In the human mouth, each tooth plays a unique role, and dentists use specific numbers for precise communication. Tooth number 18 refers to a permanent tooth located in the lower left quadrant. This universal numbering system helps dental professionals identify and track individual teeth for diagnosis, treatment, and record-keeping, avoiding confusion.
Understanding Its Place and Function
Tooth number 18 is the lower left second molar. It sits behind the lower left first molar and in front of the lower left third molar, commonly known as the wisdom tooth. This tooth is a permanent molar, meaning it is not replaced after its initial eruption.
Like all molars, its primary function is mastication, the process of grinding and crushing food into smaller, manageable pieces for easier swallowing and digestion. This tooth typically features four cusps, or raised points, on its chewing surface—two on the buccal side (facing the cheek) and two on the lingual side (facing the tongue). Its robust structure and broad surface are designed to withstand the considerable forces exerted during chewing, making it an efficient tool for breaking down a wide variety of foods.
When This Tooth Appears
The development of permanent teeth, including the second molars, begins within the jaw before they emerge. The lower second molars typically erupt between the ages of 11 and 13 years. These molars are among the last permanent teeth to appear, with only the wisdom teeth (third molars) emerging later. While eruption times can vary, this general timeline provides an expectation for when this tooth will become visible. Their appearance completes the set of permanent teeth, forming a strong foundation for a child’s expanding dietary needs.
Frequent Issues with This Tooth
Due to its position at the back of the mouth, tooth 18 is susceptible to several dental problems. Cavities are common because its deep grooves and pits easily trap food particles and bacteria, making effective cleaning challenging. Decay on the back surface, especially when adjacent to an impacted third molar, is frequent. This posterior location also makes it harder to reach with a toothbrush and floss, contributing to plaque accumulation.
Impaction of the neighboring wisdom tooth (third molar) frequently causes problems for tooth 18. An impacted wisdom tooth can press against tooth 18, leading to distal cervical caries, root resorption, or periodontal issues. Pericoronitis, an inflammation of the gum tissue around a partially erupted tooth, is another common complication often affecting the area around tooth 18 when a wisdom tooth is attempting to emerge nearby. Crowding in the dental arch can also make it difficult to maintain proper oral hygiene around this tooth, increasing the risk of gum disease.
Keeping This Tooth Healthy
Maintaining the health of tooth 18 requires consistent and thorough oral hygiene practices. Brush twice daily for at least two minutes with a soft-bristled toothbrush and fluoride toothpaste, paying close attention to all surfaces, including the chewing surface and the back portion of the tooth. Holding the brush at a 45-degree angle to the gums helps clean effectively along the gumline.
Daily flossing is also important to remove plaque and food debris from between tooth 18 and its neighbors, areas that brushing alone cannot reach. Regular dental check-ups and professional cleanings, typically every six months, allow dentists to monitor the tooth’s health, identify any developing issues early. Limiting sugary and acidic foods can also help prevent tooth decay by reducing the fuel for harmful bacteria.