Invasive cervical resorption (ICR) is a specific type of tooth resorption affecting the area near the gum line, where the tooth meets the soft tissues. This condition involves the progressive destruction of the tooth structure, beginning from the outside surface. It is an aggressive process that can lead to significant damage if not identified and addressed promptly.
What is Invasive Cervical Resorption?
Invasive cervical resorption involves the progressive breakdown of tooth structure, specifically the hard tissues like enamel and dentin. It originates from the outer surface of the tooth at its cervical region, or neck. This area is located near the gum line. The process involves the replacement of the mineralized tooth structure with a fibro-vascular tissue rich in blood vessels.
This condition differs from other types of tooth resorption, such as internal resorption, because its origin is external, rather than from within the pulp chamber. While internal resorption arises from the pulp tissue inside the tooth, ICR begins on the root’s external surface and invades inward. The aggressive nature of ICR often means it progresses silently and asymptomatically in its early stages, making early detection challenging.
If left untreated, this progressive destruction can lead to extensive tooth damage and potentially tooth loss.
Identifying the Causes
The exact cause of invasive cervical resorption is often multifactorial and not fully understood. Various factors and conditions are believed to contribute to its development. The process is thought to begin with damage to the protective layer of cementum on the root surface, which then allows cells to initiate the resorptive process.
One common association is dental trauma, such as impact injuries to the teeth, which can disrupt the cementum. Orthodontic treatment, particularly a history of such procedures, is also frequently linked to ICR, reported in up to 46% of cases. The stress placed on tooth roots during orthodontic movement may trigger an inflammatory response that weakens the tooth’s protective layers.
Tooth bleaching, especially external or intracoronal bleaching procedures, is another identified predisposing factor, as strong bleaching agents can weaken tooth structures. Periodontal (gum) disease or surgery can also contribute by causing a break in the cementum layer, providing an entry point for the resorptive process. Previous dental procedures, like restorations or root canal treatments, have also been associated, although ICR can occur in vital (living) teeth.
Genetic predisposition may also play a role, as some individuals might naturally have thinner cementum and dentin layers, increasing their susceptibility. It is important to remember that not everyone with these risk factors will develop ICR, and in some cases, the condition can appear without any clear predisposing event.
Recognizing Symptoms and Diagnosis
In its early stages, invasive cervical resorption often progresses without any noticeable symptoms. As the resorption advances, certain signs may become apparent. A notable symptom is a pinkish discoloration of the tooth, which results from the highly vascularized resorptive tissue showing through the remaining tooth structure.
As the lesion deepens, individuals might experience sensitivity to hot or cold temperatures, or discomfort while chewing. Pain typically occurs in later stages, particularly if the resorptive process reaches and involves the dental pulp. Gum inflammation or bleeding around the affected tooth may also be observed.
Diagnosing ICR involves a combination of clinical examination and specialized imaging. A dentist will conduct a visual inspection, looking for discoloration or changes in the gum tissue around the affected tooth. Radiographic examinations are also performed, with periapical X-rays often revealing irregular, mottled radiolucencies, which can sometimes be mistaken for dental caries.
For a more detailed assessment of the lesion’s extent and invasiveness, 3D imaging techniques like Cone Beam Computed Tomography (CBCT) are recommended. CBCT provides a three-dimensional view, allowing for accurate classification and treatment planning by showing the precise size, location, and spread of the lesion. Early and accurate diagnosis is important due to the aggressive nature of this condition.
Treatment Options
The approach to treating invasive cervical resorption depends on the stage and extent of the resorption. For early, superficial lesions, non-surgical management involves careful debridement, which is the removal of the resorptive tissue, followed by restoration of the defect with a suitable dental material such as glass ionomer (GI) or resin-modified glass ionomer (RMGI), which have shown high success rates.
For more advanced lesions, surgical intervention is often necessary to gain access to the affected area and thoroughly remove the resorptive tissue. This surgical debridement may involve raising a gum flap to expose the lesion. If the dental pulp is involved or at risk due to the extent of the resorption, root canal treatment may be performed in conjunction with the surgical repair.
Following the removal of the resorptive tissue, materials like mineral trioxide aggregate (MTA) or other bioceramics may be applied to repair the defect, as these materials have excellent biocompatibility and can encourage the regeneration of surrounding tissues. In cases where the tooth has sustained severe, irreversible damage and cannot be saved, extraction may be the only viable option.
The prognosis for teeth affected by ICR varies depending on the classification of the lesion. Heithersay’s classification, which categorizes lesions based on their size and extension, indicates that Class 1 and 2 lesions generally have excellent success rates with proper treatment, potentially reaching 100%. Class 3 lesions have a reported success rate around 78%, while Class 4 lesions, which are extensive, have a significantly lower success rate of approximately 12.5%. Long-term follow-up is necessary to monitor for any recurrence of the condition.