Authors’ response

We thank the Editor for allowing us to respond to the comments on our article, “Effects of magnitude of intrusive force on pulpal blood flow in maxillary molars,” published in July 2015. We appreciate the investigators’ interest in this topic and thank them for their careful observations.

We want to point out that the aim of our study was to evaluate blood-flow changes in the pulp tissues of maxillary molars after intrusion. We wanted to use contralateral molars in the same subjects as control teeth to reduce the effects of differences in patient responses and root-surface areas. Therefore, we selected overerupted maxillary molars for intrusion.

Regarding the comments on our inclusion and exclusion criteria, we endorse the criticism that it would have been better to elaborate the inclusion and exclusion criteria separately rather than together, as in the article. Accordingly, the inclusion criteria were (1) age, 20-40 years; (2) clinically healthy maxillary first molars (free of caries, restorations, defects, and discolorations) and periodontal tissues (normal gingival appearance, no mobility); (3) 1 overerupted maxillary first molar and the other maxillary first molar in normal occlusion; (4) radiographically healthy maxillary first molars (visible pulp chamber and root canals) and normal periapical tissues with no obliterated root canals, pulp stones, or diffuse calcifications; and (5) no history of smoking or systemic vascular disease.

Another issue noted had to do with the initial sample calculation. Although it would have been better to make a sample calculation, we had difficulties in obtaining ethical approval for larger sample sizes. Moreover, as is known, overeruption can be expected to occur when an opposing tooth is lost and is usually observed in older adults; for this reason, few younger patients (<40 years) have overerupted maxillary first molars.

Details of sex and age were also questioned. Of the 20 patients, 13 were men, and 7 were women, and the most frequent age was 28 years. In this regard, the most important issue commented upon was the age-related reduction in pulp-chamber size. We agree that age is a major issue, whatever the orthodontic approach. To eliminate variations in pulp related to increases in dentin deposition, decreases in pulp-chamber size and reductions in pulpal blood flow that can occur with increasing age, we selected subjects between 20 and 40 years (mean age, 27.6 years), and only 3 of the 20 subjects were above 30 years, the age at which the size of the pulp chamber begins to decrease.

Only 1 previous laser Doppler flowmetry study has reported on the effects of age on human pulp hemodynamics. Ikawa et al examined subjects between 8 and 75 years distributed in groups of 8 to 20, 20 to 40, 40 to 60, and 60 to 80 years; the authors indicated that resting pulpal blood flow during the control reading decreased with age. As with this earlier study, we selected the same age range (20-40 years) for young adults. During the study, we realized that the effect of orthodontic treatment on pulpal vasculature and blood-flow changes with regard to age has not yet been studied with laser Doppler flowmetry. Thus, we conducted a new study addressing this topic, and an article reporting on this study entitled “Effect of age on pulpal blood flow in human teeth during orthodontic movement” has been sent to AJO-DO and is currently under review. If accepted, we believe that this article will fill the gap in the literature about age-related changes in pulpal vasculature after orthodontic tooth movement.

Finally, the issue about standardization of the pulp chamber area was raised. As with most laser Doppler flowmetry studies, we did not apply a method of standardization in this regard. Further research is required that combines radiographic measurements (eg, apical foramen diameter, number of root canals, and pulp chamber dimensions) with pulpal blood flow data.

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Apr 6, 2017 | Posted by in Orthodontics | Comments Off on Authors’ response
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