Histological characteristics of newly formed cementum in surgically created one-wall intrabony defects in a canine model

Evaluation of root repair using an environmental scanning electron microscope after intentional contact with microscrew

Objective:

The purpose of this study was to evaluate the amount of root repair that took place at varying intervals of 1 day, 2 weeks, 4 weeks and 8 weeks after intentional contact with microscrews. The results were evaluated by an environmental scanning electron microscope study (E-SEM).

Material and Methods:

Ten orthodontic patients with 2 maxillary and 2 mandibular first premolars (40 premolars) to be extracted as part of the orthodontic treatment were included in this study (age 18–25 years). The position of the roots of the 4 premolars to be extracted was clinically determined and under local anesthesia, microscrew implants were placed in such a way that they directly hit the root from the buccal aspect. Implants were removed immediately after the above-mentioned procedure was performed. On the same day, premolar of the 1st quadrant (Group I) was extracted. Premolar of the 2nd quadrant (Group II) was extracted 2 weeks later. Premolar of the 3rd quadrant (Group III) was extracted 4 weeks later and premolar of the 4th quadrant (Group IV) was extracted 8 weeks later, from the day of intentional damage.

Results:

Significant changes were observed in the deposition of cementum over 8 weeks which were analyzed using ESEM under magnifications of × 50, × 200, × 500, and × 5000.

Conclusion:

The damaged root surfaces due to intentional contact with microscrews showed swift repair and healing within 8 weeks. In case, the root is damaged due to improper placement technique or wrong biomechanics which may result in the implant touching the root surface, a minimum healing period of 8–10 weeks is advocated before commencing further tooth movement.

Visualizing Different Crystalline States during the Infrared Imaging of Calcium Phosphates

Methods utilizing relatively simple mathematical operations during physical analyses to enable the visualization of otherwise invisible correlations and effects are of particular appeal to researchers and students in pedagogical settings. At the same time, discerning the amorphous phase from its crystalline counterpart in materials is challenging with the use of vibrational spectroscopy and is nowhere as straightforward as in phase composition analytical methods such as X-ray diffraction. A method is demonstrated for the use of first- and second-order differentiation of Fourier transform infrared spectra of calcium phosphates to distinguish their amorphous states from the crystalline ones based on the exact line positioning rather than on comparatively vaguer band broadening and splitting effects. The study utilizes a kinetic approach, focusing on the comparison of spectral features of amorphous precursors annealed in air at different temperatures and aged for different periods of time in an aqueous solution until transforming to one or a mixture of crystalline phases, including hydroxyapatite and α- and β-tricalcium phosphate. One of the findings challenges the concept of the nucleation lag time preceding the crystallization from amorphous precursors as a "dead" period and derives a finite degree of constructive changes occurring at the atomic scale in its course. The differential method for highlighting spectral differences depending on the sample crystallinity allows for monitoring in situ the process of conversion of the amorphous calcium phosphate phase to its crystalline analogue(s). One such method can be of practical significance for synthetic solid state chemists testing for the chemical stability and/or concentration of the reactive amorphous phase in these materials, but also for biologists measuring the maturity of bone and medical researchers evaluating its phase composition and, thus, the state of metabolic and mechanical stability.

Characterization of NODs and TLRs in innate immune response of human cementoblast cells

OBJECTIVES

Microbial Pattern-recognition receptors (PRRs), such as Toll-like receptors (TLRs) and the nucleotide-binding oligomerization domains (NODs), are essential for mammalian innate immune response. In this study, we examined the characterization of NODs and TLRs on innate immune responses in human cementoblast (HCEM) cells.

MATERIALS AND METHODS

The gene expression of NODs and TLRs was examined by RT-PCR. Interleukin-6 (IL-6) and Interleukin-8 (IL-8) productions in culture supernatants were measured by ELISA. Western blot analysis was performed to determine the degradation of IκB-α and Mitogen activated protein kinase (MAPK) activation in response to their agonist.

RESULTS

The levels of NODs and TLRs were apparently expressed in HCEM cells. Although a few gene levels were weak in intact cells, the stimulation by their agonists increased the gene expression of TLRs. NODs and TLRs led to the production of IL-6 or IL-8 and the degradation of IκB-α and MAPK activation in HCEM cells. Combination treatment of NOD1 or NOD2 agonists with TLRs agonists did not influence the production of IL-6 and IL-8 in HCEM cells.

CONCLUSIONS

Our results indicate that NODs and TLRs are functionally expressed in HCEM cells and can trigger innate immune responses. However, NOD1 and NOD2 may not be cooperated with TLRs to elicit an immune response in HCEM cells.