The influence of acetylsalicylic acid on bone regeneration: systematic review and meta-analysis.

Acetylsalicylic acid (ASA) is commonly used as a non-steroidal anti-inflammatory drug that interferes with multiple biological pathways. ASA acts by stimulating osteogenesis and inhibiting osteoclastogenesis. Thus, the objective of this study was to perform a systematic review and meta-analysis to evaluate the effectiveness of the use of ASA in the bone regeneration in animal models. This review was structured based on the PRISMA Statement and registered on PROSPERO database according to protocol number #CDR42018111403. The quality of evidence was assessed by using the Grades of Recommendation, Assessment, Development, and Evaluation (GRADE). With the development of search strategies, we identified studies on the use of ASA from the following databases: 1- Medline (via PubMed); 2 - Web of Science; 3 - Scopus; and 4 - EMBASE. A total of 296 articles were identified and after screening the title, abstract, and full text, only 18 studies were selected for qualitative analysis and 12 were selected for performance of the quantitative analysis (meta-analysis). A meta-analysis of the amount of bone tissue formed showed a significant advantage when ASA was locally used, revealing a mean difference (MD) of 22.75% (95% CI: 15.39-30.12) p < 0.00001. Within the limitations of the available data, the results were promising and showed that ASA can be effective in bone formation in animal models.

Maxilla reconstruction with autogenous bone block grafts: computed tomography evaluation and implant survival in a 5-year retrospective study.

This retrospective study was performed to evaluate the bone thickness of the anterior maxillary region after reconstruction with autogenous bone blocks at 6 months and 5 years after surgery using computed tomography (CT) and to determine the implant survival rate. Eleven patients with a horizontal bone deficiency were treated with reconstructive procedures and implant placement. CT measurements were obtained before surgery (T0) and at 6 months (T1) and 5 years (T2) after surgery. The values were analysed statistically (analysis of variance and Tukey's test; P<0.05). Implant survival was evaluated at follow-up. The mean width of the lower region of the ridge (±standard deviation, in millimetres) was 3.8±1.6 at T0, 7.0±1.6 at T1, and 6.5±1.0 at T2; the mean width of the upper region of the ridge was 5.7±2.3 at T0, 8.3±2.2 at T1, and 7.3±1.6 at T2. The mean total thickness of the ridge was 4.7mm at T0, 7.6mm at T1, and 6.9mm at T2; the average increase in horizontal thickness was 2.9mm at T1 and 2.2mm at T2. A statistically significant difference was observed in the mean width of the lower portion at T1 and T2 compared to the width at T0. The implant survival rate was 94.1%. This technique demonstrated high predictability for implant survival, with a reduction in the graft bone during the follow-up period.

Mesenchymal dental pulp cells attenuate dentin resorption in homeostasis.

Dentin in permanent teeth rarely undergoes resorption in development, homeostasis, or aging, in contrast to bone that undergoes periodic resorption/remodeling. The authors hypothesized that cells in the mesenchymal compartment of dental pulp attenuate osteoclastogenesis. Mononucleated and adherent cells from donor-matched rat dental pulp (dental pulp cells [DPCs]) and alveolar bone (alveolar bone cells [ABCs]) were isolated and separately cocultured with primary rat splenocytes. Primary splenocytes readily aggregated and formed osteoclast-like cells in chemically defined osteoclastogenesis medium with 20 ng/mL of macrophage colony-stimulating factor (M-CSF) and 50 ng/mL of receptor activator of nuclear factor κB ligand (RANKL). Strikingly, DPCs attenuated osteoclastogenesis when cocultured with primary splenocytes, whereas ABCs slightly but significantly promoted osteoclastogenesis. DPCs yielded ~20-fold lower RANKL expression but >2-fold higher osteoprotegerin (OPG) expression than donor-matched ABCs, yielding a RANKL/OPG ratio of 41:1 (ABCs:DPCs). Vitamin D3 significantly promoted RANKL expression in ABCs and OPG in DPCs. In vivo, rat maxillary incisors were atraumatically extracted (without any tooth fractures), followed by retrograde pulpectomy to remove DPCs and immediate replantation into the extraction sockets to allow repopulation of the surgically treated root canal with periodontal and alveolar bone-derived cells. After 8 wk, multiple dentin/root resorption lacunae were present in root dentin with robust RANKL and OPG expression. There were areas of dentin resoprtion alternating with areas of osteodentin formation in root dentin surface in the observed 8 wk. These findings suggest that DPCs of the mesenchymal compartment have an innate ability to attenuate osteoclastogenesis and that this innate ability may be responsible for the absence of dentin resorption in homeostasis. Mesenchymal attenuation of dentin resorption may have implications in internal resorption in the root canal, pulp/dentin regeneration, and root resorption in orthodontic tooth movement.