group was 45.14 years (range, 26 to 60 years). Themean age of patients in the Restylane 2 groupwas 44.83 years (range, 28 to 60 years). In theRestylane 2 group, 21 subjects were defined as havinga Wrinkle Severity Rating Scale grade of 3 and20 were grade 4; in the Dermalax DEEP group, 24subjects were defined as having a Wrinkle SeverityRating Scale grade of 3 and 17 were grade 4.For hyaluronic acid injection, the average volumeinto each side of nasolabial folds was 0.76 ml ofRestylane 2 and 0.68 ml of Dermalax DEEP. Thetwo groups did not display any significant differencesin the Wrinkle Severity Rating Scale gradeand hyaluronic acid volumes.As expected, the skin exhibited a three-layerstructure by analysis with high-frequency ultrasound(Fig. 1, above, left). Interestingly, the epidermispresented as a bright hyperechogenic linewith a mean thickness of 0.15 mm, and the dermisappeared to be a homogenous hypoechogenicband with a hyperechogenic area beneath it. Twoweeks after treatment, the dermis was obviouslynoted to be thicker, with less echogenicity Meanwhile, the results of WrinkleSeverity Rating Scale also revealed decreasesof three grades in 22 subjects, two grades in 50subjects, and one grade in 10 subjects 2 weeksafter injection (Fig. 2). The data regarding dermalthickness are summarized and presented inFigure 3.The dermal thickness of all subjects beforetreatment was 1.45 ± 0.16 mm (minimum,1.03 mm; maximum, 1.84 mm). Impressively,significant elevations of dermal thickness wereobserved in all subjects after hyaluronic acid injection(Fig. 1, above, right, and below, left and right).The increase in dermal thickness from baselinewas determined to be 40.29 percent at 2 weeks,21.34 percent at 24 weeks, and 11.74 percent at 48weeks after injection (Fig. 3, left). However, a dramaticreduction of dermal thickness was observedat 48 weeks after injection compared with that at24 weeks. Repeated measures analysis of varianceshowed significant differences (p < 0.001) in allsubjects at 2, 24, and 48 weeks after injection, anddemonstrated a time effect in the increased dermalthickness.At 2 and 24 weeks after injection, the increaseddermal thicknesses were 0.57 ± 0.20 and 0.270.18 mm in the Restylane 2 group and 0.59 ± 0.15and 0.34 ± 0.14 mm in the Dermalax DEEP group,respectively (Fig. 3, right). Both Restylane 2 andDermalax DEEP injection resulted in satisfactorycosmetic outcomes in nasolabial fold correctionwithin 24 weeks after injection. At 48 weeks afterinjection, however, increased dermal thickness inthe Restylane 2 group (0.14 ± 0.12 mm) was muchless than that of the Dermalax DEEP group (0.20± 0.13 mm). Variation between groups was demonstratedto be statistically significant (p < 0.01),with a linear trend of time between groups (p <0.05). These findings indicate that relative to DermalaxDEEP, Restylane 2 may be more prone to bediffused or degraded and displays much shorterlongevity in vivo. Compared with 2 weeks aftertreatment, the average Wrinkle Severity RatingScale scores of the Dermalax DEEP and Restylane2 groups increased 0 and 0.107 at 24 weeks and0.293 and 0.327 at 48 weeks, respectively. Therewas no significant difference on Wrinkle SeverityRating Scale scores at 24 and 48 weeks betweenthe two groups. However, given that the WrinkleSeverity Rating Scale scores are not sufficientlydetailed, the possibility of clinically significant differencesmay not be excluded.