Relação entre materiais dentários e o complexo dentino-pulpar

Despite the strong valorization of the esthetics and its relationship with restorative materials, the biological principles of any clinical procedure are extremely important to maintain the vitality of the dentin-pulp complex. Dentin and pulp tissue are susceptible to different kinds of irritants such as toxins from microorganisms, traumatic procedures of cavity preparation, as well as toxic components released by restorative materials applied in non recommended clinical situations. Initially, the pulp responds to irritation by starting an inflammatory reaction which involves outward movement of dentinal fluid and intratubular deposition of immunoglobulins, upregulation of odontoblast activities, presence of immune cells and their cytokines as well as local expression of neuropeptides and chemokines. After these initial events, the inflammation process can be resolved associated or not to sclerotic dentin formation and reactionary dentin deposition. If high intensity offensive stimuli are applied to the dentin-pulp complex, death of odontoblasts takes place and consequently pulp ageing or even partial necrosis of this tissue may occurs. Thereby, clinicians need to be aware about the physiological and pathological features of the dentin-pulp complex as well as the possible biological consequences of different clinical procedures. In this way, the dentists should be able to carry out minimally aggressive operative techniques and to select the more appropriate restorative materials for each specific clinical situation in order to obtain excellent clinical results associated to the maintenance of pulp vitality.

Immediate human pulp response to ethanol-wet bonding technique

To evaluate the short-term response of human pulps to ethanol-wet bonding technique. Methods Deep class V cavities were prepared on 17 sound premolars and divided into three groups. After acid-etching, the cavities from groups 1 (G1) and 2 (G2) were filled with 100% ethanol or distilled water, respectively, for 60 s before the application of Single Bond 2. In group 3 (G3, control), the cavity floor was lined with calcium hydroxide before etching and bonding. All cavities were restored with resin composite. Two teeth were used as intact control. The teeth were extracted 48 h after the clinical procedures. From each tooth serial sections were obtained and stained with haematoxylin and eosin (H/E) and Masson's trichrome. Bacteria microleakage was assessed using Brown & Brenn. All sections were blindly evaluated for five histological features. Results Mean remaining dentine thickness was 463 ± 65 μm (G1); 425 ± 184 μm (G2); and 348 ± 194 μm (G3). Similar pulp reactions followed ethanol- or water-wet bonding techniques. Slight inflammatory responses and disruption of the odontoblast layer related to the cavity floor were seen in all groups. Stained bacteria were not detected in any cavities. Normal pulp tissue was observed in G3 except for one case. Conclusions After 48 h, ethanol-wet bonding does not increase pulpal damage compared to water-wet bonding technique. Clinical significance Ethanol-wet bonding may increase resin-dentine bond durability. This study reported the in vivo response of human pulp tissue when 100% ethanol was applied previously to an etch-and-rinse simplified adhesive system.

Transdentinal cell photobiomodulation using different wavelengths

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Efeito citotóxico de agentes clareadores a base de peróxido de hidrogênio a 20% e 38% sobre células odontoblastóides

The aim of this in vitro study was to evaluate the trans-enamel and transdentinal cytotoxic effects of two in-office tooth bleaching techniques that employ bleaching gels containing 20% and 38% of H2 O2 on cultured odontoblast-like cell line (MDPC-23). Sixty enamel/dentin discs were obtained from bovine central incisors and placed individually in artificial pulp chambers. Six groups were formed according to the following enamel treatments: G1- 20% H2 O2 (1 application); G2- 20% H2 O2 (2 applications); G3- 38% H2 O2 (1 application); G4- 38% H2 O2 (2 applications); G5- 38% H2 O2 (3 applications); and G6- control (no treatment). In G1 and G2, the bleaching gel was left in contact with the enamel surface for 45 min in each application. However, in G3, G4, and G5 the bleaching gel was applied for only 10 min per application. After the last application, the extracts were collected and applied on previously cultured cells (30.000 cells/cm2 ) for 24 h. Cell metabolism was evaluated by the MTT assay and cell morphology was analysed by scanning electron microscopy. Cell metabolism decreased by 96.29%; 96.11%; 96.42%; 95.62%; and 97.18% in G1, G2, G3, G4, and G5, respectively. All treated groups differed significantly from non-treated control group (G6) (p < 0.05). However, the difference in cell metabolism among treated groups was not significant statistically. In addition, significant morphological cell alterations were observed in all treated groups. Under the tested experimental conditions, the extracts collected after both tooth bleaching techniques evaluated in this study caused severe toxic effects on cultured odontoblast-like cell MDPC-23.

Citotoxicidade transamelodentinária de uma fita clareadora com 10% de peróxido de hidrogênio sobre células de linhagem odontoblástica

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Cytotoxicity of resin-based luting cements to pulp cells

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Color alteration, hydrogen peroxide diffusion, and cytotoxicity caused by in-office bleaching protocols

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Dose-Response and Time-Course of a-Tocoferol Mediating the Cytoprotection Of Dental Pulp Cells Against Hydrogen Peroxide

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Efeitos do LPS bacteriano nos processos funcionais e de diferenciação de células progenitoras da polpa dentária

Pós-graduação em Odontologia Restauradora - ICT

Responses of Dental Pulp Cells to a Less Invasive Bleaching Technique Applied to Adhesively Restored Teeth

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Cytocompatibility of HEMA-free resin-based luting cements according to application protocols on dentine surfaces

To evaluate the transdentinal cytotoxicity of resin-based luting cements (RBLCs), with no HEMA in their composition, to odontoblast-like cells. Human dentine discs 0.3 mm thick were adapted to artificial pulp chambers (APCs) and placed in wells of 24-well plates containing 1 mL of culture medium (DMEM). Two categories of HEMA-free RBLCs were evaluated: group 1, self-adhesive Rely X Unicem (RU; 3M ESPE), applied directly to the dentine substrate; and group 2, Rely X ARC (RARC; 3M ESPE), applied to dentine previously acid-etched and treated with a bonding agent. In group 3 (control), considered as representing 100% cell metabolic activity, no treatment was performed on dentine. The APC/disc sets were incubated for 24 h or 7 days at 37 °C and 5% CO2 . Then, the extracts (DMEM + dental materials components that diffused through dentine) were applied to cultured odontoblast-like MDPC-23 cells for 24 h. After that, the cell viability (MTT assay), cell morphology (SEM), total protein production (TP) and alkaline phosphatase (ALP) activity were assessed. Data from MTT assay and TP production were analysed by Kruskal-Wallis and Mann-Whitney tests (α = 5%). Data from ALP activity were analysed by one-way anova and Tukey's test (α = 5%). In group 1, a slight reduction in cell viability (11.6% and 16.8% for 24-h and 7-day periods, respectively) and ALP activity (13.5% and 17.9% for 24-h and 7-day periods, respectively) was observed, with no significant difference from group 3 (control) (P > 0.05). In group 2, a significant reduction in cell viability, TP production and ALP activity compared with group 3 (control) occurred (P < 0.05), regardless of incubation time. Alteration in MDPC-23 cell morphology was observed only in group 2. HEMA-free Rely X ARC cement caused greater toxicity to odontoblast-like MDPC-23 cells than did Rely X Unicem cement when both resin-based luting materials were applied to dentine as recommended by the manufacturer.

Transdentinal cytotoxicity of resin-based luting cements to pulp cells

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Efeito da combinação de antibióticos e sinvastatina sobre microrganismos de interesse endodôntico e na expressão de marcadores odontoblásticos

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

In vitro evaluation of the odontogenic potential of mouse undifferentiated pulp cells

The aim of this study was to evaluate the odontogenic potential of undifferentiated pulp cells (OD-21 cell line) through chemical stimuli in vitro. Cells were divided into uninduced cells (OD-21), induced cells (OD-21 cultured in supplemented medium/OD-21+OM) and odontoblast-like cells (MDPC-23 cell line). After 3, 7, 10 and 14 days of culture, it was evaluated: proliferation and cell viability, alkaline phosphatase activity, total protein content, mineralization, immunolocalization of dentin matrix acidic phosphoprotein 1 (DMP1), alkaline phosphatase (ALP) and osteopontin (OPN) and quantification of genes ALP, OSTERIX (Osx), DMP1 and runt-related transcription factor 2 (RUNX2) through real-time polymerase chain reaction (PCR). Data were analyzed by Kruskal-Wallis and Mann-Whitney U tests (p<0.05). There was a decrease in cell proliferation in OD-21 + OM, whereas cell viability was similar in all groups, except at 7 days. The amount of total protein was higher in group OD-21 + OM in all periods; the same occurred with ALP activity after 10 days when compared with OD-21, with no significant differences from the MDPC-23 group. Mineralization was higher in OD-21+OM when compared with the negative control. Immunolocalization demonstrated that DMP1 and ALP were highly expressed in MDPC-23 cells and OD-21 + OM cells, whereas OPN was high in all groups. Real-time PCR revealed that DMP1 and ALP expression was higher in MDPC-23 cell cultures, whereas RUNX2 was lower for these cells and higher for OD-21 negative control. Osx expression was lower for OD-21 + OM. These results suggest that OD-21 undifferentiated pulp cells have odontogenic potential and could be used in dental tissue engineering.

Anwendung der konfokalen Laser-Scanning-Mikroskopie zur Charakterisierung der Struktur von Zähnen und von oberflächenmodifiziertem Titan für Knochenimplantate

Zusammenfassung Mittels Fluoreszenzfarbstoffen können Strukturen sichtbar gemacht werden, die auf kon-ventionellem Weg nicht, oder nur schwer darzustellen sind. Besonders in Kombination mit der Konfokalen Laser Scanning Mikroskopie eröffnen sich neue Wege zum spezifischen Nachweis unterschiedlichster Komponenten biologischer Proben und gegebenenfalls deren dreidimensionale Widergabe.Die Visualisierung des Proteinanteils des Zahnhartgewebes kann mit Hilfe chemisch kopplungsfähiger Fluorochrome durchgeführt werden. Um zu zeigen, daß es sich bei dieser Markierung nicht um unspezifische Adsorption des Farbstoffes handelt, wurde zur Kontrolle die Proteinkomponente der Zahnproben durch enzymatischen Verdau beseitigt. Derartig behandelte Präparate wiesen eine sehr geringe Anfärbbarkeit auf.Weiterführend diente diese enzymatische Methode als Negativkontrolle zum Nachweis der Odontoblastenfortsätze im Dentin bzw. im Bereich der Schmelz-Dentin-Grenze. Hiermit konnte differenziert werden zwischen reinen Reflexionsbildern der Dentinkanäle und den Zellausläufern deren Membranen gezielt durch lipophile Fluoreszenzfarbstoffe markiert wurden.In einem weiteren Ansatz konnte gezeigt werden, daß reduzierte und daher nichtfluoreszente Fluoresceinabkömmlinge geeignet sind, die Penetration von Oxidationsmitteln (hier H2O2) in den Zahn nachzuweisen. Durch Oxidation dieser Verbindungen werden fluoreszierende Produkte generiert, die den Nachweis lieferten, daß die als Zahnbleichmittel eingesetzten Mittel rasch durch Schmelz und Dentin bis in die Pulpahöhle gelangen können.Die Abhängigkeit der Fluoreszenz bestimmter Fluorochrome von deren chemischer Um-gebung, im vorliegenden Fall dem pH-Wert, sollte eingesetzt werden, um den Säuregrad im Zahninneren fluoreszenzmikroskopisch darzustellen. Hierbei wurde versucht, ein ratio-metrisches Verfahren zu entwickeln, mit dem die pH-Bestimmung unter Verwendung eines pH-abhängigen und eines pH-unabhängigen Fluorochroms erfolgt. Diese Methode konnte nicht für diese spezielle Anwendung verifiziert werden, da Neutralisationseffekte der mineralischen Zahnsubstanz (Hydroxylapatit) die pH-Verteilung innerhalb der Probe beeinflußen. Fluoreszenztechniken wurden ebenfalls ergänzend eingesetzt zur Charakterisierung von kovalent modifizierten Implantatoberflächen. Die, durch Silanisierung von Titantestkörpern mit Triethoxyaminopropylsilan eingeführten freien Aminogruppen konnten qualitativ durch den Einsatz eines aminspezifischen Farbstoffes identifiziert werden. Diese Art der Funktionalisierung dient dem Zweck, Implantatoberflächen durch chemische Kopplung adhäsionsvermittelnder Proteine bzw. Peptide dem Einheilungsprozeß von Implantaten in den Knochen zugänglicher zu machen, indem knochenbildende Zellen zu verbessertem Anwachsverhalten stimuliert werden. Die Zellzahlbestimmung im Adhäsionstest wurde ebenfalls mittels Fluoreszenzfarbstoffen durchgeführt und lieferte Ergebnisse, die belegen, daß die durchgeführte Modifizierung einen günstigen Einfluß auf die Zelladhäsion besitzt.