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Aim: To evaluate the fracture resistance of printed crowns with two different designs. Methods: Forty restorations (n = 20/group) were fabricated using resin matrix ceramic (VarseoSmileTM) with different designs as follows: group 1: overlay restoration with chamfer margin; group 2: overlay restoration with chamfer margin located 3 mm above the gingiva. Restorations were bonded to resin dies using 3M RelyX Luting Cement. Compression forces were applied with a 4 mm diameter steel bar at the midline fissure of each crown using the universal testing machine. Restorations were loaded until fracture, and fracture resistance at maximum load was recorded. Statistical analysis: A t-test was used for statistical comparison between groups. Results: No difference in the fracture resistance was detected for both groups. Conclusions: Different designs of composite resin crowns fabricated using CAD/CAM techniques can be used, however further research is needed to assess the clinical outcomes.

IntroductionSleep-related breathing disorders (SRBDs), neuropathic pain, spasticity and cardiovascular autonomic dysfunction are common after spinal cord injury (SCI). Prior studies suggest that systemic inflammation following SCI may be implicated in the development of neuropathic pain, spasticity and cardiovascular dysfunction. Given that SRBDs also cause a systemic inflammatory response, we hypothesized that individuals with SCI who develop more severe SRBDs would experience more intense neuropathic pain, more severe spasticity and more significant cardiovascular autonomic dysfunction.MethodsThis cross-sectional prospective study will explore the previously understudied hypothesis that SRBDs are associated with increased neuropathic pain, spasticity, and cardiovascular autonomic dysfunction in adult individuals with low-cervical/high-thoracic (injury level at C5 to T6), complete/incomplete (ASIA Impairment Scale A, B, C or D) SCI.DiscussionTo our knowledge, no prior study has addressed this clinically relevant question on whether the degree of SRBDs affects the intensity of neuropathic pain, spasticity, and cardiovascular autonomic dysfunction in individuals with SCI. We anticipate that the results of this original study will provide key information for a future clinical trial on the use of continuous positive airway pressure (CPAP) therapy for moderate-to-severe SRBDs, which may better control neuropathic pain, spasticity, and cardiovascular autonomic dysfunction among individuals with SCI.Trial registrationThe research protocol for this study was registered in the ClinicalTrials.gov website (NCT05687097). https://clinicaltrials.gov/ct2/show/NCT05687097.