Biomedical subjects

H Kärcher

Publications and source records attributed to H Kärcher.

At least 19 recordsLinked to original sources

PubMed2000

Three-dimensional planning of alveolar ridge distraction by means of distraction implants.

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.

Adult↗

PubMed2000

[Microsurgical bone replacement].

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.

Bone Transplantation↗

PubMed2000

[Histological and histomorphometric results of implantation of dental implants by early and late implantation].

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.

Alveolar Process↗

PubMed2000

Scanning electron microscopical analysis of laser-treated titanium implant surfaces--a comparative study.

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.

Aluminum Oxide↗

PubMed2000

Neuronal anastomosis of the cutaneous ramus of the intercostal nerve to achieve sensibility in the latissimus dorsi transplant.

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.

Adult↗

PubMed2000

A comparison of growth impairment and orthodontic results in adult patients with clefts of palate and unilateral clefts of lip, palate and alveolus.

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.

Adolescent↗

PubMed2000

Review of severe osteoradionecrosis treated by surgery alone or surgery with postoperative hyperbaric oxygenation.

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.

Aged↗

PubMed2000

Vascularized transplantation of the long thoracic nerve for sensory reinnervation of the lower lip.

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.

Aged↗

PubMed2000

Neuronal structure of microvascular transplants with and without neuronal anastomosis.

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.

Adult↗

PubMed2000

Healing process after alveolar ridge distraction in sheep.

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.

Alveolar Ridge Augmentation↗

PubMed2000

Histologic results of neuronal anastomosis of the microvascular latissimus dorsi transplant.

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.

Adult↗

PubMed2000

An implant to eliminate anchorage loss during molar distalization: a case report involving the Graz implant-supported pendulum.

Based on the philosophy of the pendulum appliance, a new non-integrated implant-supported device is presented, the Graz Implant-Supported Pendulum (GISP). It is designed to distalize maxillary first and second molars in adults. It consists of 2 parts: the anchorage plate, which is fixed to the palatal bone via 4 miniscrews, and the removable part, which is a pendulum-type appliance. A finished clinical case is shown, and experiences with the GISP in comparison with other orthodontic implants are discussed. The system can be loaded 2 weeks after surgical placement, actively distalize maxillary molars consecutively, serve as an active anchor unit, and provide stability against rotational movements.

Adult↗

PubMed1999

Anatomic basis of vascularized nerve graft using the long thoracic nerve.

Vascularized nerve transplants can lead to satisfactory functional reconstruction for nerve defects. These include defects following traumatic nerve severance, iatrogenic severance during tumour resection and extensive defects in poorly vascularized transplant sites. No previous description of the long thoracic nerve as a vascularized nerve graft is available. The aim of this study was to demonstrate the anatomic and initial clinical application of such a graft. The long thoracic nerve was dissected in 84 cases to examine its length, diameter, ramification and type of perfusion. On removal of the nerve, adequate perfusion through the thoracodorsal artery and a constant anatomic course with minimal loss of function were found. The long thoracic nerve is accessible anatomically, easily dissected and removed. This may be carried out together with the thoracodorsal vein and artery and even with a pedicled myocutaneous latissimus dorsi transplant, an osseo-myocutaneous scapulo-latissimus dorsi transplant or an osseous scapular transplant. The long thoracic nerve transplant can be employed for extensive facial defects together with simultaneous osseous and myocutaneous transplants of the shoulder region.

Adult↗

PubMed1999

[Transplantation of the vascular pedicled thoracicus longus nerve for recovering sensory capacities in the mentalis nerve supply region].

In the last few years microvascular techniques have improved the morphologic and functional results of reconstructive facial surgery. A main advantage is that neuronal rehabilitation can be achieved after tumor surgery. In this study the vascularized thoracic long nerve transplant was used for neuronal reconstruction of the alveolar inferior nerve after resection during tumor surgery. Five patients were examined for recurrence of neuronal function in the mental nerve and lip region after surgery in monthly control intervals. Sensation of pressure and pain was recorded for 3 months, sensation of contact and vibration feeling for 5 months and temperature sensation for 7 months after neuronal reconstruction. Nine months after surgery the mental nerve and lip sensitivity were the same on both sides--the reconstructed and the healthy side--in four patients. Thus, the vascularized thoracic long nerve seems to be a good nerve transplant for bridging defects of the alveolar inferior nerve after resection during tumor surgery.

Aged↗

PubMed1999

Changes in soft tissue profile after sagittal split ramus osteotomy and retropositioning of the mandible.

PURPOSE: The prediction of profile changes as a result of orthognathic surgery remains a problem during preoperative planning because of the different relative movements of the hard and soft tissues. This study analyzed the changes in soft tissue profile after sagittal split ramus osteotomy and mandibular setback. PATIENTS AND METHODS: Soft tissue changes relative to hard tissue references were recorded by means of computer-supported measurements of preoperative and postoperative standardized lateral skull radiographs of 60 Class III patients. RESULTS: An average backward transposition of the osseous pogonion of 7.1 mm was recorded. Relative to movements of this reference point in the sagittal plane, the soft tissue pogonion moved 83.9%, the soft tissue menton moved 98.9%, the labrale superior moved 32.0%, the stomion moved 45.2%, and the labrale inferior moved 79.6%. The same measurements were performed in the vertical plane, and changes in soft tissue references were analyzed. There was a marked difference in soft tissue changes after mandibular retropositioning when compared with results after mandibular advancement reported in the literature. CONCLUSION: It was concluded that it is of great importance to consider both the direction and the surgical method when predicting profile changes in the vertical as well as sagittal plane after orthognathic surgery.

Adult↗

PubMed1999

Fractures of the condylar process: surgical versus nonsurgical treatment.

PURPOSE: The purpose of this study was to compare outcomes from surgical and nonsurgical treatment of condylar process fractures. PATIENTS AND METHODS: Two hundred thirty-four patients with fractures of the mandibular condylar process were treated by open or closed methods. In the follow-up study, 150 patients with a mean follow-up time of 2.5 years were analyzed using radiologic and objective and subjective clinical examinations. RESULTS: No significant difference in mobility, joint problems, occlusion, muscle pain, or nerve disorders were observed when the surgically and nonsurgically treated patients were compared. The only significant difference was in subjective discomfort. Surgically treated patients showed significantly more weather sensitivity and pain on maximum mouth opening. CONCLUSION: Because of its disadvantages, open surgery is only indicated in patients with severely dislocated condylar process fractures.

Adolescent↗

PubMed1999

Distraction implants: a new operative technique for alveolar ridge augmentation.

In the past alveolar ridge augmentation was mainly based on autologous or allogenic bone transplants. Since 1996 alveolar ridge distraction has enabled local osseous build-up without bone transplantation. The 'distraction implant', uniting qualities of a distraction apparatus with those of a dental implant, has been in use for three years at the Department of Oral and Maxillofacial Surgery of Graz University. Its application in patients with alveolar ridge atrophy and other defects is demonstrated and the first results are presented in this study. Three patients with severe alveolar ridge atrophy of the edentulous mandible, three with extensive alveolar ridge defects and three with local alveolar defects following traumatic loss of a single tooth were treated with distraction implants. Segmental osteotomy was carried out in all patients and one or two distraction implants were positioned. Following this alveolar ridge distraction was carried out. In seven cases there were no complications, whereas in one patient distraction was discontinued, and altogether two distraction implants had to be removed. All complications were treated by conventional operative techniques. Fifteen of 17 distraction implants were loaded successfully. Alveolar ridge distraction by means of distraction implants is an adequate method of alveolar ridge augmentation resulting in improved implant sites and gingival conditions. The segment for distraction should not be smaller than an upper central incisor. The implants can be used for prosthetic treatment, but long-term results are still not finalised.

Adult↗

PubMed1999

Clinical and magnetic resonance findings in the temporomandibular joints of patients before and after orthognathic surgery.

It is difficult to achieve the correct position of the condyle in the temporal fossa during orthognathic surgery in angle class II patients with disorders of the temporomandibular joint. This led us to examine the TMJ of 25 of our own patients before and shortly after orthognathic operations. We recorded the clinical and magnetic resonance imaging findings of the temporomandibular joint preoperatively and three months postoperatively. The patients had skeletal class II dysgnathia and had been treated with fixed orthodontic appliances for a mean of two years and three months before operation. Operation resulted in a mean reduction of maximal incisor distance of 12 mm. In five of the 25 patients, the pattern of mouth-opening changed. Nine patients had less pain than before surgery, and nine had fewer abnormal joint sounds. The magnetic resonance imaging showed displacement of the articular disc in 38 of the 50 joints preoperatively and in 28 postoperatively. Degenerative joint changes were not improved by operation. Improvement of the disc position was achieved by repositioning of the condylar-disc complex during orthognathic surgery in angle class II patients. Clinical and magnetic resonance imaging findings regarding the temporomandibular joint in class II patients correlated significantly both preoperatively and postoperatively.

Adult↗