Disparity in the Influence of Implant Provisional Materials on Human Gingival Fibroblasts with Different Phases of Cell Settlement: An In Vitro Study.

The development of healthy peri-implant soft tissues is critical to achieving the esthetic and biological success of implant restorations throughout all stages of healing and tissue maturation, starting with provisionalization. The purpose of this study was to investigate the effects of eight different implant provisional materials on human gingival fibroblasts at various stages of cell settlement by examining initial cell attachment, growth, and function. Eight different specimens-bis-acrylic 1 and 2, flowable and bulk-fill composites, self-curing acrylic 1 and 2, milled acrylic, and titanium (Ti) alloy as a control-were fabricated in rectangular plates (n = 3). The condition of human gingival fibroblasts was divided into two groups: those in direct contact with test materials (contact experiment) and those in close proximity to test materials (proximity experiment). The proximity experiment was further divided into three phases: pre-settlement, early settlement, and late settlement. A cell culture insert containing each test plate was placed into a well where the cells were pre-cultured. The number of attached cells, cell proliferation, resistance to detachment, and collagen production were evaluated. In the contact experiment, bis-acrylics and composites showed detrimental effects on cells. The number of cells attached to milled acrylic and self-curing acrylic was relatively high, being approximately 70% and 20-30%, respectively, of that on Ti alloy. There was a significant difference between self-curing acrylic 1 and 2, even with the same curing modality. The cell retention ability also varied considerably among the materials. Although the detrimental effects were mitigated in the proximity experiment compared to the contact experiment, adverse effects on cell growth and collagen production remained significant during all phases of cell settlement for bis-acrylics and flowable composite. Specifically, the early settlement phase was not sufficient to significantly mitigate the material cytotoxicity. The flowable composite was consistently more cytotoxic than the bulk-fill composite. The harmful effects of the provisional materials on gingival fibroblasts vary considerably depending on the curing modality and compositions. Pre-settlement of cells mitigated the harmful effects, implying the susceptibility to material toxicity varies depending on the progress of wound healing and tissue condition. However, cell pre-settlement was not sufficient to fully restore the fibroblastic function to the normal level. Particularly, the adverse effects of bis-acrylics and flowable composite remained significant. Milled and self-curing acrylic exhibited excellent and acceptable biocompatibility, respectively, compared to other materials.

Involvement of mast cells and microvessels density in reactive lesions of oral cavity: A comparative immunohistochemical study.

In view of the similarity of clinicopathological features between reactive lesions of the oral cavity, the objective of the present study was to investigate the density of MCs (mast cells) and microvessels in a series of these lesions. Thirty-seven cases of reactive lesions including fibrous hyperplasia (FH, n=10), inflammatory fibrous hyperplasia (IFH, n=10), peripheral giant cell lesion (PGCL, n=10) and lobular capillary hemangioma (LCH, n=7) were investigated using immunohistochemistry for mast cell tryptase and CD34. For comparative purposes, central giant cell lesions (CGCL, n=5) were included. A higher MC density was observed in LCH (37.01), while CGCL exhibited the lowest density (n=8.14). There was a significant difference in MC density when all reactive lesions were compared to CGCL (p=0.001). The largest mean density of microvessels was observed in LCH (n=21.69). The smallest number was observed in CGCL (n=6.24). There was a significant difference in microvessel density when the reactive lesions were compared to CGCL (p=0.003). There was a significant and direct correlation between the density of MCs and microvessels only for IFH (p=0.048) and CGCL (p=0.005). A significant and direct correlation between the mean density of MCs and microvessels was observed when the reactive lesions were analyzed as a whole (p=0.005). Our results suggest that mast cells contribute to the connective tissue framework and angiogenic function, as well as the development, of reactive lesions of the oral cavity, including FH, IFH, LCH and PGCL.

Insulin-like Growth Factor II Messenger RNA-binding Protein 3 in Salivary Gland Tumors.

Insulin-like growth factor II mRNA-binding protein 3 (IMP3) is strongly expressed in malignant tumors and has been associated with their aggressive behavior. The aim of this study was to evaluate the presence of IMP3 in a series of salivary gland tumors. The sample consisted of 9 pleomorphic adenomas (PA), 14 adenoid cystic carcinomas (ACC), and 13 mucoepidermoid carcinomas (MEC) that were investigated by immunohistochemical technique. All cases of PA and MEC were positive for IMP3 particularly in the cytoplasm. PA showed 4 cases as high expression and 6 as low expression. MEC showed 10 cases as low expression and 3 as high expression. For ACC, 4 cases were high expression, whereas 6 cases were low expression. No significant difference was observed between tumors (P>0.05, Fisher's test) when both scores of IMP3 were compared. This study showed that MEC seems to be more sensitive to IMP3 than ACC and provided an insight into this protein in salivary gland tumors. Furthermore, although IMP3 is not a specific diagnostic marker to distinguish the tumors studied, it seems to mediate cell adhesion and migration in these tumors. Further studies should be performed to better understand the IMP3 biology in salivary gland tumors.