Choosing an endodontic sealer for clinical use is a decision that contributes to the long-term success of non-surgical root canal treatment (NSRCT) 1) . Sealers are used as a thin tacky paste which functions as a lubricant and luting agent during obturation, allowing the core obturation material, such as gutta-percha points or other rigid materials, to slide in and become fixed in the canal 2,3) . Sealers can fill voids 4) , lateral canals 5) , and accessory canals where core obturation materials cannot infiltrate 6,7) . If the sealer does not perform its function, microleakage may cause NSRCT failure via clinically undetectable passage of bacteria, fluids, molecules or ions between the tooth and restorative material 8,9) . Knowing the qualities and characteristics of an endodontic sealer is critical to determining the best selection and application for each clinical case.Endodontic sealers are categorized by composition based on setting reaction and composition: zinc oxideeugenol, salicylate, fatty acid, glass ionomer, silicone, epoxy resin, tricalcium silicate, and methacrylate resin sealer systems (Table 1). Some novel sealers contain fillers or ceramic powders including calcium hydroxide, mineral trioxide aggregate (MTA), and calcium phosphate; however, they are fundamentally composed of the above sealer matrices. Until recently, many review articles were published within sealer types [10][11][12][13][14][15][16] . However, few reviews have been published that cover all sealer types 17,18) . Therefore, in this comprehensive review, a historical perspective of each sealer type will be discussed first, followed by a description of the properties of all sealer types, such as setting time and solubility, sealing ability, antimicrobial activity, and biocompatibility and cytotoxicity. Sealer attributes such as the rheology 19) , radiopacity 20) , and tooth discoloration [21][22][23] have been shown to be satisfactory and will not be discussed in detail. CURRENT ROOT CANAL SEALERS AND HISTORY Chelate formationMany dental luting agents set by way of a chelation reaction, the formation of metal complexes with polydentate (usually organic) ligands 24) . Two of the most common chelates used in dentistry are eugenolates and salicylates. For eugenolates, the setting reaction starts with water that hydrolyzes the zinc oxide to form zinc hydroxide. The zinc hydroxide and eugenol chelate and solidify 25) . For salicylates, the ion is calcium, usually formulated using calcium oxide. Although uncommon, fatty acids have also been used as ligands for chelate sealers, in conjunction with zinc oxide.

Objective: Bioactive ions, when incorporated in an endodontic sealer, can contribute to the long-term success of endodontic therapy by combating the re-infection of a tooth and promoting the healing of the periapical bone. The objective of this study was to measure the release of boron, strontium, and silicon ions from surface pre-reacted glass ionomer (S-PRG) filler containing prototype endodontic sealer over a sustained period in comparison to EndoSequence BC sealer in a simulated clinical model using extracted human teeth in vitro. Methods: Twelve extracted human anterior teeth were instrumented using ProTaper Next (Dentsply Sirona, Johnson City, TN, USA) files up to size X3 (#30/variable taper) with copious 2.5% NaOCl irrigation. Teeth were obturated using a single-cone technique with a matching size tapered gutta-percha point and one of two endodontic sealers: prototype S-PRG (Shofu Inc., Kyoto, Japan) or EndoSequence BC (Brasseler, Savannah, GA, USA). The teeth were soaked in phosphate-buffered saline (PBS) solution for 336 hours. Periodically, 1-mL samples of the PBS were analyzed via an inductively coupled plasma mass spectrometer to determine the concentrations of ions released by the sealers. Results: The average (S.D.) cumulative release (ng/ml) of boron, silicon, and strontium ions over 2 weeks for the prototype S-PRG sealer was 8614.9 (1264.3), 35758.9 (5986.5), and 3965.2 (145.6), and for EndoSequence BC sealer was 1860.5 (82.7), 164648.7 (16468.1), and 227.7 (4.7). Generalized linear mixed model analysis showed significant differences in ion concentration among boron, silicon, and strontium over time between the two sealer groups (Boron: P<0.0001, Silicon: P=0.010, Strontium: P=0.028). Of the three ions, strontium had the lowest amount of release for both sealers. The prototype S-PRG sealer showed a rapid initial burst followed by a slow, continuous release of strontium ions. Conclusion: The prototype S-PRG sealer released boron and strontium ions in higher cumulative concentrations over 2 weeks compared to the EndoSequence BC sealer. Both the prototype S-PRG and EndoSequence BC sealers released silicon ions, although significantly more were eluted from the EndoSequence BC sealer. Antimicrobial and osteogenic ion release from sealers is expected to positively influence the post-treatment control of microbial infections to improve periapical healing.

Establishing a secure airway is critical in the acute phase of facial burns. This case report involving a 9-month-old infant with facial burns describes two techniques of securing an oral airway – trans-alveolar wiring and the application of an intermaxillary fixation (IMF) screw. The use of an IMF screw was more reliable than trans-alveolar wiring, as it allowed a secure airway through the patient’s hospitalization, which involved 7 additional surgical interventions including 5 separate facial skin grafts over a 3-month period.