Clinicians frequently prescribe splints to manage temporomandibular disorders, bruxism, and complex rehabilitations. However, daily maintenance protocols directly influence the structural integrity of materials for occlusal devices. Patients routinely apply mechanical brushing and commercial cleansing solutions to eliminate oral biofilm. Unfortunately, inappropriate cleaning regimens cause surface degradation, which compromises device longevity and promotes microbial colonisation. Consequently, understanding material responses to different cleaning agents remains essential for successful prosthetic management.

Evaluating Modern Materials for Occlusal Devices

Today, prosthodontists choose from diverse manufacturing workflows when designing interocclusal appliances. Traditional techniques rely on microwave-polymerized or heat-cured polymethyl methacrylate resins. Conversely, digital dentistry now incorporates computer-aided manufacturing with milled PMMA blocks and additive three-dimensional printing resins. Each processing pathway produces a distinct microstructural density and degree of monomer conversion. Consequently, these manufacturing methods exhibit varying vulnerabilities when patients subject them to routine hygiene measures.

A recent laboratory investigation methodically evaluated how multiple brushing solutions alter these three common dental substrates. Specifically, researchers fabricated one hundred and eighty standardized cylindrical specimens across milled PMMA, 3D-printed resin, and microwave-polymerized acrylic groups. They subjected the specimens to rigorous mechanical brushing simulations using distilled water, neutral detergent, conventional toothpaste, and specialized acrylic brushing gel. The investigators subsequently measured surface roughness and Vickers microhardness before and after testing. Ultimately, comparative data confirmed that pre-polymerized CAD/CAM milled blocks provide far superior baseline hardness and structural resilience compared to both printed resins and microwave-polymerized polymers.

Comparing Milling, 3D Printing, and Microwave Polymerization

The physical properties of occlusal appliances depend heavily on the polymerization mode. Industrial high-pressure manufacturing produces milled PMMA blanks under strictly controlled thermodynamic conditions. Therefore, these blocks demonstrate exceptionally high molecular weight, uniform cross-linking, and minimal residual monomer content. In contrast, additive manufacturing constructs 3D-printed devices through sequential photopolymerization of liquid resin layers. Although this additive technique offers superb dimensional precision and rapid fabrication, it frequently leaves unreacted monomers and microscopic interfaces between strata.

Similarly, microwave-polymerized acrylic resins show variable conversion rates depending on processing parameters and flask temperatures. During simulated brushing, milled specimens consistently preserved their microstructural integrity across every experimental solution. Meanwhile, additive resin specimens exhibited measurable surface vulnerabilities, particularly when exposed to abrasive mechanical challenges. Microwave-cured resins demonstrated intermediate performance, maintaining stable hardness yet suffering elevated roughness under harsh conditions. Thus, clinicians must recognize that processing technology directly governs how appliances withstand everyday patient maintenance.

Impact of Cleansing Solutions on Surface Roughness

Surface roughness represents a pivotal biological parameter in dental appliance longevity. Whenever average roughness exceeds the critical threshold of 0.20 micrometers, bacterial adhesion increases dramatically. Consequently, rough surfaces accelerate the formation of stubborn microbial biofilms and Candida albicans colonization. In this investigation, simulated brushing with conventional toothpaste caused significant increases in surface roughness across all three material categories. The abrasive particles within standard dentifrice aggressively scarred the resin surfaces, creating microgrooves and irregular topographies.

In contrast, mechanical brushing using distilled water, neutral detergent, or dedicated acrylic brushing gel resulted in minimal alterations. Neutral detergent and specialized gels maintained smooth finishes that closely matched baseline values. Furthermore, milled PMMA preserved the lowest overall roughness values throughout the simulated brushing cycles. Printed resins, however, developed greater surface irregularity after abrasive exposure. Therefore, dental practitioners must caution patients against using regular abrasive toothpastes on their splints. Instead, patients should use non-abrasive detergents or formulated cleaning gels to prevent pathogenic biofilm accumulation.

Microhardness Stability and Toothpaste Abrasiveness

Surface microhardness reflects a material's capacity to resist localized plastic deformation and surface wear. In the evaluated study, milled PMMA exhibited the highest Vickers microhardness values under all testing conditions. Moreover, microhardness remained remarkably stable after brushing for most material and solution combinations. However, the 3D-printed resin group suffered a statistically significant reduction in Vickers microhardness when brushed with conventional toothpaste. The abrasive slurry rapidly eroded the outer polymer layer of the photopolymerized specimens.

Because printed resins possess a lower degree of double-bond conversion and lower cross-linking density, mechanical abrasion readily damages their surface matrices. In contrast, neutral detergents and dedicated brushing gels preserved baseline microhardness completely across all resin types. Similarly, microwave-polymerized resins maintained stable hardness profiles despite undergoing minor superficial abrasion. These findings demonstrate that chemical formulation and particle abrasiveness interact directly with polymer microstructure. Consequently, using abrasive dentifrice on photopolymerized splints significantly degrades mechanical properties over time, predisposing the appliance to premature clinical wear.

Clinical Recommendations for Preserving Device Longevity

These laboratory findings offer immediate practical guidance for everyday dental practice. First, clinicians should select manufacturing materials that match the planned duration and mechanical demands of therapy. For long-term bruxism management, milled PMMA blocks clearly represent the most wear-resistant and structurally stable option. Although 3D-printed appliances provide remarkable efficiency and lower production costs, clinicians must prescribe tailored maintenance protocols to safeguard their longevity.

Specifically, dental teams should educate every patient on appropriate home care regimens. Patients must strictly avoid abrasive whitening or tartar-control toothpastes during daily splint hygiene. Instead, clinicians should instruct individuals to clean their appliances using soft-bristled brushes combined with neutral liquid detergents or pH-neutral brushing gels. In addition, chemical effervescent soaking tablets provide effective antimicrobial action without causing abrasive mechanical trauma. Regular recall appointments allow practitioners to inspect the splint surface, polish minor defects, and reinforce hygiene instructions. By implementing evidence-based hygiene guidelines, dentists can prevent microbial colonization, protect oral tissues, and ensure optimal long-term treatment outcomes.

Frequently Asked Questions

Can patients use standard dentifrice to clean materials for occlusal devices?

Clinicians should advise patients against using standard dentifrice for cleaning appliances. Conventional toothpastes contain abrasive silica or calcium carbonate particles designed to scour hard dental enamel. Consequently, these abrasives rapidly scratch softer acrylic resins and photopolymerized materials. The resulting microgrooves elevate surface roughness above the threshold for microbial adhesion, promoting plaque retention and fungal colonization. Therefore, patients should clean devices using non-abrasive liquid soap or designated brushing gels.

Why does milled PMMA demonstrate superior surface microhardness compared to 3D-printed resin?

Milled polymethyl methacrylate blanks undergo industrial polymerization under extreme heat and high pressure. This controlled manufacturing process creates extensive polymer cross-linking and eliminates unreacted monomers. In contrast, 3D printing relies on layer-by-layer photopolymerization, which often yields lower polymer conversion and minor structural voids. As a result, milled PMMA possesses superior microhardness and dense resistance to surface abrasion. Toothpaste brushing significantly degrades the hardness of 3D-printed resins while leaving milled blocks unaffected.

What maintenance protocol effectively disinfects occlusal splints without causing surface degradation?

Dental practitioners recommend a dual-action hygiene regimen to disinfect occlusal splints effectively without causing mechanical damage. Patients should gently brush the appliance daily using a soft toothbrush alongside lukewarm water and neutral detergent. Furthermore, patients should regularly immerse the appliance in specialized effervescent cleansing solutions or mild antimicrobial baths. This chemical immersion removes biofilm and pathogenic microorganisms without scratching resin surfaces. Consequently, patients preserve the initial polish, prevent bacterial colonization, and prolong appliance durability.

Disclaimer: This content is for informational and educational purposes only... Refer to the latest local and national guidelines for clinical practice.

References

1. de Aragao Junior EX et al. Surface alterations in materials for occlusal devices subjected to simulated brushing with different solutions. J Prosthet Dent. 2026 Oct 09. doi: undefined. PMID: 42855388.
2. Arreaza C, Seghi RR, Schricker SR, Johnston WM, Saponaro PC. Comparison of wear behavior of occlusal device materials manufactured by different processes. J Prosthet Dent. 2026;135(3):614.e1-614.e7.
3. Santos LTP, Gonçalves NMF, Silva CML, Sousa PVS, Tôrres Neto AJ, Borges ALS, et al. Surface and microhardness alterations of denture materials following exposure to gastric juice. Braz Dent Sci. 2026;29:e5143.
4. Bollen CM, Lambrechts P, Quirynen M. Comparison of surface roughness of oral hard materials to the threshold surface roughness for bacterial plaque retention: a review of the literature. Dent Mater. 1997;13(4):258-269.