Orthodontics

Index

Page 1

Introduction

How Orthodontists set their fees

Children's Orthodontics

Congenital skeletal relationships

Class I (Normal)

Class II (Retruded lower jaw or prognathic upper jaw)

Class III (Protruded lower jaw or retruded upper jaw)

Developmental Deformities

Thumb Sucking

Reverse Swallowing

Mouth Breathing

Crossbites

Crowded and missing teeth (too much or too little space)

Page 2

Adult Orthodontics

Combined Orthodontic/Surgical cases

Bands, Brackets, ligatures and elastics--The mechanics of orthodontics

A word about Invisalign®

Orthodontics, page 1 of 2

In the image on the left above, the patient is biting his top and bottom teeth together as much as he can. The space you see between the front top and bottom teeth does not exist between the back teeth. In this case, the patient had a functional problem because his deformity effected his ability to bite and eat. His esthetics (appearance) were not perfect, but not extremely abnormal to the lay public.

The most remarkable thing about the image on the right is not just the straightness of the teeth, but the straightness of the gums and supporting tissues.

And here lies the REAL art of orthodontics. Orthodontists are not just dentists. They are a very specialized form of orthopedic technologist. They manipulate BONE!

(By the way, orthodontists set their fees according to the length of time the patient is projected to be in treatment, and the complexity of that treatment. Every orthodontist you visit will give a different fee estimate for the same treatment objective because their methods differ and this effects their estimates of the time and complexity of the case. A lower fee probably means less time in braces which, on the surface, sounds good. But it may also mean a less stable result and a possible problem with relapse later. For a discussion of how dentists set their fees, click here.)

Before I go further, let me state that I am NOT an orthodontist. (I don't even play one on TV.) I am grateful to Dr. Camille M. Arcidi, for these case studies. I give here a simplified overview of a discipline that most general dentists never become involved with, and those who do usually commit suicide!

Children's orthodontics

Children are a special case because they are growing. This makes them ideal subjects for orthopedic intervention. ("Ortho" means to straighten and "pedo" means child.) Because they are fairly pliable and the bone is relatively soft and always growing and changing, it is easy to guide the bone growth in children through external means. An oak tree, tied in a knot when it is a tiny sapling, will grow in a hundred years into a huge oak tree with a knot tied in its trunk. What was possible when the tree was immature becomes impossible in maturity. (There is some argument about whether the movement of children's teeth is actually faster than that of adults, but there is no argument about the ease of movement due to the growth factor.)

As every mother knows, their children grow faster at some ages than at others. Therefore, orthodontists want to time their treatments for the ages when the child is mature enough to cooperate with treatment, and also when the bone is growing most rapidly. The optimum age for beginning treatment depends upon the specific deformity that the orthodontist needs to correct, but the best age for evaluation of that specific deformity is usually age 7 because that is the age when both factors tend to coincide for the treatment of certain skeletal deformities. A major growth spurt takes place at puberty, and orthodontists like to take advantage of this as well. When deformities are assessed early and treated prior to the time that they have fully developed, we have "intercepted" the problem and this is referred to as interceptive orthodontics.

The congenital skeletal deformities

Class I

Congenital skeletal deformities are conditions occurring at birth and are usually caused by genetic factors. In order to understand what constitutes a deformity, however, it is necessary to understand what constitutes the generally accepted standards of normality. In the diagram above, the central image shows the most normal facial profile. In dentistry, we look at the way the top and bottom teeth come together to determine the exact nature of the profile. This type of profile is called a Class I occlusion (occlusion means the way the top and bottom teeth line up together) and it is characterized by the relative positions of the upper and lower first molars (the molars are the large back teeth, and the first molars are the large back teeth that are furthest forward). The detail of the teeth under the main images show how the first molars line up in each case. From the point of view of appearance, the class I occlusion yields the best profile. Class I occlusion is considered the standard for "normality". Class I deformities are generally the result of crowding, extra space, or from developmental deformities.

Class II

The image to the right shows the class II profile. This is probably the most common skeletal deformity (deviation from "normal"). This occlusion yields a "weak" chin, or retruded chin profile. Extreme cases give an "Andy Gump" appearance. While this represents a deformity, in fact it can be quite attractive on some women. It can have the overall effect of drawing attention to the eyes, and can account for the "all eyes" attractiveness that some women possess. No matter what you think of the appearance of the profile, this occlusion does leave the patient with functional problems involving the position of the front teeth (incisors). The lower incisors frequently do not touch the upper incisors when the back teeth are together, and this allows the lower incisors to erupt up into the gums at the roof of the mouth, and allows the top incisors to erupt into an unattractively "long" and "gummy" appearance, well beyond the edge of the top lip.

Class II before (age 6)

Age 12 after treatment

ClassIII

Class III deformities yield a "prognathic", or "strong chin" appearance. This could be caused by over development of the lower jaw, or by underdevelopment of the upper jaw . This profile is not usually considered attractive on women, however it can be an asset to men, depending on the image they wish to project. It is associated with the "tough guy" or "bulldog" image projected by the 1940's movies, and gives a singularly masculine appearance that we associate with football players today. As with class II occlusions, this profile is associated with functional and esthetic problems. Since the lower incisors are located in front of the upper incisors, they too can erupt to unattractive lengths. This profile can be associated with a "smooth cheekbone" appearance and a tendency not to show the upper front teeth when talking or even when smiling. Biting can be a real problem for these people in extreme cases, because while class I and II profiles can stick their lower jaws out further to bite off a piece of food, it is impossible for the class III profile to draw his lower jaw any further back to make the front teeth meet.

What is all that "equipment" that the patient wears during treatment?

Orthodontists use lots of complicated wires, jack screws, elsatics and "retainer-like" appliances to accomplish their orthodontic/orthopedic goals. If you have specific questions regarding the purposes of things like headgear, bionators, palatal expansion devices and various other stuff that looks like it was invented by someone in Dracula's dungeons, the best thing to do is to corner your orthodontist and ask why you or your child needs it. He or she knows your child's needs specifically and can speak directly to your concerns.

The developmental deformities

Developmental deformities treated by orthodontists are caused by environmental factors such as thumb sucking and lip habits, as well as by other physical errors such as an inability to breath through the nose due to sinus and allergy problems, or the failure of some of the teeth to develop. These deformities are often associated with narrow upper arches, and/or an open anterior bite such as that seen in the image of the thumb sucking habit below. This category also includes crowded, crooked teeth since in this case there is a discrepancy between the size of the teeth and the space available in the dental arches to accommodate them. Of course, all these problems often occur in combination and there is frequently no neat division between them in any given case. Therefore, every case is unique and must be handled with completely different treatment plans.

Thumb sucking

Thumb sucking is a habit that will generally subside on its own. By the time the child is in grade school, he or she wants to stop because it has already become a social liability. If stopped by age 6 or 7, even the open bite pictured above will revert back to normal. Upon occasion, a child will want to stop, but be unable to break the habit. Under these circumstances, it can be helpful to insert a fixed (not removable) habit breaking device as a "reminder" not to put the thumb into the mouth. These work well provided that the child wants to stop the habit. If the habit persists past the age of 12, the skeletal deformity you see above can persist for the rest of that person's life.

Reverse Swallowing

The "before" picture at the top of this page is of an adult who likely developed his open bite as a result of a persistent tongue thrust habit which is similar to the habit of "reverse swallowing" in which the tongue is pushed out between the teeth every time the child swallows. Note also that the habit of persistently biting or sucking on the lower lip can produce similar deformities. These habits are all handled with their own habit breaking appliance designs.

Mouth breathing

The normal development of the oral structures depends upon the ability of the child to breath through the nose without obstruction, especially at night. This does NOT mean that if your child gets an occasional cold and can't breath through his nose he will grow up with oral abnormalities. However, chronic obstruction of the nasal airway due to deviated septum, persistent allergies or other anatomic abnormality will tend to cause the roof of the mouth (the hard palate) to rise and the back upper right and left teeth to collapse toward each other. We call this condition a constricted arch. The teeth are arranged in arches.

The picture on the right is a model of a constricted arch. The model on the left has a more normal arch form. A patient with the teeth on the right will have a smile that shows mostly the two prominent front teeth, with the others in shadow. The one on the left shows a normally shaped archform resulting in a broader smile

Crossbites

In most instances, the constriction of the upper arch is accompanied by some degree of constriction in the lower arch caused by the tilting of the lower teeth toward the tongue. However, the degree of lower constriction is not enough to keep the upper and lower back teeth in the correct relationship with each other. This produces a condition known as crossbite in which the top back teeth hit on the inside cusps of the lower back teeth instead of on the outside cusps which is the normal relationship.

Figure A shows a schematic view from the front of the mouth with teeth in a normal biting situation. Figure B shows the teeth in a crossbite situation. Posterior crossbites like this can have pronounced effect on the overall facial appearance, especially when they are unilateral (on one side of the mouth only). When a unilateral posterior crossbite is present in a young person, it can cause asymmetric development of the facial muscles and the jaw joint which means that one side of the face may grow larger than the other.

Crowded and missing teeth

Nature tries to fit the teeth into the space available. The teeth always end up in their most stable position within the dental arch, whether they are crowded, or have extra space between them. Stability is the name of the game. There is always a balance between the various forces that affect any given tooth, as well as the amount and position of bone available, that helps determine where that tooth is most stable. If a dentist tries simply to move the teeth into better looking positions, Nature may move them right back where they started. This is why an orthodontist must play certain tricks to make sure the local forces affecting each tooth will cancel each other out after treatment so that the tooth will stay put once it is moved.

This is why the orthodontist must usually treat both upper and lower teeth, even if only the appearance of the top teeth are of concern to the patient. Unless the position of the lower teeth coincide with the position of the uppers, the biting forces produced by the ill fitting lowers will create instabilities that will move the uppers back into crooked positions over time. This is also the reason that the orthodontist will order the extraction of some teeth. The extra room created by the removal of these teeth changes the stability equation in favor of the preferred new tooth positions.

Orthodontics page 2 (Surgical cases, Adult ortho and the Mechanics of orthodontics >>>