Methods: Eleven WT and 8 TG rats were used. Sacrifice times occurred at 22 and 35 weeks. The heads were mechanically defleshed and treated to remove organic material. Heads were then stained with methylene blue to locate the cementoenamel junction. ABL was measured as exposed molar root surface area (mm2) on the buccal and palatal aspects of the maxillas, and lingual aspect of the mandibles. Blinded measurements were performed using a computer assisted image analysis system. Animal ABL was calculated as the mean of the right and left sides.
Results: Mean (±sd) ABL for the TG group (n=8) was 10.68 ± 1.85 and for the WT group (n=11) was 8.16 ± 0.61 mm2. These groups were significantly different (p<0.003; Mann-Whitney U test). At 22 and 35 weeks of age TG rats experienced 22% and 37% greater ABL than WT rats, respectively. These differences at 22 and 35 weeks were statistically significant (p=0.0095 and p=0.0159). For all animals combined, and for each animal type (WT or TG), the difference in ABL was significant between the two age groups.
Conclusions: The results are consistent with previous findings of ABL in female HLA-B27 TG rats. These results give support to this accelerated ABL as being a hormone-independent, age-dependent process and further validate this host as a susceptible animal model suitable for the study of periodontal ABL pathogenesis and treatment.