Innovative Orthodontic Treatment using Piezosurgery

An increasing number of adult patients are seeking orthodontic treatment for functional or aesthetic reasons, but treatment time is often a limitation. Several surgical techniques such as corticotomies have been developed to accelerate orthodontic treatment; however, these procedures are rather invasive. Recently, some authors have proposed minimally invasive techniques such as piezocision, possibly combined with tissue augmentation. Piezocision is a localized alveolar decortication approach that combines buccal micro-incisions and minimally invasive corticotomies (3mm in depth – 5 mm in length) performed with a piezotome. However, the level of clinical evidence backing this approach is scarce, and the underlying biological response regarding piezocision surgery is not fully understood. The aim of this PhD project was to investigate and understand the effects of piezocision on orthodontic treatment based on several clinical trials and multi-level biological analyses in a preclinical setting.

Based on two randomized controlled trials, the present work demonstrates the first clinical evidence of tooth movement facilitation with piezocision. A reduction in treatment time of respectively 40% and 36% was observed in cases of minor to moderate overcrowding. Moreover, patient-reported outcome measures (PROMs) regarding the piezocision procedure were investigated and revealed limited pain scores as well as high levels of acceptance and patient satisfaction. Furthermore, the potential benefit of combining piezocision with alveolar bone augmentation in the anterior mandibular region using biomaterial was explored in a prospective study. Most of the cases demonstrated a significant increase of the alveolar bone envelope and therefore expand the orthodontic scope in cases presenting bone deficiencies or thin buccal bone plate prior to orthodontic treatment.

Beyond the clinical validation, this PhD thesis was also dedicated to understanding the biological phenomenoma associated with the piezocison concept. Within the limit of a preclinical study, the efficacy of piezocision in accelerating orthodontic tooth movement was demonstrated, and the underlying biological responses at the tissue, cellular and molecular levels were highlighted. Increased three-dimensional bone demineralization and osteoclast recruitment were observed in the piezocision group compared to a conventional orthodontic approach. Moreover, an increase in bone remodeling, highlighted at the molecular level by the coupled RANKL-OPG expression, was demonstrated for the first time using piezocision-assisted alveolar decortication. These biological phenomena were shown to be transient and completely reversible.

The clinical and preclinical data collected in this thesis contributed to the validation of piezocision-assisted orthodontic treatment. According to the present results, this treatment approach can be considered to be a new therapeutic tool in adult orthodontics.