The mechanism of dentine hypersensitivity:Stimuli-induced directional cation transport through dentinal tubules

Dentine hypersensitivity is an annoying worldwide disease,yet its mechanism remains unclear.The long-used hydrodynamic theory,a stimuli-induced fluid-flow process,describes the pain processes.However,no experimental evidence supports the statements.Here,we demonstrate that stimuli-induced directional cation transport,rather than fluid-flow,through dentinal tubules actually leads to dentine hypersensitivity.The in vitro/in vivo electro-chemical and electro-neurophysiological approaches reveal the cation current through the nanoconfined negatively charged dentinal tubules coming from external stimuli(pressure,pH,and temperature)on dentin surface and further triggering the nerve impulses causing the dentine hypersensitivity.Furthermore,the cationic-hydrogels blocked dentinal tubules could significantly reduce the stimuli-triggered nerve action potentials and the anionhydrogels counterpart enhances those,supporting the cation-flow transducing dentine hypersensitivity.Therefore,the inspired ion-blocking desensitizing therapies have achieved remarkable pain relief in clinical applications.The proposed mechanism would enrich the basic knowledge of dentistry and further foster breakthrough initiatives in hypersensitivity mitigation and cure.

A Study on Morphologic Feature of Dentinal Hypersensitivity by SEM

The morpohologic feature of radicular dentin in sensitive and naturally desensitive area was observed with scanning electron microscopy (SEM). Eight specimens were taken from six patients with periodontal diseases. It was established that the orifices of dentinal tubules in hypersensitive areas were much more than those in naturally desensitive areas. The dimension of the orifices in hyperoensitive areas was much larger than that in naturally desensitive areas. The results suggest that theie is relationship between dentin moophology and dentin hypersensitivity. In this article, a new dentin bipopsy technique with hollow drill was reported also.

Preliminary Study on Human Radicular Dentinal Characterization in both Sensitive and Naturally Desensitive Areas with SEM

The morphologic feature of radicular dentin in sensitive and naturally desensitive areas was observed with scanning electron microscopy(SEM). Eight specimens were taken from six-patients with periodontal diseases. It was established that the orifices of dentinal tubules in hypersensitive areas were much more than those in naturally desensitive areas. The dimension of the orifices in hypersensitive areas was much larger than that in naturally desensitive areas. The results suggest that there is relationship between dentin morphology and dentin hypersensitivity. In this article, a new technique of dentin biopsy with hollow drill was reported also.

Dentin-desensitizing biomaterials

Dentin hypersensitivity(DH)associated with dentinal tubule exposure is one of the most common causes of toothache with a rapid onset and short duration.Medication,filling repair,laser irradiation,crown therapy,and desensitizing toothpaste are standard clinical treatment strategies,but unsatisfactory treatment modalities are marked by long-term administration,poor dentinal tubule closure,microleakage,and the development of secondary caries.To improve the treatment efficiency of DH,numerous organic or inorganic biomaterials have been developed to relieve toothache and reverse the instability of desensitization.Biomaterials are expected to participate in dental remineralization to achieve desensitization.This review discusses various biomaterials for DH therapy based on different desensitization mechanisms,including dentinal tubule closure and dental nerve blockade,and presents a perspective on the underlying future of dentin regeneration medicine for DH therapy.

Mineral formation on dentin induced by nano-bioactive glass

The object of this study was to evaluate the effect of bioactive glass （BG） size on mineral formation on dentin surfaces. Totally demineralized dentin discs were treated using BG suspensions with different particle sizes： i.e., microscale bioactive glass （m-BG）, submicroscale bioactive glass （sm-BG） and nanoscale bioactive glass （n-BG）. Field-emission scanning electron microscopy and 3D profile measurement laser microscopy were used to observe the surface morphology and roughness. It was found that all BG particles could promoted mineral formation on dentin surfaces, while plug-like depositions were observed on the dentin discs treated by n-BG and they were more acid-resistant. The present results may imply that n-BG has potential clinical application for dentin hypersensitivity treatment.