Post-Operative Sensitivity in Adhesive Dentistry

The introduction of adhesive techniques has significantly changed the field of dentistry. Adhesive dentistry offers modern, less invasive options compared to its counterpart restorative techniques, such as root canals or tooth extraction. The materials used in adhesive dentistry are regarded for their ability to bind restorative materials directly to the tooth structure.

Yet, as with every advancement in the medical field, adhesive dentistry brings its own challenges. One of the most significant is the prevalence of post-operative sensitivity. Post Operative Sensitivity (POS) can present a significant complication with a risk of occurrence as high as 20% to 40%. As far as its prevalence is concerned amongst populations, hypersensitivity affects a significant portion of the population, ranging from 10-30% of the population. In a city of one million, this translates to 100,000 to 300,000 people impacted. It’s a widespread issue, affecting vast segments of communities. This troubling complication can affect both the clinical success of dental procedures and the patient’s dental experience. 

In light of these implications, our understanding of post-operative sensitivity, its aetiology, and potential preventive measures requires a thorough evidence-based exploration. This blog is set to delve into the complexities of this issue. It will draw on the most recent research to present a panoramic review of avoiding postoperative sensitivity in adhesive dentistry.

The Mechanism Behind Post-Operative Sensitivity

There are various triggers that can lead to post-operative sensitivity (POS) following adhesive restorative procedures, such as fluctuations in temperature (especially colder temperatures), chewing, and intake of sugary foods after adhesive dentistry procedures. 

These sensations are typically more common in Class II MOD restorations (26%), followed by Class II (15%) and Class I (5%). POS can persist in cases of deeper caries lesions or repeated treatments. Unaddressed, this discomfort can necessitate further treatments such as root canal procedures.

A myriad of factors contribute to POS. The hydrodynamic theory posits that pain or sensitivity in the dentin can be triggered by the movement of dentinal fluid induced by dentin dehydration, temperature fluctuations, and the penetration of chemical or bacterial agents. 

The pain due to dentine hypersensitivity arises when dentinal tubules are exposed due to surface lesions. Pain related to POS becomes worse when the pulp gets involved. As thermal, chemical, and mechanical stimuli prompt the movement of dentinal fluid, they also stimulate the pulpal Aδ fibres. This leads to sensitivity symptoms. This sharp, brief pain is linked to the hydrodynamic pain theory, impacting the person’s quality of life. With longer life spans and increased tooth/filling wear, this condition may become more common in the future. 

Basic Aetiology of Post-Operative Sensitivity

Post-Operative sensitivity is a frequent clinical concern following adhesive restorative procedures. Its aetiology is multifactorial, stemming from both procedural techniques and the materials utilised. A comprehensive understanding of the basic underlying causes is pivotal for clinicians to both anticipate and mitigate this challenge.

Substrate Preparation: Tooth preparation methods can cause thermal or mechanical trauma, leading to dentin hypersensitivity. The use of bleaching agents may also contribute to post-operative sensitivity.

Incomplete Resin Infiltration: The failure to completely infiltrate the collagen network within the dentin matrix during adhesive application results in porous, water-filled spaces that can cause sensitivity.

Polymerisation Shrinkage: Shrinkage of the composite resin during polymerisation causes stress at the tooth-restoration interface, leading to microleakage and resultant post-operative sensitivity.
Contamination: Contamination of the bonding site by saliva or blood can compromise the bonding process, leading to microleakage and sensitivity.

Pre-Operative Causes of Post-Operative Sensitivity

Before undertaking any restorative dental procedures, it is crucial to make an accurate diagnosis. This ensures that the patient’s reported discomfort is not due to pre-existing conditions. Detailed patient history taking, along with thorough clinical and radiographic assessments, is essential to rule out other pathological conditions affecting the pulp or periapex of the tooth.

Cracked Tooth Syndrome

The Cracked Tooth Syndrome may easily be confused with Post-operative sensitivity. It occurs due to the presence of incomplete cracks or fractures in the tooth enamel or both enamel and dentin. This can cause pain during mastication and also lead to unexplained cold sensitivity. 

Owing to the difficulty in spotting the extent of the crack and understanding the patient’s symptoms, this diagnosis can be complex. It is often confused with post-operative sensitivity.

Cervical Dentinal Exposure 

The reasons behind the exposure of cervical dentin are varied and multifaceted, and it’s common for various triggers to provoke associated pain. Cervical exposure of the dentine may have been present before the operative procedure and could have remained dormant in terms of sensitivity. However, it is possible that it could be stimulated during the operative procedure. 

Therefore, it’s imperative to thoroughly examine for exposed dentin, regardless of reported painful symptoms, to avoid procedures that could induce or worsen existing discomfort.

Health Status of the Pulp

It is pivotal to thoroughly examine and investigate the condition of the pulp before initiating tooth restoration. Investigations should include radiographic examinations, a review of prior procedures, documenting a detailed history, and conducting pulp vitality tests. These investigations are vital to reduce sensitivity risks. Otherwise, conditions such as secondary caries and irreversible or reversible pulpitis may possibly be confused for post-operative sensitivity and threaten the success of the treatment.

Technique-Sensitive Causes of Post-Operative Sensitivity

Technique-sensitive causes are a primary contributor to post-operative sensitivity in adhesive dentistry; therefore, extensive knowledge of the discipline compounded with a set of refined skills can prove to be a game-changer.

Caries Excavation Depth

The size and severity of the carious lesion dictate the depth of excavation required in the involved tooth. The deeper the excavation, the higher the chances for exposure to a greater number of dentinal tubules. Furthermore, the generation of heat during the tooth preparation procedures can further put the tooth at risk of POS. 

Using fluorescent lasers can identify endpoints that determine ideal caries removal sites whilst creating an outer seal zone capable of sustaining biomimetic restorations over a prolonged period. Employing the method of selective caries removal may also reduce the occurrence of POS in adhesive dentistry.

Generic measures to prevent POS include strategies like intermittent cutting, adequate water irrigation, and using sharp cutting burs. This contributes to cooling the tool and tooth. It minimises heat-induced damage and reduces POS occurrence.

Etching Time

The duration of the etching process has a significant impact on the physical characteristics of dental hard tissues, notably enamel and dentine. The properties of these surfaces, including their roughness and hardness, can change within mere seconds. If the etching time exceeds the suggested duration, it could potentially heighten the surface’s coarseness and diminish its hardness through demineralisation. Such changes could expose more dentinal tubules, thereby propagating the onset of postoperative sensitivity and decreasing the longevity of the adhesive restoration.

Filling Method

A systematic review and meta-analysis, which demonstrated a moderate level of evidence quality, found that both bulk fill and incremental techniques exhibited comparable clinical effectiveness when used for posterior resin composite restorations. This suggests that either technique can be reliably used in dental procedures, depending on the specific context and requirements.

However, they each have their downsides that may lead to the development of POS. The traditional incremental filling method aims to ensure sufficient polymerisation and reduce shrinkage, but it poses the risk of voids, contamination, and time consumption. The POS outcomes for each filling method rely on the skill of the dentist and the advancement of technological tools.

Curing 

Incomplete curing can result in partial or inadequate polymerisation of the bonding resin. When the resin is not fully polymerised, it may exhibit a heightened degree of solubility and absorption due to the incomplete conversion of the monomer. 

This significant increase in both of these parameters may potentially undermine the performance of the material and ultimately open the doorway to post-operative sensitivity. Hence, it is crucial to ensure adequate curing with devices providing enough light intensity.

Influence of Finishing and Polishing 

It is advisable to avoid the excessive finishing and polishing of the restoration. This can lead to microleakage at dentinal margins whilst disrupting the harmony of the resin matrix, therefore, increasing the possibility of POS. Thus, finishing should be restricted to minor corrections and superficial smoothing.

Dentine Desensitizers

Dentin desensitisers have been contemplated for their potential to reduce POS. They have been shown to successfully occlude the dentinal tubules. However, the clinical effect of these desensitisers is quite subtle and can not be relied upon heavily.  

Conclusion

Postoperative sensitivity remains a pertinent challenge in adhesive dentistry. It directly affects both patient comfort and the efficacy of dental procedures. It is a complex issue that requires a multifaceted approach for effective management. The key to a successful treatment starts with an accurate diagnosis. This initial assessment lays the groundwork for effective dental care.

Optimal etching times and the judicious selection of adhesive systems that ensure adequate polymerisation play a pivotal role in mitigating post-operative sensitivity in adhesive dentistry. The strategic use of desensitising agents has also emerged as a significant element in alleviating this sensitivity. However, their clinical effect remains questionable. 

As we move forward, it’s imperative that we continue to evolve our practices based on ongoing research and development in the field. The ultimate goal isn’t just about minimising postoperative sensitivity but ensuring enhanced patient experiences and advancing the success of adhesive dentistry as a whole.

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