Drug-Induced Gingival Overgrowth-Molecular Aspects of Drug Actions.

Drug-induced gingival overgrowth (DIGO) is one of the side effects produced by therapeutic agents, most commonly phenytoin, nifedipine and cyclosporin A. However, the precise mechanism of DIGO is not entirely understood. A literature search of the MEDLINE/PubMed databases was conducted to identify the mechanisms involved in DIGO. The available information suggests that the pathogenesis of DIGO is multifactorial, but common pathogenic sequelae of events emerge, i.e., sodium and calcium channel antagonism or disturbed intracellular handling of calcium, which finally lead to reductions in intracellular folic acid levels. Disturbed cellular functions, mainly in keratinocytes and fibroblasts, result in increased collagen and glycosaminoglycans accumulation in the extracellular matrix. Dysregulation of collagenase activity, as well as integrins and membrane receptors, are key mechanisms of reduced degradation or excessive synthesis of connective tissue components. This manuscript describes the cellular and molecular factors involved in the epithelial-mesenchymal transition and extracellular matrix remodeling triggered by agents producing DIGO.

Biological Roles of Fibroblasts in Periodontal Diseases.

Periodontal diseases include periodontitis and gingival overgrowth. Periodontitis is a bacterial infectious disease, and its pathological cascade is regulated by many inflammatory cytokines secreted by immune or tissue cells, such as interleukin-6. In contrast, gingival overgrowth develops as a side effect of specific drugs, such as immunosuppressants, anticonvulsants, and calcium channel blockers. Human gingival fibroblasts (HGFs) are the most abundant cells in gingival connective tissue, and human periodontal ligament fibroblasts (HPLFs) are located between the teeth and alveolar bone. HGFs and HPLFs are both crucial for the remodeling and homeostasis of periodontal tissue, and their roles in the pathogenesis of periodontal diseases have been examined for 25 years. Various responses by HGFs or HPLFs contribute to the progression of periodontal diseases. This review summarizes the biological effects of HGFs and HPLFs on the pathogenesis of periodontal diseases.

Bibliometric analysis of research trends and characteristics of drug-induced gingival overgrowth.

Objectives: Drug-induced gingival overgrowth (DIGO) is a frequent adverse medication reaction that is generally caused by cyclosporine, phenytoin, and nifedipine, which belong to the category of immunosuppressants, anticonvulsants, and calcium channel blockers, respectively. This bibliometric analysis aims to depict the main citation characteristics and analyze the research trends in DIGO investigations. Methods: An exhaustive search was performed in the Scopus database to create the bibliometric list of DIGO in the syntax. Furthermore, the information related to the number of citations, drugs related to DIGO, study topic and design, authorship, publication year, journal, contributing institution, country of origin, and the department was extracted. Results: In total, 399 papers on DIGO were retrieved in this study. The total number of citations and that after the removal of self-citations were 7,814 and 7,314, respectively. The mean number of citations was 19.6 in a range of 0-608. The main paper types were articles (76.94%) and reviews (19.55%). A remarkable increasing trend in the number of citations has been observed since 1994. Cyclosporine (44.89%) is the most commonly used drug that shares a close relationship with DIGO, followed by phenytoin (18.22%), nifedipine (17.93%), and amlodipine (6.81%). The review (27.82%) type constituted the most widely used design in the DIGO studies. According to the top 20 keywords, the risk factors and pathogenesis of DIGO have been prominent topics of research works for several years. Conclusions: This bibliometric analysis will facilitate the understanding of researchers and clinicians, especially those at the beginning of their careers in periodontology on DIGO, by identifying landmark research and providing an overview of this field.

Oral findings in kidney transplant children and adolescents.

BACKGROUND: Children and adolescents undergoing kidney transplantation may present oral conditions after the procedure, but a few studies have recently described them. AIM: To describe the oral conditions of post-renal transplant children and adolescents. DESIGN: Two calibrated dentists examined all the participants by assessing caries experience, enamel defects, periodontal condition and soft tissue lesions. RESULTS: A total of 120 participants were included in the study, in which 63 (52.5%) were male and 57 (47.5%) were female, with a mean age of 12.78 ± 3.9 years. Among the participants, 104 (86.7%) showed at least one oral change directly related to kidney disease. The most frequent oral findings were enamel defect (49/120; 40.8%) and drug-induced gingival overgrowth (DIGO) (20/120; 16.7%). Gingival bleeding was observed on probing in 115 (95.8%) participants, whereas 69 (57.5%) presented dental calculus and 51 (42.5%) had caries experience. CONCLUSION: Gingival bleeding, enamel defects and DIGO were the most frequent oral findings in kidney transplant children and adolescents. The use of amlodipine and anticonvulsants was associated with DIGO, and there was a positive correlation between oral ulcers and use of everolimus.

Therapeutic potential of proteasome inhibitors for dihydropyridine-induced gingival overgrowth.

OBJECTIVES: NF-κB plays a crucial role in collagen overproduction in dihydropyridine-induced gingival overgrowth (DIGO) fibroblasts. We aim to investigate the role of the kappa B (IκB) kinase (IKK)-NF-κB pathway and downstream collagen type I (Col I) synthesis in DIGO cells and to demonstrate the therapeutic strategy of interference of this pathway with proteasome inhibitors. METHODS: Gingival fibroblasts from DIGO (n = 5) and healthy (n = 5) patients were selected and stimulated with IL-1ß, nifedipine, or both. All experiments were run in triplicate and independently for each primary cell sample. RESULTS: The results demonstrated that both drugs additively mediated NF-κB activity by activating IKKα/ß phosphorylation. They also triggered nuclear translocation of NF-κB, Rela, and p50 (*p < .05) and increased Col I production in both healthy and DIGO cells. The addition of proteasome inhibitors, including bortezomib and MG132, promoted the accumulation of phosphorylated p-IκBα, prevented the subsequent cytosol-to-nuclear translocation of p50 and Rela (*p < .05), and abbreviated the biosynthesis of Col I in DIGO cells. CONCLUSIONS: We suggested that IKK-IκBα activation is mediated by proinflammatory cytokines and CCBs in DIGO cells and triggers downstream NF-κB-Col I synthesis. Proteasome inhibitors may strategically interfere with the IKK-IκBα-NF-κB-Col I pathway and inhibit the etiopathogenesis of DIGO.

Immunohistochemical study of experimentally drug-induced gingival overgrowth.

The increasing frequency of using in the medical practice drugs that have the potential to induce gingival overgrowth (GO) and the existence of many unknown aspects in GO etiopathogenesis have prompted us to carry out this immunohistochemical experimental animal study. We conducted a cell proliferation study by Ki67 immunostaining and a cytokeratin (CK) study using anti-pan-CK AE1∕AE3 and anti-MNF116 antibodies, investigating the differences induced by different classes of drugs that are more frequently involved in the induction of GO. The results of our study indicate that CK AE1∕AE3 plays an important role not only in normal cellular proliferation, but also in hypertrophic tissues, and can be considered a marker of the proliferative process occurring in GO. Immunostaining for the anti-MNF116 antibody was weaker and inconsistent in intensity compared to anti-CK AE1∕AE3 antibody, its staining pattern appearing as diffuse or zonal.

Molecular Aspects of Drug-Induced Gingival Overgrowth: An In Vitro Study on Amlodipine and Gingival Fibroblasts.

Gingival overgrowth is a serious side effect that accompanies the use of amlodipine. Several conflicting theories have been proposed to explain the fibroblast's function in gingival overgrowth. To determine whether amlodipine alters the fibrotic response, we investigated its effects on treated gingival fibroblast gene expression as compared with untreated cells. MATERIALS AND METHODS: Fibroblasts from ATCC® Cell Lines were incubated with amlodipine. The gene expression levels of 12 genes belonging to the "Extracellular Matrix and Adhesion Molecules" pathway was investigated in treated fibroblasts cell culture, as compared with untreated cells, by real time PCR. RESULTS: Most of the significant genes were up-regulated. (CTNND2, COL4A1, ITGA2, ITGA7, MMP10, MMP11, MMP12, MMP26) except for COL7A1, LAMB1, MMP8, and MMP16, which were down-regulated. CONCLUSION: These results seem to demonstrate that amlodipine has an effect on the extracellular matrix of gingival fibroblast. In the future, it would be interesting to understand the possible effect of the drug on fibroblasts of patients with amlodipine-induced gingival hyperplasia.

Effects of cyclosporin, nifedipine and phenytoin on gingival myofibroblast transdifferentiation in monkeys

Abstract Objective: Myofibroblasts have been associated with the development of several pathologic fibrotic conditions. This longitudinal study aims to assess the proliferative and antiapoptotic effects of cyclosporin, nifedipine and phenytoin on gingival connective tissue cells of nonhuman primate, as well as to analyze a possible role of myofibroblasts in gingival overgrowth. Materials and Methods: Gingival samples from the right superior canine area were obtained from 12 male monkeys ( Sapajus spp ) to comprise the control group. After one week, the animals were randomly assigned to three groups, which received daily oral doses of cyclosporin, nifedipine or phenytoin for 120 days. Gingival samples were collected from the left superior canine area of two animals of each group at 52 and 120 days. Histological sections were stained with hematoxylin and eosin, and immunoreacted against α-SMA, Ki- 67 and bcl-2. Results: α-SMA immunoreaction was negative in the control and experimental groups. Similarly, no difference between groups concerning immunostaining against Ki-67 and bcl-2 was observed in connective tissue cells. Conclusion: Based on this methodology, it may be concluded that gingival overgrowths induced by cyclosporin, nifedipine and phenytoin are not associated with neither myofibroblast transdifferentiation, proliferation nor apoptosis of gingival connective cells in monkeys.

Effects of cyclosporin, nifedipine and phenytoin on gingival myofibroblast transdifferentiation in monkeys.

OBJECTIVE: Myofibroblasts have been associated with the development of several pathologic fibrotic conditions. This longitudinal study aims to assess the proliferative and antiapoptotic effects of cyclosporin, nifedipine and phenytoin on gingival connective tissue cells of nonhuman primate, as well as to analyze a possible role of myofibroblasts in gingival overgrowth. MATERIALS AND METHODS: Gingival samples from the right superior canine area were obtained from 12 male monkeys ( Sapajus spp ) to comprise the control group. After one week, the animals were randomly assigned to three groups, which received daily oral doses of cyclosporin, nifedipine or phenytoin for 120 days. Gingival samples were collected from the left superior canine area of two animals of each group at 52 and 120 days. Histological sections were stained with hematoxylin and eosin, and immunoreacted against α-SMA, Ki- 67 and bcl-2. RESULTS: α-SMA immunoreaction was negative in the control and experimental groups. Similarly, no difference between groups concerning immunostaining against Ki-67 and bcl-2 was observed in connective tissue cells. CONCLUSION: Based on this methodology, it may be concluded that gingival overgrowths induced by cyclosporin, nifedipine and phenytoin are not associated with neither myofibroblast transdifferentiation, proliferation nor apoptosis of gingival connective cells in monkeys.

Phenytoin activates Smad3 phosphorylation and periostin expression in drug-induced gingival enlargement.

Drug-induced gingival enlargement (DIGE) is a fibrotic condition associated with systemic administration of the anti-epileptic drug, phenytoin. We have previously demonstrated that periostin, which is transforming growth factor-beta (TGF-ß) inducible gene, is upregulated in various fibrotic conditions including gingival enlargement associated with nifedipine. The objective of this study was to assess periostin expression in phenytoin-induced gingival enlargement (PIGE) tissues and to investigate the mechanisms underlying periostin expression. Human PIGE tissues were assessed using Masson's trichrome, with cell infiltration and changes in extracellular matrix composition characterized through labeling with antibodies to periostin, phospho-SMAD 3, TGF-ß, as well as the macrophage markers CD68 and RM3/1. Using human gingival fibroblasts (HGFs) in vitro we examined the pathways through which phenytoin acts on fibroblasts. In PIGE tissues, which demonstrate altered collagen organization and increased inflammatory cell infiltration, periostin protein was increased compared with healthy tissues. p-SMAD2/3, the transcription factor associated with canonical TGF-ß signaling, is localized to the nuclei in both gingival fibroblasts and oral epithelial cells in PIGE tissues, but not in healthy tissue. In vitro culture of HGFs with 15 and 30 µg/ml of phenytoin increased periostin protein levels, which correlated with p-SMAD3 phosphorylation. Inhibition of canonical TGF-ß signaling with SB431542 significantly reduced phenytoin induction of SMAD3 phosphorylation and periostin expression in HGFs. Analysis of PIGE tissues showed a subset of CD68 stained macrophages were TGF-ß positive and that RM1/3 regenerative macrophages were present in the tissues. Our results demonstrate that phenytoin up-regulates periostin in HGFs in a TGF-ß-dependent manner.

Gingival leukemic infiltration as the first manifestation of acute myeloid leukemia.

Leukemic infiltration of the gingival tissue associated or not with gingival enlargement may be the first manifestation of acute leukemia, despite being rarely reported in the literature. A 10-year-old female patient presented with a 1-month history of an asymptomatic, firm, and pinkish-red generalized gingival overgrowth. There was no bone resorption. Incisional biopsy of the gingival tissue was performed, with histopathological examination revealing a diffuse and hypercellular infiltration of monocytoid cells. The patient was referred to a hematologist and underwent a bone marrow biopsy, which led to a conclusive diagnosis of acute myeloid leukemia. The patient was treated with chemotherapy and we observed regression of gingival enlargement after 4 weeks from the initial therapy.

Tuberous Sclerosis Complex with Gingival Enlargement in an Adolescent.

Tuberous sclerosis complex (TSC) is an autosomal dominant, multisystem genetic disorder. It is characterised by formation of benign hamartomas, neurofibromas, and angiofibromas located in different organs. We describe a case of a 13-year boy who complained of gingival enlargement. Clinical examination showed distinctive dermatological signs like hypopigmented macules, shagreen plaques, miliary fibromas, fibrous plaques and multiple angiofibromas. Oral manifestation included localised gingival enlargement. Gingivectomy was performed and the excised tissue was submitted for histopathological examination. The microscopic examination of gingival tissue revealed multiple bundles of collagen fibres with proliferating fibroblast and multiple proliferating blood vessels in the connective tissue. The clinical and histopathological findings were consistent with gingival angiofibromas of TSC. Gingivectomy allowed the patient to have better function and aesthetics. Periodontal examination in conjunction with dermatological examination is important for early diagnosis of TSC.

4PBA strongly attenuates endoplasmic reticulum stress, fibrosis, and mitochondrial apoptosis markers in cyclosporine treated human gingival fibroblasts.

Cyclosporine induces overgrowth of human gingiva. Previously we have shown (i) cyclosporine-inducing ER stress in human gingival fibroblasts (HGF), (ii) increased matrix protein expression, and (iii) interference with mitochondrial pro- and anti-apoptotic factors. This study was undertaken to assess the effects of melatonin (an antioxidant), 4PBA (an ER stress inhibitor), and simvastatin on the expression of ER Stress markers as well as on matrix and mitochondrial markers. HGF incubated with cyclosporine, or without melatonin/4PBA/statin. After 24 hr of incubation, mRNA expression of ER stress markers (GRP78, CHOP, XBP1, and XBPs) and matrix protein markers (like α-SMA, VEGF, TGF-ß, CTGF), and mitochondrial apoptosis markers estimated and compared with housekeeping gene GAPDH. Compared to the control cyclosporine significantly augmented ER Stress and matrix proteins, which decreased significantly with the use of melatonin, 4PBA, and simvastatin. The mitochondrial proapoptotic molecule cyclophilin D, as well as Bcl2 expression also decreased after PBA treatment, paralleling an increase in cytochrome c expression. The effect of 4PBA was much more pronounced than the influence of other two. In conclusion, 4PBA could be a viable therapeutic option for drug-induced gingival overgrowth.

Experimental animal model in a histological study of drug-induced gingival overgrowth.

Gingival overgrowth (GO) is a pathology with important aesthetic and functional implications and with a multifactorial pathogenesis. Incriminated etiological factors include antihypertensive, antiepileptic and immunosuppressant medication. We aimed to evaluate the induction of gingival overgrowth on experimental rats, depending on the drug type, dose and duration. In the research conducted by us, the increase in gingival tissue production occurred gradually, depending on the administered medication and the time elapsed after its start. The study conducted shows that experimentally induced gingival overgrowth of the administered drugs is made possible by altering tissue homeostasis through altering the fibrocyte cell populations involved in the tissular turnover as well as those involved in the inflammatory process. A better understanding of the pathogenesis of this undesirable effect may lead to the development of improved management strategies for preventing it, or reducing it through non-surgical methods.

Local cause of gingival overgrowth. Clinical and histological study.

The overgrowth, depending on its extension, has multiple effects on the stomatognathic apparatus: functional disorders (impaired speech), difficulty in chewing and aesthetic problems but can cause significant psychological problems. We proposed this study, motivated by the relative increased frequency of the gum outgrowth, its multifactorial etiopathogeny, but especially from the point of view of the specialist practitioner, by the problems that this pathology raises not only for the functionality of the stomatognathic apparatus but also for the facial esthetics, and especially for future therapeutic attitudes needed to solve the existing pathology at this level. We conducted a clinical study and a histological one. For the clinical study, we selected 74 patients who experienced different degrees of gingival outgrowing associated with fillings, dental caries, fixed prostheses, mobile prostheses, orthodontic apparatus. Thirty gingival fragments from patients with gingival outgrowing were processed by paraffin-embedding histological technique and stained with Hematoxylin-Eosin. The morphological results obtained provide the necessary support for understanding the possibility of developing a therapeutic strategy to prevent or minimize the gum outgrowth by administering antibiotic and anti-inflammatory medications associated with medications, which shall cause the apoptosis of the fibroblasts.

Biological roles of KGF, CTGF and TGF-ß in cyclosporine-A- and phenytoin- induced gingival overgrowth: A comparative experimental animal study.

OBJECTIVE: To identify the possible biological roles of keratinocyte growth factor (KGF), connective tissue growth factor (CTGF) and transforming growth factor-ß (TGF-ß) in cyclosporine-A (CsA) and phenytoin (PNT)-induced gingival overgrowth (GO) and to correlate them with each other. METHODS: Sixty adult male albino rats were selected and divided into 3 equal groups. Group I rats received no treatment. Group II rats were administrated CsA for 7 weeks. Group III were administrated PNT for the same period. Rats were euthanized at the end of the experiment and routine tissue processing was carried out. The obtained specimens were stained with H&E, KGF, CTGF and TGF-ß antibodies. RESULTS: One-way MANOVA test for KGF, CTGF and TGF-ß revealed an overall significant difference between the different groups (P<0.001). LSD post hoc test for multiple comparisons revealed a significant difference between each two groups. Two-tailed Pearson correlation for group II revealed non-significant weak positive correlations between KGF & CTGF and between CTGF & TGF-ß. Non-significant weak negative correlation was found between KGF & TGF-ß. Meanwhile, group III revealed non-significant weak positive correlation between KGF & TGF-ß and between CTGF & TGF-ß. Significant moderate positive correlation was found between KGF & CTGF. CONCLUSION: The findings of the present study indicated that KGF, CTGF and TGF-ß have biological roles in progression of CsA- and PNT- induced GO. KGF plays a greater role in CsA- induced GO than in PNT- induced GO. Meanwhile, CTGF and TGF-ß play a role in PNT- induced GO greater than in CsA- induced GO.

Using Salivary Nitrite and Nitrate Levels as a Biomarker for Drug-Induced Gingival Overgrowth.

AIM: Drug-induced gingival overgrowth has a multifactorial nature and the pathogenesis is still uncertain. It has been suggested that Nitric Oxide (NO) might play a role in the pathogenesis of drug-induced gingival overgrowth due to the contribution of NO to immune response and matrix degradation. NO levels in biological fluids have been used as a diagnostic biomarker in many diseases. The aim of this study is to determine whether NO levels in plasma, saliva, and gingival crevicular fluid (GCF) can serve as a potential biomarker for the evaluation of drug-induced gingival overgrowth risk. MATERIALS AND METHODS: A total of 104 patients, receiving cyclosporine A (n = 35), phenytoin (n = 25), nifedipine (n = 26), or diltiazem (n = 18) participated in the study. The amount of gingival overgrowth was evaluated with two indices and was given as percentage. Periodontal clinical parameters including plaque index (PI), gingival index (GI), gingival bleeding time index (GBTI), and probing depth (PD) were also assessed. Saliva, GCF, and plasma samples were obtained from each participants. Nitrite and nitrate levels in saliva, GCF, and plasma were analyzed by Griess reagent. RESULTS: Salivary nitrite and nitrate levels in responders were significantly higher than those in non-responders in only phenytoin group (p < 0.05). Nitrite and nitrate levels of gingival crevicular fluid and plasma did not significantly differ between responders and non-responders in all study groups (p > 0.05). Salivary nitrite levels exhibited a significant correlation with PD, GBTI, severity of gingival overgrowth (%GO), and GCF volume (p < 0.05). Additionally, a strong positive correlation was detected between saliva and plasma nitrate levels (p < 0.005). However, both nitrite and nitrate levels in GCF and plasma demonstrated no significant correlation with clinical parameters, GO severity, and GCF volume (p > 0.05). CONCLUSION: Salivary nitrite and nitrate levels could be used as periodontal disease biomarkers in phenytoin induced gingival overgrowth, and that saliva seems to have a better diagnostic potential than GCF and plasma for the evaluation of drug-induced gingival overgrowth risk. However, when all drug groups were considered, saliva nitrite and nitrate levels could not be used as a biomarker for drug-induced gingival overgrowth.

The Smile Esthetic Index (SEI): A method to measure the esthetics of the smile. An intra-rater and inter-rater agreement study.

PURPOSE: To propose a method to measure the esthetics of the smile and to report its validation by means of an intra-rater and inter-rater agreement analysis. MATERIALS AND METHODS: Ten variables were chosen as determinants for the esthetics of a smile: smile line and facial midline, tooth alignment, tooth deformity, tooth dischromy, gingival dischromy, gingival recession, gingival excess, gingival scars and diastema/missing papillae. One examiner consecutively selected seventy smile pictures, which were in the frontal view. Ten examiners, with different levels of clinical experience and specialties, applied the proposed assessment method twice on the selected pictures, independently and blindly. Intraclass correlation coefficient (ICC) and Fleiss' kappa) statistics were performed to analyse the intra-rater and inter-rater agreement. RESULTS: Considering the cumulative assessment of the Smile Esthetic Index (SEI), the ICC value for the inter-rater agreement of the 10 examiners was 0.62 (95% CI: 0.51 to 0.72), representing a substantial agreement. Intra-rater agreement ranged from 0.86 to 0.99. Inter-rater agreement (Fleiss' kappa statistics) calculated for each variable ranged from 0.17 to 0.75. CONCLUSION: The SEI was a reproducible method, to assess the esthetic component of the smile, useful for the diagnostic phase and for setting appropriate treatment plans.

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.

Heterogeneity of collagen secreting cells in gingival fibrosis--an immunohistochemical assessment and a review of the literature.

AIM: In this work, we compared the histological features of the gingival lesions clinically diagnosed as fibrotic overgrowths due to various etiologic factors as well as an immunohistochemical assessment of fibroblasts phenotypic heterogeneity using the specific labeling for vimentin, α-smooth muscle actin (α-SMA) and fibroblast specific protein-1 (FSP1). MATERIALS AND METHODS: Tissue samples were obtained from 12 patients clinically diagnosed with fibrotic gingival overgrowth, divided in four groups. Fragments of gingiva were processed for paraffin embedding. Serial sections were used for routine staining Hematoxylin-Eosin, trichromic Masson and Goldner-Szekely, and for immunohistochemical reactions to label vimentin, α-SMA and FSP1 using for signal amplification several techniques (EnVision, LSAB, ABC). RESULTS: Storage of collagen fibers, increase of fibroblast number and frequent presence of inflammatory infiltrate are histological issues of all fibrotic gingival overgrowth. The incidence of granulation tissue varies but the frequency of its presence point the attention to the involvement in collagen metabolism imbalance. Immunostaining for vimentin showed a difference between its expression in samples from different groups. Except the cases of fibrosis induced by orthodontic devices, cells positive for α-SMA were rare. FSP1-positive fibroblasts were the most frequent in all cases from all the groups selected for this study. CONCLUSIONS: The phenotype of fibroblasts is different in gingival fibrosis in relation to the risk factor, at present the most common being vimentin-positive and FSP1-positive fibroblasts. Myofibroblasts are rare in gingival fibrosis, the most numerous being in local lesions caused by wearing orthodontic devices and in syndromic fibromatosis. Further studies are required to elucidate the manner in which the active fibroblasts are recruited in relation to the etiologic factor of gingival overgrowth.