Class II Solution
Blog Post

What is microleakage in dentistry?

Microleakage in dentistry refers to the tiny gaps or spaces that can develop between a dental restoration, such as a filling or crown, and the natural tooth structure. These minuscule openings allow for the seepage of saliva, bacteria, and food particles into the interface, potentially leading to secondary decay, sensitivity, and compromised restoration longevity. Effective sealing of these gaps is crucial to prevent the onset of dental issues and maintain the overall oral health of the patient. 

What can cause microleakage?

Microleakage can arise from various factors, including improper bonding between the dental material and the tooth surface, inadequate preparation or cleaning of the tooth before restoration placement, inconsistencies in the application of adhesive agents, polymerisation shrinkage of the restorative material, and the natural wear and tear that occurs over time. Skilful technique, high-quality materials, and meticulous attention to detail are essential to minimise the risk of microleakage and ensure the long-term success of dental restorations.

What are the signs of microleakage in a dental restoration?

Microleakage in a dental restoration can manifest through several telltale signs. One common indicator is tooth sensitivity to hot, cold, or sweet stimuli. Discoloration at the margins of the restoration, often appearing as a dark line, can be a visible clue of microleakage. If a patient experiences pain, discomfort, or if the restoration becomes loose, these could also point to potential microleakage issues. Regular dental check-ups are crucial for detecting these signs early and addressing any underlying problems to ensure the integrity of the dental restoration and maintain oral health. 

How do you minimise the likelihood of microleakage in a dental restoration?

Minimising the likelihood of microleakage in a dental restoration is crucial for its long-term success. As mentioned previously, microleakage can arise from various factors, including improper bonding, inadequate preparation or cleaning of the tooth before restoration placement, inconsistencies in the application of adhesive agents and polymerisation shrinkage stress of the restorative material. Skilful technique, high-quality materials, and meticulous attention to detail are essential to effectively address these potential sources of microleakage risk, ultimately enhancing the durability and longevity of dental restorations.

How to detect and prevent microleakage in dental restorations

Bacteria has a way of creeping in everywhere, and your composite restorations are no exception. This invading bacteria isn’t just problematic for the health and happiness of your patient, it’s problematic for your dental practice. With 50% of new business coming from referrals, and an average patient being worth $1,000 to a practice annually1,one premature restoration replacement can have a ripple effect on your bottom line.

Understanding the root causes of microleakage in composite restorations, how to detect it, and and how to mitigate the risk of it occurring in the first place are the keys to a long-term successful restoration. Don’t worry, though—eliminating pain points and bringing predictability and efficiency to your dental practice is what we’re here for. Below, we’ll outline how to detect microleakage in restorative dentistry and how to prevent it from happening in the first place, allowing you to create more positive experiences for your patients and grow your practice.

The causes of microleakage in a composite restoration

Microleakage is technically defined as the passage of bacteria, fluids, molecules or ions between a cavity wall and the restorative material applied to it.2


The most common causes of microleakage in composite restorations include:

  • Using high-stress restorative materials
  • Not achieving adequate isolation throughout the entire procedure
  • Not obtaining a tight seal at the floor of the proximal box/gingival margin
  • Not using proper technique when placing the restoration

How to detect microleakage

The consequences of microleakage in restorative dentistry are significant - if there is bacterial colonisation of the leaking interface, caries may not only evolve again but also affect pulp vitality - leading to endodontic treatment or even tooth loss. As a result, every step during placement of the restoration presents a risk of increasing microleakage in the future and may influence the long-term success of the restoration.

Clinically, there are various signs that could indicate microleakage of different severity, which makes treatment decisions difficult. A few common signs microleakage is present3 are:

  • Dark line or stain around margin of restoration that can’t be polished away
  • Dark or opaque appearance of enamel adjacent to a margin
  • Reports by patients of pain upon sugar exposure of the restoration
  • Pain of stimuli like cold or air blast

Technique tips to minimise the likelihood of microleakage in dental procedures

There are various ways practitioners can prevent microleakage. You first need to understand the different causes of microleakage. Once you understand what causes it, you can take steps to prevent it. Microleakage occurs when there are gaps at the margin of the restoration allowing fluid and bacteria to contaminate the tooth4. Choosing materials and techniques proven to create gap free restorations can set you on the path for success.

Microleakage caused by inadequate isolation


Adequate isolation is key to preventing microleakage and using the ideal matrix system can play a large role. Every dentist understands the need for adequate isolation when using resin based restorative materials. If the matrix system you are using does not tightly seal the margins, the opportunity for blood and saliva to enter into the restorative field exists. This can be prevented by using a matrix system that leverages an intuitive wedge design to create a tight seal, like our Palodent Matrix family.


Microleakage caused by high-stress composite materials


Selecting the appropriate materials for your restorations is key to preventing microleakage. During the light curing process, composite resins begin to polymerise. During polymerisation, stresses are generated within the material that are transferred to the tooth resulting in forces being placed on the bonded tooth. These forces pull the walls inward and can lead to breaks in the bonded material creating a pathway for microleakage.

To prevent this, choose a restorative filling material with extremely low polymerisation stress as well as excellent flowability so it can self-level without manipulation, providing excellent adaptation and enabling gap-free restorations. Dentsply Sirona’s SDR® flow+ Bulk Fill Flowable not only enables gap-free restorations but it also:

  • Reduces placement time by up to 40% with its bulk fill technique5
  • Has versatile shade options for use in multiple indications5
  • Has significantly lower shrinkage stress5

Microleakage caused by improper technique


Making the decision to use high-quality materials is one step, but using them incorrectly can lead to undesired consequences. For example, using the ideal curing light but holding it too far away from the restoration or at the wrong angle can lead to inadequate or uneven curing which in turn can lead to an increased risk of microleakage. The low-profile light curing unit SmartLite® Pro combines ease of correct positioning with a homogenous beam profile of elevated irradiance even over larger distances.

Before using, you should familiarise yourself with the proper technique for the products you have selected. To help, Dentsply Sirona has an entire online dental academy full of webinars, how-to videos, and real-world examples.

Trust Dentsply Sirona’s Class II approach

Not all restoration materials and products are created equal, and that’s where we come in. Our goal is to empower you to provide the best possible care to your patients, which is why we’ve created our procedure solution for Class II Restorations. We’ll help you bring increased predictability to your procedures and more efficiency to your practice, providing you with the tools and training you need to implement solutions for a better practice all round. To get started, contact us now!

Related Topics

  1. DENTSPLY Caulk survey June 5, 2012 n=297. For more information, contact
  2. Muliyar S, Shameem KA, Thankachan RP, Francis PG, Jayapalan CS, Hafiz KA. Microleakage in endodontics. J Int Oral Health. 2014 Nov-Dec;6(6):99-104. PMID: 25628496; PMCID: PMC4295468.
  3. Muliyar, Sabir aet al. “Microleakage in endodontics.” Journal of international oral health: JIOH vol. 6,6 (2014): 99-104.
  4. Mariani aet al 2018 J. Phys.: Conf. Ser. 1073 042005
  5. Internal data on file. For more information, contact