Center of Rotation for Retroclined Incisors (Video)
In cases of severely retroclined incisors, the temptation is to reverse the malocclusion and procline the incisors with a simple force (either a push or a pull). However, many times excessive overjet is created. We present here an analysis of how to control the moment to force ratio to minimize the amount of uncontrolled tipping and take advantage of growth. The case was treated with Invisalign. [...]
Dental Photography. Learn how to obtain high quality clinical dental photographs.
In Orthodontic Diagnosis and Treatment Planning - Applied (Module 1B), we have a full section on dental photography. In the meantime, here are some photographic adjustments to help you take the most appropriate intraoral and extraoral photographs. Remember that great photographs reflect positively on your relationship with your patients! [...]
Solution to Exercise 3, as Seen on Facebook.
Hello, Here is the correction for the exercise posted on Facebook, February 2020. The center of rotation is at the intersection of the perpendicular from the points selected as incisal edges and apices. The direction of the force is given by the line joining the initial center of resistance position to the center of resistance final position. The moment to force ratio is given by the coordinate grid from Dr. Fiorelli’s E-book. If D – 14 mm, then the moment to force ratio is 8 which means th [...]
Use of Biomechanics in Orthodontics
Biomechanics is a very important aspect of orthodontics and has unfortunately been kind of abandoned due to a lack of understanding by the orthodontic community of the limitation of the straight wire system. Here is an example of the potential use of a segmented approach to optimize the treatment mechanics. If a straight wire approach is used, the upper incisors will tend to extrude and create a two-step occlusal plane. Using a segmented approach at least at the beginning of treatment will [...]
Solution to Exercise 2, as Seen on Facebook.
Problem: A small exercise with 3 forces applied on the incisor. F1 equals 40 gr. and is vertical. F2 is horizontal and is 80 gr. F3 is a Class II elastic generating 100 gr. 12 mm away from the bracket at an angle alpha of 30 degrees. Can you calculate the resultant force system at the center of resistance? d1= 14mm d2= 8mm d3= 12 mm Have fun! Solution: [...]
October 2019 – Onsite Clinical Session on Adult Orthodontics a Success!
We just completed our fifth onsite clinical session in Hanoi, Vietnam. The clinical session was part of the two-year online-onsite course, Orthodontic Management of Moderate Malocclusions, given in partnership with Hanoi Medical University. The five-day clinical session covered Adult Orthodontics. The participants did exercises on Dentoforms and presented their progress cases. A very serious and impressive group of dentists eager to learn learn more about orthodontics. We will miss them! To [...]
Dr. Retrouvey’s Appointment at the University of Missouri-Kansas City (UMKC).
We are pleased to announce that Dr. Jean-Marc Retrouvey has been appointed Chair of the Department of Orthodontics, University of Missouri-Kansas City (UMKC). After almost 30 years, including 21 years as the Director of the Division of Orthodontics at McGill University in Montreal, Canada, Dr. Retrouvey joined UMKC in October 2019 as Department Chair & Professor of Orthodontics & Dentofacial Orthopedics. He remains at McGill University as Adjunct Professor, Division of Orthodontics. [...]
Solution to Exercise 1, as Seen on Facebook.
Problem: The simple force is applied to the crown of the incisor with an angulation alpha of 30 degrees. The magnitude is 100 gr. The distance from the center of resistance to the X-axis is 9mm. The distance from the point of application of the force to Cr is 14mm. Calculate the equivalent force system at Cr. Solution: Calculation of the force system applied to the crown of the tooth. 1. Force determination in X and Y axis: F= 100 gr Fx = F x cos alpha = 86.60 Fy = F x sin alpha = [...]