Salivary pellicle composition and multispecies biofilm developed on titanium nitrided by cold plasma

Objective

The aim of this study was to evaluate the composition of the salivary pellicle (SP) and multispecies biofilm developed on titanium nitrided by cold plasma.

Methods

Titanium discs were allocated into a control group (Ti) and an experimental group (TiN – titanium-nitrided by cold plasma). The disc surface topography was characterized by scanning electron microscopy (SEM) and atomic force microscopy (AFM). The chemical composition of the disc surface was determined by X-ray photoelectron spectroscopy (XPS). Stimulated, clarified, and filtered saliva was used to form pellicles on the discs. Proteome analysis of the adsorbed SP proteins was performed by liquid chromatography–mass spectrometry (LC–MS). The surface free energy (SFE) was evaluated before and after SP formation. A multispecies biofilm composed of Actinomyces naeslundii, Streptococcus oralis, Streptococcus mutans, Fusobacterium nucleatum, Veillonella dispar, and Candida albicans was developed on the SP-coated discs. Viable microorganism counts were determined. The biomass and average thickness of biofilms were analyzed by confocal laser-scanning microscopy (CLSM) with COMSTAT software. The biofilm organization was visualized by SEM.

Results

The surface topography was similar in both groups. The SFE of the TiN group did not differ from that of the Ti group (p > 0.05), although the adsorption of pellicle proteins increased the SFE in both pellicle-coated groups (p < 0.001). Different proteins were identified on the Ti and TiN surfaces. The amount of biofilm was similar for both groups (p = 0.416), but the counts of F. nucleatum and S. oralis were higher in the TiN group (p < 0.001). Similar biofilms were characterized by the COMSTAT data, CLSM images, and SEM images.

Conclusion

The titanium nitrided by cold plasma exhibited differences in SP composition and multispecies microbial biofilm population compared to the control titanium surface.     

Surface properties of titanium and zirconia dental implant materials and their effect on bacterial adhesion

Objectives

Zirconia ceramic material has been widely used in implant dentistry. In this in vitro study the physiochemical properties of titanium and zirconia materials were investigated and the affinity of different bacteria to different materials was compared.

Methods

Disc samples with different surface states were used: polished partially stabilized zirconia (PZ), titanium blasted with zirconia (TBZ), titanium blasted with zirconia then acid etched (TBZA), and polished titanium (PT) as a control. Surface topography was examined using scanning electron microscopy and profilometry. Contact angle, surface free energy (SFE), surface microhardness and chemical composition were determined.Disc samples were separately incubated with Streptococcus mitis and Prevotella nigrescens, either with or without pre-coating with human saliva, for 6 h and the surface area covered by bacteria was calculated from fluorescence microscope images.

Results

PZ and TBZ exhibited lower surface free energy and lesser surface wettability than PT. Also, PZ and TBZ surfaces showed lower percentage of bacterial adhesion compared with control PT surface.

Conclusions

The zirconia material and titanium blasted with zirconia surface (TBZ surface) showed superior effect to titanium material in reducing the adhesion of the experimented bacteria especially after coating with saliva pellicle. Modifying titanium with zirconia lead to have the same surface properties of pure zirconia material in reducing bacterial adhesion.SFE appears to be the most important factors that determine initial bacterial adhesion to smooth surface.     

Biofilm formation of Candida albicans on implant overdenture materials and its removal

Objectives

The purposes of this study were to clarify the surface characteristics of various implant overdenture materials and the capabilities of Candida albicans adherence and biofilm formation on these surfaces, and to investigate the role of salivary mucin in biofilm formation.

Methods

Seven commonly used implant and restorative materials were assessed. The surface roughness averages of all materials were limited to 0.07–0.10 μm. Contact angles and salivary mucin absorption were measured. After 90-min initial adhesion and 2-day biofilm formation, the amounts of C. albicans were determined by counting colony-forming units and the morphological characteristics were observed by scanning electron microscopy (SEM). The effects of saliva coating and the influences of material surface property on initial adhesion, biofilm formation and its removability were analysed by univariate two-way analysis of variance and multiple linear regression analysis.

Results

Surface contact angle of materials, the index of hydrophobicity, was found to be correlated positively with initial adhesion and biofilm formation of C. albicans. A negative correlation between mucin absorption and removability of Candida biofilm indicates that mucin plays an important role in biofilm formation and its rigidity. SEM observation also revealed fewer Candida cells on saliva-coated Ti than on saliva-coated hydroxyapatite or acrylic resin.

Conclusions

The materials with different hydrophobic property and compositions display diverse manners of salivary mucin absorption, initial adhesion and biofilm formation. The hydrophobic materials encourage enhanced initial adhesion, subsequently resulting in the active biofilm formation. Mucin has decisive effects on Candida immobilization and biofilm development on the materials.

Clinical significance

Surface hydrophilic property and composition of materials and salivary proteins, especially mucin, affect the process of Candida biofilm formation and influence the amount and rigidity of formed biofilm. The present data may be applied as a reference for selecting materials in implant overdenture treatment from a microbiological point of view.     

Antifungal properties of the anti-hypertensive drug: Aliskiren

Objectives

Aliskiren, the first in a new class of orally active renin inhibitors, is licensed for the treatment of hypertension. It inhibits plasma renin activity directly, thereby reducing generation of angiotensin II. In this study, we have explored the anti-Candida properties of aliskiren.

Methods

Candida albicans was cultured in the presence or absence of aliskiren for various time periods. Subsequently, inhibition of growth, germtube formation, adhesion, early/matured biofilm development and secreted aspartic protease (SAP) activity were studied.

Results

When cultured in the presence of aliskiren, Candida showed significant reduction in the activity of aspartic proteases. Aliskiren impaired in vitro growth of C. albicans. It also affected two other virulence factors, germtube and adhesion. There is reduction in early and matured biofilm when treated with aliskiren.

Conclusions

Aliskiren could be considered as a candidate for antifungal drug development.     

Inhibition of microbial adhesion to plastic surface and human buccal epithelial cells by Rhodomyrtus tomentosa leaf extract

Objective

The adherence of oral pathogenic microorganisms to host tissues is the initial step for successful process of oral diseases. This study aimed to determine the effect of the Rhodomyrtus tomentosa leaf extract and rhodomyrtone, an antibacterial compound from R. tomentosa leaf, on adhesion of some oral pathogens to polystyrene plastic surface and human buccal epithelial cells.

Methods

The minimum inhibitory concentration (MIC) was evaluated using broth microdilution method. The microbial adhesion to the plastic surface and buccal cells was determined using microtiter plate method and microscopy technique.

Results

The ethanol extract of leaf demonstrated antibacterial activity against oral microorganisms including Staphylococcus aureus ATCC 25923, Streptococcus mutans (clinical isolate), and Candida albicans ATCC 90028 with the MIC values of 31.25, 15.62, and 1000 μg/ml, respectively. Rhodomyrtone displayed activity with the MIC values of 0.78 and 0.39 μg/ml against S. aureus ATCC 25923 and S. mutans, respectively. The MIC value of the compound against C. albicans ATCC 90028 was more than 100 μg/ml which was the highest test concentration. All pathogenic microorganisms treated with the extract and rhodomyrtone at their subinhibitory concentrations resulted in a decrease in their adherence ability to both plastic surface and buccal cells.

Conclusion

It is suggested that R. tomentosa extract and rhodomyrtone may be useful in therapy or as prophylaxis in infections involving oral pathogens.     

Parylene coating hinders Candida albicans adhesion to silicone elastomers and denture bases resin

Objective

To investigate whether parylene coatings over denture bases and silicone elastomers can effectively reduce Candida albicans adhesion and thus to decrease the incidence of denture stomatitis.

Design

Specimens of silicone elastomers A-2186 or lucitone 199 resin were prepared, and the measurements of contact angle, assay of XTT reduction and cell count of C. albicans adhesion were taken before and after parylene treatment. Furthermore, morphology of C. albicans adhesion for 48 h was observed by scanning electron microscope (SEM), and C. albicans adhesion for 4 h was illustrated by confocal scanning laser microscopy (CLSM) in combination with fluorescent dyes FUN-1 and Concanavalin A.

Result

There was a statistical difference between mean contact angles of silicone elastomer A-2186 before and after parylene coating (P < 0.05). The amount of C. albicans adhesion to the surface of silicone elastomer A-2186 and lucitone 199 resin after parylene treatment was significantly less than before parylene treatment by cells count and XTT reduction assay (P < 0.05). In SEM and CLSM analysis, C. albicans biofilm was more apt to generate on the surface of silicone elastomer A-2186 than other three groups, and more C. albicans aggregation formed on the surface of silicone elastomer A-2186 and lucitone 199 resin before parylene treatment than after parylene treatment.

Conclusion

Parylene coating reduced C. albicans adhesion and aggregation on the surface of silicone elastomer A-2186 and lucitone 199 resin, and improved the wettability of silicone elastomer A-2186.     

Effect of the secretory leucocyte proteinase inhibitor (SLPI) on Candida albicans biological processes: A therapeutic alternative?

Objectives

The aim of this study was to evaluate the effect of SLPI on the growth and biological processes of Candida albicans.

Methods

Two C. albicans strains were used in this study, a clinical isolate resistant to fluconazole (PRI) and a reference strain ATCC 24433. The minimal inhibitory concentration (MIC) was determined according to the CLSI methodology. The influence of SLPI on secreted serine proteinase activities (SSP) was measured by the cleavage of specific substrate, and surface hydrophobicity was determined by the aqueous-hydrocarbon biphasic separation method. Flow cytometry was performed to investigate receptors for SLPI and variations in the cell wall mannoprotein expression. Interaction between yeast and epithelium was assessed using the MA-104 cells lineage. Ultrastructure was analyzed by transmission electron microscopy (TEM).

Results

MIC values were calculated as 18 and 18.9 μM for the PRI and ATCC 24433, respectively. SSP activity was reduced by 48.8% by 18 μM of SLPI and cell surface hydrophobicity increased by 11.1%. Flow cytometry suggest the existence of SLPI binding sites on the surface of the yeast. Results showed a reduction in the expression of mannoproteins in 20.8% by the cells treated with 80 μM of SLPI, and 18 μM reduced the adhesion of yeasts to mammalian cells in 60.1%. TEM revealed ultrastructural changes in cells treated with 80 μM of SLPI, such as the presence of membrane-like structures within the cytoplasm.

Conclusions

SLPI exerts a significant influence on C. albicans viability and biological processes. Considering its constitutive and physiologic features, SLPI may become a promising tool for the development of new methodologies for the treatment and control of candidiasis.     

Biofilm-forming ability and adherence to poly-(methyl-methacrylate) acrylic resin materials of oral Candida albicans strains isolated from HIV positive subjects

PURPOSE

This study evaluated the adhesion to acrylic resin specimens and biofilm formation capability of Candida albicans strains isolated from HIV positive subjects'' oral rinse solutions.

MATERIALS AND METHODS

The material tested was a heat-cured acrylic resin (Acron Duo). Using the adhesion and crystal violet assays, 14 oral Candida albicans isolated from HIV-positive subjects and 2 references Candida strains (C. albicans ATCC 90028 and C. albicans ATCC 90128) were compared for their biofilm production and adhesion properties to acrylic surfaces in vitro.

RESULTS

There were no significant differences in adhesion (P=.52) and biofilm formation assays (P=.42) by statistical analysis with Mann-Whitney test.

CONCLUSION

Denture stomatitis and increased prevalence of candidal carriage in HIV infected patients is unlikely to be related to the biofilm formation and adhesion abilities of C. albicans to acrylic resin materials.     

Corrosion behaviour of titanium in the presence of Streptococcus mutans

Objective

The main aim of this in vitro study was to evaluate the influence of Streptococcus mutans on the corrosion of titanium.

Methods

S. mutans biofilms were formed on commercially pure titanium (CP-Ti) square samples (10 mm × 10 mm × 1 mm) using a culture medium enriched with sucrose. Open circuit potential (OCP) and electrochemical impedance spectroscopy (EIS) measurements were used to evaluate the corrosion behaviour of CP-Ti in the presence of S. mutans in Fusayama's artificial saliva. The corrosion of biofilm-free CP-Ti samples was also evaluated in artificial saliva. Biofilms biomass was measured by spectrophotometry, using crystal violet staining, after 1, 2 and 7 days.

Results

The OCP values recorded on CP-Ti in the presence of S. mutans (−0.3 ± 0.02 V vs. SCE) was lower than those on biofilm-free CP-Ti (−0.1 ± 0.01 V vs. SCE) after 2 h of immersion in artificial saliva (p < 0.05). That reveals a high reactivity of titanium in presence of S. mutans. Impedance spectra revealed the formation of a compact passive film on titanium in artificial saliva or in the presence of a 2 days old S. mutans biofilm even though the corrosion resistance of CP-Ti has decreased in presence of a S. mutans biofilm.

Conclusion

The presence of bacterial colonies, such as S. mutans, negatively affected the corrosion resistance of the titanium.     

Adherence in vitro of Candida albicans to plasma treated acrylic resin. Effect of plasma parameters, surface roughness and salivary pellicle

The adhesion of Candida albicans to surfaces is the prerequisite for occurrence of denture stomatitis.

Objective

Hence, this study investigated if surface modifications with plasma treatments could reduce the adherence of C. albicans to a denture base resin.

Methods

Specimens (n = 180) with roughened and smooth surfaces were made and divided into five groups: control—specimens were left untreated; experimental groups—specimens were submitted to plasma treatments to obtain surfaces with different hydrophobicity (Ar/50 W; ArO₂/70 W; AAt/130 W) or incorporation of fluorine (Ar/SF₆70 W). Contact angle measurements were performed immediately after the treatments and after immersion in water for 48 h. For each group, half of the specimens were incubated with saliva prior to the adhesion assay. The number of adherent yeasts was evaluated by XTT reduction method.

Results

For the experimental groups, there was significant change in the mean contact angle after 48 h of immersion in water. Groups ArO₂/70 W and ArSF₆/70 W showed significantly lower absorbance readings than the other groups, regardless the presence or absence of saliva and surface roughness.

Conclusions

Results demonstrated that ArO₂/70 W and ArSF₆/70 W plasma treatments showed promising potential for reducing the adherence of C. albicans to denture base resins.     

Bone tissue response to plasma-nitrided titanium implant surfaces

A current goal of dental implant research is the development of titanium (Ti) surfaces to improve osseointegration. Plasma nitriding treatments generate surfaces that favor osteoblast differentiation, a key event to the process of osteogenesis. Based on this, it is possible to hypothesize that plasma-nitrided Ti implants may positively impact osseointegration.

Objective

The aim of this study was to evaluate the in vivo bone response to Ti surfaces modified by plasma-nitriding treatments.

Material and Methods

Surface treatments consisted of 20% N₂ and 80% H₂, 450°C and 1.5 mbar during 1 h for planar and 3 h for hollow cathode. Untreated surface was used as control. Ten implants of each surface were placed into rabbit tibiae and 6 weeks post-implantation they were harvested for histological and histomorphometric analyses.

Results

Bone formation was observed in contact with all implants without statistically significant differences among the evaluated surfaces in terms of bone-to-implant contact, bone area between threads, and bone area within the mirror area.

Conclusion

Our results indicate that plasma nitriding treatments generate Ti implants that induce similar bone response to the untreated ones. Thus, as these treatments improve the physico-chemical properties of Ti without affecting its biocompatibility, they could be combined with modifications that favor bone formation in order to develop new implant surfaces.     

Antiadherent activity of Schinus terebinthifolius and Croton urucurana extracts on in vitro biofilm formation of Candida albicans and Streptococcus mutans

Objective

To evaluate the antiadherent property of crude, methanol and acetate methanol extract fractions from Schinus terebinthifolius and Croton urucurana in hydroalcoholic (HA) and dimethylsulfoxide (DMSO) solvents on in vitro biofilms formed by Streptococcus mutans and Candida albicans strains.

Design

The minimal concentration of adherence (MICA) was determined to evaluate the antiadherent potential of extracts on the in vitro biofilm formation. The extracts of plants were subjected to thin layer chromatography (TLC) in order to detect what class of compounds was responsible for the antiadherent activity. Data were estimated by analysis of variance (ANOVA) complemented by Tukey test level of significance set at 5%.

Results

Both plants demonstrated inhibition of S. mutans and C. albicans on in vitro biofilm formation. The biofilms of C. albicans were more efficiently inhibited by the S. terebinthifolius fraction of acetate–methanol and methanol in hydroalcoholic solvents (p < 0.05). The S. mutans biofilms adherence was best inhibited by the S. terebinthifolius crude extract and its methanolic fraction, both in hydroalcoholic solvent (p < 0.05). TLC of crude extracts and fractions of S. terebinthifolius detected the presence of several active compounds, including phenolic compounds, anthraquinones, terpenoids, and alkaloids. C. urucurana extracts confirmed activity for both microorganisms (p < 0.05). However, higher concentrations were needed to achieve antiadherent activity, mainly to inhibit in vitro biofilm formation of C. albicans.

Conclusion

The antiadherent potential of both plants on in vitro biofilms formed by C. albicans and S. mutans were confirmed, suggesting the importance of studies about these extracts for therapeutic prevention of oral diseases associated with oral biofilms.     

Human gingival fibroblast functions are stimulated by oxidized nano-structured titanium surfaces

Objectives

The aim of this study was to analyze the features of an oxidized titanium implant surface and to evaluate its effects on the response of human gingival fibroblasts.

Methods

10 mm × 10 mm × 1 mm turned (control) and oxidized (test) titanium samples (P.H.I. s.r.l., Italy) were examined by scanning electron microscopy and atomic force microscopy and characterized by height, spatial and hybrid roughness parameters. Primary cultures of human gingival fibroblasts were seeded on titanium samples, and cell morphology, adhesion, proliferation and extracellular matrix deposition, in terms of type I collagen synthesis, were evaluated.

Results

Control and test surfaces appeared considerably different at the microscopic analyses: turned samples were grooved, whereas oxidized surfaces showed a more complex micro- and nano-scaled texture, as evidenced by roughness parameters. Cell adhesion and proliferation rate, as well as collagen synthesis, were greater on oxidized vs turned surfaces.

Conclusions

Although both control and test samples were in the range of average roughness proper of smooth surfaces, they exhibited significantly different topographic properties in terms of height and, mostly, hybrid parameters. Furthermore, oxidized surfaces enhanced human gingival fibroblast adhesion, proliferation and extracellular matrix deposition, and this could be due to the different structure at micro- and nano-scale levels.

Clinical significance

Oxidized nanostructured titanium surfaces could have a significant clinical utilization in virtue of their affinity for soft tissue attachment at the implant neck and/or at the transmucosal portion of the prosthetic abutment.     

The role of phosphoinositide 3-kinase in adhesion of oral epithelial cells to titanium

Background

Oral epithelial cells (OECs) adhesion to titanium may improve the success rate of implant restoration.

Purpose

We investigated the mechanism by which OECs adhere to titanium dental implants.

Materials and methods

(1) After culturing rat OECs on titanium plates (Ti) or culture dishes in the presence or absence of a phosphoinositide 3-kinase (PI3K) activator or inhibitors and/or growth factors, and OEC morphology under these conditions were analyzed. (2) Right maxillary first molars were extracted and replaced with experimental implants. The rats were treated with or without growth factors.

Results

(1) Cell adherence was lower of OECs on Ti than in those on culture dishes, as were the levels of integrin β4 and the continuity of F-actin structures. After PI3K inhibition, markedly reducing adherence to both substrates. In contrast, PI3K activation with activator or insulin-like growth factor restored the OEC adherence and the expression of adhesion molecules on Ti to the levels seen in OECs cultured on dishes. Cell migration was inhibited by PI3K activation. (2) High expression of integrin β4 was observed in the peri-implant epithelia of PI3K-activated rats.

Conclusion

These findings suggest that PI3K plays an important role in the adhesion of OECs to Ti.     

Effect acidic and alkaline/heat treatments on the bond strength of different luting cements to commercially pure titanium

Objective

The purpose of this study was to characterize the effects of either acidic or combined alkaline/heat treatments on the surface of grit-blasted commercially pure (cp) titanium. The effects of the previous treatments on the shear bond strength (SBS) of cp titanium to conventional glass ionomer, resin-reinforced glass ionomer and self-adhesive resin luting cements were evaluated.

Methods

Titanium discs were machined and received one of the following treatments; grit-blasting (GB), grit-blasting followed either by etching in HNO₃/HF solution (GB/Ac) or by combined 5 M NaOH treatment/heat treatment at 600 °C for 1 h, then immersed for 24 h in SBF solution before cementation (GB/Ak). The treated surfaces were characterized by atomic force microscope (AFM), scanning electron microscope (SEM) and laser-induced brake-down spectroscopy (LIBS). Discs were cemented either by Fuji I, Fuji Plus or Rely X™ Unicem luting cements. The SBS was evaluated and the debonded discs were investigated by SEM.

Results

Two prominent results were revealed; first, GB/Ak treatment showed the highest SBS than the other treatments (P < 0.0001). Second, Rely X™ Unicem showed the highest SBS than the other cements (P < 0.0001). Fuji I and Fuji Plus showed predominant cohesive type of failure, whereas Rely X™ showed predominant adhesive type of failure.

Significance

Combined alkaline/heat treatments of commercially pure titanium surface shows to be of beneficial effect in enhancing SBS to glass ionomer, resin-modified glass ionomer and adhesive resin luting cements.     

Antifungal Activity of Endosequence Root Repair Material and Mineral Trioxide Aggregate

Introduction

The purpose of this study was to investigate the antifungal activity of Endosequence Root Repair Material (ERRM; Brasseler USA, Savannah, GA) as compared with mineral trioxide aggregate (MTA) using Candida albicans.

Methods

All materials were packed into sterilized intravenous tubing to obtain standardized samples and allowed to set for 3 or 24 hours and then exposed to a suspension of C. albicans for incubations of 24 or 48 hours. To analyze the mechanisms of the material's antifungal activity, additional samples of each test material were prepared in the same manner and allowed to set for 24 hours; these were then incubated in a culture medium for 24 hours. The pH of each conditioned media was measured before transferring to wells containing C. albicans. The development of biofilm was analyzed after 24 and 48 hours with 2,3-bis (2-methoxy-4-nitro-5-sulfophenyl)-5-([phenyl amino] carbonyl)-2H-tetrazolium hydroxide reduction assay.

Results

Materials in both experimental groups significantly limited biofilm formation at each interval (ie, 24 and 48 hours). After incubating for a 24-hour period in the presence of C. albicans, ERRM in both experimental groups showed a reduction in biofilm formation that was statistically significant in comparison with MTA. However, when set for 24 hours and incubated for 48 hours, gray MTA and white MTA showed a more substantial reduction in biofilm formation than comparable samples of ERRM. Cultured media conditioned with test materials showed statistically significant antifungal biofilm activity after 48 hours.

Conclusions

All materials tested have comparable antifungal biofilm activity. It appeared that changing the environment, such as the pH, contributed to this activity.     

An in vitro study of alginate oligomer therapies on oral biofilms

Objectives

The in vitro effect of a novel, oligosaccharide nanomedicine OligoG against oral pathogen-related biofilms, both alone and in the presence of the conventional anti-bacterial agent triclosan, was evaluated.

Methods

The effect of OligoG ± triclosan was assessed against established Streptococcus mutans and Porphyromonas gingivalis biofilms by bacterial counts and image analysis using LIVE/DEAD^® staining and atomic force microscopy (AFM). The effect of triclosan and OligoG surface pre-treatments on bacterial attachment to titanium and polymethylmethacrylate was also studied.

Results

OligoG potentiated the antimicrobial effect of triclosan, particularly when used in combination at 0.3% against S. mutans grown in artificial saliva. OligoG was less effective against established P. gingivalis biofilms. However, attachment of P. gingivalis, to titanium in particular, was significantly reduced after surface pre-treatment with OligoG and triclosan at 0.01% when compared to controls. Light microscopy and AFM showed that OligoG was biocidal to P. gingivalis, but not S. mutans.

Conclusions

OligoG and triclosan when used in combination produced an enhanced antimicrobial effect against two important oral pathogens and reduced bacterial attachment to dental materials such as titanium, even at reduced triclosan concentrations. Whilst the use of triclosan against oral bacteria has been widely documented, its synergistic use with OligoG described here, has not previously been reported. The use of lower concentrations of triclosan, if used in combination therapy with OligoG, could have environmental benefits.

Clinical importance

The potentiation of antimicrobial agents by naturally occurring oligomers such as OligoG may represent a novel, safe adjunct to conventional oral hygiene and periodontal therapy. The ability of OligoG to inhibit the growth and impair bacterial adherence highlights its potential in the management of peri-implantitis.     

In vivo monitoring of the bone healing process around different titanium alloy implant surfaces placed into fresh extraction sockets

Objectives

Increasing surface roughness and coating with tricalcium phosphate of titanium and titanium alloy implants has been proposed to provide better rates of osseointegration. However, how these changes in surface topography and chemistry influence the osseointegration process of immediate implants placed in fresh extraction sockets is unclear. This study investigated the influence of three clinically employed implant surfaces on the early bone healing events in vivo.

Methods

Machined smooth implants were milled from grade 5 Ti6Al4V titanium. Surfaces were moderately roughened by grit blasting, which were then coated with tricalcium phosphate. Implants were placed into freshly extracted incisor sockets of mandibles of normal Wistar rats and left for 1, 3 and 9 weeks. Healing bone tissue around the implants was examined by histochemistry and immunocytochemistry to localise PCNA proliferative cells, and osteoblast differentiation markers osteopontin and osteocalcin. Positive synthesising cells were counted using image analysis.

Results

Histology indicated no differences in the amount or pattern of bone formation within the healing tissue surrounding the different implant surfaces. Bone healing occurred predominantly on exposed bone surfaces (distance osteogenesis) and not on the implant surface (contact osteogenesis). No differences were observed in the number or timing of PCNA, osteopontin and osteocalcin positive cells within the bone healing tissue around each of the implant analysed.

Conclusion

For immediately placed implants, the surface modifications investigated appeared to have little influence on the activity of bone forming cells surrounding the implant, probably due to the high level of distance osteogenesis seen within this scenario.

Clinical significance

For immediate placement of implants into fresh extraction sockets, titanium implants with roughened surfaces and coating with tricalcium phosphate have negligible influence in accelerating the early bone healing events of osseointegration.     

Initial bacterial adhesion on resin, titanium and zirconia in vitro

PURPOSE

The aim of this in vitro study was to investigate the adhesion of initial colonizer, Streptococcus sanguis, on resin, titanium and zirconia under the same surface polishing condition.

MATERIALS AND METHODS

Specimens were prepared from Z-250, cp-Ti and 3Y-TZP and polished with 1 µm diamond paste. After coating with saliva, each specimen was incubated with Streptococcus sanguis. Scanning electron microscope, crystal violet staining and measurement of fluorescence intensity resulting from resazurin reduction were performed for quantifying the bacterial adhesion.

RESULTS

Surface of resin composite was significantly rougher than that of titanium and zirconia, although all tested specimens are classified as smooth. The resin specimens showed lower value of contact angle compared with titanium and zirconia specimens, and had hydrophilic surfaces. The result of scanning electron microscopy demonstrated that bound bacteria were more abundant on resin in comparison with titanium and zirconia. When total biofilm mass determined by crystal violet, absorbance value of resin was significantly higher than that of titanium or zirconia. The result of relative fluorescence intensities also demonstrated that the highest fluorescence intensity was found on the surface of resin. Absorbance value and fluorescence intensity on titanium was not significantly different from those on zirconia.

CONCLUSION

Resin specimens showed the roughest surface and have a significantly higher susceptibility to adhere Streptococcus sanguis than titanium and zirconia when surfaces of each specimen were polished under same condition. There was no significant difference in bacteria adhesion between titanium and zirconia in vitro.