A comparison of radiographically determined periapical healing and tooth survival outcomes of root canal (re)treatment performed in two care pathways within the United Kingdom Armed Forces.

AIMS: To compare radiographic periapical healing and tooth survival outcomes of root canal (re)treatment performed within two care pathways (Routine Dental Care and Referred Treatment Pathway), in the United Kingdom Armed Forces (UKAF), and determine the effects of endodontic complexity on outcomes. METHODOLOGY: This retrospective cohort study included 1466 teeth in 1252 personnel who received root canal (re)treatment between 2015 and 2020. General Dental Practitioners treated 661 teeth (573 patients) (Routine cohort), whilst Dentists with a Special Interest treated 805 teeth (678 patients) (Referred cohort). The latter group were graduates of an MSc programme in Endodontics with 4-8 years of postgraduation experience. Case complexity was retrospectively determined for each tooth using the endodontic component of Restorative Index of Treatment Need (RIOTN) guidelines. Periapical healing was determined using loose radiographic criteria. The data were analysed using chi-square tests, univariate logistic regression and Cox proportional hazards models. RESULTS: A significantly (p < 0.0001) larger proportion of cases of low complexity had undergone root canal treatment within the Routine versus Referred cohort. The odds of periapical healing was significantly higher within the Referred versus Routine cohort, regardless of analyses using pooled (OR = 1.17; 95% CI: 1.11, 1.22) or moderate complexity (OR = 4.71; 95% CI: 2.73, 8.11) data. Within the Routine cohort, anterior teeth had higher odds of periapical healing than posterior teeth (OR = 1.13; 95% CI: 1.04, 1.22). The 60-month cumulative tooth survival was lower (p = 0.03) in the Routine (90.5%) than the Referred (96.0%) cohort. Within the Routine cohort, the hazard of tooth loss was higher amongst posterior teeth (HR = 4.03; 95% CI: 1.92, 8.45) but lower if posterior teeth had cast restorations (HR = 0.36; 95% CI: 0.19, 0.70). For the Referred cohort, posterior teeth restored with cast restoration (vs not) had significantly lower risk of tooth loss (HR = 0.21; 95% CI: 0.08, 0.55). CONCLUSIONS: For UKAF patients, root canal (re)treatment provided within the Referred pathway was significantly more likely to achieve periapical healing and better tooth survival than those provided within the Routine pathway. Posterior teeth restored with an indirect restoration had a higher proportion of tooth survival. This study supported the utility of the endodontic component of RIOTN for assessing case complexity.

Factors that influence the outcomes of surgical endodontic treatment.

Surgical endodontic treatment encompasses a broad spectrum of procedures, amongst which root-end cavity preparation and filling, retrograde root canal treatment and through-and-through endodontic surgery, may be classified under the umbrella term 'Root-end surgery'. This narrative review considers the available data on periapical healing, soft tissue healing, tooth survival and oral health-related quality of life (OHRQoL), following root-end surgery and the factors that affect its outcomes. The pooled periapical healed rate for the studies published up to 2021 was 69% (95% CI: 65%, 73%) but increased to 76% (95% CI: 66%, 86%) when only data from the 2020's studies were analysed. The prognostic factors consistently reported for periapical healing have included: pre-operative periapical lesion with complete loss of buccal plate, quality of root-end preparation, remaining thickness of apical root dentine and restorative status. Soft tissue healing of the reflected flap was found to have a positive association with periapical healing. The survival rates following root-end surgery range from 48% to 93%, with failure of periapical healing associated with root and crown fracture, being the predominant reasons for tooth extraction. The factors influencing impact of root-end surgery on patients' quality of life could not be adequately evaluated due to design flaws in the available studies. In conclusion, if root canal treatment failure due to leakage through cracks, fractures or restoration margin are excluded, the remaining cases may represent localized residual infection and inflammation at the periapex that should be amenable to predictable management with the aid of modern root-end surgery.

Factors that affect the outcomes of root canal treatment and retreatment-A reframing of the principles.

This paper undertakes a broad and comprehensive synthesis of relevant clinical, biological, biomechanical, technical and healthcare services data to understand the factors affecting outcomes of periapical healing after root canal (re)treatment. The medical and dental evidence-based era (1980-present) is contextualized with the earlier evidence drive in endodontics (1911-1940) triggered by the focal infection era. The current evidence-based approach has a sharper focus on evidence quality and derivation of practice guidelines. Contrary views question whether guideline-driven, or expertise-development-driven endeavours would best serve outcome improvement in society. The endodontic discipline functions in a broad healthcare framework and sustains industrial, economic and trend pressures that may be deemed to influence outcomes. The nature of root canal treatment and the challenges in determining the factors that affect its outcomes is discussed. The factors potentially affecting periapical healing after root canal treatment are classified into pre-operative, intra-operative and postoperative groups. These categories subsume multiple elements with interactive influences, creating a complex picture, further confounded by some apparently surprising, counter-intuitive and contradictory findings. The technical versus biological conundrum in root canal treatment continues to cause cognitive dissonance. However, due reflection and cross-discipline-synthesis resolve the apparent data conflicts into a very simple, consistent and plausible picture of how root canal treatment works and the key factors that affect periapical healing. Root canal retreatment is considered mainly in the context of its differences from primary treatment as the majority of factors influencing outcomes are common to both. The exceptional difference is that retreatments have a proportionately reduced probability of healing by virtue of compromised apical root canal ramification access or modified host/infection interactions. Root canal (re)treatment outcomes are dominantly influenced by the nature of prior dynamic host/infection interaction (pre-operative patient factors) and how the direction of this dynamic is influenced by two factors: (1) the active efficacy of the operators' root canal treatment protocol to sustain a microbial ecological shift (intra-operative treatment factors) and dampen periapical inflammation; and (2) the passive ability of the functional tooth (and its restoration margin) to maintain its integrity to resist infection reversal (postoperative restorative factors).

Effectiveness of root canal treatment for vital pulps compared with necrotic pulps in the presence or absence of signs of periradicular pathosis: A systematic review and meta-analysis.

BACKGROUND: Preoperative pulpal status may influence the outcomes of root canal treatment (RCTx) according to various measures used. OBJECTIVES: To compare the effectiveness of RCTx of teeth with a vital pulp versus a necrotic pulp, using a range of clinical and patient-related outcomes proposed for the development of S3-level clinical practice guidelines. METHODS: A search was conducted in the PubMed-MEDLINE, Scopus, EMBASE, Google scholar databases and available repositories, followed by hand searches, until 29 March 2022. Clinical studies published in the English language comparing the stipulated outcomes of RCTx of teeth with vital versus necrotic pulp were included. The Newcastle-Ottawa Scale was adapted to assess study quality. Effects of pulpal status were estimated and expressed as risk ratio (RR) using fixed- and random-effect meta-analyses. The quality of evidence was assessed through the Grading of Recommendations Assessment, Development and Evaluation tool. RESULTS: Twenty-eight studies published between 1961 and 2021 were included. Five studies have investigated the "tooth survival" outcome, four reported pulpal status was not a significant predictor, consistent with meta-analysis findings (RR: 1.00; 95% CI: 1.00, 1.00; n = 3). Seven studies reported pulpal status had no significant influence on postoperative pain, regardless of duration after treatment. Sixteen studies have analysed "periapical health," and 11 revealed pulpal status had no significant influence. Meta-analyses revealed the influence was not significant if preoperative periapical radiolucency was absent (RR: 0.95; 95% CI: 0.90, 1.00; n = 9) but significant if it was present (RR: 1.12; 95% CI: 1.05, 1.19; n = 11). Most studies were classified as "some concerns" (n = 17) to "low" (n = 9) risk of bias RoB. DISCUSSION: Evidence is limited and only available for three outcomes when comparing the effectiveness of RCTx in permanent teeth with vital pulp versus pulp necrosis. Nevertheless, the quality of available evidence was moderate to high. The "periapical health" data heterogeneity could be explained by preoperative radiolucency, thus RCTx was found more effective for prevention than the resolution of apical periodontitis. CONCLUSIONS: There was no significant difference in the "tooth survival," "postoperative pain" and "evidence of apical radiolucency" outcomes of RCTx in teeth with vital or necrotic pulps. REGISTRATION: PROSPERO database (CRD42021260280).

Bacteria in the cavity-restoration interface after varying periods of clinical service - SEM description of distribution and 16S rRNA gene sequence identification of isolates.

OBJECTIVES: To use extracted human teeth with amalgam (n = 26) or GIC (n = 3) restorations in service up to 20 years to evaluate microbiota at the cavity/restoration interface by SEM or culture. MATERIALS AND METHODS: Extracted teeth with intracoronal restorations (n = 20) of known history (2-20 years) were fixed, split, and prepared for SEM to ascertain the pattern and structure of bacterial aggregates on cavity and restoration surfaces. Another 9 teeth were anaerobically decontaminated, split and sampled (cavity/restorations), and cultured (anaerobically, aerobically); recovered isolates were identified by 16S rRNA gene sequencing. RESULTS: SEM showed rods, cocci, and filaments in 11/20 teeth (55%) on cavity and corresponding restoration surfaces; 4/20 (20%) on neither surface; 1/20 (5%) on just cavity; and 4/20 (20%) on just restoration. Microbial growth extended from marginal openings into the deeper interfacial microspace to varying extents but was not always evident. Restoration size or age did not predict bacterial presence. Bacteria-free surfaces (cavity/amalgam) showed possible calcification. Cultivation yielded 160 isolates, mainly Gram-positive (86%) and facultative (81%); and morphotypes of rods (43%), cocci (36%), and cocco-bacilli (18%) belonging to Actinobacteria (45%) and Firmicutes (50%). The most frequent genera were Staphylococcus, Streptococcus, Actinomyces, and Lactobacillus. Biofilms on cavity and restoration appeared independent of each other. CONCLUSIONS: Cavity and amalgam surfaces were independently colonised and some not. The penetration of microbiota into marginal gaps varied; resembled root caries and was dominated by Gram-positive species. CLINICAL RELEVANCE: Marginal gaps around restorations are unavoidable but are not always colonised by bacteria after long-term clinical service. Calcification of biofilms in the restorative interface may prevent further colonisation. The viable microbiota in the restorative interface resembled root caries and may be subject to ecological fluxes of activity and arrest and therefore preventative management.

Removal and dispersal of biofluid films by powered medical devices: Modeling infectious agent spreading in dentistry.

Medical procedures can disperse infectious agents and spread disease. Particularly, dental procedures may pose a high risk of disease transmission as they use high-powered instruments operating within the oral cavity that may contain infectious microbiota or viruses. Here we assess the ability of powered dental devices in removing the biofluid films and identified mechanical, hydrodynamic, and aerodynamic forces as the main underlying mechanisms of removal and dispersal processes. Our results indicate that potentially infectious agents can be removed and dispersed immediately after dental instrument engagement with the adherent biofluid film, while the degree of their dispersal is rapidly depleted owing to the removal of the source and dilution by the coolant water. We found that droplets created by high-speed drill interactions typically travel ballistically, while aerosol-laden air tends to flow as a current over surfaces. Our mechanistic investigation offers plausible routes for reducing the spread of infection during invasive medical procedures.

Radiographic periapical healing associated with root-treated teeth accessed through existing crowns: a historical controlled cohort study.

OBJECTIVES: The aim of this study was to determine the periapical healing rate and complications arising from non-surgical root canal treatment (NSRCT) conducted through the existing and retained restoration, compared to that conducted after removal of restoration (direct or indirect) with subsequent placement of a new crown. MATERIALS AND METHODS: Two-hundred-and-forty-five teeth met the inclusion criteria and were followed up for 2 years. One-hundred-and-six teeth had NSRCT completed through existing cast restorations, and 57 and 82 had the existing crowns and direct restorations removed (respectively) and received a new crown after NSRCT. Periapical healing was assessed radiographically using strict (complete healing) and loose (complete and incomplete healing) criteria. Multivariable logistic regression models were used to investigate the effect of prior restoration removal on periapical healing following NSRCT, adjusting for potential confounding (p < 0.05). RESULTS: There was no significant (p > 0.05) difference in the periapical healing rates amongst teeth accessed through existing crowns (72%, 90%) versus those where crowns (79%, 93%) or direct restorations (77%, 90%) were removed for NSRCT. The findings were adjusted for the significant influencing factor: size of pre-operative radiolucency (p < 0.05). Of the 109 teeth that were initially accessed through existing crowns, 9 (8%) displayed porcelain fracture or crown de-cementation. CONCLUSION: Performing root canal treatment through an existing full coverage restoration did not compromise periapical healing and was associated with a low incidence of associated complications. CLINICAL RELEVANCE: Crown removal before NSRCT is not mandatory for periapical healing but requires a judicious pre-assessment of current and future marginal and restorative integrity.

Viscoelastic and chemical properties of dentine after different exposure times to sodium hypochlorite, ethylenediaminetetraacetic acid and calcium hydroxide.

This study aims to evaluate the viscoelastic and chemical properties of dentine after different durations of exposure to 5.25% NaOCl, 17% EDTA and Ca(OH)2 solutions, and NaOCl in alternating combination with EDTA. Standard dentine bars were randomly assigned to: (i) formal-saline control-1; (ii) NaOCl; (iii) EDTA; (iv) NaOCl/EDTA; (v) formal-saline control-2; (vi) Ca(OH)2 pH 12.6; and (vii) Ca(OH)2 pH 9.8. Groups 1--4 underwent 10 min cycles of soaking and dynamic mechanical analysis up to 120 min. Groups 5-7 underwent similar tests at days 7, 14, 28 and 84. FTIR spectra of dentine discs exposed to the same regimens assessed surface chemistry. NaOCl or Ca(OH)2 (pH 12.6) solutions reduced the organic (N-H[1], N-H[3], C=0) peak components of dentine. This study demonstrated that accumulative damage of dentine could be facilitated by alternated exposure to NaOCl and EDTA. Exposure of dentine to Ca(OH)2 (pH12.6) for 7 days reduced viscous behaviour, inferring increased potential for fatigue failure.

Effect of Heated Sodium Hypochlorite on the Viscoelastic Properties of Dentin Evaluated Using Dynamic Mechanical Analysis.

INTRODUCTION: This study aimed to investigate the effect of the immersion of standardized dentin bars in 5% sodium hypochlorite (NaOCl) solutions at 60°C and 80°C on their viscoelastic properties using dynamic mechanical analysis. METHODS: Eighteen intact teeth were used to produce 99 dentin bars of standard dimensions (12 × 1 × 2 mm) and randomly allocated to 6 groups (n = 15 each) for immersion in (1) saline at 26°C, (2) saline at 60°C, (3) saline at 80°C, (4) NaOCl at 26°C, (5) NaOCl at 60°C, and (6) NaOCl at 80°C. The bars were individually tested using dynamic mechanical analysis at baseline and after every 10 minutes of immersion in the test medium, up to 40 minutes. The effects of media, temperature, duration of exposure, and aspect ratio of bars on the storage modulus and tan delta were investigated using generalized estimating equations. RESULTS: There was a significant interaction between the test medium and the duration of immersion (P < .05). The storage modulus of specimens immersed in NaOCl at 60°C or 80°C decreased significantly (P < .0001) over time of exposure, but the changes in other groups were minimal and insignificant. The tan delta of specimens immersed in saline 80°C (P < .05), NaOCl at 60°C (P < .05), or 80°C (P < .0001) increased significantly over the time of exposure, but the change in NaOCl at 26°C was minimal. Other groups displayed negligible changes. CONCLUSIONS: NaOCl at 60°C or 80°C significantly reduced the elastic behavior but increased the hysteresis of dentin under cyclic loading.

Value of root-filled teeth in maintaining a functional dentition for life.

The purpose of this article is to draw attention to the strategic goals of planning for a functionally and aesthetically optimal dentate quality of life, and the role that teeth maintained through root canal treatment can play in such a plan. The perception that root-treated teeth should largely, and wherever possible, be discarded as a viable option is a seriously flawed judgment. The utility of root-treated teeth must be properly and critically discriminated as they can play a significant role in the long-term plan, despite having unique characteristics that must be accounted for.

Injectable local anaesthetic agents for dental anaesthesia.

BACKGROUND: Pain during dental treatment, which is a common fear of patients, can be controlled successfully by local anaesthetic. Several different local anaesthetic formulations and techniques are available to dentists. OBJECTIVES: Our primary objectives were to compare the success of anaesthesia, the speed of onset and duration of anaesthesia, and systemic and local adverse effects amongst different local anaesthetic formulations for dental anaesthesia. We define success of anaesthesia as absence of pain during a dental procedure, or a negative response to electric pulp testing or other simulated scenario tests. We define dental anaesthesia as anaesthesia given at the time of any dental intervention.Our secondary objective was to report on patients' experience of the procedures carried out. SEARCH METHODS: We searched the Cochrane Central Register of Controlled Trials (CENTRAL; the Cochrane Library; 2018, Issue 1), MEDLINE (OVID SP), Embase, CINAHL PLUS, WEB OF SCIENCE, and other resources up to 31 January 2018. Other resources included trial registries, handsearched journals, conference proceedings, bibliographies/reference lists, and unpublished research. SELECTION CRITERIA: We included randomized controlled trials (RCTs) testing different formulations of local anaesthetic used for clinical procedures or simulated scenarios. Studies could apply a parallel or cross-over design. DATA COLLECTION AND ANALYSIS: We used standard Cochrane methodological approaches for data collection and analysis. MAIN RESULTS: We included 123 studies (19,223 participants) in the review. We pooled data from 68 studies (6615 participants) for meta-analysis, yielding 23 comparisons of local anaesthetic and 57 outcomes with 14 different formulations. Only 10 outcomes from eight comparisons involved clinical testing.We assessed the included studies as having low risk of bias in most domains. Seventy-three studies had at least one domain with unclear risk of bias. Fifteen studies had at least one domain with high risk of bias due to inadequate sequence generation, allocation concealment, masking of local anaesthetic cartridges for administrators or outcome assessors, or participant dropout or exclusion.We reported results for the eight most important comparisons.Success of anaesthesiaWhen the success of anaesthesia in posterior teeth with irreversible pulpitis requiring root canal treatment is tested, 4% articaine, 1:100,000 epinephrine, may be superior to 2% lidocaine, 1:100,000 epinephrine (31% with 2% lidocaine vs 49% with 4% articaine; risk ratio (RR) 1.60, 95% confidence interval (CI) 1.10 to 2.32; 4 parallel studies; 203 participants; low-quality evidence).When the success of anaesthesia for teeth/dental tissues requiring surgical procedures and surgical procedures/periodontal treatment, respectively, was tested, 3% prilocaine, 0.03 IU felypressin (66% with 3% prilocaine vs 76% with 2% lidocaine; RR 0.86, 95% CI 0.79 to 0.95; 2 parallel studies; 907 participants; moderate-quality evidence), and 4% prilocaine plain (71% with 4% prilocaine vs 83% with 2% lidocaine; RR 0.86, 95% CI 0.75 to 0.99; 2 parallel studies; 228 participants; low-quality evidence) were inferior to 2% lidocaine, 1:100,000 epinephrine.Comparative effects of 4% articaine, 1:100,000 epinephrine and 4% articaine, 1:200,000 epinephrine on success of anaesthesia for teeth/dental tissues requiring surgical procedures are uncertain (RR 0.85, 95% CI 0.71 to 1.02; 3 parallel studies; 930 participants; very low-quality evidence).Comparative effects of 0.5% bupivacaine, 1:200,000 epinephrine and both 4% articaine, 1:200,000 epinephrine (odds ratio (OR) 0.87, 95% CI 0.27 to 2.83; 2 cross-over studies; 37 participants; low-quality evidence) and 2% lidocaine, 1:100,000 epinephrine (OR 0.58, 95% CI 0.07 to 5.12; 2 cross-over studies; 31 participants; low-quality evidence) on success of anaesthesia for teeth requiring extraction are uncertain.Comparative effects of 2% mepivacaine, 1:100,000 epinephrine and both 4% articaine, 1:100,000 epinephrine (OR 3.82, 95% CI 0.61 to 23.82; 1 parallel and 1 cross-over study; 110 participants; low-quality evidence) and 2% lidocaine, 1:100,000 epinephrine (RR 1.16, 95% CI 0.25 to 5.45; 2 parallel studies; 68 participants; low-quality evidence) on success of anaesthesia for teeth requiring extraction and teeth with irreversible pulpitis requiring endodontic access and instrumentation, respectively, are uncertain.For remaining outcomes, assessing success of dental local anaesthesia via meta-analyses was not possible.Onset and duration of anaesthesiaFor comparisons assessing onset and duration, no clinical studies met our outcome definitions.Adverse effects (continuous pain measured on 170-mm Heft-Parker visual analogue scale (VAS))Differences in post-injection pain between 4% articaine, 1:100,000 epinephrine and 2% lidocaine, 1:100,000 epinephrine are small, as measured on a VAS (mean difference (MD) 4.74 mm, 95% CI -1.98 to 11.46 mm; 3 cross-over studies; 314 interventions; moderate-quality evidence). Lidocaine probably resulted in slightly less post-injection pain than articaine (MD 6.41 mm, 95% CI 1.01 to 11.80 mm; 3 cross-over studies; 309 interventions; moderate-quality evidence) on the same VAS.For remaining comparisons assessing local and systemic adverse effects, meta-analyses were not possible. Other adverse effects were rare and minor.Patients' experiencePatients' experience of procedures was not assessed owing to lack of data. AUTHORS' CONCLUSIONS: For success (absence of pain), low-quality evidence suggests that 4% articaine, 1:100,000 epinephrine was superior to 2% lidocaine, 1:100,000 epinephrine for root treating of posterior teeth with irreversible pulpitis, and 2% lidocaine, 1:100,000 epinephrine was superior to 4% prilocaine plain when surgical procedures/periodontal treatment was provided. Moderate-quality evidence shows that 2% lidocaine, 1:100,000 epinephrine was superior to 3% prilocaine, 0.03 IU felypressin when surgical procedures were performed.Adverse events were rare. Moderate-quality evidence shows no difference in pain on injection when 4% articaine, 1:100,000 epinephrine and 2% lidocaine, 1:100,000 epinephrine were compared, although lidocaine resulted in slightly less pain following injection.Many outcomes tested our primary objectives in simulated scenarios, although clinical alternatives may not be possible.Further studies are needed to increase the strength of the evidence. These studies should be clearly reported, have low risk of bias with adequate sample size, and provide data in a format that will allow meta-analysis. Once assessed, results of the 34 'Studies awaiting classification (full text unavailable)' may alter the conclusions of the review.

Investigation to test potential stereolithography materials for development of an in vitro root canal model.

The aims were to compare the physico-chemical properties (zeta-potential, wettability, surface free energy) of stereolithography materials (STL) (Photopolymer, Accura) to dentine and to evaluate the potential of each material to develop Enterococcus faecalis biofilm on their respective surfaces. Eighteen samples of each test material (Photopolymer, Accura, dentine) were employed (total n = 54) and sectioned to 1 mm squares (5 mm x 5 mm) (n = 15) or ground into a powder to measure zeta-potential (n = 3). The zeta-potential of the powder was measured using the Nano-Zetasizer technique. The contact angle (wettability, surface free energy tests) were measured on nine samples using goniometer. The biofilm attachment onto the substrate was assessed on the samples of each material using microscope and image processing software. The data were compared using one-way ANOVA with Dunnett post-hoc tests at a level of significance P ≤ 0.05. Both STL materials showed similar physico-chemical properties to dentine. The materials and dentine had negative charge (Accura: -23.7 mv, Photopolymer: -18.8 mv, dentine: -9.11 mv). The wettability test showed that all test materials were hydrophilic with a contact angle of 47.5°, 39.8°, 36.1° for Accura, Photopolymer and dentine respectively, and a surface free energy of 46.6, 57.7, 59.6 mN/m for Accura, Photopolymer and dentine, respectively. The materials and dentine proved suitable for attachment and growth of E. faecalis biofilm with no statistical differences (P > 0.05). Stereolithography materials show similar physico-chemical properties and growth of E. faecalis biofilm to dentine. Therefore, they may be an alternative to tests requiring dentine.

3D Computer aided treatment planning in endodontics.

OBJECTIVES: Obliteration of the root canal system due to accelerated dentinogenesis and dystrophic calcification can challenge the achievement of root canal treatment goals. This paper describes the application of 3D digital mapping technology for predictable navigation of obliterated canal systems during root canal treatment to avoid iatrogenic damage of the root. METHODS: Digital endodontic treatment planning for anterior teeth with severely obliterated root canal systems was accomplished with the aid of computer software, based on cone beam computer tomography (CBCT) scans and intra-oral scans of the dentition. On the basis of these scans, endodontic guides were created for the planned treatment through digital designing and rapid prototyping fabrication. RESULTS: The custom-made guides allowed for an uncomplicated and predictable canal location and management. CONCLUSION: The method of digital designing and rapid prototyping of endodontic guides allows for reliable and predictable location of root canals of teeth with calcifically metamorphosed root canal systems. CLINICAL SIGNIFICANCE: The endodontic directional guide facilitates difficult endodontic treatments at little additional cost.

Contemporary root canal irrigants are able to disrupt and eradicate single- and dual-species biofilms.

INTRODUCTION: Clinical/microbiological studies have consistently revealed the persistence of some bacteria after conventional root canal debridement. Although this was originally attributed to the complexity of the root canal anatomy and the difficulty of delivering antibacterial agents effectively, it has emerged that the biofilm encasement of bacterial cells may confer a further mechanism of resistance. The purpose of this study was to investigate the relative disruption and bactericidal effects of root canal irrigants on single- and dual-species biofilms of root canal isolates. METHODS: Biofilms of Streptococcus sanguinis, Enterococcus faecalis, Fusobacterium nucleatum, and Porphyromonas gingivalis were grown on nitrocellulose membranes for 72 hours and immersed in NaOCl, EDTA, chlorhexidine, and iodine for 1, 5, or 10 minutes. The number of viable and nonviable bacteria disrupted from the biofilm and those remaining adherent were determined by using a viability stain in conjunction with fluorescence microscopy. RESULTS: Gram-negative obligate anaerobe species were more susceptible to cell removal than gram-positive facultative anaerobes. The majority of cells were disrupted after the first minute of exposure; however, the extent varied according to the agent and species. The most effective agent at disrupting biofilms was NaOCl. Iodine was generally effective at bacterial killing but not disruption. CONCLUSIONS: Biofilm disruption and cell viability were influenced by the species, their coassociation in dual-species biofilms, the test agent, and the duration of exposure. The effectiveness of NaOCl as an endodontic irrigant was reinforced.

Ion release characteristics, precipitate formation and sealing ability of a phosphate glass-polycaprolactone-based composite for use as a root canal obturation material.

OBJECTIVES: The filling material used to obturate root canal systems during the common dental procedure, root canal treatment, has popularly involved gutta-percha (GP) in one of its many forms for almost a 100 years. An optimal root filling material should provide a predictable seal, inhibit or kill residual bacteria, prevent re-contamination and facilitate periapical healing. Although the goal of obturation is stated as the creation of a "seal", its precise role still remains elusive and the seal offered suspect. The primary goal of the study was to develop a novel polycaprolactone/phosphate glass composite deliverable as a root filling and capable of releasing ionic species to enable a predictable seal in an aqueous environment. MATERIALS AND METHODS: Different compositions of polycaprolactone-iron phosphate glass (Fe(2)O(3) 1, 3 and 5mol%) composites were produced and delivered into an ex vivo root canal model. Standardized root canals were prepared in extracted human teeth. The teeth were examined for root filling adaptation and precipitate formation (SEM), ion release (Na(+), Ca(2+), PO(4)(3-), P(2)O(7)(4-), P(3)O(9)(3-), and P(5)O(10)(5-)), and sealing ability. The experiments were controlled with teeth obturated with contemporary GP and a conventional zinc-oxide/eugenol sealer. RESULTS: Adaptation of the experimental material was statistically significantly better than the GP control groups. Precipitate formation was noted in some specimens but all released various ionic species in an inverse proportion to the iron oxide concentration. The experimental material exhibited significantly (P<0.001) less leakage after 7 days immersion in saline compared with those not immersed, or the control GP group. SIGNIFICANCE: PCL-phosphate glass composites showed good potential as a root filling material capable of producing a seal in an aqueous environment without a sealer.

Susceptibilties of two Enterococcus faecalis phenotypes to root canal medications.

This study aimed to investigate and compare the efficacy of selected root canal irrigants and a medicament on a clinical isolate of Enterococcus faecalis grown as biofilm or planktonic suspension phenotype. A cell-dense pellet "presentation" prepared from planktonic phenotype was also tested. Each bacterial presentation was exposed to calcium hydroxide (pH 12.3), 0.2% chlorhexidine gluconate, 17% ethylene-diamine-tetra-acetic acid, 10% povidone iodine, or 3.0% sodium hypochlorite (NaOCl) for a range of time periods (1, 2, 4, 8, 15, 30, and 60 min). Phosphate buffered saline was used as a control agent. The difference in gradients of bacterial killing among the biofilm, planktonic suspension or pellet presentation was significant (p < 0.05) and dependent upon the test agent except in the case of NaOCl and calcium hydroxide where no difference could be detected. NaOCl was the most effective agent and achieved 100% kills for all presentations of E. faecalis after a 2 min contact time.

Evaluation of protocols for field decontamination before bacterial sampling of root canals for contemporary microbiology techniques.

The effectiveness of sodium hypochlorite (NaOCl) (2.5%) or iodine (10%) for decontamination of the operation field (tooth, rubber dam, and gasket [Oraseal]) was compared by using bacterial cultivation. In addition, the final samples were also assessed for bacteria by using polymerase chain reaction. Teeth (n = 63) receiving root canal treatment were polished with pumice, isolated with rubber dam, and their margins sealed with Oraseal. The operation field was disinfected with hydrogen peroxide (30%), followed by iodine (n = 31) or NaOCl (n = 32), before and after access cavity preparation. The operation field was sampled before and after each decontamination, giving four samples per field. After the final decontamination, there was no significant difference (p = 0.602, 0.113, 0.204) in recovery of cultivable bacteria from various sites in either group. However, bacterial DNA could be detected significantly (p = 0.010) more frequently from the tooth surfaces after iodine (45%) compared with NaOCl (13%) decontamination, although on the rubber dam or Oraseal surfaces there was no difference. Root canal sampling for polymerase chain reaction might be better preceded by NaOCl decontamination than by iodine, based on the findings.

A retrospective comparison of outcome of root canal treatment using two different protocols.

OBJECTIVES: This retrospective study (1) compared the outcome of root canal treatment performed by an endodontist using 1 of 2 different protocols and (2) evaluated the influence of factors affecting outcome. STUDY DESIGN: A total of 200 teeth and 489 roots (Protocol A, 83 teeth/200 roots; Protocol B, 117 teeth/289 roots) treated nonsurgically with root canal 4 to 5 years previously were examined clinically and radiographically according to strict criteria. Generalized estimating equations were used to perform logistic regression to analyze data. RESULTS: The rate of complete healing for Protocol A (78%) was similar to that of Protocol B (76%). The pulpal status (odds ratio = 2.399, P =.040) and presence (odds ratio = 1.696, P = 0.015) and size (odds ratio = 0.823, P <.001) of periapical lesion were the only factors significantly affecting treatment outcome. CONCLUSION: The preoperative status of the pulp and the presence and extent of periapical periodontitis were important prognostic determinants of treatment outcome in this study.