Exposure to adversity can accelerate biological aging. However, existing biomarkers of early aging are either costly and difficult to collect, like epigenetic signatures, or cannot be detected until late childhood, like pubertal onset. We evaluated the hypothesis that early adversity is associated with earlier molar eruption, an easily assessed measure that has been used to track the length of childhood across primates. In a preregistered analysis ( n = 117, ages 4 to 7 y), we demonstrate that lower family income and exposure to adverse childhood experiences (ACEs) are significantly associated with earlier eruption of the first permanent molars, as rated in T2-weighted magnetic resonance images (MRI). We replicate relationships between income and molar eruption in a population-representative dataset (National Health and Nutrition Examination Survey; n = 1,973). These findings suggest that the impact of stress on the pace of biological development is evident in early childhood, and detectable in the timing of molar eruption.

It is critical for dentists to identify and differentiate primary and permanent teeth, fillings, dental restorations and areas with pathological findings when reviewing dental radiographs to ensure that an accurate diagnosis is made and the optimal treatment can be planned. Unfortunately, dental radiographs are sometimes read incorrectly due to human error or low-quality images. While secondary or group review can help catch errors, many dentists work in practice alone and/or do not have time to review all of their patients' radiographs with another dentist. Artificial intelligence may facilitate the accurate interpretation of radiographs. To help support the review of panoramic radiographs, we developed a novel collaborative learning model that simultaneously identifies and differentiates primary and permanent teeth and detects fillings. We used publicly accessible dental panoramic radiographic images and images obtained from the University of Missouri-Kansas City, School of Dentistry to develop and optimize two high-performance classifiers: (1) a system for tooth segmentation that can differentiate primary and permanent teeth and (2) a system to detect dental fillings. By utilizing these high-performance classifiers, we created models that can identify primary and permanent teeth (mean average precision [mAP] 95.32 % and performance [F-1] 92.50 %), as well as their associated dental fillings (mAP 91.53 % and F-1 91.00 %). We also designed a novel method for collaborative learning that utilizes these two classifiers to enhance recognition performance (mAP 94.09 % and F-1 93.41 %). Our model improves upon the existing machine learning models to simultaneously identify and differentiate primary and permanent teeth, and to identify any associated fillings. Human error can lead to incorrect readings of panoramic radiographs. By developing artificial intelligence and machine learning methods to analyze panoramic radiographs, dentists can use this information to support their radiograph interpretations, help communicate the information to patients, and assist dental students learning to read radiographs.

Objectives: Skeletal malocclusions are common, and severe malocclusions are treated by invasive surgeries. Recently, jaw bone length has been shown to be developmentally controlled by osteoclasts. Our objective was to determine the effect of inhibiting osteoclast‐secreted proteolytic enzymes on lower jaw bone length of avian embryos by pharmacologically inhibiting matrix metalloproteinase‐9 (MMP9) or cathepsin K (CTSK).Methods: Quail (Coturnix coturnix japonica) embryos were given a single dose of an inhibitor of MMP9 (iMMP9), an inhibitor CTSK (iCTSK), or vehicle at a developmental stage when bone deposition is beginning to occur. At a developmental stage when the viscerocranium is largely calcified, the heads were scanned via micro‐computed tomography and reproducible landmarks were placed on 3D‐reconstructed skulls; the landmark coordinates were used to quantify facial bone dimensions.Results: Approximately half of the quail given either iMMP9 or iCTSK demonstrated an overt lower jaw phenotype, characterized by longer lower jaw bones and a greater lower to upper jaw ratio than control embryos. Additionally, iMMP9‐treated embryos exhibited a significant change in midface length and iCTSK‐treated embryos had significant change in nasal bone length.Conclusion: MMP9 and CTSK play a role in osteoclast‐mediated determination of lower jaw bone length. Pharmacological inhibition of MMP9 or CTSK may be a promising therapeutic alternative to surgery for treating skeletal jaw malocclusions, but more preclinical research is needed prior to clinical translation.

Summary: Sex is a biological variable important to consider in all biomedical experiments. However, doing so in avian embryos can be challenging as sex can be morphologically indistinguishable. Unlike humans, female birds are the heterogametic sex with Z and W sex chromosomes. The female‐specific W chromosome has previously been identified in chick using a species‐specific polymerase chain reaction (PCR) technique. We developed a novel reverse transcription quantitative PCR (RT‐qPCR) technique that amplifies the W chromosome gene histidine triad nucleotide‐binding protein W (HINTW) in chick, quail, and duck. Accuracy of the HINTW RT‐qPCR primer set was confirmed in all three species using species‐specific PCR, including a novel quail‐specific HINTW PCR primer set. Bone development‐related gene expression was then analyzed by sex in embryonic lower jaws of duck and quail, as adult duck beak size is known to be sexually dimorphic while quail beak size is not. Trends toward sex differences were found in duck gene expression but not in quail, as expected. With these novel RT‐qPCR and PCR embryo sexing methods, sex of chick, quail, and duck embryos can now be assessed by either/both RNA and DNA, which facilitates analysis of sex as a biological variable in studies using these model organisms.

Mastication plays an important role in effective food digestion and nutrient absorption. Therefore, regulating masticatory force in people with declining mastication function is significant for maintaining health and quality of life. In this study, we tested the effect of tactile augmentation on mastication force. To augment tactile feedback during mastication, we applied closed-loop electrical stimulation onto the mandibular vestibule using an intraoral tooth-borne electronic system. We hypothesized that closed-loop electrical stimulation, timed with mastication and applied to the nerves delivering tactile feedback to the brain, would evoke an increase in masticatory force. Experiments were completed using the intraoral system with six healthy human subjects who masticated soft and hard foods with and without stimulation during the experiment. Their mastication forces were recorded ten times per condition. The recorded mastication force profile showed that mastication force was higher with the harder food. Also, mastication force increased when electrical stimulation was applied, compared to the non-stimulated condition. These results support the hypothesis that tactile augmentation by intraoral closed-loop electrical stimulation will increase masticatory force. Other mastication parameters including period, spike width, and duty cycle are also changed by electrical stimulation. Further, stimulation left a strong aftereffect on these mastication parameters.