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: 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

PURPOSE: This study evaluated the effect of loss of interproximal papilla, creating an undercut, on the accuracy of impression materials. MATERIALS AND METHODS: Two addition type silicone impression materials (Extrude(R) Wash, Imprint(TM) II Quick Step Light Body) and one alginate impression material (Cavex Impressional) were used to make impressions of a maxillary master model simulating clinical conditions with or without interproximal papilla. Stone was poured in the impressions and working casts were fabricated. A total of 6 groups with 6 working casts in each group were scanned using 3-dimensional optical scanner. The accuracy of the impressions was assessed by measuring the dimensional changes (DeltaI (%)) of 6 distances on working casts compared to a master model with a 3-dimensional digitizing and inspection software. The data were analyzed by two-way ANOVA (P<.05). RESULTS: Three of 6 distances showed statistically significant differences among the impression materials. Only 1 of 6 distances in alginate impression showed a statistically significant difference between casts with and without interproximal papilla (P=.047). CONCLUSION: The presence of undercut due to loss of interproximal papilla did not significantly influence the dimensional accuracy of addition type silicone and alginate impression materials.
Alginates ; Dental Impression Materials ; Silicone Elastomers

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 evaluate the effect of combined immunosuppressive treatment with FK 506-cyclophosphamide on surgical angiogenesis in non-vascularized bone xenografts. MATERIALS AND METHODS: Twenty-seven hamster-to-rat non-vascularized bone xenografts were performed. For surgical angiogenesis, recipient origin saphenous arteriovenous bundles were implanted into the medullary canals of graft bones. Immunosuppression with FK 506-cyclophosphamide was performed in group 1, not in group 2, control group. At postoperative 4 weeks, microangiography with microfil was conducted. Decalcified bones were cleared and the area of newly formed capillary, capillary density, were quantitatively evaluated using Scion image program. Bone specimens stained with hematoxylin-eosin were evaluated histologically also. RESULTS: There was no significant difference of capillary densities between immunosuppressed group and non-immunosuppressed control group (0.37+/-0.03/0.39+/-0.02, P=0.58). On histological examination, both groups showed neoangiogenesis into the medullary canals and endosteal bones. CONCLUSION: FK 506-cyclophosphamide immunosuppression did not suppress the angiogenesis in non-vascularized bone xenografts, FK 506-cyclophosphamide combination of immunosuppression will be useful even in the condition of surgical angiogenesis.
Capillaries ; Heterografts ; Immunosuppression ; Silicone Elastomers ; Transplants

PURPOSE: To evaluate the effect of combined immunosuppressive treatment with FK 506-cyclophosphamide on surgical angiogenesis in non-vascularized bone xenografts. MATERIALS AND METHODS: Twenty-seven hamster-to-rat non-vascularized bone xenografts were performed. For surgical angiogenesis, recipient origin saphenous arteriovenous bundles were implanted into the medullary canals of graft bones. Immunosuppression with FK 506-cyclophosphamide was performed in group 1, not in group 2, control group. At postoperative 4 weeks, microangiography with microfil was conducted. Decalcified bones were cleared and the area of newly formed capillary, capillary density, were quantitatively evaluated using Scion image program. Bone specimens stained with hematoxylin-eosin were evaluated histologically also. RESULTS: There was no significant difference of capillary densities between immunosuppressed group and non-immunosuppressed control group (0.37+/-0.03/0.39+/-0.02, P=0.58). On histological examination, both groups showed neoangiogenesis into the medullary canals and endosteal bones. CONCLUSION: FK 506-cyclophosphamide immunosuppression did not suppress the angiogenesis in non-vascularized bone xenografts, FK 506-cyclophosphamide combination of immunosuppression will be useful even in the condition of surgical angiogenesis.
Capillaries ; Heterografts ; Immunosuppression ; Silicone Elastomers ; Transplants

This paper reviews and analyzes the modifications of silicone rubber, containing nanometer material tilling, plasma surface modification, surface grafting, mixture with bioactive substrates and bionic coating. At last, the author shows the prospect for the future development of silicone rubber modification.
Equipment and Supplies ; Humans ; Silicone Elastomers ; chemistry

A clinical analysis was done for 51 eyes of 50 retinal detachment patients, who operated in the Depart of Ophthalmology, Chungnam National University Hospital during last 3 years. The results were as follows: 1) The maximum incidence of detachment in this study occurred between the ages of 51 and 60 years (30 %), and the next over the age of 61 years (22 %), that was somewhat different comparing with other reports in Korea. Men were more common than women. 2) Of all retinal breaks, the round holes were most common (47.1 %), followed by dialyses (27.5 %) and horse-shoe tears(19.6 %) before the ages of 30 years, cases with disinsertions were frequently observed with trauma 3) The over aU success rate of retinal detachment surgery was 74.5 %. There was no effect on the success rate by the shapes and numbers of the retinal breaks. The shorter the duration. the better the preoperative vision, and the samller the extents of detached area showed the better success rate. 4) The most frequent and main causes of failure were massive vitreous retraction and giant tears. 5) No complications of silicon rubber was observed in the operated eyes, such as foreign body reaction or invasion into the globe after surgery.
Chungcheongnam-do ; Dialysis ; Female ; Foreign-Body Reaction ; Humans ; Incidence ; Korea ; Male ; Ophthalmology ; Retinal Detachment* ; Retinal Perforations ; Retinaldehyde* ; Rubber ; Silicone Elastomers*

The purpose of this study was to evaluate the force degradation rate of synthetic elastomeric chains during space closing phase of orthodontic treatment. Two kinds of synthetic elastomeric chains(RMO, 3M) were selected which were commonly used in clinics. All of the samples were extended and tested for 4 weeks under the simulated intraoral condition. The results can be summarized as follows : 1. Time related residual force showed typical logarithm function. Residual force after 4 weeks was 41.2~64.6 % of original force, and difference between two kinds of elastomeric chain existed. 2. Elastic force decreased greatly during first 10 minutes, so 20~25 % of original force disappeared. After that, this decreasing tendency was diminished significantly, average rate of elastic force after 1 week to 4 weeks were 1.5 % demonstrating rather constant force. 3. Even though the same brand of elastomeric chiain was used, as extension rate of elastomeric chain increased, force degradation rate increased by decreasing of residual force.
Elastomers*

PURPOSE: This study aimed to investigate the potential clinical application of digitized silicone rubber impressions by comparing the accuracy of zirconia 3-unit fixed partial dentures (FPDs) fabricated from 2 types of data (working model and impression) obtained from a laser scanner. MATERIALS AND METHODS: Ten working models and impressions were prepared with epoxy resin and vinyl polysiloxane, respectively. Based on the data obtained from the laser scanner (D-700; 3Shape A/S, Copenhagen, Denmark), a total of 20 zirconia frameworks were prepared using a dental CAD/CAM system (DentalDesigner; 3shape A/S, Copenhagen, Denmark / Ener-mill, Dentaim, Seoul, Korea). The silicone replicas were sectioned into four pieces to evaluate the framework fit. The replicas were imaged using a digital microscope, and the fit of the reference points (P1, P2, P3, P4, P5, P6, and P7) were measured using the program in the device. Measured discrepancies were divided into 5 categories of gaps (MG, CG, AWG, AOTG, OG). Data were analyzed with Student's t-test (alpha=0.05), repeated measures ANOVA and two-way ANOVA (alpha=0.05). RESULTS: The mean gap of the zirconia framework prepared from the working models presented a narrower discrepancy than the frameworks fabricated from the impression bodies. The mean of the total gap in premolars (P=.003) and molars (P=.002) exhibited a statistical difference between two groups. CONCLUSION: The mean gap dimensions of each category showed statistically significant difference. Nonetheless, the digitized impression bodies obtained with a laser scanner were applicable to clinical settings, considering the clinically acceptable marginal fit (120 microm).
Bicuspid ; Denmark ; Denture, Partial, Fixed ; Molar ; Seoul ; Silicone Elastomers ; Siloxanes