Cytokines as Diagnostic Biomarkers for Pulpitis: Exploring Their Role in Vital Pulp Therapy

By Drs. Mike Sabeti and Heather Kim

The dental pulp is often categorized into specific diagnostic terminology without recognizing the progressive nature of pulpal disease. Yet, pulpitis presents as a nuanced spectrum, encompassing various degrees of involvement and pathology¹. Previous studies have shown inconsistent correlations between clinical and histological findings in pulp inflammation^11,13. Research lacks prospective studies correlating pulp condition with distinct patient symptoms¹¹. An inaccurate diagnosis may result in superfluous treatment or the removal of a tooth that could have been saved. Current trend in endodontics has favored preserving the pulp appropriately to maintain the tooth’s natural strength and function through vital pulp therapy (VPT). While VPT can be an excellent treatment option in specific cases, it can also present a dilemma to clinicians: preserve pulp vitality and risk leaving infected tissue or remove the entirety of the pulp to attempt elimination of all inflamed tissue. Accurate determination of pulpal condition is thus pivotal in VPT. Research has shown correlations between specific cytokines and different clinical characteristics of pulpal inflammation². We hope to use cytokines as biomarkers in the future to better evaluate the extent of inflammation and predict pulp survival.

VPT was utilized in the past to primarily preserve radicular pulp in immature teeth³.  However, the scope of VPT has now expanded to facilitate pulp tissue repair and preservation in mature teeth, including those previously deemed as irreversible pulpitis^1,4.  The procedure involves removing the infected portion of the pulp and sealing the remaining tissue with calcium silicate-based materials to promote healing⁵.  This in turn presents several advantages over traditional root canal therapy (RCT). VPT most importantly, conserves natural tooth structure to maintain long-term function and durability. The treatment is hence less invasive for the patient. Research has also shown that pulpotomy can at times achieve better outcomes than RCT^6,7.

Traditional diagnostic methods, such as thermal testing and patient-reported symptoms, often do not reflect the true comprehensive state of the pulp. These methods primarily differentiate between vital and necrotic pulp while the line between specific stages of pulpal inflammation is often blurred^7,8. This diagnostic uncertainty may lead to overtreatment and overlook cases in which more conservative options, such as VPT, may be sufficient for success. Thus, there is a growing need for more reliable diagnostic tools to accurately assess pulpal health to determine the most appropriate treatment.

Recent research has explored the use of cytokines – signaling proteins that mediate and regulate the immune system – as biomarkers to improve pulpal diagnosis. Cytokines play a critical role in the inflammatory response and research has shown correlation between specific molecules and pulpal conditions^9,10. Through cytokines, we hope to recognize the presence and severity of pulpitis.

A review by Duncan et al. showed increased levels of IL-1b, IL-2, IL-6, IL-8, and tumor necrosis factor alpha (TNF-a) in cases of irreversible pulpitis compared to normal controls⁹. Similarly, Fouad et al found markedly elevated levels of MMP-9 and pro-inflammatory cytokines, including IL-1b, IL-2, IL-6, and TNF-a, in pulpitis¹¹. Sabeti et al. also found IL-1a, IL-6, and IL-8 to be prominently expressed in pulpal blood of pulpitis cases with a strong association to higher pain scores¹⁰.

TNF-a is a major cytokine involved in systemic inflammation and essential for the development of the inflammatory response through activation of other cytokines and molecules. TNF-a is significantly elevated in irreversible pulpitis, emphasizing its importance in the inflammatory processes within the dental pulp⁹.  IL-1, subcategorized as IL-1a and IL-1b, is another key mediator of the immune response through promoting inflammation and the recruitment of immune cells to infection sites. In particular, IL-1a stimulates prostaglandin production and boosts blood vessel permeability, which allows immune cells to infiltrate areas of infection and contribute to the inflammatory environment of pulpitis¹⁰. IL-6, which is upregulated by bacteria and irritants, is another cytokine that plays a critical role in the inflammatory response of the dental pulp. IL-6 promotes prostaglandin production while stimulating odontoblasts and recruiting neutrophils. IL-6 has been shown to be associated with increased pain in patients with pulpitis and has been linked to chronic conditions such as apical periodontitis¹⁰. Similarly, IL-8 has also demonstrated a correlation with higher presenting pain scores. IL-8 drives recruitment of neutrophils in response to bacteria and facilitates the inflammatory process, exacerbating the pain associated with pulpitis¹⁰. In addition to cytokines, MMP-9 is an enzyme that degrades components of the extracellular matrix (ECM) and influences tissue remodeling and repair. In the context of pulpitis, MMP-9 degrades the ECM within the dental pulp and thus, exacerbates the inflammatory process¹².

These cytokines collectively contribute to the pathophysiology of pulpitis, and we thereby see potential in the utilization of these molecules as biomarkers to predict specific pulpal conditions. By identifying specific inflammatory markers, clinicians can tailor individual treatment plans and better distinguish between reversible and irreversible pulpitis.

VPT represents a significant shift towards more conservative and individualized treatment in endodontics. The use of cytokines as biomarkers holds immense potential to enhance diagnostic accuracy and guide treatment decisions. We hope to have point-of-care testing in the future to enable on-site assessment of the pulpal status. This would allow clinicians to perform VPT with more predictable outcomes and avoid unnecessarily removing the pulp’s vitality when not required. Further research is needed to fully comprehend the relationships behind specific cytokines and pulpal conditions and to ultimately understand the complexity behind pulpitis.

References:

• Dummer PM, Hicks R, Huws D. Clinical signs and symptoms in pulp disease. Int Endod J 1980;13:27–35.
• Fouad AF, Khan AA, Silva RM, Kang MK. Genetic and epigenetic characterization of pulpal and periapical inflammation. Front Physiol 2020;11:1–11.
• Sabbagh S, Shirazi AS, Eghbal MJ. Vital pulp therapy of a symptomatic immature permanent molar with long-term success. Iranian Endodontic Journal. 2016;11(4):347.
• Langeland K. Management of the inflamed pulp associated with deep carious lesion. J Endod 1981;7:169–81.
• Gandolfi MG, Spagnuolo G, Siboni F, Procino A, Rivieccio V, Pelliccioni GA, Prati C, Rengo S. Calcium silicate/calcium phosphate biphasic cements for vital pulp therapy: chemical-physical properties and human pulp cells response. Clinical oral investigations. 2015 Nov;19:2075-89.
• Galani M, Tewari S, Sangwan P, et al. Comparative evaluation of postoperative pain and success rate after pulpotomy and root canal treatment in cariously exposed mature permanent molars: a randomized controlled trial. J Endod 2017;43:1953–62.
• Tomson PL, Vilela Bastos J, Jacimovic J, Jakovljevic A, Pulikkotil SJ, Nagendrababu V. Effectiveness of pulpotomy compared with root canal treatment in managing non-traumatic pulpitis associated with spontaneous pain: A systematic review and meta-analysis. J Endod.
• Ather A, Patel B, Gelfond JAL, Ruparel NB. Outcome of pulpotomy in permanent teeth with irreversible pulpitis: A systematic review and meta-analysis. J Endod. 2022;12(1):19664.
• Duncan HF. Present status and future directions-vital pulp treatment and pulp preservation strategies. Int Endod J 2022;55(Suppl 3):497–511. 1051.
• Sabeti MA, Nikghalb KD, Pakzad R, Fouad AF. Expression of selected inflammatory mediators with different clinical characteristics of pulpal inflammation. Journal of Endodontics. 2024 Mar 1;50(3):336-43.
• Fouad AF. Molecular characterization of irreversible pulpitis: a protocol proposal and preliminary data. Front Dent Med 2022;3:1–11.
• Ballal NV, Duncan HF, Wiedemeier DB, et al. MMP-9 Levels and NaOCl lavage in randomized trial on direct pulp capping. J Dent Res 2022;101:414–9.
• Karrar RN, Cushley S, Duncan HF, et al. Molecular biomarkers for objective assessment of symptomatic pulpitis: a systematic review and meta-analysis. J Endod 2023;56:1160–77.