Comparison of particle morphology between commercial- and research-grade calcium hydroxide in endodontics

Effect of Ultrasonic Activation on Dentinal Tubule Penetration of Bio-C Temp and Ultracal XS: A Comparative CLSM Assessment

OBJECTIVE

The aim of this study was to compare the effect of ultrasonic activation (UA) on tubular penetration between Bio-C Temp and Ultracal XS intracanal medicaments.

METHODS

Forty single-rooted human premolars were endodontically prepared and divided into 4 experimental groups (n=10): Bio-C Temp, Bio-C Temp+UA, UltraCal XS and UltraCal XS+UA. All medicaments were previously mixed with a specific calcium marker (Fluo-3) and passively injected into the canals. The samples were incubated for 7 days. For each tooth, 1 mm thick sections were obtained from the middle and apical thirds of the canals. The samples were examined by confocal laser scanning microscopy (CLSM) and the depth and area of penetration were determined for each group. The Student t test was used to compare results between groups (p<0.05).

RESULTS

UA increased the depth and penetration area of Bio-C Temp and Ultracal XS, showing significant differences in the penetration area of the apical third for Bio-C Temp (p<0.0339). Bio-C Temp presented greater tubular penetration than Ultracal XS, showing significant differences in the depth of penetration in the apical third (p<0.0005), and in the penetration area in the middle (p<0.0016) and apical third (p<0.0339) after UA.

CONCLUSION

UA increases tubular penetration (both depth and area) of Bio-C Temp at the apical third but has no significant effect on Ultracal XS. Bio-C Temp has a greater depth and tubular penetration area than Ultracal XS after UA. (EEJ-2023-02-024).

Carbonation inhibitor by polyethylene glycol encapsulation of calcium hydroxide fine particles to improve antimicrobial and root canal penetration properties

The carbonation of calcium hydroxide (Ca(OH)₂) is affected by humidity and a saturated atmosphere. Ca(OH)₂ from nature is easily carbonation and self-aggregates into calcium carbonate (CaCO₃), resulting in larger particle size impairing the antimicrobial properties due to lack of penetration into the dentinal tubules and lower ion dissociation. To reduce the particle size, the wet beads milling process with distilled water as the medium is commonly used, but often results in great carbonation of the final product. Polyethylene Glycol (PEG) may inhibit the carbonation process as well as re-agglomeration. However, it requires intensive drying of the fine Ca(OH)₂ particles. As an alternative, we used ethanol as a medium in the milling process, which is easily dried and compatible with PEG as a surfactant. This study aimed to evaluate PEG 400 as a dispersing agent in ethanol medium in the beads milling process to prevent carbonation of the fine Ca(OH)₂ particles. The following groups were analysed CaP-PEG (Ca(OH)₂-PEG) with ethanol as a medium, CaP-Eth (Ca(OH)₂ with ethanol as a medium), CaP-DW (Ca(OH)₂ with distilled water as a medium), CaPC (Ca(OH)₂-carbonated) as the negative control and CaC (Ca(OH)₂ analytical grade) as the positive control The final particle results were characterized to evaluate the crystal structure, functional groups, and particle size. The corresponding pH and antimicrobial activity against Enterococcus faecalis were assessed at 1, 3, 7, and 14 days. The penetration ability was evaluated by Scanning Electron Microscope. The data obtained were analysed by ANOVA with a significance level of 5%. PEG was able to inhibit carbonation and stabilize pH for up to 14 days, providing increased antimicrobial activity against E. faecalis. PEG also facilitates the ability of fine Ca(OH)₂ particles to penetrate deeper into the dentine tubules by reducing particle size.

Facile synthesis of highly tunable monodispersed calcium hydroxide composite particles by using a two-step ion exchange reaction

“Calcium hydroxide [Ca(OH)₂]” is a medicament frequently used for antimicrobial purposes in endodontic procedures, or it is used as a toxic-waste adsorbent in industry. Ca(OH)₂ particles produced through conventional methods are size untunable and have a wide size distribution and polygonal shape. In this paper, a novel and facile approach involving template-mediated synthesis and two-step ion exchange is proposed for uniform size Ca(OH)₂ composite particles generation. “Sodium-alginate (Na-alginate)” was used as a precursor, and monodisperse Na-alginate emulsions were formed through needle droplet or droplet microfluidic technology. After the first ion exchange step with the Ca²⁺ ions, “calcium-alginate (Ca-alginate)” particles were obtained. The Ca-alginate particles were intermediate reaction products and were designed to be the templates for ensuring the spherical shape and size of products. The OH⁻ ions were used for the second ion exchange step to fabricate Ca(OH)₂ composite particles. The results revealed that the Ca(OH)₂ composite particles were size tunable, had a spherical shape, and were monodisperse (with a relative standard deviation of less than 8%). The 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl tetrazolium bromide (MTT) assay revealed that the Ca(OH)₂ composite particles were potential biocompatible materials.

The synthesized Ca(OH)₂ composite particles were size tunable, had a spherical shape, and were monodisperse.

Diffusion of calcium hydroxide through dentinal tubules of retreated root canals: An in vitro study

Objective:

Studies about the dispersion of hydroxyl ions through dentin of endodontically retreated teeth are scarce. The present study aims at examining the diffusion of calcium hydroxide in vitro by recording the pH changes of retreated root canal using two types of calcium hydroxide preparations.

Materials and Methods:

A total of 45 recently extracted single-rooted mandibular first premolars were collected and cleaned from calculus and remains of periodontal tissue. The teeth so collected were stored in thymol 10% solution till use. During collection, teeth with cracks, open apices, and restorations were excluded. Root canal preparations were performed using Protaper rotary system files, till #F3 file. All canals were obturated using cold lateral condensation and zinc oxide-based sealer. After 7 days, all gutta-percha were removed and the canals were irrigated with normal saline. The teeth were then randomly distributed into three groups. Canals in Group I were kept empty without any dressing to serve as a negative control group, Canals in Group II were filled with a freshly prepared mixture of calcium hydroxide powder with normal saline solution, and Group III was filled with Metapex. Periodically, the calcium hydroxide material was removed and the pH was measured using pH meter at 7, 10, 14, and 30 days.

Results:

The pH values of Group II and III ranged between 9.2 and 11.2. This was found to be highly significant against the negative control group. After 7 and 10 days, freshly mixed Ca(OH)₂ showed the higher pH than the creamy Metapex, and statistically the difference was highly significant after 10 days (P<0.001). After 14 days, Metapex group pH was higher than freshly mixed Ca(OH)₂, but it was not statistically significant as they reached nearly the same pH after 30 days (P>0.05).

Conclusion:

All Ca(OH)₂ preparations had high pH around the roots after 7 and 10 days. Metapex continued to have higher pH after 14 days.