Dilated Odontoma Arising in the Mandibular Third Molar Germ: Report of a Case of an Unusual Lesion in an Uncommon Site

Dilated odontoma is the most severe variant of dens invaginatus. It is extremely uncommon in the posterior mandible. It is thought to originate during the morpho-differentiation stage of dental development. However, its etiology and pathogenesis remain obscure. We report here the clinical and pathologic findings of an incidentally discovered dilated odontoma arising in the left third mandibular molar germ of an 11-year-old male and a review of the pertinent literature. As dilated odontoma is not established as an independent entity in the current WHO classification of odontogenic tumors and is the result of a well-established developmental anomaly of the tooth (that is, the invagination of the enamel organ into the dental papilla), it should be better identified as dilated dens invaginatus.

Avaliação quantitativa da expressão da proteína PCNA e das AgNORs em ameloblastomas

In order to assess the proliferative behaviour of the ameloblastoma epithelium nine cases of this neoplasm were retrieved from the files of the Oral Pathology Service laboratory of Rio Grande do Sul Federal University School of Dentistry. Two proliferation marker techniques were employed: the AgNor - argyrophilic nucleolar organizer regions staining and the proliferation cell nuclear antigen (PCNA) immunohistochemical assessment technique. Each case was submitted to a quantitative and comparative statistical analysis of the results obtained for the two techniques. The conclusion arrived at shows ameloblastoma presenting benign behavior, an average AgNOR index of 1.612, and a PCNA proteindependent proliferative activity with average immunoreactivity of 51.61%. The histological patterns analyses of the neoplastic epithelial component demonstrates that cells resembling pre-ameloblasts have obtained figures statistically higher to those obtained for cells resembling the stellate reticulum of the enamel organ, in both techniques employed. Therefore, it might be inferred that cells resembling pre-ameloblasts hold the proliferative potential of ameloblastomas and are probably responsible for the growth characteristics and infiltrative ability of this tumour.

An unusual case of incomplete healing with intraosseous fibrous scar formation in the surgically enucleated site associated with a Type II dens invaginatus: A 4-year follow-up case report

Dens invaginatus is a developmental deformation with varying anatomical features, caused by the envelopment of the enamel organ and/or the Hertwig’s epithelial root sheath within the tooth before calcification completes, increasing the vulnerability of pulpal and periodontal inflammation, posing challenges to treatment, and adequate healing. Cell rest of Malassez, remnants of enamel organ or root sheet may cause cystic lesion formations, also hinder the normal healing process and form a fibrous scar. Intraosseous fibrous scar is a result of incomplete wound healing after periradicular surgery which mimics an asymptomatic residual cyst clinically and radiographically. We herein report a case of a surgically managed an immature maxillary lateral incisor affected with Type II dens invaginatus associated with incomplete periradicular healing presented as intraosseous fibrous scar with a persistent well-defined radiolucency between the healthy trabecular bone. The regular clinical and radiographic follow-up records the asymptomatic endodontically treated dens invaginatus with an intact lamina dura and regular healing trabecular bone pattern. Its 4 years of post-operative evaluation has been presented. Features of this case, causes of such incomplete healing, diagnosis, treatment line, prognosis, and the dilemma of the clinician are discussed together with its probable implications.

Application of cryopreservation to tooth germ transplantation for root development and tooth eruption

We cryopreserved mouse tooth germs with widely open cervical margins of the enamel organ to overcome difficulties in cryoprotectant permeation and tested their efficacy by transplanting them into recipient mice. The upper right first molar germs of 8-day-old donor mice were extracted and categorized into the following four groups according to cryopreservation time: no cryopreservation, 1 week, 1 month, and 3 months. The donor tooth germs were transplanted into the upper right first molar germ sockets of the 8-day-old recipient mice. The upper left first molars of the recipient mice were used as controls. The outcome of the transplantation was assessed at 1, 2, and 3 weeks after transplantation. Stereomicroscopic evaluation revealed that most of the transplanted teeth erupted by 3 weeks after transplantation. Micro-computed tomography analysis revealed root elongation in the transplanted groups as well as in the controls. There was no significant difference between the cryopreserved and non-cryopreserved transplanted teeth, but the roots of the cryopreserved teeth were significantly shorter than those of the control teeth. Histological examination revealed root and periodontal ligament formations in all the transplanted groups. These results suggest that the transplantation of cryopreserved tooth germs facilitates subsequent root elongation and tooth eruption.

A Case of Ameloblastic Fibrodentinoma in the Posterior Maxilla

Ameloblastic fibrodentinoma (AFD) is a rare tumor with an incidence rate of less than 1%. When lesion with the histomorphology of ameloblastic fibroma(AF), which is true neoplasms, form dysplastic dentin, and had been referred to as AFD. It histologically consists of odontogenic ectomesenchyme resembling the dental papilla, epithelial strands, and nests resembling dental lamina and enamel organ with dentin formation. Although newly categorized as an odontoma by the WHO in 2017, this lesion was previously referred to as a rare odontogenic tumor by the WHO in 2005. Objective: We aim to summarize our case with other previous case reports considered to be equivalent to the conventional WHO classification of AFD. Case Report: An 8-year-old girl presented to our hospital complaining of delayed eruption of a tooth. Computed tomography showed an odontoma-like radiopacity in a unilocular radiolucent lesion sized approximately 20 mm. The lesion was extracted under general anesthesia and histopathologically exhibited AFD. Herein, we report a rare case of AFD in the maxilla. Conclusion: Although this lesion deviates from the concept of disease as an odontogenic tumor, it is hoped that clinically sufficient follow-up is required and more similar cases will accumulate as independent tumors, rather than simply being recognized as developmental odontomas

Clinical Guideline for Diagnosis and Treatment of Dens Invaginatus

The invaginated tooth, also called dens invaginatus or dens in dente, is a rare anomaly affecting human dentition, resulting from invagination of enamel organ into the dental papilla.Maxillary lateral incisors are the most commonly affected teeth. The accentuated pit within the DI accumulates debris causing prompt initiation and progression of dental caries with subsequent involvement of the pulp, resulting in periapical pathology. Invagination depth varies from a slight enlargement of the cingulum to an extended invagination into the apex. This anatomic variation means a true clinical challenge because of its complex anatomy. Early diagnosis is then essential to avoid any periodontal complications.This study aims to review: etiopathogenics, classification, elements of the diagnosis and provides guidelines for the management of dens invaginatus cases in clinic that provide hope for teeth that could not be saved before.

The Sonic Hedgehog–Patched–Gli Signaling Pathway Maintains Dental Epithelial and Pulp Stem/Progenitor Cells and Regulates the Function of Odontoblasts

This study aimed to elucidate the role of the Sonic hedgehog (Shh)–Patched (Ptch)–Gli signaling pathway in maintaining dental epithelial and pulp stem/progenitor cells and regulating the function of odontoblasts. Doxycycline (dox)-inducible histone 2B (H2B)–green fluorescent protein (GFP) transgenic mice ingested dox at prenatal embryonic days 14.5 or 15.5 and their offspring were collected from postnatal day 1 (P1) to week 3 (P3W). Immunohistochemistry for Gli1, Ptch1, and Ptch2 and in situ hybridization for Shh and Ptch1 were conducted. Mandibular incisors of postnatal day 2 H2B-GFP transgenic and wild-type mice were cultivated in a nutrient medium with Shh antibody for 4 days and subsequently processed for immunohistochemistry for Sox2. In molars, dense H2B-GFP-label-retaining cells (H2B-GFP-LRCs) were densely distributed throughout the dental pulp during P1 to postnatal week 2 (P2W) and decreased in number by postnatal P3W, whereas the number of dense H2B-GFP-LRCs in the subodontoblastic layer increased in number at P2W. Gli1+ and Pthc1+ cells were distributed throughout the enamel organ and dental pulp, including the odontoblast and subodontoblastic layers. Shh mRNA was expressed in the inner enamel epithelium and shifted into odontoblasts after dentin deposition. Ptch1 mRNA was expressed in the inner enamel epithelium and cuspal pulpal tissue on P1 and decreased in intensity from postnatal week 1 to P3W. In incisors, the apical bud contained H2B-GFP-LRCs, Gli1+ cells, and Ptch1+ cells. The addition of Shh antibody to explants induced a decrease in the number of Sox2+ cells due to the increase in apoptotic cells in the apical bud. Thus, the Shh–Ptch–Gli signaling pathway plays a role in maintaining quiescent adult stem cells and regulating the function of odontoblasts.

Management of Dentigerous Cyst: A Review Article

Introduction: Dentigerous cyst is a pathological epithelial cavity that surrounds an unerupted tooth crown. Dentigerous cysts are usually associated with impacted teeth, mandibular third molars, first and second premolars and canines. Dentigerous cysts can occur at any age, but most cases of these cysts occur at the age of approximately 20 years. Men are affected more often than women. Purpose.To find out how the mechanism of dentigerous cysts. The cyst cavity is lined with epithelial cells derived from the epithelial enamel that is reduced from the tooth-forming organs. According to its pathogenesis, the pressure exerted by an erupted tooth on the follicle can block venous flow leading to accumulation of exudate between the reduced enamel epithelium and the crown of the tooth. These cysts are mostly due to fluid accumulation either between the reduced enamel epithelium and the enamel or between the layers of the enamel organ. This fluid accumulation occurs as a result of the pressure exerted by the erupting tooth on the affected follicle, which blocks venous flow, thus inducing rapid transudation of serum in the capillary walls. Discussion: The expansion of the dentigerous cyst causes the release of bone resorbing factor and an increase in the osmolarity of the cyst fluid as a result of the discharge of inflammatory cells, the discharge of residual epithelial enamel and tooth enamel, and desquamation of epithelial cells into the lumen of the cyst. In theory, the fluid will cause cystic proliferation. because the hyperosmolar content produced by cellular breakdown and cell products causes an osmotic gradient to pump fluid into the lumen of the cyst or it can also be said that an increase in the osmolarity of cyst fluid is the result of a shortcut to inflammatory cells and desquamation of epithelial cells into the lumen of the cyst resulting in a dentigerous cyst. Conclusion: The dentigerous cysts that surround the unerupted dental crowns are caused by the accumulation of fluid either between the reduced enamel epithelium or between the layers of the enamel organs. Dentigerous cysts can cause infection, pain, swelling, root dislocation, and resorption of adjacent tooth roots.