Open AccessSystematic Review

Composite Dust Toxicity Related to Restoration Polishing: A Systematic Review

Kamila Kucharska

Anna Lehmann

^2,*

Martyna Ortarzewska

Jakub Jankowski

and

Kacper Nijakowski

^2,*

Department of Conservative Dentistry and Periodontology, University Centre of Dentistry and Specialised Medicine, 60-812 Poznan, Poland

Department of Conservative Dentistry and Endodontics, Poznan University of Medical Sciences, 60-812 Poznan, Poland

Authors to whom correspondence should be addressed.

J. Compos. Sci. 2025, 9(2), 90; https://doi.org/10.3390/jcs9020090

Submission received: 24 January 2025 / Revised: 9 February 2025 / Accepted: 17 February 2025 / Published: 18 February 2025

(This article belongs to the Special Issue Feature Papers in Journal of Composites Science in 2024)

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Abstract

An integral part of daily dental practice is preparing and polishing placed composite restorations. When these procedures are performed, significant amounts of composite dust are released from the grinding material. This systematic review aims to enhance the existing body of knowledge, encourage further dialogue, and expand the understanding of composite dust and its related risks. Following inclusion and exclusion criteria, twelve studies were included. Several studies highlight that composite dust contains nanoparticles capable of deep lung penetration, posing significant health risks to both dental staff and patients. Inhalation of composite dust can lead to respiratory diseases such as pneumoconiosis. Studies have shown that water cooling during composite grinding reduces dust emissions but does not eliminate them completely. Researchers suggest that thermal degradation of the composite material, not just filler particles, may be the source of the nanoparticles. In vitro studies have shown the toxicity of composite dust to bronchial and gingival epithelial cells, especially at high concentrations. Further research is needed on the health effects of composite dust and the development of effective methods to protect staff and patients.

Keywords:

composite dust toxicity; dental composite polishing; composite nano-dust; dental airborne particles

1. Introduction

Resin-based composite (RBC) is one of the most popular materials for direct dental restorations in the dental office [1,2]. Essential features of the composite include excellent aesthetics and ease of replication of the appearance of tooth tissue [3,4]. RBC materials are increasingly used for complex rehabilitations, including restoring endodontically treated teeth [5]. The thermal expansion coefficient of the composite is close to that of hard tooth tissues; it shows high resistance to abrasion and fracture [6,7]. Correctly placed and prepared composite material is resistant to the extreme oral environment. Despite many of the above advantages, composites also have disadvantages, such as moisture sensitivity, polymerisation shrinkage, and, in general, high procedural requirements during placement [1,8].

One of the key steps in composite tooth restoration is polishing. It guarantees better aesthetics and durability and reduces the risk of bacterial adhesion and secondary caries [9,10]. The role of polishing in removing the oxygen inhibition layer is crucial [11]. However, in light of recent research, preventing the formation of the oxygen inhibition layer has proven to be even more important than its removal [12]. Polishing begins after the final fit of the restoration in the bite, starting with coarse-grained drills moving to fine, followed by abrasive discs and strips of various gradations, from coarse to very fine, and ending with polishing with a brush and polishing paste. One of the most commonly used systems for polishing uses disks with a decreasing abrasiveness gradation. Usually, the manufacturer recommends that water cooling not be used during polishing, especially when aluminium oxide discs are used [13]. Because different abrasive discs are needed, polishing can take several minutes, during which composite nano-dust is emitted into the environment [14]. However, disc polishing is one of the better methods for smoothing composite restorations [13,15].

Given the great popularity of RBCs, composite dust inhalation has become a significant concern in modern dentistry. It has to be considered that dust toxicity can be obtained also during the repolishing procedures required to deal with gloss and colour instability [16]. It can lead to, among others, pneumoconiosis, chronic bronchitis, emphysema, dust-induced disseminated pulmonary fibrosis, systemic connective tissue disease, and kidney failure. The most commonly reported complication of dust inhalation is nonspecific pneumonia [17,18,19]. Additionally, composite dust can release large amounts of unpolymerised residual monomers, as the filler particles remain coated with resin [20,21]. It is well-known that the conversion rate of the composite material is around 60–70% or even lower [22,23]. These unpolymerised monomers can be inhaled [17,24]. Moreover, in an aqueous environment, composite materials acidify the surroundings, potentially releasing methacrylic acid, which could harm oral and systemic health [25,26].

Our international study found that the issues of composite toxicity and solubility are relatively unknown among dentists [27]. The current literature lacks definitive data on the airborne persistence of composite dust and the optimal timing for removing protective masks in dental settings [14]. Recent innovations in dust filtration systems and personal protective equipment (PPE) have significantly enhanced safety protocols for dental practitioners, particularly in response to the challenges highlighted during the COVID-19 pandemic [28]. Specialised suction devices have been developed to reduce aerosol dissemination during procedures, thereby minimising the risk of viral transmission. The incorporation of advanced air purification systems, including HEPA filters and ultraviolet germicidal irradiation (UVGI), has been explored to continuously filter and disinfect the air in dental clinics, effectively reducing airborne pathogens. Also, N95/FFP2 respirators provide superior filtration and offer enhanced protection [29].

Based on current and forthcoming research, we can enhance the protection of both patients and dental staff from respiratory, circulatory, and excretory diseases. Therefore, it is essential to accurately characterise nanoparticles and assess their toxicity using appropriate in vitro and in vivo methods. This systematic review aims to contribute to the existing body of literature, stimulate further discussion, and deepen the understanding of composite dust and its associated risks.

2. Materials and Methods

2.1. Search Strategy and Data Extraction

Our systematic review was conducted based on the records published from 1 January 2010 to 18 January 2025, according to the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA, Supplementary Materials) statement guidelines [26], using the databases PubMed, Scopus, Web of Science, and Embase. The search queries included:

-: for PubMed: dental AND composite AND (dust OR “nano-dust” OR nanoparticle OR “airborne particle”) AND (polishing OR grinding OR toxicity OR exposure)
-: for Scopus: TITLE-ABS-KEY (dental AND composite AND (dust OR “nano-dust” OR nanoparticle OR “airborne particle”) AND (polishing OR grinding OR toxicity OR exposure);
-: for Web of Science: TS = (dental AND composite AND (dust OR “nano-dust” OR nanoparticle OR “airborne particle”) AND (polishing OR grinding OR toxicity OR exposure);
-: for Embase: ’dental’:ti,ab,kw AND ’composite’:ti,ab,kw AND (’dust’:ti,ab,kw OR ’nano-dust’:ti,ab,kw OR ’nanoparticle’:ti,ab,kw OR ’airborne particle’:ti,ab,kw) AND (’polishing’:ti,ab,kw OR ’grinding’:ti,ab,kw OR ’toxicity’:ti,ab,kw OR ’exposure’:ti,ab,kw).

The retrieved search results were filtered by publication date after 1 January 2010.

The records were screened by the title, abstract, and full text by two independent investigators. The studies included in this review matched all the predefined criteria according to PICOS (“Population”, “Intervention”, “Comparison”, “Outcomes”, and “Study design”), as presented in Table 1. A detailed search flowchart is shown in Figure 1.

2.2. Quality Assessment and Critical Appraisal for the Systematic Review of Included Studies

The risk of bias in each individual study was assessed according to the “Study Quality Assessment Tool” issued by the National Heart, Lung, and Blood Institute within the National Institute of Health [27]. These questionnaires were answered by two independent investigators, and any disagreements were resolved by discussion between them.

Figure 2 reports the summarised quality assessment. The most frequently encountered risk of bias was the absence of data regarding the blinding of samples. Critical appraisal was summarised by adding up the points for each criterion of potential risk (points: 1—low, 0.5—unspecified, and 0—high). All studies were classified as having “good” quality (≥85% total score).

3. Results and Discussion

Following the search criteria, our systematic review included twelve studies. In the selected material, the authors presented, in the form of experimental studies methodology for testing composite dust, the issue of its toxicity and its impact on the human body and the possibilities of limiting it. More detailed information on the methodology of these studies is provided in Table 2.

Table 3 provides a summary of the main findings from the included studies. The results of each study are discussed below.

Firstly, Van Landuyt et al. [17] examined the characteristics of dust generated during composite grinding and assessed the clinical exposure of dental personnel to this dust. The authors highlighted that composite dust may contain respirable particles (smaller than 5 μm in size) that are capable of penetrating deep into the lungs. They also noted that dental personnel often lack sufficient awareness of this risk and frequently fail to implement appropriate protective measures. Their in vitro study demonstrated that all tested composites release significant amounts of respirable dust, with concentrations far exceeding acceptable safety standards. However, the authors emphasised that the study simulated a worst-case scenario—grinding without cooling or aspiration—which might overestimate actual dust concentrations in a dental office. Measurements conducted in a clinical setting confirmed that short episodes of highly respirable dust concentrations can occur during composite polishing. Two years later, Van Landuyt et al. [36] continued their research, concentrating on a more detailed analysis of the nanoparticles released during composite grinding. The authors employed more advanced measurement techniques, such as the miniDiSC, and investigated the chemical composition of the dust. Using a bur on dental composites generates airborne nanoparticles, which can accumulate in high concentrations within the breathing zone of the dentist and the patient. Microscopic and spectroscopic analyses revealed that the dust consists of both filler and resin particles, indicating that the nanoparticles may be encased in a resin layer. The authors stressed the importance of conducting further toxicological studies to evaluate the potential health risks posed to dental personnel by inhaling composite dust nanoparticles.

Scientists have also explored the cytotoxic potential of composite dust particles on bronchial epithelial cells. In 2016, Cokic et al. [18] conducted a study to investigate the cytotoxic effects of dust generated during the removal and polishing of composites on human bronchial epithelial cells, focusing on the impact of varying dust concentrations. The study assessed the effects of composite dust, derived from five different composite materials, on cell viability, membrane integrity, and the production of pro-inflammatory cytokines (IL-1β and IL-6) by 16HBE14o-cells. The cells were exposed to composite dust solutions at concentrations ranging from 1.1 µg/mL to 3.3 mg/mL for 24 h. The findings demonstrated that composite dust exhibited no cytotoxicity at concentrations up to 330 µg/mL. However, at concentrations between 660 µg/mL and 3.3 mg/mL, a 30–40% reduction in cell metabolic activity was observed, though no damage to cell membranes occurred at any concentration tested. Additionally, the levels of IL-1β remained unaffected regardless of the dust concentration, while a 30–40% reduction in IL-6 production was observed at a concentration of 3.3 mg/mL. In conclusion, composite dust can influence the metabolism of bronchial epithelial cells, but only at very high concentrations. No cytotoxicity or cell membrane damage was detected at clinically relevant dust concentrations. The decreased IL-6 production at high dust concentrations may suggest an impact on inflammatory processes.

Four years later, the team of Cokic et al. [19] published a follow-up study that expanded on their earlier research by supplementing information about the cytotoxicity of the respirable fraction of composite dust (<5 μm) from three different composite materials and extending it to include the genotoxic potential of this fraction on human bronchial cells (16HBE14o-). In the study, cells were exposed to composite dust at a concentration of 50 µg/mL for 3 h to evaluate genotoxicity and at concentrations ranging from 3 µg/mL to 400 µg/mL for 24 and 72 h to assess cytotoxicity. The results revealed that the respirable fraction of composite dust caused DNA damage in 16HBE14o-cells. A mild but statistically significant delay in the G0/G1 phase of the cell cycle was observed following exposure to dust from one of the tested materials (Transbond XT). Decreased formazan production, indicative of reduced metabolic activity, was detected at concentrations above 12.5 µg/mL (Filtek Supreme XTE) and 25 µg/mL (Transbond XT) after 24 h of exposure. However, after a 72 h exposure, this decrease was already apparent at concentrations as low as 3 µg/mL (Transbond XT) and 50 µg/mL (GrandiO). The disruption of cell membrane integrity became more pronounced with prolonged exposure, occurring at concentrations above 50 µg/mL (Transbond XT), 100 µg/mL (GrandiO), and 400 µg/mL (Filtek Supreme XTE). These findings demonstrated that the respirable fraction of composite dust exhibits genotoxic effects on bronchial epithelial cells and may have a stronger impact than the full dust fraction previously studied by Cokic et al. in 2016 [18]. Importantly, DNA damage was observed even at subcytotoxic concentrations, indicating that these effects are not limited to high dust concentrations. The smaller particle sizes and larger specific surface area of the respirable fraction likely contribute to its toxic potential. However, both studies were conducted in vitro, meaning that the results may not fully reflect the actual exposure conditions encountered in dental offices.

In 2017, Cokic et al. [20] and, in 2019, Nilsen et al. [34] directed their research toward investigating monomer emissions from composite dust and their potential effects on the health of dental personnel. Cokic et al. [20] analysed the release of monomers from respirable composite dust (<5 μm) under laboratory conditions. They collected respirable dust and immersed it in water and ethanol. Using liquid chromatography–mass spectrometry (LC-MS/MS), they detected significant amounts of methacrylate monomers and bisphenol A (BPA) in both solutions, with ethanol facilitating higher release levels. The authors highlighted that respirable dust, with a particle size of less than 5 μm, can penetrate deep into the respiratory system. They also noted that inhaling methacrylate monomers can irritate the respiratory tract and potentially trigger allergic reactions.

In contrast, Nilsen et al. [34] conducted their study in a simulated clinical environment, where dental students wore air samplers while performing restorative procedures on phantom models. This study aimed to evaluate dental personnel’s exposure to the organic substances present in both gaseous and particle-associated forms from resin-based dental materials. The results indicated that exposure to volatile substances was below the detection limit, which the authors attributed to water cooling and high-flow suction during the procedures. Unlike the findings of Cokic et al. [20], no methacrylates were detected in the air samples. However, the authors stressed that dust exposure could vary depending on the procedure, the preventive measures employed, and the type of materials used. An analysis of a phantom model water revealed the presence of TEGDMA and DMABEE, suggesting that patients may be exposed to these substances.

In contrast to studies conducted in small experimental chambers, Bradna et al. [35], in 2017, carried out their experiments in an office with a larger volume (6.5 m³) to better simulate the real working conditions of dentists. Their research focused on the size and source of the nanoparticles released during the grinding of dental composites. The study involved four different materials and three types of drills, with grinding performed dry to simulate the most unfavourable scenario. The findings revealed that grinding all materials, including unfilled resin, generated nanoparticles ranging in size from 16.0 to 51.6 nm. Surprisingly, the highest concentration of nanoparticles was observed when grinding the micro-hybrid composite (Charisma) rather than the nanocomposites. The authors proposed that the nanoparticles were primarily generated by the thermal decomposition of the polymer matrix due to friction rather than from the filler particles themselves. This study provided valuable insights into the characteristics of the nanoparticles released during the grinding of dental composites. The topic was further examined by Camassa et al. [32] in 2023, who analysed the toxicity of composite dust on human bronchial epithelial cells (HBEC-3KT). Their study identified ultrafine particles with diameters of 15–30 nm, with the particle size distribution being independent of the composite type or the drill’s grain thickness. This finding supported Bradna et al.’s hypothesis [35] that the nanoparticles primarily originate from the thermal decomposition of the polymer matrix. Additionally, Camassa et al. [32] observed that high concentrations of composite dust caused damage to bronchial epithelial cells and that the dust particles were absorbed by the cells through endocytosis.

Scientists have also shown interest in the impact of water cooling on the quantity and size of the nanoparticles released during the grinding of dental composite materials, highlighting its importance in reducing health risks for dental staff, patients, and the environment. In 2019, the team of Cokic et al. [14] conducted a follow-up study based on earlier findings that composite grinding produces significant amounts of dust, including nanoparticles. The researchers compared the concentration and size of the nanoparticles released during the dry and water-cooled grinding of seven different dental composites. The results demonstrated that water cooling reduced particle release by approximately half. However, despite this reduction, the concentration of airborne nanoparticles remained high and persisted for up to 10 min after grinding. This underscores the need for water cooling as a mitigation strategy while also pointing to the necessity of additional measures to manage nanoparticle exposure effectively.

In 2022, Jiang et al. [31] investigated the effects of composite dust on lung epithelial cells (A549), comparing the cytotoxicity and inflammatory response of cells exposed to dust from four different dental materials. The study revealed that dust from all tested materials adversely affected A549 lung cells, reducing cell viability, damaging cell membranes, and increasing the production of reactive oxygen species. Similar concentration–effect curves were found for all samples. No significant differences in cytotoxicity effects were observed among different materials grounded with and without water. A significant reduction in viability was noted starting at 3 μg/mL in the wet ground and at 30 μg/mL in the dry one, although this outcome varied depending on the material used. Materials containing methacrylate monomers, such as composites and hybrid materials, induced a stronger inflammatory response than ceramic material. Additionally, the size of the initial filler particles in the materials did not determine the dust particle size distribution. Instead, the authors suggested that the tools used and the grinding conditions play more significant roles in generating dust with a specific particle size distribution.

Reidelbach’s research team [33] also examined the issue of dust emissions during the grinding of composite materials, focusing on the cytotoxicity and estrogenicity of dust and eluates released into simulated dental office wastewater. Their findings showed that the eluates had strong bactericidal and cytotoxic effects on Vibrio fischeri bacteria and A549 lung cells. However, no estrogenic effects were detected in the tested eluates. The authors emphasised the need for further research to evaluate the long-term environmental impacts of composite materials, including their effects on wastewater treatment plants and the potential for these materials to enter drinking water systems. Also, it should be noted that components of RBCs have the potential to contribute to microplastic pollution with bioaccumulation risks [37,38].

Himmelsbach et al. [30] investigated the effects of dust generated during the grinding of dental composites on gingival epithelial cells. Unlike previous studies that focused on the effects of dust on bronchial or lung cells, this research examined the direct impact of dust on oral tissues, which is particularly relevant as the gums are consistently exposed to dust during dental procedures. The researchers found that the particle size varied significantly depending on the environment. In distilled water, both materials produced particles of similar size (171.9 nm–2.7 µm). In contrast, in artificial saliva, the particles were larger, suggesting that components in saliva, such as proteins and electrolytes, may influence particle agglomeration. Exposure to dust within the tested concentration range did not significantly affect the cell growth rate. However, the authors noted that various cell growth parameters could offset each other, making interpreting these results complex. They observed that exposure to dust, particularly at higher concentrations, increased fibronectin expression in the intercellular space. Since fibronectin is critical in cell migration, this finding suggests that composite dust may influence wound-healing processes in the oral cavity.

The previous systematic review by Iliadi et al. [39] focused on dust emissions during routine dental procedures involving composite materials. The authors discussed 13 studies to evaluate the influence of various factors on the amount and type of dust produced, as well as its potential health effects. The study reinforced the conclusions of earlier research regarding the health risks posed to dentists and patients by inhaling composite dust nanoparticles. The authors emphasised the need for further studies to establish specific guidelines for the safe use of composite materials.

3.1. Study Limitations

The review has several limitations that should be considered when interpreting the findings. First, the included studies exhibit significant variability in methodology, materials tested, and experimental conditions, such as polishing techniques and types of composite materials used. This variation limits the ability to draw general conclusions or make direct comparisons across studies. Moreover, due to the considerable heterogeneity of the studies and the diversity of outcome measures, it was not possible to conduct a meaningful meta-analysis. Additionally, some of the studies included in this review have small sample sizes, which could affect the validity of the findings. As a result, the conclusions drawn from these in vitro studies may not be fully representative in clinical settings. While in vitro studies provide valuable insights, future research should involve in vivo models to assess the long-term pulmonary and systemic effects of composite dust exposure in realistic clinical scenarios.

3.2. Potential Clinical Implications and Further Research Directions

Our review highlights numerous hazards associated with the composite particles generated during composite polishing. Table 4 summarises potential recommendations developed by previous authors to help reduce the release of composite nano-dust.

There is a pressing need for more comprehensive, multidirectional studies on composite materials and the appropriate techniques to maximise their benefits while minimising or eliminating their drawbacks. First, ongoing research into RBC composition is essential to evaluate their effects on oral tissues and determine their safety profiles. This should be followed by a series of laboratory and clinical studies conducted to the greatest possible extent. Given the concerns regarding cytotoxicity and respiratory hazards, research should focus on designing novel composite materials that minimise nanoparticle release without compromising mechanical properties. Additionally, the continuous education of dentists on the proper techniques for working with composite materials is crucial to minimise the potential toxicity of RBCs. Ultimately, the goal of these efforts should be to establish clear guidelines regarding the indications and contraindications for using composite materials in direct tooth restorations within the oral cavity.

In vitro studies present concerning reports about the potential dangers of using composite materials. However, composites remain the best and most widely used material in dental practice for direct restorations. Their advantages significantly outweigh the potential health risks associated with their use. There are various ways to reduce the risks associated with composite dust exposure in dental offices, making it essential to educate dental staff about the risks and implement proper precautions. These include adopting advanced suction systems, mandatory water cooling during procedures, and implementing specific protective equipment for dental staff and patients. Further research into the health effects of composite dust is needed to understand its mechanisms of action better and to develop more effective protective measures. It would benefit from identifying specific areas requiring investigation, e.g., in vivo validation of current in vitro findings, the assessment of environmental effects such as wastewater contamination, and longitudinal studies to evaluate the long-term health impacts of composite dust exposure. This approach would provide clearer guidance for both clinical practice and future research priorities.

4. Conclusions

Based on an analysis of available sources, composite dust generated during routine dental procedures presents a significant health risk to both dental staff and patients. Inhalation of composite dust, particularly nanoparticles, can lead to serious health issues, including respiratory diseases such as pneumoconiosis. Most studies have concentrated on the dust generated during composite grinding with a drill, while the dust produced during polishing with Sof-Lex discs remains underexplored. Several physicochemical factors, such as particle diameter, morphology, charge, surface properties, chemical composition, stability, solubility, and biodistribution, affect the impact of nanoparticles on living organisms. Nanoparticles can be more harmful than larger particles of the same chemical structure due to their ability to penetrate deeper into the lungs. A notable limitation of this study is the reliance on supporting evidence primarily derived from in vitro studies. While these studies provide valuable insights into the potential health risks associated with composite dust, they may not accurately reflect clinical settings. The controlled conditions of in vitro experiments often fail to replicate the complex dynamics of dental office environments, such as the use of suction, water cooling, or other mitigating factors. Consequently, the extrapolation of these findings to clinical practice should be cautiously approached, as the actual risks in real-world scenarios may differ.

Supplementary Materials

The following supporting information can be downloaded at https://www.mdpi.com/article/10.3390/jcs9020090/s1: PRISMA Checklist.

Author Contributions

Conceptualisation, K.K. and A.L.; methodology, K.N.; formal analysis, K.K. and A.L.; investigation and data curation, K.K., A.L. and M.O.; writing—original draft preparation, K.K., A.L. and M.O.; writing—review and editing, J.J. and K.N.; visualisation, K.N.; supervision, K.N. All authors have read and agreed to the published version of the manuscript.

Funding

This research received no external funding.

Data Availability Statement

No new data were created or analyzed in this study.

Conflicts of Interest

The authors declare no conflicts of interest.

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Figure 1. PRISMA flow diagram presenting search strategy.

Figure 2. Quality assessment, including the main potential risk of bias (risk level: green—low, yellow—unspecified, red—high; quality score: green—good, yellow—intermediate, red—poor) [14,17,18,19,20,30,31,32,33,34,35,36].

Table 1. Inclusion and exclusion criteria according to the PICOS.

Parameter	Inclusion Criteria	Exclusion Criteria
Population	Dental composite samples	Samples from other dental materials
Intervention	Polishing/grinding
Comparison	Not applicable
Outcomes	Quantitative measures, e.g., particle size distribution, cell toxicity, cell viability	Only qualitative analysis or sample roughness analysis
Study design	In vitro studies	Other original articles, literature reviews, case reports, letters to the editor, conference reports
Study design	Published after 1 January 2010	Not published in English

Table 2. Detailed information on the methodology of included in vitro studies testing composite dust.

Authors	Article Title	Tested Materials	Technical Data	Samples and Conditions	Measures and Analyses
Himmelsbach et al., 2023 [30]	Effect of dental composite dust on human gingival keratinocytes	- Filtek Supreme XTE (nanocomposite); - Ceram.x universal (nanoceramic composite).	- All samples ground with red (fine grain size 30 μm) diamond burs (16,000 rpm); - Assessment: DLS, RTCA iCELLigence, light microscopic examinations, SEM, indirect immunofluorescence.	- Composite grinding (no water cooling), isolated dental room, 8 min/per sample; - 2 types of composites (n = 40/per composite); - Setting: composite cylindrical blocks (5 mm × 2 mm).	- HGK cell cultures; - The particle size distribution; - The electrical impedance of HGK; - Immunofluorescence staining of HGK; - Analysis of the cell morphology of HGK.
Jiang et al., 2022 [31]	Cytotoxic and inflammatory response of human lung epithelial cells A549 to particles released from dental restorative materials during dry and wet grinding	- Ceram.x universal (nanoceramic composite); - Filtek Supreme XTE (nanofilled composite); - Lava Ultimate [resin–nanoceramic (hybrid material)]; - VITABLOCS Mark II (ceramic).	- All samples ground with rough diamond bur (100 μm), micromotor (160,000 rpm); - Assessment: LAS, CPC, DLS, SEM, ESR spectroscopy, cell culture (human alveolar basal epithelial cells A549), LDH assay, WST-1 assay, Elisa Kit Ready-SET-Go! (IL-8).	- Material grinding (with and without water), isolated dental room, open plexiglass box; - 2 composites (n = 20/per composite), nanoceramic and ceramic; - Setting: composite cylindrical blocks (6 mm × 2 mm) and original block shape.	- Quantitative analysis of the release of micron-sized particles during grinding; - Quantitative analysis of sub-micron (<1 μm) particles; - Size characterisation of generated particles; - ROS production; - Cell toxicity and cell viability; - SEM evaluation; - Influence on the formation of pro-inflammatory mediators from particle exposure.
Camassa et al., 2021 [32]	Characterisation and toxicity evaluation of air-borne particles released by grinding from two dental resin composites in vitro	- Filtek Z250 (microhybrid composite); - Filtek Z500 (nanohybrid composite).	- All samples ground with black (super coarse, grain size 181 μm) and red (fine grain size 40 μm) diamond burs (40,000 rpm); - Assessment: SMPS, DLS, SEM, LDH assay.	- Composite grinding (no water cooling), glass chamber, dust collecting with a GSP conical inhalation sampler, with a cone diameter of 10 mm, airflow approximately of 10 L/min, a filter with pore size of 5 μm (Millipore); - 2 composites (4 dental dust samples: Filtek Z250 red and black, Z500 red and black; - Setting: composite sticks in stainless steel mould (2 mm × 2 mm × 25 mm).	- Size distribution of particles generated during grinding; - Size distribution of collected particles; - Cell toxicity and cell viability; - Hydrophobic size of particles.
Reidelbach et al., 2021 [33]	Cytotoxicity and estrogenicity in simulated dental wastewater after grinding of resin-based materials	- Ceram. × universal (nanoceramic composite); - Filtek Supreme XTE (nanofilled composite); - Lava Ultimate (resin-nanoceramic hybrid material); - Core-X flow (dual-cure hybrid composite).	- All samples ground with a diamond bur (106 μm, 20,000 rpm); - Assessment: Luminescent bacteria test, WST-1 assay, YES-assay.	- Material grinding (no water cooling), three material sample types: ground dust, suspensions and the eluates; - 3 composites (n = 50/per composite), nanoceramic; - Setting: composite cylindrical blocks (5 mm × 2 mm) and original block shape (14 mm × 14 mm × 18 mm).	- Inhibitory effect of water samples on the light emission of Vibrio fischeri; - Cell toxicity and cell viability; - Estrogenic activity.
Cokic et al., 2020 [19]	Cytotoxic and genotoxic potential of respirable fraction of composite dust on human bronchial cells	- Filtek Supreme XTE (nanocomposite); - GrandiO (nanohybrid composite); - Transbond XT (orthodontic composite).	- All samples ground with rough diamond bur (100 μm), micromotor (200,000 rpm); - Assessment: DLS/ELS, WST-1 assay, LDH assay, comet assay, TEM.	- Composite grinding (no water cooling), plexiglass chamber 27 × 27 × 42 cm; measurement 3 min during grinding and additional 10 min; dust transferred to cell culture for toxicity assessment (96-well plates); - 3 composites; - Setting: composite sticks in metal mould (17.4 mm × 5.4 mm × 1.6 mm).	- Particle size distribution; - Cell viability; - Membrane integrity; - DNA damage in individual cells; - Cellular uptake of particles by epithelial cells.
Cokic et al., 2019 [14]	The effect of water spray on the release of composite nano-dust	- Filtek Supreme XTE (nanocomposite) - GrandioSO and Herculite XRV Ultra (nanohybrid composite); - Spectrum TPH3 (micromatrix with nanotechnology); - Herculite XRV (microhybrid) - Durafill VS (microfilled anterior composite) ; - Heliomolar flow (microfill, flowable); - Control: no composite grinding.	- All samples ground with rough diamond bur (100 μm), micromotor (200,000 rpm); - Assessment: SMPS, TEM-EDS.	- Composite dry and wet grinding, closed chamber 1 m3; measurement 3 min during grinding and additional 10 min; - 7 types of composites (n = 3/per composite); - Setting: composite sticks in metal mould (17.4 mm × 5.4 mm × 1.6 mm).	- Particle number concentration; - Particle size distribution and average particle size; - Ultra-morphological and chemical analysis of dust.
Nilsen et al., 2019 [34]	Airborne exposure to gaseous and particle-associated organic substances in resin-based dental materials during restorative procedures	- Ceram.x universal; - Clearfil SE Bond (primer); - Clearfil SE Bond (bond).	- Identoflex composite polisher, polishing diamonds (40, 20 μm), coarse, medium, fine, superfine grits (Sof-Lex); - Assessment: GC/MS, (UHP)LC-MS.	- Restoration polishing; sampling period from the start of bonding procedure sampling pumps + water collection; - Setting: restorative treatment on phantoms.	- Qualitative and quantitative (molecular weight, retention times, molecular and characteristic ions) analysis.
Cokic et al., 2017 [20]	Release of monomers from composite dust	- Filtek Supreme XTE (nanocomposite); - GrandiO (nanohybrid composite); - Gradia Direct (microhybrid); - Z100 MP (conventional hybrid);	- All samples ground with rough diamond bur (100 μm), micromotor (200,000 rpm); - Assessment: LC-MS/MS, TEM-EDS.	- Composite grinding, (no water cooling), plexiglass chamber 27 × 27 × 42 cm; air sampling immediately before grinding until 10 min thereafter; - 4 types of composites (n = 5/per composite); - Setting: composite sticks in metal mould (17.4 mm × 5.4 mm × 1.6 mm).	- Release of methacrylate monomers and BPA in water and ethanol; - Ultra-morphological and chemical analysis of dust.
Bradna et al., 2017 [35]	Detection of nanoparticles released at finishing of dental composite materials	- Filtek Ultimate (nanohybrid) (mixture of primary SiO2 and ZrO2 nanoparticles and zirconia–silica agglomerates); - Estellite Sigma Quick (nanohybrid), Supra-nano fill, silica–zirconia; - Charisma (microhybrid) (with Ba glass microparticles); - LC Varnish (Unfilled resin).	- Diamond round bur (medium and fine)/tungsten carbide (20 blade), Diamond round (100,000 rpm), Diamond cylindrical torpedo (10,000 rpm), Tungsten carbide flame finisher (150,000 rpm); - Assessment: online spectrometer SMPS (particles from 16 to 638 nm) and APS (particles from 0.5 to 20 μm).	- Composite grinding (no water cooling); air sampling 30 sec after end of grinding, closed cabinet (2 × 1.3 × 2.5 m); - 4 composites; - Setting: composite specimens in Teflon moulds (20 mm × 8 mm × 10 mm).	- Aerosol particle concentration - Particle size distribution
Cokic et al., 2016 [18]	Cytotoxic effects of composite dust on human bronchial epithelial cells	- Filtek Supreme XTE (nanocomposite); - GrandiO and Tetric EvoCeram (nanohybrid); - Gradia Direct (microhybrid); - Z-100 MP (conventional hybrid).	- All samples ground with rough diamond bur (100 μm), micromotor (200,000 rpm); - Assessment: ELISA, TEM, DLS, ELS.	- Composite grinding (no water cooling); laminar flow cabinet and dust transferred to cell culture for toxicity assessment (96-well plates); - 4 types of composites; - Setting: composite sticks in metal mould (17.4 × 5.4 × 1.6 mm);	- Cytotoxicity against human bronchial epithelial cells (16HBE14a-), IL-1β, IL-6 cytokine release; - Characterisation of composite particles/dust.
Van Landuyt et al., 2014 [36]	Nanoparticle release from dental composites	- Filtek Supreme XTE (nanocomposite); - GrandiO and Tetric EvoCeram (nanohybrid); - Gradia Direct (microhybrid); - Z-100 MP (conventional hybrid).	- All samples ground with rough diamond bur (100 μm), micromotor; - Assessment: mini DiSC, TEM, SMPS, ESP, EPR.	- Composite grinding (no water cooling); composite blocks in a metal mould; plexiglass box 270 × 270 × 420 mm; air sampling NR; - 5 types of composites (n = 5/per composite); - Setting: composite sticks in metal mould (17.4 × 5.4 × 1.6 mm).	- Number and distribution of submicron particles; - Chemical identity of sampled particles; - Size distribution of composite dust; - OH-generation and nonspecific surface activity index.
Van Landuyt et al., 2012 [17]	Should we be concerned about composite (nano-) dust?	- Filtek Supreme XTE (nanocomposite); - Premise and Ceram.X and Tetric EvoCeram and Herculite (nanohybrid); - Gradia Direct (microhybrid); - Z-100 MP (conventional hybrid).	- All samples ground with rough diamond bur (100 μm), micromotor; - Assessment: TEM.	- Composite grinding (no water cooling); composite blocks in a silicon mould, plexiglass box 27 × 27 × 42 mm; air sampling 30 min; - 7 types of composites (n = 5/ per composite); - Setting: composite sticks in silicon mould (15 mm × 13 mm × 3 mm),	- Dust concentration; - Number and distribution of submicron particles.

Legend: APS, aerodynamic particle sizer; BPA, bisphenol-A; CCK8, cell counting kit-8; CPC, condensation particle counter; DLS, dynamic light scattering; EDS, energy dispersive spectroscopy; ELISA, enzyme-linked immunosorbent assay; ELS, electrophoretic light scattering; EPR, electron paramagnetic resonance; ESP, electrostatic precipitator; ESR, electron spin resonance; GC/MS, gas chromatography–mass spectrometry; HGK, human gingival keratinocytes; LAS, laser aerosol spectrometer; LC–MS/MS, liquid chromatography–mass spectroscopy; LDH, lactate dehydrogenase; miniDiSC, miniature diffusion size classifier; NR, not reported; ROS, reactive oxygen species; SEM, scanning electron microscopy; SMPS, scanning mobility particle sizer; TEM, transmission electron microscopy; UHP, ultra-high performance; WST-1, water-soluble tetrazolium salt; YES, yeast estrogen screen.

Table 3. Main findings of included studies testing composite dust.

Study	Main Findings
Himmelsbach et al., 2023 [30]	In saliva, larger particles were identified, with sizes ranging from 243 nm to 6.5 μm for nanofilled composite and 204 nm to 4.6 μm for nanohybrid composite. Comparable cell growth parameters for HGK cells exposed to composite dust (≤5 μm) were demonstrated at varying concentrations. The formation of large agglomerates at high particle concentrations (>100 μg/mL) was observed. Exposure to composite dust was associated with an upregulation of fibronectin expression.
Jiang et al., 2022 [31]	Wet and dry grinding of dental materials leads to the release of ultrafine and fine particles into the air, with a strong tendency to agglomerate. The particle size distribution ranges from 150 nm to 18 μm, regardless of material composition. All tested materials significantly affected the membrane integrity and viability of A549 cells.
Camassa et al., 2021 [32]	Airborne ultrafine particles were predominantly in the size range of 15–35 nm. Over 80% of the particles had a minimum Feret diameter of less than 1 µm. In solution, the particles exhibited larger diameters and showed a tendency to agglomerate. Cell toxicity was observed after 48 and 72 h of exposure and only at the highest concentrations.
Reidelbach et al., 2021 [33]	All materials exhibited cytotoxic effects at concentrations of 0.1 mg/mL, with no significant differences observed between them. All dental monomers and BPA showed concentration-dependent cytotoxic effects, although only BPA induced an estrogenic effect.
Cokic et al., 2020 [19]	Human bronchial epithelial cells (16HBE14o-) exposed to composite dust showed a 10–35% reduction in metabolic activity at high concentrations, along with mild genotoxic effects. Cellular uptake of respirable particles was found. Cytotoxic effects were observed only at the highest concentrations, while subcytotoxic concentrations caused mild genotoxicity.
Cokic et al., 2019 [14]	Both dry and wet grinding of composites produced high concentrations of nanoparticles, with the peak concentration occurring in the final stages of grinding. Using water spray significantly reduced particle release but did not eliminate it. Predominantly, nanoparticles were released, regardless of water spray use.
Nilsen et al., 2019 [34]	No detectable exposure to gaseous or particle-associated methacrylates was identified in the samples collected by the personal air samplers worn by students performing restorative procedures. Significant amounts of the components of ceram.x universal, including non-volatile substances, were detected in the positive control.
Cokic et al., 2017 [20]	Composite dust, regardless of type, could release significant amounts of unpolymerised methacrylate monomers, with higher concentrations detected in ethanol compared to water. Dust particles also emitted the endocrine disruptor BPA. The majority of particles were at the nanoscale, often formed by clusters of filler particles encapsulated within a resin matrix, although isolated nano-filler particles were also identified.
Bradna et al., 2017 [35]	The nanoparticle size distribution spanned a range of less than 16.0 nm to 51.6 nm, not only for nanocomposites but also for the microhybrid composite and the unfilled resin. The concentration of nanoparticles in the aerosol (5.0–68 × 10³ cm⁻³) was only moderately elevated, exceeding the background concentration by 1 to 8.5 times. The release of nanoparticles occurred regardless of the size or content of the filler particles.
Cokic et al., 2016 [18]	Exposure of bronchial epithelial cells (16HBE14o-) to composite dust revealed no membrane damage or IL-1β release across all tested concentrations. However, metabolic activity decreased at concentrations above 660 µg/mL, and IL-6 release declined at the highest concentrations of dust.
Van Landuyt et al., 2014 [36]	Clinical exposure measurements demonstrated high concentrations of nanoparticles > 10⁶ cm⁻³ in the breathing zones of dentists and patients, especially during aesthetic treatments or composite build-ups. Laboratory analysis confirmed airborne composite dust was primarily nanosized, with particle diameters ranging from 38 to 70 nm. Although oxidative reactivity was low, further toxicological studies are needed.
Van Landuyt et al., 2012 [17]	All tested composites released respirable dust (<5 µm) during clinical and laboratory procedures. Dust particles often comprised resin and filler aggregates or individual nano-fillers. The study highlighted the importance of mitigating inhalation risk through water cooling, effective aspiration, ventilation, and high-efficiency filtration masks.

Table 4. Summary of potential tips developed by the previous authors that may help reduce composite nano-dust.

Effects of Composite Dust	Factors Reducing Exposure	References
The increased risk of developing asthmatic diseases	Use of water cooling	[20]
The incidence of pneumoconiosis	Use effective suction systems	[40]
The increased risk of respiratory diseases, including respiratory cancers because of heavy metals and asbestos in composite dust	Choice materials with lower dust emissions (nanocomposites feature an increased amount of nanoparticles in the dust compared to traditional hybrid composites)	[36,40,41]
The cytotoxic effect on human bronchial epithelial cells	Careful pre-polymerisation sculpturing of the composites	[18,19,31,36,39,40]
Exhibiting genotoxic effects, damaging the DNA of cells	A two-stage procedure: laboratory preparation of composite in-/on-lays on demanding restorative treatments	[19]
Affecting fibronectin expression in the intercellular space of gingival keratinocytes, which may lead to increased cell migration/mobility	Using N95/FFP2 masks and fitting them properly to fit tightly on the face	[30]
Dust interaction with alveolar macrophages can lead to cell membrane damage and induction of oxidative stress	Appropriate ventilation	[36]
Environmental pollution by microplastics that can release monomers	Removal of the mask approximately 10 min after completion of composite preparation	[42]
Contamination of wastewater with various substances, including monomers and bisphenol A	Use of rubber dam	[33,34]
Allergic reactions most commonly caused by methacrylates	Using proper polishing techniques: lower speed and less pressure	[20]
	Proper polymerisation of the composite to avoid monomer release
	Use the face shield only as an accessory to other personal protective equipment

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Kucharska, K.; Lehmann, A.; Ortarzewska, M.; Jankowski, J.; Nijakowski, K. Composite Dust Toxicity Related to Restoration Polishing: A Systematic Review. J. Compos. Sci. 2025, 9, 90. https://doi.org/10.3390/jcs9020090

AMA Style

Kucharska K, Lehmann A, Ortarzewska M, Jankowski J, Nijakowski K. Composite Dust Toxicity Related to Restoration Polishing: A Systematic Review. Journal of Composites Science. 2025; 9(2):90. https://doi.org/10.3390/jcs9020090

Chicago/Turabian Style

Kucharska, Kamila, Anna Lehmann, Martyna Ortarzewska, Jakub Jankowski, and Kacper Nijakowski. 2025. "Composite Dust Toxicity Related to Restoration Polishing: A Systematic Review" Journal of Composites Science 9, no. 2: 90. https://doi.org/10.3390/jcs9020090

APA Style

Kucharska, K., Lehmann, A., Ortarzewska, M., Jankowski, J., & Nijakowski, K. (2025). Composite Dust Toxicity Related to Restoration Polishing: A Systematic Review. Journal of Composites Science, 9(2), 90. https://doi.org/10.3390/jcs9020090

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