[Intra-individual comparison of alpha- and beta-TCP ceramics in an animal experiment]. / Intraindividueller Vergleich von alpha- und beta-TCP-Keramik im Tierexperiment.

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.

[The development of modern osteosynthesis]. / Entwicklung der modernen Osteosynthese.

Within the last 30 years, rigid fixation has revolutionized a wide range of treatment procedures in cranio-maxillofacial surgery. Rigid fixation allows for a three-dimensional reconstruction of the facial skeleton. In fracture treatment and following osteotomies in orthognathic surgery, any postoperative maxillo-mandibular fixation by dental arch bars can be avoided. Rigid plate and screw fixation began in 1886 when the Hamburg surgeon Carl Hansmann presented his experiences with the plate and screw system, which he had developed. Besides fractures of the extremities, Hansmann also reported about two cases of mandible fractures he had treated. Thus, Hansmann is the first representative of rigid plate fixation in maxillofacial surgery. Because of the high rate of complications, plate and screw osteosynthesis was not generally accepted for a long time. This changed when the Belgian surgeon Robert Danis in 1949 introduced the principle of axial compression of the fracture ends. His idea of axial compression was picked up by the ASIF Swiss research group and was further developed for clinical application in trauma surgery of the long bones in the early 1960s. Because of anatomical reasons, appliances used by the ASIF in the surgery of extremities could not be used in maxillofacial surgery. Therefore, in 1968, Luhr developed an automatic compression plate, which in a simple way realized the principle of axial compression. With this compression screw plate, Luhr performed, in 1967, the first compression plating in the maxillo-facial area in the world. Numerous publications by other authors about similar procedures followed. Different treatment principles using monocortical mini plates without axial compression for treatment of mandibular fractures and later also for fractures of the midface were introduced, namely, by Michelet and also by Champy. Based on the experiences of fracture treatment by plate and screw fixation, various systems for mandibular reconstruction following tumor resection or defect fractures were developed. With these reconstruction plates, a rigid alloplastic bridging of defects could be performed as well as rigid fixation of bone grafts using axial compression. The main advantage of these procedures was the avoidance of any postoperative MMF. Rigid fixation has also revolutionized orthognathic surgery. The avoidance of any MMF following osteotomies of the facial skeleton was the main advantage. The introduction of implant materials, which are highly resistant to corrosion (vitallium, titanium), and the development of plating systems of adequate dimensions for use within different areas of the complex facial skeleton has led to a high degree of perfection of rigid fixation in cranio-maxillofacial surgery.

[Clinical studies on the pathophysiology of odontogenic abscesses]. / Klinische Untersuchungen zur Pathophysiologie dentogen bedingter Abszesse.

In 26 patients with abscesses in the maxillofacial area, the electrolyte concentrations, pH and osmotic and hydrostatic pressures of the pus fluid were measured and calculated. The main cations identified were sodium (134 +/- 38 mmol/l) and potassium (37 +/- 16 mmol/l) and as anions chloride (183 +/- 46 mmol/l) and bicarbonate (10 +/- 4 mmol/l). The pH value of the pus liquid was 6.164 +/- 0.233. The calculated mean osmotic pressure of the pus liquid was 7910 +/- 1455 mm Hg, whereas the measured physical pressure inside the abscess was 49 +/- 13 mm Hg. Both pressure types show time-dependent pressure curves. With time, the real pressure inside the abscess cavity increases, whereas the osmotic pressure decreases. There was no relationship between the two pressure types and the different species of microorganisms responsible for the inflammation. The results of the study reveal that abscesses can be regarded as osmotically active systems, and the mechanism by which the abscess is formed might be as follows. After penetration of virulent microorganisms into the tissue space, the area of acute inflammation is walled off by the collection of inflammatory cells. Destruction of tissue by products of the polymorphonuclear leucozytes takes place and results in liquefactive necrosis and a hypertonic abscess cavity. The inwards-directed flow of tissue fluids into the cavity via the abscess membrane causes volume expansion and generates pressure, two facts that can explain the swelling dynamics and typical symptoms of abscesses in the maxillofacial area.

[Biodegradable miniplates (lactosorb) in cranio-osteoplasty--experimental results with the rapidly maturing, juvenile minipig]. / Biodegradierbare Miniplatten (Lactosorb) bei Kranioosteoplastik--experimentelle Ergebnisse am schnell wachsenden, juvenilen Miniaturschwein.

As a passive intracranial transmission (PIT- effect) has been described for metallic osteosyntheses materials in the infant growing skull. Thereby the use of resorbable plates and screws might be an alernative fixation device in infant craniofacial surgery. For evaluating the biological behaviour, craniotomies were performed in the frontoorbital region of four infant minipigs, six weeks of age and 6.1 kg of weight. After turning and orthotopical repositioning the full thickness bone graft were fixed with resorbable plates and screws made of LactoSorb on the left side after epiperiosteal, on the right side after subperiosteal preparation. The animals were sacrificed after 3, 6, 9 and 18 months. Histologically, a PIT- effect was detected similar to metallic microplates and screws being significant diminished after epiperiosteal preparation and plate positioning. The biodegradation was not affected by intraosseous translocation. Even in case of intrasinuidal transmission no inflammatory reactions werde observed. No contraindications for the clinical use of this specific PLLA-PGA copolymer could be found when implanted in the rapidly growing craniofacial bone surfaces.

[Results of the application of the Goettingen concept for three-dimensional repositioning of the maxilla in orthognathic surgery]. / Ergebnisse der Anwendung des Göttinger Konzepts zur räumlichen Einstellung des Oberkiefers nach Umstellungsosteotomien.

During orthodontic-surgical treatment, a three-dimensional repositioning of the maxilla is needed after Le Fort I osteotomy. The preoperatively planned and desired position of the maxilla could often not be implemented satisfactorily in the surgical procedure. Several authors described deviations of up to 15 mm in the vertical dimension and 5 mm in the sagittal dimension between the planned and the achieved position. In order to avoid this error, the "model-repositioning instrument" for three-dimensionally controlled cast surgery and the "three-dimensional doublesplint method" in combination with a surgical facebow for actual surgery were developed. A group of 20 adult patients with severe dentofacial deformities were treated according to the Goettingen concept for combined orthodontic-surgical treatment with condylar position control with a surgical facebow. For each patient the position of three marked reference points on the maxillary dental arch under pre- and postoperative conditions was evaluated using superimposed tracings of lateral radiographs. These values were compared with the performed movements of the dental maxillary arch during cast surgery. It can be shown that with the new developments the planned position of the maxillary dental arch could be transferred from cast surgery to actual surgery with an accuracy of +/- 1 mm vertically and sagittally.

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.

Techniques for achieving three-dimensional positioning of the maxilla applied in conjunction with the Göttingen concept.

Three-dimensional repositioning of the maxilla is possible after Le Fort I osteotomy. However, the preoperatively planned and desired position of the maxillary dental arch often cannot be sufficiently achieved during actual surgery, and deviations in the sagittal and vertical dimensions are common. To reduce these errors, the model-repositioning instrument was developed for model surgery in conjunction with the Göttingen concept for orthodontic-surgical treatment with condylar position control. This instrument allows a controlled three-dimensional positioning of jaw segments with three reference points directly on the teeth. The three-dimensional double-splint method combined with a surgical facebow was developed for a controlled three-dimensional positioning of the maxilla during surgery. This instrument and method were applied during treatment of 20 adult patients, and the position of the maxilla before and after surgery was analyzed. It was found that the planned position of the maxillary dental arch could be transferred from model surgery to actual surgery with an accuracy of +/- 1 mm sagittally and vertically. Thus, the application of the Göttingen concept for three-dimensional positioning of the maxilla results in an improvement of accuracy compared with other methods. Furthermore, use of these procedures is easier and less time-consuming during model and actual surgery than are other procedures.

Scanning electron microscopic study of primary fracture healing.

Scanning electron microscopy was used to study primary bone healing. This technique, essential for a three-dimensional description, has provided excellent visualization and revealed new aspects of the micromorphology of primary bone healing. Calcifying collagen bundles were responsible for the first mechanical stability, bone healing took place later in fracture vaults generated by compressed fracture fragments which were partially nonvital. A direct bridging of the fracture fragments by sprouting osteons was not observed.

[Significance of periosteum in profile and contour improving osteotomies of the growing skull. Animal experiment studies with the juvenile minipig]. / Bedeutung des Periosts bei profil- und konturverbessernden Osteotomien am wachsenden Schädel. Tierexperimentelle Untersuchungen am juvenilen Minipig.

Passive intracranial translocation of plates and screws (PIT effect), which has been described in the literature, is one of the undesirable outcomes in infant craniofacial surgery. Therefore, we investigated the hypothesis of whether epiperiosteal placement of plates and screws causes the periosteum to act as a "limiting membrane", possibly preventing or delaying passive intracranial translocation of hardware. In two different experimental models of the fast-growing skull of juvenile minipigs (16 or 7 weeks old) on one side of the skull a typical, standard galeaperiosteal flap was raised. On the contralateral side, the periosteum was left attached to the bone and after performing the osteotomies, plates and screws were placed on top of the periosteum. This technique showed that the periosteum acts as a "limiting membrane" and prevents early covering of the hardware by appositional bone growth. Thus, plates and screws could easily be identified if removal was intended. In contrast to this, on the subperiosteal side (conventional technique of raising a galeaperiosteal flap), plates and screws were already completely covered by appositional bone formation 8 weeks postoperatively. The posterior bone gaps that resulted from fronto-orbital advancements showed significant delay in reossification when the epiperiosteal technique was used. This may be advantageous for the growth of the skull following fronto-orbital advancements. In contrast, the posterior bone gap showed early reossification when the standard subperiosteal technique was used. Thus, in infant craniofacial surgery, the epiperiosteal technique and placing the plates and screws on top of periosteum seem to have some advantages compared to the standard subperiosteal technique.

Hemifacial microsomia: extraoral appliance for the early treatment of an infant. Literature review and case report.

In this report a description of the different features of hemifacial microsomia is given and a new way of early treatment of concomitant respiratory problems is presented. An extraoral appliance was developed for the treatment of an infant affected with this syndrome. The purpose was to temporarily minimize the child's repeated respiratory disturbances, which were probably caused by glossoptosis, until an autologous costochondral graft in the mandibular ramus could be performed. An improvement of respiration, of facial asymmetry and even a stimulation of mandibular growth was observed. It is claimed that the use of this appliance can help to avoid tracheotomy in many severe cases of uni- or bilateral facial microsomia with glossoptosis and apnea. This treatment should be considered as temporary until the general condition of the patient has improved and grafting is possible.

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.

The functional palatorrhaphy in the treatment of obstructive sleep apnoea.

We have developed a new operation for the surgical treatment of obstructive sleep apnoea, which we called functional palatorrhaphy. This preserves the posterior border of the soft palate and allows a controlled repair of the aponeurosis of the soft palate muscle. We combine the palatorrhaphy with a standard or a modified chin osteotomy with advancement of the base of tongue. In our first five treated and re-evaluated patients with severe obstructive sleep apnoea syndrome, who did not respond to conservative treatment, the operation was successful. All patients but one were considerably improved or cured of their symptoms.

A stable positioning for patients requiring large calvarial exposure for surgical correction of cranial synostosis.

We present a simple and elegant method of positioning the child's head for repair of craniosynostosis. The Sugita head holder allows large exposure of the calvarium with little risk of injury, dislocation or extensive blood loss caused by venous compression. We operated upon 37 patients (age range, between 3 and 132 months, median age 7 months) and did not observe any complication or lesion caused by positioning.

[Results of compression osteosynthesis with intraoral approach in 922 mandibular fractures]. / Ergebnisse der Kompressionsosteosynthese mit intraoralem Zugang bei 922 Unterkieferfrakturen.

A series of 922 fractures of the mandibular body (median-paramedian, horizontal ramus and mandibular angle) was treated within a 10 years period from January 1984 to December 1993 by an uniform treatment method. It consisted of compression plating with bicortical screw anchorage and intraoral approach, thus avoiding any outer scar and facial nerve damage. Postoperatively intermaxillary fixation was not used in any of these cases. A solid bony union was achieved in more than 99% of the cases. Major complications as osteomyelitis and non union were observed in 8 cases (0.86%). Minor complications of soft tissue infections without interference of fracture healing as haematomas, soft tissue abscesses and suture dehiscence were observed in 6.1%. A separate analysis of 352 mandibular angle fractures, which are regarded as particularly problematic, showed a frequency of severe complications (osteomyelitis and nonunion) of 0.85%. This is comparable with the frequency of complications of 0.86% within the total series. In this largest series of compression plating via intraoral approach, which has ever been published, the technique again has proved its significance as a standard procedure for the treatment of mandibular fractures.

[Fractures of the atrophic mandible--a challenge for therapy]. / Frakturen des atrophischen Unterkiefers--eine Herausforderung für die Therapie.

Because treatment of fractures of the atrophic mandible still today presents significant difficulties and treatment modalities remain controversial, 87 of these consecutive fractures which were treated by an uniform method as compression osteosynthesis were evaluated. A new classification of the degree of atrophy which considers the special interest of fracture treatment is introduced. It is based on a metrical measurement of the height of the mandible in the fracture area. Mandibles of 16 to 20 mm height are classified as class I atrophy, those of 11 to 15 mm as class II atrophy, and those with a height of 10 mm or less as extremely atrophic mandibles or class III atrophy. This simple and reliable classification could also be used in future investigations on the results of different treatment modalities in atrophic mandibles. In our series of 87 fractures of the atrophic mandible which were treated by compression osteosynthesis 97% resulted in a solid osseous union without the need of a second surgical intervention. Three major complications occurred: 1 osteomyelitis and 2 non-unions (the latter in one patient with a double fracture of a class III atrophy mandible). To the best of our knowledge this series is the largest of fractures of truly atrophic mandibles treated by one uniform method. Compared to other treatment modalities compression osteosynthesis produced acceptable results and is recommended as the treatment of choice in fractures of the atrophic mandible.

[The motivation and experiences of patients in connection with orthodontic-oral surgery combined therapy. A patient survey with consideration of the clinical and psychosocial factors]. / Motivation und Erfahrungen von Patienten im Zusammenhang mit einer kieferorthopädisch-kieferchirurgischen Kombinationstherapie. Patientenbefragung unter Berücksichtigung klinischer und psychosozialer Faktoren.

In a retrospective study 140 patients, 97 females and 43 males who had undergone combined orthodontic surgical therapy between 1984 and 1992, were interviewed using a questionnaire. The "closed form" questions were designed to provide insight into the patients' motivations for seeking treatment and into their perceptions of its course and outcome. Nine working hypotheses taken from the literature served as the study's starting point. The evaluation of the data gathered revealed that, contrary to other studies, the motivation for patients to seek treatment was not directly related to sex, i.e., was not sex specific, although this must be qualified. The unequal distribution of the sex of the patients who had sought treatment, and who were covered in the survey, points to differences between them in their decision making processes. When the results were evaluated, the data showed 92.2% patient satisfaction and even high satisfaction with treatment outcome. 86.4% of the patients stated that they would recommend the operation to others and 82.9% said that they would undergo the operation again. This high level of patient satisfaction was to a great degree directly attributable to, above all, the positive aesthetic result, the quality of the consultation and care, and to the absence of persisting postoperative complications. When the patients were divided into subgroups by means of using single criteria, significant varying degrees of satisfaction could be distinguished among segments of the subgroups. It was not possible, however, through the use of cluster analysis to separate out with precision the small group of patients who were not satisfied with the overall results of their treatment.

Passive and active intracranial translocation of osteosynthesis plates in adolescent minipigs.

On the basis of the clinical and experimental proof that intracranial translocation of osteosynthesis plates occurs in infants after fixation on frontal bone, we conducted an animal study on four adolescent Göttingen minipigs. Our aim was to study the effects on intracranial translocation of two different types of osteosynthesis plates by comparing the plate-bone interface on the intact frontal bone treated with a multiple-point contact plate versus a conventional smooth one, paying special emphasis to the periosteum. Within a few weeks of implantation, osseous regeneration products surrounded the plate. Total invagination of plates with initial intracranial translocation occurred 12 to 16 weeks postimplantation, regardless of plate design. In epiperiosteal fixation, intracranial translocation was delayed. The results revealed two mechanisms at play here: cranial growth-related passive intracranial translocation, which occurs regardless of plate design, and plate-dependent active intracranial translocation. In conclusion, we recommend that all metal osteosynthesis materials implanted in the infant cranium be removed as early as possible (within 3 months).

[The differential diagnostic value of skeletal, dental and soft-tissue analyses in the planning of orthodontic-oral surgical therapy. A retrospective study of treated patients with skeletal Angle class III]. / Zur differentialdiagnostischen Wertigkeit von skelettalen, dentalen und Weichteilanalysen bei der Planung der kieferorthopädisch-kieferchirurgischen Therapie. Eine retrospektive Studie von behandelten Patienten mit einer skelettalen Angle-Klasse III.

The study evaluated the orthodontic documentation gathered in the course of conducting combined surgical-orthodontic therapy on 45 skeletal angle class III patients. In 15 of the patients Le Fort I osteotomy of the maxilla was performed, in 15 sagittal split osteotomy of the mandible, and in the last 15 patients bimaxillary surgery. The purpose of the study was to evaluate by means of a retrospective analysis of cephalograms taken prior to surgery the role hard tissue, soft tissue, and dental cephalometric variables play in the choice of the type of surgery to be performed. Discriminate analysis was used to determine the ability of the individual parameters to predicate accurately the type of the surgery that had been carried out. The study revealed that the skeletal relationship diagnosed in the x-rays was suitable primarily in the differentiation of the monomaxillary and bimaxillary patients who had undergone surgery. Using discriminate analysis the accuracy to predict group membership was 75.6% for the skeletal parameters of the McNamara analysis and 67.5% for those of the Bergen analysis. Differentiation between the cases where surgery had been performed solely in the maxilla and those where surgery had been performed only in the mandible was most successful using the soft tissue parameters describing the position of the subnasale and the position of the lower lip in relation to the aesthetic line according to Ricketts. In addition, the arrangement of the lower incisors was more retrusive in the cases with isolated surgery in the maxilla. Discriminate analysis applying a combination of skeletal, dental, and soft tissue parameters had a capability to predict accurately in 93.3% of the patients the form of the chosen surgical procedure.

[Resorbable synthetics (PDS foils) for bridging extensive orbital wall defects in an animal experiment comparison]. / Resorbierbare Kunststoffe (PDS-Folien) zur Uberbrückung ausgedehnter Orbitawanddefekte im tierexperimentellen Vergleich.

In a long term animal study (min 2 weeks; max 48 weeks) on 6 minipigs, clinical related defects of the medial orbital wall extending in the orbital roof (2.5 cm x 3.5 cm) were created. The defects were bridged by slowly resorbable polydioxanon implants (so called PDS-foils, Ethicon) of different thickness (0.25/0.50 mm) and compared to control defects of identical size. The histological findings reveal: 1. After 29 weeks the resorption of both PDS-implants had been completely finished. Only the morphological intact implants had osteoconductive capabilities. 2. The osseous regeneration of the orbital defects started from the osteotomized margins of the orbital wall. The regenerates were covered by unaffected mucosa. 3. The bony regeneration was supported by the activated periosteal membrane. 4. The resorbed PDS-implants were being replaced by a tight scar tissue, which did not had any adjection to the orbital content. 5. The control defects showed a prolapse of the soft tissue with resulting enophthalmos. 6. According to the material specific characteristics, PDS-foils allow a sufficient bridging of even great and anatomically demanding orbital defects. 7. Notice: The hydrolytical broken down implant material may produce an irritation of the surrounding tissue causing a foreign body granuloma.