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Biomedical subjects

H Eufinger

Publications and source records attributed to H Eufinger.

At least 55 records · Page 3Linked to original sources
PubMed1998

Individual prefabricated titanium implants in reconstructive craniofacial surgery: clinical and technical aspects of the first 22 cases.

The reconstruction of craniofacial bone defects by intraoperative modeling of implants restricts the choice of material and its biocompatibility and also reduces the predictability of the aesthetic result. These shortcomings go hand in hand with a prolonged surgical procedure time and increased stress on the patient. In contrast, modern industrial computer-aided design and computer-aided manufacturing systems allow the prefabrication of titanium implants, i.e., individual computer-based three-dimensional models of the bone defect are generated after acquisition, transfer, and evaluation of helical computed tomographic data. Based on these data, the individual shape of the implant is designed using freeform-surfaces geometries and is fabricated by a numerically controlled milling machine in a direct fashion. The conical margins of this implant are designed with a precision of 0.25 mm to the borders of the defect, and the surface contours are generated harmonically to the nonaffected neighboring contours with a constant thickness of 1.5 mm. Individual constructions for fixation with the dimensions of microplates are integrated in this process if screw holes cannot be drilled in thin overlapping implant margins. The reconstruction of 22 posttraumatic, postoperative, or primary cranial and craniofacial defects measuring up to 18 cm was performed using this new method. Wound healing was uneventful in all but one case, although some of the patients had been operated on several times before. The result was always predictable and constant using this highly precise technique, and duration of surgery was reduced dramatically.

Adolescent↗
PubMed1997

[Clinical and experimental study of traumatic optic nerve damage].

BACKGROUND: Traumatic optic nerve lesions (TONL) range from temporary affection of vision to avulsion of the optic nerve; often they are associated with more complex injuries. Usually Tonl are not regarded as an emergency. Up to now, we lack knowledge on the dependency of strength and duration of optic nerve lesions and the point of no return for afferent disorders of the visual pathway. MATERIALS AND METHODS: We performed a prospective study on 50 patients with severe midface and skullbase fractures in order to find characteristic ophthalmological, computer tomographic und electrophysiological findings as indicators of TONL, independent of patient cooperation. We used an animal model (Wistar rats; n = 117) to study calibrated optic nerve lesions and the resulting neurodegeneration in the retinal ganglion cell (RGC) layer quantitatively. RESULTS: The electrophysiological investigation of the visual system (flash VEP/ERG) proved to be highly specific (0.97) and sensitive (1.0) for detecting TONL (n = 18). In the rat model, we could demonstrate a linear relationship between total neuron number reduction and strength and duration of calibrated optic nerve lesion. CONCLUSIONS: Experimental results indicate that optic nerve decompression is useful only within the first hours after TONL to reduce secondary optic nerve lesion. Indication for optic nerve decompression requires early detection of TONL, which is made possible by the combination of flash VEP/ERG.

Animals↗
PubMed1997

The role of alveolar ridge width in dental implantology.

Sometimes, preoperative planning in dental implantology, based on sufficient alveolar height, cannot be verified due to transversal deficiencies. A total of 102 bony mandibles and 95 maxillae were analysed after classification of atrophy, simulating implant insertion at 518 standardised edentulous cross sections with regard to anterior/posterior, mandible/maxilla and class of atrophy. Furthermore, the relation of alveolar height to possible implant length in 86 patients was evaluated retrospectively. Implant length reduction compared with alveolar height was necessary in 10% (mandibles) and 7.5% (maxillae) of the bony-jaw sections and 52.5% (mandibles) and 41.5% (maxillae) of the patients' implant regions. In this respect, the class of atrophy of the bony jaws was more important than the region of simulation. However, the highest differences were observed between mandibles and maxillae, both clinically and experimentally: simulation was possible in all mandibles and 42.5% of the maxillae, but clinical implantation was only possible in 86% of 62 mandibles and 0% of 24 maxillae, mostly due to reduced alveolar height. Alveolar ridge width primarily affected the possible implant lengths. Nevertheless, in four (two mandibular and two maxillary cases) of 58 patients (7%) with sufficient height, a surgical procedure that had already been started had to be stopped. It is expected that cross-sectional radiographical techniques of implantation planning, including ridge-width determination, will gain importance in the future.

Alveolar Bone Loss↗
PubMed1997

Individual prostheses and resection templates for mandibular resection and reconstruction.

This new technique uses helical computed tomography data and computer-aided design and manufacturing for preoperative fabrication of individual mandibular prostheses together with corresponding resection templates. Coherent 3D geometries for computer-based models are the basis for the construction of prostheses and provide data for a computerized numerical control fabrication. Fixation plates are fabricated with the titanium prostheses. The identical data of these plates are used for the computer-aided design and manufacturing of resection templates, which guide an oscillating saw in a precisely determined resection plane. This plane again is identical with the prostheses' margins for mandibular body replacement. The use of this technique in four patients is reported on: after temporary insertion of the templates for resection and after resection, the prostheses were stabilized with the same screws in the same screw-holes where the templates had been. Resection and reconstruction were thus highly precise, safe and fast and primarily led to excellent aesthetic and functional results. Wound-healing depends on a safe soft-tissue reconstruction over these large prostheses. Coverage with flaps seems obligatory. In spite of the superior technical aspects, the clinical long-term results of this new technique were poor.

Adult↗
PubMed1997

Descriptive and metric classification of jaw atrophy. An evaluation of 104 mandibles and 96 maxillae of dried skulls.

A study was carried out on 104 mandibles and 96 maxillae from anthropologic collections to challenge or support the studies of Cawood & Howell (1988, 1991). The data provided reveal considerable individual variations that cast some doubt on the practical use of the classification. It is suggested that the use of individual three-dimensional models will largely replace current modes of depicting resorbed jaws.

Alveolar Bone Loss↗
PubMed1997

[Reconstruction in craniofacial contour and continuity defects with preoperatively designed individual implants].

Reconstruction of craniofacial bone defects with intraoperatively modeled prostheses restricts the choice of material and its biocompatibility and the prediction of the aesthetic result. This goes hand in hand with prolonged duration of the surgical procedure and increased stress for the patient. In contrast, modern industrial CAD/CAM systems allow prefabrication of titanium prostheses. Individual computer-based 3D models of the bony defect are generated after acquisition, transfer and evaluation of helical CT data. Based on these data, the individual shape of the prosthesis is designed using free-form surface geometry and fabricated by a numerically controlled milling machine. The conical margins of this prosthesis are designed with a precision of 0.25 mm to the borders of the defect, and the surface contours are generated harmonically to the non-affected neighboring contours with a constant thickness of 1.5 mm. Individual constructions for fixation with the dimensions of microplates are integrated in this process if screw-holes cannot be drilled in thin overlapping margins of the prosthesis. Reconstruction of 18 posttraumatic or postoperative cranial defects measuring up to 18 cm was performed using this new method. Wound-healing was uneventful in all cases, although some of the patients had been operated on several times before. The results were always predictable and constant using this highly precise technique, and duration of surgery was reduced dramatically.

Biocompatible Materials↗
PubMed1997

[CAD/CAM (computer-aided design/computer-aided manufacturing) titanium implants for cranial and craniofacial defect reconstruction].

The reconstruction of craniofacial bone defects with intraoperatively modeled prosthesis restricts the choice of material and its biocompatibility and the prediction of the esthetic result. A prolonged duration of the surgical procedure and an increased stress on the patient are consequences. In contrast, modern industrial CAD/CAM-systems allow the prefabrication of titanium prosthesis: An individual computer-based 3D model of the bony defect is generated after acquisition, transfer and evaluation of helical CT data. Basing on these data the individual prosthesis-shape is designed using freeform surfaces geometries and fabricated by a numerically controlled milling machine. The conical margins of this prosthesis-geometry are generated by the borders of the defect with a minimal gap of 0.25 mm, and the surface contours by considering the non-affected neighbouring contours with a constant thickness of 1.5 mm. Individual osteosynthesis-microplates for fixation are integrated in design and manufacturing if screw-holes cannot be integrated in the thin margins of the implants. The radiological and clinical results of 17 patients after reconstruction of craniofacial bone defects with CAD/CAM titanium implants were good. Complications were not observed.

Adolescent↗
PubMed1995

CAD by processing of computed tomography data and CAM of individually designed prostheses.

In the past an economic fabrication of individual prostheses used in reconstructive cranio-maxillo-facial surgery was not possible due to technical deficiencies. Now, through the consistent use of the most modern computer-based techniques developed in the field of industrial engineering, these costs can be reduced to an economic level. Mathematical freeform surfaces models are first created from helical computed tomography data. These serve as the basis for an efficient and idealized construction of prostheses geometries, and provide control-data for a computerized numerical control-fabrication. In 4 clinical cases this new processing technique has successfully been utilized in the fabrication of individually designed prostheses for the reconstruction of skull defects. The range of opportunities offered is reflected not only in the great variety of possible geometric details, but also in the fact that the prostheses may be manufactured--partly using indirect impression-taking techniques--from 3 different biocompatible materials so far and other applications are likely to turn up.

Computer Simulation↗
PubMed1995

Prefabricated prostheses for the reconstruction of skull defects.

Cranioplasties using intraoperatively modeled prostheses may fail to create harmonic contours with long-term stability. In contrast, preoperative modeling would allow more sophisticated planning of the contour and better preparation of the implant material, if a sufficiently precise model of the defect-site was available. In this respect, computer aided design and manufacturing (CAD/CAM)-techniques based on helical computed tomography (CT) data are successfully used for the prefabrication of prostheses: An individual computer-based 3-dimensional model of the bony defect is generated after acquisition, transfer and evaluation of the CT data; from this freeform surfaces geometry an individual and "idealized" prosthesis-geometry is derived and fabricated by a numerically controlled milling machine using modern industrial CAD/CAM-systems and design software. The margins of this prosthesis-geometry are generated by the borders of the defect and the surface by considering the non-affected neighbouring contours. Cranioplasties in cases of large postsurgical skull defects are presented as the first clinical applications of this new method, which also allows the use of titanium and fabrication of integrated fixation-devices.

Computer Simulation↗
PubMed1995

Reconstruction of craniofacial bone defects with individual alloplastic implants based on CAD/CAM-manipulated CT-data.

Reconstruction of craniofacial bone defects by intraoperative modelling of autogenous or alloplastic materials may cause undesirable results concerning the implant shape or the long-term maintenance of this shape. Furthermore, the use of alloplastic materials to be modelled intraoperatively may result in an inflammatory tissue response. Therefore the question is raised whether CAD/CAM-techniques may be used for the pre-operative geometric modelling of the implant based on helical computed tomography data. A numerically based 3-dimensional model of the skull defect serves as the basis for a freeform-surfaces design of the implant shape, position and thickness, using modelling tools and programmes developed for industrial CAD/CAM. The precise and individual fit of the implant results from generating its margins by the borders of the defect, whereas the implant surface is generated by the geometry of the non-affected neighbouring bone contours. The implant data run a numerically controlled milling machine to fabricate the individual implant. The reconstruction of post-traumatic defects of the forehead, of post-surgical temporal defects after intracranial haemorrhage, and of a parieto-occipital defect due to ablative tumour surgery are presented as the first clinical experiences of this new method.

Adolescent↗
PubMed1995

Use of single- and multi-locus and polymerase chain reaction systems for zygosity determination--clinical application in twins with clefts of the lip and palate.

Precision of zygosity determination in twins can be improved by the use of modern methods of DNA analysis. The clinical application of 4 single- (SLS) and 2 multi-locus (MLS), and 6 PCR (polymerase chain reaction) systems for zygosity determination in 12 twin pairs with oral clefts was compared with regard to the quality and quantity of sample material required and the probability of error in monozygosity determination. PCR systems proved to be superior to SLS or MLS, as DNA sampling is much more convenient, while its level of accuracy still fulfils clinical requirements. For this reason, PCR systems should be considered a basic method in modern clinical twin research.

Cleft Lip↗
PubMed1995

Speech results and velopharyngeal morphology following 151 cranially based velopharyngoplasties.

151 velopharyngoplasties (VPP) are evaluated for velopharyngeal insufficiency (VPI) and quality of spontaneous speech, conspicuous scarring or asymmetry of the pharyngeal flap and upper airway obstruction. VPP improves speech effectively in all patient groups, although poorer results are found in patients older than 6 years or with primary VPI. Postoperative morphology does not seem to affect these results, and upper airway obstruction is related to hypertrophic tonsillar tissue.

Adolescent↗
PubMed1995

[The "incompletely operated" surgical patient as an emergency in the oral surgery clinic].

The evaluation of a large series of cases with uncompleted surgical treatment should lead to recommendations concerning the correct management of these patients. From 1983 to 1992, cases with uncompleted surgical treatment (n = 741) represented 1.6% of all patients treated. 715 cases were related to the removal of teeth: in 431 patients the completion of treatment was sufficient; in 284 cases complications had to be treated. In the majority of cases, documentation and patient management by the primary therapist were incomplete and needed improvement. With respect to this, recommendations are made on the basis of evaluation of the data.

Dental Records↗
PubMed1994

Should velopharyngoplasty and tonsillectomy in the cleft palate child be performed simultaneously?

PURPOSE: This study was undertaken to answer the question of whether the simultaneous performance of velopharyngoplasty and tonsillectomy in the cleft palate child has an influence on the speech outcome or on the rate of operation-related complications. PATIENTS AND METHODS: A series of 35 patients with simultaneous tonsillectomy and velopharyngoplasty was compared with 20 patients with these operations performed at different times. The evaluation of speech characteristics comprised defects of articulation (rhinolalia), voice quality (rhinophonia), the presence of nasal snorting, and the quality of spontaneous speech in four grades before operation and at final examination. RESULTS: The comparison showed greater improvement of the speech parameters associated with velopharyngeal closure for the patients operated on simultaneously. No difference concerning the quality of spontaneous speech was seen. The rate of intraoperative and postoperative complications and morphologic disturbances did not differ between the groups. CONCLUSIONS: The cleft palate child with velopharyngeal incompetence and enlarged tonsils seems to benefit from a simultaneous velopharyngoplasty and tonsillectomy.

Adolescent↗
PubMed1994

Individual augmentation of the atrophic mandible based on CAD/CAM-manipulated computed tomography data--in vitro results.

The problems of shaping a stable alveolar ridge form favorable for prosthodontic treatment by the various methods of ridge augmentation raise the question of whether computer-aided design (CAD) may be used for geometric modeling of the implant. Helical computed tomography (CT) data were used to create a three-dimensional (3-D) model of the atrophic mandible. This numerically based model served as the basis for a free-form-surface design of the implant's form, height, and position. The idealized data required for this geometric modeling were also derived from numerically based serial sections of 104 mandibles of dried skulls. The modeling procedure followed the formula "idealized mandibular geometry minus patient's geometry", yielding the geometric data of the implant. These numerically control (NC) a milling machine to fabricate the individual implant. The augmentation of an atrophic mandible of a dried skull is presented as the first in vitro trial of this new method.

Alveolar Bone Loss↗
PubMed1994

Velopharyngoplasty with or without tonsillectomy and/or adenotomy--a retrospective evaluation of speech characteristics in 143 patients.

Velopharyngoplasty is a well-established means of speech rehabilitation in patients with primary or secondary velopharyngeal incompetence. Principally, the result of velopharyngoplasty may be influenced by tonsillectomy or adenotomy or tonsillectomy and adenotomy because of the anatomical and physiological relations. The data of speech characteristics from 143 patients were evaluated retrospectively to determine the influence of tonsillectomy, adenotomy and both operations--performed simultaneously or at different times--on the result of velopharyngoplasty. Special regard was also given to the age at operation. The best speech rehabilitation by velopharyngoplasty was found in patients operated on before school-age, a noticeable negative influence of tonsillectomy, adenotomy or both could not be demonstrated. Therefore these operations should be considered and performed before school-age in order to achieve the best social and psychological rehabilitation.

Adenoidectomy↗