What changes in the biology of bone movement induced with mini-implants/miniplates is the synchronicity

ABSTRACT Introduction: Induced tooth-bone movement occurs by a synchronicity of dental and bone phenomena, thanks to the osteocytic network, which is a three-dimensional network that controls the bone shape or design. Objective: To describe the tooth-bone movement induced by enhanced anchorage, divided into three distinct moments: zero, start and stop. Question: From this description, the main question arises: with the use of mini-implants/miniplates, what changes in the biology of induced tooth-bone movement? The answer is: nothing changes, either biologically or microscopically. Conclusion: This technique optimizes the treatment time, and the range of therapeutic possibilities is broadened, thanks to the synchronicity of phenomena - which remain the same, in all teeth and bones, yet in a synchronized manner. Bone anchorage represents synchronicity in induced tooth-bone movement.


INTRODUCTION
For decades, induced tooth-bone movement was called induced "tooth" movement; however, considering the current knowledge, it is known that it involves synchronized bone and tooth phenomena. Teeth change their position thanks to changes in bone volume and shape.
Many doubts arise when trying to understand the induced tooth-bone movement in different clinical situations, such as in conventional orthodontic treatment with brackets and wires, and in orthodontic treatment with the use of mini-implants and miniplates to obtain enhanced anchorage.
In both situations, the molecular, cellular and tissue phenomena are the same, including intensity and duration. The difference is that, in enhanced anchorage, there is synchronicity in the most varied points of the teeth and bones, i.e., the phenomena occur at the same time in several sites.

APPLIED FORCES: DISTRIBUTION X INTENSITY
One concern of clinicians is that enhanced anchorage appliances use heavier forces than conventional treatments. For tissues and cells, what matters are the forces that reach them directly. [1][2][3][4] Consolaro A, Silva E, Cardoso MA -What changes in the biology of bone movement induced with mini-implants/miniplates is the synchronicity 5 At the moment of activation of enhanced anchorage appliances, the applied load is greater than the conventional load, yet it is distributed along the teeth and bones, being reduced when reaching the tissues.
What matters the most is not the intensity, but the distribution of forces acting on the tissues. Unfortunately, there is no way to measure the intensity of forces directly on the cells and tissues -we have not yet reached this technological advance -, but rather those applied at the moment of activation of appliances, wires and elastics.
In induced tooth-bone movement, the frequency and intensity of iatrogenic tooth resorption are more associated with the concentration and/or distribution of forces than with their intensity. 5,6,7 Intense well-distributed forces are better accepted and cause less tissue damage, while lower forces concentrated in a smaller area tend to cause more damage.
In the induced tooth-bone movement with enhanced anchorage, the applied force is distributed more uniformly across the bone and tooth structures, justifying why tooth resorptions are less frequent and intense in orthodontic treatments with miniplates than those observed in conventional treatments. 8-12 Consolaro A, Silva E, Cardoso MA -What changes in the biology of bone movement induced with mini-implants/miniplates is the synchronicity 6

THE THREE MOMENTS OF INDUCED TOOTH-BONE MOVEMENT USING ENHANCED ANCHORAGE
To understand the synchronicity of cellular and tissue phenomena in induced tooth-bone movement, we established three moments for their characterization, namely: The periosteum is fundamental in induced tooth-bone movement. In the cervical portions of the alveolus, at the alveolar crests, the alveolar cortical bone is continuous with the outer cortical bone, which is covered externally by fibrocellular tissue called periosteum. Besides being richly vascularized, the periosteum has a very fibrous outer layer, organized into a capsule, to protect the bone externally. Internally, the periosteum adheres to the cortical bone that it produces, by the insertion of many fibers, among which there are many osteoblasts and osteoclasts.
The surface of all bones is covered by periosteum, which protects them and assigns them a high reactive and productive capacity. The periosteum is "absent" in only two situations: in the direct insertions of tendons and in the alveolar bone surface of teeth. In the alveolar bone that lines the tooth alveolus, the periodontal ligament represents a highly specialized periosteum and plays its role in dentoalveolar physiology.
All bone structures have an osteocytic network. 13 In all aforementioned bone components, inside their structures there are many embedded cells, shaped as spiders, with 20 to 50 cytoplasmic processes, which contact another 20 to 50 cells.
These cells are the osteocytes, and they form a three-dimensional intercommunication network to control and change the bone shape or design, based on functional demands received throughout life (Fig 1).  Likewise, cementoblasts and cementocytes do not have membrane receptors for bone remodeling mediators released by osteocytes and other bone cells, and cannot obtain information or "orders" from the osteocytic network to promote tooth remodeling, as occurs in bones.

Consolaro A, Silva E, Cardoso MA -What changes in the biology of bone movement induced with mini-implants/miniplates is the synchronicity
When there is alveolodental ankylosis, the replacement resorption following it represents exactly the bone remodeling occurring in dental tissues, since these protective mechanisms or characteristics have been disrupted.

START MOMENT: THE DYNAMICS OF MOVEMENT HAPPENING START MOMENT: THE DYNAMICS OF MOVEMENT HAPPENING
The activation of forces promotes a deformation of cells and bone components, which will be detected by the three-dimensional osteocytic network, which is modified and deformed by the induced change in position (Figs 1 and 2). By the deformation caused, this osteocytic network knows where to deposit or resorb bone, to adapt to this new functional demand, natural or induced. For example, the alveolar cortical bone waits for the tooth to arrive with new layers deposited by the periosteum that was stimulated by the osteocytic network, even at distance, by the cell-to-cell contact of surrounding osteocytes and/or by the mediators released. At the same time, the trabeculae redesign their distribution to better dissipate forces and meet the captured functional demand (Fig 1).
From time to time, after 40 to 60 days of activation in bone anchorage, spatial changes in bone position, volume and shape, as well as in the tooth-bone and tooth-tooth relationships, are observed (Fig 2).

STOP MOMENT: IT'S TIME FOR NEW TENSEGRITY
When the application of forces in enhanced anchorage is interrupted, the accelerated bone remodeling returns to its normal rate. With a new design or shape, the bones and dental arch will now be in a new tensegrity, which is expected to have been Tensegrity is the balance between all forces generated in a system or objects, whose resultant is equal to zero, soon after functions and movements are performed. If a new tensegrity in the jaws is not obtained after orthodontic and/or orthopedic treatment, either conventional or with enhanced anchorage, there is a tendency for the system to provide movements and readaptations to return to the previous tensegrity, and thus relapses and/or instabilities occur. [1][2][3][4] In orthodontic planning, it is essential to program a new tensegrity, considering all factors that generate movements and tensions, such as the TMJs, occlusion, adjacent teeth, gingiva, soft tissues; and functions such as chewing, swallowing and speaking. With enhanced anchorage, this can be achieved in a shorter treatment time, yet the biology of phenomena involved in induced tooth-bone movement is the same. The important thing is synchronicity and the goals to be achieved.
When enhanced anchorage is applied, the force is distributed over a larger area, and the distribution of this force and its dissipation tends to be more uniform and homogeneous. For the tissues, the forces are similar or even more uniform than those obtained by conventional appliances.

SYNCHRONICITY IS NOT SIMULTANEITY
During enhanced anchorage, the osteocytic network allows the force-stimulated bone a synchronicity that cannot be called simply simultaneity 13 (Fig 1).
Simultaneity suggests independent phenomena occurring at the same time, without necessarily indicating a relationship of goals and meanings between them, or a common cause. Simultaneity is almost the expression of what happens "by chance".
Conversely, synchronicity indicates the occurrence of phenomena at the same time but maintaining an interrelation of meanings and objectives with each other and with the same cause.
In the case of enhanced anchorage with miniplates/mini-implants, the cause is the forces planned and generated with the same objectives.
In argumentation about orthodontic treatments with or without mini-implants/miniplates, questions arise such as:

-With the use of mini-implants and miniplates, what changes in the biology of induced tooth-bone movement?
The answer is: The authors report no commercial, proprietary or financial interest in the products or companies described in this article.