Cystathionine gamma‐lyase aggravates periodontal damage in traumatic occlusion mouse models

Abstract

Background and objective Though impacts of traumatic occlusion (TO) on periodontal tissues and roles of cystathionine γ‐lyase (Cth) gene in the regulation of bone homeostasis have been studied by many, no consensus has been reached so far on whether TO deteriorates the periodontium and precise roles of Cth in occlusal trauma. Therefore, this study aims to investigate the impacts of TO on periodontal tissues and the involvement of Cth gene. Methods Eighty C57BL/6 wild‐type (WT) mice and Cth knockout (Cth−/−) mice, 8 weeks old, were used in this study. The TO model was established using composite resin bonding on the left maxillary molar for one, two, and three weeks, respectively. Morphological and histological changes in the periodontium were assessed by micro‐computed tomography (micro‐CT), hematoxylin and eosin (H&E) staining, and tartrate‐resistant acid phosphatase (TRAP) staining. Osteoclast‐related genes were analyzed by real‐time polymerase chain reaction (qPCR). Results It was found that decreased alveolar bone height, expanded bone resorption area, and increased width of periodontal ligament (PDL) occurred in TO models, accompanied by an increased number of osteoclasts in a time‐dependent manner by micro‐CT and histological staining. Osteoclast‐related genes including Ctsk, Mmp9, Rank, Trap, and Rankl/Opg were also up‐regulated after one week of modeling. The up‐regulated expressions of Cth gene and its protein CTH were observed in TO mouse models. After 1, 2, or 3 weeks of modeling, WT mice showed more severe alveolar bone resorption, wider PDL, higher osteoclast count, and higher levels of osteoclast‐related genes Ctsk, Rank, and Rankl/Opg than Cth−/− mice. Conclusion TO causes a reduction in alveolar bone height and PDL morphological disorder with their severity increases in a time‐dependent manner. Cth aggravates periodontal damage caused by TO.

Occlusal Trauma and Bisphosphonate-Related Osteonecrosis of the Jaw in Mice

“…Similar to the findings for the PDL space, the area of osteonecrosis was larger in the mandible than in the maxilla. After the induction of traumatic hyperocclusion in mice, the number of osteoclasts in alveolar bone at the root furcation was reportedly increased in a time-dependent manner, peaking at 7 days and then decreasing [24,30,33]. Although osteoclast activity is suppressed in humans and mice during N-BP treatment, the number of osteoclasts in ONJ areas is similar to or greater than the number in healthy jaw tissue [8,14,34].…”

“…Hokugo et al considered that the ONJ-like bone exposure in mice was often associated with food impaction and showed that a gel diet resulted in wound healing with no bone exposure in ZOAtreated mice [31]. Recently, Kozutsumi et al focused on a report that 50% of BRONJ stage 0 (i.e., without bone exposure/necrosis) progressed to a higher stage [32], and created a mouse model of BRONJ stage 0-like lesions to investigate the effect of high-dose BPs on extraction socket healing [33]. In this mouse model, a ZOA dose-dependent increased osteonecrosis in alveolar bone, but overall wound healing was unchanged regardless of ZOA administration.…”

A new direction in managing avulsed teeth: stem cell-based de novo PDL regeneration

“…On the other hand, traumatic occlusion interferes with the cell viability, fiber alignment, orientation and healing of the PDL. Studies have shown that traumatic occlusion increased PDL width and bone resorption, and reduced bone area by delaying repair [ 55 , 56 ]. Mechanical loading of PDL is essential to preserve the PDL space, improve the regeneration and prevent ankylosis and calcification of the fibers [ 57 , 58 ].…”

Weakening of M1 macrophage and bone resorption in periodontitis cystathionine γ‐lyase‐deficient mice

“…Our previous studies found that knockout of Cth gene slowed down the orthodontic tooth movement (OTM; Mo & Hua, 2018) and ameliorated the orthodontic root resorption in mice (Lu et al, 2019). Meanwhile, CTH aggravates periodontal destruction in mouse with traumatic occlusion (Chen et al, 2020). These results indicate the role of CTH in regulating the resorption of periodontal hard tissues.…”