The aim of this paper is to discuss the mechanical and geometric features of Nickel-titanium (NiTi) rotary files and its clinical effects. NiTi rotary files have been introduced to the markets with their own geometries and claims that they have better ability for the root canal shaping than their competitors. The contents of this paper include the (possible) interrelationship between the geometries of NiTi file (eg. tip, taper, helical angle, etc) and clinical performance of the files as follows;

- Fracture modes of NiTi rotary files

Based on the reviewed contents, clinicians may have an advice to use various brands of NiTi rotary instruments regarding their advantages which would fit for clinical situation.

This retrospective study evaluated the therapeutic effects of the intentional replantation (IR) procedure performed on the maxillary and mandibular molars of 35 patients.

For the subjects, IR was performed due to difficulties in anatomically accessing the lesions and/or close proximity to the thick cortical bone, inferior alveolar nerve, or maxillary sinus, which rendered the ordinary periradicular surgery impossible. The patients' progress was followed for a year and up to 2 years and 4 months. The success of the procedure was evaluated in terms of clinical and radiographic success (%).

The results revealed the following: (a) 1 case (3%) of failed tooth extraction during IR; (b) 2 cases (6%) of extraction due to periodontal diseases and inflammatory root resorption; (c) 3 cases (9%) of normally functioning teeth in the oral cavity with minor mobility and apical root resorption, and; (d) 29 cases (82%) of normally functioning teeth without obvious problems.

IR was confirmed to be a reliably repeatable, predictable treatment option for those who cannot receive conventional periradicular surgery because of anatomic limitations or patient factors.

The purpose of this retrospective study was to evaluate the success rate of intentionally replanted mandibular second molar with C-shaped canal configurations and to access the impact of preoperative periapical lesion on the success of intentional replantation procedure.

This retrospective chart review study evaluated 52 intentionally replanted mandibular second molar teeth treated at Seoul National University Dental Hospital Department of Conservative Dentistry from January 2005 to December 2007. Seventeen teeth were lost for the follow-up, and another 6 teeth did not meet inclusion criteria of C-shaped root canal configurations. Healing outcome such as success, uncertain healing, and failure after follow-up was evaluated by clinical criteria and radiographs.

The overall success rate was 72.4% for the 29 intentionally replanted C-shaped mandibular second molars. The success rate of replanted teeth with preoperative periapical lesions was similar to that of replanted teeth which have no periapical lesions.

Therefore, root canal treatment failure on C-shaped mandibular second molar can be predictably treated by intentional replantation regardless of the presence of periapical lesion.

In the present study, three kinds of tissues cells (pulp, gingiva, and periodontal ligament) were investigated if those cells express MMP and TIMP when they were stimulated with neuropeptides (substance P, CGRP) or proinflammatory cytokine, TNF-α.

The cells cultured from human dental pulp (PF), gingiva (GF) and periodontal ligament were (PDLF) stimulated with Mock, SP, TNF-α, and CGRP for 24 hrs and 48 hrs. for an RNase protection assay and Enzyme Linked Immunosorbent Assay.

Cells (PF, GF and PDLF) seeded in 100 mm culture dish were stimulated with SP (10^-5, 10^-8 M) or only with medium (Mock stimulation) for 4hrs and for 24 hrs for RNase Protection Assay, and they were stimulated with CGRP (10^-5 M) and TNF-α (2 ng/mL) for 24 hrs and with various concentraion of TNF-α (2, 10, and 100 ng/mL) for Rnase Protection Assay with a human MMP-1 probe set including MMP 1, 2, 8, 7, 8, 9, 12, and TIMP 2, 3.

In addition, cells (PF, GF and PDLF) were stimulated with Mock and various concentraion of TNF-α (2, 10, and 100 ng/mL) for 24 hrs and with TNF-α (10 ng/mL) for 48 hrs, and the supernatents from the cells were collected for Enzyme Linked Immunosorbent Assay (ELISA) for MMP-1 and MMP-13.

The expression of MMPs in PF, GF, PDLF after stimulation with SP and CGRP were not changed compared with Mock stimulation for 4 hrs and 24 hrs. The expression of MMP-1, -12, -13 24 hrs after stimulation with TNF-α were upregulated, however the expression of TIMP-3 in PF, GF, PDLF after stimulation with TNF-α were downregulated. TNF-α (2 ng/mL, 10 ng/mL, 100 ng/mL) increased MMP-1 and MMP-12 expression in PF dose dependently for 24 hrs.

TNF-α in the area of inflammation may play an important role in regulating the remodeling of dentin, cementum, and alveolar bone.

The aim of this study was to evaluate the surface color of indirect resin restoration according to the layering placement of different shade of incisal composite.

In this study, CIE L*a*b* value of 16 Body composite of Tescera ATL (Bisco, Schaumburg IL, USA) was measured by spectrophotometer (NF999, Nippon Denshuku, Japan), and compared to CIE L*a*b* value of Vitapan shade guide. Nine shade Incisal composite of Tescera ATL were buildup to 1 mm thickness on Body composites inlay block, and CIE L*a*b* value was measured. Incisal composite was ground to 0.5 mm thickness and CIE L*a*b* value was re-measured. Color difference between Body composite and Incisal composites layered on Body composite was calculated as a function of thickness.

Color difference between corresponding shade of Tescera Body composite and Vitapan shade guide was from 6.88 to 12.80.

L* and b*value was decreased as layering thickness of Incisal composite on Body composite was increased. But, a* value did not show specific change tendency.

Surface color difference between Body composites and Incisal composites layered on Body composite was increased as the layering thickness of Incisal composite increased (p < 0.05).

The purpose of this study was to compare the microshear bond strength (uSBS) of two total-etch and four self-etch adhesive systems and a flowable resin to enamel.

Enamels of sixty human molars were used. They were divided into one of six equal groups (n = 10) by adhesives used; OS group (One-Step Plus), SB group (Single Bond), CE group (Clearfil SE Bond), TY group (Tyrian SPE/One-Step Plus), AP group (Adper Prompt L-Pop) and GB group (G-Bond).

After enamel surfaces were treated with six adhesive systems, a flowable composite resin (Filek Z 350) was bonded to enamel surface using Tygon tubes. the bonded specimens were subjected to uSBS testing and the failure modes of each group were observed under FE-SEM.

1. The uSBS of SB group was statistically higher than that of all other groups, and the uSBS of OS, SE and AP group was statistically higher than that of TY and GB group (p < 0.05).

2. The uSBS for TY group was statistically higher than that for GB group (p < 0.05).

3. Adhesive failures in TY and GB group and mixed failures in SB group and SE group were often analysed. One cohesive failure was observed in OS, SB, SE and AP group, respectively.

Although adhesives using the same step were applied the enamel surface, the uSBS of a flowable resin to enamel was different.

The purpose of this study is to compare the apical transportation and working length change in curved root canals created in resin blocks, using 3 geometrically different types of Ni-Ti files, K3, NRT, and Profile.

The curvature of 30 resin blocks was measured by Schneider technique and each groups of Ni-Ti files were allocated with 10 resin blocks at random. The canals were shaped with Ni-Ti files by Crown-down technique. It was analyzed by Double radiograph superimposition method (Backman CA 1992), and for the accuracy and consistency, specially designed jig, digital X-ray, and CAD/CAM software for measurement of apical transportation were used. The amount of apical transportation was measured at 0, 1, 3, 5 mm from 'apical foramen - 0.5 mm' area, and the alteration of the working length before and after canal shaping was also measured. For statistics, Kruskal-Wallis One Way Analysis was used.

There was no significant difference between the groups in the amount of working length change and apical transportation at 0, 1, and 3 mm area (p = 0.027), however, the amount of apical transportation at 5 mm area showed significant difference between K3 and Profile system (p = 0.924).

As a result of this study, the 3 geometrically different Ni-Ti files showed no significant difference in apical transportation and working length change and maintained the original root canal shape.