Collagen-coated Hydroxyapatite Research Articles

Effect of pomegranate solution alone or combined with chlorhexidine against oral multispecies biofilm.

Natural bioactive products have been tested as alternative antimicrobial agents. This study evaluated the effect of Punica granatum extract (PGE) on oral multispecies biofilms. Lyophilized extracts from pomegranate peel were prepared, and the punicalagin content was assessed by ultra-performance liquid chromatography (UPLC). Oral multispecies biofilms from 2 donors were grown on four collagen-coated hydroxyapatite discs. After incubation for 7 days or 3 weeks, the biofilms were exposed to water (control), 2% CHX, 10% PGE, 20% PGE or 30% PGE for 3 min. The proportions of dead bacteria were assessed by the live/dead staining and confocal microscopy. After the analysis, the best PGE concentration (30%) was combined with CHX. The experimental phases were repeated using water, 2% CHX, 30% PGE and 30% PGE + 2% CHX. Five random areas of the biofilm on each disc were scanned, resulting in 20 scanned areas for each group. Regarding the biofilm volume, no differences were found amongst solutions (p = .111). The PGE solution killed bacteria effectively in 1-week, 2-week and 3-week-old-plaque biofilms, ranging from 37 to 55.3%, depending on the PGE concentration. The 30% PGE (a) (p = .0009) had greater antibiofilm effectiveness than 2% CHX (b), which killed bacteria in the 25.2 to 48.7% range. The 10% and 20% PGE had intermediate values (ab), without significant differences from 30% PGE (p = 1.002). Water (c) had the lowest proportion of dead bacteria (p < .00001) in a range of 5 to 6.7% and lower effectiveness in killing bacteria (p < .05). The PGE alone or mixed with 2% CHX had greater anti-biofilm effectiveness than CHX (p < .05). The old plaque biofilms were more resistant than the 7-day-old plaque (p < .05). The 30% PGE (alone or combined with CHX) exhibited a greater antibiofilm effect on oral multispecies biofilms grown on hydroxyapatite discs than 2% CHX.

Effects of Sodium Hypochlorite Concentration and Application Time on Bacteria in an Ex Vivo Polymicrobial Biofilm Model

IntroductionIn endodontic treatment, it is important to remove or inactivate biofilms in the root canal system. We investigated the effects of different concentrations and application times of sodium hypochlorite (NaOCl) on the viability of bacteria in ex vivo polymicrobial biofilms of different maturation levels. MethodsPolymicrobial biofilms were prepared from dental plaque samples and grown for 1, 2, and 3 weeks under anaerobic conditions on collagen-coated hydroxyapatite discs as an ex vivo biofilm model. The biofilms were then exposed to NaOCl at concentrations ranging from 0.1% to 2% for 1 or 3 minutes. The control group was exposed to sterile distilled water. Viability staining was performed and examined by confocal laser scanning microscopy to determine the percentage of biofilm bacteria killed by NaOCl. Scanning electron microscopy was also performed to visually examine the biofilms. ResultsApplication of NaOCl at 0.5%–2% for both 1 and 3 min killed significantly more bacteria when compared to the controls (P < .05). Cell viability tended to be lower after the application of NaOCl for 3 minutes than that for 1 minute. ConclusionsOur experiments using an ex vivo model showed that within the range of 0.1%–2% of NaOCl, higher NaOCl concentrations and longer application times were more effective in killing biofilm bacteria, and that mature biofilms were more resistant to NaOCl than younger biofilms.

Recovery of Oral In Vitro Biofilms after Exposure to Peptides and Chlorhexidine

IntroductionThis study aimed to examine the dynamic recovery of established multispecies biofilms of oral bacteria after an initial treatment by D-enantiomeric peptide DJK-5, L-enantiomeric peptide 1018, or chlorhexidine digluconate (CHX). MethodsOral biofilms from 2 donors were grown on collagen-coated hydroxyapatite disks for 3 weeks and exposed to DJK-5, 1018, and 2% CHX for 3 minutes. Immediately after treatment and 1, 2, 3, 5, 7, 8, and 12 weeks after exposure, the biofilm volume and the volume ratio of dead and live bacteria in biofilms were assessed by confocal laser scanning microscopy using a live/dead viability stain. Results were examined by 1-way analysis of variance and post hoc multiple comparisons to determine significance at a P < .05 significance level. ResultsDJK-5 killed almost 80% of biofilms in 3 minutes and maintained this high level of dead bacteria for 1 week. The proportion of viable bacteria in DJK-5–treated biofilms returned to the pretreatment level after 12 weeks. The biovolume of DJK-5–treated biofilm remained significantly lower than that of biofilms after CHX and no treatment throughout the 12-week follow-up period (P < .001). The proportion of dead bacteria was higher in biofilms exposed to DJK-5 than with 1018 or CHX for 8 weeks after the exposure (P < .001). The proportion of dead bacteria almost doubled to 46%–52% during the first 7 days after the 3-minute exposure to CHX and peptide 1018. The timeline of biofilm recovery was slow but similar after exposure to CHX and the 2 peptides. Conclusionsecovery time after exposure to DJK-5 was longer than that after exposure to 1018 and CHX. Peptide 1018 showed a delayed, continued antibacterial effect similar to that of 2% CHX against the biofilm microbes.

Dynamics of Dissolution, Killing, and Inhibition of Dental Plaque Biofilm.

The present study aims to establish a standardized model that makes it possible to evaluate the dynamic dissolution of biofilm, killing of biofilm microbes and inhibition of growth of biofilm by disinfecting solutions. Biofilm was grown from dental plaque bacteria on collagen-coated hydroxyapatite (HA) disks for 3 days or 3 weeks under anaerobic conditions. Biofilms were stained with the LIVE/DEAD viability stain and subjected to sterile water, 2% sodium hypochlorite (NaOCl), 6% NaOCl, or 2% chlorhexidine (CHX) for 32 min. Dynamic change in fluorescence on bacterial cells and extracellular polymeric substance (EPS) during the exposure was analyzed using Alexa Fluor 647-labeled dextran conjugate and a live-cell imaging confocal laser scanning microscopy (LC-CLSM). The biofilm structures after treatments were visualized by scanning electron microscopy (SEM). The treated biofilms on HA disks were collected and subjected to colony forming unit (CFU) counting. Another set of sterile HA disks were coated with CHX prior to the monitoring of plaque biofilm growth for 12 h. The LC-CLSM results showed that NaOCl dissolved biofilm effectively, more so at a higher concentration and longer exposure time. Six percent NaOCl was the most effective at dissolving and killing bacteria (e.g., 99% bacterial reduction in 3-day-old biofilm and 95% bacterial reduction in 3-week-old biofilm in 32 min) followed by 2% NaOCl and CHX. Sodium hypochlorite dissolved over 99.9% of the EPS whereas CHX only slightly reduced the EPS biovolume in 32 min. CFU results indicated that the dispersed biofilm bacteria are more resistant than planktonic bacteria to disinfectants. SEM showed the disruption of biofilm after exposures to CHX and NaOCl. The use of 2% CHX and sterile water did not result in biofilm dissolution. However, prior exposure of the HA disks to 2 and 0.2% CHX for 3 min prevented biofilm from growing on the HA disk surfaces for at least 12 h. This new platform has the potential to aid in a better understanding of the antibiofilm properties of oral disinfectants.

Regulation of periodontal ligament-derived cells by type III collagen-coated hydroxyapatite.

The periodontal ligament (PDL), which maintains homeostasis in the periodontium, is a group of specialized connective tissue fibers attached to both the cementum and alveolar bone. Regeneration of periodontium with PDL cells has been investigated, and the chemical and molecular structures of scaffolds control the adhesion and differentiation of cells. Therefore, the development of adequate materials for PDL-derived cells is essential to regenerate the periodontium. We evaluated the suitable passage time for PDL-derived cells and investigated the behaviors of PDL-derived cells grown on hydroxyapatite (HAp) scaffolds coated with type I and type III collagen. PDL-derived cells were isolated with enzyme from the upper molars of male Wister rats. After characterization of HAp, type I collagen, and type III collagen, PDL-derived cells at passage 2 were seeded onto collagen-coated HAp. Cell adhesion, proliferative potential, and osteoconductivity were analyzed with immunostaining, 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide assays, Alizarin S staining, and real-time polymerase chain reaction. Type I and III collagens were successfully coated on HAp. Gene expression analysis revealed that passage 2 was suitable for maintaining differentiation potential. Proliferative potential and cell adhesion were significantly higher on type III collagen than on HAp alone or type I collagen. In contrast, the osteoconductivity of type III collagen was significantly lower than those of HAp and type I collagen. PDL-derived cells on type I collagen differentiated into osteogenic cells and formed hard tissues. However, type III collagen enhanced the adhesion of PDL-derived cells and inhibited mineralization.

Antibiofilm Effect of D-enantiomeric Peptide Alone and Combined with EDTA In Vitro

IntroductionThe aim of this study was to evaluate the effect of DJK-5, a newly developed cationic antimicrobial peptide, on oral multispecies and Enterococcus faecalis biofilms alone or combined with the endodontic chelating agent EDTA in vitro. MethodsOral multispecies biofilms from 2 donors and E. faecalis VP3-181 biofilm were grown on collagen-coated hydroxyapatite disks. After incubation for 3 days or 3 weeks, the biofilms were exposed to sterile saline (negative control), 8.5% EDTA, 2% chlorhexidine digluconate (CHX), 5 μg/mL DJK-5, 10 μg/mL DJK-5, a mixture of 5 μg/mL DJK-5 and 8.5% EDTA (final concentration), or a mixture of 10 μg/mL DJK-5 and 8.5% EDTA, all for 1 and 3 minutes. The proportions of dead bacteria in the biofilms were assessed by the LIVE/DEAD staining (Thermo Fisher Scientific, Waltham, MA) and confocal microscopy. ResultsThe peptide DJK-5 rapidly killed most bacteria in all biofilms, with significant differences to the control, 8.5% EDTA and 2% CHX (P < .01). Basically, a higher DJK-5 concentration and longer exposure (3 minutes) were more effective than a low concentration and short time exposure (P < .05). There were no significant differences in antibiofilm activities between DJK-5 used alone or in the mixture with 8.5% EDTA at either concentration. EDTA (8.5%) had no significant antimicrobial effect compared with the negative control (P > .05), but, unlike DJK-5 alone, the mixture retained the ability to remove smear layers. In peptide groups, there were no significant differences in dead bacteria proportions between 3-day and 3-week biofilms, except for 10 μg/mL DJK-5 used alone for 3 minutes on the multispecies biofilms. ConclusionsDJK-5 exerted antibiofilm ability on E. faecalis and oral multispecies biofilms grown on hydroxyapatite disks, both alone and when combined with 8.5% EDTA.

Comparing mechanical properties of silk-coated and collagen-coated hydroxyapatite scaffolds

Comparing mechanical properties of silk-coated and collagen-coated hydroxyapatite scaffolds

Effect of the Source of Biofilm Bacteria, Level of Biofilm Maturation, and Type of Disinfecting Agent on the Susceptibility of Biofilm Bacteria to Antibacterial Agents

IntroductionBiofilm development is a dynamic process that begins with the initial attachment of planktonic bacteria to a surface, eventually leading through different stages to a mature, structurally complex biofilm. The aim of this study was to assess the effect of the source of biofilm bacteria, the level of biofilm maturation, and the type of disinfecting agent on the susceptibility of biofilm bacteria to antibacterial agents. MethodsMultispecies biofilms from plaque bacteria of 6 donors were grown for up to 8 weeks on collagen-coated hydroxyapatite disks. After 1, 2, 3, 4, and 8 weeks of growth the biofilms were exposed to 1% sodium hypochlorite, 0.2/0.4% iodine-potassium iodide, and 2% chlorhexidine for 1 and 3 minutes. The percentage of killed biofilm bacteria was determined by using LIVE/DEAD viability staining and confocal laser scanning microscopy. One-way analysis of variance was used for statistical analysis. ResultsOne- and 2-week-old biofilms were moderately or very sensitive to the tested disinfecting agents, which killed 20%–100% of the biofilm bacteria. After 3 weeks of growth the biofilm bacteria were more resistant to the same agents, and only 10%–30% of the bacteria were killed (P < .001). The same pattern of the effect of biofilm age (maturation) on the resistance of bacteria was observed in all 6 biofilms and with all 3 disinfecting agents. ConclusionThe change of biofilm bacteria from sensitive to resistant against disinfecting agents occurred between 2 and 3 weeks of biofilm maturation. This development took place simultaneously in all biofilms grown from plaque bacteria from 6 different donors and was independent of the type of disinfecting agent used. The results emphasize the importance of knowing the maturation timeline of each biofilm model used to test the effectiveness of endodontic disinfecting agents against biofilm bacteria.

In vitro antibacterial effect of carbamide peroxide on oral biofilm

This study compared the effects of carbamide peroxide (CP) and chlorhexidine (CHX) on oral biofilm in vitro. Collagen-coated hydroxyapatite discs were inoculated with subgingival plaque. After 3 weeks, the emergent biofilms were subjected to 1-, 3-, and 10-min exposures of a 1% CHX gel, a 5% CP gel and rinse, and a 10% CP gel and rinse. Subsequently, the biofilms were stained using a two-colour fluorescent dye kit for confocal laser scanning microscopy, and the volume ratio of dead bacteria to all bacteria was analysed. Compared to a non-treated gel control, the active agents killed bacteria on all the discs, with higher concentration and longer exposure times killing more bacteria. The rinse form disrupted the biofilm quicker than the gel form. Overall, 10% CP showed more disruption of biofilm and a greater proportion of killed bacteria than 1% CHX (p<0.05).

Antibacterial and smear layer removal ability of a novel irrigant, QMiX

To assess in a laboratory experimental model the efficacy of a novel root canal irrigant, QMiX, against Enterococcus faecalis and mixed plaque bacteria in planktonic phase and biofilms. In addition, its ability to remove smear layer was examined. Enterococcus faecalis and mixed plaque bacteria were exposed to QMiX, 2% chlorhexidine (CHX), MTAD and 1% sodium hypochlorite (NaOCl) for 5 s, 30 s and 3 min. Following exposure, samples were taken, serially diluted and grown aerobically and anaerobically on tryptic soy agar (TSA) plates or on blood agar plates for 24 and 72 h, respectively, to measure killing of bacteria. E. faecalis and plaque biofilms were grown for 3 weeks on collagen-coated hydroxyapatite or dentine discs and exposed for 1 and 3 min to QMiX, 2% CHX, MTAD, 1% and 2% NaOCl. The amount of killed bacteria in biofilms was analysed by confocal laser scanning microscopy using viability staining. Dentine blocks were exposed to QMiX and 17% EDTA for 5 min. The effectiveness of smear layer removal by the solution was evaluated using scanning electron microscopy. For statistical analysis, one-way analysis of variance and comparison of two proportions were used. QMiX and 1% NaOCl killed all planktonic E. faecalis and plaque bacteria in 5 s, while 2% CHX and MTAD were unable to kill all plaque bacteria in 30 s, and some E. faecalis cells survived even 3 min of exposure. QMiX and 2% NaOCl killed up to 12 times more biofilm bacteria than 1% NaOCl (P < 0.01), 2% CHX (P < 0.05; P < 0.001) and MTAD (P < 0.05; P < 0.001). QMiX removed smear layer equally well as EDTA (P = 0.18 × 10(-5)). QMiX and NaOCl were superior to CHX and MTAD under laboratory conditions in killing E. faecalis and plaque bacteria in planktonic and biofilm culture. Ability to remove smear layer by QMiX was comparable to EDTA.

Antimicrobial Efficacy of Chlorhexidine against Bacteria in Biofilms at Different Stages of Development

Introduction Detailed knowledge on the nature of the physiological and metabolic phases of biofilm development is important in combating resistant, disease-associated biofilms. The aim of this study was to examine the susceptibility of multispecies biofilms at different phases of growth to root canal irrigants. Methods The multispecies biofilms were grown from plaque bacteria on collagen-coated hydroxyapatite discs in brain-heart infusion broth for time periods ranging from 2 days to several months. Fresh nutrients were added weekly for the first 3 weeks, followed by a nutrient deprivation phase, by adding fresh brain-heart infusion broth medium only once a month. Biofilms of different age were subjected to 1-, 3-, or 10-minute exposure to 2% chlorhexidine (CHX) or CHX-Plus. After treatment, the volume ratio of dead bacteria in biofilms was assessed by confocal laser scanning microscopy by using a LIVE/DEAD viability stain. Biofilm structure was visualized by scanning electron microscopy. Results The thickness of biofilms increased from 57 μm (2 days) to 155 μm (3 weeks) during biofilm development. It reached a steady state under nutrient-limiting conditions, with thickness of 190 μm (6 weeks) to 201 μm (12 weeks). The proportion of killed bacteria in mature biofilms (3 weeks) was lower than in young biofilms (2 days, 1 and 2 weeks) after treatment with both CHX products ( P < .01).The resistance of mature biofilms under the nutrient-limiting phase (6–12 weeks) to CHX remained stable and was similar to 3-week-old biofilm. However, treatment with CHX-Plus for 3 and 10 minutes did not lose effectiveness against biofilm bacteria in mature and nutrient-limited phases. CHX-Plus showed higher levels of bactericidal activity at all exposure times than 2% CHX ( P < .01). Conclusions Bacteria in mature biofilms and nutrient-limited biofilms are more resistant to CHX killing than in young biofilms. The results emphasize the importance of standardization of factors such as biofilm age when studying the comparative effectiveness of disinfecting agents against biofilm bacteria.

Bacterial Viability in Starved and Revitalized Biofilms: Comparison of Viability Staining and Direct Culture

Objectives The aim of this study was to enumerate viable bacteria at different growth stages of a multispecies oral biofilm and to compare results obtained with the LIVE/DEAD BacLight Kit (Molecular Probes, Eugene, OR) with those from culturing and plate counting (colony-forming unit counts [CFUs]). Methods The multispecies biofilm was grown from plaque bacteria on collagen-coated hydroxyapatite disks in brain-heart infusion broth for 3 weeks (phase І) with a weekly addition of new nutrients. This was followed by a 9-week nutrient-deprivation phase (phase ІІ); after which, the biofilm was reactived again by weekly additions of fresh BHI medium for 4 weeks (phase ІІІ). The number and proportion of live bacteria in biofilm was assessed by culturing and by confocal laser scanning microscopy using a LIVE/DEAD viability stain throughout the experiment. Results The CFU counts dropped more than four logarithmic steps during phase ІІ. However, viability staining by LIVE/DEAD stain indicated only a 25% drop in viability. The CFU counts increased during phase III, but it took 4 weeks for them to return close to the original CFU numbers. Cell viability, as indicated by the staining, improved from 75% close to the original 100%. Conclusions Bacteria in the multispecies biofilm grown under nutrient deprivation became viable but nonculturable but could be brought back to a culturable state after reestablishing sufficient access to nutrients. The results indicate that viability staining better reflected true viability of the biofilm bacteria than culturing during the long starvation phase. The result of this study may have an impact on the interpretation of cultural studies on root canal microbiology/biofilms in vivo.

The Synergistic Antimicrobial Effect by Mechanical Agitation and Two Chlorhexidine Preparations on Biofilm Bacteria

Introduction Irrigation of the root canal with antibacterial solutions is considered an essential part of root canal treatment in endodontics. The purpose of this study was to investigate whether mechanical agitation (ultrasonic or sonic) improves the effectiveness of chlorhexidine against biofilm bacteria in vitro. Methods Collagen-coated hydroxyapatite (CHA) disks were exposed to dispersed subgingival plaque for 3 weeks at 37°C. The multispecies biofilms established were subjected for 1 and 3 minutes to CHX-Plus (Vista Dental Products, Racine, WI) and 2% chlorhexidine (CHX), with or without mechanical agitation. After treatment, the amount of dead bacteria in biofilms was analyzed by viability staining and confocal laser scanning microscopy (CLSM). The morphology of biofilms, with or without mechanical agitation, was also examined by CLSM. Results The structure of the biofilm did not show any obvious change when the solutions surrounding the biofilm were exposed to continuous ultrasonic or sonic agitation. The combined use of mechanical agitation and chlorhexidine had a more pronounced antimicrobial effect against the biofilms than either one alone. Sonic activation (EndoActivator; Advanced Endodontics, Santa Barbara, CA) showed the highest levels of bactericidal activity with CHX-Plus after both exposure times. The proportion of killed bacteria also depended on the type of irrigant ( p < 0.001) and the time of exposure ( p < 0.001). Conclusions The low-intensity ultrasonic or sonic agitation that does not disrupt biofilm or disperse the biofilm bacteria improves the action of disinfectants against biofilm bacteria.

Evaluation of the Effect of Two Chlorhexidine Preparations on Biofilm Bacteria In Vitro: A Three-Dimensional Quantitative Analysis

Introduction Microorganisms are essential in the development of periradicular diseases and are the major causative factors associated with endodontic treatment failures. Microbial biofilms are communities of bacteria that attach to surfaces and form heterogeneous three-dimensional structures. The purpose of this study was to develop a biofilm model that closely mimicked in vivo biofilm and to determine its susceptibility to endodontic antimicrobial irrigants by three-dimensional quantitative analysis. Methods Collagen-coated hydroxyapatite (C-HA) and uncoated hydroxyapatite (HA) disks were inoculated with dispersed subgingival plaque for 3 weeks. Thick biofilms rich in spirochetes were formed on both substrates. Biofilms were subjected to 1-, 3-, and 10-minute exposures to CHX-Plus (Vista Dental Products, Racine, WI) and 2% chlorhexidine (CHX). After treatment, the volume ratio of dead bacteria to all bacteria in biofilms, indicated by the ratio of red and (red + green) fluorescence, was analyzed by confocal laser scanning microscopy for each medicament. Results The proportion of killed bacteria was depended on the type of irrigant and the time of exposure in both C-HA and HA biofilm models (p = 0.00). CHX-Plus showed higher levels of bactericidal activity at all exposure times than 2% CHX (p < 0.001). The C-HA biofilm was thicker than the HA biofilm. Less bacteria were killed in C-HA biofilm than in the HA model. Conclusions This multispecies biofilm model and quantitative analysis methodology may be useful for the evaluation of the antimicrobial effectiveness of endodontic disinfecting agents.

Comparison of mesenchymal stem cell and osteosarcoma cell adhesion to hydroxyapatite

Immortalized cells are often used to model the behavior of osteogenic cells on orthopaedic and dental biomaterials. In the current study we compared the adhesive behavior of two osteosarcoma cell lines, MG-63 and Saos-2, with that of mesenchymal stem cells (MSCs) on hydroxyapatite (HA). It was found that osteosarcoma cells demonstrated maximal binding to fibronectin-coated HA, while MSCs alternately preferred HA coated with collagen-I. Interesting, the binding of MG-63 and Saos-2 cells to fibronectin was mediated by both alpha5 and alphav-containing integrin heterodimers, whereas only alphav integrins were used by MSCs. Cell spreading was also markedly different for the three cell types. Osteosarcoma cells exhibited optimal spreading on fibronectin, but poor spreading on HA disks coated with fetal bovine serum. In contrast, MSCs spread very well on serum-coated surfaces, but less extensively on fibronectin. Finally, we evaluated integrin expression and found that MSCs have higher levels of alpha2 integrin subunits relative to MG-63 or Saos-2 cells, which may explain the enhanced adhesion of MSCs on collagen-coated HA. Collectively our results suggest that osteosarcoma cells utilize different mechanisms than MSCs during initial attachment to protein-coated HA, thereby calling into question the suitability of these cell lines as in vitro models for cell/biomaterial interactions.

乳突蜂巣構造の再生―Ｉｎ ｓｉｔｕ ｔｉｓｓｕｅ ｅｎｇｉｎｅｅｒｉｎｇの臨床応用―

The aim of this study was to regenerate the pneumatic air cells and their gas exchange function in the poorly developed mastoid cavities of patients with chronic otitis media.Five patients with severe chronic otitis media whose mastoid air cells were poorly developed took part in this clinical trial. Four of 5 patients underwent staged operation of tympanoplasty.Honeycomb-like structures made of hydroxyapatite (HA) coated with collagen was used as a framework for artificial pneumatic bones. At the first stage of tympanoplasty, collagen-coated HA was implanted into the newly opened mastoid cavity and was fixed by fibrin glue. After the first operation, recovery of mastoid aeration and regeneration of the pneumatic air cells of the newly opened mastoid cavity were assessed on CT scan images. In 4 of 5 cases, aeration was recovered. The pneumatic air cells were regenerated in 3 cases.This study demonstrated that the mastoid air cells could be regenerated with implanted HA in the newly opened mastoid cavity. This tissue engineering method may be a possible treatment for intractable otitis media because it can recover the gas exchange function.

A NOVEL COLLAGEN-COATED HYDROXYAPATITE IMPLANTS FOR REGENERATION OF PERIODONTAL TISSUE

A) To address the inability of present artificial implants in previous studies by the authors, a functional periodontium was successfully regenerated using a processed allo-tooth implant. In the present study, to induce similar regeneration, the authors have attempted to promote regeneration of periodontal tissue using a collagen-coated hydroxyapatite (HA) implant in a dog model. B)Implants were produced by wrapping hollow cylinders of porous HA (1=10mm, d0=3mm, d1=1mm, porosity=54%) in collagen, and applying a 24-hour cross-linking treatment at 120°C. Ten implants were placed in the extraction sites of five beagle dogs to evaluate their clinical effectiveness. Three months post-operatively, light microscopic analysis was employed to evaluate the regenerated tissue around the implants histopathologically. C) Three months post-operatively, all implants remained firmly attached at their implantation sites. Microscopic analysis revealed periodontal fiber tissue attached to the implants oriented perpendicular to the implant surface in seven cases. Regeneration of the cementum was also observed on the implant surface in eight cases. Such results show that periodontal tissue can be successfully regenerated at extraction sites using collagen-coated hydroxyapatite implants.