Manuel Vallecillo-Capilla

Antigenic Phenotype of Cultured Human Osteoblast-Like Cells

Background/Aims: Osteoblasts are classically considered to play an important role during bone tissue development, and to be involved in the formation of mineralized bone matrix. Recent reports have suggested that they can also exert some activities directly associated with the immune system (cytokine synthesis and antigen presentation). Moreover, some authors have found antigens on osteoblast-like cells normally expressed by other cells with a common origin in bone marrow.Methods: We isolated and cultured human osteoblast-like lines and studied their antigenic phenotype with flow cytometry using monoclonal antibodies against antigens associated with hematopoietic cells.Results: Cultured cells expressed CD34, but were negative for CD45. B cell antigens CD20 and CD23 and myelomonocytic antigens CD11b, CD13, and CD16 were detected. Expression of CD3, CD14, CD15 and CD68 was negative, whereas CD25 expression was positive. CD56, an antigen expressed on NK cells, was positive. These cells were CD10, CD44, CD54, CD80, CD86 and HLA-DR positive, as previously described. An antigen specific to follicular dendritic cells was also observed on cultured osteoblast-like cells.Conclusions: The antigenic phenotypes of human osteoblast-like cells and FDC are similar. These data suggest that osteoblasts may be functionally related to certain dendritic cells and may play an additional role in bone tissue to that classically assigned.

Phagocytosis and Allogeneic T Cell Stimulation by Cultured Human Osteoblast-Like Cells

Background/Aims: The antigen phenotype of human osteoblast-like cells suggests that they are related to other cellular populations and may also have immunologic functions in common. Methods: Flow cytometry and transmission electron microscopy were used to show the phagocytotic activity of osteoblast-like cells in culture. The allogeneic stimulation of T cells by human osteoblast-like cells was determined by the measurement of T cell proliferation. Results: We demonstrated in vitro that human osteoblast-like cells isolated from normal bone specimens obtained during mandibular osteotomy can phagocytose particles of different nature and size and can stimulate allogeneic T cells. Phagocytosis of microorganisms (E.coli, Klebsiella or C. albicans) was observed, although at a very low rate of activity in comparison with the phagocytosis of latex particles. Conclusion: Our results suggest that human osteoblast-like cells may perform immunologic functions and act as antigen presentation cells.p>

Effect of Platelet-Rich Plasma on Growth and Antigenic Profile of Human Osteoblasts and Its Clinical Impact

PURPOSE In recent years, there has been widespread clinical use of platelet-rich plasma (PRP) to facilitate the regeneration of different tissues. However, few data are available on the effect of PRP on parameters other than cell growth. The aim of the present study was to evaluate the effect of PRP on the cell cycle, antigenic profile, and proliferation of primary cultured human osteoblasts. MATERIALS AND METHODS The cells in the present study were derived from human bone sections obtained from healthy volunteers during third molar surgery. PRP was prepared from human venous blood and used to culture the cell line obtained from the same patient. Flow cytometry was used to study the cell cycle, antigenic profile, and proliferation. RESULTS The treatment of osteoblasts with PRP modified the expression of CD54, CD80, CD86, and HLA-DR antigens. PRP treatment increased cell proliferation in the short term, but the cell proliferation capacity diminished in the long term, perhaps owing to cell exhaustion. No change in the cell cycle profile was observed in the PRP-cultured cells. CONCLUSIONS These results suggest that PRP treatment accelerates bone neoformation with no cell cycle changes that might carry a risk of malignant transformation.

Risk factors associated with early implant failure: A 5-year retrospective clinical study

STATEMENT OF PROBLEM The replacement of lost teeth with dental implants is a widespread treatment whose associated problems are also frequently encountered. Nevertheless, the factors associated with early implant failure have not been well documented. Further analyses of the factors influencing osseointegration establishment are required to maximize the predictability of the procedure and minimize implant failures. PURPOSE The purpose of this retrospective clinical study was to explore the association between possible risk factors and early implant failure. MATERIAL AND METHODS This retrospective clinical study evaluated 142 participants who received 276 external connection BTI implants between 2007 and 2011. Participant variables (age, sex, systemic disease, tobacco use, alcohol consumption, bruxism, and degree of periodontal disease), implant variables (type of edentulism, localization, area, diameter, length, and bone quality), intervention variables (expansion mechanisms, sinus augmentation techniques, bone regeneration, and implant insertion), and postoperative variables (presence of pain/inflammation at 1 week postsurgery) were studied. A multilevel logistic regression model (mixed effects-type model) was used to determine the influence of variables on early implant failure. RESULTS Early implant failure was significantly associated with the male sex (P=.001), severe periodontal disease (P=.005), short implants (P=.001), expansion technique (P=.002), and postoperative pain/inflammation at 1 week postsurgery (P<.001). CONCLUSIONS Early dental implant failure is more frequent in men and in individuals with severe periodontal disease, short implants, pain/inflammation at 1 week postsurgery, or bone expansion treatment.

Effect of Different Growth Factors on Human Cultured Osteoblast-Like Cells

Background/Aims: Proliferation and differentiation of osteoblast-like cells are regulated by complex interactions among systemic hormones, cytokines, and local growth factors. The success of oral rehabilitation using biomaterial implants depends on the growth of osteoblasts and their adhesivity to the surface of the implant. The study aimed to investigate the effect of different growth factors on the proliferation and adhesivity of human osteoblast-like cells in vitro.Methods: The effects of transforming growth factor β1 (TGFβ1), fibroblast growth factor (FGF), and interleukin-2 (IL-2) on the growth and adhesivity of human osteoblast-like cells in monolayer culture were studied. Their growth was measured by 3H-thymidine incorporation and their adhesivity by flow cytometry.Results: Incorporation of 3H-thymidine was increased by all growth factors. The effect did not appear to be dose dependent. No synergic effect was found between TGFβ1 and FGF. Treatment with TGFβ1 or FGF increased cell adhesivity by shortening the time needed for cell adhesion to the culture dish surface and hydroxyapatite-coated implants. IL-2 did not modify cell adhesivity.Conclusions: Growth factors can modulate cell proliferation and adhesivity, which may help to increase the success of implantation therapy.

Dental implant stability is influenced by implant diameter and localization and by the use of plasma rich in growth factors.

PURPOSE The objective was to analyze the factors that influence the stability of dental implants at 12 weeks after implant placement as measured by resonance frequency analysis using the Osstell system. MATERIALS AND METHODS This prospective clinical study was performed in 235 implants placed in 93 patients at the Oral Surgery and Implantology Clinic of the University of Granada. The gathered predictor variables were grouped into patient variables, implant variables, operative variables, and baseline implant stability quotient (ISQ). All variables were analyzed in a multivariate model to determine their influence on the ISQ score at 12 weeks after implant insertion (outcome variable). SUDAAN software was used for clustered sampling (multiple implants in patients). RESULTS Two hundred thirty-five dental implants were placed in 47 men (50.5%) and 46 women (49.5%; total, 93 patients; mean age, 52.13 ± 11.23 years; range, 27 to 76 years). No association was found between the patient variables and the ISQ values at 12 weeks. Among implant variables, worse ISQ values at 12 weeks were observed for a narrow diameter (P < .001) and maxillary implants (P = .006). Among surgical technique variables, the use of plasma rich in growth factors (P = .011) showed the best ISQ values at 12 weeks. CONCLUSIONS The diameter and localization of implants and the application of plasma rich in growth factors influenced the stability of implants measured at 12 weeks of wound healing. Accordingly, stability was less with a narrower implant diameter and maxillary localization and greater with implants humidified with plasma rich in growth factors.

Factors Affecting Dental Implant Stability Measured Using the Ostell Mentor Device: A Systematic Review.

Objectives:The aim of this study was to review the literature on factors that may affect dental implant stability as measured with the Ostell mentor device. Materials and Methods:A systematic search of the literature was performed in Pubmed, Scopus, and Cochrane databases using dental implants, stability, and resonance frequency analysis as key words. Results:The most relevant randomized controlled trials and clinical trials (n = 39) were selected from among 264 articles. Conclusions:Many factors can affect dental implant stability as measured with the Ostell mentor device. This may be a useful instrument for deciding the timing of implant loading, but additional research is required to establish the reliability and predictability of resonance frequency analysis for the future osseointegration of dental implants, which remains controversial.

Long-Term Survival of Dental Implants with Different Prosthetic Loading Times in Healthy Patients: A 5-Year Retrospective Clinical Study

PURPOSE To compare survival rates among dental implants restored with immediate, early, and conventional loading protocols, also comparing between maxillary and mandibular implants, and to evaluate the influence of implant length and diameter and the type of prosthesis on treatment outcomes. MATERIALS AND METHODS This retrospective cohort study initially included all 52 patients receiving dental implants between July 2006 and February 2008 at a private oral surgery clinic in Granada (Southern Spain). Clinical and radiographic examinations were performed, including periapical or panoramic radiographs, and incidences during completion of the restoration were recorded at 1 week, 3 months, 6 months, and at 1, 2, 3, 4, and 5 years. After a 5-year follow-up, 1 patient had died, 3 were lost to follow-up, and 6 required grafting before implant placement; therefore, the final study sample comprised 42 patients with 164 implants. RESULTS Variables associated with the survival/failure of the restoration were: number of implants (higher failure rate with fewer implants), bone type (higher failure rate in type III or IV bone), and type of prosthesis (higher failure rate with single crowns). No significant association was found in univariate or multivariate analyses between survival rate and the loading protocol, implant length or diameter, or maxillary/mandibular location. CONCLUSIONS Immediate occlusal loading, immediate provisionalization without occlusal loading, and early loading are viable treatment options with similar survival rates to those obtained with conventional loading. Bone quality and number of implants per patient were the most influential factors.

Bacterial contamination levels of autogenous bone particles collected by 3 different techniques for harvesting intraoral bone grafts.

PURPOSE The aim of this study was to compare levels of bacterial contamination of autogenous bone collected when using low-speed drilling, a back-action chisel, and a bone filter. MATERIALS AND METHODS Bone tissue samples were taken from 31 patients who underwent surgical extraction of their third lower molars. Before surgical removal of the molar, bone particles were collected by a low-speed drill or a back-action chisel. Then, a stringent aspiration protocol was applied during the ostectomy to collect particulate bone by a bone filter. Processing of samples commenced immediately by incubation in an anaerobic or a CO2-rich atmosphere. The number of colony-forming units (CFUs) was determined at 48 hours of culture. RESULTS No significant difference in the number of CFUs per milliliter was observed between the low-speed drilling group and the back-action chisel group in the anaerobic or CO2-rich condition (P = .34). However, significantly more micro-organisms were found in the bone filter group than in the low-speed drilling group or the back-action chisel group in the anaerobic and CO2-rich conditions (P < .001). CONCLUSIONS Particulate bone harvested with low-speed drilling or a back-action chisel is safer for use as an autograft than are bone particles collected with a bone filter. These results suggest that bone obtained from low-speed drilling is safe and straightforward to harvest and could be the method of choice for collecting particulate bone. Further research is needed to lower the bacterial contamination levels of autogenous bone particles used as graft material.