BOTH ABO blood type and the bleeding disorder, haemophilia, are solely determined by the action of genes, with no environmental factors involved. Conversely, diseases like cholera and AIDS can affect anyone, regardless of their genetic makeup. Asthma, however, is an example of a disease thought to have a genetic basis, but which requires specific environmental factors, such as climatic conditions and pollen, for induction.
In dentistry, numerous differences in dento-facial characteristics of individuals are encountered, leading one to wonder whether oral health, as a condition, is inherited. Even within a family, some members have a high prevalence of dental caries, while others may be caries-free. Such observations make it difficult to answer the question on the hereditary basis of oral disease.
Regardless of abnormal or normal individual states, how do these differences come about? To deal with this question, it is necessary to turn to genetics. When we examine a specific characteristic or disease in the oral region, we often find that it is the consequence of two principal factors: Genetic and environmental.
Likewise, the sizes and shapes of teeth, as well as different degrees of susceptibility to tooth decay, depend on both genetic and environmental factors. Common diseases such as dental caries and periodontal (gum) disease are infectious in nature because the germ responsible for tooth decay can be transmitted from one person’s mouth to another. However, the problems are often considered to be mainly environmental. However, even in this case, researchers are convinced that the genetic aspects influencing the degree of susceptibility should not be overlooked.
The basic element in genetics is the gene. It is found in the nucleus of every cell. A body containing many genes is a chromosome. Humans have 46 chromosomes in each cell. Chromosomes are made in pairs, which closely resemble each other. There are 23 such pairs, of which one concerns sex. One of the sets of chromosomes comes from either parent. Each of the thousands of genes is responsible for a specific attribute. For example, there are genes for the colour of the eyes, one for the shape of the nose, and one for the colour of the skin, among others. Environmental factors may alter the composition of genes, a process known as mutation. Cancer is a classic example of a condition caused by a gene mutation that an external agent triggers.
After an alteration occurs in a gene, the change is transmitted to descendants, which is why certain conditions, such as heart disease and diabetes, tend to be passed down through families.
Many dental and maxillofacial diseases are primarily transmitted through genetic lines. During my years working at the Department of Oral and Maxillofacial Surgery, I can readily cite two common examples: Facial keloids (abnormal proliferation of scar tissue), seen almost exclusively in Afro-Guyanese, and cleft lip/palate, seen almost exclusively in Indo-Guyanese.
A study published in the Journal of Periodontology in December 2010 concludes that approximately half of the variants in gum disease in the population can be attributed to genetic differences. There are likely several genes that contribute to susceptibility, and these may vary across different racial and ethnic groups. For example, this author observed that in the village of Paramakatoi, while multiple decayed teeth are prevalent among that Amerindian community, the prevalence of gum disease is low.
So, one can say with a fair degree of accuracy that you can blame your oral health status partly on your parents.