Wettability and Dental Materials

Often, when biomaterials are being developed and selected for a particular application, the bulk properties of the material are considered first, and surface characteristics are an afterthought. In a complex biological environment like the human body, surfaces and interfaces play a critical role in enabling and mediating essential processes such as adhesion, adsorption, coagulation, and tissue integration. Surfaces must be able to withstand dynamic biochemical and mechanical conditions with minimal impact to these interfacial functions.

A particularly challenging field in the biomedical arena is dental materials. The oral environment requires biocompatibility, mechanical durability of both the bulk and surface of the material, and resistance to bacteria, corrosion, and discoloration. Materials used for implants, adhesives, sealants, and even dental tools such as drills must be carefully assessed for suitability. A survey of papers on these topics published in 2026 shows there currently is significant interest in the field^{1,2,3,4,5,6,7}.

Wettability is a key property that is predictive of many performance characteristics in dental materials. Wetting behavior describes how a liquid spreads on a solid surface. This spreading is best summarized by a contact angle, the angle formed between the liquid and the solid/liquid interface. Low contact angles (below 90°), formed by hydrophilic surfaces, indicate the surface encourages liquid spreading. Higher contact angles (above 90°) indicate a hydrophobic surface. Contact angles are fast and easy to measure and can be studied with readily available liquids such as pure water. Precision instrumentation allows for repeatable measurements that are sensitive to changes in surface conditions. This makes contact angle a practical tool for determining the suitability of a material for use in dentistry, both in the development of new materials and in quality control.

Figure 1: Hydrophobic and hydrophilic contact angles. [Source: ramé-hart instrument co.] Click to enlarge

The papers previously referenced show that wettability can be used to assess material performance for a variety of conditions. In oral-exposed regions, wetting is relevant to salivary pellicle formation, which affects microbial colonization and adhesion. For implants, wettability is a key factor in the osseointegration process and can affect protein adsorption and cell attachment. Wetting also impacts adhesion and seal bonding. Dental materials must also be resilient to biodegradation and aging. Studying wetting before and after conditioning that simulates these processes can reveal the suitability of new materials for real-world use.

Static water contact angles don't always tell the whole story. More advanced techniques can provide greater insight into relevant surface characteristics. The tilting method can be useful for further studying wettability. By tilting the surface, gravity pulls the drop downwards, which reveals more about how liquid spreads on the surface. The maximum angle formed at one side of the drop is known as the advancing contact angle. The minimum angle formed at the other side is known as the receding contact angle. The difference between the two angles is the contact angle hysteresis. Two materials with similar static contact angles can have vastly different contact angle hysteresis values. Another technique that can provide information about the polar and dispersive characteristics of the surface is surface energy measurement⁸. This method involves measuring the contact angles of two or more pure liquids on the same surface.

Figure 2: Advancing (a) and Receding (r) Contact Angles at a tilted angle (t). [Source: ramé-hart instrument co.] Click to enlarge

Using different materials isn't the only way to achieve the ideal biointerface. Surface treatments and modifications can also be highly effective. Some common techniques include surface texturing via sandblasting, acid etching, or laser, application of a coating, and plasma treatment. Contact angle measurements can be used to ensure such treatments have been applied consistently and to study the durability of these methods.

ramé-hart instrument co. offers high-quality instruments that are both user-friendly and flexible for contact angle measurements. Accessories like the Automated Dispensing System and Automated Tilting Base enable repeatable experiments and automation for studying biomaterial surfaces. If you are interested in learning how measuring contact angles can assist your application, contact us or send us a sample to see it in action. We can offer custom solutions for complex sample geometries or assist you in developing a measurement method for using our instruments.

Thank you for your continued business,

The ramé-hart Team

ramé-hart instrument co.

World Leader in Surface Science Instruments