Types of jaw deformities in Singapore

Surgery for this condition is the most highly sought amongst patients with maxillofacial deformities. This is the condition whereby the lower jaw is more protruding than the upper jaw, giving the face a concave profile. This is also a very common deformity amongst ethnic Chinese. The face also appears long and that has the effect of making a person look older and less friendly. This can be corrected by setting the upper jaw forward and the lower jaw backwards. 

 

2. "Overbite"

The opposite of the "underbite" is the "overbite". This is when the lower jaw is way disproportionately shorter than the upper jaw, The chin is retruded and lacking in prominence. This is no distinct jaw line and the lower jaw blends into the neck. The technical term for this is Class II skeletal relation or retrognathic mandible. This condition is more common amongst the Caucasian race though it is also present amongst Asians. However, the desire of Class II patients' to have surgery is not as great as the Class III. Aesthetically, this seems to be much more accepted by patients in Singapore. However, due to the retruded position of the lower jaw, some of these patients may have obstructive sleep apnea which is best treated with corrective jaw surgery. The objective of surgery for this condition is to set the lower jaw forward and maybe the upper jaw backwards.

 

 

3. Open bite

As the name the teeth in the front do not meet, leaving an open bite in front. This is usually due to excessive vertical growth of the back part of the upper jaw and deficient vertical growth of the front part. With such an uneven growth, the molars at the back will gag the bite open, preventing the front teeth from meeting. It also prevents the lips from closing, giving the patient an open mouth appearance all the time. Surgery is usually done by pushing detaching the upper jaw and differentially repositioning the back part of the upper jaw higher compared with the front. This will allow the lower front teeth to close into the upper teeth. Along with that, the lips become competent and close. Open bites are not as common as Class II and III deformities. The mild cases may not be very noticeable and patients don't seem to be bothered. The severe cases will usually be treated as having the mouth opened all the time is a signficant functional and aesthetic challenge.

 

4. Bimax protrusion

Bimax protrusion is arguably the most common "deformity" amongst ethnic Chinese and Malays. Most Chinese and Malays have bimax protrusion to a certain extent. It is when the degree of protrusion exceeds the patient's own tolerance level that they seek treatment for it. In this condition, the tooth bearing part of the jaw, called the alveolar bone, has grown excessively beyond what some people consider as the aesthetic limit. The facial profile is convex with the lips being pushed forward. The chin is often retruded in the group of patients as well. As it is a fairly "normal" facial profile, different patients have different threshold for the degree of protrusion before they seek surgery. In Singapore, while this facial profile is rather prevalent, the acceptance by the people who have it is pretty high. When I training in Hong Kong back in the early 90's, we do surgery to correct this almost on a daily basis. This is done by extracting four premolars and segmentalizing the jaw into three or four pieces and then fitting them back together in a more retruded position and at the same time moving the chin forward. In Singapore, many patients opt for a non surgical approach using only orthodontics alone. Orthodontics can minimize the amount of protrusion but cannot achieve the kind of change in facial profile that surgery can.

 

5. Gummy smile

This is also another common condition and it often occurs along with bimax protrusion. The underlying problem can be due to excessive gum tissue covering the teeth, in which case a simple trimming of the gum will soft the problem Here we are talking about gummy smiles due to excessive vertical growth the upper jaw. To correct his kind of gummy smile, the surgery is similar that described for bimax protrusion. More details on gummy smile can be found here.

 

6. Asymmetry

The secondary growth centre of the lower jaw is in the condyles. This is the part of the lower jaw that together with the fossa, forms the temporomandibular joints. Some times, the growth centre of the one of the condyles is more active than the other side. This results in more growth of the jaw bone along that side, pushing the chin point the opposing side of the face. Asymmetries should be corrected when the growth is complete and for boys, that can mean only when they are in their twenties. This is because the hyperactive grwoth of one of the condyle may not burn out till much later. As a crooked face gives the person an unpleasant look, treatment for this is fairly well sought after in Singapore. 

The above list is by no means exhaustive but will serve as a guide as to what kind of facial deformities can be done to achieve better aesthetics. However, this does not replace a professional assessment by a maxillofacial surgeon.. The gross deformities are easy to recognize but the more subtle ones are more difficult to diagnose. In real life, there are combinations of different deformities and careful assessment is needed to determine what surgery is needed. If you think that you have a jaw deformity that you do not like, consult an oral maxillofacial surgeon.