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Biomedical subjects

Constantin A Landes

Publications and source records attributed to Constantin A Landes.

24 records · Page 2Linked to original sources
PubMed2003

Resorbable plate osteosynthesis of dislocated or pathological mandibular fractures: a prospective clinical trial of two amorphous L-/DL-lactide copolymer 2-mm miniplate systems.

The purpose of this study was to evaluate the indication for resorbable miniplates in traumatic and pathological mandibular fractures. Two resorbable miniplate systems, the 2.0-mm MacroSorb (Macropore, San Diego, Calif.) and the PolyMax (Synthes, Oberdorf, Switzerland), were prospectively used in 24 mandibular osteosyntheses. Made from amorphous 70:30 poly-L/DL-lactide, amorphous copolymer plates have not yet been evaluated for mandibular osteosyntheses. The main advantage of the amorphous copolymer-structure is continuous hydrolysis through water penetration into the implant body during the first 6 months. Hydrolysis breaks the copolymer chains into smaller particles that later become degraded through phagocytotic cells. Twelve patients, aged 13 to 83 years, were treated after providing informed consent. Fourteen dentate patients with moderately dislocated traumatic fractures and two edentulous atrophic and dislocated traumatic mandibular fractures were treated. Two patients with pathological fractures due to osteomyelitis received osteosynthesis after sequestrectomy. Histological specimens of the plates, screws, and surrounding soft tissues were taken after 3, 6, 9, and 12 months in secondary dental implant operations. A total of 22 osteosyntheses healed well without clinical or radiological signs of dislocation, insufficient or excess formation of callus, pseudarthrosis, or plate fracture. The follow-up time ranged from 4 to 22 months. One patient with osteomyelitis worsened because of widespread osseous infection, and one with atrophic fracture developed a bland fibrous pseudarthrosis. The histological specimens showed a moderate inflammatory foreign body reaction. No sinuous drainage or clinically apparent inflammation occurred. The presented osteosynthesis systems showed reliable stability for mandibular osteosynthesis in cooperative patients; however, two treatment failures occurred (8 percent). Disadvantages of the resorbable osteosyntheses were costs, greater diameter, screw breakage, and the need to place the screws vertically to the plate. The use of resorbable osteosyntheses in dislocated fractures should be further evaluated in controlled studies.

Absorbable Implants↗
PubMed2003

Nine-year experience with extended use of the commissure-based buccal musculomucosal flap.

This study reports on the extended use of the commissure-based buccal musculomucosal (CBMM) flap. Large lip defects and medium-size intraoral defects have the general problem of being too large for primary closure to avoid a major functional and aesthetic impairment. Elaborate free flaps, such as axial flaps, although excellent in large defects, may not provide mucosa-equivalent sensitivity, motility, volume, and texture to replace lost tissue with a similar kind of tissue. A total of 60 flap procedures were performed with bilateral and unilateral flaps up to 7.5 x 4 cm in size. The partial and total upper and lower vermilion, gingivobuccal sulcus, floor of the mouth, lateral tongue margin, oropharynx, and hard and soft palates were reconstructed. Partial necrosis was seen in four flaps; all patients recovered with good oral function in speech and swallowing, good aesthetics, and prosthetic rehabilitation if necessary. The donor site could be closed primarily. In flaps with dorsal advancement, the mucosal excess above and below was closed, creating two small dog-ears. Facial expression and mouth opening returned to normal after less than 2 months. The parotid duct had to be marsupialized in large flap preparations, but this did never provoke stasis or infection. The two-point sensitivity of the flaps was, on average, equal to that of the nonoperated mucosa in intraindividual correlation, and the flaps lost, on average, 15 percent of their original size. In the authors' estimation, the results indicate a reliable and technically easy option for intraoral, medium-size defect reconstruction that yields sensitivity and facilitates the rehabilitation of oral function in speaking and ingestion.

Adult↗
PubMed2003

Resorbable plate osteosynthesis of sagittal split osteotomies with major bone movement.

This study evaluates resorbable miniplate osteosyntheses in sagittal split osteotomies with major bone repositioning. Two resorbable 2.0-mm miniplate systems, MacroSorb (Macropore, San Diego, Calif.) and PolyMax (Synthes, Oberdorf, Switzerland), were compared consecutively. Amorphous 70:30 poly-L/DL-lactide copolymer plates sustain continuous hydrolysis through water penetration into the implant body during the first 6 months in situ. This breaks copolymer chains into smaller particles, which later become degraded through phagocytotic cells. Eighteen patients, 10 women and eight men, 16 to 57 years old (average, 27 years) were examined. They had severe dysgnathia caused by congenital craniofacial malformations, systemic disorders, trauma, amelogenesis imperfecta, oligodontia, and other conditions, and they needed five 8- to 10-mm and 13 major 10- to 12-mm repositions. Twelve sagittal split osteotomies were fixed with 12 MacroSorb plates in six patients, and 24 osteotomies were filled with 32 PolyMax plates in 12 patients. Ten mandibular plate, screw, hard-tissue, and soft-tissue specimens were taken at 3, 6, 9, or 12 months postoperatively in secondary operations (e.g., dental implant placement).Follow-up ranged from 4 to 19 months; all osteosyntheses reossified. Four patients showed proximal fragments rotated up to 5 mm sagittally anteriorly and nonaligned burr holes on the postoperative radiogram, suggesting plate fractures or screw pullout. When plate fracture was noted, guided occlusion was maintained 4 weeks after surgery. Occlusal, radiologic, and skeletal results remained stable. After starting fixation with two plates on each side, no more plate fractures were seen. In three other patients, minor skeletal relapses up to 3 mm horizontally resulted. Local histologic inspection of specimens showed thorough osseous union. Screw remnants embedded in bone made screw pullout unlikely; rather, screw-head or plate fractures were found as multiple degraded particles. Microscopy showed a chronic foreign body reaction. Two patients (11 percent) developed a sterile fistula 3 and 4 months after surgery, draining implant debris. Here, the biopsies showed a granulocytic infiltrate that subsided clinically after excisional biopsy. The assignment of MacroSorb plates followed by PolyMax plates was done in an otherwise unchanged treatment protocol. Comparison of the number of patients in each group with stable osteosyntheses and regular healing showed no significant differences by Fisher's exact test (p = 0.1516); therefore, the authors focused on the combined results for both treatments. The current osteosynthesis systems showed sufficient stability for mandibular fixation after sagittal split osteotomy and repositioning more than 10 mm distant when two plates were applied to each side; however, 27 percent of patients had complications, including relapses. Disadvantages were the cost, breakability, diameter, and need to place the screws vertically to the plate, necessitating a bent instrument or transbuccal incisions.

Absorbable Implants↗
PubMed2002

Introduction of a three-dimensional anthropometry of the viscerocranium. Part I: measurement of craniofacial development and establishment of standard values and growth functions.

BACKGROUND AND OBJECTIVE: The analysis of lateral cephalograms is based on many vague landmarks that vary intra- and inter-individually. Exposure to radiation and high-quality equipment are essential, while identical object positioning is almost impossible. Anthropometry as presented in the literature is time consuming and cannot reproduce cranial three-dimensionality. Poor landmark definitions and resilience of the soft tissue foster systematic measurement errors. We used few easily detectable and accessible landmarks that are closely related to underlying bone. The distances measured were visualized three-dimensionally. MATERIAL AND METHODS: Measurements from 540 volunteers were reconstructed. Reliability was assessed through repeated measurements. Corresponding distances were measured in lateral cephalograms taken the same day. RESULTS: The age- and sex-related mean values and 95%-percentiles were visualized as growth functions. The intra-individual relative error in anthropometry was 3.7%, in roentgenocephalometry 0.9%. The inter-individual error was 5.8% for anthropometry and 3.6% for roentgenocephalometry. CONCLUSION: Applied anthropometry as described in the paper is reliable and valid for measuring craniofacial growth, arriving at a diagnosis and 'monitoring' treatment results. The relative measurement error in anthropometry appear to be smaller than the systematic magnification and distortion found in lateral cephalograms.

Adolescent↗
PubMed2002

Introduction of a three-dimensional anthropometry of the viscerocranium. Part II: evaluating osseous and soft tissue changes following orthognathic surgery.

BACKGROUND AND OBJECTIVE: Anthropometric measurements, described and assessed in Part I of this article were applied in dysgnathic patients. Diagnosis, surgical planning and follow-up were performed and soft tissue ratios quantified. MATERIAL AND METHODS: One hundred and seventy-five anthropometric measurements and 146 cephalograms of 100 patients were included. Forty-five patients were analysed before and after surgery. Ten randomly selected patients were re-measured directly by two investigators for reliability and validity assessment. RESULTS: Manoeuvres that expanded the facial skeleton such as maxillary or mandibular advancements or maxillary elongations generally had a greater soft tissue impact than setbacks or maxillary impactions. A 1.4% intra-observer and a 2.6% inter-observer error was apparent with anthropometry. Concordance of anthropometry with roentgenocephalometry (p<0.04) was found by paired t -test. CONCLUSION: The anthropometry allowed reliable and objective, independent calculation of cranial bone relations and soft tissue projection. It is also sensitive to facial asymmetry. Easy application, versatility and an economic price for the assessment of facial proportions, soft tissue ratios, operation planning and follow-up were obvious.

Adult↗