Effects of Apical Barriers and Root Filling Materials on Stress Distribution in Immature Teeth: Finite Element Analysis Study.

PURPOSE: A finite element analysis (FEA) study was performed to determine whether the material of apical barrier used for root apexification and/or the use of canal reinforcement affect the stress distribution in an endodontically treated immature permanent tooth in order to infer in which clinical scenarios a fracture is more likely to occur based on the ultimate tensile strength threshold of dentin. METHODS AND MATERIALS: An extracted human immature mandibular premolar was selected as the reference model and scanned by micro-computed tomography (micro-CT). The digital model was segmented and converted to STL (Standard Tessellation Language) using Simpleware Scan-IP and exported in IGES (Initial Graphics Exchange Specification) to Ansys 19. Six experimental models were designed with different combinations of composite, mineral trioxide aggregate (MTA), and Biodentine (BIO). Using FEA, a static 300 N load at a 135 angle with respect to the axis of the tooth was applied to each model and von Mises stress values (MPa) were measured at the sagittal, apical 8-mm, 5-mm, 2-mm, and 1-mm levels. RESULTS: In all regions examined, the control (NT model) had lower stress in the root compared WITH experimental models. At the mid-root level, models with composite, MTA, and BIO reinforcement exhibited lower stresses in the root dentin than those with pulp or gutta-percha. BIO models had equal or greater average von Mises stress values than those of MTA models in all regions. Both, MTA and BIO, caused increases in stress of surrounding root dentin, with BIO causing a greater increase than MTA. CONCLUSIONS: Stress distribution in immature permanent teeth treated by apexification is affected by the types of materials used. Root dentin's stress was lower when the mid-root canal was reinforced by composite, MTA, or BIO, which provided similar stress reduction to the root dentin. MTA is a more favorable apical barrier material from a mechanical standpoint because it induces less stress on apical root dentin than BIO.

Treatment options for permanent teeth with coronal one-third root fractures.

BACKGROUND AND OVERVIEW: Teeth with coronal one-third root fractures are considered to have a poor prognosis. Historically, such teeth were likely to be extracted. Observations have indicated that at least some teeth with such fractures can survive for a significant amount of time. CASE DESCRIPTIONS: The authors report on 2 cases of coronal one-third root fractures that have survived for 10 and 35 years and suggest that the long-term splinting of these teeth aided in their survival. CONCLUSION AND PRACTICAL IMPLICATION: Stabilizing teeth with coronal one-third root fractures may allow such teeth to survive for long periods, which can be of great benefit, especially for young patients.

The Use of a Dental Dam during Implant Placement and Pertinent Literature Review.

In some regions, endodontists are increasingly placing implants in their daily practice. Endodontists have been proponents of the use of a dental dam during root canal treatment. It is beneficial to reduce the ingestion/aspiration of dental instruments during implant placement. It may be beneficial to reduce the bacterial load during implant placement procedures because biofilm formation on implants can lead to failure. A dental dam may help reduce the ingress of oral bacteria during implant placement. This case report demonstrates the use of a dental dam during the surgical placement of a dental implant. A literature review is presented that includes the history and rationale for the use of dental dams during various dental procedures. It also reviews the risks of aspirating/ingesting implant instruments. The use of a dental dam during implant placement offers certain operator conveniences, while also providing a safer field with less chance of instrument swallowing. It is expected that the technique offers a less bacteria-laden operating field due to the reduction in salivary ingress into the surgical site.

Effect of apex size on the leakage of gutta-percha and sealer-filled root canals.

OBJECTIVES: There are no data comparing coronal leakage of teeth prepared to different apical sizes and obturated with gutta-percha and sealer. The aim of this study was to investigate the effect of apical preparation size on the leakage of obturated root canals. Large apical openings are encountered as a result of pulp necrosis in immature teeth, apical resorption, or over-enlargement of the apical foramen. Complete cleaning, shaping, obturation, and apical seal of root canal systems are essential for the success of root canal treatment. METHOD AND MATERIALS: One hundred twenty-five extracted human teeth were divided into groups containing 25 samples each and prepared to apical file sizes 30, 40, 50, 60, and 70. Twenty teeth served as positive and negative controls. Obturation was completed with gutta-percha and sealer via warm vertical compaction. Bacterial leakage was investigated after 112 days using Proteus vulgaris. Data were analyzed via independent-samples Kruskal-Wallis test. RESULTS: The average time for leakage of apical preparation sizes 30, 40, 50, 60, and 70 were 57.5, 52.4, 47.2, 37.5, and 28.4 days, respectively. Significant differences in leakage were observed between apical preparation sizes 70 versus 30, 70 versus 40, 70 versus 50, as well as 60 versus 30. A trend for more leakage occurred when apical preparation sizes exceeded size 60. CONCLUSIONS: Based on these results, it appears leakage of gutta-percha and sealer as obturation materials increases when apical preparation size exceeds 60. Consideration should be given to using sealing materials other than gutta-percha and sealer when the apex size exceeds 60.

Replacement of severely traumatized teeth with immediate implants and immediate loading: literature review and case reports.

One of the options for management of severely traumatized dentitions is to provide immediate implant placement with immediate loading. Three representative cases out of 15 patients with 23 traumatized teeth treated to date in our clinic are presented. None had labial bone fractures. The teeth were replaced with NobelReplace Groovy implants (Nobel Biocare, Gothenburg, Sweden) in the fresh sockets immediately after extraction. They were placed toward the palatal areas in the sockets and 3 mm below the gingival margins. If there were gaps between implants and sockets wider than 1 mm, particulate deproteinized bovine bone was grafted in the gaps. Immediately after placement, the implants were loaded with provisional prostheses. The final restorations were installed 3-4 months later. The patients were reevaluated clinically and radiographically 1-3 years after the final restorations had been placed. In all 15 patients, excellent functional and esthetic results were achieved. No implants showed radiolucency, peri-implant suppuration, or mobility. The patients were satisfied with the results. Immediate implant placement with immediate loading is an option that provides good treatment outcomes and allows good functional and esthetic results, as well as addressing the social/psychological aspects of dental trauma.