Shock waves applications in dentistry: narrative review

OBJECTIVES The purpose of this narrative review of the literature is to collect and analyze the scientific evidence regarding the application of shock waves in odontostomatology. MATERIALS AND METHODS A research was performed on electronic databases such as Medline (PubMed), Scopus and Cochrane library from January 1998 to January 2019. The inclusion criteria were: - publication in English; - publication indexed on the main search engines; - in vitro or animal studies with representative samples and reproducible results; - studies on human (case series, prospective or retrospective) with a minimum number equal to or greater than 10, randomized case-control studies (RCT, randomized clinical trials), systematic reviews, metanalysis; - absence of conflicts of interest by the authors. At the end of the electronic research, all the titles were examined and all the selected abstracts were examined, and the selection of full-text articles was determined. Of the 138 articles in full text examined, 120 were excluded from the final analysis because one or more of the inclusion criteria listed above were not respected. In the various articles taken into consideration the effect of the ESWT was investigated in different dental specialties; in particular, this method has been associated with orthodontic therapy in order to speed up the timing and help the remodeling and stability of periodontal tissues in the realigned teeth. RESULTS AND CONCLUSIONS Although the exact biological effects of shock wave therapy for musculoskeletal disorders are not completely understood, current studies seem to indicate that ESWT may have a favorable influence on osteoblasts and their precursors. The shock waves would be able to stimulate the early expression of cytokines linked to osteogenesis favoring the growth and differentiation of bone marrow stromal cells towards osteoprogenitors, thus contributing to bone regeneration processes. Studies on biochemistry have shown that ESWT is able to activate different genes, such as those involved in the synthesis of TGF-beta 1 and BMP-2, linked to osteogenesis; expression patterns of bone-related genes such as osteocalcin (OC) and osteopontin (OPN) induced by shock waves have been seen to be similar to those responsible for periosteal callus formation during healing processes. At the same time, the evidence supporting the use of ESWT in periodontology and oral surgery is still extremely limited; nevertheless, numerous information obtained from the application of shock waves in the context of dental elements subjected to or- thodontic forces, and in particular regarding the expression profiles of some inflammatory cytokines and growth factors, could potentially be transferred to periodontal therapy. CLINICAL SIGNIFICANCE At this time, based on the available results, the use of shock waves as adjuvants for periodontal or orthodontic treatment is still far from being recommended for clinical routine, as neither dosages are clear nor the number of optimal applications. Furthermore, the cellular mechanisms involved and the effects caused are far from being understood. However, hypothetical fields of use and reduced invasiveness could justify the development of future studies.