ceramic dental implants.