Abstract Regenerative approaches using mesenchymal stem cells (MSCs) have been evaluated to promote the complete formation of all missing periodontal tissues, e.g., new cementum, bone, and functional periodontal ligaments. MSCs derived from bone marrow have been applied to bone and periodontal defects in several forms, including bone marrow aspirate concentrate (BMAC) and cultured and isolated bone marrow mesenchymal stem cells (BM-MSCs). This study aimed to evaluate the periodontal regeneration capacity of BMAC and cultured BM-MSCs in the wound healing of fenestration defects in rats. Methodology: BM-MSCs were obtained after bone marrow aspiration of the isogenic iliac crests of rats, followed by cultivation and isolation. Autogenous BMAC was collected and centrifuged immediately before surgery. In 36 rats, fenestration defects were created and treated with suspended BM-MSCs, BMAC or left to spontaneously heal (control) (N=6). Their regenerative potential was assessed by microcomputed tomography (µCT) and histomorphometry, as well as their cell phenotype and functionality by the Luminex assay at 15 and 30 postoperative days. Results: BMAC achieved higher bone volume in 30 days than spontaneous healing (p<0.0001) by enhancing osteoblastic lineage commitment maturation, with higher levels of osteopontin (p=0.0013). Defects filled with cultured BM-MSCs achieved higher mature bone formation in early stages than spontaneous healing and BMAC (p=0.0241 and p=0.0143, respectively). Moreover, significantly more cementum-like tissue formation (p<0.0001) was observed with new insertion of fibers in specimens treated with BM-MSCs within 30 days. Conclusion: Both forms of cell transport, BMAC and BM-MSCs, promoted bone formation. However, early bone formation and maturation were achieved when cultured BM-MSCs were used. Likewise, only cultured BM-MSCs were capable of achieving complete periodontal regeneration with inserted fibers in the new cementum-like tissue.

Resumen Introducción: La hipertrofia gingival (HG) es el aumento del volumen de la encía asociado a ciertas enfermedades sistémicas, hereditarias (idiopático), ingesta de algunos medicamentos o a factores locales como el tratamiento ortodóntico, capaz de provocar cambios histológicos en el tejido conectivo gingival. Objetivo: Describir las características histológicas e identificar el colágeno tipo I y tipo III en tejidos gingivales de sujetos con hipertrofia gingival portadores de ortodoncia. Materiales y método: Se diseñó un estudio de casos y controles que incluyó el análisis de biopsias de tejido gingival de 12 pacientes sometidos a cirugías periodontales. La muestra se dividió en dos grupos: individuos sanos (control; n= 6) y pacientes con HG portadores de ortodoncia (pacientes; n= 6). Las muestras fueron procesadas e incluidas en parafina. Las tinciones Masson-Goldner y rojo sirius/verde rápido fueron empleadas. El colágeno tipo I y tipo III fueron identificados mediante inmunohistoquímica con anticuerpos monoclonales. Resultado: En los pacientes con HG portadores de ortodoncia se observó un epitelio hiperplásico y tejido conectivo denso con abundantes fibras de colágeno distribuidos aleatoriamente. La inmunodetención de colágeno tipo I indicó la presencia de abundantes fibras desorganizadas y el colágeno tipo III fue inmunolocalizado subyacente a la membrana basal, vasos sanguíneos y toda la extensión del tejido conectivo de los pacientes con HG con tratamiento ortodóntico. Conclusión: La acumulación de fibras de colágeno, particularmente del colágeno tipo I y tipo III, son hallazgos histológicos que caracterizan la HG en pacientes portadores de ortodoncia. Futuros estudios son necesarios para dilucidar el fenotipo de los fibroblastos gingivales y la probable pérdida homeostática entre la producción y degradación de colágeno en esta patología.

Abstract Introduction: Gingival hypertrophy (GH) is the increase in the volume of the gingiva associated with certain systemic, hereditary (idiopathic) diseases, the intake of some medications or local factors such as orthodontic treatment, capable of causing histological changes in the gingival connective tissue. Objective: To describe the histological characteristics and identify type I and type III collagen in gingival tissues of subjects with gingival hypertrophy wearing orthodontics. Method: A case-control study was designed that included the analysis of gingival tissue biopsies from 12 patients submitted to periodontal surgeries. The sample was divided into two groups: healthy individuals (Control; n= 6) and patients with GH wearing orthodontics (Patients; n= 6). The samples were processed and embedded in paraffin. Masson-goldner and sirius red/fast green stains were used. Type I and type III collagen were identified by immunohistochemistry with monoclonal antibodies. Result: A hyperplastic epithelium and dense connective tissue with abundant randomly distributed collagen fibers were observed in patients with orthodontic GH. Immunodetention of type I collagen indicated the presence of abundant disorganized fibers and type III collagen was inmunolocalized underlying the basement membrane, blood vessels and the entire extension of the connective tissue of patients with GH orthodontic. Conclusion: The accumulation of collagen fibers, particularly type I and type III collagen, are histological findings that characterize GH in orthodontic wearers. Future studies are necessary to elucidate the phenotype of gingival fibroblasts and the probable homeostatic loss between collagen production and degradation in this pathology.

ABSTRACT: The objective of the study was to compare, through a systematic review, the clinical results of periodontal / peri-implant plastic surgery (CP) procedures with autogenous soft tissue graft (ITB) obtained from the lateral palate area (ALP) versus the tuberosity area (AT). We conducted an electronic search of clinical trials in the Medline/Pubmed, Cochrane database and the journals of Periodontics and Implants with the greatest impact according to the Web of Science, to find articles published until April 2020. The risk of bias of the articles added was assessed according to the Cochrane Manual Version 5.1.0 for randomized clinical trials and the Newcastle-Ottawa scale for controlled clinical trials. From the initial sample of 930 articles, four clinical trials were included (three randomized) in the present study, where a total of 87 PC were performed around dental pieces and implants, of which 42 surgeries were performed with ITB of the ALP and 45 surgeries with ITB of the AT, the results were evaluated from the 8 weeks to 12 months. No statistically significant differences were found in the clinical results between the two groups, the gingival phenotype in the receiving area was improved for the group that obtained the ITB of the AT and the level of pain at the donor site was lower in the first two weeks than the ALP donor site. The studies showed a lowrisk of bias on average. Both soft tissue graft donor areas provide similar clinical results, grafting the tuberosity area improves the gingival phenotype of the recipient area and reduces post-operative pain of the donor site in the first few weeks.

RESUMEN: Comparar mediante una revisión sistemática los resultados clínicos de los procedimientos de cirugía plástica periodontal/periimplantar (CP) con injerto de tejido blando autógeno (ITB) obtenido del área lateral del paladar (ALP) versus del área de la tuberosidad (AT). Se realizó una búsqueda electrónica de ensayos clínicos en la base de datos Medline/Pubmed, Cochrane y las revistas de Periodoncia e Implantes de mayor impacto según la Web of Science, para hallar artículos publicados hasta abril del 2020. Se valoró el riesgo de sesgo de los artículos añadidos según el manual Cochrane Versión 5.1.0 para ensayos clínicos aleatorizados y la escala Newcastle-Ottawa para ensayos clínicos controlados. De una muestra inicial de 930 artículos, cuatro ensayos clínicos (tres aleatorizados) fueron incluidos en el presente estudio, donde se realizaron un total de 87 CP alrededor de piezas e implantes dentales, de las cuales 42 cirugías fueron realizadas con ITB del ALP y 45 cirugías con ITB del AT, se evaluó los resultados desde las 8 semanas hasta los 12 meses. No se hallaron diferencias estadísticamente significativas en los resultados clínicos entre ambos grupos, se mejoró el fenotipo gingival en la zona receptora para el grupo que obtuvo el ITB del AT y el nivel del dolor del sitio donador del AT fue menor en las dos primeras semanas que el sitio donante del ALP. Los estudios incluidos manifestaron un bajo riesgo de sesgo en promedio. Ambas áreas donantes de injerto de tejido blando proporcionan resultados clínicos similares, el injerto del área de la tuberosidad mejora el fenotipo gingival de la zona receptora y reduce el dolor post operatorio en las primeras semanas del sitio donador.

Abstract The relationship between periodontitis and the pathogenesis of other inflammatory diseases, such as diabetes, rheumatoid arthritis and obesity has been an important topic of study in recent decades. The Th17 pathway plays a significant role in how local inflammation can influence systemic inflammation in the absence of systemic pathology. Objective: To determine Th17 biased-cells in systemically healthy patients in the presence of generalized chronic periodontitis. Methodology: A total of 28 patients were recruited without systemic inflammatory pathology, which was determined by clinical history, the Health Assessment Questionnaire (HAQ) and rheumatoid factor detection. Of these patients, 13 were diagnosed as healthy/gingivitis (H/G) and 15 as generalized chronic periodontitis (GCP). Th17 (CD4+CD161+) cells and Th17IL23R+ (CD4+CD161+IL-23R+) cells were quantified by flow cytometry, based on the total cells and on the lymphocyte region, termed the “enriched population” (50,000 events for each). Results: The percentages of Th17 cells of the H/G and periodontitis groups were similar on total cells and enriched population (19 vs 21.8; p=4.134 and 19.6 vs 21.8; p=0.55). However, Th17IL23R+ cells differ significantly between periodontally healthy patients and generalized chronic periodontitis patients in both total cell (0.22% vs 0.65%; p=0.0004) and enriched populations (0.2% vs 0.75%; p=0.0266). Conclusions: GCP patients (otherwise systemically healthy) were characterized by increased Th17-proinflammatory cell phenotype positive for the IL-23 receptor in peripheral blood. The proportion of Th17 cells that are negative for the IL-23 receptor in the peripheral blood of systemically healthy patients seemed to be unaffected by the presence or absence of chronic periodontitis.

Abstract Heterogeneous cell populations of osteo/cementoblastic (O/C) or fibroblastic phenotypes constitute the periodontal dental ligament (PDL). A better understanding of these PDL cell subpopulations is essential to propose regenerative approaches based on a sound biological rationale. Objective Our study aimed to clarify the differential transcriptome profile of PDL cells poised to differentiate into the O/C cell lineage. Methodology To characterize periodontal-derived cells with distinct differentiation capacities, single-cell-derived clones were isolated from adult human PDL progenitor cells and their potential to differentiate into osteo/cementoblastic (O/C) phenotype (C-O clones) or fibroblastic phenotype (C-F clones) was assessed in vitro. The transcriptome profile of the clonal cell lines in standard medium cultivation was evaluated using next-generation sequencing technology (RNA-seq). Over 230 differentially expressed genes (DEG) were identified, in which C-O clones showed a higher number of upregulated genes (193) and 42 downregulated genes. Results The upregulated genes were associated with the Cadherin and Wnt signaling pathways as well as annotated biological processes, including “anatomical structure development” and “cell adhesion.” Both transcriptome and RT-qPCR showed up-regulation of WNT2, WNT16, and WIF1 in C-O clones. Conclusions This comprehensive transcriptomic assessment of human PDL progenitor cells revealed that expression of transcripts related to the biological process “anatomical structure development,” Cadherin signaling, and Wnt signaling can identify PDL cells with a higher potential to commit to the O/C phenotype. A better understanding of these pathways and their function in O/C differentiation will help to improve protocols for periodontal regenerative therapies.

Resumo Introdução A determinação do fenótipo gengival possibilita compreender melhor as variações e diferenças clínicas intra e interindividuais dos tecidos periodontais saudáveis. Objetivo O objetivo deste estudo foi determinar os perfis do fenótipo gengival e compará-los em diferentes regiões da cavidade oral, levando em consideração parâmetros clínicos relacionados aos tecidos moles circunjacentes nos dentes anteriores superiores e inferiores. Material e método Noventa e um pacientes com saúde periodontal foram examinados e os parâmetros clínicos profundidade de sondagem (PS), largura de mucosa ceratinizada (MC), espessura gengival em ambos incisivos centrais superiores (EG) e fenótipo gengival (FG) foram coletados nos dentes anteriores superiores e inferiores. Os dados foram analisados estatisticamente pelos testes t-Student pareado e independente, Correlação de Pearson e Qui-quadrado, com um nível de significância de 5%. Resultado O fenótipo gengival espesso predominou nos dentes anteriores superiores (60,5%), enquanto o fenótipo fino foi mais prevalente nos dentes anteriores inferiores (84,6%). Diferenças estatisticamente significativas foram encontradas para os parâmetros largura de mucosa ceratinizada e espessura gengival em relação aos fenótipos gengivais superiores e inferiores (p<0,05). Não houve diferença estatística entre profundidade de sondagem e o fenótipo gengival nos dentes superiores e inferiores. Conclusão Concluiu-se que o fenótipo gengival espesso é mais frequente nos dentes anteriores superiores e que o fenótipo fino é mais comum nos dentes anteriores inferiores, sendo mais frequente em indivíduos do sexo masculino. Os parâmetros largura de mucosa ceratinizada e espessura gengival mostraram-se adequados à determinação do fenótipo gengival.

Abstract Introduction Gingival phenotype determination enables a better understanding of intra and interindividual clinical variations in healthy periodontal tissues. Objective The aim of this study was to determine gingival phenotype profiles and compare these in different regions of the oral cavity, considering clinical parameters related to the surrounding soft tissue in the upper and lower front teeth. Material and method Ninety-one periodontally-healthy patients were examined and clinical parameters such as probing depth (PD), keratinized tissue width (KW), gingival thickness at both maxillary central incisors (GT) and gingival phenotype (GP) were determined for the upper and lower front teeth. Data were statistically analyzed by paired and independent t-Student tests, Pearson Correlation and the Chi-square test, using a significance level of 5%. Result The thick gingival phenotype predominated in the upper anterior teeth (60.5%), while the thin phenotype was more prevalent in the lower anterior teeth (84.6%). Statistically significant differences were found for keratinized tissue and gingival thickness parameters, in relation to the upper and lower gingival phenotypes (p<0.05). There were no statistical significances for probing depth and gingival phenotype in the upper and lower teeth. Conclusion It was concluded that the thick phenotype is more frequent in the upper anterior teeth and that the thin phenotype is more common in the lower anterior teeth, and more frequent in males. The keratinized tissue and gingival thickness parameters proved to be suitable for the determination of gingival phenotype.

Abstract Periodontitis develops as a result of a continuous interaction between host cells and subgingival pathogenic bacteria. The periodontium has a limited capacity for regeneration, probably due to changes in periodontal ligament stem cells (PDLSCs) phenotype. The aim of this study was to evaluate the effects of lipopolysaccharides from Porphyromonas gingivalis (PgLPS) on mesenchymal phenotype and osteoblast/cementoblast (O/C) potential of PDLSCs. PDLSCs were assessed for Toll-like receptor 2 (TLR2) expression by immunostaining technique. After, cells were exposed to PgLPS, and the following assays were carried out: (i) cell metabolic activity using MTS; (ii) gene expression for IL-1β, TNF-α and OCT-4 by real-time polymerase chain reaction (RT-qPCR); (iii) flow cytometry for STRO-1 and CD105, and (iv) osteogenic differentiation. PDLSCs were positive for TLR2. PgLPS promoted cell proliferation, produced IL-1β and TNF-α, and did not affect the expression of stem cell markers, STRO-1, CD105 and OCT-4. Under osteogenic condition, PDLSCs exposed to PgLPS showed a similar potential to differentiate toward osteoblast/cementoblast phenotype compared to control group as revealed by mineralized matrix deposition and levels of transcripts for RUNX2, ALP and OCN. These results provide evidence that PgLPS induces pro-inflammatory cytokines, but does not change the mesenchymal phenotype and osteoblast/cementoblast differentiation potential of PDLSCs.

Resumo Apesar do alto índice de sucesso em implantodontia, falhas tem aumentado drasticamente, estando associadas ao desenvolvimento de peri-implantite. A perda óssea peri-implantar é influenciada por múltiplos fatores, incluindo causas genéticas e ambientais. As BMPs (proteínas ósseas morfogenéticas) são fatores de crescimento indutores da formação óssea. Os FGFs (fatores de crescimento dos fibroblastos) e seus receptores (FGFRs) desenvolvem importante função na proliferação, diferenciação e migração celular. A relação BMP/FGF é responsável pela regeneração e perda óssea. O objetivo deste estudo foi estudar a possível correlação entre os genes BMP4, FGF3, FGF10 e FGFR1 e a perda óssea peri-implantar. Duzentos e quinze voluntários, com 754 implantes, foram submetidos ao exame oral e divididos em grupo saúde (n=129) e peri-implantite (n=86). Treze polimorfismos nos genes BMP4, FGF3, FGF10 e FGFR1 foram analisados individualmente e como haplótipos. O teste do qui-quadrado correlacionou as frequências dos genótipos, alelos e haplótipos. Valores de p<0,05 foram considerados estatisticamente significantes. Voluntários com peri-implantite mostraram alta incidência de edentulismo total (p<0,0001) e biotipo periodontal fino (p<0,04). Sangramento espontâneo, placa e mobilidade do implante foram altamente incidentes no grupo peri-implantite (p<0,0001). O genótipo polimórfico TT para BMP4 rs2761884 foi associado com saúde peri-implantar (p=0,01). FGF3 rs4631909 (genótipos TT+CT) mostraram associação com o grupo controle (p=0,04). A frequência do alelo C para FGF3 rs4631909 mostrou uma tendência de associação com peri-implantite (p=0,08). Os haplótipos FGF10 CCTG (p=0,03), BMP4 GAAA (p=0,05) e GGGA (p=0,02) foram associados com peri-implantite (p=0,03). Sendo assim, conclui-se que os haplótipos BMP4 e FGF10 estão associados com peri-implantite.

Abstract Despite the success of osseointegrated implants, failures have increased significantly, associated with development of peri-implantitis. Multiple factors influence the peri-implant bone loss, including environmental and genetic causes. BMPs (Bone morphogenetic proteins) are growth factors that induce bone formation. FGF (fibroblast growth factors) and their receptors (FGFRs) play important roles by controlling the levels of cell proliferation, differentiation and migration. BMP/FGF relationship is responsible for promoting bone regeneration and bone loss. The aim of this study was to analyze the correlation between BMP4, FGF3, FGF10 and FGFR1 genes and peri-implant bone loss. Two hundred and fifteen volunteers, with 754 dental implants, were submitted to oral examination and divided in healthy group (n=129) and peri-implantitis group (n=86). Thirteen polymorphisms in BMP4, FGF3, FGF10 and FGFR1 genes were analyzed individually and in haplotype. The chi-square test correlated genotypes, allelic and haplotype frequencies. Values of p<0.05 were considered significant. Volunteers with peri-implantitis demonstrated high incidence of total edentulism (p<0.0001) and thin peri-implant phenotype (p<0.04). Higher incidence of spontaneous bleeding, plaque and implant mobility was observed in peri-implantitis group (p<0.0001 for all). The TT polymorphic genotype for BMP4 rs2761884 was associated with healthy peri-implant (p=0.01). FGF3 rs4631909 (TT+CT genotype) also showed association with the control group (p=0.04). The frequency of C allele for FGF3 rs4631909 showed a tendency for association with peri-implantitis (p=0.08). FGF10 CCTG (p=0.03), BMP4 GAAA (p=0.05) and GGGA (p=0.02) haplotypes were associated with peri-implantitis (p=0.03). Therefore, it may be concluded that BMP4 and FGF10 haplotypes are associated with peri-implantitis.

Objective : To investigate the influence of a three-dimensional cell culture model on the expression of osteoblastic phenotype in human periodontal ligament fibroblast (hPDLF) cultures.Material and Methods : hPDLF were seeded on bi-dimensional (2D) and three-dimensional (3D) collagen type I (experimental groups) and and on a plastic coverslip (control) for up to 14 days. Cell viability and alkaline phosphatase (ALP) activity were performed. Also, cell morphology and immunolabeling for alkaline phosphatase (ALP) and osteopontin (OPN) were assessed by epifluorescence and confocal microscopy. The expression of osteogenic markers, including alkaline phosphatase, osteopontin, osteocalcin (OC), collagen I (COL I) and runt-related transcription factor 2 (RUNX2), were analyzed using real-time polymerase chain reaction (RT-PCR). Mineralized bone-like nodule formation was visualized by microscopy and calcium content was assessed quantitatively by alizarin red assay.Results : Experimental cultures produced an increase in cell proliferation. Immunolabeling for OPN and ALP in hPDLF were increased and ALP activity was inhibited by three-dimensional conditions. OPN and RUNX2 gene expression was significantly higher on 3D culture when compared with control surface. Moreover, ALP and COL I gene expression were significantly higher in three-dimensional collagen than in 2D cultures at 7 days. However, at 14 days, 3D cultures exhibited ALP and COL I gene expression significantly lower than the control, and the COL I gene expression was also significantly lower in 3D than in 2D cultures. Significant calcium mineralization was detected and quantified by alizarin red assay, and calcified nodule formation was not affected by tridimensionality.Conclusion : This study suggests that the 3D cultures are able to support hPDLF proliferation and favor the differentiation and mineralized matrix formation, which may be a potential periodontal regenerative therapy.

O linfoma de células natural killers (NK)/T extranodal é um tumor maligno agressivo com características clinicopatológicas distintas, caracterizadas por invasão e destruição vasculares, necrose proeminente, fenótipo linfocítico citotóxico e uma forte associação com o vírus Epstein-Barr. Relatamos aqui um caso de linfoma de células NK/T nasal extranodal, envolvendo o seio maxilar, assoalho de órbita, e interessantemente estendendo-se para a cavidade oral através do osso alveolar e mucosa vestibular, preservando o palato, levando a um diagnóstico inicial equivocado de doença periodontal agressiva. Ainda, nós investigamos pela primeira vez a expressão imunoistoquímica das proteínas Fatty acid sinthase (FASN) e glucose transporter 1 (GLUT-1) nesta neoplasia. FASN revelou uma forte expressão citoplasmática nas células neoplásicas, enquanto GLUT-1 e CD44 foram negativas. Estes achados sugerem que a expressão de FASN e a perda de CD44 podem estar envolvidas na patogênese do linfoma de células NK/T nasal extranodal, e que GLUT-1 não deve participar da adaptação das células tumorais ao ambiente de hipóxia. Estudos adicionais com séries maiores são necessários para confirmar nossos resultados iniciais.

Extranodal natural killer (NK)/T-cell lymphoma is an aggressive malignant tumor with distinctive clinicopathological features, characterized by vascular invasion and destruction, prominent necrosis, cytotoxic lymphocyte phenotype and a strong association with Epstein-Barr virus. Here is reported an extranodal nasal NK/T-cell lymphoma case, involving the maxillary sinus, floor of the orbit, and interestingly extending to the oral cavity through the alveolar bone and buccal mucosa, preserving the palate, leading to a primary misdiagnosis of aggressive periodontal disease. Moreover, this work investigated for the first time the immunohistochemical expression of fatty acid synthase (FASN) and glucose transporter 1 (GLUT-1) proteins in this neoplasia. FASN showed strong cytoplasmatic expression in the neoplastic cells, whereas GLUT-1 and CD44 were negative. These findings suggest that the expression of FASN and the loss of CD44 might be involved in the pathogenesis of the extranodal nasal NK/T-cell lymphoma, and that GLUT-1 may not participate in the survival adaptation of the tumor cells to the hypoxic environment. Further studies with larger series are required to confirm these initial results.

Os hábitos tabágicos constituem um factor de risco para patologias crónicas que envolvem o tecido ósseo como a osteoporose e a perda óssea alveolar associada à doença periodontal. O processo de formação óssea envolve a diferenciação de células osteoprogenitoras em osteoblastos e a formação de uma matrix colagenosa mineralizada. Assim, o objectivo deste trabalho foi caracterizar o comportamento de células osteoblásticas provenientes de medula óssea humana na presença de concentrações de nicotina representativas dos níveis sanguíneos e salivares presentes nos indivíduos com hábitos tabágicos. As culturas celulares foram mantidas durante 28 dias em condições experimentais que favorecem a diferenciação do fenótipo osteoblástico e cultivadas na ausência (situação controlo) e na presença de nicotina (10 ng/ml - 1 mg/ml). A exposição a 10 ng/ml (concentração representativa dos níveis plasmáticos) não afectou significativamente a proliferação e actividade funcional. A presença de concentrações superiores (0,01 - 1 mg/ml, representativas dos níveis salivares) influenciou o comportamento celular, de modo dependente da dose. As culturas expostas a 0,01 - 0,2 mg/ ml apresentaram estimulação da proliferação celular e da actividade de fosfatase alcalina, associada a uma antecipação do processo de mineralização da matriz extracelular. A exposição a 0,3 mg/ml causou um efeito inibitório inicial, seguido de recuperação dos parâmetros de crescimento e função. Na presença de concentrações superiores, observaram-se efeitos negativos no comportamento celular durante todo o período de incubação; as culturas apresentaram uma diminuição do número de células aderentes, níveis de fosfatase alcalina baixos e extensa vacuolização citoplasmática. Os resultados sugerem a possibilidade de modulação local da actividade osteoblástica pela nicotina, a nível da cavidade oral.

The use of tobacco has been implicated in bone pathologies like osteoporosis and alveolar bone loss associated to periodontal disease. Bone formation involves the differentiation of osteoprogenitor cells into osteoblasts and the formation of a mineralised colagenous matrix. Therefore, the aim of this work was to characterise the behaviour of human bone marrow derived osteoblastic cells in the presence of nicotine at concentrations representatives of those present in plasma and saliva of tobacco users. Cell cultures were maintained for 28 days in experimental conditions that favour the differentiation of the osteoblastic phenotype and cultured in the absence (control) and in the presence of nicotine (10 ng/ml - 1 mg/ml). Results showed that nicotine, at 10 ng/ml (representative of plasmatic levels), did not affect significantly cell proliferation and functional activity. The presence of higher levels, 0.01 - 1mg/ml (representative of the salivary levels), affected cell behaviour in a dose dependent manner. Cultures exposed to 0.01 - 0.2 mg/ml presented increased cell proliferation and alkaline phosphatase activity, associated to an anticipation of the matrix mineralization. Treatment with 0.3 mg/ml caused an initial inhibitory effect followed by a recovery of the cell growth and functional parameters. In the presence of higher concentrations, negative effects on cell behaviour were observed throughout the incubation time; cultures presented decreased numbers of adherent cells, low alkaline phosphatase levels and cytoplasm vacuolation. Results suggest the possibility of local modulation of the osteoblastic activity by nicotine, at the oral cavity.