An in vivo comparison of working length determination of two frequency-based electronic apex locators.

AIM: To compare in vivo the accuracy of two electronic apex locators (EALs) by means of digital radiographic imaging system. METHODOLOGY: Electronic working lengths of 831 canals were determined with the DentaPort ZX and Raypex 5 apex locators and confirmed radiographically. The radiographic images acquired with the aid of a digital radiographic imaging system (VisualiX eHD; Gendex Dental Systems, Des Plaines, IL, USA) were blindly analysed by two independent evaluators. The distance between the file tip and the radiographic apex was measured using dedicated software (VixWin Pro, Gendex Dental Systems, Des Plaines, IL, USA) and the mean distance achieved between different tooth type and EALs were compared statistically. Statistical analyses were performed using the t-test for independent samples and one-way anova with the null hypothesis set as 5%. Positive or negative values were recorded when the file tip was detected beyond or short of the radiographic apex, respectively. RESULTS: The mean distance between file tip and radiographic apex were -1.08 +/- 0.73 and -1.0 +/- 0.67 mm considering DentaPort ZX and Raypex 5 groups, respectively, with no significant differences (P > 0.05). No statistically significant differences were found amongst the same tooth type when comparing both groups (P > 0.05) or amongst different teeth type in the same group (P > 0.05). CONCLUSIONS: Within the limitations of this in vivo study, the DentaPort ZX and Raypex 5 were similar in terms of accuracy.

In vitro cytotoxicity of root canal filling materials: 1. Gutta-percha.

Gutta-percha (GP) has been the most widely used root canal filling material because of its well-known low toxicity. The inertness of GP, however, was challenged recently. The purpose of this study was to evaluate the toxicity of marketed endodontic GP using the radiochromium release test. Fourteen commercially available and three experimental GP brands were tested. Raw GP, zinc oxide, and barium sulfate, which were considered major components of GP points, and zinc ions were also evaluated. The material was spread to cover the bottom of testing wells after being dissolved in chloroform or warmed. A labeled suspension of L929 cells was added to the wells. After incubation at 37 degrees C for 4 and 24 h, extracellular radiochromium in the culture medium was measured and calculated in percentage of the total intracellular label. Spontaneous release of radiochromium was used as control and the results were considered to be within normal limits either at 4 or 24 h. All chloroform-dissolved GP showed low toxicity at 4 h, whereas warmed GP showed statistically significant differences at 4 h. Both dissolved and warmed GP were toxic at 24 h. The raw materials and barium sulfate were not toxic, whereas zinc oxide and zinc ions showed marked toxicity. All GP points tested were toxic at longer observation periods, and the toxicity was attributed to leakage of zinc ions into the fluids.

Long-term follow-up on C-shaped mandibular molars.

Three cases of mandibular second molars with C-shaped root canal morphology are described. Two of these molars did not radiographically show the usual anatomic configuration of two separated roots, but rather had a single conical root. Only two root canals orifices were observed in the pulp chamber floor: a mesial-lingual orifice in its normal position and a buccal C-shaped fissure that was continuous from the normal location of the mesiobuccal canal to that of the distal canal. The fissure became smaller in the apical third, ending in a distal direction. The third case, a second molar extracted because of severe periodontal involvement showed, after sectioning, a C-shaped root with connections between all three canals.

A comparative study of physicochemical properties of AH Plus and Epiphany root canal sealants.

AIM: To evaluate setting time, solubility and disintegration, flow, film thickness, and dimensional change following setting in a dual-cured resin root canal sealer Epiphany compared with an epoxy-resin-based sealer AH Plus. METHODOLOGY: The experiments were performed according to ANSI/ADA Specification 57 which tests the physicochemical properties of endodontic sealing materials. Five samples of each material were tested for each of the properties. In addition, deionized distilled water from the solubility test of Epiphany was submitted for analysis of the cations Fe, Ni, Ca, Mg, Zn, Na, and K in an atomic absorption spectrometer. Three samples were analysed. RESULTS: There were no statistical differences (P>0.05) in flow (AH Plus: 38.57 mm; Epiphany: 35.74 mm) and film thickness (AH Plus: 10.6 microm; Epiphany: 20.1 microm). The solubility (AH Plus: 0.21%; Epiphany: 3.41%) and dimensional alterations following setting (AH Plus: expansion of 1.3%; Epiphany: expansion of 8.1%) were statistically different (P<0.05). The setting times of both sealants were in accordance with ANSI/ADA requirements. CONCLUSIONS: Setting time, flow, and film thickness tests for both cements conformed to ANSI/ADA standards. Dimensional alteration test for both cements were greater than values considered acceptable by ANSI/ADA. Epiphany values regarding solubility were also greater than values considered acceptable by ANSI/ADA.

Calculus-like deposit on the apical external root surface of teeth with post-treatment apical periodontitis: report of two cases.

AIM: To report two cases in which calculus-like material was found on external root surfaces of (i) an extracted root and (ii) an apicected part of a root, both of which were removed due to post-treatment refractory apical periodontitis. SUMMARY: In each case, there was a fistulous tract, which did not heal after conventional root canal treatment. The first case did not heal even after apical surgery, and subsequent tooth extraction revealed calculus-like material on a root surface of complex anatomy. The second case showed radiographic signs of healing after apicectomy. Histology of the apical biopsy revealed a calculus-like material on the external surface of the root apex. It is suggested that the presence of calculus on the root surfaces of teeth with periapical lesions may contribute towards the aetiology of failure. KEY LEARNING POINTS: Biofilm on the external root surface has been implicated in the failure of apical periodontitis to heal, despite adequate root canal treatment. Calculus-like material was found, in two cases, on the root surface of teeth with post-treatment apical periodontitis, where the only communication externally was a sinus tract.

Traumatically injured primary incisors: a clinical and histological study.

World-wide epidemiological studies state that from 8 percent to 30 percent of children up to 7 years of age sustain injury to primary incisors, including crown fracture, root fracture, tooth avulsion, and dental displacement, which result in malformation of permanent incisors depending upon their state of development. In this study, traumatized primary incisors were evaluated clinically and radiographically, with the following data recorded: exact or approximate time-interval of traumatic episode(s) and extraction, mobility, color change, sensitivity to percussion/palpation, swelling, sinus tract, caries, crown/root fracture, periodontal/periapical lesions, external/internal root resorption, mineralization, and obturation. Based upon the local damage and developmental age, 138 teeth were extracted, fixed in 10 percent formalin, and processed for histological evaluation according to routine methodology. Histologic findings were: the presence of varying extent of necrosis, bacteria in the area of necrosis--not in all cases--neutrophilic leukocytes, chronic inflammatory cells, pulpal calcifications, resorption/apposition, and circulatory changes. The blood pigment distinguished hemorrhage due to extraction from pathologic circulatory changes. All the described reactions varied in intensity and extent with the time interval and the assumed force of the original trauma. Physical trauma to primary teeth caused pulpal damage, which could involve periapical tissue, depending on the extent of the initial damage.

Paste technique re-treatment study: a clinical, histopathologic, and radiographic evaluation of 50 cases.

This study correlated clinical, radiographic, and histopathologic aspects of 50 endodontic failures involving the paste technique. All clinical and radiographic findings were recorded. The teeth were re-treated with gutta-percha/Kloroperka and lateral condensation. Subsequently, periapical surgery, including retrograde amalgam filling, was performed for the removal of material in the periapical tissue. The resulting biopsy specimens were processed for histologic evaluation. Although neutrophilic leukocytes predominated in some cases, all types of inflammatory cells were present. Macrophages and foreign body cells contained paste particles. The blood pigment distinguished hemorrhage due to surgery from pathologic circulatory changes. There was resorption/apposition of bone and root fragments. Epithelial strands and parts of cyst walls were observed. There was a correlation between a periapical radiolucency and inflammation but no correlation between amounts and types of inflammatory cells and pain. Paste placed beyond the foramen caused tissue damage and reduced prognosis.

Tissue reaction to endodontic materials: methods, criteria, assessment, and observations.

The purpose of this study was to develop methods and criteria for the testing of the biocompatibility of endodontic materials. One hundred twenty-one teeth from 12 baboons (Papio anubis) were used to test three sealers: AH26, Kerr pulp canal sealer, and Kloroperka N.O. Gutta-percha cones were used as solid core in all cases. Under disinfected conditions, access preparation was performed, and with working length approximately 1.0 mm short of the foramen, the instrumentation of the root canal was started, using sodium hypochlorite (1%) for irrigation. After the root canals were cleaned and shaped, they were obturated with gutta-percha cones and the sealer, and by lateral condensation technique. Histologic periapical reactions were evaluated at 1, 7, 30, 365, 730, and 1095 days. The methods and criteria used were adequate for ranking of the biocompatibility of the tested materials in the short and long periods. At short observation periods (1 to 7 days) AH26 caused severe reactions, and Kerr pulp canal sealer and Kloroperka N.O., moderate and mild reactions, respectively. At 2- and 3-year observation periods the ranking was AH26, mild; Kerr pulp canal sealer, moderate; and Kloropercha N.O., severe.

Clinical, radiographic, and histologic study of endodontic treatment failures.

One hundred fifty cases of endodontic treatment failures were studied clinically, radiographically, and histologically. Fifty-seven percent of the teeth were asymptomatic. Pain alone and/or associated with swelling was present in 21% of the teeth. There was no correlation between the size of periradicular rarefaction and the occurrence or severity of clinical signs and/or symptoms. Stainable bacteria were demonstrated in 69% of the teeth and were present mostly in the canal. The severity of periradicular inflammation was related to presence of stainable bacteria in the canal. Swelling and pain or a draining sinus tract was often associated with stainable bacteria inside the canal. The development of a radicular cyst associated with an endodontically treated tooth that has failed is not necessarily the cause of endodontic treatment failure.

A comparative histological evaluation of the biocompatibility of materials used in apical surgery.

AIM: To evaluate the biological properties of a variety of materials that could be used in apical surgery. METHODOLOGY: The intraosseous implant technique recommended by the FDI (1980) and ADA (1982) was used to test the following materials: zinc oxide-eugenol (ZOE), mineral trioxide aggregate (MTA), and Z-100 light-cured composite resin. Thirty guinea-pigs, 10 for each material, divided into experimental periods of 4 and 12 weeks, received one implant on each side of the lower jaw symphysis. The connective tissue response alongside the lateral wall outside the cup served as a negative control for the technique. At the end of the observation periods, the animals were killed and the specimens prepared for routine histological examination to evaluate their biocompatibility. RESULTS: The reaction of the tissue to the materials diminished with time. The ZOE cement was highly toxic during the 4-week experimental period, but this profile changed significantly after 12 weeks, when it showed biocompatible characteristics. MTA and Z-100 showed biocompatibility in this test model at both time periods. CONCLUSIONS: MTA and Z-100 composite were biocompatible at 4 and 12 weeks in this experimental model.