This case report discusses about an innovative bone regeneration method that involves the use of autologous periosteal micrografts, which were used for a maxillary sinus floor lift in a 52-year-old female patient. This method allows for harvesting of a graft that is to be seeded on a PLGA scaffold and involves collection of a very little amount of palatal periosteal tissue in the same surgical site after elevation of a flap and disaggregation of it by using a Rigenera® filter. Histological samples collected at the time of implant installation demonstrate a good degree of bone regeneration. The clinical and radiographic outcomes at the 3-year follow-up visit showed an adequate stability of hard and soft tissues around the implants. This report demonstrates the possibility to obtain a sufficient quality and quantity of bone with a progenitor cell-based micrograft and in turn make the site appropriate for an implant-supported rehabilitation procedure, with stable results over a period of two years.
Tooth loss causes alveolar bone resorption that often limits implant placement. In the superior maxilla, this process is associated with the pneumatization of the sinus [
Since the 60s, numerous surgical techniques have been proposed for the regeneration of maxillary bone defects. When the residual bone height is inadequate for implant placement, in case of favorable prosthetical spaces, a sinus lift is considered a safe procedure with predictable results [
Current treatment options for bone defects include autologous, homologous, xenologous, and allogenous grafts; artificial bone substitutes can be synthetic or bioceramic cements or a blend of two or more materials [
In the last twenty years, researchers have shown renewed interest in developing new regeneration methods. Researchers are particularly focusing on mesenchymal stem cells because they represent a self-renewable reservoir of cells that can proliferate and differentiate at the same time. Thus, if correctly transplanted, mesenchymal stem cells are able to regenerate a particular tissue [
Unfortunately, stem cell therapies require both highly developed technologies and methods, which are not yet allowed to be used in many countries (e.g., laboratory handling of stem cells to produce tissues). Moreover, a few researchers have reported that stem cell therapies could increase the risk for tumor growth [
Recently, a class I medical device (Rigeneracons®, Human Brain Wave S.R.L., Torino, Italy) has been introduced in clinical practice in order to disaggregate a portion of tissue and obtain 50
The aim of this report is to present a clinical case in which autologous micrografts with a high percentage of progenitor cells were seeded on a PLGA hydroxyapatite- (HA-) enriched scaffold for a sinus floor lift augmentation procedure and to present the histological features shown by the sample collected at the implant site and the radiographic aspect obtained three years after the lift procedure.
The procedure discussed in this case report was performed at the Department of Clinical Surgical, Diagnostic and Paediatric Sciences, University of Pavia, Italy, and the procedure was approved by the University Ethics Committee (recorded March 2014).
A 52-year-old woman, with a good health status (ASA score: 0), was enrolled for the study; written informed consent was obtained from the patient to have the case details and any accompanying images anonymously published. She was indicated for a prosthetic implant rehabilitation procedure in the second quadrant after a maxillary sinus lift procedure for atrophy of the maxillary bone at the bicuspid and molar level (1 mm residual bone crest height) in order to collect enough bone to install two endosseous implants (Figures
Preoperative panoramic radiograph of the patient.
Intraoral radiograph (Rinn® collimator) of the surgery site.
The patient was prepared for the surgery with scaling and root planning two weeks prior to the sinus floor lift. The surgery was performed under antibiotic prophylaxis: amoxicillin plus clavulanic acid (Augmentin, GlaxoSmithKline S.p.A., Verona, Italy), 2 gr 1 hour before the surgery. For the local anesthesia, articain 4% with 1/200000 epinephrine was used.
A full-thickness flap was lifted via mesial and distal relief incisions. From the palatal flap, a 3 mm periosteal sample was harvested and then washed with a sterile saline solution. Then, it was inserted in the Rigeneracons filter with 1 ml of sterile saline for the disaggregation process (Figures
Connective tissue collected directly from the surgery site.
Tissue graft disaggregation with the Rigeneracons device, according to the manufacturer’s instructions: 1 ml of sterile saline solution, performed for 120 seconds with implant contra-angle at 15 NCm and 70 rpm.
Tissue graft disaggregation was performed for 2 minutes at 70 rpm and 15 Ncm torque, and the cell suspension was withdrawn with a sterile syringe and added to the PLGA-HA scaffold (Alos®, Allmed srl, Lissone, MB, Italy) in order to be grafted into the new subantral cavity (Figure
The syringe with progenitor cell-enriched suspension obtained via the periosteum disaggregation process.
The window elevation.
The biocomplex graft placement in the maxillary sinus, under the Schneider membrane.
Covering the osteotomy access with collagen and resorbable membrane.
During the postoperative period, the patient received antibiotic therapy (1 gr every 12 hours of amoxicillin + clavulanic acid for 7 days) and performed oral rinses with chlorhexidine 0.2% (Curasept®, Curaden Healthcare S.p.A., Saronno, VA, Italy), 3 times/day for 30 days, and she was administered nonsteroidal anti-inflammatory drugs (NSAIDs) if needed.
The healing was uneventful and the sutures were removed after 2 weeks.
At 4 months after the surgery, following a cone-beam CT examination demonstrating a good level of bone regeneration, a mucoperiosteal flap was elevated and two bone tissue carrots 3 mm in diameter were harvested from the implant sites using a trephine bur. Two 3.8 × 9 mm implants were installed (Camlog® Promote® Plus, Camlog Biotechnologies AG, Basel, Switzerland) according to the standard protocol [
Radiograph taken postimplantation.
The collected tissues were fixed in a 10% formalin solution and then prepared for microscopic observation in order to determine the ossification grade (Figure
Hematoxylin/eosin staining of samples at 4 months (a, b) after grafting with the Rigenera system. (a) 10x magnification, (b) 40x magnification.
8 weeks after the implant installation, the following standard prosthetic procedures were performed: implant impression, abutment and structure proof, and cemented prosthesis delivery.
After three years, during the follow-up visit [
Intraoral radiograph taken after 3 years.
Usually, a bone graft is the first therapeutic option in cases where the amount of bone is inadequate for implant installation. Autologous bone is considered the gold standard in sinus augmentation procedures but exposes to donor site morbidity. With the Rigenera protocol, the amount of tissue harvested is very little and the donor site is the surgical site itself, thus minimizing the risk of morbidity. In the presented clinical case, healing was uneventful and no sign of tissue harvesting resituated in the palatal flap. The authors did not observe any differences in postoperative soft tissue healing and patient morbidity with respect to the standard procedure due to soft tissue harvesting from the palatal flap. Synthetic materials exhibit a good capability to regenerate an adequate amount of bone, but they do not exhibit the osteoinductive and osteogenic properties needed for bone regeneration. Furthermore, some of these materials show a lack of resorbability even after years from the time of production. This is the reason why the field of bone tissue engineering has focused on techniques such as the use of mesenchymal stem cells [
A licit criticism related to the use of MSC in a therapeutic procedure is that the graft cell population is composed of nonclonal stromal cells containing stem cells, progenitor cells, and differentiated mesodermal cells, including fibroblasts, and that the advantages connected to their use are more related to their important role in modulating inflammation compared to any stem cell activity [
It was demonstrated that micrografts obtained by the Rigenera protocol are able to maintain the osteogenic and regenerative properties because of the content of the progenitor cells [
The sinus lift surgery performed in this case was associated with a resorbable scaffold HA enriched with progenitor cell micrograft, which was harvested from the palatal periosteum. In particular, the small tissue sample was derived directly from the surgery flap, so the biologic cost was very low.
The scaffold is important to provide the stability and mechanical resistance required to maintain the viability of the cells. Different types of osteoconductive materials could be used as scaffolds. In this case, we chose the PLGA HA-enriched scaffold, which was completely resorbable, as PLGA without HA, but also offered more stability to the graft because of the presence of hydroxyapatite. The micrografts, compared with the other bone grafts, are effective in the regeneration of bone required for implant surgery and are capable of supporting long-term prosthetical load [
This case illustrates that the use of autologous micrografts, which are rich in progenitor cells, in the sinus floor lift procedure is effective in regenerating an adequate amount of bone tissue, with both excellent implant stability and minimum biological sacrifice.
Poly lactic-co-glycolic acid
Nonsteroidal anti-inflammatory drugs
The American Society of Anesthesiologists.
The authors declare that they have no conflicts of interest.