Reducing the environmental impact of surgery on a global scale: systematic review and co-prioritization with healthcare workers in 132 countries

Abstract Background Healthcare cannot achieve net-zero carbon without addressing operating theatres. The aim of this study was to prioritize feasible interventions to reduce the environmental impact of operating theatres. Methods This study adopted a four-phase Delphi consensus co-prioritization methodology. In phase 1, a systematic review of published interventions and global consultation of perioperative healthcare professionals were used to longlist interventions. In phase 2, iterative thematic analysis consolidated comparable interventions into a shortlist. In phase 3, the shortlist was co-prioritized based on patient and clinician views on acceptability, feasibility, and safety. In phase 4, ranked lists of interventions were presented by their relevance to high-income countries and low–middle-income countries. Results In phase 1, 43 interventions were identified, which had low uptake in practice according to 3042 professionals globally. In phase 2, a shortlist of 15 intervention domains was generated. In phase 3, interventions were deemed acceptable for more than 90 per cent of patients except for reducing general anaesthesia (84 per cent) and re-sterilization of ‘single-use’ consumables (86 per cent). In phase 4, the top three shortlisted interventions for high-income countries were: introducing recycling; reducing use of anaesthetic gases; and appropriate clinical waste processing. In phase 4, the top three shortlisted interventions for low–middle-income countries were: introducing reusable surgical devices; reducing use of consumables; and reducing the use of general anaesthesia. Conclusion This is a step toward environmentally sustainable operating environments with actionable interventions applicable to both high– and low–middle–income countries

Biomechanical considerations for endocrowns in restoring endodontically treated teeth

Background: Endodontically treated teeth have an increased risk of biomechanical failure because of significant loss of tooth structure. The ideal restorative technique and material for such teeth is always a challenge for the clinician. Aims: The aim of this project was to evaluate the effect of using different dental CAD/CAM materials on the biomechanical behaviour of endodontically treated teeth restored with a new technique named endocrown. Methodology: In this study, a thorough comparison of endocrown restorations fabricated from new types of all-ceramic, resin based composite and zirconia dental restorative materials through a series of systematic tests on human permanent premolars was performed. An extensive thermal and mechanical cyclic testing, static mechanical loading, micro-computed tomography analysis, scanning electron microscopy, optical profilometry, and finite element analysis evaluated the efficiency of endocrowns in terms of their mechanical properties and behaviour, fitting accuracy and stress distribution pattern. Results: The current study reported significant effects for material selection along with restoration design and remaining sound tooth structure on the restoration efficiency of endodontically treated teeth. A significant interaction between restoration design and material type was observed, in which resin-based composite resulted in highest fracture strength among endocrowns, however all materials tested were able to survive dynamic thermo-mechanical fatigue testing simulating 2.5 years of clinical service. Monolithic translucent zirconia resulted in the highest number of catastrophic failures in restored teeth. The stress distribution pattern in the studied models revealed that the use of glass ceramics with endocrowns could enhance their long term bonding efficiency and retention, while resin composite endocrowns present a lower risk of catastrophic failure. Glass ceramics showed superior fitting accuracy and exhibited the smoothest and most homogenous fitting surface’s roughness profile. Conclusions: The mechanical behaviour, stress distribution and adaptation of resin based composite and glass ceramic endocrowns were clinically acceptable providing sufficient amount of sound tooth structure is preserved. Zirconia endocrowns should be avoided with premolar teeth owing to the low fracture resistance and high risk of catastrophic failures. Endocrowns are not recommended in cases with no remaining buccal and lingual coronal walls

Dissolution of a mineral trioxide aggregate sealer in endodontic solvents compared to conventional sealers

Abstract The aim of this study is to evaluate the solubility of a Mineral Trioxide Aggregate sealer (MTA-Fillapex) compared with five other sealers, calcium hydroxide (Sealapex), resin (Realseal), zinc oxide-eugenol (Tubli-Seal), and two epoxy resins (AH-26 and AH-Plus), in chloroform and eucalyptoil in static and ultrasonic environments. Samples of each sealer were prepared (n = 180) and then divided into 12 groups that were immersed in solvents for 5 and 10 min in static and ultrasonic environments. The mean weight loss was determined, and the values were compared using Student’s t-test, One-way ANOVA, and Tukey’s HSD post-hoc test (p 0.05). In conclusion, MTA-Fillapex was not sufficiently dissolved in either solvent. Ultrasonic activation had limited effectiveness on MTA-Fillapex dissolution, whereas it significantly increased the efficiency of solvents in dissolving a number of endodontic sealers

Original research Dental Materials Dissolution of a mineral trioxide aggregate sealer in endodontic solvents compared to conventional sealers

Abstract: The aim of this study is to evaluate the solubility of a Mineral Trioxide Aggregate sealer (MTA-Fillapex) compared with five other sealers, calcium hydroxide (Sealapex), resin (Realseal), zinc oxide-eugenol (Tubli-Seal), and two epoxy resins (AH-26 and AH-Plus), in chloroform and eucalyptoil in static and ultrasonic environments. Samples of each sealer were prepared (n = 180) and then divided into 12 groups that were immersed in solvents for 5 and 10 min in static and ultrasonic environments. The mean weight loss was determined, and the values were compared using Student's t-test, One-way ANOVA, and Tukey's HSD post-hoc test (p < 0.05). In chloroform, MTA-Fillapex, AH-26, and Sealapex displayed moderate solubility with no significant difference in dissolution (p = 0.125); however, their dissolution was significantly lower than that of AH-Plus (p < 0.001), which was almost fully dissolved after 10 minutes. Realseal was significantly less soluble than all sealers (p < 0.001). In eucalyptoil, MTA-Fillapex showed low solubility, as all of the sealers did, but Tubli-Seal was significantly more soluble than other sealers (p < 0.001). Using ultrasonic activation resulted in a significantly higher dissolution rate in chloroform for all sealers except MTA-Fillapex after 10 min (p = 0.226). In eucalyptoil, ultrasonic activation significantly increased the dissolution rate of all sealers except MTA-Fillapex after 5 and 10 min, Sealapex at 10 min, and AH-Plus at 5 min (p > 0.05). In conclusion, MTA-Fillapex was not sufficiently dissolved in either solvent. Ultrasonic activation had limited effectiveness on MTA-Fillapex dissolution, whereas it significantly increased the efficiency of solvents in dissolving a number of endodontic sealers

Assessment of biomechanical behavior of immature non-vital incisors with various treatment modalities by means of three-dimensional quasi–static finite element analysis

Abstract The objectives of this study were to evaluate the stress distribution and risk of fracture of a non-vital immature maxillary central incisor subjected to various clinical procedures using finite element analysis (FEA). A three-dimensional model of an immature central incisor was developed, from which six main models were designed: untreated immature tooth (C), standard apical plug (AP), resin composite (RC), glass-fibre post (GFP), regeneration procedure (RET), and regeneration with induced root maturation (RRM). Mineral trioxide aggregate (MTA) or Biodentine® were used as an apical or coronal plug. All models simulated masticatory forces in a quasi–static approach with an oblique force of 240 Newton at a 120° to the longitudinal tooth axis. The maximum principal stress, maximum shear stress, risk of fracture, and the strengthening percentage were evaluated. The mean maximum principal stress values were highest in model C [90.3 MPa (SD = 4.4)] and lowest in the GFP models treated with either MTA and Biodentine®; 64.1 (SD = 1.7) and 64.0 (SD = 1.6) MPa, respectively. Regarding the shear stress values, the dentine tooth structure in model C [14.4 MPa (SD = 0.8)] and GFP models [15.4 MPa (SD = 1.1)] reported significantly higher maximum shear stress values compared to other tested models (p  0.05). No significant differences between MTA and Biodentine® regarding maximum principal stress and maximum shear stress values for each tested model (p > 0.05). A maximum strain value of 4.07E−03 and maximum displacement magnitude of 0.128 mm was recorded in model C. In terms of strengthening percentage, the GFP models were associated with the highest increase (22%). The use of a GFP improved the biomechanical performance and resulted in a lower risk of fracture of a non-vital immature maxillary central incisor in a FEA model