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Biomedical subjects

J T Lambrecht

Publications and source records attributed to J T Lambrecht.

At least 19 recordsLinked to original sources
PubMed2001

Three-dimensional cephalometry using individual skeletal laser technology models.

When planning operations on the facial skull, transversal asymmetries of the maxillo-mandibular complex cannot be adequately assessed using conventional two-dimensional (2D) x-ray cephalometry. On eight patients who presented with facial skull asymmetries, a three-dimensional (3D) laser technology model (LTM) using CT data was fabricated. Five sagittal plane points and six symmetry points were marked on the LTM, measured with the FlashPoint 3-D Digitizer and then geometrically converted, such that using the sagittal plane points, sella, basion, and nasion, a method could be developed that allowed the localization of each spatial point in the three symmetry planes. Thus one could quantitatively record a patient's specific facial skull asymmetry in all three planes and a 3D measurement became feasible. Based on the measurements, the asymmetry could be assessed with respect to the sagittal, vertical, and horizontal planes. With the 3-D LTM Digitizer measuring system, the surgeon now had precise numerical information regarding the symmetry ratios of the skull at his disposal, information that would have been difficult to evaluate solely using a model analysis. The results from this study show that our measuring system is applicable and useful for complex maxillofacial asymmetries. The planning of surgical interventions was optimized because precise numerical values regarding the degree of the asymmetry were available. With the 3-D LTM Digitizer measuring system, cephalometric analysis of complex asymmetries in the three spatial planes can be pragmatically supported.

Cephalometry↗
PubMed2000

Position, shape, and dimension of the maxilla in unoperated cleft lip and palate patients: review of the literature.

The inhibition of growth and development resulting from surgical treatment of the cleft lip and palate is a widely discussed topic. Various studies have been conducted in search of answers as to how the untreated upper jaw develops, focusing on individuals with untreated cleft lip and palate as found in so-called Third World countries. This study offers the opportunity to compile literature dealing with the research and description of untreated unilateral cleft lip and palate. The focus was to take a closer look at groups of individuals with complete unilateral cleft lip and palate, who had received no surgical treatment at all, as well as groups who had received surgical treatment of only the cleft lip. The upper jaw of untreated cleft lip and palate patients most often adopts a protruded position without enlarging the maxilla itself. The horizontal dimension tends to be reduced, whereas the vertical dimension is normal. The upper jaw of patients with unilateral cleft lip and palate who received surgical treatment of the lip more often adopted a retruded position. The model analysis showed no clear-cut tendencies. There seemed to be a degree of regional variation. Considering the relatively small number of recruitable individuals with untreated cleft lip and palate, the introduction of a standard method of evaluation is desirable. This would significantly facilitate the comparison of different studies with each other in the future. The first steps in this direction have already been initiated.

Child↗
PubMed2000

[Dento-alveolar surgery].

The first publications in dentoalveolar surgery date back to the eighteenth century, while basic works in German-speaking areas appeared in the first half of the 20th century. Dentoalveolar surgical issues are still present within craniomaxillofacial surgery nowadays. Nomenclature has changed little while contents in certain areas shift away from surgical practical aspects towards biological-medical points of view. The new technologies of dentoalveolar surgery are being developed for maximal patient safety using minimal invasive methods. Other, traditionally non-surgical, dental subspecialities are taking over dentoalveolar surgical issues. Oral surgery remains a part of craniomaxillofacial surgery and should continue to get a major boost from it in the future.

Forecasting↗
PubMed2000

Accuracy of implant treatment planning utilizing template-guided reformatted computed tomography.

OBJECTIVES: To evaluate the magnitude of error in transferring the planned position of implants from reformatted CT scans to a surgical template. METHODS: The deviation between the position of the apex of the proposed implant in paraxial CT reformats and on the corresponding study cast was measured in 77 prospective sites in five maxillas and nine mandibles. RESULTS: The transfer error was 0.6 (s.d. 0.4) mm in the maxilla and 0.3 (s.d. 0.4) mm in the mandible. CONCLUSIONS: The transfer errors detected in this investigation are not clinically relevant. Other factors involved in transferring positional and angular measurements from reformatted CT to the surgical site may result in more significant errors.

Dental Implantation, Endosseous↗
PubMed1997

Hypothetical mortality risk associated with spiral tomography of the maxilla and mandible prior to endosseous implant treatment.

Radiation dose delivered from the SCANORA radiography unit during the cross-sectional mode for dentotangential projections was determined. With regard to oral implantology, patient situations of an edentulous maxilla and mandible as well as a single tooth gap in regions 16 and 46 were simulated. Radiation doses were measured between 0.2 and 22.5 mGy to organs and tissues in the head and neck region when the complete maxilla or mandible was examined. When examining a single tooth gap, only 8% to 40% of that radiation dose was generally observed. Based on these results, the mortality risk was estimated according to a calculation model recommended by the Committee on the Biological Effects of Ionizing Radiations. The mortality risk ranged from 31.4 x 10(-6) for 20-year-old men to 4.8 x 10(-6) for 65-year-old women when cross-sectional imaging of the complete maxilla was performed. The values decreased by 70% when a single tooth gap in the molar region of the maxilla was radiographed. The figures for the mortality risk for examinations of the complete mandible were similar to those for the complete maxilla, but the mortality risk decreased by 80% if only a single tooth gap in the molar region of the mandible was examined. Calculations according to the International Commission on Radiological Protection carried out for comparison did not reveal the decrease of the mortality risk with age and resulted in a higher risk value in comparison to the group of 35-year old individuals in calculations according to the Committee on the Biological Effects of Ionizing Radiations.

Adult↗
PubMed1997

Examine your orofacial cleft patients for Gorlin-Goltz syndrome.

The Gorlin-Goltz syndrome is characterized by four primary symptoms: multiple nevoid basal cell epitheliomas that usually undergo malignant transformation; jaw keratocysts that show constant growth; skeletal anomalies; and intracranial calcifications. A myriad of additional findings may also be noted. Among the most frequent are: palmar and plantar pits, a characteristic flattened facies and broad nasal root, frontal and parietal bossing, mandibular prognathia, hypertelorism, strabismus, dystrophia of the canthi, and clefts of the lip, alveolus, and/or palate. In this study, we review the literature and our 25 cases of Gorlin-Goltz syndrome patients, questioning their incidence of cleft formations (8.5%) as compared to the general population (0.1%). It is our contention that all patients who present with an orofacial cleft warrant deeper investigation as to the presence of additional signs indicative of Gorlin-Goltz syndrome. The nevi turn malignant with time, and thus, early diagnosis, follow-up, and treatment are imperative.

Adult↗
PubMed1996

Human osteoclast-like cells in primary culture.

We describe a method for the isolation and culture of osteoclast-like cells from cancellous bone chips of iliac crests from patients undergoing reconstructive maxillofacial surgery. Under aseptic conditions, bone chips were cut into small pieces, incubated briefly with collagenase, and the isolated bone cells were separated from the bone chips by filtration using a nylon mesh. Bone cells were then cultured on a variety of surfaces for up to 10 days. Cell motility and fusion, together with the development of tartrate-resistant acid phosphatase activity, were seen in many cells soon after culture. The large osteoclast-like cells adhered to human cortical bone slices and produced resorption pits. These morphological and functional characteristics suggest that the cells we isolated and cultured were human osteoclasts and their precursors. Thus this method may provide a reliable means of obtaining human osteoclasts from normal tissue for short-term studies of their metabolism or from various skeletal diseases to study pathological aberrations and mechanisms.

Acid Phosphatase↗
PubMed1995

Individual model fabrication in maxillofacial radiology.

Oral and maxillofacial surgery has long needed a methodology for accurate definition of the third dimension. The introduction of computer-aided tomography in the 1970s provided surgeons with multiple 2-D maps which they themselves had to conceptualize into a third dimension. The later advent of computerized summation of these data made it possible to display a perspective view of the third dimension on a TV monitor. CT, and more recently MRI, with the further analytical refinement afforded by software processing (interactive data presentation, contour detection and summation, hypothetical 3-D construction and interactive visualization) now provide the basic information that is needed for the fabrication of an individual model. Such models can be milled from a variety of materials. More recently, laser-hardened acrylic resins have been shown to be a useful alternative. Both systems are described and their advantages and disadvantages in the planning and performance of oral and maxillofacial surgical procedures are discussed.

Acrylic Resins↗
PubMed1995

Dental implant treatment planning with reformatted computed tomography.

By using specific software programmes, it is now possible to obtain reformatted CT images of the mandible and maxilla. This facility has proved to be valuable in the planning of fixed and removable suprastructures in implantology. We describe the use of a radiopaque prosthetic template to enable the optimal position and axial inclination of the fixtures in edentulous patients to be established.

Alveolar Process↗
PubMed1995

[Odontogenic diseases of the maxillary sinuses].

Odontogenic maxillary sinusitis is aetiologically different from rhinogenic maxillary sinusitis. Accordingly, there are distinct and--for the oral maxillofacial surgeon--very specific therapeutic consequences. The general clinical diagnostical principles have scarcely changed in the last years. In diagnostic imaging, computed tomography and magnetic resonance tomography are of great importance, especially concerning pre-operative diagnostics. Endoscopical techniques have been enhanced with the introduction of microcamera-supported endoscopy, a technical improvement. Therapeutical principles are: complete treatment of odontogenic factors in the whole quadrant; conservative and operative therapeutical procedures are to be combined. Other than in the ENT field, where the maxillary sinus is approached by an endo-nasal technique--infundibulotomy-in oral and maxillofacial surgery the transalveolar approach through the fossa canina is used when treating odontogenic maxillary sinusitis. However, cautious methods assuring the preservation of tissue in all respects are treatment of choice.

Diagnosis, Differential↗
PubMed1995

[The toxicity of root-canal filling materials in primary osteoclast cell cultures].

Endodontic root-filling material is brought into direct contact with apical tissues when finishing endodontic therapy. Endodontic two-component materials develop cytotoxic effects during the phase, as shown in different in-vitro studies. Insufficient specificity of these tests could be eliminated by using bone cell cultures. The toxicity of seven endodontic root-filling materials towards osteoclasts in primary cell culture were investigated. Osteoclasts initially reacted to freshly mixed endodontic materials by losing their physiological properties (surface adherence), longer exposition on the toxic agents led to cell lysis. To quantify these light-microscopical phenomena, the content of lactate dehydrogenase (LDH) in the adherent cells as well as in the medium of the cultures were determined photometrically. All the examined two-component materials induced a distinct loss of intracellular LDH activity with a proportional uprise in the media. Calibration showed a positive correlation of LDH content and cell number. The results could be interpreted as the survival rate of osteoclasts after incubation with endodontic filling materials. All tested materials--except for gutta-percha--showed a distinct toxicity towards osteoclasts in primary cell culture during the first 24 hours. Osteoclasts proved to be sensitive indicators for cell-adverse toxicity during the in-vitro tests of endodontic root-filling materials.

Animals↗