Occlusion is defined as the contact relationship of the maxillary and mandibular teeth when the mouth is fully closed. Occlusion is important because it can influence a person’s facial profile and also the health of the oral cavity. Occlusions that are not ideal may be improved with dental treatments such as orthodontics. In this course, we are going to examine some of the most fundamental concepts that dental professionals need to know when classifying occlusion. Also we discuss basic terminology and use of orthodontic treatment need index used to grade severity of malocclusion.
WHAT IS CLASS I MALOCCLUSION?
A Class I malocclusion is when the upper teeth stick out over the lower teeth, commonly called an overlap, but the bite is otherwise normal. There are many reasons why the upper teeth may overlap, including prolonged thumb-sucking or bottle use in childhood. An overlap may require minor correction with orthodontic appliances. There are three types of Class I malocclusion according to Edward Hartley Angle’s classification:
Type I: The teeth angle toward the tongue.
Type II: Includes narrow arches with the upper teeth sticking out and lower teeth leaning in toward the tongue.
Type III: The upper front teeth angle toward the tongue and crowding is present.
WHAT IS CLASS II MALOCCLUSION?
A Class II malocclusion is when the upper teeth stick out over the lower teeth and affect the overall bite alignment, also known as an overbite. This type of malocclusion is often severe enough that orthodontic intervention is recommended. While it may take a little more time to shape the bite to a more natural state, it is still possible to do so with the right appliances and approach to treatment. There are two divisions of Class II malocclusions that each includes a subdivision where the condition applies to the entire mouth:
WHAT IS CLASS III MALOCCLUSION?
A Class III malocclusion occurs when the lower teeth stick out farther than the upper teeth, resulting in a severe underbite, but it can also include a crossbite, which may have a series of overlapping upper and lower teeth. Angle further classifies this malocclusion into three types:
Type I: The alignment of the teeth is good in general, but there is an abnormal shape to the arch.
Type II: The upper front teeth alignment is fine, but the lower front teeth lean toward the tongue.
Type III: The upper arch is underdeveloped. The lower teeth have good alignment, but the upper front teeth lean toward the tongue.
Classification of the Malocclusion
Before beginning orthodontic treatment, we need to classify malocclusion. Proper identification will guide the course of treatment to bring the teeth and jaw into proper alignment. It can also help to identify possible causes of the malocclusion, especially if those causes include habits that need to be addressed first.
