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This article highlights the importance of proper suturing of mucosa, gingiva, and skin after surgical procedures and trauma. Several factors play a role in promoting good healing, including optimal tension on the sutured wound, adequate blood flow, and careful selection of suture materials. The selected suture material depends on various factors, such as type of tissue, location of the wound, and healing time. Different suture techniques are discussed, including interrupted sutures, continuous sutures, horizontal and vertical mattress sutures, each with their own specific applications and benefits. Skillfulness in suture techniques and appropriate material selection contribute to effective wound healing and optimal outcomes.
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Procedimientos Quirúrgicos Orales , Técnicas de Sutura , Suturas , Cicatrización de Heridas , Humanos , Procedimientos Quirúrgicos Orales/métodos , Cicatrización de Heridas/fisiología , Encía/cirugía , Mucosa Bucal/cirugíaRESUMEN
The oral mucosa is made up of an epithelium supported by the lamina propria and the submucosa. When the mucosa is damaged, wound healing is characterized by distinct, sequential phases. How does the healing process proceed? Both primary and secondary wound healing, encompasses haemostasis, inflammation, proliferation, and remodelling. Secondary healing also involves a granulation phase to cover the wound. Saliva and the oral microbiome play a role in the healing process, too. Smoking, certain systemic disorders and medication can have a negative effect on the healing process.
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Inflamación , Mucosa Bucal , Humanos , Saliva , Cicatrización de HeridasRESUMEN
A 50-year-old woman presented at the outpatient clinic of the department of oral and maxillofacial surgery with a severe swelling around the left eye 1 week after removal of the second molar in the upper jaw. Despite administration of antibiotics 2 days after the removal of the molar because of periorbital swelling, the inflammation spread to the intraorbital space with eventual loss of the left eye. Timely recognition of the symptoms of (the onset of) an orbital infection after dental treatment and immediate referral to an oral and maxillofacial surgeon and/or ophthalmologist for adequate treatment can be vision-saving. Fortunately, orbital infections with an odontogenic cause are rare.
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Inflamación , Diente Molar , Antibacterianos/uso terapéutico , Femenino , Humanos , Persona de Mediana EdadRESUMEN
We developed a hybrid Monte Carlo self-consistent field technique to model physical gels composed of ABA triblock copolymers and gain insight into the structure and interactions in such gels. The associative A blocks of the polymers are confined to small volumes called nodes, while the B block can move freely as long as it is connected to the A blocks. A Monte Carlo algorithm is used to sample the node configurations on a lattice, and Scheutjens-Fleer self-consistent field (SF-SCF) equations are used to determine the change in free energy. The advantage of this approach over more coarse grained methods is that we do not need to predefine an interaction potential between the nodes. Using this MC-SCF hybrid simulation, we determined the radial distribution functions of the nodes and structure factors and osmotic compressibilities of the gels. For a high number of polymers per node and a solvent-B Flory-Huggins interaction parameter of 0.5, phase separation is predicted. Because of limitations in the simulation volume, we did however not establish the full phase diagram. For comparison, we performed some coarse-grained MC simulations in which the nodes are modeled as single particles with pair potentials extracted from SF-SCF calculations. At intermediate concentrations, these simulations gave qualitatively similar results as the MC-SCF hybrid. However, at relatively low and high polymer volume fractions, the structure of the coarse-grained gels is significantly different because higher-order interactions between the nodes are not accounted for. Finally, we compare the predictions of the MC-SCF simulations with experimental and modeling data on telechelic polymer networks from literature.
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BACKGROUND: Biodegradable fixation systems could reduce or eliminate problems associated with titanium removal of implants in a second operation. AIM: The aim of this study was to compare the long-term (i.e. >5 years postoperatively) clinical performance of a titanium and a biodegradable system in oral and maxillofacial surgery. MATERIALS AND METHODS: The present multicenter Randomized Controlled Trial (RCT) was performed in four hospitals in the Netherlands. Patients treated with a bilateral sagittal split osteotomy (BSSO) and/or a Le Fort-I osteotomy, and those treated for fractures of the mandible, maxilla, or zygoma were included from December 2006 to July 2009. The patients were randomly assigned to either a titanium (KLS Martin) or a biodegradable group (Inion CPS). RESULTS: After >5 years postoperatively, plate removal was performed in 22 of the 134 (16.4%) patients treated with titanium and in 23 of the 87 (26.4%) patients treated with the biodegradable system (P = 0.036, hazard ratio (HR) biodegradable (95% CI) = 2.0 (1.05-3.8), HR titanium = 1). Occlusion, VAS pain scores, and MFIQ showed good and (almost) pain free mandibular function in both groups. CONCLUSION: In conclusion, the performance of the Inion CPS biodegradable system was inferior compared to the KLS Martin titanium system regarding plate/screws removal in the abovementioned surgical procedures. TRIAL REGISTRATION: http://controlled-trials.com ISRCTN44212338.
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Materiales Biocompatibles/química , Materiales Biocompatibles/normas , Cirugía Bucal/instrumentación , Titanio/normas , Adolescente , Adulto , Tornillos Óseos , Femenino , Humanos , Estimación de Kaplan-Meier , Masculino , Mandíbula/cirugía , Fracturas Mandibulares/cirugía , Maxilar/cirugía , Persona de Mediana Edad , Países Bajos , Titanio/química , Adulto Joven , Cigoma/cirugíaRESUMEN
BACKGROUND: Biodegradable fixation systems could reduce/delete the problems associated with titanium plate removal. This means less surgical discomfort, and a reduction in costs. AIM: The aim of the present study was to compare the cost-effectiveness between a biodegradable and a titanium system in Maxillofacial surgery. MATERIALS AND METHODS: This multicenter RCT was performed in the Netherlands from December 2006 to July 2009. Included were 230 patients who underwent a bilateral sagittal split osteotomy (BSSO), a Le Fort-I osteotomy, or a bi-maxillary osteotomy and those treated for fractures of the mandible, maxilla, or zygoma. The patients were randomly assigned to a titanium group (KLS Martin) or to a biodegradable group (Inion CPS). Costs were assessed from a societal perspective. Health outcomes in the incremental cost-effectiveness ratio (ICER) were bone healing (8 weeks) and plate removal (2 years). RESULTS: In 25 out of the 117 patients who were randomized to the biodegradable group, the maxillofacial surgeon made the decision to switch to the titanium system intra-operatively. This resulted in an Intention-To-Treat (ITT-)analysis and a Treatment-Received (TR-) analysis. Both analyses indicated that operations performed with titanium plates and screws had better health outcomes. In the TR-analysis the costs were lower in the biodegradable group, in the ITT-analysis costs were lower in the titanium group. CONCLUSION AND DISCUSSION: The difference in costs between the ITT and the TR analyses can be explained by the intra-operative switches: In the TR-analysis the switches were analysed in the titanium group. In the ITT-analysis they were analysed in the biodegradable group. Considering the cost-effectiveness the titanium system is preferable to the biodegradable system in the regular treatment spectrum of mandibular, Le Fort-I, and zygomatic fractures, and BSSO's, Le Fort-I osteotomies and bimaxillary osteotomies. TRIAL REGISTRATION: Controlled-Trials.com ISRCTN 44212338.
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Materiales Biocompatibles , Análisis Costo-Beneficio , Cirugía Bucal/economía , Cirugía Bucal/métodos , Titanio , Adolescente , Adulto , Placas Óseas , Tornillos Óseos , Femenino , Humanos , Masculino , Persona de Mediana Edad , Resultado del Tratamiento , Cicatrización de Heridas , Adulto JovenRESUMEN
Triblock copolymers, with associative end-groups and a soluble middle block, form flower-like micelles in dilute solutions and a physical gel at higher concentrations. In a gel the middle blocks form bridges between domains/nodes that contain the ends. We combine the self-consistent field theory with a simple molecular model to evaluate the pair potential between the nodes. In this model the end-groups are forced to remain in nodes and the soluble middle blocks are in solution. When the distance between the centres of the nodes is approximately the corona diameter, loops can transform into bridges, and the pair potential is attractive. Due to steric hindrance, the interaction is repulsive at smaller distances. Till now a cell-model has been used wherein a central node interacts through reflecting boundary conditions with its images in a spherical geometry. This artificial approach to estimate pair potentials is here complemented by more realistic three-gradient SCF models. We consider the pair interactions for (i) two isolated nodes, (ii) nodes positioned on a line (iii) a central node surrounded by its neighbours in simple cubic ordering, and (iv) a central node in a face centred cubic configuration of its neighbours. Qualitatively, the cell model is in line with the more refined models, but quantitative differences are significant. We also notice qualitative differences for the pair potentials in the specified geometries, which we interpret as a breakdown of the pairwise additivity of the pair potential. This implies that for course grained Monte Carlo or molecular dynamics simulations the best choice for the pair potentials depends on the expected node density.
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Micelas , Modelos Teóricos , Simulación de Dinámica Molecular , Polímeros/química , Método de Montecarlo , SolucionesRESUMEN
Biodegradable fixation systems could reduce or eliminate the problems associated with removal of titanium plates. A multicenter randomised controlled trial (RCT) was performed in the Netherlands from December 2006-July 2009, and originally 230 injured and orthognathic patients were included. The patients were randomly assigned to either a titanium control group (KLS Martin) or to a biodegradable test group (Inion CPS). The aim of the present study was to compare the long-term skeletal stability of advancement bilateral sagittal split osteotomies (BSSO) of a biodegradable system and a titanium system. Only patients from the original RCT who were at least 18 years old and who had a BSSO advancement osteotomy were included. Those who had simultaneous Le Fort I osteotomy or genioplasty were excluded. Analysis of skeletal stability was made by digital tracing of lateral cephalograms. Long-term skeletal stability in BSSO advancement did not differ significantly between patients treated with biodegradable plates and screws and those treated with titanium plates and screws. Given the comparable amount of relapse, the general use of Inion CPS in the treatment of BSSO advancement should not be discouraged. On the basis of other properties a total picture of the clinical use can be obtained; the short-term stability, the intraoperative switches, the number of plates removed and cost-effectiveness. Trial registration of original RCT: http://www.controlled-trials.com; ISRCTN 44212338.
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Implantes Absorbibles , Materiales Biocompatibles/química , Placas Óseas , Tornillos Óseos , Osteotomía Sagital de Rama Mandibular/métodos , Titanio/química , Adolescente , Adulto , Cefalometría/métodos , Estudios de Cohortes , Femenino , Humanos , Estudios Longitudinales , Masculino , Mandíbula/patología , Fracturas Mandibulares/cirugía , Fracturas Maxilares/cirugía , Persona de Mediana Edad , Hueso Nasal/patología , Osteotomía Sagital de Rama Mandibular/instrumentación , Estudios Prospectivos , Silla Turca/patología , Resultado del Tratamiento , Adulto Joven , Fracturas Cigomáticas/cirugíaRESUMEN
Spontaneous paresthesia of the mental nerve is considered an ominous clinical sign. Mental nerve paresthesia has also been referred to as numb chin syndrome. Several potentially different factors have been investigated for their role in interfering with the inferior alveolar nerve (IAN) and causing mental nerve neuropathy. In the present case, the patient had an elongated calcified styloid process that we hypothesized had caused IAN irritation during mandibular movement. This eventually resulted in progressive loss of sensation in the mental nerve region. To our knowledge, this dynamic irritation, with complete recovery after resection of the styloid process, has not been previously reported.
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Nervio Mandibular/patología , Síndromes de Compresión Nerviosa/complicaciones , Parestesia/etiología , Humanos , Masculino , Persona de Mediana Edad , Tomografía Computarizada por Rayos XRESUMEN
OBJECTIVE: The aim of this study was to evaluate the influence of different splitting techniques, namely, "mallet and chisel" versus "spreading and prying", used during bilateral sagittal split osteotomy (BSSO) on postoperative hypoesthesia outcomes. STUDY DESIGN: We systematically searched the PubMed and Cochrane databases (from January 1957 to November 2012) for studies that examined postoperative neurosensory disturbance (NSD) of the inferior alveolar nerve (IAN) after BSSO. RESULTS: Our initial PubMed search identified 673 studies, of which, 14 met our inclusion criteria. From these 14 studies, 3 groups were defined: (1) no chisel use (4.1% NSD/site), (2) undefined chisel use (18.4% NSD/site), and (3) explicit chisel use along the buccal cortex (37.3% NSD/site). CONCLUSION: Study heterogeneity and a frequent lack of surgical detail impeded our ability to make precise comparisons between studies. However, the group of studies explicitly describing chisel use along the buccal cortex showed the highest incidence of NSD. Moreover, comparison of the study that did not use chisels with the 2 studies that explicitly described chisel use revealed a possible disadvantage of the "mallet and chisel" group (4.1% versus 37.3% NSD/site). These results suggest that chisel use increases NSD risk after BSSO.
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Hipoestesia/etiología , Nervio Mandibular/fisiopatología , Osteotomía Sagital de Rama Mandibular/métodos , Complicaciones Posoperatorias , Humanos , Osteotomía Sagital de Rama Mandibular/efectos adversos , Osteotomía Sagital de Rama Mandibular/instrumentación , Traumatismos del Nervio Trigémino/etiologíaRESUMEN
In a recent RCT comparing biodegradable (Inion CPS) with titanium (KLS Martin) plates and screws for fixation of osteotomies or fractures, we found that in 21% of the cases the surgeon decided intra-operatively to switch from biodegradable to titanium. The aim of the current retrospective cohort study was to analyse the reasons for these switches in order to find predictor variables that may be helpful in the decision to use biodegradable devices or not. The surgeons' opinion about the biodegradable system, and if there was a learning curve in the application of the biodegradable system were also investigated. All variables were assessed during the original RCT by using a questionnaire that was completed by the OMF surgeon directly post-operatively. For the outcome variable "surgeons' opinion" a separate questionnaire was used. Regarding the predictor variables a mandibular fracture had a higher risk of switching compared to a BSSO. However, looking at the reasons for these switches no firm conclusions can be drawn. There was a subjective learning curve to acquire the application-skills for the biodegradable system. There were no changes in isolated Le-Fort-I osteotomies despite the fact that the biodegradable system seems more difficult to apply in the midface. Inadequate stability was the main reason for switching. This can be material-related, or related to inexperience with or lack of confidence in the system, or impatience of the surgeon. A learning curve and personal preferences probably play an important role in the decision to switch. We think that with more patience and more experience it should be possible to increase both user comfort and confidence in the biodegradable system of Inion CPS, which likely will decrease the number of intra-operative switches.
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Implantes Absorbibles , Toma de Decisiones , Dispositivos de Fijación Ortopédica , Adolescente , Adulto , Actitud del Personal de Salud , Materiales Biocompatibles/química , Placas Óseas , Tornillos Óseos , Competencia Clínica , Estudios de Cohortes , Femenino , Estudios de Seguimiento , Humanos , Aprendizaje , Masculino , Fracturas Mandibulares/cirugía , Fracturas Maxilares/cirugía , Persona de Mediana Edad , Osteotomía Le Fort/instrumentación , Osteotomía Sagital de Rama Mandibular/instrumentación , Estudios Retrospectivos , Cirugía Bucal , Titanio/química , Adulto Joven , Fracturas Cigomáticas/cirugíaRESUMEN
Biodegradable osteosynthesis could reduce/delete the problems associated with titanium plate removal. The aim of the present study was to compare the clinical performance in the first 2 post-operative years between a biodegradable and a titanium system in oral and maxillofacial surgery. The multicenter randomized controlled trial (RCT) was performed in the Netherlands from December 2006 to July 2009. Included were 230 patients who underwent a bilateral sagittal split osteotomy (BSSO) and/or a Le Fort-I osteotomy and those treated for fractures of the mandible, maxilla, or zygoma. The patients were randomly assigned to a titanium group (KLS Martin) or to a biodegradable group (Inion CPS). Plate removal was necessary in 16 of the 134 patients (11.9%) treated with titanium and in 21 of the 87 patients (24.1%) treated with the biodegradable system within the first 2 post-operative years [p = .016, HR biodegradable (95% CI) = 2.2 (1.1-4.2), HR titanium = 1]. Occlusion, VAS, and MFIQ scores showed that both groups had good mandibular function and were (almost) free of pain 1 and 2 years post-operatively (http://controlled-trials.com ISRCTN 44212338).
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Implantes Absorbibles , Materiales Biocompatibles/química , Fijación Interna de Fracturas/instrumentación , Procedimientos Quirúrgicos Ortognáticos/instrumentación , Dispositivos de Fijación Ortopédica , Titanio/química , Adolescente , Adulto , Oclusión Dental , Remoción de Dispositivos , Huesos Faciales/lesiones , Huesos Faciales/cirugía , Femenino , Estudios de Seguimiento , Fijación Interna de Fracturas/métodos , Humanos , Masculino , Mandíbula/fisiología , Fracturas Mandibulares/cirugía , Fracturas Maxilares/cirugía , Persona de Mediana Edad , Procedimientos Quirúrgicos Ortognáticos/métodos , Osteotomía Le Fort/instrumentación , Osteotomía Le Fort/métodos , Osteotomía Sagital de Rama Mandibular/instrumentación , Osteotomía Sagital de Rama Mandibular/métodos , Dimensión del Dolor , Dolor Postoperatorio/etiología , Fracturas Craneales/cirugía , Factores de Tiempo , Resultado del Tratamiento , Adulto Joven , Fracturas Cigomáticas/cirugíaRESUMEN
OBJECTIVE: To analyze the splitting pathways of the (lingual) fracture lines during a bilateral sagittal split osteotomy (BSSO) in cadaveric pig mandibles. STUDY DESIGN: A BSSO was performed using splitters and separators. Special attention was paid to end the horizontal medial cut at the deepest point of the entrance of the mandibular foramen. RESULTS: Of all lingual fractures, 95% ended in the mandibular foramen. Forty percent of these fractures extended through the mandibular canal and 40% extended inferiorly along the mandibular canal. CONCLUSION: Almost all lingual fracture lines ended in the mandibular foramen, most likely due to the placement of the medial cut in the concavity of the mandibular foramen. The mandibular foramen and canal could function as the path of least resistance in which the splitting pattern is seen. We conclude that a consistent splitting pattern was achieved without increasing the incidence of possible sequelae.
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Mandíbula/cirugía , Osteotomía Sagital de Rama Mandibular/métodos , Animales , Osteotomía Sagital de Rama Mandibular/efectos adversos , Osteotomía Sagital de Rama Mandibular/instrumentación , Proyectos Piloto , Reproducibilidad de los Resultados , Sus scrofa/cirugía , Porcinos , Traumatismos del Nervio Trigémino/prevención & controlRESUMEN
An unfavourable fracture, known as a bad split, is a common operative complication in bilateral sagittal split osteotomy (BSSO). The reported incidence ranges from 0.5 to 5.5%/site. Since 1994 we have used sagittal splitters and separators instead of chisels for BSSO in our clinic in an attempt to prevent postoperative hypoaesthesia. Theoretically an increased percentage of bad splits could be expected with this technique. In this retrospective study we aimed to find out the incidence of bad splits associated with BSSO done with splitters and separators. We also assessed the risk factors for bad splits. The study group comprised 427 consecutive patients among whom the incidence of bad splits was 2.0%/site, which is well within the reported range. The only predictive factor for a bad split was the removal of third molars at the same time as BSSO. There was no significant association between bad splits and age, sex, class of occlusion, or the experience of the surgeon. We think that doing a BSSO with splitters and separators instead of chisels does not increase the risk of a bad split, and is therefore safe with predictable results.
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Mandíbula/cirugía , Osteotomía Sagital de Rama Mandibular/efectos adversos , Adolescente , Adulto , Placas Óseas , Tornillos Óseos , Femenino , Estudios de Seguimiento , Mentoplastia , Humanos , Hipoestesia/prevención & control , Complicaciones Intraoperatorias , Técnicas de Fijación de Maxilares , Masculino , Maloclusión Clase II de Angle/cirugía , Maloclusión de Angle Clase III/cirugía , Persona de Mediana Edad , Miniaturización , Tercer Molar/cirugía , Procedimientos Quirúrgicos Ortognáticos/efectos adversos , Procedimientos Quirúrgicos Ortognáticos/instrumentación , Osteotomía Le Fort , Osteotomía Sagital de Rama Mandibular/instrumentación , Complicaciones Posoperatorias/prevención & control , Estudios Retrospectivos , Factores de Riesgo , Extracción Dental , Adulto JovenRESUMEN
The use of thin layers of a surface bound (polyelectrolyte) hydrogels for measuring the concentration of metal ions from electrolyte solutions is our motivation for modeling such hydrogels. The gels are composed of polymeric species with conformational degrees of freedom on the nanometer scale. The polymer conformations are affected by the presence of cross-links in the gel on a five to ten times larger length scale, and the repulsive interactions generated by the charges along the chains. Here we present a hybrid computational Monte Carlo Self-consistent field (MC-SCF) approach to model such hydrogels. The SCF formalism is used to evaluate the conformational properties of the chains, implementing a freely jointed chain model, in between featureless cross-links. The Monte Carlo simulation method is used to sample the (restricted) translational degrees of freedom of the cross-links in the gel. We consider the case that the polymers in the gel have an affinity for surface positioned at the edge of the simulation volume. The polymer density decays as a power-law from the surface to the gel-density with an exponent close to -4/3. The gel features relatively large density fluctuations which is natural for a gel with a low density (φ ≈ 0.035), a low degree of cross-linking (average of three chainparts per cross-link), and relatively large chains (N = 50) in between the cross-links. Some parts of the gel can break loose from the gel and sample the adjoining volume. Representative snapshots exemplify large density fluctuations, which explain the large pore size distribution observed in experimental counterparts.
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Geles/química , Membranas Artificiales , Simulación de Dinámica Molecular , Polímeros/química , Adsorción , Electrólitos/química , Método de Montecarlo , Propiedades de SuperficieRESUMEN
Biodegradable fixation systems could reduce or delete the problems associated with metallic systems, since removal is not necessary. The aim of this study was to establish the effectiveness and safety of biodegradable plates and screws as potential alternatives to metallic ones. This multi-center randomized controlled trial was conducted from December 2006 to July 2009. Included were patients who underwent mandibular and/or Le Fort I osteotomies and those with fractures of the mandible, maxilla, and zygoma. The patients were assigned to a titanium control group (KLS Martin) or to a biodegradable test group (Inion CPS). The primary outcome measure was 'bone healing 8 weeks post-operatively'. The Intention-To-Treat (ITT) analysis of 113 patients in the titanium group and 117 patients in the biodegradable group yielded a significant difference (p < 0.001), primarily because in 25 patients (21%) who were randomized to the biodegradable group, the surgeon made the decision to switch to titanium intra-operatively. Despite this 'inferior' primary outcome result, biodegradable plates and screws could be safely used when it was possible to apply them. The benefits of using biodegradable systems (fewer plate removal operations) should be confirmed during a follow-up of minimally 5 years (Controlled-trials.com ISRCTN number 44212338).
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Implantes Absorbibles , Placas Óseas , Tornillos Óseos , Procedimientos Quirúrgicos Orales/instrumentación , Implantes Absorbibles/efectos adversos , Materiales Biocompatibles , Distribución de Chi-Cuadrado , Humanos , Fracturas Mandibulares/cirugía , Fracturas Maxilares/cirugía , Osteotomía Le Fort/instrumentación , Osteotomía Sagital de Rama Mandibular/instrumentación , Estudios Prospectivos , Titanio , Resultado del Tratamiento , Cicatrización de Heridas , Fracturas Cigomáticas/cirugíaRESUMEN
A 90-year old woman attended a department of Oral and Maxillofacial Surgery with a tongue that had been painful for at least 3 months. Clinical examination revealed extensive bullous and ulcerative lesions located on the tongue, the oral vestibule and the buccal mucosa on both sides. A variety of diseases may be causative of ulcerative stomatitis: autoimmune diseases (like Pemphigus vulgaris, Erosive Lichen Planus, SLE or M. Crohn), or a viral, bacterial or mycotical infection, vitamin deficiency, a toxic reaction to medication or an immune deficiency. After an extensive, clinical examination, a definitive diagnosis still had not been achieved. The patient suffered from osteoporosis, for which she used alendronate (Fosamax). A study of the literature described a possible relationship between the occurrence of oral ulcers and the use of oral biphosphonates. Since a toxic reaction to alendronate was suspected, the use of Fosamax tablets was suspended. Three months later a complete recovery of the oral mucosa was observed.
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Alendronato/efectos adversos , Mucosa Bucal/efectos de los fármacos , Mucosa Bucal/patología , Anciano de 80 o más Años , Alendronato/uso terapéutico , Femenino , Humanos , Osteoporosis/tratamiento farmacológicoRESUMEN
The in vivo local reaction of as-polymerized poly-L-lactide composed of 96% L-lactide and 4% D-lactide (PLA96) was investigated by histology at 2, 13 and 26 weeks after subcutaneous implantation in rats. In order to simulate possible end stage reactions the PLA96 was also predegraded in vitro until approximately 50% weight loss. The local reaction of predegraded PLA (PLA96(168)) was compared to the local reaction of polyethylene (PE) and non-predegraded PLA (PLA96). For PE and PLA96 a mild local reaction was observed at all time points consisting of a minimal layer of macrophage like cells with incidentally multinucleated giant cells at the implant interface, surrounded by a mild connective tissue capsule. For PLA96 at weeks 13 and 26 some minimal alterations in terms of degradation and ingrowth of cells was noted. The in vitro incubation (90 degrees C for 168 h) of PLA96(168) resulted for the thin 0.2 mm samples in complete degradation. Predegraded 0.5, 1.0 and 2.0 mm PLA96(168) samples were implanted and evaluated. The 1.0 and 2.0 mm samples could be evaluated for all time points investigated, but some 0.5 mm PLA96(168) samples were already completely resorbed at week 2 after implantation. In general, responses found for the predegraded PLA96(168) at weeks 2, 13 and 26 were similar with a pronounced macrophage infiltrate containing birefringent material, encapsulation of polymer fragments, and the presence of a debris area consisting of polymer and cellular remnants. In lymph nodes foamy macrophages with birefringent material were only observed in lymph nodes draining sites with predegraded PLA96(168). Immunohistochemistry was performed for further characterization of the cellular infiltrate. At the implant interface of the non-degrading PE and PLA96, ED1 and OX6 (MHC class II) positive cells were identified. In the capsule macrophage like cells expressed all three macrophage markers ED1, ED2, and ED3. CD4 and CD8 positive cells, indicating T helper and T supressor/cytotoxic cells, respectively, could be observed in low numbers, CD4 more than CD8. Both CD4 and CD8 were occasionally observed within the degrading PLA96(168) implant. Polymorphonuclear neutrophilic granulocytes were mainly observed at 2 weeks after implantation. We showed that predegradation could be used as a means to study late tissue reactions to polymers. Complete degradation may be studied with relatively thin implants, but this may lead to rather optimistic interpretation of resorption periods. When materials are intended to be used for screws and/or plates for bone fixation, implants of at least 1.0-2.0 mm thickness should be used as these may show a more realistic representation of the resorption characteristics of the material under investigation.
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Implantes Absorbibles/efectos adversos , Materiales Biocompatibles/efectos adversos , Citocinas/inmunología , Reacción a Cuerpo Extraño/inmunología , Reacción a Cuerpo Extraño/patología , Poliésteres/efectos adversos , Animales , Reacción a Cuerpo Extraño/etiología , Implantes Experimentales/efectos adversos , Masculino , Ensayo de Materiales/métodos , Ratas , Ratas WistarRESUMEN
Addition of ammonium sulphate to nitrogen-depleted yeast cells resulted in a transient increase in Ins(1,4,5)P(3), with a maximum concentration reached after 7-8 min, as determined by radioligand assay and confirmed by chromatography. Surprisingly, the transient increase in Ins(1,4,5)P(3) did not trigger an increase in the concentration of intracellular calcium, as determined in vivo using the aequorin method. Similar Ins(1,4,5)P(3) signals were also observed in wild-type cells treated with the phospholipase C inhibitor 3-nitrocoumarin and in cells deleted for the only phospholipase C-encoding gene in yeast, PLC1. This showed clearly that Ins(1,4,5)P(3) was not generated by phospholipase C-dependent cleavage of PtdIns(4,5)P(2). Apart from a transient increase in Ins(1,4,5)P(3), we observed a transient increase in PtdIns(4,5)P(2) after the addition of a nitrogen source to nitrogen-starved glucose-repressed cells. Inhibition by wortmannin of the phosphatidylinositol 4-kinase, Stt4, which is involved in PtdIns(4,5)P(2) formation, did not affect the Ins(1,4,5)P(3) signal, but significantly delayed the PtdIns(4,5)P(2) signal. Moreover, wortmannin addition inhibited the nitrogen-induced activation of trehalase and the subsequent mobilization of trehalose, suggesting a role for PtdIns(4,5)P(2) in nitrogen activation of the fermentable-growth-medium-induced signalling pathway.