A line is drawn from the nasal tip to the most anterior point of the lower lip. The distance from soft tissue pogonion to the ideal soft tissue pogonion is the amount of correction. Alloplastic augmentation does not correct the soft tissue in a 1:1 ratio. In the case of a patient having normal soft tissue(8~11 mm), the ratio of the soft tissue correction is 1:0.66. In the case of a patient having a soft tissue deficiency(less than 7mm), the ratio of the soft tissue correction is 1:0.8. In the case of a patient having a soft tissue excess(more than 12mm), the ratio of the soft tissue correction is 1:0.5. The length of the implant is required to be more lateral to the mental foramen by 1~1.5 cm for restoration of the prejowl sulcus. The posterior surface of the implant must be carved to shape precisely to the bony surface. I usually make several vertical etchings and 20~30 holes in the implant. The vertical etchings help expand the implant to securely fit the mandibular contour. Fenestrated silastic implants can be further stabilized with fibrous tissue ingrowth and future reconstruction if bony erosion occurs.
Chin ; Dimethylpolysiloxanes ; Humans ; Lip ; Silicone Elastomers

OBJECTIVETo compare shear bond strength (SBS) between two types of silicone soft liner and polymethyl methacrylate (PMMA) under the condition of heat curing and room temperature curing.

METHODSA total of 48 PMMA specimens (50 mm x 10 mm x 3 mm) were made by water-bath heating method, and randomly divided into four groups. By using Ufi Gel P (UGP) as soft liner material, group A1 was prepared under heat curing, and group A2 was prepared under room temperature curing. To form the other two groups, Silagum-Comfort (SLC) as soft-liner material was used. Group B1 was prepared under heat curing, and group B2 was prepared under room temperature curing. Shear bond strength (SBS) was tested by using the electronic universal testing machine. The adhesives layer and surface of silastic and PMMA were observed by optical microscope and scanning electron microscopy (SEM).

RESULTSThe SBS of groups A1, A2, B1, B2 were (2.39 +/- 0.24), (1.74 +/- 0.27), (3.09 +/- 0.26), and (2.21 +/- 0.29) MPa, respectively. Significant differences were found between A1 and A2, B1 and B2, A1 and B1, and A2 and B2 (P < 0.05). Optical microscope showed numerous bubbles in the cured UGP, and no air bubbles in the SLC. The surface of PMMA was rough. SEM images showed that each group had continual consistent adhesive interface and a whisker hump on the adhesive layer of A2 and B2.

CONCLUSIONThe SBS ofUGP, SLC, and PMMA achieved minimum clinical standard of 0.44 MPa. The SBS of UGP and PMMA were higher than that of SLC and PMMA. The polymerization method of heat curing was higher than room temperature curing.

OBJECTIVEThe biological safety of a new developed silicone rubber for inflatable silastic prosthesis (SRISP) was evaluated.

METHODSFollowing the GB/T 16886.10-2005 standard, YY/T 0127.13-2009 standard, and GB/T 16886.11- 2011 standard, samples were prepared and tested by animal experiments, such as guinea pig maximization test, oral mucous membrane irritation test, and short-term systemic toxicity test (oral route).

RESULTSNo obvious erythema and edema in the guinea pig abdominal skin were observed after 24, 48, and 72 h of stimulating touch, thus indicating that SRISP does not cause potential skin sensitivity. No local response to SRISP was found, and the visual observation and pathological findings of oral mucosa were normal and similar to that of the control group. Therefore, SRISP had no irritation response to oral mucosa. No clinical signs of toxicity were observed in rats, and no significant differences in weight and weight relative growth rate between extract group and blank control group (P > 0.05) were found. Thus, SRISP had no short-term systemic toxicity.

CONCLUSIONThese results indicated that SRISP met the requirement of biomedical materials and had good bio- security.

PURPOSE: Purpose of this study was to evaluate effect of two surface treatments, sandblasting and monomer treatment, on tensile bond strength between two long term resilient liners and poly (methyl methacrylate) denture base resin. MATERIALS AND METHODS: Two resilient liners Super-Soft and Molloplast-B were selected.Sixty acrylic resin (Trevalon) specimens with cross sectional area of 10x10 mm were prepared and divided into two groups of 30 specimens each. Each group was surface treated (n = 10) by sandblasting (250 micro alumina particles), monomer treatment (for 180 sec) and control (no surface treatment). Resilient liners were processed between 2 poly(methyl methacrylate) surfaces, in the dimensions of 10x10x3 mm. Tensile strength was determined with Instron Universal testing machine, at a crosshead speed of 5 mm/min; and the modes of failure (adhesive, cohesive or mixed) were recorded. The data were analyzed using one-way ANOVA, followed by Tukey HSD test (alpha = 0.05). RESULTS: Monomer pretreatment of acrylic resin produced significantly higher bond strengths when compared to sandblasting and control for both resilient liners (P < .001). Sandblasting significantly decreased the bond strength for both the liners when compared to monomer pretreatment and control (P < .001). Mean bond strength of Super-Soft lined specimens was significantly higher than Molloplast-B in various surface treatment groups (P < .05). CONCLUSION: Surface pretreatment of the acrylic resin with monomer prior to resilient liner application is an effective method to increase bond strength between the base and soft liner. Sandblasting, on the contrary, is not recommended as it weakens the bond between the two.
Aluminum Oxide ; Collodion ; Denture Bases ; Dentures ; Dimethylpolysiloxanes ; Polymethyl Methacrylate ; Silicone Elastomers ; Tensile Strength

There are some attempts to improve the survival of venous island flap, such as delay procedure and pharmacological agents. This study includes prefabrication of vein which could enhance the survival of the venous island flap. The venous island flap was created by a branch of the central vein in rabbit auricle. At 1.5 cm away from the distal margin of the designed flap, the central vein was dissected and transferred under the random part of the future venous flap for 1 week. The survival of prefabricated venous flap was compared with unprefabricated flap 1 week after the flap elevation. The vasculature in the flap were also visualized by microfil cast. The results were as follows: 1. The prefabrication improved the survival of the venous flap significantly. 2. The transferred veins in the prefabricated flap were well visualized 1 week after the flap elevation. In conclusion, it is inferred that the prefabrication enhance the survival of the venous island flap.
Silicone Elastomers ; Veins

PURPOSE: This study was designed to better understand the mechanism of low temperature burn and to show clinical cases of low temperature burn. METHODS: The local temperature increase of electric pad was investigated at 4 different surface cooling conditions. Blocks (5x5x2 cm3) made of silicone rubber, aluminum, or urethane foam were placed on the top of the electric pad, and temperature between the blocks and electric pad was measured up to 7 hours after switching on maximally (level 7). Each block has different thermal conductivity (TC) and TC of silicone rubber (0.2 W/m.degrees C) is similar to TC of human skin (0.37 W/m.degrees C). TC of aluminum is higher and TC of urethane foam is lower than TC of human skin. Experiments were performed on two occasions with or without a blanket covering over the electric pad and blocks. RESULTS: The initial surface temperature (18degrees C) of the electric pad under the silicone rubber block was elevated to 36.5degrees C at 1 hour, 41.8degrees C at 3 hours, 44.2degrees C at 5 hours, and 45.5degrees C at 7 hours. After covering the electric pad and blocks with a blanket, the temperature of the electric pad under the silicone rubber block was elevated to 40.9degrees C at 1 hour, 51.8degrees C at 3 hours, 56.1degrees C at 5 hours and 58.1degrees C at 7 hours. Under the same conditions, surface temperatures under the urethane foam and aluminum blocks were 70.8degrees C and 50.degrees C respectively at 7 hours. CONCLUSION: The local temperature increase of electric pad was dependent on the surface cooling conditions, heating time and blanket covering over the electric pad. The surface temperature increased to 56.1degrees C at 5 hours after blanket covering over the silicone block which temperature can cause severe injuries on the human skin within a minute.
Aluminum ; Beds ; Burns* ; Heating ; Hot Temperature ; Humans ; Silicon ; Silicone Elastomers ; Silicones ; Skin ; Thermal Conductivity ; Urethane

We report the case of a patient who presented with rupture of a silicone breast implant showing acute and chronic inflammation. Magnetic resonance imaging (MRI) showed silicone foci outside the implant shell and inside the pectoralis muscles that represented intra- and extracapsular ruptures of the implant and silicone granuloma. There were distinct fluid-fluid levels of various signal intensities and no signs of implant collapse such as ‘linguine sign.’ Rather, we detected enlargement of both the implant shell and the breast.
Breast Implants ; Breast ; Granuloma ; Humans ; Inflammation ; Magnetic Resonance Imaging ; Pectoralis Muscles ; Rupture ; Silicon ; Silicone Elastomers ; Silicones

PURPOSE: The aim of the study was to evaluate the effect of 3 silicone primers and 3 surface characterization of acrylic resin surface on bond strength between silicone elastomer and acrylic resin. MATERIALS AND METHODS: 96 Cosmesil silicones bonded to heat-curing acrylic resin were fabricated with the dimension of 75 x 10 x 3 mm. The 3 primers used in this study were G611 platinum primer, A-330 Gold platinum primer, and cyanoacrylates resin. Specimens without primer were used as control. The 3 types of surface characterization done were retentive holes with 1.5 mm in diameter and 0.5 mm deep, retentive beads of 0.6 mm diameter and the third type which was plain without any characterization. The specimens were then checked for bond strength by subjecting them to 180degrees peel test on a universal testing machine. The obtained results were then subjected to statistical analysis using 2-way ANOVA and Scheffe multiple post hoc procedures. The statistical significance was set at 5% level of significance. RESULTS: The maximum bond strength was seen for samples in which A-330G primer was used followed by G611 primer. The control group showed the minimum bond strength. Surface characterization of retentive holes increased the bond strength considerably as compared to retentive beads and samples without any surface characterization. CONCLUSION: Within the limitations of the study, A-330G primer was more compatible with Cosmesil M511 silicone and has better bonding of Cosmesil to acrylic resin. Retentive holes made on acrylic surface increased the bond strength considerably than those without any surface characterization.
Collodion ; Cyanoacrylates ; Platinum ; Silicone Elastomers

Silicone has become one of the most commonly used biomaterials in modern medicine. There are three forms of silicone in medical use: silicone oil, gel, and rubber. Among these, silicone rubbers are used as heart valves, shunts, coatings on pacemakers and implants of cosmetic surgery. In tissues, silicone produces a range of histological reactions depending on the form of silicone. We report a case of a foreign body granuloma due to the prescence of silicone rubber inserted for nasal augmentation fifteen years previously, and review the complications of augmentation rhinoplasty using silicone implants.
Biocompatible Materials ; Foreign Bodies ; Granuloma, Foreign-Body ; Heart Valves ; History, Modern 1601- ; Rhinoplasty ; Rubber ; Silicone Elastomers ; Silicone Oils ; Skin ; Surgery, Plastic

Three-types of expandable metallic stents were constructed to evaluate the differences between the stents : one, formed in a cylindrical zigzag pattern with stainless steel wire (Gianturco stent), another, made by coating the Gianturco stent with silicone rubber(Silicone stent), the third, made by coating the Gianturco stent with 24 carat gold(God stent) for tissue acceptance. A total of 69 stents(each 23 stents of Glanturco, Silicone, and Gold stents) of 8-12 mm in diameter and 20 mm long were placed into normal abdominal aorta, inferior vena cava and iliac artery of nine adult dogs for 2 weeks to 11 months. It was more difficult to introcuce Silicone stent into an introducing sheath than Gianturco or Gold stent due to the thickness of silicone rubber, Four Gianturco stents and three Silicone stents showed migration but Gold stent did not. Luminal narrowing or occlusion was noted in 3 Silicone stents, in 2 Gianturco stents, and in 1 Gold stent. Neointimal proliferation over the stent wires was more rapid and even in God stent than Silicone or Gianturco stent. Although further study is needed, Gold stent seems to be better than Gianturco or Silicone stent as an endovascular graft material.
Adult ; Animals ; Aorta, Abdominal ; Dogs* ; Humans ; Iliac Artery ; Phenobarbital ; Silicon ; Silicone Elastomers ; Silicones ; Stainless Steel ; Stents* ; Transplants ; Vena Cava, Inferior