ABSTRACT
Objective:To observe the clinical efficacy of CAD/CAM all-ceramic onlay in the restoration of molars with extensive defect after root canal therapy(RCT).Methods:260 molars with extensive defect were restored by all-ceramic onlay after RCT.The patients were followed up for 18 months.The restoration effects were assessed using USPHS criteria.Results:The success rate of CAD/CAM all-ceramic onlay was 98％.Restoration exfoliation was found in 3 cases,fractured in 2 cases.Conclusion:CAD/CAM all-ceramic onlay can be applied in restoring extensive postenor tooth-defection after RCT.
ABSTRACT
Objective:To study the factors of nickel titanium instrument(NTI)seperation in posterior tooth root canal therapy.Meth-ods:NTIs were used in 1 498 patients with 1 562 involved posterio teeth and 3 518 root canals for RCT from Jun.2009 to May.2012. The relation of instrument seperation(IS)with gender,age,tooth position,working years of the dentists,bending degree of the in-volved tooth canal and the NTI form was analyzed statistically.Results:68 out off 1 198 applied NTIs(5.68%)were seperated in cal-nal preparation.Single factor analysis showed that IS incidence was not statistically different between male and femal(χ2 =0.013,P >0.05),it was statistically different among the patient ages(χ2 =-354.258,P <0.05),between molar and premolar(χ2 =-201.344,P <0.05),among working years of the dentists(χ2 =13.763,P <0.05),bending degree of involved teeth(χ2 =22.414,P <0.05),times of NTI uses(χ2 =16.807,P <0.05),taper of NTIs(χ2 =18.283,P <0.05)and diameter of NTIs(χ2 =21.312,P <0.05).Logistic analysis showed that age,tooth position,working years of dentists,bending degree of involved tooth canal,frequency of NTIs applica-tion and NTI form were independent risk factors for NTI seperation.Conclusion:Dentists should take appropriate technique and stand-ard operation sequence to reduce the incidence of nickel titanium instrument seperation.