Sinus floor elevation using autogenous bone or bone substitute combined with platelet-rich plasma

Study of Elevation Forces and Resilience of the Schneiderian Membrane Using a New Balloon Device in Maxillary Sinus Elevations on Pig Head Cadavers

Background: Although elevation of the sinus can be considered a predictable procedure, it is nonetheless not free of complications, for which reason there is a constant search for new tools and techniques that may reduce these complications. The present study focused on maxillary sinus lifts performed on pig heads cadavers, using a new device with the balloon technique. Materials and Methods: Fifteen ex vivo adult pig heads were used in this experimental study. Sinus floor elevation was performed using the new balloon elevation control system, which consists of a syringe containing latex and serum as well as a system of burs for membrane access and control. Each lift was performed within a 3 min time frame while constant pressure was applied to allow the tissue to adapt to the tension. Results: In 100% of cases, perforations do not occur during aperture or in the elevation of the wall. In the global sample, there was histological elevation in 73.33% compared to 26.66% non-elevation (p = 0.0268). Conclusions: Within the limits of this study, the maxillary sinus lifts employing the new device and the balloon technique were minimally invasive procedures. The elevations achieved proved sufficient to allow future placement of implants of varying lengths and diameters without risk of perforating the membranes, even in the presence of crests of less than 1 mm.

Maxillary Sinus Floor Augmentation with Autogenous Bone Graft Alone Compared with Alternate Grafting Materials: a Systematic Review and Meta-Analysis Focusing on Histomorphometric Outcome

Objectives

The objective of present systematic review was to test the hypothesis of no difference in histomorphometric outcome after maxillary sinus floor augmentation with autogenous bone graft alone compared with alternate grafting materials applying the lateral window technique.

Material and Methods

MEDLINE (PubMed), Embase and Cochrane library search in combination with hand-search of relevant journals were conducted. Human studies published in English until the 25^th of March, 2020 were included. Histomorphometric outcomes were evaluated by descriptive statistics and meta-analysis including 95% confidence interval (CI).

Results

Electronic search and hand-searching resulted in 1902 entries. Sixteen randomized controlled trials with unclear risk of bias fulfilled the inclusion criteria. Descriptive statistics showed comparable or improved histomorphometric outcomes with autogenous bone graft. Meta-analysis revealed a mean difference of -7.1% (CI = -11.0 to -3.2) indicating a significant higher amount of bone after maxillary sinus floor augmentation with autogenous bone graft compared with alternate grafting materials. Subgroup analysis demonstrated a non-significantly differences of -3.7% (CI = -10.9 to 3.4), -11.5% (CI = -25.9 to 2.8), 2.2% (CI = -16.9 to 21.3), and -4.6% (CI = -14.4 to 5.2), when autogenous bone graft was compared with allogeneic bone graft, xenograft, composite grafting materials involving xenograft or synthetic biomaterial mixed with autogenous bone graft, respectively.

Conclusions

Maxillary sinus floor augmentation with autogenous bone graft seems to facilitate improved histomorphometric outcomes compared with alternate grafting materials. However, the included studies were characterised by an unclear risk of bias and various methodological confounding factors. Hence, the conclusions drawn from the results of present study should be interpreted with caution.

Hydroxyapatite from Fish for Bone Tissue Engineering: A Promising Approach

Natural or synthetic hydroxyapatite (HA) has been frequently used as implant materials for orthopaedic and dental applications, showing excellent bioactivity, adequate mechanical rigidity and structure, osteoconductivity and angiogenic properties, no toxicity, and absence of inflammatory or antigenic reactions. HA can be easily synthesized or extracted from natural sources, such as bovine bone. However, the manufacturing costs to obtain HA are high, restricting the therapy. Herein, much effort has been paid for obtaning alternative natural sources for HA. The potential of HA extracted from skeleton of animals has been investigated. The aim of this review is to exploit the potential of HA derived from fish to fulfill biological activities for bone tissue engineering. In particular, HA from fish is easy to be manufactured regarding the majority of protocols that are based on the calcination method. Furthermore, the composition and structure of HA from fish were evaluated; the biomaterial showed good biocompatibility as a result of non-cytotoxicity and handling properties, demonstrating advantages in comparison with synthetic ones. Interestingly, another huge benefit brought by HA from bone fish is its positive effect for environment since this technique considerably reduces waste. Certainly, the process of transforming fish into HA is an environmentally friendly process and stands as a good chance for reducing costs of treatment in bone repair or replacement with little impact into the environment.

Inlay osteotome sinus floor elevation with concentrated growth factor application and simultaneous short implant placement in severely atrophic maxilla

Sinus floor elevation with simultaneous implant placement in severely atrophic maxilla is challenging. The aim of this retrospective study was to evaluate the short-term performance of modified osteotome sinus floor elevation (OSFE) with concentrated growth factor (CGF) application and concurrent placement of a short implant in cases with residual bone height (RBH) of 2-4 mm. Twenty-five short implants were installed in 16 patients with mean RBH of 3.23 mm using modified OSFE with CGFs from January 2012 to April 2014. Postoperatively, the implants were clinically evaluated, and vertical bone gain (VBG) was measured using cone beam computed tomography. The mean duration of follow-up was 19.88 months (12-32 months). All the implants were stable with an overall survival rate of 100%. The mean VBG immediately after surgery was 9.21 mm. Six months later, significant reduction of alveolar bone height (2.90 ± 0.22 mm) was found (P < 0.05). During the second 6-month period, further alveolar bone resorption (0.14 ± 0.11 mm) was noted but without significance (P > 0.05). Within the limits of this study, modified OSFE with CGF application and simultaneous short implant placement could yield predictable clinical results for severely atrophic maxilla with RBH of 2-4 mm.

Effectiveness of platelet-rich plasma as an adjunctive material to bone graft: a systematic review and meta-analysis of randomized controlled clinical trials

The use of platelet-rich plasma (PRP) has become a strategic therapy in tissue regeneration medicine. PRP represents a good source of growth factors. Due to this property, it has been considered a reliable adjunctive material in bone augmentation procedures, such as the sinus lift technique. The aim of this review was to assess the scientific evidence on the effectiveness of PRP as an adjunctive material in the sinus floor elevation technique. The following databases were searched for relevant published studies: Medline, Cochrane Central Register of Controlled Trials, Cochrane Database of Systematic Reviews, CINAHL, Science Direct, ISI Web of Knowledge, and SCOPUS. Only randomized controlled clinical trials comparing a group receiving PRP as an adjunctive material to a control group without PRP, involving adult human subjects (age >18 years) with no systemic disease, were included. Of the studies identified, only one reported a significant difference in bone augmentation in favour of the adjunctive use of PRP, while four studies did not find any significant difference. None of the studies included reported a significant difference in the implant survival rate. Further randomized clinical trials are needed to clarify the effectiveness of adjunctive PRP.

Histomorphometric Analysis of Contaminated Autogenous Tooth Graft Materials After Various Sterilization

PURPOSE

The purpose of this study was to evaluate histomorphometrically contaminated autogenous tooth graft materials, which were resterilized.

MATERIALS AND METHODS

The intentional defects (diameter: 8 mm, depth: 4 mm) were formed around implant fixture on the iliac crest of 6 mongrel dogs. Autogenous tooth graft materials were made by extracted premolars. After the contamination of the tooth materials, graft procedure was performed; no contaminated group (control group), contaminated groups (nonsterilization group [group 1], ethylene oxide [EO] gas group [group 2], and autoclave group [group 3]). The bone-to-implant contact (BIC) and the new bone formation rate (NBFR) were evaluated after sacrifice.

RESULTS

The BIC and NBFR of groups 1 and 3 were significantly lower than the control group after 4 weeks. The BIC and NBRF of group 3 were significantly lower than the control group after 8 weeks. However, the BIC and NBRF of group 2 was not significantly different comparing with the control group after 4 and 8 weeks.

CONCLUSION

Sterilization using EO gas may be more favorable than high-pressure sterilization in cases the reuse of contaminated autogenous tooth graft materials.

Effects of platelet-rich plasma in association with bone grafts in maxillary sinus augmentation: a systematic review and meta-analysis

This systematic review evaluated the effect on bone formation and implant survival of combining platelet-rich plasma (PRP) with bone grafts in maxillary augmentation. A comprehensive review of articles listed in the PubMed/MEDLINE, Embase, and Cochrane Library databases covering the period January 2000 to January 2015 was performed. The meta-analysis was based on bone formation for which the mean difference (MD, in millimetres) was calculated. Implant survival was assessed as a dichotomous outcome and evaluated using the risk ratio (RR) with 95% confidence interval (CI). The search identified 3303 references. After inclusion and exclusion criteria were applied, 17 studies were selected for qualitative analysis and 13 for quantitative analysis. A total of 369 patients (mean age 51.67 years) and 621 maxillary sinus augmentations were evaluated. After the data analysis, additional analyses were performed of the implant stability quotient, marginal bone loss, and alveolar bone height measured by MD. The results showed no significant difference in implant stability (P=0.32, MD 1.00, 95% CI -0.98 to 2.98), marginal bone loss (P=0.31, MD 0.06, 95% CI -0.05 to 0.16), alveolar bone height (P=0.10, MD -0.72, 95% CI -1.59 to 0.14), implant survival (P=0.22, RR 1.95, 95% CI 0.67-5.69), or bone formation (P=0.81, MD -0.63, 95% CI -5.91 to 4.65). In conclusion, the meta-analysis indicates no influence of PRP with bone graft on bone formation and implant survival in maxillary sinus augmentation.

Platelet-Rich Plasma: A Study of the Variables that May Influence Its Effect on Bone Regeneration

BACKGROUND

Currently, the use of platelet-rich plasma in bone regeneration is a real option, although more than one opinion has alerted us to the absence of clinical benefits.

PURPOSE

Analysis of the factors able to modify the characteristics of the platelet preparation obtained by Curasan, Plasma Rich in Growth Factors (PRGF), Platelet Concentrate Collection System (PCCS) and SmartPrep systems, relating them to the type of clinical application and the final bone regeneration achieved.

MATERIALS AND METHODS

A search was conducted in PubMed using the keywords "platelet-rich plasma," "PRP," "platelet rich growth factors," and "oral bone regeneration." Four widely accepted protocols for the obtention of PRP (above) were analyzed. Any clinical studies with controls, using the four preparation protocols and with a 4 to 6 weeks follow-up period were compared. The protocols were also grouped according to the type of PRP application: PRP-alone, with bone, or with bone substitutes.

RESULTS

Bone regeneration was not achieved in any of the cases using PRP obtained by Curasan and PCCS systems, whereas PRP obtained by SmartPrep achieved it only in one in three published cases and PRGF in one in six.

CONCLUSION

Based on the poor results observed in current literature, the use of PRP in oral surgery cannot be recommended.

Concentration of platelets and growth factors in platelet-rich plasma from Goettingen minipigs

In minipigs little is known about the concentration of growth factors in plasma, despite their major role in several patho-physiological processes such as healing of fractures. This prompted us to study the concentration of platelets and selected growth factors in plasma and platelet-rich plasma (PRP) preparation of sixteen Goettingen minipigs.

Platelet concentrations increased significantly in PRP in comparison to native blood plasma. Generally, significant increase in the concentration of all growth factors tested was observed in the PRP in comparison to the corresponding plasma or serum. Five of the plasma samples examined contained detectable levels of bone morphogenic protein 2 (BMP-2) whereas eleven of the plasma or serum samples contained minimal amounts of vascular endothelial growth factor (VEGF) and platelet-derived growth factor (PDGF-bb) respectively. On the other hand variable concentrations of bone morphogenic protein 7 (BMP-7) and transforming growth factor β1 (TGF-β1) were measured in all plasma samples. In contrast, all PRP samples contained significantly increased amounts of growth factors. The level of BMP-2, BMP-7, TGF-β1, VEGF and PDGF-bb increased by 17.6, 1.5, 7.1, 7.2 and 103.3 fold, in comparison to the corresponding non-enriched preparations. Moreover significant positive correlations were found between platelet count and the concentrations of BMP-2 (r=0.62, p<0.001), TGF-β1 (r=0.85, p<0.001), VEGF (r=0.46, p<0.01) and PDGF-bb (r=0.9, p<0.001). Our results demonstrate that selected growth factors are present in the platelet-rich plasma of minipigs which might thus serve as a source of autologous growth factors.

Histomorphometric analysis of bone formation in bony defects around implants in adult dogs: a comparison of grafts of low and high heat-treated autogenous tooth ash

PURPOSE

The purpose of this study was to compare the bone formation of autogenous tooth ash treated with different temperatures.

MATERIALS AND METHODS

Heat treatment was rendered by powder after extraction of teeth from dogs. The bony defects were made at iliac and resorbable blast medium surfaced implant placement and bone graft was performed; no bone graft group (control group), low heat-treated tooth ash group (group 1), high heat-treated tooth ash group (group 2). Right side had healing periods of 12 weeks, and the left side had 6 weeks. Histomorphometrical analysis was performed at 12 weeks.

RESULTS

The control group had poor bone formation and showed large loose connective tissue. Group 1 displayed good healing and bone formation. Group 2 showed higher rate of bone formation than group 1 and the control group. The high heat-treated tooth ash group showed a statistically significant increase in the rate of bone formation in the early stage.

CONCLUSION

The heat-treated autogenous tooth ash powder showed excellent new bone formation. The temperature of heat treatment is an important factor in new bone formation. The high heat treatment was the optimal treatment method for making tooth ash than the low heat treatment.

Experimental study of the effect of autologous platelet-rich plasma on the early phases of osteoinduction by allogenic demineralized bone matrix

PURPOSE

To evaluate the effect of autologous platelet-rich plasma (PRP) on the early phases of osteoinduction by allogenic demineralized bone matrix (DBM) in rabbit intramuscular positions.

MATERIALS AND METHODS

Allogenic DBM was produced from bones of 3 healthy rabbits. In each of 6 experimental animals, 0.3 mL autologous PRP was prepared and 2 muscle pouches were created, where 250 mg DBM + PRP (experimental sites) and 250 mg DBM without PRP (control sites) were randomly implanted. Animals were euthanized 3 weeks postoperatively.

RESULTS

Histologic examination revealed uneventful healing in all cases, whereas remineralization of the periphery of the bone graft particles was a constant finding. In both control and experimental sites, fibroblasts and other mesenchymal cells (probably osteoprogenitor cells and preosteoblasts) were observed. The main histological difference was the recolonization of the empty lacunae of the bone graft particles by osteocytes at the control sites. The degradation of the graft at the control sites was statistically significantly quicker, although a statistically significant difference regarding the amount of the newly formed fibrous connective tissue was not observed.

CONCLUSION

The present study demonstrated that in this experimental model, the addition of PRP to DBM had a negative effect on the early phases of osteoinduction at 3 weeks of observation.

The pig as an experimental model for clinical craniofacial research

The pig represents a useful, large experimental model for biomedical research. Recently, it has been used in different areas of biomedical research. The aim of this study was to review the basic anatomical structures of the head region in the pig in relation to their use in current research. Attention was focused on the areas that are frequently affected by pathological processes in humans: the oral cavity with teeth, salivary gland, orbit, nasal cavity and paranasal sinuses, maxilla, mandible and temporomandibular joint. Not all of the structures have an equal morphology in the pig and human, and these morphological dissimilarities must be taken into account before choosing the pig as an experimental model for regenerative medicine.

Platelet-rich growth factor in oral and maxillofacial surgery

Platelet-rich growth factor is an innovative regenerative therapy used to promote hard and soft tissue healing. It involves the application of autologous platelet-leukocyte-rich plasma containing growth factors and thrombin directly to the site of treatment. It is the intrinsic growth factors released by activated platelets which are concentrated in a topical gel formula. Clinically, it is an affordable treatment with potentially broad spectrum of applications in maxillofacial surgery especially in the treatment of complex or refractory wounds. The present article reviews its various applications not only in the specialization of oral and maxillofacial surgery but also in regenerative medicine.

Histological results after maxillary sinus augmentation with Straumann® BoneCeramic, Bio-Oss®, Puros®, and autologous bone. A randomized controlled clinical trial

OBJECTIVE

This investigation focused on a comparison of clinical and histological characteristics after sinus floor augmentation with biphasic calcium phosphate (BCP, Straumann BoneCeramic(®) ), anorganic bovine bone (ABB, Geistlich Bio-Oss(®) ), mineralized cancellous bone allograft (MCBA, Zimmer Puros(®) ), or autologous bone (AB).

MATERIALS AND METHODS

Thirty consecutive patients with a posterior edentulous maxillary situation and a vertical bone height less than or equal to 4 mm were included in this study. A two-stage procedure was carried out. After augmentation of the maxillary sinus with ABB, BCP, MCBA, or AB followed by a healing period of 5 months, biopsies were taken with simultaneous implant placement. The samples were analyzed using microradiography and histology.

RESULTS

Ninety-four implants were placed in the augmented positions and 53 bone biopsies were taken and evaluated. The bone volume fraction of newly formed bone was measured as 30.28 ± 2.16% for BCP, 24.9 ± 5.67% for ABB, 41.74 ± 2.1% for AB, and 35.41 ± 2.78% for MCBA with significant increases in bone volume of AB vs. BCP and ABB, and MCBA vs. ABB samples. Significantly different residual bone substitute material was measured as 15.8 ± 2.1% in the BCP group and 21.36 ± 4.83% in the ABB group.

CONCLUSION

As it provides the highest rate of de novo bone formation, AB can be considered to remain the gold standard in sinus floor augmentation. All tested control materials showed comparable results and are suitable for maxillary sinus augmentation.

Does platelet-rich plasma accelerate recovery after rotator cuff repair? A prospective cohort study

BACKGROUND

Platelet-rich plasma (PRP) has been recently used to enhance and accelerate the healing of musculoskeletal injuries and diseases, but evidence is still lacking, especially on its effects after rotator cuff repair.

HYPOTHESIS

Platelet-rich plasma accelerates recovery after arthroscopic rotator cuff repair in pain relief, functional outcome, overall satisfaction, and enhanced structural integrity of repaired tendon.

STUDY DESIGN

Cohort study; Level of evidence, 2.

METHODS

Forty-two patients with full-thickness rotator cuff tears were included. Patients were informed about the use of PRP before surgery and decided themselves whether to have PRP placed at the time of surgery. Nineteen patients underwent arthroscopic rotator cuff repair with PRP and 23 without. Platelet-rich plasma was prepared via plateletpheresis and applied in the form of a gel threaded to a suture and placed at the interface between tendon and bone. Outcomes were assessed preoperatively and at 3, 6, 12, and finally at a minimum of 16 months after surgery (at an average of 19.7 ± 1.9 months) with respect to pain, range of motion, strength, and overall satisfaction, and with respect to functional scores as determined using the following scoring systems: the American Shoulder and Elbow Surgeon (ASES) system, the Constant system, the University of California at Los Angeles (UCLA) system, the Disabilities of the Arm, Shoulder and Hand (DASH) system, the Simple Shoulder Test (SST) system, and the Shoulder Pain and Disability Index (SPADI) system. At a minimum of 9 months after surgery, repaired tendon structural integrities were assessed by magnetic resonance imaging.

RESULTS

Platelet-rich plasma gel application to arthroscopic rotator cuff repairs did not accelerate recovery with respect to pain, range of motion, strength, functional scores, or overall satisfaction as compared with conventional repair at any time point. Whereas magnetic resonance imaging demonstrated a retear rate of 26.7% in the PRP group and 41.2% in the conventional group, there was no statistical significance between the groups (P = .388).

CONCLUSION

The results suggest that PRP application during arthroscopic rotator cuff repair did not clearly demonstrate accelerated recovery clinically or anatomically except for an improvement in internal rotation. Nevertheless, as the study may have been underpowered to detect clinically important differences in the structural integrity, additional investigations, including the optimization of PRP preparation and a larger randomized study powered for healing rate, are necessary to further determine the effect of PRP.

Application of platelet-rich plasma for enhanced bone regeneration in grafted sinus

PURPOSE

The present study was conducted to evaluate the effect of platelet-rich plasma (PRP) on new bone formation and remodeling after grafting of the maxillary sinus with an algae-derived hydroxyapatite AlgOss/C Graft/Algipore.

MATERIALS AND METHODS

Fourteen consecutive patients with severely atrophic maxillae underwent uni- or bilateral grafting of the maxillary sinus with a mixture of collected bone, algae-derived hydroxyapatite AlgOss/C Graft/Algipore (ratio 1:10), and a combined addition of PRP and thrombin (Tissucol Kit; Baxter, Vienna, Austria) to allow for fast clotting. After an average healing period of 7.1 months bone samples were retrieved. Patients from a former consecutive series treated without PRP served as control group. Statistical analysis was done by Welch 2-sample t test and mixed linear model testing.

RESULTS

In the coronal specimen portions, mean values for newly formed bone area, biomaterial area and marrow space of 32.2% ± 10.4%, 20.1% ± 13.0%, and 47.7% ± 8.5% were found with PRP, respectively. In the control group the corresponding values were 27.6% ± 13.4%, 20.3% ± 12.9%, and 52.1% ± 9.3%. In the apical specimen portions in the PRP group, the newly formed bone area, biomaterial area, and marrow space was 25.7% ± 15.0%, 23.4% ± 14.9%, and 50.9% ± 12.5%, respectively. The corresponding values in the control group were 17.0% ± 8.6%, 34.5% ± 11.2%, and 48.5% ± 8.5%.

CONCLUSIONS

Statistical evaluation of the samples proved significantly better overall resorption of algae-derived hydroxyapatite AlgOss/C Graft/Algipore and increased new bone formation when PRP was used, especially in the apical region.

The effect of bovine bone graft with or without platelet-rich plasma on maxillary sinus floor augmentation

PURPOSE

The purpose of this study was to compare Unilab Surgibone (USB) (Mississauga, Ontario, Canada), a bone xenograft (bovine), with platelet-rich plasma (PRP) and USB without PRP to augment the human maxillary sinus in preparation to receive dental implants.

PATIENTS AND METHODS

Patients who had bilateral pneumatized maxillary sinuses were included. Sinuses on one side were augmented with the USB-PRP combination and formed the study group, whereas the opposite-side sinuses were augmented with USB alone and served as controls. Bone biopsy specimens were taken during implant placement at 6.8 ± 0.9 months after maxillary sinus floor augmentation. Resonance frequency analysis measurements were performed at implant placement (first control) and before the prosthetic stage (second control), at 6.5 ± 0.7 months after implant surgery.

RESULTS

There were 10 patients (7 men and 3 women; mean age, 53.7 ± 0.8 years). Integration between new bone and residual grafts was histologically observed in all samples. The volumes of soft tissue were 59.9% ± 7.5% and 57.8% ± 4.4% in the control and study groups, respectively; residual graft, 21.9% ± 6.6% and 23.6% ± 5.9%, respectively; new bone, 15.8% ± 4.8% and 16.0% ± 3.8%, respectively; and trabecular bone, 64.7% ± 22.5% and 69.1% ± 18.6%, respectively. A positive correlation was found between new bone volume and trabecular bone volume (P = .0001). The mean Implant Stability Quotient (ISQ) values were 71.7 ± 4.9 and 70.3 ± 5.7 in the control and study groups, respectively, at first control and 75.4 ± 6.4 and 74.4 ± 6.4, respectively, at second control. The mean ISQ values at second control in both groups were significantly higher than at first control (P = .043 and P = .028, respectively). No statistically significant differences were observed between groups (P > .05).

CONCLUSION

The combination of USB and PRP does not have any effect on new bone formation and implant stabilization.

Platelet-rich plasma in sinus augmentation procedures: a systematic literature review: Part II

BACKGROUND

Although platelet-rich plasma (PRP) has been extensively studied for over a decade, there are no definitive reports, which prove the benefit of using PRP in sinus augmentation procedures. In addition, no systematic literature review has been done to report the benefit of treatment outcome in patients who received PRP in conjunction with bone/bone substitutes in maxillary sinus augmentation procedures. Therefore, it can be rightly stated that evidence for an adjunctive benefit of using PRP with bone grafts in sinus augmentation procedures is equivocal and inconclusive.

AIM

: The objective of this systematic literature review was to examine this literature in determining whether PRP with bone and bone substitutes leads to more rapid and effective bone regeneration clinically, radiographically, and histologically with sinus augmentation procedures and was there any clinical data parallel to animal experiments providing clinical evidence in sinus augmentation procedures?

METHODS

A systematic review of randomized clinical trials of at least 6 months duration was conducted comparing PRP and bone/bone substitutes (test group) to bone/bone substitutes (control group) alone. Electronic databases such as MEDLINE and CENTRAL (Cochrane central register of controlled clinical trials) were searched for relevant articles. The reference list of all included articles was searched along with unpublished clinical trials whose abstracts were available.

RESULTS

Although, there is a lack of human studies, which show benefit of using PRP in conjunction with bone grafting materials, it can be stated that use of PRP does lead to early regeneration and reduction in healing time of soft and hard tissues. However, no significant statistical or clinical benefit was reported from studies that would satisfy the inclusion criteria. This study answers the question very clearly that at this point of time, there is no human study that strongly supports the benefit of using PRP in sinus augmentation procedures.

CONCLUSION

There is a paucity of clinically controlled trials regarding benefits of PRP in sinus augmentation procedures. Theoretically, it seems to have significant beneficial effects on the soft and hard tissue healing; however, the disparity in study design, surgical techniques, and different outcome assessment variables used, makes it difficult to assess the practical benefit of its clinical use. Although no obvious positive effects of PRP on healing of bone graft material in maxillary sinus augmentation procedures were noted, the handling of the particulate bone grafts was improved.

The design and use of animal models for translational research in bone tissue engineering and regenerative medicine

This review provides an overview of animal models for the evaluation, comparison, and systematic optimization of tissue engineering and regenerative medicine strategies related to bone tissue. This review includes an overview of major factors that influence the rational design and selection of an animal model. A comparison is provided of the 10 mammalian species that are most commonly used in bone research, and existing guidelines and standards are discussed. This review also identifies gaps in the availability of animal models: (1) the need for assessment of the predictive value of preclinical models for relative clinical efficacy, (2) the need for models that more effectively mimic the wound healing environment and mass transport conditions in the most challenging clinical settings (e.g., bone repair involving large bone and soft tissue defects and sites of prior surgery), and (3) the need for models that allow more effective measurement and detection of cell trafficking events and ultimate cell fate during the processes of bone modeling, remodeling, and regeneration. The ongoing need for both continued innovation and refinement in animal model systems, and the need and value of more effective standardization are reinforced.

Angiogenic factor-enriched platelet-rich plasma enhances in vivo bone formation around alloplastic graft material

PURPOSE

Although most researchers agree that platelet-rich plasma (PRP) is a good source of autogenous growth factors, its effect on bone regeneration is still controversial. The purpose of this study was to evaluate whether increasing angiogenic factors in the human PRP to enhance new bone formation through rapid angiogenesis.

MATERIAL AND METHODS

In vitro, the human platelets were activated with application of shear stress, 20 µg/ml collagen, 2 mM CaCl(2) and 10U thrombin/1 × 10(9) platelets. Level of vascular endothelial growth factor (VEGF) and platelet microparticle (PMP) in the activated platelets were checked. In the animal study, human angiogenic factors-enriched PRP was tested in 28 athymic rat's cranial critical bone defects with β-TCP. Angiogenesis and osteogenesis were evaluated by laser Doppler perfusion imaging, histology, dual energy X-ray densinometry, and micro-computed tomography.

RESULTS

In vitro, this human angiogenic factors-enriched PRP resulted in better cellular proliferation and osteogenic differentiation. In vivo, increasing angiogenic potential of the PRP showed significantly higher blood perfusion around the defect and enhanced new bone formation around acellular bone graft material.

CONCLUSION

Angiogenic factor-enriched PRP leads to faster and more extensive new bone formation in the critical size bone defect. The results implicate that rapid angiogenesis in the initial healing period by PRP could be supposed as a way to overcome short term effect of the rapid angiogenesis.

Effect of Tisseel on bone healing with particulate dentin and plaster of Paris mixture

OBJECTIVES

The purpose of this study was to evaluate the effect of Tisseel on the early healing of bone defects in the skulls of rats.

STUDY DESIGN

Forty-eight rats were randomly assigned to 4 groups, and each group was further divided into 3 subgroups which were examined at 4 and 8 weeks after the defects were filled. The 4 different groups were animals containing: no graft (group 1); particulate dentin and plaster of Paris mixture graft (group 2); Tisseel and particulate dentin and plaster of Paris mixture graft (group 3); and Tisseel graft (group 4). After killing the animals at 4 and 8 weeks after surgery, all implant blocks were prepared for histologic sections and histomorphometric analysis.

RESULTS

The overall new bone formation was significantly different between the 4-week samples and the 8-week samples. Significant differences between groups 1 and 2, groups 1 and 3, groups 1 and 4, groups 2 and 4, and groups 3 and 4 were observed at 4 weeks after surgery. At 8 weeks after surgery, significant differences between groups 1 and 2, groups 1 and 3, groups 1 and 4, and groups 2 and 4 were observed. As expected, effective bone formation was observed when the defects were filled with either particulate dentin, Tisseel, or particulate dentin-Tisseel combination. It was also observed from this study that particulate dentin is especially effective, followed by the particulate dentin-Tisseel combination and Tisseel.

CONCLUSION

It was concluded that the use of Tisseel may be an alternative therapy for regenerating bone in defects when used in combination with particulate dentin.

Particulate inlay nasal graft with immediate dental implant placement in a patient with repaired alveolar cleft: case report

Primary bone grafts in congenital cleft alveolus do not always provide sufficient bulk or height of bone for ideal placement of endosseous implants. Thus, maxillary sinus or nasal floor elevation and inlay bone grafts in previously grafted areas are not exceptions in the daily routine. This case report stresses the need of a detailed treatment plan and careful surgical management of nasal floor elevation with particulate autogenous bone graft to successfully provide the patient with osseointegrated prostheses.

Sinus lift augmentation using autogenous bone grafts and platelet-rich plasma: radiographic results

OBJECTIVES

Autologous bone grafting and sinus floor elevation is a widely accepted method for reconstruction of the atrophic maxilla. The aim of this investigation was to examine the influence of platelet-rich plasma (PRP) on bone grafting in sinus floor augmentation.

STUDY DESIGN

A prospective, controlled, randomized study including 34 patients undergoing sinus augmentation before implant placement was designed. The intervention group had additional treatment with PRP. Radiographic imaging was performed by computerized tomography (CT) and panoramic radiography 4 months after augmentation and before implant placement.

RESULTS

Bone density showed no significant increase when PRP was used in combination with autologous bone grafting compared with autologous bone alone.

CONCLUSIONS

This study showed no positive effect of PRP on bone density in CT evaluation when used in sinus floor augmentation. Bone density in the CT showed no correlation to histomorphometric evaluation.

Preparation of highly concentrated and white cell-poor platelet-rich plasma by plateletpheresis

BACKGROUND AND OBJECTIVES

Contaminating white blood cells (WBC) contribute remarkably to the overall growth factor content of locally applicable platelet-rich plasma (PRP) or platelet (PLT) gel and change the relative proportions of the contained growth factors.

MATERIALS AND METHODS

To study the independent effects of locally applicated highly concentrated PLTs, the development of preparations is needed that contain large amounts of PLTs and no or at least very few leucocytes. Therefore, 20 plateletpheresis procedures were performed in voluntary blood donors to get highly concentrated and extremely WBC-poor plateletpheresis concentrates. The degree of spontaneous PLT activation, the PLT aggregation response to agonists and the level of the growth factor TGF-beta1 (transforming growth factor beta1) were measured immediately after the donation and 1 day later.

RESULTS

The concentrates contained 1.96 +/- 0.36 x 10e11 PLTs per unit in 55.2 +/- 7.9 ml, respectively. In comparison to the donors' blood, the PLT-enrichment factor was 15.3 +/- 5.4. At the same time, the concentrates contained extremely low residual numbers of WBCs (0.8 +/- 3.3 x 10e3/ml). The concentration of the growth factor TGF-beta1 was 743.2 +/- 243.9 ng/ml. On day 1, the PLT concentration and the TGF-beta1 content of the PLT concentrates had not decreased.

CONCLUSIONS

In summary, plateletpheresis is suited to provide PRP products with higher concentrations of human platelets and platelet-derived growth factors than previously reported PRP preparation methods but with extremely low numbers of contaminating leucocytes.