When tooth decay erodes the protective layers of a tooth, a dental filling is necessary. A filling is a restorative material used to repair the structure damaged by bacterial activity and acid production. The procedure physically seals the breached area, preventing further damage and protecting the sensitive internal tissues. This treatment is required once bacteria have penetrated the hard outer enamel layer.
Understanding Tooth Decay and Cavities
Tooth decay, or dental caries, begins with the presence of dental plaque, a sticky film composed primarily of bacteria and their byproducts. Specific oral bacteria, such as Streptococcus mutans and Lactobacillus, thrive on dietary sugars and starches. They metabolize these carbohydrates and produce acidic waste, primarily lactic acid, which initiates the process of demineralization.
Demineralization occurs when the acid lowers the pH level on the tooth surface below a threshold of approximately 5.5. At this acidity, the calcium and phosphate ions forming the enamel crystals begin to dissolve. If this acidic environment is temporary, the mouth’s natural saliva can neutralize the acid and allow for remineralization, a natural repair process. This early stage often appears as a white spot lesion on the enamel surface.
A true cavity forms when demineralization overwhelms the capacity for repair and penetrates the enamel. Once the decay reaches the underlying dentin, progression accelerates because dentin is softer and less mineralized. Dentin contains microscopic tubules that allow the decay to spread deeper toward the sensitive pulp. At this point, the damage is irreversible, and a physical filling is required to restore the lost structure and seal the deeper layer.
What Happens If a Cavity Goes Untreated
Ignoring a cavity allows the bacterial infection to continue its destructive path through the dentin tubules. The decay will eventually reach the pulp chamber, which houses the tooth’s nerves and blood vessels. This invasion causes inflammation and infection within the pulp tissue, a condition known as pulpitis.
Pulpitis can lead to severe and constant pain, especially when exposed to temperature changes or pressure. If the infection remains untreated, the pulp tissue will die, and the bacteria will spread beyond the root tip. This often results in a periapical abscess, a painful pocket of pus and infection located in the jawbone surrounding the tooth’s root apex.
Treating an abscess requires significantly more complex and costly procedures than a simple filling. The infection necessitates either root canal therapy, which involves removing the infected pulp and sealing the root, or, in severe cases where the tooth structure is compromised, a complete tooth extraction.
The Filling Procedure and Material Choices
The process begins with administering a local anesthetic, such as lidocaine, to numb the tooth and surrounding gum tissue. This ensures the patient experiences no pain during the removal of the decayed material. Once numb, the dentist uses a specialized dental drill to precisely remove all compromised and infected tooth structure.
The removal aims to preserve as much healthy tooth structure as possible while ensuring no bacteria-laden tissue remains. After the decay is cleared, the resulting space, called the preparation, is thoroughly cleaned and disinfected. The surface is then prepared with an etching gel and a bonding agent to ensure the filling material adheres securely.
Patients have several options for restorative materials, with the choice often depending on the filling’s location and visibility. Composite resin fillings are the most common choice today, as they are tooth-colored and highly aesthetic. This material is a mixture of acrylic plastic and fine glass or quartz particles.
Composite resin is applied in layers and hardened instantly using a high-intensity blue curing light, a process called polymerization. Alternatively, dental amalgam, often referred to as a silver filling, remains an option due to its durability and longevity, especially for large restorations in the back chewing teeth. Amalgam is an alloy of metals, including silver, tin, copper, and mercury, which is mixed into a paste and packed into the preparation.
The choice between materials is influenced by factors like the size of the cavity, the chewing forces the tooth must withstand, and aesthetic preferences or cost considerations. Composite resin requires a dry field for successful bonding and is more technique-sensitive than amalgam. Amalgam, while durable, lacks the natural appearance of composite resin.
Immediately following the procedure, patients will experience lingering numbness from the local anesthetic, which wears off within a few hours. It is normal to feel temporary sensitivity to hot or cold temperatures for a few days or weeks as the tooth recovers. Maintaining excellent oral hygiene and regular check-ups is necessary to ensure the filling’s longevity and prevent new decay from forming at the margins of the restoration.