Objective:To compare the effect of four different techniques on removal of vapor lock in the apical region of curved root canals.Methods:Forty simulated resin root canals with 45° curvature were prepared using WaveOne Primary,then the apical foramen were sealed with soft wax.The teeth were divided randomly into 4 groups thereafter (n =10).Contract solution was injected into the canals using a 30 G side-vented needle and scanned with cone-beam CT (CBCT) to identify the volume of the vapor lock.Four different techniques including photon-induced photoacoustic streaming (PIPS) laser-activated irrigation,gutta-percha cone technique,ultrasonic irrigation,and sonic irrigation were used to remove the vapor locks in the root canals.The residual volume of the vapor lock was identified again using CBCT scanning data.Accordingly,the reduction rates of the vapor lock were calculated.Furthermore,the initial and residual vapor lock length was calculated.The data were analyzed by using the One-Way ANOVA analysis and Kruskal-Wallis H test at a significance level of P ＜ 0.05.Results:There was no significant difference in the initial vapor lock volume (P ＞ 0.05).Residual volume of the vapor lock for PIPS laser-activated irrigation was 0 mm3,and that for gutta-percha cone technique was (0.02 ± 0.07) mm3,significantly lower than those of ultrasonic and sonic irrigation,the values being (0.20 ± 0.09)mm3 and (0.23 ±0.06) mm3 (P ＜0.001),respectively.The reduction rates of the vapor lock of PIPS laser-activated irrigation and gutta-percha cone technique were 100.00％ (100.00％,100.00％) and 100.00％ (77.66％,100.00％),respectively,significantly higher than those of ultrasonic irrigation [70.37％ (56.41％,91.43％)] and sonic irrigation [63.54％ (51.47％,74.00％),P ＜0.001].The length of the residual vapor lock for PIPS laser-activated irrigation was 0 mm,and that for gutta-percha cone technique was (0.15 ±0.47) mm,significantly lower than those of ultrasonic and sonic irrigation,values being (2.21 ±0.09) mm and (2.34 ±0.08) mm (P ＜0.001),respectively.The length of the residual vapor locks in the ultrasonic and sonic group remained approximately the same as the distance between the working tip and the apical foramen.Conclusion:PIPS laser activated irrigation and gutta-percha cone technique could remove the vapor lock from the apical region of curved canals effectivelv.

Objective To discuss the clinical features,differential diagnosis and complication treatment of a patient with genetic visceral myopathy.Methods Medical history,physical examination and laboratory results of the patient were collected in detail.The pathology of previous surgery was reviewed.The patient's peripheral blood DNA was extracted and submitted for whole-exome sequencing.Subsequent Sanger sequencing was used to complete the pedigree verification of the mutation site.Results The patient was a young female presented with repeated in-complete intestinal obstruction since early childhood.She used to be misdiagnosed as Hirschsprung's disease for a long period and underwent multiple gastrointestinal segment resections.Her intestinal obstruction symptoms were temporarily relieved by surgeries,but severe diarrhea,mucus and bloody stools and malnutrition gradually occurred after the last operation.The patient had bacterial overgrowth in small intestinal tract and followed by intestinal op-portunistic infections secondary to chronic intestinal pseudo-obstruction.The symptoms improved after anti-infection and enteral element diet treatment.Further pathological consultation and whole-exome gene sequencing confirmed the diagnosis of visceral myopathy related to ATCG2 R148L mutation.Conclusions Patients with early onset of chronic intestinal pseudo-obstruction and have poor response to conventional treatment are recommended to perform genetic test.The patients with hereditary visceral myopathy are susceptible to opportunistic intestinal infection.At-tentions should also be paid to the prevention and treatment of complications to avoid unnecessary surgery.