[Sk2 guidelines"diagnosis and therapy of snoring in adults" : compiled by the sleep medicine working group of the German Society of Otorhinolaryngology, Head and Neck Surgery]. / S2k-Leitlinie "Diagnostik und Therapie des Schnarchens des Erwachsenen" : Vorgelegt von der Arbeitsgemeinschaft Schlafmedizin der Deutschen Gesellschaft für Hals-Nasen-Ohren-Heilkunde, Kopf- und Hals-Chirurgie e. V.

These guidelines aim to facilitate high quality medical care of adults with snoring problems. The guidelines were devised for application in both in- and outpatient environments and are directed primarily at all those concerned with the diagnosis and therapy of snoring. According to the AWMF three-level concept, these represent S2k guidelines.A satisfactory definition of snoring does not currently exist. Snoring is the result of vibration of soft tissue structures in narrow regions of the upper airway during breathing while asleep. Ultimately, these vibrations are caused by the sleep-associated decrease in muscle tone in the area of the upper airway dilator muscles. A multitude of risk factors for snoring have been described and its occurrence is multifactorial. Data relating to the frequency of snoring vary widely, depending on the way in which the data are collected. Snoring is usually observed in middle-aged individuals and affected males predominate. Clinical diagnosis of snoring should comprise a free evaluation of the patient's medical history. Where possible this should also involve their bed partner and the case history can be complimented by questionnaires. To determine the airflow relevant structures, a clinical examination of the nose should be performed. This examination may also include nasal endoscopy. Examination of the oropharynx is particularly important and should be performed. The larynx and the hypopharynx should be examined. The size of the tongue and the condition of the mucous membranes should be recorded as part of the oral cavity examination, as should the results of a dental assessment. Facial skeleton morphology should be assessed for orientation purposes. Technical examinations may be advisable in individual cases. In the instance of suspected sleep-related breathing disorders, relevant comorbidities or where treatment for snoring has been requested, an objective sleep medicine examination should be performed. Snoring is not-at least as we currently understand it-a disease associated with a medical threat; therefore there is currently no medical necessity to treat the condition. All overweight patients with snoring problems should strive to lose weight. If snoring is associated with the supine position, positional therapy can be considered. Some cases of snoring can be appropriately treated using an intraoral device. Selected minimally invasive surgical procedures on the soft palate can be recommended to treat snoring, provided that examinations have revealed a suitable anatomy. The choice of technique is determined primarily by the individual anatomy. At an appropriate interval after the commencement or completion a therapeutic measure, a follow-up examination should be conducted to assess the success of the therapy and to aid in the planning of any further treatments.

Laminin-5 immunocytochemistry: a new tool for identifying dysplastic cells in oral brush biopsies.

BACKGROUND: The brush biopsy technique is not only a seminal technique but also a critically discussed method for detection of oral pre-cancerous stages and manifest carcinomas. The gamma2 chain of laminin-5 and its proteolytic fragments comprise an invasion factor for many carcinomas. OBJECTIVES: The aim of this study was to determine whether the immunocytochemical presentation of the laminin gamma2 chain identifies pre-invasive or invasive squamous cells in brush biopsies. METHODS: The value-based identification of atypical epithelia was analysed in 93 consecutive brush biopsies with histopathological diagnoses: standardized haematoxylin and eosin staining; standardized immunocytochemistry: monoclonal antibodies against laminin gamma2 chain: D4B5, 4G1, detection using ChemMate and Autostainer. RESULTS: Conventional cytology did not result in any false-positive cases, i.e. atypical cells in normal, inflamed or benignly hyperproliferative mucosa (specificity, 100%), whereas immunocytochemistry revealed one false-positive case (specificity, 98%). In brush biopsies of oral squamous cell carcinomas, the following immunocytochemical patterns were possible: (1) staining of the cytoplasm, (2) banded markings between clumped carcinoma cells and (3) positive hazes surrounding atypical cells. Bacterial colonies appeared as false-positive results. Four of 27 carcinomas and one of three recurrences were not cytologically identified (sensitivity of conventional cytology, 79%). Three of the five carcinomas not identified by cytology were immunocytochemically stained with laminin gamma2 chain antibody (sensitivity of laminin gamma2 chain immunocytochemistry, 93%). The positive predictive value was 100% for conventional cytology and 97% for laminin gamma2 chain immunocytochemistry. The negative predictive value attained was 92% for conventional cytology and 97% for laminin gamma2 chain immunocytochemistry. CONCLUSIONS: The high sensitivity level observed for method-enhanced brush cytology suggests that this technique be used as an initial diagnostic step.

[Foudroyant course of a therapy resistent Wegener's granulomatosis with negative c-ANCA]. / Foudroyanter Verlauf einer therapierefraktären Wegener Granulomatose bei negativen c-ANCA.

BACKGROUND: Wegener's Granulomatosis is a rare systemic disease characterized by the triad of necrotizing granulomas of blood vessels, upper respiratory tract, and kidneys. Diagnosis depends on clinical symptoms (ACR-criteria), detection of serum circulating antineutrophil cytoplasmic antibodies (c-ANCA) and bioptical histopathology. CASE-REPORT: A 34-year-old patient presented with intraoral ulcerating, necrotizing inflammations of the palate and the gingiva. Chest radiograph (nodules, infiltrates), urin analysis (red blood cell casts) being inconspicuous Wegener's granulomatosis was diagnosed by histopathology of an intraoral incisional biopsy. Conventional therapy with corticosteroids and cyclophosphamide relapsed while the disease was taking a progressive course (pulmonary infiltrates, necrotizing vasculitides all over the common integument). The patient died of cardiac decompensation three months after diagnosis. c-ANCAs were not present at any time of disease. CONCLUSIONS: 1. Symptoms of the head and neck are manifest in up to 95% of Wegener's granulomatosis. So knowledge of the disease is important for dentists and oral and maxillofacial surgeons in spite of its low prevalence. 2. c-ANCA-titers do not reflect disease activity. Negative c-ANCAs do not exclude Wegener's granulomatosis. 3. Wegener's granulomatosis can take a progressive, therapy resistent course.

High-molecular tenascin-C as an indicator of atypical cells in oral brush biopsies.

Tumour-invasion like wound healing is characterised by the formation of an extracellular matrix with a high tenascin-C content. The tenascin-C molecule undergoes alternative splicing. Analysis using antibody BC2 indicates that especially the high-molecular tenascin-C (hm tn-C) variants are typically tumour-associated, while distribution in normal tissue is restrictive. This study investigated whether hm tn-C is a suitable indicator of atypical cells with invasive potential in oral brush biopsies. One hundred fifty nine consecutive oral brush biopsies with histopathological diagnoses were analysed for the identification of atypical cells. A standardised haematoxylin and eosin staining plus standardised immunocytochemistry using the monoclonal anti-hm tn-C antibody was performed. The bound hm tn-C antibodies were detected with the streptavidine/alkaline phosphatase technique in the autostainer. Conventional cytology produced four false-positives when identifying atypical cells in brush biopsies of inflammatory/benign hyperproliferative mucosa (specificity 96%), while 10 in 52 carcinomas and three of eight recurrences were not identified (sensitivity 78%). Ten of these 13 non-identified tumours could be marked when adding the hm tn-C assay (increasing specificity to 99%). Combining the two assays also reduced the false-positive outcomes from four to one (increasing sensitivity to 95%). The positive and negative predictive values were 92 and 88% for conventional cytology vs 98 and 97% for the dual assay. (1) A 95%-sensitivity proves hm tn-C assisted conventional cytology to be a suitable means of identifying atypical cells in oral brush biopsies. (2) The positive (98%) and negative (97%) predictive values obtained approximate hm tn-C assisted conventional cytology to laminin-5 (100/97%).

[Oral cytology: historical development, current status, and perspectives]. / Orale Zytologie: Historische Entwicklung, aktueller Stand und Ausblick.

Oral cytology has aroused new interest caused by introduction of the cytobrush as a sampling device and the use of additional analytical methods. By brushing it is possible to reach deeper layers of the oral mucosa where squamous intraepithelial neoplasia (SIN) begins. The biological potential of the oral epithelial cells obtained can be evaluated by the following additional methods: computer-assisted image analysis (OralCDx), DNA cytometry, immunohistochemistry, monolayer cytology, and molecular biological analysis. All of those methods can increase sensitivity (up to 100%) and specificity (up to 100%) of oral brush biopsy. Nevertheless, there are reports that oral epithelial carcinomas were not identified. No comparative study exists allowing conclusions to be drawn about the value of the single methods. Immunocytochemistry with commercial antibodies against laminin-5 is generally available and methodologically easy. Oral brush biopsy as a non invasive diagnostic method can be useful for the early detection of oral mucosal lesions. Positive findings or progression of the lesion despite negative findings are indications to refer the patient to a specialized clinic where a surgical biopsy should be performed, followed by histopathological analysis. Histopathology remains the gold standard for the definitive diagnosis of oral malignant lesions.

[Computer assisted chewing power in patients with segmental resection of the mandible]. / Computergestützte Kaukraftanalyse bei Patienten mit Unterkieferkontinuitätsresektionen.

BACKGROUND: Surgical treatment of tumors of the oral cavity often requires a segmental resection of the mandible. This always implies a considerable loss in function and aesthetics. The aim of the present study was to measure the chewing force obtained by patients after mandibular resection. PATIENTS AND METHODS: In a group of 20 patients (twelve males, eight females, average age 59 years), chewing force were registered by means of a computerized measurement device. In 16 patients, the defect was bridged by a reconstruction plate, in three with an iliac bone graft stabilized by miniplates, and in one patient with only two miniplates. RESULTS: The maximum value in the molar region was 186 N und the minimum was 28 N. The average bite force in the molar region reached 81.1 N (+/-46.1) with 42.9 N (+/-35.7) in the front region. The highest value was registered in a patient with an iliac bone graft without soft tissue defect. The lowest was found in patients with bony chin defects. CONCLUSION: Based on these results, a reduction of 76% in the molar region and 59% in the incisor region was observed. These values might be helpful in providing a more realistic definition of the functional loadings found in patients after mandibular resection, which in turn may help in the development of new reconstruction devices.

[Central giant cell granuloma of the mandible. Definition and differential diagnosis]. / Zentrales Riesenzellgranulom des Unterkiefers. Begriffsbestimmung und Differenzialdiagnose.

The synopsis of radiographic examination (uni- or multilocular radiolucency), histologic findings (giant cells throughout a benign fibroblastic matrix), blood chemistry analysis (normal serum parathyroid hormone) and clinical features provides the definitive diagnosis of giant cell granuloma, allowing the clearly defined surgical management of this lesion. The case history of a 48-year-old female patient who presented with a giant cell granuloma in the right mandible is used to illustrate this controversially discussed intra-osseous lesion. The potential therapeutic change from radical operative treatment, including functional maintenance, to conservative procedures is emphasized.

[Dental injuries due to miniplate osteosynthesis. Classification, treatment management, complications, and prognosis]. / Zahnverletzungen bei Miniplattenosteosynthese. Einteilung, Therapiemanagement, Komplikationen und Prognose.

BACKGROUND: In spite of a monocortical design, miniplate osteosynthesis can injure dental roots directly as well as damage dental substance indirectly by interrupting the apical blood stream. PURPOSE: The present retrospective study classifies different types of dental root trauma caused by monocortical screws, suggests therapeutic options based on diagnosis, and documents survival probability and prognosis after tooth trauma. PATIENTS AND METHODS: During a period of 11 years, 380 patients with permanent dentition underwent miniplate osteosynthesis for the treatment of mandibular fractures, 29 of whom sustained dental root trauma caused by drilling failure. These patients were clinically and radiographically examined for a follow-up time of not less than 38 months. RESULTS: The 29 patients could be classified into four different types of dental root trauma: 13 pulp injuries above the apical third of the root (type Ia), 6 pulp injuries in the apical third of the root or extradental lesions interrupting the apical blood stream (type Ib), 4 lesions to the central radicular dentin without pulp injury (type II), and 6 lesions to the peripheral radicular dentin and root cementum (type III). Of 13 type Ia injuries, 5 developed apical periodontitis and dilatation of the periodontal space. Therefore one root canal treatment and three apicoectomies were performed. One tooth had to be extracted. Three further type Ia injuries and two type Ib injuries showed root resorptions inducing two root canal treatments. One of six type Ib injuries required root canal treatment because of apical periodontitis. One of four type II injuries caused root resorption not requiring therapy. No relevant, pathological finding could be identified after type III injury. CONCLUSIONS: The type of dental root trauma caused by miniplate osteosynthesis determines therapy, complication rate, and survival of the injured tooth.

[Metallic condylar head prostheses to replace the temporomandibular joint]. / Metallische Halbendoprothesen zum Ersatz des Kiefergelenkkopfes. Vergleich funktioneller und ästhetischer Langzeitergebnisse mit und ohne Rekonstruktion.

BACKGROUND: Up to now the results after condylar reconstruction of the mandible have been regarded as less than satisfactory. PURPOSE: Functional and aesthetic long-term results after condylar head resection in traumatic and tumour cases with or without replacement by a metallic condylar head prosthesis were compared in a retrospective study. PATIENTS AND METHODS: From 1980 to 2001, 23 temporomandibular joints of 19 patients were reconstructed with metallic condylar head prostheses. The resected region, the contralateral joint, facial and masticatory muscles and the dental system were clinically and radiographically monitored for a mean period of 4 years and 9 months. Seven patients who underwent condylar resection without substitution were observed over an average follow-up time of 7 years and 11 months. RESULTS: Patients who underwent condylar resection without substitution reported more trouble with eating and speaking for a long time. TMJ endoprostheses preserved facial symmetry better. Maximum mandibular opening as well as lateral and protrusive excursions were slightly reduced in comparison with both unaffected controls and patients who underwent condylar resection without substitution. In this study bilateral condylar prostheses exhibited the same functional and aesthetic results as unilateral arthroplasty. CONCLUSIONS: Metallic condylar head prostheses originally developed for temporary replacement worked in some cases as long-term joint replacement but were not able to reach the total functional quality of natural temporomandibular joints.

[Treatment results after surgery for basal cell carcinomas of the head and neck region taking into consideration various reconstruction techniques]. / Behandlungsergebnisse nach chirurgischer Therapie von Basalzellkarzinomen im Kopf-Hals-Bereich unter Berücksichtigung unterschiedlicher Rekonstruktionsverfahren.

BACKGROUND: Basal cell carcinomas are the most frequently occurring malignant tumors in the white population. They exhibit a multitude of histological/morphological forms. PATIENTS AND METHOD: All cases of basal cell carcinoma treated at the department for oral and maxillofacial and regional plastic surgery of the HELIOS hospital in Erfurt between 1976 and 2003 were analyzed and partly reexamined in a retrospective study. RESULTS: A total of 648 patients with 765 basal cell carcinomas were treated. Occurrences in females dominated those in males with a frequency distribution of 1.24:1. The average age was 70.6 years with a significantly larger number of female seniors above 60. In 64% of the cases the basal cell carcinomas were nodular, in 16% infiltrative. Other morphological/histological forms occurred with a frequency of

[Genioplasty alone and in combination. Long-term results with emphasis on sensitivity and photoanalysis]. / Kinnosteotomie isoliert und in Kombination. Langzeitergebnisse unter besonderer Berücksichtigung der Sensibilität und der Fotoanalyse.

PURPOSE: Striving for beauty and expressiveness is a deeply rooted human attitude. The lower jaw-especially the mentum-plays an important role in the perception of the face as an instrument of communication. According to Grammer a distinctive lower jaw is an essential characteristic feature of male attractiveness. MATERIAL AND METHODS: During a period of 10 years 58 patients underwent genioplasty. A follow-up examination was performed in 49 patients (complete sensitivity evaluation: 33 patients, complete photoanalysis: 30 patients). To reduce radiation due to cephalometric radiography a simple photometric method for cephalometry was developed and applied. Particular attention was directed at sensitivity of the mental nerve after genioplasty. RESULTS: To the best of our knowledge, this is the first time that photos of the right profile were compared with those of the left side. Unexpectedly, intraindividual differences dependent on the facial side (right and left) could be found in the relationship of the lower to the upper face and in the proportion of the profile angle and the nasomental angle. After three-dimensional genioplasty these differences were reduced and facial asymmetry was improved. Comparing the right with the left side the average difference of the nasomental angle was reduced from 2.5 degrees to 0.6 degrees on average. The profile angle was changed by genioplasty from 19 degrees on average to 15 degrees ("ideally" 10 degrees , the so-called upright face). According to Schwarz the ideal height of the mentum (stomion-menton) should amount to 66% of the total lower face. Especially by combined dorsal and cranial positioning of the mentum a reduction from 85 to 68% was achieved. Postoperatively 24 of 33 patients (73%) showed disturbances of the mental nerve. After at least 1 year following the operation, normal sensitivity of the lower lip and chin of both sides was evaluated by almost all of these patients (19 of 24 = 79%). Especially all patients having had only a single genioplasty recovered totally from a neurosensory deficit. CONCLUSIONS: Genioplasty can be considered to be a reliable procedure to achieve harmony of the lower face.

[Intra- and postoperative monitoring of transplanted flaps. Measurement of the partial pressure of oxygen in tissue]. / Intra- und postoperatives Monitoring von Lappentransplantaten. Messung des Gewebesauerstoffpartialdrucks.

BACKGROUND: According to Schmelzeisen et al. (1996), the failure rate for microvascular free flaps is 5%. While surface tissue oxygenation can be assessed clinically, if necessary by a puncture, the oxygen supply to deeper areas mostly cannot be checked. We therefore wished to find whether measurement of tissue pO(2) would prove to be an objective and practical technique that could be used for continuous and accurate intra- and postoperative evaluation of flap perfusion. MATERIAL AND METHODS: A Clark-type microcatheter was used intra- and postoperatively to monitor tissue pO(2) in 5 pedicled pectoralis major flaps and 32 free revascularized flaps (9 jejunal flaps, 5 latissimus dorsi flaps, 6 radial forearm flaps and 12 scapular flaps). RESULTS: The mean values for tissue pO(2) were significantly lower in pedicle grafts than in free revascularized flaps. Within in each flap group the pO(2) values measured did not vary significantly over an observation period of up to 77.2 h after transplantation. CONCLUSIONS: Continuous measurement of tissue pO(2) by means of a Clark-type microcatheter combined with clinical examination constitutes a reliable method of monitoring tissue oxygenation in pedicle grafts and free revascularized flaps during the intra- and postoperative phases. Analysis of small and of wide fluctuations in pO(2) values may help in the diagnosis of early arterial and venous obstructions in flaps and may in the future result in new insights into the tissue oxygenation in surgical flaps allowing some alleviation of the problems currently experienced in clinical monitoring.

[Oral adenoid squemous carcinoma. Tumor markers and prognosis]. / Orales adenoid-squamöses Karzinom. Tumormarker und Prognose.

CASE REPORT: A 58-year-old female patient presented with an exophytic adenoid squamous cell carcinoma on the right alveolar process of the lower jaw. Histological and immunohistochemical differential diagnosis and cellular background of the unfavorable prognosis are described. The patient was treated with curative intent by radical tumor resection including partial mandibulectomy, extensive conservative/radical neck dissection, and postoperative radiation. The adenoid squamous cell carcinoma was classified as pT4, pN0, cM0, R0. During radiation, regional lymph node metastases and distant metastases developed. The patient died of distant metastases 7 months after the initial diagnosis. HISTOPATHOLOGIC FINDINGS: Tumor cells of adenoid squamous cell carcinoma express epithelial intermediate filament cytokeratin, epithelial membrane antigen (EMA), and epithelial basal membrane protein laminin-5 (Ln-5). Glandular differentiation can be excluded by the absence of epithelial mucins (Alcian blue, mucicarmine). Differentiation from angiosarcoma can be performed using endothelial differential markers CD31, CD34, and factor VIII-associated antigen (FVIII-ass. AG). Both entities are characterized by high proliferation and Ki-67 index of 20%. beta-catenin (cell-cell adhesive protein) loses its primary membrane-bound localization and can explain the histologic pattern of acantholysis. Ln-5 (guide rail of invasion) is massively expressed in adenoid squamous cell carcinoma cells and may be responsible for rapid progression. CONCLUSIONS: Pseudopapillary proliferation, cellular atypia, vascular-like cavities, expression of cytokeratin, EMA, and Ln-5 are common features of oral adenoid squamous cell carcinoma and angiosarcoma. Diagnosis is determined by the absence of endothelial differential markers CD31, CD34, and FVIII-ass. AG. Modulation of the beta-catenin pattern (transcription factor of Ln-5) and massive expression of invasion factor Ln-5 are suggested as cell biological reasons for rapid progression of adenoid squamous cell carcinoma.

[Rapid setting calcium phosphate cement for craniomaxillofacial surgery. 6 years experience]. / Schnell abbindender Kalziumphosphatzement für die kraniomaxillofaziale Chirurgie. Erfahrungen über sechs Jahre.

BACKGROUND: Long-term results using hydroxyapatite cement (Bone Source) for the reconstruction of the facial skeleton and the forehead are reported. MATERIAL AND METHODS: The cement consists of 73% tetracalcium phosphate and 27% dicalcium phosphate. Using 0.25 M phosphoric acid instead of water, the primary setting time can be shortened from 20 to 5 min in an isothermic reaction. Twenty-two patients suffering from consequences of trauma, tumor-like lesions, or neoplasm as well as dysmorphia were treated. RESULTS: Following implantation, the healing process proceeded in most cases without complications. Due to hematoma and seroma as well as infection, two implants were lost. Follow-up examinations could be performed in 19 of the 22 patients on a average 40 months after operation. Most patients had good clinical long-term results. X-ray-analysis showed some discrete resorption of the implants in six patients. The further course must be decided based on clinical relevance. DISCUSSION: The hydroxyapatite cement used in this study evidenced good intraoperative handling, an excellent histologically proved biocompatibility, and good long-term stability in normal body fluid. Up to now we have limited its use to non-load-bearing applications in craniofacial surgery.

[Oral rehabilitation of tumor patients with endosseous implants. Implant success with special reference to peri-implant tissue]. / Orale Rehabilitation von Tumorpatienten mit enossalen Implantaten. Implantationserfolg unter besonderer Berücksichtigung der periimplantären Gewebe.

In a prospective study, the influence of the status of the peri-implant hard and soft tissues on the success of enosseous dental implants in tumor patients was assessed. Out of 59 tumor patients with 261 implants, treated between July 1988 and August 1996, a pool of 23 patients with 99 implants provided with dentures for at least 1 year was obtained. Eighteen of these patients suffered from a squamous cell carcinoma of the oral cavity. Seventeen patients underwent preoperative radiation (40 Gy). A total of 68 out of 99 implants were inserted into autologous bone transplanted to reconstruct the mandible. In order to assess the peri-implant hard and soft tissues, the Hygiene Index, the Sulcus Bleeding Index, the Gingiva Index, the pocket-probing depth. the peri-implant bone resorption, and the periotest were used. The results in the tumor patients were compared with the results in a pool of nontumor patients. Tumor patients had significantly worse periimplant parameters than nontumor patients. The peri-implant pocket-probing depth proved to have significant influence on the success rate. The overall success rate was 77.8%.

[Clinical application of osteoinductive implants in craniofacial surgery]. / Klinischer Einsatz osteoinduktiver Implantate in der kraniofazialen Chirurgie.

Autolyzed, antigen-extracted, allogeneic bone (AAA bone) is prepared from cortical bones of human organ donors. AAA bone possesses osteoinductive properties as it delivers BMPs from its bone matrix. Within a prospective study, 37 cranial defects were reconstructed using AAA bone implants over a period of more than 7 years. The patients were followed-up at standardized intervals. Roentgenographic assessments and bone scintigraphies revealed osseous integration and remodelling of the AAA bone implants. In one quarter of the cases re-entry was performed 10 to 18 months after the cranioplasty (removal of osteosynthesis material, recurrence of tumor). All nine AAA bone reconstructions showed bleeding surfaces and bony integrations. A bone biopsy was taken from the center of one of these AAA bone implants and this showed new bone formation originating from the surface of the implant. In one case an AAA bone implant was lost due to infection. This is noteworthy as in approximately one third of the cases the bone implants were in direct contact with the frontal sinus. The clinical results clearly emphasize the therapeutical benefit of AAA bone for cranioplasties. Large AAA bone chips from human skull bones facilitate the reconstruction of the skull's convexity, especially when sterolithography-based operation planning is performed.

[New hydroxylapatite cement for craniofacial surgery]. / Neuer Hydroxylapatitzement für die kraniofaciale Chirurgie.

A new stoechiometric mixture of 27% dicalcium-phosphate (DCPA) and 73% tetra-calcium-phosphate (TTCP) can be prepared with water intraoperatively to a paste that subsequently sets to a structurally stabile implant composed of hydroxyapatite (HA). Primary setting time is about 20 min; pH during setting ranges from 6.5 to 8.5. There is no relevant curing heat or expansion or contraction. Compressive strength is about 50 MPa, tensile strength about 8 MPa. Over a period of about 4 h in physiological milieu, the cement converts to hydroxyapatite. This product is no longer redissolvable in normal body fluid. This cement can be used for non-load-bearing applications especially in craniofacial bone surgery. Cranial defects due to tumour or trauma as well as deficits in the facial skeleton may be reconstructed using this new biomaterial. In nine of ten patients we used the hydroxyapatite cement successfully for reconstructions in the craniofacial area. Fluid control of the operation field and implant site is extremely important and sometimes difficult to achieve. Further applications could be all non-load-bearing augmentations such as filling of blocked paranasal sinuses, of dentoalveolar cysts and defects following dental apectomy or fixation of implanted hearing-aid electrodes. The perspectives for the hydroxyapatite cement include its application as a carrier for osteogenic protein preparations, especially because of its isothermic reaction and intrinsic osteoconductive characteristics.