Dental Education Lecture: Tooth Alignment & Oral Health
We have used photos of two clinical cases to explain Why We Need Braces. Today let us use drawings to show how tooth alignment influences our oral health.
Fig.1 illustrates a tooth with crown and root. The crown has two major components: cusp and fossa, analogous to mountain and valley. When upper and lower teeth bite together, the cusp of an upper teeth bites into a fossa of the opposing tooth and vice versa (Fig.2). This relationship is similar to pestle and mortar, facilitating our chewing. When our teeth do not have good alignment like Fig.3, we can grab our food as quickly as a dog does, but cannot chew very well. Our digestive system may suffer. For example, cusps are under undue stress. One day one of them is chipped (arrow in Fig.4). Or the teeth become worn too soon, i.e., cusps flattened (arrow, Fig.5). Sometimes even the tooth may be split into two pieces due to undue pressure and wear.
Fig.6 is the biting surface view of our lower teeth with normal alignment. By comparison, Fig.7 demonstrates ill-alignment of two teeth (labeled as 1,2) in the front region of our mouth. It is easy to clean well-aligned teeth (Fig.8), whereas it is difficult to clean crowded areas (dead corner) as shown in Fig.9. Orthodontic treatment through braces can fix alignment problems, making easy to keep our teeth and gums healthy. We have less chance to have cavities and gum diseases. We can also avoid premature tooth wear and unexpected tooth chip and fracture as mentioned above.
Xin Wei, DDS, PhD, MS 1st edition 01/17/2009, last revision 03/20/2010