In vitro endotoxin penetration of coronally unsealed endodontically treated teeth

Periapical health related to the quality of root canal treatment in a Belgian population

AIM

The aim of this study was to collect data on the prevalence and technical standard of root canal treatment as well as the prevalence of apical periodontitis in Belgium.

METHODOLOGY

The panoramic radiographs of 206 Belgian adults attending the Dental School of the University Hospital of Gent were examined for endodontic treatment, periapical conditions and coronal restorations.

RESULTS

Of the 4617 teeth examined, 6.8% were endodontically treated. Periapical radiolucencies were found in 6.6% of all teeth and in 40.4% of the endodontically treated teeth. More than half of the root-filled teeth (56.7%) were scored inadequate on the basis of a criterion evaluating the level of the root canal filling.

CONCLUSION

The endodontic treatment need of this Belgian subpopulation was great and the technical standard of root canal treatment disappointing. The findings indicate that there is still a substantial need for postgraduate endodontic education in Belgium and a need for specialists in endodontology.

Bacterial leakage versus dye leakage in obturated root canals

AIM

The aim of this study was to compare in vitro bacterial and dye leakage tests, commonly used to determine the seal of root canal fillings.

METHODOLOGY

Ninety-six single-rooted teeth had their crowns removed at the cemento-enamel junction and their roots instrumented to ISO size 60 within 1 mm of the apex. Three groups of 30 roots were obturated by lateral condensation using gutta-percha and one or other of the sealers. AH26, Ketac Endo, or Roth's 801 sealer. Three roots were used as negative controls and three roots as positive controls. The roots were then exposed at their coronal end first for 38 days to soy broth containing Staphylococcus epidermidis and thereafter for 48 h to basic fuchsin. Bacterial leakage was recorded when the challenging organism could be recovered from the apical end. Dye leakage was checked by microscopy of transverse sections of the apical tip at the end of the experiment.

RESULTS

For the bacterial experiment, there was no significant difference amongst the three sealer groups. The dye experiment showed significantly greater leakage in the AH26 compared to the Ketac Endo group. No correlation between the results of the two tests could be seen.

CONCLUSIONS

The results of this study suggest that the molecular size of the penetrating agent may not be the relevant parameter when attempting to determine an appropriate test for the sealability of root canal fillings.

Assessment of apical and coronal root canal seals using contemporary endodontic obturation and restorative materials and techniques

AIM

The purpose of this study was to evaluate the sealing ability of two contemporary endodontic obturation and restorative techniques and materials.

METHODOLOGY

Seventy-nine extracted human single-rooted teeth were distributed randomly in two experimental groups of 36 and 37 specimens (groups 1 and 2, respectively), one group of three positive controls and one of three negative controls. The teeth were radiographed preoperatively, accessed, and instrumented. After smear layer removal, the teeth in group 1 were obturated using the System B and Obtura and were restored coronally with Core Paste using Tenure as a bonding agent. The teeth in group 2 were obturated using the Microseal technique and were restored coronally with amalgam using Panavia 21 as a bonding agent. All teeth in groups 1 and 2 were coated with three layers of nail varnish on all of their surfaces apart from the apical 4.0 mm and the coronal area above the cemento-enamel junction. The positive control teeth were obturated, restored coronally and completely coated with varnish, whereas the negative control teeth were not obturated, restored coronally, nor coated with varnish. The teeth were radiographed postoperatively and retained in saline solution for 10 days. For the next 10 days they were submerged in India ink. Subsequently all teeth were demineralized, dehydrated and rendered transparent. Dye penetration was measured using a stereomicroscope.

RESULTS

All materials and techniques provided minimal to zero dye penetration, apart from one specimen in the Core Paste group that showed 4.0 mm of dye penetration. The Wilcoxon rank sum test and t-test showed no statistically significant differences and all materials and techniques tested presented with a high degree of acceptability.

CONCLUSIONS

It was concluded that these contemporary techniques and materials provide equally good results, but long-term studies are needed for outright inferences to be drawn relative to their clinical performance.

Coronal leakage: endotoxin penetration from mixed bacterial communities through obturated, post-prepared root canals

Coronal leakage has been considered as one of the major causes of failure in root canal treatment. Bacteria have been shown to penetrate the root canal obturating materials and influence the periapical tissues. Endotoxin, a component of Gram-negative bacteria, is a potent inflammatory agent and may be able to penetrate obturating materials faster than bacteria. This in vitro study examined the possible penetration of post-prepared canals by endotoxin and bacterial cells derived from mixed bacterial communities. Results showed that both bacteria and endotoxin were able to penetrate the obturating materials in post-prepared canals; however, endotoxin penetration was faster than bacterial. If one speculates that a similar sequence of events occurs clinically, then such a rapid penetration of endotoxin could lead to an early periapical reaction, with subsequent treatment failure and need for retreatment or periapical surgery. The need for an immediate and proper coronal restoration after root canal treatment is therefore reinforced.

An in vitro study of coronal microleakage in root-canal-treated teeth restored by the post and core technique

The aims of this study were to compare coronal microleakage around cast and prefabricated post and cores and to examine the coronal seal achieved by temporary post crowns. Thirty extracted, single-rooted, human teeth were prepared chemomechanically, root filled with gutta-percha and sealer and prepared for a standard post. Three groups, each of 10 teeth, were restored with either: (i) cast post and cores cemented with zinc phosphate cement; (ii) prefabricated posts and composite cores cemented with a composite luting cement; or (iii) temporary post crowns cemented with a temporary zinc oxide-eugenol cement. The teeth were thermocycled and placed in Indian ink for 1 week, then demineralized and rendered transparent. Linear coronal dye penetration around the posts was measured and recorded. Results indicated that while cast post and cores and prefabricated posts and composite cores produced a good seal, leakage was significantly greater with temporary post crowns (P < 0.05). It is concluded that to prevent re-infection of the root canal system, it may be preferable to restore the tooth immediately with a prefabricated post and composite system rather than place a temporary post crown and subsequently a cast post and core.

Effect of root canal contents on healing of teeth with dentin-bonded resin composite retrograde seal

Healing results were compared among 551 infected roots apically sealed with a dentin-bonded resin composite (Gluma-Retroplast). These roots contained either 1) root filling to apex after resection, 2) insufficient root filling, or 3) empty root canals with necrotic pulp remnants. At 2- to 4-yr follow-up, complete bone healing was found to be 92%, 85%, and 81% in groups 1, 2, and 3, respectively. The results from groups 1 and 3 were significantly different, and the results from group 2 did not differ significantly from that of groups 1 or 3. Reasons for "Failures" were found to be mainly loose filling or uncovered canal. After 21 roots classified as "Failures" were reoperated, 76% of these showed "Complete Healing" after 1 yr.

Periapical status, quality of root canal fillings and estimated endodontic treatment needs in an urban German population

The objective of this study was to determine the periapical status and the quality of root canal fillings and to estimate the endodontic treatment needs in a German population. Clinical and radiographic data and the operative procedures performed were evaluated on 323 patients coming to a dental surgery in Stuttgart, Germany, in 1993. In 182 individuals at least one tooth exhibited a root canal filling, a necrotic pulp or an irreversible pulpitis. Out of the 7897 teeth examined, 215 (2.7%) had a root canal treatment (category A), 122 being non-endodontically treated (1.5%) did not respond to the sensitivity test (category B) and 53 (0.7%) were diagnosed as having irreversible inflamed pulp tissue (category C). The prevalence of teeth associated with radiographic signs of periapical pathosis was 61% in the group of root canal filled teeth and 88% in the group of pulpless and non-endodontically treated teeth. Using the level and the density of the root canal filling as criteria for evaluating the technical standard, only 14% of the endodontic treatments of non-apicectomized teeth were qualified as adequate. The minimal endodontic treatment need is 2.3% related to all examined teeth when the root canal filled teeth with clinical symptoms of periapical periodontitis (category A) and those of categories B and C are included. The real endodontic treatment need is suggested to be larger when considering that the technical quality of the obturation is poor in most symptomless endodontically treated teeth associated with a periapical lesion. In the case of retreatment of these teeth, the endodontic treatment need would then be calculated at 3.7%.

An in-vitro study of smear layer removal and microbial leakage along root-canal fillings

The objective of this study was to determine the effect of removal of the smear layer on canal obturation as measured by penetration of bacteria from a coronal direction. Fifty-four extracted human teeth were decoronated and instrumented in a uniform manner. Following instrumentation the root canals of 20 teeth were rinsed with 17% EDTA and 5.25% NaOCl to remove the smear layer before obturation. A second group of 20 teeth were flushed with NaOCl alone. The teeth of both groups were obturated with Thermafil plastic carriers and Roth's sealer. The root canals of another 10 teeth, five rinsed with EDTA and five without, were obturated with Thermafil without sealer. Two teeth serving as positive controls were instrumented but not obturated, while another set of two were sealed coronally and apically to serve as negative controls. The root surface of each tooth was sealed with nail varnish. A small chamber was thoroughly sealed around the coronal aspect of each tooth so that bacteria placed therein could move only through the obturated canal space. Each tooth was placed in a test tube containing sterile trypticase soy broth (TSB). An inoculum of Proteus vulgaris in TSB was placed in each coronal chamber at five day intervals and daily observations were made for bacterial growth in the apical reservoir for 21 days. Both positive control teeth showed bacterial penetration after 24 h. Neither of the two negative control teeth demonstrated penetration for the duration of the study. The frequency of bacterial penetration through teeth obturated with intact smear layer (70%) was-significantly greater than that of teeth from which the smear layer had been removed (30%) P < 0.05. All but one tooth obturated without sealer exhibited bacterial penetration, irrespective of the presence or absence of smear layer. Removal of the smear layer enhanced sealability as evidenced by increased resistance to bacterial penetration.