Dental follicle

Ideas such as remodelling of the alveolar bone, root elongation and to a certain extent, the most probable reasoning for tooth eruption in human beings is the formation of the periodontal ligament.

[3] A sequence of experiments in dogs does provide the most reliable substantiation to prove that bone remodelling is a cause of tooth movement.

When an eruption is stopped by wiring the tooth germ on to the lower margin of the mandible or when the dental follicle remains undisturbed as the developing pre-molar is removed, osteoclasts enlarge the gubernacular canal while an eruptive pathway develops within the bone covering over the enucleated tooth.

Firstly, eruptive pathways have unmistakably been demonstrated to develop in bone deprived of a budding or growing tooth.

Furthermore, in some recent research, it has been observed that alveolar bone growth at the base of the crypt is a prerequisite for molar tooth eruption in rats.

Researches show a repeated series of cellular activities which involves the reduced dental epithelium and the follicle linked to tooth eruption that assists bone absorption and connective tissue degradation.

Proteases, which is produced by the reduced enamel epithelium, results in a path of least resistance as it promotes the breakdown of connective tissue.

This signalling could be a plausible reason for the noteworthy regularity of eruption timings because the enamel epithelium is most possibly programmed as part of its functional life cycle.

Signalling would also aid in explaining why radicular follicle, that is not related to reduced enamel epithelium, is involved in the formation of the periodontal ligament but does not experience degeneration.

Cells of dental follicle will differentiate into collagen forming fibroblast of cementoblasts and periodontal ligaments, that produces and secretes cementum on the surface of the tooth roots.

Delicate fibres that appear along the developing roots near the cervical region of the crown will also be formed by some cells of the ligament.

As fibres become implanted in the cementum of the root surface, the other end will be attached to the forming alveolar bone.

It can be observed that the coronal half of the periodontal ligament is made up of well composed, obliquely orientated principal collagen fibre bundles when an erupting permanent molar enters into the oral cavity.

A majority of the periodontal ligament of an erupting permanent premolar is deprived of a discernable number of organized principal collagen fibre bundles passing from tooth to alveolar bone.

Down-regulation of the expression of the Runt-related transcription factor- 2 in the apex portion of the dental follicle, that supports bone removal along the surface which the tooth erupts, is due to the transforming growth factor b.

[5] The most common pathologies associated with dental follicle are dentigerous cyst, keratocystic odontogenic tumor and ameloblastoma.

It can also develop from break down of stellate reticulum or collection of fluid between the reduced enamel epithelium layers.

Odontogenic tumours of mixed origin contain both ameloblastic epithelium and odontoblastic tissue while in active growth.

The presence of stem cells in the dental is an integral part of the DF's ability to differentiate into the periodontal ligament.

Multipotentectomesenchymal precursor cells also referred to as DFCs are found in the coronal part of the DF of impacted human third molar teeth contains.

The extracellular signal regulated kinase (ERK) pathway was also revealed during the osteogenic differentiation of DFCs by these investigations.

Furthermore, DFC migration can be accelerated during cultivation, with the use of growth factors found in the dental hard tissue matrix such as TGF-β or BMP2 which have also been found to be involved in the differentiation of DFCs[6][10] FENCSCs are a sub-population of DFCs, however both differ in their in cell migration properties.

FENSCs express high levels of embryonic stem cell markers (TRA1-60, TRA1-81, OCT-4) and mRNA transcripts for Nanog and Rex-1.

Some examples include, smooth and skeletal muscle, osteoblasts, neurons, glial cells, and adipocytes and therefore display pluripotency.

Once the development of the tooth root is completed, the DF disappears thus meaning that all cells are considered to be part of the periodontium.

PFACs are targets of regenerative dentistry due to their high multipotent differentiation potential within all types of dental tissue.

[6] Human dental follicles can be separated from impacted wisdom teeth with undeveloped tooth roots.

Therefore, undifferentiated ectomesenchymal cells can be isolated from both apical and coronal parts of the human dental follicle.