Pumice problems
Featured Products Promotional FeaturesPosted by: Dental Design 19th December 2024
Infection control is widely understood to be an essential aspect of any dental laboratory workflow. When carried out effectively, health risks can be minimised for technicians, clinicians, and even patients who eventually receive a restoration.
Pumice slurries are one apparatus within the laboratory that can harbour a significant volume of bacteria. Ensuring technicians manage this part of the workflow safely is essential, and steps must be taken to maintain regulatory compliance and ultimate infection control.
Contamination sources
The microbiological contamination of pumice slurries is widely reported in the literature. International studies have cited contamination rates as high as 66.7%,[i] or even 100% in one assessment of 20 randomly selected slurries.[ii]
The variety of microorganisms found within pumice slurry samples can be categorised in a multitude of different ways – fungal and non-fungal species, Gram positive and negative bacteria – but one interesting lens is the variety of oral and non-oral species. One study[iii] found that 60% of assessed prostheses delivered to dental laboratories were contaminated with pathogenic microorganisms native to the oral cavity of patients. These included streptococci, lactobacilli and diphtheroids. This creates the potential for the pumice slurries to be contaminated with such bacteria, posing risks to technicians and other patients.
The differentiation of these contaminants tells us that the microorganisms may come from both items that have been sent from a practice after intraoral placement/use, as well as microorganisms encountered through the transportation and treatment process. If used restorations are not disinfected by either the dentist or the dental technician, its introduction to the pumice slurry heightens the risk of contamination for subsequently treated items. For this reason, all prostheses received in a laboratory should be disinfected prior to being worked on by a dental technician.[iv]
A pumice slurry may also be contaminated through the actions of the technician or from objects in the surrounding environment if they are not managed properly.
In the air
The way that pumice is utilised in the process of polishing restorations to create an even and aesthetic finish can put technicians at risk. Aerosol formation through the process is not uncommon, creating inhalation risks for all technicians.[v] It is recognised that this also aerosolises the bacteria found within the slurry,[vi] which can then spread throughout the dental laboratory.
Pneumoconiosis, a disease that occurs when individuals experience a build-up of inhaled particles in the lungs, is a known occupational lung condition amongst dental technicians.[vii] Where a laboratory is small and ill-ventilated, this risk is especially noteworthy. With dental technicians uniquely exposed to higher rates of this condition, the inhalation of aerosolised microorganisms that contaminate the pumice is also possible.
Studies have reported that Gram negative bacteria such as Pseudomonas, Moraxella and Acinetobacter can all be found in contaminated pumice and cause infection through aerosol production and inhalation.i These bacteria could cause ocular and respiratory infection, especially in individuals with existing chronic respiratory disorders.
Clinicians should ensure laboratories are well ventilated, and that they wear appropriate goggles with side-shield protection, as well as masks that reduce the risk of aerosol inhalation. A respiratory mask is ideal, as it has a 95% filtering capacity for particles with a diameter of 0.3µm, compared to surgical masks which filter out approximately 80% of particles.[viii] A proper fit and seal around the edge is necessary.
Cross-contamination
Dental technicians work with restorations that will aim to provide newfound function and aesthetics to patients. Edentulism is often a result of poor oral health and infection, and if pumice slurries and polished restorations are not properly decontaminated, patients could be subject to further harmful microorganisms. Creating two pumice slurries may be helpful; using one for restorations and refurbishments and another for new restorations that have been created in the laboratory. This can minimise the spread of native oral microorganisms to new restorations.
Clinicians should minimise the presence of harmful microorganisms within a pumice slurry by introducing an effective disinfectant. This is recommended in the literature, as is the daily changing of a pumice solution – if not more frequently. Lathe brushes, rag wheels and other laboratory tools should also be cleaned and sterilised daily.[ix]
The PumiceSafe Universal Cleaner from Kemdent is an effective solution for every dental laboratory. The algaecidal, fungicidal cleaner is an optimal application for pumice slurries, creating a pleasant smelling and microorganism-free solution. This reduces dust in the laboratory environment, and simply minimises the risk of cross contamination. It can also be used as a tabletop surface cleaner, to help every element of the laboratory.
Infection control is essential in every aspect of the dental laboratory, especially in the management of the pumice slurry. Knowing the risks that they present to technicians and patients, professionals can take effective steps to reduce harm in any given environment.
For more information about the leading solutions available from Kemdent, please visit www.kemdent.co.uk or call 01793 770 256
[i] Firoozeh, F., Zibaei, M., Zendedel, A., Rashidipour, H., & Kamran, A. (2013). Microbial contamination of pumice used in dental laboratories. Healthcare in Low-resource Settings, 1(1), e5-e5.
[ii] Vafaee, F., Radan, P., Firouz, F., Heidari, B., Izadi, A., Khoshhal, M., & Basami, M. (2013). Microbial contamination of pumice powder and slurry in dental laboratories of hamadan. Journal of Dental Research, 5(2).
[iii] Qaisar, A., Asmat, M., Fareed, M. A., Baig, Q. A., & Noor, N., (2015). Microbial contamination of pumice slurry, pumice powders and acrylic dentures constructred in dental laboratories of Lahore. Biomedia Vol 31., Issue 2, Apr. – Jun., 2015. (Online) Available at: http://thebiomedicapk.com/articles/438.pdf [Accessed October 2024]
[iv] Fluent, M. T., Molinari, J. A., (2013). How the Dental Laboratory Provides Infection Control. Inside Dental Assisting, March/April 2013, Volume 9, Issue 2. (Online) Available at: https://www.aegisdentalnetwork.com/ida/2013/04/how-the-dental-laboratory-provides-infection-control [Accessed October 2024]
[v] Sykes, L. M., Said, M., Ehlers, M., Mateis, S. M., van Dyk, C., & Dullabh, H. D. (2019). Microbial contamination of denture polishing equipment. South African Dental Journal, 74(3), 116-122.
[vi] Upendran, A., Gupta, R., Geiger, Z., (2023). Dental Infection Control. StatPearls [Internet]. (Online) Available at: https://www.ncbi.nlm.nih.gov/books/NBK470356/ [Accessed October 2024]
[vii] Ergün, D., Ergün, R., Özdemir, C., Öziş, T. N., Yilmaz, H., & Akkurt, İ. (2014). Pneumoconiosis and respiratory problems in dental laboratory technicians: analysis of 893 dental technicians. International Journal of Occupational Medicine and Environmental Health, 27, 785-796.
[viii] Ding, J., Li, J., Qi, J., & Fu, L. (2023). Characterization of dental dust particles and their pathogenicity to respiratory system: a narrative review. Clinical Oral Investigations, 27(5), 1815-1829.
[ix] Fluent, M. T., Molinari, J. A., (2013). How the Dental Laboratory Provides Infection Control. Inside Dental Assisting, March/April 2013, Volume 9, Issue 2. (Online) Available at: https://www.aegisdentalnetwork.com/ida/2013/04/how-the-dental-laboratory-provides-infection-control [Accessed October 2024]
