Fracture resistance of human roots filled with mineral trioxide aggregate mixed with phosphate-buffered saline, with and without calcium hydroxide pre-medication.

AIM: To compare the fracture strength of extracted human roots with apical plugs of mineral trioxide aggregate (MTA) mixed with either Ca- and Mg-free phosphate-buffered saline (PBS) or water, with and without calcium hydroxide (CH) canal pre-medication. METHODOLOGY: A total of 180 single-rooted human teeth were prepared to resemble immature roots and divided into groups (n = 20). The negative control received canal irrigation only, and the positive control received intracanal treatment with CH for either two or twelve weeks. MTA mixed with water was used in Group 1: (i) without CH pre-medication - MTA(W); (ii) after 2 weeks CH pre-medication - 2/52CH + MTA(W); and (iii) after 12-week CH pre-medication - 12/52 CH + MTA(W). MTA mixed with PBS was used in Group 2: (i) without CH pre-medication - MTA(PBS); (ii) after 2-week CH pre-medication - 2/52CH + MTA(PBS); and (iii) after 12-week CH pre-medication - 12/52 CH + MTA(PBS). A compressive force was applied to each root until the point of fracture. The results were analysed by the Kruskal-Wallis and Dunn's multiple comparisons tests (P < 0.05). RESULTS: There was no significant difference between groups MTA(W), MTA(PBS) and 2/52CH + MTA(PBS), and all three groups were significantly (P < 0.01, P < 0.05 and P < 0.05, respectively) more resistant to fracture than the negative control. Within Group 1, the samples that received two- (P < 0.01) and twelve-week (P < 0.001) CH pre-treatment were more prone to fracture than those which did not. No difference was found amongst the control groups. The roots of the MTA(PBS) group had a higher dependability (P < 0.05) than the MTA(W) group when compared by the Weibull modulus. The difference was also present when a 2-week CH pre-medication was used. CONCLUSIONS: Mineral trioxide aggregate mixed with Ca- and Mg-free phosphate-buffered saline had a significant strengthening effect on the fracture resistance of structurally weak roots, even when short-term calcium hydroxide pre-medication had been used. MTA mixed with water lost its strengthening effect on human roots when 2- or 12-week CH pre-treatment had been used. Use of CH dressing for up to 12 weeks had no negative effect on fracture resistance of human roots.

Treatment planning the endodontic-implant interface.

One of the most challenging treatment planning decisions in restorative dentistry is the retention of a root filled tooth or its extraction and replacement with an implant. Making an informed judgement relies upon not only clinical experience and expertise but also interpretation of the published clinical evidence. In the last few years, more robust data and closer scrutiny of the evidence has helped to understand the advantages and disadvantages of each of these treatment modalities. The purpose of this paper is to provide a narrative review of some of the factors that may influence treatment planning for root canal treated teeth and indications for whether these teeth would be better replaced by an implant. From the evidence presented it is clear that both treatments have a place in contemporary restorative dental treatment and that survival for both root filled teeth and implants are similar. Unsurprisingly, both these treatment choices require high standards of clinical expertise and careful planning to ensure the best outcome.

Prevalence of periradicular periodontitis in a Scottish subpopulation found on CBCT images.

AIM: To investigate the prevalence of periradicular periodontitis (PRP) using cone-beam computed tomography (CBCT) scans in a retrospective cross-sectional epidemiological study in a Scottish subpopulation. METHODOLOGY: Of the 319 CBCT scans performed at Dundee Dental Hospital between November 2009 and July 2012, 245 dentate scans of patients over 18 years of age were included and 3595 teeth examined. Odds ratios were calculated, and the association between root filling and posts with PRP was determined. RESULTS: Radiological signs of PRP were detected in 209 teeth (5.8%) in 96 patients (male = 53, female = 43) of which 145 (69.4%) were measurable and 64 (30.6%) appeared as periapical widening. Most lesions were seen in the 46-55-year age group and in maxillary anterior teeth (35.4%); 47.4% (n = 81) of the total root filled teeth (n = 171) had PRP. Of the root filled teeth with lesions, approximately half (50.6%) had an inadequate root filling. Teeth with crowns, but not root filled, accounted for 17.7% of PRP. Periapical changes were detected on a high proportion of teeth with post-retained crowns (70.7%). The presence of a root filling was significantly associated with PRP (z = 17.689 P < 0.0001; odds ratio 16.36 < 23.17 < 32.83, 95% CI) and the presence of a post (z = 10.901 P < 0.0001; odds ratio 21.36 < 41.8021 < 81.78, 95% CI). CONCLUSIONS: The prevalence of PRP in a Scottish subpopulation was 5.8%. The presence of a root filling or a post-retained crown was significantly associated with the presence of PRP as determined by CBCT scans. The prevalence of periradicular disease in root filled teeth remains high in the Scottish population.

Dental dilemmas: endodontics or dental implants?

This narrative review explores treatment planning options in restorative dentistry. The growth of dental implants, as an accessible and predictable treatment option, gives practitioners a useful tool for managing the missing tooth or teeth with a hopeless prognosis. Traditionally, endodontics and fixed prosthodontics have been used to restore teeth and spaces where the outlook for such treatment appears reasonable. Practitioners may, however, question the predictability and cost effectiveness of such an approach where, at times, it might appear that replacement of a compromised tooth with a dental implant could be a more predictable option. The evidence base for these treatment options is explored and discussed, and suggestions are made for future management strategies.

Assessment of vascularity as an index of angiogenesis in periradicular granulomas. Comparison with oral carcinomas and normal tissue counterparts.

AIM: To quantify vascularity in periradicular granulomas using different endothelial markers, and assess its value as an index of angiogenesis by comparing granulomas with healthy periodontal ligament (PDL). To use oral tumours, compared with adjacent normal mucosa, as positive controls. METHODOLOGY: Paraffin-embedded sections were stained with antibodies to von Willebrand factor (vWF), a pan-endothelial marker, and CD105, a putative marker for angiogenic vessels. Vascularity was quantified by different methods reflecting vessel volume and density. RESULTS: Irrespective of the marker or method used, vascularity values were similar in periradicular granuloma and PDL. Both tissues were highly vascularized, with levels similar to those found in oral squamous cell carcinoma. Vascularity was significantly higher in the latter than in normal mucosa. Fewer vessels were positive for CD105 than for vWF in the normal mucosa, whereas similar numbers were found in the other tissues examined. CONCLUSIONS: A comparison of vascularity in oral tumours and normal oral mucosa provided evidence of angiogenesis in the former. Staining with CD105 added limited value to staining with vWF in these tissues. In contrast, a comparison of periradicular granuloma and PDL failed to demonstrate evidence of angiogenesis in the granuloma. As all vessels were similarly stained with vWF and CD105 in granuloma and PDL, a possible hypothesis is that all vessels are newly formed in these tissues. A more plausible alternative is that CD105 expression may reflect the metabolic activity or intrinsic characteristics of the tissues, rather than the presence of angiogenic vessels.

Detection of bacteraemias during non-surgicalroot canal treatment.

UNLABELLED: Some dental procedures initiate a bacteraemia. In certain compromised patients, this bacteraemia may lead to distant site infections, most notably infective endocarditis. OBJECTIVE: To investigate whether a detectable bacteraemia was produced during non-surgical root canal therapy. METHODS: Thirty patients receiving non-surgical root canal therapy were studied. Three blood samples were taken per patient: pre-operatively, peri-operatively and post-operatively. In addition, a paper point sample was collected from the root canal. The blood samples were cultured by pour plate and blood bottle methods. The isolated organisms were identified by standard techniques. Blood samples were analysed for the presence of bacterial DNA by the polymerase chain reaction (PCR). In two cases where the same species of organism was identified in the root canal and the bloodstream, the isolates were typed by pulsed field gel electrophoresis (PFGE). RESULTS: By conventional culturing, a detectable bacteraemia was present in 9 (30%) of the 30 patients who had no positive pre-operative control blood sample. In 7 (23.3%) patients, the same species of organism was identified in both the bloodstream and in the paper point sample from the root canal system. Overall, PCR gave lower detection rates compared with conventional culture, with 10 of 90 (11%) of the blood samples displaying bacterial DNA. PFGE typing was undertaken for two pairs of culture isolates from blood and paper points; these were found to be genetically identical. CONCLUSIONS: Non-surgical root canal treatment may invoke a detectable bacteraemia.

Peer review amongst restorative specialists on the quality of their communication with referring dental practitioners.

OBJECTIVE: A peer review study was carried out to assess the written communication between consultants and specialist registrars in restorative dentistry with the referring general dental practitioners. METHODS: Seven people took part in the study and each presented referral and reply letters for five patients whom they had seen for consultation. The referral letters were used for information only and were not used in the peer review process. Each participant inspected the referral and reply letters from the other six participants. The reply letters were anonymously peer reviewed by using a proforma containing agreed criteria in relation to appropriate factors to include in the reply letter. The reviewer also ranked the letter in relation to overall quality on a 1-10 point scale. RESULTS: It was found that the participants' letters generally conformed positively with the agreed criteria although there were some differences between individuals. There were particular problems identified in relation to tooth notation. Reply letters commonly used different forms of tooth notation to the referring practitioners. CONCLUSIONS: The ranking of the letters generally indicated that the participants' replies were judged to be favourable by their peers. There may be scope for continuing this study in relation to peer review by other groups of professionals, in particular practitioners in primary dental care.

Fibre-based post systems: a review.

OBJECTIVES: This article presents a review of published literature examining fibre-based endodontic post systems. DATA SOURCES: A MEDLINE search was carried out for any articles in dental journals pertaining to fibre-based post systems. Wherever possible articles cited were obtained from the journals and where this was not possible abstracts were obtained. Where no abstract was available the article was not considered for evaluation. DATA EXTRACTION: Articles were reviewed by a single observer and subject to meeting inclusion criteria were included in the review. Fifty-nine articles were considered suitable for inclusion. DATA SYNTHESIS: Articles were divided into categories and a subjective description of the articles was made. CONCLUSIONS: Review indicated that (1) most published literature on fibre-based posts took the form of laboratory analyses; (2) evidence for carbon-fibre posts far exceeds that for quartz-fibre posts; (3) laboratory evidence was contradictory and could not be used to inform practice reliably; (4) few clinical studies have been carried out though these have suggested fibre based posts may be clinically appropriate for restoration of the endodontically treated tooth; and (5) controlled prospective clinical trials evaluating fibre-based posts should be undertaken to inform use for clinical practice.

Reduction in intracanal bacteria during root canal preparation with and without apical enlargement.

AIM: To compare in vitro intracanal bacterial reduction using nickel-titanium rotary instruments with and without apical enlargement. METHODOLOGY: Thirty-eight palatal roots of maxillary molar teeth, with mature apices were subdivided according to lengths and then randomly assigned to two experimental and one control groups. The roots were sterilized and then reinfected with Enterococcus faecalis, which served as a bacteriological marker. All roots in the experimental groups were prepared in a step-down sequence with engine-driven GT rotary files at 350 rpm. In experimental group A (n = 16) additional apical enlargement to ISO size 35 was performed. In group B (n = 16) a serial step-back technique was followed with no apical enlargement. This was combined in groups A and B with irrigation with NaOCl and EDTA. In the control group (group C, n = 6) irrigation only was carried out, with no mechanical preparation. Samples were then taken from the root canals to determine the numbers of remaining bacteria. RESULTS: In groups A and B, 15 (94%) and 13 (81%) specimens were rendered bacteria-free, respectively. In the control group C none of the specimens were bacteria-free. There was a significant difference (P < 0.001) in the antibacterial effects of experimental and control regimens. There was, however, no significant difference (P = 0.276) between the preparation methods used in the experimental groups. CONCLUSIONS: There was no significant difference in intracanal bacterial reduction when Ni-Ti GT rotary preparation with NaOCl and EDTA irrigation was used with or without apical enlargement preparation technique. It may therefore not be necessary to remove dentine in the apical part of the root canal when a suitable coronal taper is achieved to allow satisfactory irrigation of the root canal system with antimicrobial agents.

The effectiveness of various disinfectants used as endodontic intracanal medications: an in vitro study.

The purpose of this study was to compare in vitro the suitability of four disinfectants as intracanal medications: calcium hydroxide, chlorhexidine gel, chlorhexidine in the form of a controlled-release delivery system (PerioChip), and the combination of chlorhexidine gel with calcium hydroxide. Saline was used as the control. The disinfectants were tested at three different time periods (3, 8, and 14 days) by using human tooth specimens that had been previously contaminated with Enterococcus faecalis. Calcium hydroxide worked very efficiently in killing E. faecalis in the 3-day group and 8-day group. It was not as effective in the 14-day group. The different chlorhexidine formulations were also found to be effective for all time periods. More specifically, the combination of chlorhexidine gel with calcium hydroxide and the chlorhexidine gel worked slightly better than the PerioChip, but there was no significant difference among the medications.

Molecular identification of microorganisms from endodontic infections.

A relatively wide range of bacteria have been isolated from root canals using standard culture techniques. However, only 50% of the bacteria in the oral cavity are cultivable (S. S. Socransky et al., Arch. Oral Biol. 8:278-280, 1963); hence, bacterial diversity in endodontic infections is underestimated. This study used a PCR-based 16S rRNA gene assay, followed by cloning and sequencing of 16S rRNA amplicons from a small subset of samples to assess the diversity of bacteria present in infected root canals. A total of 41 clinical samples from 15 de novo and 26 refractory cases of endodontic infections were assessed. Of these samples, 44% were positive by culture and 68% were positive by PCR. Eight samples were selected for further analysis. Of these, the two de novo cases yielded sequences related to those of the genera Enterococcus, Lactobacillus, Propionibacterium, and Streptococcus and two clones were related to previously uncultivated bacteria, while the sinus-associated, de novo case yielded sequences related to those of the genera Lactobacillus, Pantoea, Prevotella, and Selenomonas. The five refractory cases produced clones which were related to the genera Capnocytophaga, Cytophaga, Dialister, Eubacterium, Fusobacterium, Gemella, Mogibacterium, Peptostreptococcus, Prevotella, Propionibacterium, Selenomonas, Solobacterium, Streptococcus, and Veillonella and two clones representing previously uncultivated bacteria. The phylogenetic positions of several clones associated with the Clostridiaceae and Sporomusa subgroups of the Firmicutes grouping are also shown. This study demonstrates that molecular techniques can detect the presence of bacteria in endodontic infections when culture techniques yield a negative result and can be used to identify a wider range of endodontic-infection-related bacteria including the presence of previously unidentified or unculturable bacteria.

The influence of three Erbium:YAG laser energies on the in vitro microleakage of Class V compomer resin restorations.

OBJECTIVES: To investigate the influence of three Erbium:YAG pulse energies (200 mJ, 240 mJ, and 300 mJ with a 100 mJ dentine finish) on the microleakage of Class V compomer restorations (Compoglass). DESIGN: In vitro study. SAMPLE AND METHODS: Sixty-one extracted human premolar teeth were randomly allocated to three groups (according to pulse energy). Each tooth hosted one test cavity prepared with one of the three Er:YAG pulse energies using a pulse repetition rate of 5 Hz and a pulse duration of 250 microseconds, and one control cavity prepared with a conventional diamond bur in a high-speed hand piece. Both cavities were placed at the cervical margin of the tooth and were restored and finished according to the manufacturer's instructions. Each tooth was then stored in 0.12% thymol solution at 37 degrees C for three months, before being thermocycled through water baths between 5 degrees C and 55 degrees C for 240 cycles. Microleakage was assessed using a methylene blue dye penetration technique and was quantified using a score 0 (none) to 4 (to and into the axial wall). The data was analysed using the Kruskal-Wallis and Mann-Whitney U-tests. RESULTS: Leakage was seen in all groups at both the dentine and enamel margins. There were no statistically significant differences in leakage (P < 0.05) at either the enamel or dentine margins, except for the 240 mJ lased enamel margins. This group performed significantly better than the enamel margins prepared with 200 mJ (P = 0.03) and the 300/100 mJ (P = 0.01) laser energies as well as the conventionally prepared enamel margins (P < 0.001). CONCLUSION: Cavity preparation with this Erbium:YAG laser did not influence the microleakage of Compoglass restorations adversely. Different pulse energies were required for optimum cavity sealing at the enamel and dentine margins and for different materials.

The influence of specialty training and experience on decision making in endodontic diagnosis and treatment planning.

AIM: The purpose of this study was to compare the diagnostic and treatment-planning decision making of cohorts of dental surgeons with different experiences and specialty backgrounds. METHODOLOGY: Periapical radiographs of 20 teeth in patients referred for an opinion regarding the provision of endodontic surgical retreatment were taken using a paralleling technique and a film holder. The radiographs were photographed and black and white photographic prints produced to provide an image 10.5 times larger than the original radiograph. Each image was related to a clinical scenario. Each participant was asked to assess whether a periradicular lesion, as manifested by a radiolucency, was present and what clinical management would be prescribed. Ten participants in each of seven groups took part in the study. These groups were chosen to represent those dentists who were most likely to be involved in decision making in similar cases. RESULTS: In 12 out of 20 cases interobserver agreement for radiographic analysis was 'excellent' (above 90%) or 'good' (between 70 and 90%). There was less agreement for treatment decisions than for radiographic analysis and the order of agreement for cases for diagnosis was not the same as for treatment. No case achieved 'excellent' percentage interobserver agreement. The average percentage interobserver agreement of the endodontists was significantly greater than the average percentage interobserver agreement for the other groups for both radiographic assessment and treatment decisions. CONCLUSIONS: Differences in specialty backgrounds amongst the participants in this study affected both endodontic diagnostic and treatment decisions. Endodontists showed the most consistent agreement amongst the specialty groups.

Influence of Erbium:YAG laser energies on the microleakage of Class V resin-based composite restorations.

PURPOSE: To evaluate the influence of three Erbium:YAG laser energies on the microleakage of Class V resin-based composite restorations. MATERIALS AND METHODS: 60 extracted human premolar teeth stored in 0.12% thymol solution were randomly allocated to three groups. Buccal and lingual box-shaped Class V cavities were prepared on each tooth. One cavity served as the control and was cut using a conventional diamond bur in a high-speed handpiece. The test cavity was prepared using a pulse repetition rate of 5 Hz with 1 of 3 pulse energies; 200 mJ, 240 mJ, and 300 mJ with a 100 mJ dentin finish. The cavities were restored with Scotchbond Multi-Purpose and Z100 and were finished immediately before being stored for 3 months in thymol solution at 37 degrees C. Following thermocycling between 5 degrees C and 55 degrees C for 240 cycles and a further 12 hrs storage, the teeth were immersed in a 2% aqueous solution of methylene blue for 24 hrs. They were then sectioned through the mid-point of the restorations in a bucco-lingual plane and dye penetration was scored as 0 (none) to 4 (to the axial wall) for the enamel and dentin margins of both sections. The worst score for each margin was used for statistical analysis using the Kruskal Wallis and Mann-Whitney U tests at P < 0.05. RESULTS: When the lased groups were compared, optimum sealing was achieved with energies of at least 240 mJ at the enamel margin and with energies no higher than 200 mJ to finish the dentin margin. However, while all the pulse energies compared favorably to the control group in enamel, a similar result was found only using the 300 mJ, with 100 mJ, finish at the dentin margins.

Root canal treatment and general health: a review of the literature.

REVIEW: The focal infection theory was prominent in the medical literature during the early 1900s and curtailed the progress of endodontics. This theory proposed that microorganisms, or their toxins, arising from a focus of circumscribed infection within a tissue could disseminate systemically, resulting in the initiation or exacerbation of systemic illness or the damage of a distant tissue site. For example, during the focal infection era rheumatoid arthritis (RA) was identified as having a close relationship with dental health. The theory was eventually discredited because there was only anecdotal evidence to support its claims and few scientifically controlled studies. There has been a renewed interest in the influence that foci of infection within the oral tissues may have on general health. Some current research suggests a possible relationship between dental health and cardiovascular disease and published case reports have cited dental sources as causes for several systemic illnesses. Improved laboratory procedures employing sophisticated molecular biological techniques and enhanced culturing techniques have allowed researchers to confirm that bacteria recovered from the peripheral blood during root canal treatment originated in the root canal. It has been suggested that the bacteraemia, or the associated bacterial endotoxins, subsequent to root canal treatment, may cause potential systemic complications. Further research is required, however, using current sampling and laboratory methods from scientifically controlled population groups to determine if a significant relationship between general health and periradicular infection exists.

Calcium hydroxide pastes: classification and clinical indications.

REVIEW ARTICLE: Calcium hydroxide has been used in endodontology for many years. The aim of this paper is to review the various formulations of calcium hydroxide that have been described, with specific reference to the vehicle used to carry the compound. The requirements for a vehicle are described, and ex vivo and in vivo studies reviewed. Vehicles can be classified into aqueous, viscous and oily, the clinical properties of calcium hydroxide changing depending on the vehicle. The review also describes the use of various active components that have been added to calcium hydroxide, including antimicrobial and anti-inflammatory agents. This review will help clinicians to make informed judgements about which formulations of calcium hydroxide should be used for specific endodontic procedures.

Three-body wear associated with three ceramics and enamel.

STATEMENT OF PROBLEM: Wear of human enamel is a clinical concern whenever opposing teeth need to be restored using ceramic restorations. PURPOSE: This in vitro study investigated wear of human enamel and 3 dental ceramics: a conventional porcelain (Vitadur Alpha), a low-fusing hydrothermal ceramic (Duceram-LFC), and a machinable ceramic (Vita Mark II) in a 3-body wear test. MATERIAL AND METHODS: Thirty pairs of tooth-ceramic specimens were tested in a dental wear machine, under a standard load (40 N), rate (80 cycles/minute), and for 25,000 cycles in a simulated food slurry medium. Amount of wear was determined by measuring the height loss of the tooth and depth of wear track of the ceramic materials. Analysis of variance (ANOVA) was used to analyze the data, followed by Bonferroni multiple comparisons method to produce sets of simultaneous 95% confidence intervals. RESULTS: ANOVA revealed significant differences between the groups for both enamel wear (P =. 002) and ceramic wear (P <.001). Further comparisons (95% CI significance level) revealed that the difference in enamel wear produced by Alpha porcelain and Duceram-LFC ceramic material was not statistically significant, whereas that produced by Vita Mark II ceramic was significantly less. Vita Mark II ceramic was significantly more resistant to wear than Alpha porcelain and Duceram-LFC ceramic. Furthermore, Alpha porcelain was significantly more resistant to wear than Duceram-LFC ceramic. CONCLUSION: The abrasiveness of Alpha porcelain and Duceram-LFC ceramic was similar, yet both were significantly more abrasive than Vita Mark II ceramic. In addition, Vita Mark II was the most wear-resistant ceramic and Duceram-LFC ceramic the least resistant.

The effect of saliva on fluoride release by a glass-ionomer filling material.

The initial aim of this study was to investigate the effect of saliva and the formation of pellicle on the fluoride release in vitro of the glass-ionomer filling material, Chemfil Superior. For the first study glass-ionomer discs of 6 mm in diameter and 1.5 mm thick were made. Ten discs were immersed in whole stimulated saliva each day for 10 min and 10 control discs were immersed in deionized water. For the remaining 23 h and 50 min of each day, over the 20-day experimental period, both test and control discs were placed in deionized water. A considerable amount of fluoride was released on the first day (14.5 ppm F control and 13.3 ppm F test). The concentration of fluoride released on the second day fell sharply to 5.3 ppm F for controls and 4.9 ppm F for tests. This release had almost reached a plateau by day 10 and at day 20 the pellets continued to release low levels of fluoride. The concentration of fluoride released was only slightly higher for controls than for test discs when both were immersed in deionized water until day 20. However, during the 10-min period between 1.5 and 2 times as much fluoride was released into the deionized water as into saliva until day 20 when the ratio fell to 1.2:1. The second experiment assessed fluoride release when specimens were incubated for 1 h using an identical protocol. Again, less fluoride was released from the saliva-coated specimens compared with the controls (17%), which was not substantially different to the comparable 10-min samples (13%). This study indicates that saliva retards the release of fluoride from glass-ionomer and that this retarding effect is still present when discs are subsequently immersed in water compared with those that were placed in water alone. This suggests that salivary deposits have formed within minutes of immersion in saliva. This retarding effect was observed throughout the study period with the exception of the 20-day samples which had been incubated in saliva for 10 min.