Plaque attack: why materials matter – Neil Photay – CosTech

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  Posted by: Dental Design      6th March 2019

Dental plaque is responsible for the majority of serious complications seen in the oral environment, especially those affecting the soft tissue. The root cause of periodontal diseases, this sticky film has a natural affinity to our teeth and therefore can be highly damaging if not properly removed on a regular basis.

However, it is not just natural teeth that plaque can cling to, and dental restorations too can experience build-ups of plaque that can then compromise the soft tissue surrounding them. As such, it’s necessary for professionals to consider the plaque affinity of various materials when fitting dental restorations, especially when it comes to patients who are more prone to plaque build up.


The oral microbiome

Our oral cavities are home to a plethora of different microorganisms including bacteria, viruses and fungi.[i]Over 700 unique species of bacteria have been identified in our mouths, and it’s been revealed that just one milligram of dental plaque can hold over 100 billion individual bacterium. What we eat and drink, our oral hygiene routines and our genetic susceptibility can heavily influence the concentration of these bacteria, which is why every mouth is unique and why certain people are more prone to gum diseases and bacterial infections than others.[ii]

These huge colonies of bacteria are usually organised in biofilms – thin layers of cells covering the majority of surfaces within the oral cavity. In light of this, the materials selected for restorations need to be resilient, as they will have extended contact with plaque causing bacteria.


What affects plaque adhesion?

Research has revealed that plaque may adhere better to restorations than natural teeth, and this may be due to a number of factors including both surface roughness and surface-free energy.[iii]The surface of a material influences plaque adhesion as certain materials have porous or rough surfaces. Though not visible to the naked eye, surfaces with these characteristics have indentations and crevices that are the perfect breeding ground for bacteria as they are harder to keep clean by conventional brushing. Therefore, smoother surfaces are less likely to attract plaque as they do not give microorganisms a chance to colonise in this manner.[iv]

Surface-free energy is more complex, but in simplistic terms it relates to the bonding forces created between plaque causing bacteria and tooth surfaces due to their physiochemical interactions. These interactions create a push or pull effect between two substances. High-energy surfaces (those with a strong pull together effect) have been shown to collect more plaque and bind that plaque more strongly – meaning more opportunity for these pathogens to cause damage.[v]


Which materials are best?

The library of materials used in dental restorations keeps on expanding. From metallic alloys and resins to porcelains and ceramics, these materials all present different opportunities for plaque accumulation in terms of their smoothness and surface energy. Though studies have proven that initial bacteria numbers present in the pellicle layer are the same regardless of the material used for restoration,[vi]over time material choices do seem to have a noticeable effect.

Research carried out on composite and resin materials suggests that, despite having a good level of surface smoothness, the chemical make up of the materials increases the surface energy exhibited and can therefore lead to greater bacterial adhesion.[vii]Furthermore, a study that explored plaque’s adhesive capabilities to an array of dental materials found that amalgam was most attractive to plaque, followed by resin composites, then gold alloys and finally ceramics.[viii]

However, a similar study exploring the same four materials found that plaque retention was higher on all metallic materials than resin and ceramics.[ix]This just goes to show that material alone is not the primary causation for plaque accumulation, though it may play a reasonable part.

Substantiating this is the idea that the finish on the material could make a bigger difference than the actual material itself. One study that compared glazed porcelain, polished metal, composites and normal tooth enamel found that composites accumulated plaque much sooner, and this was because the finish on these did not provide the same smooth surface as other materials.[x]

Some recently introduced dental materials, such as zirconia, have been shown to exhibit a low affinity to plaque.[xi] This is thought to be because the material has a low surface-free energy. Therefore, for patients who exhibit high levels of plaque, restorations made from zirconia such as the new Monolith Full Contour Zirconia from CosTech Dental Laboratory are a smart option. These units are available to both private and NHS patients at just £29.95 including delivery.


Just part of the puzzle

Overall, the effect that materials have on levels of plaque is significant, but it’s clear that other factors come into play too. When treating a patient further considerations will impact the decision such as aesthetics and strength, and therefore it’s your duty to discuss all of these aspects with the individual before settling on a solution that you are both happy to proceed with.


For more information about CosTech Dental Laboratory, please visit call 01474 320076



[i]Oilo, M., Bakken, V. Biofilm and Dental Biomaterials. Materials 2015; 8: 2887-2900.

[ii]US Department of Health and Human Services. Periodontal (Gum) Disease. Link:[Last accessed November 18].

[iii]Litonjua, L., Cabanilla, L., Abbott, L. Plaque Formation and Marginal Gingivitis Associated with Restorative Materials. Compendium. 2012; 33(1).

[iv]Litonjua, L., Cabanilla, L., Abbott, L. Plaque Formation and Marginal Gingivitis Associated with Restorative Materials. Compendium. 2012; 33(1).

[v]Litonjua, L., Cabanilla, L., Abbott, L. Plaque Formation and Marginal Gingivitis Associated with Restorative Materials. Compendium. 2012; 33(1).

[vi]Hannig, M. Transmission Electron Microscopy of Early Plaque Formation on Dental Materials in Vivo. Eur J Oral Sci. 1999;107(1):55-64.

[vii]Litonjua, L., Cabanilla, L., Abbott, L. Plaque Formation and Marginal Gingivitis Associated with Restorative Materials. Compendium. 2012; 33(1).

[viii]Kawai, K., Urano, M. Adherence of Plaque Components to Different Restorative Materials. Oper Dent. 2001;26(4):396-400.

[ix]Wise, M., Dykema, W. The Plaque-Retaining Capacity of Four Dental Materials. J Prosthet Dent. 1975; 33(2): 178-190.

[x]Weitman, R., Eames, W. Plaque Accumulation on Composite Surfaces After Various Finishing Procedures. J Am Dent Assoc. 1975;91(1):101-106.

[xi]Cionca, N., Hashim, D., Mombelli, A. Zirconia Dental Implants: Where Are We Now, and Where Are We Heading? Link:[Last accessed November 18].

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