Effectiveness of D,L-2-hydroxyisocaproic acid (HICA) and alpha-mangostin against endodontopathogenic microorganisms in a multispecies bacterial-fungal biofilm in an ex vivo tooth model

AIM

To develop a defined multispecies root canal biofilm model ex vivo, and to perform viable compositional analysis following D,L-2-hydroxyisocaproic acid (HICA), alpha-mangostin, Calcicur^® , and Odontopaste^® exposure.

METHODOLOGY

Time-kill assays were conducted in vitro using HICA, alpha-mangostin, Calcicur^® , Odontopaste^® , and saline solution on the planktonic cultures of C. albicans, E. faecalis, L. rhamnosus, and S. gordonii. Human root dentine blocks were prepared (n = 100) ex vivo, and multispecies suspensions containing each of 1.5 × 10⁸  CFU/mL C. albicans, E. faecalis, L. rhamnosus, and S. gordonii in brain heart infusion (BHI) were incubated within the root canals for 21 days. Canals (n = 20/group) were then exposed to medicaments for 7 days. Samples taken from the inner (first 0.1 mm) and deeper (second 0.1 mm) dentine by drilling with Ash Steel Burs No. 5 and No. 6, and residual roots were cultured in broth for 24 h. Cell growth was detected by spectrophotometry and confirmed by culture on agar. The other set of inner dentine, deeper dentine, and residual root samples were sonicated, and then exposed with 50 μM PMA before DNA was extracted using the QIAamp DNA mini kit. Real-time quantitative PCR was performed to determine the biofilm composition as well as the number of live and total cells remaining in the biofilm following each treatment. The OD data were analysed with Kruskal-Wallis and Friedman with Wilcoxon signed-rank test between and within groups, respectively, agar culture and qPCR data with Pearson chi-square with Mann-Whitney and Cochran with McNemar tests, respectively (p < .0001).

RESULTS

Time-kill assays revealed that HICA and Calcicur^® killed all planktonic organisms within 24 h, whilst alpha-mangostin killed the organisms within 72 h. However, Odontopaste^® was a slow-killing agent: 10 cells of planktonic organisms survived after exposure to the agent for 7 days. The ex vivo tooth model demonstrated that HICA and alpha-mangostin significantly inhibited the cell growth in all sampling depths (p < .0001). All species-specific data revealed the effectiveness of each medicament on the biofilm composition.

CONCLUSIONS

D,L-2-hydroxyisocaproic acid and alpha-mangostin had antimicrobial activity against multispecies bacterial-fungal biofilms.

WITHDRAWN: Pulp management for caries in adults: maintaining pulp vitality

BACKGROUND

There is a range of treatment options for the management of the pulp in extensively decayed teeth. These include direct and indirect pulp capping, pulpotomy or pulpectomy. If the tooth is symptomatic or if there are periapical bone changes, then endodontic treatment is required. However, if the tooth is asymptomatic but the caries is extensive, there is no consensus as to the best method of management. In addition, there has been a recent move towards using alternative materials and methods such as the direct or indirect placement of bonding agents and mineral trioxide aggregate.Most studies have investigated the management of asymptomatic carious teeth with or without an exposed dental pulp using various capping materials (e.g. calcium hydroxide, Ledermix, Triodent, Biorex, etc.). However, there is no long term data regarding the outcome of management of asymptomatic, carious teeth according to different regimens.

OBJECTIVES

This study aims to assess the effectiveness of techniques used to treat asymptomatic carious teeth and maintain pulp vitality.

SEARCH METHODS

Electronic searches of the following databases were undertaken: The Cochrane Oral Health Group's Trials Register (March 2006), the Cochrane Central Register of Controlled Trials (CENTRAL) (The Cochrane Library 2006, Issue 1), MEDLINE (1966 to week 4, February 2006), EMBASE (1974 to 13 March 2006), National Research Register (March 2006), Science Citation Index - SCISEARCH (1981 to March 2006). Detailed search strategies were developed for each database. Handsearching and screening of reference lists were undertaken. There was no restriction with regard to language of publication.

SELECTION CRITERIA

Studies included were randomised controlled trials (RCTs). Asymptomatic vital permanent teeth with extensive caries were included. Studies were those which compared techniques to maintain pulp vitality. Outcome measures included clinical success and adverse events.

DATA COLLECTION AND ANALYSIS

Data were independently extracted by three review authors. Authors were contacted for details of randomisation and withdrawals and a quality assessment was carried out. The Cochrane Collaboration's statistical guidelines were followed.

MAIN RESULTS

Only four RCTs were identified. Interventions examined included: Ledermix, glycerrhetinic acid/antibiotic mix, zinc oxide eugenol, calcium hydroxide, Cavitec, Life, Dycal, potassium nitrate, dimethyl isosorbide, and polycarboxylate cement. Only one study showed a statistically significant finding; potassium nitrate/dimethyl isosorbide/polycarboxylate cement resulted in fewer clinical symptoms than potassium nitrate/polycarboxylate cement or polycarboxylate cement alone when used as a capping material for carious pulps.

AUTHORS' CONCLUSIONS

It was disappointing that there were so few studies which could be considered as being suitable for inclusion in this review. The findings from this review do not suggest that there should be any significant change from accepted conventional practice procedures when the pulp of the carious tooth is considered. Further well designed RCTs are needed to investigate the potential of contemporary materials which may be suitable when used in the management of carious teeth. It is recognised that it is difficult to establish the 'ideal' clinical study when ethical approval for new materials must be sought and strict attention to case selection, study protocol and interpretation of data is considered. It is also not easy to recruit sufficient numbers of patients meeting the necessary criteria.

Modern Endodontic Principles. Part 6: Managing Complex Situations

Clinicians are often faced with endodontic cases that are significantly more challenging than the primary root canal treatment of mature adult teeth. This paper outlines some of the common treatment modalities which can be employed in situations in which either primary treatment has failed, or there is iatrogenic damage or unusual anatomy. CPD/Clinical Relevance: This paper will provide the reader with advice and techniques for undertaking orthograde endodontic retreatment, hemisection, endodontic surgery and management of teeth with incompletely formed roots.

Modern Endodontic Principles. Part 8: The Future of Endodontics

Although the principles of endodontics have remained unchanged for many decades, root canal treatment has been subject to major changes in the past few years. This paper outlines the cutting-edge advances including the materials and techniques used. CPD/Clinical Relevance: This article provides an overview of bioactive materials and insight into regenerative endodontics, vital pulp therapy and intentional replantation.

Modern Endodontic Principles Part 7: The Restorative Interface

The restoration of endodontically-treated teeth is a topic that has been extensively studied and yet remains controversial. The endodontically-treated tooth can be restored with a wide range of techniques of varying complexity. This article reviews the literature on this topic. Consideration is given to the ferrule and its importance in achieving success. Furthermore, consideration will be given to the use of endodontically-treated teeth as abutments for fixed and removable prostheses and the challenges this presents. Clinical recommendations are presented as guidelines to improve the predictability and outcome of treatment when restoring structurally compromised root-filled teeth. Clinical relevance: The prognosis of endodontically-treated teeth depends not only on the success of the endodontic treatment, but also on the type of reconstruction.

Root Resorption: Simplifying Diagnosis and Improving Outcomes

Root resorption is a condition resulting in the progressive loss of dental hard tissue. It may occur both within the root and upon the external aspect of the root. Diagnosis can be difficult and management challenging. Understanding the pathology is critical to understanding why and when this disease occurs and what the best management techniques involve. With such knowledge practitioners can confidently diagnose resorption, discuss prognoses and management strategies with the patient and either refer or begin treatment. Early intervention is paramount in improving outcomes. As such, if practitioners choose to refer patients they must be aware of what can be done immediately to mitigate risks until consultation and specialist treatment begins.

A laboratory evaluation of the physical and mechanical properties of selected root canal sealers

AIM

To evaluate and compare the porosity, degree of conversion (DC) and hardness of two resin-based sealers; RealSeal and EndoRez, and a silicon-based sealer; GuttaFlow to that of a traditional zinc oxide-based sealer; TubliSeal.

METHODOLOGY

For porosity, four samples from each sealer were prepared and scanned using a SkyScan 1072 Micro-CT. Porosity was then calculated using specialized software. For DC, 10 samples from each sealer were prepared and placed onto a Fourier transform infrared spectroscopy spectrometer. Spectra readings were carried out before and after curing of the sealers, and the DC for each sealer was calculated. For hardness, 10 samples from each sealer were prepared and then tested using a Wallace hardness tester. SPSS software was used for statistical analysis of the data using one-way anova and independent t-tests.

RESULTS

TubliSeal had the highest percentage porosity (3.52%), whilst RealSeal had the lowest percentage porosity (0.41%). Statistically significant differences (P = 0.01) in porosity were present between all groups except between RealSeal and EndoRez groups. RealSeal exhibited a significantly higher DC% than EndoRez (P = 0.01), whereas EndoRez had the highest hardness number [28.54 Vickers hardness number (VHN)] whilst TubliSeal showed the lowest (13.57 VHN). Statistically significant differences in hardness were found between all groups (P = 0.01) except between RealSeal and EndoRez groups.

CONCLUSIONS

Resin-based sealers had less porosity, greater hardness and a high DC.

The use of outreach clinics for teaching undergraduate restorative dentistry

AIM

To examine the experience of being an outreach teacher of undergraduate restorative dentistry; to describe the desirable characteristics of such teachers; and to consider the management of outreach teaching.

DESIGN

A three year pilot of an outreach course in fourth year restorative dentistry began in 2001. Students spent one day per week treating adults in NHS community dental clinics, run by Primary Care Trusts (PCTs). Action research involved monitoring meetings with students, clinic staff (dental teachers and nurses), and PCT clinical service managers. These data are supplemented by an independent evaluation involving interviews with dental school academic staff, and an account by an outreach teacher.

RESULTS

Outreach is a different and more demanding context for teaching restorative dentistry than the dental hospital, characterised by isolation, management responsibility, pressure, a steep learning curve, and stress. The desirable characteristics of outreach teachers are those which enable them to cope in this environment, together with a student-centred teaching style, and the appropriate knowledge. Management of teaching passed to the PCTs and this created an additional workload for them in relation to staffing, risk, and service-based issues. Four teaching surgeries were the maximum for a satisfactory level of patient care and student supervision. A key issue for the dental school is quality. The changes to teaching and the teaching environment introduced during and after the pilot to address problems identified are described.

CONCLUSION

In developing facilities to enable students to benefit from the advantages of outreach, dental schools should recognise that the characteristics of the outreach environment need to be taken into account during planning, that staff selection is a critical success factor, and that an ongoing proactive approach to organisational arrangements and to the support of teaching staff is necessary.

Pulp management for caries in adults: maintaining pulp vitality

BACKGROUND

There is a range of treatment options for the management of the pulp in extensively decayed teeth. These include direct and indirect pulp capping, pulpotomy or pulpectomy. If the tooth is symptomatic or if there are periapical bone changes, then endodontic treatment is required. However, if the tooth is asymptomatic but the caries is extensive, there is no consensus as to the best method of management. In addition, there has been a recent move towards using alternative materials and methods such as the direct or indirect placement of bonding agents and mineral trioxide aggregate. Most studies have investigated the management of asymptomatic carious teeth with or without an exposed dental pulp using various capping materials (e.g. calcium hydroxide, Ledermix, Triodent, Biorex, etc.). However, there is no long term data regarding the outcome of management of asymptomatic, carious teeth according to different regimens.

OBJECTIVES

This study aims to assess the effectiveness of techniques used to treat asymptomatic carious teeth and maintain pulp vitality.

SEARCH STRATEGY

Electronic searches of the following databases were undertaken: The Cochrane Oral Health Group's Trials Register (March 2006), the Cochrane Central Register of Controlled Trials (CENTRAL) (The Cochrane Library 2006, Issue 1), MEDLINE (1966 to week 4, February 2006), EMBASE (1974 to 13 March 2006), National Research Register (March 2006), Science Citation Index - SCISEARCH (1981 to March 2006). Detailed search strategies were developed for each database. Handsearching and screening of reference lists were undertaken. There was no restriction with regard to language of publication.

SELECTION CRITERIA

Studies included were randomised controlled trials (RCTs). Asymptomatic vital permanent teeth with extensive caries were included. Studies were those which compared techniques to maintain pulp vitality. Outcome measures included clinical success and adverse events.

DATA COLLECTION AND ANALYSIS

Data were independently extracted by three review authors. Authors were contacted for details of randomisation and withdrawals and a quality assessment was carried out. The Cochrane Oral Health Group's statistical guidelines were followed.

MAIN RESULTS

Only four RCTs were identified. Interventions examined included: Ledermix, glycerrhetinic acid/antibiotic mix, zinc oxide eugenol, calcium hydroxide, Cavitec, Life, Dycal, potassium nitrate, dimethyl isosorbide, and polycarboxylate cement. Only one study showed a statistically significant finding; potassium nitrate/dimethyl isosorbide/polycarboxylate cement resulted in fewer clinical symptoms than potassium nitrate/polycarboxylate cement or polycarboxylate cement alone when used as a capping material for carious pulps.

AUTHORS' CONCLUSIONS

It was disappointing that there were so few studies which could be considered as being suitable for inclusion in this review. The findings from this review do not suggest that there should be any significant change from accepted conventional practice procedures when the pulp of the carious tooth is considered. Further well designed RCTs are needed to investigate the potential of contemporary materials which may be suitable when used in the management of carious teeth. It is recognised that it is difficult to establish the 'ideal' clinical study when ethical approval for new materials must be sought and strict attention to case selection, study protocol and interpretation of data is considered. It is also not easy to recruit sufficient numbers of patients meeting the necessary criteria.

Antimicrobial activity of varying concentrations of sodium hypochlorite on the endodontic microorganisms Actinomyces israelii, A. naeslundii, Candida albicans and Enterococcus faecalis

AIM

To determine the resistance of microorganisms associated with refractory endodontic infections to sodium hypochlorite used as a root canal irrigant.

METHODOLOGY

Two strains each of Actinomyces naeslundii, Candida albicans and Enterococcus faecalis were tested as late logarithmic phase inocula, against sodium hypochlorite adjusted to 0.5, 1.0, 2.5 and 5.25% w/v. Contact times used were 0, 10, 20, 30, 60 and 120 s. In the case of E. faecalis, additional experiments used contact times of 1.0, 2.0, 5.0, 10.0 and 30.0 min. Anti-microbial action was halted by sodium thiosulphate addition. Survivors were measured primarily using viable counts on drop plates. Additionally, pour plates were used to count low colony-forming units (cfu) and dilutions to 10(-6) were used to count high cfu.

RESULTS

All concentrations of NaOCl lowered cfu below the limit of detection after 10 s in the case of A. naeslundii and C. albicans. However, E. faecalis proved to be more resistant to NaOCl. Using 0.5% NaOCl for 30 min reduced cfu to zero for both strains tested. This compares with 10 min for 1.0%, 5 min for 2.5% and 2 min for 5.25% (P < 0.001). Regression analysis for the dependent variable log(e)(count + 1) with log(e)(time + 1) and concentration as explanatory variables gave rise to a significant interaction between time and concentration (P < 0.001).

CONCLUSION

The published association of E. faecalis with refractory endodontic infection may result, at least partially, from high resistance of this species to NaOCl. This does not appear to be the case with A. naeslundii or C. albicans.

Antimicrobial activity of varying concentrations of sodium hypochlorite on the endodontic microorganisms Actinomyces israelii, A. naeslundii, Candida albicans and Enterococcus faecalis

AIM

To determine the resistance of microorganisms associated with refractory endodontic infections to sodium hypochlorite used as a root canal irrigant.

METHODOLOGY

Two strains each of Actinomyces naeslundii, Candida albicans and Enterococcus faecalis were tested as late logarithmic phase inocula, against sodium hypochlorite adjusted to 0.5, 1.0, 2.5 and 5.25% w/v. Contact times used were 0, 10, 20, 30, 60 and 120 s. In the case of E. faecalis, additional experiments used contact times of 1.0, 2.0, 5.0, 10.0 and 30.0 min. Anti-microbial action was halted by sodium thiosulphate addition. Survivors were measured primarily using viable counts on drop plates. Additionally, pour plates were used to count low colony-forming units (cfu) and dilutions to 10(-6) were used to count high cfu.

RESULTS

All concentrations of NaOCl lowered cfu below the limit of detection after 10 s in the case of A. naeslundii and C. albicans. However, E. faecalis proved to be more resistant to NaOCl. Using 0.5% NaOCl for 30 min reduced cfu to zero for both strains tested. This compares with 10 min for 1.0%, 5 min for 2.5% and 2 min for 5.25% (P < 0.001). Regression analysis for the dependent variable log(e)(count + 1) with log(e)(time + 1) and concentration as explanatory variables gave rise to a significant interaction between time and concentration (P < 0.001).

CONCLUSION

The published association of E. faecalis with refractory endodontic infection may result, at least partially, from high resistance of this species to NaOCl. This does not appear to be the case with A. naeslundii or C. albicans.