Biomedical subjects
Publications and source records attributed to H Kärcher.
Seven patients with severe periodontitis that had resulted in loss of alveolar ridge bone were treated by tooth extraction followed by immediate insertion of an implant distraction device. After successful distraction and bony healing the implant was used to fit a prosthesis.
A new, immediately loadable palatal implant with rotational stability and an implant-supported pendulum for patients with dental class II dysgnathia and dental crowding is presented. In seven cases, the treatment goal of distalization of all upper molars without extraction of a single tooth was achieved within 8 months.
INTRODUCTION: Patients suffering from unilateral cleft lip, alveolus and palate exhibit a varying degree of asymmetry of the midface. Evaluation of this asymmetry can be carried out by means of 3D-CT, or a laser surface scanner. MATERIAL AND METHODS: In this paper, 3D-CT-scan data of 21 patients with unilateral clefts of lip, alveolus and palate were analysed using three-dimensional models. Evaluations of the 3D-models were carried out with the computer-aided 3D-operation simulator 3D-Cosmos. RESULTS: Asymmetry was found in the orbital, nasal and maxillary regions. The infraorbital rims were displaced craniocaudally and horizontally as well as laterally of the cleft-sided piriform aperture. This asymmetry corresponded to a dislocation of the maxillary segment on the cleft side. A deficit in volume was not reliably found.
STUDY: In this study 24 patients with tumours of the mandible, mandibular resection, neck dissection and reconstruction by microvascular iliac crest (13) or scapula transplants (11) were examined following implantological treatment. RESULTS: In all patients the implantological examination was performed on average two years and five months after implant insertion. This allowed for observation of periotest values, periimplant probing depth and sulcus bleeding (SBI). Furthermore, the loss of periimplant bone was registered radiologically. In both groups periotest values were normal. In the group with scapular transplants the mean periotest value was -3.2 and in the other group -0.8. Pathological probing depth was registered in both groups and sulcus bleeding was similar. The loss of periimplant crestal bone was similar in both groups, too. DISCUSSION: It can thus be concluded that perimimplant conditions were equal in both groups two years after implant loading. The stability of implants in scapula transplants was higher than in iliac crest transplants.
PURPOSE: The use of CT-based intraoperative navigation has greatly improved surgical control in many specialities. In this study the precision of the SMN system (Zeiss, Oberkochen, Germany) for navigated drilling before implant insertion is evaluated. MATERIAL AND METHOD: One hundred test drillings were carried out on 10 standardized acrylic lower jaw models with the aid of the navigation system after CT scanning. The CT scans were taken using a slice thickness of 1 mm. Then the CT data were transferred to the workstation of the SMN system and referentiation with the help of reference points (fiducials) of the mandibular models for superposition of the acrylic and the CT models were carried out. Referentiation of the model and the drilling were performed by a drilling tool. The limit of drilling was the upper border of the mandibular canal. The aim was to come as near as possible without perforation of the canal roof. RESULTS: An average drilling depth of 6.23 mm and a mean distance to the mandibular canal of 0.14 mm (s=0.05) was found. In 11 cases the upper border of the canal was perforated. The average penetration of the mandibular canal measured 0.19 mm. Eighty-nine drill holes were accomplished without perforation. The average distance to the alveolar canal measured 0.13 mm. CONCLUSION: A high precision of CT-based navigation for controlled drilling of mandibles for dental implants was seen.
This case report demonstrates computer assisted resection of a skull base tumour after combined chemotherapy and irradiation, in a 40-year-old man with a squamous cell carcinoma of maxilla, zygoma, orbit and skull base. The resection of the skull base was performed with computer assistance after conventional resection of the maxilla, midface, exenteration of the orbit and lymph node dissection. Following combined chemotherapy and irradiation, the original, pretherapeutic tumour extent was marked on the new, presurgical CT scan enabling resection of the skull base with the use of a navigation microscope. Thus planned resection from the presurgical CT could be transposed intraoperatively using the navigation system, and the skull base could be resected with precision.
From the clinical point of view, the state of vascularized nerve transfers is clearly demonstrated in the literature. This study was carried out to elicit the basic histologic differences between vascularized and non-vascularized nerve transfers in an animal experiment. In 46 rats, the lateral femoral cutaneous nerve was resected, and an interposition with a free (n=23) ischiatic nerve transfer on one side and a vascularized (n=23) ischiatic nerve transfer on the other side was carried out. Three months postoperatively, the rats were sacrificed and 45 nerve transfers and 46 contralateral reference specimen probes were histologically evaluated. A lower degree of nerve fibrosis and vesicular degeneration of the myelin sheath were found in the vascularized nerve transfers, compared to the free non-vascularized transfers. The thickness of the myelin sheaths was less in the free transfers. From a histologic point of view, a lower degree of degenerative changes was seen in the vascularized nerves after transfer.
OBJECTIVE: In recent years, three-dimensional (3D) CT-based planning methods have increasingly been implemented in oral and maxillofacial surgery. Alveolar ridge distraction is accomplished by unidirectional distraction devices which in turn must be positioned optimally in all three dimensions. It is the aim of this study to demonstrate 3D planning of alveolar ridge distraction by means of distraction implants. PATIENTS AND METHODS: In 1997, nine patients were treated with distraction implants for a deficient alveolar ridge. A CT-scan-based 3D milled model of the facial skull was prepared for each patient to enable preoperative diagnosis and operative planning. RESULTS: Exact preoperative diagnosis of the alveolar ridge defect and atrophy was enabled by the 3D polyurethane model. Correct positioning of the distraction implants and predictability of the course of distraction was facilitated by preoperative planning according to the 3D model. CONCLUSION: Three-dimensional planning according to a milled model is an indispensable aid to positioning of distraction implants and therefore to directed augmentation of the alveolar ridge. Correct distractor positioning is vital for optimal subsequent prosthetic treatment.
Microvascular bone transplantation has become a routine procedure. The iliac crest, scapula, and fibula are the most common donor sites. These are used for reconstruction of tumor-related defects or after osteoradionecrosis. But additional indications have been developed as defects after trauma, extreme atrophy, or hemifacial microsomia. In the future, three-dimensional techniques will improve transplantation surgery and will enable the prefabrication of transplants.
In this study, a histologic and histomorphometric analysis of delayed and immediate-placed implants was performed. An implantation of 16 self-cutting conical titanium screw implants was carried out in 8 beagle dogs. Of these implants, 8 were placed immediately after extraction of the second premolar and 8 implants were placed after 6 months of healing after extraction. For dynamic histomorphometry, fluorochrome bone markers were injected at two different times prior to euthanasia. The specimens were examined macroscopically and microscopically 8 months after implantation. A histologic, dynamic, and static histomorphometry was performed with the aid of different computer programs. A mean surface of osseointegration of 75.7% and a mean soft tissue implant contact surface of 24.2% was seen in immediate-placed implants. For delayed implantation, an osseointegrated surface of 80.7% and a soft tissue covering of 19.3% was examined. The fibrogenic structures in the cervical implant part were more dense and there were more adhesive epithelial elements (hemidesmosomes) around delayed implants. The result of the dynamic and static histomorphometry showed no significant differences in the two groups (P < 0.1). In conclusion, it can be stated that a new steady-state of the soft and hard tissue around dental implants was seen 8 months after implant insertion in both groups. There was a pseudoankylotic healing in the osseous part. The lower level of osseointegration in immediate-placed implants was caused by early resorption of bone in the crestal part. Thus, a larger part of the implant was surrounded by soft tissue and a long epithelial attachment resulted.
Design and surface qualities of titanium implants are of vital importance for long-term stability following implantation. Four different implant surfaces treated individually were analyzed with special attention focused on laser surface treatment. Surfaces with machine roughness, titanium spray coating, treated by aluminum oxide and treated by laser were examined individually. Evaluation of the surface was carried out by electron microscope examination and mechanical profilometry. The EDS analysis determined the degree of contamination of the implant surface. Electron microscope examination showed that the titanium plasma spray as well as the laser-treated implants have optimum surface qualities: a secondary and tertiary structure with micro-roughness of 10 mm and roughness ranging from 0.5 to 4 mm. The least contamination was found for machine rough surfaces as well as those treated by laser. The other implants showed contamination corresponding to the method of surface treatment. In summary the optimal surface structure with the least contamination was found for the laser-treated titanium surface. Similar surface purity was found for the machine rough surfaces. An optimal structure was also achieved by the titanium plasma spray method, however, at the cost of surface purity.
PURPOSE: The return of sensory qualities in microvascular free myocutaneous transplants is of great importance in oral and maxillofacial surgery, because such sensations are responsible for improved speech and chewing. This study evaluated the results of neuronal anastomosis of sensory nerves in free microvascular anastomosed myocutaneous flaps. PATIENTS AND METHODS: Anastomosis of the lateral cutaneous ramus of the intercostal nerve and the greater auricular nerve was performed to reestablish sensibility of the latissimus dorsi transplant. All patients had undergone tumor surgery because of an oral carcinoma and had been treated with a free microvascular myocutaneous latissimus dorsi transplant. Clinical follow-up was performed at monthly intervals postoperatively, and pain, temperature, and pressure sensations were tested, as well as 2-point discrimination and vibration perception. RESULTS: Only 1 patient showed no sensibility in the transplant. In all other patients, pressure and pain sensations were elicited first. Next, slight touch, vibration, and sharp and blunt discrimination recovered. Thermal stimuli were sensed by only 1 patient. CONCLUSION: Improved sensation of a latissimus dorsi transplant can be achieved by sensory nerve anastomosis.
OBJECTIVE: To evaluate and compare the long-term aesthetic and functional results of surgical and orthodontic treatment in patients with cleft palate and unilateral cleft lip, palate, and alveolus. DESIGN: 30 patients with unilateral cleft lip, palate, and alveolus and 30 patients with isolated cleft palate, mean age of 18.9 years, were evaluated by cephalometric and model analysis a mean of 1.5 years after orthodontic treatment. In each group the surgical treatment has been similar. RESULTS: Model analysis: The sum of every mesiodistal tooth diameter in the maxilla and in the mandible was recorded according to the Bolton analysis. Twenty patients with unilateral cleft lip, palate and alveolus had relatively large upper dental arches and nine had relatively large lower dental arches. Twenty-two patients with cleft palates had large upper dental arches and seven had large mandibular arches. Eleven patients with unilateral cleft lip, palate, and alveolus and 18 patients with cleft palate had a negative space supply (the sum of the mesiodistal tooth diameters compared with the sagittal length of the alveolar ridge) in the region of the lateral teeth. All patients had persistent transverse space deficits that were increased on the side of the cleft in patients with cleft lip, palate, and alveolus. These unilateral transversal space deficits were recorded in 22 patients with unilateral cleft lip, palate, and alveolus and in 8 patients with isolated cleft palate. Sagittal measurements were reduced in 26 patients with unilateral cleft lip, palate, and alveolus and in 23 patients with cleft palate alone. The alveolar midline of the maxilla and the mandible were displaced in 25 patients with unilateral cleft lip, palate, and alveolus and in 19 patients with isolated cleft palate. Lateral cephalometric analysis: The lateral cephalograms taken at the same time as the models showed a mean SNA of 76.8 degrees and a NL-NSL angle of 8.7 degrees, indications of a tendency towards maxillary retrognathia in patients with unilateral cleft lip, palate, and alveolus. Patients with cleft palate had a mean SNA of 79.6 degrees and NL-NSL angle of 8.1 degrees. The anterior facial vertical index was within normal limits in patients with cleft lip, palate, and alveolus (44% vs 56%). An anterior facial height index of 42% compared with 58% in patients with isolated cleft palate indicated a slight reduction in midface height with an increase in the lower face as a consequence. CONCLUSION: Orthodontic and surgical treatment can result in satisfactory results on model analysis. However, there is specific growth impairment of the maxilla 1.5 years after termination of orthodontic treatment and this influences the final cephalometric analysis, particularly in patients with cleft lip, palate, and alveolus.
We reviewed 41 patients with osteoradionecrosis of the mandible. Each patient was treated by radical resection followed by external beam irradiation. The diagnosis of infected osteoradionecrosis was confirmed clinically, radiologically, and histologically. After operation had failed, 20/41 were given hyperbaric oxygen (HBO) as in 'salvage' treatment. Daily sessions of HBO 2.5 ATA for 60 minutes (mean: 29 sessions) were given. The other 21 patients were treated by operation and antibiotics alone. HBO group (n = 20): The overall success rate for HBO after operation had failed was 13/20. Repeated debridement as first-line treatment followed by postoperative HBO was successful in 12/19. In seven of 19 patients, partial mandibulectomy and microvascular transplantation were required as second-line treatment, and this was successful in five. Primary partial mandibulectomy and microvascular transplantation followed by HBO was successful in 1 patient. Non-HBO group (n = 21): Repeated debridement was successful in 10/11 patients. Partial mandibulectomy was required as second-line treatment in the remaining one. In the other 10, partial mandibulectomy and microvascular transplantation were successful as first-line treatment in four. In the remaining six, further surgical intervention became necessary and were successful for 5-17 months (mean: 13). With a success rate of 13/20, we do not recommend HBO for the treatment of osteoradionecrosis.
Microsurgical techniques have improved functional and morphological reconstruction of the face in recent years. An important factor is the re-establishment of neuronal function. The aim of this study was a follow-up of the regeneration of sensation in the inferior alveolar nerve after partial resection of a tumour and reconstruction with a vascularized long thoracic nerve graft. Five patients were examined in monthly intervals to assess the degree of re-establishment of sensation. Pressure and pain responses were elicited as early as three months postoperatively, sense of touch and vibration were found after five months, and sensitivity to temperature after seven months postoperatively. In four patients nine months postoperatively, sensory qualities in the region of the mental nerve were identical on both sides. The vascularized long thoracic nerve is therefore an adequate nerve graft for covering defects as a result of resection of the inferior alveolar nerve patients with tumours.
OBJECTIVE: Latissimus dorsi transplants have little neuronal regenerative capacity without neuronal anastomosis. Histologic differences between transplants with and without neuronal anastomosis and 2 distinct types of neurosurgical reanastomosis are highlighted in this study. PATIENTS AND METHODS: Fifty-four patients with squamous cell carcinomas of the oral cavity (T4) were treated by tumor resection and homolateral neck dissection. The defect was covered with a microvascular latissimus dorsi transplant. In 15 patients, no neuronal anastomoses were performed. In 21 patients, the thoracodorsal nerves were used for microneurosurgical reanastomosis, whereas in 18 patients, the cutaneous branches of the intercostal nerves were used for microneurosurgical reanastomosis. The transplant was examined during surgery and 9 months after surgery by means of a histologic examination of a biopsy specimen. The number of fascicles, the degree of fibrosis, and the myelination were examined. Furthermore, a neurosensory examination was performed 9 months after surgery. RESULTS: Overall, our patients had an average of 12.1 fascicles during surgery. After surgery, patients without neuronal anastomosis showed an average of 4.9 fascicles, patients with nerve anastomosis to the cutaneous branches of the intercostal nerve showed an average of 6.2 fascicles, and patients with anastomosis to the thoracodorsal nerve showed an average of 9.6 fascicles. In cases of nerve anastomosis, a lesser degree of fibrosis was found, together with good myelinization. The clinical examination showed the best neurosensory function in the transplants with anastomosis to the thoracodorsal nerve and the worst function in those without neuronal anastomosis. CONCLUSION: Neuronal reanastomosis led to more surviving neuronal structures in the postoperative histologic specimen. The highest density of fascicles was found in the well vascularized thoracodorsal nerve. The neurosensory function agrees with the histologic result.
OBJECTIVE: Mandibular augmentation by distraction of the alveolar ridge has been in use for several years. Since 1996, a distraction device that remains in the alveolar ridge after distraction has been used by the Department of Oral and Maxillofacial Surgery of Graz University. The distraction device is transformed into a dental implant after the end of the distraction process and can later be used for prosthetic purposes. We aimed to show the application of the device in this animal experiment and to follow the osseous healing process. STUDY DESIGN: Two distraction implants were inserted into the mandibles of 8 sheep. Distraction of 0.5 mm per day was carried out for 8 days. Two sheep were killed 1, 2, 3, and 6 months after distraction, and the dissected mandibles were examined clinically, radiologically, and histologically. RESULTS: After the first month of distraction, only slight radiopacity of the distraction gap was found. This increased steadily up to the third month after distraction. The boundary between the distraction fragments and the gap disappeared gradually. Six months after distraction, a homogeneous fine-meshed spongiosa structure was found in the area of distraction. Histologic examination showed desmoid ossification in the distraction gap and a continued increase in osteoid. After 6 months, mature bone was found. Only in the center was the rebuilding process not complete. Six months after distraction, osseointegration of the implants was shown in the region of the screw thread and distraction cylinder. CONCLUSIONS: The healing process corresponded to that found in long bones, but showed only desmal ossification. Osseous integration of the distraction implants was found 6 months after distraction, although the implants were stable 3 months after distraction.
Latissimus dorsi transplants have little neuronal regenerative capacity without neuronal anastomosis. Histologic differences between transplants with and without neuronal anastomosis and two distinct types of neurotization are highlighted in this study. Eighteen patients after tumor resection and defect coverage with a latissimus dorsi transplant were examined preoperatively and postoperatively by means of a biopsy for histologic examination. The number of fascicles, degree of scarring, myelinization, and fibrosis were examined. All patients had a mean of 11.8 fascicles preoperatively. Patients without neuronal anastomosis showed an average of 5.0 fascicles, patients with nerve anastomosis to the cutaneous branches of the intercostal nerve showed an average of 6.2 fascicles, and patients with anastomosis to the thoracodorsalis nerve showed an average of 9.2 fascicles postoperatively. In cases of nerve anastomosis, a lesser degree of fibrosis was found, together with good myelinization. Neuronal reanastomosis led to more vital neuronal structures in the postoperative histologic specimen. The highest density of fascicles was found in the case of the well-vascularized thoracodorsalis nerve.