Nasolabial Sulcus Rejuvenation: Paranasal Augmentation Using a Folded Dermal Graft.

BACKGROUND: Nasolabial sulcus rejuvenation is steadily gaining popularity among Asians. Though many treatment options using synthetic grafts and autografts have been introduced, none of them has yet been accepted as an ideal technique. This study describes the operative procedure and evidence-based clinical outcomes of paranasal augmentation using dermal grafts. METHODS: From March 2015 to August 2019, 56 patients underwent paranasal augmentation. The dermal graft, harvested from the buttock, was folded into 4 to 6 layers and inserted into the supraperiosteal pocket through a gingivobuccal incision. Ultrasonographic evaluation was performed at postoperative months 1, 6, 12, and 18 to appraise the change in the thickness of the graft. RESULTS: No major complications, including foreign body sensation and graft extrusion, occurred. The average dermal thickness was 10.31 mm at postoperative month 1 and 6.30 mm, 5.21 mm, and 5.17 mm at postoperative months 6, 12 and 18, respectively. The average absorption rates were 38.72%, 49.36%, and 49.92% at postoperative months 6, 12, and 18, respectively. CONCLUSIONS: Paranasal augmentation using a folded dermal graft serves as a useful method to rejuvenate the midface with durable and aesthetically satisfactory outcomes. By virtue of biocompatibility, complications occurred rarely compared with the artificial implants. LEVEL OF EVIDENCE IV: This journal requires that authors assign a level of evidence to each article. For a full description of these Evidence-Based Medicine ratings, please refer to the Table of Contents or the online Instructions to Authors www.springer.com/00266.

Augmentation Genioplasty Using Double Folded Dermal Graft.

INTRODUCTION: The chin is a very important aesthetic subunit of the face. The diverse materials and methods for chin augmentation can be classified according to autologous tissues and artificial ones. Among them, reports on the effectiveness of dermal graft for chin augmentation are scarce. The authors report on our new techniques and surgical results regarding chin augmentation using a dermal graft. PATIENTS AND METHODS: From July 2010 to January 2013, the authors performed supraperiosteal chin augmentation using a double folded dermal graft for 58 patients (15 men and 43 women; range of age: 20-45, average was 29.4). Periodic sonography was performed routinely to measure the change of thickness of the dermal graft (preoperative, postoperatively 1, 6, and 12 months). RESULTS: Thickness of the survived dermal graft was 8.33 ± 1.21 mm and 7.99 ± 1.19 mm at postoperative 6 and 12 months separately. Statistics showed that the average resorption rate was 32.17% (SD = 10.99) at postoperative 6 months and 34.93% (SD = 10.74) at postoperative 12 months. Of 56 patients 54 (2 patients were excluded from the study) did not request additional surgery during the 3-year follow-up period and showed a high level of satisfaction with the surgical results. CONCLUSIONS: The authors consider that our unique design and surgical techniques of double folded dermal graft have many advantages and provide consistent evidence-based results to meet patients' desire for a natural appearance after chin augmentation, particularly patients who refuse to get artificial implants.

Augmentation rhinoplasty using a folded "pure" dermal graft.

BACKGROUND: Although there are several reports about the use of dermal or dermofat grafts, there are only a few reports about augmentation rhinoplasty performed using a "pure" dermal graft. Authors introduce the refined techniques, clinical experience, and report an aesthetically pleasing result of augmentation rhinoplasty performed using a folded pure dermal graft. MATERIALS AND METHODS: Between 2008 and 2012, augmentation rhinoplasty was performed in 68 cases using a folded pure dermal graft. Pure dermal graft was harvested from one side of the buttock close to the intergluteal crease and the graft length was approximately 7-8 cm and the graft width was 1.5-2 cm, and the epidermis and fat were completely removed. Tip-plasty was performed using a conchal or septal cartilage as a columellar strut and an onlay graft. Pure dermal grafts are folded into 2 layers and sculpted to the desired size and shape, and are inserted into the supraperiosteal pocket. Ultrasonography was performed to know the absorption rate of the folded pure dermal grafts. RESULTS: The thickness of a dermal graft at postoperative 12 months was 60.3% of that at postoperative 1 month. Even with 39.7% of reduction in the thickness of the dermal graft, the height of nasal dorsum after postoperative 1 year is considered to be well maintained. Among the 68 cases that underwent augmentation rhinoplasty (43 primary and 25 secondary), most of the patients sustained consistent cosmetic results; however, 12 patients (17 %) showed over-absorption, under-absorption or contour irregularity of the dermal graft, and slight erythema. There were no aesthetically or medically serious problems needing secondary rhinoplasty such as hematoma formation, warping of the graft, graft extrusion, infection, and rejection of the graft. DISCUSSION: Augmentation rhinoplasty using a folded pure dermal graft has many advantages and is a very useful surgical option in patients who have an aversion to the use of artificial implants, who want to change the postoperative appearance of their nose due to insertion of an artificial implant into a more natural appearance, and when there is too much thinning of the skin due to repeated insertion of silicone implants.

Evaluation of Contact Heat Transfer Coefficient and Phase Transformation during Hot Stamping of a Hat-Type Part.

Using an inverse analysis technique, the heat transfer coefficient on the die-workpiece contact surface of a hot stamping process was evaluated as a power law function of contact pressure. This evaluation was to determine whether the heat transfer coefficient on the contact surface could be used for finite element analysis of the entire hot stamping process. By comparing results of the finite element analysis and experimental measurements of the phase transformation, an evaluation was performed to determine whether the obtained heat transfer coefficient function could provide reasonable finite element prediction for workpiece properties affected by the hot stamping process.

An Optimal Cure Process to Minimize Residual Void and Optical Birefringence for a LED Silicone Encapsulant.

Silicone resin has recently attracted great attention as a high-power Light Emitting Diode (LED) encapsulant material due to its good thermal stability and optical properties. In general, the abrupt curing reaction of the silicone resin for the LED encapsulant during the curing process induces reduction in the mechanical and optical properties of the LED product due to the generation of residual void and moisture, birefringence, and residual stress in the final formation. In order to prevent such an abrupt curing reaction, the reduction of residual void and birefringence of the silicone resin was observed through experimentation by introducing the multi-step cure processes, while the residual stress was calculated by conducting finite element analysis that coupled the heat of cure reaction and cure shrinkage. The results of experiment and analysis showed that it was during the three-step curing process that the residual void, birefringence, and residual stress reduced the most in similar tendency. Through such experimentation and finite element analysis, the study was able to confirm that the optimization of the LED encapsulant packaging process was possible.