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WITHDRAWN: Pulp management for caries in adults: maintaining pulp vitality.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

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 Planning Part 1: Assessing Complexity and Predicting Success.

Following a diagnosis of irreversible pulpal disease, periapical disease or failed endodontic therapy, the options for the tooth are extraction or root canal treatment. There is increasing evidence that certain factors may allow the clinician to predict the likely outcome of root canal therapy (RCT) and thus better inform the patient of the possible success rates. Should the patient choose root canal treatment, the clinician must also be able to gauge the potential difficulties that may be encountered and consequently determine whether it is within their competency. CPD/CLINICAL RELEVANCE: Assessing outcomes and complexity of care is an essential part of informed consent. Knowing when to refer is an essential component of best clinical practice.

Resistance to vertical fracture of MTA-filled roots.

AIM: To investigate the effect of MTA root canal fillings on the resistance to vertical root fracture (VRF) over different time intervals. MATERIAL AND METHODS: Freshly extracted anterior human teeth with single canals and minimal curvatures were decoronated, instrumented to size 50/.05 ProTaper file, irrigated with 1%NaOCl and randomly allocated to one of three groups (n = 36): (i) filled with MTA, (ii) filled with gutta-percha and sealer and (iii) unfilled roots used as a negative control. Each group was subdivided into three subgroups (n = 12) according to the storage time of 48 h, 1 and 6 months at 37°C in synthetic tissue fluid (STF). Following the storage periods, filled roots were mounted in acrylic supports, and the periodontal ligament was simulated using elastomeric impression material. Vertical loading was carried out with a ball-ended steel cylinder fitted on a universal testing machine at 1 mm/min crosshead speed. The maximum force at fracture (F-max) and the fracture mode were recorded for each root. RESULTS: Data were statistically analysed using two-way anova and Bonferroni post hoc tests. The mean F-max was significantly higher in the MTA subgroups after 1 and 6 months compared with all other subgroups. Two modes of fracture were identified: split and comminuted. The mean F-max values recorded with the latter were significantly higher compared with the former (P < 0.001). In all groups, split fracture was the most dominant mode apart from the MTA/1 month and MTA/6 month groups. CONCLUSION: MTA increases the resistance to VRF of endodontically treated teeth and influences the mode of fracture after 1 and 6 month of storage in STF compared with gutta-percha and sealer.

Endodontics and the older patient.

UNLABELLED: The number of elderly people in the population is rising and there is an increasing trend for tooth preservation. Older patients are more likely to have complex medical histories and/or physical disabilities. They are increasingly likely to retain their teeth, which could be heavily restored or broken down and root treatment may be challenging. In order to maintain teeth, a decision needs to be made as to whether or not to carry out endodontic treatment, which may be challenging in itself, and may also be associated with other age-related considerations. This paper considers endodontic issues related to the older patient, bearing in mind the plethora of considerations which may be relevant to root canal treatment. CLINICAL RELEVANCE: There are many benefits of retaining teeth, but there may be disadvantages.

A novel instrument to determine pulp proximity.

The aim was to determine whether extracted teeth could be used to test the Prepometer instrument, which indicates pulp proximity with green/amber/red light emitting diodes. Third molars were reduced to a plane in dentine and Prepometer readings made. Dentine was removed in 0.5 mm increments and readings made until only lights 9 or 10 (red) showed. The teeth were sectioned and the dentine thickness measured. Analysis permitted construction of a highly significant predictor-model (p < 0.01), the red/amber light boundary coinciding with a dentine thickness of 2.4 mm. The Prepometer was consistent in predicting pulp proximity but was more sensitive than specified.

Extended setting shrinkage behavior of endodontic sealers.

The aim of this study was to investigate the polymerization shrinkage behavior of newly introduced root canal sealers. Three recently developed sealers; EndoRez (dual cure resin-based), RealSeal (dual cure resin-based), and GuttaFlow (silicon-based) were tested and compared with TubliSeal (zinc oxide-eugenol-based). The bonded disk method was used. Sixty specimens were tested at body and room temperatures. Dual cure resin-based sealers were tested as chemically cured only and as dual cured. Samples were tested for 24 hours. It was found that there were statistically significant differences between the tested sealers. EndoRez had the highest shrinkage-strain value, followed by RealSeal, whereas TubliSeal had the lowest. GuttaFlow exhibited expansion on polymerization. It was concluded that shrinkage associated with setting might jeopardize the seal of the root canal, leading to root canal failure.

A two-stage shape optimization process for cavity preparation.

OBJECTIVES: Clinical data indicate that previously restored teeth are more likely to fracture under occlusal loads. The reason for this is attributed to the high stresses at the tooth-restoration interface, especially following debonding of the restoration from the tooth. This work aims to minimise these interfacial stresses by optimizing the cavity shape using modern shape optimisation techniques. METHODS: Shape optimisation methods based on the principle of biological adaptive growth were incorporated into a finite element program and used to optimize the design of cavity preparations as previous work had successfully used one such method to minimise stresses at the internal line angles of conventional restorations with defective bonds. The overall shapes of the cavity preparations were maintained while the profiles of the internal line angles were modified. In the present study, the overall shape of the cavity preparation was also subject to modification in the optimization process. A topological optimization method which placed the restorative material according to the stress distribution was first used to obtain a draft design for the cavity shape, assuming perfect bonding at the tooth-restoration interface. The draft shape was then refined using the method employed in the previous study, to allow for deterioration in the interfacial bond strength. These optimization methods were incorporated into the commercial finite element package ABAQUS as a User Material Subroutine (UMAT) to automate the optimization process. RESULTS: Compared with the conventional design, the stress level at the tooth-restoration interface in the optimized design was reduced significantly, irrespective of the bonding condition. CONCLUSIONS: Finite-element based shape optimization methods provide a useful tool for minimizing the interfacial stresses in dental restorations. The longevity of restored teeth using the optimized designs is therefore expected to be prolonged.

Time-dependence of coronal seal of temporary materials used in endodontics.

The aim of this in vitro study was to compare parametrically the coronal seal ability over different periods of times of four restorative materials used to seal the pulpal access cavity after endodontic treatment. One hundred and thirty-five mandibular premolars were divided randomly into three time groups (1, 2 and 4 weeks), each of which was in turn divided into four subgroups. Each subgroup was restored using one of four restorative materials: Coltosol, glass ionomer cement (GIC), zinc phosphate (ZP) cement, or intermediate restorative material (IRM) cement. The root canals were prepared using the crown-down technique, and obturated using lateral condensation. Following placement of the restorative material, the samples were incubated in distilled water at 37 degrees C and were subjected to 50 thermocycles (0 +/- 4, 56 +/- 4C). After immersing in (2%) methylene blue dye for 24 h, teeth were longitudinally sectioned and examined under a stereomicroscope. The results showed that Coltosol and GIC cement were significantly superior in sealing ability to ZP and IRM cements (P < 0.05). There was no significant difference between GIC cement and Coltosol. Both Coltosol and GIC after 1 week were significantly better than 4 weeks. There was no significant difference in the seal ability at different time periods when ZP and IRM cements were used.

Is a "flexible" glass fiber-bundle dowel system as retentive as a "rigid" quartz fiber dowel system?

PURPOSE: This study had two aims: (1) to compare the retention of a flexible directly placed fiber-bundle dowel system with that of a rigid prefabricated fiber-reinforced composite (FRC) dowel system, and (2) to determine the effect of decreasing the volume of luting cement around the flexible fiber-bundle dowels on the axial retention of the restorations. MATERIALS AND METHODS: Single-canal premolars (n = 36) were decoronated, cleaned, shaped, and prepared for both flexible and rigid dowels to a depth of 10 mm using a size 2 drill. The roots were then randomly allocated into three groups: Ia, Ib, and II (n = 12). Flexible fiber-bundle dowels were placed in groups Ia and Ib. These were available in three fiber-bundle diameters: small (0.9 mm), medium (1.2 mm), and large (1.5 mm). These bundles were luted in the root canals with Variolink II. The differences between Ia and Ib were in the ratio of the volume of fiber-bundles to the volume of luting cement and in the mode of application. Medium fiber-bundles were placed to the end of the preparation in groups Ia and Ib; however, in group Ia, a small diameter auxiliary bundle was placed, whereas in group Ib, a large-diameter auxiliary bundle was cut axially into strips of circa 0.2-mm thickness before being sequentially overlapped in placement. Roots in group II were restored with size 2 rigid prefabricated fiber dowels and luted with the light-cured cement provided by the manufacturer. After 24 hours of storage, axial tensile forces were applied to all luted dowels progressively to failure at 0.5 mm/min. Data were analyzed using a one-way analysis of variance (ANOVA) and the Bonferonni test. RESULTS: The mean axial resistance forces (standard deviation [SD]) for groups Ia, Ib, and II were not statistically different at 166 (49), 157 (36), and 151 (44) N, respectively (p > 0.05). CONCLUSIONS: There was no significant difference between the retention of the flexible fiber-bundle dowel system and that of the rigid prefabricated fiber dowel system. Decreasing the volume of luting cement around the flexible dowels did not have a significant effect on the axial retention of the restorations.

Effect of new obturating materials on vertical root fracture resistance of endodontically treated teeth.

The aim of this study was to compare vertical forces at fracture of teeth obturated with different materials. Single-rooted teeth were divided into five groups. The first group served as a negative control. The remaining four groups were shaped using ProTaper rotary files (Dentsply Maillefer, Ballaigues, Switzerland). The second group was obturated with gutta percha and a zinc oxide sealer. The third group was obturated with EndoRez points and EndoRez sealer (both from Ultradent, South Jordan, UT). The fourth group was obturated with Resilon (Pentron Clinical Technologies, Wallingford, CT) and RealSeal sealer (Pentron Clinical Technologies). The fifth group was obturated with Guttaflow (Colténe/Whaledent, Altstätten, Switzerland). Roots were then fixed into a universal testing machine and loaded with a spreader until fracture. It was found that forces at fracture were statistically significantly higher in the Resilon and EndoRez groups. It was concluded that obturation of roots with resin-based obturation materials (Resilon and EndoRez) increased the resistance of root canal filled teeth to vertical root fracture.

Structural optimization of dental restorations using the principle of adaptive growth.

OBJECTIVES: In a restored tooth, the stresses that occur at the tooth-restoration interface during loading could become large enough to fracture the tooth and/or restoration and it has been estimated that 92% of fractured teeth have been previously restored. The tooth preparation process for a dental restoration is a classical optimization problem: tooth reduction must be minimized to preserve tooth tissue whilst stress levels must be kept low to avoid fracture of the restored unit. The objective of the present study was to derive alternative optimized designs for a second upper premolar cavity preparation by means of structural shape optimization based on the finite element method and biological adaptive growth. METHODS: Three models of cavity preparations were investigated: an inlay design for preparation of a premolar tooth, an undercut cavity design and an onlay preparation. Three restorative materials and several tooth/restoration contact conditions were utilized to replicate the in vitro situation as closely as possible. The optimization process was run for each cavity geometry. RESULTS: Mathematical shape optimization based on biological adaptive growth process was successfully applied to tooth preparations for dental restorations. Significant reduction in stress levels at the tooth-restoration interface where bonding is imperfect was achieved using optimized cavity or restoration shapes. In the best case, the maximum stress value was reduced by more than 50%. SIGNIFICANCE: Shape optimization techniques can provide an efficient and effective means of reducing the stresses in restored teeth and hence has the potential of prolonging their service lives. The technique can easily be adopted for optimizing other dental restorations.

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.

Randomized clinical comparison of endodontically treated teeth restored with amalgam or with fiber posts and resin composite: five-year results.

Prospective clinical studies comparing the results of different types of restorations of endodontically treated teeth are lacking. This study compared the clinical success rate of endodontically treated premolars restored with fiber posts and direct composite to the restorations of premolars using amalgam. Premolars with Class II carious lesions were selected and randomly assigned to one of two experimental groups: (1) restoration with amalgam or (2) restoration with fiber posts and composite. One hundred and nine teeth were included in Group 1 and 110 in Group 2. Patients were recalled after 1, 3 and 5 years. No statistically significant difference was found between the proportion of failed teeth in the two experimental groups. Significant differences were observed between the proportion of root fractures (p=0.029) and caries (p=0.047), with more root fractures and less caries observed in the teeth restored with amalgam at the five-year recall. Within the limits of this study, it can be concluded that restorations with fiber posts and composite were found to be more effective than amalgam in preventing root fractures but less effective in preventing secondary caries.

A comparison of the retention of tooth-colored posts.

OBJECTIVE: The aim of this in vitro study was to compare the retention of five different esthetic post systems of similar dimensions in extracted teeth using titanium posts as controls. METHOD AND MATERIALS: Sixty recently extracted single-rooted, caries-free teeth were sectioned horizontally and mounted in acrylic resin. The samples were randomly allocated into six groups of 10 for post preparation. Post space preparation was carried out according to the individual manufacturer's instructions. All posts were bonded using Panavia F. A 4-mm hollow, metal sleeve was luted over the free end of each post prior to mounting in a universal testing machine, and the forces required to dislodge the posts using a cross-head speed of 5 mm/min were recorded. RESULTS: It was found that the parallel-sided Lightposts were significantly more retentive than all of the other posts. Parapost Fibrewhite posts were more retentive than tapered Lightposts and Snowposts. There was no significant difference between the retention of stainless steel Paraposts and any of the other groups. CONCLUSIONS: Serrated parallel-sided stainless steel posts were no more retentive than either parallel-sided or tapered tooth-colored posts in this study. When all groups were considered, post dimension appeared to influence retention, with parallel-sided posts being more retentive than tapered posts.

Effect of thermocycling on the retention of glass-fiber root canal posts.

OBJECTIVE: This study investigated the effects of thermocycling on the retention of glass-fiber and resin posts. METHOD AND MATERIALS: Forty premolar and canine tooth roots were embedded in acrylic blocks shaped to fit into a retention device. The roots were randomly assigned to two groups of 20 to receive either Lightposts or Luscent Anchors which were cemented into 9-mm-deep post spaces, with Panavia F resin cement. Each group was randomly divided into two equal subgroups: one for thermocycling, and the other to serve as a control. The thermocycled specimens were cycled 3,000 times between water baths at 5 degrees C and 55 degrees C, with a dwell time of 60 seconds in each. Control specimens were stored at 37 degrees C. The tensile force required to dislodge each post from its root was recorded and the data analyzed using Student's t tests. RESULTS: There were no significant differences in the forces required to cause post-retention failure between the control and thermocycled specimens. Lightposts were significantly more retentive than Luscent Anchors without thermocycling, but this distinction was not apparent in the thermocycled groups. CONCLUSION: Glass-fiber and resin posts cemented with resin cement offer acceptable levels of retention and are not susceptible to reduced retention from thermocycling. Thermocycling should be given less emphasis in tests for the retention of root canal posts cemented with resin cements.

Comparison of two methods for the removal of root canal posts.

OBJECTIVE: To compare the application of ultrasound with the use of an engine-driven trephine bur to remove parallel-sided root canal posts. METHOD AND MATERIALS: Single-rooted human canine teeth were decoronated and prepared to receive preformed titanium posts. The posts were cemented with Panavia F resin cement. Ten teeth acted as controls, 10 had a 4-mm-deep gutter cut around the post using a Masserann trephining bur, and 10 were subjected to 10 minutes of ultrasound. The forces required to dislodge the posts were determined using a universal testing machine, and the data were analyzed using analysis of variance. RESULTS: The only significant difference was between the trephined and ultrasonically energized groups, with the ultrasonic group requiring greater forces for dislodgement. CONCLUSION: Resin composite cement could be removed from around the posts with the trephine bur but with considerable difficulty, and neither method of dislodging the posts was effective.