The prevalence and distribution of cervical enamel projections reaching into the bifurcation on human molars

Mandibular Carnassial Tooth Malformations in 6 Dogs-Micro-Computed Tomography and Histology Findings

Objective: To document the clinical, radiographic, and histological characteristics of mandibular first molar teeth with developmental abnormalities previously attributed to dens invaginatus and enamel pearls in dogs. Materials and Methods: Affected mandibular first molar teeth from dogs were evaluated grossly and via intraoral radiography. Endodontically and/or periodontally compromised teeth were extracted and subjected to some combination of micro-computed tomography, histopathology, and immunohistochemistry with anti-amelogenin antibody. Results: Six dogs with developmental abnormalities of mandibular first molar teeth were identified, representing 11 affected teeth. The condition was bilateral in 5 dogs, while in 1 dog, only one mandibular first molar tooth was present. Patient weight ranged from 1.7 to 6 kg (median = 4.09 kg). On intraoral radiographs, root convergence or parallelism was noted in 6 of 11 teeth, and root dilaceration was noted in 3 of 11 teeth. Eight teeth required extraction due to periapical lucencies or periodontitis. On micro-CT, the abnormal teeth were characterized by the presence of abnormal, heterogenous hard tissue with beam attenuation characteristics midway between that of enamel and dentin. Enamel fissures were identified in 4 of 8 teeth, while ectopic radicular enamel was identified in 2 of 8 teeth. The abnormal tissue was traversed by channels measuring 20-40 μm in diameter. Channels communicated with the enamel fissures in 2/8 teeth, the furcation in 2/8 teeth and the pulp in 4/8 teeth. The abnormal tissue was frequently surrounded by disorganized dentin. Histologic features of enamel and dentin were absent from the abnormal tissue and immunohistochemistry to detect amelogenin in the abnormal tissue was negative in all samples. Conclusion: The dental abnormalities described here correspond to a previously unrecognized developmental abnormality involving the mandibular first molar teeth in dogs. The developmental origin of the abnormal tissue could not be ascertained, and further investigations are required to determine the mode of formation, origin of the abnormal tissue, and factors associated with development. These developmental abnormalities more closely resemble molar-incisor malformation, rather than dens invaginatus or enamel pearls as described in humans. The authors propose that affected mandibular first molar teeth simply be referred to as having carnassial tooth malformations.

Enamel pearls: Their occurrence in recent human populations and earliest manifestation in the modern human lineage

OBJECTIVE

To document and describe the occurrence of an enamel pearl on the distal root surface of the maxillary M3 of the fossil hominin specimen from Florisbad, South Africa that is dated to ca. 259,000 years B.P., and is an early representative of Homo sapiens or as a member of the evolutionary line that was directly ancestral to modern humans.

DESIGN

The molar was examined macroscopically and by micro-computed tomography (μCT) to enable accurate measurement and visualization of the structure of the enamel pearl.

RESULTS

The single pearl has a diameter of 0.97 mm; it is a Type 2 "composite" pearl comprising an enamel cap and dentine core without pulp chamber involvement. The size of the Florisbad pearl falls within or just below the size ranges of this anomaly in modern human samples. Type 2 pearls are most commonly encountered in recent human populations, and the location of the pearl on the distal root surface of the Florisbad M³ is consistent with its most frequent location in recent humans. Pearls in recent human populations affect between 0.2-4.8% of individuals, and 1.7-6.8% of permanent molars. Pearls have been documented in several prehistoric human dentitions, and all examples are less than 4000 years old.

CONCLUSIONS

Enamel pearls have been associated with periodontal disease, but it is not possible to relate its presence to the advanced periodontal inflammation and alveolar bone loss in the Florisbad fossil. Florisbad presents the earliest evidence of this anomaly in the fossil record pertaining to modern humans.

Prevalence of enamel projections and its co-relation with furcation involvement in maxillary and mandibular molars: A study on dry skull

Background:

The objectives of this study were to investigate the incidence of cervical enamel projection (CEP) in molars of Indian dry human skulls and to evaluate its relationship with furcation involvement (FI).

Materials and Methods:

The material consisted of 944 upper and lower first, second and third permanent molars from 89 Indian dry human skulls. CEPs were investigated from the buccal aspect of the tooth and classified according to a system describeddescribed by Masters and Hoskins. FI was measured horizontally from the buccal aspect into the furcation with a graduated probe to the nearest millimeter. Any measurement ≥2 mm was considered to have positive FI.

Results:

The results showed that CEPs was found more frequently in the mandibular than in the maxillary molars (2:1). The highest incidence of CEP was found in the mandibular second molar (14.7%) followed by the maxillary second molar (14.6%). The mandibular third molar showed the lowest incidence (5.5%). The association between CEP and FI (87.5%) was statistically significant. This favors the view of the possible role played by such anomalies in the progression of periodontal diseases. CEP in male skulls (77.4%) was significantly more prevalent than in female skulls (20.4%). No significant difference was found between the right and left side of maxillary and mandibular teeth with CEP and FI.

Conclusion:

The findings suggested the role of CEPs as a local contributing factor in localized chronic periodontitis and FI in molars. Detailed examination as well as early diagnosis of periodontal disease at the region of furcation is clinically very important.

Prevalence of enamel pearls in teeth from a human teeth bank

Enamel pearls are anatomical structures that can bring about clinical implications if associated with the retention of plaque, in turn resulting in periodontal disease. In an attempt to avoid periodontal disease, the removal and treatment of these enamel pearls, may be a necessity in some circumstances. A total of 45,785 extracted teeth from a human teeth bank were analyzed for the presence of enamel pearls. The most prevalent anatomical location of enamel pearls was the permanent maxillary first and second molar region. An association between the prevalence of enamel pearls and dental class (P < 0.001) was observed, most frequently in the maxillary molars. In the maxillary molars, the most prevalent anatomical location of enamel pearls in the first and second molars was the furcation between the distobuccal and palatal roots. Enamel pearls are a common observation in molars in general, but are most commonly found in maxillary molars.

Multiple enamel pearls in two siblings detected by volumetric computed tomography

A rare case of multiple enamel pearl formation is presented involving the maxillary molars in two siblings incidentally recognized during volumetric CT examination. Although the pathogenesis of ectopic enamel formation is not known, possible mechanisms to account for this phenomenon are discussed in the context of current knowledge regarding root genesis. The radiographic presentation of enamel pearls and its clinical significance is also discussed. The observation of multiple enamel pearls in two siblings raises the possibility of a hereditary association in the formation of enamel pearls.