Porcine fetal enamel matrix derivative enhances bone formation induced by demineralized freeze dried bone allograft in vivo

BACKGROUND: Embryonic enamel matrix proteins are involved in the formation of acellular cementum during development of the periodontal attachment apparatus, suggesting that these proteins might be used clinically to promote periodontal regeneration. At present, it is unknown if these proteins are osteoinductive, osteoconductive, or osteopromotive. To address this question, we examined the ability of a commercially prepared embryonic porcine enamel matrix derivative to induce new bone formation in nude mouse calf muscle, or to enhance the bone induction ability of a demineralized freeze-dried bone allograft (DFDBA). METHODS: Porcine fetal enamel matrix derivative (EMD) was implanted bilaterally in the calf muscle of 4 male Nu/Nu mice per treatment group (N = 8 implants): 2 mg EMD alone; 4 mg EMD alone; inactive human DFDBA alone; inactive DFDBA + 2 mg EMD; inactive DFDBA + 4 mg EMD; active DFDBA alone; active DFDBA + 2 mg EMD; and active DFDBA + 4 mg EMD. Implants were harvested after 56 days and examined histologically for bone induction using a semi-quantitative score and histomorphometrically for area of new bone, cortical bone, bone marrow, and residual DFDBA. RESULTS: Implants containing inactive DFDBA, 2 mg EMD, 4 mg EMD, and inactive DFDBA + 2 or 4 mg EMD did not induce new bone. Active DFDBA and active DFDBA + 2 mg EMD induced new bone to a similar extent. In contrast, active DFDBA + 4 mg EMD resulted in enhanced bone induction, area of new bone, and cortical bone. Residual DFDBA was also increased in this group. CONCLUSIONS: EMD is not osteoinductive. However, it is osteopromotive, due in part to its osteoconductive properties, but a threshold concentration is required.     

Evaluation of guided bone regeneration and/or bone grafts in the treatment of ligature-induced peri-implantitis defects: a morphometric study in dogs

The goal of this study was to evaluate, morphometrically, hard-tissue healing following the treatment of ligature-induced peri-implantitis defects in dogs and guided bone regeneration and/or bone grafts. Five dogs were used, and the mandibular premolars were removed. Three months later, two titanium implants were installed on each side of the mandible, and after another 3 months, abutment connection was performed. Following abutment connection, experimental periimplantitis was induced by placing cotton ligatures in a submarginal position. Ligatures and abutments were removed after 1 month and the bony defects were randomly assigned to one of the following treatments: debridement (DE), debridement plus guided bone regeneration (GBR), debridement plus mineralized bone graft (BG), and debridement plus guided bone regeneration associated with mineralized bone graft (GBR/BG). The dogs were euthanatized after 5 months. Morphometric analysis did not reveal significant differences among the treatments neither with respect to the percentage of bone to implant contact (p = 0.996) nor to the bone area (p = 0.946) within the limits of the threads of the implant. Within the limits of this investigation, there is insufficient evidence to indicate that any of the treatments presented an improved response in dealing with bony defects resulting from peri-implantitis.     

Treatment of a large periapical lesion with loss of labial cortical plate using GTR: a case report

Following endodontic treatment, a large periapical lesion (9.0 mm x 9.0 mm) at a maxillary central incisor was treated with demineralized freeze-dried bone allograft (DFDBA) using the principles of guided tissue regeneration. The physical barrier was removed 6 months postsurgical. The cortical alveolar plate was observed to be completely reconstructed. Histologic evaluation demonstrated lamellar bone surrounding DFDBA particles. Radiographic follow-up 1 year posttreatment demonstrated complete resolution of the periapical radiolucency.     

Das Doppelsplintverfahren zur Vorbereitung einer simultanen chirurgischen Lagekorrektur des Ober- und Unterkiefers

Zusammenfassung Die Genauigkeit der Fixation bei der chirurgischen simultanen Lagekorrektur von Maxilla und Mandibula ist eine wesentliche Voraussetzung für ein gutes Operationsergebnis. Hier soll das an der Frankfurter Universitätsklinik praktizierte Doppelsplintverfahren vorgestellt werden. Zwei Hartgipsmodellpaare des Patienten werden auf zwei halbjustierbare Artikulatoren mit Hilfe des Quick-Mount Face Bows übertragen und montiert. Auf den Arbeitsmodellen werden Referenzlinien für die Zahn- und Kieferpositionen eingezeichnet. Zunächst wird das Oberkiefermodell wie bei einer Le-Fort-I-Operation durchgesägt. Dann wird ein Wachsbiß hergestellt, der später in Kunststoff überführt werden soll. Der in gelenkbezüglicher Zentrallage der Kondylen hergestellte Splint dient bei der Operation zur Orientierung und Fixierung des Oberkiefers in seiner neuen Position, während der Unterkiefer noch intakt ist. Danach wird das Unterkiefermodell durchtrennt und so weit verschoben, bis im Eckzahnbereich eine neutrale Okklusion erreicht ist. Überkorrekturen werden routinemäßig zu diesem Zeitpunkt je nach vorliegenden Anomalien und deren Rezidivtendenzen eingebaut. Der zweite Wachsbiß wird in dieser neuen Position hergestellt und ebenfalls in Kunststoff überführt. Dieser Splint dient bei der Operation zur Fixierung der Kiefersegmente in der vorgesehenen, endgültigen Position und bleibt während der ganzen Fixationsperiode im Mund des Patienten. Auf diese Weise verliert der Operateur während der gesamten Operation trotz Kontinuitätsunterbrechung im maxillären und mandibulären Bereich nie die Orientierung und erreicht eine funktionsgerechte, gelenkbezügliche Okklusion, die eine Grundvoraussetzung für die Stabilität des Operationsergebnisses darstellt.

---

Summary The precise fixation of bony segments in simultaneous two-jaw surgery plays an important role in obtaining good results from this treatment. The author recommends, for orthodontists who intend to be members of surgical-orthodontic teams, a method which is modified and developed from previous technics. Two pairs of dental models were mounted on two semi-adjustable articulators, one as a control and one as a working articulator. In the first step, the model surgery is performed according to Le Fort I operation on the upper model, as determined by cephalometric prediction tracing. An interocclusal wax-bite is fabricated and is processed later into an acrylic splint. This splint is used to fix the maxilla into the new predetermined position by closing the intact mandible in hinge axis anterior rotation. The second step is model surgery on the lower model, moving the mandible into the class I canine occlusal relationship. Over-correction my be done at this stage. The second interocclusal wax-bite is fabricated by the same technic as the first wax-bite and processed into an acrylic splint. During surgery, the second splint is used to fix the maxilla and the mandible together in the predetermined final position, and it remains in position through the whole period of fixation. With this procedure, the surgeon will not lose the orientation during the fixation of simultaneous repositioned jaw bones, and a better result may be expected.

---

Résumé La fixation précise des segments osseux dans la chirurgie bimaxillaire simultanée joue un rôle important dans l'obtention d'un bon résultat de traitement. L'auteur voudrait recommander aux orthodontistes désireux de faire partie d'une équipe de chirurgie orthodontique une méthode modifée et dérivée de techniques précédentes. Deux paires de moulages sont montées sur des articulateurs semiadaptables, l'un comme contrôle, l'autre utilisé comme articulateur de travail. La chirurgie simulée sur le moulage supérieur est exécutée suivant une opération de Le Fort I, déterminée par l'objectif du tracé céphalométrique. Un mordu en cire d'occlusion est établi, qui sera par la suite mis en moufle pour obtenir un plan d'occlusion acrylique, ou splint. Ce splint sera utilisé afin de fixer le maxillaire dans la nouvelle position prédéterminée en amenant la mandibule intacte en occlusion selon une rotation autour de l'axe charnière. La seconde étape est la chirurgie simulée sur le moulage mandibulaire et le déplacement en occlusion canine de Classe I. Une hypercorrection est parfois souhaitable à ce niveau. Le deuxième mordu en cire est établi, pour fabriquer un plan d'occlusion acrylique, comme précédemment. Ce deuxième splint sera utilisé pour fixer la mandibule aux maxillaire dans la position prédéterminée, pendant toute la durée de la fixation. De cette façon le chirurgien ne perdra pas l'orientation pendant la fixation de fragments maxillaires et mandibulaires repositionnés simultanément, et un meilleur résultat peut être attendu.

     

Advances in subperiosteal implant reconstruction

Recent advances in subperiosteal implant surgery of the mandible and maxilla are described in terms of changes in implant design, use of particulate autogenous marrow cancellous bone in conjunction with subperiosteal implant to structurally rebuild marked deficient mandibles at the time the implant is placed, and the of computerized tomography to develop a three-dimensional model for the construction of implant framework, eliminating the direct bone impression surgery. The latter procedure has revolutionized the use of subperiosteal implants. These techniques are outlined, and areas of future research in use of implants in structurally deficient areas are described.     

Solitary calvarial plasmacytoma.

One patient with a solitary plasmacytoma of the frontal bone was treated with complete surgical resection. To reconstruct the large calvarial defect, a split-thickness calvarial graft was harvested from the parietal area and secured in place with miniplates. Solitary plasmacytomas of the calvaria are not common. Clinical presentation, diagnostic criteria, therapeutic approaches, and prognosis are discussed.     

Demineralized bone matrix polydioxanone composite as a substitute for bone graft: a comparative study in rats.

Demineralized bone matrix (DBM) has been successfully used as a substitute for bone grafting. Autogenous bone grafts (ABG) may cause donor site morbidity and undergo significant resorption. DBM may overcome these problems but is mechanically unstable when originally placed. We explored using a slowly resorbable template, polydioxanone (PDS), in combination with DBM and compared it to ABG in a rat 9 x 9 mm cranial defect model. After both 1 and 3 months, histologically and biochemically well-formed bone was present in ABG/PDS and DBM/PDS-treated defects, but not in control defects (PDS alone). Mechanical push-out tests using a servohydraulic testing frame were conducted. Maximum load before failure of DBM/PDS increased from 65% at 1 month to 100% of that of intact skull at 3 months. In contrast, ABG/PDS was 50% as strong as DBM/PDS and not significantly stronger than PDS alone. ABG/DBM did not significantly increase in strength from 1 to 3 months. We conclude that DBM/PDS is better than ABG/PDS in treating cranial defects in the rat model, and that an absorbable osteoinductive bone substitute with superior mechanical advantage is possible without the disadvantages of ABG.     

An in utero model of craniosynostosis.

To define better the pathophysiology of craniosynostosis, we developed an in utero model in rabbits. Premature fusion of the sutures was achieved by osteoinduction using demineralized bone matrix (DBM). Thirty-six fetuses from 18 time-dated pregnant rabbits underwent coronal strip craniectomies and implantation of DBM at 25 days of gestation (term = 31 days). Seventeen (47%) survived vaginal delivery and 10 (28%) survived for long-term follow-up. Surviving, operated animals demonstrated bony fusion across the coronal sutures presumably due to osteoinduction by the DBM. Coronal computed tomographic scans with sagittal reconstructions revealed that experimental animals had taller and wider skulls than nonoperated control animals. We conclude that employing DBM to create craniosynostosis in the fetal rabbit is technically feasible. Such a model may be used to more clearly define the pathophysiology of craniosynostosis and to evaluate methods of treatment.     

Effect of altered occlusal guidance on lateral border movement of the mandible

The purpose of this study was to evaluate the effects of a change in the lateral anterior guidance pathway on the lateral border movement pathway of mandible. The results showed that altered occlusal guidance reproducibly and reversibly changed (increased) the lateral border movement area in two subjects who had unilaterally restricted lateral border movements.