Knowledge and Practices of Family and Emergency Physicians in Managing Nontraumatic Dental Conditions: A Case-based Survey.

INTRODUCTION: Physicians are often patients' first point of contact for management of nontraumatic dental conditions (NTDCs). This study's aim was to evaluate the knowledge and practices of Ontario physicians in managing NTDCs, with a specific focus on antibiotic usage. METHODS: A Web-based survey featured 4 NTDC clinical scenarios: irreversible pulpitis, localized acute apical abscess with or without systemic involvement, and chronic apical abscess. The survey link was distributed to active Ontario family and emergency physicians. The sample group was asked questions about their management of and experience with NTDCs, and demographic and practice characteristics were collected. Descriptive and multivariate logistic regression analyses were undertaken (P ≤ .05). RESULTS: Sampled Ontario physicians tend to manage NTDCs in a manner that is not consistent with evidence-based care. For irreversible pulpitis and for localized acute apical abscess with or without systemic involvement, most physicians would prescribe an antibiotic (57.4%, 84.8%, and 96.3%, respectively), and 23.5% would prescribe an antibiotic for chronic apical abscess. Approximately half the sample (52.9%) felt discomfort in managing NTDCs, and 85.3% felt they were inadequately trained to manage NTDCs. CONCLUSION: Areas that present opportunities for improvement in the physician management of NTDCs were identified, including the incorporation of further NTDC training in medical curricula and continuing medical education courses, and development and dissemination of guidelines for physicians in managing NTDCs.

Culture-independent Characterization of the Microbiome of Healthy Pulp.

INTRODUCTION: Advances in culture-independent molecular biotechnologies have driven a greater appreciation for the function of mutualistic microorganisms in the maintenance of states of health in humans. The purpose of this study was to test the long-held hypothesis that healthy pulp lack bacteria. METHODS: Strict inclusion criteria were used to identify 10 pristine teeth from 10 healthy patients that were scheduled to be electively extracted in compliance with an orthodontic treatment plan. Using a rigorous disinfection protocol to isolate the operating field, the pulp space was accessed, and pulp tissue was collected in vivo from each tooth using a barbed broach. Genomic DNA was extracted from each pulp sample and analyzed for the presence of bacterial DNA using universal 16S ribosomal RNA polymerase chain reaction primers and MiSeq sequencing (Illumina, San Diego, CA) of community amplicons. RESULTS: One hundred percent (10/10) of the tested pulp tissues demonstrated the presence of bacterial DNA, with a mean of 343 operational taxonomic units per sample (range, 191-479). These were derived from 12 genera in which Ralstonia, Actinetobacter, and Staphylococcus were predominant (43%-78% of total community). None of the negative-field controls and none of the instruments used in the study tested positive for the presence of contaminating DNA. CONCLUSIONS: This study presents evidence to support the conclusion that the pulp spaces of pristine healthy teeth contain detectable bacterial DNA.

Bioactivity of Photoactivated Functionalized Nanoparticles Assessed in Lipopolysaccharide-contaminated Root Canals In Vivo.

INTRODUCTION: The persistence of dentin-bound lipopolysaccharides (LPS) in disinfected root canals impedes treatment outcomes of endodontic procedures. This study assessed the effects of photoactivated rose bengal-functionalized chitosan nanoparticles (CSRBnps) on LPS-contaminated root dentin in vivo using an intraosseous implantation model and neotissue formation as a marker. METHODS: Fifty human, 3-mm-long root segments with a 1.2-mm canal lumen were divided into 5 groups (n = 10): group 1, canals not contaminated; group 2, canals contaminated with Pseudomonas aeruginosa LPS; group 3, canals contaminated and disinfected with sodium hypochlorite (NaOCl); group 4, canals contaminated and disinfected with NaOCl and calcium hydroxide; and group 5, canals contaminated and disinfected with NaOCl and CSRBnps (300 µg/mL) with photoactivation (λ = 540 nm, 40 J/cm2). Specimens were implanted into mandibles of guinea pigs, block dissected after 4 weeks, and the canal content evaluated histologically and immunohistochemically. The ingrown neotissue interface (50 µm) with dentin was characterized for fibroblasts, osteoclasts, inflammatory markers, dentin resorption, mineralization, and angiogenesis and dichotomized as type 1 (no inflammation and resorption, indicative of LPS inactivation) or type 2 (inflammation and resorption). The frequency of the observed parameters was analyzed using the Fisher exact test. RESULTS: The outcome was categorized as type 1 in groups 1 and 5, type 2 in group 2, and mixed type 1 and 2 in groups 3 and 4. The outcomes in groups 1 and 5 (P > .05) differed significantly (P < .05) from those in groups 2, 3, and 4. CONCLUSIONS: Disinfection of LPS-contaminated root canals with photoactivated CSRBnps in vivo supported ingrowth of neotissue without signs of inflammation or resorption, suggestive of effective inactivation of dentin-bound LPS.

Effects of a Bioactive Scaffold Containing a Sustained Transforming Growth Factor-ß1-releasing Nanoparticle System on the Migration and Differentiation of Stem Cells from the Apical Papilla.

INTRODUCTION: This 2-part study hypothesized that a bioactive scaffold containing a sustained transforming growth factor (TGF)-ß1-releasing nanoparticle system will promote migration and enhance differentiation of stem cells from the apical papilla (SCAP). The study aimed to develop and characterize a novel modified chitosan-based scaffold containing TGF-ß1-releasing chitosan nanoparticles (TGF-ß1-CSnp) to enhance migration and differentiation of SCAP. METHODS: Part I concerns the synthesis and characterization of a carboxymethyl chitosan-based scaffold and TGF-ß1-CSnp. Part II examines the effect of sustained TGF-ß1 release from scaffold containing TGF-ß1-CSnp on odontogenic differentiation of SCAP. RESULTS: The scaffold demonstrated properties conducive to cellular activities. The incorporation of TGF-ß1 in CSnp allowed sustained release of TGF-ß1, facilitating delivery of a critical concentration of TGF-ß1 at the opportune time. TGF-ß1 bioactivity was maintained for up to 4 weeks. SCAP showed greater viability, migration, and biomineralization in the presence of TGF-ß1-CSnp than in the presence of free TGF-ß1. SCAP cultured in TGF-ß1-CSnp + scaffold showed significantly higher dentin matrix protein-1 and dentin sialophosphoprotein signals compared with free TGF-ß1 + scaffold or CSnp + scaffold. CONCLUSIONS: These experiments highlighted the potential of a carboxymethyl chitosan-based scaffold with growth factor releasing nanoparticles to promote migration and differentiation of SCAP. The results of this study may have direct application to improve current endodontic regenerative protocols.

Dentin Conditioning with Bioactive Molecule Releasing Nanoparticle System Enhances Adherence, Viability, and Differentiation of Stem Cells from Apical Papilla.

INTRODUCTION: Temporal-controlled bioactive molecule (BM) releasing systems allow the delivery of appropriate concentration of BM to enhance the interaction of stem cells to dentin matrix and subsequent odontogenic differentiation in regenerative endodontics. OBJECTIVES: The goal of this study was to evaluate the effect of dentin conditioning with 2 variants of dexamethasone (Dex) releasing chitosan nanoparticles (CSnp), (1) Dex-CSnpI (slow releasing) and (2) Dex-CSnpII (rapid releasing), on adherence, viability, and differentiation of stem cells from apical papilla (SCAP) on root dentin exposed to endodontic irrigants. METHODS: Slab-shaped dentin specimens were prepared parallel to the root canal and treated with 5.25% sodium hypochlorite (NaOCl) for 10 minutes and/or 17% EDTA for 2 minutes. Dentin was then conditioned accordingly by (1) no nanoparticle treatment, (2) CSnp, (3) Dex-CSnpI, and (4) Dex-CSnpII. The effect of nanoparticle conditioning on SCAP viability was determined by cell count and a circularity index. SCAP adherence and viability on dentin were assessed by fluorescence and scanning electron microscopy and odontogenic differentiation by immunofluorescence. RESULTS: SCAP on dentin treated with NaOCl alone or NaOCl as the last irrigant showed the least adherence, minimal cytoplasmic extensions, and higher circularity. SCAP adherence and viability on Dex-CSnpI and Dex-CSnpII conditioned dentin were increased and had a well-developed cytoplasmic matrix and significantly lower circularity (P < .05). SCAP cultured in Dex-CSnpII group expressed higher levels for DSPP and DMP-1 than in CSnp or Dex-CSnpI groups. CONCLUSIONS: Dex-CSnpI and Dex-CSnpII conditioning of dentin enhanced SCAP adherence and viability. Temporal-controlled release of Dex from Dex-CSnpII enhanced odontogenic differentiation of SCAP. This study highlighted the ability of dentin conditioning with temporal-controlled BM releasing nanoparticles to improve the local environment in regenerative endodontics.

Bioactive chitosan nanoparticles and photodynamic therapy inhibit collagen degradation in vitro.

INTRODUCTION: Collagen is the major structural protein of human dentin. Degradation of collagen by bacterial enzymes can facilitate microbial penetration, compromise structural/interfacial integrity, and lower resistance to fracture of dentin. We evaluated the ability of photodynamic therapy (PDT), bioactive chitosan nanoparticles (CSnp), or PDT in combination with CSnp to inhibit bacterial collagenase-mediated degradation of collagen. METHODS: Rat type 1 fibrillar collagen matrices were untreated or treated with 2.5% glutaraldehyde (GD), 2.5% GD followed by 1% CSnp, 1% CSnp, PDT (rose bengal activated with 540 nm light at 40 J/cm(2)), or 1% CSnp followed by PDT. Samples, except those used as untreated controls, were exposed to Clostridium histolyticum collagenase (125 CDU/mL) for 24 hours. The soluble digestion products were assessed by hydroxyproline assay, and the remaining adherent collagen was quantified by picrosirius red staining. Fourier transform infrared spectroscopy, immunoblotting, and scanning electron microscopy were used to study the interaction between CSnp/PDT with type 1 collagen. The data were analyzed by 1-way analysis of variance and post hoc Tukey test. RESULTS: As assessed by hydroxyproline release into the medium, collagen treated with CSnp, PDT, or a combination of CSnp and PDT exhibited less degradation than untreated controls (3.6-fold, 1.7-fold, and 7.9-fold reduction, respectively; P < .05). Compared with all other treatments, GD-treated collagen was the most resistant to collagenolytic degradation (239.6-fold reduction, P < .05). The abundance of post-treatment residual collagen, as measured by picrosirius red staining, was inversely related to the extent of collagen degradation. Analysis of collagen cross-links with Fourier transform infrared spectroscopy showed that PDT or GD treatments enhanced collagen cross-linking. Immunoblotting of sedimented CSnp indicated that CSnp and collagenase bound with low affinity. However, CSnp-bound collagenase showed a significant reduction in collagenolytic activity compared with controls (P < .05). CONCLUSIONS: Combined photochemical cross-linking of rat tail collagen by PDT and binding to CSnp inhibit collagenolytic activity.

Revascularization: a treatment for permanent teeth with necrotic pulp and incomplete root development.

INTRODUCTION: Endodontic treatment of immature permanent teeth with necrotic pulp, with or without apical pathosis, poses several clinical challenges. There is a risk of inducing a dentin wall fracture or extending gutta-percha into the periapical tissue during compaction of the root canal filling. Although the use of calcium hydroxide apexification techniques or the placement of mineral trioxide aggregate as an apical stop has the potential to minimize apical extrusion of filling material, they do little in adding strength to the dentin walls. It is a well-established fact that in reimplanted avulsed immature teeth, revascularization of the pulp followed by continued root development can occur under ideal circumstances. At one time it was believed that revascularization was not possible in immature permanent teeth that were infected. METHODS: An in-depth search of the literature was undertaken to review articles concerned with regenerative procedures and revascularization and to glean recommendations regarding the indications, preferred medications, and methods of treatment currently practiced. RESULTS: Disinfection of the root canal and stimulation of residual stem cells can induce formation of new hard tissue on the existing dentin wall and continued root development. CONCLUSIONS: Although the outcome of revascularization procedures remains somewhat unpredictable and the clinical management of these teeth is challenging, when successful, they are an improvement to treatment protocols that leave the roots short and the walls of the root canal thin and prone to fracture. They also leave the door open to other methods of treatment in addition to extraction, when they fail to achieve the desired result.

Blockade of TLR2 inhibits Porphyromonas gingivalis suppression of mineralized matrix formation by human dental pulp stem cells.

INTRODUCTION: Human dental pulp stem/progenitor cells (hDPSC) can differentiate into odontoblast-like cells and express dentin sialophosphoprotein (DSPP) and osteocalcin (OCN); thus, they may be used to regenerate dentin. However, residual bacterial components in the root canal may suppress this activity. PURPOSE: This study investigated the effect of a Porphyromonas gingivalis component on the expression of DSPP and OCN by stimulated hDPSCs and the influence of blockade of TLR2-mediated P. gingivalis host recognition. METHODS: Stimulated hDPSCs were exposed to varying concentrations of P. gingivalis lipopolysaccharide (LPS), and the expression of DSPP and OCN was measured. Similar groups of stimulated hDPSCs were exposed to TLR2 blocking agents before exposure to LPS. RESULTS: hDPSCs exposed to 5, 10, and 20 µg/mL LPS exhibited a dose-dependent reduction in the expression of DSPP (3.19 ± 0.18, 2.60 ± 0.49, and 1.15 ± 0.29, respectively) and OCN (3.51 ± 1.18, 2.60 ± 0.67 and 1.66 ± 0.89, respectively). The expression of DSPP and OCN after exposure to 20 µg/mL of LPS was significantly lower than measured for unexposed stimulated cells (analysis of variance and post hoc Tukey test, P < .05). The blockade of TLR2 using an extra- and intracellular agent affected DSPP (4.67 ± 0.97 and 5.29 ± 1.66, respectively) and OCN (5.25 ± 1.69 and 5.82 ± 2.38, respectively) expression at levels comparable to stimulated cells unexposed to 20 µg/mL LPS (6.32 ± 2.47 and 4.70 ± 1.60 for DSPP and OCN, respectively). CONCLUSIONS: The suppressing effect of P. gingivalis on mineralized matrix formation by hDPSCs is confirmed, and this suppression can be moderated by TLR2 blockade.

Technique acquisition in the use of two thermoplasticized root filling methods by inexperienced dental students: a microcomputed tomography analysis.

INTRODUCTION: Limited endodontic experiences in dental schools suggest the need for easy-to-learn techniques. Therefore, two simplified root filling methods were assessed for adequacy and expediency when performed by inexperienced students. METHODS: Eight students were trained (45-minute lecture and 90-minute practice) in use of ProTaper Obturators (PTO) and System-B/Calamus (SBC). They subsequently filled the root canals in two extracted, single-rooted teeth per method (n = 32). Canals were preshaped and prefitted with obturators and master cones. The volume of root-filling voids determined by microcomputed tomography imaging in 1-mm increments, time to complete fillings, and students' responses in questionnaires were analyzed (independent-sample t test and Mann-Whitney U test). RESULTS: PTO had a significantly smaller void volume in the apical 6 mm of canals (P < 0.001), required significantly shorter time (P < 0.001), and was perceived as easier to learn and use but less likely to be favored after graduation than SBC. CONCLUSION: These results suggested that the PTO root filling method was particularly suitable for teaching when endodontic experiences available for students are limited.

Proportion of healed teeth with apical periodontitis medicated with two percent chlorhexidine gluconate liquid: a case-series study.

INTRODUCTION: Chlorhexidine gluconate (CHX) is a potential intracanal medicament, but data on healing after its use are lacking. Previously we reported on bacterial sampling in 22 teeth with apical periodontitis medicated with CHX. This study assessed healing in those teeth. METHODS: Canals were instrumented and medicated with 2% CHX liquid for 7-15 days and subsequently irrigated and filled. Bacterial samples were taken before and after instrumentation, after medication and before root filling, and enumerated by culture and vital microscopy. After 2-4 years, subjects were examined clinically and radiographically by assigning Periapical Index scores by independent calibrated examiners. Outcome was dichotomized as healed or disease. RESULTS: With 2 teeth extracted, 1 deceased subject, and 2 nonrespondents, 16 of 17 examined teeth (94%) were healed without association with bacterial sampling results. The proportion of healed teeth in this study did not differ significantly (Fisher exact test; P = .20) from that in a historical control (90%). CONCLUSIONS: The results suggested a comparable outcome after medication with 2% CHX liquid and calcium hydroxide.

Characterization of an ex vivo model for the assessment of root canal disinfection.

Root canal bacteria in teeth with apical periodontitis were enumerated after extraction and incubation. Canals in 36 teeth were sampled after: S1, incubation for 2 hours (group A), 2 days (group B), 4 days (group C), and 6 days (group D); S2, subsequent incubation for 1 week; S3, canal disinfection; and S4, final incubation for 1 week. Bacterial concentrations were determined by culture (colony-forming unit [CFU]) and epifluorescence-microscopy (EFM) and compared by using pairwise and exact-permutation tests (p < 0.05). CFU counts were lower than EFM counts. CFU counts in S1 were higher in Gp(A) than in Gp(C) (p < 0.004) and Gp(D) (p < 0.02). EFM counts in S1 were higher in Gp(A) than in Gp(C) (p < 0.02). Both enumeration methods showed bacterial counts decreasing from S1 to S2 (p < 0.04). EFM was superior to culture in this ex vivo model. The indigenous flora survived incubation for 6 days, but the adverse effect of initial access would preclude testing of disinfection protocols that require two sessions.