Nd:YAG laser irradiation of the tooth root surface inhibits demineralization and root surface softening caused by minocycline application.
OBJECTIVE
The aim of this study was to investigate the effect of laser irradiation on root surface demineralization caused by local drug delivery systems (DDS), and to evaluate the effect of sealing on drug retention.


BACKGROUND
The duration of supportive periodontal treatment (SPT) has increased with increasing life expectancy. Repeated root planing and DDS application during SPT should be reconsidered with regard to their effects on the root surface.


METHODS
Extracted human teeth were collected, cut into 3 × 3 × 2 mm root dentin specimens, and divided randomly into eight groups with various combinations of Nd:YAG laser power (0, 0.5, 1, and 2 W), with and without DDS (minocycline HCl). Specimen microhardness and calcium (Ca) solubility were measured after treatment. The specimens (control and laser and DDS groups) were examined by scanning electron microscopy. Forty SPT patients were recruited, to assess the effect of periodontal pocket sealing on drug retention.


RESULTS
Laser irradiation increased the microhardness of root specimens in an energy-dependent manner. Calcium solubilities decreased from the 0 W+DDS group to the 2.0 W+DDS group. The mean Ca solubilities in the 1.0 W+DDS and 2.0 W+DDS groups were significantly lower than in the 0 W+DDS group (p<0.01, p<0.001, respectively). Laser irradiation counteracted the softening effect of DDS. Morphologic change was observed in the 2 W+DDS group; however, no morphologic changes were observed in the control and the 1 W+DDS groups. The mean concentration of minocycline in the periodontal pocket 24 h after application was 252.79 ± 67.50 μg/mL.


CONCLUSIONS
Laser irradiation of the root surface inhibited the softening and decalcification caused by minocycline HCl. Sealing the periodontal pockets effectively improved drug retention. These results suggest that the combination of laser irradiation and DDS could benefit patients receiving repeated SPT.
1 Department of Periodontology, School of Dentistry, Aichi Gakuin University , Chikusa-ku, Nagoya, Aichi, Japan .
Tomohisa
T
Watanabe
Mitsuo
M
Fukuda
Akio
A
Mitani
Chun-Chan
CC
Ting
Kazuhiro
K
Osawa
Ayako
A
Nagahara
Sohta
S
Satoh
Takeki
T
Fujimura
Shinko
S
Takahashi
Yuki
Y
Iwamura
Taeko
T
Murakami
Toshihide
T
Noguchi
D006801:Humans; D066298:In Vitro Techniques; D053844:Lasers, Solid-State / Q000627:therapeutic use*; D008911:Minocycline / Q000494:pharmacology*; D017001:Tooth Demineralization / Q000517:prevention & control*; D014092:Tooth Root / Q000187:drug effects* / Q000528:radiation effects*
D008911:Minocycline