Gingival invagination area after space closure: A histologic study

Summary Background The maxillary lateral incisor is one of the teeth most likely to suffer agenesis, resulting in spacing between the central incisor and the canine. Objective To compare maxillary lateral incisor agenesis with space closure treatment versus non-treatment based on measurements of the self-perceived oral-health-related quality of life (OHRQoL) and self-esteem of the participants. Subjects and methods A total of 44 people, aged 17–49 years, with missing lateral incisors were randomly assigned to two groups (n = 22 in each)—a treated group in which the space was orthodontically closed (TG) and a control group that remained untreated (CG). Randomization was performed by a researcher who was not involved in the clinical part of the study. The outcomes were assessed using the Oral Health Impact Profile and Rosenberg’s Self-Esteem Scale, which were applied before (phase 1) and after (phase 2) the orthodontic treatment in the TG, and at baseline (phase 1) and 12 months after (phase 2) in the CG. All the data were blindly evaluated, supporting the single-blinded design of the study. Results All participants finished the randomized controlled trial, and the demographic characteristics were similar between the groups. In phase 1, the levels of self-esteem and OHRQoL at baseline were similar (P = 0.079, P = 0.693, respectively). In phase 2, the self-esteem scores of the CG decreased and the OHRQoL increased (P = 0.005, P < 0.001, respectively), while self-esteem increased in the TG and the OHRQoL decreased (P < 0.001). The CG had lower scores than the TG for self-esteem, but the opposite was observed for OHRQoL (P < 0.001). Limitations Information bias may have occurred. Since the questionnaires could not have been applied at the same time in both groups, the time difference between the two assessments may have led to random and systematic error. Conclusions The spacing resulting from missing maxillary lateral incisors had a negative impact on the OHRQoL and self-esteem of the participants, while orthodontically closing those spaces had a positive impact on those aspects. Clinical trial registration This study was not registered. Protocol The protocol was not published before trial commencement.

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Tooth Movement Efficacy of Retraction Spring Made of a New Low Elastic Modulus Material, Gum Metal, Evaluated by the Finite Element Method

Materials ◽

10.3390/ma14112934 ◽

2021 ◽

Vol 14 (11) ◽

pp. 2934

Author(s):

Naohiko Tamaya ◽

Jun Kawamura ◽

Yoshinobu Yanagi

Keyword(s):

Finite Element Method ◽

Finite Element ◽

Tooth Movement ◽

The Finite Element Method ◽

Bodily Movement ◽

Anterior Teeth ◽

Low Elastic Modulus ◽

Space Closure ◽

Gum Metal ◽

Element Method

The aim of this study was to evaluate the tooth movement efficacy of retraction springs made of a new β-titanium alloy, “gum metal”, which has a low Young’s modulus and nonlinear super elasticity. Using double loop springs incorporated into an archwire made of gum metal (GUM) and titanium molybdenum alloy (TMA), the maxillary anterior teeth were moved distally to close an extraction space. The long-term movements were simulated by the finite element method. Its procedure was constructed of two steps, with the first step being the calculation of the initial tooth movement produced by elastic deformation of the periodontal ligament, and in the second step, the alveolar socket was moved by the initial tooth movement. By repeating these steps, the tooth moved by accumulating the initial tooth movement. The number of repeating calculations was equivalent to an elapsed time. In the GUM and TMA springs, the anterior teeth firstly tipped lingually, and then became upright. As a result of these movements, the canine could move bodily. The amount of space closure in GUM spring was 1.5 times that in TMA spring. The initial tipping angle of the canine in the GUM spring was larger than that in the TMA spring. The number of repeating calculations required for the bodily movement in the GUM spring was about two times that in the TMA spring. It was predicted that the speed of space closure in the GUM spring was smaller than that in the TMA spring.

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