Hydrophobic vs. Hydrophilic: Comparing Dental Sealants Performance

Dental sealants are an excellent preventative tool for your high-caries-risk patients. Since their introduction in the 1970s, sealants have protected the tooth's occlusal surfaces, particularly in the pits and fissures of molars.

Applying dental sealants correctly requires isolating and drying the tooth before curing. Failure to do so could result in early loss of the protection on the occlusal surface.¹ However, as materials science progresses, dental product formulation and features change. For example, early sealants were hydrophobic, but today hydrophilic sealants are also available. 

The introduction of hydrophilic sealants presents benefits to dental clinicians. The most obvious is that these water-tolerating products are more forgiving in applications where moisture is present. Since the deep pits and fissures in newly emerged permanent molars are difficult to isolate and dry thoroughly—particularly in less compliant patient populations where dental sealants are usually applied (aka, kids)—hydrophilic sealants are more likely to facilitate a stronger bond and improved retention.²

But do they work? Three studies seek to answer that question, and the results might surprise you.

First Study: Hydrophilic and Hydrophobic Sealants Have the Same One-Year Clinical Success Rate

The first study reviewed is the 2017 study out of Iran. Researchers from Tehran's University of Medical Sciences found no difference between the clinical performance of two dental sealants, one hydrophilic and one hydrophobic.²

With 23 6- to 9-year-old participants, the split-mouth clinical trial used Helioseal-F (Western Digital), the hydrophobic sealant, and Embrace™ Wetbond™ (Pulpdent), the hydrophilic sealant on the first molars for the comparison. The researchers compared participants' retention, marginal adaptation, color match, surface smoothness, and recurrent decay at 3, 6, and 12 months after placement. They found no significant difference in any of the categories.²

There were some performance differences at 12 months in some of the categories, however, which include:²

• 32.5% of Embrace and 27.5% of Helioseal-F sealants lost surface smoothness on the teeth
• 82.5% of Embrace and 77.5% of Helioseal-F had an optimal color match
• 60% of teeth and 52.5% of Helioseal-F had acceptable marginal adaptation
• Three teeth with Embrace had cavities
• One tooth in Helioseal-F had a cavity

The researchers indicated that their findings supported previous studies. They also suggest that hydrophilic sealants have less technical sensitivity than hydrophobic ones. By not requiring a bonding agent, they also take less chair time, which also helps with patient compliance.²

However, they also suggest more studies. For example, the researchers think evaluations of longer-term performance are necessary. Also, they believe an examination of some of the Embrace features, like fluoride release, water sorption, microleakage, and compressive strength, should be undertaken in the future.²

Second Study: The Hydrophobic Sealant Performed Better, But Hydrophilic Ones Have Potential

The Journal of Contemporary Dental Practice published a study 2 years later than the Tehran University study in 2019 with different conclusions. In this study, the hydrophobic dental sealant (Clinpro, 3M ESPE) outperformed the Hydrophilic sealants (Embrace Wetbond and Champ, Centrix) in retention and cavity prevention.³

The study included 150 participants aged seven to 13 randomly divided into 3 groups, each receiving a different brand of sealant. Researchers evaluated the teeth at 1, 3, 6, 9, and 12 months regarding retention and evidence of decay. The evaluator did not know which sealant each patient had during the patient's assessment.³

Here's what they found:³

• The retention was the same at 3 and 6 months, with around 80% of no loss for all at 3 and nearly 70% at 6 months.
• At 9 months, 20% of the Clinpro group still had no loss, but only 2% in the Champ group and none of the Embrace Wetbond group had no loss.
• At 9 months, 58.7% of the sealants were gone entirely in the Embrace Wetbond group.
• There were no caries present until the 9- and 12-month evaluations.
• The Clinpro group had 5% and 9% at 9 and 12 months, respectively.
• The Champ group had 14% and 17% at 9 and 12 months, respectively.
• The Embrace Wetbond group had nearly 17% and 28% of teeth with caries at 9 and 12 months, respectively.

Despite these findings, the researchers were optimistic about the future of hydrophilic sealants. The researchers thought the presence of fillers interfered with the hydrophilic sealants. They suggested removing fillers from the hydrophilic sealant and testing those results. Moreover, the researchers suggest that recall visits are essential to the preventative strategy for clinical success. Regularly assessing caries risk at a set interval allows dental teams to reapply if needed before caries form.³

Third Study: Hydrophilic and Hydrophobic Sealants Have the Same Two-Year Clinical Success Rate

Children published a study in April 2022 that compared the performance of Embrace Wetbond and Helioseal-F at 2 years. Like the University of Tehran study, the researchers did not find a significant difference between retention and caries prevention at two years.⁴

The study had 28 participants aged 6 to 8. The participants were divided into 2 groups, receiving the Embrace Wetbond or Helioseal-F on 4 permanent molars. Researchers evaluated the sealants' performances at 6, 12, 18, and 24 months. The researchers discovered:⁴

• At 1 year, the hydrophilic sealed teeth had perfect integrity in 89% of the molars; the hydrophobic material had excellent integrity at 91%.
• At 2 years, Embrace teeth had 78.5% retention, and Helioseal had 80%.
• The first signs of decay at 12 months occurred on 2 molars in the Embrace group and 1 in the Helioseal group.
• Decay at 24 months came in at 7% for the Embrace group (4 cavities) and 3.5% for Helioseal (2 cavities).

So, even though Helioseal did have more retention and fewer cavities, it was not a ton more. The conclusions were that the Embrace Wetbond dental sealant effectively protects the teeth (retention) and prevents cavities. However, the researchers also recognize that these results between studies are inconsistent enough that the area requires further analysis. They also recommend further study on water-tolerant dental sealants.⁴

What Can Clinicians Do to Enhance Dental Sealant Performance?

So, in addition to choosing the material that works best in your hands, hydrophobic or hydrophilic, there are a few things that can make a difference in how sealants perform.

Perfecting their placement technique: Of course, the better the placement technique, the better the performance regarding retention and evidence of caries.³

Optimize curing steps: Achieving optimal polymerization does a lot for the performance of your sealants, so ensuring that you have a working curing light emitting the proper intensity for a sufficient time is essential.²

Sealing teeth as soon as possible: Per the literature, this opportunity is as soon as the tooth erupts and no longer has gingival material on the occlusal surface.⁴

Patient education: Sealants are not magic; patient behavior has much to do with success. Therefore, continual education and building patient (and parental) awareness about how diet, dental health consciousness, and consistent oral home care contribute to preventing decay.³

Materials science continues to look for ways to deliver an excellent clinical outcome without the need for precise techniques and perfect conditions. Hydrophilic dental sealants are an example of a development that can significantly affect a patient's oral health and prevent decay while optimizing the placement process for today's busy clinician. In some research, they are performing almost as well. Others, not so much.

So, will hydrophilic dental sealants work as well as conventional sealants? Time will tell, and so will future studies.

References

1. Brown, J, Dodds, M. Prevention strategies for dental caries. Prevention in Clinical Oral Health Care. 2008.196-212.
   doi.org/10.1016/B978-0-323-03695-5.50019-7
2. Askarizadeh N, Heshmat H, Zangeneh N. One-year clinical success of embrace hydrophilic and Helioseal-F hydrophobic sealants in permanent first molars: a clinical trial. J Dent (Tehran). 2017;14(2):92-99.
3. Mohanraj M, Prabhu R, et al. Comparative evaluation of hydrophobic and hydrophilic resin-based sealants: a clinical study. J Contemp Dent Pract 2019;20(7):812–817.
4. Beresescu L, Pacurar M, Vlasa A, Stoica AM, Dako T, Petcu B, Eșian D. Comparative assessment of retention and caries protective effectiveness of a hydrophilic and a conventional sealant—a clinical trial. Children. 2022;9(5):646. https://doi.org/10.3390/children9050646