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Open research questions in Dental materials and restorations

352 unresolved questions extracted from the limitations and future-work sections of 9,612 Dental materials and restorations papers in our library. Each links back to the study that raised it.

What the literature leaves open

  • Given the limitations of this study, the following conclusions can be drawn: ARTICLE IN PRESS ARTICLE IN PRESS ACCEPTED MANUSCRIPT - Ultrasound application to sound dentin before adhesive placement improved the adhesion of the universal adhesives evaluated.

    Ultrasound pretreatment of dentin enhances the adhesion of universal adhesives · 2026 · DOI

  • The findings of this study underscore the need for further research on the marginal sealing properties of the IDS technique using larger sample sizes and different resin materials.

    Assessing the Impact of Immediate and Delayed Dentin Sealing on Microleakage of Ceramic Onlays: An In-Vitro Study · 2026 · DOI

  • To our knowledge, no data are available regarding the effect of incorporating NC to CH as intra- canal medicament on POBS of AHP or NSF sealers.

    Influence of calcium hydroxide/nano-chitosan as intracanal medication on push-out bond strength of epoxy resin and bioceramic sealers: an ex-vivo study · 2026 · DOI

  • Although various nanoparticles have been incorporated into maxillofacial silicone elastomers to improve mechanical and antimicrobial performance, the cytocompatibility of BNP-modified systems remains insufficiently investigated.

    Cytocompatibility of boron nanoparticle-modified maxillofacial silicone elastomers: an in vitro study · 2026 · DOI

  • Within the limitations of this study, it can be concluded that three-body wear simulation significantly degrades the surface roughness and microhardness of CAD/CAM materials, with the degree of degradation being highly material-dependent and significantly correlates to its baseline microhardness.

    Effect of three-body wear on the surface properties of different polymer-based CAD/CAM dental restorative and prosthetic materials · 2026 · DOI

  • • All specimens were made and examined under optimal in vitro settings, which might not accurately reflect clinical situations. • Only marginal gaps were measured; internal gaps were not assessed due to the need for cementation and sectioning.

    Surface treatments and thermocycling effects on the fracture resistance and marginal adaptation of veneering systems on yttrium stabilized tetragonal zirconia polycrystal: An In-vitro study · 2026 · DOI

  • While this systematic review is informative, se- veral limitations should be considered. The existing evidence base is limited by the small number of hi- gh-quality randomized controlled trials testing sili- cone-based resilient denture liners. There is signifi- cant heterogeneity in study design, sample size, follow-up period, and outcome measurement methods, which makes direct comparison between studies challenging. Furthermore, the absence of in- ternationally standardized assessment tools for quantifying patient-reported and masticatory func- tion outcomes limits the ability to aggregate quanti- tative data consistently. Differences in liner material, manufacturing method, and patient adaptation periods add additio- nal sources of potential bias. Moreover, the short- to medium-term follow-up of most included studies re- stricts investigation of the long-term functional sta- bility, durability, and resistance of silicone-based li- ners. The subjective nature of several patient- reported outcome measures also adds variability, which could affect the generalizability of the results. The literature search was completed on Septem- ber 30, 2023, and was not updated before final ma- nuscript revision. Therefore, randomized controlled trials published after this date may not have been captured, and the findings should be interpreted as reflecting the evidence available up to September 2023. Future studies should address these limitations by using standardized procedures, validated outco- me measures, longer follow-up periods, and larger and more heterogeneous patient populations. Im- proved methodology is needed to enhance the qua- 223 lity of evidence and the clinical relevance of silico- ne-based resilient denture liners. CONCLUSION Within the limitations of the available randomi- zed controlled trials, silicone-based resilient dentu- re liners appear to offer potential benefits in increa- sing maximum bite force, reducing pain during mastication, and improving patient-reported com- fort in complete denture wearers. Evidence regar- ding objective masticatory performance remains inconsistent. Given the limited number of studies, methodolo- gical variability, and absence of meta-analysis, these findings should be interpreted cautiously. Further well-designed randomized trials with standardized outcome measures and longer follow-up periods are required to clarify the magnitude and consistency of functional benefits.

    Effectiveness of silicone-based resilient denture liners on masticatory function - a systematic review of randomized controlled trials · 2026 · DOI

  • into the optimal surface treatment conditions for bonding is warranted to establish more generalizable conclusions. The development of next-generation VPP-fabricated crown materials and fabrication systems with enhanced mechanical and functional properties is warranted.

    Comparison of the mechanical and bonding properties of vat photopolymerization resin and resin composite blocks · 2026 · DOI

  • Additionally, further investigation into the microstructural interactions between alloy particles and the GIC matrix is warranted Conclusion Within the limitations of this in vitro study, alloy incorporation into glass ionomer cement (GIC) enhanced bond strength and durability compared to the control.

    Experimental and Finite Element Evaluation of Long-Term Bond Strength in Alloy-Modified Glass Ionomer Cement · 2026 · DOI

  • However, the potential elution of urethane dimethacrylate (UDMA) into saliva and its associated safety implications remain insufficiently investigated.

    Comparison of urethane dimethacrylate monomer elution between indirect composites when subjecting to thermocycling · 2026 · DOI

  • Clear aligner therapy (CAT) increasingly relies on composite-based attachments to improve force transmission and aligner retention, yet the role of flowable composite properties in clinical performance remains poorly understood.

    Rheological and Structural Evaluation of Dental Flowable Composites for Optimized Performance in Transparent Aligner Systems · 2026 · DOI

  • Within the limitations of this study and based on the reviewed evidence, the following key conclusions can be drawn: ● Deeper curing capability of bulk-fill RBCs permits bulk placement up to 4–5 mm without compromising poly- merization efficiency.

    A Narrative Review of the Material Properties, Clinical Efficacy, and Developmental Prospects of Bulk-Fill Resin-Based Composites · 2026 · DOI

  • The mean observation period was 14.07 ± 7.89 years in the present study, and the maximum was 31.66 years. Due to the long observation period of the present study and the small number of studies of similar length, comparability with the literature reviewed is limited. Moreover, there are only a few comparable studies that are dealing with DCR-RPDs with spark-eroded friction pins, and both are set at universi- ties [1–3, 12, 13]. Studies with a similarly long observation period are rare. Apart from the studies by Yoshino et al. and Prott et al., no other studies have reached a maximum obser- vation time that is as high [4, 5]. Apart from the methodological problems mentioned above, the study has many positive aspects. The prostheses were always manufactured in the same dental laboratory so that standardized restorations of comparable quality can be assumed. The initial treatment as well as the final fitting of the prostheses was always performed by the same practitio- ner, whereas follow-up measures were also carried out by other practitioners. Nevertheless, it should be noted that this could also be seen as a limitation of the study, given that the skills of both technician and dentist may have improved over the years, leading to variations in the quality of the dentures over time. Continuous and date-related data collec- tion was carried out regarding the manufacturing process, the follow-up examinations, and the necessary post-treat- ment measures within the private dental practice, thereby ensuring high data quality. However, due to the free choice of dentist or a temporary or permanent change of dentist, 100% data collection cannot be guaranteed. The statistical analysis considered potential influencing factors, with their effects on the survival of the DCR-RPDs- SEFPs and abutments being assessed using the Kaplan- Meier method and Cox regression. However, potential correlations and/or interactions between certain variables, as well as overlaps in specific aspects, could not be fully excluded, which represents a limitation of the study.

    Up to 30 years of clinical performance of double-crown-retained removable dental prostheses with spark-eroded friction pins placed in a general dental practice · 2026 · DOI

  • Key limitations include: (i) color estimation based on visual VITA 3D-Master assessment and conversion to CIE L*a*b*, combined with the use of the CIE76 (ΔE*ab) formula, which, while clinically pragmatic, does not replace direct spectrophotometric measurement and may introduce observer-dependent variability and reduced perceptual accuracy; (ii) time was not included as an inferential factor for ΔE due to incomplete representation across time levels, limiting statistical inference on the temporal evolution of color; (iii) clinically relevant oral challenges-thermal cycling, toothbrushing abrasion, acquired pellicle, and fluctuations in pH and staining-agent concentration-were not comprehensively modeled; and (iv) compressive testing was performed using disc-shaped specimens rather than standardized cylindrical specimens as recommended by ISO 4049; therefore, the mechanical results should be interpreted as comparative rather than absolute values. Future work should incorporate these aging components and assess in situ clinical performance under controlled diet, hygiene, and polishing conditions using longitudinal designs. Additionally, standardized mechanical testing approaches, such as biaxial or uniaxial flexural strength tests, should ODOVTOS-Int. J. Dent. Sc. | Online First, 2026 | ISSN: 2215-3411. 572 ODOVTOS-Int. J. Dent. Sc. | Online First, 2026 | ISSN: 2215-3411. 573 ODOVTOS-International Journal of Dental Sciences Molina-Gantiva et al: Color Change and Compressive Strength of Novel Single-Shade Composite Resins Exposed to Staining Beverages be incorporated to provide more robust and clinically relevant mechanical data. CONFLICT OF INTEREST: None.

    Color Change and Compressive Strength of Novel Single-Shade Composite Resins Exposed to Staining Beverages · 2026 · DOI

  • As an in vitro study, it cannot fully replicate the complex dynamics of the oral environment, including pH fluctuations and thermal cycling, and lacks long-term testing and assessment of how different adhesive systems affect the durability of the DME complex.

    Effect of deep marginal elevation with different intermediate materials on the fracture resistance of direct and indirect final composite restorations: an in vitro study · 2026 · DOI

  • This study employed two measurement instruments and varied the number of measurement points to provide com- plementary insights into marginal gap assessment. How- ever, some limitations should be considered. The study was conducted under in vitro conditions which cannot fully rep- licate clinical conditions such as saliva, blood, and patient compliance [34]. The crowns were assessed without luting agents which adds further clinical considerations. Although the crown preparations were originally performed by under- graduate dental students, the relatively small sample size of 24 limits the generalisability of the findings. Operator dependent variability was present using both measurement instruments. Stereomicroscopy required precise handling to avoid projection errors, while micro-CT relied on subjective thresholding and segmentation [27]. Measurements were performed by a single operator, eliminating inter-examiner variability but introducing potential single-examiner bias and susceptibility to measurement-order effects, such as fatigue or visual adaptation, particularly during prolonged stereomicroscopic assessment. Additionally, the use of mean marginal gap values per specimen may underestimate the magnitude of localised marginal discrepancies, as aver- aging circumferential measurements can obscure site-spe- cific extremes that may be relevant. The present study did not assess method agreement using correlation or Bland–Altman analysis, as it was not designed to evaluate interchangeability or proportional bias between measurement instruments. The absence of statistically sig- nificant differences in mean values should not be interpreted as evidence of measurement interchangeability or agree- ment, which would require dedicated agreement-based 1 3Clinical Oral Investigations (2026) 30:262 262 Page 10 of 11 analytical frameworks. Future studies designed to assess reproducibility through repeated measurements of identi- cal marginal locations would provide additional insight into instrument-specific variability and agreement. Although a post hoc sensitivity analysis was performed, the present study was not designed within an equivalence or non-inferiority framework with a prespecified clinically meaningful margin. Consequently, while no statistically significant differences in mean marginal gap values were detected, the sample size limits inference regarding whether smaller differences may exist between measurement instru- ments. The absence of statistical significance should there- fore be interpreted as an absence of detectable differences of the magnitude assessed, rather than confirmation of equivalence. Future investigations incorporating a priori equivalence thresholds and larger or repeated-measurement designs would be required to determine method equivalence within clinically acceptable limits. The methodological differences between software plat- forms may have influenced the outcomes. DataViewer (used for the 12 point micro-CT analysis) imposed a higher detec- tion threshold compared with ImageJ-based processing (used for the 360 point analysis) and may therefore have contributed to inflated marginal gap values [27]. Stereomi- croscopy provides a two-dimensional external assessment, whereas micro-CT offers both 2D and 3D evaluation [35]. This study did not account for the three-dimensional nature of marginal adaptation, including contour discrepancies and internal fit, which may affect MG measurements and clinical outcomes [36]. Future research should address these limitations by transitioning to in vivo investigations. Incor- porating multiple operators, standardized measurement pro- tocols, and comprehensive three-dimensional analyses will strengthen reliability.

    Comparative evaluation of marginal gaps of lithium disilicate crowns measured using stereomicroscopy and micro‑computed tomography · 2026 · DOI

  • Accordingly, the Page 35 of 48 F1000Research 2026, 14:894 Last updated: 14 MAY 2026 conclusions have been revised to be more cautious and limited to the interpretation of laboratory-based material performance.

    Fracture resistance of nanocomposite 3D-printed resins designated for teeth fabrication: An in vitro analysis before and after thermal aging · 2026 · DOI

  • This study addresses a critical gap in understanding the durability of ocular prostheses by investigated the surface roughness and color stability of ocular prostheses fabricated using three‐dimensional (3D) printing and heat‐cured polymethyl methacrylate (PMMA) acrylic resin (QC‐20 heat polymerize) after they were subjected to artificial weathering.

    Color Stability and Roughness of Ocular Prosthesis Between Heat‐Cured Acrylic and 3D Printed Acrylic After Artificial Weathering · 2025 · DOI

  • The results warrant further investigation of nanoAg-ACP microparticles as fillers for orthodontic adhesives using more clinically relevant in vitro models to confirm their potential clinical application in orthodontic treatments.

    Effects of Bioactive <scp>NanoAg</scp>‐<scp>ACP</scp> Microparticles on the Bond Strength of a Commercial Orthodontic Adhesive and Enamel Resistance to Demineralization · 2025 · DOI

  • Furthermore, functionally graded additive manufacturing (FGAM), a potential direction for AM, enables the realization of biomimetic structures, such as natural teeth; however, specific studies are currently lacking.

    Additive manufacturing of dental ceramics in prosthodontics: The status quo and the future · 2024 · DOI

  • CONCLUSION: Within the limitations of this study, conventionally processed RPD groups exhibited better overall fit accuracy post-finishing and polishing.

    Effect of finishing and polishing techniques on the fit accuracy and dimensions of conventional and CAD‐CAM removable partial denture frameworks · 2024 · DOI

  • CLINICAL RELEVANCE: Since comparable evidence between 3D-printable and millable CAD/CAM dental hybrid materials is scarce, the present study gives clear guidance for pretreatment planning on different materials.

    Effect of surface treatment strategies on bond strength of additively and subtractively manufactured hybrid materials for permanent crowns · 2024 · DOI

  • CONCLUSION: Within the limitations of this study, it can be deduced that PEEK is a feasible substitute for zirconia when used in conjunction with indirect composite for the fabrication of dental prostheses.

    Comparative evaluation of bond strength and color stability of polyetheretherketone and zirconia layered with indirect composite before and after thermocycling: An in vitro study · 2024 · DOI

  • However, the application of BAG in bonding agents and its impact on bond strength remain uncertain due to insufficient information and limited research in this area.

    Effect of bioactive glass-containing dentin adhesives on microshear bond strength of composite restorations · 2023 · DOI

  • The literature has shown that incorporating nanoparticles in dental materials in different specialties could have a positive effect on reinforcing the mechanical properties of those materials; however, there was no consensus on the effectiveness of using nanoparticles in enhancing the mechanical properties of dental materials, due to the variety of the properties of nanoparticles itself and their effect on the mechanical properties.

    Influence of inorganic nanoparticles on dental materials’ mechanical properties. A narrative review · 2023 · DOI

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352 open questions have been extracted from the limitations and future-work passages of 9,612 Dental materials and restorations papers in our library. Each one below links back to the study that raised it, so you can read the original claim in context.

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