Enhanced NHS endodontic services in England: a postcode lottery?

Aim To investigate the consistency of commissioning and provision of enhanced NHS endodontic services across England.Methods The level of provision for enhanced endodontic services was sought using two methods. An electronic questionnaire was distributed to each of the thirteen director of commissioning operations (DCO) teams in NHS England to determine the perception from commissioners of what endodontic services are currently provided and commissioned. A systematic search to assess what is advertised by enhanced endodontic providers was also carried out to cross-reference with the information gained from electronic questionnaires.Results A 77% response rate to the questionnaire was achieved. Eight out of the ten DCO teams that replied provided enhanced NHS endodontics to a greater or lesser extent, one did not and one was unsure. Three teams did not respond. Providers of services included dentists with enhanced skills, endodontic specialists, and dentists working within district or dental hospitals. Five out of ten DCO teams commissioned level two services and six commissioned level three services. Dental hospital acceptance criteria for enhanced endodontics differ regionally, but most accept level three and some level two complexity treatments, depending upon capacity at the time.Conclusions This investigation demonstrates that although the majority of NHS commissioning areas within England provide enhanced endodontic services, these are not the same across the country. Therefore, patients are not getting equal access to services and it may vary depending upon location.

X-ray scattering evaluation of ultrastructural changes in human dental tissues with thermal treatment.

Micro- and ultrastructural analysis of burned skeletal remains is crucial for obtaining a reliable estimation of cremation temperature. Earlier studies mainly focused on heat-induced changes in bone tissue, while this study extends this research to human dental tissues using a novel quantitative analytical approach. Twelve tooth sections were burned at 400-900°C (30-min exposure, increments of 100°C). Subsequent combined small- and wide-angle X-ray scattering (SAXS/WAXS) experiments were performed at the Diamond Light Source synchrotron facility, where 28 scattering patterns were collected within each tooth section. In comparison with the control sample, an increase in mean crystal thickness was found in burned dentine (2.8-fold) and enamel (1.4-fold), however at a smaller rate than reported earlier for bone tissue (5-10.7-fold). The results provide a structural reference for traditional X-ray scattering methods and emphasize the need to investigate bone and dental tissues separately to obtain a reliable estimation of cremation temperature.

Reciprocating root canal technique induces greater debris accumulation than a continuous rotary technique as assessed by 3-dimensional micro-computed tomography.

INTRODUCTION: The ability of single-file, reciprocating instruments to remove inorganic debris is uncertain. By using micro-computed tomography (microCT), this study compared the 3-dimensional distribution, quantity, and density of remaining inorganic debris in the mesial root of mandibular molars after instrumentation. A single reciprocating file was compared with a multifile rotary instrumentation technique. METHODS: Teeth were selected for instrumentation using reciprocating or rotary instruments (n = 19). Teeth were scanned using microCT before and after instrumentation. Through shape recognition and superimposition image analysis techniques, remaining inorganic tissue debris was identified, quantified, and visualized 3-dimensionally, mapping debris to its location. The use of a density phantom enabled the debris density to be calculated, giving a measure of compactness. RESULTS: After single-file instrumentation, an average of 19.5% debris remained in the canal compared with 10.6% with the multifile technique (P = .01) and at an average density of 1.60 g/m(3) compared with 1.55 g/m(3) for the multifile system (P > .05). Isthmuses, protrusions, and irregularities in the canal wall were repeatedly seen at the locations of debris accumulation. CONCLUSIONS: In canals with a high prevalence of isthmuses and protrusions, using multifile rotary systems may be preferred over reciprocating files because it can yield cleaner canals with less debris accumulation.

Multiscale modelling and diffraction-based characterization of elastic behaviour of human dentine.

Human dentine is a hierarchical mineralized tissue with a two-level composite structure, with tubules being the prominent structural feature at a microlevel, and collagen fibres decorated with hydroxyapatite (HAp) crystallite platelets dominating the nanoscale. Few studies have focused on this two-level structure of human dentine, where the response to mechanical loading is thought to be affected not only by the tubule volume fraction at the microscale, but also by the shape and orientation distribution of mineral crystallites, and their nanoscale spatial arrangement and alignment. In this paper, in situ elastic strain evolution within HAp in dentine subjected to uniaxial compressive loading along both longitudinal and transverse directions was characterized simultaneously by two synchrotron X-ray scattering techniques: small- and wide-angle X-ray scattering (SAXS and WAXS, respectively). WAXS allows the evaluation of the apparent modulus linking the external load to the internal HAp crystallite strain, while the nanoscale HAp distribution and arrangement can be quantified by SAXS. We proposed an improved multiscale Eshelby inclusion model that takes into account the two-level hierarchical structure, and validated it with a multidirectional experimental strain evaluation. The agreement between the simulation and measurement indicates that the multiscale hierarchical model developed here accurately reflects the structural arrangement and mechanical response of human dentine. This study benefits the comprehensive understanding of the mechanical behaviour of hierarchical biomaterials. The knowledge of the mechanical properties related to the hierarchical structure is essential for the understanding and predicting the effects of structural alterations that may occur due to disease or treatment on the performance of dental tissues and their artificial replacements.

Hepatocyte growth factor is sequestered in dentine matrix and promotes regeneration-associated events in dental pulp cells.

Extracellular matrix of dentine contains a rich cocktail of soluble cytokines and growth factors which mediate wound repair of the dentine-pulp complex. Hepatocyte growth factor (HGF) is a mesenchyme derived growth factor regulating a broad range of physiological processes including tissue development and regeneration. In this study, we have investigated the sequestration of HGF in the dentine matrix and analysed its action as a chemokine in the induction of differentiation and mineral deposition in pulp derived cells in vitro. Using ELISA, the presence of HGF was demonstrated in solubilised fractions of dentine matrix released by the therapeutic pulp repair materials of white and grey mineral trioxide aggregate. HGF was shown to be a chemo-attractant for primary rat dental pulp cells (RDPCs) in transwell assays highlighting its potential in progenitor cell recruitment during dentine-pulp tissue repair. Transcription factors Osterix and Runx2, and genes encoding for Osteopontin and Osteocalcin, were up-regulated in HGF-exposed RDPC cultures compared with controls. Adenoviral-mediated expression of HGF in RDPCs or exposure to recombinant HGF induced mineral secretion in RDPCs which was significantly greater than controls. The receptor of HGF, c-Met was also detected within human dental pulp indicating the potential for HGF released from dentine matrix to contribute to cellular signalling events following tissue injury. Combined, these data suggest that HGF is important in the repair of the dentine-pulp complex potentially participating in several aspects of wound healing.

An analytical Micro CT methodology for quantifying inorganic dentine debris following internal tooth preparation.

OBJECTIVES: MicroCT allows the complex canal network of teeth to be mapped but does not readily distinguish between structural tissue (dentine) and the debris generated during cleaning. The aim was to introduce a validated approach for identifying debris following routine instrumentation and disinfection. METHODS: The mesial canals of 12 mandibular molars were instrumented, and irrigated with EDTA and NaOCl. MicroCT images before and after instrumentation and images were assessed qualitatively and quantitatively. RESULTS: Debris in the canal space was identified through morphological image analysis and superimposition of the images before and after instrumentation. This revealed that the removal of debris is prohibited by protrusions and micro-canals within the tooth creating areas which are inaccessible to the irrigant. Although the results arising from the analytical methodology did provide measurements of debris produced, biological differences in the canals resulted in variances. Both irrigants reduced debris compared to the control which decreased with EDTA and further with NaOCl. However, anatomical variation did not allow definitive conclusions on which irrigant was best to use although both reduced debris build up. CONCLUSIONS: This work presents a new approach for distinguishing between debris and structural inorganic tissue in root canals of teeth. The application may prove useful in other calcified tissue shape determination. CLINICAL SIGNIFICANCE: Remaining debris may contain bacteria and obstruct the flow of irrigating solutions into lateral canal anatomy. This new approach for detecting the amount of remaining debris in canal systems following instrumentation provides a clearer methodology of the identification of such debris.

Analyzing endosonic root canal file oscillations: an in vitro evaluation.

INTRODUCTION: Passive ultrasonic irrigation may be used to improve bacterial reduction within the root canal. The technique relies on a small file being driven to oscillate freely within the canal and activating an irrigant solution through biophysical forces such as microstreaming. There is limited information regarding a file's oscillation patterns when operated while surrounded by fluid as is the case within a canal root. METHODS: Files of different sizes (#10 and #30, 27 mm and 31 mm) were connected to an ultrasound generator via a 120 degrees file holder. Files were immersed in a water bath, and a laser vibrometer set up with measurement lines superimposed over the files. The laser vibrometer was scanned over the oscillating files. Measurements were repeated 10 times for each file/power setting used. RESULTS: File mode shapes are comprised of a series of nodes/antinodes, with thinner, longer files producing more antinodes. The maximum vibration occurred at the free end of the file. Increasing generator power had no significant effect on this maximum amplitude (p > 0.20). Maximum displacement amplitudes were 17 to 22 microm (#10 file, 27 mm), 15 to 21 microm (#10 file, 31 mm), 6 to 9 microm (#30 file, 27 mm), and 5 to 7 microm (#30, 31 mm) for all power settings. Antinodes occurring along the remaining file length were significantly larger at generator power 1 than at powers 2 through 5 (p < 0.03). CONCLUSIONS: At higher generator powers, energy delivered to the file is dissipated in unwanted vibration resulting in reduced vibration displacement amplitudes. This may reduce the occurrence of the biophysical forces necessary to maximize the technique's effectiveness.

The flexural properties of endodontic post materials.

OBJECTIVES: To measure the flexural strengths and moduli of endodontic post materials and to assess the effect on the calculated flexural properties of varying the diameter/length (D/L) ratio of three-point bend test samples. METHODS: Three-point bend testing of samples of 2mm diameter metal and fiber-reinforced composite (FRC) rods was carried out and the mechanical properties calculated at support widths of 16 mm, 32 mm and 64 mm. Weibull analysis was performed on the strength data. RESULTS: The flexural strengths of all the FRC post materials exceeded the yield strengths of the gold and stainless steel samples; the flexural strengths of two FRC materials were comparable with the yield strength of titanium. Stainless steel recorded the highest flexural modulus while the titanium and the two carbon fiber materials exhibited similar values just exceeding that of gold. The remaining glass fiber materials were of lower modulus within the range of 41-57 GPa. Weibull modulus values for the FRC materials ranged from 16.77 to 30.09. Decreasing the L/D ratio produced a marked decrease in flexural modulus for all materials. SIGNIFICANCE: The flexural strengths of FRC endodontic post materials as new generally exceed the yield strengths of metals from which endodontic posts are made. The high Weibull modulus values suggest good clinical reliability of FRC posts. The flexural modulus values of the tested posts were from 2-6 times (FRC) to 4-10 times (metal) that of dentin. Valid measurement of flexural properties of endodontic post materials requires that test samples have appropriate L/D ratios.

The MAP kinase pathway is involved in odontoblast stimulation via p38 phosphorylation.

INTRODUCTION: We have previously shown that the p38 gene is highly expressed in odontoblasts during active primary dentinogenesis, but is drastically down-regulated as cells become quiescent in secondary dentinogenesis. Based on these observations, we hypothesized that p38 expression might be upregulated, and the protein activated by phosphorylation, when odontoblasts are stimulated such as during tertiary reactionary dentinogenesis. METHODS: We stimulated immortalized, odontoblast-like MDPC-23 cells, alone or in combination, with heat-inactivated Streptococcus mutans, EDTA-extracted dentine matrix proteins (DMPs), or growth factors, including transforming growth factor (TGF)-beta1, tumor necrosis factor-alpha (TNF-alpha), and adrenomedullin (ADM). We used ELISA to measure the resulting phosphorylation of the p38 protein, as well as its degree of nuclear translocation. RESULTS: Our results suggest that the p38-MAPKinase pathway is activated during odontoblast stimulation in tertiary dentinogenesis by both p38 phosphorylation and enhanced nuclear translocation. CONCLUSIONS: Data indicate that odontoblast behaviour therefore potentially recapitulates that during active primary dentinogenesis.

Trauma and dentinogenesis: a case report.

INTRODUCTION: After a traumatic injury to the upper central incisors of a 7-year-old patient, avulsion of tooth #9 and pulp exposure after crown fracture of tooth #8 were managed. METHODS: After immediate replacement of tooth #9 in its socket, teeth were splinted for 3 weeks. No endodontic treatment was performed on tooth #9, but pulp capping was performed with mineral trioxide aggregate (Pro Root MTA; Dentsply Maillefer, Ballaigues, Switzerland) on #8, and both teeth were restored with composite resin. The teeth were monitored every 3 months for 2 years. RESULTS: At 24 months, both teeth responded positively to electrometric tests and roots showed normal development, but an abnormal reduction in the size of the root canal space of tooth#8 was observed. CONCLUSION: Based on these observations, we discuss odontoblast behavior in the context of the stage of dentinogenesis and the probable disturbance of regulation of the physiologic dentinogenic secretory processes in the pathologic situation.

Dissolution of bio-active dentine matrix components by mineral trioxide aggregate.

OBJECTIVES: To analyze the soluble components of setting and set mineral trioxide aggregate (MTA), assess the abilities of two varieties of MTA and Ca(OH)(2) solutions to solubilise dentine matrix proteins (DMPs) and determine if these extracts contain signalling molecules important to pulpal repair and regeneration. METHODS: The metallic ion composition of solutions of white and grey MTA (pH 11.7), 0.02M Ca(OH)(2) (pH 11.9) and 10% EDTA (pH 7.2) was determined using atomic absorption spectroscopy. Extracellular dentine matrix components from powdered human dentine were extracted using all solutions over 14 days. Extracts were analysed for concentrations of non-collagenous proteins (NCPs) and glycosaminoglycans (GAGs), and protein profiles were examined using 1D-polyacrylamide gel electrophoresis (1D-PAGE). ELISAs for TGF-beta1 and adrenomedullin (ADM) were also performed. RESULTS: Aluminium, calcium, potassium, and sodium ions were detected in both white and grey MTA solutions. MTA and Ca(OH)(2) solutions liberated similar amounts of GAGs and NCPs although yields were considerably lower than those obtained using the EDTA solution. 1D-PAGE analysis demonstrated differences in protein profiles solubilised from dentine for all solutions. All extracts contained TGF-beta1 and ADM, EDTA solution liberated significantly greater amounts of TGF-beta1, and Ca(OH)(2) and grey MTA solutions released more ADM. CONCLUSIONS: These data imply that when placed clinically soluble components of set and setting MTA may release dentine matrix components that potentially influence cellular events for dentine repair and regeneration.

Performance of ultrasonic retrograde systems.

The aim of this study was to evaluate variations in power output of different Piezon-Master 400 (Electro Medical Systems, Nyon, Switzerland) ultrasonically driven generators and analytic handpieces at a range of power settings. A scanning laser vibrometer was used to measure the maximum vibration displacement amplitude of a KiS 2D tip. Ten repeat scans were made of the unloaded tip oscillation at six power settings. Data were acquired from four different generators and handpieces. Linear trend lines fitted to all tip data showed that none of the generator/handpiece combinations produced a linear increase in tip displacement amplitude with increasing power setting. A univariate analysis of variance (general linear model) showed that generator, handpiece, and power were all significant variables (p<0.0001). This study showed that there is significant variability in the power output between generators, and not all Analytic handpieces performed consistently when compared with each other.

Effect of bismuth oxide radioopacifier content on the material properties of an endodontic Portland cement-based (MTA-like) system.

The effect of bismuth oxide (Bi2O3) radioopacifier addition on the material properties of an endodontic Portland cement-based system were investigated. Increasing Bi2O3 content from 0 to 10 wt % resulted in a deterioration of mechanical strength from 82 to 40 MPa, decreasing gradually on further addition to 29 MPa for 40 wt %. Bi2O3 content increase also gradually increased the relative porosity of the set material from 15 to 31%. Strong linear correlationships were found for increases in relative porosity, dry and strut densities, and Bi2O3 content increase. Material constants, such as critical flaw size, were found to alter drastically with Bi2O3 addition and remained constant with further increase, thus affecting the potential longevity of the endodontic model system. The cement system was also found to be comparable in composition and strength to commercial MTA but had lower porosity because of the better workability of the Portland cement component.

Root canal retreatment.

Root canal therapy is not always successful and an increasing number of patients are requesting retreatment to address intraradicular infection. The armamentarium available to assist the dentist, some of which is described in this article, has never been greater.

Endodontics and new graduates, Part 2: Undergraduate experience and course evaluation.

A postal survey of recent United Kingdom dental graduates was undertaken to establish the amount of their undergraduate endodontic experience and their opinions of their training. A 75% response was achieved from all but two schools. Recent graduates had generally undertaken fewer cases as students than older graduates. Several had undertaken very few endodontic procedures as students. Differences and trends were seen in the opinions of students and their experiences among the schools, and between the two year groups studied. Most students were not very confident to undertake molar endodontics. Many felt they needed more practical experience as students and training in newer techniques and instrumentation.

Preserving the vital pulp in operative dentistry: 4. Factors influencing successful pulp capping.

The sequence of factors that mediate pulp inflammation and necrosis are unclear, and controversy surrounds the effects of different pulp capping materials on exposed pulps. Clinicians have few quantitative studies that rank the in vivo pulp capping effects of commonly used restorative materials.

Preserving the vital pulp in operative dentistry: 3. Thickness of remaining cavity dentine as a key mediator of pulpal injury and repair responses.

Confusion surrounds the pivotal role played by the remaining dentine thickness in a cavity in determining pulpal injury and repair response outcomes after restorative treatment. The multifactorial nature of the injury repair response requires that attention is focused on the most important factors, including remaining dentine thickness, to harness the natural regenerative properties of the pulp and to avoid postoperative treatment complications.

Cavity remaining dentin thickness and pulpal activity.

PURPOSE: To investigate pulpal injury by measuring odontoblast numbers, and pulp dentin repair activity by measuring reactionary dentin area, in relation to the remaining dentin thickness (RDT) of cavity preparations in 217 human teeth. MATERIALS AND METHODS: Cavities were restored with adhesive bonded composite, resin-modified glass-ionomer cement, zinc oxide-eugenol or calcium hydroxide materials. The teeth were extracted for orthodontic reasons between 20-381 days post-operatively, and odontoblast numbers and reactionary dentin area were analyzed histomorphometrically, and statistically using ANOVA. RESULTS: Reactionary dentin deposition was observed beneath cavities with a RDT above 0.5 mm as well as beneath cavities with a RDT below 0.25 mm; however maximal reactionary dentin appeared to be beneath cavities with an a RDT between 0.5-0.25 mm (P= 0.0001). The area of reactionary repair was also influenced by the choice of restoration material (P= 0.0385) from greatest to least; calcium hydroxide, composite, resin-modified glass-ionomer cement and zinc oxide-eugenol. Odontoblast numbers were maintained beneath cavities with a RDT above 0.25 mm, cavities placed closer to the pulp appeared to injure underlying odontoblasts, reducing their numbers (P= 0.0001). The choice of cavity restoration material also influenced the survival of underlying odontoblasts (P= 0.0061).

Preserving the vital pulp in operative dentistry: 2. Guidelines for successful restoration of unexposed dentinal lesions.

The exciting treatment possibilities arising from tissue engineering approaches are still some years away from involvement in dentistry. Meanwhile, it is important to optimize conventional treatments, although precise information on pulp responses to cavity preparation and restoration variables are limited. Odontoblast survival, pulp inflammation, and tertiary dentine area are used as measures of pulp injury and repair.

Preserving the vital pulp in operative dentistry: I. A biological approach.

This is the first in a series of four papers aimed at understanding human pulpal responses to tissue injury, cavity preparation and restorative events. This article provides an insight into the exquisite regenerative potential of the dentine-pulp complex which underpins the success of restorative dentistry.