Long‐term calcium hydroxide as a root canal dressing may increase risk of root fracture

Abstract

It has been proposed (Cvek 1992) that immature teeth are weakened by filling of the root canals with calcium hydroxide dressing and gutta-percha. The aim of the present study was to test the hypothesis that dentin in contact with calcium hydroxide would show a reduction in fracture strength after a certain period of time. Immature mandibular incisors from sheep were extracted and divided into two experimental groups. Group 1: the pulps were extirpated via the apical foramen. The root canals were then filled with calcium hydroxide (Calasept) and sealed with IRM(R) cement, and the teeth were then stored in saline at room temperature for 0.5, 1, 2, 3, 6, 9, or 12 months. Group 2: the pulps were extirpated and the root canals were filled with saline and sealed with IRM(R) cement. The teeth were then stored in saline for 2 months. Intact teeth served as controls and were tested immediately after extraction. All teeth were tested for fracture strength in an Instron testing machine at the indicated observation periods. The results showed a markedly decrease in fracture strength with increasing storage time for group 1 (calcium hydroxide dressing). The results indicate that the fracture strength of calcium hydroxide-filled immature teeth will be halved in about a year due to the root filling. The finding may explain the frequent reported fractures of immature teeth filled with calcium hydroxide for extended periods.

Comparison of Fracture Sites and Post Lengths in Longitudinal Root Fractures

“…In particular, a number of studies have shown that cracks form more readily with a nickel-titanium rotary file than when a hand instrument is used (3 -5). Prolonged irrigation of the root canal with highly concentrated irrigant solutions (6,7) and long -term application of calcium hydroxide to the root canal are reported to decrease the strength of the dentin (8)(9)(10). Excessive pressure applied during root canal obturation is also seen as a cause of root fracture (11,12).…”

Intracanal Irrigating Solutions Prior to Calcium Hydroxide Medication and Its Effects on Root Dentin Strength

“…Reports have shown that one week of calcium hydroxide medication can damage dentin resistance (3). Andreasen et al (17) demonstrated that extracted sheep incisors filled with calcium hydroxide for 1/2, 1, 2, 3, 6, 9, or 12 months had their fracture strength greatly reduced, and this decrease was proportional to the increase of the experimental periods. Sahebi et al (16) reported that dentin cylinders exposed to calcium hydroxide for 30 days needed a lower compression load to fracture.…”

“…Meanwhile, root canals treated with calcium hydroxide medication, even for short (16) or long periods (17), may be associated with reduced dentin strength. However, there is little scientific knowledge about the effects of irrigating solutions, like NaOCl and EDTA, prior to calcium hydroxide medication on root dentin strength.…”

Intracanal dressing paste composed by calcium hydroxide, chlorhexidine and zinc oxide for the treatment of immature and mature traumatized teeth

“…Contrasting with the uncertainty about this new treatment, apexification is a well-known and successful procedure with long-term followup studies 11 . Although it is a well-known procedure, apexification also presents some disadvantages, due to the lack of patient cooperation for intracanal dressing changes, long-term weakening of the root considering the hygroscopic and proteolytic properties of calcium hydroxide, increase of fracture risk and pulp space contamination 12 .…”