Modular Wear Facet Nomenclature for mammalian post-canine dentitions

Abstract

Dental wear facets on the occlusal surface of premolars and molars are traces of their main function, the mastication and therefore reflect masticatory movements and also paramasticatory (i.e. non-dietary use of teeth) behavior. Here we present the Modular Wear Facet Nomenclature applicable to most mammalian dentitions. Topographic positions of wear facets in relation to the major cusps and crests of the teeth are used to designate the areas of the occlusal surface the facets occupy (e.g. their mesial, distal, lingual, or buccal position). Previous published systems for labeling wear facets have been inconsistent with each other. Therefore, we provide a synoptic review of the most widely-used terminologies, and introduce the alternative Modular Wear Facet Nomenclature. This nomenclature aims to overcome the difficulties caused by the existing inconsistent wear facet terminologies. Our new approach is applicable to dentitions where the occlusal morphology does not change significantly for most of the lifetime of the animal. In those dentitions, the primary occlusal surfaces are not significantly modified as wear facets become more extensive with wearing. This appears to be a common pattern in pre-tribosphenic, tribosphenic molars, and the teeth derived from tribosphenic precursors (e.g. bunodont molar morphologies). In teeth where the secondary occlusal surface is functionally intensely modified (i.e. high-crowned and evergrowing teeth with large areas of dentine exposed) any facet labeling system appears to be challenging, since the identification of individual facets is blurred and their spatial position may be indeterminable.

Overcoming sampling issues in dental tribology: Insights from an experimentation on sheep

“…The lack of any significant differences between teeth from the same tooth row suggests that dietary differences will still be able to be highlighted when using first, second, and third molars together. We have also highlighted the misuse of the combination of upper and lower dental facets, assumed to be homologous (or antagonist sensu Schultz et al, 2017) because occluding during the dental shearing phase I (Janis, 1990), but actually involved in different ways during the phase I. Thus, here, we investigated the effects of grouping altogether these two types of dental facets from upper and lower molars, a habit widely used by paleoecologists to increase sample size and supposedly strengthen their analysis.…”

Dust affects chewing efficiency and tooth wear in forest dwelling Western chimpanzees (Pan troglodytesverus)

“…Food processing generates considerable mechanical stress on teeth and thus modifies the occlusal surface during an individual's life, leading to so‐called wear facets. These facets develop during mastication either as the result of tooth‐tooth contacts (attrition) or through tooth‐substrate‐tooth contacts (abrasion; for a review of terminology see Schultz et al ()). Abrasives that are intrinsic to the food (e.g., phytoliths) and those that are extrinsic (e.g., grit, dust) have both been discussed as causes for tooth wear (Calandra, Schulz, Pinnow, Krohn, & Kaiser, ; Lucas et al, , ; Massey, Ennos, & Hartley, ; Sanson, Kerr, & Gross, ).…”

Dentition and body condition: tooth wear as a correlate of weight loss in roe deer

“…The schematization was based on the shape of the occlusal surface. When molariform teeth are unworn, this surface is characterized by three valleys in premolars and cusps separated by deep infundibula in molars (Table 1 ; see [ 12 , 25 , 60 – 63 ] for nomenclature and terminology of morphotypes of the occlusal surface). The progressive wear of the crown determines the reduction in the number of valleys and the gradual fusion of the cusps and the disappearance of the infundibula (Table 1 ; see [ 12 , 25 , 60 – 63 ]).…”

“…When molariform teeth are unworn, this surface is characterized by three valleys in premolars and cusps separated by deep infundibula in molars (Table 1 ; see [ 12 , 25 , 60 – 63 ] for nomenclature and terminology of morphotypes of the occlusal surface). The progressive wear of the crown determines the reduction in the number of valleys and the gradual fusion of the cusps and the disappearance of the infundibula (Table 1 ; see [ 12 , 25 , 60 – 63 ]). Taking this into account, the wear process has been outlined in stages, each of which is identified by a recognizable morphotype depending on the number of valleys for the premolars and the fusion of cusps for molars (see Table 1 for major details about the recognizable morphotypes).…”

“…See Part b for a comprehensive description of each wear stage and score). See [ 12 , 25 , 60 – 63 ] for nomenclature and terminology of morphotypes of the occlusal surface Part b: Wear scoring system. Scores assigned to the progressive wearing stages of the cheek teeth based on objectively described morphotypes being either present or absent in each tooth.…”