[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.

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.

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.

New trends in the 3D management of CT data in plastic and reconstructive surgery

Introduction of computer aided tomography in 1972 provided surgeons with multiple 2D maps which they themselves had to conceptualize mentally 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, with the further analytical refinement afforded by software processing (interactive data presentation, contour detection and summation, hypothetical 3D data construction and interactive visualization) now provides the basic information that is needed for the fabrication of an individual model. Such models can be milled from polyurethane. More recently, laser-hardened acrylic resins have proved to be a useful alternative. Both systems are described and their advantages and disadvantages in the planning and performance of plastic and reconstructive surgical procedures discussed in the light of present knowledge.

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.

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.

Hypothetical mortality risk associated with spiral computed tomography of the maxilla and mandible

In the present study, dose measurements have been conducted following examination of the maxilla and mandible with spiral computed tomography (CT). The measurements were carried out with 2 phantoms, a head and neck phantom and a full body phantom. The analysis of applied thermoluminescent dosimeters yielded radiation doses for organs and tissues in the head and neck region between 0.6 and 16.7 mGy when 40 axial slices and 120 kV/165 mAs were used as exposure parameters. The effective dose was calculated as 0.58 and 0.48 mSv in the maxilla and mandible, respectively. Tested methods for dose reduction showed a significant decrease of radiation dose from 40 to 65%. Based on these results, the mortality risk was estimated according to calculation models recommended by the Committee on the Biological Effects of Ionizing Radiations and by the International Commission on Radiological Protection. Both models resulted in similar values. The mortality risk ranges from 46.2 x 10.6 for 20-year-old men to 11.2 x 10(-6) for 65-year-old women. Using 2 methods of dose reduction, the mortality risk decreased by approximately 50 to 60% to 19.1 x 10(-6) for 20-year-old men and 5.5 x 10(-6) for 65-year-old women. It can be concluded that a CT scan of the maxillofacial complex causes a considerable radiation dose when compared with conventional radiographic examinations. Therefore, a careful indication for this imaging technique and dose reduction methods should be considered in daily practice.

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.

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.

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.

Interactions between osteoclastic cells and biodegradable polymers in vitro

The use of implants to stabilize fractured diaphyseal bone, to handle difficult bone damage and to perform augmentation or replacement procedures in bone has become a common method in bone surgery. In most cases metal implants were used. Biodegradability of implant materials offers new perspectives. Restoration of the physiological status in the implant site becomes possible. Allergic reaction and second operations to remove the implants can be avoided and transitional aid in wound healing by the use of biomaterials can be achieved. An in-vitro system was established to investigate the interactions between osteoclasts and biomaterials, since it is the osteoclasts which are potentially able to resorb or degrade implants. The cell's resorption capabilities as well as its morphological behavior were documented. Two biodegradable and four nonbiodegradable materials were tested. The non-degradable materials provoked specific cell behaviour patterns but were not resorbed. Fibrin tissue adhesive sealant, however, displayed resorption lacunae mediated by osteoclasts, whereas polydioxanone (PDS) showed no resorption sites but normal cellular morphology when compared to the standard control (cells on hydrophilic coated teflon dishes). Both materials appeared to be well accepted by osteoclasts. This test system was established for the valuation of biodegradable implant materials and can be used to characterize new materials concerning their resorbability and biocompatibility without superposition by other cell systems.

Individual skull model fabrication for craniofacial surgery

The purpose of this report is to describe a milling procedure for the fabrication of skull models from 3-D CT data. Data from computer tomographic cuts are transferred to a computer and stored. Model fabrication takes place using high quality styrodur that is shaped with a high speed milling device. This allows the modeling of an individual life size skull in its skeletal as well as in its soft tissue contours. Smaller bone pieces and areas can be enlarged separately up to eight times normal size for better visualization. Planning and simulation of craniofacial surgery in three dimensions is possible, and bone implants or alloplastic biomaterials can be modeled for implantation.

Resorption of fibrin tissue adhesive sealant by isolated osteoclasts in culture

The tissue tolerance of fibrin tissue adhesive sealants has been investigated. These materials are increasingly being used to close wounds and to stabilize spongy bone transplants. An in vitro model consisting of isolated osteoclasts in primary cell culture was used. The 2 commercially available tissue adhesive sealant protein solutions differ substantially with regard to the spreading and resorption capacity of the cultivated osteoclasts.

[Cell cultures of human osteoclasts for testing biomaterials]

A method for isolating and culturing osteoclast-like cells from cancellous bone material collected from external iliac crest bone of patients is described. Aseptic techniques were used for comminution of the bone material, treatment with collagenase and separation of the bone cells from the bulk bone through a nylon filter. The bone cells were cultured on various surfaces for ten days. Cell motility, mobility and fusion was be observed along with tartrate-resistant acidic phosphatase activity in a majority of the cells soon after they had been cultured. These large cells attached to human cortical bone fragments, where they produced resorption lacunae in vitro. These morphologic and functional characteristics indicate that the cells we had isolated were, in fact, human osteoclasts. SEM studies of these cells on various biomaterials (titanium, hydroxyl apatite, tricalcium phosphate) revealed different morphologic characteristics varying with the substrate used and allowing conclusions as to substrate acceptance. Large areas of cell contact and cell proliferation suggest a favorable response to the materials applied.

Cleft lip and palate, lower lip pits, and limb deficiency defects

Cleft lip or palate and lower lip pits are typical features of the autosomal dominantly inherited Van der Woude syndrome. Limb defects have not been reported in this syndrome so far. A girl with a unilateral complete cleft lip and palate, bilateral lower lip pits, and amniotic deformities of all four limbs is reported and the possibility of chance occurrence of cleft lip and palate, lower lip pits, and limb defects is discussed.