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Statement of the Problem: Gubernacular canal (GC) is a canal that extends from the follicle of unerupted permanent teeth to the alveolar bone crest filled with remnants of the dental lamina. This canal is thought to guide tooth eruption and be related to some pathologic conditions. Purposes: This study aimed to determine the presence of GC and its anatomical characteristics in teeth, which failed to erupt normally on cone beam computed tomography (CBCT) images. Materials and Method: This cross-sectional study evaluated CBCT images of 77 impacted permanent and supernumerary teeth obtained from 29 females and 21 males. The frequency of GC detection, its location in relation to the crown and root, the anatomical surface of the tooth from which the canal has originated, and the adjacent cortical table to which the canal opens, along with the length of the GC were studied. Results: GC was observed in 53.2% of teeth. The anatomical tooth aspect of origin was occlusal/ incisal in 41.5% and crown in 82.9% of teeth. Moreover, 51.2% of GCs opened in palatal/lingual cortex and 63.4% of canals were not located along the tooth long axis. Finally, GC was detected in 85.7% of teeth undergoing the crown formation stage. Conclusion: Although GC was introduced as an eruption pathway, this canal is also present in impacted teeth. This means that presence of this canal does not promise the normal eruption of tooth and the anatomical characteristics of GC may influence the eruption process. [ABSTRACT FROM AUTHOR]

An ameloblastoma is a benign, yet locally aggressive odontogenic tumour. The vast majority (80%) of ameloblastomas arise in the mandible, and unicystic ameloblastomas are commonly found in relation to an unerupted lower third molar. We present the case of a 39-year-old patient with an incidental finding of an enlarged dental follicle around an unerupted lower third molar that progressed to an extensive unicystic ameloblastoma. This ameloblastoma was decompressed and marsupialized before enucleation to reduce the risk of pathological fracture due to the extensive size of the tumour. [ABSTRACT FROM AUTHOR]

Ki67 expressions are the most widely used markers to show the pathologic proliferation and early-stage tumoral alterations in vital tissues. This study aimed to compare the expressions of Ki67 protein between smokers' and nonsmokers' pericoronal follicles of asymptomatic impacted lower third molars (ILTMs), thirty-seven specimens of DFs associated with impacted mandibular third molars fully covered by mucosa or bone were surgically removed from 37 patients. The patients were divided into 2 age groups. 19 of thirty-seven DFs were between (18-24) years (Group 1) and 18 were (< 24) years (Group 2). Ki-67 immunostaining was evaluated in the epithelial component of the all DFs, independent-samples t-test analyses were conducted with SPSS 10.0 with statistical significance set at a P-value equal to 5%. There were statistically significant differences in the mean values of KI-67 (%) expression between the non-smokers group and the smokers group regardless of the patient's age group The values of KI-67 (%) expression in the non-smokers group were smaller than in the smokers group, in both the( 18-24) age group and the( 24 >) year age group. Separately in the research sample. this study showed that DFs of smokers have higher Ki67 expressions than nonsmokers follicles. [ABSTRACT FROM AUTHOR]

Lesions arising from odontogenic tissues of the jaws vary from very common to very rare. Some, such as radicular cysts, form a routine part of the diagnostic workload for histopathologists who report specimens from the head and neck, but many other lesions are rarely seen and can cause significant diagnostic difficulty for the non-specialist. These issues are compounded by the vagaries of dental disease (and terminology used by dentists and oral surgeons) and issues in the interpretation of radiographic images, which can be crucial to making a correct diagnosis. In this review article, we will discuss a number of areas of diagnostic difficulty, largely based on the authors experience in receiving tertiary referrals. This will focus on practical advice to help avoid the pitfalls in the diagnosis of odontogenic lesions. [ABSTRACT FROM AUTHOR]

Abstract We have an interest in the cellular response to mechanical stimuli, and here describe an in-vitro method to examine the response of cells cultured in a three-dimensional matrix to mechanical compressive and tensile stress. Synthetic aliphatic polyester scaffolds coated with 45S5 bioactive glass were seeded with human dental follicular cells (HDFC), and attached to well inserts and magnetic endplates in six well palates. Scaffolds were subjected to either cyclic 10% tensile deformation, or 8% compression, at 1 Hz and 2 Hz respectively for 6, 24 or 48 h, by uniaxial motion of magnetically-coupled endplates. It was possible to isolate high quality mRNA from cells in these scaffolds, as demonstrated by high RNA integrity numbers scores, and ability to perform meaningful cRNA microarray analysis, in which 669 and 727 genes were consistently upregulated, and 662 and 518 genes down regulated at all times studied under tensile and compressive loading conditions respectively. MetaCore analysis revealed the most regulated gene ontogenies under both loading conditions to be for: cytoskeletal remodelling; cell adhesion-chemokines and adhesion; cytoskeleton remodelling-TGF WNT and cytoskeletal remodelling pathways. We believe the method here described will be of value for analysis of the cellular response to cyclic loading. Graphical abstract fx1 Highlights • Description of an in-vitro method to examine the response of cells to cyclic mechanical compressive or tensile stress. • Use of synthetic aliphatic polyester 3D scaffolds which were seeded with human dental follicular cells. • High quality mRNA isolated from cells stimulated by this method, permitting meaningful cDNA microarray analysis. [ABSTRACT FROM AUTHOR]

Abstract Objectives Odontogenesis is dependent on serial temporal and spatial epithelial-mesenchymal interaction. Multiple signaling networks have been identified in the inductive interactions of odontogenesis at the early stage. Technical obstacles and heterogeneity of the dental follicle (DF), which is the origin of the majority of periodontal tissues, have hindered the clarification of the molecular blueprint in early periodontal tissue development. This has in turn hindered studies of new/effective periodontal regeneration therapy. In this study, we comparatively analyzed the gene expression profiles of DF at E17 (when DF cells are histologically recognized) and PN2 (the initiation of periodontal development). Methods Gene expression profiles of DF at E17 and PN2 were assessed by the combined use of laser capture microdissection and microarray. Results Comparative gene expression analysis of DF at E17 and PN2 during periodontal development revealed > 2-fold up-regulation and down-regulation of 2519 and 5060 genes, respectively. Bioinformatic analysis of the selected genes revealed that the temporally changed genes were mostly enriched in GO terms relative to the vasculature system, and were sometimes linked to multiple processes. RT-qPCR was used to verify the microarray data. Conclusions The delineation of the differential gene expressions between pre- and post-natal developmental stages of DF in vivo will increase the understanding of periodontal tissue development. Highlights • LCM and Microarray were used for the gene expression profiles of dental follicle at two stages. • Comparative analysis of the two stages identified 2519 up- and 5060 down-regulated genes. • Bioinformatic analysis on the temporally changed genes revealed the enriched GO terms. • RT-qPCR results confirmed the microarray data. [ABSTRACT FROM AUTHOR]

Odontoameloblastomas (previously incorporated within ameloblastic odontomas) are matrix-producing odontogenic mixed tumors and are closely related in histologic appearance to the 2 other types of matrix-producing odontogenic mixed tumors: odontomas and ameloblastic fibro-odontomas. The presence or absence of intralesional, induced non-neoplastic tissue must be accounted for in the diagnosis. Herein we describe a naturally occurring odontoameloblastoma with extensive chondroid cementum deposition in a guinea pig (Cavia porcellus). Microscopically, the mass featured palisading neoplastic odontogenic epithelium closely apposed to ribbons and rings of a pink dental matrix (dentinoid), alongside extensive sheets and aggregates of chondroid cementum. The final diagnosis was an odontoameloblastoma given the abundance of odontogenic epithelium in association with dentinoid but a paucity of pulp ectomesenchyme. Chondroid cementum is an expected anatomical feature of cavies, and its presence within the odontoameloblastoma was interpreted as a response of the ectomesenchyme of the dental follicle to the described neoplasm. Our case illustrates the inductive capabilities of odontoameloblastomas while highlighting species-specific anatomy that has resulted in a histologic appearance unique to cavies and provides imaging and histologic data to aid diagnosis of these challenging lesions. [ABSTRACT FROM AUTHOR]

Aim: To histologically evaluate dental follicles of impacted third molars with no radiographic evidence of pathology. Methods: We carried out both a quantitative and qualitative analysis of pericoronal follicles removed from impacted third molars and investigated the association with clinical data. The sample included 36 extracted dental follicles of impacted third molars, obtained from 28 patients, which presented with no radiographic evidence of pathologies. Results: None of the follicles analyzed showed any pathological entity. The epithelial lining was observed in 61.1% of samples, being identified as reduced enamel epithelium. We found a significant relation between the the presence of inflammatory infiltrate and the group aged over 21 years (64.3%; p<0.05). Conclusions: Considering the absence of pathological lesions, we suggest that the removal of impacted third molars, particularly in young-aged individuals, should be carefully indicated. [ABSTRACT FROM AUTHOR]

Introduction Dental follicle stem cells (DFSCs) possess neurogenic potential because they originate from the embryonic neural crest. This study investigated whether neural differentiation of DFSCs can be enhanced by culture on decellularized matrix substrata (NSC-DECM) derived from neurogenesis of human embryonic stem cells (hESCs). Methods The hESCs were differentiated into neural stem cells (NSCs), and NSC-DECM was extracted from confluent monolayers of NSCs through treatment with deionized water. DFSCs seeded on NSC-DECM, Geltrex, and tissue culture polystyrene (TCPS) were subjected to neural induction during a period of 21 days. Expression of early/intermediate (Musashi1, PAX6, NSE, and βIII-tubulin) and mature/late (NGN2, NeuN, NFM, and MASH1) neural markers by DFSCs was analyzed at the 7-, 14-, and 21-day time points with quantitative real-time polymerase chain reaction. Immunocytochemistry for detection of βIII-tubulin, PAX6, and NGN2 expression by DFSCs on day 7 of neural induction was also carried out. Results Quantitative RT-PCR showed that expression of PAX6, Musashi1, βIII-tubulin, NSE, NGN2, and NFM by DFSCs was enhanced on NSC-DECM versus either the Geltrex or TCPS groups. Immunocytochemistry showed that DFSCs in the NSC-DECM group displayed more intense staining for βIII-tubulin, PAX6, and NGN2 expression, together with more neurite outgrowths and elongated morphology, as compared with either Geltrex or TCPS. Conclusions DECM derived from neurogenesis of hESCs can enhance the neurogenic potential of DFSCs. [ABSTRACT FROM AUTHOR]

Background/purpose Plasma rich in growth factors (PRGFs), which is prepared from autologous blood from patients, has been reported with regards to bone regeneration for dental implants. Human dental follicle cells (hDFCs) have the capacity to commit to multiple cell types such as the osteoblastic lineage. The aim of this study is to evaluate the effects of PRGFs for mineralization in hDFCs. Materials and methods PRGFs was prepared from whole blood centrifuged at 460 g for 8 minutes. hDFCs isolated from the dental follicle with collagenase/dispase were cultured with growth medium or osteogenic induction medium (OIM) containing PRGFs or fetal bovine serum. Concentrations of the growth factors were examined using an enzyme-linked immunosorbent assay kit. A cell migration assay was used for two-dimensional movement. Gene expressions were examined with real-time polymerase chain reaction using a DyNAmo SYBR Green quantitative polymerase chain reaction kit. Results The platelet concentration in PRGF Fraction 2 was 2.14-fold higher than in whole blood. White blood cells were not detected in PRGFs. Transforming growth factor-β levels were higher than insulin-like growth factor-1, platelet-derived growth factor-AB and -BB, and vascular endothelial growth factors in PRGF Fraction 2. Proliferation and migration by hDFCs increased in OIM supplemented with PRGFs in a dose-dependent manner and were higher in hDFCs cultured in OIM plus 10% PRGFs compared with OIM plus 10% fetal bovine serum. PRGFs upregulated the gene expression of type I collagen , osteomodulin , alkaline phosphatase , bone morphogenic protein-4 , and transforming growth factor-β in hDFCs. Conclusion PRGFs may promote bone regeneration due to it including high levels of growth factors. [ABSTRACT FROM AUTHOR]

The dental follicle is involved in tooth eruption and it expresses a great amount of the parathyroid hormone-related protein (PTHrP). PTHrP as an extracellular protein is required for a multitude of different regulations of enchondral bone development and differentiation of bone precursor cells and of the development of craniofacial tissues. The dental follicle contains also precursor cells (DFCs) of the periodontium. Isolated DFCs differentiate into periodontal ligament cells, alveolar osteoblast and cementoblasts. However, the role of PTHrP during the human periodontal development remains elusive. Our study evaluated the influence of PTHrP on the osteogenic differentiation of DFCs under in vitro conditions for the first time. The PTHrP protein was highly secreted after 4 days of the induction of the osteogenic differentiation of DFCs with dexamethasone (2160.5 pg/ml ± 345.7 SD. in osteogenic differentiation medium vs. 315.7 pg/ml ± 156.2 SD. in standard cell culture medium; Student’s t Test: p < 0.05 (n = 3)). We showed that the supplementation of the osteogenic differentiation medium with PTHrP inhibited the alkaline phosphatase activity and the expression of the transcription factor DLX3, but the depletion of PTHrP did not support the differentiation of DFCs. Previous studies have shown that Indian Hedgehog (IHH) induces PTHrP and that PTHrP, in turn, inhibits IHH via a negative feedback loop. We showed that SUFU (Suppressor Of Fused Homolog) was not regulated during the osteogenic differentiation in DFCs. So, neither the hedgehog signaling pathway induced PTHrP nor PTHrP suppressed the hedgehog signaling pathway during the osteogenic differentiation in DFCs. In conclusion, our results suggest that PTHrP regulates independently of the hedgehog signaling pathway the osteogenic differentiated in DFCs. [ABSTRACT FROM AUTHOR]

Introduction During tooth development, cells originating from the neural crest serve as precursors to the cells in the dental follicle and dental papilla. Therefore, the current study aimed to understand the associations of cranial neural crest cells (CNCCs), dental follicle cells (DFCs), and dental papilla cells (DPCs) by performing a parallel comparison to evaluate their odontogenic differentiation capacities. Methods In this study, we harvested the 3 cells from C57/green fluorescent protein–positive mice or embryos and compared the cell morphology, surface antigens, microstructures, and gene and protein expression. Under the odontogenic microenvironments provided by treated dentin matrix, the odontogenic differentiations of the 3 cells were further compared in vitro and in vivo . Results The gene levels of DFCs in neurofilament, tubulin, and nestin were close to the DPCs, and in alkaline phosphatase, osteopontin, dentin matrix protein 1, and dentin sialophosphoprotein were the lowest in the 3 cells. However, Western blot results showed that DFCs possessed more similar protein profiles to CNCCs than DPCs, including collagen 1, transforming growth factor beta 1, osteopontin, neurofilament, and dentin matrix protein 1. Meanwhile, DFCs as 1 source of dental stem cells possessed high potency in odontogenic differentiation in vitro . Moreover, similar dentinlike tissues were observed in all 3 groups in vivo . Conclusions CNCCs, DFCs, and DPCs possessed different biological characteristics in odontogenic differentiation. [ABSTRACT FROM AUTHOR]

The aim of this study was to investigate the capacity of human dental follicle cells (hDFCs) for bone formation in vivo. hDFCs were obtained from wisdom teeth extracted from patients aged 14 and 22 years. hDFCs from the 5th to 8th passages were grown in three-dimensional (3D) culture using gelatin sponges. Cells were transplanted onto the calvaria of F344/NJcl-rnu/rnu male rats (immunodeficient rats). Haematoxylin and eosin (HE) staining and immunohistochemistry were performed, and newly formed bone was evaluated by micro-computed tomography (micro-CT). HE staining showed newly formed bone in 3D culture. Immunohistochemistry showed bone morphogenetic protein 2 (BMP-2), runt-related transcription factor 2 (RUNX2), and osterix staining in areas with newly formed bone. Furthermore, micro-CT showed that, in comparison to controls, transplanted hDFCs promoted better bone quality and bone mineral density (BMD 582 ± 131.1 vs. 300.5 ± 77.7 mg/cm 3 ; P = 0.039), bone mineral content (BMC 5.6 ± 1.1 vs. 2.1 ± 0.4 mg; P = 0.006), bone volume (BV 9.7 ± 0.5 × 10 −3 vs. 7.0 ± 0.4 × 10 −3 cm 3 ; P = 0.002), BMC/total volume (TV) (399.9 ± 76.3 vs. 147.7 ± 30.8 mg/cm 3 ; P = 0.006), and BV/TV (69.1 ± 3.6% vs. 49.6 ± 3.1%; P = 0.002). This suggests that human dental follicles are potentially useful for regenerative therapy. [ABSTRACT FROM AUTHOR]

Introduction Residual dental follicles surrounding the crowns of impacted teeth may represent a significant risk for their potential pathological changes. In this study, the expression levels of cell cycle proteins, proliferating cell nuclear antigen (PCNA), cyclin D1, and p21 were evaluated using immunohistochemistry. Patients and methods Twenty-two impacted mandibular third molars in 17 healthy individuals were evaluated in this study. They were divided into two groups on the basis of the depth of impaction: the partially impacted group and the fully impacted group. The impacted teeth were surgically removed and the surrounding follicle was curetted and examined by immunohistochemistry to evaluate whether there was a difference in cell cycle regulation between the two groups. Results PCNA was expressed in most of the epithelial cells with no significant difference between the groups. The p21 expression was significantly higher in the full bony impaction group. Cyclin D1 expression was expressed at low levels with no significant difference between the groups. Weak cyclin D1 expression was consistent with high p21, a negative regulator of the cell cycle. The high p21 expression could be a compensatory mechanism to the high PCNA levels. These results suggest the possibility that dental follicles associated with full bony impactions possess different cellular activities compared with partial bony/soft-tissue impactions. [ABSTRACT FROM AUTHOR]

Adult stem cells are multipotent and can be induced experimentally to differentiate into various cell lineages. Such cells are therefore a key part of achieving the promise of tissue regeneration. The most studied stem cells are those of the hematopoietic and mesenchymal lineages. Recently, mesenchymal stem cells were demonstrated in dental tissues, including dental pulp, periodontal ligament, and dental follicle. The dental follicle is a loose connective tissue that surrounds the developing tooth. Dental follicle stem cells could therefore be a cell source for mesenchymal stem cells. Indeed, dental follicle is present in impacted teeth, which are commonly extracted and disposed of as medical waste in dental practice. Dental follicle stem cells can be isolated and grown under defined tissue culture conditions, and recent characterization of these stem cells has increased their potential for use in tissue engineering applications, including periodontal and bone regeneration. This review describes current knowledge and recent developments in dental follicle stem cells and their application. [ABSTRACT FROM AUTHOR]

PURPOSE : To study the effects of epidermal growth factor (EGF) on the secretion of monocyte chemotactic protein-one (MCP-1) in rat dental follicle cells. METHODS : Dental follicle was harvested from 4-6 days postnatal Wistar rats and cultured in α-MEM with 15% FBS. Cells in the third passage were incubated with EGF at different concentrations to choose the best dosage. MTT assays were used to evaluate cell proliferation. Using the suitable concentration, 10ng/ml EGF cells were cultured for 0, 0.5, 1, 3 and 6 hours respectively, and then collected for RT-PCR analysis. The results were analyzed with SPSS13.0 software package. RESULTS: EGF(ng/ml) at 5-10 ng/ml increased the cell proliferation (P<0.05), which reached the peak at 10ng/ml according to MTT assay (P<0.01). 10ng/ml and 3 hours EGF exposure up-regulated the cellular MCP-1 expression dramatically (P<0.01). CONCLUSION: Proper concentration of EGF may promote dental follicle cell proliferation, EGF may up-regulate MCP-1 transcription in the rat dental follicle cells. [ABSTRACT FROM AUTHOR]

Abstract: Bone morphogenetic proteins (BMPs) and BMP receptors (BMPRs) are known to regulate the development of calcified tissues by directing mesenchymal precursor cells differentiation. However, their role in the formation of tooth-supporting tissues remains unclear. We investigated the distribution pattern of STRO-1, a marker of mesenchymal progenitor cells and several members of the BMP pathway during the development of mouse molar periodontium, from the post-natal days 6 to 23 (D6 to D23). STRO-1 was mainly localized in the dental follicle (DF) at D6 and 13 then in the periodontal ligament (PDL) at D23. BMP-2 and -7 were detected in Hertwig''s epithelial root sheath (HERS) and in DF, then later in differentiated periodontal cells. BMP-3 was detected after D13 of the periodontal development. BMPRs-Ib, -II, the activin receptor-1 (ActR-1) and the phosphorylated Smad1 were detected in DF and HERS at D6 and later more diffusely in the periodontium. BMPR-Ia detection was restricted to alveolar bone. These findings were in agreement with others data obtained with mouse immortalized DF cells. These results suggest that STRO-1 positive DF cells may be target of BMPs secreted by HERS. BMP-3 might be involved in the arrest of this process by inhibiting the signaling provided by cementogenic and osteogenic BMPs. [Copyright &y& Elsevier]

Background: Syndecans are cell surface heparan sulfate proteoglycans that modulate the action of growth factors and extracellular matrix components. Syndecan-1 plays important roles during early tooth development, and it is expressed in the dental follicle of fetal tooth germ. However, no studies have followed its expression in the dental follicle during the postnatal period. We hypothesized that syndecan-1 protein expression in the dental follicle may be important for postnatal tooth development, and, thus, examined its expression patterns. Methods: Syndecan-1 protein expression in the dental follicle of the lower first molar was investigated by immuno-histochemistry using embryonic day (E) 18.5 to 21-day-old (d 21) mice. Immunoelectron microscopy was applied to the dental follicle and pulp cells to confirm its membrane localization in mesenchymal cells. Results: Strong syndecan-1 immunostaining was maintained in the dental follicle and the adjacent dental pulp surrounded by the Hertwig's epithelial root sheath (HERS) from d 4 to d 14, but reduced staining was noted at d 21 with the near-completion of tooth eruption. Three dimensionally, syndecan-1-positive areas plugged the apical foramina surrounded by HERS. However, immunostaining was detected constantly in the dental follicle and the dental pulp of the lower incisor at d 21. In addition, membrane localization of syndecan-1 protein was confirmed for the first time in mesenchymal cells, including dental follicle and pulp cells, by immunoelectron microscopy. Conclusion: The spatial and temporal expression of syndecan-1 in the dental follicle suggests that this proteoglycan is important for the maintenance of proliferation and/or movement of cells in this region during tooth eruption. [ABSTRACT FROM AUTHOR]

Tooth eruption requires the presence of the dental follicle to recruit mononuclear cells, which fuse to form osteoclasts that resorb the alveolar bone such that the tooth can erupt. In the rat first mandibular molar, there is a major burst of osteoclastogenesis at day 3 postnatally and a lesser burst at day 10. Eruption molecules, such as CSF-1, are maximally expressed at day 3 in the dental follicle to promote this maximal osteoclast formation, but by the time of the secondary burst of osteodastogenesis their expression is dramatically reduced. Because vascular endothelial growth factor (VEGF) can substitute for CSF-1 to promote osteoclastogenesis, we examined its gene expression in vivo in the dental follicle and found that it and its two major isoforms (VEGF 120 and 164) were all maximally expressed at days 9-11, the time of the secondary burst. Treatment of the cells with phorbolmyristate acetate (PMA), a protein kinase C(PKC) activator, enhanced expression of the 2 major VEGF isoforms in the cultured dental follicle cells, whereas adding a specific PKC inhibitor prevented this. Treatment with PMA also increased the protein level of VEGF. Thus, VEGF may be involved in promoting the secondary burst of osteoclastogenesis, and activation of PKC may upregulate its expression. [ABSTRACT FROM AUTHOR]

We performed computed tomography (CT) on 107 children and adolescents aged 9-15 years with 176 unerupted maxillary canines (152 erupting ectopically and 24 erupting normally) to determine whether there is an association between widened dental follicles of the maxillary canines and resorption of the adjacent incisors during eruption. Contiguous axial (transverse) CT scans were obtained through the maxilla in the region of the canines. The width and shape of the dental follicles were recorded, as were any contacts between the follicles and the crowns of the maxillary canines and neighboring incisors. Fifty-eight lateral incisors (38%) and 14 central incisors (9%) had some type of root resorption. The position of the maxillary canine in relation to the root of the lateral incisor varied greatly, as did the width and shape of the canine dental follicle. Follicle width ranged from 0.5 mm to 7.0 mm. The mean ± SD width of dental follicles was, on average, larger for the ectopically positioned canines (2.9 ± 0.8 mm) than for the normally erupting canines (2.5 ± 0.8 mm) (P ⩽ .01). We found that during eruption, the follicle of the erupting maxillary canine frequently resorbed the periodontal contours of adjacent permanent teeth but not the hard tissues of the roots. We concluded that the dental follicle did not cause root resorption of permanent teeth. Resorption of neighboring permanent teeth during maxillary canine eruption was most probably an effect of the physical contacts between the erupting canine and the adjacent tooth, active pressure during eruption, and cellular activities in the tissues at the contact points, all of which are part of the eruptive mechanism. The findings also confirm an association between root resorption of deciduous canines and the dental follicles of erupting permanent canines. [ABSTRACT FROM AUTHOR]

The subjects in the study were children who were X-rayed because of increased risk for resorption following ectopically erupting maxillary canines. One hundred and seven children 9 to 15 years of age with 156 maxillary canines that were erupting ectopically and 58 normally were investigated by computed tomography (CT) to describe the features of the dental follicles of the erupting maxillary canines. Contiguous, transverse CT scans were exposed through the maxilla in the canine region and the width and shape of the dental follicles were registered scan by scan throughout the extension of the follicle. The width and the shape of the dental follicle of the erupting maxillary canine varied greatly. The range of the maximum width, measured from the crown to the periphery of the follicle, was 0.5-7.0 mm, with a mean of 2.9 mm and a 95% confidence interval of 2.7-3.2 mm for the entire sample. No relationship was found between the width or shape of the follicles and sex, age, stage of eruption, inclination of the canine, or width of the dental arch. However, the location of the maxillary canine vis-à-vis the adjacent incisor was significantly associated with the width of the follicle, which indicated that local anatomic conditions might influence the width and shape of the follicle. The dental follicles of the ectopically erupting canines were, on average, wider than those of the normally erupting canines. The 95% confidence interval for the normally erupting canines was 2.3-2.7 mm; for the buccally erupting canines 2.4-4.1 mm; for the lingually erupting canines 2.6-3.0 mm; and for the apically erupting canines in relation to the lateral incisors 2.9-4.1 mm. Canine follicles that were wide but within normal limits did not cause deviations in adjacent teeth. Cystically degenerated dental follicles were found but were indistinguishable on the CT scans from those that had been widened physiologically. The contributions of the studied variables to the variation in the width of the dental follicle of the maxillary canine were analyzed with regression models. [ABSTRACT FROM AUTHOR]

Background: It is thought that during development of the periodontium, dental follicle cells, when appropriately triggered, have the ability to differentiate into periodontal ligament fibroblasts, cementoblasts, and osteoblasts. However, the exact mechanisms/factors responsible for initiating cell differentiation are not defined. The purpose of this in vitro study was to further characterize follicle cells and to determine the effects of an enamel matrix-derived protein (EMD) on these cells. Methods: Murine follicle cells, transformed with simian virus 40 (SV 40) T antigen-containing virus (SVF cells), were used. SVF cells were cultured in Dulbecco's modified Eagle's medium (DMEM) plus 2% fetal bovine serum (FBS) or 2% FBS plus EMD (100 µg/ml), with and without ascorbic acid (50 µg/ml). For proliferation assays, cells were plated at 500 cells/cm² in 24-well plates and counted on days 3, 4, and 5. For Northern analysis, total RNA was isolated on days 8, 12, and 18. Induction of mineral nodules by SVF cells was determined by von Kossa staining. Results: EMD had a significant proliferate effect on SVF cells, when compared with 2% FBS control. Based on investigations in situ, follicle cells at the time point used here do not express key mineral-associated markers, e.g., osteocalcin (OCH) or bone sialoprotein (BSP). Significantly, by day 12 in culture, Northern analysis indicated that the follicle cells expressed transcripts for BSP, OCN, and osteopontin (OPN). EMD increased OPN mRNA and decreased OCN mRNA expression. SVF cells were capable of inducing mineralization on day 18, but EMD blocked this activity. Conclusions: These results suggest the follicle cells have the capacity to act as cementoblasts or osteoblasts. Furthermore, EMD can regulate follicle cell activity, thus suggesting that epithelial-mesenchymal interactions may be important during development of periodontal tissues. [ABSTRACT FROM AUTHOR]

The pericoronal tissue, or dental follicle, is a connective tissue found around impacted teeth crown. The dental follicle is involved in odontogenesis, dental eruption and periodontogenesis. A young woman presented a vestibular U-shaped periodontal recession localized in tooth 26. After consent the patient underwent a local intervention combining the extraction of her included 28 and a mucogingival management of her periodontal recession localized in 26, using the pericoronary sac of the tooth of 28 has been used as a subepithelial connective autograft. The results 6 weeks after surgery showed a significant gain in thickness and a gain in height of attached gingiva of 26. The success of the use of pericoronary sac in subepithelial connective autograft may allow to spare the use of a healthy harvesting site. Furthermore, the dental follicle is often available in young patients with prophylactic extraction of impacted 3rd molars. However, one pericoronary sac may provide enough connective tissue, only for the surgical treatment of a unique recession site. The use of the pericoronal sac has shown promising results in the treatment of periodontal recessions. Wider applications could be investigated using the pericoronal sac in the future. • The pericoronal tissue may be used in subepithelial autografting technics. • The pericoronal tissue has the great histophysiological potential of pluripotent cells. • Pericoronal tissues are easily collected in young patients. • The use of pericoronal tissue may replace other conjonctive sampling methods. [ABSTRACT FROM AUTHOR]