Development of ceramic and ceramic composite devices for maxillofacial applications.
Explore the source record for details and available documents.
Animals↗
SEARCH · PubMed Health
Results for “Mandibular Prosthesis”
Explore indexed PubMed citations for clinical trials, systematic reviews and public health research. Read source abstracts and follow each citation to its original PubMed record.
Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.
Methods of osseous reconstruction of the mandible following surgical resection.
Explore the source record for details and available documents.
Animals↗
Prefabricated silicone subdermal mandibular implants: observations and problems related to their application.
Success in the use of custom-fabricated Silastic implants in patients with facial contour defects led us to utilize this method in reconstructing mandibular defects. However, mandibular reconstruction with alloplastic material is quite difficult because of the presence of continous stress and motion in that region. The evolution in the use in the use of the mandibular implant from the commercially available one to the K-wire reinforced, prefabricated, silicone implant was largely dependent on the availability of silicone and the ultimate result obtained. In the past few years, about 30 subdermal implants were inserted. Some of those implants were placed immediately into patients undergoing resection for tumor. The implant was prefabricated prior to surgery from x-ray measurements of the anticipated segment to be resected; it was then used to reconstruct the defect prior to the final closure of the operative wound. Other implants were manufactured 6-18 months after resection for tumor or for deformity as a result of trauma. The implants were used to reconstruct the facial defects and to correct the funtional abnormality, such as drooling or deviation of the affected side by the unstable mandibular segment. Patients with severe congenital malformation have soft tissue deficiency in association with their bony malformation. Therefore, implants in such conditions were doomed to failure. Patient selection is the key to successful implantation.
Dental Implantation↗
Craniofacial contour defect reconstruction with a dacron/urethane composite: an alloplastic tray for bone induction fabrication and application.
An alloplastic tray made of poly(ethylene terephthalate) cloth mesh and poly(ether urethane) used in conjunction with cancellous bone-chip grafts is the basis for this new method of reconstructing facial osseous contour defects. The tray can be prefabricated in quantity and at low cost for standard defects, such as discontinuity defects of the mandible or for chin augmentation. It can be custom-fabricated for specific defects in individual patients as, for example, gunshot wounds to the forehead. The materials were chosen because of their known histocompatibility, the ease of fabrication, and because the materials can be molded to form esthetic contours. The can be easily modified at the time of surgery. Sterilization is by autoclaving. Initial studied were undertaken in mongrel dogs where mandibular discontinuity defects in the range of 2-4 cm were reconstructed. In man, the technique has been used to reconstruct discontinuity defects of the mandible ranging in size from 1.5-12 cm in 16 patients. Atrophic mandibular alveolar ridges have been augmented using this technique in 7 patients, thus providing an adequate alveolar ridge for dentures. Two patients with defects of the skull secondary to gunshot wounds have had frontal bone restoration using this method. Reconstructions of the ear, the chin, and the orbital floor are currently being evaluated. This technique overcomes many problems of esthetic contour reconstruction and combines the use of autogenous cancellous particulate bone and a tissue-compatible synthetic composite material.
Bone Transplantation↗
Evolution of the mandibular mesh implant.
Between 1960 and 1972, the Dallas Veterans Administration Hospital Maxillofacial Research Laboratory developed and made over 150 cast-mesh implants. Successive designs were ovoid, circular, and double-lumened in cross section to improve implant strength, surface area for bioattachment, and adjustability. Sleeves, collars, and bows were employed in the assembly of these implants, with an acrylic condylar head attached when indicated. In 1972, our laboratory developed a mandibular mesh tray, cast in one piece on a single sprue, with preservation of the vertically adjustable ramus. Stainless steel replaced Vitallium because of its greater malleability. Essentially, a lost-wax technique is used to cast the mesh tray. The model of a mandibular segment is duplicated as a refractory model. Mesh wax, made in our own custom-made die, is adapted to the refractory model. The unit is then sprued and invested. The wax is fired our of the mold in a gas furnace. Casting is done by the transferral of molten stainless steel from the crucible to the mold by centrifugal force in an electro-induction casting machine. Other mesh implants that have been developed are made from wire mesh, Dacron mesh, cast Ticonium, and hydroformed titanium.
Dental Implantation, Endosseous↗
A clinical case report: interface analysis of a successful well-functioning transmandibular implant from a cadaver mandible.
Transmandibular implants (TMI) are indicated both for functional reconstruction of the severely atrophic mandible and when routine augmentation is unpredictable. This study investigates the interface of bone around a TMI, retrieved from the cadaver. The TMI had successfully functioned for 7 years. The mandible was immersed in 10% formaldehyde and sectioned into nine appropriate pieces. Samples were embedded in polymethylmethacrylate, and cut around the transosseous posts and cortical screws in both vertical and horizontal sections. Samples were analyzed at 400 MHz (nominal lateral resolution, 2.5 microm) using a UH3 Scanning Acoustic Microscope (Olympus, Tokyo, Japan). The middle of implant specimens 1-4 were cut to 50 microm, and stained by toluidine blue for light microscopy. Dental X-rays showed no bone resorption around any implant. On a 2-mm lateral scan, almost uniform interface space was seen between bone and implant surface in cortical screws. There are wider spaces around the transmandibular posts in the superior area. Histology revealed the small area of direct contact. There is bone marrow space in the interface, with no significant fibrous tissue. We interpret these results at the interface to be because of adaptation for stress distribution.
Adaptation, Physiological↗
Fracture of titanium plates used for mandibular reconstruction following ablative tumor surgery.
PURPOSE: The purpose of this study was to identify reasons for fracture of titanium mandibular reconstruction plates, when used to bridge lateral mandibular defects after ablative tumor surgery. MATERIALS AND METHODS: Sixteen titanium reconstruction plates from sheep mandibles were examined to identify reasons for the plate fractures. The broken plates and the seemingly unbroken plates were examined separately. The plates were removed from the mandibular bone and inspected by dye penetrant examination, metallography, optical microscope, scanning electron microscope, and energy dispersive X-ray spectrometer. Furthermore, axial load fatigue tests were performed in two different environments, air and physiologic salt solution, 0.9% NaCl, to compare titanium behavior in air and the human body. RESULTS: The site of crack initiation was the inner curvature of the reconstruction plate, and the cracks initiated as a result of stress concentration in the shoulder fillet of the plate. The cracks grew in a cyclic manner under masticatory loading of the mandible and the plate. The plate fracture occurred by means of fatigue. The corrosive environment did not affect the failure of the titanium plate, and the fracture was not caused by hydrogen embrittlement. The results revealed that the fatigue properties of the plates may have been impaired by the residual stresses generated in plate bending. CONCLUSIONS: Adjustive bending of the plates, in the surgical operation, may thus be an important cause of fracture of the reconstruction plates, because of generated residual stresses, which affect the mean stress in fatigue loading. To make the plates function without failure the plates should match closely with the three-dimensional shape of the mandible, to avoid any bending in the operative phase.
Animals↗
Finite element analysis of a transmandibular implant.
Finite element analysis (FEA) was used to study the influence of bony height and baseplate effect on the transmandibular implant (TMI). FEA was used to assess the stress distribution in the mandible, with and without a baseplate. Forces were applied to the center of a bar space. The von Mises stress (SEQV) was displayed in bone, and shear stress also was measured. Tensile stress was always seen at the so-called saddle area; compressive stress was seen at the inferior border. Tensile strain at the saddle area of a 6-mm height mandible is always 9.1 times greater (corresponding to more SEQV) than that of an 18-mm mandible. At same bone heights, saddle area stresses are similar with or without a baseplate. However, stress at the lateral transossseous post interface with bone was significantly different between different bone height groups. Shear stress around the lateral transossseous post was smaller than does the SEQV of the same site. Decreased bone height dramatically increases stress at the saddle area independent of the baseplate presence. These data suggest that bone apposition is found in the severely atrophic mandibles. Thus, there is no need for a baseplate in a slight to mild atrophic mandible.
Biomechanical Phenomena↗
Transformation of 3DP gypsum model to HA by treating in ammonium phosphate solution.
Three-dimensional printing (3DP) is a CAD/CAM built-up using ink-jet printing technique. Commercially available 3DP system can form only gypsum model and not for bioceramics. On the other hand, transformation of hardened gypsum into hydroxyapatite (HA) by treatment in ammonium phosphate solution was found lately. In the present study, transformation of the 3DP gypsum block to HA was attempted. However, the fabricated 3DP block was soluble in water. To insolubilize, it was heated at 300 degrees C for 10 min, and then, gypsum was transformed to calcium sulfate hemihydrate, CaSO(4) x 0.5H(2)O. The 3D block was immersed in 1M (NH(4))(3)PO(4) x 3H(2)O solution at 80 degrees C for 1-24 h, and the transformation into HA within 4 h was ascertained. A heat-treated plaster of Paris (POP) block was also investigated for comparison. The unheated POP block consisting of gypsum dihydrate took 24 h to complete the transformation, while the heat-treated POP consisting calcium sulfate hemihydrate promoted the transformation into HA; but the transformed thickness in the block was less than the 3DP block. This is probably due to higher solubility of the hemihydrate than gypsum dihydrate. Accelerated transformation of the 3DP block was also caused by its porous structure, which enabled an easy penetration of the phosphate solution. With the present method, it is possible to transform the fabricated gypsum by 3D printing that is adaptive to the osseous defect into HA prostheses or scaffold.
Bone Substitutes↗
Prospective analysis of masticatory function following lateral mandibulotomy.
Based on clinical impressions and subjective reports by patients, it is generally accepted that a loss of mandibular continuity will result in decreased masticatory function while preserving continuity will result in maintenance of masticatory function. Surprisingly, there is a paucity of well controlled studies objectively evaluating masticatory function to support these statements. The purpose of this study was to objectively evaluate masticatory function in a patient who underwent surgical resection for cure of a tonsillar carcinoma where a lateral mandibulotomy was used. Masticatory performance and swallowing threshold were assessed using a 0.5 gm frito as the test food substance and a sieve analysis. The subject was evaluated pre and post surgery and post prosthetic rehabilitation. When compared with pre surgery function, masticatory function and swallowing threshold were maintained and enhanced with prosthetic treatment 1 year post surgery. Maintenance of mandibular continuity did have functional merit for the subject studied.
Denture, Complete, Upper↗
Use of Kirschner wire in mandible reconstruction: a case report and review of the literature.
Reconstruction of massive defects in head the and neck usually requires different tissues such as skin, bone, and muscle in three-dimensional organization. Therefore, reconstruction of mandibular defects in particular include many difficulties for the head and neck, and for reconstructive surgeons. Various techniques and materials are available, and each has some advantages and disadvantages. But no materials or methods have all the reconstructive requirements. The surgeon's choice of techniques should be safe, simple, economic, and effective. We present a patient with a massive facial defect that was reconstructed successfully by using a 2-mm K wire with a free transverse rectus abdominis myocutaneous flap, and we also review the literature about the use of K wires in mandible fixation and reconstruction. We think that K wires should be kept in mind as a readily available, easily applicable, safe, inexpensive, and stable prosthetic material for mandible reconstruction, especially in cases with advanced disease.
Bone Wires↗
Reconstruction of intraoral mucosal defects with revascularized jejunal segments.
The intraoral mucosa subserves a multitude of structural and functional roles. This paper details the importance of this within the context of reconstruction. The various methods are reviewed historically. Also, both the experimental and clinical basis for using revascularized jejunum as mucosal reconstruction are presented.
Animals↗
Advances in osseointegrated implants for dental and facial rehabilitation following major head and neck surgery.
Osseointegrated implants can be used to facilitate retention stability and support for facial and intraoral prostheses used to restore head and neck defects. Preliminary studies indicate that in nonirradiated maxillectomy patients the success rates are about 75%. In the reconstructed mandible the results appear to be more favorable--over 90% for implants placed in free nonvascularized bone grafts and over 90% for free revascularized bone grafts. Similar high success rates have been observed for most sites used to support facial prostheses. Success rates for auricular sites exceed 95% and for floor of nose sites success rates exceed 90%. Success rates have been lower (77%) for implants placed in the frontal bone for retention of orbital prostheses. Success rates for irradiated bone sites have been lower and range from 60.4% in the maxilla to 68.6% in facial bone sites. Of greater concern is that most implants placed in irradiated sites are beginning to show signs of impending failure.
Combined Modality Therapy↗
Bone scintigraphy in the evaluation of bone grafts used for mandibular reconstruction.
Bone scintigraphy was applied in the follow-up of 24 patients who received bone grafts for reconstruction of the mandible after partial resection. Semiquantitative assessment of the grafts was done with a six-grade scoring system, based on comparison of tracer uptake in the graft and in the calvarium (as an internal control). Sixty-nine bone scans were evaluated. Late planar imaging was carried out in all cases, and single-photon emission tomography (SPET) was performed additionally in 34 of these cases. Complications were observed in four grafts. They occurred less frequently in revascularized grafts than in non-revascularized grafts. Planar scintigrams performed within 14 days after reconstruction showed a significantly higher tracer uptake in grafts with an uncomplicated further course than in those which developed complications. Follow-up scintigrams after 1 and 3 months revealed a significant increase in tracer uptake in grafts with an uncomplicated course. This was not apparent in grafts which developed complications. The tracer uptake was estimated to be higher on the basis of the SPET scans as compared with the planar scintigrams. It is concluded that bone scintigraphy is of prognostic value in the evaluation of bone grafts used for mandibular reconstruction. SPET seems to be more sensitive than planar imaging for the assessment of graft viability.
Bone Transplantation↗
Mandibular angle implants.
A new type of implant designed to increase the angle of the mandible in three dimensions is described. Made of silicone and shaped like a saddle, this implant makes the technique of implantation relatively simple, and its versatility makes it a desirable addition to the tools for skeletal framework reconstruction of the face. The satisfaction rate has been high and the complications easy to manage. The surgical technique consists of an intraoral incision and the development of a subperiosteal pocket at the mandibular angle area, often performed under local anesthesia.
Adult↗
Augmentation mentoplasty: a critical analysis.
An evaluation of the senior author's mentoplasty technique by use of inorganic silicone and acrylic implants is presented, encompassing 16 years of experience. The evaluation was chiefly concerned with the silicone implant and long-term followup observations of its survival and some of its extrusions and complications.
Adolescent↗
[Studies of growth in the jaw-facial region after semilateral mandible resection in childhood during a period of 10 years].
Explore the source record for details and available documents.
Adolescent↗
Case control study in the treatment of obstructive sleep-disordered breathing with an intraoral protrusive appliance.
BACKGROUND: Mandibular protrusive appliances have long been used to treat obstructive sleep apnea/hypopnea syndrome (OSAHS). Their efficacy regarding respiration during sleep varies greatly and remains difficult to predict. In this study the efficacy of a two-splint appliance on nocturnal breathing disorders, sleep profile, and daytime sleepiness were evaluated according to a specially-designed treatment process. PATIENTS AND METHODS: In this study 42 consecutive OSAHS patients who had been fitted with a mandibular protrusive appliance according to a preset treatment regimen were included in a follow-up analysis. The diagnosis and the degree of severity of OSHAS were determined by polysomnography in the sleep laboratory. The treatment regimen was established with the sleep laboratory physician. Treatment regimen included the diagnostic procedure in the sleep laboratory, each patient's dental requirements, the fabrication of the appliance used, and the titration of the mandibular protrusion. After having grown accustomed to the appliance for 24.5 +/- 7.8 days, 34 patients underwent overnight polysomnography. RESULTS: The mean apnea/hypopnea index decreased significantly from 19.6 +/- 12.8 to 3.3 +/- 7.8 events per hour to 83%; the apnea index also improved significantly, as did minimal oxygen saturation and the desaturation index. Changes in sleep profile did not reach statistical significance; the arousal index (p < 0.02) and the subjectively-assessed daytime sleepiness (p < 0.02) decreased significantly. A therapeutically-required AHI of below 5 events per hour was achieved in 88.2% of the patients. CONCLUSION: A significant improvement in the respiratory situation of the vast majority of OSAHS patients, particularly in their AHI, can be achieved when one applies the procedural steps and employs the mandibular protrusive appliance we describe herein.
Adult↗