Applying the American Association of Endodontists and American Academy of Oral and Maxillofacial Radiology guidelines for cone-beam computed tomography prescription: Impact on endodontic clinical decisions

BACKGROUND

The American Association of Endodontists (AAE) and the American Academy of Oral and Maxillofacial Radiology (AAOMR) developed guidelines for the prescription of cone-beam computed tomographic (CBCT) imaging. The impact of appropriately prescribed CBCT imaging on endodontic diagnosis and treatment (Tx) decisions was examined.

METHODS

The clinical databases at the School of Dentistry at the University of California, Los Angeles, Los Angeles, California, were queried to identify patients referred for CBCT imaging from the postgraduate endodontic clinic over a consecutive 36-month period. Primary and secondary indications for CBCT imaging were recorded. Pre-CBCT uncertainty in diagnosis, Tx of the teeth in question, and post-CBCT changes to the diagnosis and Tx plan were recorded.

RESULTS

CBCT imaging was prescribed for 12% of patients. A total of 442 scans were prescribed to evaluate 526 teeth. Molars accounted for 51% of teeth examined. Overall, CBCT effected a change in periapical diagnosis (21%) and in the Tx plan (69%). The 5 most frequent primary indications for CBCT imaging were, in order, AAE-AAOMR recommendations 7, 9, 2, 12, and 6. The impact of these recommendations on Tx decisions varied from 48% through 93%.

CONCLUSIONS

This study validates the use of the AAE-AAOMR guidelines for prescribing CBCT imaging for endodontic evaluations. CBCT imaging contributed predominantly to Tx decisions rather than diagnostic determinations.

PRACTICAL IMPLICATIONS

This study validates AAE-AAOMR case selection guidelines for CBCT imaging and shows a positive impact of prescription imaging on endodontic decision making.

Reprint of: Prevalence and Characteristics of Root Resorption Identified in Cone-Beam Computed Tomography Scans

INTRODUCTION

Root resorption is a destructive process that compromises tooth structure and can result in tooth loss. Often it remains asymptomatic and is an incidental finding on radiographic examinations. The purpose of this study was to determine prevalence and characteristics of root resorption in patients referred for cone-beam computed tomography (CBCT) imaging for a variety of indications.

METHODS

The study included CBCT scans of 1086 consecutive patients referred for CBCT imaging over an 18-month period. A total of 1148 scans were acquired. Data were abstracted from radiology reports, and prevalence estimates of resorption were computed for the aggregate sample and also across specific indications.

RESULTS

Resorption was identified in 171 patients (15.7%, 95% CI: 13.6%-17.9%) and in 249 teeth with a prevalence range of 2.6%-92.3% across specific indications. An 18.7% of the patients had 2 resorption sites whereas 8.8% had 3 or more resorption sites. The majority of affected teeth were anteriors (43.8%), followed by molars (40.6%) and premolars (14.5%). The most prevalent resorption types were external (29.3%), cervical (22.5%), infection-induced apical resorption (13.7%), internal (9.6%), and impacted tooth induced (8.8%). The majority of teeth with resorption did not have prior endodontic treatment (73.9%) and had radiographically normal periapex (69.5%). Of 249 teeth with resorption, 31% presented as incidental finding. The prevalence of incidental findings of resorption increased with age, P < .05, and was significantly lower for anterior teeth (20.2%) as compared to premolars (41.7%) and molars (36.6%), (P < .05).

CONCLUSION

The high proportion of incidental findings of resorption detected by CBCT suggests that resorption is not recognized/detected by conventional radiography and therefore remains underdiagnosed.

Alkaline Materials and Regenerative Endodontics: A Review

Periapical health is the primary goal of endodontic treatment in mature and immature teeth. In addition, the goals of treatment of immature teeth with arrested root development include root growth to length and maturation of the apex, as well as thickening of the canal wall. These goals are valid for immature teeth that have been subjected to trauma and dental caries or that are the result of developmental anomalies that expose the tooth to the risk of pulp necrosis and consequently result in the cessation of root maturation. Regenerative endodontic procedures (REPs) have been described as a “paradigm shift” in the treatment of immature teeth with pulp necrosis and underdeveloped roots, as there is the potential for further root maturation and return of vitality. Treatment with REPs is advocated as the treatment of choice for immature teeth with pulp necrosis. REP protocols involve the use of alkaline biomaterials, primarily sodium hypochlorite, calcium hydroxide, mineral trioxide aggregates and Biodentine, and are the essential components of a successful treatment regimen.

Three-dimensional Sphere-forming Cells Are Unique Multipotent Cell Population in Dental Pulp Cells

INTRODUCTION

Mesenchymal stem cells (MSCs) are typically cultured as adherent monolayer using a conventional tissue culture technique. However, this technique incompletely reproduces an in vivo microenvironment of stem cells and results in the loss of stemness properties. Three-dimensional (3D) sphere culture is one of the most widely used 3D culture techniques that have been developed to recapitulate the in vivo microenvironment. However, the stemness and multilineage differentiation capacity of spheres derived from dental pulp stem cells (DPSCs) have not been well investigated.

METHODS

DPSCs were cultured and examined for the sphere-forming ability in serum-free, nonadherent conditions. The expression of pluripotency transcription factors was assayed by reverse transcription quantitative polymerase chain reaction and Western blot analysis. The expression of MSC-associated markers was determined by flow cytometry. Multilineage differentiation capacity was examined by alkaline phosphatase, alizarin red S, and oil red O assays. Subcutaneous transplantation in nude mice was used to examine the in vivo mineralized tissue-forming ability of sphere and adherent monolayer cells derived from DPSCs.

RESULTS

We showed that DPSCs form spheres. DPSC spheres exhibited a distinct stem cell phenotype characterized by robust expression of pluripotency transcription factors and decreased expression of MSC-associated markers compared with their corresponding adherent monolayer cells. Functionally, DPSC spheres exhibited enhanced in vitro multilineage differentiation capacity. The expression of multilineage differentiation-related genes was also highly increased in DPSC spheres. Furthermore, DPSC sphere cells possessed higher in vivo mineralized tissue-forming ability than adherent monolayer cells.

CONCLUSIONS

Our findings indicate that sphere-forming cells are unique multipotent cell populations in DPSCs. Our study further suggests that DPSC spheres may provide a unique opportunity for pulp tissue regeneration.

Endodontic Treatment Outcomes

The primary goal of conventional endodontic treatment is prevention and/or elimination of apical periodontitis for both mature permanent teeth and immature teeth with an open apex. Besides these goals, the objectives of endodontic treatment of immature teeth include preservation of pulp vitality and often further root maturation. Robust criteria for outcome assessment are an essential determinant for any measure of treatment success for both mature and immature teeth.

Pulp-dentin Regeneration

The goal of regenerative endodontics is to reinstate normal pulp function in necrotic and infected teeth that would result in reestablishment of protective functions, including innate pulp immunity, pulp repair through mineralization, and pulp sensibility. In the unique microenvironment of the dental pulp, the triad of tissue engineering would require infection control, biomaterials, and stem cells. Although revascularization is successful in resolving apical periodontitis, multiple studies suggest that it alone does not support pulp-dentin regeneration. More recently, cell-based approaches in endodontic regeneration based on pulpal mesenchymal stem cells (MSCs) have demonstrated promising results in terms of pulp-dentin regeneration in vivo through autologous transplantation. Although pulpal regeneration requires the cell-based approach, several challenges in clinical translation must be overcome—including aging-associated phenotypic changes in pulpal MSCs, availability of tissue sources, and safety and regulation involved with expansion of MSCs in laboratories. Allotransplantation of MSCs may alleviate some of these obstacles, although the long-term stability of MSCs and efficacy in pulp-dentin regeneration demand further investigation. For an alternative source of MSCs, our laboratory developed induced MSCs (iMSCs) from primary human keratinocytes through epithelial-mesenchymal transition by modulating the epithelial plasticity genes. Initially, we showed that overexpression of ΔN p63α, a major isoform of the p63 gene, led to epithelial-mesenchymal transition and acquisition of stem characteristics. More recently, iMSCs were generated by transient knockdown of all p63 isoforms through siRNA, further simplifying the protocol and resolving the potential safety issues of viral vectors. These cells may be useful for patients who lack tissue sources for endogenous MSCs. Further research will elucidate the level of potency of these iMSCs and assess their transdifferentiation capacities into functional odontoblasts when transplanted into the root canal microenvironment.

Molecular characterization of the microbial flora residing at the apical portion of infected root canals of human teeth

INTRODUCTION

This study investigated the bacterial communities residing in the apical portion of human teeth with apical periodontitis in primary and secondary infections by using a culture-independent molecular biology approach.

METHODS

Root canal samples from the apical root segments of extracted teeth were collected from 18 teeth with necrotic pulp and 8 teeth with previous endodontic treatment. Samples were processed for amplification via polymerase chain reaction and separated with denaturing gradient gel electrophoresis. Selected bands were excised from the gel and sequenced for identification.

RESULTS

Comparable to previous studies of entire root canals, the apical bacterial communities in primary infections were significantly more diverse than in secondary infections (P = .0003). Interpatient and intrapatient comparisons exhibited similar variations in profiles. Different roots of the same teeth with secondary infections displayed low similarity in bacterial composition, whereas an equivalent sample collected from primary infection contained almost identical populations. Sequencing revealed a high prevalence of Fusobacteria, Actinomyces species, and oral Anaeroglobus geminatus in both types of infection. Many secondary infections contained Burkholderiales or Pseudomonas species, both of which represent opportunistic environmental pathogens.

CONCLUSIONS

Certain microorganisms exhibit similar prevalence in primary and secondary infection, indicating that they are likely not eradicated during endodontic treatment. The presence of Burkholderiales and Pseudomonas species underscores the problem of environmental contamination. Treatment appears to affect the various root canals of multirooted teeth differently, resulting in local changes of the microbiota.

The Antimicrobial Effect of Silver Ion Impregnation into Endodontic Sealer against Streptococcus mutans

Pulpal and periradicular diseases are primarily caused by bacterial invasion of the root canal system as a result of caries progression. The presence of residual bacteria at the time of root canal completion (obturation) is associated with significantly higher rate of treatment failure. Re-infection of obturated root canals can be potentially prevented by enhancing the antibacterial activities of root canal obturation materials. We evaluated, in an in vitro model, the antimicrobial efficacy of silver ions added to a common endodontic sealer. For that purpose we performed growth inhibition studies and bacterial viability tests. We measured the zone of inhibition, optical density and performed confocal laser scanning microscopy. Our results show that the silver ions enhance the antimicrobial activity of the root canal sealer against Streptococcus mutans. This study approach may hold promise for studying other biologically based therapies and therefore increasing the success rate of routine orthograde root canal treatment.

Effect of interleukin-6 deficiency on the formation of periapical lesions after pulp exposure in mice

OBJECTIVE

The multifunctional cytokine interleukin-6 (IL-6) has actions on multiple cell types, including promotion of the development of immune cells and osteoclasts. Periapical inflammation as the result of root canal infection is characterized by the accumulation of inflammatory cells and bone resorption. The effect of IL-6 on periapical lesion formation after pulpal infection is unknown. We sought to determine whether deletion of IL-6 affects periapical lesion formation after pulp exposure.

METHODS

Molar pulps of homozygous IL-6 knock-out mice (IL-6(-/-), strain B6, 129-Il6tm1Koe ) and wild-type mice (IL-6(+/+)) were exposed, and the mice were killed at 1, 2, 3, 5, and 8 weeks after the exposure. Mouse jaws were decalcified and prepared for histologic examination of periapical lesions.

RESULTS

The IL-6(-/-) mice developed larger periapical lesions more rapidly than did the IL-6(+/+) mice.

CONCLUSIONS

IL-6 deletion promoted periapical lesion development.

Increased interleukin-8 expression in inflamed human dental pulps

OBJECTIVE

Elevated levels of interleukin-8, a potent chemoattractant and activator of neutrophils, are associated with infectious and inflammatory diseases. However, little is known about interleukin-8 expression in human dental pulp. The purpose of this study was to determine whether tissue levels of interleukin-8 are elevated in irreversibly inflamed human pulps.

STUDY DESIGN

Experimental samples were from teeth clinically diagnosed with irreversible pulpitis (diseased pulps). Controls were from freshly extracted, caries-free third molars (normal pulps). Samples were subjected to enzyme-linked immunosorbent assay and/or immunohistochemical analysis with specific antibodies to interleukin-8.

RESULTS

The enzyme-linked immunosorbent assay studies showed elevated levels of interleukin-8 in diseased pulps (mean, 1.82+/-0.79 pg/mL/microg protein), as compared to detectable interleukin-8 levels in samples from normal pulps (mean, 0.08+/-0.04 pg/mL/microg protein; P<.05). Immunohistochemical analyses demonstrated that diseased samples exhibited a higher density of localized interleukin-8 staining in areas with heavy infiltration of inflammatory cells. In contrast, normal pulps showed negative or weak interleukin-8 staining.

CONCLUSIONS

Interleukin-8 concentration was higher in pulps diagnosed with irreversible pulpitis; only negligible amounts of interleukin-8 were present in normal pulps.