Based on a previous study by Azuma et al. in 2014 [13 (link)], the clinical important difference in DAn between the two groups was expected to be 6, with a standard deviation (SD) of the control group was ±4.38. Considering a significance level of 5.0% and statistical power of 80.0%, 9 patients per group would be necessary (18 totals). Taking into account possible losses to follow-up, this number was increased to a sample size of 11 patients per group (22 totals; 20% more than the calculated) for losses compensation. The sample size was calculated using PS program.
Data analysis was conducted using IBM SPSS advanced statistics, version 24 (SPSS Inc., Chicago, IL). Summary statistics were presented with either the mean ± standard deviation or the median (range) for numerical data and with counts and percentages for categorical data. Kolmogorov-Smirnov test and Shapiro-Wilk test were used to explore the data for normality. The Student’s t-test was used to compare the normally distributed numeric variables of aesthetic outcomes and operation times, while comparisons for non-normally distributed numerical variables were done by Mann-Whitney test. Comparisons between categorical variables were performed using the chi-square test. A P-value less than or equal to 0.05 (P ≤ 0.05) was considered statistically significant. All tests were two-tailed.
Data analysis was conducted using IBM SPSS advanced statistics, version 24 (SPSS Inc., Chicago, IL). Summary statistics were presented with either the mean ± standard deviation or the median (range) for numerical data and with counts and percentages for categorical data. Kolmogorov-Smirnov test and Shapiro-Wilk test were used to explore the data for normality. The Student’s t-test was used to compare the normally distributed numeric variables of aesthetic outcomes and operation times, while comparisons for non-normally distributed numerical variables were done by Mann-Whitney test. Comparisons between categorical variables were performed using the chi-square test. A P-value less than or equal to 0.05 (P ≤ 0.05) was considered statistically significant. All tests were two-tailed.