Contrast-enhanced nano-CT reveals soft dental tissues and cellular layers.

AIM: To introduce a methodology designed to simultaneously visualize dental ultrastructures, including cellular and soft tissue components, by utilizing phosphotungstic acid (PTA) as a contrast-enhancement agent. METHODOLOGY: Sound third molars were collected from healthy human adults and fixed in 4% buffered paraformaldehyde. To evaluate the impact of PTA in concentrations of 0.3%, 0.7% and 1% on dental soft and hard tissues for CT imaging, cementum and dentine-pulp sections were cut, dehydrated and stained with immersion periods of 12, 24 h, 2 days or 5 days. The samples were scanned in a high-resolution nano-CT device using pixel sizes down to 0.5 µm to examine both the cementum and pulpal regions. RESULTS: Dental cementum and periodontium as well as odontoblasts and predentine were made visible through PTA staining in high-resolution three-dimensional nano-CT scans. Different segments of the tooth required different staining protocols. The thickness of the cementum could be computed over the length of the tooth once it was made visible by the PTA-enhanced contrast, and the attached soft tissue components of the interior of the tooth could be shown on the dentine-pulp interface in greater detail. Three-dimensional illustrations allowed a histology-like visualization of the sections in all orientations with a single scan and easy sample preparation. The segmentation of the sigmoidal dentinal tubules and the surrounding dentine allowed a three-dimensional investigation and quantitative of the dentine composition, such as the tubular lumen or the ratio of the tubular lumen area to the dentinal surface. CONCLUSION: The staining protocol made it possible to visualize hard tissues along with cellular layers and soft tissues in teeth using a laboratory-based nano-CT technique. The protocol depended on both tissue type and size. This methodology offers enhanced possibilities for the concomitant visualization of soft and hard dental tissues.

Prediction of periapical status and tooth extraction.

AIM: To describe and analyse risk factors associated with prediction of periapical status, assessed using the full-scale Periapical Index (PAI) supplemented with extraction as outcome variable. METHODOLOGY: In 1997-1998, 616 randomly selected individuals from Aarhus County, Denmark, underwent a full-mouth radiographic survey. All 616 were re-invited in 2003-2004 and in 2008-2009, when 473 and 363 persons, respectively, consented and attended a new radiographic examination. The study population of the present investigation included 330 persons who had participated in all three examinations, and 143 persons who had participated in the first and second examination only. Using the full-mouth radiographic survey and interview information, the following variables were assessed: on person level - age, gender, smoking habits and number of teeth; on tooth level - presence of tooth, PAI, root filling, caries, marginal bone level, restoration, jaw and tooth group. The outcome variable was the 5 score PAI supplemented with extraction. The observation period was 5 years. Ordered logistic regression analyses were carried out for root filled and non-root filled teeth separately. The Regional Committee of Ethics approved the study. RESULTS: For both root filled teeth and non-root filled teeth, the baseline PAI score was the most important predictive factor of periapical status and extraction (P < 0.0001). Non-root filled teeth had in general a better outcome than root filled teeth. However, in non-root filled teeth, several other factors had a significant influence on the outcome, and the risk estimates were larger and showed a more pronounced variation between the different categories of predictive factors. For root filled teeth few variables, other than baseline PAI score, influenced the outcome significantly. CONCLUSION: The full-scale PAI was the strongest predictive factor of periapical status or extraction even when adjusted for additional factors, such as marginal bone level. A high baseline PAI score increased the risk for an impaired outcome. The large difference in risk estimates for non-root filled compared to root filled teeth documents the importance of separate analyses/studies for identification and quantification of predictive factors associated with periapical status and extraction of a tooth.

Prognostic value of the full-scale Periapical Index.

AIM: To evaluate whether the full-scale Periapical Index (PAI) can predict the periapical status over time in nonroot filled and root filled teeth. METHODOLOGY: Full-mouth radiographic surveys of a random sample from a general population were performed in 1997, 2003 and 2008. The present investigation included 330 persons who participated in all three examinations and 143 persons who participated in the first and second examination. At each examination, the presence or absence of a tooth and of a root filling was recorded, and a PAI score (1-5) was assigned to all teeth. Retreatment of a root filling was recorded for root filled teeth. Statistical analysis was carried out using ordinal logistic regression and logistic regression and computed as Wald's tests. RESULTS: At baseline, nonroot filled teeth had lower PAI scores than root filled teeth (P < 0.0001). A high baseline PAI increased the risk of extraction for both root filled (P < 0.001) and nonroot filled teeth (P < 0.001). At 5-year follow-up, PAI scores were higher when baseline PAI scores had been higher. The overall pattern for root filled and nonroot filled teeth was similar, however, the differences were statistically significant (P < 0.001). In particular, the follow-up PAI score for nonroot filled teeth with baseline PAI score 1 or 2 was significantly lower than that of root filled teeth (P < 0.001). For root filled teeth with baseline PAI score 3, 4 or 5, the trend was reversed as they overall had slightly lower PAI scores at follow-up (P = 0.023). CONCLUSION: Repeated radiographic assessments of teeth using the full-scale PAI reveal that each of the five scores had distinct prognostic value for the course of periapical disease over a 5-year period for both nonroot filled and root filled teeth.

Sealing ability of mineral trioxide aggregate, glass ionomer cement and composite resin when repairing large furcal perforations.

OBJECTIVE: To evaluate the sealing ability of different repair materials and the pathway of bacterial penetration after closure of large pulp chamber floor perforations. MATERIALS AND METHODS: Perforations were made in the furcation area of extracted human molars and sealed with either mineral trioxide aggregate (MTA), glass ionomer cement or resin composite. The bacterial leakage method was used with Enterococcus faecalis as microbial tracer. The time of leakage (in days) was recorded for each specimen. Statistical analysis of bacterial leakage was performed using the survival analysis and pairwise comparison of groups. A p-value less than 0.05 was considered statistically significant. Leaking specimens were prepared and inspected for the presence of bacteria by a scanning electron microscope (SEM). RESULTS: The percentage of leaking samples was significantly higher in resin composite than in the other groups and the negative control group (p<0.05). SEM inspection revealed the presence of bacteria in all leaking specimens. Bacteria were observed along the filling-dentine interface as well as in dentinal tubules at some distance from the filling. CONCLUSIONS: The resin composite material leaked significantly more than the MTA and glass ionomer cements when used to repair large furcation perforations. Bacteria could penetrate into dentine even at a distance from the perforation filling.

A laboratory assessment of coronal bacterial leakage in root canals filled with new and conventional sealers.

AIM: To evaluate the resistance to ex vivo bacterial leakage over a 40-day period of root canal fillings with five new root canal sealers: RC Sealer, Epiphany, EndoREZ, GuttaFlow and Acroseal, compared with Apexit, AH Plus and RoekoSeal. METHODOLOGY: One hundred and forty-four single rooted human teeth were divided randomly into eight test (n = 15) and two control groups (n = 12). The root canals were filled using a single cone technique with gutta-percha except in the Epiphany and EndoREZ groups. These were filled with Resilon and resin-coated gutta-percha, respectively. The gutta-percha surface of the GuttaFlow group was coated with an experimental primer prior to filling. Positive controls were filled with gutta-percha without sealer and tested with bacteria, whereas negative controls were sealed with wax to test the seal between the chambers. Filled roots were incorporated in a split chamber model system using Streptococcus mutans as a microbial marker. Leakage was assessed for turbidity of the broth in the lower chamber every day for 40 days. Survival analysis was performed using the Kaplan-Meier product limit method and event times were compared using the Log-rank test (alpha = 0.05). RESULTS: Epiphany, GuttaFlow with test primer and Apexit prevented leakage significantly better than AH Plus, RC Sealer, RoekoSeal, EndoREZ and Acroseal (P < 0.05). None of the specimens in the AH Plus, RC Sealer, RoekoSeal and EndoREZ groups resisted bacterial penetration for 40 days. CONCLUSION: The new sealers, Epiphany and GuttaFlow with primer, along with Apexit, showed better resistance to bacterial penetration than the other new or traditional sealers tested.

Possible role of the adhesin ace and collagen adherence in conveying resistance to disinfectants on Enterococcus faecalis.

INTRODUCTION: This study aimed to evaluate whether the presence of the ace gene and Ace-mediated binding to collagen confers on Enterococcus faecalis resistance against common endodontic disinfectants. METHODS: Isogenic strains of E. faecalis: OG1RF (wild-type) and TX5256 (ace insertion mutant of OG1RF) were grown in brain-heart infusion broth at 46 degrees C overnight. Standardized bacterial suspensions were pretreated for 1 h either with acid-soluble collagen or acidified phosphate-buffered saline (ac-PBS). Bacteria were challenged with chlorhexidine digluconate (CHX), iodine potassium-iodide (IKI), sodium hypochlorite (NaOCl), and calcium hydroxide [Ca(OH)(2)]. Samples were removed at 1, 3, and 6 h, and cultured on Todd-Hewitt agar plates. Colonies were counted, the absolute values were log transformed, and the data were statistically analyzed using Fisher's least significant differences test and t-test. RESULTS: OG1RF was more resistant than TX5256 to IKI, NaOCl, and Ca(OH)(2) (P < 0.05). Collagen-exposed OG1RF was more resistant than the ac-PBS-pretreated OG1RF against CHX at 3 h and against IKI at 1 h (P < 0.05); no significant difference was found against NaOCl. As expected, the ace mutant strain, TX5256, pretreated with collagen or ac-PBS did not differ significantly in viability when challenged with CHX, IKI, and NaOCl. An unexpected result was found for Ca(OH)(2): collagen-pretreated OG1RF and TX5256 were both more susceptible than ac-PBS-pretreated OG1RF and TX5256, respectively (P < 0.05). CONCLUSION: The presence of the ace gene confers resistance against IKI, NaOCl, and Ca(OH)(2) on E. faecalis. Exposure to collagen makes the wild-type bacterium more resistant against CHX and IKI; however, exposure to collagen apparently decreases resistance to Ca(OH)(2).

Bacterial penetration along different root canal filling materials in the presence or absence of smear layer.

AIM: To study the effect of the smear layer on the penetration of bacteria along different root canal filling materials and to examine the dentine/sealer and sealer/core material interfaces for the presence of bacteria. METHODOLOGY: A total of 110 human root segments were instrumented to size 80 under irrigation with 1% sodium hypochlorite. Half of the roots were irrigated with a 5-mL rinse of 17% EDTA. Roots with and without smear layer were filled with gutta-percha (GP) and AH Plus sealer (AH), GP and Apexit sealer (AP), or RealSeal cones and sealer (RS). Following storage in humid conditions at 37 degrees C for 7 days, the specimens were mounted into a bacterial leakage test model for 135 days. Survival analyses were performed to calculate the median time of leakage and log-rank test was used for pairwise comparisons of groups. The level of significance was set at P = 0.05. Selected specimens were longitudinally sectioned and inspected by scanning electron microscopy for the presence of bacteria at the interfaces. RESULTS: In the presence of the smear layer, RS and AP leaked significantly more slowly than in its absence. In the absence of the smear layer, AH leaked significantly more slowly than RS. SEM results indicated a differential pattern of bacterial penetration among the sealers. CONCLUSIONS: Removal of the smear layer did not impair bacterial penetration along root canal fillings. A comparison of the sealers revealed no difference except that AH performed better than RS in the absence of the smear layer.

Toxicity evaluation of root canal sealers in vitro.

AIM: To compare the toxicity of methacrylate resin-based root canal sealers with sealers based on epoxy resin and silicone by two-well established cell culture methods. METHODOLOGY: Specimens of AH Plus, EndoREZ, RoekoSeal and Epiphany were prepared for direct contact in the Millipore filter diffusion test and as extracts in the MTT assay. Mouse fibroblasts (L929) were used as toxicity targets. Differences in cytotoxicity between fresh and set specimens and between the extracts of root canal sealers were determined by t-test (P < 0.05). RESULTS: In the filter diffusion test, freshly mixed Epiphany and AH Plus were rated severely toxic and RoekoSeal and EndoREZ nontoxic. When set, Epiphany was moderately toxic, whereas AH Plus, RoekoSeal and EndoREZ were nontoxic. Epiphany was significantly more toxic than RoekoSeal and EndoREZ (P < 0.05). In the MTT assay with set specimens, Epiphany was rated severely toxic; AH Plus and RoekoSeal slightly toxic; and EndoREZ nontoxic. Epiphany was significantly more toxic than the other three materials in this test (P < 0.001). CONCLUSION: The multi-methacrylate resin-based (Epiphany) root canal sealer was significantly more toxic to L-929 cells than the silicone-based Roeko Seal and the single methacrylate-based EndoREZ root canal sealers. AH Plus showed intermediate toxicity.

Cytotoxicity of new resin-, calcium hydroxide- and silicone-based root canal sealers on fibroblasts derived from human gingiva and L929 cell lines.

AIM: To assess ex vivo the cytotoxic effects of five new root canal sealers (RC Sealer, Epiphany, EndoREZ, GuttaFlow and Acroseal) and three existing products (AH Plus, RoekoSeal and Apexit) using primary human gingival fibroblasts (HGF) and a mouse fibroblast cell line, L929. METHODOLOGY: Eight samples of each sealer were fabricated in sterile cylindrical Teflon blocks, 4.4 mm diameter and 2 mm height and then divided into two groups, fresh and aged specimens. Extraction of fresh specimens was carried out after setting whilst aged specimens were placed in Petri dishes and kept in a humid chamber at 37 degrees C for 7 days before extraction in cell culture medium using the ratio 1.25 cm(2) mL(-1). Undiluted eluates were used for the dimethylthiazol diphenyltetrazolium bromide (MTT) assay with HGF and L-929. Morphology of HGF cells was also examined by an inverted microscope using undiluted eluates of the sealers. The results were analysed using a two-tailed t-test (alpha = 0.05) between groups. RESULTS: Resin-based (Epiphany and EndoREZ) and calcium hydroxide-based (Apexit and Acroseal) sealers were significantly more cytotoxic than other sealers (P<0.05). However, L929 cells were more sensitive to Apexit and EndoREZ than HGF cells. RC Sealer showed mild cytotoxicity to HGF at both setting times. AH Plus did not exert any cytotoxic effect to HGF and aged specimens appeared to induce cellular proliferation. RoekoSeal and GuttaFlow also demonstrated mild cytotoxicity. GuttaFlow was slightly more cytotoxic to both cultures, especially when tested fresh. CONCLUSIONS: Toxicity varied but RC Sealer and GuttaFlow were the least toxic new sealers.

Short-term antibacterial activity of root canal sealers towards Enterococcus faecalis.

AIM: To investigate the antimicrobial activity of root canal sealers on Enterococcus faecalis, either allowing or avoiding direct contact between sealers and bacteria. METHODOLOGY: Filter paper discs were immersed in standardized E. faecalis suspensions and exposed to freshly mixed sealers (MCS, AH Plus, Grossman's sealer, Sealapex, Apexit) in teflon wells for 30 min, with or without a filter membrane placed between filter paper discs and sealers (membrane-restricted contact test and direct contact test, respectively). After exposure, the filter paper discs were transferred to vials containing phosphate-buffered saline (PBS) and glass beads, and vigorously vortexed. PBS with resuspended bacterial cells was serially diluted and 25 microL droplets were seeded on TSA plates. The plates were incubated in air at 37 degrees C for 24 h and colony-forming units were counted. Using alpha = 0.05 as level for statistical significance, the data obtained were analysed using Student's t-test. RESULTS: In the direct contact test, MCS and AH Plus killed the bacteria to a level below the detection limit. They were followed in decreasing order of efficacy by Grossman's sealer, Sealapex and Apexit. In the membrane-restricted contact test, the sealers ranked: MCS, AH Plus, Grossman's sealer, Apexit and Sealapex, in descending order of antibacterial potency. MCS, AH Plus and Grossman's sealer significantly reduced the number of viable bacteria in both tests. Sealapex and Apexit were not statistically different from control. CONCLUSIONS: MCS, AH Plus and Grossman's sealer were effective in reducing the number of cultivable cells of E. faecalis. Calcium hydroxide-based sealers, Sealapex and Apexit were ineffective in this short-term experiment.

Growth at high pH increases Enterococcus faecalis adhesion to collagen.

AIM: To evaluate the effect of growth at pH levels from 7.1 to 9.5 on the adherence of Enterococcus faecalis to bovine serum albumin (BSA) and collagen type I. METHODOLOGY: Enterococcus faecalis strain A197A was grown in broth of adjusted pHs varying between 7.1 and 9.5. Aliquots of bacterial suspensions were added to wells coated either with BSA or with collagen type I. Bacteria adhering to the surfaces were stained with crystal violet. Spectrophotometric measurements of the dissolved stain were used to assess the number of bacteria adhering to the surfaces. The data obtained were analysed using the Kolmogorov-Smirnov test, Levene's test and Student's t-test, with alpha = 0.05 as the level for statistical significance. RESULTS: The adhesion of E. faecalis to BSA-coated surfaces decreased inversely with alkalinity of the growth medium. The pH 7.1-grown bacteria bound to BSA significantly more than the other BSA groups. On the contrary, the adhesion to collagen type I-coated surfaces of bacteria grown at pH 8.0 and 8.5 was significantly greater than for those grown at pH 7.1. CONCLUSIONS: A minor increase in pH up to 8.5, which may be a consequence of insufficient treatment with alkaline medicaments such as calcium hydroxide, increases the collagen-binding ability of E. faecalis, in vitro. This can be a critical mechanism by which E. faecalis predominates in persistent endodontic infections.

Survival of Enterococcus faecalis in infected dentinal tubules after root canal filling with different root canal sealers in vitro.

AIM: To investigate the ability of different endodontic sealers and calcium hydroxide to kill bacteria in experimentally infected dentinal tubules. METHODOLOGY: Fifty-six human root segments were enlarged to size 2 (ISO size 090) Largo Peeso Reamer. After treatment with 17% EDTA and 5% NaOCl for 4 min each, the specimens were infected with Enterococcus faecalis for 3 weeks. The roots were divided into eight groups and filled with gutta-percha and AH Plus (AH); Grossman's sealer (GS); Ketac-Endo (KE); Apexit (AP); RoekoSeal Automix (RSA); or RoekoSeal Automix with an experimental primer (RP), or calcium hydroxide (CH) only. One group of specimens was left unfilled for control (CT). Following storage in humid conditions at 37 degrees C for 7 days, the root canals were re-established with new sterile Largo size 2. Dentine samples from each canal were then collected using a sterile size 5 (ISO size 150) Largo Peeso Reamer. The number of colony-forming units (CFU) was determined for each sample. RESULTS: The mean log10 CFU in all test groups was significantly lower (P < 0.05) than that in the CT group. Root filling with AH and GS killed bacteria (mean CFU = 0) in the dentinal tubules. The mean log10 CFU for the CH group (0.53) was lower than that of RSA, AP, RP and KE (1.36, 1.40, 1.46 and 1.94, respectively), but only the difference between the CH and the KE groups was statistically significant (P < 0.05). CONCLUSION: Root fillings in vitro with gutta-percha and AH or GS were effective in killing E. faecalis in dentinal tubules. Other endodontic sealers, as well as CH, were less effective.

Yeasts in apical periodontitis.

Microbiological reports of apical periodontitis have revealed that yeasts can be isolated from approximately 5-20% of infected root canals. They occur either in pure cultures or together with bacteria. Almost all isolated yeasts belong to the genus Candida, and the predominant species is C. albicans. Pheno- and genotypic profiles of C. albicans isolates show heterogeneity comparable with those of isolates from other oral sites. C. albicans expresses several virulence factors that are capable of infecting the dentin-pulp complex, including dentinal tubules. This causes, consequentially, an inflammatory response around the root apex, which suggests a pathogenic role for this organism in apical periodontitis. Yeasts are particularly associated with persistent root canal infections that do not respond favorably to conservative root canal therapy. This may be due to the resistance of all oral Candida species against a commonly used topical medicament, calcium hydroxide. However, other antimicrobial agents may offer alternative therapeutic approaches and improve the treatment of these persistent cases of apical periodontitis.

Healing of apical periodontitis after endodontic treatment: a comparison between a silicone-based and a zinc oxide-eugenol-based sealer.

AIM: To assess the treatment results up to 1 year after endodontic treatment of apical periodontitis using a silicone-based sealer in comparison with Grossman's sealer, and to compare the results at 3 months after treatment with the 12-month follow-up to assess the prognostic value of a 3-month control. METHODOLOGY: A total of 199 teeth were treated at three centres. The sealer was randomly chosen at the time of filling. Treatment results were evaluated clinically and radiographically 3 and 12 months after root-canal filling. The periapical status was evaluated using the periapical index (PAI). RESULTS AND CONCLUSIONS: Average PAI scores decreased from 3.43 at start to 2.21 at 12 months for Grossman's sealer and from 3.40 to 2.26 for the silicon-based material. No significant difference between the groups at start or any of the follow ups was seen. The 3-month control was adequate in establishing significant healing in both groups. The improvement of the periapical condition continued at the 12-month examination.

The effects of dentine pretreatment on the adhesion of root-canal sealers.

AIM: The adhesion of five root-canal sealers to dentine and gutta-percha was studied. The effects of various dentine pretreatments on adhesion were also investigated. METHODOLOGY: Root dentine cylinders, 4 mm in diameter, were prepared from human teeth. The dentine surfaces were conditioned with either 37% H(3)PO(4) for 30 s, 25% citric acid for 30 s, 17% EDTA for 5 min or a rinse with 10 mL distilled water (control). Gutta-percha cylinders, 4 mm in diameter, were prepared and their end surfaces polished flat. The dentine and gutta-percha surfaces were coated with freshly mixed sealer: Grossman's sealer (GS), Apexit (AP), Ketac-Endo (KE), AH Plus (AH), RoekoSeal Automix (RS) or RoekoSeal Automix with an experimental primer (RP). The surfaces were pressed together and the sealers allowed to set. The test specimens were subjected to a tensile force in a universal testing machine. RESULTS: Mean tensile bond strengths (MPa +/- SD) ranged from 0.07 +/- 0.01 (AP) to 1.19 +/- 0.47 (AH). Pretreatment with EDTA showed no effect or produced weaker bonds than controls. Phosphoric and citric acid pretreatments increased adhesion of GS. A primer used with RoekoSeal significantly enhanced its adhesion to untreated dentine. Inspection of fractured surfaces indicated failure of adhesion to dentine for GS and RS and to gutta-percha for KE and RP. The failure appeared to be mainly cohesive within the sealer for AH and AP. CONCLUSIONS: Removal of the smear layer may impair sealer adhesion to dentine. Different sealer types require different dentine pretreatments for optimal adhesion.

A comparative study of lateral condensation, heat-softened gutta-percha, and a modified master cone heat-softened backfilling technique.

AIM: The aim of the study was to compare the quality of root fillings completed by lateral condensation (L), Thermafil (TF), and a new technique using Thermafil for backfilling (BF), with special emphasis on control of overfilling. METHODOLOGY: Sixty curved canals in plastic blocks were prepared with the ProFile system to size 40/04 taper in the apical half and to 06 taper in the coronal half. The canals were divided into three groups of 20. Apical patency was verified with a size 15 K-file. The canals were then filled using three different techniques: LC (20 canals), TF (20 canals), and BF, where a size 40 master point with sealer was seated prior to the introduction of a size 30 Thermafil point (20 canals). The same resin-based sealer was used on each occasion. The root fillings were assessed using stereo-microscopy for material extrusion, digital radiography for occurrence of voids, and microscopy of sections for voids and thickness of sealer layer. RESULTS: Extrusion of both gutta-percha and sealer occurred in all 20 canals filled with the TF technique, but only three and five cases of sealer extrusion were detected with LC and BF techniques, respectively. No voids were detected in the TF group, whereas small voids were present in most fillings in the LC and BF groups. The average total length of the voids was less than 1 mm per canal. The thickness of the sealer layer in the middle and apical parts was greater in the LC and BF groups than in the TF group. CONCLUSIONS: LC and BF techniques resulted in fewer overfills than TF. Voids were absent in TF fillings, whilst small voids were found in the LC and BF groups.

Dimensional change following setting of root canal sealer materials.

OBJECTIVE: The study was designed to evaluate a method proposed for measuring dimensional changes of endodontic sealers, and to assess the dimensional changes of 11 commercial sealers after prolonged storage in water. METHODS: The method for linear dimensional change described in the draft standard for endodontic sealers was applied to 11 different types of endodontic sealers. One material (Sealapex) could not be tested by the method. The other 10 materials were followed for dimensional change over 48 weeks. RESULTS: The sealers showed markedly different dimensional properties. For most materials, the greatest dimensional changes took place within the first 4 weeks. Zinc-oxide-eugenol based sealers generally showed shrinkage ranging from 0.3 to 1%, while one product (Proco-Sol) exhibited expansion exceeding 6% after prolonged storage. The epoxy-based materials, AH 26 and AH 26 silverfree, exhibited a large, initial expansion of 4-5%. AH Plus expanded from 0.4% after 4 weeks up to 0.9%. Apexit, a Ca(OH)2-based material, showed only minor variation round baseline value, -0.14 to +0.19%. Roeko-Seal expanded to 0.2% within 4 weeks, but was stable thereafter. SIGNIFICANCE: The test methodology adequately assessed dimensional changes exceeding +/-0.2%, but some brands of material either could not be made into adequate test specimens or showed surface changes which interfered with dimensional change measurements. Theoretical approaches to the consequences of expansion by materials of low bulk strength question the necessity of a strict requirement against expansion, whereas bacterial penetration may be a real threat from sealers shrinking as little as 1%.

Clinical performance of 3 endodontic sealers.

OBJECTIVE: Calcium hydroxide is used in endodontics as an interappointment dressing. Its inclusion in salicylate resin or zinc oxide-eugenol-based sealers for filling root canals also may lead to a better treatment outcome. The purpose of the present study was to compare the clinical/radiographic treatment outcome of 3 sealers, 2 of which contain calcium hydroxide. STUDY DESIGN: Two hundred and four teeth underwent a standardized endodontic treatment regimen and were assigned to 1 of 3 groups at the time of root filling: group PS, teeth filled with gutta-percha and Procosol sealer; group CR, teeth filled with gutta-percha and CRCS sealer; and group SA, teeth filled with gutta-percha and Sealapex sealer. The results of the treatment were assessed yearly for up to 4 years by clinical and radiologic (periapical index scores) controls. The ridit statistic (r) was used to compare PAI scores among the groups. RESULTS: The overall treatment results were comparable with, but slightly poorer than, results previously obtained from patients seen at the Dental School at the University of Oslo. During the first year after filling, the mean ridit value decreased from .51 +/- .039 to .31 +/- .042 (Deltar = .20) in the SA group. Corresponding values went from .43 +/- .030 to .38 +/- .035 (Deltar = .05) in the PS group and from 37 +/- .045 to .34 +/- .050 (Deltar = .03) in the CR group. At the 2-year examination, teeth in group SA had slightly better periapical conditions (r =.22 +/-.045) than did teeth in group PA (r = .30 +/- .037) or in group CR (r = .30 +/- 052). The difference was statistically significant at P = .01. By years 3 and 4, no significant difference among the groups was detected. CONCLUSIONS: The overall influence of the sealer on treatment outcome was small. Root fillings with salicylate resin containing Ca(OH)2 may support more rapid healing of apical periodontitis or operative trauma, but the results after 3 and 4 years were as good for zinc oxide-eugenol-based sealers with or without Ca(OH)2.

Comparison between PAI and quantitative digital radiographic assessment of apical healing after endodontic treatment.

OBJECTIVE: The purpose of this study was to compare both subjective (Periapical Index, PAI) and objective (densitometric) radiographic evaluation of healing after endodontic treatment for apical periodontitis. STUDY DESIGN: Standardized radiographs of 103 teeth taken at baseline (immediately after endodontic treatment) and at 1, 4, 12, 26, and 52 weeks were evaluated. Consensus PAI scores obtained from 7 calibrated observers served as "true scores." Densitometric estimates of periapical status were obtained from digitized radiographs as the ratio of mean gray value of an area of radiolucency (AR) to an adjacent and similar-sized normal (N) area (AR/N). The selected regions of interest on baseline images were automatically superimposed on postoperative images. All estimates of change were measured with respect to baseline. The subtraction estimate was expressed as AR(S)-N(S). Linear regression was used to analyze longitudinal changes against baseline and to assess the relationship of PAI and AR/N and of change in PAI with respect to baseline and AR(S)-N(S). RESULTS: Five hundred fifty-six PAI scores were generated, with 547 AR/N values and 444 subtraction estimates. PAI, AR/N, and AR(S)-N(S) demonstrated statistical significance for change (P < or = .05) starting at 12 weeks. PAI was significantly correlated with AR/N (P < .0001), as was CHPAI with AR(S)-N(S) (P < .024). CONCLUSION: The PAI and 2 densitometric estimates (AR/N and AR(S)-N(S)) detected healing of apical periodontitis at 12 weeks after treatment. No difference could be observed among the methods.