RESUMEN
BACKGROUND: An extra tooth in the normal tooth sequence in any region of the dental arch is regarded as a supernumerary tooth (SNT). Due to the large variation in location and morphology, the extraction of impacted SNTs is an extensive and complex procedure with high risks of several complications. This report presents a rare case of seven impacted SNTs in the bilateral upper and lower arch that were successfully extracted with the use of digital positioning guide plates. CASE SUMMARY: In January 2022, a 21-year-old male was referred to our department with a chief complaint of pain in relation to tooth #36. Clinical examination showed a deep carious lesion with pulpal involvement in tooth #36 and lingual swelling of the bilateral mandibular posterior area. Radiographic examination revealed seven deeply impacted SNTs in the bilateral posterior area and bilateral impacted mandibular third molars. Based on these findings, the patient was diagnosed with bilateral, multiple impacted SNTs and tooth #36 chronic pulpitis. A root canal treatment and an all-ceramic crown restoration for tooth #36 were performed. An individualized digital positioning guide plate was designed by computer-aided design/computer-aided manufacturing technology and cone-beam computed tomography for extraction of the impacted SNTs. During the operation, the digital positioning guide plate allowed rapid positioning and exposure of the SNTs while avoiding adjacent important anatomical structures. At 3-month follow-up, regeneration of bone and soft tissues was visible. CONCLUSION: The application of digital positioning guide plates is useful for the individualized and minimalized extraction of impacted supernumerary teeth.
RESUMEN
Understanding the responses of stomatal structure, photosynthesis and biomass of maize to exogenous Ca2+ addition under NaCl stress has important significance for further uncovering the alleviative mechanism of exogenous Ca2+ on maize under salt stress. We examined the effects of exogenous Ca2+(0, 5, 10, 20, 40, 80 mmol·L-1) on the stomatal structure, photosynthesis and biomass of maize (Zea mays L. cv. Jingke 665) seedlings under NaCl stress (100 mmol·L-1). Our results showed that exogenous Ca2+ addition had limited effect on stomatal density, but significantly decreased stomatal shape index, stomatal area, stomatal length, stomatal width, and stomatal cir-cumference. Meanwhile, the net photosynthetic rate (Pn) initially increased and then decreased with the increases of exogenous Ca2+ concentration, whereas both the stomatal conductance (gs) and intercellular CO2 concentration (Ci) were decreased, suggesting that the decrease of Pn was mainly due to stomatal limitation under high Ca2+ concentration. The biomass of maize seedlings was increased and the root/shoot ratio was decreased with the increases of exogenous Ca2+ concentration, suggested that the alleviated effect of exogenous Ca2+ on aboveground biomass was higher than that on belowground biomass of maize under salt stress.
