[Need for dentists with post-graduate training in endodontology according to members of the Swiss Dental Association].

This questionary-based study was financed by the Swiss Society for Endodontology (SSE). At the time of this survey (2022) there were merely 20 board-certified endodontists in Switzerland, and 239 other members of the SSE, i.e. general practitioners with some form of post-graduate endodontic training or a keen interest in the field. The aim of this investigation was to evaluate the need for a higher number of trained endodontists as viewed by the general population of dentists in Switzerland. An electronic questionary in either German, French, or Italian was sent to all 4072 active members of the Swiss Dental Association (SSO). The questionnaire focused on the background of the surveyed dentists, their willingness to refer endodontic cases to a specialist or colleague with a focus on endodontics, their propensity to do so, and their perceived need for endodontists in their region. The response rate was 21%, and was similar between the different regions and cantons. Seventy-nine (9%) of the dentists participating in the survey were members of the SSE, while 16 (2%) were board-certified. Merely 7% of the participants received endodontic referrals themselves, while 81% referred cases in some instances. However, only 13% of participants referred endodontic cases always or regularly. The main reason for not referring was the belief by the surveyed dentists that they could perform the endodontic treatments themselves. Long distance to the next endodontic specialist or expert was the second most frequently given reason not to refer cases. A total of 58% of the participants believed that there were enough endodontists in Switzerland to cover the encountered clinical problems.

Precision-milled simulated curved root canals in bovine dentine for the assessment of chemo-mechanical root canal preparation.

AIM: The aim was to develop a standardized curved root canal model in bovine dentine and to assess whether that natural substrate would behave differently from the resin in standard plastic training blocks when prepared chemo-mechanically. The impact of substrate microhardness on simulated canal transportation was considered. METHODOLOGY: High-precision computer numerical control (CNC) milling was used to recreate a simulated root canal from a resin training block (Endo Training Bloc J-Shape, size 15) in longitudinally sectioned, dis- and re-assembled bovine incisor roots. Optical overlays obtained from 10 resin blocks were used to identify an average canal and program the CNC milling apparatus accordingly. Resin and dentine microhardness were measured. Simulated root canals in resin training blocks and their bovine counterparts were then instrumented at 37°C using Reciproc R25 instruments (VDW) with water or 17% EDTA (n = 10). Open-access image processing software was used to superimpose and analyse pre- and postoperative images obtained with a digital microscope. Centering ratios were averaged to indicate canal transportation. The effects of substrate and irrigant on canal transportation were assessed by two-way anova. RESULTS: Superimposed images showed that resin blocks under investigation varied considerably in terms of simulated canal length and curvature, whilst the milled canals were highly similar. The microhardness of dentine was more than three times higher than that of the resin. Conversely, canal transportation was considerably greater in dentine compared to resin, and in dentine had a tendency to be increased by EDTA. There was a strong effect of substrate on canal transportation (p < .001), no overall effect of irrigant, and a marginally significant interaction between irrigant and substrate (p = .077). CONCLUSIONS: CNC milling allows to create standardized simulated curved root canals in bovine dentine. These models may be useful to test and compare materials and concepts of chemo-mechanical root canal instrumentation. Microhardness is a bulk feature that does not predict the response to chemo-mechanical instrumentation of a composite material such as dentine.

4-Year Pulp Survival in a Randomized Trial on Direct Pulp Capping.

INTRODUCTION: This study aimed to assess pulp survival in a randomized trial on pulp lavage in adult nonpainful posterior teeth with carious pulp exposure. The treatment included complete caries excavation, direct pulp capping with mineral trioxide aggregate, and immediate restoration with composite resin. METHODS: Fluid was collected from the pulp wound to assess matrix metalloproteinase-9 (MMP-9) and total protein values. Before pulp capping, cavities were randomly (block randomization, n = 48) washed with a physiological saline or a sodium hypochlorite solution (2.5% NaOCl). Treatment outcome was assessed clinically (cold test) and radiographically after at least 1 year and again after at least 3 years. Painful failures were differentiated from nonpainful failures. Pulp survival was estimated using the Kaplan-Meier method including 95% confidence intervals (CIs) up to 1500 days. RESULTS: From the 96 patients originally enrolled, 73 individuals could be followed continuously. The clinical observations indicated a beneficial and sustained effect of pulp lavage with 2.5% NaOCl over a control treatment with physiological saline solution on estimated pulp survival 1500 days postintervention, with 7% (95% CI, 1%-40%) in the saline group versus 55% (95% CI, 30%-100%) in the NaOCl group. High MMP-9/total protein values in pulpal fluid collected from the exposed site indicated early and painful treatment failures yet were not associated with failures that occurred more than 250 days after intervention. CONCLUSIONS: The low 4-year success rates reported here challenge the concept of direct pulp capping in the cases that were included. NaOCl lavage did not only increase the survival of affected pulps substantially but also particularly diminished painful failures (33% in the NaOCl group vs 62% in the saline group). The lack of the predictive value of MMP-9 assessments beyond early treatment failures points to inflammatory states of the pulp tissue under deep caries, which are not related to neutrophil infiltration.

Assessment of Irrigant Agitation Devices in Simulated Closed and Open Root Canal Systems.

INTRODUCTION: The in vitro efficacy of irrigant activation devices has not been contrasted to their safety. This was attempted in this study using apically closed versus patent simulated root canal systems in epoxy resin models, with the latter featuring a simulated periapical lesion. METHODS: All 72 models had 2 joining canals connected by an isthmus, which was filled with dentin debris. The simulated periapical lesion was filled with colored gelatin in the 36 respective models. Canals were irrigated with 1.3% sodium hypochlorite. Samples were divided into 4 subgroups per system (n = 9): conventional irrigation, sonic low (EndoActivator; Dentsply Sirona, Charlotte, NC) and high frequency (EDDY; VDW, Munich, Germany), and ultrasonic agitation of the irrigant (always applying 3 cycles of 20 seconds). The total cleared surface areas (mm2) in the simulated isthmus and periapical lesion were compared between systems and devices using parametric tests (P < .05). RESULTS: The cleaning of the isthmus was more effective in the apically open compared with the closed systems and was also significantly influenced by the agitation method (P < .001). In the closed systems, EDDY and ultrasonic agitation achieved the significantly (P < .05) best cleaning of the isthmus. In the open systems, ultrasonic agitation showed the single best result (P < .05). EDDY caused by far the highest and ultrasonic agitation the lowest dissolution of the gelatin in the simulated periapical lesion. CONCLUSIONS: Under the conditions of this study, ultrasonic agitation of a previously administered sodium hypochlorite irrigant was more laterally targeted and thus safer and more effective than sonic agitation methods.

The Impact of Changing from First- to Fifth-Generation Nickel-Titanium Rotaries on Root-Filling Quality in a Clinical Undergraduate Course

In this retrospective study, it was investigated whether the use of a fifth-generation rotary system (ProTaper Next) resulted in improved radiological root filling quality compared to a first-generation counterpart (ProFile) in a controlled student course setting. Cases treated by fourth-year dental students in the 2020/21 academic year were collected and compared to those treated in 2019/20. Root canals in the former group were all instrumented using the ProTaper Next system, and the latter using the ProFile system. All other clinical parameters were similar between the two academic years, including the time of pre-clinical teaching, hands-on course hours, endodontic auxiliaries, and chemicals used for treatment. After excluding patients who were not available or refused to give their informed consent to this study (n = 20), and excluding teeth with missing or poor radiographs (n = 16), the fillings in 178 roots could be assessed by two calibrated observers blinded to the system that was used. The primary outcome was the radiographic quality of the root fillings according to the five-scale modified MOLANDER score. The secondary outcome was the number of separated rotary instruments by group. Both instrumenting systems resulted in a similar number of "excellent" root fillings (score I), 59 % in the ProTaper Next group and 60% in the ProFile group, with no statistically significant difference in outcome scores between groups (Probability > ChiSquare = 0.70). Furthermore, there was merely one separated instrument in the ProTaper Next group, and none in the ProFile group (Fisher's exact test, p = 1.00).

A critical analysis of research methods to study clinical molecular biomarkers in Endodontic research.

The authors of this narrative review aimed to address various experimental methods and make recommendations for how research should move forward in the context of studying biomarkers in clinical Endodontic research. The approach adopted is exemplified using two prominent clinical problems, namely (a) the 'reversible' versus 'irreversible' pulpitis conundrum and (b) persistent idiopathic dentoalveolar pain (PIDAP). Pulpitis under deep caries or dentinal cracks is understood from a histological perspective, but clinical assessment tools to indicate irreversibly inflamed aspects of the dental pulp are elusive. PIDAP, on the other hand, is a diagnosis of exclusion; its pathophysiology is complex and not understood sufficiently to avoid unnecessary dental treatments. This review addresses how diagnostic biomarkers could further our understanding of those and other clinical problems, and how issues can be tackled from a methodological point of view. Hence, different methodological approaches to identify suitable diagnostic biomarker(s) or use known biomarkers are presented. The importance of asking a relevant research question, collecting the most suitable fluid and using the ideal collection vehicle for the research question under investigation is discussed based on the defined clinical problems.

Patients with persistent idiopathic dentoalveolar pain in dental practice.

AIM: To assess whether persistent idiopathic dentoalveolar pain (PIDAP), a diagnosis of exclusion, exhibits common features that can facilitate its diagnosis. PIDAP is defined by the International Classification of Orofacial Pain (ICOP 6.3.) as 'Persistent unilateral intraoral dentoalveolar pain, rarely occurring in multiple sites, with variable features but recurring daily for more than 2 h per day for more than 3 months, in the absence of any preceding causative event'. METHODOLOGY: In this observational study, participants fulfilling the new ICOP diagnostic criteria of PIDAP were included, covering 16 years of consecutive data. A systematic, retrospective assessment of patients utilizing the new PIDAP criteria on complaints of chronic tooth pain in a referral-based endodontic practice was undertaken. Non-idiopathic cases were excluded on the basis of clinical and radiologic findings. A modified neuropathic pain questionnaire was used to describe the painful sensations. Furthermore, allodynia in the periodontal space and sensory changes in the oral mucosa were assessed using a periodontal probe. RESULTS: Amongst the 160 patients assessed, 78 (63 women) fulfilled the strict PIDAP criteria. Pain history of PIDAP included no nocturnal awakening (85%) and a 'pulling/dragging' pain quality (59%). In 69% of the patients with PIDAP, pain was associated with a root filled tooth at the same site. In 14% of the cases, no endodontic treatment was performed in the affected quadrant. Mechanical allodynia in the gingival sulcus was observed in 91% of patients with painful teeth or implants. CONCLUSIONS: In this observational study, PIDAP mainly affected females and was associated with undisturbed sleep and periodontal allodynia.

Effect of Sodium Hypochlorite Concentration in Continuous Chelation on Dislodgement Resistance of an Epoxy Resin and Hydraulic Calcium Silicate Sealer.

The conditioning of the root canal wall during chemo-mechanical root canal treatment differentially affects the adhesion of root canal sealers. This investigation evaluated the impact of sodium hypochlorite (NaOCl) concentration as used in a root canal irrigation concept called continuous chelation, with 1-hydroxyethylidene-1,1-diphosphonic acid (HEDP) contained in the NaOCl solution that is applied. Fourier-transform infrared spectra of the dentinal wall were gathered. The consequential effects on push-out bond strength of an epoxy resin (AH Plus) versus a hydraulic CaSi sealer (BioRoot RCS) were assessed. Single-rooted extracted human teeth were used and irrigated with pure NaOCl at a concentration of 0% (physiological saline), 2.5%, or 5.25%. Dual Rinse HEDP (9%) was added to the solutions, or not added for further control. Pure NaOCl solutions caused a decrease in the amide III: phosphate ratios, which was counter-acted by the addition of HEDP. It was observed that the adhesion of the epoxy resin sealer under investigation was negatively affected by this NaOCl deproteinization of the canal wall in a dose-dependent manner, while the opposite was observed with the CaSi sealer. HEDP when used in conjunction with NaOCl was beneficial for the adhesion of both sealers.

Influence of 1-Hydroxyethylidene-1,1-Diphosphonic Acid on the Soft Tissue-Dissolving and Gelatinolytic Effect of Ultrasonically Activated Sodium Hypochlorite in Simulated Endodontic Environments.

The addition of Dual Rinse HEDP, an etidronate powder, to a sodium hypochlorite (NaOCl) solution can create a combined single endodontic irrigant with a soft tissue-dissolving and a decalcifying effect, which can replace traditional alternating irrigation with chemically non-compatible solutions. While the short-term compatibility between NaOCl and 1-hydroxyethylidene-1,1-diphosphonic acid (HEDP) has been shown, it remains unclear whether ultrasonic activation of a combined NaOCl & HEDP solution immediately reduces the available chlorine and/or renders the NaOCl ineffective in dissolving organic tissue remnants. This was tested in three experiments: (1) direct activation in test tubes in an ultrasonic bath and then the activation by an ultrasonically oscillating tip (IrriSafe) in (2) an epoxy resin model containing a simulated isthmus filled with gelatin, and (3) extracted teeth with simulated resorption cavities filled with soft tissue. The control solutions were physiological saline and 2.5% NaOCl without HEDP. In (1), available chlorine after 30 s of ultrasonic activation (37 kHz) of test and control solution was assessed, as well as shrimp tissue weight loss in direct exposure. In (2) and (3), the ultrasonic tip was driven at 1/3 of full power using the respective unit, and areas of removed gelatin from the isthmus and tissue weight loss were used as the outcomes, respectively. Experiment (1) revealed no negative impact by HEDP on available chlorine (1), while all three experiments showed a highly significant (p > 0.001) synergistic effect, which was not hampered by HEDP, between NaOCl and ultrasonic activation regarding tissue weight loss (1, 3) and dissolution of gelatin (2).

Hydrogen Peroxide Versus Sodium Hypochlorite: All a Matter of pH?

INTRODUCTION: Hydrogen peroxide (H2O2) and sodium hypochlorite (NaOCl) solutions are similar in that they contain oxidizing agents with a bleaching effect. NaOCl solutions are stable at a high pH, at which they also exert increased cleansing/proteolysis. On the other hand, H2O2 solutions are natively acidic, yet gain bleaching power on organic stains when alkalized. It was investigated whether alkalizing a H2O2 solution would also let it dissolve soft tissue or increase its bleaching power on blood-stained dentin. METHODS: The stability of alkalized H2O2 solutions was assessed by iodometric titration. Soft tissue dissolution was investigated on porcine palatal mucosa. The bleaching effect (ΔL∗) after 60 minutes of exposure was monitored in blood-stained human dentin using a calibrated spectrophotometer. To compare similar molarities, 2.5% H2O2 solutions were used here, and 5.0% NaOCl was used as the positive control, whereas nonbuffered saline solution served as the negative control. RESULTS: Adding alkali (NaOH) to the H2O2 solutions rendered them unstable in a dose-dependent manner. A H2O2 solution of pH 11.1 was chosen for the main experiments (tissue dissolution and bleaching effect) and compared with a native counterpart (pH = 4.7). Alkalizing the H2O2 solution had no discernible effect on its soft tissue dissolution or bleaching power (P = .75 compared with the native H2O2 solution). The NaOCl solution of similar molar concentration had a considerably (P < .001) higher tissue dissolving and bleaching effect under current conditions. CONCLUSIONS: The proteolytic/bleaching effects of NaOCl solutions are unique and cannot be achieved by altering the pH of peroxide solutions.

Sodium Hypochlorite Reduces Postoperative Discomfort and Painful Early Failure after Carious Exposure and Direct Pulp Capping-Initial Findings of a Randomized Controlled Trial.

In this randomized controlled single-center clinical trial on 96 adult patients with parallel experimental groups (n = 48), the effects of washing a dentin/pulp wound in non-symptomatic teeth with extremely deep caries and pulpal exposure were compared between a 2.5% sodium hypochlorite (NaOCl) solution and a chemically-inert physiological saline control solution. After the allocated wound lavage, the pulps were capped with a mineral trioxide aggregate, covered by a glass-ionomer/resin liner, and the teeth were immediately restored with a resin-bonded-composite. In this first report, the early events were analyzed: postoperative discomfort (on an NRS-11 scale) at day-3 and -7 after intervention, and the occurrence of unbearable pain causing patients to contact the principal investigator to perform a root canal treatment (pulpectomy) during the first three months. The NaOCl solution caused a highly significant reduction in post-operative discomfort (p = 0.0010 day 3; p = 0.0007 day 7) and early painful failures (p = 0.0008) compared with the control. These novel findings highlight the importance of infection control in teeth with extremely deep carious lesions. Based on these observations, the use of an NaOCl solution to wash the exposed dentin/pulp wound in the vital pulp treatment is highly recommended in order to reduce pain and early failure.

What happened to our former students five to six years after graduation? An endodontic teacher's perspective.

Endodontic teaching follows common concepts in the four Swiss dental schools. The aim of this survey was to ask former Swiss dental students how they adopted these endodontic concepts in clinical practice. All the graduates of the years 2012 and 2013 (n = 196) were targeted in 2018 using an internet-based anonymous questionnaire, which was based on five initial questions. One hundred forty-one individuals (participants) filled in these questions on their work situation and referral concepts (72% response rate). Those 111 participants who performed root canal treatments themselves were the focus group. They answered an additional 11 questions. Their affinity towards performing endodontic treatments was investigated. The use of rubber dam isolation served as a surrogate to see if biological principles were respected. Furthermore, it was asked which instrumentation systems they used in daily practice, and how they perceived the impact of their superior/employer on these choices. Of the 141 survey participants 55 were men and 86 women. Thirty-eight of these (27%) reported to refer difficult endodontic cases. Individuals in the focus group had an overall positive attitude towards endodontics. There was very little variance in the responses between the four Swiss dental schools. The vast majority (86.5%) reported to use rubber dam routinely. More than half in the focus group used reciprocating systems, and only a few (22.5%) would still use the rotary system they were taught at university. There was a significantly (p < 0.05) higher perceived impact of the employer on choice of instrumenting system versus the use of rubber dam.

New Ways to Disinfect and Fill Dental Hard Tissues.

The main biological goal in clinical dentistry remains to prevent micro-organisms from exerting pathogenic effects by establishing non-commensal biofilms or entering the wrong niches [...].

Wound Lavage in Studies on Vital Pulp Therapy of Permanent Teeth with Carious Exposures: A Qualitative Systematic Review.

The aim of this study was to systematically review pulp wound lavage in vital pulp therapy (VPT). A search was conducted in six life science databases to identify clinical trials carried out on permanent teeth with a carious pulp exposure and a recall interval of at least six months. Twenty-seven trials of low to moderate risk of bias (RoB-2 and ROBINS-I) were included. Data was extracted and analyzed regarding study characteristics and methods used for pulp wound lavage. The agent used for pulp wound lavage was specified in all included trials. Most of the identified trials (23/27) randomized the pulp capping material. Many (14/27) reported the use of sodium hypochlorite (NaOCl); ten used only saline or water. One trial was identified that compared pulp wound lavage with 2.5% (NaOCl) to saline, another compared 5% glutaraldehyde to water, both in immature molar pulpotomies. Both studies were underpowered. Neither showed a significant difference between treatments. The use of NaOCl was positively correlated to recent year of publication and use of hydraulic calcium silicate cements for pulp capping (p < 0.05). In conclusion, despite a lack of well-designed trials on pulp wound lavage in VPT, a trend towards using NaOCl for this purpose was observed.

Transforming Growth Factor Beta 1 Distribution and Content in the Root Dentin of Young Mature and Immature Human Premolars.

INTRODUCTION: Transforming growth factor beta 1 (TGF-ß1) is a key morphogen in regenerative endodontics; yet, its location within the hard tissue phase of dentin and its availability in mature roots have not been fully elucidated. METHODS: Young mature (n = 8) and immature (n = 11) roots from sound premolars were obtained from 13 orthodontic patients aged 17 ± 1 and 12 ± 1 years, respectively. Roots were cleaned of organic remnants in 5% sodium hypochlorite. The width of the minor foramen was measured using a digital microscope. TGF-ß1 distribution was assessed in 3 roots per group by immunostaining combined with confocal laser scanning microscopy. The root dentin of the remaining 13 roots was powdered and decalcified in 17% EDTA to determine the overall levels of hard tissue-embedded TGF-ß1 by enzyme-linked immunosorbent assay. Data were compared between groups using the Student t test (α = .05). RESULTS: The minor foramen was 168 ± 49 µm versus 557 ± 295 µm in mature compared with immature roots (P < .05). TGF-ß1 was highly stainable toward the pulp space in both groups. It was clearly associated with peritubular dentin and apparently absent in nontubular outer dentin. TGF-ß1 content was 115 ± 31 pg and 74 ± 35 pg/100 mg mature versus immature root dentin, respectively (P > .05). CONCLUSIONS: TGF-ß1 is deposited into the peritubular dentin. It should be possible to release this molecule in regenerative endodontic procedures from young mature roots as well as immature roots.

Pulp-Derived Exosomes in a Fibrin-Based Regenerative Root Filling Material.

Regenerative endodontics has been described as a paradigm shift in dentistry, despite its current limitation to immature teeth and reparative rather than regenerative outcomes. Cell-free treatments are favored because of regulatory issues. However, the recruitment of host-derived stem cells to the desired site remains challenging. We investigated whether dental pulp-derived exosomes, which are extracellular vesicles that contain proteins, lipids, RNA, and DNA and thus mirror their parental cells, may be used for this purpose. The use of exosomes may present appreciable advantages over the direct use of transplanted stem cells due to a higher safety profile, easier isolation, preservation, and handling. Here we harvested exosomes from a cultured third-molar pulp cell and assessed them by transmission electron microscopy and Western blotting. Human mesenchymal stem cells (MSCs) were exposed to these exosomes to assess exosome uptake, cell migration, and proliferation. In addition, a fibrin gel (i.e., a diluted fibrin sealant), was assessed as a delivery system for the exosomes. Our results show that exosomes attracted MSCs, and the fibrin gel enhanced their effect. Moreover, exosomes improved the proliferation of MSCs. Therefore, we propose that pulp-derived exosomes in combination with a fibrin gel could be a powerful combination for clinical translation towards improved cell-free regenerative endodontics and thus represent a new way to fill dental hard tissues.

Light Transmittance and Polymerization of Bulk-Fill Composite Materials Doped with Bioactive Micro-Fillers.

This study investigated the effect of bioactive micro-fillers on the light transmittance and polymerization of three commercially available bulk-fill resin composites. These were mixed with 20 wt% bioactive glass 45S5, Portland cement, inert dental barium glass, or nothing (controls). Composites were photo-activated and light transmittance through 4 mm thick specimens was measured in real time. Moreover, degree of conversion (DC) and Knoop hardness (KHN) were assessed. Light transmittance of all bulk-fill composites significantly decreased (p < 0.05) with addition of 20 wt% bioactive glass 45S5 but not when inert barium glass was added. For bulk-fill composites modified with Portland cement, light irradiance dropped below the detection limit at 4 mm depth. The DC at the top surface of the specimens was not affected by addition of bioactive or inert micro-fillers. The bottom-to-top ratio of both DC and KHN surpassed 80% for bulk-fill composites modified with 20 wt% bioactive or inert glass fillers but fell below 20% when the composites were modified with Portland cement. In contrast to Portland cement, the addition of 20 wt% bioactive glass maintains adequate polymerization of bulk-fill composites placed at 4 mm thickness, despite a decrease in light transmittance compared to the unmodified materials.

Effects of endodontic irrigants on blood and blood-stained dentin.

OBJECTIVES: This study aimed to investigate bleaching effects of common endodontic irrigants on human whole blood and blood-stained dentin. Specifically, it was assessed whether sodium hypochlorite at a clinically recommended concentration (2.5% NaOCl) would bleach with similar efficacy as a peroxide-based irrigant at higher molarity (5% H2O2). Furthermore, the effects of a NaOCl-compatible chelator with a high affinity to iron (Dual Rinse HEDP) were investigated. METHODS: Human whole blood was mixed at a 1:20 ratio with either phosphate-buffered saline, 9% HEDP, 2.5% NaOCl, 2.5% NaOCl containing 9% HEDP, or 5% H2O2. Effects were assessed spectrometrically and photographically. Human dentin specimens were prepared with a methacrylate reservoir for liquids and a polished assessment side over 1 mm dentin thickness. Dentin was stained using human whole blood for 3 weeks and subsequently exposed to the irrigants for 60 min. Measurements were performed in the CIELAB color space. Results were compared using parametric tests with the alpha-type error set to 5%. RESULTS: When directly exposed, the solutions containing NaOCl completely discolored the blood, while the 5% H2O2 exerted a bleaching effect without complete dissolution of dissolved matter, and the pure 9% HEDP had no effect at all. The NaOCl solutions bleached blood-stained dentin more efficiently than H2O2 (p < 0.05). CONCLUSIONS: Under the current conditions, the 2.5% NaOCl solution had a stronger bleaching effect on blood and blood-stained dentin than 5% H2O2. HEDP did not have any direct impact on blood color or NaOCl-derived bleaching.

Biomimetic Conditioning of Human Dentin Using Citric Acid.

INTRODUCTION: In carious teeth, transforming growth factor beta 1 (TGF-ß1) is released from the dentin matrix and possibly activated in an acidic environment. Conversely, EDTA solutions with a neutral to slightly alkaline pH are used in clinics to promote cell homing in regenerative endodontic procedures. We hypothesized that citric acid (CA) might be more beneficial. METHODS: TGF-ß1 release from human dentin disks conditioned with either 10% CA (pH = 2) or 17% EDTA (pH = 8) and the behavior of human stem cells toward such pretreated dentin were studied. The protein concentration in conditioning solutions after 10 minutes of dentin exposure was determined using a pH-independent slot blot technique. RESULTS: There was a 5-fold higher concentration of the target protein in CA (382 ± 30 ng/disk) compared with EDTA (66 ± 3 ng/disk, P < .005). Using confocal laser scanning microscopy on immunofluorescent-labeled disks, we identified a high density of TGF-ß1 in peritubular dentin after CA treatment. A migration assay showed that CA conditioning attracted significantly more stem cells toward the dentin after 24 hours compared with EDTA (P < .05) or phosphate-buffered saline (P < .005). To investigate whether the cell response to these dentin surfaces could be affected by different pretreatments, we cultured stem cells on conditioned dentin disks and found that CA had a significantly (P < .05) better effect than EDTA on cell attachment and cell survival. CONCLUSIONS: CA conditioning could be useful and may have significant benefits over current treatments.

MMP-9 in Dentinal Fluid Correlates with Caries Lesion Depth.

The analysis of molecular cues in dentinal fluid from an excavated cavity could improve diagnostics in the context of minimally invasive caries treatment. In the current clinical trial we assessed whether the dentinal fluid levels of MMP-9 (matrix metalloproteinase-9; neutrophil gelatinase) would increase with the progression of carious lesions. MMP-9 is associated with neutrophil-related tissue breakdown in the pulp. Absolute MMP-9 levels were contrasted against the levels of MMP-2, an enzyme related to normal tissue turnover. Dentinal fluid was collected below deep and shallow caries from molars and premolars within the same patients aged 18 years and older (n = 30, 1 tooth per group/patient). Experimental teeth were isolated under a rubber dam prior to excavation. Dentinal fluid was collected from the bottom of the cavity using a size 25 paper point. MMP levels were assessed using an enzyme-linked immunosorbent assay. Nonparametric methods were applied to test for differences between groups. Significantly more (p < 0.05, Wilcoxon test) MMP-9 was collected from the deep carious lesions than from the shallow counterparts. Pairwise comparison of MMP-9 values within patients revealed that there was more MMP-9 collected from deep lesions than from shallow counterparts in 27 of the 30 individuals under investigation (pairwise Wilcoxon test, p < 0.001). In contrast, no such difference existed for MMP-2. There was a high correlation between MMP-9 from deep and shallow lesions (Spearman's ρ = 0.72, p < 0.001), indicating that patients with more MMP-9 in the deep carious lesion also tended to have more MMP-9 in the shallow lesion.