Apical barrier technology to treat chronic apical periodontitis caused by type Ⅱ dens invaginatus: a case report / 华西口腔医学杂志

Dens invaginatusis a rare malformation of the teeth, resulting in frequent pulp necrosis and chronic apical periodontitis. In this paper, the apical barrier technology was used to treat a case of chronic apical periodontitis caused by type Ⅱ dens invaginatus.

Effects of Structural Changes in Subchondral Bone on Articular Cartilage in a Beagle Dog Model / 生物医学与环境科学（英文）

<p><b>OBJECTIVE</b>Using MR T2-mapping and histopathologic score for articular cartilage to evaluate the effect of structural changes in subchondral bone on articular cartilage.</p><p><b>METHODS</b>Twenty-four male Beagle dogs were randomly divided into a subchondral bone defect group (n = 12) and a bone cement group (n = 12). Models of subchondral bone defectin the medial tibial plateau and subchondral bone filled with bone cement were constructed. In all dogs, the left knee joint was used as the experimental sideand the right knee as the sham side. The T2 value for articular cartilage at the medial tibial plateau was measured at postoperative weeks 4, 8, 16, and 24. The articular cartilage specimens were stained with hematoxylin and eosin, and evaluated using the Mankin score.</p><p><b>RESULTS</b>There was a statistically significant difference (P < 0.05) in Mankin score between the bone defect group and the cement group at postoperative weeks 16 and 24. There was a statistically significant difference in the T2 values between the bone defect group and its sham group (P < 0.05) from week 8, and between the cement group and its sham group (P < 0.05) from week 16. There was significant difference in T2 values between the two experimental groups at postoperative week 24 (P < 0.01). The T2 value for articular cartilage was positively correlated with the Mankin score (ρ = 0.758, P < 0.01).</p><p><b>CONCLUSION</b>Structural changes in subchondral bone can lead to degeneration of the adjacent articular cartilage. Defects in subchondral bone cause more severe degeneration of cartilage than subchondral bone filled with cement. The T2 value for articular cartilage increases with the extent of degeneration. MR T2-mapping images and the T2 value for articular cartilage can indicate earlycartilage degeneration.</p>