The efficacy of techniques for the disinfection of artificial sub-surface dentinal caries lesions and their effect on demineralization and remineralization in vitro.
OBJECTIVE
The efficacy of three techniques for the disinfection of artificial sub-surface root caries lesions and their response to subsequent episodes of de- and remineralization was investigated quantitatively in vitro.


METHODS
Sub-surface dentinal lesions (n=20), cut into four experimental blocks and deliberately contaminated with Streptococcus mutans, were subject to either steam autoclaving (121 degrees C, 5min), gamma irradiation (4100Gy), immersion in 0.1% (w/v) thymol-distilled water solution (24h) or reserved as a control. Next, the lesions were incubated aerobically in sterile nutrient broth for 24h at 37 degrees C and resultant cultures plated onto blood agar and neutralisation agar. Ten blocks from each experimental group were then immersed in an acidic buffer solution or exposed to artificial saliva for 5 days. Baseline changes in the mineral content and distribution of the lesions were assessed by transverse microradiography (TMR).


RESULTS
Micro-organisms were recovered from each control block and one block treated by gamma irradiation. Steam autoclaving and immersion in a thymol solution significantly decreased (p<0.05) the amount of mineral lost from the body of lesions subject to a further acid challenge. Mineral ion uptake by lesions exposed to artificial saliva was significantly increased (p<0.05) through disinfection by steam autoclaving.


CONCLUSIONS
Gamma irradiation proved the most acceptable method for the disinfection of sub-surface root dentine lesions having the least adverse effect on demineralization and remineralization.
Preston
K P
KP
School of Dental Sciences, University of Liverpool Dental Hospital and School, Pembroke Place, Liverpool L3 6PS, UK.
Higham
S M
SM
Smith
P W
PW
D000085:Acetates / Q000737:chemistry; D000891:Anti-Infective Agents, Local / Q000627:therapeutic use; D002021:Buffers; D003804:Dentin / Q000187:drug effects / Q000382:microbiology* / Q000528:radiation effects; D003808:Dentin Solubility / Q000187:drug effects / Q000528:radiation effects; D004203:Disinfection / Q000379:methods* / Q000592:standards; D005720:Gamma Rays; D006801:Humans; D007091:Image Processing, Computer-Assisted; D008852:Microradiography; D008903:Minerals / Q000737:chemistry; D017213:Root Caries / Q000382:microbiology*; D012464:Saliva, Artificial / Q000737:chemistry; D013227:Steam; D013242:Sterilization / Q000379:methods; D013295:Streptococcus mutans / Q000187:drug effects / Q000302:isolation & purification / Q000528:radiation effects; D013943:Thymol / Q000627:therapeutic use; D017001:Tooth Demineralization / Q000503:physiopathology*; D014089:Tooth Remineralization
D000085:Acetates; D000891:Anti-Infective Agents, Local; D002021:Buffers; D008903:Minerals; D012464:Saliva, Artificial; D013227:Steam; D013943:Thymol