20 January 2017
Root resorption is the loss of dental hard tissues as a result of clastic activities. There are two types of root resorption in dentistry that we know, one is physiologic and the other is pathologic. Root resorption in the primary dentition is considered a normal physiologic process except when the resorption occurs prematurely. On the other hand, pathologic resorption causes a progressive loss of tooth structure. It occurs when there is a break in the protective covering of the dentin, the cementum on the external surface, or the odontoblast layer on the internal surface, which allows clastic cells from the circulatory system access to the dentin. Unfortunately, pathologic resorption frequently is diagnosed too late for effective treatment, misdiagnosed and sometimes treated inappropriately.
There are four types of pathologic resorption in dentistry, one is internal and three external.
1. Internal resorption (IR)
2. Invasive Cervical Resorption (ICR)
3. External Inflammatory Resorption (EIR)
4. Replacement Resorption (RR)
In this article, internal root resorption only will be discussed from it’s prevalence, etiology, diagnosis to treatment perspective and followed case report.
Internal root resorption has been described as intraradicular or apical according to the location in which the condition is observed. Intraradicular internal resorption is an inflammatory condition that results in progressive destruction of intraradicular dentin and dentinal tubules along the middle and apical thirds of the canal walls. This condition is more frequently observed in male than female subjects. Patel el al (2010) reported that the most commonly affected teeth were maxillary incisors.
Apical internal resorption on the other hand is fairly common occurrence in teeth with periapical lesions. In the rest of this article, only intraradicular forms of internal root resorption will be discussed and and it will be simply referred to as internal resorption.
For internal root resorption to occur, the outermost protective odontoblast layer and the predentin of the canal wall must be damaged, resulting in exposure of the underlying mineralized dentin to odontoclasts. Various etiologic factors have been proposed for the loss of predentin, including trauma, caries and periodontal infections, excessive heat generated during restorative procedures on vital teeth, calcium hydroxide procedures, vital root resections, orthodontic treatment, or simply idiopathic dystrophic changes within normal pulps. Calixskan MK, 1997 showed a study of 25 teeth with internal resorption, trauma was found to be the most common predisposing factor that was responsible for 45% of the cases examined. The other etiologies as suggested by Wedenberg, 1987 were inflammation as a result of carious lesions (25%) and carious / periodontal lesions (14%) also pulpal inflammation/infection. Those are the major contributory factors in the initiation of internal resorption. However, the advancement of internal root resorption depends on bacterial stimulation of the clastic cells involved in hard tissue resorption. Without this stimulation, the resorption will be self-limiting (Wedenberg, 1987).
Among the four types of pathologic resorption, internal resorption is the most well known in the dental community although it is fairly uncommon. Internal resorption originates in a vital pulp, and the pulp must remain vital for the resorption to be progressive. Unfortunately in many cases internal resorption is found after the pulp has become necrotic and the process has arrested. Teeth with internal resorption usually are asymptomatic and often identified radiographically. Clinically, internal resorption teeth sometimes can be identified when resorption is in the coronal area and the tooth takes on a pink hue. Radiographically, internal resorption usually is round or oval-shaped and centered on the root canal, and the canal is not visible through the resorption area. Also, the defect for internal resorption is a widening of the canal.
In general, there are three treatment options for internal resorption
1. No treatment with eventual extraction if and when the tooth becomes symptomatic.
2. Immediate extraction.
3. Saving it by doing internal treatment that include conventional root canal treatment.
Before we decide our plans, we must make a decision first on the prognosis of the tooth. If the resorption is contained within the root with no perforation, good prognosis for treatment with conventional endodontic treatment can be achieved. If the resorption perforates the root the prognosis is reduced. If the resorption is in the cervical area of the tooth, long term predictability of the tooth needs to be considered from a structural point, especially for anterior teeth. Restorability also must not forget to consider for deciding the treatment plan and if the tooth is restorable and has a reasonable prognosis, saving it by doing root canal treatment is the choice.
In internal resorption, our purpose of doing root canal treatment is to remove any remaining vital or necrotic tissues in the systems that can sustained and stimulate the resorbing cells via their blood supply. Good access cavity preparation is important. In teeth with actively resorbing lesions, we might need to be extra careful since bleeding from the inflamed pulpal and granulation tissues can occur and might impair visibility during the initial stages of chemomechanical debridement. The use of material such as Mineral trioxide aggregate (MTA) is also suggested to repaire internal resorption successfully, especially when there is a perforation on the root.