Restorative Dentistry & Endodontics

Statistical Review Article

Practical considerations and methods for determining sample size to estimate a population mean: a narrative review: Mohamad Adam Bujang; J Korean Acad Conserv Dent ;Published online August 12, 2026; DOI: https://doi.org/10.5395/rde.2026.51.e41 [Epub ahead of print]

Abstract PDF PubReader ePub: Sample size determination plays a crucial role in ensuring the validity and precision of research findings. This paper reviews the concept, rationale, and application of the sample size formula for estimating the mean of a population. It outlines the theoretical foundation, practical calculation steps, and appropriate contexts for its use in descriptive and estimation-based studies. This formula is often overlooked, as many researchers focus primarily on hypothesis testing frameworks rather than estimation approaches. Although it is a classical method, it remains highly relevant and essential in contemporary research. Therefore, this paper highlights the importance of this formula across various research settings and provides detailed guidance on how to compute the required sample size accurately. By doing so, it aims to support proper sample size planning, strengthen research design validity, and ultimately enhance the quality and credibility of scientific investigations.

13 View
0 Download

Original Article

THE EFFECT OF SMEAR LAYER TREATMENT ON THE MICROLEAKAGE: Jung-Min Lee, Sang-Hyuk Park, Gi-Woon Choi; J Korean Acad Conserv Dent 2006;31(5):378-389. Published online January 14, 2006; DOI: https://doi.org/10.5395/JKACD.2006.31.5.378

Abstract PDF PubReader ePub

Abstract

The purpose of this study was to compare the sealing ability of root canal obturation with or without the treatment of smear layer. Eighty extracted human teeth with one canal were selected. Instrumentation was performed with crown-down technique. After instrumentation, root canals of the NaOCl group and NaOCl-6 group were irrigated with 3% NaOCl. EDTA group and EDTA-6 group were irrigated with 17% EDTA. Then all teeth were obturated using continuous wave obturation technique.

NaOCl group and EDTA group were immersed in methylene blue solution for 84hours. NaOCl-6 group and EDTA-6 group were immersed in methylene blue solution for 6months. The teeth were sectioned at 1.5 mm (Level 1), 3.0 mm (Level 2) and 4.5 mm (Level 3) from the root apex. The length of dye-penetrated interface and the circumferential length of canal at each level were measured using Sigma-Scan Pro 5.0.

The mean leakage ratio was decreased cervically.

NaOCl group showed higher mean leakage ratio than EDTA group at each level. But there was significant difference at level 1 only (p < 0.05).

NaOCl-6 group showed higher mean leakage ratio than EDTA-6 group at each level. But there was significant difference at level 1 only (p < 0.05).

NaOCl-6 group showed higher mean leakage ratio than NaOCl group at each level. But there was significant difference at level 1 only (p < 0.05).

EDTA-6 group showed higher mean leakage ratio than EDTA group at each level. But there was no significant difference.

In NaOCl group and NaOCl-6 group, scanning electron micrographs of tooth sections generally covered with smear layer. In EDTA group and EDTA-6 group, tooth sections showing the penetration of sealers to opened dentinal tubules. The results suggest that removal of smear layer was effective to reduce the apical microleakage of the root canal.

Citations

Citations to this article as recorded by

Effect of soft chelating irrigation on the sealing ability of GP/AH Plus root fillings
Yi-Suk Yu, Tae-Gun Kim, Kwang-Won Lee, Mi-Kyung Yu
Journal of Korean Academy of Conservative Dentistry.2009; 34(6): 484. CrossRef
The effect of MTAD as a final root canal irrigants on the coronal bacterial leakage of obturated root canals
Tae Woo Kim, Seok Woo Chang, Dong Sung Park
Journal of Korean Academy of Conservative Dentistry.2008; 33(4): 397. CrossRef

1,768 View
11 Download
2 Crossref

First
Prev
Page of 1
Next
Last

Search