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.

Dental Bonding ; Denture Liners ; Dimethylpolysiloxanes ; Materials Testing ; Polymerization ; Polymethyl Methacrylate ; Silicone Elastomers ; Silicones ; Tensile Strength

OBJECTIVETo evaluate the effect of denture base resin surface pretreatment with chemical etchants on microleakage and bond strength between silicone-based resilient liner and denture base resin. The initial bending strength of denture base resin after surface pretreatment was also examined.

METHODSThirty-six polymethyl methacrylate (PMMA) denture base resin blocks (30 mm × 30 mm × 2 mm) were prepared and divided into three groups: group acetone, group methyl methy acrylate (MMA) and group control. Subsequently, a 2 mm silicone-based resilient liner was applied between every two blocks. After 5000 cycles in the thermal cycler (5 and 55°C), they were immersed in the (131) I solution for 24 hours and γ-ray counts were measured. Another 36 PMMA resin blocks (30 mm × 10 mm × 7.5 mm) were prepared. The blocks were divided into three groups and treated as mentioned above. A 3 mm silicone-based resilient liner was applied between every two blocks. After 5000 thermal cycles, tensile bond strength of the sample was measured in a universal testing machine. Another 18 PMMA resin blocks (65 mm × 10 mm × 3.3 mm) were prepared. They were divided into 3 groups and treated in the same way. After an adhesive was applied, the bending strength was measured with three-piont bending test.

RESULTSTwo experimental groups showed lower microleakage (520.0 ± 562.2 and 493.5 ± 447.9) and higher tensile bond strength [(1.5 ± 0.4) and (1.4 ± 0.5) MPa] than the group control [microleakage: (1369.5 ± 590.2); tensile bond strength: (0.9 ± 0.2) MPa, P < 0.05]. There was no statistically significant difference between group acetone and MMA in microleakage and tensile bond strength (P > 0.05). There was no statistically significant difference in bending strength among the three groups (P > 0.05).

CONCLUSIONSTreating the denture base resin surface with acetone and MMA decreased the microleakage, increased the tensile bond strength between the two materials and did not make the initial bending strength of denture base resin decline.

Dental Bonding ; Dental Cements ; Dental Materials ; Denture Bases ; Denture Liners ; Dimethylpolysiloxanes ; Humans ; Materials Testing ; Polymethyl Methacrylate ; Silicone Elastomers ; Silicones ; Surface Properties ; Tensile Strength

No abstract available.
Silicones*

No Abstract Available.
Silicones*

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

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

PURPOSE: To compare the clinical outcome of silicone tube intubation according to the tie methods. METHODS: Eighty-eight eyes of 87 patients who underwent silicone tube intubation were divided into two groups based on the tie method: a silicone silastic sheet group (Group 1, n=59) and a nylon 6-0 suture knot group (Group 2, n=29). The two groups were compared according to their success rates, recurrence rates and complications. RESULTS: No significant difference was found in the success rate between the two groups (83.0% in Group 1 and 82.7% in Group 2). However, Group 2 showed a significantly higher rate of postoperative complications than Group 1. In Group 1, 5/59 (8.4%) eyes had ocular irritation, 2/59 (3.4%) eyes exhibited tube prolapse, conjunctivitis, corneal erosion, and dacryocystitis and 1/69 (1.6%) eyes had a punctal slit after intubation. In Group 2, 3/29 (10.3%) eyes had ocular irritation, 2/29 (6.9%) eyes exhibited tube prolapse, conjunctivitis, a punctal slit, and dacryocystitis, and 1/29 (3.4%) eyes showed corneal erosion, or a granuloma after intubation. A recurrence of symptomatic tearing was found in 6/59 (10%) eyes in Group 1 and 3/29 (10%) in Group 2. CONCLUSIONS: In silicone tube intubation of incomplete NLD obstruction, the usage of silicone silastic sheets to tie both ends of the silicone tube produced a lower complication rate and a higher success rate than that of the suture knot group. Lower tension on the nasolacrimal passage in the silicone silastic sheet group allows for a significantly lower rate of punctal slit development. Therefore, the method of using silicone silasitic sheets can be considered useful in the treatment of NLD obstruction.
Conjunctivitis ; Dacryocystitis ; Dimethylpolysiloxanes ; Eye ; Granuloma ; Humans ; Intubation ; Nasolacrimal Duct ; Nylons ; Postoperative Complications ; Prolapse ; Recurrence ; Silicones ; Sutures

BACKGROUND: For reconstruction of the mild to moderate medial orbital wall fractures, various surgical approaches have been used. Prior existing W-shaped incision was a direct local approach through a 3 cm incision on the superior medial orbital area with a titanium mesh implant. In this study, the authors modified W-shaped incision and reconstructed the defect with silastic sheet to improve the result and the postoperative scar. METHODS: This study included 20 patients who had mild to moderate size of medial wall defect and therefore relatively suitable for reconstruction with silastic sheets from July, 2009 to December, 2011. A modified W-shaped skin incision approximately 1.2 to 1.5 cm in length was made along the superior medial orbital rim from approximately 1 cm medial to the medial canthus to the lower border of the medial eyebrow. The angles of the limbs of the W ranged from 150 to 160 degrees. RESULTS: By using soft flexible silastic sheet, the authors reduced the incision from 3 to 1.5 cm, and by widening the angle of the W limbs, scars were more effectively hided in the relaxed skin tension line. Scar assessment was done with modified patient and observer scar assessment scale and mean score from patients was 2.08 and mean score from observers was 2.12. CONCLUSION: Although this method will not be suitable for every case, it can be a consistent method to obtain the surgical goal in treatment of mild to moderate blowout fractures of the medial orbital wall.
Cicatrix ; Dimethylpolysiloxanes ; Extremities ; Eyebrows ; Humans ; Orbit ; Orbital Fractures ; Silicones ; Skin ; Titanium

Laryngeal stenosis is a partial or complete narrowing of the endolaryngeal airway and it may occur congenitally or may be acquired. Acquired stenosis is caused by iatrogenic injuries from endotracheal intubation or traffic accidents. We report a case of anterior glottis stenosis combined with subglottic granuloma with a history of neck trauma and intubation. We have successfully treated the stenosis using intra-laryngeal thin silicon sheets after adhesiolysis.
Accidents, Traffic ; Constriction, Pathologic ; Dimethylpolysiloxanes ; Glottis ; Granuloma ; Intubation ; Intubation, Intratracheal ; Laryngostenosis ; Neck ; Silicones ; Stents