## 3 Results
### Alveolar Bone Crest Level (RCF Versus Non-RCF Teeth)  
A total of 940 periodontal measuring points in each group were analyzed for both groups, RCF and n-RCF. No statistically significant differences (\(p>0.05\)) were detected between teeth with root canal fillings (2.64 \(\pm\) 1.25 mm) and those without root canal fillings (2.61 \(\pm\) 1.16 mm) (Table 1; Figure 2). The pairwise comparisons of both the mean values of each individual and of all individual measuring points show a marked scattering. A linear regression analysis reveals a gradient of 0.91 with a determination coefficient (R2) of 0.0001 indicating that a linear relationship cannot be assumed (Figure 2). \begin{table}
\begin{tabular}{c c c c c c c c} \hline \hline  & & & \multicolumn{4}{c}{**Distance C�j**—**Alveolar Bone Crest (mm)**} \\ \cline{3-8}
**No of** & **RCF** & & **Mesial** & **Distal** & **
\begin{tabular}{c} **Lingual/** \\ **Palatal** \\ \end{tabular}** & **Buccal** & **Mean** \\ \hline
235 & yes & mean \(\pm\) sd & 2.51 \(\pm\) 1.09 & 2.70 \(\pm\) 1.53 & 2.73 \(\pm\) 1.22 & 2.55 \(\pm\) 1.12 & 2.64 \(\pm\) 1.24 \\  & & CI 95\% & 2.37-2.65 & 2.49-2.84 & 2.58-2.89 & 2.42-2.70 & 2.51-2.77 \\  & & range & 0.28 & 0.35 & 0.41 & 0.28 & 0.26 \\ \hline
235 & no & mean \(\pm\) sd & 2.52 \(\pm\) 1.22 & 2.64 \(\pm\) 1.22 & 2.70 \(\pm\) 1.10 & 2.59 \(\pm\) 1.11 & 2.61 \(\pm\) 1.16 \\  & & CI 95\% & 2.37–2.68 & 2.48–2.79 & 2.55–2.84 & 2.45–2.73 & 2.49–2.73 \\  & & range & 0.31 & 0.31 & 0.29 & 0.28 & 0.24 \\ \hline \(\Sigma\)470 & \(p\)-value & & 0.789 & 0.601 & 0.776 & 0.555 & 0.810 \\ \hline \hline \end{tabular}
\end{table} 
Table 1: Distance C�j—alveolar bone crest in the matching pairs with 95% confidence interval and the corresponding range; CEJ = cemento–enamel-junction; RCF = root canal filling; CI = confidence interval. Figure 2: (**Top**) Pairwise comparison of the mean values of matching teeth in each individual concerning ABC-level of RCF and n-RCF teeth. (**Bottom**) Comparison of all measured values ((RCF vs. n-RCF; mesial, distal, lingual/palatal, buccal = \(\sum\)1180) between the CEJ and the ABC-level at each measuring point. \begin{table}
\begin{tabular}{c c c c c c c c c c} \hline \hline  & & & & & & & & & \\ \cline{3-10}
**Location** &
\begin{tabular}{c} **No of** \\ **Teeth** \\ \end{tabular} & **RCF** & \multicolumn{2}{c}{**Mesial**} & \multicolumn{2}{c}{**Distal**} & \multicolumn{2}{c}{**Diasual/**} & \multicolumn{2}{c}{**Buccal**} & \multicolumn{2}{c}{**Mean**} & \multicolumn{2}{c}{**Pooled**} \\ \cline{2-10} upper jaw & \(118\) & yes & mean \(\pm\) sd & 2.56 \(\pm\) 1.08 & 2.73 \(\pm\) 1.34 & 2.91 \(\pm\) 1.21 & 2.67 \(\pm\) 1.10 & 2.72 \(\pm\) 1.19 & \\  & & & CI 95\% & 2.36–2.75 & 2.49–2.98 & 2.68–3.13 & 2.47–2.87 & 2.54–2.89 & \\  & & & range & 0.39 & 0.49 & 0.45 & 0.40 & 0.35 & 2.74 \(\pm\) 1.22 \\ upper jaw & \(118\) & no & mean \(\pm\) sd & 2.63 \(\pm\) 1.27 & 2.71 \(\pm\) 1.39 & 2.93 \(\pm\) 1.20 & 2.73 \(\pm\) 1.11 & 2.76 \(\pm\) 1.25 & \\  & & & CI 95\% & 2.40–2.86 & 2.45–2.96 & 2.72–3.16 & 2.54–2.95 & 2.58–2.94 & \\  & & & range & 0.46 & 0.49 & 0.44 & 0.41 & 0.36 & \\ \hline upper jaw & 236 & \(p\)-value & 0.640 & 0.980 & 0.909 & 0.586 & 0.773 & \\ lower jaw & \(117\) & yes & mean \(\pm\) sd & 2.46 \(\pm\) 1.09 & 2.68 \(\pm\) 1.71 & 2.56 \(\pm\) 1.21 & 2.44 \(\pm\) 1.12 & 2.55 \(\pm\) 1.31 & \\  & & & CI & 2.26–2.66 & 2.33–2.86 & 2.35–2.80 & 2.25–2.67 & 2.35–2.72 & \\  & & & range & 0.40 & 0.53 & 0.45 & 0.38 & 0.37 & 2.51 \(\pm\) 1.18 \\ lower jaw & \(117\) & no & mean \(\pm\) sd & 2.42 \(\pm\) 1.15 & 2.56 \(\pm\) 1.03 & 2.45 \(\pm\) 0.93 & 2.43 \(\pm\) 1.08 & 2.47 \(\pm\) 1.05 & \\  & & & CI & 2.20–2.63 & 2.38–2.75 & 2.28–2.62 & 2.23–2.63 & 2.31–2.62 & \\  & & & range & 0.43 & 0.37 & 0.34 & 0.40 & 0.31 & \\ \hline lower jaw & 234 & \(p\)-value & 0.898 & 0.252 & 0.773 & 0.867 & 0.568 & \\ \hline total & 470 & \(p\)-value & & & & & & \\ \hline \hline \end{tabular}
\end{table}