Evaluation of Pulp Repair after BiodentineTM Full Pulpotomy in a Rat Molar Model of Pulpitis

Abstract

Dental pulp is a dynamic tissue able to heal after injury under moderate inflammatory conditions. Our study aimed to evaluate pulp repair under inflammatory conditions in rats. For this purpose, we developed a rat model of controlled pulpitis followed by pulpotomy with a tricalcium silicate-based cement. Fifty-four cavities were prepared on the occlusal face of the maxillary upper first molar of 27 eight-week-old male rats. E. coli lipopolysaccharides at 10 mg/mL or phosphate-buffered saline PBS was injected after pulp injury. Non-inflamed molars were used as controls. Levels of inflammation-related molecules were measured 6 and 24 h after induction by enzyme-linked immunosorbent assay of coronal pulp samples. Pulp capping and coronal obturation after pulpotomy were performed with tricalcium silicate-based cement. Four and fifteen days after pulpotomy, histological and immunohistochemical analysis was performed to assess pulp inflammation and repair processes. Our results showed significantly higher levels of innate inflammatory proteins (IL-1β, IL-6, TNF-α and CXCL-1) compared with those in controls. Moderate residual inflammation near the capping material was demonstrated by histology and immunohistochemistry, with the presence of few CD68-positive cells. We showed that, in this model of controlled pulpitis, pulpotomy with BiodentineTM allowed the synthesis at the injury site of a mineralized bridge formed from mineralized tissue secreted by cells displaying odontoblastic characteristics. Analysis of these data suggests overall that, with the limitations inherent to findings in animal models, pulpotomy with a silicate-based cement is a good treatment for controlling inflammation and enhancing repair in cases of controlled pulpitis.

A critical analysis of research methods and experimental models to study pulpitis

“…The vast majority of the models used bacterial PAMPs purified from the bacterial cell wall as inductive molecules to mimic the action of caries-related Gram-positive (for LTA) or Gram-negative (for LPS) bacteria on the pulp. LPS seems to induce similar and reproducible pulp inflammatory responses (Cleaton-Jones et al, 2004;Hahn et al, 2000) and it has been widely used by the community (Chung et al, 2011;Minic et al, 2021;Okiji, 1989;Renard et al, 2016;Songsiripradubboon et al, 2017). However, bacterial inducers often originate from microorganisms not involved in caries formation, being mostly derived from Bacillus subtilis, S. aureus, E. faecalis (for LTA) or Escherichia coli (for LPS).…”

“…In a similar model, elevation of autophagy‐associated protein level was observed in irreversibly inflamed rat pulp, suggesting the association of autophagy mechanisms to pulpitis development (Qi et al, 2019). Recently, the levels of IL‐1β, IL‐6, TNF‐α and CXCL‐1 were shown to be equally up‐regulated 6 h or 24 h after LPS‐induced inflammation in rat molars, suggesting that short stimulation times are sufficient to observe modifications of the pro‐inflammatory cytokine level (Minic et al, 2021). Pulpitis was also induced in continuously growing rat maxillary incisors.…”

“…Another important factor is the nature of the material used to restore the dentine cavity since it represents a potential physical‐chemical irritant that could influence pulp inflammation features. Interestingly, cavity‐filling biomaterials such as MTA or Biodentine ® induce minimal pulp inflammation and they may constitute a good option to study bacterial‐ or by‐product‐induced pulp responses (Minic et al, 2021; Santos et al, 2021).…”

A critical analysis of research methods and biological experimental models to study pulp regeneration

“…Moreover, as most small animal models are rodents, there is always the concern about high cell turnover and constant root development, which do not mimic the conditions found in humans. Nonetheless, pulp regeneration studies that specifically address the effects of pulp capping materials and/or pulpotomies are still possible in rodents, as some studies have proven (Minic et al, 2021). However, for full pulp regeneration studies, these species present too many disadvantages to provide meaningful data, leading to the preference for larger animal models (Mangione et al, 2021; Nakashima et al, 2019).…”

TheraCal as the material of choice for direct pulp treatment compared to two other materials: MTA and biodentine

“…In an animal study it was demonstrated that Biodentine allowed the synthesis at the lesion site of a mineralized bridge formed from mineralized tissue secreted by cells exhibiting odontoblastic characteristics [30] . It was concluded that, on clinical and histological evaluation, Biodentine performed better as a direct pulp capping treatment agent.…”