Research Spotlight

Methani, M. M., Revilla-Leon, M. and Zandinejad, A. (2020). “The potential of additive manufacturing technologies and their processing parameters for the fabrication of all-ceramic crowns: A review.” J Esthet Restor Dent 32(2): 182-192.

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OBJECTIVE: This article aims to provide a review of the additive manufacturing technologies and the processing parameters that have been investigated for the fabrication of all ceramic crowns. OVERVIEW: Additive manufacturing has crept its way into the field of dentistry for the fabrication of resin and metal prosthesis. To evaluate the current status of additive manufacturing for the fabrication of all ceramic crowns, literature review was targeted to include publications pertaining to the fabrication of dental ceramics and all ceramic crowns. With respect to the additive manufacturing of dental ceramics, five technologies have been investigated to date: stereolithography, material extrusion, powder based fusion, direct inkjet printing, and binder jetting. The processing parameters and experimental outcomes were collated and described for each of the aforementioned technologies. CONCLUSION: Additive manufacturing has demonstrated promising experimental outcomes and corroborated to the fabrication all ceramic crowns. However, the technology is yet to witness a commercial breakthrough within this domain. CLINICAL SIGNIFICANCE: Additive manufacturing mitigates raw material wastage and tooling stresses that are associated with milling of ceramics. Continued research and development can lead to its approbation as an alternate technology for manufacturing all ceramic restorations.

Liang, Y., Luan, X. and Liu, X. (2020). “Recent advances in periodontal regeneration: A biomaterial perspective.” Bioact Mater 5(2): 297-308.

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Periodontal disease (PD) is one of the most common inflammatory oral diseases, affecting approximately 47% of adults aged 30 years or older in the United States. If not treated properly, PD leads to degradation of periodontal tissues, causing tooth movement, and eventually tooth loss. Conventional clinical therapy for PD aims at eliminating infectious sources, and reducing inflammation to arrest disease progression, which cannot achieve the regeneration of lost periodontal tissues. Over the past two decades, various regenerative periodontal therapies, such as guided tissue regeneration (GTR), enamel matrix derivative, bone grafts, growth factor delivery, and the combination of cells and growth factors with matrix-based scaffolds have been developed to target the restoration of lost tooth-supporting tissues, including periodontal ligament, alveolar bone, and cementum. This review discusses recent progresses of periodontal regeneration using tissue-engineering and regenerative medicine approaches. Specifically, we focus on the advances of biomaterials and controlled drug delivery for periodontal regeneration in recent years. Special attention is given to the development of advanced bio-inspired scaffolding biomaterials and temporospatial control of multi-drug delivery for the regeneration of cementum-periodontal ligament-alveolar bone complex. Challenges and future perspectives are presented to provide inspiration for the design and development of innovative biomaterials and delivery system for new regenerative periodontal therapy.

Chang, L., Umorin, M., Augsburger, R. A., Glickman, G. N. and Jalali, P. (2020). “Periradicular Lesions in Cancellous Bone Can Be Detected Radiographically.” J Endod Feb 11. pii: S0099-2399(20)30001-7. [Epub ahead of print].

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INTRODUCTION: The purpose of this study was to evaluate whether naturally occurring periradicular lesions confined to cancellous bone can be detected on periapical digital radiography and whether the size of the lesion had any effect on lesion detection. METHODS: One hundred twenty-nine roots were chosen based on cone-beam computed tomographic imaging and categorized as having no lesion, a lesion confined to cancellous bone, a lesion that encroaches on junctional corticocancellous trabeculae, or a lesion with cortical involvement. The largest buccolingual dimension of the lesions was measured on cone-beam computed tomographic imaging. Two observers separately viewed the corresponding periapical radiographs in their original version as well as in the edge-enhanced setting on MiPACS (LEAD Technologies Inc, Charlotte, NC). Observers were asked to evaluate and interpret the periapical radiographs as having a lesion present, absent, or “unsure.” Evaluations of images were conducted at 2 times 1 week apart. Data were analyzed, and the level of significance was set at P = .05. RESULTS: Lesion size, not the degree of cortical involvement, significantly affected the observers’ ability to accurately detect lesions. As the size of the lesion increased, the probability of correctly identifying a lesion increased (P = .0008). Lesions were correctly identified 97.6%, 94.1%, 91.6%, and 89.3% of the time, respectively, when in cortical bone, at the junction of corticocancellous bone, in cancellous bone, and when no lesion was present. Observers were “unsure” whether a lesion was present or absent 10.7% of the time. Only lesions in cortical bone significantly increased observers’ certainty in making a diagnosis. CONCLUSIONS: This study concluded that lesions confined to cancellous bone can be detected radiographically at a high rate. Lesion size was positively correlated with correct lesion identification, whereas the degree of cortical involvement had no significant effect. This suggests that lesion size may be a better predictor for correct lesion identification than lesion location.

Chan, S., Glickman, G. N., Woodmansey, K. F. and He, J. (2020). “Retrospective Analysis of Root-end Microsurgery Outcomes in a Postgraduate Program in Endodontics Using Calcium Silicate-based Cements as Root-end Filling Materials.” J Endod 46(3): 345-351.

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INTRODUCTION: The purpose of this retrospective study was to determine the clinical and radiographic outcomes of root-end microsurgery in a postgraduate program in endodontics using modern techniques and calcium silicate-based root-end filling materials (ProRoot MTA; Dentsply International, Johnson City, TN, and EndoSequence Root Repair Material [ERRM]; Brasseler USA, Savannah, GA) and to identify any potential prognostic factors that may have affected healing outcomes. METHODS: Clinical records and periapical radiographs were collected from patients who had undergone endodontic microsurgery between 2007 and 2018 in a postgraduate endodontic clinic with a minimum follow-up interval of 6 months. Either ProRoot MTA or ERRM was used as the root-end filling material. Outcomes were categorized into healed, healing, and nonhealing based on clinical and radiographic findings. Healed and healing cases were pooled and considered as successes, whereas nonhealing cases were considered as failures. RESULTS: A total of 129 patients with 142 teeth were included in the final analysis. Seventy-six cases were root-end filled with ProRoot MTA and 66 root-end filled with ERRM. The ProRoot MTA group had a success rate of 92.1%, and the ERRM group had a success rate of 92.4% with no significant difference between the groups (P > .05). Vertical root fracture was found to be the predominant cause of failure. No patient- or treatment-related factor was identified to have any significant impact on healing. CONCLUSIONS: High overall success can be achieved in a postgraduate endodontic program when either ProRoot MTA or ERRM is used as the root-end filling material.

Azarpazhooh, A., Diogenes, A. R., Fouad, A. F., Glickman, G. N., Kang, M. K., Kishen, A., Levin, L., Roda, R. S., Sedgley, C. M., Tay, F. R. and Hargreaves, K. M. (2020). “Insights into the March 2020 Issue of the Journal of Endodontics.” J Endod 46(3): 343-344.

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Welcome to the March 2020 issue of the Journal of Endodontics ( JOE ). Here we share some of our favorite articles that are published in this issue of the journal. We hope you look forward to reading these and other articles in JOE [Excerpt from article].