Loss of TBC1D2B causes a progressive neurological disorder with gingival overgrowth.

Biallelic loss-of-function variants in TBC1D2B have been reported in five subjects with cognitive impairment and seizures with or without gingival overgrowth. TBC1D2B belongs to the family of Tre2-Bub2-Cdc16 (TBC)-domain containing RAB-specific GTPase activating proteins (TBC/RABGAPs). Here, we report five new subjects with biallelic TBC1D2B variants, including two siblings, and delineate the molecular and clinical features in the ten subjects known to date. One of the newly reported subjects was compound heterozygous for the TBC1D2B variants c.2584C>T; p.(Arg862Cys) and c.2758C>T; p.(Arg920*). In subject-derived fibroblasts, TBC1D2B mRNA level was similar to control cells, while the TBC1D2B protein amount was reduced by about half. In one of two siblings with a novel c.360+1G>T splice site variant, TBC1D2B transcript analysis revealed aberrantly spliced mRNAs and a drastically reduced TBC1D2B mRNA level in leukocytes. The molecular spectrum included 12 different TBC1D2B variants: seven nonsense, three frameshifts, one splice site, and one missense variant. Out of ten subjects, three had fibrous dysplasia of the mandible, two of which were diagnosed as cherubism. Most subjects developed gingival overgrowth. Half of the subjects had developmental delay. Seizures occurred in 80% of the subjects. Six subjects showed a progressive disease with mental deterioration. Brain imaging revealed cerebral and/or cerebellar atrophy with or without lateral ventricle dilatation. The TBC1D2B disorder is a progressive neurological disease with gingival overgrowth and abnormal mandible morphology. As TBC1D2B has been shown to positively regulate autophagy, defects in autophagy and the endolysosomal system could be associated with neuronal dysfunction and the neurodegenerative disease in the affected individuals.

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.

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.

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.

NADPH Oxidase 4 Mediates TGFß1-induced CCN2 in Gingival Fibroblasts.

Transforming growth factor ß (TGFß) plays a central role in the pathogenesis of gingival overgrowth (GO). Connective tissue growth factor (CTGF; or CCN2) is induced by TGFß in human gingival fibroblasts (HGFs) and is overexpressed in GO tissues. CCN2 creates an environment favorable for fibrogenesis and is required for the maximal profibrotic effects of TGFß. We previously showed that Src, JNK, and Smad3 mediate TGFß1-induced CCN2 protein expression in HGFs. Moreover, Src is an upstream signaling transducer of JNK and Smad3. Recent studies suggested that NADPH oxidase (NOX)-dependent redox mechanisms are involved in mediating the profibrotic effects of TGFß. In this study, we demonstrated that TGFß1 upregulated NOX4 protein expression and increased reactive oxygen species (ROS) production in HGFs. Genetic or pharmacologic targeting of NOX4 abrogated TGFß1-induced ROS production; Src, JNK, and Smad3 activation; and CCN2 and type I collagen protein expression in HGFs. Our results indicated that NOX4-derived ROS play pivotal roles in activating Src kinase activity leading to the activation of canonical (Smad3) and noncanonical (JNK) cascades that cooperate to attain maximum CCN2 expression. Furthermore, we demonstrated that curcumin significantly inhibited the TGFß1-induced NOX4 protein expression in HGFs. Curcumin potentially qualifies as an agent to control GO by suppressing TGFß1-induced NOX4 expression in HGFs.

Molecular and clinical aspects of drug-induced gingival overgrowth.

Drug-induced gingival overgrowth is a tissue-specific condition and is estimated to affect approximately one million North Americans. Lesions occur principally as side-effects from phenytoin, nifedipine, or ciclosporin therapy in approximately half of the people who take these agents. Due to new indications for these drugs, their use continues to grow. Here, we review the molecular and cellular characteristics of human gingival overgrowth lesions and highlight how they differ considerably as a function of the causative drug. Analyses of molecular signaling pathways in cultured human gingival fibroblasts have provided evidence for their unique aspects compared with fibroblasts from the lung and kidney. These findings provide insights into both the basis for tissue specificity and into possible therapeutic opportunities which are reviewed here. Although ciclosporin-induced gingival overgrowth lesions exhibit principally the presence of inflammation and little fibrosis, nifedipine- and especially phenytoin-induced lesions are highly fibrotic. The increased expression of markers of gingival fibrosis, particularly CCN2 [also known as connective tissue growth factor (CTGF)], markers of epithelial to mesenchymal transition, and more recently periostin and members of the lysyl oxidase family of enzymes have been documented in phenytoin or nifedipine lesions. Some oral fibrotic conditions such as leukoplakia and oral submucous fibrosis, after subsequent additional genetic damage, can develop into oral cancer. Since many pathways are shared, the study of gingival fibrosis and comparisons with characteristics and molecular drivers of oral cancer would likely enhance understandings and functional roles of molecular drivers of these oral pathologies.

Altered oxidative status and integrin expression in cyclosporine A-treated oral epithelial cells.

BACKGROUND AND OBJECTIVE: Cyclosporine A (CsA) is an immunosuppressive agent administered to transplant patients. A well-known reported oral side effect of CsA consumption is gingival overgrowth (GO). Changes in the expression of integrins occurring in the gingiva following CsA treatment have been reported but these reports are mainly concerned with the connective tissue of the gingiva. In this study we targeted the alterations in the oral epithelium using KB cells, an oral epithelial cell line. METHODS: Cultured oral epithelial cells were treated with increasing concentrations of CsA (0.1, 1 and 10 µg/mL) and the molecular changes involving antioxidant enzymes [glutathione peroxidase (GPx) and glutathione reductase (GR)] and the level of reactive oxygen species (ROS) were measured. Quantitative real-time PCR was used to assess the expression of selected integrins (α2, α5 and ß1). RESULTS: At CsA concentration above 0.1 µg/mL GPx demonstrated an increase in activity while GR activity and the level of reduced glutathione were diminished (p < 0.05). α5 and ß1 integrin were downregulated at all treatment concentrations of CsA while α2 integrin presented this effect at concentrations above 1 µg/mL (p < 0.05). CONCLUSION: The results suggest a possible role for oxidative stress and the altered expression of integrins in the pathology of CsA-induced gingival overgrowth.

Cyclosporine A enhances gingival ß-catenin stability via Wnt signaling.

BACKGROUND: Cyclosporine A (CsA) increases ß-catenin messenger RNA (mRNA) and protein expression. The present study demonstrates that Wnt/ß-catenin signaling inhibits ß-catenin degradation in the gingiva. METHODS: Forty 5-week-old male Sprague-Dawley rats were assigned to two study groups after healing from right maxillary molar extractions. The rats in the experimental group were fed 30 mg/kg CsA daily for 4 weeks, whereas the control rats were fed mineral oil. At the end of the study, all rats were sacrificed, and the gingivae were obtained. The gingival morphology after CsA treatment was evaluated by histology, and the genes related to Wnt/ß-catenin signaling were initially screened by microarray. Polymerase chain reaction, Western blotting, and immunohistochemistry were used to examine the mRNA and protein expression of proliferating cell nuclear antigen, cyclin D1, E-cadherin, ß-catenin, Dvl-1, glycogen synthase kinase-3ß, axin-1, and adenomatous polyposis coli (APC). Phosphoserine and ubiquitinylated ß-catenin were detected after immunoprecipitation. RESULTS: In rats treated with CsA, overgrowth of gingivae was observed, and altered expression of genes related to Wnt/ß-catenin signaling was detected by the microarray. The gingival mRNA and protein expression profiles for genes associated with Wnt/ß-catenin signaling further confirmed the effect of CsA: ß-catenin and Dvl-1 expression increased, but APC and axin-1 expression decreased. Western blotting and immunohistochemistry showed decreases in ß-catenin serine phosphorylation (33/37) and ubiquitinylation in the gingivae of CsA-treated rats. CONCLUSION: CsA-enhanced gingival ß-catenin stability may be involved in gene upregulation or ß-catenin degradation via the Wnt/ß-catenin pathway.

Nifedipine induces periostin expression in gingival fibroblasts through TGF-beta.

Gingival enlargement is a fibrotic condition that can arise from systemic administration of the dihydropyridine calcium channel blocker nifedipine. Periostin, a transforming growth factor-beta (TGF-ß)-inducible matricellular protein, has been associated with fibrosis in numerous tissues, but its expression has never been examined in nifedipine-influenced gingival enlargement (NIGE). The objective of this study was to assess if periostin up-regulation is associated with NIGE and whether nifedipine induces periostin expression in gingival fibroblasts. In NIGE tissue (n = 6), periostin is overexpressed in the gingival connective tissue compared with healthy control tissue (n = 6). The transcription factor p-SMAD2/3, which is associated with canonical TGF-ß signaling, localizes to the nuclei in both HGFs and oral epithelial cells in NIGE tissues, but not in control healthy tissue. In vitro culture of HGFs with 30 and 100 ng/mL of nifedipine significantly increased periostin mRNA and protein levels, which correlated with increased levels of active TGF-ß and increased phosphorylation and nuclear localization of SMAD3. Blocking of canonical TGF-ß signaling through inhibition of the TGF-ß receptor I with SB431542 significantly reduced nifedipine-induced SMAD3 phosphorylation and periostin expression. Our results demonstrate that nifedipine up-regulates periostin in HGFs in a TGF-ß-dependent manner.

Serum cyclophilin A concentrations in renal transplant recipients receiving cyclosporine A: clinical implications for gingival overgrowth.

OBJECTIVE: The aim of this study was to investigate the clinical factors in relation to the cyclosporine A (CsA) induced gingival overgrowth (GO). STUDY DESIGN: Seventy-three participants were assigned as GO+ and GO-. Factors including demographic, pharmacological, gingival variables and the serum cyclophilin A (CyPA) concentration were analyzed. RESULTS: The occurrence of GO was 39.72%. Papillary bleeding index (PBI) had a significantly higher risk of GO than plaque index (PI), the ratio of CsA to CyPA, and serum CyPA concentration (odds ratio = 364.323, 25.791, 1.002, 0.096, respectively). The severity of GO correlated with PI, the ratio of CsA to CyPA, PBI, serum concentrations of CsA and CyPA (r = 0.366, 0.355, 0.344, 0.305, and -0.232, respectively). CONCLUSIONS: Since a cross-sectional study is not able to explain whether plaque and inflammation are the cause or consequence of GO, the ratio of CsA to CyPA may be a valuable marker for predicting GO.

Immunolocalization of Bcl-2 oncoprotein in amlodipine-induced gingival overgrowth.

BACKGROUND: Drug-induced gingival overgrowth (DIGO) is one of the unwanted side effects of amlodipine therapy, but the pathogenesis still remains unclear. Apoptosis, which plays a ubiquitous role in tissue homeostasis, including gingiva, may be involved in the development of gingival enlargement. AIMS AND OBJECTIVES: (i) To study the distribution of Bcl-2 in healthy and overgrown gingival tissues. (ii) To compare and correlate the Bcl-2 expression in gingival samples from subjects on amlodipine therapy to the findings in healthy controls. MATERIALS AND METHODS: A total of 25 subjects were recruited for the study - 15 hypertensive patients and 10 systemically healthy subjects. Both the groups were analyzed for Bcl-2 expression using immunohistochemistry. RESULTS: Few of the control specimens showed weak positivity to Bcl-2 antibody, with the distribution limited to the basal cell layers alone, whereas 10 hyperplastic specimens expressed Bcl-2 and, unlike the control group, the distribution pattern was seen in both basal and suprabasal layers. CONCLUSION: The results indicate that the pathogenesis of amlodipine-induced gingival overgrowth might involve inhibition of apoptosis, especially with morphogenesis of hyperplastic gingival epithelia.

Unusual presentation of localized gingival enlargement associated with a slow-growing odontogenic myxoma.

Unusual presentation of localized gingival enlargement associated with a subjacent tumoural pathology is reported. The patient was a 55-year-old black male, whose chief complaint was a progressive gingival overgrowth for more than ten years, in the buccal area of the anterior left mandible. According to the clinical features and the radiological diagnosis of odontogenic keratocyst, a conservative surgery with enucleation and curettage was performed. Tissue submitted for histopathological analysis rendered the diagnosis of odontogenic myxoma. After 12-month of follow-up, no evidence of recurrence was found. Clinicians should be cautious when facing any gingival enlargement to avoid diagnostic pitfalls and to indicate the appropriate treatment.

Arthropathy, osteolysis, keloids, relapsing conjunctival pannus and gingival overgrowth: a variant of polyfibromatosis?

Polyfibromatosis is a rare fibrosing condition characterized by fibromatosis in different body areas and by keloid formation, and which can be associated with arthropathy and osteolysis. Familial occurrence has been described, but the cause remains unknown. Here, we describe a patient with characteristics of polyfibromatosis with arthropathy who had in addition severe conjunctival fibrosis, distinctive face, gingival overgrowth, and pigmented keloids. We discuss the resemblances and differences with polyfibromatosis and descriptions of other, similar patients. We conclude that at present it remains uncertain whether the patient has a variant of polyfibromatosis or a separate entity.

Gene and protein localisation of tumour necrosis factor (TNF)-α converting enzyme in gingival tissues from periodontitis patients with drug-induced gingival overgrowth.

OBJECTIVE: It is known that tumour necrosis factor (TNF)-α converting enzyme (TACE) plays a crucial role in fibrotic inflammatory diseases, and is specifically inhibited by tissue inhibitor of metalloproteinase (TIMP)-3. Fibrotic drug-induced gingival overgrowth (GO) is often combined with periodontitis. However, neither TACE nor TIMP-3 has been thoroughly examined in periodontal tissues to date. The aim of the present study was to analyse mRNA expression of TACE and TIMP-3, and protein localisation of TACE in gingival tissues removed from drug-(calcium-channel blocker) induced GO and periodontitis. METHODS: A total of 30 gingival tissue samples were taken from 15 GO and 15 periodontitis patients. The mRNA expression levels were analysed by quantitative reverse transcription polymerase chain-reaction (qRT-PCR) and the protein localisation was investigated by immunohistochemistry. Statistical analysis was performed using the Mann-Whitney U-test. RESULTS: TACE and TIMP-3 mRNA levels were significantly higher in GO compared to the periodontitis groups, as revealed by qRT-PCR (p<0.05). TACE-producing cells were immunohistochemically detected among monocytes/macrophages, plasma cells and some epithelial cells. TACE immunoreactivity was shown to be more intense in GO than in periodontitis-gingival tissue. CONCLUSIONS: We have demonstrated TACE expression in cells such as macrophages, plasma cells and epithelial cells, and its predominant expression in GO tissues. This data suggests that TACE expression in GO-gingiva could be involved in the pathogenesis of disease.

Stromal myofibroblasts in focal reactive overgrowths of the gingiva

Focal reactive overgrowths are among the most common oral mucosal lesions. The gingiva is a significant site affected by these lesions, when triggered by chronic inflammation in response to microorganisms in dental plaque. Myofibroblasts are differentiated fibroblasts that actively participate in diseases characterized by tissue fibrosis. The objective of this study was to evaluate the presence of stromal myofibroblasts in the main focal reactive overgrowths of the gingiva: focal fibrous hyperplasia (FFH), peripheral ossifying fibroma (POF), pyogenic granuloma (PG), and peripheral giant cell granuloma (PGCG). A total of 10 FFHs, 10 POFs, 10 PGs, and 10 PGCGs from archival specimens were evaluated. Samples of gingival mucosa were used as negative controls for stromal myofibroblasts. Oral squamous cell carcinoma samples, in which stromal myofibroblasts have been previously detected, were used as positive controls. Myofibroblasts were identified by immunohistochemical detection of alpha smooth muscle actin (α-sma). Myofibroblast immunostaining was qualitatively classified as negative, scanty, or dense. Differences in the presence of myofibroblasts among FFH, POF, PG, and PGCG were analyzed using the Kruskal-Wallis test. Stromal myofibroblasts were not detected in FFH, POF, PG, or PGCG. Consequently, no differences were observed in the presence of myofibroblasts among FFH, POF, PG, or PGCG (p > 0.05). In conclusion, stromal myofibroblasts were not detected in the focal reactive overgrowths of the gingiva that were evaluated, suggesting that these cells do not play a significant role in their pathogenesis.

Stromal myofibroblasts in focal reactive overgrowths of the gingiva.

Focal reactive overgrowths are among the most common oral mucosal lesions. The gingiva is a significant site affected by these lesions, when triggered by chronic inflammation in response to microorganisms in dental plaque. Myofibroblasts are differentiated fibroblasts that actively participate in diseases characterized by tissue fibrosis. The objective of this study was to evaluate the presence of stromal myofibroblasts in the main focal reactive overgrowths of the gingiva: focal fibrous hyperplasia (FFH), peripheral ossifying fibroma (POF), pyogenic granuloma (PG), and peripheral giant cell granuloma (PGCG). A total of 10 FFHs, 10 POFs, 10 PGs, and 10 PGCGs from archival specimens were evaluated. Samples of gingival mucosa were used as negative controls for stromal myofibroblasts. Oral squamous cell carcinoma samples, in which stromal myofibroblasts have been previously detected, were used as positive controls. Myofibroblasts were identified by immunohistochemical detection of alpha smooth muscle actin (α-sma). Myofibroblast immunostaining was qualitatively classified as negative, scanty, or dense. Differences in the presence of myofibroblasts among FFH, POF, PG, and PGCG were analyzed using the Kruskal-Wallis test. Stromal myofibroblasts were not detected in FFH, POF, PG, or PGCG. Consequently, no differences were observed in the presence of myofibroblasts among FFH, POF, PG, or PGCG (p > 0.05). In conclusion, stromal myofibroblasts were not detected in the focal reactive overgrowths of the gingiva that were evaluated, suggesting that these cells do not play a significant role in their pathogenesis.