## 3 Results
### Dentine Pulp Complex Response
#### 3.1.4. Residual Dentin Thickness and Tertiary Dentin Formation  
Figure 6a indicates the remaining dentin thickness (RDT) in all the cavities of c-GIC and nano-HA-SiO\({}_{2}\)-GIC occlusal and cervical restorations at different time intervals, which shows that all cavities had a RDT of \(\sim\)200 \(\upmu\)m, which is appropriate for investigating the pulp complex response to any restorative materials. For occlusal cavities, in both groups of restorations, RDT was in the range of 192-218 \(\upmu\)m and for cervical cavities, RDT was in the range of 163-179 \(\upmu\)m. Morphometric evaluation indicates that neither specific factors (type of material and time of being euthanized) nor their interrelation were statistically significant (statistical data not shown). Therefore, all cavities prepared on occlusal and cervical aspects had almost comparable RDTs, hence the reproducibility of the procedures we performed was demonstrated. A significant difference in results was detected when the tertiary dentin thickness (TDT) of both c-GIC and nano-HA-SiO\({}_{2}\)-GIC in first molars was compared with second molars (which was taken as negative control). These results in Table 4 and Figure 6b show that both types of restoration (c-GIC and nano-HA-SiO\({}_{2}\)-GIC) had a reasonable inductive influence on the deposition of tertiary dentin as compared with second molars. Although nano-HA-SiO\({}_{2}\)-GIC showed higher TDF compared to c-GIC, the result was not statistically significant. Also, there was more TDF in cervical restorations as compared to occlusal restorations, which is observed in Figure 6b. \begin{table}
\begin{tabular}{c c c c c} \hline \hline  & **Occlusal 1 Week** & **Occlusal 1 Month** & **Cervical 1 Week** & **Cervical 1 Month** \\ \cline{2-5}  & **Mean (SD)** & **Mean (SD)** & **Mean (SD)** & **Mean (SD)** \\ \hline
**Nano-HA-SiO\({}_{2}\)-GIC** & 96.66 (41.24) & 100.10 (56.53) & 85.82 (17.69) & 219.59 (118.85) \\ \hline
**c-GIC** & 66.21 (43.15) & 78.29 (54.55) & 83.30 (70.34) & 185.72 (112.51) \\ \hline
**2 nd molar** & 31.97 (5.30) & 44.48 (7.79) & 30.70 (21.18) & 23.38 (7.51) \\ \hline  & \(p\): 0.005 \({}^{*}\) & \(p\): 0.070 & \(p\): 0.075 & \(p\): 0.001 \({}^{*}\) \\ \hline \hline \end{tabular} \({}^{*}\) indicates significant difference between cGIC and nano-HA-SiO2-GIC (\(p\leq 0.05\)).  
\end{table} 
Table 4: Comparisons of tertiary dentin thickness of nano-HA-SiO\({}_{2}\)-GIC, c-GIC, and 2 nd molar (negative control) on various days using one-way ANOVA. Figure 5: (**A–D**) (4\(\times\), 10\(\times\), and 40\(\times\)): Microscopic view of cervical restoration with c-GIC at a 1-month interval (H&E and trichrome showing new dentin formation). (**D**) shows the bacterial detection under Brown and Brenn staining. At the 1-week interval of occlusal restorations, 80% of the teeth restored with nano-HA-SiO\({}_{2}\)-GIC showed Grade 1 deposition of tertiary dentin, whereas samples of the positive control c-GIC group showed 50% of Grade 1 tertiary dentin deposition (\(p>0.05\)). Teeth that underwent a 1-month intervention showed almost similar results for both types of restorations. With regards to the cervical type of restorations, both materials exhibited similar responses at the 1-week interval, but at the 1-month interval, nano-HA-SiO\({}_{2}\)-GIC showed a better response than c-GIC in which 60% of the teeth exhibited Grade 3 TDF, whereas this grade was only observed in 30% of c-GIC-restored teeth. It was also noted that the nano-HA-SiO\({}_{2}\)-GIC group displayed better deposition of tertiary dentin formation as shown in Figure 7. This is in comparison to the c-GIC group in terms of thickness and extension of the tertiary dentin deposition along the cavity wall, as shown earlier in Figure 6b. Figure 6: (**a**): Comparison of RDT values shown by c-GIC and nano-HA-SiO\({}_{2}\)-GIC in both cervical and occlusal restorations in different interventional periods. (**b**): Comparison of TDT values among 2 nd molar, c-GIC, and nano-HA-SiO\({}_{2}\)-GIC for both materials at different time intervals.