# Quantitative Ultrasound Analysis of Oral Mucosa: An Observational Cross-Sectional Study
## 3 Results  
This study analyzed 330 images of healthy oral mucosa. The mean scan distance was 4.378 (\(\pm\)0.86) mm, which corresponded to the EP's target depth (TD). The other TDs and the ICC are shown in Table 2.  
For the quantitative ultrasound parameters, the assumption of homogeneity of variances was violated, as assessed by [PERSON]'s test for equality of variances (_p_ = 0.001), so a Games-Howell test was performed to assess the differences between groups. A comparison of ELs shows a difference between subgroups (_p_ = 0.001). In particular, as regards the mucous layer, EP was not different from CL (_p_ = 0.831), but these two tissues \begin{table}
\begin{tabular}{l l r r r r r} \hline \hline
**Tissue Layers** & **US Parameters** & **EL (dB)** & **GL (B-bit)** & **ATT (dB/cm)** & **TD (cm)** & **ICC (Sig.)** \\ \hline \multirow{3}{*}{EP} & _Mean_ & \(-41.073\) & \(149.205\) & \(-97.268\) & \(0.438\) & \\  & _SD_ & \(5.84\) & \(15.04\) & \(25.21\) & \(0.09\) & \(0.871\) (_p = 0.001_) ** \\  & _Minimum_ & \(-50.44\) & \(125.08\) & \(-143.20\) & \(0.27\) & \(0.871\) (_p = 0.001_) ** \\  & _Maximum_ & \(-29.11\) & \(180.01\) & \(-45.78\) & \(0.64\) & \\ \hline \multirow{3}{*}{EP-RR} & _Mean difference (SE)_ & \(26.18\) (\(\pm 1.17\)) & \(73.21\) (\(\pm 4.34\)) & \(49.73\) (\(\pm 7.14\)) & & \\  & _Sig.(p-value)_ & \(0.001\) ** & \(0.001\) ** & \(0.001\) ** & & \\ \hline \multirow{3}{*}{RR} & _Mean_ & \(-67.259\) & \(75.994\) & \(-147.003\) & \(0.470\) & \\  & _SD_ & \(8.33\) & \(19.87\) & \(32.34\) & \(0.09\) & \(0.880\) (_p = 0.001_) ** \\  & _Minimum_ & \(-82.77\) & \(31.00\) & \(-203.38\) & \(0.29\) & \\  & _Maximum_ & \(-45.40\) & \(108.98\) & \(-84.99\) & \(0.67\) & \\ \hline \multirow{3}{*}{RR-CL} & _Mean difference (SE)_ & \(-27.85\) (\(\pm 1.89\)) & \(-77.51\) (\(\pm 4.34\)) & \(-66.08\) (\(\pm 6.81\)) & & \\  & _Sig.(p-value)_ & \(0.001\) ** & \(0.001\) ** & \(0.001\) ** & & \\ \hline \multirow{3}{*}{CL} & _Mean_ & \(-39.406\) & \(143.500\) & \(-80.9206\) & \(0.501\) & \\  & _SD_ & \(7.00\) & \(18.05\) & \(22.04\) & \(0.09\) & \\  & _Minimum_ & \(-53.94\) & \(116.07\) & \(-119.76\) & \(0.33\) & \\  & _Maximum_ & \(-29.09\) & \(180.06\) & \(-42.88\) & \(0.68\) & \\ \hline \multirow{3}{*}{CL-ML} & _Mean difference (SE)_ & \(-3.27(\pm 1.89)\) & \(-8.44(\pm 4.69)\) & \(-24.85(\pm 4.46)\) & & \\  & _Sig.(p-value)_ & \(0.383\) & \(0.383\) & \(0.001\) ** & & \\ \hline \multirow{3}{*}{ML} & _Mean_ & \(-36.130\) & \(161.939\) & \(-56.071\) & \(0.644\) & \\  & _SD_ & \(7.77\) & \(20.01\) & \(13.02\) & \(0.13\) & \\  & _Minimum_ & \(-52.49\) & \(119.80\) & \(-76.59\) & \(0.39\) & \\  & _Maximum_ & \(-26.80\) & \(185.97\) & \(-31.83\) & \(0.84\) & \\ \hline \multirow{3}{*}{Bone} & _Mean_ & \(-16.571\) & \(212.315\) & \(-26.482\) & \(0.659\) & \\  & _SD_ & \(4.35\) & \(11.20\) & \(8.25\) & \(0.11\) & \\ \cline{1-1}  & _Minimum_ & \(-25.55\) & \(189.19\) & \(-40.01\) & \(0.44\) & \\ \cline{1-1}  & _Maximum_ & \(-7.02\) & \(236.92\) & \(-10.43\) & \(0.85\) & \\ \hline \multirow{3}{*}{Bone-CL} & _Mean difference (SE)_ & \(22.83\) (\(\pm 1.43\)) & \(58.82\) (\(\pm 3.70\)) & \(54.44\) (\(\pm 4.10\)) & & \\ \cline{1-1}  & _Sig.(p-value)_ & \(0.001\) ** & \(0.001\) ** & \(0.001\) ** & \(0.001\) ** & \\ \hline \hline \end{tabular}  
* Statistical significance (Sig.) with Bonferroni correction \(p\) \(<\) 0.01; ** Sig. set at _p = 0.05_. Standard deviation (SD) and standard error (SE) have been reported. Accronyms in alphabetic order: ATT = attenuation; CL = connective; ELs = echo levels; EP = epithelium; GL = greyscale levels; ICC = intraclass correlation coefficient; ML = muscular layer; RR = rete ridges; TD = target depth.  
\end{table} 
Table 2: Descriptive statistics of quantitative ultrasound parameters. are always separated by RR, which was found to have significantly lower EL than both EP (\(p\) = 0.001) and submuc (CL; \(p\) = 0.001). In the MM, the bone had mean ELs of \(-\)16,571 (\(\pm\)4.3) dB. The difference from the overlying CL was 22.83 (\(\pm\)1.43)--\(p\) = 0.001.