Use of Laser in Controlling the Growth of Facial Structures, "Laser-Orthopedics"

By Dr. Mhd. Azhar Kharsa

ABSTRACT:

Background and Objectives:

This was an endeavor to use a laser to control the development of facial structures, especially the condyle and the mandible. The aim of the study was to investigate the potential use of a laser for treating patients whose facial structures are predisposed to deviation in growth and development much as chin-cups, face-masks and headgear are used. Laser treatment might, one day, be an additional method for controlling the development of these facial structures.

Study Material and Methods:

Three groups of three hamsters were established: Group A, the normal development group, or control group; Group B, three hamsters treated with a chin-cup of a moderate force of about 450g. per side; and Group C the lased group. In Group C the condyles were exposed to the light energy of a diode laser. A red light at 650 nm with energy of 90m W/cm² was used to perform dosages of 10 - 15 J/cm².  

Results:

The long term study over seven months showed slower lower jaw growth in both Groups B and C, relative to group A. The importance of these findings is the implied possibility of laser use in the future to modify the growth and development of facial structures in humans.

Key Words:

In Vitro, Chin-cup, diode laser, Laser-Orthodontic Therapy.

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INTRODUCTION:

Orthodontics is one of the important domains with interests in human growth and development. With the advent of light energy lasers (that are not deleterious) it may prove that research could lead to the use of lasers in the practice of Orthodontics. "Light energy" lasers might be applied to manipulation of human facial growth leading to new methods to cope with problems of either overgrowth or undergrowth.

 MATERIALS AND METHODS

Nine hamsters of the same age were used in this study. They were divided into three groups for comparison. The first, Group A was a surveillance or control group. Group A was allowed to develop naturally and was not treated by chin-cup or laser. Group B consisted of three hamsters exposed to chin-cup therapy with an average force of approximately 450 g. per side.
This force has been demonstrated to be efficient in hindering or slowing the normal growth of the lower jaw11. Group C is the lased group. A red light diode laser at 650 NM and 90m W/cm² in light dosages of 10-15 J/cm² was used on both sides of lower jaws of the three hamsters

In all nine animals, the length of lower jaws were measured in monthly intervals to compare the efficiency of each method on both groups "B" and "C". The measurements established the average growth for each group and permitting comparison between conventional treatment in the Chin Cup Group and the Laser Group. The nine hamsters were in the same stage of growth and therefore comparable.

The Influence of Laser on growth

Unfortunately, the contemporary usage of laser is still often "ablative". On high-energy laser, and high dosage laser treatment, it's normal to see necrotic foci in the exposed tissue22.However, gradual, light dosage laser treatments, and low energy laser are drawing more attention, especially because of their non-ablative impact on vital cells. The influence of laser at 650 NM does not produce necrosis especially in the joint of the lower jaw, or the temporo-mandibular joint (TMJ). The hamster study should provide insight for possible future methods of treatment in the human. In this study we focused on the laser's impact on the cartilaginous growth and its impact on the growth of the condyle. The condyle is comprised of multiple strata that are subsequently proliferated and deposited.11-12

To understand the normal growth in facial structures, it's desirable to study the Condyle Cartilage strata. 

The Condyle Cartilage strata are:

According to chin-cup studies12 the influence of chin-cup happens on the aspect of Prechondroblasts stratum.

However, the influence of low laser energy laser is slightly different as it mainly happens on the so-called zone of growth and zone of maturation, or in other words the prechondroblasts, cartilaginous matrix, hypertrophied chondroblasts, and the calcified cartilaginous matrix.

 Fig 1.The therapy with chin-cup

The fibrous capsule, the prechondroblasts, and skeletoblasts form the so-called Zone of Growth. While the cartilaginous matrix, functional chondroblasts, hypertrophied chondroblasts and the calcified cartilaginous matrix form a so-called Zone of Maturation. Whereas the degenerated chondroblasts form the so called: zone of erosion. The final terminology on that aspect of mandibular condyle is the zone of ossification. It is observed that after the exposure to low energy laser the number of the cells on the strata of zone of growth and zone of maturation lessens. Consequently, the evolution of newly ossified layers would decrease; in other word, the growth would be delayed.  

Fig2. Strata of the mandibular condyle.

RESULTS:

In this experiment, Group B, where the chin-cup had been used for seven months, the greatest retardation in mandibular growth was in the beginning of the experiment, with the highest percentage of delay in jaw growth in the first month (42%). Perhaps this exaggerated percentage was related with the preliminary "onslaught" on the jaw, which pushed the condyle back. Nonetheless, the delay in growth of Group B was decreased to only 8% on the final days of the seventh month of the experiment. (P>0.05)

In contrast to Group B, Group C (the three hamsters treated with low energy laser) had the most delay in growth in the seventh month. The values of delay in growth had been minimal in the first month (5)%, but, gradually , the growth was reduced to approximately 20% relative to Group A on the final days of the seventh month. (P<0.05)

Group C does not exhibit an "onslaught" effect.

The advantage of the laser technique in Group C was apparent in its ability to retard mandibular growth in the hamster. Growth restriction increased continuously from 5% in the first month to about 20% in the final steps of the experiment.

 

TABLE 1. The Average of Changes of values of growth: "in groups B and C" relatively to A per month. SD means here the Standard deviation.

DISCUSSION:

This experiment illustrates a potential substitution to chin-cup therapy in the future. Nonetheless, to perform such experiment in vivo, it's crucial to have more profound knowledge about the side-effects of light energy laser therapy. The importance of such an experiment is in demonstrating the influence of the laser on normal growth. It would also be vital to know the threshold, or upper limit that the organism could tolerate without irreversible damage.

Therefore, for laser to be used in non-ablative therapies, it is paramount that acceptable thresholds be established to allow its therapeutic use without the risk of destructive or necrotic changes. The mechanism of laser energy influence on the tissue strata is still somewhat vague. It will be important to find the possible "receptors" or the tissues of higher "response". If this could be established it would be of great value in establishing a therapeutic laser technique.

Conclusion:

This experiment demonstrates the use of the laser in regulating facial growth and its potential as a substitute for current conventional methods such as a chin-cup