Bradford R. Johnson

In Vivo Generation of Dental Pulp-like Tissue by Using Dental Pulp Stem Cells, a Collagen Scaffold, and Dentin Matrix Protein 1 after Subcutaneous Transplantation in Mice

The presence of a perforation is known to significantly compromise the outcome of endodontic treatment. One potential use of regenerative endodontic therapy might be the repair of root canal perforations. In addition to nutrients and systemic in situ interactions, the 3 main components believed to be essential for tissue regeneration are stem cells, scaffold, and growth factors. This study investigated the role of each component of the tissue engineering triad in the organization and differentiation of dental pulp stem cells (DPSCs) in a simulated furcal perforation site by using a mouse model. Collagen served as the scaffold, and dentin matrix protein 1 (DMP1) was the growth factor. Materials were placed in simulated perforation sites in dentin slices. Mineral trioxide aggregate was the control repair material. At 6 weeks, the animals were killed, and the perforation sites were evaluated by light microscopy and histologic staining. Organization of newly derived pulp tissue was seen in the group containing the triad of DPSCs, a collagen scaffold, and DMP1. The other 4 groups did not demonstrate any apparent tissue organization. Under the conditions of the present study, it might be concluded that the triad of DPSCs, a collagen scaffold, and DMP1 can induce an organized matrix formation similar to that of pulpal tissue, which might lead to hard tissue formation.

Considerations in the selection of a root-end filling material

Surgical root canal treatment often includes the placement of a root-end filling material. New materials have recently emerged to challenge the long-standing position of amalgam as the root-end filling material of choice. This review discusses several of the commonly used root-end filling materials, with emphasis on indications and contraindications for the use of each.

In vitro fracture strength of endodontically treated premolars

The recent introduction of new bonding agents has led some authors to suggest that certain endodontically treated posterior teeth could be restored with a bonded restoration instead of a full-coverage crown or onlay. To test the fracture resistance of endodontically treated premolars restored with and without bonding agents, we randomly divided 56 intact and caries-free maxillary premolars into seven groups as follows: unaltered teeth; access only; MOD prep and RCT; MOD prep, RCT, and amalgam restoration; MOD prep, RCT, and amalgam with 4-META bonding agent; MOD prep, RCT, and composite resin restoration; and MOD prep, RCT, and composite resin with 4-META bonding agent. The teeth were subjected to compressive fracture tests in a Zwick 1435 Universal Testing Machine. Unaltered teeth and those with access only demonstrated similar fracture strengths. Under the conditions of this study, there was no significant difference in fracture strength between the experimental groups.

Outcome of One-visit and Two-visit Endodontic Treatment of Necrotic Teeth with Apical Periodontitis: A Randomized Controlled Trial with One-year Evaluation

The choice of one-visit versus two-visit root canal therapy for necrotic teeth with apical periodontitis is a source of current debate. The primary objective of this randomized controlled clinical trial was to compare radiographic evidence of periapical healing after root canal therapy completed in one visit or two visits with an interim calcium hydroxide/chlorhexidine paste dressing. Ninety-seven patients met the inclusion criteria and consented to participate in this study. Patients were randomly assigned to either the one-visit or two-visit group, and root canal therapy was performed with a standardized protocol. Patients in the two-visit group received an intracanal dressing of calcium hydroxide/chlorhexidine paste. Sixty-three patients, 33 in the one-visit group and 30 in the two-visit group, were evaluated at 12 months. The primary outcome measure was change in apical bone density by using the periapical index (PAI). Secondary outcome measures were proportion of teeth healed or improved in each group. Both groups exhibited equally favorable periapical healing at 12 months, with no statistically significant differences between groups.

Comparison of Effect of Intracanal Use of Ketorolac Tromethamine and Dexamethasone with Oral Ibuprofen on Post Treatment Endodontic Pain

The purpose of this study was to compare the pain-reducing efficacy of dexamethasone and ketorolac tromethamine when used as an intracanal medication, with oral ibuprofen and a placebo. An additional objective was to establish if any relationship exists between the incidence and severity of pretreatment pain and the incidence and severity of postinstrumentation pain. A total of 48 patients who presented to the University of Illinois postgraduate endodontic clinic were invited to participate. Patients were randomly assigned to 1 of 4 groups: oral ibuprofen, placebo, dexamethasone, or ketorolac tromethamine. Patients were asked to evaluate their pretreatment pain when they presented to the clinic with a Visual Analog Scale. The root canal treatment was performed in two appointments. The first appointment consisted of cleansing and shaping of the canal/s and placement of an intracanal medication. All teeth were closed with a sterile cotton pellet and IRM. Each patient was sent home with a Visual Analog Scale to fill out at 6, 12, 24 and 48 h after initiation of therapy. At the 12-h period, both dexamethasone and ketorolac provided statistically significant better pain relief than placebo. At the 24-h period, only ketorolac demonstrated better pain relief than the placebo. There were no statistically significant differences among the groups at 6 and 48 h. Although ibuprofen pain ratings were less than the placebo at all time points, the reduction was not significant. In addition, no significant differences were demonstrated between ibuprofen and either dexamethasone or ketorolac.

Effective shelf-life of prepared sodium hypochlorite solution

Although the tissue solvent and bactericidal properties of sodium hypochlorite are well known, the effective shelf-life of prepared sodium hypochlorite solutions is not known. The stability of sodium hypochlorite is adversely affected by exposure to high temperature, light, air, and the presence of organic and inorganic contaminants. The purpose of this study was to investigate the variables of storage conditions and time on the tissue-dissolving capacity of three different concentrations of sodium hypochlorite. Fresh frozen human umbilical cord was used as the tissue sample for this experiment. Tissue samples were dissolved at time intervals ranging from 1 day to 10 wk in 5.25%, 2.62%, and 1.0% solutions of sodium hypochlorite. The tissue-dissolving ability of 5.25% sodium hypochlorite remains stable for at least 10 wk. The tissue-dissolving ability of 2.62% and 1.0% sodium hypochlorite remains relatively stable for 1 wk after mixing, then exhibits a significant decrease in tissue-dissolving ability at 2 wk and beyond.

Comparison of Endodontic Diagnosis and Treatment Planning Decisions Using Cone-beam Volumetric Tomography Versus Periapical Radiography

INTRODUCTION Accurate and confident treatment planning is an essential part of endodontic practice. Periapical radiographs have been used to aid in the diagnosis of pathology and to help establish an appropriate treatment strategy. Recently, a new imaging modality, cone-beam volumetric tomographic (CBVT) imaging, has been shown to be a useful tool in a number of endodontic applications. The aim of this study was to compare the relative value of preoperative periapical radiographs and CBVT scanning in the decision-making process in endodontic treatment planning. METHODS Thirty endodontic cases completed in a private endodontic practice were randomly selected to be included in this study. Each case was required to have a preoperative digital periapical radiograph and a CBVT scan. Three board-certified endodontists reviewed the 30 preoperative periapical radiographs. Two weeks later, the CBVT volumes were reviewed in random order by the same evaluators. The evaluators were asked to select a preliminary diagnosis and treatment plan based solely on their interpretation of the periapical and CBVT images. Diagnosis and treatment planning choices were then compared to determine if there was a change from the periapical radiograph to the CBVT scan. RESULTS A difference in treatment plan between the 2 imaging modalities was recorded in 19 of 30 cases (63.3%, P = .001), 17 of 30 cases (56.6%, P = .012), and 20 of 30 cases (66.7%, P = .008) for examiners 1, 2, and 3, respectively. CONCLUSIONS Under the conditions of this study, preoperative CBVT imaging provides additional information when compared with preoperative periapical radiographs, which may lead to treatment plan modifications in approximately 62% of the cases.

Identify and Determine the Metrics, Hierarchy, and Predictive Value of All the Parameters and/or Methods Used During Endodontic Diagnosis

A Consensus Conference on Terminology was convened by the American Association of Endodontists in Chicago on Oct 3, 2008 to review solicited papers on focused questions. This paper addressed the question: Identify and determine the metrics, hierarchy, and predictive value of all the parameters and/or methods used during endodontic diagnosis. The best available clinical evidence was used to determine the sensitivity, specificity, and predictive value of pulpal and periapical testing methods and imaging technologies. Diagnosis of dental pulp diseases suffers from operators inability to test/image that tissue directly due to its location within dentin. In general, current pulp tests are more valid in determining teeth that are free of disease, but less effective in identifying teeth with pulp disease. Radiographic imaging is probably the most commonly used diagnostic tool to determine the status of root-supporting tissue, although interpretation of structural changes in the periradicular tissues is still considered unreliable.

Biomimetic approach to perforation repair using dental pulp stem cells and dentin matrix protein 1.

INTRODUCTION Dentin regeneration could be an ideal treatment option to restore tissue function. This study was conducted to evaluate the ability of dental pulp stem cells (DPSCs) and dentin matrix protein 1 (DMP1) impregnated within a collagen scaffold to regenerate dentin. METHODS Simulated perforations were created in 18 dentin wafers made from freshly extracted human molars. Six groups were established. They were (1) empty wafers, (2) mineral trioxide aggregate, (3) collagen scaffold, (4) scaffold with DMP1, (5) scaffold with DPSCs, and (6) scaffold with DPSCs and DMP1. One sample was placed subcutaneously in each mouse with three mice in each group. After 12 weeks, the samples were subjected to radiographic, histological, and immunohistochemical evaluations. RESULTS DPSCs impregnated within a collagen scaffold differentiated into odontoblast-like cells forming a highly cellular, vascular, and mineralized matrix in the presence of DMP1. CONCLUSIONS A triad consisting of DPSCs, DMP1, and a collagen scaffold promotes dentin regeneration in a simulated perforation repair model.

Biologic Markers for Odontogenic Periradicular Periodontitis

INTRODUCTION The diagnosis and assessment of apical periodontitis by traditional periapical radiographs can be challenging and might yield false-negative results. The aim of this study was to determine whether interleukin-1beta (IL-1beta) and dentin sialoprotein (DSP) in gingival crevicular fluid (GCF) can be used as biological markers for apical periodontitis. METHODS Forty healthy patients with teeth diagnosed with apical periodontitis of pulpal origin were included in the study. GCF samples were obtained from the diseased tooth and from a healthy contralateral control tooth. Total protein concentration in each sample was determined by using the Bio-Rad protein assay. Enzyme-linked immunosorbent assay was used to analyze the concentration of IL-1beta and DSP in the samples. RESULTS Protein content of the GCF was statistically significantly higher in the disease group compared with the control group. The levels of IL-1beta and DSP were not statistically different between disease and control groups. CONCLUSIONS Although this study was unable to demonstrate a significantly higher level of IL-1beta or DSP in the GCF of teeth with apical periodontitis, the observed presence of a significantly higher level of total protein in the GCF of diseased teeth suggests the possible role of total protein level as a marker for periapical disease.