Quantification of intrusive/retraction force and moment generated during en-masse retraction of maxillary anterior teeth using mini-implants: A conceptual approach

Abstract

Objective: The aim of the present study was to clarify the biomechanics of en-masse retraction of the upper anterior teeth and attempt to quantify the different forces and moments generated using mini-implants and to calculate the amount of applied force optimal for en-masse intrusion and retraction using mini-implants. Methods: The optimum force required for en-masse intrusion and retraction can be calculated by using simple mathematical formulae. Depending on the position of the mini-implant and the relationship of the attachment to the center of resistance of the anterior segment, different clinical outcomes are encountered. Using certain mathematical formulae, accurate measurements of the magnitude of force and moment generated on the teeth can be calculated for each clinical outcome. Results: Optimum force for en-masse intrusion and retraction of maxillary anterior teeth is 212 grams per side. Force applied at an angle of 5o to 16o from the occlusal plane produce intrusive and retraction force components that are within the physiologic limit. Conclusion: Different clinical outcomes are encountered depending on the position of the mini-implant and the length of the attachment. It is possible to calculate the forces and moments generated for any given magnitude of applied force. The orthodontist can apply the basic biomechanical principles mentioned in this study to calculate the forces and moments for different hypothetical clinical scenarios.

Alveolar bone remodeling during maxillary incisor intrusion and retraction

“…For example, Ren's systematic literature review [14] The angle between the line touching the margin of the tooth at the alveolar crest level and the line touching the marginal margin of the alveolar bone suggested to conduct more clinical studies and experiments to gain more insight on optimal applied force and the rate of movement in orthodontics. Felicita [15] found that there are different clinical outcomes depending on the positions of anchors and length of attachment. In addition, Yodthong's study [16] believed that some factors, such as rate of tooth movement, change in inclination, and extent of intrusion may influence the alveolar bone thickness during upper incisor retraction.…”

Prevalence of midline diastema and its correlation with high Frenal attachment

“…An attempt was made in this study to identify the prevalence of midline diastema (Kumar et al, 2011;Felicita, 2017b) and its etiological factors among the population (Vikram et al, 2017;Kamisetty, 2015;Viswanath et al, 2015). Further studies with a larger population is advised (Felicita, 2018;Felicita et al, 2012;Dinesh, 2013).…”

A Comparison of Shear Bond Strength of two Visible Light Cured Orthodontic Adhesives -An In-vitro Study

“…Previously our team has done extensive research that ranged from epidemiological studies to randomised clinical trials that have been published in reputed journals. (Felicita, 2017a(Felicita, , 2017b(Felicita, , 2018Felicita, Thirumurthi and Jain, 2017;korath, Padmanabhan and Parameswaran, 2017;krishnan, Pandian and Rajagopal, 2017;Charles et al, 2018;Pandian, krishnan and kumar, 2018;Reddy et al, 2018;Chinnasamy et al, 2019) .we have also done clinical trials on bond strength (Samantha, 2017). We wanted to compare the shear bond strength of the new adhesive-Brace Paste with that Enlight -an orthodontic adhesive produced by Ormco and hence this study.…”