OBJECTIVETo photoelastically investigate the difference in load distribution of Tension More (TM) implants with different conical angle designs.

METHODSThe following five groups of implants of different conical angles were designed: cylinder implant, upper 1/3 TM implant (taper length of 3 mm); 1/2 TM implant (taper length of 5 mm); lower 1/3 TM implant (taper length of 7 mm); and bottom TM implant (taper length of 10 mm). The implants were centrally located in individually photoelastic models consisting of a simulated trabecular bone and a 1 mm-thick layer of cortical bone. Vertical and 45° oblique static loads were applied at the center of the superstructures. The resulting stresses were monitored photoelastically and recorded photographically. RESULTS With vertical loading, the cylinder implant showed higher stress levels in the cortical bone and trabecular bone than the upper 1/3 TM implant, 1/2 TM implant, and lower 1/3 TM implant. The four groups of TM implants showed lower stress levels in the cortical bone than the cylinder implant under oblique loads. The least favorable stress concentration in cortical bone was observed in the upper 1/3 TM implant under vertical and oblique loads.

CONCLUSIONTM implants of rational conical angle designs seem to be effective in stress distribution. For all designs and load directions, the upper 1/3 TM implant is the most favorable around the crest.

Bone and Bones ; Dental Implants ; Stress, Mechanical

Objective · To evaluate the value of ultrasonic measurement of distance from skin to epiglottis (DSE) for predicting the difficult airway. Methods · 71 patients (20-80 year-old, ASA Ⅰ-Ⅲ ) undergoing endotracheal intubation and general anesthesia for an elective surgical procedure were enrolled. Conventional airway evaluation was performed. The distance from skin at thyroid cartilage upper edge to epiglottis was measured using ultrasound before anesthesia and compared between patients with difficult airway and normal airway. The effects of different methods for evaluating difficult airway were analyzed Results · The ultrasonic measurements of DSE on parasagittal view in patients with difficult airway and normal airway were (23.31±0.43) mm and (19.21±0.27) mm, respectively. The difference was statistically significant (P=0.003). The area under the ROC curve of ultrasonic measurement was 0.799 (95% CI:0.639-0.958) with the best cutoff point of 23.6 mm. The specificity of ultrasonic measurement was significantly increased as compared with Mallampati classification (96.43% vs 71.40%, P=0.004). The difference in sensitivity was not statistically significant (60.00% vs 73.33%, P=0.170). Conclusion · Ultrasonic measurement of DSE on parasagittal view can be used to predict the difficult airway.