Dental fillings are common restorative treatments. Dental professionals use the standardized G.V. Black classification system to categorize cavities based on their location on the tooth surface. Understanding this system is important because the location dictates the cause, treatment approach, and choice of filling material. This article focuses specifically on the Class V lesion, a defect found near the gum line.
Defining Class V Lesions and Location
The G.V. Black classification divides lesions into six classes based on the anatomical area of the tooth they affect. The Class V designation refers to lesions located specifically on the cervical third of the tooth.
The cervical third is the portion of the tooth closest to the gum line, located on either the cheek (buccal or facial) or tongue (lingual) side. Unlike Class I or Class II lesions, Class V defects occur on the smooth surface of any tooth, front or back. This location makes the defects highly visible, creating aesthetic concerns, especially on front teeth. Because this area is close to the sensitive root surface, these lesions often cause tooth sensitivity to temperature changes.
Unique Causes of Class V Cavities
Class V lesions frequently result from factors other than typical bacterial decay, known as non-carious cervical lesions (NCCLs). These defects are often caused by a combination of three main types of physical and chemical wear. Abrasion occurs when external friction removes tooth structure, commonly resulting from aggressive, horizontal toothbrushing or abrasive toothpaste. This mechanical wear creates a shallow, flat-shaped defect.
Erosion involves the chemical dissolution of tooth enamel and dentin due to acid exposure, separate from bacterial activity. This acid can be extrinsic (from acidic foods and drinks like soda) or intrinsic (linked to conditions like acid reflux or frequent vomiting). The third cause is abfraction, a theory proposing that excessive biting forces, such as grinding or clenching (bruxism), cause the tooth to flex. This stress concentrates at the cervical area, leading to wedge-shaped defects with sharp internal angles.
Many gumline defects are mixed lesions, meaning a combination of abrasion, erosion, and abfraction contributes to the loss of tooth structure. Dental professionals must accurately identify the primary cause to prevent the lesion from recurring after restoration. Addressing the underlying issue, such as modifying brushing habits or managing acid reflux, is necessary for long-term success.
The Procedure and Filling Materials
Restoring a Class V lesion requires a specific clinical approach due to its location at the junction of the tooth and gum tissue. Although the lesion is accessible, achieving a dry, isolated working field is challenging due to the constant presence of gum fluid and saliva. The dentist must carefully prepare the area to remove damaged tissue while avoiding injury to the surrounding gum.
Material selection is dictated by the lesion size, the patient’s aesthetic needs, and moisture control difficulty. Composite resin, a tooth-colored plastic material, is frequently chosen for its cosmetic properties, especially for visible lesions. However, bonding composite to the dentin near the gum line can be less reliable than bonding to enamel, sometimes leading to leakage or staining.
Glass Ionomer Cement (GIC) or Resin Modified GIC (RMGIC) are alternative materials favored for Class V restorations. These materials release fluoride, which helps protect the surrounding tooth from future decay. They also bond well to the dentin in the cervical area. Some dentists use a technique where GIC is placed as a base layer and then covered with composite resin for better aesthetics.