Periodontal ligament regulatory role in experimental diabetic rat model of periodontium remodelling.

BACKGROUND: Diabetes, among multiple systemic harmful health issues, also may deteriorate normal regenerative and reparative functions of periodontium. The aim of this research was to study the role of periodontal ligament in tissue remodelling under the orthodontic appliance stimulation in two rat experimental models (healthy Wistar rats and Goto-Kakizaki, rodent model of non-obese type 2 diabetes). MATERIALS AND METHODS: Four groups of rats were defined: Wistar (WI; n = 8) and Goto-Kakizaki (GK; n = 8) control groups without orthodontic appliances, and Wistar (n = 16) and Goto-Kakizaki (n = 16) appliance groups with orthodontic appliances. After 42 days, rats were sacrificed and histopathology descriptive analysis about periodontal ligament and adjacent structures was performed as well as cellularity of periodontal ligament and Kappa curvature of tooth roots were measured. RESULTS: Goto-Kakizaki control rats showed statistically significantly higher cellularity in comparison with Wistar control rats (p < 0.001). Both applied groups (WI 44.63 ± 6.68; GK 79.58 ± 10.06) also showed statistically significantly higher cellularity (p < 0.001) in comparison with control groups (WI 34.48 ± 6.92; GK 45.31 ± 11.18). Applied groups (WI 0.197 ± 0.2; GK 0.126 ± 0.083) had statistically significant higher values of Kappa curvature in comparison with control groups (WI 0.023 ± 0.011; GK 0.037 ± 0.011) (WI appliance vs. WI control: p < 0.001; GK appliance vs. GK control: p < 0.05). Agitated periodontal ligament caused different degrees of cementoclasia and additionally dentinoclasia, altering the natural root curvature. CONCLUSIONS: Although not significantly different (WI and GK appliance groups) according to degree of molar roots odontoclasia, higher cellularity of agitated GK periodontal ligament could be influencing factor for, as previously reported, elevated osteoclast mobilization and possible prolonged periodontium reconstitution.

The role of endothelin B receptor in bone modelling during orthodontic tooth movement: a study on ETB knockout rats.

The endothelin system has an important role in bone modelling during orthodontic tooth movement (OTM); however, little is known about the involvement of endothelin B receptors (ETB) in this process. The aim of this study was to evaluate the role of ETB in bone modelling during OTM using ETB knockout rats (ETB-KO). Thirty-two male rats were divided into 4 groups (n = 8 per group): the ETB-KO appliance group, ETB-KO control group, wild type (ETB-WT) appliance group, and ETB-WT control group. The appliance consisted of a super-elastic closed-coil spring placed between the first and second left maxillary molar and the incisors. Tooth movement was measured on days 0 and 35, and maxillary alveolar bone volume, osteoblast, and osteoclast volume were determined histomorphometrically on day 35 of OTM. Next, we determined the serum endothelin 1 (ET-1) level and gene expression levels of the osteoclast activity marker cathepsin K and osteoblast activity markers osteocalcin and dentin matrix acidic phosphoprotein 1 (DMP1) on day 35. The ETB-KO appliance group showed significantly lower osteoblast activity, diminished alveolar bone volume and less OTM than the ETB-WT appliance group. Our results showed that ETB is involved in bone modelling in the late stage of OTM.