External Cervical Root Resorption Research Articles

The effect of the bleaching agent sodium perborate on macrophage adhesion in vitro: Implications in external cervical root resorption

The purpose of this study was to investigate the in vitro effect of sodium perborate, which is used as a bleaching agent in the treatment of discolored pulpless teeth, on substrate adherence capacity of macrophages. Inflammatory macrophages were obtained from Wistar rats and resuspended in RPMI-1640 medium. As a test of macrophage adhesion, the adherence capacity of macrophages to a plastic surface was determined. Assays were conducted in Eppendorf tubes for 15 min of incubation at 37 degrees C in a humidified atmosphere of 5% CO2. The adherence index was calculated. Results showed that sodium perborate decreased in a dose-dependent manner and decreased significantly (p < 0.05) the adherence index of rat peritoneal macrophages. Sodium perborate was less potent than sodium hypochlorite and eugenol in inhibiting macrophage adhesion. The inhibitory effect of sodium perborate on macrophage adhesion further supports the concept that this agent is not implicated in external cervical root resorption associated with intracoronal bleaching.

Role of cementoenamel junction on the radicular penetration of 30% hydrogen peroxide during intracoronal bleaching in vitro.

Intracoronal bleaching of nonvital, teeth with 30% hydrogen peroxide is occasionally associated with external cervical root resorption. The exact mechanism by which bleaching induced root resorption occurs is not yet fully understood. The relationship of cementum to the enamel at the cementoenamel junction may have clinical significance. Seventeen single rooted human mandibular premolars extracted atraumatically for orthodontic reasons were used. The radicular hydrogen peroxide penetration in each tooth was measured in vitro by an indirect colorimetric method. Thereafter, the teeth were examined with a scanning electron microscope to determine the type of the cementoenamel junction. It was found that the radicular penetration of 30% hydrogen peroxide was related to the type of cementoenamel junction.

Radicular penetration of hydrogen peroxide during intra‐coronal bleaching with various forms of sodium perborate

The development of external cervical root resorption following internal bleaching of discoloured pulpless teeth is associated with the use of hydrogen peroxide. The aim of the study was to determine radicular penetration of hydrogen peroxide following intracoronal bleaching with various forms of sodium perborate. 63 extracted human incisors were root filled and stained artificially. Standardized cementum defects were created on the mesial and distal aspects of the root directly below the cemento-enamel junction (CEJ). Using the walking bleach technique all teeth were bleached for a 6-day period, with replacement of the bleaching paste after days 1 and 3. Sodium perborate monohydrate (MH), trihydrate (TRH) or tetrahydrate (TH) was mixed with H2O2 or H2O and subsequently placed intracoronally 1 mm below the labial CEJ. The teeth were divided into six groups: I. MH + H2O2(30%) (n = 12); II. TRH + H2O2(30%) (n = 12); III. TH + H2O2(30%) (n = 12); IV. TH + H2O (n = 12); V. TH + H2O, gel (n = 12); VI. no bleaching paste (n = 3). At baseline and at days 1, 3 and 6 the amount of H2O2 taken up from the surrounding medium of each root was indirectly recorded and calculated as p.p.m. Almost all teeth of the experimental groups showed leakage of hydrogen peroxide compared to those of the control group. The radicular penetration of hydrogen peroxide was significantly higher in teeth of groups I and III than in those of groups IV and V (P < or = 0.001). In conclusion, the amount of hydrogen peroxide leakage depends, among other factors, on the form of sodium perborate used.(ABSTRACT TRUNCATED AT 250 WORDS)

A method to determine the location and shape of an intracoronal bleach barrier

The external cervical root resorption associated with intracoronal bleaching of pulpless teeth can be a devastating lesion. It often cannot be repaired. To prevent this problem, increasing attention has been focused on placing a barrier between the pulp chamber and the endodontic filling material. The objective of this article is to propose a method for determining the location and shape of an intracoronal bleach barrier.

Effect of intracoronal bleaching on external cervical root resorption

The purpose of this study was to examine histologically and radiographically the effect of a bleaching agent, a mixture of sodium perborate and superoxol (30% hydrogen peroxide), without a heat source on the cervical root surface and periodontal tissue of endodontically treated teeth of dogs. Endodontic treatment was performed on anterior teeth of dogs. The endodontically treated teeth were then divided into two groups. One group received walking bleach procedures, while the other group did not. The animals were killed at intervals of 1 and 3 months after bleaching for histological and radiographic examination. External cervical root resorption was only observed in bleached teeth at 3-month but not at 1-month observation.

Effect of trichloracetic acid on the microhardness and surface morphology of human dentin and enamel.

Trichloracetic acid is recommended for the treatment of external cervical root resorption. The present study examined the effect of 90% trichloracetic acid on the microhardness and surface morphology of human dentin and enamel. Intact extracted human teeth were sectioned and embedded in acrylic resin. Each tooth was grinded and highly polished exposing a flat surface of dentin and enamel. The teeth were treated with 90% trichloracetic acid for 30, 60 and 90 s. Vicker's microhardness of the dentin and enamel was assessed for each tooth before and after each treatment. In addition the surface morphology of a trichloracetic acid treated tooth was examined via SEM. The results showed that 90% trichloracetic acid caused a second order type reduction of the microhardness, as well as structural changes in both dentin and enamel.

In vitro determination and quantification of 30% hydrogen peroxide penetration through dentin and cementum during bleaching

Bleaching pulpless teeth with 30% hydrogen peroxide was reported to cause external cervical root resorption. It was hypothesized that H 2O 2 penetrated open dentin tubules to initiate an inflammatory response that could result in root resorption. No direct experimental evidence was provided to support this theory. An in vitro model for determination and quantification of H 2O 2 penetration during bleaching procedures is suggested. Artificial defects of the cementum covering the cementoenamel junction were performed in 22 extracted human premolars. After 15 minutes of thermocatalytic bleaching, H 2O 2 could be detected in the medium surrounding all the tested teeth. Cervical root permeability to 30% H 2O 2 could reach up to 82% of the total amount applied.

PH variation among materials used for intracoronal bleaching

Intracoronal bleaching of pulpless teeth with 30% hydrogen peroxide may result in external cervical root resorption. One of several suggested etiological factors associated with this complication is the pH of the bleaching materials. Because the available data on the pH values of bleaching materials were conflicting, it was the purpose of this study to measure the pH of the materials commonly used for bleaching pulpless teeth. The pH of different concentrations of sodium perborate and 30% hydrogen peroxide, alone or in combination, were measured for a period of 14 days. Sodium perborate was confirmed to be alkaline, whereas 30% hydrogen peroxide was acidic. The pH of the materials when mixed together gradually changed from acidic to alkaline as the concentration of sodium perborate was increased. A thick clinical consistency mixture of both materials was alkaline, and its alkalinity increased with time. These results do not support the theory relating bleaching-induced root resorption to an acidic pH of the bleaching pastes.

Effect of cementum defects on radicular penetration of 30% H 2O 2 during intracoronal bleaching

Bleaching pulpless teeth with 30% hydrogen peroxide has been reported to cause external cervical root resorption. It has been hypothesized that H2O2 penetrating through open dentin tubules can initiate an inflammatory reaction which could result in root resorption. Extracted human premolars were treated endodontically and bleached intracoronally using the thermocatalytic technique. The teeth were divided into three groups; one group with no cementum defects at the cementoenamel junction, one group with artificial cementum defects at the cementoenamel junction, and another group with artificial cementum defects at the middle third of the root. The radicular penetration of 30% hydrogen peroxide in the three groups was assessed directly and compared using an in vitro model. Radicular penetration of hydrogen peroxide was found in all of the groups tested. The penetration of hydrogen peroxide was significantly higher in teeth with cementum defects at the cementoenamel junction than in those without defects.

External cervical root resorption following bleaching

A case of external cervical root resorption is reported as a sequela to internal bleaching techniques and possible trauma. The etiology of cervical root resorption is reviewed. Treatment implications are also discussed with emphasis on prevention. The clinician must consider the cosmetic benefits of bleaching in light of the potential risk of root resorption.

Cervical external root resorption

Abstract Cervical external root resorption is frequently confused with internal resorption, yet a correct diagnosis is of great importance because the methods of treating these two conditions differ fundamentally. Views on the aetiology of cervical external root resorption are disparate, but it seems most plausible that the cause is chronic inflammation of periodontal tissues.