Article
Dentistry, Oral Surgery & Medicine
Zixuan Zhou, Di Guo, David C. Watts, Nicholas G. Fischer, Jing Fu
Summary: C-factor is an index used to evaluate the relationship between cavity configuration and the development of polymerization shrinkage stress in dental restorations. However, its correlation with stress analysis remains controversial. C-factor is only applicable under low-rigid compliance and cannot accurately predict the shrinkage stress of restorations and the mechanical behavior of material-tooth interfaces.
Article
Multidisciplinary Sciences
Blend Hamza, Marcus Zimmerman, Thomas Attin, Tobias T. Taubock
Summary: This study compared the marginal integrity of bulk-fill and classical composite restorations in primary and permanent molars before and after thermo-mechanical loading. The high-viscous bulk-fill restorations showed similar marginal integrity to classical restorations in both primary and permanent molars, while the flowable bulk-fill restorations had the lowest marginal integrity among all restorations.
SCIENTIFIC REPORTS
(2022)
Article
Polymer Science
Akimasa Tsujimoto, Masao Irie, Erica Cappelletto Nogueira Teixeira, Carlos Alberto Jurado, Yukinori Maruo, Goro Nishigawa, Takuya Matsumoto, Franklin Garcia-Godoy
Summary: Flowable composite restorations, including new generation and bulk-fill variants, exhibit lower flexural properties and bond strengths immediately after polymerization compared to 24 hours later. Polymerization shrinkage and stress levels vary by material type, with bulk-fill composites showing notably lower values. Marginal adaptation and polymerization shrinkage appear to have a stronger correlation with shear bond strength to dentin than to enamel. Early-stage mechanical weaknesses must be considered when using flowable composites clinically, as polymerization shrinkage can still cause gaps and adaptation issues regardless of the composite type.
Article
Dentistry, Oral Surgery & Medicine
A. A. Oliveira, M. L. P. Ribeiro, P. V. M. Costa, R. D. Pereira, A. Versluis, C. Verissimo
Summary: CS values were higher at lingual cusp for Horizontal and NEDS techniques. No statistical difference was found for Bulk or Oblique techniques. Bulk showed lower CS values and more enamel cracks. DC was lower at 4 mm regardless of technique.
Article
Dentistry, Oral Surgery & Medicine
Peng Yu, Yong-Xiang Xu, Yu-Shu Liu
Summary: This study evaluated the polymerization shrinkage (PS) and shrinkage stress (SS) of bulk-fill resin-based composites (RBCs) and compared them with conventional non-bulk-fill RBCs. The results showed no significant differences in PS and SS between the bulk-fill RBCs and the conventional RBCs.
JOURNAL OF DENTAL SCIENCES
(2022)
Article
Engineering, Chemical
Masihullah Jabarulla Khan, Claudia Creighton, Russell J. Varley
Summary: This study investigates the shrinkage during cure of a rapid curing epoxy/cycloaliphatic amine system. A volumetric shrinkage model considering chemical shrinkage, thermal and physical changes, and cure conversion is proposed. The model provides a valuable tool for predicting shrinkage during cure and designing cure profiles to minimize residual stress.
INDUSTRIAL & ENGINEERING CHEMISTRY RESEARCH
(2022)
Article
Dentistry, Oral Surgery & Medicine
I-S Yoo, D. Kim, K. Kim, S-h Park
Summary: The aim of this study was to investigate the polymerization shrinkage forces of five different composite resins under different deflection modes. It was found that the shrinkage force was highest in zero-deflection mode, decreased as deflection increased, and was smallest in maximum-deflection mode. Additionally, a high negative correlation was observed between allowable deflection and shrinkage force in all materials.
OPERATIVE DENTISTRY
(2021)
Article
Dentistry, Oral Surgery & Medicine
Robert Taylor, Rodrigo Fuentealba, William W. Brackett, Howard W. Roberts
Summary: The study evaluated the 24-hour polymerization shrinkage of resin composite core materials. Results showed a wide volumetric shrinkage range, inconsistent shrinkage behavior, and all materials reaching maximum values before 24 hours. No significant difference was observed during proposed digital same day all ceramic crown procedures, but some differences were noted at 24 hours.
JOURNAL OF ESTHETIC AND RESTORATIVE DENTISTRY
(2021)
Article
Engineering, Biomedical
Parisa Amiri, Zahra Talebi, Dariush Semnani, Rouhollah Bagheri, Hossein Fashandi
Summary: Surface-modified nanofibers in dental composites can significantly enhance mechanical properties and color by forming semi-interpenetration network between nanofibers and resin matrix and achieving uniform distribution of nanofibers in the resin. However, increasing nanofiber content may lead to a decrease in mechanical properties of the composite materials.
JOURNAL OF MATERIALS SCIENCE-MATERIALS IN MEDICINE
(2021)
Article
Dentistry, Oral Surgery & Medicine
Hamad Algamaiah, Nikolaos Silikas, David C. Watts
Summary: The study found that PFill group with addition fragmentation chain transfer (AFCT) agent had significantly lower polymerization shrinkage rates compared to the comparator ECeram, regardless of the irradiation protocol. In contrast, the PFlow group exhibited comparable results to EFlow and ECeram under different irradiation protocols. Overall, PFill consistently showed lower shrinkage stress results than ECeram and were comparable for both high irradiance protocols.
Article
Polymer Science
Louis Hardan, Layla Sidawi, Murad Akhundov, Rim Bourgi, Maroun Ghaleb, Sarah Dabbagh, Krzysztof Sokolowski, Carlos Enrique Cuevas-Suarez, Monika Lukomska-Szymanska
Summary: This study evaluated the clinical performance of the Fast-Modelling Bulk Technique (FMBT) compared to the Composite-Up Layering Technique (CULT) in posterior cavities over one year. FMBT showed less postoperative sensitivity and more desirable results than CULT, with no significant difference in secondary caries, material fracture, and marginal adaptation. However, CULT resulted in more marginal staining compared to FMBT. Radiological examination indicated good marginal fit with FMBT during the first year.
Article
Dentistry, Oral Surgery & Medicine
Camilo Pulido, Cesar A. G. Arrais, Giovana Mongruel Gomes, Ana Paula G. B. Franco, Hypolito Jose Kalinowski, Andres Davila-Sanchez, Osnara Maria Mongruel Gomes
Summary: The study evaluated the shrinkage strain and hardness of conventional and self-adhesive resin luting agents in root canals, finding that the shrinkage kinetics and hardness of self-adhesive RLA may differ depending on the root third.
JOURNAL OF PROSTHETIC DENTISTRY
(2021)
Article
Polymer Science
Daisuke Miura, Yoshiki Ishida, Akikazu Shinya
Summary: The study investigated the polymerization shrinkage of short fiber reinforced composite (SFRC) and found that the aspect ratio of glass fiber filler has an influence on alleviating polymerization shrinkage stress.
Article
Engineering, Biomedical
Zonghua Wang, Xiaoran Zhang, Shuo Yao, Jiaxin Zhao, Chuanjian Zhou, Junling Wu
Summary: In this study, a novel low-shrinkage resin adhesive was synthesized by adding specific additives, which effectively reduced polymerization shrinkage and improved shear bond strength. The additives had no adverse effects on double bond conversion and cell toxicity.
JOURNAL OF THE MECHANICAL BEHAVIOR OF BIOMEDICAL MATERIALS
(2022)
Article
Polymer Science
Soren Schumacher, Sanwardhini Pantawane, Stephan Gekle, Seema Agarwal
Summary: The synthesis and polymerization behavior of four different monofunctional vinyl cyclopropane (VCP) derivatives were investigated. The study found that different VCPs have varying abilities to form hydrogen bonds in their side chains, leading to preorganization and potentially faster polymerization. Although VCPs capable of hydrogen bonding did not show significant differences, a general effect of hydrogen bonds on polymerization behavior was observed.
Article
Dentistry, Oral Surgery & Medicine
Mohammed Aldhafyan, Nikolaos Silikas, David C. Watts
Summary: The study aimed to investigate the effects of curing modes on the conversion degree and polymerization shrinkage of dual-cure resin cements. The results showed that light-cured specimens had higher conversion degree and lower shrinkage compared to self-cured specimens over specific post-activation periods. There was a positive correlation between conversion and shrinkage. The findings are significant for clinical selection of resin cement products.
Article
Dentistry, Oral Surgery & Medicine
Juergen Durner, Klaus Schrickel, David C. Watts, Marc Becker, Miriam E. Draenert
Summary: This study compared the elutable substances directly released from bulk-fill resin-based composites (BF-RBCs) with those indirectly released from teeth restored with a BF composite. In addition to (co)monomers, the study focused on other potentially toxic ingredients or impurities. The study also examined the barrier function of the residual dentin/adhesive layer.
Article
Dentistry, Oral Surgery & Medicine
Rua S. Babaier, Modi S. Aldeeb, Nick Silikas, David C. Watts
Summary: This study investigated the chemical composition, radiopacity, and correlation between radiopacity and specimen thickness of CAD/CAM restorative blocks and other resin-based materials. The results showed that the radiopacity of CAD/CAM materials was thickness-dependent, with polymer-infiltrated ceramics being fairly radiolucent. Therefore, there is a need to revisit the radiopacity requirements for CAD/CAM restorative materials.
Article
Dentistry, Oral Surgery & Medicine
Mohammed Aldhafyan, Nikolaos Silikas, David C. Watts
Summary: This study investigated the effect of two curing modes on the performance of dual-cure resin cements. After 30 days of water storage and 30 days of dry reconditioning, it was found that the resin elution, water sorption, and solubility were significantly higher in the self-cure mode compared to the light-cure mode. Light curing remains beneficial in reducing resin degradation and related properties.
Article
Dentistry, Oral Surgery & Medicine
Rua S. Babaier, Julfikar Haider, Abdulrahman Alshabib, Nick Silikas, David C. Watts
Summary: The mechanical properties of the three CAD/CAM composite materials were strongly influenced by the media and ageing process, with fibre-reinforced composites showing greater reductions in performance in 70%E/W and MEK.
Article
Dentistry, Oral Surgery & Medicine
A. Sadeghyar, S. Lettner, D. C. Watts, A. Schedle
Summary: The study aimed to investigate the effect of pretreatment of the dentin surface on the bond strengths of self-adhesive restorative materials and materials requiring pretreatment. The results showed that the bond strengths of the materials with pretreatment were significantly higher than the self-adhesive materials. Glass-ionomer cements without pretreatment were the only restoratives that experienced pretest failures. Among the materials without pretreatment, Surefil one had the highest bond strengths.
Article
Dentistry, Oral Surgery & Medicine
Jiawei Yang, Nick Silikas, David C. Watts
Summary: This study investigated the degree of conversion, maximum polymerization rate, polymerization shrinkage, maximum shrinkage rate, and fracture toughness of different types of bulk-fill composites, as well as the effect of viscosity reduction techniques.
Article
Dentistry, Oral Surgery & Medicine
Muataz A. Osman, Rasha A. Alamoush, Evgeny Kushnerev, Kevin G. Seymour, David C. Watts, Julian M. Yates
Summary: This study investigated the biological response of primary human gingival fibroblasts and keratinocytes to titanium surfaces with different levels of roughness. The results showed that keratinocytes had better growth on smooth surfaces, while fibroblasts had better growth on minimally rough and rough surfaces. Different surface roughness and exposure times had a significant effect on cell proliferation, and cytotoxicity was highest on day 3.
Article
Dentistry, Oral Surgery & Medicine
Markus Reise, Stefan Kranz, Andre Guellmar, Ralf Wyrwa, Tobias Rosenbaum, Juergen Weisser, Aileen Jurke, Matthias Schnabelrauch, Markus Heyder, David C. Watts, Bernd W. Sigusch
Summary: The aim of this study was to prepare resorbable polylactide fibers for periodontitis treatment using coaxial electrospinning, and to optimize the release of metronidazole (MNA) by reducing the initial burst effect. The results showed that the coaxial electrospun mats exhibited a retarded drug release compared to conventional fibers, and had a significantly higher antibacterial effect. The biocompatibility test also demonstrated that the coaxial mats had higher numbers of vital cells. These findings suggest that coaxial electrospun fibers can be potential drug delivery systems for local periodontitis treatment.
Article
Dentistry, Oral Surgery & Medicine
A. Franz, S. Lettner, D. C. Watts, A. Schedle
Summary: The study investigated the shear bond strengths and failure modes of four self-etch bonding agents on bovine dentin and enamel. Data analysis revealed that excluding cohesive failure specimens affected the evaluation of shear bond strengths, with OBXTR adhesive showing significantly lower strengths on dentin substrate.
Article
Dentistry, Oral Surgery & Medicine
Alaaeldin Elraggal, Rania. R. Afifi, Rasha A. Alamoush, Islam Abdel Raheem, David C. Watts
Summary: The effect of acidic media on the flexural strength and fatigue of CAD-CAM materials was investigated. Different materials were immersed in various media and their surface topography and roughness were analyzed. The results showed that the erosive media changed the surface roughness of the materials but did not compromise their flexural strength. Moreover, resin composite and hybrid ceramic were more resistant to cyclic fatigue compared to other materials.
Article
Dentistry, Oral Surgery & Medicine
Pietro Ausiello, Alessandro Espedito Di Lauro, Joao Paulo Mendes Tribst, David C. Watts
Summary: This study aimed to evaluate the influence of new resin-based CAD-CAM implant-supported materials on posterior crown restoration stress and strain concentrations. The finite element analysis revealed differences in stress distribution among different resin materials. The Estelite P Block material showed lower tensile and shear stresses compared to other resin-based materials.
Article
Dentistry, Oral Surgery & Medicine
Rua Babaier, Julfikar Haider, Nick Silikas, David C. Watts
Summary: This study investigated potential variations in polymerisation of light-and dual-cured resin cements photoactivated through four CAD/CAM restorative materials as a function of substrate thickness. The results showed that increasing substrate thickness reduced energy delivery to the luting cements and significantly affected the hardness of the cement discs. However, there was only a slight reduction in degree of conversion.
Article
Dentistry, Oral Surgery & Medicine
S. Kranz, M. Heyder, U. Rabe, P. Liu, A. Mrozinska, A. Guellmar, A. Berg, D. Steen, J. Tuckermann, David C. Watts, Bernd Sigusch, M. Reise
Summary: This study aimed to investigate the osseointegration and bone formation of two different polymeric biomaterials in an ovine model. The results showed that both biomaterials exhibited good osseointegration and bone formation characteristics, making them suitable for further examination in periodontal regeneration studies.
Review
Dentistry, Oral Surgery & Medicine
David C. Watts
Summary: This review focuses on the underlying science and technology of light curing in dental resin-based composites. It discusses the particle-wave understanding of light, the penetration ability of photons into bulk fill composites, the technology of LED light-curing units, and the criteria for absorption of photons by photo initiators. The implications for clinical practice, including design variables, selection criteria for LED-LCUs, and guidelines for their use, are also examined to ensure safe and effective light-curing procedures.
FRONTIERS IN DENTAL MEDICINE
(2023)