The effect of cooling procedures on monomer elution from heat-cured polymethyl methacrylate denture base materials

Abstract Objective To evaluate the amount of methyl methacrylate (MMA) released in water from heat-cured polymethyl methacrylate (PMMA) denture base materials subjected to different cooling procedures. Methodology Disk-shaped specimens (Ø:17 mm, h:2 mm) were fabricated from Paladon 65 (PA), ProBase Hot (PB), Stellon QC-20 (QC) and Vertex Rapid Simplified (VE) denture materials using five different cooling procedures (n=3/procedure): A) Bench-cooling for 10 min and then under running water for 15 min; B) Cooling in water-bath until room temperature; C) Cooling under running water for 15 min; D) Bench-cooling, and E) Bench-cooling for 30 min and under running water for 15 min. A, B, D, E procedures were proposed by the manufacturers, while the C was selected as the fastest one. Control specimens (n=3/material) were fabricated using a long polymerization cycle and bench-cooling. After deflasking, the specimens were ground, polished and stored in individual containers with 10 ml of distilled water for seven days (37oC). The amount of water-eluted MMA was measured per container using isocratic ultra-fast liquid chromatography (UFLC). Data were analyzed using Student's and Welch's t-test (α=0.05). Results MMA values below the lower quantification limit (LoQ=5.9 ppm) were registered in B, C, E (PA); E (PB) and B, D, E (QC) procedures, whereas values below the detection limit (LoD=1.96 ppm) were registered in A, D (PA); A, B, C, D (PB); C, D, E (VE) and in all specimens of the control group. A, B (VE) and A, C (QC) procedures yielded values ranging from 6.4 to 13.2 ppm with insignificant differences in material and procedure factors (p>0.05). Conclusions The cooling procedures may affect the monomer elution from denture base materials. The Ε procedure may be considered a universal cooling procedure compared to the ones proposed by the manufacturers, with the lowest residual monomer elution in water.

Comparative analysis of biofilm formation on materials used for the fabrication of implant-supported prostheses

Abstract The purpose of this study was to compare biofilm formation on materials used for the fabrication of implant-supported dental prostheses. Twenty discs (D=15 mm, H=3 mm) were fabricated from one of the following restorative materials: yttria tetragonal zirconia polycrystal (Y-TZP); commercially pure titanium (CP-Ti); or heat-cured polymethyl methacrylate (PMMA). Specimens were polished following standard protocols. A non-contact profilometer (NPFLEX, Bruker, UK) was used to assess the surface roughness of each disk; results were reported as Ra (µm). Five strains of Gram-negative bacteria frequently associated with peri-implantitis, Aggregatibacter actinomycetemcomitans, Candida. albicans, Porphyromonas gingivalis, Prevotella intermedia, and Tannerella forsythia, were cultured on hand-polished discs fabricated from heat-cured PMMA, Y-TZP, or CP-Ti to compare biofilm formation on each type of material. The results were reported as colony-forming units per milliliter (CFU/mL). One-way ANOVA and post hoc tests were used to compare surface roughness and bacterial colonization on the respective materials. Statistical significance was set at a = 0.05. Discs fabricated from Y-TZP had a significantly higher Ra value (350 ± 30 µm) than either PMMA, or CP-Ti discs. Discs fabricated from either Y-TZP and CP-Ti may exhibit less colonization by bacteria associated with peri-mucositis and peri-implantitis. Y-TZP and CP-Ti are suggested materials for fabrication of implant-supported prostheses, considering biofilm formation.

Resumo O objetivo deste estudo foi comparar a formação de biofilme em materiais utilizados na confecção de próteses dentárias implantossuportadas. Vinte discos (D = 15 mm, H = 3 mm) foram confeccionados com um dos seguintes materiais restauradores: zircônia tetragonal policristalina estabilizada por ítrio (Y-TZP); titânio comercialmente puro (CP-Ti); ou polimetilmetacrilato (PMMA). As amostras foram polidas seguindo protocolos padrão. Um perfilômetro sem contato (NPFLEX, Bruker, UK) foi usado para avaliar a rugosidade da superfície de cada disco; os resultados foram relatados como Ra (µm). Cinco cepas de bactérias Gram-negativas freqüentemente associadas a peri-implantite, Aggregatibacter actinomycetemcomitans, Candida. albicans, Porphyromonas gingivalis, Prevotella intermedia e Tannerella forsythia, foram cultivadas em discos polidos à mão feitos de PMMA, Y-TZP ou CP-Ti para comparar a formação de biofilme em cada tipo de material. Os resultados foram relatados como unidades formadoras de colônias por mililitro (UFC/mL). Análise de variância a um fator e testes post hoc foram usados ​​para comparar a rugosidade da superfície e a colonização bacteriana nos respectivos materiais. A significância estatística foi estabelecida em a=0,05. Os discos feitos de Y-TZP tiveram um valor Ra significativamente mais alto (350 ± 30 µm) do que os discos de PMMA ou CP-Ti. Os discos fabricados com Y-TZP e CP-Ti podem apresentar menor colonização por bactérias associadas à perimucosite e peri-implantite. Considerando O Y-TZP e CP-Ti são materiais indicados para a confecção de próteses implantossuportadas, considerando a formação de biofilme

Evaluation and comparison of different polymerization techniques, curing cycles, and thicknesses of two denture base materials

Purpose: The study aimed to compare the effect of different materials, thicknesses, and polymerization methods and cycles, on the surface porosity of acrylic denture base resins. Materials and Methods: Conventional heat-polymerized polymethyl methacrylate (PMMA) and specially designed acrylic resin (Acron MC) were used to make 84 rectangular samples. They were divided into three groups to evaluate and compare the polymerization techniques, curing cycles, and thicknesses of the two denture base materials (28 samples each). Group A contained PMMA samples polymerized using water bath method (control group); Group B contained Acron MC samples polymerized by microwave method, and Group C contained PMMA samples polymerized by microwave method. Each group was further divided based on sample thickness and polymerization cycles. Each sample was scanned for surface porosity and area of each pore was measured using optical microscope. Data was analyzed using ANOVA, Bonferroni, and student t-tests. Unpaired student t-test was performed to compare the means of surface porosity with polymerization cycles and thicknesses among the groups. The power of study was kept at 80%. Results: Group C showed highest mean % of porosity depending on method of polymerization, different polymerization cycles (short and long) and polymerization cycles within the group. Group B showed the highest mean % of porosity depending on thickness and thickness within the groups. Conclusions: Microwavable acrylic resin polymerized by microwave energy exhibited statistically insignificant increase in porosity when compared to conventional heat cured acrylic resin by water bath method. Conventional acrylic resin polymerized by microwave energy exhibited high statistically significant porosity irrespective of sample thickness. There was statistically insignificant increase in porosity depending on sample thickness irrespective of material and method of polymerization.

Corrosion Cast- Comparison of Different Techniques and Materials Used in Corrosion Casting

In medical terms, cast refers to the replica obtained after filling a luminal structure with resin to reproduce its morphology. It can be accomplished by removing the soft tissue around it, termed corrosion or maceration. Corrosion casts form very important material in learning morphology of various structures like- vascular tree, tracheobronchial tree, luminal casts of various organs. Vascular casts have been studied using scanning electron microscopy, which has contributed to understanding the biological processes. If the specimen is fixed after resin injection, it can be used for surgical training, medical teaching etc. In the present review, the authors have tried to analyse the technical aspects of corrosion casting. We have also added note on polyurethane foam cast of coronary vessels, which was carried out in our laboratory.

Simultaneous detection of four kinds of methyl acrylate compounds in workplace air by a portable GC-MS technique / 中国职业医学

OBJECTIVE: To establish a method for simultaneously detecting methyl methacrylate, ethyl methacrylate, n-propyl methacrylate and butyl methacrylate in workplace air by a portable gas chromatography-mass spectrometer(GC-MS) technique. METHODS: The portable GC-MS hand-held probe was used for sampling and detection. Samples were separated with DB-5 rapid chromatographic column in order to maintain retention time and characteristics of the ions, and quantified by standard curve method. RESULTS: The linear correlation of this method was higher than 0.999 0. The minimum detection concentration was 0.03-0.06 mg/m~3, and the minimum quantitation concentration was 0.10-0.20 mg/m~3. The standard recovery rate was 82.22%-91.24%. The within-run and the between-run relative standard deviation were 7.67%-14.63% and 10.40%-13.79% respectively. CONCLUSION: The portable GC-MS technique could be used for qualitative and quantitative detection of above-mentioned four methylacrylate compounds in workplace air.

Embolia pulmonar por metilmetacrilato / Pulmonary embolism due to methyl acrylate

Resumen La vertebroplastia es un procedimiento terapéutico que se usa para reparar lesiones vertebrales. Por su parte, el metilmetacrilato, es un cemento óseo que se inyecta en el hueso esponjoso del cuerpo vertebral durante dicho procedimiento. Se expone el caso de una paciente de sexo femenino de 59 años, con antecedente de artrodesis lumbar, quien consultó por lumbalgia tipo punzada, posterior a caída desde su propia altura. Al examen físico se refirió dolor en región torácica sin signos clínicos de radiculopatía e imposibilidad para la movilización. Los estudios imagenológicos reportaron fractura por acuñamiento de cuerpos vertebrales T12-L1. Se hizo cambio de material de artrodesis que requirió uso adicional de metilmetacrilato para fijación de tornillos canulados. Dos horas posteriores al procedimiento quirúrgico refirió dolor torácico, disnea y taquipnea por lo cual se solicitaron estudios adicionales. Por hallazgos en la radiografía de tórax, se sospechó embolia pulmonar secundaria a metilmetacrilato y por tanto se solicitó tomografía computarizada de tórax. Fue trasladada a la unidad de cuidados intensivos; luego de 72 horas de estancia allí, se hizo ecocardiograma que mostró cavidades derechas dilatadas, hipoquinesia del ventrículo derecho con deterioro de la sístole, insuficiencia tricúspide e hipertensión pulmonar moderada. Se indicó tromboprofilaxis por tres meses y seguimiento por servicios de Medicina interna y Neurocirugía.

Abstract Vertebroplasty is a therapeutic procedure that is used to repair spinal lesions. For its part, methyl acrylate is a bone cement that is injected into the spongy bone of the vertebral body during this procedure. The case is presented of a 59 year-old woman with a history of a lumbar arthrodesis, who consulted due stabbing-type lower back pain, after a fall from her own height. On physical examination, she had pain in the thoracic region with no clinical signs of radiculopathy, and impossibility for movement. The imaging studies reported a fracture due to wedging of vertebral bodies T12-L1. A change was made in the arthrodesis material, which required the additional use of methyl acrylate to fix the cannulated screws. Two hours after the surgical procedure, she referred to chest pain, dyspnoea and tachypnoea, for which further studies were requested. Due to the findings in the chest x-ray, a pulmonary embolism induced by methyl acrylate was suspected, for which a computed tomography scan of the chest was requested. She was transferred to the Intensive Care Unit. After 72 hours of admission there, an echocardiogram was performed that showed dilated right cavities, hypokinesis of the right ventricle with systolic dysfunction, tricuspid insufficiency, and moderate pulmonary hypertension. Thromboprophylaxis was prescribed for three months and follow-up by the Internal Medicine and Neurosurgery departments.

Effects of incorporation of 2.5 and 5 wt% TiO₂ nanotubes on fracture toughness, flexural strength, and microhardness of denture base poly methyl methacrylate (PMMA)

PURPOSE: The aim of this preliminary study was to investigate, for the first time, the effects of addition of titania nanotubes (n-TiO2) to poly methyl methacrylate (PMMA) on mechanical properties of PMMA denture base. MATERIALS AND METHODS: TiO2 nanotubes were prepared using alkaline hydrothermal process. Obtained nanotubes were assessed using FESEM-EDX, XRD, and FT-IR. For 3 experiments of this study (fracture toughness, three-point bending flexural strength, and Vickers microhardness), 135 specimens were prepared according to ISO 20795-1:2013 (n of each experiment=45). For each experiment, PMMA was mixed with 0% (control), 2.5 wt%, and 5 wt% nanotubes. From each TiO2:PMMA ratio, 15 specimens were fabricated for each experiment. Effects of n-TiO2 addition on 3 mechanical properties were assessed using Pearson, ANOVA, and Tukey tests. RESULTS: SEM images of n-TiO2 exhibited the presence of elongated tubular structures. The XRD pattern of synthesized n-TiO2 represented the anatase crystal phase of TiO2. Moderate to very strong significant positive correlations were observed between the concentration of n-TiO2 and each of the 3 physicomechanical properties of PMMA (Pearson's P value ≤.001, correlation coefficient ranging between 0.5 and 0.9). Flexural strength and hardness values of specimens modified with both 2.5 and 5 wt% n-TiO2 were significantly higher than those of control (P≤.001). Fracture toughness of samples reinforced with 5 wt% n-TiO2 (but not those of 2.5% n-TiO2) was higher than control (P=.002). CONCLUSION: Titania nanotubes were successfully introduced for the first time as a means of enhancing the hardness, flexural strength, and fracture toughness of denture base PMMA.

Complicaciones en craneoplastias: hueso autólogo criopreservado vs. polimetilmetacrilato. Análisis retrospectivo de 63 pacientes / Complications in cranioplasties: autologous bone cryopreserved vs. Polymethylmethacrylate. Retrospective analysis of 63 patients

Introducción: se define como craneoplastia a la reparación quirúrgica de los defectos óseos craneanos. En nuestro medio el material utilizado mayormente es el hueso autólogo criopreservado (HACp) y, en caso de no contar con dicho tejido, el Polimetilmetacrilato (PMMA) es de elección. Objetivo: Se plantea un estudio retrospectivo observacional a fin de analizar y comparar complicaciones en pacientes sometidos a craneoplastias con HACp en comparación a un grupo de pacientes a los que se les realizó craneoplastia con PMMA. Materiales y métodos: Se incluyeron pacientes que fueron sometidos a craneopatías durante un periodo de 5 años (2008-2013). El seguimiento delos pacientes fue de al menos 12 meses. Se analizaron variables relacionadas a complicaciones tempranas y tardías. Resultados: 63 pacientes recibieron craneoplastia con HACp (31 pacientes, 52%) o polimetilmetacrilato (31 pacientes, 49%). La tasa de complicación global fue del 36,6%. Doce pacientes (19,04%) requirieron tratamiento quirúrgico. Las complicaciones más frecuentes fueron las colecciones subcutáneas no infectadas (19%), seguidas por las infecciones de heridas (17%). No existen diferencias estadísticamente significativas en cuanto a para complicaciones, tanto globales como en las distintas categorías (p>0,05), para ambas técnicas quirúrgicas. Conclusión: Las craneoplastias tanto con HACp como aquellas con PMMA presentan una alta tasa de complicaciones. En nuestra serie no se hallaron diferencias entre ambos grupos estudiados.

Introduction: cranioplasty is defined as the surgical procedure to cover a skull bone defect. In our institution, we mainly use cryopreserved autologous bone graft (HACp), and if it is not available, polymethylmethacrylate is chosen (PMMA). Objective: We performed an observational retrospective study to assess complications in both groups of patients. Materials and Methods: Patients who underwent cranioplasty between 2008 and 2013 were included. Minimum follow up was 12 months. Variables related with early and late complications were analyzed. Results: 63 patients received cranioplasty consisting of autologous bone graft (32 patients, 52%) or PMMA (31 patients, 48%). The global complications rate was 36.6%. 12 patients (19.04%) required surgical treatment for these complications. The most common complications were sterile persistent subcutaneous fluid collection (19%) and wound infection (17%). No differences in complications rates were found between both groups (p>0.05). Conclusions: Cranioplasty following craniectomy is associated with a high complication rate. In our series, both groups showed no differences in complications rates.

In vitro study of fracture strength of provisional crown materials

PURPOSE: The purpose of this report was to evaluate the effect of the fabrication method and material type on the fracture strength of provisional crowns. MATERIALS AND METHODS: A master model with one crown (maxillary left second premolar) was manufactured from Cr-Co alloy. The master model was scanned, and the data set was transferred to a CAD/CAM unit (Yenamak D50, Yenadent Ltd, Istanbul, Turkey) for the Cercon Base group. For the other groups, temporary crowns were produced by direct fabrication methods (Imident, Temdent, Structur Premium, Takilon, Systemp c&b II, and Acrytemp). The specimens were subjected to water storage at 37degrees C for 24 hours, and then they were thermocycled (TC, 5000x, 5-55degrees C) (n=10). The maximum force at fracture (Fmax) was measured in a universal test machine at 1 mm/min. Data was analyzed by non-parametric statistics (alpha=.05). RESULTS: Fmax values varied between 711.09-1392.1 N. In the PMMA groups, Takilon showed the lowest values (711.09 N), and Cercon Base showed the highest values (959.59 N). In the composite groups, Structur Premium showed the highest values (1392.1 N), and Acrytemp showed the lowest values (910.05 N). The composite groups showed significantly higher values than the PMMA groups (P=.01). CONCLUSION: Composite-based materials showed significantly higher fracture strengths than PMMA-based materials. The CAD-CAM technique offers more advantages than the direct technique.

Evaluation and Comparison of the Transverse Strength of Two Heat Cure Denture Base Resins Repaired with Auto Polymerizing Resin by Wetting with Methyl Methacrylate (MMA) at Different Time Intervals - An In vitro Study.

Aims: Fracture of dentures is a common clinical finding in daily prosthodontic practice, resulting in great inconvenience to both the patient and the dentist. A satisfactory repair should be costeffective, simple to perform, and quick. This study evaluated and compared the transverse strength of two heat cure denture base resins repaired with auto polymerizing resin by wetting with methyl methacrylate (MMA) at different time intervals. Materials and Methods: Stellon and Trevalon denture base materials were used in the study. A total of 200 heat cure acrylic resin specimens (100 specimens each of Stellon and Trevalon acrylic material) with the dimensions of (65 mm x 10 mm x 3 mm) were prepared. The specimens were divided with 10 specimens for each of the test groups (n =10). The test groups were designated as Group A through J. Repair gap of 2 mm was prepared in the centre of the specimen. The repair surface of the specimens were wetted with MMA at different time intervals (1, 2, 3, 4, 5, 10, 15 and 30 minutes) and repaired by using auto polymerizing resin. The transverse strength of the repaired specimens was tested by a 3 point bending test. All data was statistically analyzed with one-way ANOVA, differences within the groups were analyzed by independent sample t -test. Results: The results showed that the significant difference between the specimens wetted with MMA at different time intervals. A gradual increase was shown in the mean transverse strength of repaired specimens wetted from 1 minute to 5 minutes in Stellon and from 1 minute to 10 minutes in Trevalon. Conclusion: Wetting the repair surfaces with MMA for a period of more than 5 minutes and 10 minutes in case of Stellon and Trevalon respectively increases the incidence of adhesive failure in the repaired specimens.

Controlled drug release studies of valsartan using differently sulfonated methacryloxyacetophenone and methyl methacrylate co-polymer resins as drug carriers.

2-methacryloxyacetophenone (MAP) was prepared and subjected to suspension polymerization with methyl methacrylate (MMA) using benzoylperoxide (BPO) as free radical initiator. The differently sulfonated MAPMMA cross-linked copolymer cationic exchange resins were prepared by sulfonation with concentrated sulphuric acid at 70oC. Several characteristics of the prepared resins were evaluated, i.e. FT-IR, the Ion-exchange capacity (IEC), Swelling studies, Particle size distribution and Microscopic morphology. The resin characteristics were altered with degree of sulfonation, providing that differently sulfonated resins could be prepared. The behavior of valsartan (VLN) loading and in vitro release in the USP stimulated gastric and intestinal fluids of the obtained resins were evaluated. The drug loaded in the resin increased with increasing degree of sulfonic group and hence the drug binding site in resin employed. The drug release was lower from the resins with higher degree of sulfonic group due to the increase in the diffusive path depth. The drug release was a little lower in stimulated gastric fluid (SGF) than stimulated intestinal fluids (SIF). The basic group, ionized to a little greater extent in SGF and preferred binding with the resin rather than releasing. Hence, the differently sulfonated resins could be utilized as novel carriers for drug delivery.

Manejo protésico-quirúrgico del paciente hemimandibulectomizado / Prosthetic and surgical treatment of patient previously subjected to hemi-mandibulectomy

Por lo general las mejores opciones de rehabilitación para el paciente hemimandibulectomizado quedan fuera del alcance del poder adquisitivo de la mayoría de ellos, esto hace que el abordaje reconstructivo protésico- quirúrgico para éstos se tenga que restringir al uso de materiales más accesibles tales como el clavo de Kirschner y las prótesis inmediatas de metilmetacrilato, siendo estas últimas las más recomendables por su bajo costo, fácil manejo, por evitar la rotación mandibular y por prevenir la atrofia de los tejidos blandos. Se reporta el caso clínico de un paciente masculino de 25 años de edad el cual ingreso al Servicio de Oncología del Hospital General de México debido a la presencia de un aumento de volumen en el área correspondiente al ángulo mandibular izquierdo, diagnosticándose microscópicamente como un tumor mixto maligno (diagnóstico histopatológico final). Se decidió hacer la hemimandibulectomía de la zona involucrada, con reconstrucción del segmento óseo perdido mediante la colocación de una prótesis inmediata implantada confeccionada con metilmetacrilato de metilo termocurable, la cual fue fijada con alambre para osteosínteis aproximadamente a 3 y 6 milímetros por arriba de la cortical inferior mandibular en ambos bordes de sección.

In general terms, the best rehabilitation options for patients previously subjected to hemi-mandibulectomy are far beyond their financial possibilities. For this reason surgical-prosthetic reconstructive approach is mainly restricted to the use of more affordable materials such as Kirschner wire and methyl-methacrylate immediate prostheses. The latter are widely recommended due to their low cost, ease of handling, and because they prevent soft tissue atrophy. A clinical case is reported in this article: 25 year old male patient seeking treatment at the Oncology Service of the Hospital General de Mexico (Mexico's General Hospital) due to the presence of a volume increase in the area of the left mandibular angle. Microscopic analysis revealed presence of mixed malign tumor ( final histopathological diagnosis). It was decided to perform hemi-mandibulectomy of involved area, with reconstruction of lost bone segment by means of positioning an immediate methyl methacrylate prosthesis (thermosetting methyl). The prosthesis was fixated with osteosynthesis wire at both resection margins, at 3 mm above the cortex.

A Case of Hypersensitivity Pneumonitis with Giant Cells in a Female Dental Technician

OBJECTIVES: Dental technicians are exposed to methyl methacrylate(MMA) and hard metal dusts while working, and several cases of hypersensitivity pneumonitis caused by the exposure have been reported. The authors experienced a case of hypersensitivity pneumonitis in a female dental technician who had 10 years' work experience and report the case with clinical evidence. METHOD: The patient's work, personal, social, and past and present medical histories were investigated based on patient questioning and medical records. Furthermore, the workplace conditions and tools and materials the patient worked with were also evaluated. Next, the pathophysiology and risk factors of pneumonitis were studied, and studies on the relationship between hypersensitivity pneumonitis and a dental technician's exposure to dust were reviewed. Any changes in the clinical course of her disease were noted for evaluation of the work-relatedness of the disease. RESULTS: The patient complained of cough and sputum for 1 year. In addition, while walking up the stairs, the patient was not able to ascend without resting due to dyspnea. She visited our emergency department due to epistaxis, and secondary hypertension was incidentally suspected. Laboratory tests including serologic, electrolyte, and endocrinologic tests and a simple chest radiograph showed no specific findings, but chest computed tomography revealed a centrilobular ground-glass pattern in both lung fields. A transbronchial biopsy was performed, and bronchoalveolar washing fluid was obtained. Among the findings of the laboratory tests, microcalcification, noncaseating granuloma containing foreign body-type giant cells, and metal particles within macrophages were identified histologically. Based on these results, hypersensitivity pneumonitis was diagnosed. The patient stopped working due to admission, and she completely quit her job within 2 months of restarting work due to reappearance of the symptoms. CONCLUSION: In this study, the patient did not have typical radiologic findings, but pathological evaluation of the lung biopsy from the bronchoscope led to the suspicion of pneumonitis. Under the microscope, the sample contained fibrotic changes in the lung, multinucleated giant cells, and particles in macrophages and was diagnosed as dental technician pneumoconiosis by the pathology. Working as a dental technician had directly exposed her to light metal dust and MMA, and her clinical symptoms and radiologic findings subsided after withdrawal from exposure to the workplace. These outcomes led to the diagnosis of hypersensitity pneumonitis due to MMA exposure and strong work-relatedness.

Properties of nanometer silver antibacterial agent and tetrapod-like zinc oxide antibacterial agent against Candida albicans / 中国组织工程研究

10.3969/j.issn.2095-4344.2013.25.007

Bone cement injection for the treatment of thoracolumbar osteoporotic fractures：Common problems in the mature technology / 中国组织工程研究

10.3969/j.issn.2095-4344.2013.26.022

Mechanical properties of dental base resins prepared with the fast automatic dental base resin hydraulic pressure cooker / 实用口腔医学杂志

0.05), the FADRHPC could save a great amount of time and worked automatically. Conclusion: The FADRHPC can simplify manipulation processes and make satisfied dentures.

A Clinical Analysis of Cranioplasty Using Methyl Methacrylate

Cranioplasty has long been performed by many physicians with different materials from the prehistoric era. Among the materials, methyl methacrylate has been known to be the superior to any other substitutes since 1940s in biologic, chemical and physical characteristics and its availability. So the authors review 72 patients who underwent cranioplasty with methyl methacrylate at out hospital from 1985 to 1989. The clinical analyses were as follow : 1) There was male predominance and epidural hematomas, compound, comminuted depressed fractures by traffic accidents or fall down injuries were the main causes of craniectomy. 2) The location of defects was mainly frontal and/or parietal area and average size of defects was 17cm2 in plain skull film measurements. 3) The cosmetic results were satisfactory. 4) Complication rate was 6% and there was no mortality.