ABSTRACT
INTRODUCTION: The objective of this study was to evaluate, through a systematic review of the literature and an in vitro study, the alteration of the mechanical and chemical properties of aligners after aging in artificial saliva and in the oral cavity. MATERIALS AND METHODS: A systematic literature review was carried out, through an electronic consultation of three databases: PubMed, EBSCO and Sciencedirect, between September 2018 and January 2020. The search was guided by the use of several specific keywords. In our in vitro study, the mechanical properties of our sample of aligners were evaluated using the 3-point bending test after a water immersion. RESULTS AND DISCUSSION: Of the 189 articles found, only six articles met our inclusion criteria. In the light of the studies selected in this systematic review and of our in vitro study, it can be concluded that the orthodontic aligners undergo an alteration in their mechanical properties after stay in the mouth. However, the real impact of these modifications on their clinical performance remains to be demonstrated and it is difficult to make a final judgment on their chemical stability. Other controlled clinical studies, with protocols better suited to the clinical criteria studied, are necessary to objectively assess the aging phenomenon of orthodontic aligners.
Subject(s)
Aging , HumansABSTRACT
Coronoradicular dilaceration is a particular abnormality of the permanent incisors, usually maxillary, and usually occurs around the age of 4 to 5 when the crown is formed and the root is still growing. It follows acute mechanical trauma affecting the temporary incisor. This anomaly of shape is characterized by an angulation between the crown and the root of the permanent tooth. The prognosis may be serious because the affected tooth may not erupt normally. It also compromises possible orthodontic treatment later. Our clinical case is that of a young patient (ES) aged 8 years and 4 months, in good general health condition, consulted for the absence 21 on the arch while the contralateral tooth was present. Interrogation revealed that the patient suffered trauma with severe luxation of the 61 at the age of 3 years. Radiographic examination showed the presence of the germ of 21 with an atypical sickle-shaped position and an image of a hand of a traffic policeman with a crown in a horizontal position. Three-dimensional imaging using a CT scan shows the shape of the 21 with a root angulation. The therapeutic attitude allowed the correction of its axis by an orthodontico-surgical treatment.