Letter to the Editor

Dear Editor,

We appreciated the article published in your journal, Operative Dentistry, titled “Ferrule design does not affect the biomechanical behavior of anterior teeth under mechanical fatigue: an in vitro evaluation.”¹ It was a quality study and threw light upon the factors that are necessary to consider for clinical application, while performing similar studies on ferrule. However, we would appreciate it if the authors could attend to the following concerns regarding the study.

1. There are differences in the properties of bovine and human teeth, and since this study evaluated biomechanical properties, the results may not be clinically relevant. Bovine enamel has been found to have significantly less microhardness value and higher wear as compared with human enamel.² There are also significant differences in the bond strength and shear bond strength of bovine and human teeth.^3-4

2. The title of the study is suggestive of a conclusion rather than an insight to the study.

3. The conclusions of the cross reference quoted in the study have shown contrasting results, but the present study mentioned otherwise, stating “Ma and others reported a statistical difference between no-ferrule, 0.5-mm ferrule, and 1-mm ferrule designs, with an effect size that varied from 154,925 load fatigue cycles (mean difference between no-ferrule and 0.5-mm ferrule groups) to 262,659 cycles (mean difference between no-ferrule and 1-mm ferrule groups)”; however, in the original article by Ma and others, it was concluded that teeth with a 1.0-mm ferrule showed a significantly higher fatigue cycle count than the no-ferrule group (p=0.008) but were not statistically different from the 0.5-mm ferrule group (p=0.032).⁵

4. The masticatory forces acting on the anterior teeth ranges from 382N to 108N, respectively, for males and females.⁶ However, in the present study the dynamic load testing applied a load of up to 550N, which may not be clinically relevant.

Dr Anwetakshmi Ray

Post-graduate student

Department of Conservative Dentistry & Endodontics Manipal College of Dental Sciences, Mangalore

Affiliated to Manipal Academy of Higher Education, Manipal

anwetakshmiray@gmail.com

Dr M Kundabala, BDS, MDS

Department of Conservative Dentistry & Endodontics Manipal College of Dental Sciences, Mangalore

Affiliated to Manipal Academy of Higher Education, Manipal

Kunda.kamath@manipal.edu

Dr Neeta Shetty, BDS, MDS

Department of Conservative Dentistry & Endodontics Manipal College of Dental Sciences, Mangalore

Affiliated to Manipal Academy of Higher Education, Manipal

Neeta.shetty@manipal.edu