Chapter 15

Treatment Planning for Open Bites

15.1 Introduction

Open bites can be associated with Class I, Class II/1 and Class III anomalies. Most abnormalities that occur separately within the dental arches can also be found along with open bites.

Open bites in which the front teeth are regularly aligned are not esthetically disturbing. The patient and his social circle generally do not know there is anything wrong. There also are seldom complaints of open bites interfering with function. Occasionally, a parent complains that the child eats with his mouth open, or is a messy eater.

The only open bites that are relatively easy to treat are those associated with digit sucking. The others are seldom satisfactorily concluded; open bites often relapse to a great extent.334 361 392 415 Moreover, excessive root resorption is often found after treatment.

The fact that in an open bite the occlusion is different from what is considered normal is no reason for treatment. Open bites, either anterior or posterior, that are not associated with other problems that require correction, are best left alone.

15.2 Anatomic aspects

Open bites caused by digit sucking alone exhibit local deviations in tooth position and morphology of the alveolar process in the maxilla and sometimes in the mandible. The deviations often are asymmetric.

Open bites that for their development do not depend on digit sucking, or on digit sucking alone, exhibit a great variety of forms of craniofacial skeleton.189 They are often associated with a Class II/1 with increased lower face height, a steeply inclined mandibular lower border, and an obtuse gonial angle with antegonial notching. An open bite can also be associated with a Class III. In this instance, the mandible is usually excessively large, while the form of the mandible is a similar to that in a Class II/1 with open bite.

The tongue is positioned between the opposing teeth. In limited open bites the interposition is usually the cause of a lack of vertical contact, unless there is a sucking habit present, or was till recently. In pronounced skeletal deviations the cause is probably primarily of genetic character, derived from the inherited morphology of the face that is largely determined not only in form and size but also in function by the soft tissues.

Amelogenesis imperfecta is often combined with an open bite. It has been suggested that these open bites could be the result of covering the crowns of the teeth with the tongue to prevent pain from the sensitive teeth. Perhaps the posterior open bites sometimes seen to develop during treatment with fixed appliances can also be due to interposition of the tongue to reduce or eliminate pain due to the appliances.

Open bites can also be caused by ankylosis. This is in two forms: that due to dental ankylosis and that due to ankylosis of the TMJ, leading to defective mandibular growth. Condylectomy is indicated for the latter.

15.3 Guidance of the development of the dentition and facial growth

If an open bite is caused by digit sucking, it can close spontaneously after the habit is broken. If there are no other abnormalities (e.g., Class II/1), when the habit is stopped is of little importance from the point of view of further development, but the proviso of no other abnormalities is an important one.

Many open bites due to tongue interposition improve spontaneousl/>