Co-occurrence of periodontal lesions and dental wear in incisor and masticatory teeth in two sheep flocks in Brazil.

BACKGROUND: Periodontitis and tooth wear are multifactorial diseases with distinct etiopathogenesis that affect the health, feed efficiency and welfare of sheep. METHODS: This study evaluated the co-occurrence of tooth wear and periodontal lesions in 129 ewes from two Brazilian flocks, clinically classified the lesions and presence of dental calculus, and identified potential pathogens in the dental biofilm of 63 ewes by polymerase chain reaction. RESULTS: Of the 129 ewes included in the study, 75 presented periodontal lesions, while all animals presented tooth wear and dental calculus. Of the animals with periodontal lesions, 16.2% had lesions in incisor teeth and 52.7% in masticatory teeth. Regarding excessive tooth wear, 38.6% had severe wear on the incisor teeth and 89.1% on the masticatory teeth. Ewes older than 36 months had a higher frequency of periodontal lesions in incisor teeth (p < 0.001) and a greater amount of dental calculus (p < 0.001), but there was no association between tooth wear and animal age. Fusobacterium nucleatum, Tannerella forsythia and Fusobacterium necrophorum predominated in periodontal lesions. LIMITATION: This study is limited by the small sample size and lack of diagnostic imaging to assess periodontal disease. CONCLUSION: The co-occurrence of periodontal lesions and excessive dental wear involving both the incisor and masticatory teeth suggests that although the two diseases have different aetiologies, they likely have common risk factors.

Is a blunt sword pointless? Tooth wear impacts puncture performance in Tasmanian devil canines.

As teeth wear, their shapes change and functional features can be dulled or lost, presumably making them less effective for feeding. However, we do not know the magnitude and effect of this wear. Using Tasmanian devil canines as a case study, we investigated the impact of wear on puncture in pointed teeth. We measured aspects of shape impacted by wear (tip sharpness, height and volume) in teeth of varying wear followed by 3D printing of real and theoretical forms to carry out physical puncture tests. Tooth wear acts in two ways: by blunting tooth tips, and decreasing height and volume, both of which impact performance. Sharper tips in unworn teeth decrease the force and energy required to puncture compared with blunter worn teeth, while taller unworn teeth provide the continuous energy necessary to propagate fracture relative to shorter worn teeth. These wear-modulated changes in shape necessitate more than twice the force to drive worn teeth into ductile food and decrease the likelihood of puncture success.

The Ruminant sorting mechanism protects teeth from abrasives.

Dental wear due to ingestion of dust and grit has deleterious consequences. Herbivores that could not wash their food hence had to evolve particularly durable teeth, in parallel to the evolution of dental chewing surface complexity to increase chewing efficacy. The rumen sorting mechanism increases chewing efficacy beyond that reached by any other mammal and has been hypothesized to also offer an internal washing mechanism, which would be an outstanding example of an additional advantage by a physiological adaptation, but in vivo evidence is lacking so far. Here, we investigated four cannulated, live cows that received a diet to which sand was added. Silica in swallowed food and feces reflected experimental dietary sand contamination, whereas the regurgitate submitted to rumination remained close to the silica levels of the basal food. This helps explain how ruminants are able to tolerate high levels of dust or grit in their diet, with less high-crowned teeth than nonruminants in the same habitat. Palaeo-reconstructions based on dental morphology and dental wear traces need to take the ruminants' wear-protection mechanism into account. The inadvertent advantage likely contributed to the ruminants' current success in terms of species diversity.

Dental macrowear reveals ecological diversity of Gorilla spp.

Size and shape variation of molar crowns in primates plays an important role in understanding how species adapted to their environment. Gorillas are commonly considered to be folivorous primates because they possess sharp cusped molars which are adapted to process fibrous leafy foods. However, the proportion of fruit in their diet can vary significantly depending on their habitats. While tooth morphology can tell us what a tooth is capable of processing, tooth wear can help us to understand how teeth have been used during mastication. The objective of this study is to explore if differences in diet at the subspecies level can be detected by the analysis of molar macrowear. We analysed a large sample of second lower molars of Grauer's, mountain and western lowland gorilla by combining the Occlusal Fingerprint Analysis method with other dental measurements. We found that Grauer's and western lowland gorillas are characterised by a macrowear pattern indicating a larger intake of fruit in their diet, while mountain gorilla's macrowear is associated with the consumption of more folivorous foods. We also found that the consumption of herbaceous foods is generally associated with an increase in dentine and enamel wear, confirming the results of previous studies.

Tooth wear, growth and height in rabbits (Oryctolagus cuniculus) fed pelleted or extruded diets with or without added abrasives.

Among the different factors thought to affect dental wear, dietary consistency is possibly the least investigated. To understand tooth wear of herbivorous animals consuming different dietary consistencies with different abrasive potential, we fed 14 rabbits (Oryctolagus cuniculus) exclusively with a timothy grassmeal-based diet in either pelleted or extruded form, or the same diets with an addition of 5% fine sand abrasives (mean size 130 µm). First, we offered the rabbits the pelleted and extruded diets as well as the pelleted control and pelleted abrasive diet in a two-stage preference experiment. Then, the rabbits received each diet for 2 weeks in a randomised serial feeding experiment, where each animal served as its own control. Tooth measurements for wear, growth and height were achieved using a manual calliper, endoscopic examination and CT scans. The analysis of the diets as fed showed almost identical mean particle size, but the extruded diet had a lower density (volume/mass) and softer consistency compared to the pelleted one and was favoured by most rabbits. The rabbits selected against the diet with sand during the preference experiment, possibly because it caused more tooth wear, especially on the teeth most exposed to wear along the upper tooth row (upper P4 and M1). The maxillary teeth also showed evidence of an increased chewing laterality by the end of the experiment. The extruded diet led to a significantly lower cheek teeth height than the pelleted diet, potentially due to the higher chewing effort needed for a similar dry matter intake. The results suggest that dietary hardness alone is a poor predictor of dental wear. The regrowth of the teeth matched wear consistently.

Wearing the devil down: Rate of tooth wear varies between wild and captive Tasmanian devils.

Mammalian carnivores rely on their sharp teeth to effectively kill and consume prey. However, over time this causes wear and breakage that alters tooth shape, reducing their effectiveness. Extreme tooth wear and damage is especially prevalent in species that scavenge carcasses, like the Tasmanian devil (Sarcophilus harrisii), which are well known for their voracious appetites and ability to consume almost all of a carcass, including bone. In this study, we comprehensively describe tooth wear in captive and wild devils to look for differences in the patterns and rate of wear between these environments. To do this we surveyed tooth condition in skulls from 182 wild and 114 captive devils for which age was estimated using canine over-eruption. We found the types of tooth wear documented were the same in captive and wild devils, but captive animals have less severe wear than wild devils of the same estimated age. There was no difference in the proportion of captive or wild individuals with broken canine or molar teeth; however, breakage occurred at a younger age in wild devils. Although not considered anomalous or harmful, this indicates a difference in the way teeth are being used and/or the foods consumed between captive and wild devils. We hypothesize how these results relate to differences in diet or behavior that may stem from their various feeding environments, for example, higher quality food (fresh, whole, and yet to be scavenged carcasses) provided to captive devils likely causes less wear. Further, we support management options that closely replicate wild diet items and behaviors suitable for a long-term insurance population.

Dental microwear of a basal ankylosaurine dinosaur, Jinyunpelta and its implication on evolution of chewing mechanism in ankylosaurs.

Jinyunpelta sinensis is a basal ankylosaurine dinosaur excavated from the mid Cretaceous Liangtoutang Formation of Jinyun County, Zhejiang Province, China. In the present study, its dental microwear was observed using a confocal laser microscope. Jinyunpelta had steep wear facets that covered most of buccal surfaces of posterior dentary teeth. Observation of dental microwear on the wear facet revealed that scratch orientation varied according to its location within the wear facet: vertically (i.e. apicobasally) oriented scratches were dominant in the upper half of the wear facet, and horizontally (i.e. mesiolaterally) oriented ones were in the bottom of the facet. These findings indicated that Jinyunpelta adopted precise tooth occlusion and biphasal jaw movement (orthal closure and palinal lower jaw movement). The biphasal jaw movement was widely observed among nodosaurids, among ankylosaurids, it was previously only known from the Late Cretaceous North American taxa, and not known among Asian ankylosaurids. The finding of biphasal jaw movement in Jinyunpelta showed sophisticate feeding adaptations emerged among ankylosaurids much earlier (during Albian or Cenomanian) than previously thought (during Campanian). The Evolution of the biphasal jaw mechanism that contemporaneously occurred among two lineages of ankylosaurs, ankylosaurids and nodosaurids, showed high evolutionary plasticity of ankylosaur jaw mechanics.

Confirmation of a wear-compensation mechanism in dental roots of ruminants.

Diet affects many factors of an animal's anatomy, but teeth are a specific focus of dietary research, as their durability lends them to record information on a large variety of scales. Abrasive diets like those of grazing herbivores are known to wear down teeth, but how that wear affects tooth growth and the relations between its different morphological components is rarely investigated. Seven pelleted diets varying in abrasive size and concentration were fed over a 17-month period to 49 sheep (Ovis aries), of which n = 39 qualified for morphology measurements. Using computed tomography, scans of the skulls were made over the course of the experiment, and the impact of diet-related wear was observed on tooth volume and morphology, including the position of dental burr marks, over time. Digital caliper measurements were applied to 3D renderings of the teeth, and the volume of crown and root segments were investigated separately. We aimed to detect a signal of root growth compensating for wear, and test if this mechanism would be affected by dietary abrasives. Crown-segment volume loss was correlated to root-segment volume gain. Height and burr mark measurements indicated a much higher experimental tooth wear than that previously reported for free-ranging animals. The reason for this is unclear. There was no relationship between tooth height and dentine basin depth. For all parameters, there was no effect of diet; hence, while the measurements corroborate general understanding of tooth wear and compensatory processes, these methods appear not suitable to assess subtle differences between feeding regimes.

Shape, size, and quantity of ingested external abrasives influence dental microwear texture formation in guinea pigs.

Food processing wears down teeth, thus affecting tooth functionality and evolutionary success. Other than intrinsic silica phytoliths, extrinsic mineral dust/grit adhering to plants causes tooth wear in mammalian herbivores. Dental microwear texture analysis (DMTA) is widely applied to infer diet from microscopic dental wear traces. The relationship between external abrasives and dental microwear texture (DMT) formation remains elusive. Feeding experiments with sheep have shown negligible effects of dust-laden grass and browse, suggesting that intrinsic properties of plants are more important. Here, we explore the effect of clay- to sand-sized mineral abrasives (quartz, volcanic ash, loess, kaolin) on DMT in a controlled feeding experiment with guinea pigs. By adding 1, 4, 5, or 8% mineral abrasives to a pelleted base diet, we test for the effect of particle size, shape, and amount on DMT. Wear by fine-grained quartz (>5/<50 µm), loess, and kaolin is not significantly different from the abrasive-free control diet. Fine silt-sized quartz (∼5 µm) results in higher surface anisotropy and lower roughness (polishing effect). Coarse-grained volcanic ash leads to significantly higher complexity, while fine sands (130 to 166 µm) result in significantly higher roughness. Complexity and roughness values exceed those from feeding experiments with guinea pigs who received plants with different phytolith content. Our results highlight that large (>95-µm) external silicate abrasives lead to distinct microscopic wear with higher roughness and complexity than caused by mineral abrasive-free herbivorous diets. Hence, high loads of mineral dust and grit in natural diets might be identified by DMTA, also in the fossil record.

Buccal dental-microwear and feeding ecology of Early Pleistocene Theropithecus oswaldi from Cueva Victoria (Spain).

Despite the scarcity of fossil specimens of Theropithecus oswaldi in Eurasia, its presence out of Africa attests to the great dispersal of this Papionini genus during the Early Pleistocene. In the present study, we analyze the buccal dental microwear of T. oswaldi (T. o. leakeyi) fossil specimens from Cueva Victoria (Southeastern Spain). This analysis is the first characterization of the feeding ecology of T. oswaldi in Europe. The buccal microwear pattern of the molar and premolar teeth of T. oswaldi from Cueva Victoria shows great similarities to that observed for the extant frugivorous forest-dwelling Mandrillus sphinx and mangabeys (Cercocebus sp.)-both species adapted to durophagous dietary habits-while significantly different from that observed for the gramnivorous Theropithecus gelada. These results suggest that T. oswaldi from Cueva Victoria could have exploited both hard-shelled fruits or seeds and succulent fruits from open and forested Mediterranean ecosystems.

Dust and grit matter: abrasives of different size lead to opposing dental microwear textures in experimentally fed sheep (Ovis aries).

External abrasives ingested along with the herbivore diet are considered main contributors to dental wear, though how the different sizes and concentrations of these abrasives influence wear remains unclear. Dental microwear texture analysis (DMTA) is an established method for dietary reconstruction which describes a tooth's surface topography on a micrometre scale. The method has yielded conflicting results as to the effect of external abrasives. In the present study, a feeding experiment was performed on sheep (Ovis aries) fed seven diets of different abrasiveness. Our aim was to discern the individual effects of size (4, 50 and 130 µm) and concentration (0%, 4% and 8% of dry matter) of abrasives on dental wear, applying DMTA to four tooth positions. Microwear textures differed between individual teeth, but surprisingly, showed no gradient along the molar tooth row, and the strongest differentiation of experimental groups was achieved when combining data of all maxillary molars. Overall, a pattern of increasing height, volume and complexity of the tooth's microscopic surface appeared with increasing size of dietary abrasives, and when compared with the control, the small abrasive diets showed a polishing effect. The results indicate that the size of dietary abrasives is more important for dental microwear texture traces than their concentration, and that different sizes can have opposing effects on the dietary signal. The latter finding possibly explains conflicting evidence from previous experimental DMTA applications. Further exploration is required to understand whether and how microscopic traces created by abrasives translate quantitatively to tissue loss.

The dental microwear of hard-object feeding in laboratory Sapajus apella and its implications for dental microwear formation.

OBJECTIVES: This study seeks to determine if (a) consumption of hard food items or a mixture of food items leads to the formation of premolar or molar microwear in laboratory capuchin monkeys (Sapajus apella) in one feeding session and (b) rates of microwear formation are associated with the number of food items consumed. MATERIALS AND METHODS: Five adult male capuchins were used in two experiments, one where they were fed unshelled Brazil nuts, and the other where they were fed a mixture of food items. Dental impressions were taken before and after each feeding session. Epoxy casts made from those impressions then were used in SEM analyses of rates of microwear formation. Upper and lower premolars and molars were analyzed. Qualitative comparisons were made and Spearman's rank-order correlations used to examine the relationship between rates of microwear formation and number of Brazil nuts consumed. RESULTS: Premolars and molars generally showed new microwear in the form of pits and scratches. However, the incidence of those features was low (0-6%). Rates of microwear formation were highest during the consumption of Brazil nuts. DISCUSSION: Variations in the rate of microwear formation on the premolars likely reflected patterns of ingestion whereas consistency in the rate of microwear on the molars likely reflected patterns of chewing. While dental microwear formation seemed to be correlated with the number of hard objects consumed, rates did differ between individuals. Differences in results between the two experiments demonstrate some of the limitations in our knowledge of dental microwear formation.

Malocclusions in the koala (Phascolarctos cinereus).

Malocclusions are a misalignment or incorrect positioning of the teeth when the upper and lower jaws close. These are poorly described in the koala and can result in irregular mastication which can have lifelong effects on body condition and oral health. A total of 370 koalas from two populations in Queensland (295) and one in South Australia (75) were examined for malocclusions. The prevalence of malocclusions in South Australian free-ranging koalas, captive Queensland koalas and Queensland free-ranging koalas was 39% (44), 30% (29) and 22% (29) respectively. Four types of malocclusion were identified based on severity of misalignment of the incisor/canine region, types 1, 2, 3 and 4. Maxillary overbite measurements of the molariform teeth were determined and these anisognathic values were then used to describe malocclusions within familial relationships in captive colonies. Captive koalas with a malocclusion had narrower mandibular width that ranged between 0.5 and 1% less than the normal measurements. The specific malocclusions reported in this study affected individuals by leading to tooth rotation, mobility and erosion with inefficient mastication of food and vegetation compaction. These changes increased the oral cavity pathology, by placing animals at risk of periodontal disease. There was evidence of familial links to malocclusion types in captive animals. Therefore captive breeding recommendations should consider known koala malocclusion traits to minimise their effect on future generations.

Complementary approaches to tooth wear analysis in Tritylodontidae (Synapsida, Mammaliamorpha) reveal a generalist diet.

Stereoscopic microwear and 3D surface texture analyses on the cheek teeth of ten Upper Triassic to Lower Cretaceous tritylodontid (Mammaliamorpha) taxa of small/medium to large body size suggest that all were generalist feeders and none was a dietary specialist adapted to herbivory. There was no correspondence between body size and food choice. Stereomicroscopic microwear analysis revealed predominantly fine wear features with numerous small pits and less abundant fine scratches as principal components. Almost all analyzed facets bear some coarser microwear features, such as coarse scratches, large pits, puncture pits and gouges pointing to episodic feeding on harder food items or exogenous effects (contamination of food with soil grit and/or dust), or both. 3D surface texture analysis indicates predominantly fine features with large void volume, low peak densities, and various stages of roundness of the peaks. We interpret these features to indicate consumption of food items with low to moderate intrinsic abrasiveness and can exclude regular rooting, digging or caching behavior. Possible food items include plant vegetative parts, plant reproductive structures (seeds and seed-bearing organs), and invertebrates (i.e., insects). Although the tritylodontid tooth morphology and auto-occlusion suggest plants as the primary food resource, our results imply a wider dietary range including animal matter.

Root growth compensates for molar wear in adult goats (Capra aegagrus hircus).

One reason for the mammalian clade's success is the evolutionary diversity of their teeth. In herbivores, this is represented by high-crowned teeth evolved to compensate for wear caused by dietary abrasives like phytoliths and grit. Exactly how dietary abrasives wear teeth is still not understood completely. We fed four different pelleted diets of increasing abrasiveness (L: Lucerne; G: grass; GR: grass and rice husks; GRS: grass, rice husks, and sand) to four groups of a total of 28 adult goats, all with completely erupted third molars, over a six-month period. Tooth morphology was captured by medical computed tomography scans at the beginning and end of the controlled feeding experiment, and separation lines between the crown and root segments were defined in the upper right second molar (M2), to gauge absolute wear. Using bootstrapping, significant differences in volume loss between diets L/G and GR/GRS were detected. A small but nevertheless consistent volume gain was noted in the roots, and there was a significant, positive correlation between crown volume loss and root volume gain. This growth could possibly be attributed to the well-known process of cementum deposition and its relation with a putative feedback mechanism, in place to attenuate wear caused by abrasive diets.

Three-dimensional tooth surface texture analysis on stall-fed and wild boars (Sus scrofa).

Categorizing the archaeological remains of Sus scrofa as domesticated "pigs" or wild "boars" is often difficult because of their morphological and genetic similarities. For this purpose, we tested whether feeding ecological change of S. scrofa that accompanied their domestication can be detected based on the three-dimensional texture created on the tooth enamel surface by mastication. We scanned the lower tooth surface of one wild and one stall-fed populations of modern S. s. leucomystax and one wild population of S. s. riukiuanus by using a confocal laser microscope. The average body weight of S. s. leucomystax is twice as heavier as that of S. s. riukiuanus. The textures were quantified using the industrial "roughness" standard, ISO 25178, to prevent inter-observer errors and to distinguish small differences that were difficult to detect by two dimensional image observation. The values of parameters related to height and volume were significantly larger in the stall-fed population. Twenty parameters differed significantly between the stall-fed and wild population of S. s. leucomystax, which indicated that the feeding ecological difference affected the ISO parameters of the two boar populations. Six parameters also differed between the wild populations of S. s. leucomystax and S. s. riukiuanus. Surprisingly, no parameter differed between the populations of stall-fed S. s. leucomystax and wild S. s. riukiuanus. Consumption of hard nuts and/or agricultural fruits and crops by the wild population of S. s. riukiuanus may have produced a tooth surface texture similar to that of the stall-fed population of S. s. leucomystax. Further analysis of S. s. riukiuanus with a known diet is necessary to conclude whether ISO parameters reflect the dietary transition accompanying the domestication of Sus (e.g., wild, semi-domestic, and domestic). Until then, caution is needed in discriminating domesticated populations from wild populations that mainly feed on hard objects.

Controlled feeding experiments with diets of different abrasiveness reveal slow development of mesowear signal in goats (Capra aegagrus hircus).

Dental mesowear is applied as a proxy to determine the general diet of mammalian herbivores based on tooth-cusp shape and occlusal relief. Low, blunt cusps are considered typical of grazers and high, sharp cusps typical of browsers. However, how internal or external abrasives impact mesowear, and the time frame the wear signature takes to develop, still need to be explored. Four different pelleted diets of increasing abrasiveness (lucerne, grass, grass and rice husks, and grass, rice husks and sand) were fed to four groups of a total of 28 adult goats in a controlled feeding experiment over a 6-month period. Tooth morphology was captured by medical CT scans at the beginning and end of the experiment. These scans, as well as the crania obtained post mortem, were scored using the mesowear method. Comparisons between diet groups showed few significant differences after 6 months, irrespective of whether CT scans or the real teeth were scored. Only when assessing the difference in signal between the beginning and the end of the experiment did relevant, significant diet-specific effects emerge. Diets containing lower phytolith content caused a more pronounced change in mesowear towards sharper cusps/higher reliefs, while the feed containing sand did not result in more extreme changes in mesowear when compared with the same feed without sand. Our experiment suggests that the formation of a stable and hence reliable mesowear signal requires more time to develop than 6 months.

Earliest evidence for equid bit wear in the ancient Near East: The "ass" from Early Bronze Age Tell es-Sâfi/Gath, Israel.

Analysis of a sacrificed and interred domestic donkey from an Early Bronze Age (EB) IIIB (c. 2800-2600 BCE) domestic residential neighborhood at Tell es-Sâfi/Gath, Israel, indicate the presence of bit wear on the Lower Premolar 2 (LPM2). This is the earliest evidence for the use of a bit among early domestic equids, and in particular donkeys, in the Near East. The mesial enamel surfaces on both the right and left LPM2 of the particular donkey in question are slightly worn in a fashion that suggests that a dental bit (metal, bone, wood, etc.) was used to control the animal. Given the secure chronological context of the burial (beneath the floor of an EB IIIB house), it is suggested that this animal provides the earliest evidence for the use of a bit on an early domestic equid from the Near East.

Equine cheek teeth occlusal fissures: Prevalence, association with dental wear abnormalities and occlusal angles.

BACKGROUND: Fissures of the occlusal surface of equine cheek teeth are commonly encountered during oral examination but their aetiology is unknown. OBJECTIVES: To examine the prevalence and characteristics of occlusal fissures in cadaver teeth. It is hypothesised that their prevalence is influenced by masticatory forces. Consequently, their possible association with wear disorders and occlusal angles were examined. STUDY DESIGN: Cross-sectional survey. METHODS: The dental abnormalities and occlusal fissure findings in the cheek teeth of 143 cadaver heads were recorded. The cheek teeth occlusal angles were measured using the stiff-hinge technique. Multiple regression analyses were performed to establish possible relationships between age, sex, dental wear, occlusal angle and fissure prevalence. RESULTS: Occlusal fissures were found in 103/143 (72%) heads. Sex and age were determining factors in the prevalence of fissures. A similar prevalence was found in mandibular (54.1%) and maxillary teeth (45.9%, OR = 1.10; 95% CI = 0.95-1.29, P = 0.2). Mandibular fissures were more commonly located on the buccal aspect (OR = 1.42; 95% CI = 1.16-1.65, P < 0.001), whereas for maxillary fissures there was no difference in prevalence between palatal and buccal aspects (OR = 1.19; 95% CI = 0.97-1.46, P = 0.1). Two main fissure types were identified. Type 1a fissures were the most prevalent type (39.5%). No significant correlation was found between the presence of wear abnormalities or the occlusal angle of cheek teeth, and the prevalence of fissures. MAIN LIMITATIONS: No dental histories were available. CONCLUSION: Equine cheek teeth show a high prevalence of occlusal fissures. Despite some evidence of predilection sites on the tooth surface that might indicate a mechanical aetiology for these lesions, no associations were found with wear abnormalities or occlusal angles of affected cheek teeth. Further histological and ultrastructural studies are warranted to elucidate their aetiology and possible role in other dental diseases.

Tooth Wear Inclination in Great Ape Molars.

Primate dietary diversity is reflected in their dental morphology, with differences in size and shape of teeth. In particular, the tooth wear angle can provide insight into a species' ability to break down certain foods. To examine dietary and masticatory information, digitized polygon models of dental casts provide a basis for quantitative analysis of wear associated with tooth attrition. In this study, we analyze and compare the wear patterns of Pongo pygmaeus, Gorilla gorillagorilla and Pan troglodytes schweinfurthii lower molars, focusing on the degree of inclination of specific wear facets. The variation in wear angles appears to be indicative of jaw movements and the specific stresses imposed on food during mastication, reflecting thus the ecology of these species. Orangutans exhibit flatter wear angles, more typical of a diet consisting of hard and brittle foods, while gorillas show a wear pattern with a high degree of inclination, reflecting thus their more leafy diet. Chimpanzees, on the other hand, show intermediate inclinations, a pattern that could be related to their highly variable diet. This method is demonstrated to be a powerful tool for better understanding the relationship between food, mastication and tooth wear processes in living primates, and can be potentially used to reconstruct the diet of fossil species.