# Dental Composites from Photoresponsive Addition-Fragmentation Filler Particles

> **NIH NIH F31** · UNIVERSITY OF COLORADO · 2020 · $41,031

## Abstract

Project Summary.
 The proposed research involves the development of crosslinked organic filler particles and surface-
modified inorganic fillers that are functionalized with radical addition-fragmentation chain transfer (AFT)
moieties for stress reduction in dental restorative composites. Although there have been significant advances in
the design of functionalized inorganic fillers and addition of AFT monomers to the resin (polymerizable) phase,
stress development during polymerization is still a significant issue in dental restoratives that can lead
microcracking of the composite, delamination from the tooth, or even tooth fracture. The design of functional,
crosslinked AFT-based particles and subsequent implementation into classic dental resins will enable covalent
bond rearrangement within the filler particle to relax stress as it develops. Similarly, incorporation of AFT
moieties onto the surface of inorganic fillers is an additional method to introduce dynamic chemistry to the filler
phase while maintaining the same mechanical properties of the resin.
 The purposed research will address stress concentration on the filler and filler/resin interface by taking
advantage the Covalent Adaptable Networks (CANs) paradigm. This approach replaces the static bonds that
normally exist in a crosslinked network with dynamic bonds that rearrange to a lower stress state in the presence
of proper activating species. In the case of AFT, the activating species are free radicals, which are also the active
species during the photopolymerization of the dimethacrylate based resins used in most dental restorative
composites. The first aim is to develop AFT particles that reduce stress development both during polymerization
and upon external loading of classic glassy systems, then implement these particles directly as an additive to
standard dental resin formulations and study their effect on the stress behavior. Next, we will develop AFT
organic/inorganic nanocomposite particles with functionalized silica nanoparticles to circumvent limitations
such as resin viscosity and modulus of the composite. The second aim is to functionalize silica nanoparticles
with AFT moieties to enable bond exchange only at the filler/matrix interface without maintaining the
mechanical properties of the final composite. We will then incorporate the both the organic AFT particles and
the functionalized to investigate possible synergistic effects of both particle types in a dental composite.
 To accomplish these goals, the purposed training plan will enable trainee to interact with mentors and
learn from their technical and practical experience with dental materials. The selected mentoring committee has
extensive experience with synthesis, characterization of polymeric dental materials, and clinical implementation,
and industrial considerations. The trainee will receive relevant and meaningful training in research-oriented
areas and conducting research both thoughtfully and ethically.

## Key facts

- **NIH application ID:** 9886076
- **Project number:** 5F31DE027861-03
- **Recipient organization:** UNIVERSITY OF COLORADO
- **Principal Investigator:** Nick Bongiardina
- **Activity code:** F31 (R01, R21, SBIR, etc.)
- **Funding institute:** NIH
- **Fiscal year:** 2020
- **Award amount:** $41,031
- **Award type:** 5
- **Project period:** 2018-05-01 → 2021-04-30

## Primary source

NIH RePORTER: https://reporter.nih.gov/project-details/9886076

## Citation

> US National Institutes of Health, RePORTER application 9886076, Dental Composites from Photoresponsive Addition-Fragmentation Filler Particles (5F31DE027861-03). Retrieved via AI Analytics 2026-05-24 from https://api.ai-analytics.org/grant/nih/9886076. Licensed CC0.

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