1-SmileLineNewsSUM2021 - Flipbook - Page 27
apex, using long-term calcium hydroxide or single-step
MTA apical plug. However, apexification does not appear
to strengthen the root structure.
In recent years, The AAE has proposed a new procedure,
termed regenerative endodontic procedures (REPs), with
the goal to reintroduce the pulpal tissue and to allow
further development of the root in a pulpless tooth [ref 4].
The regeneration of the pulp in a young patient is possible
due to presence of mesenchymal stem cell populations
remaining outside of the apex of a young pulpless tooth.
When these cells are reintroduced into the disinfected
pulpal space, supported with tissue scaffolds, and influenced by local tissue growth factors, they may expand and
differentiate into cell populations resembling the niche cells
of the pulp, thus allowing continued root development.
According to the AAE treatment considerations [ref 5], a
typical regenerative procedure starts with disinfection of
the canal system with a mild disinfectant, such as 1.5%
sodium hypochloride, and with minimal mechanical
instrumentation to avoid damaging the stem cells near
the apex. Calcium hydroxide paste is then placed short
of the apex for 2-3 weeks.
At the second visit, the canal space is often adequately
cleaned. The tooth is anesthetized with local anesthesia
without epinephrine to facilitate bleeding. The canal is
conditioned with 17% ethylenediaminetetraacetic acid
(EDTA), which has been shown to release growth factors
embedded within the dentin. A hand file is used to induce
bleeding from the apex into the canal space, up to the
cervical level.The blood contains mesenchymal stem cells
and the blood clot acts as tissue scaffolds. A collagen
barrier is placed on top of the blood clot, and calcium
silicate-based material is laid on top of collagen as pulp
space barrier. The access opening is then restored with
glass ionomer or bonded composite.
Periodic follow-ups are then scheduled to assess the healing
of the apical lesion as well as continued root development.
In majority of subjects studied, the regenerative endodontic
procedures were successful, showing increases in the root
length and/or the width of canal walls [ref 4]. New studies
are still ongoing to explore alternative sources of stem cells,
scaffolding materials, and growth factors.
Dr. Xudong “Don” Yang, D.D.S.,
Dr. Xudong (“Don”) Yang is an Endodontist
in Salinas, CA. He graduated from University
of the Pacific Arthur A.Dugoni School of
Dentistry in 2004, and completed his postdoctoral specialty training in Endodontics at
Harvard School of Dental Medicine. During
his residency, he was involved in research on
tooth development in genetically engineered
mice at Brigham and Women's Hospital in
Boston. Dr. Yang has also received a PhD
in Molecular Biology from Oklahoma
In his spare time, he enjoys photography,
traveling, and model railroading.
www.mbdsdentist.com I MONTEREY BAY SMILELINE – SUMMER 2021