## 3 Results  
### Demographic Information  
A total of 38 patients requiring 40 root canal treatments were accepted to be included in the study (Figure 1). Two patients contributing with two root canal treatments (5%) were unable to complete the follow-up and were excluded. A total of 38 teeth were analysed at the end-line. Information on patient and tooth-related parameters is reported in Table 2, while obturation-related parameters are reported in Table 3a,b. The pilot cohort included a high number of teeth with a periapical lesion (PAI \(\geq\) 3) (47%), pulp necrosis (21%), and re-exacerbated periapical lesion (26%). The majority of root canal obturation length was considered adequate (79%), while 10% resulted in overfilled and 13% were underfilled. Sealer periapical extrusion was observed in a high percentage of cases (47%). Most of the radiographic extrusion resulted in smaller than 5 mm. The cumulative percentage of healed teeth at 12 months was 82% (95% CI 67-91%). Seven out of thirty-eight teeth presented a periapical radiolucency after 12 months (18%). Cumulative survival rate was 100% (95%CI = 94-100%). Figure 1: Endline PAI, frequency of post-operative Pain and sealer stability between teeth with preoperative PAI 1–2 versus teeth with a preoperative PAI 3–5. No differences in post-operative Pain distribution were observed at 12 months between the two groups. Two root canal treatments still presented a slight tenderness to percussion at 1-year follow-up. Teeth with preoperative PAI \(>\) 2 had a higher percentage of healing lesions and a higher percentage of sealer resorption. Patient-related characteristics (age, sex, tooth location, and type) did not influence the healing percentage. Interestingly, at the tooth level, the type of treatment (root canal treatment vs. retreatment) did not influence the healing percentage (\(p\)-value = 0.472). Initial PAI was significantly related to periapical healing; that is, teeth with a preoperative PAI > 2 had lower healing rates at 12 months (\(p\)-value = 0.001) (Table 3a). As shown in Table 3b, obturation length, sealer extrusion and extrusion size did not influence the outcome (all \(p\)-values > 0.05). Interestingly, healed teeth exhibited a lower periapical sealer resorption as compared with healing teeth (43% vs. 75%), but the difference was not statistically significant due to small sample sizes (\(p\)-value = 0.333). \begin{table}
\begin{tabular}{l c} \hline \hline
**Characteristic** & **All (_n_ = 38)** \\ \hline Sex & \\ Male & 16 (42\%) \\ Female & 22 (58\%) \\ \hline Age group & \\ \textless{}30 & 6 (16\%) \\ 30–54 & 17 (45\%) \\ \(\geq\)55 & 15 (39\%) \\ \hline Tooth type & \\ Anterior & 6 (16\%) \\ Premolar & 14 (37\%) \\ Molar & 18 (47\%) \\ \hline Tooth location & \\ Maxilla & 26 (68\%) \\ Mandible & 12 (32\%) \\ \hline Diagnosis & \\ Pulpitis & 20 (53\%) \\ Pulp necrosis & 8 (21\%) \\ Re-exacerbated lesion & 10 (26\%) \\ \hline Baseline PAI & \\ 1–2 & 20 (53\%) \\ \(\geq\)3 & 18 (47\%) \\ \hline Endodontic treatment & \\ Root canal treatment & 28 (74\%) \\ Re-treatment & 10 (26\%) \\ \hline Obturation & \\ Underfilled & 4 (11\%) \\ Adequate filling & 30 (79\%) \\ Overfilled & 4 (11\%) \\ \hline Extrusion & \\ No & 20 (53\%) \\ Yes & 18 (47\%) \\ \hline Extrusion, mm & \\ No extrusion & 20 (53\%) \\
0.1–2.0 & 9 (24\%) \\
2.1–5.0 & 6 (16\%) \\ \(>\)5.0 & 3 (8\%) \\ \hline \hline \end{tabular}
\begin{tabular}{l c} \hline \hline
**Sealer Resorption * & \\ No & 9 (50\%) \\ Yes & 9 (50\%) \\ \hline \hline \end{tabular}  
* Among extrusions (_n_ = 18).  
\end{table} 
Table 2: Patient and tooth-related characteristics of the study at baseline. month (_p_-value = 0.007), and 12 months (_p_-value = 0.011) after obturation; that is, patients with no pain had higher healing percentages (Table 4). Figure 1 depicts endemic PAI, frequency of post-operative pain and sealer stability between teeth with no preoperative periapical lesion (PAI 1-2) versus teeth with a preoperative periapical lesion (PAI 3-5).