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Biomedical subjects

M A Merkx

Publications and source records attributed to M A Merkx.

14 recordsLinked to original sources
PubMed2000

Incorporation of composite bone implants in the facial skeleton.

The purpose of this study was to evaluate the capacity of composite grafts consisting of either particulated cancellous or particulated cortical bone and anorganic bovine bone mineral (BBM) (Bio-Oss) to induce regeneration in standardized critical size bony defects overlying the frontal sinus. Four full thickness critical size bone defects were made in the frontal bone in each of 8 skeletally mature female goats. These defects were filled at random with composite cancellous bone/BBM grafts or composite cortical bone/BBM grafts. Control defects were not included but could be evaluated using data from a previous study in which the same experimental setting was used (Merkx et al. 1999a). Fluorochrome bone markers were injected subcutaneously 1 and 5 weeks after implantation, and 1 week before the animals were killed. Two animals were killed at 3, 6, 12 and 24 weeks after surgery respectively. The results were evaluated by histological means including fluorescence microscopy. In conclusion, composite grafts consisting of autogenous cancellous bone/BBM yield good results, combining the advantages of each material alone and reducing the disadvantages of each when used separately. Critical size defects in the maxillofacial area, overlying a paranasal sinus, filled with this material heal uneventfully within 12 weeks. Composite grafts consisting of cortical bone and BBM show less favorable results. These grafts induce osteoclasts, probably by the presence of non-functional BBM, resulting in resorption of the cortical bone chips.

Animals↗
PubMed1999

Incorporation of three types of bone block implants in the facial skeleton.

The regenerative response on autogenous cancellous and cortical bone grafts, and on a commercial available xenogenous resorbable bone mineral (RBM) (Bio-Oss, Geistlich-Pharma, Wolhusen, Switzerland) was compared in standardized bony defects related to a paranasal sinus. On 15 skeletally mature goats four critical sized full thickness bone defects were trephined in the frontal bone. These defects were filled at random with a cortical bone plug, a cancellous bone plug, a plug of spongious RBM cut into shape or left empty. Fluorochrome bone markers were injected subcutaneously 1 and 5 weeks after transplantation, and one week before the animals were killed. The animals were killed at 3, 6, 12 and 24 weeks after surgery. Histological evaluation showed that autogenous bone grafts were all accepted and incorporated in a similar way as in calvarial defects. RBM was only osteoconductive. New bone was formed at the margins of the defects, and only little of the RBM was incorporated. Most of the RBM was gradually resorbed by multinucleated osteoclast-like cells.

Absorbable Implants↗
PubMed1999

Incorporation of particulated bone implants in the facial skeleton.

The purpose of this study was to compare the regenerative response of autogenous cortical and cancellous bone chips and a natural particulate resorbable bone mineral (RBM) (Bio-Oss, Geistlich-Pharma, Wolhusen, Switzerland) in standardized bony defects relating paranasal sinuses to one another and to bone blocks. On 13 skeletally mature female goats four standardized critical-sized full thickness bone defects were made in the frontal bone overlying the frontal sinus. These defects were filled at random with cortical bone chips, cancellous bone chips, spongiosa granules of a RBM or left empty. Fluorochrome bone markers were injected subcutaneously 1 and 5 weeks after transplantation, and one week before the animals were killed. The animals were killed at 3, 6, 12 and 24 weeks after surgery. Autogenous cancellous bone chips is the material of choice for bridging a bony defect in the maxillofacial area where there is no need for mechanical strength. They heal in the same way as cancellous bone blocks do. Cortical bone chips are not reliable enough to be used as a solitary bone-grafting material under these conditions. A cortical block as a solitary implant gives better results. RBM granules as solitary implant in a critical-sized defect do not stimulate osteoconduction but give rise to an extensive osteoclastic activity stimulated by the mutual loose relation. A solid block of RBM is in a similar case more reliable.

Absorbable Implants↗
PubMed1997

Tooth eruption through autogenous and xenogenous bone transplants: a histological and radiographic evaluation in beagle dogs.

The effect of implanting autogenous and xenogenous (Bio-Oss) bone transplants into metabolically active sites within beagle dog mandibles during permanent premolar tooth eruption was examined. Ten 14-week-old beagles were used. Before commencing the radiographic experiments, metal bone markers were placed in the caudal margin of the mandible at the age of 10 weeks. The deciduous first and third molar teeth were extracted and their sockets over the permanent second and fourth premolars were implanted with autogenous particulate enchondral iliac crest bone, autogenous particulate membraneous mandibular body bone, xenogenous bovine anorganic bone mineral spongiosa granules (1-2mm3) (Bio-Oss, Geistlich Pharma, Switzerland) of left empty. The third premolar served as control site. Standardized oblique lateral radiographs were taken once a week. A number of coordinates of defined points and structures were determined by means of a coordinate digitizing system. Animals were killed 4, 10 and 16 weeks after bone transplantation for histological examination of the transplantation sites. All premolars showed no delay in eruption or disruption of crown and root development. On histology, the Bio-Oss particles were not resorbed or integrated in the alveolar bone but were pushed forward into the gingiva. We have demonstrated that there is on difference in the eruption curve of the permanent premolars in the four groups (ANOVA P > 0.5) and that bone transplantation has no inhibitory effect on eruption (ANOVA P > 0.3) and crown development of the underlying permanent premolar but that Bio-Oss does not have the same resorbable or integrating capability as autogenous bone grafts.

Alveolar Process↗
PubMed1996

A modification of the tibial bone-graft-harvesting technique.

A modified method of tibial bone-graft harvesting is presented. A hollow, cylindric, hand-driven instrument is used to harvest the graft at the medial slope of the tibial tuberosity. Satisfactory amounts of autogenous cancellous bone graft are available to bridge osteotomy gaps and facial fractures, fill smaller defects, and even obliterate a frontal sinus. There is minimal donor-site morbidity, and complications have not been seen in a series of nine consecutive patients.

Adult↗
PubMed1995

Effectiveness of primary correction of traumatic telecanthus.

To assess the aesthetic and functional results of primary treatment of telecanthus in patients with naso-orbito-ethmoidal fractures, the results in 36 patients were evaluated in a retrospective study. Twenty had double-sided telecanthus: 13 required an indirect technique of canthopexy and seven a direct technique. Sixteen had unilateral telecanthus, of whom six were treated by the indirect and 10 by the direct technique. The intercanthal distance (ICD) was measured directly postoperatively and more than 12 months after reconstruction. The late ICD after application of the direct technique was nearly 3 mm smaller (ANOVA, P < or = 0.02, mean 34.3 mm) and yielded 2 mm less relapse (ANOVA, P < or = 0.02) as compared with the indirect technique. Delayed or late-primary treatment showed a significantly higher frequency of epiphora (chi-square test, P < or = 0.05). Early primary treatment of traumatic telecanthus produced the best aesthetic and functional result.

Analysis of Variance↗
PubMed1995

Fracture of costochondral graft in temporomandibular joint reconstructive surgery: an unexpected complication.

The case of a 35-year-old woman with a history of several temporomandibular joint (TMJ) operations, including condylectomy, is reported. She presented with myofacial pain and partial fibrous ankylosis of her right TMJ. The ankylosis was released and an autogenous costochondral graft was used to restore the vertical dimension of the ramus. About 3 months after surgery, a fracture of the graft occurred during physical therapy. The cause of this complication is discussed with reference to the literature.

Adult↗
PubMed1995

[Ectodermal dysplasia: a heterogenic deviation].

The 'problem' of ectodermal dysplasia is discussed in conjunction with a case report and a review of the literature. In a range of hereditary disorders all ectodermal structures can be effected in a variable way: reduction of the amount of hair, sweat glands and sebaceous glands, and a complete or partial anodontia of the deciduous and permanent dentition with malformation of the erupted teeth.

Adult↗
PubMed1994

Condylar resorption after orthognathic surgery. Evaluation of treatment in 8 patients.

Several articles have been published on the subject of condylar resorption as a complication of orthognathic surgery. However, since there is little reference to treatment, the frequency of this phenomenon and the results of therapy are evaluated in a retrospective study. 8 patients out of a group of 329 who underwent sagittal split osteotomy in a 10-year period (251 bilateral, 73 Le Fort I + bilateral and 5 unilateral), were treated actively following the development of condylar resorption. 4 patients were operated upon a second time while others underwent occlusal rehabilitation. The results for the patients who underwent revisional surgery were unsatisfactory, with poor aesthetics and occlusal stability. The patients treated with an occlusal splint (+/- orthodontics and/or prosthetic therapy) had a functional occlusion and tolerable temporo-mandibular-joint complaints.

Adult↗