Smaller Jaw Research Articles

Early evolution of small body size in Homo floresiensis

Recent discoveries of Homo floresiensis and H. luzonensis raise questions regarding how extreme body size reduction occurred in some extinct Homo species in insular environments. Previous investigations at Mata Menge, Flores Island, Indonesia, suggested that the early Middle Pleistocene ancestors of H. floresiensis had even smaller jaws and teeth. Here, we report additional hominin fossils from the same deposits at Mata Menge. An adult humerus is estimated to be 9 − 16% shorter and thinner than the type specimen of H. floresiensis dated to ~60,000 years ago, and is smaller than any other Plio-Pleistocene adult hominin humeri hitherto reported. The newly recovered teeth are both exceptionally small; one of them bears closer morphological similarities to early Javanese H. erectus. The H. floresiensis lineage most likely evolved from early Asian H. erectus and was a long-lasting lineage on Flores with markedly diminutive body size since at least ~700,000 years ago.

Ecomorphological variation of pumpkinseed sunfish (Lepomis gibbosus) in exposed littoral shoreline habitat of a postglacial lake

The spatial distribution of phenotypes across the environment has important consequences for population biology, community ecology, and evolution. Populations of pumpkinseed sunfish (Centrarchidae: Lepomis gibbosus) have repeatedly diversified between the littoral and pelagic habitats of postglacial lakes, but we know little about the natural history of pumpkinseed in exposed rocky littoral shorelines relative to those in sheltered littoral bays. We addressed three general questions with respect to the pumpkinseed found in exposed littoral shoreline relative to conspecifics from sheltered littoral and pelagic habitats: (1) What phenotype is associated with the exposed littoral shoreline? (2) What is their summer diet? (3) What is the condition of pumpkinseed from exposed littoral shorelines? Reference sheltered littoral and pelagic pumpkinseed were phenotypically and ecologically differentiated in a pattern consistent with several previous studies; pelagic pumpkinseed had deeper bodies, smaller jaws (narrower oral jaw width and shorter premaxilla), and a more terminal mouth, as well as having more zooplankton and less insects in their diet. Pumpkinseed from exposed shoreline habitat had jaw and body shape phenotypes, as well as diets, that were similar to sheltered littoral reference pumpkinseed in some traits while others were more intermediate. We found no evidence that differences between habitats in phenotype or diet translated into differences in body condition at the end of the summer growing season, suggesting that exposed littoral shorelines are unlikely to be an ecological ‘sink’ habitat. This study expands our understanding of the spatial distributions of polyphenic pumpkinseed, and their habitat use in postglacial lakes.

Environmental determinants in morphospace and diet of the larval blenny Calliclinus geniguttatus from an upwelling ecosystem.

The effects of two contrasting environmental conditions in nearshore waters off central Chile on the diet and morphospace of two cohorts of larval labrisomid blenny Calliclinus geniguttatus were studied using geometric morphometrics and gut content analysis. The two environmental conditions corresponded to (a) a cold period with upwelling-favourable southwesterly winds and a mixed water column of cooler water and (b) a warm period with calm winds and stratified warmer water. During the cold period, fish larvae had a more hydrodynamic head shape, longer jaws and a higher feeding incidence, suggesting a greater food supply due to upwelling events and a possible increase in encounter rates in the turbulent environment. In contrast, the larvae from the warm period had a more robust head shape with smaller jaws and a lower feeding incidence, which was related to higher water temperatures and lower wind intensities. The present study suggests that larvae have a rapid response to environmental changes on a short time scale (i.e., from weeks to months), showing a link between environmental conditions and changes in the phenotypic traits and diet of the larval stages of this cryptobenthic species.

Unilateral Hypoglossal Nerve Palsy after the Use of a Novel Supraglottic Airway Device

Background: The LMA® Protector™ Airway is a new supraglottic airway device with Cuff Pilot™ Technology that enables visual monitoring of intra-cuff pressure, to reduce the risk of complications from an overinflated device. Case: We present a case of unilateral hypoglossal nerve injury after its use. In our knowledge, this is the first reported case of hypoglossal nerve injury after LMA® Protector™ use. Learning Points: Hypoglossal nerve injury is a rare but distressing complication of LMA use. The greater horn of the hyoid bone is a potential site of injury, as the cuff of the LMA may compress the nerve against bone. In our patient, possible contributing factors included cuff overinflation with/without failure of the Cuff Pilot™ technology, inappropriate sizing and placement of an unfamiliar device. Fortuitously, injury is often neuropraxia with complete recovery in 6 months following conservative management. Consideration should be given to down-sizing the device for Asian patients who tend to have smaller jaws for their weight range. We caution that whilst the green zone of the Cuff Pilot™ corresponds to 40 - 60 cm H2O cuff pressure, it may be more than the “just-seal” pressure required and the cuff may still be overinflated relative to the size of the patient’s airway.

Comparison of village dog and wolf genomes highlights the role of the neural crest in dog domestication

BackgroundDomesticated from gray wolves between 10 and 40 kya in Eurasia, dogs display a vast array of phenotypes that differ from their ancestors, yet mirror other domesticated animal species, a phenomenon known as the domestication syndrome. Here, we use signatures persisting in dog genomes to identify genes and pathways possibly altered by the selective pressures of domestication.ResultsWhole-genome SNP analyses of 43 globally distributed village dogs and 10 wolves differentiated signatures resulting from domestication rather than breed formation. We identified 246 candidate domestication regions containing 10.8 Mb of genome sequence and 429 genes. The regions share haplotypes with ancient dogs, suggesting that the detected signals are not the result of recent selection. Gene enrichments highlight numerous genes linked to neural crest and central nervous system development as well as neurological function. Read depth analysis suggests that copy number variation played a minor role in dog domestication.ConclusionsOur results identify genes that act early in embryogenesis and can confer phenotypes distinguishing domesticated dogs from wolves, such as tameness, smaller jaws, floppy ears, and diminished craniofacial development as the targets of selection during domestication. These differences reflect the phenotypes of the domestication syndrome, which can be explained by alterations in the migration or activity of neural crest cells during development. We propose that initial selection during early dog domestication was for behavior, a trait influenced by genes which act in the neural crest, which secondarily gave rise to the phenotypes of modern dogs.

Beneath the beard: do facial morphometrics influence the strength of judgments of men's beardedness?

Converging evidence suggests men's beards, like many androgen-dependent masculine secondary sexual traits, communicate masculinity and dominance intra-sexually while effects of men's beardedness on attractiveness ratings are more equivocal. Beards may enhance perceived masculinity and dominance via amplifying aspects of underlying craniofacial masculinity, particularly the size of the lower face and jaw. Here we tested these predictions across two studies. In study 1, we tested how three facial metrics - objectively measured craniofacial masculinity, facial-width-to-height ratio (fWHR), and jaw size - calculated while clean-shaven impacted on ratings of attractiveness, masculinity and dominance of 37 men photographed when clean-shaven and with full beards. Results showed that beards exerted significant and positive effects on masculinity, dominance and to a lesser extent attractiveness. However, fWHR did not significantly interact with beardedness to influence the directions of any of the ratings, and while some linear and nonlinear interactions were significant between objective craniofacial masculinity and beardedness as well as between jaw size and beardedness, they tended to be subtle and dwarfed by the large main effect of beardedness on perceptual ratings. In study 2, we measured ratings of attractiveness, masculinity and dominance for composite clean-shaven and bearded stimuli experimentally manipulated in facial shape to represent ±50% the shape of a beard, essentially manipulating the size of the lower face and jaw of the stimuli. We found a strong main effect whereby bearded stimuli enhanced dominance and masculinity ratings over clean-shaven stimuli. Increasing the size of the lower face and jaw augmented ratings of masculinity and dominance in clean-shaven stimuli but did not exert strong effects within bearded stimuli. Attractiveness ratings were highest for bearded faces with smaller jaws followed by bearded and clean-shaven faces with larger jaws and lowest for clean-shaven faces with small jaws. Taken together, our findings suggest that beards exert main effects on masculinity and dominance possibly by amplifying male typical facial shape. Attractiveness ratings of facial hair may reflect a compromise between overly dominant looking faces with larger jaws and the additive effects beardedness has on these ratings.

Cephalometry in adults and children with neurofibromatosis type 1: Implications for the pathogenesis of sphenoid wing dysplasia and the “NF1 facies”

BackgroundNeurofibromatosis type 1 (NF1) is a common, autosomal dominant tumor-predisposition disorder that arises secondary to mutations in the tumor suppressor gene NF1. Cephalometry is an inexpensive, readily available and non-invasive technique that is under-utilized in studying the NF1 craniofacial phenotype. An analysis of NF1 cephalometry was first published by Heervä et al. in 2011. We expand here on that first investigation with a larger cohort of adult and pediatric patients affected with NF1 and sought objective insight into the NF1 facies, said to feature hypertelorism and a broad nasal base, from cephalometric analysis. MethodsWe obtained cephalograms from 101 patients with NF1 (78 adults and 23 children) from two NF1 protocols at the National Institutes of Health. Each subject had an age-, gender- and ethnicity-matched control. We used Dolphin software to make the cephalometric measurements. We assessed the normality of differences between paired samples using the Shapiro–Wilk test and evaluated the significance of mean differences using paired t-tests and adjusted for multiple testing. We explored the relationship between the cephalometric measurements and height, head circumference and interpupillary distance. ResultsIn this dataset of American whites with NF1, we confirmed in a modestly larger sample many of the findings found by Heerva et al. in an NF1 Finnish cohort. We found a shorter maxilla, mandible, cranial base, (especially anteriorly, p = 0.0001) and diminished facial height in adults, but not children, with NF1. Only one adult exhibited hypertelorism. ConclusionsThe cephalometric differences in adults arise in part from cranial base shortening and thus result in a shorter face, mid-face hypoplasia, reduced facial projection, smaller jaw, and increased braincase globularity. In addition, we suggest that NF1 sphenoid bone shortening, a common event, is consistent with an intrinsic NF1 bone cell defect, which renders the bone more vulnerable to a random “second hit” in NF1, leading to sphenoid wing dysplasia, a rare event.

Evaluasi perkembangan lengkungrahanganaksebelum dansesudah penggunaan pirantiortodontiklepasan (Evaluation of the jaw arch development in children before and after using removable orthodontic appliance)

Orthodontics is one science that evaluates the development and growth of the child masticatory system in order to achieve a harmonious face shape and adequate chewing function. This study is aimed to evaluate the development of thejaw arch in children before and after using removable orthodontic appliance through model of the patient's teeth in theDental Hospital, Faculty of Dentistry, University of Hasanuddin. At this descriptive observational study, sample met thecriteria as much as 33 models of patients aged 13-19 years old were measured by the Ponts, Kesling and Howes index.According to Ponts Index, based on the width of the anterior arch, enlarged jaw72.7%and 15.1%decreases; while basedon the width of the posterior arch, enlarged jaw jaw 69.7% and 12.1% decreases. According to Kesling Index, based on right jaw, enlarged by 84.8%and9.1%smaller jaw; based on left jaw, enlarged by 87.8% and 6.1% smaller jaw.Accordingto Howes Index, interpremolar enlarged shrinking 75.8% and 21.2%. According to Howes Index, large apical baseenlarged shrinking 81.8% and 12.1%. It was concluded that the use of different removable orthodontic device affects thedevelopment and growth of the child's jaw.

Developmental origins of the stomodeum links brain and jaw size evolution (921.8)

The evolutionary relationship between brain size and jaw size has been explored in many Vertebrate clades, and is particularly relevant to studies of human evolution. In hominins, an increase in brain size is associated with smaller jaws, but the degree to which these evolutionary changes are independent is largely unknown. We have used quail and duck, two embryos with remarkably different jaw size, to investigate the early developmental relationship between brain and jaw size. Species‐specific jaw size in quail and duck is associated with corresponding differences in early developmental head patterning, including differences in brain regionalization and the size of the stomodeum, or primary mouth. At HH13, the stomodeum in duck is long and narrow, whereas the stomodeum in quail is shorter and rounder. Neural crest migration in quck embryos indicates that stomodeum morphology affects the number of neural crest migrating into the region around the stomodeum, which subsequently determines the initial size of the jaw primordia. To investigate the molecular origins of the distinct head morphology in duck and quail embryos, we investigated the expression of early neural plate and brain regionalization genes, including Pitx2, Pax6, Otx2, Fgf8, Shh, and Krox20. We find that duck embryos exhibit an anterior shift in head patterning at neural plate stages, which increases the length between the midbrain and the primitive foregut in duck relative to quail. Our data suggest that species‐specific differences in jaw size are mediated, in part, by very early developmental mechanisms establishing brain regionalization.Grant Funding Source: Supported by NIH NIDCR R01 DE016402 and F32 DE021929

Quantitative characterization of tomotherapy MVCT dosimetry

Megavoltage computed tomography (MVCT) is used as image guidance for patient setup in almost every tomotherapy treatment. Frequent use of ionizing radiation for image guidance has raised concern of imaging dose. The purpose of this work is to quantify and characterize tomotherapy MVCT dosimetry. Our dose calculation was based on a commissioned dose engine, and the calculation result was compared with film measurement. We studied dose profiles, center dose, maximal dose, surface dose, and mean dose on homogeneous cylindrical water phantoms of various diameters for various scanning parameters, including 3 different jaw openings (of nominal value J4, J1, and J0.1) and couch speeds (fine, normal, and coarse). The comparison between calculation and film measurement showed good agreement. In particular, the thread pattern on the film of the helical delivery matched very well with calculation. For the J1 jaw and coarse imaging mode, the maximum difference between calculation and measurement was about 6% of the center dose. Calculation on various sizes of synthesized phantoms showed that the center dose decreases almost linearly as the phantom diameter increases, and that the fine mode (couch speed of 4mm/rotation) received twice the dose of the normal mode (couch speed of 8mm/rotation) and 3 times that of the coarse mode (couch speed of 12mm/rotation) as expected. The maximal dose ranged from 100% to ∼200% of the center dose, with increasing ratios for larger phantoms, smaller jaws, and faster couch speed. For all jaw settings and couch speeds, the mean dose and average surface dose vary from 95% to 125% of the center dose with increasing ratios for larger phantoms. We present a quantitative dosimetric characterization of the tomotherapy MVCT in terms of scanning parameters, phantom size, center dose, maximal dose, surface dose, and mean dose. The results can provide an overall picture of dose distribution and a reference data set that enables estimation of CT dose index for the tomotherapy MVCT.

SU-D-217BCD-03: Impact of Jaw Width on the Megavoltage Computed Tomography Image Quality and Imaging Dose with Helical Tomotherapy.

On-treatment megavoltage computed tomography on Helical Tomotherapy (Accuray Inc., Sunnyvale, CA) is critical for image guided radiotherapy. A strategy was developed to assess the impact of various jaw widths on image quality and imaging dose with Tomotherapy. A cheese phantom (Gammex RMI, Middleton, WI) made of water equivalent materials was employed in this study. Three sets of measurements were independently carried out. Firstly, in the imaging dose measurement, the phantom was placed on the couch and aligned with a stationary green laser and beam isocenter. The measurement point was 10 mm up from the cente of the phantom. Three slices on either side of the middle slice were selected. Secondly, two inserts with different rows of holes of various sizes were placed inside the phantom for image contrast and resolution investigation. Lastly, twelve density inserts were placed into the outer holes in the phantom for measurement of the image value to density table (IVDT). A comparison of imaging dose, image resolution and contrast, IVDT table between different jaw configurations was performed to evaluate the imaging system. Imaging dose was 2.93 cGy with a jaw size of one mm as opposed to 1.62 cGy with a four mm jaw, both of which are below the vendor's requirement: 3 cGy. However, image quality is improved significantly with the smaller jaw. Four lines of holes can be readily identified on images using smaller jaw while only three lines visible with the larger jaw. Image contrast is similarly enhanced when reducing the jaw size. On average CT numbers are 6% higher with the smaller jaw than those obtained with the larger one. Significant improvement in image quality is achieved with the smaller jaw field in Tomotherapy while the imaging dose is kept at a clinically acceptable level.

MO‐G‐213AB‐01: Quantification of TomoTherapy MVCT Dose

Purpose: To quantify MVCT dose of TomoTherapy for three jaw settings, J4, J1, and J0.1, corresponding to beam widths of 7 mm, 4 mm, and 3 mm, respectively, at the isocenter plane, and three imaging modes, fine, normal, and coarse, corresponding to a couch speed of 4, 8, and 12 mm/rotation, respectively. Material and Methods: An MVCT dose engine was commissioned specifically for the MVCT beams, including updates to the fluence attenuation table (FAT), energy deposition kernel, cone profiles, and penumbrae. MVCT dose calculation was then applied on real and synthesized images of cylindrical water phantoms of diameters ranging from 5 cm to 40 cm, and the results were compared with film measurement. Result: For the J1 jaw and coarse imaging mode, the maximum difference between calculation and measurement was about 6% of the center dose. Calculation on synthesized phantoms showed that the center dose decreased almost linearly as the phantom diameter increased, and that the fine mode received twice the dose of the normal mode and three times that of the coarse mode. The maximal dose due to the helical ripple ranged from 100%∼200% of the center dose, with increasing ratios for larger phantoms (due to the larger radius), smaller jaws, and faster couch speed (the latter two yielding a higher helical pitch). For all jaw settings and couch speeds, the mean dose and average surface dose vary from 95%–115% of the center dose with increasing ratios for larger phantoms. Conclusion: An MVCT dose calculator was set up with validation through film measurement and subsequently used to calculate TomoTherapy MVCT dose for various phantom sizes under various imaging parameters. The results can serve as a reference for TomoTherapy MVCT dose.

Plane surface of edentulous jaws of patients with skeletal class II

Surfaces of edentulous jaw vary in patients with different skeletal classes. The aim of this study was to assess surfaces of supporting tissue areas of edentulous jaws of patients with the skeletal class 2. Materials and method. Thin aluminum phoils (0.5 mm of thickness) were adapted on plaster's surfaces of 47 pairs of edentulous jaw casts. Phoils were positioned to millimetric paper and surface of each foil; was calculated. Additionally, surfaces were measured by plan-meter (G. Coradi, Switzerland, serial no. 49823). The error of measurement was 1%. Skeletal class of edentulous jaws was analyzed on lateral cephalometric radiographs with the analyses of ANB (SNA-SNB) angle. Results. Surfaces of edentulous upper jaws were calculated: 4521 ± 471mm2 for men, and 4386±935 mm2 for women. Surfaces of edentulous lower jaws were 1571 ± 379 mm2 for edentulous men, and 1524 ± 449 mm2 for edentulous women. ANB values were higher than 4o. Dissimilarity of numerical values of surfaces of edentulous upper jaws was 7,2 % when patients with skeletal class I and skeletal class II were compared, but the surfaces of edentulous lower jaws were 16,1 % smaller in patients with skeletal class II. Conclusion. Surfaces of edentulous jaws of men were larger in comparison to women. Edentulous surfaces to the right side were not absolutely symmetric with surfaces to the left side. Patients with skeletal class II had smaller jaws.

Trophic polymorphism in introduced pumpkinseed (Lepomis gibbosus) inhabiting Iberian reservoirs

Introduced pumpkinseed in Iberian reservoirs display marked external morphological differentiation along two simultaneous dimensions of flow and trophic structure. We assessed the degree of internal morphological differentiation using gill rakers, pharyngeal jaws and the levator posterior muscle among pumpkinseeds occupying four different habitats and determined whether prey consumption accounted for any discernible differences in feeding structures among ecomorphs. Results showed significant differentiation by habitat based on pharyngeal muscle and jaw dimensions in all study reservoirs, with pelagic pumpkinseeds having smaller jaws than littoral pumpkinseeds in four of the five reservoirs. Gill rakers, however, differentiated morphs in only three of the five reservoirs, corresponding to differences in zooplankton consumption among pelagic and littoral individuals in those reservoirs. Based on all internal morphological traits, greater divergence was seen along the littoral-pelagic trophic axis in the lacustrine zones of reservoirs compared to the fluvial zone. Overall differences noted in internal morphology are likely the result of phenotypic plasticity; the ability of this species to readily adapt to changing physical environments may explain the success of the pumpkinseed in its introduced range.

ORAL RABIES VACCINE (ORV) BAIT UPTAKE BY CAPTIVE STRIPED SKUNKS

Aerial delivery of oral rabies vaccine (ORV) baits has proven effective in large-scale efforts to immunize wildlife against rabies, and in North America this strategy currently is being used to immunize foxes (Urocyon cinereoargenteus and Vulpes vulpes), raccoons (Procyon lotor), and coyotes (Canis latrans). Skunks are also a major reservoir and vector of rabies, but at present oral vaccines for use in skunks are not licensed. Furthermore, given differences in morphology (smaller jaws) and behavior (food handling and consumption), it is unknown if baits currently used in ORV campaigns would be effective for skunks. Because oral vaccine delivery is contingent upon puncture of the vaccine container (VC), baits need to be sufficiently attractive to elicit selection and consumption. Manipulation of the bait to facilitate vaccine ingestion by the target species is a critical element for an effective ORV bait. The objectives of this study were to assess manipulation and consumption of current ORV baits by striped skunks (Mephitis mephitis). We conducted four independent trials with penned animals and various baits to assess bait selection frequency, VC puncture frequency, and consumption. Video recorded trials were used to assess attractiveness of baits and consumption behavior of skunks. Bait characteristics, such as texture, size, and flavor influenced selection and consumption. Fish and chicken flavors were preferred and vaccine containers within selected baits were likely to be punctured. Vaccine ingestion seemed more likely if VCs were directly coated with the bait matrix. To make baits attractive to skunks and to ensure puncture of the VC, modifications to current baits should consider a smaller size, a meat-flavored matrix, a slightly pressurized VC, and a direct coating of matrix on the VC.

TWO COLEOID JAWS FROM THE UPPER CRETACEOUS OF HOKKAIDO, JAPAN

Abstract Two isolated cephalopod jaws recovered from the middle Turonian of the Obira area and the Campanian of the Nakagawa area, Hokkaido, Japan, consist of short outer, and large and posteriorly elongated inner “chitinous” lamellae, with a sharply pointed rostrum in the outer lamella. These features are common with the upper jaws of Recent cephalopods. Comparison with the upper jaws of ammonoids and Recent cephalopods indicates that the two Cretaceous upper jaws are attributed to the Coleoidea other than the Octopodida. This assignment is also suggested by the cladistic analysis of the Nakagawa specimen compared with five upper jaw characters on 22 Recent cephalopod species. The Obira specimen differs from the Nakagawa specimen in having a much smaller jaw and a larger jaw angle, but its order-level assignment could not be determined because of imperfect preservation. The Nakagawa specimen shares several common features with the upper jaws of Recent Oegopsina; thus we assigned its higher systematic pos...

The relationship between jaw length and jaw opening for vowels

Almost nothing is known about the physiological and acoustic aspects of speech adaptation among speakers whose oral structure is modified by trauma or surgical revision. For example, in speakers who undergo surgical shortening or lengthening of the mandible, it is not clear how the revised jaw length is related to articulatory compensation. Systematic changes in jaw position for speech due to surgical revision would provide insight into the biomechanics of normal jaw movement and speech motor control. The relation between “jaw length” and jaw opening for steady‐state vowels has been investigated using both patients undergoing surgical changes in jaw length and a group of normal controls. Photographic and photoelectric transducing techniques were used to monitor jaw movement during the production of the steady‐state vowels [i, e, ae, o, u, Λ]. Patients exhibited an increase in jaw opening with surgical shortening and a decrease in jaw opening with surgical lengthening. Controls (adults and children) with a large range in jaw size had a similar pattern in that a speaker with a larger jaw had less jaw opening for the steady‐state vowel [a] than a speaker with a smaller jaw. The biomechanical and phonetic factors of this inverse relationship between jaw size and jaw opening will be discussed.