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Background: Nowadays different materials are being used in alveolar bone reconstruction surgeries. Dentin is one of the biomaterials has drawn attention in recent years, but the results of studies are inconsistent. Aim: The aim of this study was to investigate osteoinduction capability of demineralized human derived-dentin particles implanted into muscular tissue. Material and Methods: The present experimental study was carried out on adult Rats (8 weeks old,200-250 gram). Demineralized human dentin (DHD) was implanted (100mg) in latissimus dorsi muscle under the deep anesthesia. At the end of one, second and fourth months, tissue samples were removed and stained with H&E. Result: At the end first month, the particles were enclosed with connective tissue. Multinucleated giant osteoclast attached to the DHD particle, capillaries and differentiating cells in vicinity of particles less than 250 µm were found. Fibroblasts and differentiating cells around the scalloped borders of the large dentin particles (> 850µm) were found. At the end of second month differentiating cells from deeper layer of collagenous capsule, young osteoblast and osteoid deposition adjacent and between the particles (250 µm) were seen. At the end of fourth month capillaries, differentiating cells, osteoid formation and osteoblasts were also found in vicinity of the ruffled margin of the large particles. Young osteoblasts and fibroblasts were observed in dentin niches. Quantification of new bone formation showed that meaningful difference between the 120 days (45±3 µm²), 60 days (23±5 µm²) and 30 days (0) (p<0.05). Conclusion: Our results suggest that demineralized human dentin particles less than 250 µm induce osteoinduction two month after implantation. Larger particles (>850µm) showed limited osteoinduction only in ruffled margins and dentin artifactal niches after four months. Additionally bone formation proceeded at higher rate after 120 days. [ABSTRACT FROM AUTHOR]

Nongmahir reservoir of Meghalaya state of northeast India (NEI), sampled at the littoral and limnetic regions, revealed fairly biodiverse zooplankton of total 56 species with peak consortium (52 species) in January collection from the littoral region. The richness indicated spatial monthly variations and heterogeneity at the two regions mainly influenced by Rotifera. The ‘soft and de-mineralized waters’ resulted in low zooplankton abundance. Copepoda > Rotifera with Cyclopidae > Brachionidae influenced zooplankton, and Mesocyclops leuckarti > Keratella cochlearis > Ascomorpha ovalis > Microcyclops hyalinus are notable species at the littoral region. The limnetic region recorded Rotifera dominance, and importance of Brachionidae > Cyclopidae and K. cochlearis > Conochilus unicornis >M. leuckarti >A. ovalis > Asplanchna priodonta > Polyarthra vulgaris. Zooplankton recorded moderate species diversity and notable differences of evenness and dominance. The spatial monthly differences of richness, abundance and diversity indices of zooplankton, and importance of notable taxa are hypothesised to habitat heterogeneity of the two regions. Our results also indicated limited and differential influence of individual abiotic factors on zooplankton taxa, while the canonical correspondence analysis registered high cumulative influence of 10 abiotic factors on the littoral (80.62%) and limnetic (74.79%) assemblages along axis 1 and 2. This study highlighted distinct temporal variations of different diversity parameters than our preliminary survey of June 1995–May 1996.

We evaluated the effect of phytic acid on matrix metalloproteinase (MMP)‐ or cysteine cathepsin (CC)‐mediated dentin degradation. Demineralized dentin beams were divided into five groups (n = 12) and treated with 1%, 2%, or 3% phytic acid or with 37% phosphoric acid. Untreated demineralized beams served as controls. After incubation for 1 or 3 wk, dry mass loss was determined and aliquots of incubation media were analysed for cross‐linked telopeptide of type I collagen (ICTP) fragments for MMP‐mediated and c‐terminal telopeptide of type I collagen (CTX) for cathepsin‐k‐mediated degradation. The direct effect of phytic acid was evaluated using MMP activity assay. Data were analysed using repeated‐measures anova. ICTP releases with 1% and 2% phytic acid treatment were statistically significantly lower than those following phosphoric acid treatment at 3 wk. The CTX release for phytic acid‐treated beams at 3 wk was not significantly different from that of untreated control beams, but it was significantly lower than that of phosphoric acid‐treated beams. Their MMP activities at 3 wk were not significantly different from those of the controls but they were significantly lower than those seen for phosphoric acid‐treated beams. Compared to phosphoric acid, phytic acid treatment resulted in a reduced dentinal host‐derived endogenous enzymatic activity and collagen degradation. [ABSTRACT FROM AUTHOR]

To evaluate the possibility of regenerating bone around endosseous dental implants, 3t implants were placed into postextraction sockets or other bony defects, and human demineralized freeze-dried cortical bone powder (DFDB) mixed with tetracycline was packed around the exposed parts. Implants were covered with expanded polytetrafluoroethylene (e-PTFE) membranes for 4 to 6 months until abutment connection, unless the membranes were prematurely exposed and had to be removed. Bone biopsies from nonsupporting regenerated bone were taken from some of the patients and examined histologically. Whenever complete coverage was maintained throughout the healing period (4 to 6 months), complete bone regeneration resulted. Early membrane removal mainly resulted in partial bone regeneration. Histologically, regenerated bone consisted of particles of devitalized bone in contact with newly formed woven or lamellar bone with some connective tissue around them. Osteogenic activity was even present 1 year post-grafting. Thus, DFDB is capable of promoting bone formation around dental implants if complete flap coverage and the membrane presence can be maintained throughout the healing phase. [ABSTRACT FROM AUTHOR]

Aim: The present study was conducted to evaluate the efficacy of human dentine grafts for new bone augmentation. Materials & methods: Dentine grafts (demineralized dentine matrix [DDM] and mineralized dentine matrix [MDM]) were prepared and implanted in rats. Tetracycline was administered twice. Paraffin and resin sections were prepared from the harvested grafts and stained respectively with hematoxylin and eosin (in addition to tartrate acid phosphatase for osteoclasts) and Villanueva. The new bone formation (bone thickness, mineral apposition rate and the bone formation rate) was analyzed in tetracycline-labeled resin sections. Results & conclusion: DDM grafts implanted in bone were better able to augment the bone compared to MDM grafts. However, both MDM and DDM failed to induce new bone in ectopic site, they could be considered as alternative autograft substitutes after protocol optimization. [ABSTRACT FROM AUTHOR]

Due to the extensive use of bone allografts in bone reconstruction and periodontal therapy as suitable alternatives to autografts, they are now marketed under different commercial brands. Considering the controversial reports regarding the osteoinductive properties of bone allografts, this study sought to assess the effect of type (mineralized/demineralized), amount and particle size of several allografts on the proliferation and differentiation of MG-63 osteoblast-like cells. MG-63 cells (24-h culture) were exposed to 20 and 40 mg amounts of nine different commercially available freeze-dried bone allografts. After 24 and 72 h of incubation, the effect of water-soluble allograft released materials on cell viability and proliferation was assessed using methyl thiazol tetrazolium (MTT) assay after 24 and 72 h of exposure. Cell differentiation and mineralization was assessed by real-time quantitative reverse transcription PCR and alizarin red staining after 72 h of exposure. The amount and particle size of understudy allografts had significant effects on cell viability after 24 h of exposure (in contrast to 72 h). Higher rate of proliferation was seen in non-differentiated or slow-differentiated groups. The amount and particle size factors had no significant effect on the amount of calcified nodules or the expression of osteogenic marker genes in most groups. Faster and more distinct differentiation and mineralization was noted in mineralized compared to demineralized groups during the 3-day study period. Based on the results, the understudy mineralized (non-demineralized) bone allografts had greater effect on osteogenic differentiation of the MG-63 cells and showed more in vitro osteoinductive activity compared to partially demineralized and fully demineralized types. [ABSTRACT FROM AUTHOR]

This article describes the study of the feasibility of pretreatment effect on oil palm ash (OPA) with hydrochloric acid (HCl) before compounding with the natural rubber (NR) using a conventional two roll mill. Results revealed that metal elements such as calcium and magnesium had been reduced from the OPA particle after treated by HCl solution, meanwhile the surface tended to be rougher and provided bigger pores on the surface. Scorch and cure times for HCl-treated OPA were longer with higher tensile strength, tensile modulus and hardness as compared to the nontreated OPA-filled NR vulcanizates. [ABSTRACT FROM AUTHOR]

This study determined if dentin proteases are denatured by phosphoric acid (PA) used in etch-and-rinse dentin adhesives. Dentin beams were completely demineralized with EDTA for 30 days. We “acid-etched” experimental groups by exposing the demineralized dentin beams to 1, 10, or 37 mass% PA for 15 sec or 15 min. Control beams were not exposed to PA but were incubated in simulated body fluid for 3 days to assay their total endogenous telopeptidase activity, by their ability to solubilize C-terminal crosslinked telopeptides ICTP and CTX from insoluble dentin collagen. Control beams released 6.1 ± 0.8 ng ICTP and 0.6 ± 0.1 ng CTX/mg dry-wt/3 days. Positive control beams pre-incubated in p-aminophenylmercuric acetate, a compound known to activate proMMPs, released about the same amount of ICTP peptides, but released significantly less CTX. Beams immersed in 1, 10, or 37 mass% PA for 15 sec or 15 min released amounts of ICTP and CTX similar to that released by the controls (p > 0.05). Beams incubated in galardin, an MMP inhibitor, or E-64, a cathepsin inhibitor, blocked most of the release of ICTP and CTX, respectively. It is concluded that PA does not denature endogenous MMP and cathepsin activities of dentin matrices. [ABSTRACT FROM PUBLISHER]

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Demineralized freeze-dried bone (DFDB) in matrix form must be rehydrated with a carrier medium which allows for easy manipulation during periodontal surgery. The purpose of this study was to evaluate how human DFDB suspended in a polyol matrix affects new bone formation in the rat calvarium critical-sized defect (CSD)model. Fifty-five adult male Harlan Sprague-Dawley rats were assigned to 1 of 5 treatment groups: polyol, 100% DFDB, 47% DFDB/polyol, 47% DFDB, or an unfilled control. They were then placed into 8-m calvarial CSDs. The bone donor source company for the DFDB and DFDB/polyol groups was the same. Calvaria were harvested 10 weeks after surgery and evaluated histomorphometrically. The diameter of bone particles from the 3 groups containing DFDB was measured by scanning electron microscopy. There was no statistically significant difference in the percentage of bone fill between any of the groups, although the 100% DFDB group exhibited the most bone fill. The 47% DFDB/polyol and 47% DFDB groups had similar amounts of bone formation. The average size of the demineralized bone particles from the 100% DFDB group was significantly smaller than that of the other 2 groups containing DFDB. Adding a polyol to DFDB produced similar osseous regeneration in the rat calvarium defect model vs DFDB alone. Yet from a clinical standpoint, the polyol enhanced graft handling and stability. Graft particle size may have an effect on bone fill. [ABSTRACT FROM AUTHOR]

Electrochemical impedance spectroscopy (EIS) offers a potentially nondestructive quantitative method for measuring the stability of resin films and or resin‐bonded dentin over time. The purpose of this study was to measure the electrical impedance of five experimental dental adhesives of increasing hydrophicities as 30‐μm films and as resin‐bonded coatings on acid‐etched dentin. Resin films or resin‐coated dentin disks were placed in U‐shaped chambers containing pairs of Ag–AgCl electrodes in 0.1M KCl. Electrical impedance spectra were run at day 0, 1, 7, 14, and 21 days. All resin films and resin‐bonded dentin showed increases in capacitance during the first day of storage in electrolyte. This was usually associated with an increase in the pore resistance of the resins. Generally, resin‐bonded dentin gave lower impedance values than their respective resins (resins 1–4) but solvated resin 5 bonded to water‐saturated dentin gave higher capacitance and impedance values than resin 5 films. However, solvated resin 5 films gave higher impedance values than resin 5‐bonded dentin. This behavior was confirmed by TEM examinations of silver uptake into films of neat resin 5 vs. ethanol‐solvated resin 5, where water tree‐like structures seen in the former were not seen in the latter. EIS is useful in examining changes in the capacitance and electrical impedance of very hydrophilic, ionic methacrylate resins. Its utility in detecting degradation in resin‐bonded dentin interfaces remains to be determined in longer term studies. © 2007 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 2008 [ABSTRACT FROM AUTHOR]

Background: Total hip replacement can be complicated by periprosthetic osteolysis. Monocytes/macrophages play a major role in the formation of the foreign body granulomas induced by wear debris. We hypothesized that periprosthetic monocytes/macrophages do not only accelerate inflammatory and osteoclast‐mediated osteolytic processes, but also resorb periprosthetic bone directly by themselves. This study was designed to evaluate the osteolytic potential in vitro of monocytes/macrophages derived from bone marrow. Methods: Monocytes/macrophages were produced by filtration of rat bone marrow cells, followed by culture in the presence of macrophage‐colony stimulating factor (M‐CSF). Monocyte/macrophage properties were ascertained using immunocytochemistry and phagocytic activity. Osteolytic cytokines and extracellular matrix degrading proteinases were quantified at the mRNA level. Results: Adherent cell fraction was immunoreactive for the monocyte/macrophage specific marker CD68 and active in the phagocytosis of carbon particles up to 72 h. They also showed immunoreactivity to cathepsin K, IL‐1β, IL‐6, and M‐CSF, but mostly did not react to TRAP. mRNA levels of osteolytic cytokines and extracellular matrix degrading proteinases were enhanced, but that of RANKL were not. Monocytes/macrophages resorbed dentine discs and carbonated calcium phosphate was very actively resorbed after stimulation with titanium particles. Discussion: Harvested bone marrow cells expressed monocyte/macrophage phenotype, but not osteoclastic markers. The capacity of these cathepsin‐K–positive phagocytic cells to resorb dentine discs and carbonated calcium phosphate in vitro suggests a direct role of monocytes/macrophages in bone resorption and periprosthetic osteolysis. The finding supports our hypothesis and previous histomorphometric observations on the presence of such osteolytic macrophages in vivo around loosening prosthesis. © 2007 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater 2008 [ABSTRACT FROM AUTHOR]

Mammalian and avian osteoclasts were isolated mechanically from long bones, seeded on to either untreated, unmineralized, anorganic or surface-demineralized mammalian dental tissues, and cultured for 1-6 h or up to 9 days in medium with added serum (10% heat-inactivated FCS). All substrates showed Howship's resorption lacunae which varied in detail with the composition and structural organization of the tissue. There was no species or substrate specificity. Osteoclasts also adhered, spread, migrated and resorbed in the absence of serum. In addition, osteoclasts resorbed avian egg shell and mollusc shell containing calcite and aragonite. When given the opportunity, osteoclasts are thus biochemically competent to resorb a much wider range of substrates than they usually do in vivo. Access to the substrate and attraction or deliverance of osteoclast precursors to it must be curtailing factors in in vivo resorption. [ABSTRACT FROM AUTHOR]

Objectives: The aim of this study was to evaluate the capacity of two rotatory instruments (controlled speed electric motor [CSEM] - 300 rpm; conventional slow handpiece [CSHP] - 18,000 rpm) to remove sound and demineralized dentin, by examining prepared cavity walls using the scanning electron microscopy (SEM) and assessing loss of mass., Materials and Methods: A total of 40 blocks of human occlusal dentin, measuring 5 mm × 5 mm × 4 mm (L × W × H), were divided into two groups according to the substrate type in which the cavity preparation was performed: D - demineralized dentin; and S - sound dentin (control group). The groups were subdivided according to the rotatory instrument used for cavity preparation (n = 10): CSEM (300 rpm); and CSHP (18,000 rpm). In half of the dentin blocks, caries lesion induction was performed for 6 weeks. The preparation of the cavities was performed on a standardizing machine, using a cylindrical tungsten carbide burr. Before and after the preparation, specimens were dehydrated in an incubator at 60°C for 30 min. The initial and final mass (in mg) of each dentin block was measured 3 times using the digital precision balance to obtain the mean weight Following cavity preparation, all specimens were hemisected and SEM was used to blindly assess each half so that the lateral walls of the prepared cavity were measured in μm, accepting the average of two measurements as the total depth of the preparation. Non-parametric Mann-Whitney analysis was performed with a 5% of significance level., Results: Regarding the weight difference (mg), no significance was detected between the groups. Regarding depth (μm), a significant difference was found between the groups, so that the CSRM showed lower cavity depth when compared with CSHP, both in sound and demineralized dentin., Conclusions: Controlled speed rotatory instruments were found to be more conservative in removing both sound and demineralized dentin, in terms of preparation and depth.

The present study evaluated the effects of guided tissue regeneration (GTR), with and without demineralized freeze-dried cortical bone grafts, in the treatment of furcation defects in 4 female beagle dogs with naturally occurring periodontal disease. The root surfaces were thoroughly debrided. Four weeks later, full thickness facial and lingual mucoperiosteal flaps were reflected using inverse bevel incisions on both sides of the mandible involving the 2nd, 3rd, and 4th premolar, and the 1st molar teeth. Following debridement, notches were placed on the roots at the level of supporting bone. Test quadrants were randomly selected and furcations were filled with reconstituted, demineralized, freeze-dried human cortical bone grafts. Following bone grafting, all defects were covered with an expanded polytetrafluoroethylene (ePTFE) membrane, which was sutured with 4-0 sutures. Afterward, interproximal sutures were placed through the flaps, assuring the flaps covered the membranes completely. The contralateral side, serving as control, was treated by debridement only and application of ePTFE membrane. All membranes were removed 6 weeks after surgery. Dogs were sacrificed at 4 months after surgery. Both mesio-distal and bucco-lingual histologic sections were evaluated by descriptive histology. Linear measurements and surface area determination of the furcal tissues were carried out using the microscope attached to a digitizer. Twelve to 20 nonserial sections were made of the mid-buccal aspects of each root of each treated tooth. Half of these sections were stained with Harris' hematoxylin and eosin (H&E) and the other half stained with Mallory's trichrome stain. Additionally, another group of 12 to 20 non-serial sections cut in the mesio-distal direction were secured for the surface area measurements of the furcations. Mean values for each dog were obtained for test and control teeth. ANOVA procedure for a split plot design was employed. Periodontal healing following the use of guided tissue regeneration procedures resulted in an increase in connective tissue and alveolar bone regeneration. Adjunctive bone grafting did not appear to enhance regeneration. J Periodontol 1993; 64:1145-1153., (© 1993 American Academy of Periodontology.)