Method: Intact non-carious human teeth were obtained. Teeth were sectioned into approximately 3mmx3mm squares and embedded in resin. Samples were polished using 600-grit SiC paper to obtain a flattened enamel surface (Ecomet®, Buehler). Samples were randomly assigned to two groups (n=20): normal enamel (NE) and demineralized enamel (DE). The DE group was immersed in a demineralizing solution (Queiroz et.al, 2008) for 32hrs at 370C to create artificial demineralized lesions. Each group was randomly divided into four subgroups (n=5) and treated with microabrasion material (Opalustre®, Ultradent) with variation of techniques: cotton swab for 30 or 60sec or rotary prophy cup for 30 or 60 sec. All samples were abraded using a light pressure determined by a digital scale. Samples were cross-sectioned (Isomet®, Buehler). The removal depths were measured under stereo microscope (Olympus SZX16®) with analysis software (Omninet 9.0, Buehler). Statistical analysis was done using Independent Samples T-test.
Result:
Depth of Enamel Removal Based on Technique
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Time=30 |
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Time=60 |
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Rotary (n=5) |
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Swab (n=5) |
|
p-value |
|
Rotary (n=5) |
|
Swab (n=5) |
|
p-value |
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Mean |
95% CL mean (µm) |
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Mean |
95% CL mean (µm) |
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|
|
Mean |
95% CL mean (µm) |
|
Mean |
95% CL mean (µm) |
|
|
DE |
105.9 |
28.8-183.1 |
|
41.2 |
34.4-47.9 |
|
.049 |
|
216.5 |
153.2-279.7 |
|
74.1 |
59.0-89.1 |
|
.0003 |
NE |
53.6 |
47.9-59.2 |
|
35.7 |
27.1-44.3 |
|
.002 |
|
55.3 |
40.7-69.9 |
|
53.3 |
44.9-61.7 |
|
.759 |
Conclusion: Results from all groups were normally distributed (Shapiro-Wilk test). On DE, the focus of treatment, at t=30, enamel removal using swab had a mean (95% CL) of 41.2µm (34.3-47.9), and rotary was greater at 105.9µm (28.8-183.1) (p=.049). DE depth at t=60 using swab had a mean (95% CL) of 74.1µm (59.0-89.1), and rotary was again greater at 216.5µm (153.2-279.7) (p=.003). Small sample size limited comparison between time points. Greatest enamel removal was observed using rotary and after greater time (t=60). By referencing these techniques based on time and instrument used, a more efficient and accurate microabrasion procedure can be clinically accomplished.