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Biomedical subjects

J A Obwegeser

Publications and source records attributed to J A Obwegeser.

16 recordsLinked to original sources
PubMed2006

The galea fascia flap in orbital reconstruction: innovative harvest technique.

AIM: To report the treatment of a recurrent adenoid-cystic carcinoma of the lacrimal gland required orbital exenteration with an en bloc resection of the lateral orbital rim and wall and an anterior portion of the temporal muscle. Reconstruction was planned with both the objectives of a shortened healing time for faster epithetic reconstruction and no visible scars. METHOD: After a cranially extended temporal approach, the dissection of the superficial galea layer was connected with the subcutaneous dissection of the upper and lower eyelid after subciliary incisions. RESULTS: Ample exposure of the temporal, frontal and orbital region was obtained, facilitating the orbital exenteration with en bloc resection of the lateral orbital rim and wall and the anterior portion of the temporal muscle. The epithelialization of the eye socket covered with the galea fascia flap was accelerated, providing faster epithetic reconstruction, without visible scars. CONCLUSIONS: Healing time is accelerated, providing faster epithetic rehabilitation without visible scars, which is important in the postoperative rehabilitation ladder after eye exenteration for both patient and surgeon. Further more ablative surgery within this region gets safer and easier due to the ample exposure of this innovative surgical technique. Further evaluation of the effectiveness and safety of this new approach is advisable.

Carcinoma, Adenoid Cystic↗
PubMed2005

[Solitary abscessing osteomyelitis of the mandibular condyle. A rarity].

CASE REPORT: We report on a rare case of secondary chronic osteomyelitis of the left condyle. Haemophilus aphrophilus could be isolated from the abscess material. The condyle was resected and reconstructed with an endoprosthesis in the same operation. DISCUSSION: Possible causes of the rare location of secondary chronic osteomyelitis are assembled in a review of the literature and compared with the actual case. CONCLUSION: We suggest the inoculation of microorganisms through the needle of a local anesthetic injection, bacterial contamination during the tooth extraction, or bacteremia following the dental extraction to be possible causes for the infection.

Abscess↗
PubMed2004

Influence of different sterilization procedures and partial demineralization of screws made of bone on their mechanical properties.

Since 1992, screws made of allogenic, autoclaved human cortical bone have been employed as osteosynthesis materials. Autoclaving at 134 degrees C for 5 min makes them microbiologically safe, but on the other hand it reduces both their mechanical properties and osteoconductive capacity. The aim of this in vitro study was to determine if the mechanical properties of these screws could be improved after receiving different autoclaving procedures and partial inner demineralization, the latter additionally tending to increase their osteoconductive potential. 132 screws made of bovine cortical bone were employed. Some of them were partially demineralized with 0.6 N HCl from an inner canal performed following their longitudinal axis. All the specimens were autoclaved at 134 degrees C but under different vacuum conditions and sterilization time (A1-A2). They were then subjected to tension, shear and torque tests. A difference between both sterilization procedures was observed. Samples sterilized at 134 degrees C, 2-2.4 mbars for 5 min (A1) showed better mechanical properties than those autoclaved for longer time and higher vacuum conditions (A2). Demineralization also influenced their mechanical properties, being less resistant with increasing time. Based on these results, a standard screw made of bone and autoclaved at 134 degrees C, 2-2.4 mbars, 5 min seems to be the most appropriate, from a biomechanical point of view, to be used as osteosynthesis material.

Animals↗
PubMed2003

Effects of enzymatic treatments on the biomechanical properties of screws made of bone.

Nowadays, bone tissue employed to manufacture screws used as osteosynthesis material is obtained from organ donors. But in different medical fields there is an increasing need to use xenogenic grafts and implants, which still imply risks of transmission of some diseases and antigenicity. Two different autoclaving programs (A1, A2) and an alternative to reduce the antigenicity of screws made of xenogenic bone based on enzymatic treatment are analyzed from a biomechanical point of view. 128 screws made of bovine femur bone were employed. Some of them were partially demineralized with 0.6 N HCl, enzymatically digested with collagenase (specific) and pepsin (nonspecific) and then autoclaved. The specimens were subjected to tension, shear and screw torque tests and histologically evaluated. Compared to A1, A2 sterilization method (134 degrees C but higher vacuum and longer time) considerably reduced the mechanical strength of specimens. The enzymatic digestion, expected to reduce antigenicity, did not affect the screw superficial structure and would not modify the bone biomechanical properties per se, but maybe because of the association with autoclaving and partial demineralization.

Animals↗
PubMed2002

Volume variations of bone tissue after undergoing different physical and chemical treatments.

Both autogenic and allogenic bone has been employed through different surgical procedures to fill different defects or as osteosynthesis materials. Some physical and/or chemical treatments are usually necessary before its use. Since bone volume is important from a surgical point of view, the present study was designed to analyse its possible variations when subjected to certain procedures. Screws made of bovine cortical bone were autoclaved in different conditions regarding time and vacuum (A1-A2), cryopreserved, demineralised, enzymatically digested and rehydrated. The samples were measured before and after every treatment. Sterilisation caused a volume reduction more marked with method A1 than A2 whereas freezing allowed to obtain the original size. No volumetric changes were registered after demineralisation and enzymatic digestion. Rehydration significantly increased their volume already during the first hour but the maximum value was reached at 24 h. Thus, autoclaving was the only treatment able to reduce the bone volume whilst freezing and rehydration allowed the samples to return to their original size.

Animals↗
PubMed2001

[Indication and technique of orbital enlargement in the treatment of endocrine ophthalmopathy].

Typical symptoms in endocrine ophthalmopathy are a result of an interstitial swelling of the ocular muscles and of the volume increase of the postbulbar fat and connective tissue. Clinically, we find a spectrum that reaches from infiltration of the eyelid and conjunctival tissue, exophthalmos, swelling of the muscles with diplopia, damage to the cornea till to involvement of the optic nerve with loss of vision. Regarding functional impairment of the optic nerve, orbital decompression represents an operative ultimate ratio. The surgical principle is based on the decompression within one or usually several orbital walls occasionally in combination with a sagittal enlargement of the eye socket by osteotomy and advancement of the orbital rims. As rule of thumb is considered: The reduction of the exophthalmos is proportional to the number of decompressed walls and amounts to 2-3 mm per decompressed orbital wall. A reduction of exophthalmos going beyond that can be obtained by advancement of the orbital rims.

Conjunctiva↗
PubMed1998

[Absorbable and bioconvertible osteosynthesis materials in maxillofacial surgery].

In order to overcome the need for secondary intervention to remove metallic osteosynthesis devices after fracture healing, endeavours have been directed towards developing resorbable osteosynthesis materials during the last decade. The resorbable material must fulfil a number of basic demands. For example, an adequate holding strength of these materials is essential for undisturbed fracture union, complete resorption after bone healing, good histocompatibility without any damage to the surrounding tissues and without detrimental distant effects within the organism. Suggested materials are primarily high-polymerlactic acid or glycolic acid compounds. In particular, research was concentrated on the enhancement of the mechanical properties and biodegradation of polylactides. Debris high in crystallin was found to be responsible for late soft tissue reactions. To achieve disintegration products with lower crystallin content stereocopolymeres of lactic acids are preferred nowadays. Based on our experimental work, another osteosynthesis system manufactured from autoclaved allogenic bone tissue was developed as an alternative. This has osteoconductive properties and converts by creeping substitution into bone. In contrast to metallic plates and screws, the modulus of elasticity is quite similar to vital bone tissue. The initial strength enables its use in the field of maxillofacial surgery.

Absorbable Implants↗
PubMed1994

Bioconvertible screws made of allogenic cortical bone for osteosynthesis following sagittal split ramus osteotomy without postoperative immobilisation.

Since 1990, 12 patients have been operated on by sagittal split ramus osteotomy with subsequent osteosynthesis using screws made of allogenic cortical bone without any postoperative immobilisation. These cases have been followed-up and were clinically and cephalometrically analysed. In all patients no complications were recorded. Preliminary data suggests that the stability of the segments is in good accordance with procedures using metallic devices for osteotomy fixation. The advantage of the screws presented can be seen by the fact that the material used is bioconvertible and therefore no removal operation is needed. Thermal treatment of these screws prevents problems of infection.

Biocompatible Materials↗
PubMed1994

Osteosynthesis using biodegradable Poly-p-dioxanon (PDS II) in Le Fort I-osteotomy without postoperative intermaxillary fixation.

The purpose of the study was to evaluate the stability of Le Fort I advancement using biodegradable Poly-p-dioxanon (PDS II)-thread in the fixation of the osteotomy and to compare the results with that of metallic devices. Positional changes were registered by cephalometric examination with standardized radiography. 30 class III adult patients were chosen, whose treatment by surgical movement of the Le Fort I segment was similar in dimension and direction. They were subjected to a clinical and cephalometric analysis of postoperative stability. 4 lateral cephalometric X-rays were evaluated for each patient and compared in their two deviation levels. In order to assess the vertical and sagittal behaviour of the osteotomized segments, independent of intraoperatively altered structures, a system of coordinates was drawn up. Statistical examination of the existing data was carried out by computer. For calculation of significance the Wilcoxon-test, T-test, and Kruskal-Wallis-test were used. It could be demonstrated that PDS-thread as well as titanium-miniplates showed good stability in the anterioposterior plane, but a tendency to vertical relapse in both groups.

Adolescent↗
PubMed1989

[Can inferior alveolar nerve lesions be avoided during sagittal splitting? Anatomy, surgical technique and neurological aspects].

The overriding principle in surgery should always be "nihil nocere". This is particularly true for maxillofacial surgery and assumes critical importance in orthognathic operations in which the prevention of motor and sensory nerve lesions should have priority. Considering that orthodontic surgery is increasingly done in an ever growing number of situations, it is obvious that this issue has become central to the decision-making process in each and every case. This contribution is designed to review the basic anatomy, to outline a useful surgical management concept and present the results obtained with it.

Humans↗
PubMedDate not supplied

[A new concept for the reconstruction of the extremely atrophied mandible].

The introduction of interposition techniques for mandibular ridge augmentation brought about such great improvement in the results that we may speak, with reservations, of having achieved absolute ridge augmentation at least in the anterior mandibular area. The unsatisfactory results in the buccal area induced us to change the treatment concept and study the patients treated according to this new concept in a first post-treatment evaluation.

Alveolar Ridge Augmentation↗