Publications by authors named "Hans-Albert Merten"

Purpose: The success rate of dental implants after graftless sinus augmentation versus conventional sinus augmentation surgery in atrophic maxillae in edentulous patients was investigated.

Methods: This randomized study was performed in ten edentulous patients with marked maxillary atrophy. On the graftless side, the sinus membrane was lifted by a resorbable membrane.

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Introduction: In edentulous patients the form and size of the maxillary sinus vary greatly. Therefore sinus floor augmentation is a standard procedure for implantological purposes. As the sinus membrane cannot be characterized as periosteum, various augmentation materials are used.

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Purpose: Sinus floor elevation via the lateral window approach represents a reliable technique for bone augmentation in the atrophic posterior maxilla. It is known that sinus membrane elevation leads to new bone formation. This prospective clinical study compared a specific technique in sinus membrane elevation with a conventional sinus floor augmentation (xenogenous/autogenous bone) in a human split mouth model.

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Aim: The aim of this study was to test the hypothesis that recombinant human growth and differentiation factor-5 (rhGDF-5) in combination with a beta-tricalcium phosphate (beta-TCP) scaffold material results in superior bone formation in sinus floor augmentations in miniature pigs compared with a particulated autogenous bone graft combined with the scaffold material.

Material And Methods: Six adult female Goettingen minipigs underwent a maxillary sinus floor augmentation procedure. In a split-mouth design, the sinus floors were augmented with beta-TCP mixed with autogenous cortical bone chips, in a ratio of approximately 1 : 1, on one side.

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Aim: The aim of this study was to test the hypothesis that recombinant human growth and differentiation factor-5 (rhGDF-5) enhances bone formation in sinus floor augmentations in miniature pigs.

Material And Methods: The maxillary sinus floors in 12 adult female Goettingen minipigs were augmented with beta-tricalcium phosphate (beta-TCP) on one side. The contralateral test side was augmented using two concentrations of rhGDF-5 (400 microg rhGDF-5/g beta-TCP; 800 microg rhGDF-5/g beta-TCP) delivered on beta-TCP (six animals each).

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The two biopolymers Ethisorb and its modification Ethisorb Rapid were implanted in 80 defects of the anterior wall of frontal sinus in 20 Goettingen minipigs to analyze density of trabecula (Mann-Whtiney-Rank-Sum-Test), degradation of biopolymers and histomorphology. To optimate bone regeneration, particular resorbable membranes and autogenic spongiosa chips were used. The animals were killed after six, 12, 26 and 52 weeks and then postoperative undecalcified bone cuts were obtained.

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The goal of this animal study in Goettingen minipigs was to compare Ethisorb with its modification Ethisorb Rapid where the hydrolytic degradation process has started, with respect to degradation and bony substitution qualitites. For comparison, both biopolymers were implanted with and without addition of autogenic spongiosa chips in comparison with blank defects in metaphysis of the tibia. The animals were killed after six, 12, 26 and 52 weeks.

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The flat panel-based volume computed tomography (fpVCT) is a new CT device applicable for experimental, three-dimensional evaluation of teeth at a resolution of about 150 microm in the high contrast region. The aim of this study was to investigate whether fpVCT was suitable for quantification of the volumes of dental hard tissues and the root canal system to establish a new method for morphological studies. Fifty-two extracted third molars (maxillary: 31, mandibular: 21) were examined with a prototype of an fpVCT using a volumetry algorithm at different levels according to the radiographic density of enamel and dentine.

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Frontoorbital advancement has become a standard method both to increase intracranial volume and to improve facial appearance in patients with syndromal or nonsyndromal craniosynostosis. Relevant complications of this procedure include severe hemorrhage and trauma to intracranial, orbital, or facial soft tissues, which mostly arise during the process of bone exposure or osteotomy. To minimize the risk of soft tissue injury and to increase the precision of the osteotomy, the authors applied a piezoelectric osteotome for frontoorbital advancement in 15 patients with craniosynostosis seen consecutively (mean age 11.

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The biocompatible hydroxyapatite cement (HAC) is a welcome alternative to the traditional use of autogenous bone for postoperative corrections of cranial vault irregularities. The authors performed experimental studies to show the safety and osseointegration capacity of HAC on animal models and confirm the osseous replacement without toxic reactions. The purpose of the current study was to analyze the clinical outcome after correction of secondary cranial vault irregularities with HAC.

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Short-chained cyanoacrylates have been used for many years for topical skin closure. Toxic effects in cell culture of a new long-chained octyl-2-cyanoacrylate tissue adhesive are compared with those of short-chained ethyl-2- and butyl-2-cyanoacrylates. Two cellular tests were used: the agar overlay test and the MTT test.

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A new classification system and algorithm of zygomatic arch fractures is described that provides the surgeon with a useful starting point from which to organize a valid treatment plan and management of zygomatic arch fractures. Hönig Merten (HM) class I is defined as an isolated tripod fracture, HM class II as an isolated stick fracture of the arch, and HM class III is a combined fracture of the malar bone and the zygomatic arch. Although reduction of the class I and II is usually closed, open reduction is mandatory in class III zygomatic arch fractures.

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To correct the malocclusion and facial asymmetry in patients with Pruzansky type III hemifacial microsomia after autogenous costochondral grafting during early childhood (two male and three female patients with an average age of 17.8 years), the technique of distraction osteogenesis with a three-dimensional device was used. Because of the missing periosteum of the transplanted rib and its relatively small height compared with the horizontal mandible, a dovetail geometrical pattern osteotomy was introduced to increase the osteotomy surface area, which by itself could enhance the amount of fibrin filaments between 30% and 40% in the hematoma occurring during the initial distraction process.

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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.

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Large mandibular defects caused by trauma, infection or resection of a tumour are still a major problem for plastic and maxillofacial surgeons. The modern concept of tissue engineering combines the osteoinductive effects of osteogenic cells with a suitable scaffold structure to promote differentiation of osteoblasts and optimal matrix production. Critical size mandibular bone defects were therefore made to investigate the osteogenic potential of periosteal cells and a bioabsorbable polymer fleece (Ethisorb 510) in minipigs.

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Aim: In an experimental study the hydroxyapatite cement BoneSource was tested for the ability in relation to the defect size and for its resorption properties.

Material And Methods: In an animal study, BoneSource was applied to repair bicortical defects of different sizes in frontal bones of six Goettingen minipigs. The area was evaluated radiographically and histologically 12, 18 and 40 weeks postoperatively.

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According to the literature, the development of the frontal sinus cavity is a result of the active immigration of cells from the ethmoidal complex into the os frontale. This migration theory is in contrast to the operative outcome of Apert's syndrome patients, after fronto-orbital advancement. When a fronto-orbital advancement at the age of a few months is performed in these patients while the frontal suture is yet closed, a sinus developed even the distance between nasal root and frontal bone bing up to 2 cm.

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Bone distraction is still on the rise again since McCarthy et al. presented in their clinical investigation new osseous formation in the elongated area while performing the distraction of the mandible in 1992. But at the level of craniofacial skeleton, the initial description to the technique of distraction osteogenesis should be credited to the German craniofacial surgeons Rosenthal for the bone lengthening of the mandible in a microgen patient in 1927.

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Bone distraction has been used increasingly since McCarthy and associates showed in their clinical investigation new osseous formation in the elongated area while performing mandibular distraction in 1992. However, at the craniofacial skeletal level, the initial description of the classic technique of distraction osteogenesis should be credited to German craniofacial surgeons Rosenthal (for bone lengthening of the mandible in a microgenia patient around 1927) and Wassmund (for the clinical advancement of a maxilla in a patient with hypoplasia of the upper jaw in 1926). Both procedures are described, and their original schedules and cases are presented.

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