We report on our experience using a new endosseous implant designed to provide sufficient retention to various types of facial prostheses. In a preclinical animal experiment implants (N=12, 4 x 3.5 mm) were placed in the frontal calvarial region of nine adult pigs. The animals were sacrificed at 2, 4 and 8 weeks to evaluate the implant incorporation microradiographically. The clinical outcome and patient satisfaction of implant-retained prostheses were evaluated in a group of 10 patients with facial defects by using clinical assessment and standardized questionnaires for patients and relatives. In the prospective clinical study 33 identical modified implants for extraoral anchorage were placed for the fixation of various prostheses in the midfacial (eye, nose) and ear regions in the course of a clinical trial and observed over a follow-up period of 34 months. The bone-implant contact in the animal experiment reached 31% (+/-2) at 2 weeks, 39% (+/-1) after 4 weeks and 51% (+/-5) at 8 weeks. In the clinical trial, no implants were lost and all implants remained osseointegrated as confirmed clinically and radiographically, providing a stable prosthetic restoration. The analysis of the questionnaire indicates an improvement of the quality of life of patients with respect to aesthetic and psychological well-being. The results demonstrate that extraoral implants not only achieve sufficient osseointegration but also show good clinical handling and easy fixation possibilities for prosthetic anchorage.

Non-resorbable thermoplastic polymers have become more important for reconstructive surgery due to their excellent chemical and physical properties. Polyetheretherketone-beta-tricalcium phosphate (betaTCP-PEEK) composites were developed as alternative materials for load-bearing applications. This study presents the effect of polyetheretherketone (PEEK) specimens incorporated with 5, 10, 20 and 40 wt% beta-tricalcium phosphate (betaTCP) and processed by injection molding on cultivated osteoblast cells. Normal human osteoblast (NHOst) cells were seeded onto polymer discs to evaluate cell viability and proliferation after 24, 72 and 120 h of cultivation by employing the WST-1 assay. Standard tissue culture plastic was used as a control. The osteoblast cells were found to be viable in all PEEK groups, while the cell proliferation was progressively inhibited due to the incorporated beta-tricalcium phosphate. BetaTCP-PEEK showed concentration independent decrease of cell proliferation compared to the unfilled PEEK and the control group. In summary, this study confirms the non-toxic nature of pure PEEK, whereas this could not definitely be verified for betaTCP-PEEK as a composite material in chosen concentrations of beta-tricalcium phosphate in vitro.

This animal study (domestic pig) examined the bone formation after filling defined defects with autogenous bone or a collagen lyophilisat in combination with Platelet-rich-plasma (PRP) by evaluating bone matrix proteins. Six groups, both materials with and without PRP in two concentrations (+ 1, + 2) were compared to untreated bone by means of immunohistochemistry at 2, 4, 12 and 26 weeks. BMP-2 expression was increased at 2 weeks in the collagen + 1 group and after 4 weeks in the collagen + 1 and + 2 group. Collagen-I expression was increased at 2 weeks in all collagen groups. After 4 weeks raised levels were observed after adding the higher concentrated PRP to bone and the collagen material. Osteocalcin expression was enhanced at 2 weeks in all collagen groups and the autogenous bone + PRP1 group, after 4 weeks in the bone and collagen + 2 groups. At 12 weeks higher values were observed after adding higher concentrated PRP to bone. Osteonectin and especially osteopontin were confirmed to be effective markers of early bone formation in all specimens. The described setting allows to combine established techniques (microradiography, light microscopy) with approaches to explore the underlying biology (immunohistochemistry) on the same specimen.

BACKGROUND AND OBJECTIVES:The sensor-controlled Er:YAG laser system may be a potent tool for tissue specific cutting in surgery. In order to investigate the impact of the laser on neural tissues, inferior alveolar nerve (IAN) function was monitored by the jaw-opening reflex (JOR) during specific corticotomy in rabbits.STUDY DESIGN/MATERIALS AND METHODS:Laser jaw corticotomy was performed in 13 anesthetized rabbits. During and after specific corticotomy the JOR was evoked by electric intraoral stimulation to monitor effects on IAN function.RESULTS:The JOR permanently abolished in one case and transiently failed immediately after surgery but largely recovered within days in another rabbit. In one experiment JOR threshold increased 7 days after corticotomy. Histology did not prove any objective nerve pathology.CONCLUSIONS:Monitoring IAN function by the JOR demonstrated the relatively low risk of nerve damaging during sensor-controlled laser corticotomy.

PURPOSE:The histological differences between the defect and contact areas of the implant surface to bone were tested in 35 New Zealand White rabbits in a standardized model. Microwave plasma chemical vapor-coated implant probes were tested in control and uncoated materials.MATERIAL AND METHODS:In each femur of 35 rabbits, cylindrical implant rods with a planed side were inserted. Three groups, divided in coated and uncoated material at half, were observed 42, 84 and 168 days. The probes were examined histologically for bone-implant contact in the curved and plane (defect area) sides.RESULTS:Generally the bone-implant contact seems to be nearly constant in time in the curved area of coated and uncoated probes. Here the implant was inserted in the press-fit mode. Diamond-coated probes showed similar bone-implant contact (51.9% (42 days), 62.5% (84 days), 56.1% (168 days)) compared to uncoated material (56.2%, 65.4%, 62.9%). The defect area (plane side) had no bone-implant contact at the time of insertion and showed increasing values on longer observation times with only significant differences in the 42-day group between coated (17.85%, 35.2%, 47.7%) and uncoated materials (35.5%, 40.55%, 51.81%).CONCLUSION:The evaluation of the curved side of the implant probe showed no great variation of bone-implant contact within the described observation times. This model simulates the usual implant insertion situation. The diamond-coated material becomes osseointegrated at a later time point. The bone-implant contact was only statistically relevant in one group in comparison to uncoated material.

INTRODUCTION:In patients with oral cancer the treatment has a strong impact on the quality of life. In recent years different therapeutic concepts have been developed, which include preoperative simultaneous 'neoadjuvant' radiochemotherapy (RCT) and one-stage surgery with tumour ablation and reconstruction. Consideration of long-term survival rates yields substantial evidence that mixed-modality treatment including neoadjuvant RCT is superior to adjuvant therapy concepts based on a surgical approach with postoperative radiation.PATIENTS AND METHODS:In this nonrandomised longitudinal prospective study quality of life was evaluated in two groups made up of a total of 53 patients with squamous cell carcinoma of the oral cavity, 26 of whom underwent neoadjuvant radiochemotherapy with subsequent surgical resection while the remaining 27 received surgical treatment first and then postoperative radiotherapy. The quality-of-life core questionnaire (QLQ C-30) and the head and neck cancer module (H&N 35) of the European Organisation for Research and Treatment of Cancer (EORTC) were used. Long-term survival was estimated according to the Kaplan-Meier test.RESULTS:Postoperatively both groups showed a marked reduction in quality of life, especially in restricted chewing, swallowing and speaking. One year later their quality of life had improved substantially, though without quite reaching the preoperative quality-of-life scores. Both groups showed specific impairments in the symptom scales. With adjustment for the fact that the patients were not randomised, long-term survival was 78% in the neoadjuvant treatment group and 50% in the adjuvant treatment group.CONCLUSION:Temporary limitations in the quality of life can be expected after tumour treatment of the kinds presented here for oral cancer. Neoadjuvant therapy concept is more aggressive and might result in longer disease-free survival. The primary goal should be eradication of the tumour. Nevertheless preservation or reconstruction of a maximum of function is essential for a high level of quality of life. Combined-modality treatments seem to be superior to any kind of monotherapy and should therefore be preferred.

BACKGROUND:Giant cell lesions of the bone present similar histological features. The differential diagnosis comprises central giant cell granuloma, giant cell tumor of bone, and osteitis fibrosa cystica (brown tumor) in combination with hyperparathyroidism. Since these lesions may mimic metastatic bone disease in patients with a history of cancer, a malignant process has to be considered. Since the treatment and prognosis of these entities-benign versus malignant osteolytic bone processes-differ greatly, definitive differential diagnosis is of utmost importance.CASE REPORT:Two patients presenting with osteolytic lesions of the maxilla are reported here. In both cases a history of cancer (breast and prostate) suggested bone spreading of these malignant tumors. The clinical and histological findings were similar in both patients. One lesion was diagnosed as central giant cell granuloma, the other was found to be brown tumour in osteitis fibrosa cystica as an initial manifestation of hyperparathyroidism.DISCUSSION:The presented cases demonstrate the difficulties in establishing the correct diagnosis of patients found to have osteolytic lesions of the jawbones which is critical for the appropriate management of these patients. The article discusses the different entities of osteolytic lesions of the jawbones and the necessary diagnostic and therapeutic approach.

Das Plattenepithelkarzinom der Mundhöhle gehört zu den 10 häufigsten malignen Tumoren. Trotz kombinierter Therapiemaßnahmen, die alle in unterschiedlichem Maß Einfluss auf die Lebensqualität haben, ist die Prognose nach wie vor schlecht. In den letzten Jahren wurden Konzepte unter adjuvanter oder neoadjuvanter Kombination mit Radiochemotherapie und chirurgischer Resektion des Tumor tragenden Areals favorisiert. Neoadjuvante Therapiekonzepte scheinen dabei in Bezug auf das langfristige Überleben bessere Ergebnisse zu erbringen.

PURPOSEEpithetic solutions in the maxillofacial region are indicated if plastic surgery reconstruction is not a valid option for an extensive defect. The purpose of this study was to examine whether the extraoral implants used provided sufficient retention to be used as anchoring aids.MATERIALS AND METHODSBetween November 1999 and September 2002, 33 identical modified Ankylos implants for extraoral anchorage were placed in 10 patients for the fixation of various epitheses in the midfacial (eye, nose) and ear regions in the course of a clinical trial.RESULTSOver a follow-up period of 2 to 34 months, all implants remained osseointegrated (as confirmed radiographically), and the implants and epithetic restorations were clinically stable.DISCUSSIONThe results demonstrated that the lasting retention of maxillofacial epitheses provided by implants assures patients that their epitheses are securely fixed.CONCLUSIONThe demonstrated extraoral implant system not only achieved sufficient osseointegration but also showed good clinical handling and easy fixation possibilities for epithetic anchorage.

Purpose: We sought to present a new method for primary reconstruction of traumatic or tumor calvarial defects.Patients and Methods: Forty-one patients underwent reconstruction of calvarial bone defects between October 1998 and December 2001. Among them were 19 patients who needed reconstruction of the calvaria due to traumatic bone loss. Five of these trauma cases had insufficient primary reconstruction of the calvaria. Tumor resection caused calvarial defects in 22 patients. For primary reconstruction of the skull bone defects, calvarial split grafts were used to cover the defect as accurately as possible. The monocortical layers of the calvaria were fixed with titanium miniplates. Irregular defects surrounding the transplanted regions were filled with hydroxyapatite cement. In one case of posttraumatic bone loss, hydroxyapatite cement alone was sufficient to reconstruct the defect.Results: The follow-up of each patient was at least 6 months; the longest period was 38 months. Evaluated clinical and radiologic results are stable, showing no measurable side effects.Conclusion: Hydroxyapatite cement alone or in combination with calvarial split grafts gave clinically and aesthetically stable results in the reconstruction of skull bone defects. The cement can be used for many reconstruction possibilities in craniofacial surgery. (C) 2004 American Association of Oral and Maxillofacial Surgeons.

In order to regenerate critical-size bone defects, a variety of bone substitutes is used in addition to autogenous bone. The regenerative capacity of these bone substitutes is usually compared to the efficacy of autogenous bone known as the "golden standard". Different cytokines influence the regeneration process because of their morphogenic or mitogenic properties. Platelet-rich plasma (PRP), a platelet concentrate, is characterised by having a positive effect on wound healing, reducing bone graft resorption and increasing the density of bone transplants. This experiment was commenced with a view to studying the osseous defect regeneration after placing various combinations of "filler materials" in experimentally created defects in the forehead of adult pigs. Regeneration by means of grafted autogenous bone (Group 1) or a bovine collagen based medical device (Group 4) alone and combined with PRP in two concentrations (Groups 2, 3, 5 and 6) was evaluated by means of microradiography and light microscopy after 2, 4 and 12 weeks. The microradiographic and light microscopic findings showed that autogenous bone in combination with PRP (Groups 2 and 3) had a significant accelerating effect on early bone regeneration (2 weeks). This effect was not evident when PRP was added to the bovine collagen (Groups 5 and 6). When using the collagen alone, significantly higher mineralisation values were achieved after 2 and 4 weeks than when using autogenous bone alone. After a 12-week observation period, the existing differences between the healing processes in the various groups were more or less levelled out. In summary, the results of the study indicate that clinically autogenous bone, as expected, is the ideal defect filler. Combining autogenous bone with PRP did not provide significantly better results. The findings in the groups treated with bovine collagen indicate that its local application mimics the effect of autogenous bone and amplifies bone regeneration when comparing with the control defect.

Zu ossären Läsionen des Kiefers mit ähnlichem histologischen Bild gehören das zentrale Riesenzellgranulom und braune Tumoren bei Hyperparathyreoidismus. Da auch der radiologische Befund dieser Erkrankungen nahezu identische Merkmale aufweist, ist die differenzialdiagnostische Abgrenzung schwierig. Liegen zusätzlich maligne Grunderkrankungen vor, ist die Abgrenzung von ossären Metastasen ein zusätzliches Problem.

Die Beschichtung von Titanimplantaten mit Mitogenen oder Morphogenen kann eine zeitlich verkürzte Einheilung und ein größeres Knochen-Implantat-Interface bedeuten [1, 5, 15]. Die Sicherheit des Einsatzes von Liposomen als DNA-Träger ist in der Literatur vielfach beschrieben [4, 13, 17]. Ziel der vorgestellten Pilotstudie war es, im Tiermodell Möglichkeiten der Oberflächenaktivierung von Implantaten und zur Behandlung periimplantärer Defekte durch Liposome zu evaluieren, die für BMP-2 („bone morphogenetic protein“) kodierende DNA enthielten.

Purpose: Diamond layers can be plated with microwave plasma chemical vapor deposition (MWP-CVD) treatment on metal bases such as titanium-aluminum-vanadium alloy (Ti-6Al-4V), The bonding strength of the diamond layer to the metal base is very high, so that no fissures and partial loss of coating take place-well known phenomena that may occur with other coatings in tribologic material testing. In an experimental study using 40 New Zealand White rabbits, a new method for coating implant material was tested for stability of the bone-metal interface. Materials and Methods: The results of histomorphometric and biomechanical evaluation of coated and uncoated probes implanted in the distal femur of 40 rabbits were compared. The animals were divided into 3 groups, with observation times of 42, 84, and 168 days. Results: The bone-implant contact was 5% to 18% less in coated than in uncoated probes. Only the early group, with 42 days healing time showed significant differences. Values for the pull-off force of uncoated material were about 3 to 4 times higher than coated material (diamond layer = 2.7 mum). The force increased 2 to 3 times when 200-nm coatings were tested. Electron microscopy detected undercuts of the rough surface that were obturated by diamond when the coating was too thick. Discussion: Diamond-coated material seems to have no corrosion problems in contrast to all other known implant material. Conclusion: An inert diamond layer on a metal base can become osseointegrated. Biomechanical stability increased by thinning the diamond coating,

The connection of such key technologies as laser and sensor technology opens a broad field of applications especially in medicine. The development of sensor-controlled medical laser systems represents a quantum leap in precision and safety in medical practice. This makes the treatment or surgery more gentle and safer for both physician and patient.This paper presents the possibilities and the potential of sensor-based laser procedures in medical practice. It starts with medical laser technology and sensor systems that are already used in medical diagnostics and therapy. A concrete example from laser surgery illustrates the advantages of laser ablation for an osteotomy of the mandible and a sensor and control concept for tissue-specific bone ablation. An Er:YAG laser system was combined with a process control and qualified for layer-specific ablation of hard tissue. Layer-specific ablation of tissue is especially important when, as in the laser osteotomy of the mandible (lower jaw), vulnerable structures, as e.g. nerves (mandibular nerve), run underneath the to-be-ablated tissue that may not be damaged. The closed loop control system developed for laser osteotomy is based on the evaluation of process emissions that occur during the laser ablation and are recorded with several sensors. Thereby optical and acoustic process emissions are used for achieving switching-off criteria for the laser system before damaging the nerve. Tests were performed on dissected bone specimens from the rabbit's femur and minipig's jaw. After laser application the bone specimens were evaluated macroscopically, radiologically, histologically and by micro computed tomography.

Background: Great efforts have been taken in the past to develop laser systems suitable for bone cutting. Laser systems emitting light in the infrared spectrum (2.9, 3.0 mum) have been found to be ideal for efficient bone ablation with very little carbonization. Aim: To evaluate a new laser bone cutting system enabling the automatic detection of different tissue qualities by an integrated sensor to avoid damage to sensitive structures such as blood vessels or nerves. Material: An Erbium:YAG laser containing an integrated closed-loop control system, was constructed and tested on dissected bone. Process emissions such as resonance changes caused by the interaction of laser light and various tissue structures can be used for a controlled system. Sensor signals from a photodiode and a piezo-electric accelerometer were received and processed to guide the laser osteotomy. Methods: Tests were performed on dissected bone specimens from rabbit femur (14) and minipig jaw (6). After laser application, the bone specimens were evaluated macroscopically and histologically. Results: The specimens were evaluated histomorphometrically for the depth of cortical bone ablation when the closed-loop control system switched off the laser. Mean courses of 97.45% (pig) and 97.83% (rabbit) showed that the systems work with precision. Conclusion: After penetrating the cortical bone layer, the laser beam was promptly interrupted due to extreme changes of the signal character received by the sensor system. The in vitro tests of this new laser closed-loop control system were successful. V 2003 European Association for Cranio-Maxillofacial Surgery.