Tissue response during Piezocision-assisted tooth movement: a histological study in rats.

OBJECTIVES: Piezocision is a novel, minimally invasive technique combining micro-incisions and decortications made by a piezotome in order to enhance the rate of orthodontic tooth movement. The combined technique allows simultaneous hard and/or soft tissue grafting via selective tunnelling to correct gingival recessions or bone deficiencies. The present study was designed to evaluate the effects of Piezocision on bone with or without tooth movement on a rat model. MATERIALS AND METHODS: Ninety-four Sprague-Dawley rats were divided into four groups: no treatment (n = 3), TM (tooth movement alone; n = 21), PS (Piezocision alone; n = 35), and PS + TM (Piezocision and tooth movement; n = 35). In each group, seven time points were studied: 1, 3, 7, 14, 28, 42, and 56 days. After sacrifice, the maxillae were removed, defleshed, stained with haematoxylin and eosin for morphometric analyses and tartrate-resistant acid phosphatase for osteoclastic activity. RESULTS: Three days after the surgery, the bone content decreased significantly in the PS and PS + TM groups compared to baseline (P < 0.01) and the TM group (P < 0.05). This trend continued until Day 28 and was particularly evident in the PS + TM group. At Day 56, alveolar bone returned to its baseline levels in all groups. Osteoclastic activity followed similar change pattern found in the amount of bone, suggesting a strong role for the coupling of the resorptive and formative turnover of the bone. Osteoclastic activity increased as soon as Day 1 in the PS (29.0±3.0, P < 0.05) and PS + TM groups (39.0±6.0, P < 0.01) compared to baseline (22.0±4.0). The highest level of osteoclastic activity in TM group was observed at 3 days (64.3±8.0, P < 0.01) with a steady decrease thereafter. The Piezocision-induced osteoclastic activity showed a steady increase up to 7 days in both PS (39.0±7.0, P < 0.01) and PS + TM (51.8±7.0, P < 0.01) groups and decreased thereafter until Day 56. CONCLUSIONS: Within the limitations of our study (number of animals, duration in time, and limited data on the anabolic activity), our preliminary results suggest that Piezocision-facilitated orthodontic tooth movement increases the rate of movement of the teeth undergoing orthodontic treatment through the coupled remodelling of the alveolar bone. This process is initiated by the osteoclastic activity following surgery and extended via the synergistic relationship between Piezocision and tooth movement.

1-Tetradecanol complex: therapeutic actions in experimental periodontitis.

BACKGROUND: The present study was planned to investigate the therapeutic actions of 1-tetradecanol complex (1-TDC), a novel monounsaturated fatty acid mixture, in established periodontitis in rabbits. METHODS: Periodontitis was initiated in 18 New Zealand White rabbits using ligatures around mandibular second premolars, followed by topical Porphyromonas gingivalis application (10(9) colony forming units). After 6 weeks of disease induction (phase 1), three animals were sacrificed to assess the established periodontitis level. P. gingivalis application was discontinued, and the remaining 15 animals continued with topical treatment of 1-TDC (100 mg/ml; n = 5) or placebo (n = 5) or no treatment (n = 5) for an additional 6 weeks (phase 2). Mandibular block sections obtained after euthanasia were decalcified and embedded in paraffin. In addition to the macroscopic analyses, hematoxylin and eosin-stained sections were used to study cellular inflammatory infiltrate and quantitative histomorphometry. Tartrate-resistant acid phosphatase and osteocalcin were used to identify osteoclastic and osteoblastic activity, respectively. RESULTS: P. gingivalis application resulted in periodontal disease with gingival inflammation and bone loss (30% compared to baseline) at 6 weeks. Treatment with 1-TDC stopped the progression of the disease and resulted in a significant reduction in the macroscopic periodontal inflammation, attachment, and bone loss (10.1% +/- 1.8%), whereas periodontal disease progressed in the untreated and placebo groups (P <0.05). Histologic assessment and histomorphometric measurements demonstrated that 1-TDC inhibited inflammatory cell infiltration and osteoclastic activity (P <0.05). CONCLUSION: The findings suggest that topical application of cetylated monounsaturated fatty acid complex (1-TDC) is a potential therapeutic approach in controlling the progression of chronic periodontal disease.

Resolvin E1 regulates inflammation at the cellular and tissue level and restores tissue homeostasis in vivo.

Resolvin E1 (RvE1) is a potent proresolving mediator of inflammation derived from omega-3 eicosapentaenoic acid that acts locally to stop leukocyte recruitment and promote resolution. RvE1 displays potent counter-regulatory and tissue-protective actions in vitro and in vivo. Periodontal disease is a local inflammatory disease initiated by bacteria characterized by neutrophil-mediated tissue injury followed by development of a chronic immune lesion. In this study, we report the treatment of established periodontitis using RvE1 as a monotherapy in rabbits compared with structurally related lipids PGE(2) and leukotriene B(4). PGE(2) and leukotriene B(4) each enhanced development of periodontitis and worsened the severity of disease. Promotion of resolution of inflammation as a therapeutic target with RvE1 resulted in complete restoration of the local lesion, and reduction in the systemic inflammatory markers C-reactive protein and IL-1beta. This report is the first to show that resolution of inflammation by a naturally occurring endogenous lipid mediator results in complete regeneration of pathologically lost tissues, including bone.