Biodegradable gelatin/beta-tricalcium phosphate sponges incorporating recombinant human fibroblast growth factor-2 for treatment of recession-type defects: A split-mouth study in dogs

BACKGROUND AND OBJECTIVE

Tissue engineering by using recombinant human (rh) growth factor technology may offer a promising therapeutic approach for treatment of gingival recession. Fibroblast growth factor-2 (FGF-2) has shown the ability to promote periodontal regeneration. Gelatin/beta-tricalcium phosphate (gelatin/β-TCP) sponges have been developed to control the release of growth factors. The present study evaluated the periodontal regenerative efficacy of rhFGF-2 by comparing gelatin/β-TCP sponges incorporated with rhFGF-2 to the scaffolds alone in artificially created recession-type defects in dogs.

MATERIAL AND METHODS

Critically sized buccal gingival recession defects were surgically created on maxillary canine teeth of five dogs. In each animal, defects were randomized to receive either a gelatin/β-TCP sponge soaked with rhFGF-2 (gelatin/β-TCP/rhFGF-2) or phosphate-buffered saline (gelatin/β-TCP). Eight weeks after surgery, biopsy specimens were obtained and subjected to microcomputed tomography and histological analyses.

RESULTS

Complete root coverage was achieved in both groups. Microcomputed tomography revealed significantly greater new bone volume in the gelatin/β-TCP/rhFGF-2 group. Histologically, both groups achieved periodontal regeneration; however, gelatin/β-TCP/rhFGF-2 sites exhibited more tissue regeneration, characterized by significantly larger amounts of new cementum and new bone. Gelatin/β-TCP sites featured increased long junctional epithelium and connective tissue attachment. In the gelatin/β-TCP/rhFGF-2 sites, new bone exhibited many haversian canals and circumferential lamellae as well as remarkably thick periosteum with blood vascularization and hypercellularity.

CONCLUSION

Within the limitations of this study, rhFGF-2 in gelatin/β-TCP sponges exhibits an increased potential to support periodontal wound healing/regeneration in canine recession-type defects.

Ridge augmentation using recombinant human fibroblast growth factor-2 with biodegradable gelatin sponges incorporating β-tricalcium phosphate: a preclinical study in dogs

BACKGROUND AND OBJECTIVE

Fibroblast growth factor-2 (FGF-2) regulates the proliferation and differentiation of osteogenic cells, resulting in the promotion of bone formation. Biodegradable gelatin sponges incorporating β-tricalcium phosphate (β-TCP) have been reported as a scaffold, which has the ability to control growth factor release, offering sufficient mechanical strength and efficient migration of mesenchymal cells. In this study, we evaluated the effects of the combined use of recombinant human FGF-2 (rhFGF-2) and gelatin/β-TCP sponge on ridge augmentation in dogs.

MATERIAL AND METHODS

Six male beagle dogs were used in this study. Twelve wk after tooth extraction, bilateral 10 × 5 mm (width × depth) saddle-type defects were created 3 mm apart from the mesial side of the maxillary canine. At the experimental sites, the defects were filled with gelatin/β-TCP sponge infiltrated with 0.3% rhFGF-2, whereas gelatin/β-TCP sponge infiltrated with saline was applied to the control sites. Eight wk after surgery, qualitative and quantitative analyses were performed.

RESULTS

There were no signs of clinical inflammation at 8 wk after surgery. Histometric measurements revealed that new bone height at the experimental sites (2.98 ± 0.65 mm) was significantly greater than that at the control sites (1.56 ± 0.66 mm; p = 0.004). The total tissue height was greater at the experimental sites (6.62 ± 0.66 mm) than that at the control sites (5.95 ± 0.74 mm), although there was no statistical significant difference (p = 0.051). Cast model measurements revealed that the residual defect height at the experimental sites (2.31 ± 0.50 mm) was significantly smaller than that at the control sites (3.51 ± 0.78 mm; p = 0.012).

CONCLUSION

The combined use of rhFGF-2 and gelatin/β-TCP sponge promotes ridge augmentation in canine saddle-type bone defects.

Pocket epithelium in the pathological setting for HMGB1 release

High-mobility group box-1 (HMGB1) protein acts as a transcription factor in the nucleus and also as a pro-inflammatory cytokine when released into extracellular fluids. The presence of higher levels of HMGB1 is reported in the gingival crevicular fluid from periodontal patients. Since the proliferation of bacteria within the periodontal pocket is closely involved in the exacerbation of periodontal disease, it is hypothesized that the periodontal pocket causes the release of HMGB1. Immunohistochemical staining of inflamed gingiva revealed that HMGB1 is exclusively dislocated from the nucleus to the cytoplasm in the pocket epithelium, whereas it is mainly present in the nucleus in the gingival epithelium. Butyric acid, an extracellular metabolite from periodontopathic bacteria populating the periodontal pocket, induced the passive release of HMGB1 as a result of eliciting necrosis in the human gingival epithelial cell line. Thus, the periodontal epithelium may provide a unique pathological setting for HMGB1 release by bacterial insult.

Effect of rhBMP-2 with PLGA/gelatin sponge type (PGS) carrier on alveolar ridge augmentation in dogs

Recombinant human bone morphogenetic protein-2 has been shown to promote bone formation because of its osteoinductive property. The purpose of this study was to evaluate the efficacy of rhBMP-2 delivered on a poly (D, L-lactic-co-glycolic acid) copolymer/gelatin sponge (PGS) in vertical alveolar ridge augmentation on height-reduced edentulous mandible to verify the retention of rhBMP-2 withstanding the pressure of soft tissues. Coronal defects of the alveolar bone were created in six adult beagle dogs. After a healing period of 9 weeks, PGSs with or without rhBMP-2 (0 or 0.4 mg mL(-1)) were implanted on the defects(6 mm in height, 30 mm in length, 8 mm in width). Sixteen weeks after implantation, the bone mineral content (BMC) and the total bone area were measured by peripheral quantitative computed tomography. The BMC and the total bone area of the defect sites with rhBMP-2 group were significantly greater (133+/-33 mg mm(-1), 277+/-54 mm2, respectively) than those of the control group (80+/-19 mg mm(-1), 155+/-49 mm2, respectively) (P<0.01, P<0.0001, respectively; paired t-test). From the histological analyses, the height of newly formed bone in the experimental group was greater than that of the control group (4.3+/-0.9 mm, 0.22+/-0.28 mm, P<0.0001, n=6, paired t-test). These results indicate that PGS has characteristics of effective bone graft substitutes for implantation of rhBMP-2 on vertical alveolar ridge augmentation in huge defect of mandibles in dogs.

Distraction osteogenesis for craniosynostosis

Object

The authors describe the use of distraction devices and surgical techniques of distraction osteogenesis for the treatment of patients with craniosynostosis.

Methods

Since 1994, the authors have performed distraction procedures in 23 patients with craniosynostosis in whom osteogenesis was achieved. Thirteen of the 23 patients underwent a complete Le Fort III midface osteotomy and distraction. In 10 patients the distraction osteogenesis involved the cranial bone; six underwent combined forehead and midface distraction (Le Fort IV distraction) in which multiple internal devices were used after performing a Le Fort IV osteotomy.

An external distraction procedure was used to treat the first two cases. Since 1996, the authors have used internal devices developed in their unit.

Distraction was initiated 1 week after the osteotomy at the rate of 0.5 mm per day for the cranium and 1.0 mm per day for the midface. The consolidation phase after distraction was initiated was 2 to 3 months.

No major complications such as intracranial infection or neurological deficits were observed during the course of distraction osteogenesis. The osteogenesis generated at the distraction site was considerably satisfactory; and recurrence of the deformity in the follow-up period was minimal.

Conclusions

Distraction osteogenesis for craniofacial deformity has numerous advantages: 1) bone grafting is unnecessary; 2) the procedure is less invasive, has short operating time, and less blood loss occurs than in conventional craniofacial procedures; 3) no intracranial dead space is created; 4) there is a good amount of blood flow to the bone segment; and 5) soft-tissue expansion occurs. The authors believe that distraction osteogenesis is a versatile and stable option for the treatment of patients with craniosynostosis.

A thinned forearm flap transfer to the nose

We employed a forearm flap that had been thinned through primary defatting for nasal covering in three cases to reduce the need for secondary revision. Partial flap loss did occur in one case due to subcutaneous vascular plexus injury, but acceptable results were obtained in the remaining two cases. Donor site concave deformities were substantially reduced by removal of fat from around the flap margin. Great care must be taken during surgery to avoid damage to the small vascular network around the pedicle to prevent flap necrosis.

Histological examination of regenerated bone through craniofacial bone distraction in clinical studies

The process of bone formation by distraction osteogenesis of the craniofacial bone has been studied in animals. To our knowledge there are no published findings in which histological examination of craniofacial distraction in humans has been reported. Specimens were obtained from 10 patients who underwent craniofacial distraction: 2 patients who underwent mandibular distraction, 7 patients who underwent midface distraction, and 1 patient who underwent nasal bone distraction. These specimens were examined histologically. The results revealed that 8 of 10 patients exhibited new bone formation. No cartilaginous callus formation was observed in any of the specimens, which strongly suggests that new bone was produced by intramembranous ossification during human craniofacial bone distraction.

Vertical symphyseal osteotomy

For the treatment of mild crossbite with increased bigonial distance, the authors performed a vertical symphyseal osteotomy on six patients in the last 3 years. Three of these patients had cleft lip deformities and the others had operations for orthodontic or aesthetic reasons. After exposing the mandible through the buccal mucosal incision, both premolars were extracted with or without conventional segmental osteotomy. The two vertical symphyseal osteotomies were performed with approximately 1 cm between them, and the central part of the mandibular bone was discarded. The bilateral segments of the mandibular body were fixed in the midline using titanium miniplates. Satisfactory results were obtained with a reduction in the size of the mandibular arch, which produced better three-dimensional proportions in the bimaxillary area. No patients had temporomandibular joint problems, however postoperative orthodontics were essential for this type of operation.

Avoiding ectropion by using the Mitek Anchor System for flap fixation to the facial bones

The application of the Mitek Anchor System for bony fixation of the flap in the cheek area is described. The cervicofacial rotation-advancement flap is fixated to the malar bone using Mini Anchors for the purpose of diminishing the downward traction on the lower eyelid. They reduced the tension in the distal part of the flap and avoided distal-edge necrosis and ectropion. In another patient the free vascularized musculocutaneous flap, which had been grafted previously for a surgical defect in the cheek and resulted in ectropion of the lower eyelid, was fixated to the malar bone, and the ectropion was corrected. The Mitek Anchor System is useful in flap fixation to the bone because it provides a simple, fast, and reliable method for flap fixation with minimal dissection and precise placement.

Medical canthoplasty with the Mitek Anchor System

A variety of surgical techniques have been described for medial canthal tendon reattachment. They generally require technical skill and prolonged operating time. We have applied a new device, the Mitek Anchor System, in reattaching the medial canthal tendon to the medial orbital wall in 3 patients, and got excellent tendon fixation with this rapid and simple method. No complications, such as local infection or exposure, have occurred in any of the patients up to the present. Medial canthoplasty using the Mitek Anchor System has the advantage of being an easy technique with very accurate placement of the anchor and, consequently, reduced operating time. The operation can be performed through a small incision as well, and may not be so invasive as with other conventional procedures. This new technique of medial canthoplasty offers an excellent alternative to conventional techniques.

Combined use of an orbital osteotomy and living bone graft in the treatment of huge ossifying tumors involving the orbit

Huge ossifying tumors involving the orbit were treated with a combination of craniofacial surgery and microsurgical techniques in two patients. The orbital osteotomy facilitated wide exposure of the tumors and their excision even though the tumors were extremely large. Stable results were obtained in one stage without visual disturbance by simultaneous reconstruction of the resulting bony defects using a free vascularized bone graft even in unfavorable tissue beds such as when one side of the bone graft is exposed to the affected nasal cavity or maxillary sinus. The combination of craniofacial surgery and microsurgical techniques has proven in our experience to be an effective approach to the treatment of a huge orbital ossifying tumor in one stage.

Harvest of sural nerve grafts using the endoscope

Endoscopic surgical techniques were employed in 5 patients to harvest the sural nerve atraumatically with a minimal number of skin incisions. The medial sural nerve was harvested by two 2-cm-wide transverse incisions made under endoscopic-magnified visualization, which allowed the surgeon to see the detailed structure of the nerve and surrounding tissue. This method requires minimal traction of the nerve during nerve dissection, and postoperative pain and swelling were less than encountered with conventional methods, because the method we have employed is less invasive and atraumatic.

Extremely thinned inferior rectus abdominis free flap

To overcome a major drawback of the inferior rectus abdominis free flap, unpleasant thickness in a obese patient, a method of extreme thinning of the flap has been introduced. Extreme thinning is achieved by resecting a large volume of subcutaneous fatty tissue of the flap using scissors without damaging the subdermal vascular plexus. According to our clinical experience, it is supposed that the extremely thinned portion can be prepared safely when the width-to-length ratio is within 1:2.

A long surviving case of holoprosencephaly agnathia series

The rare syndrome of the agnathia with microstomia, aglossia, synotia (the external ears approaching one another in the midline) and brain malformation (agnathia-holoprosencephaly) was reported by Pauli et al. (1983) as a developmental field defect. This syndrome has two subgroups. One is more severe with brain malformation (holoprosencephaly), and the other is less severe without brain malformation. This report presents a long surviving case of this syndrome without brain malformation.

A histopathologic study of spinal cord ischemia using an isohistogenic rat upper-half-body transplantation model

To study the histopathologic changes of spinal cords exposed to long-duration complete ischemia, the authors developed an upper-half-body transplantation model of inbred rat. In this model, an infant Lewis rat is transplanted to the inguinal region of another adult Lewis rat using microsurgical vascular anastomosis. Even when 2-week-old donor rats were exposed to complete ischemia for 90 minutes, functions of the spinal cord were comparatively preserved. In histopathologic observations, degeneration proportional to complete ischemia duration was noted. In the 60-minute ischemia group of 2-week-old donor rats, however, no substantial differences from normal spinal cord were observed. Under conditions of equal ischemia duration, it appeared the younger animal had the greater ischemic tolerance.

Microsurgical facial reconstruction of a xeroderma pigmentosum patient after skin tumor resection: case report

Microsurgical reconstruction of the face completely destroyed after malignant skin tumor excisions in a xeroderma pigmentosum patient is reported. The patient's left cheek was reconstructed using a free latissimus dorsi flap and the nose using a free forearm flap with a base of iliac bone graft. There has been no recurrence of tumor at or surrounding the transferred flap site over two years postoperative follow-up.

P waves in acute myocardial infarction

Relationships between P wave abnormalities in lead II and V1 and clinical as well as hemodynamic findings and the prognosis of 27 attacks of AMI were evaluated. 1) Patients with clinical left ventricular failure showed large negative deflections in lead V1 compared to patients without. 2) There was a significant correlation between the magnitude of PTF-V1 and PCW (r=-0.75, p less than 0.01). 3) In 20 of the 27 attacks (74%), PTF-V1 correctly identified whether or not PCW was normal on admission. 4) Patients with frequent premature beats and any of the bundle branch blocks had a large negative deflection in V1 compared to patients without. 5) There was a significant correlation between the magnitude of PTF-V1 and Peel's prognostic index (r=-0.74, p less than 0.01). Moreover, 70% of the patients with abnormal PTF-V1 (less than -0.03 mm-sec) and elevated Peel's prognostic index (more than 12) died during hospitalization. 6) The patients who died during hospitalization had a large negative deflection in lead V1 compared to those patients who survived. 7) Patients with past history of old myocardial infarction had a larger negative deflection in lead V1 compared to the patients without past history of old myocardial infarction. 8) There is no correlation between the duration and amplitude of P wave in lead II and PCW. 9) Thus, it is concluded that in patients with AMI, the magnitude of PTF-V1 reflects the level of PCW and is useful as a parameter for therapy and prognosis evaluation.