Adhesión a dentina parte I: características del sustrato y sistemas adhesivos / Dentin bonding part I: substrate characteristics and bonding systems

La Odontología Restauradora contemporánea no puede concebirse sin la adhesión de los materiales restauradores a las estructuras dentarias. En mu-chos procedimientos restauradores, no sólo el esmal-te sino también la dentina se encuentra involucrada, por lo tanto, la adhesión a esta última juega un rol cla-ve en el éxito clínico. No obstante, todavía supone un gran desafío lograr una adhesión estable y predeci-ble en el tiempo. El propósito del presente artículo es analizar las características principales de la dentina como sustrato adhesivo y describir los sistemas ad-hesivos actuales y sus mecanismos de acción (AU)

Contemporary Restorative Dentistry cannot be conceived without the adhesion of restorative materials to dental structures. In many restorative procedures not only the enamel, but also the dentin is involved, therefore dentin bonding plays a key role in their success. However, it is still a great challenge to achieve stable and predictable dentin bonding over time. The aim of this article is to analyze the main characteristics of dentin as an adhesive substrate and to describe current adhesive systems and their bonding mechanisms (AU)

Exposición compleja de placa craneal / Complex exposure of cranial plate

Es recomendable que los pacientes con antecedentes de trauma craneal moderado o grave, con pérdida de fragmentos de calota, que deben reparar con posterior craneoplastia, la realicen luego de 3 a 6 meses, reduciendo el riesgo de infección y de hipertensión endocraneana. Los materiales a utilizar son diversos; y para evitar la reapertura es fundamental un cierre sin tensión, en dos planos y sin tejido desvitalizado. Las infecciones son raras; son más frecuentes cuando la craneopatía se realizó dentro del 1er año del trauma. Otra complicación es la úlcera crónica, de manejo muy complejo. Material y métodos. Paciente de 58 años, sufrió un traumatismo encefalocraneano con pérdida de conocimiento en el año 2011, por accidente de tránsito; craneoplastia realizada a 8 meses del trauma, posterior ulceración sobre líneas de incisión en dos oportunidades, reparado en ambas con colgajos locales, conservando la placa craneal. La paciente consultó presentando nueva ulceración parietal izquierda y adelgazamiento del cuero cabelludo y translucencia del material frontoparietal izquierdos; sin infección local; y múltiples cicatrices remanentes. Se retiró la placa craneal, y a dos años se realizó expansión con insuflados lentos controlados con la signosintomatología que presentaba la paciente. Al 3er mes se recolocó nueva placa de titanio y cobertura con colgajos del cuero cabelludo. Discusión. La expansión tisular del cuero cabelludo es un método simple, con baja frecuencia de complicaciones si la técnica es delicada y atendemos la signosintomatología del paciente. Conclusión. El trabajo conjunto multidisciplinario, es la piedra angular para obtener resultados óptimos en la reconstrucción de lesiones complejas.

Patients with a history of moderate or severe skull trauma, with loss of shell fragments, which must be repaired with subsequent cranioplasty, it is recommended to perform it after 3 to 6 months, reducing the risk of infection and endocranial hypertension. The materials to use are diverse; and to avoid reopening, a tension-free closure is essential, in two planes and without devitalized tissue. Infections are rare, being more frequent when the craniopathy took place within 1 year of the trauma. Another complication is the chronic ulcer, very complex to handle. Material and methods. Fifty eight year-old patient, suffered a traumatic brain injury with loss of consciousness in 2011, due to a traffic accident; craneoplasty performed 8 months after trauma, subsequent ulceration on incision lines on two occasions, both repaired with local flaps, preserving the cranial plate. The patient consulted presenting a new left parietal ulceration, and thinning of the scalp and translucency of the left fronto-parietal material; no local infection; and multiple remaining scars. The cranial plate was removed, and two years later, expansion was performed with slow insufflants controlled with the patient's symptom sign. At the 3rd month, a new titanium plate was replaced and covered with flaps of the scalp. Discussion. Tissue expansion of the scalp is a simple method, with little frequency of complications if the technique is delicate, and we attend to the patient's sign-symptomatology. Conclusion. Multidisciplinary joint work is the cornerstone for obtaining optimal results in the reconstruction of complex injuries.

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.

Reação alérgica a resina acrílica em paciente com coroa provisória: relato de caso / Allergic reaction to acrylic resin in a patient with a provisional crown: case report

As resinas acrílicas são amplamente utilizadas na odontologia, especialmente em ortodontia e prótese. Este artigo relata o caso de um paciente de 33 anos de idade, do gênero masculino que relatava desconforto e dores na região de pré-molar superior esquerdo após a colocação de um provisório, com presença de uma lesão eritomatosa. Após biópsia incisional constatouse a processo inflamatório crônico inespecífico. A causa apresentada para tal patologia foi o provisório confeccionado com resina acrílica autopolimerizável à base de metil-metacrilato. (AU)

Acrylic resins are widely used in dentistry, especially in orthodontics and prosthetics. Patients: this article reports the case of a leukodermic 33-year-old male who reported discomfort and pain due to an erythematous lesion in the upper first left premolar (24) after the placement of an acrylic resin temporary restoration. Discussion: The signs and symptoms presented by the patient and his report of visiting the rural countryside generated concern regarding the possible diagnosis, which led to a more invasive biopsy to differentiate allergic inflammation from a paracoccidioidomycosis. Biopsy revealed a chronic inflammatory process. Conclusion: the pathology was caused by contact with methyl methacrylate-based provisional acrylic resin. After cementation of the final crown, the inflammatory signs and symptoms disappeared .(AU)

Preenchimentos estéticos na cirurgia ortognática: há indicações? / Aesthetic augmentation in orthognathic surgery: are there indications?

Introdução: resultados estéticos na cirurgia ortognática são um dos principais objetivos dos pacientes, ortodontistas e cirurgiões. A correção da deformidade óssea maxilomandibular, geralmente, restabelece as funções do sistema estomatognático e a estética facial. No entanto, nem sempre obtém-se simetria e projeção desejada dos tecidos moles somente com a movimentação óssea. Nesse sentido, o preenchimento com o polimetilmetacrilato (PMMA) atua como coadjuvante na tentativa de se obter contornos faciais que alcancem as expectativas estéticas dos pacientes e profissionais. Objetivo: o presente artigo revisa a utilização do metilmetacrilato como material de preenchimento na região craniofacial, abordando a sua perspectiva histórica, vantagens e aspectos biológicos. As principais indicações são ilustradas com figuras e casos clínicos

Cranioplasty with Methylmethacrylate in Plagiocephaly

No abstract available.

Protótipo para realização de cranioplastia de baixo custo / Prototype for cranioplasty low cost in postoperative decompressive craniotomy

Objetivo: O presente trabalho propõe uma técnica para realização de cranioplastia com metilmetacrilato em formas pré-moldadas e esterilizadas visando evitar cranioplastia com prototipagem pré-moldada.Método: Conforme rotina apresentada, o flap ósseo realizado para craniotomia descompressiva é armazenado em recipientes com formol e enviado para o serviço de patologia do hospital. Quando realizamos a cranioplastia, utilizamos o flap ósseo armazenado para realização dos moldes que serão utilizados na cranioplastia. Resultado: O resultado estético é muito bom e os índices de complicação e infecção são baixos. Conclusão: Apresenta resultados estéticos semelhantes aos casos de prototipagemcom baixo custo na confecção.

Objective: This paper proposes a technique for cranioplasty with methyl methacrylate and molded into shapes pre-sterilized to avoid aiming cranioplasty with pre molded prototyping. Method: As presented routine bone flap performed to decompressive craniectomy is stored in containers with formalin and sent to the pathology service of the hospital. When we performed the cranioplasty, we used the bone flap stored for realization of molds that will be used in cranioplasty. Result: The aesthetic result is very good and the rates of complication and infection are lo

Candida albicans biofilms and MMA surface treatment influence the adhesion of soft denture liners to PMMA resin

The effect of Candida albicans biofilms and methyl methacrylate (MMA) pretreatment on the bond strength between soft denture liners and polymethyl methacrylate (PMMA) resin was analyzed. Specimens were prepared and randomly divided with respect to PMMA pretreatment, soft liner type (silicone-based or PMMA-based), and presence or absence of a C. albicans biofilm. Samples were composed of a soft denture liner bonded between two PMMA bars. Specimens (n = 10) were incubated to produce a C. albicans biofilm or stored in sterile PBS for 12 days. The tensile bond strength test was performed and failure type was determined using a stereomicroscope. Surface roughness (SR) and scanning electron microscopy (SEM) analysis were performed on denture liners (n = 8). Highest bond strength was observed in samples containing a silicone-based soft liner and stored in PBS, regardless of pretreatment (p < 0.01). Silicone-based specimens mostly underwent adhesive failures, while samples containing PMMA-based liners predominantly underwent cohesive failures. The silicone-based specimens SR decreased after 12 days of biofilm accumulation or PBS storage, while the SR of PMMA-based soft liners increased (p < 0.01). The PMMA-based soft liners surfaces presented sharp valleys and depressions, while silicone-based specimens surfaces exhibited more gentle features. In vitro exposure to C. albicans biofilms reduced the adhesion of denture liners to PMMA resin, and MMA pretreatment is recommended during relining procedures.

Augmentation of craniofacial defects using alloplastic material / Técnica de aumento para la reparación de defectos craneofaciales usando materiales aloplásticos

BACKGROUND: Alloplastic materials are increasingly being used in augmentation of craniofacial defects because of its ready availability, good aesthetic outcome and absence of donor site morbidity. This paper highlights experience in the use of heat-cured acrylic in augmentation cranioplasty. SUBJECTS AND METHOD: The management of three patients with anterior skull defect who presented at the Dental and Maxillofacial Surgery Clinic of the Aminu Kano Teaching Hospital over a five-year period is presented. RESULTS: There was good aesthetic outcome in all the patients and no complications were recorded. CONCLUSION: Augmentation of craniofacial defects using customized prefabricated heat-cured acrylic provides patients with a durable, stable and structural repair ofcraniofacial defects with good aesthetic outcome.

ANTECEDENTES: Los materiales aloplásticos son usados cada vez más en la técnica de aumento para la reparación de defectos craneofaciales, debido a su disponibilidad inmediata, buen resultado estético y ausencia de morbosidad del sitio donante. Este trabajo destaca nuestra experiencia en el uso de acrílico curado por calor en las técnicas de aumento en la craneoplastia. SUJETOS Y MÉTODOS: Se describe el tratamiento de tres pacientes con defectos del cráneo anterior, que asistieron a la Clínica de Cirugía Maxilofacial y Dental del Hospital Docente Aminu Kano por un período de más de cinco años. RESULTADOS: Hubo un buen resultado estético en todos los pacientes y no se reportaron complicaciones. CONCLUSIÓN: La técnica de aumentación para los defectos craneofaciales, utilizando acrílico prefabricado curado con calor, proporciona a los pacientes una reparación duradera, estable y estructural de los defectos craneofaciales con buen resultado estético.

Afundamento costal estabilizado com suporte externo de metilmetacrilato em um felino / Ditching costal stabilized with external support of methylmethacrylate in a feline

O tórax instável ou afundamento costal acontece quando há fraturas múltiplas de pelo menos duas costelas consecutivas (CROWE et al., 2005). Nesse caso, durante a inspiração, o segmento fraturado, ao invés de expandir com o restante da caixa torácica, tende a penetrar no tórax. Subsequentemente, no momento da expiração, o conjunto instável tende a expansão (CROWE et al., 2005, FOSSUM, 2008). O tratamento inicial consiste em tornar o tórax estável, com uma pinça backhaus (AGUIAR, 2011). Posteriormente faz-se necessária a imobilização externa, que permitirá a adequada expansão torácica, sendo mantida por alguns dias até a estabilização do paciente. Para o tratamento cirúrgico recomenda-se a reconstrução anatômica das costelas fraturadas (CUNHA et al., 2009). O objetivo desse trabalho é demonstrar o tratamento da instabilidade costal com metilmetacrilato em felino, descrita por Coutinho et al. (2012).

Avaliação morfológica e por imagem radiográfica da matriz óssea mineralizada heteróloga fragmentada e metilmetacrilato, preservados em glicerina para reparação de falhas ósseas em tíbias de coelhos / Morphological evaluation and radiographic image of fragmented heterolog mineralized bone matrix and methylmethacrylate preserved in glycerin to repair osseous defects in tibias of rabbits

Os traumas que resultam em fraturas ósseas, principalmente as cominutivas, têm uma importância muito grande na rotina clínico-cirúrgica veterinária e humana. Foi realizada falha segmentar de 6mm na região metafisária medial da tíbia esquerda de 12 coelhos, a qual foi preenchida com implante constituído de matriz óssea mineralizada heteróloga fragmentada e metilmetacrilato, preservados em glicerina (98%) para a sua reconstrução. Foi realizada avaliação morfológica e radiológica aos 30, 60, 90 e 120 dias e observou-se a incorporação do implante ao leito receptor, em 100% dos casos, mostrando ser biologicamente compatível, pois promoveu a reparação das falhas ósseas, sem sinais de infecção, migração e/ou rejeição, sendo uma opção de substituto para preencher defeitos ósseos.

The traumas that result in bone fractures, especially comminuted, have high importance in veterinary and human surgical routine. A 6mm of segmental defect was performed at the medial metaphyseal region of the left tibia of 12 rabbits and an association of fragmented heterologue mineralized bone matrix and methylmethacrylate conserved in glycerin (98%) was used as a graft to fill the bone defect. To evaluate the procedure morphological and radiological exams were performed after 30, 60, 90 and 120 days. There was gradual integration of the bone graft in the receptor bed in 100% of the cases showing that the material is biologically compatible as it promotes bone defect reparation without signs of infection, migration and/or rejection and can be considered one more option to be used as a substitute to fill bone defects.

Assessment of methyl methacrylate genotoxicity by the micronucleus test

The aim of this study was to evaluate the genotoxic potential of methyl methacrylate (MMA) vapor by simulating standard occupational exposure of 8 hours per day and using the micronucleus test. We used 32 adult male Wistar rats divided into three groups: A - 16 rats exposed to MMA for 8 hours a day, B - Eight rats receiving single subcutaneous doses of cyclophosphamide on the first day of the experiment (positive control), C - Eight rats receiving only water and food ad libitum (negative control). Eight rats from group A and all of the rats from groups B and C were sacrificed 24 hours after beginning the experiment (acute exposure in group A). The remaining animals in group A were sacrificed 5 days after the experiment began (repeated exposure assessment in group A, simulating occupational exposure 40 hours/week). Femoral bone marrow was collected from each rat at the time of sacrifice for use in the micronucleus test. Two slides were completed per animal and were stained with Giemsa staining. Two thousand polychromatic erythrocytes were counted per animal. The Kruskal-Wallis test followed by a multiple comparisons test (Dunn test) was used for statistical analysis. The median number of micronuclei was 7.00 in the group exposed to MMA for 1 day, 2.00 in the group exposed to MMA for 5 days, 9.00 in the group exposed to cyclophosphamide (positive control) and 0.756 in the negative control group (p < 0.0001). MMA was genotoxic when measured after 1 day of exposure but was not evidently genotoxic after 5 days.

Fifteen-year Results of Precoated Femoral Stem in Primary Hybrid Total Hip Arthroplasty

BACKGROUND: There has been controversy whether methylmethacrylate precoating of the cemented femoral stem is a solution for aseptic loosening or rather contributes to increased failure rates in cemented total hip arthroplasties. METHODS: On a retrospective basis, we analyzed 76 primary hybrid total hip arthroplasties from 63 patients with precoated, cemented femoral stems between October 1990 and December 1995. The mean age of the patients was 46.8 years (range, 22 to 77 years) with a minimum follow-up of 14 years (mean, 15.5 years; range, 14 to 19.5 years). Third generation cementing techniques were employed in all cases. RESULTS: Twenty-four out of 76 cases (31.6%) showed aseptic loosening of the femoral stems, of which 23 stems were revised at an average revision time of 8 years (range, 3 to 14.8 years). The main mode of loosening was cement-stem interface failure in 22 hips (91.7%). Twenty-one out of 24 failed hips (87.5%) demonstrated C2 cementing grades (p < 0.001). Kaplan-Meier survivorship analysis using radiographic aseptic loosening of the femoral stem as the endpoint for failure showed survival rates of 76.5% at 10 years (95% confidence interval [CI], 71.4 to 81.6) and 63.2% at 19 years (95% CI, 57.3 to 69.1). CONCLUSIONS: An early failure of the precoated femoral stem in this study was mainly due to an insufficient cementing technique. Achievement of good cement mantle may improve the survival rates.

Forehead Augmentation with a Methyl Methacrylate Onlay Implant Using an Injection-Molding Technique

BACKGROUND: The forehead, which occupies about one third of the face, is one of the major determinants of a feminine or masculine look. Various methods have been used for the augmentation of the forehead using autologous fat grafts or alloplastic materials. Methylmethacrylate (MMA) is the most appropriate material for augmentation of the forehead, and we have used an injection-molding technique with MMA to achieve satisfactory results. METHODS: Under local anesthesia with intravenous (IV) sedation, an incision was made on the scalp and a meticulous and delicate subperiosteal dissection was then performed. MMA monomers and polymers were mixed, the dough was injected into the space created, and manual molding was performed along with direct inspection. This surgery was indicated for patients who wanted to correct an unattractive appearance by forehead augmentation. Every patient in this study visited our clinics 3 months after surgery to evaluate the results. We judged the postoperative results in terms of re-operation rates caused by the dissatisfaction of the patients and complications. RESULTS: During a 13-year period, 516 patients underwent forehead augmentation with MMA. With the injection-molding technique, the inner surface of the MMA implant is positioned close to the underlying frontal bone, which minimizes the gap between the implant and bone. The borders of the implant should be tapered sufficiently until no longer palpable or visible. Only 28 patients (5.4%) underwent a re-operation due to an undesirable postoperative appearance. CONCLUSIONS: The injection-molding technique using MMA is a simple, safe, and ideal method for the augmentation of the forehead.

Profilometeric and SEM evaluation of effect of polishing on surface roughness of two composites [silorane-based and methylmethacrylate-based] and a Glass ionomer

To evaluate the effect of polishing on surface roughness of silorane-based composite using profilometery and Scanning Election Microscopy [SEM] and compare it with that of a methylmethacrylate- based composite and a glass ionomer. In this study, 3 groups [n=28] were tested: specimens of two composites [Filtek P90 and Filtek P60] and a glass ionomer [Fuji IX] which were prepared in polyethylene molds [4 mm diameter x10 mm Height]. Half of the specimens in each group were finished with 180-grit silicon carbide paper and the remaining were finished with 180-grit, and subsequently polished with 250, 400, 800, 1000, 2000, and 2500-grit silicon carbide papers. The surface roughness was evaluated using a contact profilometer and then mean [R[a]] and maximum [R[max]] of surface roughness were recorded. Then, the surface of 4 specimens of each subgroup was observed under SEM. Statistical analysis was performed with T-test, ANOVA and Dunnett T3 tests. In all materials, Ra was different between polishing with 180 and 2500-grit silicon carbide papers. In 180-grit group, only Ra of Filtek P60 and Fuji IX showed significant difference [P=0.01]. In 2500-grit group, there was no significant difference between the Ra of Filtek P60 and Filtek P90 [P=0.56]. Polishing is recommended for the glass ionomer and posterior composite restorations

Tomografia computadorizada da matriz óssea mineralizada heteróloga fragmentada e metilmetacrilato na reparação de falhas ósseas segmentares produzidas em tíbia de coelhos / Computed tomography to evaluate the association of fragmented heterolog cortical bone and methylmethacrylate to repare segmental bone defect produced in tibia of rabbits

Foi realizada falha segmentar de 6mm na região metafisária medial da tíbia de 12 coelhos, seguida de preenchimento desta por matriz óssea mineralizada heteróloga fragmentada conservada em glicerina (98%) e metilmetacrilato autoclavado, bem como avaliação por meio da tomografia computadorizada de feixe cônico (cone beam) aos 30, 60 e 90 dias. Houve incorporação gradativa do implante no leito receptor em relação ao tempo em 100% dos casos, o que mostra ser este biologicamente compatível, ao promover reparação da falha óssea, sem sinais de infecção, migração e/ou rejeição, caracterizando-se, assim, como nova opção de substituto ósseo para preenchimento de falhas ósseas.

A 6mm segmental defect was performed on the metaphyseal region of the tibia of 12 rabbits and the autoclaved fragmented heterolog cortical bone conserved in glycerin (98%) and methylmethacrylate was used as a bone graft for the reconstruction. The graft was placed in the receptor bed and its integration was evaluated by computed tomography after 30, 60 and 90 days. There was gradual bone graft incorporation in the receptor bed during the time in 100% of the cases. Fragmented cortical bone heterograft and methylmethacrylate was biologically compatible and promotes bone defect reparation without signs of infection, migration and or rejection, featuring a new option of osseous substitute to fill in bone defects.

Customized Cranioplasty Implants Using Three-Dimensional Printers and Polymethyl-Methacrylate Casting

OBJECTIVE: The prefabrication of customized cranioplastic implants has been introduced to overcome the difficulties of intra-operative implant molding. The authors present a new technique, which consists of the prefabrication of implant molds using three-dimensional (3D) printers and polymethyl-methacrylate (PMMA) casting. METHODS: A total of 16 patients with large skull defects (>100 cm2) underwent cranioplasty between November 2009 and April 2011. For unilateral cranial defects, 3D images of the skull were obtained from preoperative axial 1-mm spiral computed tomography (CT) scans. The image of the implant was generated by a digital subtraction mirror-imaging process using the normal side of the cranium as a model. For bilateral cranial defects, precraniectomy routine spiral CT scan data were merged with postcraniectomy 3D CT images following a smoothing process. Prefabrication of the mold was performed by the 3D printer. Intraoperatively, the PMMA implant was created with the prefabricated mold, and fit into the cranial defect. RESULTS: The median operation time was 184.36+/-26.07 minutes. Postoperative CT scans showed excellent restoration of the symmetrical contours and curvature of the cranium in all cases. The median follow-up period was 23 months (range, 14-28 months). Postoperative infection was developed in one case (6.2%) who had an open wound defect previously. CONCLUSION: Customized cranioplasty PMMA implants using 3D printer may be a useful technique for the reconstruction of various cranial defects.

Easy Molding Technique of Methylmethacrylate Implant Using Plaster and Rapid Prototyping Model in Cranioplasty

PURPOSE: Methylmethacrylate is the most commonly used alloplastic material in cranioplasty. However during the polymerization of methylmethacrylate, a significant exothermic reaction takes place. This reaction may result in thermal injury to the brain tissue and other soft tissues. Also it is difficult to make three-dimensional methylmethacrylate implant that is perfectly matched to the defect during the operation time. We report on the molding technique of methylmethacrylate implant using plaster mold and the rapid prototyping model in cranioplasty. METHODS: A 44-year-old male was referred to the department for severe frontal hollowness. He was involved in an automobile accident resulting in large frontal bone defect with irregular margin. The preformed patient-specific methylmethacrylate implant was made using plaster mold and the rapid prototyping model before the operative day. The methylmethacrylate implant was placed in the frontal defect and rigidly fixed with miniplates and screws on the operative day. RESULTS: The operation was performed in an hour. In the 6 months follow-up period, there were no complications. Patient was satisfied with the results of cranioplasty. CONCLUSION: Safe cranioplasty was performed with the preformed patient-specific methylmethacrylate implant using plaster mold and the rapid prototyping model. The result of this method was satisfactory, aesthetically and functionally.

Effect of leaching residual methyl methacrylate concentrations on in vitro cytotoxicity of heat polymerized denture base acrylic resin processed with different polymerization cycles

OBJECTIVES: Residual methyl methacrylate (MMA) may leach from the acrylic resin denture bases and have adverse effects on the oral mucosa. This in vitro study evaluated and correlated the effect of the leaching residual MMA concentrations ([MMA]r) on in vitro cytotoxicity of L-929 fibroblasts. MATERIAL AND METHODS: A total of 144 heat-polymerized acrylic resin specimens were fabricated using 4 different polymerization cycles: (1) at 74ºC for 9 h, (2) at 74ºC for 9 h and terminal boiling (at 100ºC) for 30 min, (3) at 74ºC for 9 h and terminal boiling for 3 h, (4) at 74ºC for 30 min and terminal boiling for 30 min. Specimens were eluted in a complete cell culture medium at 37ºC for 1, 2, 5 and 7 days. [MMA]r in eluates was measured using high-performance liquid chromatography. In vitro cytotoxicity of eluates on L-929 fibroblasts was evaluated by means of cell proliferation using a tetrazolium salt XTT (sodium 3´-[1-phenyl-aminocarbonyl)-3,4-tetrazolium]bis(4-methoxy-6-nitro)benzenesulphonic acid) assay. Differences in [MMA]r of eluates and cell proliferation values between polymerization cycles were statistically analyzed by Kruskal-Wallis, Friedman and Dunn's multiple comparison tests. The correlation between [MMA]r of eluates and cell proliferation was analyzed by Pearson's correlation test (p<0.05). RESULTS: [MMA]r was significantly (p<0.001) higher in eluates of specimens polymerized with cycle without terminal boiling after elution of 1 and 2 days. Cell proliferation values for all cycles were significantly (p<0.01) lower in eluates of 1 day than those of 2 days. The correlation between [MMA]r and cell proliferation values was negative after all elution periods, showing significance (p<0.05) for elution of 1 and 2 days. MMA continued to leach from acrylic resin throughout 7 days and leaching concentrations markedly reduced after elution of 1 and 2 days. CONCLUSION: Due to reduction of leaching residual MMA concentrations, use of terminal boiling in the polymerization process for at least 30 min and water storage of the heat-polymerized denture bases for at least 1 to 2 days before denture delivery is clinically recommended for minimizing the residual MMA and possible cytotoxic effects.

Effect of incorporation of 2-tert-butylaminoethyl methacrylate on flexural strength of a denture base acrylic resin

Polymethyl methacrylate (PMMA) resins have commonly been used as a denture base material. However, denture bases may act as a reservoir for microorganisms and contribute to oral diseases in denture wearers. It is hypothesized that the 2-tert-butylaminoethyl methacrylate (TBAEMA) incorporated to acrylic resins should have antimicrobial activity related to the presence of amino groups on acrylic resin surface. OBJECTIVES: The objectives of this study were to evaluate the presence of amino groups on acrylic resin surface and the influence on flexural strength after incorporation of TBAEMA. MATERIAL AND METHODS: Six groups were divided according to the concentration of TBAEMA incorporated to acrylic resin (Lucitone 550): 0, 0.5, 1.0, 1.5, 1.75 and 2 percent. Specimens surface were evaluated by Electron Spectroscopy for Chemical Analysis (ESCA) to detect the presence of amino groups, represented by nitrogen ratios. Flexural strength of the specimens was tested and results were analyzed by ANOVA and Tukey's test (α=0.05). RESULTS: Different nitrogen ratios were observed on specimen surfaces: 0, 0.13, 0.74, 0.66, 0.92 and 0.33 percent for groups 0, 0.5, 1.0, 1.5, 1.75, and 2 percent, respectively. Significant differences were found for flexural strength (p<0.001). The mean flexural strength values were 98.3±3.9, 93.3±3.2, 83.9±2.1, 82.8±5.2, 71.2±5.1 and 17.3±3.2 MPa for groups 0, 0.5, 1.0, 1.5, 1.75, and 2 percent, respectively. CONCLUSION: Within the limitations of this study, the incorporation of TBAEMA results in the presence of the potentially antimicrobial amino groups on specimen surfaces, but affect the flexural strength, depending on the concentration of TBAEMA.