Early marginal bone loss around dental implants to define success in implant dentistry: A retrospective study.

PURPOSE: The aim of this study was to establish an objective criterion in terms of marginal bone level (MBL) to know the prognosis of an implant. MATERIALS AND METHODS: A group of 176 patients in whom 590 implants were placed were included in this retrospective study. Patients older than 18 years, presenting either Kennedy class I or II edentulous section, or totally edentulous at least in one of the dental arches were included in this study. Those with any type of disturbance able to alter bone metabolism or with nontreated periodontal disease were excluded. Data on radiographic MBL at loading, 6 and 18 months later, age, gender, smoking habits, history of periodontitis, bone substratum, implant, and prosthetic features were recorded. Nonparametric receiver operating curves (ROC) were constructed for the MBL at 18 months in order to establish a distinction among high bone loser (HBL) and low bone loser (LBL) implants. Differences as a function of main variables were also determined, particularly abutment height and periodontal disease. RESULTS: HBL implants lost at least 0.48 mm of MBL 6 months after loading; they reached at least 2 mm of MBL 18 months after loading. MBL rate followed a nonlinear trend, except in implants restored over long prosthetic abutments and in patients with history of severe periodontitis; in whom the rate of MBL over the time was nearly zero. CONCLUSION: Implants that lose more than 0.5 mm of marginal bone 6 months after loading are at great risk of not being radiographically successful anymore. Therefore, 0.5 mm of MBL is proposed as a distinctive and objective criterion of success in Implant Dentistry within a 6-month follow-up period. A prosthetic abutment height ≥2 mm resulted the most protective factor in the peri-implant bone maintenance.

Histopathological comparison of healing after maxillary sinus augmentation using xenograft mixed with autogenous bone versus allograft mixed with autogenous bone.

OBJECTIVE: To compare the clinical and histologic outcomes of two different grafting materials (allograft and xenograft) when combined with autogenous bone and covered with a collagen membrane for sinus augmentation. MATERIAL AND METHODS: A parallel case series of fourteen patients in need of a unilateral sinus augmentation was evaluated in this study. Seven patients received a graft composed by autologous cortical bone (ACB) and anorganic bovine bone in a ratio of 1:1; the other seven patients received ACB mixed with an allograft in the same ratio. Bone biopsies were obtained 6 months after sinus augmentation at the time of implant placement. Comparative histomorphometrical, histopathological, and immunohistochemical analyses were conducted and statistically analyzed. RESULTS: After 12 months of functional loading, all implants in both groups were clinical and radiographically successful. Histomorphometrically, although the initial bone formation was not significantly different between groups (new mineralized tissue: 41.03(12.87)% vs. 34.50(13.18)%, p = .620; allograft vs. xenograft groups), the graft resorbed faster in the allograft group (remnant graft particles: 9.83[7.77]% vs. 21.71[17.88]%; p = .026; allograft vs. xenograft groups). Non-mineralized tissue did not statistically differ either (49.00[14.32]% vs. 43.79[19.90]%; p = .710; allograft vs. xenograft groups). The histologic analyses revealed higher cellular content, four times more osteoid lines, and higher vascularization in the xenograft group. Musashi-1 (mesenchymal stromal cell marker) was also more intensively expressed in the xenograft group (p = .019). CONCLUSIONS: Both composite grafts generate adequate substratum to receive dental implants after healing. Compared with the xenograft composite, allograft composite shows faster turnover and a quicker decrease in biological action after 6 months.

Role of wettability and nanoroughness on interactions between osteoblast and modified silicon surfaces.

Development of new biomaterials is a constant in regenerative medicine. A biomaterial's surface properties, such as wettability, roughness, surface energy, surface charge, chemical functionalities and composition, are determinants of cell adhesion and subsequent tissue behavior. Thus, the main aim of this study was to analyze the correlation between changes in wettability without topographical variation and the response of osteoblast-like cells. For this purpose oxidized silicon surfaces were methylated to different degrees. Additionally, the influence of nanoroughness, and the subsequent effect of hysteresis on cell behavior, was also analyzed. In this case oxidized silicon pieces were etched with caustic solutions to produce different degrees of nanoroughness. Axisymmetric drop-shape analysis and atomic force microscopy confirmed that the proposed surface treatments increased the nanometer roughness and/or the water contact angles. MG-63 osteoblast-like cells were cultured on the altered surfaces to study proliferation, and for ultrastructural analysis and immunocytochemical characterization. Increasing the nanometer surface roughness or water contact angle enhanced osteoblast behavior in terms of cell morphology, proliferation and immunophenotype, the effect provoked by methylation being more significant than that caused by nanoroughness.

Optimal microvessel density from composite graft of autogenous maxillary cortical bone and anorganic bovine bone in sinus augmentation: influence of clinical variables.

OBJECTIVES: The objectives of this study were to assess the microvessel density (MVD) of intra-sinus grafts after 6 months of wound healing and to study the relationship between revascularization processes and patient clinical variables and habits. MATERIAL AND METHODS: We performed 45 maxillary sinus augmentations with different implant placements in 25 consecutive patients, obtaining bone cores of the grafted area for histological, histomorphometric and immunohistochemical study. Biopsies were also taken from pristine bone in the posterior maxilla (control). RESULTS: All implants survived at 24 months. Biopsies of sinus augmentation areas showed significantly greater remodeling activity vs. pristine bone, with significantly more osteoid lines. The morphometry study revealed 34.88+/-15.2% vital bone, 32.02+/-15.1% non-mineralized tissue and 33.08+/-25.4% remnant anorganic bovine bone particles. The number of CD34-positive vessels was 86.28+/-55.52/mm(2) in graft tissue vs. 31.52+/-13.69/mm(2) in native tissue (P=0.002, Mann-Whitney U=46). The larger amount of non-mineralized tissue in grafts was directly correlated with a higher MVD (r=0.482, P=0.0001, Pearson's test). MVD was affected by the presence of periodontitis or tobacco and alcohol consumption. CONCLUSION: The angiogenesis and revascularization obtained by this type of graft achieve adequate tissue remodeling for osseointegration and are influenced by periodontal disease and tobacco or alcohol consumption.

Histomorphometric comparison of maxillary pristine bone and composite bone graft biopsies obtained after sinus augmentation.

INTRODUCTION: Sinus grafting is a technique oriented to facilitate implant placement in posterior atrophic maxillae. Several modifications of the original technique and a wide variety of materials have been proposed; most of them associated with implant survival rates. However, the quality of the bone obtained after the application of certain grafting materials has not been fully elucidated yet. The aims of this multicenter study were to analyse histomorphometrical samples obtained 6 months after sinus grafting using a composite graft consisting of anorganic bovine bone (ABB)+ autologous bone (AB), and to compare these samples with maxillary pristine bone biopsies. MATERIAL AND METHODS: Ninety maxillary sinus augmentations were performed for delayed implant placement (N = 90) in 45 consecutive patients (test group). Bone cores were harvested 6 months after grafting for histomorphometric and ultrastructural study. Control pristine bone biopsies were taken from the posterior maxilla of 10 patients (control). Bone radiographic changes were assessed up to 24 months after implant loading. RESULTS: The total mean values after analysis of test cores revealed a proportion of 46.08 + or - 16.6% of vital bone, 42.27 + or - 15.1% of non-mineralized connective tissue, and 37.02 + or - 25.1% of the remaining ABB particles. Significant bone remodeling activities were noticed in sinus grafting samples when compared with pristine bone. A statistically significant difference was observed in the number of osteoid lines between two groups, with higher values in the test one (15.1 + or - 11.48% vs. 2.5 + or - 2.2%, P = 0.0005). Ultrastructural study showed that vital trabecular bone was in intimal contact with ABB particles. Radiographic analysis revealed that the higher the proportion of remaining ABB, the lower the total vertical resorption of the graft. CONCLUSION: Sinus grafting constitutes an excellent model for the study of de novo bone formation patterns and graft consolidation, when a combination of different bone substitutes is applied. The combination of ABB+AB yields highly satisfactory outcomes from both a clinical and a histologic perspective.

Clinical and histologic comparison of two different composite grafts for sinus augmentation: a pilot clinical trial.

BACKGROUND AND OBJECTIVES: Sinus augmentation is a procedure used for augmenting insufficient bone height that is often observed in the maxillary posterior areas. Many different techniques as well as bone graft regimens have been suggested for performing this procedure. It was the goal of this study to compare, clinically and histologically, two different composite grafting regimens used for sinus augmentation. MATERIAL AND METHODS: Five patients, needing a bilateral sinus augmentation to allow implant placement, were recruited for this study. Right sinuses were grafted with cortical bone (collected from overlying the sinus membrane) and bovine hydroxyapatite (HA), while the left side sinuses were grafted with overlying autologous bone plus a bioglass (BG) material. Bone core biopsies were taken at 6 months after sinus graft or at the time of implant insertion. A waiting period of 6 additional months was granted to allow healing, before prosthetic restoration and functional loading. The level of peri-implant bone was evaluated 12 months after loading. A comparative histomorphometric analysis was conducted and a statistical analysis was performed. RESULTS: All implants in both groups were functional after a 12-month loading period. No bone loss was observed radiographically or clinically in both groups. Histologic analysis revealed that both composite grafts had a high biocompatibility. In the bovine HA-containing group, minimal xenogenic graft absorption was noted. In contrast, BG group samples presented a high absorption rate with some remaining particles imbedded in new normal bone. CONCLUSIONS: Sinus augmentation using a combination of autogenous bone plus either bovine HA or BG is a predictable technique.

Evaluation of sinus floor elevation using a composite bone graft mixture.

BACKGROUND: The performance of implant surgery in the posterior maxilla often poses a challenge due to insufficient available bone. Sinus floor elevation was developed to increase needed vertical height to overcome this problem. The present study described and reported a simple, safe and predictable bone graft mixture for the sinus lifting procedure. MATERIAL AND METHODS: Seventy patients were recruited for this study and underwent a sinus lift procedure. All sites were treated with a composite graft of cortical autogenous bone, bovine bone and platelet-rich plasma (PRP). A total of 263 implants (171 Astra Tech and 92 Microdent) were placed either simultaneously or delayed. All sites were clinically and radiographically evaluated 24 months after their prosthetic loading. Biopsy samples were taken from 16 delayed implant placement sites at the time of their implant placement. RESULTS: A 100% implant success rate was found after 24 months of functioning. Only two Microdent implants failed before loading, which translates to a 99% overall implant success rate. No statistically significant differences were found between simultaneous and delayed implant placement. Image processing revealed 34+/-6.34% vital bone, 49.6+/-6.04% connective tissue and 16.4+/-3.23% remaining Bio-Oss particles. However, the histomorphometric analysis showed that the bovine bone was incorporated into new bone formation. CONCLUSION: The results showed that a composite graft comprised of cortical autogenous bone, bovine bone and PRP mixture can be successfully used for sinus augmentation.

Flow cytometric and morphological characterization of platelet-rich plasma gel.

UNLABELLED: BACKGROUND OF PROBLEMS: Platelet-rich plasma (PRP) gel is derived from an autogenous preparation of concentrated platelets and is widely used in implant dentistry as a vector for cell growth factors. However, limited data are available on its structure and composition. The present study was aimed at providing a flow cytometric and ultrastructural characterization of PRP gel. MATERIALS AND METHODS: Twenty PRP gel samples were obtained from healthy volunteers. These PRP gel specimens were prepared for transmission (TEM) and scanning electron microscopy (SEM) examination of their morphological ultrastructure. Flow cytometry with CD41-PE monoclonal antibody was used to detect platelet cells, as this antibody recognizes human-platelet-specific antigen CD41. RESULTS: Both SEM and TEM showed that PRP gel contains two components: a fibrillar material with striated band similar to fibrin filaments, and a cellular component that contains human platelet cells. Both techniques indicated that no morphological elements were bound between the cellular component and the fibrillar material. The cells were confirmed as platelet cells by flow cytometric study after incubation with specific monoclonal antibody CD41-PE. CONCLUSION: PRP gel contains a fibrillar and a cellular (largely human platelet cell) component. This unique structure may be capable of acting as a vehicle for carrying of cells that are essential for soft/hard tissue regeneration.

Influence of alcohol and tobacco habits on peri-implant marginal bone loss: a prospective study.

A prospective clinical study was conducted to explore the possible link between peri-implant bone loss and the widespread habits of tobacco smoking and alcohol consumption. One hundred and eighty-five patients who received 514 implants were followed up for 3 years. Peri-implant marginal bone loss was evaluated by digital panoramic radiography and image analysis techniques. Multivariate analysis showed that peri-implant marginal bone loss was significantly related to a daily consumption of >10 g of alcohol, tobacco use and increased plaque levels and gingival inflammation. The present results indicate that daily alcohol consumption and tobacco use may have a negative influence on predictable long-term implant treatment outcomes, producing peri-implant bone loss and compromising restorative treatment with implant-supported prostheses.