Your browser doesn't support javascript.
loading
Mostrar: 20 | 50 | 100
Resultados 1 - 20 de 27
Filtrar
Más filtros













Base de datos
Intervalo de año de publicación
1.
Clin Oral Investig ; 28(7): 358, 2024 Jun 06.
Artículo en Inglés | MEDLINE | ID: mdl-38842694

RESUMEN

OBJECTIVES: To establish an analysis pipeline for the volumetric evaluation of the osteotomy site after bilateral sagittal split osteotomy (BSSO). PATIENTS AND METHODS: Cone-beam computed tomography (CBCT) was performed before, directly after BSSO, and 6-12 months after surgery. Image segmentations of each osteotomy gap data set were performed manually by four physicians and were compared to a semi-automatic segmentation approach. RESULTS: Five patients with a total of ten osteotomy gaps were included. The mean interclass correlation coefficient (ICC) of individual patients was 0.782 and the standard deviation 0.080 when using the manual segmentation approach. However, the mean ICC of the evaluation of anatomical sites and time points separately was 0.214, suggesting a large range of deviation within the manual segmentation of each rater. The standard deviation was 0.355, further highlighting the extent of the variation. In contrast, the semi-automatic approach had a mean ICC of 0.491 and a standard deviation of 0.365, which suggests a relatively higher agreement among the operators compared to the manual segmentation approach. Furthermore, the volume of the osteotomy gap in the semi-automatic approach showed the same tendency in every site as the manual segmentation approach, but with less deviation. CONCLUSION: The semi-automatic approach developed in the present study proved to be valid as a standardised method with high repeatability. Such image analysis methods could help to quantify the progression of bone healing after BSSO and beyond, eventually facilitating the earlier identification of patients with retarded healing.


Asunto(s)
Tomografía Computarizada de Haz Cónico , Osteotomía Sagital de Rama Mandibular , Humanos , Tomografía Computarizada de Haz Cónico/métodos , Proyectos Piloto , Osteotomía Sagital de Rama Mandibular/métodos , Femenino , Masculino , Adulto , Resultado del Tratamiento
2.
Quant Imaging Med Surg ; 14(2): 1652-1659, 2024 Feb 01.
Artículo en Inglés | MEDLINE | ID: mdl-38415165

RESUMEN

Background: Sagittal split ramus osteotomy is an established procedure used in oral and maxillofacial surgery. Major bleeding is representative intraoperative complication involves vessels such as the inferior alveolar, facial, and maxillary arteries and accompanying veins, in particular the retromandibular vein (RMV). We previously described the RMV course patterns using embalmed cadavers. However, owing to the possible influence of formalin fixation and unclear skeletal classification of the jaws, the present study aimed to use contrast-enhanced computed tomography to confirm the RMV in patients with defined jaw deformities. Methods: Twenty patients with orthognathic jaw deformities (40 sides) were included. The RMV and the lateral and posterior views of the mandible were evaluated using contrast-enhanced computed tomography. Course patterns and RMV positions were classified as previously reported. Results: Three patterns were identified in the lateral view. Type A: RMV posterior to the posterior border of the ramus (n=25; 62.5%). Type B: adjoining the posterior border of the ramus (n=12; 30.0%). Type C: anterior to the posterior border of the ramus (n=3; 7.5%). Five course patterns were identified in the posterior view. Pattern I: rectilinear course running medial to the posterior border of the ramus (n=3; 7.5%). Pattern II: diagonal course running medially from immediately posterior to posterior border of the ramus (n=11; 27.5%). Pattern III: rectilinear course running immediately posterior to the posterior border of the ramus (n=12; 30.0%). Pattern IV: diagonal course running from lateral to medial relative to the posterior border of the ramus (n=8; 20.0%). Pattern V: diagonal course running from lateral to immediately posterior relative to the posterior border of the ramus (n=6; 15.0%). In the no-course pattern group, the RMV inferior to the lingula was lateral to its position and superior to that of the lingula. In half of the cases, the left and right sides exhibited different running patterns. We observed no correlation between the skeletal patterns of jaw deformities and the course of the RMV. Conclusions: Type B/Pattern II that runs in a straight line bordering the posterior margin of the ramus requires the most attention during surgery. These findings suggest the possibility of predicting intraoperative bleeding risk.

3.
J Prosthodont Res ; 68(2): 336-346, 2024 Apr 08.
Artículo en Inglés | MEDLINE | ID: mdl-37612075

RESUMEN

PURPOSE: This study aims to develop a numerical prediction method for the average and standard deviation values of the largely varied fatigue life of additively manufactured commercially pure titanium (CPTi grade 2) clasps. Accordingly, the proposed method is validated by applying it to clasps of different shapes. METHODS: The Smith-Watson-Topper (SWT) equation and finite element analysis (FEA) were used to predict the average fatigue life. The variability was expressed by a 95% reliability range envelope based on the experimentally determined standard deviation. RESULTS: When predicting the average fatigue life, the previously determined fatigue parameters implemented in the SWT equation were found to be useful after conducting fatigue tests using a displacement-controlled fatigue testing machine. The standard deviation with respect to stroke and fatigue life was determined for each clasp type to predict variability. The proposed prediction method effectively covered the experimental data. Subsequently, the prediction method was applied to clasps of different shapes and validated through fatigue tests using 22 specimens. Finally, the fracture surface was observed using scanning electron microscopy (SEM). Many manufacturing process-induced defects were observed; however, only the surface defects where the maximum tensile stress occurred were crucial. CONCLUSIONS: It was confirmed that the fatigue life of additively manufactured pure titanium parts is predictable before the manufacturing process considering its variability by performing only static elasto-plastic FEA. This outcome contributes to the quality assurance of patient-specific clasps without any experimental investigation, reducing total costs and response time.


Asunto(s)
Aleaciones de Cromo , Dentadura Parcial Removible , Humanos , Titanio , Reproducibilidad de los Resultados , Abrazadera Dental , Ensayo de Materiales
4.
J Clin Med ; 12(23)2023 Nov 29.
Artículo en Inglés | MEDLINE | ID: mdl-38068460

RESUMEN

Genioplasty is performed for the orthognathic surgical correction of dentofacial deformities. This article reports a safe and accurate method for genioplasty combining a novel three-dimensional (3D) device with mixed reality (MR)-assisted surgery using a registration marker and a head-mounted display. Four types of devices were designed based on the virtual operation: a surgical splint with a connector; an osteotomy device; a repositioning device; and a registration marker. Microsoft HoloLens 2 and Holoeyes MD were used to project holograms created using computed tomography (CT) data onto the surgical field to improve the accuracy of the computer-aided designed and manufactured (CAD/CAM) surgical guides. After making an incision on the oral vestibule, the splint was fitted on the teeth and the osteotomy device was mounted at the junction site, placed directly on the exposed mandible bone surface. Temporary screws were fixed into the screw hole. An ultrasonic cutting instrument was used for the osteotomy. After separating the bone, a repositioning device was connected to the splint junction and bone segment, and repositioning was performed. At the time of repositioning, the registration marker was connected to the splint junction, and mandible repositioning was confirmed three-dimensionally through HoloLens 2 into the position specified in the virtual surgery. The rate of overlay error between the preoperative virtual operation and one-month postoperative CT data within 2 mm was 100%. CAD/CAM combined with MR enabled accurate genioplasty.

5.
Pain Res Manag ; 2023: 1021918, 2023.
Artículo en Inglés | MEDLINE | ID: mdl-37719895

RESUMEN

The inferior alveolar nerve block (IANB) is an established technique with a success rate of 60-80%; however, large errors have been reported among operators. Some dentists do not prefer to use IANB because of the risk of complications. Nevertheless, it is a useful technique for pain control, and a secure IANB offers significant benefits to operators and patients. This case series study aimed to investigate the efficacy of the "IANB Device," a nerve block guide for IANB, and the adverse events associated with its use in clinical practice. IANB was performed using the device on five patients who had undergone detailed computed tomography examination for chronic orofacial pain in the third division of the trigeminal nerve. Lidocaine 1% (1 mL, no adrenaline added) was used as the local anesthetic. IANB was performed by three dentists with 2, 5, and 11 years of experience in orofacial pain treatment. Thus, the data were collected in triplicate for each patient. The primary endpoints were whether adjustment of the IANB device was required, changes in the sensation threshold of the lower lip, the time to disappearance of pain, the presence or absence of tongue sensation ("Do you have numbness in your tongue?": "Yes/No"), and discomfort (visual analog scale). The incidence of any other adverse events was recorded. The procedure was judged to be successful if the pain disappeared and an elevation in the sensation threshold of the lower lip was observed. Adjustment of the IANB device was not required in any patient. A significant elevation in the sensation threshold of the lower lip and the disappearance of pain were observed in all patients. Three of the five patients reported experiencing tongue numbness. Discomfort with the use of the IANB device was less than 30 mm on the visual analog scale. No notable complications were observed. The appropriate type, concentration, and dosage of the local anesthetic must be considered during general dental treatment and oral surgical procedures. Our findings suggest that the IANB device is useful for eliminating errors between operators, enhancing safety, and improving the success rate.


Asunto(s)
Anestesia de Conducción , Anestésicos Locales , Humanos , Hipoestesia , Dolor Facial , Nervio Mandibular
7.
J Prosthodont Res ; 67(4): 626-632, 2023 Oct 13.
Artículo en Inglés | MEDLINE | ID: mdl-37032073

RESUMEN

PURPOSE: In this study, the fatigue properties of additively manufactured titanium clasps were compared with those of commercially pure titanium (CPTi) and Ti-6Al-4V (Ti64), manufactured using laser powder-bed fusion. METHODS: Fourteen specimens of each material were tested under the cyclic condition at 1 Hz with applied maximum strokes ranging from 0.2 to 0.5 mm, using a small stroke fatigue testing machine. A numerical approach using finite element analysis (FEA) was also developed to predict the fatigue life of the clasps. RESULTS: The results showed that although no significant differences were observed between the two materials when a stroke larger than 0.35 mm was applied, CPTi had a better fatigue life under a stroke smaller than 0.33 mm. The distributions of the maximum principal stress in the FEA and the fractured position in the experiment were in good agreement. CONCLUSIONS: Using a design of the clasp of the present study, the advantage of the CPTi clasp in its fatigue life under a stroke smaller than 0.33 mm was revealed experimentally. Furthermore, the numerical approach using FEA employing calibrated parameters for the Smith-Watson-Topper method are presented. Under the limitations of the aforementioned clasp design, the establishment of a numerical method enabled us to predict the fatigue life and ensure the quality of the design phase before manufacturing.


Asunto(s)
Aleaciones , Accidente Cerebrovascular , Humanos , Titanio , Polvos , Abrazadera Dental , Rayos Láser , Ensayo de Materiales
9.
J Prosthodont Res ; 67(3): 487-492, 2023 Jul 31.
Artículo en Inglés | MEDLINE | ID: mdl-36031348

RESUMEN

PATIENTS: This clinical report describes the process for fabricating a double-crown-retained removable dental prosthesis combining a fiber-reinforced composite and zirconia using digital technology. An 83-year-old woman presented with gingival swelling around the maxillary right premolar. The swollen tooth was the abutment tooth of a cross-arch fixed partial denture. An intraoral scanner (IOS) and computer-aided design/manufacturing as digital technology were used to plan treatment with a double-crown-retained removable dental prosthesis. A metal-free prosthesis using zirconia for the primary crown and fiberglass-reinforced composite resin for the secondary crown was planned, and the patient consented to the treatment plan. After autotransplantation of a tooth as one of the abutments, the IOS was used to obtain digital scans of the prepared surface of the abutment teeth, opposing dentition, and occlusal relationships. First, primary crowns were milled using zirconia. Next, the intraoral scanner obtained a pick-up impression of the primary crowns, and secondary crowns were designed and milled from the fiber-reinforced composite. After delivery, the patient expressed satisfaction with the functionality, esthetics, and fit of the double-crown-retained removable dental prosthesis. DISCUSSION: Digital technology offers many advantages such as efficient fabrication of double crowns, reduced material costs, improved biocompatibility, and good aesthetics of metal-free materials. CONCLUSIONS: This clinical report describes the application of digital technology for the fabrication of a double-crown-retained removable dental prosthesis combining a fiber-reinforced composite and zirconia, resulting in patient satisfaction.


Asunto(s)
Diseño de Prótesis Dental , Tecnología Digital , Femenino , Humanos , Anciano de 80 o más Años , Diseño de Prótesis Dental/métodos , Circonio , Coronas , Diseño Asistido por Computadora , Porcelana Dental
10.
Dent Mater J ; 41(2): 286-294, 2022 Apr 01.
Artículo en Inglés | MEDLINE | ID: mdl-35249900

RESUMEN

The present study was aimed to develop a probabilistic finite element method (FEM) that predicts the variability in the fatigue life of additively manufactured clasp so that it can be used as a virtual test in the design phase before manufacturing. Titanium alloy (Ti-6Al-4V) clasp with integrated chucking part, which was designed for experimental fatigue test to validate the computational method, was investigated. To predict the lower bound, an initial spherical defect was assumed in the region where stress concentration was predicted. The Smith-Watson-Topper (SWT) method, Bäumel & Seeger rule, elasto-plastic FEM, and zooming FEM were used. The influence of assumed initial defect on the fatigue life was significant, and the large variability in the fatigue life was predicted. This study demonstrated that the proposed practical computational method can simulate the large variability in the fatigue life of titanium alloy clasp, which is useful in its design before manufacturing.


Asunto(s)
Aleaciones , Titanio , Diseño de Dentadura , Análisis de Elementos Finitos , Falla de Prótesis
11.
J Dent Educ ; 86(5): 526-534, 2022 May.
Artículo en Inglés | MEDLINE | ID: mdl-34978716

RESUMEN

PURPOSE/OBJECTIVES: Simulated educational models of teeth, bones, and gums have been used for a long time in procedural skills training in dentistry.  The advent of three-dimensional (3D) printing technologies and additive manufacturing has facilitated the production of more advanced 3D printed models that can be utilized for surgical and dental training together with other technologies (e.g., 3D scanners and image analysis software). METHODS: We conducted training on osteotomy in the maxilla and mandible using maxillofacial simulation software (MSS) and a 3D-printed model for 5th-year undergraduate dental students (13 students in 2017 and 11 students in 2018 with more than half of their results). We compared the group (13 students) who performed osteotomy after participating in the simulation lecture with those (11 students) who performed osteotomy after performing self-simulation (they were instructed to bring their personal computers and install the MSS) using tests and questionnaires (pre- and post-curriculum). RESULTS: The average test score was significantly higher in the group who performed osteotomy using the 3D-printed model after performing self-simulation; participants in this group had acquired a better understanding of the surgical procedure. Comparison using questionnaires showed a significant difference in the students' understanding of instruments and surgical techniques between both groups. CONCLUSION: The MSS and 3D printed models are widely used clinically. Incorporating these in the curriculum will help accelerate student development. In addition, prompt education on the purpose and usefulness of these tools will not only facilitate simulation software and 3D-printed model-based treatment plan in the clinic but also promote further research.


Asunto(s)
Entrenamiento Simulado , Estudiantes de Odontología , Educación en Odontología , Humanos , Modelos Anatómicos , Osteotomía , Impresión Tridimensional , Programas Informáticos
12.
Quant Imaging Med Surg ; 11(5): 2187-2194, 2021 May.
Artículo en Inglés | MEDLINE | ID: mdl-33936998

RESUMEN

In the field of oral and maxillofacial surgery, many institutions have recently begun using three-dimensional printers to create three-dimensional models and mixed reality in a variety of diseases. Here, we report the actual situation model which we made using three-dimensional printer from virtual operation data and the resection that was performed while grasping a maxillary benign tumor and neighboring three-dimensional structure by designing an application for Microsoft® HoloLens, and using Mixed Reality surgery support during the procedure.

13.
Bull Tokyo Dent Coll ; 62(2): 99-106, 2021 Jun 04.
Artículo en Inglés | MEDLINE | ID: mdl-33994425

RESUMEN

The objective of this study was to analyze the distribution and morphology of the valves in the human retromandibular vein. The retromandibular, internal thoracic, azygos, femoral, and brachial veins were harvested from 46 cadavers donated to the Department of Anatomy at Tokyo Dental College for dissection. The frequency of the valves in each vein, the length of the cusps, and the thickness of the vein itself were measured. Valves were present at high frequency (92.1%) in the veins of the limbs and had cusps at least twice as long as the internal diameter of the vein. Veins in the trunk contained a lower frequency of valves, with cusps that tended to be shorter (1.60±0.77) than those of the venous valves in the limbs (2.12±0.60). The valves of the retromandibular vein tended to resemble venous valves in the trunk in terms of both frequency and morphology. The main function of venous valves in the limbs is to prevent retrograde flow. Conversely, valves in the veins of the trunk and retromandibular vein play a role in retaining blood in the veins, and their relationship to other veins means that they can cause major hemorrhage.


Asunto(s)
Venas , Cadáver , Humanos , Tokio
14.
J Dent ; 110: 103681, 2021 07.
Artículo en Inglés | MEDLINE | ID: mdl-33905767

RESUMEN

OBJECTIVES: In recent years, computer-aided design/computer-aided manufacturing (CAD/CAM) has been used to produce removable complete dentures. Most workflows include fabrication of milled or 3D-printed try-in prostheses. 3D-printing accuracy is affected by laboratory-specific and operator-dependent factors. This international five-center study sought to compare the accuracy of 3D-printed and milled try-in dentures. METHODS: The construction file of a maxillary removable complete denture was selected as a reference. Eight try-in dentures were 3D printed at each of the five centers. Each center used their own printer (Objet260 Connex, Stratasys; MAX, Asiga; Anycubic Photon, Anycubic 3D; PRO2, Asiga and cara Print 4.0, Kulzer) along with their own material, printing settings, post-processing and light-curing parameters. At center 2, eight try-in dentures were milled to serve as a benchmark (PrograMill PM7, Ivoclar Vivadent). Dentures were scanned and aligned to the reference file using best-fit algorithms. Geometric accuracy was analyzed using the root mean square value (trueness) and standard deviation (precision) of the distributed absolute mesh deviations. Mean values of the five sets of printed dentures and the single set of milled dentures were compared. RESULTS: Milled dentures showed a mean trueness of 65 ±â€¯6 µm and a mean precision of 48 ±â€¯5 µm. Thus, they were significantly more accurate than the 3D-printed dentures in four out of five centers. In mean absolute numbers, 3D printing was less true than milling by 17-89 µm and less precise by 8-66 µm. CONCLUSIONS: Although milling remains the benchmark technique for accuracy, differences between milled and 3D-printed dentures were non-significant for one printing center. Furthermore, the overall performance of 3D printing at all centers was within a clinically acceptable range for try-in prostheses. CLINICAL SIGNIFICANCE: The accuracy of 3D printing varies widely between and within laboratories but nonetheless lies within the range of accuracy of conventional manufacturing methods.


Asunto(s)
Dentadura Completa , Impresión Tridimensional , Diseño Asistido por Computadora , Maxilar , Flujo de Trabajo
15.
Ann Anat ; 235: 151694, 2021 May.
Artículo en Inglés | MEDLINE | ID: mdl-33571646

RESUMEN

Skeletal muscle regeneration is initiated by the activation of the transcription factor paired box 7 (Pax7), which is expressed in the satellite cells. The nuclear transcription factor T-cell factor 4 (Tcf4) is expressed in the fibroblasts and is involved in muscle tissue repair, while M2-like macrophages play an important role in skeletal muscle regeneration. However, the localization of M2-like macrophages and the expression of Tcf4 over a period of time during skeletal muscle regeneration remain unknown. Therefore, the murine masseter muscle was immunofluorescence investigated for the surface protein CD206 of M2-like macrophages and Tcf4 of fibroblasts during skeletal muscle regeneration to understand the changes in the CD206 and Tcf4 expression over time. We observed that CD206 entered the cytoplasm of some regenerating muscle fibers 5-7 days after the experimental muscle damage, that is, in the early stage of maturation of the regenerating muscle fibers with central nuclei. In addition, Tcf4 was expressed in the nuclei of the fibroblasts around the regenerating muscle fibers and in the central nuclei of the regenerating muscle fibers. Furthermore, the expression of laminin adjacent to Tcf4-positive cells was observed to partially disappear, and the shape of this missing part was observed to be identical to that of the nuclei of Tcf4-positive cells adjacent to the laminin. Clathrin was also expressed in these sites, demonstrating endocytosis. Thus, these results suggest that in the early stage of maturation of the regenerating muscle fibers, M2-like macrophages and Tcf4-positive fibroblasts enter the cytoplasm of the regenerating muscle fibers, thereby regulating the expression of various maturation factors.


Asunto(s)
Regeneración , Proteína 2 Similar al Factor de Transcripción 7 , Animales , Fibroblastos , Macrófagos , Ratones , Fibras Musculares Esqueléticas , Músculo Esquelético
16.
Maxillofac Plast Reconstr Surg ; 42(1): 32, 2020 Dec.
Artículo en Inglés | MEDLINE | ID: mdl-32963987

RESUMEN

BACKGROUND: Le Fort I osteotomy is a highly effective treatment for skeletal jaw deformities and is commonly performed. High Le Fort I osteotomy is a modified surgical procedure performed for improving the depression of the cheeks by setting the osteotomy higher than the conventional Le Fort I osteotomy. Developments in three-dimensional (3D) technology have popularized the use of 3D printers in various institutions, especially in orthognathic surgeries. In this study, we report a safe and inexpensive method of performing a high Le Fort I osteotomy using a novel 3D device and piezosurgery, which prevent tooth root injury without disturbing the operation field for patients with a short midface and long tooth roots. RESULTS: A 17-year-old woman presented with facial asymmetry, mandibular protrusion, a short midface, and long tooth roots. We planned high Le Fort I osteotomy and bilateral sagittal split ramus osteotomy. Prevention of damage to the roots of the teeth and the infraorbital nerve and accurate determination of the posterior osteotomy line were crucial for clinical success. Le Fort I osteotomy using 3D devices has been reported previously but were particularly large in size for this case. Additionally, setting the fixing screw of the device was difficult, because of the risk of damage to the roots of the teeth. Therefore, a different surgical technique, other than the conventional Le Fort I osteotomy and 3D device, was required. The left and right parts of the 3D device were fabricated separately, to prevent any interference in the surgical field. Further, the 3D device was designed to accurately cover the bone surface from the piriform aperture to the infra-zygomatic crest with two fixation points (the anterior nasal spine and the piriform aperture), which ensured stabilization of the 3D device. The device is thin and does not interfere with the surgical field. Safe and accurate surgical performance is possible using this device and piezosurgery. The roots of the teeth and the infraorbital nerve were unharmed during the surgery. CONCLUSIONS: This device is considerably smaller than conventional devices and is a simple, low-cost, and efficient method for performing accurate high Le Fort I osteotomy.

17.
Oncol Lett ; 20(3): 2153-2160, 2020 Sep.
Artículo en Inglés | MEDLINE | ID: mdl-32782532

RESUMEN

Disorders of the oral mucosa are considered easy to diagnose since they can be visualized and examined directly. A change in the color of the oral mucosa reflects histopathological changes and is an important diagnostic parameter. However, the subjective perception of color varies. To determine the extent of resection for oral mucosa conditions, it is necessary to digitize the color and perform objective assessments. In recent years, fluorescence visualization devices and analysis software that measure tissue luminance G have been employed for the identification of oral mucosa diseases. Fluorescence visualization is presumably based on the decrease in epithelial flavin adenine dinucleotide content and luminance G values due to the destruction of collagen cross-links [fluorescence visualization loss (FVL)]. However, cases with differences between luminance values and histopathological presentation exist. Therefore, additional factors may affect fluorescence visualization. The present study used a portable, non-contact oral mucosa fluorescence visualization device for luminance measurements in seven patients with oral squamous cell carcinoma. Furthermore, Picro-Sirius Red and immunohistochemical staining were performed for CK13, CK17, Ki67, p53 and E-cadherin in the FVL(+) (lesion) and FVL(-) (resection stump) areas to elucidate the principle of fluorescence visualization. Fluorescence was significantly lower in the FVL(+) than in the FVL(-) areas, and the mean luminance G value was 56. The Picro-Sirius Red stain revealed collagen destruction in the FVL(+) areas but no collagen disruption in the FVL(-) areas. CK13 was negative in the FVL(+) and positive in the FVL(-) areas, whereas the opposite pattern was observed for CK17. In the FVL(+) area, p53 staining was positive. E-cadherin expression was enhanced in the FVL(-) areas and reduced in the FVL(+) areas. Furthermore, the luminance G value tended to be lower in cases with weaker E-cadherin staining. The aforementioned results suggest that decreased E-cadherin expression may be a factor that regulates fluorescence visualization.

18.
J Biomed Mater Res B Appl Biomater ; 108(7): 2799-2806, 2020 10.
Artículo en Inglés | MEDLINE | ID: mdl-32190994

RESUMEN

The coronoid process provides attachment to temporalis and masseter muscles, and thus plays an important role in mastication. Tendons connect muscles and bones, mediating the transmission of functional loads to bones. Thus, tendon-bone entheses govern mechanical stress in bones. The preferential orientation of biological apatite (BAp) crystallites, the main mineral component in bones, is an important index for bone quality and function, and is largely influenced by locally applied stress. In this study, we analyzed BAp orientation, Young's modulus, and bone mineral density (BMD) at different sites in the human coronoid process. No differences in BMD were found among the analyzed sites, but BAp crystal orientation was observed to differ. BAp crystallites showed a uni-directional orientation in the mesiodistal direction at the coronoid process apex, but were oriented in the direction vertical to the occlusal plane at other sites. Young's modulus tended to vary according to the BAp orientation. At the apex, a tendon form with characteristics different from those at other sites, including the presence of a fibrocartilaginous layer that may act as a stretching brake to control stress concentration, was observed. These findings suggest that the functional pressure of the temporalis muscle affects bone quality and strength.


Asunto(s)
Densidad Ósea , Mandíbula/química , Estrés Mecánico , Tendones/química , Anciano , Anciano de 80 o más Años , Femenino , Fibrocartílago/química , Humanos , Masculino
19.
J Craniofac Surg ; 31(3): 861-864, 2020.
Artículo en Inglés | MEDLINE | ID: mdl-31842072

RESUMEN

PURPOSE: The maxillary vein is associated with major hemorrhage, an intraoperative risk factor during mandibuloplasty. Our objectives in this study were to identify the anatomical course of the maxillary vein relative to the mandible, and to ascertain the relationship of its course with that of the maxillary artery. METHODS: Thirteen sides of 13 cadavers in the possession of the Department of Anatomy of Tokyo Dental College were used. The maxillofacial region was first dissected, after which the upper part of the mandibular ramus was removed and the maxillary artery, maxillary vein, and pterygoid venous plexus were identified. The length of the maxillary vein and its height from the mandibular plane were then measured, and its anatomical course was recorded. RESULTS: The maxillary vein ran downward along the inner aspect of the temporal muscle, then from the base of the coronoid process it ran horizontally near the bone surface of the inner aspect of the mandibular ramus. After joining the inferior alveolar vein, it joined the superficial temporal vein to form the retromandibular vein. The mean length of the maxillary vein was 22.2 ±â€Š3.2 mm. At the posterior margin of the mandibular ramus, its mean height above the mandibular plane was 34.2 ±â€Š5.4 mm. From the posterior margin of the mandibular ramus to the lowest point of the mandibular notch, the maxillary vein was located within the areolar connective tissue directly above the periosteum adjoining the inner aspect of the mandibular ramus. CONCLUSIONS: In the wide area from the center of the maxillary notch to the posterior margin of the mandibular ramus, the maxillary vein runs extremely close to the periosteum on the inner aspect of the mandibular ramus, suggesting that it may pose a risk of hemorrhage in various oral surgical procedures.


Asunto(s)
Venas Yugulares/cirugía , Mandíbula/cirugía , Osteotomía Mandibular , Maxilar/irrigación sanguínea , Atención , Cadáver , Humanos , Maxilar/cirugía , Arteria Maxilar
20.
Maxillofac Plast Reconstr Surg ; 41(1): 43, 2019 Dec.
Artículo en Inglés | MEDLINE | ID: mdl-31649904

RESUMEN

BACKGROUND: Reconstructive surgery is often required for tumors of the oral and maxillofacial region, irrespective of whether they are benign or malignant, the area involved, and the tumor size. Recently, three-dimensional (3D) models are increasingly used in reconstructive surgery. However, these models have rarely been adapted for the fabrication of custom-made reconstruction materials. In this report, we present a case of maxillary reconstruction using a laboratory-engineered, custom-made mesh plate from a 3D model. CASE PRESENTATION: The patient was a 56-year-old female, who had undergone maxillary resection in 2011 for intraoral squamous cell carcinoma that presented as a swelling of the anterior maxillary gingiva. Five years later, there was no recurrence of the malignant tumor and a maxillary reconstruction was planned. Computed tomography (CT) revealed a large bony defect in the dental-alveolar area of the anterior maxilla. Using the CT data, a 3D model of the maxilla was prepared, and the site of reconstruction determined. A custom-made mesh plate was fabricated using the 3D model (Okada Medical Supply, Tokyo, Japan). We performed the reconstruction using the custom-made titanium mesh plate and the particulate cancellous bone and marrow graft from her iliac bone. We employed the tunneling flap technique without alveolar crest incision, to prevent surgical wound dehiscence, mesh exposure, and alveolar bone loss. Ten months later, three dental implants were inserted in the graft. Before the final crown setting, we performed a gingivoplasty with palate mucosal graft. The patient has expressed total satisfaction with both the functional and esthetic outcomes of the procedure. CONCLUSION: We have successfully performed a maxillary and dental reconstruction using a custom-made, pre-bent titanium mesh plate.

SELECCIÓN DE REFERENCIAS
DETALLE DE LA BÚSQUEDA