Associations between 44 nonmetric permanent dental traits or anomalies with skeletal sagittal malocclusions and sex, besides correlations across the variations or abnormalities

Abstract

Introduction Nonmetric dental traits and the shape, size, or number of dental anomalies are essential to various dental fields such as orthodontics, dental anatomy, anthropology, pathology, and forensic dentistry. Nonetheless, many are not well assessed worldwide. Moreover, most studies are limited to a few nonmetric traits. Therefore, we aimed to examine several nonmetric dental traits/anomalies. Methods In this cross-sectional epidemiological study, ~ 9000 permanent teeth of 331 non-syndromic orthodontic patients (radiographs and dental casts) with fully erupted permanent dentitions (except the third molars and some cases of a few teeth missing or excluded) were evaluated by two observers, each twice, in search for 62 nonmetric traits/shape-number-size anomalies. The traits/anomalies of interest were supernumerary, microdontia, peg-shaped lateral, shovelings, talon cusps, Carabelli cusps, fifth/sixth/seventh cusps on the molars, hypocone/hypoconulid absence, protostylid, deflecting wrinkle‏s, canine mesial ridge, distal trigonid crest, canine distal accessory ridge, accessory cusps in the mesial/distal marginal ridges, mesial/distal accessory ridges, and accessory cusps in the lingual of the mandibular premolars and second molars). Data, at both patient/quarter levels, were analyzed regarding the associated factors (skeletal Angle classes, crowding, sex, and sides) as well as the correlations among traits, using the chi-square test and Spearman correlation coefficient (α = 0.05). Results Prevalence rates of 44 traits/anomalies were reported (18 out of the 62 searched traits/anomalies were not found [prevalence = 0%]). Microdontia and accessory cusps on the marginal ridge of the second mandibular molars were significantly more common in women (P < 0.05). Canine talon cusp and distal trigonid crest of the second mandibular molars were more prevalent in men (P < 0.05). Shoveling, canine talon cusp, canine distal accessory ridge, and accessory cusp in the first premolar might be more prevalent in skeletal Angle class II; whereas, accessory cusp in the mesial marginal ridge of the second premolar might be rather more prevalent in skeletal Angle class I (P < 0.05). Few dental traits were positively and moderately or strongly correlated with each other (Spearman Rho ≥ 0.4, P < 0.0005). Conclusions Sex dimorphism was uncommon in nonmetric dental traits/anomalies. Skeletal malocclusions may be associated with a few dental abnormalities or variations.

Comprehensive Oral Diagnosis and Management for Women with Turner Syndrome

“…Only 7% of TS subjects did not present any of the tooth anomalies. Microdontia, a common size anomaly reported in the TS cohort, was recently reported to be slightly more prevalent in women [52]. However, no other non-metrical dental anomalies associated with sexual dimorphism were found, either in our sample subjects or in their first-degree relatives.…”

Dental Anomalies: An Identification Marker in Forensics

“…Similar to Angadi and Acharya (2008), who reported that 34% of upper second molars in their previously stated Indian sample (n=100) displayed hypocone absence, three-cusp upper second molars were found in 32.8% of the Ajnala teeth. Once more, compared to reports for Western Eurasians (17%), sub-Saharan Africans (6.7%), and North-eastern Asians (12.7%), this frequency is distinct and greater [2].…”

“…Nonmetric dental traits are traits that can be passed down genetically but exhibit diversity in expression both within and between populations [1]. Inadequate historical records about previous armed conflicts, natural or mass disasters that produced such human remains, severe damage or fragmentation, missing elements, and poor preservation all make the process of forensic anthropological identification of commingled human remains recovered from diverse contexts more difficult and complex [2]. An essential part of biological anthropology and forensic anthropology, non-metric dental features provide unique insights into the evolutionary history and genetic makeup of the human population.…”

Morphometric variations and nonmetric anatomical traits or anomalies of the primary molar teeth, plus the molars' size thresholds for sex identification

“…Nevertheless, due to the difficulty of this task, most previous studies were likewise limited to dental populations. Another limitation of this study was the lack of assessment of the role of age; we discarded the individuals’ age data because (1) age has no role in non-metric traits [ 18 ], and (2) its very limited effect on metric dental sizes, if any, is extremely small and may appear after many years, probably due to attrition [ 9 , 10 ] which might be absent in a very short life span of primary dentition, especially given the presence of generalized interdental spacing between the primary teeth. Therefore, age was not considered a variable within this sample of children with primary teeth and thus having very small ranges of age.…”

“…Sex identification is an important step in reconstructing the biological profile of individuals with unknown identities in forensic medicine [ 5 – 8 ]. The metric sizes and non-metric features of the teeth may provide information about the sex of individuals [ 9 , 10 ]. There are studies that show differences in metric characteristics of permanent teeth in women and men [ 5 – 7 , 11 ].…”