Class I Cases
Class I Crowding
Crowding of the teeth is very common in the community and in most cases is simply an inherited difference in the size of the teeth compared to the size of the jaws – the teeth are of a “normal” size and so are the jaws; they just don’t fit together.
The term “Class I” also suggests that the upper and lower jaws are well positioned in relation to each other; neither is too far forward or back, just “average.”
Class I Mild Crowding
In this case, the upper teeth were forward of the lowers, there was some crowding and the bite was out by several millimetres. The teeth were lined up with braces and remained in a good position in relation to the face and lips and the surrounding gums. Retainers were fitted when the braces were removed and, like most patients, they need to stay in place long-term.
Class I moderate crowding
The crowding is too great and room is needed for the teeth to be fully lined up. For this patient, the four second premolars were removed.
Straightening the teeth without extractions would stretch the gums too much (which would predispose to gum recession), would push the lips too far forward and the teeth would be at risk of substantial relapse in the future.
Class I Severe Crowding
The removal of upper and lower teeth was essential in order to line the teeth up within the limits posed by the patient’s face and lips and the gums and bones of the jaws.
Back To Top
Both upper and lower front teeth are forward in their jaws, pushing the lips forward also. Sometimes they are so prominent that the patient has difficulty closing their lips together without considerable strain and the lips are usually well apart when at rest. Treatment for this can be optional if there is no crowding or other problems – it may just be a problem of appearance and patients do not have to have treatment unless they want a change. In order to retract the teeth in the face and jaws, it’s necessary to have teeth extracted and is usually a choice between the first or second premolars (either the 4th or 5th teeth from the centerline). There can be quite a noticeable change in profile, although everyone is different!
Another before and after showing profile changes
Back To Top
Class II Cases
Class II generally relates to those whose lower jaw is back in the face relative to the upper jaw. People sometimes think that their upper front teeth “stick out,” but it is actually the lower jaw that is back.
Class II Division 1 – No extractions
The upper front teeth stuck out by 5-6 millimetres and treatment required braces on all the lower teeth.
Class II Division 1 with the extraction of two upper premolars
The upper front teeth stuck out by 12mm and the bite of the back teeth was “out” by the width of a premolar tooth.
The two upper first premolars (the teeth without brackets) were removed later.
Back To Top
Class II Severe
If the difference between the upper and lower jaws is too great and the lower jaw is back too far for braces alone to correct the apparently protruding upper teeth, correction of the lower jaw or both jaws may have to be considered. This involves jaw surgery or “orthognathic surgery” which surgically repositions the tooth-bearing parts of one or both jaws to position them correctly in relation to each-other (hence fixing the bite) and in relation to the rest of the face, placing them in the most attractive position.
Braces are used first to place the upper and lower teeth in their best position within each jaw, making no compensation for the jaw differences and correcting any crowding or other irregularities. The surgery is then carried out with the braces still in place, to reposition the jaws. For further examples, go to Orthognathic surgery.
Class II Division 2 non-extraction
The upper front teeth overlapped the lowers to an excessive amount, with the lower front teeth biting on the gum behind the uppers. When smiling, the patient showed a lot of gum pre-treatment and this was improved by moving the upper front teeth upwards relative to the upper lip.
Class II Division 2 with the removal of two upper premolars
This is similar to the above problem but the bite of the back teeth was out by 7 or 8mm and two upper premolar teeth were removed for the correction.
Class III Cases
This is effectively the opposite of Class II with the lower jaw forward of the upper jaw. Often the lower front teeth are tipped back and the upper front teeth tipped forward to compensate for the jaw difference.
Treatment without extractions
Some of the upper front teeth were biting behind the lower front teeth and all the upper teeth had to be expanded to match the lowers.
Class III involving extractions as the crowding was too severe
Back To Top
Class III Severe
If the difference between the upper and lower jaws is too great for braces alone to correct the protruding lower teeth, correction of the jaws themselves may have to be considered. This involves jaw surgery or “orthognathic surgery,” which surgically repositions the tooth-bearing parts of one or both jaws to position them correctly in relation to each-other (hence fixing the bite) and in relation to the rest of the face, placing them in the most attractive position.
Braces are used first to place the upper and lower teeth in their best position within each jaw, making no compensation for the jaw differences. The surgery is then carried out with the braces still in place, to reposition the jaws. See examples under “Jaw Surgery or Orthognathic Surgery” page.
When the patient bites on his or her back teeth, the front teeth do not overlap vertically and there is a gap which can make biting into food difficult (the “Ham Sandwich Syndrome” – they bite off the bread but leave the ham behind). The gap can also affect speech. Anterior openbites can develop in young children who have a persistent thumb-sucking habit. This often improves just by assisting the child to cease the habit. For more details, check under the “Thumb-sucking” section. In adolescents, just moving the teeth with braces may correct the problem and be reasonably stable.
A thumb-sucking habit has caused this openbite, which closed down considerably when the habit stopped.
Braces were fitted to fully close the bite and correct the bite.
Other cases have an upper and lower jaw relationship that means the openbite is too great for braces to fix or, if braces did move the teeth enough, the result would put the teeth in an unattractive and/or unstable position. Here jaw surgery may be needed with braces to get a good looking and functional result.
This patient can only bite on the wisdom teeth.
The most commonly impacted tooth, apart from wisdom teeth, is the upper canine which has a long pathway of eruption and sometimes goes off-track. These teeth require surgical exposure and braces to move them into place.
Sometimes teeth simply do not develop and the deciduous tooth that should be displaced may remain in place. Often the deciduous tooth falls out anyway, leaving a gap that is unsightly or causes biting problems. Apart from wisdom teeth, the most commonly absent teeth are the upper lateral incisors. Either both laterals are absent, or if only one is missing, the other lateral incisor may be quite small or even peg-shaped.
Missing Lateral incisors:
When both laterals are missing or one is missing and the remaining lateral is too small to be of use, a basic orthodontic decision that has to be made involves either:
- closing the gaps by bringing the back teeth forward
- opening enough space between the upper canines and the upper central incisors to allow the ultimate placement of implants to replace the missing laterals
In this case, spaces were opened to allow for implants.
In the case below, it was decided to close the gaps by bringing the upper back teeth forward and adjusting the shapes of the upper canines to make them look more like lateral incisors. Of course this meant that implants were not needed in the future.
Back To Top
Missing second premolars:
The next most commonly missing teeth are lower second premolars (the 5th tooth from the mid-line, just in front of the first molar). The deciduous tooth in this position often does not fall out at the usual time and for some people these deciduous teeth may last into middle age. Usually the roots of the deciduous teeth dissolve even though there is no permanent tooth underneath forcing them out.
If the lower teeth are crowded, the absence of the lower second premolars is not a problem as the resulting space can be used for alignment of the rest of the teeth. If upper second premolars are missing and the top teeth stick out (protrusion), the space can be used to correct that protrusion, or in the case below, correct the upper front teeth which were off-centre:
The four second premolars were missing and two deciduous teeth were retained. The top teeth were several millimetres to the left and the bite was incorrect.
Braces were placed, the remaining deciduous teeth were removed and the spaces closed.
If the lower teeth are well aligned and not crowded, the space can be closed by moving the lower back teeth forward. This will mean that implants or bridges are not necessary in the future. It is essential that the lower front teeth do not move back during this procedure and Temporary Anchorage Devices can be used to provide the anchorage needed to pull the back teeth forward.
Back To Top