Long-Term Clinical and Radiographic Observation of Previously Regenerated Treated Incisors Subjected to Orthodontic Movement. A Case Series.

INTRODUCTION: With an increasing number of anterior traumatized teeth treated with regenerative endodontic procedures (REPs) nowadays, orthodontic movement of such teeth is expected to become a common scenario in everyday clinical practice. However, little is known about the clinical implications and the response capacity of regenerated tissues to orthodontic forces. METHODS: The aim of this clinical article was to report on 4 cases of REP-treated immature anterior permanent teeth subjected to orthodontic forces, and to describe the long-term response of the regenerated apical and intracanal tissues. RESULTS: Signs of orthodontic-induced external root resorption were observed in 2 of the 4 presented cases without, however, the presence of any associated adverse events. No other complications were observed, either clinically or radiographically, throughout the observation period. In the long-term, all 4 cases responded favorably to orthodontic forces, maintaining healthy apical tissues and structural integrity of both intracanal as well as apically regenerated tissues. CONCLUSIONS: The orthodontic movement of REP-treated teeth seems feasible, nevertheless, special care should be implemented. Lightly acting orthodontic forces, short duration of active movement, and close monitoring of the patient seem to be prerequisites to limit complications to a minimum and achieve a favorable healing of REP-treated teeth in the long-term following orthodontic treatment completion.

Experimental formation of dentin-like structure in the root canal implant model using cryopreserved swine dental pulp progenitor cells.

OBJECTIVES: The purpose of the present study was to present histological and immunohistochemical evidence showing the regenerative capacity of swine dental pulp stem cells (S-DPSCs) seeded on organic or synthetic scaffolds and implanted as hybrid root implants in the jaw bone of minipigs. METHODS: Immature permanent incisor teeth and unerupted premolars at the early root-forming stage were extracted from three 7-month-old minipigs, and mesenchymal stem/progenitor cells were isolated from dental pulp. Cells were cryopreserved in liquid nitrogen. A year later, new permanent incisor and premolar teeth were extracted; pulp tissue was removed; and pieces of root canals of the extracted teeth, containing collagen or Poly(lactic-co-glycolic acid) scaffolds seeded with the autologous cryopreserved DPSCs, were implanted into the fresh post-extraction socket of the mini pig jaw. The resulting constructs were harvested after 6 and 10 weeks and evaluated by histological and immunohistochemical analyses. RESULTS: Six weeks postoperatively, the central canal space of the root implants showed degrading scaffold material. New extracellular matrix had been deposited in a polar predentin-like pattern on the canal dentinal walls by cuboidal nonpolarized cells. Ten weeks postoperatively, newly formed organic matrix had been consistently deposited on the canal walls. The presence of a continuous layer of polarized cells showing typical columnar morphology adjacent to the newly deposited organic matrix was evident. CONCLUSIONS: The interactions of S-DPSCs with the dentin matrix of roots implanted in the jawbone of minipigs constitute a model to study in vivo organization and differentiation potential of DPSCs.

Effect of simulated pulpal microcirculation on intrachamber temperature changes following application of various curing units on tooth surface.

OBJECTIVE: The purpose of this study was to evaluate ex vivo the rise in intrachamber temperature induced by the application of various curing units on tooth surface, under conditions of continuous water flow inside the pulp chamber simulating pulp microcirculation. METHODS: Fifteen extracted intact human teeth were selected. Intrachamber temperature increases were induced by applying the following curing units to the buccal aspect of the tested teeth: a conventional halogen lamp, two high-intensity halogen lamps, a plasma arc curing light, a mercury/metal-halide lamp, and a diode laser. Temperature changes on the tooth surfaces were recorded using thermocouples connected to a data logger. The Greenhouse-Geisser and Bonferroni tests in the SPSS software package were used for analysis of the data. The level of significance was set at 0.05. RESULTS: Under conditions of water flow the average intrachamber temperature rise was less than 6 degrees C, for all curing units. Without water flow, the increase in pulp temperature exceeded 6 degrees C for all units except the conventional halogen lamp. The diode laser produced a significantly greater temperature increase than any other curing unit. Application of the diode laser and the two high-intensity halogen lamps to lateral incisor specimens produced significantly greater temperature increases than other teeth. CONCLUSIONS: When the simulated pulp microcirculation was absent, the temperature increases produced by all curing units except the conventional halogen lamp were large enough to be potentially harmful to the pulp. On the contrary, with the cooling effect of water flow inside the pulp chamber, all units proved to be safe for use.

Effect of heat application on adhesion of epoxy resin sealer.

Sealers are subjected to high temperatures during the warm condensation of gutta-percha; however, there are few reports on the impact of this temperature rise on the physical properties of a sealer. The purpose of this study was to compare the bond strength of AH26 to human dentin substrates, with or without heat application, by measuring the shear bond strength with a single plane shear test assembly. The results showed that there was no statistically significant difference between the shear bond strength of AH26 with or without heat application, indicating that the use of this sealer with all warm compaction techniques might be considered safe from this perspective.