Influence of abutment angulation on loss of prosthetic abutment torque under mechanical cycling.

STATEMENT OF PROBLEM: Internal conical connections provide mechanical stability for the prosthetic abutment and implant connection. However, some clinical situations require the use of angled prosthetic abutments that may increase stress on supportive implants by difference force vectors under cyclic loading. PURPOSE: The purpose of this in vitro study was to measure the screw loosening values of prosthetic abutments with internal conical connections (indexed and nonindexed) having different angles under mechanical cycling. MATERIAL AND METHODS: Thirty-six implants (4.0×13 mm, Titamax) with internal conical connections and their respective universal prosthetic abutments (n=36, 3.5×3.3 mm) were divided into indexed and nonindexed groups (n=18) with abutment inclinations of 0 (straight), 17, and 30 degrees. An insertion torque of 15 Ncm was applied according to the manufacturer's specifications. The specimens underwent fatigue testing of 500 000 cycles at a frequency of 2 Hz with a dynamic compressive load of 120 N at an angle of 30 degrees. The detorque values were measured by using a digital torque meter and tabulated for statistical analyses. RESULTS: The specimens with indexed abutments had mean ±standard deviation detorque values of 6.72 ±2.29 Ncm under mechanical cycling, whereas those with nonindexed abutments had values of 8.98 ±1.84 Ncm. In the indexed group, the lowest detorque value was observed for abutments at 30 degrees compared with the straight group (P<.05). As for nonindexed abutments, similar detorque values were observed after increasing the abutment inclination (P>.05). CONCLUSIONS: A decrease in detorque values in the indexed abutments related to their inclination was found under mechanical cycling, whereas the prosthetic abutments with 30 degrees of angulation had the lowest values. No decrease was found in the nonindexed abutments.

Peroxiredoxin I expression in epithelial cells of buccal mucosa from patients exposed to panoramic X-rays: influence of the age.

OBJECTIVES: The aim of this study was to evaluate peroxiredoxin I (Prx I) participation in the cellular antioxidant response to low-dose X-rays through the analysis of its expression in buccal mucosa cells from patients of different ages following panoramic dental radiography. MATERIALS AND METHODS: Of the 50 patients included in this study, oral mucosa cells from six adults were collected for the immunofluorescence cytological analysis. The other 44 patients, 11 patients aged below 20 years; 22 patients aged between 20 and 50 years; and 11 patients aged above 50 years, were submitted to panoramic dental radiography, and oral mucosa cells were collected for the gene expression analysis before and 1 hour after exposure. RESULTS: The results demonstrated Prx I expression in the cytoplasm of oral mucosa cells either before or after radiation exposure. The quantitative analysis showed that in oral mucosa cells from patients aged below 50 years the mRNA levels of PRDX1 were significantly increased after radiation exposure. On the other hand, the cells from patients aged above 50 years presented significantly lower PRDX1 transcript levels after radiation exposition. CONCLUSIONS: Panoramic radiography leads to increased Prx I expression in buccal mucosa cells, probably as an adaptive response to eliminate X-ray-induced ROS, except in cells from elderly people. CLINICAL RELEVANCE: Even low doses of radiation employed for dental purposes are capable to provoke stress to cells, which was demonstrated via the induction of the antioxidant gene PRDX1. In elderly patients, such mechanism was demonstrated to be impaired.

In Vitro Microbiological Analysis of Bacterial Seal in Hybrid Zirconia Abutment Tapered Connection.

PURPOSE: The aim of this study was to evaluate the bacterial seal at the implant-hybrid zirconia abutment interface and Morse taper-type connections through in vitro microbiological analysis. MATERIALS AND METHODS: Sixteen implants and their respective abutments were divided into 3 groups: test (10 sets), positive control (3 sets), and negative control (3 sets). In the test group, 10 implants were contaminated with Escherichia coli using a sterile inoculating loop to the inner portion of the implants, followed by torque application to the abutment (30 N·cm). The positive controls were also contaminated, but no torque was applied to the abutment screw. The negative control consisted of uncontaminated sets. All specimens were immersed in test tubes containing 5 mL brain heart infusion (BHI) broth, maintained in a microbiological incubator for 14 days at 37°C under aerobic conditions, and monitored every 24 hours for evidence of bacterial growth. RESULTS: During the 14 days of incubation, no significant increase in the number of cloudy culture media was observed in the test group (P = 0.448). No significant difference in broth turbidity ratio was observed (P > 0.05). CONCLUSION: Hybrid zirconia abutments can create an effective seal at the tapered abutment-implant interface with a 30-N·cm installation torque.

In vitro cytotoxicity of resin cement and its influence on the expression of antioxidant genes.

AIM: This study evaluated cytotoxicity and antioxidant gene expression of resin cements on human gingival fibroblasts (hGF). MATERIALS AND METHOD: RelyX Ultimate™(RXU), Variolink™II(VLII), and RelyXU200™(RXU200) resin cements were incubated with culture medium for 24 h to obtain eluates. Then, the eluates were applied over hGF to assess cell viability at 24 h, 48 h, and 72 h and antioxidant gene expression at 24 h. hGF cultures non-exposed to the eluates were used as Control. Data were submitted to ANOVA and Bonferroni tests (α≤0.05). RESULTS: RXU and RXU200 reduced the number of viable cells in 24 h. Longer exposure to cement extracts caused cell death. Gene expression showed peroxiredoxin 1 (PRDX1) induction by all resin cement types, and superoxide dismutase 1 (SOD1) induction by RXU200 and VLII. Moreover, RXU200 induced not only PRDX1 and SOD1, but also glutathione peroxidase 1 (GPX1), catalase (CAT), and glutathione synthetase (GSS). CONCLUSIONS: All resin cements showed toxicity, and induced antioxidant genes in hGF. Antioxidant gene induction is at least partly associated with cytotoxicity of tested cements to oxidative stress experience.

OBJETIVO: O objetivo deste estudo foi avaliar a toxicidade dos cimentos resinosos Rely X Ultimate 2, Rely X U200 e Variolink II, bem como sua influência na expressão de genes antioxidantes em fibroblastos gengivais humanos. Materiais e Método: Corpos de prova de cada cimento foram colocados em meio de cultura por 24 h e os extratos correspondentes foram aplicados aos fibroblastos. A viabilidade celular foi avaliada após 24, 48 e 72 h de exposição pelo ensaio de exclusão do azul de tripano e MTT. A expressão gênica foi avaliada por PCR quantitativo após 24 h de exposição aos extratos. Estes parâmetros foram comparados aos das células não expostas aos cimentos. Os dados foram submetidos ao teste ANOVA, seguido pelo pós-teste de Bonferroni (a≤0.05). RESULTADOS: Os resultados demonstraram que todos os cimentos promoveram redução do número de células viáveis e da atividade mitocondrial nos períodos de 48 e de 72 h (p< 0,01), sendo que o Variolink II apresentou o menor efeito e os cimentos Rely X Ultimate e Rely X U200 promoveram similarmente os maiores efeitos. A análise de expressão gênica evidenciou influência significativa em todos os cimentos avaliados sobre os níveis de transcritos de PRDX1, SOD1, GPX1 e GSS (p> 0,05), com um aumento considerável no Rely X U200. Conclusão: A indução de genes antioxidantes está, pelo menos em parte, associada à citotoxicidade dos cimentos testados para a experiência de estresse oxidativo.

Can Collagen Membrane on Bone Graft Interfere with Light Transmission and Influence Tissue Neoformation During Photobiomodulation? A Preliminary Study.

Objective: This study qualitatively and quantitatively evaluated the transmission of light through a collagen membrane and the consequent local bone formation in a critical bone defect in vitro and in an animal model. Background: Currently, bone substitutes and collagen membranes are used to promote new bone formation; however, when associated with photobiomodulation, biomaterials can act as a barrier, hindering the passage of light radiation to the area to be treated. Methods: Light transmittance was evaluated in vitro with a power meter and a 100 mW, 808 nm laser source with and without membrane. Twenty-four male rats received a critical surgical defect of 5 mm in diameter in the calvarial bone, subsequently a biomaterial (Bio-Oss; Geistlich®, Switzerland) was applied, and the animals were divided into the following three groups: G1-collagen membrane and no irradiation; G2-collagen membrane and photobiomodulation (irradiation with 4 J of 808 nm); and G3-photobiomodulation (4 J) followed by a collagen membrane. Histomophometric analyses were performed at 7 and 14 days after euthanasia. Results: The membrane reduced the light transmittance (808 nm) by an average of 78%. Histomophometric analyses showed significant differences in new blood vessels on day 7 and bone neoformation on day 14. Irradiation without membrane interposition resulted in a 15% more neoformed bone compared with the control (G1), and 6.5% more bone compared with irradiation over the membrane (G2). Conclusions: The collagen membrane interferes with light penetration during photobiomodulation, decreases light dosimetry on the wound area, and interferes with bone neoformation.

Clinical and Molecular Microbiological Evaluation of Regenerative Endodontic Procedures in Immature Permanent Teeth.

INTRODUCTION: This study evaluated the bacterial levels after regenerative endodontic procedures and their correlation with the treatment outcome using molecular microbiology methods. METHODS: Root canal samples of 15 necrotic immature teeth were analyzed by quantitative polymerase chain reaction. Bacteria were counted before treatment (S1), after irrigation with 6% sodium hypochlorite (S2), and after intracanal dressing (S3) using either triple antibiotic paste (n = 7) or calcium hydroxide with chlorhexidine (n = 8). The Wilcoxon test for related samples and the Mann-Whitney test were used for statistical analysis (P < .05). After a follow-up period of 12-48 months, clinical and radiographic findings were correlated with microbiological data using a linear regression model (P < .05). RESULTS: All S1 and S2 samples were positive for bacteria, but the number of positive S3 samples decreased to 53.3% (P = .001). Overall, there was a significant reduction of bacterial levels after each treatment step (S1-S2, P = .001; S2-S3, P = .02). In the triple antibiotic paste and chlorhexidine groups, 57.1% and 50% of S3 samples were positive with median numbers of 6.97 × 103 and 3.59 × 104 bacterial cells, respectively. No significant differences were found between the groups. Periapical healing occurred in all cases despite the presence of low levels of residual bacteria. However, the latter had a negative impact on the thickness of dentinal walls (R2 = 0.0043). CONCLUSIONS: Although the bacterial levels were drastically reduced after the regenerative endodontic procedures, the residual bacteria influenced the thickness of the dentinal walls.

Photobiomodulation increases intrusion tooth movement and modulates IL-6, IL-8 and IL-1ß expression during orthodontically bone remodeling.

This study investigated the effects of photobiomodulation (PBM) on upper molar intrusion movement, regarding acceleration of orthodontic movement and its molecular effects. The sample consisted of 30 patients with indication of tooth intrusion for oral rehabilitation. Teeth were divided into three different groups: G1 (n = 10) pre-molars without force or laser application (control); G2 (n = 10) upper molar intrusion; and G3 (n = 10) upper molar intrusion and PBM. On PBM treated molars, the teeth were irradiated with a low-power diode laser (808 nm, 100 mW), receiving 1 J per point, density of 25 J/cm2 , with application of 10 s per point, 10 points (5 per vestibular and 5 per palatal region). Orthodontic force of intrusion applied every 30 days and PBM was performed immediately, 3 and 7 days after force application for 3 months. Gingival crevicular fluid was collected at the same time periods as the laser applications and interleukins (IL) 1-ß, -6 and -8 were evaluated by enzyme-linked immunosorbent assay. Clinical measures were performed monthly to verify the amount of intrusion. The levels of IL-6, IL-8 and IL-1ß increased under orthodontic force (G2 and G3) when compared to control group (G1), however, the cytokines levels were significantly higher after PBM (G3). The mean intrusion velocity was 0.26 mm/month in the irradiated group (G3), average duration of 8 months vs 0.17 mm/month for the non-irradiated group (G2), average duration of 12 months. This study suggests that PBM accelerates tooth movement during molar intrusion, due to modulation of IL-6, IL-8 and IL-1ß during bone remodeling.

In vitro cytotoxicity of resin cement and its influence on the expression of antioxidant genes / Avaliação in vitro da toxicidade de cimentos resinosos e sua influência na expressão de genes antioxidantes em fibroblastos humanos

ABSTRACT Aim: This study evaluated cytotoxicity and antioxidant gene expression of resin cements on human gingival fibroblasts (hGF). Materials and Method: RelyX Ultimate™(RXU), Variolink™II(VLII), and RelyXU200™(RXU200) resin cements were incubated with culture medium for 24 h to obtain eluates. Then, the eluates were applied over hGF to assess cell viability at 24 h, 48 h, and 72 h and antioxidant gene expression at 24 h. hGF cultures non-exposed to the eluates were used as Control. Data were submitted to ANOVA and Bonferroni tests (α≤0.05). Results: RXU and RXU200 reduced the number of viable cells in 24 h. Longer exposure to cement extracts caused cell death. Gene expression showed peroxiredoxin 1 (PRDX1) induction by all resin cement types, and superoxide dismutase 1 (SOD1) induction by RXU200 and VLII. Moreover, RXU200 induced not only PRDX1 and SOD1, but also glutathione peroxidase 1 (GPX1), catalase (CAT), and glutathione synthetase (GSS). Conclusions: All resin cements showed toxicity, and induced antioxidant genes in hGF. Antioxidant gene induction is at least partly associated with cytotoxicity of tested cements to oxidative stress experience.

RESUMO Objetivo: O objetivo deste estudo foi avaliar a toxicidade dos cimentos resinosos Rely X Ultimate 2, Rely X U200 e Variolink II, bem como sua influência na expressão de genes antioxidantes em fibroblastos gengivais humanos. Materiais e Método: Corpos de prova de cada cimento foram colocados em meio de cultura por 24 h e os extratos correspondentes foram aplicados aos fibroblastos. A viabilidade celular foi avaliada após 24, 48 e 72 h de exposição pelo ensaio de exclusão do azul de tripano e MTT. A expressão gênica foi avaliada por PCR quantitativo após 24 h de exposição aos extratos. Estes parâmetros foram comparados aos das células não expostas aos cimentos. Os dados foram submetidos ao teste ANOVA, seguido pelo pós-teste de Bonferroni (a≤0.05). Resultados: Os resultados demonstraram que todos os cimentos promoveram redução do número de células viáveis e da atividade mitocondrial nos períodos de 48 e de 72 h (p < 0,01), sendo que o Variolink II apresentou o menor efeito e os cimentos Rely X Ultimate e Rely X U200 promoveram similarmente os maiores efeitos. A análise de expressão gênica evidenciou influência significativa em todos os cimentos avaliados sobre os níveis de transcritos de PRDX1, SOD1, GPX1 e GSS (p> 0,05), com um aumento considerável no Rely X U200. Conclusão: A indução de genes antioxidantes está, pelo menos em parte, associada à citotoxicidade dos cimentos testados para a experiência de estresse oxidativo.

Effect of Surgical Installation of Dental Implants on Surface Topography and Its Influence on Osteoblast Proliferation.

Surface treatment alone does not determine the final microtopography of a dental implant, which can be influenced by implant design and the surgical procedure. This study investigated the effect of surgical placement of dental implants with same surface treatments on surface roughness. Three implants (SIN) of each group with different macrogeometries (Strong, Stylus, and Tryon) were analyzed using laser interferometry and scanning electron microscopy to evaluate surface topography. All threaded regions of the implants, namely, top, flank, and valley, were analyzed individually. Relevant surface parameters (S a, S sk, S ku, S tr, and S dq) were calculated for the different regions on each implant before (B) (n = 9) and after (A) (n = 9) placement into porcine rib bones. The behavior and proliferation of a preosteoblastic cell line MC3T3-E1 on titanium surface, cell viability, and osteopontin secretion were evaluated after 24 h, 48 h, and 96 h, also before (n = 18) and after (n = 18) implant placement into porcine ribs bone. As results, the valleys of all implants had an increase in S a values after implant placement. By contrast, the tops of the Stylus A implant and the flanks of the Tryon A implant showed a significant decrease in mean height of the irregularities (S a), 0.16 µm and 1.25 µm, respectively. The Stylus implant presented significantly (p < 0.05) higher asymmetry values on the distribution curve for irregularity heights (S ku) in all regions after insertion into bone (6.99 for tops, 9.54 for flanks, and 17.64 for valleys), indicating a greater preponderance of peaks over valleys. An increase in roughness gradients (S dq) was observed for all macrogeometries after insertion into bone. The cell culture results showed no significant difference (p > 0.05) for all macrogeometries after bone placement. In conclusion, a subtle change in implant surface roughness was detected after insertion into bone for all the macrogeometries, without significantly affecting the cellular parameters studied.

TGF-beta1 enhances the expression of alpha-smooth muscle actin in cultured human pulpal fibroblasts: immunochemical and ultrastructural analyses.

Transforming growth factor-beta 1 (TGF-beta1) has been related to induce the expression of alpha-smooth muscle actin (alpha-SMA) in fibroblasts during repair. Because pulpal fibroblasts seem to be somewhat different from other fibroblasts, the present study investigated in vitro whether TGF-beta1 enhances the expression of alpha-SMA in human pulpal fibroblasts. TGF-beta1 was added in doses between 5-10 ng/mL to cultures of both dental pulp and gingival human fibroblasts. The expression of alpha-SMA was analyzed by immunofluorescence and Western blotting, whereas the ultrastructure was evaluated by electron microscopy. In addition, the expression of tenascin, osteonectin, and vimentin was also investigated. Both cell types were immunoreactive for alpha-SMA even without TGF-beta1. When TGF-beta1 was added to cell cultures, the expression of alpha-SMA increased dramatically in pulpal fibroblasts, independent of the concentration used. It was confirmed by the Western blotting analysis. Ultrastructure revealed myofilaments and indented nuclei in both fibroblasts treated with TGF-beta1. Tenascin and osteonectin were only immunolabeled in pulpal fibroblasts treated or not with TGF-beta1. Both fibroblast types were positive for vimentin. The present findings showed that TGF-beta1 up-regulated the expression of alpha-SMA, thus inducing pulpal fibroblasts to acquire the myofibroblast phenotype.

Effects of Low-Level Laser Therapy in Orthodontic Patients on Immediate Inflammatory Response After Mini-Implants Insertion: A Preliminary Report.

BACKGROUND: The primary stability of a mini-implant is crucial to treatment sequence since most orthodontic mini-implant failures occur at an early stage. Irritation or inflammation of peri-implant tissues has been related to decreasing mini-implant success. PURPOSE: This study evaluates the effect of low-level laser therapy on initial inflammation after orthodontic mini-implants installation. METHODS: Ten volunteers received two mini-implants (1.3 mm diameter, 7 mm length). One mini-implant was inserted on each side of the maxilla following manufacturer recommendation. On the right side, low-level laser therapy (LLLT) was applied (diode laser 660 nm, 40 mW, 1 min, 2.4 J of total energy). Peri-implant crevicular fluid (PGF) was obtained after 24 h (T1), 48 h (T2), and 72 h (T3) to identify levels of interleukin (IL)-6 and IL-8 around mini-implants and around upper first premolars. RESULTS: An increase in interleukin levels was observed for both groups, compared to upper first premolar. PGF around nonirradiated mini-implants showed higher levels of IL-8. Levels of IL-6 24 h after mini-implant insertion were higher for laser group. CONCLUSIONS: LLLT modulates the initial inflammation after the insertion of mini-implant, possibly increasing the mini-implant success prognostic and decreasing patient discomfort.

Rehabilitation of the atrophic mandible with short implants in different positions: A finite elements study.

OBJECTIVE: The aim of this study was to analyze whether the use of inclined short implants without lower transcortical involvement (test model - SI), thus preserving the mandibular lower cortical bone, could optimize stress distribution. MATERIALS AND METHODS: Six identical atrophic mandible models were created featuring 8mm of height at the symphysis. Two study factors were evaluated: implant length and angulation. Implant length was represented either by short implants (7mm) with preservation of the mandibular lower cortical bone or standard implants (9mm) with a bicortical approach and 3 possible implant positioning configurations: 4 distally-inclined implants at 45° (experimental model), all-on-four, 4 vertical implants. All tridimensional (3D) models were analyzed using the Finite Element Method (FEM) and the Ansys Workbench software. RESULTS: The maximum stress on the bone at the cervical region of the implants in the experimental model was 132MPa and transcortical involvement with implant inclination yielded higher values (171MPa). Regarding von Mises stress on the retaining screw of the prosthesis, 61MPa was recorded for the experimental model while upright implants had the highest values (223MPa). At the acrylic base, 4MPa was recorded for the experimental model whereas models with upright implants showed the highest stress values (11MPa). CONCLUSION: Rehabilitation of severely resorbed mandibles with 4 short implants placed distally at 45°, without lower transcortical involvement, were biomechanically more favorable, generating lower stress peaks, than the models with short implants on an all-on-four, or on an upright configuration, with or without lower transcortical involvement.

Microbiological Seal of Two Types of Tapered Implant Connections.

Tapered implant connections have gained wide popularity for being more resistant to fatigue and for promoting a better seal against bacterial infiltration than conventional connections. The aim of this study was to evaluate the bacterial seal at the implant-abutment interface using two Morse taper implant models, by in vitro microbiological analysis. Eleven non-indexed and 11 indexed abutments were selected and connected to their respective implants with a 20 N torque, according to manufacturer's recommendation. Microbiological analysis was carried out using colonies of Escherichia coli transported directly from a culture dish to the prosthetic component. For control, one non-contaminated abutment-implant set from each group (negative control) and one contaminated implant with no abutment (positive control) were used. The specimens were immersed in BHI broth and maintained in an incubator at 37 °C for 14 days to assess the development of bacterial contamination. The results revealed that 36.4% (n=4) of the indexed components and 90.9% (n=10) of the non-indexed components allowed bacterial leakage, with significant difference between groups (p=0.0237). In conclusion, both tapered components failed to provide adequate sealing to bacterial leakage, although the indexed type components showed a superior seal compared with non-indexed components.

Expression of SOFAT by T- and B-lineage cells may contribute to bone loss.

A novel T cell-secreted cytokine, termed secreted osteoclastogenic factor of activated T cells (SOFAT) that induces osteoclastic bone resorption in a RANKL-independent manner, has been described. Our group have previously reported that SOFAT is highly expressed in gingival tissues of patients with chronic periodontitis suggesting a putative role in the bone loss associated with periodontal disease. The aim of the present study was to identify other potential cellular sources of SOFAT in the bone resorptive lesions of patients with periodontal disease. Gingival tissues were biopsied from systemically healthy subjects without periodontal disease (n=5) and patients with chronic periodontitis (n=5), and the presence of SOFAT was analyzed by immunohistochemistry and immunofluorescence staining. The present data demonstrated marked SOFAT staining in diseased periodontal tissues that was predominantly associated with the lymphocytic infiltration of gingival tissues. Notably, in addition to CD3+ T cells, B­lineage cells including plasma cells also exhibited strong staining for SOFAT. As SOFAT has not previously been reported in B­lineage cells, splenic T cells and B cells were further purified from BALB/c mice and activated using CD3/CD28 and lipopolysaccharide, respectively. SOFAT was quantified by reverse transcription­quantitative polymerase chain reaction and was shown to be significantly expressed (P<0.05) in both activated T cells and B cells compared with unstimulated cells. These data support a putative role of SOFAT in the bone loss associated with chronic periodontal disease. In addition, to the best of our knowledge, this study demonstrates for the first time that in addition to T cells, B-lineage cells may also be a significant source of SOFAT in inflammatory states.

Evaluation of the Biological Behavior of Mucograft® in Human Gingival Fibroblasts: An In Vitro Study.

Mucograft(r) is a resorbing porcine matrix composed of type I and type III collagen, used for soft tissue augmentation in guided tissue bony regeneration procedures. This in vitro study aimed to evaluate the biological behavior of Mucograft(r) in human gingival fibroblasts, as well as the ability of the matrix to induce production of extracellular matrix. Six resorbing Mucograft(r) matrices (MCG) were cut into 3 x 2 mm rectangles and 5 x 5 mm squares and were placed in 96- and 24-well plates, respectively. The control group (CTRL) consisted of cells plated on polystyrene without the MCG. After one, two, three and seven days, cell proliferation and viability were assessed using the Trypan exclusion method and MTT test, respectively. Type III collagen (COL 3A1) and vimentin (VIM) expression were also evaluated at 10 and 14 days, using Western blotting. Statistical analysis, using ANOVA with post hoc Bonferroni test, revealed that human gingival fibroblasts from MCG showed similar results (p>0.05) for proliferation and viability as the cells cultured on CTRL. After 14 days, a significant decrease in COL 3A1 expression (p<0.05) was observed when cultured with the MCG. VIM expression showed no significant difference at any time period (p>0.05). Although no increase in extracellular matrix secretion was observed in this in vitro study, Mucograft(r) presented cellular compatibility, being an option for a scaffold whenever it is required.

In vitro effects of ascorbic acid and ß-glycerophosphate on human gingival fibroblast cells.

Ascorbic acid (AA) and ß-glycerophosphate (ßG) are considered in vitro osteogenic factors important to the differentiation of osteoblastic progenitor and dental pulp cells into mineralized tissue-forming cells. So, the present study investigated in vitro if these mineralizing inducible factors (AA and ßG) could influence differentiation of human gingival fibroblasts when compared with human pulp cells and osteogenic cells derived from rat calvaria cultured. The expression of osteopontin (OPN) and osteoadherin (OSAD) was analyzed by indirect immunofluorescence, immunocytochemistry as well as Western-blotting. In addition, the main ultrastructural aspects were also investigated. No mineralized matrix formation occurred on gingival fibroblasts induced with AA+ßG. On these cells, no expression of OPN and OSAD was observed when compared with pulp cells, pulp cells induced with AA+ßG as well as osteogenic cells. Ultrastructure analysis additionally showed that gingival fibroblasts exhibited typical fibroblast morphology with no nodule formation. The present findings showed that AA and ßG could not promote a mineralized cell differentiation of human gingival fibroblasts and confirm that human dental pulp cells, as the osteogenic cells, are capable to form a mineralized extracellular.

Microbiological Seal of Two Types of Tapered Implant Connections

Abstract Tapered implant connections have gained wide popularity for being more resistant to fatigue and for promoting a better seal against bacterial infiltration than conventional connections. The aim of this study was to evaluate the bacterial seal at the implant-abutment interface using two Morse taper implant models, by in vitro microbiological analysis. Eleven non-indexed and 11 indexed abutments were selected and connected to their respective implants with a 20 N torque, according to manufacturer's recommendation. Microbiological analysis was carried out using colonies of Escherichia coli transported directly from a culture dish to the prosthetic component. For control, one non-contaminated abutment-implant set from each group (negative control) and one contaminated implant with no abutment (positive control) were used. The specimens were immersed in BHI broth and maintained in an incubator at 37 °C for 14 days to assess the development of bacterial contamination. The results revealed that 36.4% (n=4) of the indexed components and 90.9% (n=10) of the non-indexed components allowed bacterial leakage, with significant difference between groups (p=0.0237). In conclusion, both tapered components failed to provide adequate sealing to bacterial leakage, although the indexed type components showed a superior seal compared with non-indexed components.

Resumo Conexões de implantes cônicos cresceram em popularidade por serem mais resistentes à fadiga e por promover uma melhor vedação contra infiltração bacteriana do que as conexões convencionais. O objetivo deste estudo foi avaliar o selamento bacteriano na interface implante-pilar utilizando dois modelos de implantes cone Morse, por meio de análise microbiológica in vitro. Onze pilares não indexados e 11 pilares indexados foram selecionados e conectados aos seus respectivos implantes com um torque de 20 N, de acordo com a recomendação do fabricante. A análise microbiológica foi realizada utilizando colônias de Escherichia coli retirados diretamente a partir de uma placa de cultura para o componente protético. Para os grupos de controle, foi utilizado um pilar-implante não contaminado de cada grupo (controle negativo) e um implante contaminado sem pilar (controle positivo). Os espécimes foram imersos em caldo BHI e mantidos numa incubadora a 37 °C durante 14 dias, para monitorar o desenvolvimento de contaminação bacteriana. Os resultados revelaram que 36,4% (n=4) dos componentes indexados e 90,9% (n=10) dos componentes não indexados obtiveram infiltração bacteriana, com diferença significativa entre os grupos (p=0,0237). Como conclusão, os dois componentes cônicos não conseguiram proporcionar uma vedação adequada contra infiltração bacteriana, embora os componentes do tipo indexados mostrassem uma vedação superior, quando comparados com componentes não indexados.

Evaluation of the Biological Behavior of Mucograft® in Human Gingival Fibroblasts: An In Vitro Study

Mucograft(r) is a resorbing porcine matrix composed of type I and type III collagen, used for soft tissue augmentation in guided tissue bony regeneration procedures. This in vitro study aimed to evaluate the biological behavior of Mucograft(r) in human gingival fibroblasts, as well as the ability of the matrix to induce production of extracellular matrix. Six resorbing Mucograft(r) matrices (MCG) were cut into 3 x 2 mm rectangles and 5 x 5 mm squares and were placed in 96- and 24-well plates, respectively. The control group (CTRL) consisted of cells plated on polystyrene without the MCG. After one, two, three and seven days, cell proliferation and viability were assessed using the Trypan exclusion method and MTT test, respectively. Type III collagen (COL 3A1) and vimentin (VIM) expression were also evaluated at 10 and 14 days, using Western blotting. Statistical analysis, using ANOVA with post hoc Bonferroni test, revealed that human gingival fibroblasts from MCG showed similar results (p>0.05) for proliferation and viability as the cells cultured on CTRL. After 14 days, a significant decrease in COL 3A1 expression (p<0.05) was observed when cultured with the MCG. VIM expression showed no significant difference at any time period (p>0.05). Although no increase in extracellular matrix secretion was observed in this in vitro study, Mucograft(r) presented cellular compatibility, being an option for a scaffold whenever it is required.

Resumo A Mucograft(r) é uma matriz reabsorvível, de origem suína, composta de colágenos do tipo I e III, utilizada para aumento de tecido mole em regeneração óssea guiada. Este estudo in vitro teve como objetivo avaliar o comportamento biológico da Mucograft(r), em fibroblastos gengivais humanos, bem como a indução da síntese de matriz extracelular. Seis matrizes reabsorvíveis de Mucograft(r) (MCG) foram cortadas em retângulos e quadrados medindo 3 x 2 mm e 5 x 5 mm e alocadas em placas de 96 e 24 poços, respectivamente. O grupo controle (CTRL) consistiu no plaqueamento celular em poliestireno, sem MCG. Após um, dois, três e sete dias, a proliferação e a viabilidade celular foram avaliadas utilizando o corante vital azul de Trypan e o teste MTT, respectivamente. Além disso, a expressão de colágeno tipo III (COL 3A1) e vimentina (VIM) foi avaliada após 10 e 14 dias, por meio de Western-blotting. Após análise estatística (Anova e pós teste de Bonferroni), pode-se observar que os fibroblastos gengivais humanos, cultivados sobre MCG, apresentaram proliferação e viabilidade semelhantes em comparação às células que foram cultivadas apenas no poliestireno (CTRL). Após 14 dias, notou-se uma diminuição significativa da expressão de COL 3A1 (p<0,05) quando as células foram cultivadas sobre a MCG. A expressão da VIM não mostrou diferença significativa em nenhum dos períodos estudados (p>0,05). No presente estudo in vitro pode-se concluir que apesar de não ter sido observado aumento da síntese de matriz extracelular, a Mucograft(r) apresentou compatibilidade celular, sendo uma opção de biomaterial em casos que o arcabouço é necessário.