Particulate Allografts (DFDBA) Combined with Platelet Concentrate: An Effective Combination for Sinus Lifts and Post-Extraction Bone Grafting

Abstract

Alveolar bone resorption after tooth extraction can lead to considerable loss of bone volume, which can complicate dental implant planning. To limit this bone loss, immediate post-extraction bone grafting is recommended, while maxillary sinus grafting may be necessary in cases of insufficient sub-sinusal bone height. The use of a combination of particulate Demineralized Freeze-Dried Bone Allograft (DFDBA) and platelet concentrates, such as Platelet-Rich-Fibrin (PRF), has shown promising results in alveolar bone preservation after teeth extractions, as well as in sinus bone grafts (sinus lifts). We conducted several studies, both clinical and histomorphological, to find out if the use of this combination of biomaterials could lead to good bone quantity and quality, and be suitable for implants. Following the results of our studies, the use of particulate DFDBA combined with PRF, whether for alveolar bone preservation after dental extractions or sinus lifts, appears to be an effective technique to maintain or recreate bone volume for dental implant placement. Moreover, histomorphometric study shows a good quality and a good maturity of bone gained with this technique.

1. Introduction

Bone resorption of the maxilla related to tooth loss: The alveolar bone resorption that occurs after tooth extraction is a gradual, inevitable, and irreversible physiological phenomenon. According to studies, this resorption leads to a loss of bone height and thickness of up to 40% and 60%, respectively. The maximum resorption occurs within 3 months to 1 year after extraction, with two-thirds occurring in the first 3 months [1, 2, 3].

In the region of single-rooted teeth, resorption occurs mainly in a horizontal direction, while in the region of multi-rooted teeth, it predominantly occurs vertically (Figure 1) [1, 2, 3]. In the posterior part of the maxilla, this bone resorption is accompanied by a centrifugal pneumatization of the maxillary sinuses that increases with age [4]. The result of this phenomenon is a significant reduction in residual sub-sinus bone height, which may compromise implant placement in this area.

Figure 1.

Single-rooted tooth (1): Bone resorption with a predominant horizontal direction (red arrow). In multi-rooted teeth (2), resorption mainly occurs in a vertical direction, both in the lower level of bone (black arrow) and in the upper level due to pneumatization of the maxillary sinuses resulting from the loss of root support (blue arrow).

In a retrospective study of 248 edentulous patients, it was observed that less than half of the maxillae of patients over 65 years old have a bone height greater than or equal to 6 mm [4]. Post-extractional resorption can lead to a situation of bone volume loss that may compromise the implant treatment plan. Moreover, in some cases, it results in a modification of the relationships between the bone ridges due to centripetal resorption in the upper maxilla (Figure 2), which leads to an unfavorable situation in terms of biomechanics and esthetics.

Figure 2.

Clinical view, panoramic radiograph, and CT scan: Centripetal resorption of the upper alveolar crest, resulting in an anteroposterior displacement of the upper crest relative to the lower crest and an inverted maxillary relationship in the direction of an Angle class III.

It has been shown that post-extraction bone volume loss results from two phenomena: loss of the fasciculated bone [2, 3] and colonization of the upper third of the dental alveolus by connective tissue which has the effect of reducing the available space for bone healing [2, 3, 4]. There is currently a consensus on the need to perform post-extraction bone filling immediately after extractions to achieve the most optimal bone preservation [1, 2, 3, 5, 6], in order to minimize the bone loss that follows dental extractions and to ensure the best possible bone conditions for patient implant rehabilitation. When there is insufficient sub-sinus bone height, it is necessary to resort to a maxillary sinus graft prior to implant placement in this area [7, 8].

2. Techniques used in oral surgery to avoid post-extraction bone volume loss or increase sub-sinus bone volume

Alveolar ridge preservation and maxillary sinus graft techniques are based on filling respectively the empty alveolus or the space between the sinus floor and the Schneider membrane with biocompatible material, with or without adjuncts, with or without a covering membrane.

2.1 Biomaterials used in oral surgery

Biomaterials used in oral surgery are classified into two categories: Natural origin biomaterials and synthetic origin biomaterials.

2.1.1 Synthetic origin biomaterials

Synthetic origin biomaterials include tricalcium phosphate, hydroxyapatites, biphasic ceramics, bioactive glasses, and polymers [9]. Tricalcium phosphates (ßTCP) Ca3(PO4)2 are produced by heating a mixture of calcium phosphate powder and naphthalene to over a thousand degrees and under pressure, which, after sublimation, leaves a porous structure that is responsible for the material’s osteoconductive properties. Porous hydroxyapatite Ca10(PO4)6(OH)2 is obtained by the thermal transformation of calcium carbonate. Chemically, this calcium phosphate is the closest to biological apatite crystals. Several porosities are available. The higher the porosity, the better the osteoconduction. Biphasic ceramics (BCP) comprise a combination of hydroxyapatite and tricalcium phosphate in varying proportions, allowing the qualities of both materials to be combined, particularly to obtain adequate resorption and mechanical properties. Bioactive glasses, SiO2P2O5CaONaO, are materials known as “bioactive.” This “bioactivity” would be due to surface reactions of the bioactive glass and ionic exchanges with biological fluids. The os/bioactive glass bond would be made through a layer of amorphous silica gel that exerts a chemotactic effect on osteoblasts. Polymers, notably polymethylmethacrylate (PMMA), have excellent biocompatibility.

2.1.2 Natural biomaterials natural include xenogeneic bone, natural coral, and allogenic bone

Xenogeneic bone (xenograft) is most commonly derived from pigs or cows. Inorganic bovine bone retains a bone spatial structure, giving it osteoconductive properties. These products are presented in a lyophilized form [9, 10]. Natural coral is composed of 99% calcium carbonate. After thermal treatment, it retains a porous structure that gives it osteoinductive properties [9, 10]. Allogeneic bone substitutes are produced from femoral head bone taken from fresh human cadavers. Compared to autogenous bone, they have the advantage of not requiring bone harvesting from the patient (as autogenous bone harvesting carries an increased risk of postoperative morbidity). There are two types of allografts depending on the treatment applied to the harvested bone: lyophilized allograft called Freeze-Dried Bone Allograft (FDBA) and demineralized lyophilized allograft called Demineralized Freeze-Dried Bone Allograft (DFDBA) or Demineralized Bone Matrix (DBM). To obtain FDBA, the harvested bone undergoes a series of treatments [11]: elimination of residual muscular and fibrous tissues, size reduction to obtain particles of 5 mm, first decontamination, microbial treatment with antibacterial, antifungal and antimycotic solutions, freezing in liquid nitrogen at −80°C, dehydration by lyophilization, second size reduction of particles, packaging in a sterile container, and finally sterilization with gamma rays to reduce the risk of contamination. FDBA will mainly serve as a matrix for bone regeneration: osteoconduction.

For the DFDBA, the treatment sequence is similar but with an additional demineralization phase in a bath of hydrochloric acid following the second reduction in particle size. The DFDBA has osteoconductive properties, meaning it serves as a scaffold for the colonization of the recipient site by various types of cells and growth factors, and some authors have shown that it has osteoinductive properties, meaning it may allow for new bone formation. This is due to the presence of Bone Morphogenetic Proteins (BMPs) within the bone matrix [12, 13]. As the bone is resorbed, growth factors including BMPs, which belong to the TGF β superfamily and were first isolated in the 1960s by American orthopedic surgeon Marshal Urist, are released. BMPs, especially isoforms 2, 3, 4, and 7, play a crucial role in bone healing by stimulating the differentiation of mesenchymal stem cells into bone cells [13].

The ability of DFDBA to be osteoconductive and osteoinductive is influenced by various factors such as the age of the donor (better between 41 and 50 years for men and 51 and 60 years for women), the particle size which should be between 500 and 710 μm to ensure optimal effects, the residual calcium content (optimal osteoinduction occurs when the percentage of residual calcium is 2%) [14], as well as the methods of preparation, sterilization, and preservation [15]. It has been shown that there is a large variation in the amounts of extracted proteins within different lots of DFDBA, and the authors have hypothesized that some proteins may be degraded within certain lots of DFDBA or present in too small quantities within the bone matrix to be detectable by their method [13].

2.1.3 Autologous platelet concentrates as surgical adjuvants

The use of autologous platelet concentrates (PRP and PRF) in oral and implant surgery aims to accelerate and improve the healing process, particularly in surgical procedures for bone regeneration [16]. Platelet Rich Plasma (PRP), introduced by Marx et al. in 1998, is obtained through two successive centrifugations in tubes containing citrate dextrose A anticoagulant (to prevent platelet activation and degranulation). The platelet concentrate is instantaneously gelled by the addition of bovine thrombin, recombinant human thrombin, or recombinant human tissue factor, which triggers platelet activation and fibrin polymerization [17].

Authors have developed a simplified protocol to obtain an autologous platelet concentrate without the use of anticoagulants or thrombin, called Platelet-Rich-Fibrin (PRF) [18]. Venous blood collected without anticoagulant is immediately centrifuged for 10 to 12 minutes at 2700–3000 rpm. The authors obtain three successive layers from the bottom to the surface of the tube: red blood cells, a PRF clot rich in platelets, and on the surface, acellular plasma rich in fibrin (Figure 3).

Figure 3.

Blood tubes collected from the patient without the addition of anticoagulant are placed in a centrifuge and spun at 3000 rpm for 10 minutes. This results in a material consisting of a portion rich in fibrin (in yellow), a portion rich in erythrocytes (in red), and a PRF clot rich in platelets located between them.

The natural mechanism of coagulation is triggered when blood comes into contact with the glass tube surface, leading to the formation of a fibrin clot rich in platelets and white blood cells without any biochemical modifications, without the addition of anticoagulant, thrombin, or calcium chloride. PRF can be used in the form of a gel or membrane.

After centrifugation, the portion rich in platelets can be mixed with the biomaterial (Figure 4), while the portion rich in fibrin can be transformed into a membrane by applying pressure between two compresses (Figure 5).

Figure 4.

300–500 μm particulate demineralized bone matrix (DFDBA). The platelet-rich portion is located at the boundary between the fibrin-rich and red blood cell-rich portions. It can be cut and mixed with DFDBA.

Figure 5.

The fibrin-rich portion can be manually pressed between two compresses to obtain autologous fibrin membranes.

PRF has the advantage over PRP of being entirely autologous, and it has been shown to release platelet growth factors over a period of at least 1 week [19], unlike PRP, which releases them within an hour of preparation [20]. Due to its ease of obtention, purely autologous nature, and the fact that the coagulation cascade occurs physiologically without the addition of bovine thrombin, PRF tends to replace PRP currently.

Platelet concentrates contain fibrinogen, cell adhesion molecules (fibrin, fibronectin, and vitronectin) that play a role in cell migration and osteoconduction, as well as growth factors such as PDGF (Platelet-Derived Growth Factor), TGF-β, EGF (Epithelial Growth Factor), IGF (Insulin-like Growth Factor), and VEGF (Vascular Endothelial Growth Factor) [19]. In oral implant surgery, platelet concentrates are used as adjuvants to bone reconstruction procedures. The aim of their use is to accelerate and improve the healing process, particularly in terms of bone graft integration and regeneration [21].

They are used in various clinical applications, such as maxillary sinus augmentation, alveolar ridge augmentation, mandibular reconstruction, treatment of periodontal pockets, post-extraction alveolar bone filling, and dental implant osseointegration [22, 23, 24, 25]. Studies have shown the beneficial effects of platelet concentrates, such as improved soft tissue healing [26, 27]. However, the improvement of bone regeneration through platelet concentrate administration is still controversial [28, 29]. The lack of standardization in platelet concentrate obtention protocols may explain the lack of concordance in various studies, and the kinetics of growth factor delivery is still poorly understood, with large variations observed among patients and even within the same patient depending on the time of day of the blood collection (circadian variations in platelet concentration exist) [18, 19]. Furthermore, the contradictory results reported in the literature regarding the benefits of using platelet coagulation factors can be partly explained by the fact that these results come from clinical studies for some and animal studies for others, and it is difficult to extrapolate results obtained from one species to another [30, 31].

On the other hand, the minimum platelet concentration required to obtain a blood clot meeting the criteria for PRF is not well defined by the authors. However, they agree that clinical benefits can be obtained for a platelet concentration of 1 million/μL of plasma (4 to 7 times the baseline level) [32].

2.1.4 Use of a combination of allograft and platelet concentrates

The benefits associated with the use of a combination of biomaterials, such as allograft and platelet concentrates, are currently still controversial. One study [33] compared the use of a bone allograft alone with a bone allograft combined with platelet-rich fibrin (PRF) for maxillary sinus augmentation in 9 patients. According to the authors, the combination of allograft and PRF allows for faster bone maturity, which enables dental implant placement at 4 months postoperatively compared to 8 months for the control group.

The clinical benefits of platelet concentrates combined with demineralized freeze-dried bone allograft (DFDBA) in bone regeneration have been demonstrated in the treatment of periodontal pockets [34, 35], but have not yet been evaluated in oral surgery in a large cohort of patients.

2.2 Surgical techniques

2.2.1 Principles of post-extraction alveolar ridge preservation

Post-extraction alveolar ridge preservation techniques are based on the principle of guided bone regeneration. The principle involves placing a membrane between the soft tissues and the alveolar bone contours. This membrane prevents the passage and proliferation of epithelial cells and connective tissue into the alveolus, thus ensuring a space that can be colonized by osteoprogenitor cells. This prevents the growth and invagination of soft tissues into the extraction site during healing, thus allowing for adequate bone preservation. In addition to its role in maintaining space, the membrane stabilizes, protects, and ensures the containment of the blood clot and, optionally, the graft material that has been inserted into the alveolus. The biomaterial placed in the dental alveolus under the membrane immediately after extraction will constitute a structure whose architecture will guide and support colonization by osteoprogenitor cells and, thereby, bone regeneration. The Alveolar Ridge preservation Technique Using DFDBA and Platelet Concentrates The Implantology Clinic at Erasme Hospital routinely uses a combination of DFDBA bone bank and PRF platelet concentrates in the form of gel and membrane during post-extraction alveolar ridge preservation procedures. At the start of surgery, 6 to 8 tubes of 10 ml blood without anticoagulants are collected from the patient. Centrifugation at 3000 rpm for 10 minutes or 2800 rpm for 12 minutes is performed according to a protocol described in a previous study [18]. The platelet-rich portion (which is at the boundary between the yellow fibrin-rich part and the red erythrocyte-rich part) is collected and mixed with particulate allograft (DFDBA) with a particle size of 300 to 500 μm. The fibrin-rich portion is manually pressed between two compresses to obtain autologous fibrin membranes. Atraumatic extractions are performed, and immediately thereafter, the alveolar ridge is filled with the DFDBA-platelet concentrate mixture. Closure of the alveolus is ensured by the fibrin membrane, and resorbable sutures (Vicryl® 3/0) are performed (Figure 6).

Figure 6.

Post-extractional alveolar ridge augmentation technique as practiced in the Implantology Clinic of Erasme Hospital.

Immediately after atraumatic extraction, the alveolar ridge is augmented using a mixture of DFDBA and platelet concentrates. The alveolar ridge is closed using a fibrin membrane and absorbable sutures (Vicryl® 3/0). During the post-operative period, 600 mg of ibuprofen three times a day and 500 mg of paracetamol are prescribed for pain relief. All patients receive 1 g of amoxicillin twice a day for 4 days or 300 mg of clindamycin three times a day if allergic to penicillin, for 4 days. This technique provides good results in terms of preserving post-extractional bone volume [36].

2.2.2 Sinus lift

There are different techniques for augmenting the maxillary sinus floor to create adequate bone volume. Studies have shown that the results of maxillary sinus grafting in terms of implant survival rates are best when using only biomaterial as the grafting material, with 96.0% implant survival rate at 5 years when using 100% biomaterial versus 87.8% when using autogenous bone [36].

The technique we use in the Implantology Clinic of Erasme Hospital is based on the insertion of a mixture consisting exclusively of DFDBA and platelet concentrates under the Schneiderian membrane of the maxillary sinus, after creating a bone flap using piezo surgery at the antero-external wall of the maxillary sinus. Autologous fibrin membranes are placed on the walls of the cavity, followed by a mixture of DFDBA and autologous platelet concentrates, which is obtained as described in the previous chapter. Autologous fibrin membranes are then applied outside the graft, and the mucoperiosteal flap is sutured in place (Figure 7).

Figure 7.

Procedure for maxillary sinus grafting as performed at the implantology clinic of Erasme Hospital. A bone flap is made with piezoelectric surgery on the antero-external wall of the right maxillary sinus, followed by horizontal tipping while lifting the Schneider membrane of the sinus. Autologous fibrin membranes are placed on the internal, anterior, and posterior walls of the cavity, and then a mixture of DFDBA and autologous platelet concentrates is placed in the cavity. Autologous fibrin membranes are then applied outside the graft, and the mucoperiosteal flap is sutured in place.

3. Bone quality

It has become crucial in contemporary implantology to keep the alveolar ridge after extraction. There is currently agreement that alveolar ridge maintenance is necessary to prevent further bone loss [36, 37]. According to a recent study, the combination of PRF platelet concentrates with particle DFDBA (300–500 m) results in excellent outcomes for post-extractional bone preservation [36].

Alveolar ridge preservation and sinus lift procedures enable the favorable conservation or restoration of bone volume; however, for medium- and long-term implant results, it is also crucial to objectively evaluate the quality of the acquired reconstruction. To achieve this, authors frequently employ histomorphometry, a method for examining both qualitative and quantitative aspects of bone quality [37, 38, 39, 40].

A. Wardani et al.’s recent work used DFDBA (300–500) and PRF platelet concentrate to assess bone quality in sinus lift and alveolar socket preservation. 40 2 mm-diameter bone samples from 21 patients were the subject of an interventional prospective investigation. In order to serve as control groups, 22 biopsies were taken from preserved sockets, 7 from grafted sinus locations, and 11 from native bone [37].

The samples were fixed, embedded in paraffin, sliced on a microtome, and then stained with Masson’s trichrome and hematoxylin-eosin.

According to the ratios of woven (immature) and lamellar (mature) bone, a healing score ranging from 1 to 3 was given to each bone sample to make it easier to compare them. Score 1 showed a predominance of woven bone (difference between woven and lamellar bone proportion > 10%) and reflected an early stage of bone healing; score 2 showed the presence of lamellar and woven bone in similar proportions (difference between woven and lamellar bone proportion 10%) and reflected a moderate stage of bone healing; and score 3 showed a predominance of lamellar bone (difference between woven and lam) (Table 1).

Bone healing score
1	Prevalence of woven bone (difference in the proportions of woven and lamellar bone >10%)
2	Lamellar and woven bon in similar proportions (difference in the proportions of woven and lamellar bone <10%)
3	Prevalence of lamellar bone (difference in the proportions of woven and lamellar bone >10%)

Table 1.

Bone healing score.

3.1 Native bone samples

The majority of the native bone samples displayed a score of 3 (9/11), which denotes extensive bone repair. Only two samples (Table 2) got a score of 2, corresponding to a moderate level of healing. Only lamellar bone was visible in two samples, which indicates extraordinarily high bone density. Remember that the mandibular symphysis bone is where these samples originated. Lamellar bone made up an average of 52.73% of native bone, woven bone made up an average of 10.74% of native bone, and overall bone made up an average of 65.29% of native bone. Native bone received an average healing score of 2.82.

Native bone sample	Proportion of total bone (%)	Proportion of lamellar bone (%)	Proportion of woven bone	Score
Sample 1	44.31	44.15	0.15%	3
Sample 2	39.45	39.45	0.00%	3
Sample 3	48.13	45.45	2.67%	3
Sample 4	44.69	42.80	1.89%	3
Sample 5	48.64	46.23	2.40%	3
Sample 6	91.01	91.01	0	3
Sample 7	83.54	83.54	0	3
Sample 8	85.40	42.50	42.90%	2
Sample 9	65.60	39.10	26.50%	3
Sample 10	70.10	61.20	8.90%	3
Sample 11	97.4	44.70	52.70%	2
Mean	65.29	52.73	10.74%	2.82

Table 2.

Proportion of bone surfaces in native bone.

3.2 Alveolar samples

Table 3 contains a list of the samples collected from grafted alveolar structures. A score of 1 was assigned to two out of the 22 samples, which were eliminated after 3 and 5 months of healing, respectively. Except for four samples that were obtained after 5 months had passed since the start of the healing process, 12 out of 22 samples (Figures 8–11) had a score of 2. Table 3 shows that 8 out of 22 samples received a 3 rating. Alveolar structure samples were divided into two groups based on whether the healing duration was less than (A) or higher than (B) 5 months. In comparison to group A, the samples in group B had a higher average proportion of newly produced bone and a lower average proportion of DFDBA residual particles (Table 4).

Samples	Δt (healing time prior to sampling in months)	Proportion of newly formed bone (%)	Proportion of residual DFDBA particles (%)	Score
Sample 1	2	38.76	16.10	2
Sample 2	3	21.89	7.10	1
Sample 3	3	52.80	20.10	2
Sample 4	3	83.10	14.20	3
Sample 5	4	45.10	29.60	3
Sample 6	4	76.60	20.20	3
Sample 7	4	38.60	32.30	2
Sample 8	4.5	45.20	31.10	2
Sample 9	5	5.15	18.91	1
Sample 10	5	22.04	12.31	2
Sample 11	5	30.64	4.22	2
Sample 12	5	25.90	3 .45	2
Sample 13	5	75.99	0.91	3
Sample 14	5	15.44	5.54	2
Sample 15	6	69.60	12.70	2
Sample 16	7	45.70	2.33	3
Sample 17	7.5	72.90	17.50	2
Sample 18	7.5	54.70	37.40	2
Sample 19	9	36.55	5.90	3
Sample 20	9	31.32	8.59	3
Sample 21	15	63.40	5.40	2
Sample 22	15	73.00	20.00	3
Mean	—	46.29	14.81	2.27

Table 3.

Proportions of newly formed bone surface, residual particles, and healing score of samples from alveolar grafted sockets.

Figure 8.

Sample from a grafted alveolar socket showing a healing score of 2 (H&E). Lamellar bone (LB), woven bone (WB), residual particle (RP).

Figure 9.

Sample from a grafted alveolar socket showing a healing score of 2 (H&E). Lamellar bone (LB).

Figure 10.

Sample from a grafted alveolar socket showing a healing score of 2 (H&E). Residual particle (RP).

Figure 11.

Sample from a grafted alveolar socket showing a healing score of 2 (H&E). Woven bone (WB).

	Average proportion of newly formed bone (%)	Average proportion of residual particle (%)	Average healing score
≤5 months	41.42	15.43	2.14
>5 months	55.89	13.72	2.5

Table 4.

Average proportions as a function of the healing time for alveolar grafted sockets.

3.3 Sinus lift samples

Table 5 displays the samples taken from sinus lifts. The samples, all except one of which had a score of 3, were collected between six and 9 months after healing (Figures 12 and 13). A single sample was taken 8 months into the healing process and had a score of 2 (Table 5).

Bone samples in sinus lifts	Δt(healing time prior to sampling in months)	Proportion of newly formed bone (%)	Proportion of residual DFDBA particles (%)	Healing score
Sample 1	6	82.90	9.60	3
Sample 2	6	41.40	24.60	3
Sample 3	7	26.88	13.72	3
Sample 4	7.5	36.88	6.47	3
Sample 5	8	63.50	13.90	3
Sample 6	8	48.20	20.10	2
Sample 7	9	40.24	3.09	3
Mean	—	48.57	13.07	2.86

Table 5.

Proportions of newly formed bone, residual particles, and healing score of sinus lifts.

Figure 12.

Sample from a sinus lift displaying a healing score of 3 (H&E). Woven bone (WB), lamellar bone (LB), residual particle (RP).

Figure 13.

Sample from a sinus lift displaying a healing score of 3 (TM). Woven bone (WB), lamellar bone (LB), residual particle (RP).

According to the study, as healing time increases, there is a greater proportion of lamellar neoformed bone than unformed tissue (Figure 8). The amount of newly produced bone in the grafted sockets significantly increased as healing progressed (average: 41.22% 5 months, 55.89% > 5 months). Additionally, it appears that DFDBA particle resorption and healing time in the grafted socket are associated (average: 15.43 5 months, 13.72% > 5 months). When utilizing DFDBA and PRF for sinus lift and alveolar socket preservation, high-quality, mature bone tissue is produced that meets histological standards [37].

In the present investigation, samples taken from native bone were examined, and it was shown that 10.72% of the samples (8 out of 11) included immature woven bone, which is probably the result of normal bone remodeling [41, 42]. Furthermore, lamellar bone was only present in two native bone samples, making up more than 80% of the sample area and indicating advanced bone maturity. With an average healing score of 2.32 and a majority of lamellar bone, all 22 samples tested from grafted alveoli showed freshly created bone. The average percentage of newly produced bone across all prepared cell samples was 46.56%, demonstrating the effectiveness of using PRF and DFDBA alveolar fillers to encourage bone neoformation. The average percentage of newly produced bone in samples collected within the first 5 months of recovery was 41.22%, but the average percentage in samples taken more than 5 months later was 55.89%.

An average proportion of newly produced bone of 47.41% was seen 4 months after healing in a previous histomorphometric study that used DFDBA without PRF [42], which is marginally greater than the proportion attained in the current study. It was noticed that the DFDBA (donor variability) origin difference in our study may have had an impact on the outcomes.

Our study found an average of 15.43% at healing periods less than or equal to 5 months and an average of 13.72% at healing periods more than 5 months, indicating gradual resorption of the allograft particles over time. This proportion of residual DFDBA particles was found to exist within the grafted alveoli. According to a recent study [43], there were 37.42% residual DFDBA particles at 2 months and 26.80% at 4 months. This suggests that particles in our study were absorbed more quickly.

The study found a propensity to see equal amounts of both at healing durations of less than 5 months with regard to the proportions of lamellar and woven bone, indicative of bone maturity. In contrast, there was a tendency toward a predominance of lamellar bone after 5 months of healing, which suggests that the graft evolved over time toward better bone maturity. These results suggest that the post-extraction alveolar arrangement using particle DFDBA (300–500 m) and A-PRF produces good results in terms of bone quality and maturity. It is difficult to compare these findings with other histomorphometric studies because many of them just look at the overall proportion of freshly created bone rather than distinguishing between lamellar and woven bone.

After 6 to 9 months, samples from the locations that received a sinus lift revealed an average proportion of newly produced bone of 48.57% in all seven samples, with a higher proportion of lamellar bone (scoring 3) than woven bone in six of the seven samples. This demonstrates that sinus grafts that were treated with particulate DFDBA (300–500 m) and PRF successfully healed the bone.

In a different study [43], sinus lift patients were divided into two groups: one with DFDBA alone and the other with DFDBA with PRF. At 6 months, the group with PRF had a larger percentage of newly created bone (18.35%) than the group without PRF (12.95%), indicating that PRF has a beneficial effect on new bone production.

As comparing these findings to those of our study, it appears that DFDBA and PRF for sinus lift produce superior results in terms of new bone creation as compared to DBBM and PRF. By exposing lingering BMPs, the osteoinductive capability of DFDBA—a product of its demineralization during preparation—might be able to explain this discrepancy. However, because of the small sample size in our study, additional research with bigger sample sizes is preferred to improve the findings. We found 13.07% of residual particles in the sinus lift samples, with an average healing time of 7.35 months.

After an average healing duration of 10.81 months, histomorphometric analysis of samples taken without sinus lifts using FDBA and DFDBA revealed an average proportion of residual particles of 9.56% and 10.11%, respectively [44]. These findings are consistent with our research and point to a long-term beneficial absorption of allograft particles after sinus lift surgeries.

4. Conclusion

For post-extractional alveolar ridge augmentation and sinus lift surgeries, the combination of 300–500 m DFDBA and autologous platelet-rich concentrate, such as PRF, yields predictable clinical results.

Conflict of interest

The authors declare no conflict of interest.