Biomedical subjects

F W Neukam

Publications and source records attributed to F W Neukam.

At least 55 records · Page 3Linked to original sources

PubMed2000

Soft tissue profile changes after autogenous iliac crest onlay grafting for the extremely atrophic maxilla.

PURPOSE: The aim of this study was to evaluate profile changes in the hard and soft tissues after onlay grafting in the extremely atrophic maxilla. PATIENTS AND METHODS: Onlay grafting using autogenous iliac crest bone grafts was performed in 49 patients (42 females and 7 males) with extreme atrophy of the edentulous maxilla (vertical amount of bone: <6 mm, transverse amount of bone: <5 mm). For the assessment of the changes to the hard and soft tissues, the preoperative and postoperative cephalograms were traced and the cephalometric measuring points (44 skeletal and 25 soft tissue points) were digitalized with the aid of the Dentofacial Planner System. Evaluation of a relationship between soft tissue and hard tissue profile changes was performed by comparing the movement of the skeletal points Sub-ANS and A-point with the shift of the soft tissue point SLS. To determine significant hard tissue and soft tissue changes, the measured values were evaluated using the SPSS program system and examined for statistical significance by use of the Wilcoxon test. RESULTS: An advancement of the bony maxilla profile in the sagittal direction by an average of 2.4 mm (P < .01) was found. The soft tissue profile of the upper lip was moved forward on average by 2.3 mm (P = .0039) at the superior labial sulcus point and by 2.7 mm (P = .0018) at the labrale superius point. The ratio of the soft tissue change to hard tissue change was 0.7:1 (superior labial sulcus: skeletal point sub-ANS) or 0.9:1 (superior labial sulcus: A point). CONCLUSIONS: When planning onlay graft operations, consideration should be given to the functional and aesthetic effects of the profile changes on the upper lip.

Adult↗

PubMed2000

Osseointegration of endodontic endosseous cones: zirconium oxide vs titanium.

OBJECTIVE: The purpose of this investigation was to investigate the osseointegration of zirconium oxide (ZrO(2)) ceramic cones in comparison with that of titanium cones in apicectomy. STUDY DESIGN: To evaluate the bone/implant interface, 20 ZrO(2) cones and 20 titanium cones were inserted into the mandibles of 4 Göttinger minipigs. During the 6-month healing period, intravital polychrome sequence marking was performed. Qualitative light microscopic, fluorescence microscopic, and quantitative histomorphometric assessment was carried out. Differences between continuous histomorphometric measures were tested through use of a 2-way analysis of variance. RESULTS: Light microscopy revealed zones of direct bone contact with the ZrO(2) and titanium surfaces. Fluorescence microscopy revealed remodeling processes directly adjacent to both material surfaces. There was no significant difference in the distances of the fluorescence bands of each fluorescence marker for either the ZrO(2) surfaces or the titanium surfaces. Quantitatively and histomorphometrically, the mean ratio between the total cone/bone contact and the total cone/fibrous tissue contact was 0.95 (SD 1.10) on the titanium surface (n = 38) and 1.47 (SD 1.12) on the ZrO(2) surface (n = 78; P =.02). CONCLUSIONS: The qualitative results show that the biocompatibility of ZrO(2) was similar to that of titanium. The use of ZrO(2) cones for sealing purposes in resected teeth after apicectomy appears to be acceptable.

Analysis of Variance↗

PubMed2000

A new distraction device to compare continuous and discontinuous bone distraction in mini-pigs: a preliminary report.

Callus-distraction has become an accepted procedure to lengthen hypoplastic mandibles in humans. Extra- and intraoral devices have been applied successfully. Systematic studies have proven the importance of direction, stability, rate and frequency in callus-distraction. In an experimental animal study a newly developed intraoral microhydraulic osteodistractor was tested. Initially the pressures necessary to distract the mandible in mini-pigs were recorded in discontinuous callus-distraction. These results were used to perform continuous bone distraction. Besides testing the new distractor and evaluating the distraction pressures, the aim of the study was to prove that direct bone growth occurred without preceding cartilage formation. Clinical and microscopic results are presented.

Animals↗

PubMed2000

Histomorphometric analysis of irradiated recipient vessels and transplant vessels of free flaps in patients undergoing reconstruction after ablative surgery.

The aim of the study was to investigate, histomorphometrically, quantitative and qualitative changes in irradiated neck recipient vessels and transplant vessels used for microsurgical anastomoses in free flaps in patients undergoing preoperative radiotherapy and chemotherapy. In 55 patients receiving 42 radial forearm flaps, 6 latissimus dorsi flaps, 6 osteomyocutaneous fibula grafts and 1 lateral arm flap, a total of 220 vessels were obtained from neck recipient vessels and transplant vessels during anastomosis. Three groups were formed: Group 1 (16 patients) treated with no radiotherapy or chemotherapy; Group 2 (20 patients) treated with preoperative irradiation (40-50 Gy) and chemotherapy (800 mg/m2 5-FU and 20 mg/m2 cisplatin) 1.5 months prior to surgery; Group 3 (19 patients) treated with radiotherapy (60-70 Gy) (median interval 78.7 months; IQR 31.3 months) prior to surgery. From each of the 220 vessel specimens, 3 sections each were histomorphometrically investigated, both qualitatively and quantitatively. To evaluate these changes as a function of age, radiation dose and chemotherapy, a statistical analysis was performed using analysis of covariance and chi-square tests. In Group 3, qualitative changes (intima dehiscence, hyalinosis) were found in recipient arteries significantly more frequently (25%, P=0.009) than in Groups 1 and 2. For Group 3 recipient arteries, histomorphometry revealed a significant decrease in the ratio of media area/total vessel area (median 0.53, IQR 0.10) in comparison with Group 1 (P= 0.02) (median 0.60, IQR 0.29) and Group 2 (P=0.046) (median 0.59, IQR 0.10). No significant differences were found between the vessels of Groups 1 and 2 (P= 0.48). Age and chemotherapy did not appear to have a significant influence on vessel changes in this study.

Adult↗

PubMed1999

[Masticatory rehabilitation of tumor patients by endosseous implants. 10 year analysis].

A total of 409 implants was inserted into 83 consecutive patients, who had tumor-related intraoral resections of soft tissue and bone. A life table analysis was used to determine the survival rate of the implants placed over a period of 13 years. Log rank tests and a Cox regression analysis were employed to identify relevant effects of surgical parameters on implant survival. A total of 38 implant failures were encountered. Most of the losses (n = 16) occurred during the first year of functional loading. The cumulative, overall survival rate of implants was 56.5%. Previous radiation therapy, insertion into grafted bone or original jaw bone, and insertion into microsurgically revascularized grafts did not significantly affect the survival rates. In the Cox regression, only the timing of implant placement was significantly related to the survival rate in the group of patients with bone grafts (P = 0.0197), with a lower survival rate of 36.2% of primary inserted implants and 67.1% survival in the group with secondary implant placement.

Bone Transplantation↗

PubMed1999

Prospective study on post-traumatic and postoperative sensory disturbances of the inferior alveolar nerve and infraorbital nerve in mandibular and midfacial fractures.

In a prospective study (January 1999 to December 1997), 34 patients with 26 mandibular and 20 midfacial fractures were investigated. All the fractures were managed by osteosynthesis. To evaluate the incidence and duration of recovery of post-traumatic and postoperative sensory disturbances, the following tests were carried out: sharp/blunt testing, and the two-point discrimination test as conventional clinical examination methods, and electromyographic recording of the masseter reflex to calibrate the clinical findings. To establish the sensory status of the inferior alveolar and the infraorbital nerves in the region of the fracture, and on the intact and control sides, the tests were performed pre-operatively and postoperatively on the seventh day, after 4 weeks and after 3, 6 and 12 months. The incidence of post-traumatic sensory disturbance was 46% for mandibular fractures and 65% for fractures to the midface (sharp/blunt test, two-point discrimination test). The rate of postoperative sensory disturbance in surgical treatment of mandibular fracture involving the region of the intra bony course of the inferior alveolar nerve, including the post-traumatic sensory disturbance, was 76.9%, and 55% following surgical treatment of midfacial fractures. The incidence of persistent sensory disturbances following surgical treatment was 7.7% in the case of mandibular fractures, and 15% in the case of midfacial fractures (sharp/blunt test, two-point discrimination test, masseter reflex). Recovery of neurological function is delayed in the presence of a displaced fracture (> 1 mm) as compared with non-displaced fractures. For the postoperative calibration of sensory disturbances, electromyographic recording of the masseter reflex from the fourth postoperative week onwards has proved useful.

Adolescent↗

PubMed1999

Long-term results of endosteal implants used for restoration of oral function after oncologic surgery.

The aim of the present study was to analyse the long-term survival rate of endosteal implants used for restoration of oral function in patients having undergone oncologic surgery. Eighty-three consecutive patients, who had received a total of 409 endosteal implants ad modum Brånemark, subsequent to resections of soft tissue and bone during ablation of oral malignancies, were enrolled into the study. A life-table analysis was used to determine the survival rate of the implants placed during a period of 13 years. Log rank tests and Cox regression analysis were employed to identify relevant effects of surgical parameters on implant survival. A total of 38 implant failures were encountered. Most of the losses (n = 19) occurred during the first year of functional loading. Subsequent failures were evenly distributed across the remaining follow-up period. The cumulative overall survival rate of implants was 56.5%. Previous radiation therapy, insertion into grafted bone or original jaw bone and the technique of grafting did not significantly affect the survival rates. In the Cox regression analysis, the timing of implant placement in the group of patients with bone grafts (primary vs. secondary placement) was significantly related to the survival rate (P = 0.0197), with a lower survival rate of 36.2% for primary insertion of implants and 67.1% for secondary placement.

Adolescent↗

PubMed1997

Survival analysis of endosseous implants in bone grafts used for the treatment of severe alveolar ridge atrophy.

PURPOSE: The aim of the current study was to evaluate the long-term results of endosseous implants placed into autogenous bone grafts in severely atrophic alveolar ridges. PATIENTS AND METHODS: A total of 871 implants were placed in 137 patients. The success rate was determined using survival analysis, log rank tests, and a cox regression analysis. RESULTS: Seventy-four implant failures were encountered in 23 patients. Most implants were lost because of a lack of osseointegration at the time of abutment connection or by asymptomatic loosening during the first months thereafter. The overall 1-year cumulative survival rate (CSR) was 83.4%, with a decrease to 67.8% after 5 years. The only parameter of prognostic relevance in the multivariate analysis of the whole study population was the patients' gender, with a significantly worse prognosis in female patients (5-year CSR, 62.3%). However, when the patients were divided into edentulous and partially edentulous jaws, a change was observed in the overall significance of the parameters introduced into the analysis. In edentulous patients, the maxilla appeared to over-rule all other parameters, with a 5-year cumulative survival rate of 48.8%, whereas the mandible presented a significantly higher rate of implant survival (5-year CSR, 89.3%). CONCLUSION: This study shows a poorer success rate in females than in males, probably because of differences in the quality of the bone grafts.

Adolescent↗

PubMed1997

Use of sequential bone scintigraphy for monitoring onlay grafts to grossly atrophic jaws.

OBJECTIVES: To evaluate the capability of sequential bone scintigraphy for assessing the viability of avascular onlay grafts in combination with primary or secondary implant placement. METHODS: Forty-six patients with severe alveolar ridge atrophy received full-arch onlay grafts from the iliac crest. Twenty patients received primary insertion of endosseous implants, while secondary implant placement was performed in 26 patients after an average interval of 95 days. In cases of primary implant placement, bone scintigraphy was performed after grafting and before abutment connection. In patients with secondary insertion, bone scans were performed after grafting, before and after implant placement and before abutment connection. For bone scintigraphy, 8 MBq 99mTc-MDP/kg body weight were administered intravenously and anterior views of the skull were obtained 3 h later. Regions of interest were drawn over the grafted area and over the calvarium as a reference area. Ratios of count densities between jaw and calvarium were calculated as a measure of tracer uptake. RESULTS: Bone grafts with primary insertion of implants showed a significant decrease (P = 0.0001) in ratios calculated for the whole graft from a mean of 3.53 after grafting to 2.35 before abutment connection. In cases of secondary implant placement, ratios decreased significantly after grafting from 4.04 to 2.78 before implant placement (P = 0.0001). After implant placement, there was a significant increase to 3.28 (P = 0.0062), which was followed again by a significant decrease to a mean ratio of 2.58 (P = 0.0437). CONCLUSIONS: Sequential bone scintigrams can provide information about the viability of the graft at the time of implant insertion and may thus indicate the ability of the grafted bone to accomplish osseointegration.

Adult↗

PubMed1997

[Profile modification of the middle and lower face after anterior onlay osteoplasty in severe atrophy of the maxilla].

A retrospective study was performed to evaluate hard- and soft-tissue changes after onlay bone grafts in atrophic maxillae. The assessment included 49 patients who received bone grafts from the iliac crest. Lateral cephalograms were taken pre- and postoperatively and analyzed by the Dentofacial Planner System. Sagittal hard tissue changes from 2.3 to 3.5 mm (p < 0.01) in an anterior direction were found. Soft-tissue advancements from 2.3 mm (p = 0.0039) to 2.7 mm (p = 0.0018) were measured. The relationship of soft-tissue changes to hard-tissue changes ranged from 0.7:1 to 0.9:1.

Adult↗

PubMed1996

The free revascularized rectus abdominis myocutaneous flap for the repair of tumour related defects in the head and neck area.

The present work reviews a series of 11 consecutive patients who have received free revascularized rectus abdominis myocutaneous flaps for primary reconstruction of soft tissues after ablative tumour surgery in the head and neck area. In 10 patients, a total or subtotal glossectomy had been performed and the flap was used to replace the resected tongue volume. In 5 of these cases, extensive perforating defects had resulted after additional resection of large portions of the chin and the cheek. Mandibular continuity was restored by a metal plate and the flap was divided into an intraoral and extraoral portion in these patients. In one patient, the flap had been used for closure of a full thickness defect of the calvarium. 9 of the 11 flaps healed uneventfully. In one case, a partial flap loss was encountered after thrombosis of the venous pedicle due to compression as a result of an unfavourable defect anatomy and flap positioning. Primary closure of the abdominal wall was achieved in all cases. A subcutaneous hematoma occurred at the donor site in one patient. According to our present experience, the rectus abdominis free flap may serve as an alternative to the frequently employed latissimus dorsi flap in maxillofacial reconstructions while it offers the possibility for flap elevation simultaneously to the surgical procedures in the head and neck area.

Arteries↗

PubMed1996

Masticatory function of postoperative tumor patients rehabilitated with osseointegrated implants.

PURPOSE: This study determined the level of masticatory function that can be achieved with osseointegrated implants in postoperative tumor patients. PATIENTS AND METHODS: Masticatory function was evaluated in 15 postoperative tumor patients with implants, 22 nontumor patients with implants, and 15 natural dentate controls. The area of occlusal contact was evaluated with a pressure-sensitive, color-developing bite sheet analyzed by computer. Chewing performance was evaluated by a low-adhesive, color-developing, chewing-gum system. RESULTS: Subjects in the tumor group had load-bearing tooth contacts similar to those of the natural dentate controls and nontumor implant patients. Continuity of the mandible was essential to sustain occlusal load. The presence of the hypoglossal nerve was the main factor in determining restoration of chewing performance. CONCLUSIONS: Surgical efforts to preserve the mobility of the residual tongue and prosthetic approaches to restore impaired mobility to as great an extent as possible are especially important for better functional rehabilitation of patients who have defects of the hypoglossal nerve.

Adult↗

PubMed1996

[Reconstruction of speech and chewing function after extensive tumor resection in the area of the jaw and face].

BACKGROUND: Following extensive resections of head and neck tumors, re-establishing speech and masticatory function are of crucial importance for the patient. METHODS: In 23 patients with vascularised jejunal grafts for reconstruction of the intraoral mucosa, tongue and floor of mouth, a speech intelligibility test was performed, tongue and floor of mouth mobility was investigated using a 3.5 MHz ultrasound scanner. In another 18 patients with vascularised bone grafts for reconstruction of the mandible, masticatory function was analysed using a T-scan system and a miniature pressure transducer. RESULTS: Speech results with jejunal grafts in the lateral floor of mouth/tongue region may attain 91.4%, in anterior floor of mouth reconstructions 63.4%. Patients with implant-bone dentures and vascularised bone grafts prefer the non-reconstructed side for chewing. Masticatory force is significantly diminished compared to a control group. DISCUSSION: Lack of neurosensitive feedback mechanisms may be responsible for diminished chewing pressure and also for inferior speech results despite good floor-of-mouth/tongue mobility. CONCLUSIONS: Despite complex microvascular tissue reconstructions, severe functional impairments remain and necessitate further investigations on improvement of postoperative speech, swallowing and chewing function.

Adult↗

PubMed1996

Postoperative function after implant insertion in vascularized bone grafts in maxilla and mandible.

Between 1988 and 1992, 80 Brånemark-type implants were inserted in 18 patients during reconstruction of the mandible or maxilla with vascularized iliac crest or scapula grafts with or without additional soft tissue pedicles. In these procedures, nine vascularized bone grafts were combined with a primary insertion of 32 implants and a secondary insertion of 48 implants. Twelve patients are currently wearing the implant-borne dentures. From 32 implants inserted primarily, eight could not be used for prosthodontic rehabilitation because three were lost with a graft, three were left as sleepers, and two demonstrated a lack of osseointegration. None of the implants inserted secondarily in grafts were lost. Primary implant insertion should be performed only in close cooperation with the prosthodontist and in selected cases, for example, in free-end reconstruction of the mandible with a straight graft and where a limited number of implants is needed. Although restoration of masticatory function in patients with head and neck cancer can be achieved, compared with a healthy control group, functional impairments remain. Patients subjectively favor the nonreconstructed side of the mandible or maxilla for chewing. These findings can be correlated with a postoperative follow-up investigation using a miniature force transducer and the T-scan system.

Denture, Partial↗

PubMed1996

[Incidence and regeneration time of disorders of the inferior alveolar nerve in osteosynthesis of mandibular fractures--a prospective clinical study].

In a prospective study posttraumatic and postoperative sensitivity disturbances after mandible fractures in the region of osseous course of the inferioralveolar nerve were assessed. The study contains 28 patients with 31 mandible fractures. For assessment somato sensoric evoked potentials and computer assisted pain and thermal sensitivity testing was used. A rate of 32% posttraumatic and 52% nerve disturbances resulting from osteosynthesis was found. In 81% the sensitivity disturbances lasted only 6 months post-operatively. In 19%, mainly cases of fracture dislocation of 5 mm minimum, anesthesia and hypesthesia lasted for more than half a year.

Adolescent↗

PubMed1996

[Bone SPECT of the jaws after fracture, onlay osteoplasty of insertion of implants].

AIM: The aim of this study was early differentiation between uncomplicated and complicated processes of healing in the jaw using bone SPECT. METHODS: Investigations were performed in 40 mandibular fractures and 26 jaws after onlay osteoplasty as well as secondary insertion of implants. Bone SPECT was carried out within 1-2 months and after approximately 4-5 months. The uptake in the jaw was assessed semi-quantitatively using ROI analysis. RESULTS: Fractures with uncomplicated healing showed a decrease of uptake in follow-up, whereas fractures with an infection in the later course showed an increase, resulting in a significantly higher uptake at the follow-up investigation for the latter group. 1-2 months after onlay osteoplasty significantly lower uptake was found in regions with later occurrence of sequestration. In regions with implants in which osseointegration failed, there was significant reduction of uptake initially and significant elevation at the follow-up investigation. CONCLUSION: These results indicate a prognostic relevance of bone SPECT in the evaluation of processes of healing in the jaw.

Adolescent↗

PubMed1995

Evaluation of the incorporation of bone grafts used in maxillofacial surgery with [18F]fluoride ion and dynamic positron emission tomography.

This study investigates the incorporation of bone grafts used in maxillofacial surgery by means of [18F]fluoride ion and positron emission tomography (PET). It considers patients who received pedicle grafts for mandibular reconstruction or onlay grafts for alveolar ridge augmentation. Dynamic PET images and arterialized venous blood samples were obtained within a 1-h period after i.v. injection of [18F]fluoride. Assuming a three-compartment model and applying multilinear least squares fitting, bone blood flow (K1) and fluoride influx (Kmlf) were determined. Additionally Patlak plot analysis was used to calculate fluoride influx (Kpat). In cervical vertebral bodies as the reference region, mean values for flow of K1 = 0.1162 +/- 0.0396 ml/min/ml and influx of Kmlf = 0.0508 +/- 0.0193 and Kpat = 0.0385 +/- 0.0102 ml/min/ml were found. Essentially these figures are comparable with physiological values in animal and man reported in the literature. Early after surgery a significant increase in flow and influx compared to vertebral bodies was observed in the regions of osteosyntheses between grafts used for reconstruction and recipient bone (K1 = 0.2181, Kmlf = 0.1000 and Kpat = 0.0666 ml/min/ml) and in onlay grafts (K1 = 0.2842, Kmlf = 0.1637 and Kpat = 0.0827 ml/min/ml). At the same time pedicle grafts showed a significant increase in flow but not in influx (K1 = 0.2042, Kmlf = 0.0774 and Kpat = 0.0529 ml/min/ml). Furthermore Kpat was significantly lower in pedicle grafts than in onlay grafts. In follow-up studies a significant decrease in flow occurred in pedicle grafts and the regions of osteosyntheses. Moreover the latter showed a significant decrease in Kmlf as well. It is concluded that [18F(-)] PET depicted increased blood flow and osteoblastic activity in onlay grafts and regions of osteosyntheses, indicating bone repair in the graft and adjacent host bone early after surgery. For the regions of osteosyntheses the decrease in both parameters corresponded to uncomplicated healing. The lack of increased influx, although flow was increased in pedicle grafts, most likely indicates that some necrosis occurred in these grafts despite patency of anastomoses. It may be concluded that [18F(-)] PET provides further insight into the biology of graft incorporation.

Adult↗

PubMed1995

Experimental transplantation of hydroxylapatite-bone composite grafts.

PURPOSE: This study was undertaken to determine if autogenous bone can be cultivated in vivo in a porous hydroxylapatite (HA) matrix by ingrowth from underlying bone and if this autogenous HA-bone composite graft can then be transplanted. PATIENTS AND METHODS: Five Göttingen minipigs received subperiosteal implantation of one HA block each (40 x 10 x 10 mm), covered by a polylactic membrane, on the ascending ramus of the mandible. After 5 months, half of each implant was harvested and transplanted as an onlay graft to the horizontal ramus of the mandible with simultaneous insertion of a titanium implant. Polychrome fluorescence labeling was done 1, 2, 4, and 8 weeks postoperatively. After 3 months, the vascular system of the animals was filled with BaSO4 for microangiographic examination, and all blocks were retrieved. RESULTS: Fluorescence microscopy showed that there was a significant decrease in deposition of the label in the grafted blocks at 1 week when compared with later labels. After the second week, there were no significant changes. A 20% to 30% decrease in the frequency of fluorochrome staining was noted in the upper third of each block. In this region, microangiography demonstrated highly vascularized tissue and limited bone resorption. CONCLUSION: It was concluded that cultivation of mandibular bone in a porous matrix under guided bone regeneration is possible and that this autogenous HA-bone composite graft can be transplanted at a later date.

Angiography↗