In vitro bacterial penetration of coronally unsealed endodontically treated teeth

Forty-five root canals were cleaned, shaped, and then obturated with gutta-percha and root canal sealer, using a lateral condensation technique. The coronal portions of the root filling materials were placed in contact with Staphylococcus epidermidis and Proteus vulgaris. The number of days required for these bacteria to penetrate the entire root canals was determined. Over 50% of the root canals were completely contaminated after 19-day exposure to S. epidermidis. Fifty percent of the root canals were also totally contaminated when the coronal surfaces of their fillings were exposed to P. vulgaris for 42 days.     

Evaluation of root reinforcement of endodontically treated teeth

OBJECTIVES: The purpose of this study was to test the root reinforcing capabilities of a glass ionomer sealer and to test whether pretreatment of the instrumented canal to alter or remove the smear layer might enhance the reinforcement. STUDY DESIGN: Ninety single-canaled roots of standardized dimensions were instrumented to International Standards Organization size 45 and were analyzed for resistance to vertical fracture. Six groups were tested (n = 15). RESULTS: No significant difference in fracture resistance was observed between any of the groups. CONCLUSIONS: Under the conditions of this study, reinforcement of endodontically treated mature teeth by placement of adhesive materials in the root was not demonstrated.     

In vitro endotoxin penetration of coronally unsealed endodontically treated teeth

Abstract The purpose of the study was to evaluate the penetration of bacterial endotoxin (L.P.S.) through obturated root canals. Twenty-four single-rooted teeth were instrumented in a uniform manner. The root canals of 16 teeth were obturated with gutta-percha and Roth's sealer and 8 teeth were similarly obturated but without sealer. The teeth were then divided into three groups. Group 1 – Positive control (4 teeth). Teeth obturated without sealer were used. Sticky wax was softened in an open flame and painted over the external root surface except the apical 2 mm and coronal canal orifice which were left free of the sticky wax. Group 2 – Negative control (4 teeth). Again teeth without sealer comprised the teeth in this group. However, in this group the sticky wax covered the apical area of the root and the canal orifice coronally, in addition to the rest of the root. Group 3 – Experimental (16 teeth). The teeth obturated in conjunction with sealer were used. Otherwise the teeth were treated as in group 1. The coronal root half was then hermetically sealed from the apical root half so that LPS placed coronally could move only through the obturated canal space to the apical segment. One ml of water containing 100 μg/ml endotoxin was placed in the upper chambers and pyrogen-free water in the lower chambers. The upper and lower chambers were then tested for endotoxin at different time periods up to 21 days. The upper chambers tested positive for endotoxin at all test times for all teeth. All 4 positive control teeth showed endotoxin in the lower chambers by 24 hrs. None of the 4 negative control teeth showed endotoxin in the lower chambers for the duration of the study. Five of the 16 (31.5%) experimental teeth had demonstrable L.P.S. in the lower chambers by the end of the 21 day test period. According to the results of this study, endotoxin may move through obturated root canals.     

Enterococcus spp. in endodontically treated teeth with and without periradicular lesions

The purpose of this study was to determine if Enterococcus spp. are more prevalent in endodontically treated teeth with periradicular lesions compared with teeth that require retreatment but have no periradicular rarefaction. Fifty-eight teeth that had received root canal therapy more than 1 yr previously and required retreatment were included. Designation of lesion versus no lesion was determined by two experienced endodontists. DNA extraction and PCR amplification were performed using ubiquitous 16S rDNA bacterial primers, as well as Enterococcus spp.-specific primers. The results showed that the overall prevalence of bacteria was 90% and Enterococcus spp. was 12%. chi analysis revealed a statistically significant relationship between the presence of a lesion and the presence of bacteria, as detected by the universal primers (p = 0.032). Using logistic regression, a statistically significant relationship was found between teeth with normal periapex and the presence of Enterococcus spp. (p = 0.023). This study revealed that bacteria are significantly associated with endodontic treatment failure but enterococci are not associated with disease.     

Extrusion of endodontically treated teeth.

Extrusion in a vertical direction was used in efforts to retain 14 teeth that had subcrestal fractures, perforations, or caries below the gingival tissue. Indications for the procedure, techniques, and complications are discussed.     

Restoration of endodontically treated teeth.

Criteria have been presented for the evaluation of and treatment planning for endodontically treated teeth for final restoration. The dentist must consider the advantages and disadvantages of saving teeth according to their eventual role in restoring occlusal function, arch integrity, and esthetics. The prognosis is dependent on successful endodontic therapy, the presence of sound periodontal support, and an acceptable restorative effort. Currently accepted post and core systems and materials have been reviewed.     

In vitro microbial leakage of endodontically treated teeth using new and standard obturation techniques

Coronal microbial leakage is an important cause of apical periodontitis and thus should be prevented if possible. The purpose of this study was to compare microbial leakage of new and standard obturation techniques over a 30-day period. A split chamber microbial leakage model was used in which Streptococcus mutans placed in the upper chamber could reach the lower chamber only through the obturated canal. Leakage was assessed every day for 30 days. One hundred forty single-rooted human teeth were used in this study, equally split between lateral, vertical, and Obtura II condensation; SimpliFill with Obtura II condensation; FibreFill; and a combination of FibreFill and SimpliFill. Cochran-Mantel-Haenszel row mean score statistics showed a high statistical significance when all groups were compared (p < 0.0001). Microbial leakage occurred more quickly in lateral and vertical condensation techniques compared with SimpliFill and FibreFill techniques. A combination of an apical plug of gutta-percha with SimpliFill and a FibreFill coronal seal was the best obturation technique used (SimpliFill-FibreFill group).     

In vitro bacterial penetration of endodontically treated teeth coronally sealed with a dentin bonding agent

This study evaluated the effectiveness of a dentin bonding agent as a barrier to prevent coronal microleakage and examined the effect of a eugenol-based sealer on the sealing ability of this resin adhesive. Fifty-one extracted human mandibular molars were incorporated in a model system using an oral streptococci as a microbial marker. Group 1 consisted of 15 teeth that were obturated with only gutta-percha and received a coronal barrier of Clearfil Liner Bond 2V. Group 2 was identical to group 1, but included the use of a eugenol-based sealer in the obturation. Group 3 consisted of 15 teeth that were obturated with gutta-percha and sealer, but did not receive a coronal barrier. Six teeth served as controls. Bacterial penetration was monitored for 90 days. Results were analyzed after 30, 60, and 90 days with Fisher's exact test (p < 0.05). All controls behaved as expected. Neither group 1 nor group 2 exhibited any bacterial leakage. Eleven of the 15 specimens in group 3 leaked between 15 and 76 days. The coronal barriers in group 1 and group 2 were significantly better in preventing coronal microleakage at 60 days (p = 0.002) and 90 days (p = 0.00005). The presence of eugenol in the sealer had no significant effect on the sealing ability of Clearfil Liner Bond 2V (p = 1).     

Bleaching and restoring endodontically treated teeth.

Internal, or "walking," bleaching has been successfully used in dentistry for many years to reverse stains associated with nonvital teeth. The procedure is predictable for color change but is not without problems. Current research has identified the cause of cervical resorption, which has been associated with internal bleaching. Second-generation esthetic bonding materials theoretically should provide an improved seal at the tooth-restorative interface, but the limited current research does not support this contention. A suggested method for internal bleaching and restoring the access cavity is presented.     

In vivo fractures of endodontically treated posterior teeth restored with amalgam

Abstract The cumulative survival rate (retention of both cusps) and the fracture pattern of 1639 endodontically treated posterior teeth were assessed in a retrospective study. All teeth had an MO/DO or an MOD cavity restored with amalgam without cuspal overlays. The 20-year survival rate of teeth with an MO/ DO cavity was markedly higher than that of teeth with an MOD cavity. The lowest survival rate was found for the upper premolars with an MOD cavity: 28% of these teeth fractured within 3 years after endodontic therapy, 57% were lost after 10 years, and 73% after 20 years. Generally, the cusp most prone to fracture was the lingual one, and lingual fractures caused significantly more damage to the periodontal tissues than did facial or total crown fractures. The severity of periodontal damage increased with posterior location of the tooth. By far the most serious failures, irrespective of the cavity type, were found for the upper second molar, as 10 of 29 fractures led to extraction. It is concluded that amalgam, especially in MOD cavities, is an unacceptable material for restoration of endodontically treated posterior teeth if used without cuspal overlays.     

In vivo fractures of endodontically treated posterior teeth restored with amalgam

The cumulative survival rate (retention of both cusps) and the fracture pattern of 1639 endodontically treated posterior teeth were assessed in a retrospective study. All teeth had an MO/DO or an MOD cavity restored with amalgam without cuspal overlays. The 20-year survival rate of teeth with an MO/DO cavity was markedly higher than that of teeth with an MOD cavity. The lowest survival rate was found for the upper premolars with an MOD cavity: 28% of these teeth fractured within 3 years after endodontic therapy, 57% were lost after 10 years, and 73% after 20 years. Generally, the cusp most prone to fracture was the lingual one, and lingual fractures caused significantly more damage to the periodontal tissues than did facial or total crown fractures. The severity of periodontal damage increased with posterior location of the tooth. By far the most serious failures, irrespective of the cavity type, were found for the upper second molar, as 10 of 29 fractures led to extraction. It is concluded that amalgam, especially in MOD cavities, is an unacceptable material for restoration of endodontically treated posterior teeth if used without cuspal overlays.     

Restoration and reinforcement of endodontically treated teeth with a polyethylene ribbon and prefabricated fiberglass post

In the past it was considered appropriate to place a cast post and core in every pulpless tooth without regard to the remaining supportive tooth structure present. Recent research and the advent of adhesive bonding techniques have caused clinicians to reevaluate their restorative protocol. This article reviews the current literature with regard to restoration of the endodontically treated tooth and presents a method for restoration and reinforcement utilizing a combination of polyethylene ribbon and a prefabricated fiberglass post.