Eruptive and functional changes in periodontal ligament fibroblast orientation in CD44 wild-type vs. knockout mice.

BACKGROUND AND OBJECTIVE: Periodontal ligament (PDL) fibroblasts establish principal fibers of the ligament during tooth eruption, and maintain these fibers during occlusion. PDL development and occlusal adaptation includes changes in the orientation of PDL fibroblasts; however, the mechanism for these changes in orientation is unclear. The objective of this study was to compare PDL fibroblast orientation in different stages corresponding with first molar eruption and occlusion in CD44 wild-type (WT) and knockout (KO) mice. MATERIAL AND METHODS: CD44 WT and KO mice were raised to six postnatal stages corresponding with first molar (M1 ) eruption (postnatal day 8, 11, 14 and 18) and occlusion (postnatal day 26 and 41). Coronal sections of the first mandibular molar (M1 ) were prepared and the orientation of fibroblasts in the cervical root region was measured. Angle measurements were compared across developmental stages and between strains using Watson-Williams F-test (oriana software) and ANCOVA. RESULTS: PDL fibroblast orientation increased significantly in CD44 WT (9-87°) and KO mice (14-93°; p ≤ 0.05) between intraosseous eruption (day 11), mucosal penetration (day 14) and preocclusal eruption (day 18); however, the PDL fibroblast orientation did not change significantly with the onset of occlusion (day 26) or continued function (day 41). Within each strain, the variance in fibroblast orientation during preocclusal eruption (day 18) was significantly higher than the variance of all other time points (p < 0.0005). CD44 WT and KO mice showed a similar pattern of PDL development and eruption with a significant difference in CD44 WT vs. KO fibroblast orientations only during early function (day 26, 92° vs 116°; p = 0.05). CONCLUSIONS: The development of PDL fibroblast orientation is highly similar between CD44 WT and KO mice. Between early (day 11) and late (day 18) eruptive stages PDL fibroblast orientation increases, corresponding with the upward movement of M1 . The PDL fibroblast orientation established in preocclusal eruption (day 18) is maintained during early (day 26) and late (day 41) stages of occlusal function, suggesting that PDL cells adapt to mechanical loads in the oral cavity before M1 occlusion.

A first look: determinants of dental care for children in foster care.

PURPOSE: This hypothesis-generating study sought to identify potential determinants of dental care use and oral health among children living in foster care. METHOD: Using a grounded theory approach, fourteen key informant interviews were conducted among health and social services professionals experienced with children in foster care and families in western Washington State. RESULTS: The identified potential determinants of oral health and dental use among children living in foster care included: (1) linguistic and cultural barriers; (2) lack of dentists willing to accept children's Medicaid dental insurance; (3) lack of resources available to case workers (i.e., large caseload burden) (4) lack of federal funding for specialized dental care; (5) lack of systematic health record-keeping; (6) child transience, leading to the lack of a dental home; (8) foster parents' competing needs; (7) child behavior problems; and (9) lack of dental "buy in" from adolescents. CONCLUSION: Additional studies are needed to determine whether children living in foster care achieve oral health, and the extent of their unmet dental need.