# Mechanobehavior distinguishes mandibular growth differences in two facial types

> **NIH NIH R01** · OREGON HEALTH & SCIENCE UNIVERSITY · 2022 · $567,812

## Abstract

In the United States, >9% of children are orthodontic patients who are treated for crooked teeth and jaw
discrepancies known as malocclusions (AAO, 2017). Costs for this treatment are >$9.5 billion annually (Guay
et al. 2008; Laniado et al. 2017). Management of jaw growth via dentofacial orthopedics is indicated in >30% of
orthodontic patients but 13-36% of mandibular growth enhancement therapies fail to correct the malocclusion
(Hedlund and Feldmann 2016; O'Brien et al. 2003). Hence, the costs of poor results are considerable.
Orthopedic therapies for mandibular enhancement try to promote growth of the load-sensitive secondary
cartilages of the jaw through changes in temporomandibular joint (TMJ) loading mechanics and behaviors.
Mandibular growth is expected to be less in amount and expressed more vertically (Buschang et al. 2017;
Karlsen 1997) with poorer prognoses for orthopedic therapies in children with dolichofacial (long-narrow)
compared to brachyfacial (short-wide) phenotypes (Deen and Woods 2015; Pancherz and Michailidou 2004;
Rogers et al. 2018). However, differences in the TMJ loading mechanics and behaviors (mechanobehavior) in
these phenotypes during growth and treatment are unknown. The broad, long-term goals of this research are
to provide evidence-informed dentofacial orthopedic therapies with predictable results. Thus, this application
proposes a prospective observational study in selected populations of dolichofacial and brachyfacial children
before, during and after orthodontic treatment. This study will contribute to the mission of improving dental,
oral, and craniofacial health by addressing three Specific Aims:
1. Test the hypothesis that dolichofacial compared to brachyfacial children have energy densities (energy input
 per volume of cartilage, mJ/mm3) that are significantly larger for the same jaw tasks and, thus, limit
 mandibular growth earlier.
2. Test the hypothesis that dolichofacial compared to brachyfacial children have duty factors (% time of jaw
 muscle activity/total recording time) that are significantly smaller and, thus, promote less mandibular growth
 per year.
3. Test the hypothesis that phenotypic dentofacial subgroups exist, differentiated by mechanobehavior scores
 ((energy densities)2 X duty factors) that correspond with significant differences in mandibular growth.
Longitudinal clinical treatment records and data collected via validated techniques, including numerical
modeling, dynamic stereometry, and laboratory and in-field electromyography, will be used to compare
mechanobehavior variables between phenotypes and test if these variables predict mandibular growth as
indicated by ramus height. The novel outcomes of this research will be critical foundations for future clinical
approaches that modify mechanobehavior to achieve more successful and predictable orthopedic therapies in
children with jaw discrepancies.

## Key facts

- **NIH application ID:** 10449217
- **Project number:** 5R01DE028548-04
- **Recipient organization:** OREGON HEALTH & SCIENCE UNIVERSITY
- **Principal Investigator:** Laura R Iwasaki
- **Activity code:** R01 (R01, R21, SBIR, etc.)
- **Funding institute:** NIH
- **Fiscal year:** 2022
- **Award amount:** $567,812
- **Award type:** 5
- **Project period:** 2019-08-01 → 2024-07-31

## Primary source

NIH RePORTER: https://reporter.nih.gov/project-details/10449217

## Citation

> US National Institutes of Health, RePORTER application 10449217, Mechanobehavior distinguishes mandibular growth differences in two facial types (5R01DE028548-04). Retrieved via AI Analytics 2026-05-24 from https://api.ai-analytics.org/grant/nih/10449217. Licensed CC0.

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