Platelet-rich plasma activity on maxillary sinus floor augmentation by autologous bone

OBJECTIVES: This work aims to evaluate the regenerative potential of platelet-rich plasma (PRP) on an implant site of peculiar clinical impact, such as sinus augmentation. MATERIAL AND METHODS: Sixteen consenting patients (11 females and five males), with symmetrical maxillary sinus atrophy, underwent bilateral sinus floor augmentation, using autologous (iliac crest) bone on one side and PRP plus autologous bone contralaterally. Implants were inserted 4, 5, 6 and 7 months after surgery in the patients randomly split into four groups. Orthopantomographies, computed tomography with transverse image digital reconstructions and densitometries were used to monitor the treatment progress. A core biopsy was performed at the site of implant. RESULTS: Clinical performance across both sites showed no statistical significance (P=0.414). Densitometric values were higher at PRP sites (mean Hounsfield units approximately +57%), even if densitometry converged in the two sites 8 months after surgery. Histology documents enhanced bone activities in sites treated with PRP, 4 months after surgery. Reduced bone activity was observed in both sites 5, 6 and 7 months after surgery. Bone amount, higher in sites treated with PRP (mean trabecular bone volume approximately +37%), decreased in both sites over time. CONCLUSIONS: Our results seem to indicate a certain regenerative potential of PRP when used with autologous bone. The effect of this enhancement of bone regeneration appeared to be restricted to shorter treatment times. A progressive extinguishment of the PRP effect is recorded after an interval longer than 6-7 months.     

基因强化组织工程骨用于上颌窦底提升的动物实验

目的 评价骨形态生成蛋白2( bone morphogenetic protein-2,BMP-2)基因强化骨髓间充质干细胞(bone marrow stromal cells,BMSC)复合Bio-Oss骨在上颌窦底提升术中的效果.方法 抽取12只犬髂部骨髓体外分离扩增BMSC,分别加入含BMP-2基因、绿色荧光蛋白(green fluorescent protein,GFP)基因的腺病毒载体共培养,观察转染效率,并植入裸鼠皮下观察成骨情况.将BMP-2基因强化BMSC-Bio-Oss复合骨随机植入犬一侧上颌窦底提升形成的空腔中为实验组,另一侧植入BMSC-Bio-Oss复合骨为空白对照组.分别于术后30、60、120 d行大体观察、CT检查、组织学检查和新生骨量分析.结果 裸鼠皮下可见新生骨,荧光显微镜示踪可见BMSC.犬上颌窦底提升30 d后,大体观察和CT检查示少量新骨形成,120 d后上颌窦内新骨生成致密,仅有少量Bio-Oss骨.新生骨量分析显示,与空白对照组[(19.67 ±5.73) mm2]相比,实验组新生骨量[(24.74±6.33) mm2]显著增多(P＜0.05).结论 BMP-2基因强化BMSC-Bio-Oss复合骨应用于上颌窦底提升术可获得良好的成骨效果.     

Bioactive glass granules as a bone adjunctive material in maxillary sinus floor augmentation

OBJECTIVES: Bilateral sinus floor augmentation procedure was performed in 17 patients to study the effect of bioactive glass (BG) granules mixed with autologous bone (AB) chips on bone regeneration. The posterior part of 17 maxillary sinus was augmented with a 1:1 mixture of BG granules (phi 800-1000 microm) and AB chips harvested from the iliac crest (BG-AB group). The anterior parts of the same sinus and the contralateral sinus, serving as a control (AB group), were filled with AB chips alone. Trephine biopsies for histological, scanning electron microscopy (SEM), and energy dispersive X-ray (EDX) analyses were taken from the posterior part of the sinus after 21-34 weeks at the time of insertion of dental implants. Additionally, six biopsies were taken from the BG-AB group and four biopsies were taken from the AB group in connection with abutment operation at 49-62 weeks. RESULTS: Histological evaluation revealed lamellar bone growth in all the specimens. Although most of the BG granules were without bone contact in the majority of the patients in the BG-AB group, the bone lamellae were thicker than observed in the AB group. In the contact areas, bone was growing along the glass surface connecting the particles together. Histomorphometrical analysis carried out from the SEM images at 21-34 weeks revealed 26% and 25% bone in the BG-AB and the AB group, respectively. Corresponding figures for 49-62 weeks were 29% for the BG-AB group and 25% for the AB group. Bone-BG complex, i.e. the granules with intimate contact with bone, occupied 34% of the area measured at 21-34 weeks and 31% at 49-62 weeks. EDX analysis showed a tight contact and chemical bonding between the glass and bone. As a sign of dissolution, a few small Si-depleted areas were present in some BG granules at 21-34 weeks, while more and larger Si-free areas were observed in the granules at 49-62 weeks. CONCLUSION: The results indicate that BG granules (S53P4) can be used together with AB chips for sinus floor augmentation procedure, thus decreasing the amount of bone needed. Further studies concerning especially the biomechanical properties of the BG-AB complex with dental implants are needed.     

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.     

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     

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.     

Bone reformation with sinus membrane elevation: a new surgical technique for maxillary sinus floor augmentation

Background: Various maxillary sinus floor augmentation techniques using bone grafts and bone substitutes are frequently used to enable placement of dental implants in the posterior maxilla. A previous case report demonstrated the possibility of promoting bone formation in the sinus by lifting the membrane without using a grafting material. However, the predictability of the technique is not known. Purpose: The aim of this study was to investigate whether sinus membrane elevation and the simultaneous insertion of titanium implants without additional grafting material constitute a valid technique for bone augmentation of the maxillary sinus floor. Materials and Methods: The study group comprised 10 patients in whom a total of 12 maxillary sinus floor augmentations were performed. A replaceable bone window was prepared in the lateral sinus wall with a reciprocating saw. The sinus membrane was dissected, elevated superiorly, and sutured to the sinus wall to create and maintain a compartment for blood clot formation. One to three dental implants were inserted through the residual bone and protruded at least 5 mm into the maxillary sinus. The bone window was replaced and secured with the overlying mucosa. Bone height was measured directly at each implant site at the time of insertion. Resonance frequency analysis (RFA) was performed on each implant at the time of initial placement, at abutment surgery, and after 12 months of functional loading. Computed tomography (CT) was performed in the immediate postoperative period and 6 months later, prior to exposure of the implants. Results: A total of 19 implants (Brånemark System®, TiUnite?, Nobel Biocare AB, Gothenburg, Sweden) in lengths of 10 to 15 mm were placed, with an average residual bone height of 7 mm (range, 4–10 mm). All implants remained clinically stable during the study period. Comparisons of pre‐ and postoperative CT radiography clearly demonstrated new bone formation within the compartment created by the sinus membrane elevation procedure. RFA measurements showed mean implant stability quotient values of 65, 66, and 64 at placement, at abutment connection, and after 12 months of loading, respectively. Conclusions: The study showed that there is great potential for healing and bone formation in the maxillary sinus without the use of additional bone grafts or bone substitutes. The secluded compartment created by the elevated sinus membrane, implants, and replaceable bone window allowed bone formation according to the principle of guided tissue regeneration. The precise mechanisms are not known, and further histologic studies are needed. Sinus membrane elevation without the use of additional graft material was found to be a predictable technique for bone augmentation of the maxillary sinus floor.     

Apical and marginal bone alterations around implants in maxillary sinus augmentation grafted with autogenous bone or bovine bone material and simultaneous or delayed dental implant positioning

Objective: A re‐pneumatization phenomenon was recorded in sinuses grafted with different materials. The specific aims of this paper were to assess the dental implant survival rate and the behavior of marginal and apical bone remodeling around dental implants placed following sinus augmentation. Materials and methods: A retrospective study was conducted on consecutive patients treated in two surgical centers. Different surgical techniques were adopted for sinus augmentation: simultaneous or delayed dental implant insertion with bovine bone‐material augmentation or autologous bone grafting (chin and iliac crest). Survival rates were recorded for the overall number of implants (patients of group A). Apical and marginal bone levels (ABL and MBL, respectively) were radiographically measured, and statistical analysis was performed in implants of a subgroup of patients (group B). Results: A total of 282 dental implants were positioned. Recorded cumulative survival rates (CSRs) were 95.6% and 100% for autogenous and bovine bone material, respectively, while CSRs at 2‐year follow‐up for immediate and delayed procedures were 99.3% and 96.5%. For the subgroup B, 57 sinus augmentation procedures were performed in 39 patients, with the positioning of 154 implants. Generally, the apical‐ and marginal‐bone resorption of the bovine bone‐material group was less than that of the autogenous group. The differences between the ABL values of the bovine bone‐material and iliac‐crest groups were statistically significant at 1 year, whereas this significance disappeared at the 2‐year follow‐up; tests showed that a statistical difference was recorded in the bovine bone‐material group between the 1‐ and 2‐year follow‐ups. With regard to MBL comparisons between simultaneous and delayed implantation, the differences maintained their significance at the 2‐year follow‐up also. Conclusions: Differences regarding apical bone alteration between autogenous bone from the iliac crest and bovine bone material at the 1‐ and 2‐year follow‐ups, as well as in the bovine bone‐material group between the 1‐ and 2‐year follow‐ups, attested to slower but more prolonged physiologic bone remodeling in the bovine‐graft‐material group than in the autogenous‐bone group. The MBL analysis showed that remodeling in the delayed implant group demonstrated a greater resorption in the cervical portion than was seen in the simultaneous implant group. To cite this article:
Sbordone L, Levin L, Guidetti F, Sbordone C, Glikman A, Schwartz‐Arad D. Apical and marginal bone alterations around implants in maxillary sinus augmentation grafted with autogenous bone or bovine bone material and simultaneous or delayed dental implant positioning.
Clin. Oral Impl. Res 22 , 2011; 485–491
doi: 10.1111/j.1600‐0501.2010.02030.x     

Retrospective analysis of time-related three-dimensional iliac bone graft resorption following sinus lift and vertical augmentation in the maxilla

The atrophic maxilla frequently requires bone grafting using an onlay graft (OG) or sinus lifting (SL) before implant rehabilitation. The resorption of bone grafts is influenced by the time until implantation, quality of donor bone, and grafting technique. The aim of this study was to investigate the impact of both grafting techniques on the time-related resorption of autologous iliac bone graft. Forty-three patients underwent either onlay grafting or a sinus lift at 73 sites in the maxilla. Graft height was measured by cone beam computed tomography after augmentation and during follow-up for up to 12 months prior to implant insertion. The effect of time and technique on graft resorption was evaluated retrospectively. The reduction in bone graft height was greater for OG than SL over the investigated time intervals (OG = 51%, SL = 28%; P = 0.002). Each technique followed a specific course of resorption, which was independent of the initial graft height and could be calculated by a non-linear regression model. Iliac bone graft undergoes rapid resorption when used as an OG prior to implant insertion. For SL, this resorption is reasonably lower. This is especially crucial to determine the optimal time for implant insertion after graft healing to improve implant survival.     

Implant survival rates after maxillary sinus augmentation

Implant therapy in the atrophic posterior maxilla becomes challenging in the presence of reduced maxillary bone height. Sinus augmentation can be performed for resolving this condition prior to implant placement. The aim of this article was therefore to evaluate implant survival rates in the grafted sinus taking into account the influence of the implant surface, graft material, and implant placement timing. A systematic review of the literature was performed. Articles retrieved from electronic databases were screened using specific inclusion criteria, and data extracted were divided according to: graft material (autogenous, non‐autogenous, composite graft), implant surface (machined or textured), and implant placement (simultaneous with grafting or delayed). Fifty‐nine articles were included. Survival rates for implants placed in grafts made of bone substitutes alone and grafts of composite material were slightly better than the survival rates for implants placed in 100% autogenous grafts. Over 90% of implants associated with non‐autogenous grafts had a textured surface. Textured surfaces achieved better outcomes compared with machined surfaces, and this was independent of the graft material. Simultaneous and delayed procedures had similar outcomes. It may be concluded that bone substitutes can be successfully used for sinus augmentation, reducing donor‐site morbidity. Long‐term studies are needed to confirm the performance of non‐autogenous grafts. The use of implants with a textured surface may improve the outcome in any graft type.     

Bone augmentation after soft‐tissue expansion using hydrogel expanders: effects on microcirculation and osseointegration

Objectives: The success of bone augmentation, for example of the alveolar ridge, might be endangered by dehiscence of the soft tissue that covers the augmented bone. Soft‐tissue coverage can be achieved without tension through pre‐augmentation tissue expansion with hydrogel expanders. We used a periosteal chamber to study the influence of tissue expansion on microcirculation and osseointegration in an in vivo animal model. Material and methods: Sixteen isogeneic Lewis rats were randomised into two groups. Additional eight animals served as donors of isogeneic bone grafts (Group 3, n=8). The bone grafts were harvested and implanted into Group 1 animals (n=8) (without tissue expansion) and Group 2 animals (after tissue expansion). In Group 2 (n=8), hydrogel expanders were inserted subperiosteally at the site to be augmented for 21 days. We used intravital microscopy to monitor microcirculation in vivo for 19 days after implantation. Specimens from both groups were evaluated histologically. Results: During the entire study period, functional microvessel density in the region above the augmentation material was significantly higher after previous tissue expansion (P>0.05). Both groups showed physiological microcirculation around the augmentation material. Histology revealed bone osseointegration of the bone graft in the group with tissue expansion and the presence of connective and granulation tissue in the group without tissue expansion. Conclusions: Pre‐augmentation soft‐tissue expansion with hydrogel expanders leads to higher functional microvessel density in the tissue above the augmentation material and thus, to more rapid osseointegration. The use of hydrogel expanders appears to increase the probability of success, especially of pre‐implant bone augmentation. To cite this article:
von See C, Gellrich N‐C, Jachmann U, Laschke MW, Bormann KH, Rücker M. Bone augmentation after soft‐tissue expansion using hydrogel expanders: effects on microcirculation and osseointegration.
Clin. Oral Impl. Res. 21 , 2010; 842–847
doi: 10.1111/j.1600‐0501.2009.01847.x     

上颌窦提升植骨在上颌后牙区种植术的临床应用

目的评价上颌窦提升、植入上颌结节自体骨加Bio-Oss骨粉在上颌后牙种植的方法和效果。方法对5例上颌后牙区垂直骨量不足患者行6侧上颌窦提升,植入上颌结节自体骨加Bio-Oss骨粉,同期种植体植入。结果6个月后X线片显示植骨区改建成新骨,种植体无松动脱落,与周围组织形成良好的骨性结合。结论上颌结节自体骨加Bio-Oss骨粉植入,提升上颌窦拓展了种植的应用范围。     

侧壁开窗上颌窦底提升术后垂直向骨增量的观察研究

目的通过观察侧壁开窗上颌窦底提升术后垂直向骨增量的变化情况,研究其相关的影响因素。方法收集上颌后牙区牙列缺损行侧壁开窗上颌窦底提升术分期种植患者资料,对纳入病例的术前剩余牙槽骨高度(residual bone height,RBH)、术后当日垂直向骨高度、术后6个月垂直向骨高度及垂直向骨增量的变化情况进行观察。结果术后6个月较术后当日垂直向骨高度有显著性降低,降低量为0.56±0.25mm;上颌窦底黏膜厚度的术后6个月较术后当日垂直向骨增量的变化量无明显差异;在不同剩余牙槽骨高度情况下,术后6个月较术后当日垂直向骨增量的变化量有统计学差异,RBH大于5mm的患者相对RBH小于5mm的患者垂直向骨增量的降低值显著增加;上颌窦宽度与术后6个月较术后当日垂直向骨增量的降低值呈正相关。结论侧壁开窗上颌窦底提升术后6个月较术后当日存在垂直向骨增量的降低现象;剩余牙槽骨高度大于5mm时垂直向骨增量的降低值显著增加;上颌窦宽度与垂直向骨增量的降低值呈正相关。     

Maxillary sinus augmentation model in rabbits: effect of occluded nasal ostium on new bone formation

This study was undertaken to establish an experimental model for maxillary sinus augmentation in rabbits and to clarify the bone response to the occluded nasal ostium. In rabbits without ostial occlusion, the elevation of the sinus mucosa resulted in formation of a subantral hollow space filled with blood clots and granulation tissue 1 week after operation. The newly formed bone filled in the space had a central granulation tissue. The space was almost completely replaced by a normal sinus airspace after 3 weeks. In rabbits with ostial occlusion, a fully formed bone mass was seen after 3 weeks. The mass had both mature trabeculae and peripheral cortical bone containing no sinus airspace after 6 weeks. This animal model for maxillary sinus augmentation may improve our understanding of the bone formation procedure in humans and delineate how sinus air pressure caused by the occluded nasal ostium affects the quantity and fate of newly formed bone.     

关于上颌窦底提升术骨增量策略的研究进展

上颌后牙区骨高度不足是种植手术常见的问题之一。而上颌窦底提升术拓宽了上颌后牙区种植的适应证。随着临床技术的进步和口腔材料学的发展,上颌窦底提升术的植骨策略不断更新。尽管上颌窦内的成骨机制尚未完全阐明,但上颌窦底提升术不植骨已经得到了越来越多的认可,如何选择和把握适应证是该策略的关键。经典传统的骨移植材料存在不同程度的缺陷,新型骨组织工程辅助材料应运而生,部分已得到临床应用。该文就上颌窦底提升术是否植骨、骨移植材料等方面的研究进展作一综述。