 Statistical Analyses Quantitative data were recorded as mean and standard deviations. No data points were missing. Sample size was determined by Power analysis, assuming a standard deviation of the difference of 0.5, which indicated that with a sample of 20 subjects, the study would have 90 power to detect a 1-mm difference in the primary outcome measures PAL gain and CEJ-BD reduction between the two groups. In order to verify the normality of the data, the kurtosis and skewness curves were used. Because all data were considered to be normal for the parameters analysed, Students paired t-test was used for intra-group baseline versus 12 months and inter-group test versus control comparisons. The level of significance set at 5 was used in all statistical comparisons performed in the software ProStat Poly Software International, Pearl River, NY, USA . 