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14 pages, 1857 KiB

Open AccessArticle

Fractal Dimension and Texture Analysis in the Assessment of Experimental Laser-Induced Periodic Surface Structures (LIPSS) Dental Implant Surface—In Vitro Study Preliminary Report

by Jakub Hadzik, Paweł Kubasiewicz-Ross, Wojciech Simka, Tomasz Gębarowski, Ewa Barg, Aneta Cieśla-Niechwiadowicz, Anna Trzcionka Szajna, Ernest Szajna, Tomasz Gedrange, Marcin Kozakiewicz, Marzena Dominiak and Kamil Jurczyszyn

Materials 2022, 15(8), 2713; https://doi.org/10.3390/ma15082713 - 7 Apr 2022

Cited by 14 | Viewed by 2646

Abstract

Laser-induced periodic surface structures (LIPSS) are the sub-wavelength periodic nanostructures generated by the femtosecond laser. Implant topography and its nanostructural changes can be important for biomedical applications. In order to compare the surface topography of different implants, appropriate mathematical and physical descriptive methods [...] Read more.

Laser-induced periodic surface structures (LIPSS) are the sub-wavelength periodic nanostructures generated by the femtosecond laser. Implant topography and its nanostructural changes can be important for biomedical applications. In order to compare the surface topography of different implants, appropriate mathematical and physical descriptive methods should be provided. The aim of the study was to evaluate the experimental LIPSS-based—Low Spatial Frequency LIPSS (LSFL) dental implant surfaces. Novel methods of surface analysis, such as Fractal Dimension Analysis and Texture Analysis, were compared to the standard surface roughness evaluation. Secondary, cell viability, and attachment tests were applied in order to evaluate the biological properties of the new titanium surface and to compare their correlation with the physical properties of the new surfaces. A Normal Human Dermal Fibroblast (NHDF) cytotoxicity test did not show an impact on the vitality of the cells. Our study has shown that the laser LIPSS implant surface modifications significantly improved the cell adhesion to the tested surfaces. We observed a strong correlation of adhesion and the growth of cells on the tested surface, with an increase in implant surface roughness with the best results for the moderately rough (2 μm) surfaces. Texture and fractal dimension analyses are promising methods to evaluate dental implants with complex geometry. Full article

(This article belongs to the Special Issue Numerical and Biomechanical Analysis in Bioengineering)

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14 pages, 1628 KiB

Open AccessArticle

Bone Union Quality after Fracture Fixation of Mandibular Head with Compression Magnesium Screws

by Marcin Kozakiewicz and Izabela Gabryelczak

Materials 2022, 15(6), 2230; https://doi.org/10.3390/ma15062230 - 17 Mar 2022

Cited by 11 | Viewed by 2150

Abstract

For some years now, fixation devices created with resorbable magnesium alloys for the mandibular head have been clinically available and are beginning to be used. It is thus valuable to evaluate the quality of unions in these cases. The aim of this study [...] Read more.

For some years now, fixation devices created with resorbable magnesium alloys for the mandibular head have been clinically available and are beginning to be used. It is thus valuable to evaluate the quality of unions in these cases. The aim of this study was radiological comparison of magnesium versus titanium open reduction and rigid fixations in the mandible condylar head. Thirty-one patients were treated for fractures of the mandibular head with magnesium WE43 alloy headless compression screws (diameter 2.3 mm) and, as a reference group, 29 patients were included with similar construction titanium screws (diameter 1.8 mm). The 12-month results of the treatment were evaluated by the texture analysis of CT. Near similar treatment results were found with magnesium screws in traditional titanium fixation. Magnesium screws result in a higher density of the bone structure in the mandibular head. Conclusions: The quantitative evaluation of bone union after surgical treatment of mandibular head fracture with magnesium compression headless screws indicates that stable consolidation was achieved. Undoubtedly, the resorption process of the screws was found to be incomplete after 12 months, evidenced by a marked densification of the bone structure at the fracture site. Full article

(This article belongs to the Special Issue Numerical and Biomechanical Analysis in Bioengineering)

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11 pages, 2136 KiB

Open AccessArticle

Surface Evaluation of Orthodontic Brackets Using Texture and Fractal Dimension Analysis

by Michał Sarul, Marcin Mikulewicz, Marcin Kozakiewicz and Kamil Jurczyszyn

Materials 2022, 15(6), 2071; https://doi.org/10.3390/ma15062071 - 11 Mar 2022

Cited by 6 | Viewed by 2279

Abstract

The surface topography of orthodontic brackets can have a significant impact on both the effectiveness of the therapy and the behavior of these elements in the oral cavity environment. In this situation, striving to obtain the most uniform, smooth surface in a repeatable [...] Read more.

The surface topography of orthodontic brackets can have a significant impact on both the effectiveness of the therapy and the behavior of these elements in the oral cavity environment. In this situation, striving to obtain the most uniform, smooth surface in a repeatable manner for each manufactured element should be a sine qua non condition for each supplier of orthodontic brackets. Therefore, it is necessary to analyze the surfaces of orthodontic brackets using different methods. One of them—that is relatively simple and repeatable—is the analysis of the fractal dimension and the analysis of the textures of the optical images on the surface. In the presented study, fractal dimension analysis and texture analysis were performed by selecting four brackets from three different manufacturers (Mini Sprint, Sprint, Nu-Edge, Orthos SS). The area of each bracket slot was analyzed at six predefined points. The smoothest and most uniform and reproducible surface structure was shown by the Mini Sprint bracket. On the other hand, Sprint brackets showed the least homogeneous and least repeatable surface structure. Full article

(This article belongs to the Special Issue Numerical and Biomechanical Analysis in Bioengineering)

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18 pages, 3051 KiB

Open AccessArticle

Clinical Evaluation of Magnesium Alloy Osteosynthesis in the Mandibular Head

by Marcin Kozakiewicz, Izabela Gabryelczak and Bartosz Bielecki-Kowalski

Materials 2022, 15(3), 711; https://doi.org/10.3390/ma15030711 - 18 Jan 2022

Cited by 12 | Viewed by 2310

Abstract

Titanium alloys are used in skeletal surgery. However, once bone union is complete, such fixation material becomes unnecessary or even harmful. Resorbable magnesium materials have been available for several years (WE43 alloy). The aim of this study was to clinically compare magnesium versus [...] Read more.

Titanium alloys are used in skeletal surgery. However, once bone union is complete, such fixation material becomes unnecessary or even harmful. Resorbable magnesium materials have been available for several years (WE43 alloy). The aim of this study was to clinically compare magnesium versus titanium open reduction and rigid fixations in mandible condylar heads. Ten patients were treated for fractures of the mandibular head with magnesium headless compression screws (2.3 mm in diameter), and 11 patients were included as a reference group with titanium screws (1.8 mm in diameter) with similar construction. The fixation characteristics (delay, time, and number of screws), distant anatomical results (mandibular ramus height loss, monthly loss rate, and relative loss of reconstructed ramus height), basic functional data (mandibular movements, facial nerve function, and cutaneous perception) and the influence of the effects of the injury (fracture type, fragmentation, occlusion, additional fractures, and associated diseases) on the outcome were evaluated. The long-term results of treatment were evaluated after 18 months. Treatment results similar to those of traditional titanium fixation were found with magnesium screws. Conclusions: Resorbable metal screws can be a favored option for osteosynthesis because surgical reentry can be avoided. These materials provide proper and stable treatment results. Full article

(This article belongs to the Special Issue Numerical and Biomechanical Analysis in Bioengineering)

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12 pages, 4715 KiB

Open AccessArticle

Biomechanical Analyses of Porous Designs of 3D-Printed Titanium Implant for Mandibular Segmental Osteotomy Defects

by Yen-Wen Shen, Yuen-Shan Tsai, Jui-Ting Hsu, Ming-You Shie, Heng-Li Huang and Lih-Jyh Fuh

Materials 2022, 15(2), 576; https://doi.org/10.3390/ma15020576 - 13 Jan 2022

Cited by 11 | Viewed by 3779

Abstract

Clinically, a reconstruction plate can be used for the facial repair of patients with mandibular segmental defects, but it cannot restore their chewing function. The main purpose of this research is to design a new three-dimensionally (3D) printed porous titanium mandibular implant with [...] Read more.

Clinically, a reconstruction plate can be used for the facial repair of patients with mandibular segmental defects, but it cannot restore their chewing function. The main purpose of this research is to design a new three-dimensionally (3D) printed porous titanium mandibular implant with both facial restoration and oral chewing function reconstruction. Its biomechanical properties were examined using both finite element analysis (FEA) and in vitro experiments. Cone beam computed tomography images of the mandible of a patient with oral cancer were selected as a reference to create 3D computational models of the bone and of the 3D-printed porous implant. The pores of the porous implant were circles or hexagons of 1 or 2 mm in size. A nonporous implant was fabricated as a control model. For the FEA, two chewing modes, namely right unilateral molar clench and right group function, were set as loading conditions. Regarding the boundary condition, the displacement of both condyles was fixed in all directions. For the in vitro experiments, an occlusal force (100 N) was applied to the abutment of the 3D-printed mandibular implants with and without porous designs as the loading condition. The porous mandibular implants withstood higher stress and strain than the nonporous mandibular implant, but all stress values were lower than the yield strength of Ti-6Al-4V (800 MPa). The strain value of the bone surrounding the mandibular implant was affected not only by the shape and size of the pores but also by the chewing mode. According to Frost’s mechanostat theory of bone, higher bone strain under the porous implants might help maintain or improve bone quality and bone strength. The findings of this study serve as a biomechanical reference for the design of 3D-printed titanium mandibular implants and require confirmation through clinical investigations. Full article

(This article belongs to the Special Issue Numerical and Biomechanical Analysis in Bioengineering)

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16 pages, 42048 KiB

Open AccessArticle

Application of Texture and Fractal Dimension Analysis to Evaluate Subgingival Cement Surfaces in Terms of Biocompatibility

by Katarzyna Skośkiewicz-Malinowska, Martyna Mysior, Agnieszka Rusak, Piotr Kuropka, Marcin Kozakiewicz and Kamil Jurczyszyn

Materials 2021, 14(19), 5857; https://doi.org/10.3390/ma14195857 - 7 Oct 2021

Cited by 16 | Viewed by 2450

Abstract

Biocompatibility is defined as “the ability of a biomaterial, prosthesis, or medical device to perform with an appropriate host response in a specific application”. Biocompatibility is especially important for restorative dentists as they use materials that remain in close contact with living tissues [...] Read more.

Biocompatibility is defined as “the ability of a biomaterial, prosthesis, or medical device to perform with an appropriate host response in a specific application”. Biocompatibility is especially important for restorative dentists as they use materials that remain in close contact with living tissues for a long time. The research material involves six types of cement used frequently in the subgingival region: Ketac Fil Plus (3M ESPE, Germany), Riva Self Cure (SDI, Australia) (Glass Ionomer Cements), Breeze (Pentron Clinical, USA) (Resin-based Cement), Adhesor Carbofine (Pentron, Czech Republic), Harvard Polycarboxylat Cement (Harvard Dental, Great Britain) (Zinc polycarboxylate types of cement) and Agatos S (Chema-Elektromet, Poland) (Zinc Phosphate Cement). Texture and fractal dimension analysis was applied. An evaluation of cytotoxicity and cell adhesion was carried out. The fractal dimension of Breeze (Pentron Clinical, USA) differed in each of the tested types of cement. Adhesor Carbofine (Pentron, Czech Republic) cytotoxicity was rated 4 on a 0–4 scale. The Ketac Fil Plus (3M ESPE, Germany) and Riva Self Cure (SDI, Australia) cements showed the most favorable conditions for the adhesion of fibroblasts, despite statistically significant differences in the fractal dimension of their surfaces. Full article

(This article belongs to the Special Issue Numerical and Biomechanical Analysis in Bioengineering)

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23 pages, 4309 KiB

Open AccessArticle

Fractal Dimension and Texture Analysis of Lesion Autofluorescence in the Evaluation of Oral Lichen Planus Treatment Effectiveness

by Kamil Jurczyszyn, Witold Trzeciakowski, Marcin Kozakiewicz, Dorota Kida, Katarzyna Malec, Bożena Karolewicz, Tomasz Konopka and Jacek Zborowski

Materials 2021, 14(18), 5448; https://doi.org/10.3390/ma14185448 - 21 Sep 2021

Cited by 7 | Viewed by 2560

Abstract

Background: Oral Lichen planus (OLP) is a chronic inflammatory disease. Topical steroids are used as the treatment of choice. The alternative is photodynamic therapy (PDT). The study aimed to fabricate optimal biodegradable matrices for methylene blue or triamcinolone acetonide because of a lack [...] Read more.

Background: Oral Lichen planus (OLP) is a chronic inflammatory disease. Topical steroids are used as the treatment of choice. The alternative is photodynamic therapy (PDT). The study aimed to fabricate optimal biodegradable matrices for methylene blue or triamcinolone acetonide because of a lack of currently commercially available carriers that could adhere to the mucous. Methods: The study was designed as a 12-week single-blind prospective randomized clinical trial with 30 patients, full contralateral split-mouth design. Matrices for steroid and photosensitizer and laser device were fabricated. Fractal and texture analysis of photographs, taken in 405, 450, 405 + 450 nm wavelength, of lesions was performed to increase the objectivity of the assessment of treatment. Results: We achieved two total responses for treatment in case of steroid therapy and one in the case of PDT. Partial response was noted in 17 lesions treated using local steroid therapy and 21 in the case of PDT. No statistically significant differences were found between the effectiveness of both used methods. Statistically significant differences in fractal dimension before and after treatment were observed only in the analysis of photographs taken in 405 + 450 nm wavelength. Conclusions: Photodynamic therapy and topical steroid therapy are effective methods for treating OLP. Using a carrier offers the possibility of a more predictable and effective method of drug delivery into the mucous membrane. Autofluorescence enables the detection of lesions especially at the early stage of their development. Full article

(This article belongs to the Special Issue Numerical and Biomechanical Analysis in Bioengineering)

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29 pages, 12132 KiB

Open AccessArticle

Printable and Machinable Dental Restorative Composites for CAD/CAM Application—Comparison of Mechanical Properties, Fractographic, Texture and Fractal Dimension Analysis

by Wojciech Grzebieluch, Piotr Kowalewski, Dominika Grygier, Małgorzata Rutkowska-Gorczyca, Marcin Kozakiewicz and Kamil Jurczyszyn

Materials 2021, 14(17), 4919; https://doi.org/10.3390/ma14174919 - 29 Aug 2021

Cited by 65 | Viewed by 4563

Abstract

Thanks to the continuous development of light-curing resin composites it is now possible to print permanent single-tooth restorations. The purpose of this study was to compare resin composites for milling -Gandio Blocks (GR), Brilliant Crios (CR) and Enamic (EN) with resin composite for [...] Read more.

Thanks to the continuous development of light-curing resin composites it is now possible to print permanent single-tooth restorations. The purpose of this study was to compare resin composites for milling -Gandio Blocks (GR), Brilliant Crios (CR) and Enamic (EN) with resin composite for 3D printing—Varseo Smile Crown plus (VSC). Three-point bending was used to measure flexural strength (σ_f) and flexural modulus (E_f). The microhardness was measured using a Vickers method, while fractographic, microstructural, texture and fractal dimension (FD) analyses were performed using SEM, optical microscope and picture analysis methods. The values of σ_f ranged from 118.96 (±2.81) MPa for EN to 186.02 (±10.49) MPa for GR, and the values of E_f ranged from 4.37 (±0.8) GPa for VSC to 28.55 (±0.34) GPa for EN. HV01 ranged from 25.8 (±0.7) for VSC to 273.42 (±27.11) for EN. The filler content ranged from 19–24 vol. % for VSC to 70–80 vol. % for GR and EN. The observed fractures are typical for brittle materials. The correlation between FD of materials microstructure and E_f was observed. σ_f of the printed resin depends on layers orientation and is significantly lower than σ_f of GR and CR. E_f of the printed material is significantly lower than E_f of blocks for milling. Full article

(This article belongs to the Special Issue Numerical and Biomechanical Analysis in Bioengineering)

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10 pages, 2608 KiB

Open AccessArticle

Development of Custom Anatomic Healing Abutment Based on Cone-Beam Computer Tomography Measurement on Human Teeth Cross-Section

by Monika Teślak, Adam Ziemlewski, Igor Foltyn, Iwona Ordyniec-Kwaśnica and Barbara Drogoszewska

Materials 2021, 14(16), 4570; https://doi.org/10.3390/ma14164570 - 14 Aug 2021

Cited by 9 | Viewed by 3149

Abstract

Introduction: Nowadays, the final success of implantation is not only based on obtaining osseointegration of the implant but is also determined by achieving a satisfactory aesthetic effect of the soft tissues surrounding the implant, which can be defined as an aesthetic integration. The [...] Read more.

Introduction: Nowadays, the final success of implantation is not only based on obtaining osseointegration of the implant but is also determined by achieving a satisfactory aesthetic effect of the soft tissues surrounding the implant, which can be defined as an aesthetic integration. The process of obtaining this aesthetic integration already begins at the stage of placing the healing abutment, which allows us to obtain the emergence profile necessary for our prosthetic reconstruction. Materials and Methods: The study used cone-beam computer tomography (CBCT) scans of 51 patients. The measurements of the maxillary teeth (central incisor, lateral incisor, canine, first premolar, and first molar) were performed from cross-sections of the individual teeth at the transition zone to design a custom anatomic healing abutment milled from zirconium and luted to the non-index Ti-base. Results: The obtained results allowed to design and create the shape of the anatomic healing abutment. Conclusions: The use of laboratory-produced anatomical healing abutments is possible and may allow to obtain the desired and planned emergence profiles of prosthetic restorations. In addition, it might be a method of reducing work time at the dental chair but further clinical trials are necessary. Full article

(This article belongs to the Special Issue Numerical and Biomechanical Analysis in Bioengineering)

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13 pages, 1748 KiB

Open AccessArticle

Application of Fractal Dimension and Texture Analysis to Evaluate the Effectiveness of Treatment of a Venous Lake in the Oral Mucosa Using a 980 nm Diode Laser—A Preliminary Study

by Mateusz Trafalski, Marcin Kozakiewicz and Kamil Jurczyszyn

Materials 2021, 14(15), 4140; https://doi.org/10.3390/ma14154140 - 25 Jul 2021

Cited by 10 | Viewed by 3069

Abstract

Venous lake (VL) is a common lesion resulting from the enlargement of thin-walled veins surrounded by a thick wall of fibrous tissue. Photocoagulation is becoming one of the basic methods for treating small vascular lesions. The aim of this study was an application [...] Read more.

Venous lake (VL) is a common lesion resulting from the enlargement of thin-walled veins surrounded by a thick wall of fibrous tissue. Photocoagulation is becoming one of the basic methods for treating small vascular lesions. The aim of this study was an application of texture analysis (TA) and fractal dimension analysis (FDA) to evaluate VL treatment. Twenty-three VLs were included in the study. We used a 980 nm diode laser, 6 W, 100 ms pulse mode with a 50% duty cycle. The total dose of energy was in a range from 80 J to 600 J. We used the difference of intensity algorithm for FDA and microcontrast and a co-occurrence matrix for TA. A complete therapeutic effect was achieved in 83%, and in 9%, scar formation was observed after three months. No healing was observed in 4%, and there was partial healing in 4%. No differences in FD were observed between the lesions after three months and the healthy mucosa. The fractal dimension and microcontrast of a vascular lesion are mutually coupled. FDA and TA is a useful and objective method of assessing treatment effects for venous lakes. The non-contact mode of the 980 nm diode laser is an effective and safe method for treating a VL. Full article

(This article belongs to the Special Issue Numerical and Biomechanical Analysis in Bioengineering)

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13 pages, 22180 KiB

Open AccessArticle

Surface Evaluation of Orthodontic Wires Using Texture and Fractal Dimension Analysis

by Michał Sarul, Marcin Kozakiewicz and Kamil Jurczyszyn

Materials 2021, 14(13), 3688; https://doi.org/10.3390/ma14133688 - 1 Jul 2021

Cited by 8 | Viewed by 2567

Abstract

Mechanical properties of orthodontic wires can have a very significant impact both on the resistance of the entire appliance to the oral cavity conditions and directly on the effectiveness of the therapy. Striving to achieve repeatability of mechanical characteristics of orthodontic wires of [...] Read more.

Mechanical properties of orthodontic wires can have a very significant impact both on the resistance of the entire appliance to the oral cavity conditions and directly on the effectiveness of the therapy. Striving to achieve repeatability of mechanical characteristics of orthodontic wires of a given type should be an obligatory condition in their production. To achieve it, these components should be thoroughly analyzed using various mechanical tests. Twenty-four steel and nickel-titanium orthodontic wires from four different manufacturers were examined. Each wire was subjected to fractal dimension analysis and texture analysis. The two sides of each wire were compared against each other, as well as in terms of variation in the surface area for each wire type made by different manufacturers. Most wires showed significant variation in fractal dimension and texture, both when comparing two sides of the same wire and between individual wires of a given type made by a single manufacturer. When conducting research and clinically using orthodontic wires made of Ni-Ti alloys and stainless steel, it should be assumed that the surface of orthodontic wires shows a significant degree of variation, and wires of the same type from the same manufacturer may differ significantly in this respect. Full article

(This article belongs to the Special Issue Numerical and Biomechanical Analysis in Bioengineering)

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10 pages, 2275 KiB

Open AccessArticle

Assessment of Differences in the Dimensions of Mandible Condyle Models in Fan- versus Cone-Beam Computer Tomography Acquisition

by Bartosz Bielecki-Kowalski and Marcin Kozakiewicz

Materials 2021, 14(6), 1388; https://doi.org/10.3390/ma14061388 - 12 Mar 2021

Cited by 1 | Viewed by 1737

Abstract

Modern treatment in the field of head and neck surgery aims for the least invasive therapy and places great emphasis on restorative treatment, especially in the case of injury and deformation corrective surgery. More and more often, surgeons use CAD/CAM (Computer-Aided Design and [...] Read more.

Modern treatment in the field of head and neck surgery aims for the least invasive therapy and places great emphasis on restorative treatment, especially in the case of injury and deformation corrective surgery. More and more often, surgeons use CAD/CAM (Computer-Aided Design and Computer-Aided Manufacturing) tools in their daily practice in the form of models, templates, and computer simulations of planning. These tools are based on DICOM (Digital Imaging and Communications in Medicine) files derived from computed tomography. They can be obtained from both fan-beam (FBCT) and cone-beam tomography (CBCT) acquisitions, which are subsequently segmented in order to transform them into a 1-bit 3D model, which is the basis for further CAD processes. Aim: Evaluation of differences in the dimensions of mandible condyle models in fan- versus cone-beam computer tomography for surgical treatment purposes. Methods: 499 healthy condyles were examined in CT-based 3D models of Caucasians aged 8–88 years old. Datasets were obtained from 66 CBCT and 184 FBCT axial image series (in each case, imaging both mandible condyles resulted in the acquisition of 132 condyles from CBCT and 368 condyles from FBCT) and were transformed into three-dimensional models by digital segmentation. Eleven different measurements were performed to obtain information whether there were any differences between FBCT and CBCT models of the same anatomical region. Results: 7 of 11 dimensions were significantly higher in FBCT versus lower in CBCT (p < 0.05). Full article

(This article belongs to the Special Issue Numerical and Biomechanical Analysis in Bioengineering)

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17 pages, 4330 KiB

Open AccessArticle

Comparison of Tooth- and Bone-Borne Appliances on the Stress Distributions and Displacement Patterns in the Facial Skeleton in Surgically Assisted Rapid Maxillary Expansion—A Finite Element Analysis (FEA) Study

by Rafał Nowak, Anna Olejnik, Hanna Gerber, Roman Frątczak and Ewa Zawiślak

Materials 2021, 14(5), 1152; https://doi.org/10.3390/ma14051152 - 1 Mar 2021

Cited by 9 | Viewed by 2601

Abstract

The aim of this study was to compare the reduced stresses according to Huber’s hypothesis and the displacement pattern in the region of the facial skeleton using a tooth- or bone-borne appliance in surgically assisted rapid maxillary expansion (SARME). In the current literature, [...] Read more.

The aim of this study was to compare the reduced stresses according to Huber’s hypothesis and the displacement pattern in the region of the facial skeleton using a tooth- or bone-borne appliance in surgically assisted rapid maxillary expansion (SARME). In the current literature, the lack of updated reports about biomechanical effects in bone-borne appliances used in SARME is noticeable. Finite element analysis (FEA) was used for this study. Six facial skeleton models were created, five with various variants of osteotomy and one without osteotomy. Two different appliances for maxillary expansion were used for each model. The three-dimensional (3D) model of the facial skeleton was created on the basis of spiral computed tomography (CT) scans of a 32-year-old patient with maxillary constriction. The finite element model was built using ANSYS 15.0 software, in which the computations were carried out. Stress distributions and displacement values along the 3D axes were found for each osteotomy variant with the expansion of the tooth- and the bone-borne devices at a level of 0.5 mm. The investigation showed that in the case of a full osteotomy of the maxilla, as described by Bell and Epker in 1976, the method of fixing the appliance for maxillary expansion had no impact on the distribution of the reduced stresses according to Huber’s hypothesis in the facial skeleton. In the case of the bone-borne appliance, the load on the teeth, which may lead to periodontal and orthodontic complications, was eliminated. In the case of a full osteotomy of the maxilla, displacements in the buccolingual direction for all the variables of the bone-borne appliance were slightly bigger than for the tooth-borne appliance. Full article

(This article belongs to the Special Issue Numerical and Biomechanical Analysis in Bioengineering)

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20 pages, 7534 KiB

Open AccessArticle

Custom-Made Zirconium Dioxide Implants for Craniofacial Bone Reconstruction

by Marcin Kozakiewicz, Tomasz Gmyrek, Radosław Zajdel and Bartłomiej Konieczny

Materials 2021, 14(4), 840; https://doi.org/10.3390/ma14040840 - 10 Feb 2021

Cited by 8 | Viewed by 2591

Abstract

Reconstruction of the facial skeleton is challenging for surgeons because of difficulties in proper shape restoration and maintenance of the proper long-term effect. ZrO₂ implant application can be a solution with many advantages (e.g., osseointegration, stability, and radio-opaqueness) and lacks the disadvantages [...] Read more.

Reconstruction of the facial skeleton is challenging for surgeons because of difficulties in proper shape restoration and maintenance of the proper long-term effect. ZrO₂ implant application can be a solution with many advantages (e.g., osseointegration, stability, and radio-opaqueness) and lacks the disadvantages of other biomaterials (e.g., metalosis, radiotransparency, and no osseointegration) or autologous bone (e.g., morbidity, resorption, and low accuracy). We aimed to evaluate the possibility of using ZrO₂ implants as a new application of this material for craniofacial bone defect reconstruction. First, osteoblast (skeleton-related cell) cytotoxicity and genotoxicity were determined in vitro by comparing ZrO₂ implants and alumina particle air-abraded ZrO₂ implants to the following: 1. a titanium alloy (standard material); 2. ultrahigh-molecular-weight polyethylene (a modern material used in orbital surgery); 3. a negative control (minimally cytotoxic or genotoxic agent action); 4. a positive control (maximally cytotoxic or genotoxic agent action). Next, 14 custom in vivo clinical ZrO₂ implants were manufactured for post-traumatologic periorbital region reconstruction. The soft tissue position improvement in photogrammetry was recorded, and clinical follow-up was conducted at least 6 years postoperatively. All the investigated materials revealed no cytotoxicity. Alumina particle air-abraded ZrO2 implants showed genotoxicity compared to those without subjection to air abrasion ZrO₂, which were not genotoxic. The 6-month and 6- to 8-year clinical results were aesthetic and stable. Skeleton reconstructions using osseointegrated, radio-opaque, personalized implants comprising ZrO₂ material are the next option for craniofacial surgery. Full article

(This article belongs to the Special Issue Numerical and Biomechanical Analysis in Bioengineering)

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10 pages, 1093 KiB

Open AccessArticle

Change in Pull-Out Force during Resorption of Magnesium Compression Screws for Osteosynthesis of Mandibular Condylar Fractures

by Marcin Kozakiewicz

Materials 2021, 14(2), 237; https://doi.org/10.3390/ma14020237 - 6 Jan 2021

Cited by 7 | Viewed by 3327

Abstract

Background: Magnesium has been used as degradable fixation material for osteosynthesis, but it seems that mechanical strength is still a current issue in these fixations. The aim of this study was to evaluate the axial pull-out force of compression headless screws made of [...] Read more.

Background: Magnesium has been used as degradable fixation material for osteosynthesis, but it seems that mechanical strength is still a current issue in these fixations. The aim of this study was to evaluate the axial pull-out force of compression headless screws made of magnesium alloy during their resorption. Methods: The tests included screws made for osteosynthesis of the mandible head: 2.2 mm diameter magnesium alloy MgYREZr (42 screws) and 2.5 mm diameter polylactic-co-glycolic acid (PLGA) (42 pieces, control). The screws were resorbed in Sørensen’s buffer for 2, 4, 8, 12, and 16 weeks, and force was measured as the screw was pulled out from the polyurethane block. Results: The force needed to pull the screw out was significantly higher for MgYREZr screws than for PLGA ones (p < 0.01). Within eight weeks, the pull-out force for MgYREZr significantly decreased to one third of its initial value (p < 0.01). The dynamics of this decrease were greater than those of the pull-out force for PLGA screws (p < 0.05). After these eight weeks, the values for metal and polymer screws equalized. It seems that the described reduction of force requires taking into account when using magnesium screws. This will provide more stable resorbable metallic osteosynthesis. Full article

(This article belongs to the Special Issue Numerical and Biomechanical Analysis in Bioengineering)

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17 pages, 2914 KiB

Open AccessArticle

Mechanical Assessment and Hyperelastic Modeling of Polyurethanes for the Early Stages of Vascular Graft Design

by Arévalo-Alquichire Said, Dominguez-paz Carlos and Valero Manuel F.

Materials 2020, 13(21), 4973; https://doi.org/10.3390/ma13214973 - 5 Nov 2020

Cited by 7 | Viewed by 2999

Abstract

The material design of vascular grafts is required for their application in the health sector. The use of polyurethanes (PUs) in vascular grafts intended for application in the body appears to be adequate due to the fact that native tissues have similar properties [...] Read more.

The material design of vascular grafts is required for their application in the health sector. The use of polyurethanes (PUs) in vascular grafts intended for application in the body appears to be adequate due to the fact that native tissues have similar properties as PUs. However, the influence of chemical structure on the biomechanics of PUs remains poorly described. The use of constitutive models, together with numerical studies, is a powerful tool for evaluating the mechanical behavior of materials under specific physiological conditions. Therefore, the aim of this study was to assess the mechanical properties of different PU mixtures formed by polycaprolactone diol, polyethylene glycol, and pentaerythritol using uniaxial tensile, strain sweep, and multistep creep-recovery tests. Evaluations of the properties were also recorded after samples had been soaked in phosphate-buffer saline (PBS) to simulate physiological conditions. A hyperelastic model based on the Mooney–Rivlin strain density function was employed to model the performance of PUs under physiological pressure and geometry conditions. The results show that the inclusion of polyethylene glycol enhanced viscous flow, while polycaprolactone diol increased the elastic behavior. Furthermore, tensile tests revealed that hydration had an important effect on the softening phenomenon. Additionally, after the hydration of PUs, the ultimate strength was similar to those reported for other vascular conduits. Lastly, hyperelastic models revealed that the compliance of the PUs showed a cyclic behavior within the tested time and pressure conditions and is affected by the material composition. However, the compliance was not affected by the geometry of the materials. These tests demonstrate that the materials whose compositions are 5–90–5 and 46.3–46.3–7.5 could be employed in the designs of vascular grafts for medical applications since they present the largest value of compliance, ultimate strength, and elongation at break in the range of reported blood vessels, thus indicating their suitability. Moreover, the polyurethanes were revealed to undergo softening after hydration, which could reduce the risk of vascular trauma. Full article

(This article belongs to the Special Issue Numerical and Biomechanical Analysis in Bioengineering)

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11 pages, 1744 KiB

Open AccessArticle

Fast-Versus Slow-Resorbable Calcium Phosphate Bone Substitute Materials—Texture Analysis after 12 Months of Observation

by Tomasz Wach and Marcin Kozakiewicz

Materials 2020, 13(17), 3854; https://doi.org/10.3390/ma13173854 - 1 Sep 2020

Cited by 14 | Viewed by 2912

Abstract

The development of oral surgery and implantology has led to the need for better and more predictable materials. Various substitute materials are now used for bone regeneration. The replacement of scaffolding material by new bone tissue is the most important condition. This study [...] Read more.

The development of oral surgery and implantology has led to the need for better and more predictable materials. Various substitute materials are now used for bone regeneration. The replacement of scaffolding material by new bone tissue is the most important condition. This study aimed to evaluate the effects of the resorbability of bone substitute materials during regeneration to the jawbone. The study included 88 patients during the 12-month follow-up. All the patients had undergone oral surgical procedures using two different substitute materials—Cerasorb (high-rate resorbable (β-tricalcium phosphate)) and Endobone (low-rate resorbable (hydroxyapatite)). Texture analysis was performed in intraoral radiographs, in which regions of interest were established for the bone substitute materials and reference bone. Five texture features were calculated, namely the sum average (SumAverg), entropy (Entropy), and three Harr discrete wavelet transform coefficients. This study revealed that all 5 features described the healing process well. Entropy was decreased in both cases with time; however, in Cerasorb cases, the texture feature values were very close to those of the reference bone after 12 months of healing (p < 0.05). The wavelet transform coefficient at scale 6 also showed that longitudinal objects appeared in implantation sites, similar to trabecular bone (p < 0.05) after 12 months of healing. The slow-resorbing material restored the structure of the alveolar crest better in terms of producing large objects similar to the components of a barrel bone image (wavelet coefficients), but required a longer time for reconstruction. The fast-resorbing material showed a texture image with a similar scattering of structures to that of the reference bone (entropy) after 12 months. Full article

(This article belongs to the Special Issue Numerical and Biomechanical Analysis in Bioengineering)

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11 pages, 1026 KiB

Open AccessArticle

Influence of General Mineral Condition on Collagen-Guided Alveolar Crest Augmentation

by Marcin Kozakiewicz, Piotr Szymor and Tomasz Wach

Materials 2020, 13(16), 3649; https://doi.org/10.3390/ma13163649 - 18 Aug 2020

Cited by 10 | Viewed by 3210

Abstract

The local regeneration of bone defects is regulated by general hormone, enzyme, ion, and vitamin levels. General diseases and dysregulation of the human mineral system can impact this process, even in alveolar crest. The aim of this study is to investigate a relation [...] Read more.

The local regeneration of bone defects is regulated by general hormone, enzyme, ion, and vitamin levels. General diseases and dysregulation of the human mineral system can impact this process, even in alveolar crest. The aim of this study is to investigate a relation between bone density, measured in two-dimensional X-rays, and general mineral condition of patients. The study included 42 patients on whom tooth extractions were performed. Data were divided into two groups: the region where collagen scaffold (BRM) was used and the reference region of intact normal bone (REF). Two-dimensional intraoral radiographs were taken in all cases just after the surgery (00 M) and 12 months later (12 M). Thyrotropin (TSH), parathormone (PTH), Ca²⁺ in serum, HbA1c, vitamin 25(OH)D₃, and spine densitometry were checked. Digital texture analysis in MaZda 4.6 software was done. Texture Index (TI: BRM 1.66 ± 0.34 in 00 M, 1.51 ± 0.41 in 12 M, and REF 1.72 ± 0.28) and Bone Index (BI: BRM 0.73 ± 0.17 in 00 M, 0.65 ± 0.22 41 in 12 M, and REF 0.80 ± 0.14) were calculated to evaluate bone regeneration process after 12 months of healing (TI (p < 0.05) and BI (p < 0.01) are lower in BRM 12 M than in REF). This showed a relation between BI and TSH (R² = 26%, p < 0.05), as well as a between BI and patient age (R² = 65%, p < 0.001), and a weak relation between TI and TSH level (R² = 10%, p < 0.05). This study proved that a collagen scaffold can be successfully used in alveolar crest regeneration, especially in patients with a high normal level of TSH in the middle-aged population. Full article

(This article belongs to the Special Issue Numerical and Biomechanical Analysis in Bioengineering)

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18 pages, 2876 KiB

Open AccessArticle

Application of Texture and Fractal Dimension Analysis to Estimate Effectiveness of Oral Leukoplakia Treatment Using an Er:YAG Laser—A Prospective Study

by Kamil Jurczyszyn and Marcin Kozakiewicz

Materials 2020, 13(16), 3614; https://doi.org/10.3390/ma13163614 - 15 Aug 2020

Cited by 6 | Viewed by 2563

Abstract

Background: Oral leukoplakia (OL) is a potential neoplasmic lesion. The aim of this study was to apply texture analysis (TA) and fractal dimension analysis (FDA) to estimate the effectiveness of OL treatment using an Er:YAG laser. Methods: Eighteen patients with 32 lesions were [...] Read more.

Background: Oral leukoplakia (OL) is a potential neoplasmic lesion. The aim of this study was to apply texture analysis (TA) and fractal dimension analysis (FDA) to estimate the effectiveness of OL treatment using an Er:YAG laser. Methods: Eighteen patients with 32 lesions were treated. Laser procedures were conducted using the LiteTouch™ Er:YAG Dental Laser. The diameter of the operational tip was 1.3 mm, the power was 50 mJ, the frequency was 50 Hz, and the wavelength was 2940 nm. TA was based on long and short-run emphasis inverse moments, difference entropy, inverse difference moment, and wavelet decomposition for two-dimensional photography. FDA was measured using the box-counting method. Results: Total response was achieved in 50% of lesions, partial response was observed in 47%, and 3% of lesions did not respond to treatment. Recurrence occurred in 34% of lesions. TA features indicated pathological images depicting leukoplakia and complete reconstruction of the correct mucosal image after laser ablation. The discrete wavelet transformation feature detects much larger structures than the properties derived from the run-length matrix and co-occurrence matrix. Conclusions: The Er:YAG laser is an effective treatment method in cases of oral leukoplakia. Leukoplakia treatment by Er:YAG laser is an effective modality, as revealed by the oral mucosa microstructure. TA and FDA are promising methods to estimate the effectiveness of OL treatment. Full article

(This article belongs to the Special Issue Numerical and Biomechanical Analysis in Bioengineering)

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15 pages, 5666 KiB

Open AccessArticle

New Oral Surgery Materials for Bone Reconstruction—A Comparison of Five Bone Substitute Materials for Dentoalveolar Augmentation

by Marcin Kozakiewicz and Tomasz Wach

Materials 2020, 13(13), 2935; https://doi.org/10.3390/ma13132935 - 30 Jun 2020

Cited by 21 | Viewed by 3940

Abstract

This article presents a comparison of bone replacement materials in terms of their ability to produce living bone image at the place of their implantation. Five bone replacement materials are compared (Osteovit—porous collagen, Cerasorb Foam—collagen scaffolding of synthetic β tricalcium phosphate, Osbone—synthetic hydroxyapatite, [...] Read more.

This article presents a comparison of bone replacement materials in terms of their ability to produce living bone image at the place of their implantation. Five bone replacement materials are compared (Osteovit—porous collagen, Cerasorb Foam—collagen scaffolding of synthetic β tricalcium phosphate, Osbone—synthetic hydroxyapatite, Endobone—deproteinized bovine-derived cancellous bone hydroxyapatite, and Cerasorb—synthetic β tricalcium phosphate). Intraoral radiographs are taken immediately after implantation and 12 months later. The texture analysis was performed to assess (texture index, TI) the level of structure chaos (entropy) in relation to the presence of longitudinal elements visible in radiographs (run length emphasis moment). The reference ratio of the chaotic trabecular pattern (Entropy) to the number of longitudinal structures, i.e., trabeculae (LngREmph), is 176:100 (i.e., 1.76 ± 0.28). Radiological homogeneity immediately after the implantation procedure is a result of the similar shape of its particles (Osbone, Endobone and Cerasorb) or radiolucency (Osteovit, Cerasorb Foam). The particles visible in radiographs were similar in the LngREmph parameters applied to the reference bone, but not in the co-occurrence matrix features. The TI for Osteovit during a 12-month follow-up period changed from 1.55 ± 0.26 to 1.48 ± 0.26 (p > 0.05), for Cerasorb Foam from 1.82 ± 0.27 to 1.63 ± 0.24 (p < 0.05), for Osbone from 1.97 ± 0.31 to 1.74 ± 0.30 (p < 0.01), and for Endobone from 1.86 ± 0.25 to 1.84 ± 0.25 (p > 0.05), The observed structure in the radiological image of bone substitute materials containing calcium phosphates obtains the characteristics of a living bone image after twelve months. Full article

(This article belongs to the Special Issue Numerical and Biomechanical Analysis in Bioengineering)

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9 pages, 2497 KiB

Open AccessArticle

Are Magnesium Screws Proper for Mandibular Condyle Head Osteosynthesis?

by Marcin Kozakiewicz

Materials 2020, 13(11), 2641; https://doi.org/10.3390/ma13112641 - 10 Jun 2020

Cited by 13 | Viewed by 3973

Abstract

Recently, magnesium alloys have gained a significant amount of recognition as potential biomaterials for degradable implants for craniofacial bone screws. Purpose: The aim of this work was to compare screws made specifically for mandibular head osteosynthesis from different materials. Materials and Methods: Screws [...] Read more.

Recently, magnesium alloys have gained a significant amount of recognition as potential biomaterials for degradable implants for craniofacial bone screws. Purpose: The aim of this work was to compare screws made specifically for mandibular head osteosynthesis from different materials. Materials and Methods: Screws measuring 14 mm made by one manufacturer specifically for mandibular head osteosynthesis out of the following materials were selected: magnesium (MgYREZr), titanium (Ti6Al7Nb), and polymer (PLGA). The axial pull-out strength and torsional properties were investigated. Results: Each type of screw presented different pull-out forces (Kruskal–Wallis test, p < 0.001). The magnesium screw had the highest pull-out force of 399 N (cracked without the screw out being pulled out), followed by the titanium screw, with a force of 340 N, and the PLGA screw, with a force of 138 N (always cracked at the base of the screw head without the screw being pulled out). ANOVA was performed for the maximal torques before damage to the screw (torsional properties), revealing that the maximal torque of the magnesium screw was 16 N·cm, while that of the titanium screw was 19 N·cm. The magnesium screw was significantly weaker than the titanium screw (p < 0.05). The measured torque and pull-out force were not related to each other (p > 0.05). Conclusion: Among the screws compared, the metal biodegradable magnesium screw seems to be the most suitable material for multiscrew mandibular head osteosynthesis, considering the condition of the fragile screwdriver socket. Full article

(This article belongs to the Special Issue Numerical and Biomechanical Analysis in Bioengineering)

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Review

Jump to: Research

16 pages, 1590 KiB

Open AccessReview

Application of Finite Element Analysis in Oral and Maxillofacial Surgery—A Literature Review

by Magdalena Lisiak-Myszke, Dawid Marciniak, Marek Bieliński, Hanna Sobczak, Łukasz Garbacewicz and Barbara Drogoszewska

Materials 2020, 13(14), 3063; https://doi.org/10.3390/ma13143063 - 9 Jul 2020

Cited by 69 | Viewed by 5410

Abstract

In recent years in the field of biomechanics, the intensive development of various experimental methods has been observed. The implementation of virtual studies that for a long time have been successfully used in technical sciences also represents a new trend in dental engineering. [...] Read more.

In recent years in the field of biomechanics, the intensive development of various experimental methods has been observed. The implementation of virtual studies that for a long time have been successfully used in technical sciences also represents a new trend in dental engineering. Among these methods, finite element analysis (FEA) deserves special attention. FEA is a method used to analyze stresses and strains in complex mechanical systems. It enables the mathematical conversion and analysis of mechanical properties of a geometric object. Since the mechanical properties of the human skeleton cannot be examined in vivo, a discipline in which FEA has found particular application is oral and maxillofacial surgery. In this review we summarize the application of FEA in particular oral and maxillofacial fields such as traumatology, orthognathic surgery, reconstructive surgery and implantology presented in the current literature. Based on the available literature, we discuss the methodology and results of research where FEA has been used to understand the pathomechanism of fractures, identify optimal osteosynthesis methods, plan reconstructive operations and design intraosseous implants or osteosynthesis elements. As well as indicating the benefits of FEA in mechanical parameter analysis, we also point out the assumptions and simplifications that are commonly used. The understanding of FEA’s opportunities and advantages as well as its limitations and main flaws is crucial to fully exploit its potential. Full article

(This article belongs to the Special Issue Numerical and Biomechanical Analysis in Bioengineering)

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