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±16.6% of vital bone, 42.27±15.1% of non‐mineralized connective tissue, and 37.02±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±11.48% vs. 2.5±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. To cite this article:
Galindo‐Moreno P, Moreno‐Riestra I, Ávila G, Fernández‐Barbero JE, Mesa F, Aguilar M, Wang H‐L, O'Valle F. Histomorphometric comparison of maxillary pristine bone and composite bone graft biopsies obtained after sinus augmentation.
Clin. Oral Impl. Res. 21 , 2009; 122–128.     

Effect of anorganic bovine bone to autogenous cortical bone ratio upon bone remodeling patterns following maxillary sinus augmentation

Introduction: Maxillary sinus augmentation is a predictable implant site development technique, although several local and systemic factors may influence outcomes. The aim of this study was to evaluate healing patterns and bone remodeling activity following the use of two different graft mixtures for maxillary sinus augmentation. Materials and methods: Patients in need of maxillary sinus augmentation were randomly assigned to two different groups. A graft mixture using a 50% autologous bone (AB) to 50% anorganic bovine bone (ABB) ratio was used in group 1, while a 20% AB to 80% ABB ratio was utilized for group 2. After a 6‐month healing period, bone core biopsies were harvested for histological, histomorphometrical, and immunohistochemical analyses. Results: Twenty‐eight subjects participated in this study. No statistically significant differences were found between groups in regards to vital bone and non‐mineralized tissue proportions. Higher number of osteoid lines (18.05 ± 10.06 in group 1 vs. 9.01 ± 7.53 in group 2; P=0.023) and higher cellularity, particularly regarding the number of osteocytes (631.85 ± 607.98 in group 1 vs. 219.08 ± 103.26 in group 2; P=0.002), were observed in specimens from group 1. Differences in expression patterns of osteopontin and tartrate‐resistant acid phosphatase were also detected between groups. Conclusion: AB to ABB ratio appears to influence bone remodeling patterns and cell content following maxillary sinus augmentation procedures. Similar proportion of vital bone was found in specimens obtained from both groups. More cellular presence was observed in samples containing higher proportions of AB. To cite this article:
Galindo‐Moreno P, Moreno‐Riestra I, Avila G, Padial‐Molina M, Paya JA, Wang H‐L, O'Valle F. Effect of anorganic bovine bone to autogenous cortical bone ratio upon bone remodeling patterns following maxillary sinus augmentation.
Clin. Oral Impl. Res. 22 , 2011; 857–864.
doi: 10.1111/j.1600‐0501.2010.02073.x     

Maxillary sinus grafting with Bio-Oss or Straumann Bone Ceramic: histomorphometric results from a randomized controlled multicenter clinical trial

Introduction: This investigation was designed to compare the histomorphometric results from sinus floor augmentation with anorganic bovine bone (ABB) and a new biphasic calcium phosphate, Straumann^® Bone Ceramic (BCP). Materials and methods: Forty‐eight maxillary sinuses were treated in 37 patients. Residual bone width was ≥6 mm and height was ≥3 mm and <8 mm. Lateral sinus augmentation was used, with grafting using either ABB (control group; 23 sinuses) or BCP (test group; 25 sinuses); sites were randomly assigned to the control or test groups. After 180–240 days of healing, implant sites were created and biopsies taken for histological and histomorphometric analyses. The parameters assessed were (1) area fraction of new bone, soft tissue, and graft substitute material in the grafted region; (2) area fraction of bone and soft tissue components in the residual alveolar ridge compartment; and (3) the percentage of surface contact between the graft substitute material and new bone. Results: Measurable biopsies were available from 56% of the test and 81.8% of the control sites. Histology showed close contact between new bone and graft particles for both groups, with no significant differences in the amount of mineralized bone (21.6±10.0% for BCP vs. 19.8±7.9% for ABB; P=0.53) in the biopsy treatment compartment of test and control site. The bone‐to‐graft contact was found to be significantly greater for ABB (48.2±12.9% vs. 34.0±14.0% for BCP). Significantly less remaining percentage of graft substitute material was found in the BCP group (26.6±5.2% vs. 37.7±8.5% for ABB; P=0.001), with more soft tissue components (46.4±7.7% vs. 40.4±7.3% for ABB; P=0.07). However, the amount of soft tissue components for both groups was found not to be greater than in the residual alveolar ridge. Discussion: Both ABB and BCP produced similar amounts of newly formed bone, with similar histologic appearance, indicating that both materials are suitable for sinus augmentation for the placement of dental implants. The potential clinical relevance of more soft tissue components and different resorption characteristics of BCP requires further investigation.     

Atrophic maxillary floor augmentation by mineralized human bone allograft in sinuses of different size: an histologic and histomorphometric analysis

Objective: The aims of this work were to histologically examine the healing of mineralized human bone allograft (MHBA) in sinus augmentation for elevating a severe maxillary atrophy ridge (≤2 mm residual ridge height) and to correlate the results to the sinus cavity size. Material and methods: A two‐stage protocol was conducted in 23 patients, all having crestal bone ≤2 mm. A mixture of 80/20 cortical/cancellous of MHBA particles was used to augment sinus using the lateral window approach in narrow (NS; <15 mm bucco‐palatal distance) and wide (WS; ≥15 mm bucco‐palatal distance) sinuses, based upon computerized tomography (CT) assessment. A bone core biopsy was taken at implant placement, 6 and 9 months after surgery. Microradiography, histology and histochemistry of methacrylate‐embedded sections were performed to analyze and to evaluate the bone and graft amount. Results: Newly formed bone around MBHA particles was found in all 28 biopsies. Bone showed a woven structure at 6 months after surgery and a lamellar structure 9 months after surgery. At 6 months after surgery, the 13 NS and 15 WS had 30.5±8.8% and 20.7±4.9% mean±SD bone formation, respectively. At 9 months after surgery, it was 38.8±7% (NS) and 30.7±3% (WS). Residual graft was about 16% (6 months) and 6% (9 months), in both NS and WS. The Mann–Whitney test showed a greater bone formation in NS than in WS (P<0.005). Conclusions: The used 80/20 MHBA mixture appears to promote, in the severe atrophic maxilla, a satisfactory bone formation. Our results prove that the larger the sinus, the longer the maturation time needed to achieve a suitable amount of new bone formation. To cite this article:
Maria Soardi C, Spinato S, Zaffe D, Wang H‐L. Atrophic maxillary floor augmentation by mineralized human bone allograft in sinuses of different size: an histologic and histomorphometric analysis.
Clin. Oral Impl. Res. 22 , 2011; 560–566
doi: 10.1111/j.1600‐0501.2010.02034.x     

Influence of two barrier membranes on staged guided bone regeneration and osseointegration of titanium implants in dogs. Part 2: augmentation using bone graft substitutes

Objectives: To assess the influence of two barrier membranes and two bone graft substitutes on staged guided bone regeneration and osseointegration of titanium implants in dogs. Materials and methods: Saddle‐type defects were prepared in the lower jaws of 6 fox hounds and randomly filled with a natural bone mineral (NBM) and a biphasic calcium phosphate (SBC) and allocated to either an in situ gelling polyethylene glycol (PEG) or a collagen membrane (CM). At 8 weeks, modSLA titanium implants were inserted and left to heal in a submerged position. At 8+2 weeks, respectively, dissected blocks were processed for histomorphometrical analysis (e.g., mineralized tissue [MT], bone‐to‐implant contact [BIC]). Results: The mean MT values (mm²) and BIC values (%) tended to be higher in the PEG groups (MT: NBM [3.4±1.7]; SBC [4.2±2]/BIC: NBM [67.7±16.9]; SBC [66.9±17.8]) when compared with the corresponding CM groups (MT: NBM [2.5±0.8]; SBC [2.3±1.6]/BIC: NBM [54.1±22.6]; SBC [61±8.7]). These differences, however, did not reach statistical significance. Conclusion: It was concluded that all augmentation procedures investigated supported bone regeneration and staged osseointegration of modSLA titanium implants. To cite this article :
Mihatovic I, Becker J, Golubovic V, Hegewald A, Schwarz F. Influence of two barrier membranes on staged guided bone regeneration and osseointegration of titanium implants in dogs. Part 2: augmentation using bone graft substitutes.
Clin Oral Impl Res. 23 , 2012; 308–315.
doi: 10.1111/j.1600‐0501.2011.02238.x     

Guided bone generation in a rabbit mandible model after periosteal expansion with an osmotic tissue expander

Objectives: To evaluate the space‐maintaining capacity of titanium mesh covered by a collagen membrane after soft tissue expansion on the lateral border of the mandible in rabbits, and to assess bone quantity and quality using autogenous particulate bone or bone‐substitute (Bio‐Oss^®), and if soft tissue ingrowth can be avoided by covering the mesh with a collagen membrane. Material and methods: In 11 rabbits, a self‐inflatable soft tissue expander was placed under the lateral mandibular periosteum via an extra‐oral approach. After 2 weeks, the expanders were removed and a particulated onlay bone graft and deproteinized bovine bone mineral (DBBM) (Bio‐Oss^®) were placed in the expanded area and covered by a titanium mesh. The bone and DBBM were separated in two compartments under the mesh with a collagen membrane in between. The mesh was then covered with a collagen membrane. After 3 months, the animals were sacrificed and specimens were collected for histology. Results: The osmotic soft tissue expander created a subperiosteal pocket and a ridge of new bone formed at the edges of the expanded periosteum in all sites. After the healing period of 3 months, no soft tissue dehiscence was recorded. The mean bone fill was 58.1±18% in the bone grafted area and 56.9±13.7% in the DBBM area. There was no significant difference between the autologous bone graft and the DDBM under the titanium mesh with regard to the total bone area or the mineralized bone area. Scanning electron microscopy showed that new bone was growing in direct contact with the DBBM particles and the titanium mesh. There is a soft tissue ingrowth even after soft tissue expansion and protection of the titanium mesh with a collagen membrane. Conclusion: This study confirms that an osmotic soft tissue expander creates a surplus of periosteum and soft tissue, and that new bone can subsequently be generated under a titanium mesh with the use of an autologous bone graft or DBBM. To cite this article:
Abrahamsson P, Isaksson S, Andersson G. Guided bone generation in a rabbit mandible model after periosteal expansion with an osmotic tissue expander.
Clin. Oral Impl. Res. 22 , 2011; 1282–1288.
doi: 10.1111/j.1600‐0501.2010.02108.x     

Histological evaluation of healing after transalveolar maxillary sinus augmentation with bioglass and autogenous bone

Objectives: The aim was to evaluate histologically the outcome of a bioglass and autogenous bone (at 1 : 1 ratio) composite implantation for transalveolar sinus augmentation. Methods: In 31 patients, during implant installation ca. 4 months after sinus augmentation, biopsies were harvested through the transalveolar osteotomy by means of a trephine bur and non‐decalcified sections through the long axis of the cylinder were produced. After a strict selection process, taking into account the presurgical residual bone height and biopsy length, 8 and 15 biopsies representing the new tissues formed inside the sinus and the transalveolar osteotomy, respectively, qualified for analysis. The tissue fractions occupied by newly formed bone (mineralized tissue+bone marrow), soft connective tissue, residual biomaterial+empty spaces, and debris inside the sinus cavity or the transalveolar osteotomy were estimated. Results: Bone and connective tissue fraction in the newly formed tissues inside the sinus cavity averaged 23.4 ± 13.2% and 54.1 ± 23.5%, respectively. Residual biomaterial, empty spaces, and debris averaged 1.9 ± 3.5%, 10.5 ± 6.3%, and 8.4 ± 14.5%, respectively. In the transalveolar osteotomy, bone and connective tissue fraction averaged 41.6 ± 14.3% and 46.1 ± 13%, respectively, while the amount of residual biomaterial, empty spaces, and debris was 2.8 ± 5%, 4.7 ± 1.9%, and 3.2 ± 2.6%, respectively. Statistically significant differences between the sinus cavity and the transalveolar osteotomy were found only for bone and empty spaces' values (P=0.02 and 0.04, respectively). Conclusion: Sinus augmentation with a bioglass and autogenous bone composite is compatible with bone formation that, in a short distance from the floor of the sinus, shows similar density as that reported previously for other commonly used bone substitutes. New bone fraction inside the transalveolar osteotomy was almost twice as much as in the sinus cavity, while the amount of residual biomaterial was much less than that inside the sinus. To cite this article :
Stavropoulos A, Sima C, Sima A, Nyengaard J, Karring T, Sculean A. Histological evaluation of healing after transalveolar maxillary sinus augmentation with bioglass and autogenous bone.
Clin. Oral Impl. Res. 23 , 2012; 125–131.
doi: 10.1111/j.1600‐0501.2011.02161.x     

Single-stage sinus augmentation with cancellous iliac bone and anorganic bovine bone in the presence of platelet-rich plasma in the miniature pig

Aim: The aim of the present study was to evaluate the osseointegration of dental implants and bone formation in maxillary sinus grafting with autologous and anorganic bovine bone in the presence of platelet‐rich plasma (PRP) in an established animal model. Material and methods: We performed bilateral maxillary sinus augmentation with 50% anorganic bovine bone and simultaneously inserted a titanium screw implant in five minature pigs. Six hundred microlitre autologous PRP were added to the left side (test). The right side (no PRP) served as control. Polychrome sequential labeling was performed. The animals were sacrificed 6 weeks after surgery. Undecalcified ground sections were evaluated by microradiography, digitized histomorphometry and under fluorescent light. Results: The mean bone implant content in the test and control group was 8.4% and 17.3% respectively (P=0.042). The mean height of newly formed mineralized bone in the augmented area of the test group was 3.6 mm and 5.7 mm respectively (P=0.342). In the PRP group, the mean area of newly formed bone in the base of the sinus was enhanced (75.23%) as compared to the control side (51.8%) (P=0.020^*). Although PRP enhanced bone formation at the base of the maxillary sinus, it neither improved osseointegration of dental implants nor bone in‐growth into the bone substitute under the selected experimental conditions.     

Comparison of a synthetic bone substitute composed of carbonated apatite with an anorganic bovine xenograft in particulate forms in a canine maxillary augmentation model

Objective: To evaluate the effect of a porous geometry in particulate bone on new bone formation by comparison of anorganic bovine carbonate apatite (ABCA) with synthetic carbonated apatite (SCA), which have similar properties but different micro‐structures. Material and methods: Porous structures and anorganic components of ABCA and SCA were evaluated using scanning electron microscope and Fourier transform infrared. They were implanted in maxillary augmentation models with the mouth split design in a total of 15 Beagle dogs. The animals were sacrificed 4, 8 and 16 weeks after surgery, and the histomorphometrical results were statistically analyzed for the material's geometrical relationship and new bone formation in relation to the available space and contact surface for osteoconduction. Results: Both materials showed a typical infrared pattern of CO₃^2?‐substituted hydroxyapatite (HA). Porous structures and a bridging effect of osteoconductive bone material were relatively better observed in SCA. The ratio of the material area to the total area was higher (P<0.01) for ABCA (28.03±6.09) than for SCA (20.26±4.23). The ratio of the number of particles possessing a pore structure to the total number and the interparticular space was greater (P<0.001 and 0.01) for SCA (18.12±9.44 and 79.74±4.23) compared with ABCA (1.45±1.74 and 71.63±5.85). The new bone areas and the bone–material contact lengths were greater in SCA than in ABCA (P<0.05). Conclusions: The present study showed that porous structures may have an influence on new bone formation in osteoconductive bone substitutes. To cite this article:
Kim DK, Lee S‐J, Cho TH, Hui P, Kwon M‐S, Hwang SJ. Comparison of a synthetic bone substitute composed of carbonated apatite with an anorganic bovine xenograft in particulate forms in a canine maxillary augmentation model.
Clin. Oral Impl. Res. 21 , 2010; 1334–1344.
doi: 10.1111/j.1600‐0501.2010.01953.x     

Sinus augmentation analysis revised: the gradient of graft consolidation

Objective: Graft consolidation follows a gradient that reflects the properties of bone substitutes at sites of sinus augmentation. Here we present an analytical method to investigate the process of graft consolidation taking the distance from the maxillary host bone into account. Material and methods: We therefore evaluated histological specimens, 6 and 12 weeks after the sinus of minipigs was augmented with Bio‐Oss^®, a deproteinized bovine bone mineral, and Ostim^®, an aqueous paste of synthetic nanoparticular hydroxyapatite. A curve was drawn that represents the changes in histomorphometric parameters within a given distance from the maxillary host bone. Results: Based on this curve, three regions of interest were defined: R1 (0–1 mm) the bridging distance where new bone is laid onto the host bone, R2 (2–3 mm) a region of osteoconduction where new bone exclusively grows on the biomaterial, R3 (4–5 mm) and a region of osteoconduction where bone formation has reached its maximal extension. Qualitative and quantitative analysis of the three regions can reveal differences in graft consolidation, depending on the bone substitutes and the observation period [Bone volume (BV) per tissue volume after 6 weeks: R1: 19±8.4% for Bio‐Oss^® and 42.9±13.2% for Ostim^® (P=0.03), R2: 3±2.4% for Bio‐Oss^® and 14.7±9.5% for Ostim^® (P=0.03), R3: 5±4.1% for Bio‐Oss^® and 5.3±5.3% for Ostim^® (P=0.86). BV per tissue volume after 12 weeks: R1: 38.0±13.3% for Bio‐Oss^® and 53.3±6.6 for Ostim^® (P=0.04), R2: 14±12.2 for Bio‐Oss^® and 26.4±11 for Ostim^® (P=0.18), R3: 6.6±7 for Bio‐Oss^® and 10.7±5.8 for Ostim^® (P=0.32) after 12 weeks]. Conclusion: Based on the graft consolidation gradient, the impact of bone substitutes to modulate the process of bone formation and the kinetic of degradation within a distinct region of the augmented sinus can be investigated.     

Back‐scattered electron imaging and elemental analysis of retrieved bone tissue following sinus augmentation with deproteinized bovine bone or biphasic calcium phosphate

Objectives: To compare resorption of a synthetic biphasic calcium phosphate (BCP) bone–graft substitute with deproteinized bovine bone (DBB) used for human maxillary sinus augmentation. Materials and methods: Eleven patients underwent bilateral maxillary sinus floor augmentation with DBB in one side and a BCP (40%β‐tricalcium phosphate (β‐TCP) and 60% hydroxyapatite) in the contralateral side. Simultaneously, with the augmentation on each side a microimplant was placed vertically from the top of the alveolar crest penetrating the residual bone and the grafting material. Eight months after initial surgery the microimplants were retrieved with a surrounding bone core. The composition of residual graft material and surrounding bone was analysed by scanning electron microscopy and energy dispersive X‐ray spectroscopy. Results: Residual graft material of both types was present as 10–500 μm particles in direct contact with, or completely surrounded by, newly formed bone; smaller particles were also present in non‐mineralized tissue. In the case of BCP the bone–graft substitute interface showed evidence of superficial disintegration of particles into individual grains. Median Ca/P ratios (at.%), determined from >200 discreet sites within residual graft particles and adjacent bone, were: DBB: 1.61 (confidence interval [CI] 1.59–1.64); BCP: 1.5 (CI 1.45–1.52); DBB‐augmented bone: 1.62 (CI 1.59–1.66); BCP‐augmented bone: 1.52 (CI 1.47–1.55); P=0.028 for DBB vs. BCP and DBB‐ vs. BCP‐augmented bone. The reduction in Ca/P ratio for BCP over the healing period is consistent with the dissolution of β‐TCP and reprecipitation on the surface of calcium‐deficient hydroxyapatite. Conclusion: The β‐TCP component of BCP may be gradually substituted by calcium‐deficient hydroxyapatite over the healing period. This process and superficial degranulation of BCP particles may influence the progress of resorption and healing. To cite this article:
Lindgren C, Hallman M, Sennerby L, Sammons R. Back‐scattered electron imaging and elemental analysis of retrieved bone tissue following sinus augmentation with deproteinized bovine bone or biphasic calcium phosphate.
Clin. Oral Impl. Res. 21 , 2010; 924–930.
doi: 10.1111/j.1600‐0501.2010.01933.x     

Maxillary sinus augmentation with autologous bone harvested from the lateral maxillary wall combined with bovine‐derived hydroxyapatite: clinical and histologic observations

Objective: The aim of this study was to determine the clinical efficacy of a mixture of autologous bone harvested from the lateral wall of the maxilla using bone shavers and bovine‐derived hydroxyapatite (HA) placed as a graft to elevate the maxillary sinus floor. The histological picture of tissue found in the sinus, the survival rate and the success of the implants were all evaluated. Material and methods: A total of 90 titanium implants were placed in 34 patients. In all of them, the lateral maxillary wall was harvested as a particulate bone graft, subsequently mixed with bovine‐derived HA and packed in the sinus cavity. The lateral access window was then covered with a bioresorbable porcine‐derived collagen membrane. In 32 sinuses, a two‐stage surgery was performed, while in the remaining 10 cases a one‐stage surgery was carried out. In the two‐stage approach, 14 randomly selected biopsies were obtained at the time of implant insertion after a healing period of 9 months. The histological specimens were histologically and histomorphometrically evaluated. Results: One implant was lost, leading to a survival rate of 98.9%. The new bone consisted of lamellae of living bone contained osteocytes and in close contact with bovine bone particles that were partly infiltrated by newly formed bone. Bovine bone particle resorption could not be found. The histomorphometric analysis showed the following averages: 29% of newly formed bone and 21% of anorganic bovine bone. The marrow spaces made up the remaining 50% of the specimens. Conclusion: Sinus lift graft with autologous bone harvested from the maxillary lateral wall combined with demineralized bovine bone leads to a predictable outcome regarding the amount of bone formation in sinus floor augmentation. To cite this article:
de Vicente JC, Hernández‐Vallejo G, Braña‐Abascal P, Peña I. Maxillary sinus augmentation with autologous bone harvested from the lateral maxillary wall combined with bovine‐derived hydroxyapatite: clinical and histologic observations.
Clin. Oral Impl. Res. 21 , 2010; 430–438
doi: 10.1111/j.1600‐0501.2009.01877.x     

Evaluation of an anorganic bovine-derived mineral with P-15 hydrogel bone graft: preliminary study in a rabbit cranial bone model

Objectives: The present investigation aimed to assess the bone‐regenerative potential of two formulations of anorganic bovine‐derived mineral bound to a P‐15 (ABM/P‐15) bone graft – the particulate and the hydrogel forms – in a delayed healing rabbit cranial defect model. Material and methods: Ten adult male New Zealand White rabbits were used to create two 8 mm transcortical cranial defects per rabbit and each one received randomly the test material (ABM/P‐15 carboxymethyl cellulose (CMC)‐hydrogel graft), the standard control material (ABM/P‐15 particulate graft) or remained empty as a negative control. The defects were allowed to heal for 2 and 4 weeks. Qualitative and quantitative histological outcomes were assessed on undecalcified sections. Results: In the defects grafted with the test material, at both time points, there was a marked random migration of the bone substitute particles. As a consequence, the space maintenance provision was lost and new bone formation was reduced compared with the control particulate graft material. The histomorphometric analysis showed that the control material attained better results, with an average of 13.8 ± 1.9% and 18.2 ± 4.4% of new bone at 2 and 4 weeks, compared with 8.5 ± 2.4% and 13 ± 2.9% for the test material. These differences were significant at 2 weeks (P≤0.05), but not at 4 weeks (P>0.05). Additionally, there was a significant difference in the total area of mineralized tissue (new bone plus particles), favoring the standard control over the test material: 43.2 ± 14.4% vs. 14.2 ± 5.3% at 2 weeks and 56.9 ± 4.2% vs. 24.2 ± 9.6% at 4 weeks, respectively. Conclusions: The test ABM/P‐15 CMC‐hydrogel graft material behaved in this animal model by migration of the graft particles, what determined an unpredictable osseoconduction and, consequently, a decreased quality and quantity of bone regeneration as compared with the osseopromotive behavior exhibited by the standard particulate form of the ABM/P‐15 control graft. It is therefore suggested to restrain the application of the hydrogel graft form in non‐contained anatomical bone defects.     

Experimental model of bone response to xenografts of bovine origin (Endobon): a radiological and histomorphometric study

Objective: To carry out a radiological and histomorphometric evaluation of bone response to bovine bone implants inserted in rabbits' tibiae. Materials and Methods: Twenty New Zealand rabbits weighing 3900–4500 g were used. Twenty bovine bone implants (Endobon^®) in granulated form of 500–1000 μm granulometry were inserted in the proximal metaphyseal area of the animals' right tibia and 20 control areas were located in the proximal metaphyseal area. Following implantation, the animals were sacrificed in four groups of five, after 1 month, 2 months, 3 months and 4 months, respectively. Anteroposterior and lateral radiographs were taken. Samples were sectioned at 5 μm and stained using Hematoxylin–Eosin and Masson's trichromic. Results: After 4 months, radiological images showed complete repair of the bone defects. No healed or residual bone alterations attributable to the presence of the implant were observed. Histomorphometric analysis at 4 months showed the presence of a higher density of newly formed bone with mean values for new bone, residual graft material and non‐mineralized connective tissue of 22.8 ± 1.5%, 39.4 ± 2.3% and 37.7 ± 2.5%. There were no statistically significant differences in the length of cortical formation with bovine bone, 98.8 ± 1.1%, compared with the control group, 99.1 ± 0.7%, at the end of the study period. Conclusions: The biomaterial used in the study was shown to be biocompatible, osteoconductive and non‐resorbable and as such a possible bone substitute that does not interfere with normal reparative bone processes. To cite this article:
Ramírez‐Fernández M^aP, Calvo‐Guirado JL, Delgado‐Ruiz RA, Maté‐Sánchez del Val JE, Gómez‐Moreno G, Guardia J. Experimental model of bone response to xenografts of bovine origin (Endobon^®): a radiological and histomorphometric study.
Clin. Oral Impl. Res. 22 , 2011; 727–734
doi: 10.1111/j.1600‐0501.2010.02052.x     

Maxillary sinus floor elevation with bovine bone mineral combined with either autogenous bone or autogenous stem cells: a prospective randomized clinical trial

Aim: To assess whether differences occur in bone formation after maxillary sinus floor elevation surgery with bovine bone mineral (BioOss^®) mixed with autogenous bone or autogenous stem cells. The primary endpoint was the percentage of new bone three months after the elevation procedure. Material and methods: In a randomized, controlled split‐mouth design, in 12 consecutive patients (age 60.8 ± 5.9 years, range 48–69 years) needing reconstruction of their atrophic maxilla, a bilateral sinus floor augmentation procedure was performed. Randomly, on one side the augmentation procedure was performed with bovine bone mineral (BioOss^®) seeded with mononuclear stem cells harvested from the posterior iliac crest (test group) while BioOss^® mixed with autogenous bone (harvested from the retromolar area) was applied on the contra‐lateral side (control group). On 14.8 ± 0.7 weeks after the sinus floor elevation, biopsies from the reconstructed areas were taken at the spots where subsequently the endosseous implants were placed. The biopsies were histomorphometrically analyzed. Results: Significantly more bone formation was observed in the test group (17.7 ± 7.3%) when compared with the control group (12.0%± 6.6; P=0.026). In both the test and control group, all implants could be placed with primary stability. In one patient, not all biopsies contained BioOss^®. This patient was excluded from analysis. Conclusion: Mesenchymal stem cells seeded on BioOss^® particles can induce the formation of a sufficient volume of new bone to enable the reliable placement of implants within a time frame comparable with that of applying either solely autogenous bone or a mixture of autogenous bone and BioOss^®. This technique could be an alternative to using autografts. To cite this article: Rickert D, Sauerbier S, Nagursky H, Menne D, Vissink A, Raghoebar GM. Maxillary sinus floor elevation with bovine bone mineral combined with either autogenous bone or autogenous stem cells: a prospective randomized clinical trial.
Clin. Oral Impl. Res. 22 , 2011; 251–258.
doi: 10.1111/j.1600‐0501.2010.01981.x     

Bone response to hydroxyapatites with open porosity of animal origin (porcine [OsteoBiol mp3] and bovine [Endobon]): a radiological and histomorphometric study

Purpose: To carry out a radiological and histomorphometric evaluation of bone response to two xenografts of animal origin, one porcine, and the other bovine, inserted in rabbits' tibiae. Material and methods: Twenty New Zealand rabbits weighing 3900–4500 g were used. Twenty bovine bone grafts (Endobon^®) in granulated form of 500–1000 μm granulometry were inserted in the proximal metaphyseal area of the animals' right tibia, and 20 porcine bone grafts (OsteoBiol^®mp3) in granulated form of 600–1000 μm granulometry were inserted in the proximal metaphyseal area of the animals' left tibia. Following graft insertion, the animals were sacrificed in four groups of five, after 1, 2, 3 and 4 months, respectively. Anteroposterior and lateral radiographs were taken. Samples were processed for observation under light microscopy. Histomorphometric measurements were presented as mean values ± standard deviations. Results: At 4 months after treatment, the bone defects displayed radiological images that showed complete repair of osseous defects. Histomorphometric evaluation showed that for the porcine xenograft, the study averages for newly formed bone represented 22.8 ± 1.8%, for residual graft material 23.6 ± 3% and for connective tissue 53.5 ± 2.5%, while for the bovine xenograft newly formed bone represented 23.1 ± 1.8%, residual graft material 39.4 ± 3% and non‐mineralized connective tissue 37.5 ± 2.5%. Conclusions: The biomaterials assessed in the study were shown to be biocompatible and osteoconductive. Collagenized porcine xenografts proved more resorbable than bovine xenografts. Both can be used as possible bone substitutes without interfering with normal reparative bone processes. To cite this article:
Ramírez‐Fernández MP, Calvo‐Guirado JL, Delgado‐Ruiz RA, Maté‐Sánchez del Val JE, Vicente‐Ortega V, Meseguer‐Olmos L. Bone response to hydroxyapatites with open porosity of animal origin (porcine [OsteoBiol^®mp3] and bovine [Endobon^®]): a radiological and histomorphometric study.
Clin. Oral Impl. Res. 22 , 2011; 767–773.
doi: 10.1111/j.1600‐0501.2010.02058.x     

Influence of two barrier membranes on staged guided bone regeneration and osseointegration of titanium implants in dogs: part 1. Augmentation using bone graft substitutes and autogenous bone

Objectives: To assess the influence of two barrier membranes and two bone graft substitutes mixed with autogenous bone (AB) on staged guided bone regeneration and osseointegration of titanium implants in dogs. Materials and methods: Four saddle‐type defects each were prepared in the upper jaw of six fox hounds and randomly filled with a natural bone mineral (NBM)+AB and a biphasic calcium phosphate (SBC)+AB and allocated to either an in situ gelling polyethylene glycol (PEG) or a collagen membrane (CM). At 8 weeks, modSLA titanium implants were inserted and left to heal in a submerged position. At 8+2 weeks, dissected blocks were processed for histomorphometrical analysis (e.g., treated area [TA], bone‐to‐implant contact [BIC]). Results: The mean TA values (mm²) and BIC values (%) tended to be higher in the PEG groups(TA: NBM+AB [10.4 ± 2.5]; SBC+AB [10.4 ± 5.8]/BIC: NBM+AB [86.4 ± 20.1]; SBC+AB [80.1 ± 21.5]) when compared with the corresponding CM groups (TA: NBM+AB [9.7 ± 4.8]; SBC+AB [7.8 ± 4.3]/BIC: NBM+AB [71.3 ± 20.8]; SBC+AB [72.4 ± 20.3]). A significant difference was observed for the mean TA values in the SBC+AB groups. Conclusion: It was concluded that all augmentation procedures investigated supported bone regeneration and staged osseointegration of modSLA titanium implants. However, the application of PEG may be associated with increased TA values. To cite this article:
Schwarz F, Mihatovic I, Golubovic V, Hegewald A, Becker J. Influence of two barrier membranes on staged guided bone regeneration and osseointegration of titanium implants in dogs: part 1. Augmentation using bone graft substitutes and autogenous bone.
Clin. Oral Impl. Res. 23 , 2012; 83–89.
doi: 10.1111/j.1600‐0501.2011.02187.x     

Immunoexpression of Cbfa‐1/Runx2 and VEGF in sinus lift procedures using bone substitutes in rabbits

Objectives: To analyze and compare the expression of core binding factor‐1 (Cbfa‐1)/Runx2 and vascular endothelium growth factor (VEGF) in sinus lift procedures using bovine hydroxyapatite (HA) and β‐tricalcium phosphate (β‐TCP). Material and Methods: Twenty‐four male rabbits that had undergone bilateral sinus lift procedures were divided into three groups, according to the sinus filling material: Group 1: autogenous bone graft; Group 2: bovine HA; and Group 3: β‐TCP. All groups were sacrificed after 7, 14, 30 and 60 days, for microscopic, histomorphometry and immunohistochemistry analysis. Results: Microscopic analysis showed a similar bone repair pattern between the tested groups. New bone formation, soft and medular tissue, remaining material or particulate bone graft area were obtained by histomorphometric analysis. After 14 days, statistically significant differences in new bone formation were found between Group 1 (27.76±7.8) and Groups 2 (14.22±3.2) and 3 (11.1±7.7). After 30 days, statistically significant differences (P<0.05) were detected in bone formation between Groups 1 (31.39±36.5) and 2 (14.13±3.2). The last period showed improved bone formation in Group 2. Also, Group 2 showed higher Cbfa‐1/Runx2 immunoexpression when compared with Group 3. No remarkable differences were observed in VEGF immunoexpression among groups. Conclusion: Taken together, both biomaterials allowed bone tissue growth in a conductive pattern and did not interfere with bone remodeling in the late period, with a slight improvement in bone tissue formation when using HA, confirmed by marked expression of Cbfa‐1 at initial periods. To cite this article:
Nunes LSS, De Oliveira RV, Holgado LA, Nary Filho H, Ribeiro DA, Matsumoto MA. Immunoexpression of Cbfa‐1/Runx2 in sinus lift procedures using bone substitutes in rabbits.
Clin. Oral Impl. Res. 21 , 2010; 584–590.
doi: 10.1111/j.1600‐0501.2009.01858.x     

Histologic analysis of clinical biopsies taken 6 months and 3 years after maxillary sinus floor augmentation with 80% bovine hydroxyapatite and 20% autogenous bone mixed with fibrin glue

Background: Bovine hydroxyapatite (Bio‐Oss®, Geistlich Pharmaceutical, Wollhausen, Switzerland) has been suggested to be used in maxillary sinus floor augmentation procedures prior to or in conjunction with implant placement. However, the long‐term histologic fate of this material is not well understood. Purpose: The aim with this study was to histologically evaluate the tissue response in patients to a mixture of bovine hydroxyapatite (BH), autogenous bone, and fibrin glue 6 months and 3 years after a maxillary sinus floor augmentation procedure. Materials and Method: Biopsies were taken from a group of 20 consecutive patients 6 months (n = 16) and 3 years (n = 12) after maxillary sinus floor augmentation with a mixture of BH (80%), autogenous bone (20%), and fibrin glue and prepared for histologic analysis. Results: Light microscopy and morphometry from biopsies taken after 6 months showed various amounts of mineralized bone tissue. The specimen area was occupied by 54.1 ± 12.6% nonmineralized tissue, followed by 21.2 ± 24.5% lamellar bone, 14.5 ± 10.3% BH particles, and 10.2 ± 13.4% woven bone. The nonmineralized tissue seen in bone‐forming areas consisted of a loose connective tissue, rich with vessels and cells. There were no signs of resorption of the BH particles. The lamellar bone appeared to have originated from the recipient site and was seldom in contact with the BH particles. After 3 years, the nonmineralized tissue area had decreased to 36.0 ± 19.0% (p > .05) and consisted mainly of bone marrow tissue. The surface area of lamellar bone had increased to 50.7 ± 22.8% (p > .05), and there was almost no immature bone. The mean specimen area occupied by BH particles, was 12.4 ± 8.7% and had not changed from 6 months (not significant). Moreover, the sizes of the particles were similar after 6 months and 3 years. The degree of BH particle–bone contact had increased from 28.8%± 19.9% after 6 months to 54.5 ± 28.8% after 3 years (p > .05). Conclusion: Histology of specimens from maxillary sinuses augmented with 80% BH particles, 20% autogenous bone, and fibrin glue showed a positive bone tissue response after 6 months and 3 years after augmentation of the maxillary sinus floor prior to implant placement in a group fo 20 patients. The bone surrounding and in contact with the BH particles after 6 months was mainly immature woven bone, which with time was replaced by mature lamellar bone filling the interparticle space as observed in the 3‐year specimens. Moreover, bone‐integrated BH particles seem to be resistant to resorption. The results indicate that the procedure may be considered when only small amounts of intraoral autogenous bone graft are available.     

Use of self-setting α-tricalcium phosphate for maxillary sinus augmentation in rabbit

Purpose: The purpose of this study was to histologically and immuno‐histochemically evaluate tissue changes in the maxillary sinus after bone screw implantation and maxillary sinus augmentation using self‐setting α‐tricalcium phosphate (α‐TCP; BIOPEX^®‐R) in rabbit. Study design: Adult male Japanese white rabbits (n=15, 12–16 weeks, 2.5–3 kg) were used. The sinus lift was made from the nasal bone of a rabbit. Bone screws (Dual top auto‐screw^®) were implanted into the nasal bone, and after BIOPEX^®‐R was implanted into the left elevated space (operated side) an atelocollagen sponge (ACS: Teruplug^®) was implanted into the right elevated space (control side). The rabbits were sacrificed at 4, 12 and 24 weeks postoperatively, and formalin‐fixed specimens were embedded in acrylic resin. The specimens were stained with hematoxylin and eosin. For immune‐histochemical analysis, the specimens were treated with bone morphogenetic protein‐2 (BMP‐2) antibodies. Finally, these were evaluated microscopically. Results: Tight bonding without fibrous tissue continued between the bone screw and BIOPEX^®‐R, and the rigidity of the bone screw in the nasal bone was retained for 24 weeks in all cases. The area ofnew bone formation increased gradually on both sides; however, there was no significant difference between both sides at 4, 12 and 24 weeks. The number of BMP‐2‐stained cells on the experimental side was significantly larger than that on the control side after 4 weeks (P=0.0361). Conclusion: This study suggested the usefulness of self‐setting α‐TCP (BIOPEX^®‐R) to maintain the rigidity of implanted bone screws from an early period, and the result of BMP‐2 expression suggested that BIOPEX^®‐R could have bone‐conductive activity in the maxillary sinus augmentation. To cite this article:
Marukawa K, Ueki K, Okabe K, Nakagawa K, Yamamoto E. Use of self‐setting α‐tricalcium phosphate for maxillary sinus augmentation in rabbit
Clin. Oral Impl. Res. 22 , 2011; 606–612
doi: 10.1111/j.1600‐0501.2010.02023.x