Molars are the large, flat teeth located in the back of the jaw, designed for grinding food during chewing. While the first set of molars, known as primary or “baby” molars, are expected to be shed as a normal part of human development, the permanent adult molars are meant to last a lifetime. The distinction between these two sets is the most important factor in understanding molar loss.
The Primary and Permanent Molar Classifications
The primary dentition includes 20 teeth, eight of which are molars—two on each side of the upper and lower jaws. These primary molars help a child chew and speak, and they also act as placeholders, maintaining space for the adult teeth that will follow. The permanent dentition, which replaces the primary set, is comprised of up to 32 teeth. This adult set includes three types of molars on each side: the first, second, and third molars (wisdom teeth). Permanent molars do not replace primary molars directly; instead, they erupt behind them, with the first permanent molars typically appearing around age six. The permanent teeth that replace the primary molars are the premolars, which are absent in the primary dentition.
The Natural Loss of Primary Molars
The process by which primary molars are lost is a natural event known as exfoliation. This shedding occurs because the developing permanent teeth, specifically the premolars, begin to resorb or dissolve the roots of the primary molars above or below them. The primary molars are among the last baby teeth to be naturally lost, typically shedding between the ages of 10 and 12 years. This timing coincides with the readiness of the first and second permanent premolars to take their place. The natural loss of a primary molar is a sign of healthy dental development and ensures the jaw maintains a functional chewing surface as the permanent teeth emerge.
Causes of Losing Permanent Molars
Permanent molars are not designed for natural loss, and their removal signals underlying disease or injury. The leading cause of permanent tooth loss in adults is periodontal disease, commonly known as gum disease. This condition results from a bacterial infection that causes chronic inflammation of the gums and the underlying support structures of the tooth. In its advanced stage, periodontitis destroys the alveolar bone that anchors the molar’s roots. As the bone recedes, the molar loses its stable foundation, leading to progressive loosening and eventual loss or extraction. Poor oral hygiene allows plaque buildup, which triggers this destructive process.
Severe dental decay, or deep cavities, is another primary reason for permanent molar loss. Molars are particularly susceptible to decay due to their complex anatomy, which includes deep grooves and fissures that trap food and bacteria. When decay is left untreated, the bacterial infection can destroy the tooth structure until it becomes irreparable, sometimes extending into the nerve and supporting bone. In such cases, extraction is necessary to prevent the infection from spreading further into the jaw.
Trauma is a third significant cause of losing a permanent molar, occurring from accidents, sports injuries, or chronic habits like teeth grinding (bruxism). A sudden, forceful impact can immediately knock a molar out or cause a severe fracture of the tooth or its root. Root fractures often compromise the tooth’s long-term viability, necessitating a later extraction.
Options for Replacing Missing Molars
When a permanent molar is lost due to disease or trauma, replacement is advised to preserve bite alignment and chewing function. One of the most common and durable replacement methods is the dental implant. An implant involves surgically placing a titanium post into the jawbone, which acts as an artificial root for a custom-made crown.
Another option is a fixed dental bridge, which “bridges” the gap created by the missing molar. This restoration involves crowning the healthy adjacent teeth and using them as anchors for an artificial tooth. For individuals missing multiple teeth, a removable partial denture offers a less invasive and often more affordable solution. A partial denture consists of replacement teeth attached to a gum-colored base secured by clasps onto the remaining natural teeth.