Hans-Albert Merten

Results of treatment of fractures of the atrophic edentulous mandible by compression plating: A retrospective evaluation of 84 consecutive cases

PURPOSE This article introduces a simple and reproducible classification of the degree of atrophy in fractures of the atrophic edentulous mandible, and evaluates the results of treatment in 84 consecutive fractures based on this classification. MATERIAL AND METHODS Eight-four fractures of the edentulous mandible, with a height at the fracture site of < or = 20 mm, were included. Using the ratio of actual plate width to plate width on the postoperative radiograph, the actual height of the mandible at the fracture site was calculated. Twenty-five fractures (30%) were in the Class I atrophy group (height at the fracture site 16 to 20 mm), 33 fractures (39%) occurred in Class II atrophic mandibles (height 11 to 15 mm), and 26 fractures (31%) were seen in extremely atrophic Class III mandibles (height < or = 10 mm). The treatment was performed by compression plating without any postoperative MMF. Primary bone grafting was used in six cases (7%) because a partial bone defect was present at the fracture site. RESULTS In 81 (96.5%) of the 84 fractures an uncomplicated, solid, bony union was achieved. Three major complications occurred: one osteomyelitis and two nonunions. The two nonunions occurred in bilateral fracture of an extremely atrophied mandible (Class III atrophy). Minor soft tissue infections, without interference with fracture healing, were observed in six cases (7%). CONCLUSIONS Because there is an obvious relation between the height of the mandible and the incidence of complications in fracture healing, a special classification of the degree of atrophy is needed. In fractures of the extremely atrophic mandible (Class III atrophy) periosteal degloving should be avoided and supraperiosteal placement of plates is recommended. Compression osteosynthesis has proved to be a successful method, with minimal impairment of the patient and a low frequency of serious complications.

Hydroxyapatite cement (BoneSourceTM) for repair of critical sized calvarian defects—an experimental study

AIM In an experimental study the hydroxyapatite cement BoneSource was tested for the ability in relation to the defect size and for its resorption properties. MATERIAL AND METHODS In an animal study, BoneSource was applied to repair bicortical defects of different sizes in frontal bones of six Goettingen minipigs. The area was evaluated radiographically and histologically 12, 18 and 40 weeks postoperatively. RESULTS After 40 weeks approximately 90% of the hydroxyapatite cement had been resorbed and replaced with bone. After 12 weeks, approximately 30% had been degraded, and 40% after 18 weeks. In small bone defects, the mucosa of the frontal sinus lined the bone substitute (BoneSource). In the reconstruction of large areas, a membrane was used to stabilize the material. Despite this membranous support, BoneSource material prolapsed into the frontal sinus. DISCUSSION Hydroxyapatite cement is for the repair of bone defects. It can be moulded to shape the reconstruction. Its use is limited by the defect size and the need for a dry bed. CONCLUSION BoneSource is well suited to repair small defects with proven high biocompatibility. However, in large defects, the material is not sufficiently stable.

Sinus floor augmentation with recombinant human growth and differentiation factor-5 (rhGDF-5): a pilot study in the Goettingen miniature pig comparing autogenous bone and rhGDF-5

AIM The aim of this study was to test the hypothesis that recombinant human growth and differentiation factor-5 (rhGDF-5) in combination with a beta-tricalcium phosphate (beta-TCP) scaffold material results in superior bone formation in sinus floor augmentations in miniature pigs compared with a particulated autogenous bone graft combined with the scaffold material. MATERIAL AND METHODS Six adult female Goettingen minipigs underwent a maxillary sinus floor augmentation procedure. In a split-mouth design, the sinus floors were augmented with beta-TCP mixed with autogenous cortical bone chips, in a ratio of approximately 1 : 1, on one side. The contralateral test site was augmented using beta-TCP coated with two concentrations of rhGDF-5 (400 microg rhGDF-5/g beta-TCP or 800 microg rhGDF-5/g beta-TCP; three animals in each case). Simultaneously, one dental implant was inserted into each sinus floor augmentation. After 12 weeks, a histological and histomorphometric assessment of non-decalcified histological specimens was made. RESULTS There were significantly higher mean values of volume density of newly formed bone using beta-TCP coated with two concentrations of rhGDF-5 (400 microg: 32.9%; 800 microg: 23.9%) than with the corresponding control (autogenous bone/beta-TCP) (14.6%, 12.9%) (P=0.012, P=0.049). The bone-to-implant contact rates (BIC) were significantly enhanced in test sites (400 microg: 84.2%; 800 microg: 69.8%) compared with the corresponding control sites (24.8%, 40.8%) (P=.027, P=.045). CONCLUSION rhGDF-5 delivered on beta-TCP significantly enhanced bone formation compared with beta-TCP combined with autogenous bone in sinus lift procedures in miniature pigs.

The resorbable miniplate system lactosorb in a growing cranio-osteoplasty animal model

In the surgical treatment of craniosynostosis and craniofacial dysostosis in the growing child, passive intraosseous translocation (PIT effect) with intracranial displacement of metal plates and screws may be a problem. In an animal experiment, a possible PIT effect using resorbable PLA/PGA miniplates (Lactosorb, W. Lorenz, FL, USA) following cranio-osteoplasty were investigated in four young Göttingen minipigs. In addition to the mechanical properties, the processes of degradation and of sub- vs supraperiosteal application of the miniplates were evaluated. During degradation the resorbable PLA/PGA miniplates performed like metal plates as they also displayed passive intraosseous translocation in the growing animal model. However, in the experimental PLA/PGA miniplating the internal calvarial bone was not affected. Degradation took 12-18 months and was not delayed by bony incorporation. Mechanical properties proved to be sufficient in craniofacial surgery. Supraperiosteal plating delayed the PIT effect during the first 3 months after surgery. In the growing skull resorbable plates seem to be a promising therapeutic approach. However, prior to a general recommendation results of long-term clinical studies have to be evaluated.

Cellular, Histomorphologic, and Clinical Characteristics of a New Octyl-2-Cyanoacrylate Skin Adhesive

Short-chained cyanoacrylates have been used for many years for topical skin closure. Toxic effects in cell culture of a new long-chained octyl-2-cyanoacrylate tissue adhesive are compared with those of short-chained ethyl-2- and butyl-2-cyanoacrylates. Two cellular tests were used: the agar overlay test and the MTT test. An in vitro test using copper plates coated with the three types of cyanoacrylates serves for evaluating the stability of polymerized skin adhesives. Bilateral neck skin incisions in Goettingen miniature pigs were glued on one side with Dermabond. On the other side, conventional sutures were applied. After the pigs were killed, the resulting skin samples were tested for the tensile strength of their wound stability. Samples of pig dermis were exemplarily and histomorphologically characterized. A clinical examination after submandibular lymph node dissection should examine the application in humans. Cell culture tests were used to show the toxic effects of the three cyanoacrylates. In a copper test, octyl-2-cyanoacrylate was more stabile than ethyl- and butyl-cyanoacrylates. Breaking strength was 30% lower 28 days after operation with the new product than with sutures. In electron microscopy, octyl-2-cyanoacrylate showed no disadvantages with regard to tissue regeneration and no histotoxicity. For plastic surgery, this new topical skin adhesive is a real alternative with attractive results, as compared with conventional suture.

Subperiosteal versus epiperiosteal forehead augmentation with hydroxylapatite for aesthetic facial contouring: Experimental animal investigation and clinical application

The difference between periosteal and subperiosteal application of hydroxylapatite (HA) in aesthetic forehead augmentation in the subimplant bed was investigated in six adult Göttingen minipigs. These results were then transferred to clinical application. One exemplary case is described. We found that epiperiosteal augmentation with hydroxylapatite should be performed only if shape and location are stable. Subperiosteal augmentation with hydroxylapatite must be judged critically since HA particles migrate into the subimplant bone.

Intraindividueller Vergleich von α- und β-TCP-Keramik im Tierexperiment

Im Links-rechts-Vergleich wurden bei ¶7 adulten Göttinger Miniaturschweinen proximale Tibiamarkraumdefekte kritischer Größe präpariert und links mit granulärer β-Trikalziumphosphat(TCP)-Keramik ad modum Cerasorb sowie rechts mit granulärer α-TCP-Keramik ad modum Biobase α pore aufgefüllt. Zeitgleich wurden zudem dentale Schraubenimplantate (ITI) in die jeweiligen Keramiken mit inseriert und im orthotop replantierten Kortikalisdeckel stabil fixiert. Bei 2 weiteren Tieren wurden Kontrolldefekte angelegt. Die Standzeiten reichten von 4–68 Wochen (Leerversuch: 16 und 20 Wochen). An unentkalkten Stufenschnitten wurden für die beiden Keramikspezifitäten Form und Ausmaß der Knochenregeneration, die Dynamik der Keramikdegradation sowie das Remodellationsverhalten der Knochen-Keramik-Regenerate im Zusammenhang mit der Osseointegration der Dentalimplantate histomorphologisch untersucht. Ergebnisse: 1. Beide Keramikspezifitäten wirken ausschließlich osteokonduktiv, wobei die zentripetal orientierte angiogene Knochenregeneration aus den zirkulären Defektlagerrändern erfolgt. 2. Die Keramikdegradation erfolgt hydrolytisch sowie zellulär, wobei der definitive Abbau der intratrabekulär integrierten Keramikreste dem dynamischen Remodellationsprozess unterliegt. 3. Nach 68 Wochen sind annähernd 80–90% der etwas größer dimensionierten α-TCP-Granula und etwa 90–95% der β-TCP-Granula abgebaut. Im Markraum sind zu dieser Zeit allerdings besonders bei der α-TCP-Modifikation noch Mikrokeramikpartikel in freier Form sowie in mehrkernigen Makrophagen nachweisbar. 4. Die programmierte Degradation beider TCP-Keramiken gewährleistet eine frühzeitige funktionelle Adaptation der Knochenregenerate und ermöglicht somit eine verzögerungsfreie biofunktionelle, anisotrope Orientierung der Neotrabekel. 5. Wegen einer initial gesteigerten Makrophagenakkumulation sollten Dentalimplantate zweizeitig, d. h. nach fortgeschrittenem Abbau der Keramiken (etwa 5–6 Monate nach TCP-Implantation) inseriert werden. In the quest for bioinert adaptable alloplastic materials, TCP ceramics have gained a new application in craniofacial bone substitutes. Therefore, a histomorphological, intraindividual, comparative study was conducted on seven adult Goettingen miniature pigs (GMP) to analyze the difference of the degradation and remodelling processes of α-TCP and β-TCP in critical size defects of the proximal tibiae. In addition, primary insertion of dental implants followed to study osseous integration. The critical size defects, which were created in the proximal tibiae in GMPs, were filled on the left side with β-TCP and on the right side with α-TCP. Two GMPs were used as control group. After 4–68 weeks of investigation, the GMPs were sacrificed by narcosis. The histological investigation showed that these ceramics have an osteoconductive effect. It was noted that ossification proceeds centripetally. It could be demonstrated that the degradation of the materials follows a hydrolytical process and that the intratrabecular integrated ceramic remnants follow a dynamic remodelling process. Within 68 weeks after implantation, 90% of the TCP granulae were degraded. Macrophages were found in the marrow space, containing microparticles of TCP, especially after α-TCP implantation. In conclusion, defined degradation of these ceramics allows early functional bone regeneration with an additional undisturbed biofunctional unisotrop orientation of new trabeculae. Furthermore, dental implants should be inserted 5–6 months after TCP implantation.In the quest for bioinert adaptable alloplastic materials, TCP ceramics have gained a new application in craniofacial bone substitutes. Therefore, a histomorphological, intraindividual, comparative study was conducted on seven adult Goettingen miniature pigs (GMP) to analyze the difference of the degradation and remodelling processes of alpha-TCP and beta-TCP in critical size defects of the proximal tibiae. In addition, primary insertion of dental implants followed to study osseous integration. The critical size defects, which were created in the proximal tibiae in GMPs, were filled on the left side with beta-TCP and on the right side with alpha-TCP. Two GMPs were used as control group. After 4-68 weeks of investigation, the GMPs were sacrificed by narcosis. The histological investigation showed that these ceramics have an osteoconductive effect. It was noted that ossification proceeds centripetally. It could be demonstrated that the degradation of the materials follows a hydrolytical process and that the intratrabecular integrated ceramic remnants follow a dynamic remodelling process. Within 68 weeks after implantation, 90% of the TCP granulae were degraded. Macrophages were found in the marrow space, containing microparticles of TCP, especially after alpha-TCP implantation. In conclusion, defined degradation of these ceramics allows early functional bone regeneration with an additional undisturbed biofunctional unisotrop orientation of new trabeculae. Furthermore, dental implants should be inserted 5-6 months after TCP implantation.

A new condylar positioning technique in orthognathic surgery

In two-jaw surgery, special importance must be attached to the maintenance of the condylar position, particularly in combination with rigid fixation, not only to enhance the stability of the post-operative result but also to avoid iatrogenic temporomandibular joint complications. The new positioning method reported herein is based on a mini fragmentation plate, which can be easily adapted to the bone surface. Reinforcement of the plate by autopolymerizing acrylate, injected into a silicone tube which is pushed over the plate, prevents any unnoticed deformation of the positioning device during surgery. In clinical use, this positioning method has proved to be more versatile and technically less difficult to perform than previous techniques, without any decrease in reliability.

Evaluation der B-Scan-Sonographie, 3D-Sonographie, Röntgendiagnostik und Sinuskopie zur Kontrolle der Kieferhöhle nach Sinusbodenelevation

Fragestellung. Es sollte geprüft werden, welche Wertigkeit die B-Scan-Sonographie, 3D-Sonographie, Röntgendiagnostik und Sinuskopie zur Diagnostik von Kieferhöhlenveränderungen nach Sinusbodenelevation besitzen. Material und Methode. Bei 33 Patienten wurden vor der Sinusbodenelevation sowie 1 Woche und 6 Monate postoperativ die Kieferhöhlen mittels eines 7,5-MHz-Linearschallkopfs sowie 3D-sonographisch untersucht. Die sonographischen Befunde der Nasennebenhöhle, die röntgenologischen Nasennebenhöhlenaufnahmen, das Dental-CT oder Orthopantomogramm und die sinuskopischen Befunde wurden verglichen. Die Sinuskopien erfolgten nur im Rahmen der Sinusbodenelevation und bei der Implantatfreilegung nach 6 Monaten. Ergebnisse. Insgesamt wurden 56 Sinusbodenelevationen mit simultaner Knochentransplantation durchgeführt. Präoperativ waren in allen Untersuchungsverfahren keine Auffälligkeiten in den Kieferhöhlen nachweisbar. 1 Woche postoperativ bestanden in 40 Kieferhöhlen Schwellungen der Mukosa, die sowohl sonographisch als auch röntgenologisch nachweisbar waren. Nach der Einheilungsphase der Knochentransplantate von 6 Monaten persistierten in 3 Kieferhöhlen sowohl sonographisch als auch röntgenologisch als auch sinuskopisch identifizierbare polypöse Veränderungen. Die 3D-Sonographie erhöhte dabei die Vergleichbarkeit und die Reproduzierbarkeit der sonographischen Ergebnisse. Schlussfolgerungen. Wegen der fehlenden Strahlenbelastung, Kostengünstigkeit und der beliebig oft durchführbaren Untersuchungsmöglichkeit ist die Sonographie als primäres Screeningverfahren im Recall geeignet. Bei unauffälligen Sonogrammen, aber klinischer Symptomatik sollten dann das CT, das MRT oder die Sinuskopie eingesetzt werden, um Prozesse an der Sinushinterwand sicher auszuschließen. Problem. The aim of this study was to determine which technique – B-scan sonography, 3D sonography, X-ray, or endoscopy – is the most effective for diagnosis in changes of the maxillary sinus after sinus lift and simultaneous augmentation. Material and methods. In 33 patients the maxillary sinus was examined before sinus lift, 1 week and 6 months postoperatively with a 7.5-MHz linear scanner and 3D sonography. At the same time, the sonographic results were compared with the X-ray as well as the endoscopic results. Endoscopy of the maxillary sinus was only applied during the sinus lift operation and the abutment operation after 6 months. Results. A total of 56 operations of sinus lift and simultaneous augmentation with autogenous bone were carried out. Preoperatively, there where no pathological findings detectable in the maxillary sinus. One week postoperatively, the X-rays as well as the sonographic images revealed thickening of the mucosa in 40 maxillary sinuses. After the healing period of 6 months, polyposa was still detected in three cases sonographically, in the radiographic follow-up as well as endoscopically. The sonographic 3D imaging of the maxillary sinus improved the spatial visualization of postoperative changes in the maxillary sinus and the reliability of the diagnosis. Conclusion. Due to the lack of radiation, the cost effectiveness, and its reproducibility, sonography is suitable as a primary screening technique in recall. In cases of normal sonographic findings but clinical symptoms, CT, MRT, and endoscopy should be performed to exclude pathological processes of the posterior maxillary sinus.

The Multipoint Contact Plate in Fracture Treatment of the Atrophied Mandible: Animal Study and Clinical Application

&NA; Rapid consolidation of osseous fractures requires stable immobilization of the fragments. In the atrophied mandible, the nutrient supply should be ensured by protecting the periosseous soft tissue, i.e., the periosteum. In the conventional placement of osteosynthesis plates, however, the subimplant nutrition is restricted because of the high surface pressure between the osteosynthesis plate and bone. In order to improve the subimplant nutrient supply, we designed a new osteosynthesis plate with a “knobbed” underside enabling multipoint contact. Histomorphologic comparative studies were conducted on 16 Göttingen minipigs with an average weight of 47.5 ± 8 kg. In each minipig, one side of the mandible was fractured and one side was left intact. One side of each mandible was plated with a six‐hole dynamic multipoint contact plate and the other side with a conventional plate. The plates were applied, either epiosseous or epiperiosteal, with bicortical screws under defined torque. The results demonstrate the advantages of multipoint contact plates over the conventional ones and create the clinical basis for a “bio‐logical” plate design that allows callus to grow between the knobs and therefore provide adequate nutritional and vascular supply. The plates knobbed profile also promotes extraosseous venous drainage without impeding intraosseous fluid flow. This plate is the logical choice for rapid fracture consolidation in the high‐grade atrophied mandible. (Plast. Reconstr. Surg. 97: 1158, 1996.)