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    Impact of osteotomy angle on bone failure risk in a modified pull-through approach: a finite element analysis
    Background: A modified pull-through approach represents a promising treatment strategy to access tumors in the posterior oral cavity. The design of the wedge osteotomy plays a key role in preserving postoperative mechanical stability while enabling surgical access. However, the optimal osteotomy design to reduce fracture risk remains unclear. Therefore, this study aimed to test osteotomy wedge designs that have the potential to lower the bone fracture risk. Methods: Four wedge osteotomy configurations were compared using finite element analysis based on a realistic mandible model. Each design differed in the angles and curvature of the osteotomy planes. Unilateral molar clenching was simulated, and mechanical strains were quantified and compared to the yield strain of cortical bone in the canine region to evaluate the risk of bone failure. Results: The finite element analysis showed that a wedge osteotomy with less acute angles in the canine region has a lower fracture risk when compared to osteotomies with sharp angles. Peak bone strain values could be reduced by half by changing the osteotomy angle at the canine region. Conclusions: A larger angle between the osteotomy cutting planes offers mechanical advantages by reducing strain concentrations in critical regions. These findings provide valuable guidance for refining the current surgical technique and support the integration of biomechanical analyses into osteotomy planning to optimize surgical outcomes.
    Publicationtype: Journal Article
      20  21
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    Item type:Publication,
    Comparative study of CAD/CAM reconstruction and miniplates for patient-specific fixation in LCL-type mandibular reconstruction
    Objective: Miniplates offer superior clinical handling and facilitate postoperative removal after mandibular reconstruction but unfavorable load distribution under high stress has been shown. This study aimed to compare the clinical outcome of patient-specific 3D-printed (PS-3D) titanium miniplate with reconstruction plate fixation in three-segmental LCL-type reconstructions for the first time. Methods: Patients undergoing three-segmental LCL-type mandibular reconstruction after malignant tumor resection between April 2017 and July 2023 were analyzed in a retrospective single-center study. Inclusion criteria were primary reconstruction using a fibula free flap and PS-3D titanium mini- or reconstruction plate fixation. Complication rates were recorded and analyzed within 6 months after surgery using the N – 1 Chi2- and unequal variance t-test. Results: 38 patients (10 females, 28 males; mean age 61.4 ± 7.6 years) met the inclusion criteria. In 14 patients (36.8%) miniplates were used in the anterior region. Rates of fixation failure, plate exposure, incomplete osseous union, wound infection, soft tissue, and overall complications did not differ significantly between the two plate systems. Conclusion: Complication rates did not differ significantly between PS-3D mini- and reconstruction plates in three-segmental LCL-type mandibular reconstructions. Given their advantages in clinical handling and postoperative removal, PS-3D miniplates can be a viable alternative also in larger mandibular reconstructions.
    Publicationtype: Journal Article
      13
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    Clinical and technical validation of novel bite force measuring device for functional analysis after mandibular reconstruction
    Bite force measuring devices that are generally suitable for edentulous patients or patients undergoing mandibular reconstruction are missing. This study assesses the validity of a new bite force measuring device (prototype of loadpad®, novel GmbH) and evaluates its feasibility in patients after segmental mandibular resection. Accuracy and reproducibility were analyzed with two different protocols using a universal testing machine (Z010 AllroundLine, Zwick/Roell, Ulm, Germany). Four groups were tested to evaluate the impact of silicone layers around the sensor: no silicone (“pure”), 2.0 mm soft silicone (“2-soft”), 7.0 mm soft silicone (“7-soft”) and 2.0 mm hard silicone (“2-hard”). Thereafter, the device was tested in 10 patients prospectively who underwent mandibular reconstruction using a fibula free flap. Average relative deviations of the measured force in relation to the applied load reached 0.77% (“7-soft”) to 5.28% (“2-hard”). Repeated measurements in “2-soft” revealed a mean relative deviation of 2.5% until an applied load of 600 N. Maximum bite force decreased postoperatively by 51.8% to a maximum mean bite force of 131.5 N. The novel device guarantees a high accuracy and degree of reproducibility. Furthermore, it offers new opportunities to quantify perioperative oral function after reconstructive surgery of the mandible also in edentulous patients.
    Publicationtype: Journal Article
      4
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    Item type:Publication,
    Increased rate of pseudarthrosis in the anterior intersegmental gap after mandibular reconstruction with fibula free flaps : a volumetric analysis
    (British Institute of Radiology, 2022-09-01) ; ;
    Sauerbrey, Marius
    ;
    Heintzelmann, Thelma
    ;
    Objectives: Pseudarthrosis after mandibular reconstruction leads to chronic overload of the osteosynthesis and impedes dental rehabilitation. This study evaluates the impact of gap site on osseous union in mandible reconstruction using a new volumetric analysis method with repeated cone-beam computed tomography (CBCT). Methods: The degree of bone regeneration was evaluated in 16 patients after mandible reconstruction with a fibula free flap and patient-specific reconstruction plates. Percentual bone volume and width changes in intersegmental gaps were retrospectively analyzed using a baseline CBCT in comparison to a follow-up CBCT. Patients’ characteristics, plate-related complications, and gap sites (anterior/posterior) were analyzed. Detailed assessments of both gap sites (buccal/lingual/superior/inferior) were additionally performed. Results: Intersegmental gap width (p = 0.002) and site (p < 0.001) significantly influence bone volume change over two consecutive CBCTs. An initial larger gap width resulted in a lower bone volume change. In addition, anterior gaps showed significantly less bone volume changes. Initial gap width was larger at posterior segmental gaps (2.97 vs 1.65 mm, p = 0.017). Conclusions: A methodology framework has been developed that allows to quantify pseuarthrosis in reconstructed mandibles using CBCT imaging. The study identifies the anterior segmental gap as a further risk factor for pseudarthrosis in reconstructions with CAD/CAM reconstruction plates. Future research should evaluate whether this outcome is related to the biomechanics induced at this site. Dentomaxillofacial Radiology (2022) 51, 20220131. doi: 10.1259/dmfr.20220131
    Publicationtype: Journal Article
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