Polymethylmethacrylate for managing frontal bone deformities

Labial Repositioning Using Print Manufactured Polymethylmethacrylate- (PMMA-) Based Cement for Gummy Smile

Treating patients with excessive gingival display (EGD) to provide them with a pleasant smile is a challenge to periodontists. A gummy smile can be due to excessive vertical bone growth, dentoalveolar extrusion, short upper lip, upper lip hyperactivity, or altered passive eruption (APE). In addition, many patients have a lack of lip support due to marked depression of the anterior process of the maxilla. In these cases, lip repositioning using polymethylmethacrylate (PMMA) cement could be performed. This article describes a case of EGD with subnasal depression. In the clinical examination, the presence of a marked subnasal depression was found, in which the upper lip lodged during a spontaneous smile. In addition to this, gingival exposure extending from the maxillary molar on one side of the mouth to the one on the opposite side was also found during the spontaneous smile. Therefore, the periodontal surgical intervention proposed consisted of performing a procedure to fill the subnasal depression with PMMA cement. This article describes a digital approach to plan the use of PMMA cement in lip repositioning in a patient with gummy smile and subnasal depression. The patient reported no postoperative complications. Six months after the surgery, the patient revealed a more harmonious smile than before, with reduction in the gingival exposure and new adequate support for and repositioning of the upper lip.

Improved osteoblast response to UV-irradiated PMMA/TiO2 nanocomposites with controllable wettability

Osteoblast response was evaluated with polymethylmethacrylate (PMMA)/titanium dioxide (TiO2) nanocomposite thin films that exhibit the controllable wettability with ultraviolet (UV) treatment. In this study, three samples of PMMA/TiO2 were fabricated with three different compositional volume ratios (i.e., 25/75, 50/50, and 75/25) followed by UV treatment for 0, 4, and 8 h. All samples showed the increased hydrophilicity after UV irradiation. The films fabricated with the greater amount of TiO2 and treated with the longer UV irradiation time increased the hydrophilicity more. The partial elimination of PMMA on the surface after UV irradiation created a durable hydrophilic surface by (1) exposing higher amount of TiO2 on the surface, (2) increasing the hydroxyl groups on the TiO2 surface, and (3) producing a mesoporous structure that helps to hold the water molecules on the surface longer. The partial elimination of PMMA on the surface was confirmed by Fourier transform infrared spectroscopy. Surface profiler and atomic force microscopy demonstrated the increased surface roughness after UV irradiation. Both scanning electron microscopy and energy-dispersive X-ray spectroscopy demonstrated that particles containing calcium and phosphate elements appeared on the 8 h UV-treated surface of PMMA/TiO2 25/75 samples after 4 days soaking in Dulbecco's Modified Eagle Medium. UV treatment showed the osteoblast adhesion improved on all the surfaces. While all UV-treated hydrophilic samples demonstrated the improvement of osteoblast cell adhesion, the PMMA/TiO2 25/75 sample after 8 h UV irradiation (n = 5, P value = 0.000) represented the best cellular response as compared to other samples. UV-treated PMMA/TiO2 nanocomposite thin films with controllable surface properties represent a high potential for the biomaterials used in both orthopedic and dental applications.

Aesthetic restoration of fronto-orbital deformity with prefabricated implant utilizing modeling clay and rapid-prototyping technology

Skeletal deformity in the fronto-orbital region resulting from various problems can have significant aesthetic concerns. Restoring an aesthetically acceptable appearance relies most importantly on the restoration of a precise skeletal contour. Current surgical options for depression deformities or partial-thickness defects range from extensive corrective osteotomies to less complicated methods of onlay grafting with autogenous or alloplastic materials. Both methods have difficulties in providing a symmetric and smooth contour for predictable and reliable cosmetic results. Alloplastic implants provide another effective alternative and the success of the skeletal contouring correlates directly with the accuracy of the implant sculpture. Prefabricated methylmethacrylate implants, with the aid of modeling clay, computer imaging, and modern rapid-prototyping technologies, fits the depression deformity well and balances the skeletal contour. It provides plastic surgeons greater precision in customizing the implant, which ensures better predictability and reliability of cosmetic outcomes.

Lipoatrofia facial associada ao HIV/AIDS: do advento aosconhecimentos atuais

O advento da AIDS trouxe novos desafios para a Dermatologia. A terapia antirretroviral mudou drasticamente a morbimortalidade associada à infecção pelo HIV/AIDS, mas contribuiu para o surgimento de outras novas situações que exigem abordagem adequada do dermatologista. A Síndrome Lipodistrófica Associada ao HIV/AIDS tem origem multifatorial, mas está fortemente associada ao uso dos antirretrovirais. Compreende alterações na distribuição da gordura corporal, acompanhada ou não de alterações metabólicas. A perda da gordura da face, chamada lipoatrofia facial, é dos sinais mais estigmatizantes da síndrome. Esta condição, muitas vezes reveladora da doença, trouxe de volta o estigma da AIDS. É necessário que os especialistas que atuam com pacientes com HIV/AIDS identifiquem estas alterações e busquem opções de tratamento, dentre as quais se destaca o implante com polimetilmetacrilato, que é disponibilizado para tratamento da lipoatrofia facial associada ao HIV/AIDS no Sistema Único de Saúde

Temperature elevation during simulated polymethylmethacrylate (PMMA) cranioplasty in a cadaver model

The aims of this study were to: (i) obtain temperature measurements during in vitro polymerisation of polymethylmethacrylate (PMMA) disks of a range of thicknesses; and (ii) obtain tissue temperature measurements at various locations within a skull defect during a simulated PMMA cranioplasty procedure using a cadaver. In vitro, higher temperatures were recorded with increasing PMMA thickness. During the simulated cranioplasty, the maximum temperature was observed inside the PMMA sample, with nearby tissues being exposed to temperatures of greater than 50 degrees C over prolonged periods. There is conflicting information in the literature concerning the sensitivity of brain tissue and bone to elevated temperatures. Preoperatively fabricated PMMA cranioplasty prostheses are recommended.