Dentinal Fluid: Unravelling the Mysteries Beneath the Surface

1. Postgraduate Student, Department of Conservative Dentistry and Endodontics, Bharati Vidyapeeth Deemed to be University Dental College and Hospital, Pune, Maharashtra, India. 2. Professor, Department of Conservative Dentistry and Endodontics, Bharati Vidyapeeth Deemed to be University Dental College and Hospital, Pune, Maharashtra, India. 3. Assistant Professor, Department of Oral Pathology and Microbiology, Bharati Vidyapeeth Deemed to be University Dental College and Hospital, Navi Mumbai, Maharashtra, India. 4. Assistant Professor, Department of Conservative Dentistry and Endodontics, Bharati Vidyapeeth Deemed to be University Dental College and Hospital, Pune, Maharashtra, India. 5. Assistant Professor, Department of Conservative Dentistry and Endodontics, Bharati Vidyapeeth Deemed to be University Dental College and Hospital, Pune, Maharashtra, India.

Abstract

The Dentinal Fluid (DF), often referred to as dentinal microcirculation, represents the interstitial fluid within the Dentinal Tubules (DT). Understanding the dynamics of DF is pivotal in comprehending the physiology and pathology of the dental pulp. The composition of the DF, including ions, proteins, and growth factors, plays a critical role in maintaining pulp vitality, but imbalances can lead to various pathological conditions, such as dental hypersensitivity, pulpitis and pulp necrosis. The present review provides insight into the multifaceted role of DF in endodontics, highlighting its significance in pulp nutrition, defense mechanisms, and the mediation of inflammatory responses. Furthermore, it explores the various pathologies that can disrupt the delicate balance of DF, leading to adverse clinical outcomes.

Dental pulp, Dental pulp necrosis, Intertubular fluid, Microcirculation, Pulpitis

The DF originates from the terminal cytoplasmic extensions of the odontoblasts in the pulp and diffuses into the dentinoenamel junction (1). The composition of the DF is a complex and dynamic mixture of water, ions, and proteins that fill the microscopic spaces between the DT. Understanding its composition is crucial in unravelling its role in dental health and various physiological processes within the tooth structure. It’s important to note that DF flow is not a uniform response and can vary from person to person based on factors such as individual tooth anatomy, the condition of the dentin, and the presence of underlying dental issues. For example, during inflammation or infection in the dental pulp, there may be an increase in the concentration of inflammatory mediators within the DF (1). This alteration in composition can lead to changes in fluid dynamics, affecting the overall health and vitality of the tooth.

Understanding the changes in DF is crucial for diagnosing and managing dental conditions. Dental professionals can utilise techniques like fluid analysis or imaging methods to assess the composition, flow, and changes in DF (2). This information aids in the diagnosis of dental diseases, evaluation of treatment outcomes, and development of targeted therapies to address specific dental concerns. Researchers are actively studying the changes in DF and exploring innovative approaches to promote dentin regeneration, remineralisation, and the development of biomimetic materials that mimic the properties of natural DF (2). These advancements aim to improve dental treatments and enhance oral health outcomes for patients. Changes in DF can occur due to inflammation, dental caries, dental treatments, dentin hypersensitivity, and ageing (3). Understanding these changes contributes to the diagnosis, management, and development of effective treatments for various dental conditions, ultimately promoting better oral health. This literature attempted to shed light on the less talked-about topic of DF, which is actually “The Lifeline of the Teeth."

Physiological Characteristics of Dentinal Fluid (DF)

General Composition of Dentinal Fluid (DF)

Water constitutes the major component of DF, accounting for about 95% of its volume, while inorganic ions such as calcium and phosphorous are present along with organic components comprising proteins such as albumin, globulin, and growth factors (2). The various functions of the components of DF are tabulated in (Table/Fig 1) (4).

Response to Occlusal Load

The movement of DF through the porous pathways between DT elicits a response from the tooth structure when subjected to mechanical loads. The fluid-filled DT acts as hydraulic cushions to dissipate the occlusal forces applied to the bulk dentin (5). It has been demonstrated, through observing coffee particles suspended in water moving through a capillary continuous with the apical canal under a light microscope, that the DF gets displaced out of the DT under the normal occlusal load of 20 to 120 N and tends to flow back upon unloading (6). From a theoretical mechanical perspective, the structural stability of the bulk dentin is not solely dependent on its mineralisation extent but also on the DF, which imparts its flexibility (7). Experiments on an elephant tusk specimen have revealed the essential role of DF in imparting deformability properties to the dentin (8). The physiological functional role of DF and its constituents is depicted in (Table/Fig 2) (1),(2) and (Table/Fig 3) (3),(6),(7),(9).

Effectof Pathologies

Caries-induced pressure changes could potentially influence the movement of DF within the DT, affecting fluid flow and exchange between the tooth and surrounding tissues. The collapse of cavitation bubbles may create localised disruptions in the dentin’s microstructure, potentially affecting the DT and their fluid dynamics (10). Carious processes can generate localised heat, which might impact the temperature of the DF and surrounding structures. The process can also trigger cellular responses in the dental pulp and surrounding tissues, potentially affecting the DF composition (9). Similar inflammatory reactions can be provoked by exposure of DT due to periodontitis or trauma. Exposure of DT due to tissue destruction and release of cytokines and prostaglandins in periodontitis increase the bacterial invasion of DT and stimulate tubular fluid movements (11). The overall pathophysiology of all these factors leading to pain and sensitivity due to alterations in the DF dynamics is depicted in (Table/Fig 4) (9),(10),(11). The physiological and pathological alterations in the DF are summarised in (Table/Fig 5) (1),(3),(4),(6),(9),(11).

Effect of Therapeutic Materials and Procedures

Local Anaesthetics

Local anaesthetics, particularly those containing vasoconstrictors like epinephrine, can cause vasoconstriction in the area of administration. Studies suggest vasoconstriction can reduce blood flow to the tooth pulp, which may lead to a decrease in DF flow within the DT. Thus, local anaesthetics containing vasoconstrictors might have direct or indirect effects on odontoblasts, which could influence DF dynamics (9),(12).

At times, when Local Anaesthesia (LA) is administered, the tissues seem to have achieved anaesthesia; however, the exposed DT seems to take longer than usual to achieve complete anaesthesia and exhibit some sensitivity. This can be explained by the fact that DF continuously flows outward from the pulp through the tubules, which can potentially dilute and wash away the local anaesthetic, reducing its effectiveness. Thus, although certain local anaesthetics have higher degrees of hydrophilicity, their effectiveness might be reduced due to dilution. Additionally, the fluid and tubular structures create a barrier that can hinder the penetration of the anaesthetic to the deeper layers of dentin and the underlying pulp (13).

In some cases, local anaesthetics can cause transient irritation or inflammation in the dental pulp, although any potential impact on DF dynamics would be a secondary consideration compared to the primary goal of pain management during dental procedures. While this is more likely associated with certain components of the anaesthetic solution, particularly preservatives, it might have secondary effects on DF dynamics due to the inflammatory response (14).

Cavity Preparation

The mechanical action of the airotor during cavity preparation can cause fluid movement within the DT. This movement might lead to temporary changes in the flow of DF within the tooth structure. As the dentist removes decayed dentin, the DT may become exposed. This exposure could transiently increase the permeability of the dentin, potentially affecting fluid flow. The drilling process generates heat, which can transiently increase the temperature of the tooth. The average pulpal temperature increase was 5.03±0.98°C for the ultrasonic preparation (test group) and 3.55±0.95°C for the conventional technique (control group) (15).

Elevated temperatures may influence the fluid dynamics within the DT. After cavity preparation, the tooth may experience increased sensitivity to temperature changes, pressure, or air due to the temporary changes in the DF flow and tubule exposure. DF plays a critical role in maintaining the health and vitality of the dental pulp, and any alterations caused during cavity preparation are usually well-tolerated by the pulp. The effects of cavity preparation on DF are generally temporary and reversible (16).

Vital Pulp Therapies and Pulp Devitalisers

Vital pulp therapies may affect the rate and direction of DF flow within the tooth, which can influence the sensitivity of the tooth to various stimuli. The composition of DF, including the presence of various ions, growth factors, and other bioactive molecules, can be altered by vital pulp therapies (14). The released components from the therapeutic materials may interact with DF and influence its composition. Vital pulp therapies may impact DF flow and composition.

Pulp devitalisers are designed to cause necrosis of the dental pulp tissue. As the pulp tissue dies, it loses its cellular function, including the ability to regulate DF flow within the DT (17). Pulp devitalisers, by inducing pulp tissue necrosis, can disrupt the normal flow of DF, potentially altering tooth sensitivity in the treated tooth. The use of pulp devitalisers may cause an inflammatory response in the surrounding dental tissues as they interact with the dentin and other structures. Inflammation can influence DF flow and may affect the permeability of the dentin. Some pulp devitalisers contain substances like arsenic trioxide, which can cause tooth discolouration when used in significant amounts or when left in contact with the tooth for an extended period (18).

Tooth discolouration can also be considered as an indicator of potential DF flow disturbances. Tooth discolouration may indicate disturbances in DF flow, as the outward flow of this fluid plays a role in maintaining the tooth's natural color by preventing external staining agents from penetrating the dentin. Any disruption in this flow, often due to trauma, disease, or ageing, can lead to increased permeability and subsequent discolouration (18).

Mechanical Preparation of Root Canal Space

Rotary files are designed to shape and clean the root canal by removing dentin. As the files rotate within the canal, they shave-off layers of dentin, creating a space for the subsequent irrigation and obturation steps. This mechanical action may lead to the release of dentinal debris into the DT. The use of rotary files can enhance the penetration of irrigating solutions into the root canal system. The removal of dentin allows for better access of irrigants to the entire canal space. Proper irrigation is crucial for removing debris, disinfecting the canal, and facilitating the cleaning process.

The instrumentation with rotary files may alter the patency of DT (19). The removal of dentin can open up DT, potentially allowing for the exchange of fluids between the root canal system and the periapical tissues. This may have implications for the diffusion of medication and disinfecting agents into the dentin. The use of rotary files generates heat due to friction between the file and dentin. Excessive heat can lead to thermal damage, affecting the vital tissues within the tooth (20). However, modern rotary files often have features such as sharp and efficient cutting ends, flexibility, reduced speed and torque requirements to achieve mechanical canal preparation, use of lasers, thermal imaging assessments, and continuous irrigation to minimise heat generation.

Rotary instrumentation has been associated with the generation of microcracks in dentin. These microcracks may potentially extend into the root and compromise the structural integrity of the tooth. However, the clinical significance of these microcracks is a subject of ongoing research and debate (21).

Endodontic Irrigants

Dental irrigants, especially those with strong antimicrobial properties, may affect the normal flow of dentinal fluids within the DT. This disruption can result from the interaction between the irrigant and the dentin, altering the fluid dynamics. In certain cases, dental irrigants may trigger a mild inflammatory response in the surrounding tissues due to their chemical properties (22). This inflammation may also have secondary effects on dentinal fluid dynamics. The choice of the correct irrigant in the correct concentration is important, and its effect on the DT should be kept in mind when selecting an irrigant for any root canal procedure.

Intracanal Medicaments

Some intracanal medicaments have a dehydrating effect on DT. This can occur due to their hygroscopic properties, which draw moisture out of the DT. Changes in the fluid flow can impact the transport of nutrients, toxins, and immune cells between the pulp and the external environment. In some cases, this alteration may be beneficial for reducing inflammation and removing toxins, while in others, it may hinder normal dentinal fluid functions (23).

Dentinal fluid can act as a vehicle for the diffusion of intracanal medicaments deeper into the DT. This diffusion is essential for the medicaments to reach areas where bacteria and microorganisms may reside, contributing to their antimicrobial effectiveness (24). The use of certain intracanal medicaments can cause dentinal hypersensitivity (25). This sensitivity may arise due to the removal of the smear layer and exposure of the DT, leading to increased fluid movement and nerve stimulation. However, this sensitivity is usually temporary and resolves once the final restoration is placed. Temporary pain typically arises from reversible conditions like mild inflammation or transient stimuli, where dentinal fluid flow and tubular response are temporarily disrupted but can return to normal. Permanent pain, on the other hand, often indicates irreversible damage such as significant pulpitis or nerve involvement, leading to persistent alteration in dentinal fluid dynamics and continuous nociceptive signaling (25).

Root Canal Sealers

When root canal sealers are applied, they can displace dentinal fluids present within the DT. This displacement contributes to the adaptation of the sealer to the canal walls, allowing it to fill irregularities and voids effectively. Many root canal sealers are chemically activated and set in the presence of moisture. Dentinal fluids can participate in the hydration and setting reactions of these sealers, affecting their physical properties and setting times. The interaction of root canal sealers with dentinal fluids can influence their biocompatibility with the dental pulp and periapical tissues (26).

Root canal sealers like calcium hydroxide-based sealers (e.g., Sealapex) and resin-based sealers (e.g., AH Plus) demonstrate varied interactions with dentinal fluids affecting their biocompatibility. Calcium hydroxide-based sealers interact with dentinal fluids to release hydroxyl ions, promoting an alkaline environment conducive to healing and less inflammatory response, enhancing biocompatibility. Conversely, resin-based sealers may release formaldehyde or other irritating substances upon interaction with dentinal fluids, potentially leading to inflammation and cytotoxicity, thereby reducing their biocompatibility with dental pulp and periapical tissues (27).

Over time, root canal sealers can undergo dissolution in the presence of dentinal fluids and tissue fluids. This gradual dissolution can lead to a more extended release of certain chemical components, which may contribute to the antimicrobial properties of some sealers (26). Some root canal sealers contain antimicrobial agents, such as calcium hydroxide or antibiotics. The interaction of these antimicrobial agents with dentinal fluids can influence their release and distribution within the DT, aiding in disinfection and preventing reinfection. The interaction of root canal sealers with dentinal fluids can affect their adhesion to the dentin walls (28).

Bioceramic materials have gained significant attention as root canal sealers and repair materials, owing to their hydrophilic nature, antimicrobial properties, and low cytotoxicity (27). A study by Casino Alegre A et al., has revealed that certain bioceramic formulations can positively influence the flow of dentinal fluid within the DT, leading to enhanced nutrient exchange and waste removal (29). Bioceramics exhibit hydrophilicity, allowing them to attract and absorb dentinal fluid. This phenomenon occurs through capillary action and the formation of nanostructured water channels within the bioceramic material. These enhanced fluid dynamics can contribute to the overall health of the tooth and aid in the healing process (29).

Moreover, bioceramic materials have demonstrated the ability to modulate the inflammatory response within the dentin-pulp complex. Dentinal fluid serves as a vital medium for communication between the dental pulp and the external environment. Bioceramics can regulate the release of inflammatory mediators within the dentinal fluid, potentially reducing pulpal inflammation and promoting healing (26). The effect of bioceramic materials on dentinal fluid has significant clinical implications for various dental procedures. Improved fluid flow within the DT can facilitate the penetration and distribution of therapeutic agents used in root canal treatments, such as disinfectants and obturation materials. This can lead to more effective disinfection and sealing of the root canal system, reducing the risk of reinfection and improving treatment outcomes (27),(29).

Acid Etching Agents

The increase in tubule permeability due to etching causes an outward movement of dentinal fluid. This further leads to dehydration of the dentin, which can affect the overall properties of the tooth structure. In some cases, the fluid movement within the DT can elicit a mild response from the pulp and trigger sensitivity in the tooth during and after the etching process (30). This sensitivity is usually transient and resolves after the completion of the restoration.

Dentine Bonding Agents

Dentin bonding agents are di- or multifunctional organic molecules that contain reactive groups that interact with dentin and the restorative resin monomer. Bonding agents are dental materials used to improve the adhesion between restorative materials (such as composite resins) and tooth structure. When bonding agents are applied, they penetrate the DT and create a micromechanical bond with the tooth structure. The bond strength to enamel is higher than to dentin. Bonding to dentin has proven to be more difficult due to its composition (organic and inorganic), moisture, and lower mineral content (31). The wettability of the demineralised dentin collagen matrix is also problematic. Because dentinal tubules and their resident odontoblasts are an extension of the pulp, attachment to dentin also involves biocompatibility issues (32).

The application of bonding agents might lead to temporary dehydration of the dentin, which could result in a reduction of dentinal fluid flow. Dehydration can cause structural changes in dentin, as demonstrated by Van der Graaf ER and Ten Bosch JJ, who compared freeze-drying and drying of dentin in nitrogen at 60 and 100°C, resulting in weight reduction of 9.0% to 10.5% and shrinkage of 1.4-2.0% in different planes (33). Carvalho RM et al. also showed that demineralised coronal dentin underwent significant volumetric shrinkage (15-20%) when dehydrated using acetone followed by hexamethyldisilazane or critical-point drying, indicating that shrinkage depends on the tissue’s microstructure. Structural changes due to ageing, such as the formation of sclerotic dentin and increased mineral content, may also influence dehydration and shrinkage characteristics (34). The presence of bonding agents in the dentinal tubules influences the transport of ions and molecules within the tooth structure, potentially affecting the long-term success of the dental restoration. The 2nd and 3rd generation dentin bonding agents rely on this concept, but a disadvantage is the inclusion of a smear layer in the bond, which reduces bond strength as the agent penetrates the dentinal tubules only to a limited extent (35).

The presence of bonding agents in the dentinal tubules also influences the transport of ions and molecules within the tooth structure (34). Any potential adverse reaction of the bonding agent with dentinal fluid or the tooth structure could have implications for the long-term success of the dental restoration. The 2nd and 3rd generation Dentin Bonding Agents (DBA) depend on this concept, but the disadvantage is the inclusion of a smear layer in the bond, which results in a loss of bond strength, as the DBA penetrates the dentinal tubules only to a limited extent (36).

The overall concept of etching is based on the removal of the smear layer plus the optimal penetration of the adhesive to achieve the thickness of the hybrid layer. The 4th and 5th generation binders fall into this category. When an acid etchant is applied to enamel and dentin, surface decalcification occurs with the loss of minerals and removal of the sebaceous plug. The application of the adhesive resin replaces the lost minerals in the tooth structure and the sebaceous plug, causing the DBA to penetrate into the dentinal tubules, which after curing in-situ, are micromechanically retained in the pores created during the acid etching process. The self-etching method leads to the dissolution and inclusion of the smear layer in the hybridisation. The 6th and 7th generation binders belong to this category (36),(37).

Therefore, it can be safely concluded that the bond strength of DBA depends on its penetration into the dentinal tubules and its interaction with the dentinal fluid. Removing or manipulating the lubricant layer helps the DBA penetrate deeper but can also cause harmful substances to penetrate the pulp. Therefore, a good balance between the penetration of DBA and its interaction with the dentinal fluid should be maintained to achieve a good adhesive bond. It is important to note that the effect of bonding agents on dentinal fluid is a complex and multifactorial area of study. Researchers continue to investigate the interactions between dental materials and tooth structure to improve the performance and durability of dental prostheses (35),(37).

Varnishes, Liners and Bases

The presence of liners and bases can affect the permeability of dentin and alter the movement of dentinal fluid. Research suggests that certain liners and bases may reduce fluid flow by partially or completely occluding DT, limiting the exchange of nutrients and waste products (38). This alteration in fluid flow can have implications for the vitality and health of the tooth.

The potential release of ions from varnishes, liners, and bases can also raise concerns about their toxicity. For example, some liners and bases containing calcium hydroxide or glass ionomer cement may release ions such as calcium, hydroxide, or fluoride into the dentinal fluid (39). Varnishes, such as those containing fluoride, can form a protective layer over dentin, reducing dentinal fluid flow and permeability, which helps in preventing hypersensitivity and protecting against acid erosion. However, this occlusion can also limit nutrient and waste exchange, potentially impacting the overall health of the dentin and pulp over time (38). Overall, the released ions can interact with the dentin structure and influence its properties. While the released ions are generally within safe limits, their long-term effects on dentinal fluid and tooth health require further investigation.

Dentinal fluid is involved in the exchange of minerals between the dentin and the oral cavity, playing a crucial role in remineralisation and repair processes. Liners and bases can influence this mineral exchange. For instance, calcium hydroxide-based liners have been shown to promote the release of calcium and phosphate ions, which can enhance dentin remineralisation. Glass ionomer cement liners and bases can release fluoride ions, which aid in remineralisation and offer additional protection against tooth decay (40).

Glass Ionomer Cements

The application of Glass Ionomer Cement (GIC) onto dentin creates a seal that reduces the flow of DF. This sealing effect is due to the physical properties of GIC, including its ability to expand and contract during setting (41). The reduced flow of dentinal fluid may impact the transportation of nutrients and defense cells within the DT, potentially affecting pulpal health.

The GIC can interact chemically with dentinal fluid, leading to changes in its composition. GIC releases fluoride ions, which can diffuse into the dentinal tubules and form fluorapatite crystals. These crystals can obstruct dentinal tubules, further reducing dentinal fluid flow. Additionally, the release of fluoride ions by GIC can contribute to the remineralisation of adjacent dentin, promoting its overall health (42).

The interaction between GIC and dentinal fluid can modify the composition of the fluid. GIC releases various ions, including calcium, aluminum, and strontium ions, into the dentinal tubules (40). These ions can potentially alter the mineral content and pH of dentinal fluid, influencing pulpal health. Moreover, the release of these ions can contribute to the remineralisation of adjacent dentin, promoting its strength and resistance to decay.

By reducing fluid flow and altering its composition, GIC can help maintain the integrity and health of the dental pulp. The effects of GIC on dentinal fluid have significant clinical implications in various dental procedures. GIC-based materials can be used in dentinal fluid management strategies, such as the treatment of dentinal hypersensitivity, or as a lining material beneath other restorative materials. The ability of GIC to modify dentinal fluid flow and composition should be considered when selecting restorative materials and planning treatment approaches (41),(42).

Silver Amalgam

Amalgam restorations can alter the permeability of dentin, affecting fluid movement. Studies have demonstrated that the presence of dental amalgam can reduce fluid flow by occluding dentinal tubules, limiting the exchange of nutrients and waste products (43),(44),(45).

One of the main concerns associated with dental amalgam is the potential release of mercury and other metals. Despite advancements in dental amalgam formulations, there is a risk of mercury vapour release during the placement, removal, and long-term presence of amalgam restorations (46). Although the amount of mercury released is generally within acceptable limits, its potential toxic effects on DF and surrounding tissues have been a subject of debate.

The occlusion of dentinal tubules caused by dental amalgam can reduce fluid flow, resulting in decreased sensitivity or desensitisation of the tooth. This can be beneficial for patients experiencing tooth sensitivity, but it may mask underlying dental problems, making early detection and diagnosis more challenging. Studies have shown that the presence of dental amalgam can affect this mineral exchange, potentially disrupting the natural balance and leading to changes in the composition of DF (46). These alterations can have long-term implications for tooth health and integrity.

While dental amalgam has been widely used in dentistry for its favourable properties, including durability and cost-effectiveness, its potential effects on DF cannot be overlooked. The presence of dental amalgam restorations may influence DF flow, dentin sensitivity, mineral exchange, and bacterial defense mechanisms (45).

Surgical Endodontics

Surgical endodontics involves cutting through the tooth’s structure to access the root apex. This can disrupt the natural flow of DF within the dentinal tubules, altering the normal fluid exchange between the pulp chamber and the surrounding dentin. Surgical manipulation of the root apex can potentially affect these pressure differentials, leading to changes in fluid movement within the dentinal tubules (47). This could impact the transport of nutrients and waste products within the tooth. Due to access issues, the root is frequently resected at an oblique angle to allow visibility and insertion of the retrograde closure. This angled cut across the root opens up the prospect of another leaking pathway between the canal and the apical tissues, especially through the exposed dentinal tubules (48).

The procedures are often performed to address issues such as persistent infections, failed root canal treatments, or cysts at the root tip. These conditions can be associated with inflammation in the periapical region. The surgical procedure itself, along with the removal of infected tissue and cleaning of the area, can trigger an inflammatory response. This inflammation can affect DF dynamics as the tooth undergoes the healing process. Surgical endodontic procedures can also potentially alter the permeability of dentin due to the disruption of dentinal tubules during the procedure (47). Changes in dentin permeability could impact the movement of fluids, ions, and other substances through the tooth structure.

The effects of surgical endodontics on DF dynamics are likely to be most pronounced immediately following the procedure and during the initial stages of healing. As the tooth heals and adapts to the changes introduced by the surgery, the DF flow and associated dynamics may gradually return to a more stabilised state. The extent of these changes can depend on factors such as the nature of the surgical procedure, the individual patient’s response to healing, and the success of the surgery in resolving underlying issues (47),(48).

Utility Of Dentinal Fluid (DF) In Diagnostic Procedures

The DF can be used in the detection of early-stage caries. When a tooth starts to decay, the pH in the affected area decreases due to the acid produced by bacteria. This drop in pH can lead to changes in DF flow, which can be measured and assessed to detect the presence of early caries, potentially before they become visible on X-rays or clinical examination (49). The DF exhibits defense cells including neutrophils, lymphocytes, and plasma cells during inflammatory conditions of the pulp or periodontal tissues. Therefore, an estimation of the extent of the damage caused by pulpal or periapical pathologies can be made by characterisation of DF (50). This would also aid in gauging the extent of healing and efficacy of dental restorations.

In endodontics, DF flow has been explored as a potential aid in assessing pulp vitality. Vital teeth have active DF flow, while non vital or necrotic teeth have limited or no DF flow. By analysing the fluid flow, dentists can determine the vitality status of a tooth and make appropriate treatment decisions. There is an increased expression of cytokines such as interleukin-8, matrix metalloproteinase-9, and tumour necrosis factor-alpha in the DF during pulpal inflammation (49).

The assessment of DF flow can provide information about the status of the dental pulp associated with various pulp vitality tests. Cold thermal testing causes contraction of the DF within the DT, resulting in a rapid outward flow of fluid within the patent DT. This rapid movement of DF results in hydrodynamic forces acting on the Aδ nerve fibres within the pulp-dentin complex, leading to a sharp sensation lasting for the duration of the thermal test (51). The rapid movement of DF results in hydrodynamic forces acting on the Aδ nerve fibers within the pulp-dentin complex, leading to a sharp sensation lasting for the duration of the thermal test. DF movement plays a significant role in transmitting the cold stimulus to the pulp, triggering the sensory response. A vital tooth with active DF flow will typically exhibit a sharp and brief pain response to the cold stimulus, while a non vital tooth will have little to no sensation (52).

Hot stimulation can hardly initiate a high rate of fluid flow needed for the activation of mechano-sensitive nociceptors (51). Sweet intake can stimulate dentinal fluid flow due to the osmotic gradient created by high sugar concentration, leading to an outward fluid movement that activates mechano-sensitive nociceptors and potentially causes a sensation of pain or discomfort. This reaction is similar to the response seen with air blasts and other osmotic stimuli, indicating the presence of vital pulp and active dentinal fluid dynamics. Air blasts and osmotic stimuli show outward flow of dentinal fluid (53).

It is important to note that while dentinal fluid flow is relevant to these pulp vitality tests, the accuracy of these tests may vary depending on several factors, including the tooth’s condition, the extent of pulpal inflammation, and the presence of other confounding factors (e.g., medications, previous dental treatments) (54).

Conclusion

In conclusion, endodontic and conservative dental procedures exert a substantial influence on DF, a vital component in maintaining tooth health. These procedures encompass root canal treatments, cavity preparations, and tooth restorations, all of which have the potential to alter DF flow, dentin sensitivity, mineral exchange, and bacterial defense mechanisms. Understanding these effects is paramount for clinicians aiming to provide comprehensive and effective dental care, ultimately ensuring the long-term well-being of the patient’s dentition. Nevertheless, further research is warranted to delve deeper into the specific mechanisms and implications of these influences on overall oral health. By considering the profound impact of these procedures on DF, clinicians can make informed decisions to optimise treatment outcomes and enhance patient oral health and comfort.

DOI and Others

DOI: 10.7860/JCDR/2024/71023.19808

Date of Submission: Apr 02, 2024
Date of Peer Review: May 29, 2024
Date of Acceptance: Jun 29, 2024
Date of Publishing: Aug 01, 2024

AUTHOR DECLARATION:
• Financial or Other Competing Interests: None
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