The effect of chemical inhibition of matrix metalloproteinases on the size of experimentally induced apical periodontitis.
OBJECTIVE
To determine the effect of matrix metalloproteinase (MMP) inhibition on periapical lesion formation in a rat model.


METHODS
The pulp chambers of mandibular fist molars of adult SD rats were exposed to be infected by oral microbes. The experimental group was fed 20 mg kg(-1) MMP-inhibitor chemically modified tetracycline-3 (CMT-3) daily in an oral gavage and the controls were fed the vehicle. After 2 and 4 weeks, the mandibles (n = 10 in both groups at both times) were radiographed, decalcified and subjected to histological analysis. Extension of necrosis in first molar distal root canals was measured from the histological sections, and periapical lesion sizes in the same roots were determined from radiographs and histological sections. Mann-Whitney U-test was used for the statistical analysis.


RESULTS
There was a statistically significant difference in the extension of necrosis in root canals between 2 and 4 weeks in the control group (P < 0.05), but not with MMP inhibition. Radiographically, MMP inhibition increased the periapical lesion size by 70% and 34% after 2 and 4 weeks respectively (P < 0.05 in after 2 weeks). In histological measurements, lesion size increased with MMP inhibition by 26% and 8% after 2 and 4 weeks respectively.


CONCLUSIONS
MMP inhibition affects pulpal and periapical inflammation, increasing the rate of spreading of necrosis in root canals and the rate of periapical lesion formation.
Tjäderhane
L
L
Institute of Dentistry, University of Helsinki, Helsinki, Finland. leo.tjaderhane@helsinki.fi
Hotakainen
T
T
Kinnunen
S
S
Ahonen
M
M
Salo
T
T
D000818:Animals; D016866:Bacteroidaceae Infections / Q000201:enzymology; D003790:Dental Pulp Necrosis / Q000201:enzymology*; D004791:Enzyme Inhibitors / Q000494:pharmacology; D005260:Female; D061965:Matrix Metalloproteinase Inhibitors; D020782:Matrix Metalloproteinases / Q000502:physiology*; D010485:Periapical Periodontitis / Q000201:enzymology*; D016966:Porphyromonas gingivalis; D051381:Rats; D017207:Rats, Sprague-Dawley; D013754:Tetracyclines / Q000494:pharmacology
D004791:Enzyme Inhibitors; D061965:Matrix Metalloproteinase Inhibitors; D013754:Tetracyclines; C117155:tetracycline CMT-3; D020782:Matrix Metalloproteinases