An Experimental Study On Sealing Performance Of Different Fissure Sealants

Background and ObjectivesSince the application of pit and fissure sealant technology, scholars have done a lot of clinical and experimental research on the continuous improvement of sealants and technology,to improve the penetration of sealants and reduce microleakage of sealants,thus to improve the anti-caries effect of pit and fissure technology.In this experiment,by the study on sealing performance of three different types of fissure sealant,we expected to select a technique of low sensitivity and can achieve good sealing ability of fissure sealant to provide experimental evidence,and to provide a theoretical basis on guiding its work in the mass prevention of dental caries.Methods1.Forty human maxillary premolars,freshly extracted,caries-free for orthodontic reasons,were collected and stored in saline,4℃incubator.2.The forty extracted teeth were randomly divided into five groups with 8 each,which were namely A,B,C,D,E group. In the A group,as the control group,fissures were sealed with conventional pit and fissure sealant (Helioseal F).Fissures were respectively sealed with glass ionomer cement(GC FujiⅦ),GC FujiⅦplus saliva contamination,wet bond sealant(Embrace WetBond),Embrace WetBond plus saliva contamination in the remaining four groups.3. After sealing, all specimens were immersed in artificial saliva at 37℃for 24h, then thermocycled for 100 cycles at 5℃and 55℃, each temperature stayed 30s.4.Then the six specimens of each group were apically sealed and then coated with 2 layers of nail varish up to 1 mm from the sealing margins. The teeth were quenched in a 50% silver nitrate solution and stirred for 2 h in a dark room. The samples were then rinsed with water, cleaned before exposure to an intense light for 6 h, and immersed in a developer bath for 2 h,then the samples rinsed with water again.Three buccolingual axial sections were cut from each specimen with a medical hard issue cutting machine.The penetration depth of the dye into the pit and fissures of the different interfaces was observed under a stereomicroscope.5. The remaining two specimens of each group were sectioned buccolingually at the centre of the tooth.The sections were observed by scanning electron microscope(SEM) for the marginal adaptability of fissure sealants and interface condition,thus to assess the sealing ability of sealants.Results1.Without saliva contamination,there were significantly differences concerning the microleakage results among the three different sealants(Helioseal F,GC Fuji VII,Embrace WetBond).2.The A group(Helioseal F), as the control group,showed significantly less microleakage comparing with B,C,D,E group which as the experimental groups.3. When use of glass ionomer sealants(between B and C).there were significantly differences concerning the microleakage results with or without saliva contamination. While use of wet bond sealant(between D and E),there were no significantly differences concerning the microleakage results.4.SEM showed that Helioseal F had a good sealing ability,which fully penetrate into the bottom of the fissure, together with the enamel completely. It showed that GC Fuji VII and Embrace WetBond were not fully penetrate into the bottom of the fissure,while with saliva contamination, GC Fuji VII and Embrace WetBond had a poor sealing ability,the interface between sealants and enamel appeared significant micro-gap.Conclusion1.The conventional pit and fissure sealant Helioseal F had a excellent sealing ability.2.The new glass ionomer sealant GC Fuji VII and wet-bond sealant Embrace WetBond needed a technology with lower sensitivity,but could achieve a good sealing ability,which could be widly applied in the rural.3.Saliva contamination would affect the sealing ability of GC Fuji VII and Embrace WetBond.There was no significantly difference on the sealing ability of Embrace WetBond,however,the marginal adaptability would be declined,it was best to avoid saliva contamination.