Matti Peltola

BIOACTIVE GLASS S53P4 IN FRONTAL SINUS OBLITERATION: A LONG-TERM CLINICAL EXPERIENCE

Synthetic, osteoconductive, and antimicrobial bioactive glass (BAG) has been used in many surgical applications.

Obliteration of the frontal sinus cavity with bioactive glass

Bioactive glass (BG) is a glass ceramic material. It has been used as surgical bone replacement material in ear and oral surgery, orthopedics, and dentistry.

Reconstruction of orbital wall defects with bioactive glass plates.

PURPOSE Synthetic bioactive glass (BAG) is used in many surgical applications. Special bioactive glasses do not favor microbial growth. This study evaluated the clinical outcome of bioactive glass plates in reconstructive orbital surgery. PATIENTS AND METHODS In a retrospective series of 49 patients, 35 orbital floors and 6 orbital medial and superior walls were reconstructed after fronto-orbital trauma, and 8 patients were treated with BAG plates after fronto-orbital tumor resection. These patients were evaluated in terms of reconstruction materials, complications, and functional outcomes. RESULTS During the 2-year follow-up, 3 of the 35 orbital floor trauma reconstructions were reoperated (9%) because of diplopia, and new reconstructions with BAG were performed. In all of the 8 patients with tumors and in 6 of the patients undergoing orbital wall reconstruction, the plates were in the correct position after reconstruction, and none had to be removed. One patient with a benign tumor and 7 of the 8 patients with malignant tumors survived to the 2-year follow-up. CONCLUSIONS Reconstructive surgery of the orbit is one of the most demanding challenges in head and neck surgery. In orbital defect reconstruction, a BAG plate seems to be a well-tolerated and reliable reconstruction material alternative; however, BAG plates are brittle and rigid, and cannot be molded and shaped by a surgeon. The use of a stainless steel template of equal shape and size to a BAG plate is recommended to ameliorate this deficiency.

In vivo model for frontal sinus and calvarial bone defect obliteration with bioactive glass S53P4 and hydroxyapatite

An in vivo model was developed to investigate the usability of a frontal sinus and a calvarial bone defect obliteration with bioactive glass S53P4 (BG) and hydroxyapatite (HA) granules. Roofs of 21 Elco rabbit frontal sinuses were drilled open from 4 separate holes using a standard method, and the sinuses, located in pairs, in frontal bone were filled with BG on one side and with HA on the other side. Two parallel posterior defects were covered with a pedicled periosteum flap, and 2 anterior defects with a free flap. The stability of materials, new bone, and connective tissue formation were observed with histomorphometry, scanning electron microscopy (SEM), energy dispersive X-ray analysis (EDXA), and X-ray pictures at 1, 3, 6, and 12 months postoperatively. The results showed more rapid resorption of filling material (p = 0.019) and new bone formation (p = 0.0001) in the defects filled with BG than in the corresponding HA-filled defects studied by histomorphometry throughout the study. New bone formation and resorption of materials were faster in defects covered by a pedicled flap than by a free periosteum flap. The results were supported by SEM histomorphometric and radiologic analysis. Both bioactive materials studied were well tolerated in frontal sinuses and in calvarial bone defects. The experimental model showed the influence of early periosteum vascularization on accurate frontal sinus filling and the healing process in rabbit frontal sinuses.

Bioactive glass hydroxyapatite in fronto-orbital defect reconstruction.

Background: Synthetic bioactive ceramics and glasses have osteoconductive properties. These materials are capable of chemically bonding to the bone tissue. In addition, special bioactive glasses do not favor microbial growth. In this study, the clinical outcome of bioactive glass and hydroxyapatite in head and neck surgery was evaluated. Methods: In a retrospective series of 150 patients, 62 patients underwent reconstruction with frontal sinus obliteration after chronic frontal sinusitis, 65 patients were operated on for fronto-orbital traumas, and 23 patients underwent reconstruction after fronto-orbital tumor resections. These patients were evaluated for surgical procedures, reconstruction materials, complications, and functional outcomes. Results: Three of the 62 frontal sinus occlusions underwent operation (4.8 percent) during the follow-up of 5 years. The reoperations were caused by a new mucocele. In fronto-orbital reconstructions, we have reoperated on the orbital floor in four cases (7 percent). All 12 benign tumor patients and six of 11 malignant tumor patients survived during a follow-up of 3 years. Two of the 23 (9 percent) complicated tumor and trauma patients underwent reoperation because of a local mucocele. Conclusions: Treatment of severe head and neck defects with biomaterial is a suitable alternative to conventional methods. Bioactive materials seem to be stable and reliable at clinical follow-up. The reconstructions with bioactive glass and hydroxyapatite are associated with good functional and aesthetic results without donor-site morbidity. However, more long-term outcomes of studied biomaterials are needed to determine whether they are capable of competing with traditional tissue grafts.

Clinical follow-up method for frontal sinus obliteration with bioactive glass S53P4.

A clinical follow-up method was developed to investigate the behavior of a massive amount of bioactive glass S53P4 (BG) clinically used in frontal sinus obliteration. Two sizes of granules (0.63-0.8 mm or 0.8-1.0 mm) in 16 separate BG amounts, weight 25 g, were tested both in simulated body fluid (SBF) and in a buffer containing tris-hydroxymethyl aminomethane citric acid (TRIS-c.a) in standard conditions. The dissolution of silicon (Si) and phosphate (P) was detected with direct current plasma atom emission spectroscopy (DCP-AES) monthly up to 6 months. The BG masses were scanned both wet in the solutions and dried by computer tomography (CT), and the scans were analyzed by Region of Interest (ROI) technique. Calcium phosphate (CaP)- and silica (Si)-gel-layers were studied by scanning electron microscopy (SEM) at 1, 3, and 6 months. Cumulative loss of Si and P was stronger in TRIS-c.a than in SBF (p < 0.0001), and it was higher with smaller than with larger granules in both solutions (p < 0.0001). This was shown correspondingly by the decrease of Hounsfield units (HUs) in ROI analysis (p < 0.0001). The level of HUs was lower with dried than with wet BG (p < 0.0001). The results were compared for clinical ROI analysis of patients with obliterated frontal sinuses up to 48 months and they were parallel. The follow-up method seems to indirectly reveal the behavior of BG and the healing process in the obliterated cavity.

In vitro model for frontal sinus obliteration with bioactive glass S53P4

An in vitro model was used to investigate the behavior of a massive frontal sinus obliteration with bioactive glass S53P4 (BG) for clinical purposes. Two sizes of granules (0.63-0.8 mm or 0.8-1.0 mm) in 16 separate BG amounts, weight 25 g, were tested both in simulated body fluid (SBF) and a buffer containing trishydroxymethyl aminomethane citric acid (TRIS-c.a) in standard conditions. The dissolution of silicon (Si) and phosphate (P) was detected with direct current plasma atom emission spectroscopy (DCP-AES) monthly up to 6 months. The BG masses were scanned by computer tomography (CT) and the scans analyzed by Region of Interest (ROI) technique. Calcium phosphate (CaP)- and silica (Si)-gel-layers were studied by scanning electron microscopy (SEM) at 1, 3, and 6 months. Cumulative loss of Si and P was stronger in TRIS -c.a than in SBF (p < 0.0001), and it was higher with smaller than with larger granules in both solutions (p < 0.0001). This was shown correspondingly by the decrease in Hounsfield units (HU) by ROI analysis (p < 0.0001). In SBF-soaked BG masses, the CaP-layer occurred on the uppermost granules, and in TRIS-c.a at 3-6 months, on the granules in the center and lower parts. The decrease of HU seems to reveal indirectly the resorption of BG.

A Review of Two Animal Studies Dealing with Biological Responses to Glass-Fibre-Reinforced Composite Implants in Critical Size Calvarial Bone Defects in Rabbits

In these studies, E-glass-fibre-reinforced composite (FRC) implants with photopolymerisable resin systems and bioactive glass granules (BAG) were evaluated as a reconstructive material in the critical size bone defects made to rabbits’ calvarial bones. In the first study, a new experimental resin system, DD1/MMA/BDDMA, was used to impregnate the doubleveil FRC-implants, while in the second study, a commercial resin system composed of BisGMA/MMA/PMMA was used in impregnation. These double-veil FRC-implants were coated with bioactive glass granules (BAG, 315-500 0m). In the second study, an experimental FRC consisting of two laminates of woven fibres, was also tested as an implant material. These implants were filled with BAG-granules and pure fused quartz fibers (Quartzel wool). In the first study, implantation time was 4 or 12 weeks, while in the second study, it was 12 weeks for both the implant types. Results: In the first study, the healing of the defects had started in the form of new bone growth from the defect margins, as well as small islands of woven bone in the middle of the defect, at 4 weeks postoperatively. Ingrowth of dense connective tissue into the pores of the implant was widely seen. At 12 weeks postoperatively, more bony islands were seen as compared to the animals studied at 4 weeks. Part of the newly formed bone had an appearance of lamellar structure. The porous structures of the implant were deeply filled with fibroconnective tissue. Ingrowth of maturing bone to the implant structures was occasionally seen. The inflammatory reaction was moderate, and was mostly found inside the upper part of the implant. In the second study, inflammatory reactions caused by both types of the FRC implants were very slight. Small amount of new bone had started to grow from the defect margins in doulble-veil implanted defects. No ingrowth of connective tissues or new bone formation was seen inside these implants. Instead, both the connective tissues and newly formed, mineralizing bone were seen inside the experimental double-laminate implants. SiO2-fibres seemed to cause moderate inflammatory reaction inside the implants, while BAG granules did not. In both the study groups, the brain tissue was oedemic, but no obvious serious damage was found. Conclusions: The structural properties of the FRC-implants had an influence on the healing process of the bone defect. BAG, as a constituent of the FRCimplants, enhanced the bone formation process. After some modifications to the properties of the FRC, this type of implant has possibilities to become one material alternative in clinical bone defect reconstruction at the craniofacial area in the future.

Long-Term Tissue Reactions of Three Biomaterials in Craniofacial Surgery

Successful craniofacial reconstruction needs both a well-known and a reliable reconstruction material. However, there is often a lack of long-term knowledge of the tissue reactions and healing process in the human body. In this study, frontal sinus obliterations with bovine bone natural hydroxyapatite derivative (BHA), synthetic bioactive glass S53P4 (BAG) and hydroxyapatite cement (HAC) were investigated with clinical, histologic, scanning electron microscopic (SEM) and energy dispersive x-ray analysis (EDXA) 27, 12 and 3 years postoperatively. The aim was to determine the long-term clinical biocompatibility of the used materials. Histologic studies revealed bone formation with BHA particles and lamellar bone with BAG granule remnants in close contact to the new bone formation. In HAC reconstruction there was scattered fibroconnective tissue growth without new bone formation in the surface of HAC implantation. Neither foreign body reaction nor any abnormal findings were seen. SEM studies revealed a CaP layer on the surface of BAG granule remnants. In EDXA studies, composition profiles showed Ca-, P- and Si- rich layers on the BAG granule surface. No differences were found in CaO and P2O5 levels between BHA granules and HAC implantation and the surrounding bone. All investigated biomaterials were well tolerated in long-term applications.