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Biomedical subjects

J Prein

Publications and source records attributed to J Prein.

At least 19 recordsLinked to original sources
PubMed2001

[Fractures of the edentulous atrophic mandible. Fracture management and complications].

BACKGROUND: With increasing atrophy, fractures of the edentulous mandible tend to have a higher incidence of nonunion. However, the connection between disturbances of bony consolidation and inadequate primary stability is often insufficiently discussed. FIXATION: Rigid internal fixation with 2.7 or now 2.4 AO compression and reconstruction plates is a safe procedure to achieve short-term rehabilitation in the mostly elderly patients by ensuring immediate function without intermaxillary fixation. With increasing atrophy, our concept suggests the use of stronger plates and fixation of screws in safe bony regions far from the fracture site. RESULTS AND DISCUSSION: This study reports the results of treatment of 40 fractures of the edentulous mandible in 25 patients from 1979 until 1996: 38 fractures (95%) showed primary healing, and only 1 nonunion was revealed after fracture of the plate. The criteria for choice of plates are discussed as well as fracture exposure and the question of primary and secondary bone grafting.

Adult↗
PubMed2000

[Bone tumors and tumor-like lesions of the jaw. Findings from the Basel DOSAK reference registry].

Within this chapter, tumors which produce bone matrix (osteoid) or other bone-forming tissues, like cartilage, connective tissue, and cementum or originate within the bone marrow are described. In addition, those lesions are mentioned which, according to the WHO, are typical for the jawbones and are therefore included within the 1992 WHO classification of odontogenic tumors. Vascular and epithelial tumors which may also be observed in the jaws are not described. All the lesions and tumors reported have in common a more or less similar clinical and radiological appearance. A precise diagnosis, therefore, can only be established by a sufficient biopsy which should be seen by a pathologist with experience in this field. In addition to clinical, radiological, and histological appearances, therapeutic necessities are described. The data from recent publications are taken into account. This presentation is based on the data collected within the reference registry of the German-Austrian-Swiss Study Group of Tumors of the Face and Jaws (DOSAK) in Basel.

Bone Neoplasms↗
PubMed2000

[New possibilities for reconstructing extensive jaw defects with prefabricated microvascular fibula transplants and ITI implants].

The reconstruction of extensive jaw defects is frequently only possible with microvascular bone flaps. Here we are presenting an operative technique using prefabricated fibular flaps and osseointegrated implants. In a first operation, the fibula is prepared with implants, split skin graft, and a nonresorbable membrane. The jaw defect is reconstructed 6 weeks later and can be treated directly with a prosthesis thanks to osseointegrated implants. The technique is described with reference to 5 patients already operated according to this technique and the initial findings are evaluated.

Adult↗
PubMed2000

Manipulation of callus after linear distraction: a "lifeboat" or an alternative to multivectorial distraction osteogenesis of the mandible?

Despite impressive results, distraction osteogenesis of the mandible is still compromised by difficulties with vector control. Because of the action of the masticatory muscles, the gonion angle has the tendency to open, resulting in an open bite. We report two patients, aged 10 and 12 years, who developed a severe open bite during mandibular distraction. As a salvage procedure, manual shaping of the soft regenerate was done immediately after distraction. Uneventful bony consolidation was observed, which resulted in anatomically shaped gonion angles. The fact that a regenerate created by distraction osteogenesis can be molded to virtually any shape offers interesting perspectives for the correction of complex mandibular deformities.

Bony Callus↗
PubMed1999

Repair of complex orbital fractures: technical problems, state-of-the-art solutions and future perspectives.

Within the wide range of severity of orbital fractures, the small group of complex fractures causes most of the sequelae. Therefore identification of severe injuries and adequate treatment is of major importance. The introduction of craniofacial techniques made possible a wide exposure of even large orbital wall defects and their reconstruction by grafts. In spite of significant progresses, repair of complex orbital wall defects remains a difficult surgical problem even for the experienced. This paper outlines the specific technical problems concerning surgical anatomy, exposure and defect reconstruction of this type of injuries. A number of new developments providing interesting future perspectives for orbital wall reconstruction such as intraoperative navigation, endoscopic techniques and new materials are discussed.

Animals↗
PubMed1998

[Experimental reconstruction of the sheep orbit with biodegradable implants].

In a complex animal model in sheep, polydioxanone (PDS) and polylactic membranes were used for the reconstruction of large orbital-wall defects. In a long-term experiment over 1 year, polylactic implants alone showed the best performance as compared with combinations involving autogenous bone grafts and titanium miniplate fixation. As soon as these polylactic implants are approved for human surgery, they will be used to solve the still challenging problem of anatomical reconstruction of large comminuted fractures of more than one orbital wall.

Animals↗
PubMed1997

Osteosynthesis of condylar neck fractures: a review of 30 patients.

This article reviews 31 condylar neck fractures in 30 patients stabilized with different types of plates with emphasis on complications associated with different types of plates. Indications for stabilization were predominantly bilateral fractures, shortening of the ascending ramus due to lack of occlusal buttressing and condylar neck fractures associated with panfacial fractures. Stabilization was achieved with a single (23 fractures) or a double adaptation miniplate (4 fractures), a 2.4 mm plate (2 fractures) or a TMJ prosthesis (2 fractures). Eight fractures exhibited complications requiring reoperation (4 plate fractures, 3 cases of screw loosening associated with infection, 1 malposition). Complications occurred exclusively in the fractures stabilized with a single adaptation miniplate. Recommendations for stabilization, therefore, include a double miniplate, a 2.4 plate, a minidynamic compression plate (finger-plate) or a 2.0 mandibular-miniplate. Screws are preferably placed bicortically.

Adolescent↗
PubMed1996

[Gunshot injuries of the mandible].

43 patients with gunshot wounds of the mandible were treated in Tübingen and Basel between 1968 and 1995. Among them were 31 patients ( = 72.09%) with bone loss and defect fractures. Over that time period the treatment principles of gunshot wounds have not changed. They are based on an early soft tissue closure and an approach from the inside to the outside. Besides that modern techniques in maxillofacial reconstructive surgery, which include the application of biocompatible plates and screws and the introduction of microvascular reconstructive techniques, have enlarged the therapeutical options. Every patient needs an individual approach to his special medical condition, which is illustrated in three exemplary cases. The combination of the above mentioned modern reconstructive techniques prevents long and multiple hospital stays and invalidity. Furthermore it is the basis for social reintegration as well as functional and esthetic rehabilitation.

Adolescent↗
PubMed1996

[Therapy of infected mandibular fractures].

In a follow-up study the results after rigid internal fixation (RIF) in 23 patients with mandible fractures showing signs of bone infection at the fracture sites are presented. Depending on the bony defect RIF was performed with or without additional autogenous bone grafts. RIF led to a calculable and uneventful bone healing despite the infections. The plates must be fixed with at least 3 screws on each fracture site and outside the infected areas. An adequate soft tissue coverage is a prerequisite for primary or secondary bone transplantation. In our series infected fractures were usually observed in problem patients as alcoholics, drug addicts or uncooperative patients as mentally disabled or aged persons. These patients also frequently escape from the follow-up program. To prevent complications an osteosynthesis in problem patients should be performed with enough stability so no compliance is required.

Adolescent↗
PubMed1996

[Development of a resorbable implant: experimental reconstruction of the orbits with polylactate membranes. Animal model and preliminary results].

In a complex animal model in five sheep, PDS or polylactic biodegradable membranes were used for reconstruction of large orbital defects in combination with autogenous bone grafts and stable internal fixation with titanium miniplates and screws. Because of anatomical similarities, animal model and human clinical findings are comparable. After eight weeks, in four sheep all reconstructions were separated from the maxillary and frontal sinus by a continuous mucosal layer. The bone grafts were integrated into the bony frame of the orbit. Foreign body reactions were milder with polylactic membranes compared to PDS, probably due to the slow degradation of polylactide. These preliminary results will lead to a further study with a larger series to compare the two biodegradable materials and to prepare the way for clinical use of polylactic membranes in orbital reconstruction.

Animals↗
PubMed1995

Stabilization of the short sagittal split osteotomy: in vitro testing of different plate and screw configurations.

Using a 3-dimensional in vitro model, the stability of different types of osteosynthesis for the short sagittal osteotomy was tested. The following four groups of plate and screw configurations were evaluated: Group I: Fixation with miniplates using monocortical screws only, Group II: Fixation with miniplates, but with two of the screws engaging both fragments, Group III: Same as group II with an additional position screw, Group IV: Fixation with 3 position screws. The stability obtained with miniplate fixation using monocortical screws only (group I) was by a factor of 2.9 less than position screw fixation (group IV), which is considered to be an approved standard. In order to increase the stability of miniplate fixation, the screws in the area of overlapping bone should engage both fragments.

Bone Plates↗
PubMed1995

Correction of post-traumatic orbital deformities: operative techniques and review of 26 patients.

The skeletal reconstruction of post-traumatic orbital deformities includes the zygomatic complex, the nasoethmoid area and the internal orbit. Repositioning of the malpositioned zygoma is the key element and the first step. Due to remodelling processes, most of the landmarks for proper positioning are lost, leaving the lateral orbital wall as the only reliable landmark in secondary revisions. The details of the skeletal reconstruction are discussed. Between January 1988 and December 1992, 31 patients with major post-traumatic orbital deformities have been operated on, of which 26 could be followed for a minimum of 6 months. A total of 61 operative procedures using craniofacial techniques have been performed. Complications occurred in 5 (15%) of the 26 patients, the most severe being visual loss caused by a displaced bone graft. The most frequent deformity was enophthalmos. Most patients presented with more than one deformity. The aesthetic results were rated as 'good' in 12, 'satisfactory' in 8 and 'unsatisfactory' in 6 patients. Of the patients suffering from double vision, 55% were improved after orbital reconstruction. Craniofacial techniques allow radical correction of post-traumatic skeletal deformities. The functional and aesthetic results, however, are limited by the soft tissues.

Adult↗
PubMed1993

[Reconstructive surgery in the area of the orbit].

Craniofacial techniques have dramatically improved the possibilities for reconstructive procedures in the orbital region. Indications occur in acute or delayed fracture repair as well as in tumor surgery and in the correction of congenital malformations.

Humans↗
PubMed1992

[Bone defect filling material in jaw bones using tricalcium phosphate].

Our experience shows that resorbable Beta-Tricalcium-phosphate is a useful alternative as filling material for cystic defects of the maxilla and mandible. It proves to be biocompatible and causes no immunologic reactions. Granulate has been used in 51 patients, in most cases it was Tricalciumphosphate. In three patients it had to be removed. Radiologically as well as histologically it was shown that resorption of Tricalciumphosphate takes place and that is replaced by osseous integration.

Calcium Phosphates↗
PubMed1992

[Differential diagnosis of epulis-type changes in the mouth].

Various tumorlike reactions of the oral mucous membranes under the term Epulis are summarized. These histologically different benign or malignant neoplasms of the gingiva are not very frequent. The differential diagnosis on a clinical basis like symptoms and macroscopic appearance is not easy. Sometimes under these harmless appearing lesions highly aggressive and malignant tumors may be hidden; as there are carcinomas, sarcomas, metastases, tumors of the salivary glands or malignant lymphomas. The therapy of choice is the complete removal including the underlaying periosteum. Occasionally the adjacent bone and tooth have also to be resected. Because of the harmless clinical appearance a histological examination is always required. Some clinical and pathohistological impressive examples are presented.

Diagnosis, Differential↗
PubMed1991

[Structural and biomechanical based differences of osteosynthesis in mandibular or mid-face fractures. Why does the AO still use stiff plates?].

The mandible and the midface differ considerably in their anatomic structure, and therefore require different techniques for fracture stabilisation. Midface-fractures are stabilised by mini-plates, which are arranged in a three dimensional fashion. Fractures of the mandible require stronger plates because the osteosynthesis is done in only one plane.

Adult↗
PubMed1990

[Procedures and results with preoperative individual AO reconstruction plates].

As a rule continuous bony defects of the mandible after tumour resection are temporarily bridged with the AO reconstruction plate. To precontour the plate, CT-scans of the mandible at a scale of 1:1 6 mm above and parallel to the inferior margin are needed. Corresponding layers further cranial show the anatomy of the chin. Using a lateral cephalograph, the mandibular angle and the length of the plate in the ascending ramus are measured. Using the CT-scans, the lateral cephalograph, a prebent template and a corresponding model of the mandible, the plate is bent into shape. Of the nineteen preshaped reconstruction plates implanted, eleven did not need any intraoperative adjustment. The other eight plates needed only slight modifications of contour. Preoperative bending of the reconstruction plate reduces the time taken for the operation, protects the material and the plate is precisely shaped.

Bone Plates↗