Evaluation of Electronic Method in Determining the Root Canal Length in Teeth of Dogs

The aim of this study was to investigate the efficacy of electronic apex locators to determine the root canal length in teeth of dogs. For this purpose, APIT and ENDOSONIC units, which are third generation apex locator devices, were used to identify the root length in 58 teeth (82 roots). The electronic method was compared to radiographic and tactile sense methods. The results showed that APIT and ENDOSONIC devices were ineffective when used to determine the root canal length in 2–3 year-old dogs. A beep indicating the canal depth was heard in only two of 82 (2.4%) canals. The digital-tactile sense method with radiographic confirmation is more appropriate for root length measurement than the electronic method during endodontic therapy in dogs.

Effect of the pro-resolution lipid mediator Resolvin E1 (RvE1) on pulp tissues exposed to the oral environment

AIM

To evaluate the effects of topical Resolvin E1 (RvE1) application on infected dental pulps.

METHODOLOGY

Forty-two male Wistar rats (n = 6 per three groups/and two time periods) were used. To induce inflammation, pulps in mandibular right first molars were accessed and then left exposed to the oral environment for 24 h. After this period, topical medication with a corticosteroid/antibiotic blend, or RvE1, or its vehicle (Ethanol 0.1%) was directly applied onto the pulp tissue and teeth were restored with silver amalgam. The effects of the protocols were evaluated histologically and compared with control pulps not exposed to the oral environment. The inflammatory changes after 24 and 72 h were assessed through a scoring method and analysed using the Kruskal-Wallis test followed by Dunn's. Differences were considered significant if P < 0.05 (CI = 95%).

RESULTS

Ethanol and corticosteroid/antibiotic treatment were not effective in arresting severe inflammatory alterations of exposed pulps at 24 and 72 h (P < 0.05, CI = 95%). At both time periods, RvE1 treatment led to a reduction of tissue cellularity and extent of inflammation, whose changes were not different from control pulps (P > 0.05, CI = 95%).

CONCLUSIONS

A protective role for RvE1 in pulp inflammation was observed even in the presence of contamination, suggesting that it may be a candidate for a novel therapeutic strategy for conservative dental pulp treatment.

Use of cone beam computed tomography in the diagnosis, planning and follow up of a type III dens invaginatus case

AIM

To present the case of a maxillary left lateral incisor with Oehlers' type III dens invaginatus in which cone beam computed tomography (CBCT) was used as an adjunctive resource in the diagnosis as well as in the planning and 2-year follow-up of the nonsurgical/surgical treatment.

SUMMARY

The tooth had two root canals: a primary (main) canal with vital pulp that appeared to be closed apically and an invaginated canal that was necrotic, wide-open at the portal of exit and associated with a large chronic periapical lesion extending to the apex of the maxillary left central incisor. Radiographic tracking of a sinus tract in the labial gingiva of the affected tooth with a gutta-percha point revealed its origin to be the invagination. The CBCT scans revealed that the periapical radiolucency was significantly larger than seen radiographically as well as an increased thickness of the buccal cortical plate. Conventional root canal treatment of the primary canal was undertaken. As nonsurgical access to the invaginated canal was not possible, endodontic surgery was performed for curettage of the lesion, root-end cavity preparation using ultrasonic tips and root canal filling with white mineral trioxide aggregate (MTA). CBCT scanning after 17 months and clinical and radiographic follow-up after 24 months revealed complete periapical repair and absence of symptoms.

KEY LEARNING POINTS

The combination of nonsurgical and surgical treatments produced periapical repair in a tooth with type III dens invaginatus with two root canals. CBCT may aid the diagnosis as well as the management plan and follow-up of teeth with this developmental anomaly.

The effect of head-fractioned teletherapy on pulp tissue

AIM

To evaluate the early and delayed effects of fractioned teletherapy (radiotherapy) on the dental pulps of rats using Co(60).

METHODOLOGY

In group 1 - rats (n = 15) were subjected to fractioned teletherapy by 30 daily sessions fractioned in doses of 200 cGy day(-1), totaling 60 Gy and the rats were killed immediately after the final dose of irradiation; group 2 - same protocol but killed 30 days following the final irradiation dose; groups 3 (n = 7) and 4 (n = 8) - formed controls without irradiation. Following perfusion, the left mandible of each rat was dissected and processed for histopathology. Serial sections (5 microm) were obtained and stained with HE or picrosirius. Observations were recorded for the coronal pulp tissue. A blinded observer evaluated HE sections using pre-defined indices of inflammation, nuclear alterations and extracellular matrix (ECM) hyalinization. Images of sections stained with picrosirius were converted to black and white for analysis by image-pro plus; areas in black (collagen) were measured as percentage area. The pulps of mandibular incisors of the specimens prepared for transmission electron microscopy (TEM) were subjected to descriptive analysis. Magnifications of 6300 and 10000 x were used to observe 10 pulp fibroblasts from each group.

RESULTS

No inflammatory reactions or modification of the ECM status were found (P = 0.428) in any specimens. The collagen content also displayed no significant changes (P = 0.067) as a result of treatment. Groups 1 and 2 displayed significantly more nuclear alterations than the control groups (P < 0.05). The bubble-like aspect was more pronounced in group 1, and the bubbles looked smaller in group 2. The ECM showed no differences in the hyalinization status and there were no differences in the collagen area within the pulps. Under TEM, the pulp fibroblasts in group 1 displayed nuclear alterations that resembled circular, oval or elongated perforations; perforations also appeared in the cytoplasm.

CONCLUSION

Fractioned teletherapy is capable of producing nuclear alterations in the dental pulp tissue of rats.

Deformation and fracture of RaCe and K3 endodontic instruments according to the number of uses

AIM

To evaluate, by scanning electron microscopy, the deformation and fracture of NiTi RaCe and K3 size 25, 0.04 taper instruments.

METHODOLOGY

Ten sets of instruments from RaCe and K3 NiTi rotary systems were used to prepare 100 simulated canals in epoxy resin blocks with 20 or 40 degree curvatures beginning 8 or 12 mm from the orifice. Each instrument set was used to prepare five simulated canals using a crowndown technique. The size 25, 0.04 taper instruments were analysed by SEM when new and again after each use. Three observers scored images of the instruments after each use for distortion of the spirals (no distortion, distortion of one spiral or distortion of more than one spiral), wear (no wear, small, moderate or severe wear) and fracture (yes or no). Two-way anova was used to analyse differences between instruments for distortion and wear; Fisher's exact test looked for differences related to fracture of instruments.

RESULTS

No fractures occurred with K3 instruments, whereas six RaCe instruments fractured (P = 0.005). A statistically significant difference occurred between RaCe and K3 instruments in terms of distortion of spirals and surface wear (P < 0.001). Distortion of spirals and wear increased with progressive use of RaCe instruments, whereas K3 instruments remained relatively undamaged after their fifth use. The simulated canals with smaller radii of curvature were positively associated with fracture of RaCe instruments.

CONCLUSIONS

A significant difference was found between RaCe and K3 in terms of deformation and fracture of size 25, 0.04 taper instruments; K3 instruments had more favourable results.

Internal apical resorption and its correlation with the type of apical lesion

AIM

To determine the presence of various periapical pathologies and their association with the presence and extent of internal apical inflammatory root resorption in human teeth.

METHODOLOGY

A total of 75 root apices from extracted teeth with periapical lesions were examined. Semi-serial sections of soft tissue lesions were stained with HE. The lesions were classified as non-cystic or cystic, and according to the degree of abscess severity: 0, 1, 2 or 3. The apices were reduced to 3 mm in length and longitudinally cut so that the internal aspect could be analyzed under scanning electron microscopy (SEM). Internal root resorption was also classified as 0, 1, 2 or 3 according to the extent of the resorbed area. Additionally, six vital teeth were used as a control.

RESULTS

Non-cystic lesions with severe abscesses were the most common finding (70.7%), while 20% of the lesions were cystic (4% little or no abscess; 16% severe abscesses). Non-cystic lesions with little or no abscess comprised 9.3% of the sample. Of the root canals containing periapical lesions, 48% had internal apical resorption in more than half of the area, while 25.3% of the sample had no internal resorption. Resorption degree 1 was identified in 12% of the cases, and 14.7% showed resorption degree 2. The control group displayed significantly less internal resorption than the test groups.

CONCLUSIONS

Most periapical lesions (86.7%), whether cystic (16.0%) or non-cystic (70.7%), showed large collections of acute inflammatory cells. Apical internal resorption was present in 74.7% of roots and was associated with periapical lesions. There was no correlation between internal apical resorption and the histological diagnosis of the lesions.

Morphometric analysis of shank-to-flute ratio in rotary nickel-titanium files

AIM

To evaluate the shank-to-flute ratio in rotary nickel-titanium (Ni-Ti) instruments.

METHODOLOGY

The cutting portion of 15 size 30 Ni-Ti rotary instruments, ProFile.04, ProFile.06, Pow R.02, Pow R.04 and Quantec series 2000, were examined. The handles of the instruments were fixed to a bench and supported by a removable resin base. The cutting portion was then manually abraded with abrasive strips along one aspect of their length. All instruments were fixed in a stub that permitted the adaptation and inspection of six instruments at the same time. A scanning electron microscope (SEM; Phillips model XL 20; Eindhmoven, the Netherlands) at x60 magnification was used to collect cross-sectional measurements of the shank and the flutes at the first, third and fifth flutes from the tip. The software autocad 2000 was used to measure these areas.

RESULTS

The shank percentage value was, on average, equal to or greater than the flute percentage value at the sites analyzed. A regular and proportional pattern of increase of shank and flute measurements, as well as the ratio between them, was preserved. There was no significant difference between instruments and between flute sites on the same instrument (P > 0.05). However, the Quantec instruments had a flute area twice the flute area of the other instruments.

CONCLUSIONS

The instruments had a shank percentage measurement value equal to or greater than the flute percentage value; the cross-sectional shank-to-flute ratio was preserved. The instruments had similar shank areas, but the flute area of the Quantec instruments was twice their shank area; i.e. the design of the Quantec files provides longitudinal reinforcement by means of a gain in flute area.

Dissolution of pulp tissue by aqueous solution of chlorhexidine digluconate and chlorhexidine digluconate gel

AIM

To evaluate the activity of various root canal irrigants on bovine pulp tissue.

METHODOLOGY

The irrigants tested were: 0.5, 1.0 and 2.5% sodium hypochlorite; 2% aqueous solution of chlorhexidine digluconate; 2% chlorhexidine digluconate gel (Natrosol); and distilled water as control. Bovine pulp fragments were weighed and placed in contact with 20 mL of each tested substance in a centrifuge at 150 r.p.m. until total dissolution. Dissolution speed was calculated by dividing pulp weight by dissolution time. Statistical analysis was performed using the Kruskal-Wallis test.

RESULTS

Distilled water and both solutions of chlorhexidine did not dissolve the pulp tissue within 6 h. Mean dissolution speeds for 0.5, 1.0 and 2.5% sodium hypochlorite solutions were 0.31, 0.43 and 0.55 mg min(-1), respectively. The solvent ability of chlorhexidine solutions was similar to that of distilled water. The results for sodium hypochlorite solutions, chlorhexidine solutions and distilled water were statistically different (P>0.01).

CONCLUSIONS

Both chlorhexidine preparations and distilled water were not able to dissolve pulp tissue. All sodium hypochlorite solutions were efficient in dissolving pulp tissue; the dissolution speed varied with the concentration of the solution.

Comparative in vivo analysis of the sealing ability of three endodontic sealers in post-prepared root canals

AIM

To compare the sealing ability of the endodontic sealers AH Plus, Sealer 26 and Endofill in premolar teeth of dogs exposed to the oral cavity after post-preparation.

METHODOLOGY

Forty teeth with two canals each underwent root canal cleaning and shaping. Before filling, the canals were randomly distributed into three groups according to the sealer to be used: Group 1 - AH Plus; Group 2 - Sealer 26; and Group 3 - Endofill (Dentsply, Indústria e Comércio Ltda.). Immediately after filling, the gutta percha and sealer were partially removed from the canals, leaving material only in the apical third of the root. The teeth were temporarily sealed with glass ionomer sealer for 72 h to ensure setting. The coronal seal was then removed and the canals were exposed to the oral cavity for 45 days. The animals were euthanased and their mandibles and maxillae were removed. After abundant irrigation with distilled water, the canals were dried and filled with India ink. The teeth were sealed again for 96 h before extraction. The roots of the extracted premolars were separated and stored in labelled test tubes. The roots were cleared and the extent of dye penetration was measured with a 20x stereoscopic magnifying lens.

RESULTS

Statistical analysis revealed that there were significant differences between the sealers studied (P < 0.001). Means for the extent of dye penetration for AH Plus, Endofill and Sealer 26 were, respectively, 0.13, 2.27 and 3.08 mm.

CONCLUSIONS

After 45 days exposure to the oral cavity, none of the sealers was capable of preventing leakage and coronal dye penetration. There were significant differences between the sealers studied, in terms of mean dye penetration.

Prevalence of different periapical lesions associated with human teeth and their correlation with the presence and extension of apical external root resorption

AIM

The aim of this study was to determine the prevalence of various periapical pathologies and their association with the presence and extent of apical external inflammatory root resorption in human teeth.

METHODOLOGY

One hundred and four root apices from extracted teeth with periapical lesions were examined. Semi-serial sections of soft tissue lesions were stained with HE. The lesions were classified as noncystic or cystic, each with different degrees of acute inflammation: 0, 1, 2 and 3, increasing in severity. The root apices were analysed by SEM. External root resorption was classified according to site, as periforaminal or foraminal, and the extension of the resorbed area graded in increasing area as 0, 1, 2 or 3.

RESULTS

Cysts accounted for 24.5% of the samples, 84% of which were associated with marked inflammation. The most prevalent diagnosis was noncystic periapical abscess with varying degrees of severity (63.7%). Periapical granuloma was not a frequent finding. SEM analysis showed that 42.2% of the root apices had periforaminal resorption extending over 50% of their circumference. When the foraminal resorption was evaluated, 28.7% had resorption affecting >50% of the periphery. Only 8.9% of the samples showed no periforaminal or foraminal resorption.

CONCLUSIONS

In the sample of extracted teeth investigated, 24.5% of the periapical lesions were cysts. Most periapical lesions (84.3%) displayed acute inflammation, whether cystic or not. Periforaminal resorption was present in 87.3% of the cases, and foraminal resorption in 83.2%. Periforaminal and foraminal resorptions were independent entities. There was no association between external root resorption and the nature of the periapical lesions.