Sample size estimation: An overview with applications to orthodontic clinical trial designs
Nikolaos Pandis, Argy Polychronopoulou, and Theodore Eliades. Am J Orthod Dentofacial Orthop 2011;140:e141-e146
Proper sample size estimation is an important part of clinical trial methodology and closely related to the precision and power of the trial’s results. Trials with sufficient sample sizes are scientifically and ethically justified and more credible compared with trials with insufficient sizes. Planning clinical trials with inadequate sample sizes might be considered as a waste of time and resources, as well as unethical, since patients might be enrolled in a study in which the expected results will not be trusted and are unlikely to have an impact on clinical practice. Because of the low emphasis of sample size calculation in clinical trials in orthodontics, it is the objective of this article to introduce the orthodontic clinician to the importance and the general principles of sample size calculations for randomized controlled trials to serve as guidance for study designs and as a tool for quality assessment when reviewing published clinical trials in our specialty. Examples of calculations are shown for 2-arm parallel trials applicable to orthodontics. The working examples are analyzed, and the implications of design or inherent complexities in each category are discussed.
Effect of a self-etching adhesive containing an antibacterial monomer on clinical periodontal parameters and subgingival microbiologic composition in orthodontic patients
Mihri Amasyali, Sukru Enhos, Tancan Uysal, Isil Saygun, Abdullah Kilic, and Orhan Bedir. Am J Orthod Dentofacial Orthop 2011;140:e147-e153
I ntroduction: The aims of this study were to evaluate the effect of a self-etching adhesive system containing an antibacterial monomer on periodontal health and subgingival microbiologic composition in orthodontic patients and to compare it with a conventional adhesive system. Methods: A split-mouth design was chosen, and 15 patients were included in the study. Brackets in contralateral quadrants were bonded with either a conventional adhesive system (control) or a self-etching adhesive system that contained an antibacterial monomer. Clinical periodontal parameters including plaque index, gingival index, probing depths, and bleeding on probing were determined. Subgingival plaque samples were collected before bracket placement (T0) and at the 6-month follow-up (T1). The real-time TaqMan polymerase chain reaction assay was used to determine the subgingival counts of Porphyromonas gingivalis , Tannerella forsythensis , Prevotella intermedia , Aggregatibacter actinomycetemcomitans , Fusobacterium nucleatum , and Campylobacter rectus . For clinical periodontal parameters, analysis of covariance (ANCOVA) and, for bacterial counts, Wilcoxon tests were used for statistical comparisons at the P <0.05 level. Results: Clinical periodontal parameters were not changed, and they were not different between the groups from T0 to T1. T forsythensis and F nucleatum increased during the treatment period in both groups ( P <0.05). The majority of the bacteria were T nucleatum at T0 and T1 in both groups. Changes in bacterial load from T0 to T1 were not different between groups except for T forsythensis and F nucleatum ( P <0.05). Conclusions: The use of an antibacterial monomer did not have an additional positive effect on clinical periodontal parameters. When used in bonding orthodontic brackets, the antibacterial monomer failed to reduce periodontopathogenic bacteria when compared with the conventional adhesive system during a 6-month treatment period.
Effect of a self-etching adhesive containing an antibacterial monomer on clinical periodontal parameters and subgingival microbiologic composition in orthodontic patients
Mihri Amasyali, Sukru Enhos, Tancan Uysal, Isil Saygun, Abdullah Kilic, and Orhan Bedir. Am J Orthod Dentofacial Orthop 2011;140:e147-e153
I ntroduction: The aims of this study were to evaluate the effect of a self-etching adhesive system containing an antibacterial monomer on periodontal health and subgingival microbiologic composition in orthodontic patients and to compare it with a conventional adhesive system. Methods: A split-mouth design was chosen, and 15 patients were included in the study. Brackets in contralateral quadrants were bonded with either a conventional adhesive system (control) or a self-etching adhesive system that contained an antibacterial monomer. Clinical periodontal parameters including plaque index, gingival index, probing depths, and bleeding on probing were determined. Subgingival plaque samples were collected before bracket placement (T0) and at the 6-month follow-up (T1). The real-time TaqMan polymerase chain reaction assay was used to determine the subgingival counts of Porphyromonas gingivalis , Tannerella forsythensis , Prevotella intermedia , Aggregatibacter actinomycetemcomitans , Fusobacterium nucleatum , and Campylobacter rectus . For clinical periodontal parameters, analysis of covariance (ANCOVA) and, for bacterial counts, Wilcoxon tests were used for statistical comparisons at the P <0.05 level. Results: Clinical periodontal parameters were not changed, and they were not different between the groups from T0 to T1. T forsythensis and F nucleatum increased during the treatment period in both groups ( P <0.05). The majority of the bacteria were T nucleatum at T0 and T1 in both groups. Changes in bacterial load from T0 to T1 were not different between groups except for T forsythensis and F nucleatum ( P <0.05). Conclusions: The use of an antibacterial monomer did not have an additional positive effect on clinical periodontal parameters. When used in bonding orthodontic brackets, the antibacterial monomer failed to reduce periodontopathogenic bacteria when compared with the conventional adhesive system during a 6-month treatment period.
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