Hard Food Research Articles

Dental health among older Israeli adults: is this a reflection of a medical care model inadequately addressing oral health?

Israel's health-care system is considered as one of the most efficient worldwide. The purpose of the present study was to assess oral health outcomes, dental care use and respective social inequalities among the older segment of the Israeli population. Secondary analyses were conducted of recently available data from the Survey of Health, Ageing, and Retirement in Europe (SHARE Israel, wave 2), which specifically includes information on chewing ability, denture wearing and dental care use obtained from more than 2,400 Israeli people, 50+ years of age. Multivariate logistic regressions and concentration indices were used to analyse determinants of oral health and dental care use. Seventy per cent of respondents reported being able to bite/chew on hard foods and 49% of respondents reported wearing dentures. Forty-three per cent of respondents had visited a dentist within the past 12months, with about half of all dental visits being made for solely nonpreventive reasons. Significant income-related inequalities were identified, with higher income being associated with greater dental care use (particularly preventive dental visits), better chewing ability and less denture wearing. For the older segment of the Israeli population and compared with other countries, the findings of the present study suggest a relatively low level of chewing ability, a high extent of nonpreventive dental visiting, as well as considerable inequalities in oral health and care. It seems that the Israeli health-care system may be improved even further by more comprehensive inclusion of dental care into universal health coverage.

Pediatric Facial Arteriovenous Malformations: Case Report and Overview of the Basics

Aims: Describe the multimodality imaging of a large facial AVM in a child and discuss the treatment options of pediatric facial AVMs Case Presentation: An 11 year old girl developed spontaneous (no prior trauma) enlargement of her left cheek with bleeding from her mouth when eating hard foods. The bleeding was described as pulsatile red bleeding that stopped spontaneously. On physical exam, she had a palpable pulsatile left buccal AVM; auscultation revealing high-flow through it. MRI demonstrated a 2.7 cm heterogeneous vascular mass arising in the soft tissues of the left cheek with involvement of the anterior wall of the left maxillary sinus with a large tortuous ectatic draining vein. CTA demonstrated a large AVM involving the left face with the nidus along the posterior wall of the left maxillary sinus, markedly enlarged draining veins throughout the left face/cheek and prominence of the pterygoid venous plexus. Left common carotid artery angiogram demonstrated an extensive AVM centered in the left maxilla. Left external carotid artery angiogram demonstrates the AVM receiving supply from the distal left internal maxillary, left facial, and left internal maxillary arteries. Angiography of the left internal maxillary demonstrated a high flow AVM with drainage to the left facial vein. The left internal maxillary artery was embolized using Onyx. The left facial, transverse facial, and internal

食品用3Dゲルプリンタを用いた食の創成

The market of care food is growing for aging society and the personal version of care food will be needed for improving a fun of meal. On this occasion, 3D printing technologies have been developed and are being applied for food creation. In the present study, we prepare food ink for the world-first 3D gel printer designed by our group. The hardness of food is one of the most important factors that influence the texture of food. So that the jelly foods made by the 3D gel printer is designed being soft and easy to chew. Here four kinds of jelly food samples are prepared by using agar and gelatin as gelation agents. The mechanical strength of the jelly foods is evaluated by a compression test for foods. We measured the hardness (maxmum stress) of the jelly foods and succeeded in the preparation of various jelly foods of 8 ~ 45kPa in hardness. The gelation of agar is possibly controlled by temperature change. Thus by using the temperature change, the jelly foods are easily printed by the 3D gel printer. We hope these printed jelly foods will make it possible for elder persons to enjoy their fun of everyday meal and improve the quality of life for the elder persons.

Diet-induced phenotypic plasticity in head morphology in European eel elvers (Anguilla anguilla): the effects of hard vs soft food

Event Abstract Back to Event Diet-induced phenotypic plasticity in head morphology in European eel elvers (Anguilla anguilla): the effects of hard vs soft food Jens De Meyer1*, Joachim Christiaens1 and Dominique Adriaens1 1 Ghent University, Biology, Belgium By bone remodeling and changing of muscle volume, fish can adapt to changes in mechanical loads they are confronted with, including dietary changes such as prey hardness. This capability of a genotype to develop different phenotypes in response to varying environment is known as phenotypic plasticity. Differences in prey type being consumed might trigger such a phenotypic plasticity in fish. In European eel, two morphotypes exist: broadheads and narrowheads. Studies based on gut content have shown that broadheads consume larger and harder prey, such as fish, whereas narrowheads feed on smaller prey, such as benthic invertebrates. These studies, however, are performed on yellow eels with a minimum length of 30 cm, and only provide indirect evidence that head shape is affected by diet differences. Here, we performed a feeding experiment on glass eels that just swam up the European rivers to start feeding. These glass eels were captured and separated in three groups: one group was given hard feed requiring biting, the second group got soft feed that could be sucked in and the final group, which acted as a control group, was given a mixture of both. We found that hard feeders developed a broader general head width and postorbital region than soft feeders. This region is associated with the location of the jaw muscles, indicating that hard feeders develop larger muscles to cope with the harder prey. Hard feeders, however, also grew more slowly than soft feeders, suggesting that net energy uptake of hard feeders was lower as prey handling required more energy and time. Specimens of the control group, finally, developed intermediate head widths, implying that they are not fully adapted to feed on either hard or soft prey. In conclusion, this study provides the first direct evidence that diet influences the head shape of European eel. Keywords: dimorphism, Trophic plasticity, elver eel stage, Feeding Behavior, morphology Conference: XV European Congress of Ichthyology, Porto, Portugal, 7 Sep - 11 Sep, 2015. Presentation Type: Oral Presentation Topic: Phylogeny, Systematics and Genetics Citation: De Meyer J, Christiaens J and Adriaens D (2015). Diet-induced phenotypic plasticity in head morphology in European eel elvers (Anguilla anguilla): the effects of hard vs soft food. Front. Mar. Sci. Conference Abstract: XV European Congress of Ichthyology. doi: 10.3389/conf.fmars.2015.03.00022 Copyright: The abstracts in this collection have not been subject to any Frontiers peer review or checks, and are not endorsed by Frontiers. They are made available through the Frontiers publishing platform as a service to conference organizers and presenters. The copyright in the individual abstracts is owned by the author of each abstract or his/her employer unless otherwise stated. Each abstract, as well as the collection of abstracts, are published under a Creative Commons CC-BY 4.0 (attribution) licence (https://creativecommons.org/licenses/by/4.0/) and may thus be reproduced, translated, adapted and be the subject of derivative works provided the authors and Frontiers are attributed. For Frontiers’ terms and conditions please see https://www.frontiersin.org/legal/terms-and-conditions. Received: 27 Oct 2015; Published Online: 04 Nov 2015. * Correspondence: Mr. Jens De Meyer, Ghent University, Biology, Ghent, 9000, Belgium, jendmeye.demeyer@ugent.be Login Required This action requires you to be registered with Frontiers and logged in. To register or login click here. Abstract Info Abstract The Authors in Frontiers Jens De Meyer Joachim Christiaens Dominique Adriaens Google Jens De Meyer Joachim Christiaens Dominique Adriaens Google Scholar Jens De Meyer Joachim Christiaens Dominique Adriaens PubMed Jens De Meyer Joachim Christiaens Dominique Adriaens Related Article in Frontiers Google Scholar PubMed Abstract Close Back to top Javascript is disabled. Please enable Javascript in your browser settings in order to see all the content on this page.

食品の硬さの違いによる咀嚼運動の変化

食品の硬さの違いによる咀嚼運動の変化

A systematic nutritional and dietary guideline for orthodontic patients

A review of the basic principles of nutritional science indicates its applicability to the orthodontics to the many levels. Nutritional considerations are most critical during growth and development and environmental challenges. The orthodontic patients avoid many types of food, particularly fruits, raw vegetables, and other hard and tough foods, as they cannot chew these properly, because of pressure sensitivity of the teeth in the initial 3-5 days period after routine. As a result, such individuals consume significantly less proteins and other key nutrients, fiber, calcium, nonhaem iron, and some vitamins. This paper presents an overview of the relationship between diet and orthodontic treatment. The nutritional guidelines to obtain good oral and general health in orthodontic patients are discussed.

A Comparison of Masticatory Performance and Efficiency of Complete Dentures Made with High Impact and Flexible Resins: A Pilot Study.

In patients with extensive tooth loss, restoration of masticatory function and aesthetics is main concern for a prosthodontist. This study aimed to evaluate and compare differences in masticatory efficiency of patients treated with complete dentures made with either high impact or flexible resins. The sample size consisted of 10 study subjects. Two sets of dentures first conventional followed by flexible dentures were fabricated for each subject and both the sets of dentures were accessed for masticatory performance and efficiency. This study compared the masticatory performance and efficiency of dentures by means of standardized mesh sieves. Masticatory efficiency was calculated by recording the total number of chewing cycles and time required to completely swallow a standardized food item. A patient satisfaction questionnaire was given and evaluated. The statistical analyses were performed using Z-test of Proportion and Paired t-test. The masticatory performance ratio was found to be more for hard food in conventional dentures. The values of masticatory performance ratios for soft food, time and number of masticatory strokes were indicating better masticatory efficiency of conventional dentures. Though masticatory efficiency and performance were found to be better for patient's dentures made with Polymethyl methacrylate (PMMA), a statistically significant number of patients reported that the flexible dentures were more satisfying than the conventional dentures.

A basic study for prediction of food hardness based on an acceleration monitoring of lower jaw during mastication

A basic study for prediction of food hardness based on an acceleration monitoring of lower jaw during mastication

On crack growth in molar teeth from contact on the inclined occlusal surface

Extracted human molar teeth are indented by hard balls laid at the central fossa, sectioned, and their interior examined for damage. Contact on the fissured enamel coat generally occurs on three distinct spots. The main forms of damage are radial cracks growing from the DEJ to the occlusal surface and median radial and cylindrical cracks growing from a contact spot to the DEJ. For large balls failure by edge chipping near a cusp apex may occur. The median cracks tend to run unstably to the DEJ upon reaching the middle part of the enamel coat. The corresponding load, PFM, and the load needed to initiate radial cracks at the DEJ, PFR, are taken to signal crown failure. The mean values of PFM and PFR are on the order of 1000N.A conical bilayer model defined by thickness d, inclination angle θ, failure stress σF and toughness KC of the enamel coat is developed to assess crown failure. The analytical predictions for PFR and PFM agree well with the tests. The results indicate that enamel thickness is so designed as to ensure that PFR and PFM just exceed the maximum bite force under normal conditions while the choice of θ seems to reflect a compromise between needs to resist crown failure and break hard food particles. Both PFR and PFM are greatly reduced with reducing d, which points to the danger posed by tooth wear. The analytical expressions for PFR and PFM may also apply to other multi-cusp mammalian or prosthetic molar crowns. Cone cracking, suppressed in the anisotropic tooth enamel, may be an important failure mode in prosthetic crowns.

The feeding biomechanics and dietary ecology of Paranthropus boisei.

The African Plio-Pleistocene hominins known as australopiths evolved derived craniodental features frequently interpreted as adaptations for feeding on either hard, or compliant/tough foods. Among australopiths, Paranthropus boisei is the most robust form, exhibiting traits traditionally hypothesized to produce high bite forces efficiently and strengthen the face against feeding stresses. However, recent mechanical analyses imply that P. boisei may not have been an efficient producer of bite force and that robust morphology in primates is not necessarily strong. Here we use an engineering method, finite element analysis, to show that the facial skeleton of P. boisei is structurally strong, exhibits a strain pattern different from that in chimpanzees (Pan troglodytes) and Australopithecus africanus, and efficiently produces high bite force. It has been suggested that P. boisei consumed a diet of compliant/tough foods like grass blades and sedge pith. However, the blunt occlusal topography of this and other species suggests that australopiths are adapted to consume hard foods, perhaps including grass and sedge seeds. A consideration of evolutionary trends in morphology relating to feeding mechanics suggests that food processing behaviors in gracile australopiths evidently were disrupted by environmental change, perhaps contributing to the eventual evolution of Homo and Paranthropus.

Oral Sensing of Food Properties

AbstractFood properties are perceived through oral receptors during eating. In this review, various oral receptors involved in food oral processing of food are briefly described. Touch and taste are the most important senses in oral perception. Different tactile receptors are used to determine the mechanical properties, size, shape and their temporal/spatial changes of food materials in the oral cavity. Instrumental test results are often inconsistent with sensory‐perceived food properties. A multiple‐point pressure sensor inserted into the mouth with food can be used to mimic the human tactile systems and to relate instrumental and sensory results. Three evaluation systems of food properties with artificial tongues which were designed in different concepts are presented. Physiological research results are useful to simulate oral processing to design texture, flavor and appearance of diets for people with different eating functions.Practical ApplicationsFood oral processing is a dynamic process in which a mouthful of food is reduced in heterogeneity and converted into a more homogenized swallowable bolus. Human‐mimetic sensing technologies have been recently developed to analyze the physical and chemical properties, these complex interactions and drastic changes of foodstuffs during oral processing. As practical applications, two current social topics are discussed in terms of homogenization of foods during oral processing. First, with the increase of elderly population, a need for texture‐modified foods has emerged: hard food must be converted into paste‐like, where the function of oral processing is partly done by pre‐oral processing. Second, WASHOKU, the traditional dietary cultures of the Japanese, was added to UNESCO's Intangible Cultural Heritage list in 2013. Seasoning in the mouth, one of the features of oral processing of WASHOKU, is addressed. To improve food texture and flavor is needed for people with various ages and regions.

Deep-Frying Oil: Heat-Induced Changes

Studies report that the frying process causes chemical changes in altering its composition, causing unpleasant flavor, very hard and dark fried food surface, and an excess of oil absorbed, among others. Deep-frying oil samples were collected from four randomly chosen food services every other day for 10 days. Acidity, peroxide, and iodine values were measured; lipid profiles were determined by gas chromatography. Esterified samples were stored at -18°C. The statistical software used was SAS, version 2.0, 5 % significance level. Analysis of variance (PROC GLM) was used to look for differences among oils of different food services (p ≤ 0.05). Since differences were found, regression analysis was done (PROC REG). The Tukey’s test was used for comparing the oil characteristics that did not vary homogeneously with use. Acidity was the most appropriate indicator for assessing oil stability. Linoleic and linolenic acids were the most affected by heat. Linolelaidic acid content increased only 0.03%.

Dental Function and Diet of Vintana Sertichi (Mammalia, Gondwanatheria) from the Late Cretaceous of Madagascar

ABSTRACT—The nearly complete and well-preserved cranium of Vintana sertichi provides an opportunity to investigate its dietary adaptations. We used a combination of comparative morphological and biomechanical analyses to reveal the direction of its power stroke during mastication, reconstruct the positions and relative sizes of its muscles of mastication, and predict its capacity to produce bite forces during incision and molariform occlusion. The orientation of dental wear striations on the upper molariform teeth of Vintana, in combination with the orientation of the enamel islets and synclines and the position of leading and trailing edges, demonstrates that the power stroke was primarily palinal (distally directed), with a significant buccally directed component that is absent in multituberculates, haramiyidans, and other gondwanatherians. The large palinal component of jaw movement was corroborated by biomechanical analyses of the moments generated by the primary jaw adductors around the dentary-squamosal joint axis. Similar analyses also confirmed the previously documented proal (mesially directed) power stroke of the extant rodent Myocastor. Finite element analyses predict that Vintana was capable of producing bite forces that were more than twice as high as the similarly sized Myocastor. Vintana was almost certainly an herbivore, as claimed previously for other sudamericid gondwanatherians. Its size and capacity to generate high bite forces at both the incisors and the molariform teeth suggest that it was a mixed feeder whose diet may have included relatively large, hard food items such as roots, seeds, twigs, or nut-like fruits.

Bacteriophage Mixture Inactivation Kinetics against Escherichia Coli O157:H7 on Hard Surfaces

AbstractThis study determined the effect of previously described phage cocktail (BEC8) on the inactivation kinetics of a mixture of Escherichia coli (EHEC) O157:H7 strains on food processing surface materials: stainless steel chip (SSC), ceramic tile chip (CTC) and high‐density polyethylene chip (HDPEC). EHEC strains were combined and spot‐inoculated on surfaces in dried or liquid form and BEC8 was applied and incubated at 12, 23, 30 and 37C. EHEC survival was determined on tryptic soy agar. D values ranged from 3.9 min at 37C to 46.7 min at 12C. Z values calculated for SSC, CTC and HDEPC resulted in 26.1, 23.7 and 26.7C for dry cells, respectively, and 23.2, 23.7 and 24.5C for liquid cells, respectively. There was a significant difference in the rate of bacterial inactivation between lower (12 and 23C) and higher temperatures (30 and 37C). These results indicated that BEC8 killed EHEC on hard surfaces rapidly following first‐order kinetics.Practical ApplicationsThe effect of a previously described phage cocktail (BEC8) on the inactivation kinetics of a mixture of Escherichia coli (EHEC) O157:H7 strains applied on hard food processing surface materials was studied. The results indicated that phages killed EHEC on hard surfaces relatively rapidly following a predictable rate. However, one must consider the long times to achieve a 5‐log reduction when initial cell counts are high. It would take approximately 2–4 h for a 5‐log cfu reduction of liquid cells at 23C. Both the time length and the temperature of application must fit within the industry time scales.

Assessment of masticatory function in patients with non-sagittal occlusal discrepancies.

Non-sagittal occlusal discrepancies such as posterior cross-bite and anterior openbite are common types of malocclusion, but studies on masticatory function related to those malocclusions have been scarce. The aim of this study was to quantify the masticatory performance in patients with non-sagittal discrepancies compared to those with normal occlusion, using both objective and subjective measures. Maximum bite force and contact area using Dental Prescale(®) system as a static objective assessment, Mixing Ability Index (MAI) as a dynamic objective evaluation and food intake ability (FIA) as a subjective assessment were analysed from 21 people in normal occlusion (Group N) and 64 patients with posterior cross-bite (Group C), anterior openbite (Group O) or both (Group B). The differences of the maximum bite force, the contact area, the MAI and the FIA were compared, and their correlations were figured out. The non-sagittal malocclusion groups showed lower values in the maximum bite force, the contact area, the MAI and the FIA compared to those in the normal group (P < 0·0001). Compared to Group N, Groups C, O and B showed 61·5%, 42·1% and 40·1% of the maximum bite force, and 84%, 84% and 76% of hard food FIA, respectively. However, there were no significant differences among Groups C, O and B. The MAI showed higher correlation with the FIA (r = 0·38, P < 0·01), than with the maximum bite force and the contact area (both r = 0·24, P < 0·5). These results revealed that masticatory function in patients with non-sagittal discrepancies is significantly reduced both objectively and subjectively.

Effect of mini-implant-supported mandibular overdentures on electromyographic activity of the masseter muscle during chewing of hard and soft food.

To objectively evaluate the effect of mini-implant- supported mandibular overdentures on electromyographic activity (EMG) of the masseter muscle during chewing of hard and soft foods. Twelve completely edentulous patients (4 females and 8 males) with maladaptive experience of wearing mandibular dentures received new maxillary and mandibular dentures. After 3 months of adaptation, four mini dental implants (MDIs) were inserted in the interforaminal region of the mandible, and the new mandibular dentures were connected to the implants immediately with O/ring attachments. The activity of masseter muscle (EMG) and the duration of chewing cycle were measured during chewing hard (carrot) and soft (gum) foods. The measurements were made 3 months after wearing each of the following prostheses: the new conventional dentures; and the MDI-retained mandibular overdentures. The EMG of masseter muscle increased and the DC decreased with MDI-retained mandibular overdentures when compared to conventional dentures. Hard food (carrot) was associated with increased EMG and decreased DC when compared to soft food (gum) for both conventional dentures and MDI-retained mandibular overdentures. Mini-implant-supported mandibular overdentures are associated with increased activity of masseter muscle and decreased duration of chewing cycle for both hard and soft foods when compared to conventional dentures.

Towards a gene regulatory network perspective on phenotypic plasticity, genetic accommodation and genetic assimilation.

Many organisms can produce alternative phenotypes in direct response to different environmental conditions, a phenomenon known as phenotypic plasticity. The environmentally sensitive gene regulatory networks (GRNs) that mediate such developmental flexibility are largely unknown. Yet, characterizing these GRNs is important not only for elucidating plasticity's molecular basis, but also for shedding light onto whether and how plasticity might impact evolution. In this issue of Molecular Ecology, Schneider et al.) describe one of the first efforts to determine the GRN underlying a plastic trait. They focus on diet-induced plasticity in the cichlid fish, Astatoreochromis alluaudi. Depending on whether soft food (e.g. insects) or hard food (e.g. molluscs) is consumed, this species forms a lower pharyngeal jaw (LPJ) with many fine teeth or with fewer molar-like teeth, respectively (Fig. 1). The authors previously identified genes that are differentially expressed between LPJ morphs during early development. In the present study, they examine the expression of 19 of these genes across development and diet. By analysing these transcriptional data in combination with information on putative transcription factor binding sites, they construct a GRN that explains observed gene expression patterns and is likely to control LPJ morphology. This work advances our understanding of how plasticity can arise as a consequence of environmentally sensitive GRNs and promises to help illuminate how changes in such GRNs could facilitate evolution.

Functions of the Temporomandibular System in Extracranial Chronic Pain Conditions: Modulatory Effects on Nocifensive Behavior in an Animal Model

ObjectiveMastication may be able to activate endogenous pain inhibitory mechanisms and therefore lead to modulation of nociceptive processing. The purpose of this study was to examine the possible effect of food consistency on noxious input from the spinal system. MethodsThree groups of adult male Sprague-Dawley rats were given an injection of complete Freund adjuvant in a hind paw 10 days after eating soft or hard food (one group received a saline injection—the control group [C]; the other group (D) received no injection). Nocifensive behavior was assessed with the use of the hot plate and tail flick assays at 1, 3, 6, and 12 hours and at 6.5 days after injection for groups A/B, and c-Fos activity was assessed in the brain after testing. Groups C/D had hot plate testing at 1 hour and 6.5 days. The data were analyzed by general linear modeling and 1-way analysis of variance. ResultsThere was a small increase in the hot plate percent maximum possible effect (MPE) from −45.7 to −61.1 in group A over the length of the experiment, but a very small decrease for group B over the same period (−33.5 to −28.8). For the saline control group, there was a small increase toward 0 %MPE over the same time frame (−15.0 to 1.7). The %MPE differences were significant between groups A and C (P < .0005), but not significant between the other groups (F = 13.34, df = 2, P = .001, observed power = 99%). Using the pooled results (all time points), the differences between all groups were significant (P < .0005). There were no significant differences in the tail flick test. c-Fos was mainly observed in the raphe pallidus area with significant differences between groups A and B at 3 and 6 hours after injection of CFA (P = .027 and .022, respectively). ConclusionsThe results of this study indicate that food consistency (hardness) influences nocifensive behavior in this animal model via a descending pathway operating at the supraspinal level.

Food mechanical properties, feeding ecology, and the mandibular morphology of wild orangutans

Bornean orangutan mandibular morphology has been functionally linked to the exploitation of hard and tough foods, based on evidence that Pongo pygmaeus wurmbii spends a greater percentage of time feeding on bark, seeds and vegetation compared with Pongo abelii (Sumatran orangutans) and the assumption that these tissues are more challenging to process than fruit pulp. We measured and compared toughness (R) and Young's modulus (E) of ripe and unripe foods exploited by P. abelii and P. p. wurmbii. Additionally, we recorded and compared the percentage of time these orangutans fed on plants/plant parts of varying degrees of R and E. Compared with P. abelii, P. p. wurmbii consumed significantly tougher and more displacement limited (R/E)0.5 fruit parts, leaves and inner bark, and spent a significantly greater percentage of time feeding on immature leaves, unripe fruit and other vegetation. Modulus did not vary as expected between species, likely because we failed to capture the high-end range of modulus values for tissues consumed by P. p. wurmbii. Notably, P. p. wurmbii spent ∼40% of its feeding time on the toughest foods consumed (between 1000 and 4000 J m−2). Thus, the hypothesis that mandibular robusticity in P. p. wurmbii is functionally linked to feeding on tough foods is supported and is likely related to countering relatively larger external forces and/or repetitive loads required to process the toughest tissues. The importance of elastic modulus on morphological divergence awaits future studies capturing the full range of this material property for P. p. wurmbii. Finally, phenophase and fruit availability influence orangutan species differences in food material properties and percentage of time spent feeding on various foods, emphasizing the importance of incorporating these variables in future studies of feeding ecology and craniodental morphology in extant taxa.

Dietary variation and food hardness in sooty mangabeys (Cercocebus atys): implications for fallback foods and dental adaptation.

We present information on food hardness and monthly dietary changes in female sooty mangabeys (Cercocebus atys) in Tai Forest, Ivory Coast to reassess the hypothesis that thick molar enamel is parsimoniously interpreted as a response to consumption of hard foods during fallback periods. We demonstrate that the diet of sooty mangabeys varies seasonally, but that one food--Sacoglottis gabonensis--is the most frequently consumed food every month and year round. This food is the hardest item in the sooty diet. Given that this species has among the thickest enamel within the primate order, a plausible conclusion is that thick enamel in this taxon evolved not in response to seasonally critical function or fallback foods, but rather to the habitual, year round processing of a mechanically protected foodstuff. These data serve as a caution against de rigueur interpretations that reliance on fallback foods during lean periods primarily explains the evolution of thick enamel in primates.