Introduction
The aims of this study were to evaluate the in-vivo reaction of newly erupted enamel to demineralization around orthodontic brackets and to compare it with that of mature enamel.
Methods
Thirteen orthodontic patients scheduled to have 4 first premolars extracted for orthodontic reasons were divided into 2 groups. Group 1 included 7 younger patients with newly erupted teeth (4 boys, 3 girls; mean age, 11.21 ± 1.12 years; range, 11-13 years). Group 2 contained 6 adults with mature teeth (5 men, 1 woman; mean age, 34.64 ± 4.01 years; range, 25-41 years). Brackets were placed, and, 30 days later, the teeth were extracted. These teeth were longitudinally sectioned, and demineralization was assessed by cross-sectional microhardness. Determinations were made at the bracket-edge composite limits and at occlusal and cervical points 100 μm away. Evaluations under the brackets and at the lingual surfaces were made as controls. In all these positions, 6 indentations were made at depths from 10 to 90 μm from the enamel surface. Analysis of variance (ANOVA) and Tukey tests were used for statistical evaluation at the P <0.05 level.
Results
ANOVA showed statistically significant differences for tooth type, position, depth, and their interactions ( P <0.05), except the tooth type and position interaction. The multiple comparison test showed less demineralization in the enamel around orthodontic brackets bonded to mature teeth campared with newly erupted teeth ( P <0.05).
Conclusions
During the 30-day study period, the tooth enamel in the adult orthodontic patients was more resistant to demineralization than that of the younger patients.
Editor’s comment
Your first consult of the day, a 37-year-old woman, posed a question that you had not heard before. She said that her younger brother had worn braces as an 11-year-old and had problems with decalcification when the braces were removed. Should she expect a similar problem if she went ahead with treatment today? With experience in treating adults for many years, you are quick to respond. “Although decalcification can be a problem with children, adults take better care of their teeth, and decalcification does not seem to be a problem for them. In fact, their teeth appear to be more resistant to enamel decalcification.” That reasoning satisfies the patient, but is it true? Is mature enamel more resistant to decalcification?
The aims of this study were to evaluate in vivo the reactions of newly erupted enamel to demineralization around orthodontic brackets and to compare it quantitatively with the response of more mature enamel. The subjects were 13 patients slated for the removal of 4 premolars. The sample was divided into a younger (11-13 years old) group and an older (25-41 years old) one. The study was designed to compare the microhardness between relatively newly erupted premolars and mature premolars after 30 days of wearing brackets and using a nonfluoridated toothpaste.
After extraction of the premolars, the demineralization values of the enamel under each bracket and on the lingual surface of each premolar were used to evaluate the effect of acid etching and demineralization. The results showed that mature teeth have significantly less enamel mineral loss compared with newly erupted teeth in a group of orthodontic patients. This suggests that, in the short term, adult patients’ teeth are more resistant to demineralization than those of younger patients. Of course, this study would have been even more interesting if the authors had started with a larger sample and the internal review board had considered it ethical to allow a longer study period.
