Sample size calculation practices in original research articles of the Journal of Conservative Dentistry and...

Sample size calculation is essential for methodological rigor and statistical validity in dental research, yet deficiencies in its reporting and coherence with statistical analysis remain frequent. This study aimed to evaluate the frequency and methodological coherence of sample size calculation practices in original research articles published in the Journal of Conservative Dentistry and Endodontics (JCDE).

A methodological review was conducted, including original research articles published between January 2021 and December 2025. Extracted variables comprised study design, sample size reporting, characteristics of the sample size calculation, statistical tests applied, and coherence between the calculation model and the final analysis. Study designs were grouped into in vitro, clinical, and observational categories. Descriptive statistics were summarized using absolute and relative frequencies. Bivariate associations were assessed using the chi-square test, and multivariable logistic regression was used to identify factors independently associated with methodological coherence.

Of 631 eligible articles, 176 (27.9%) reported a sample size calculation. Complete and methodologically coherent reporting was identified in only 9 studies (1.43%). Methodological coherence differed significantly by study design in bivariate analyses (p < 0.05). In the adjusted model, clinical and observational studies showed higher odds of coherent sample size calculation compared with in vitro studies.

Sample size calculations in JCDE are infrequently reported and often methodologically incoherent. Study design appears to be a key determinant of coherence, underscoring the need for improved integration of statistical planning and reporting standards.