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Effect of root canal pretreatments using Er:YAG laser and chlorhexidine on microleakage of fiber posts

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EFFECT OF ROOT CANAL PRETREATMENTS USING ER: YAG LASER AND  CHLORHEXIDINE ON MICROLEAKAGE OF FIBER POSTS
GHAZALEH AHMADIZENOUZ1, FATEMEH ZAHEDIPOUR2
1- Assistant Professor, Department of Restorative Dentistry, Babol University of Medical sciences , Iran
2- Dentist, Private Practice

Backgroun and aim: In recent years, restoration of endodontically treated teeth with fiber reinforced composites (FRCs) posts has become increasingly popular . The most common failure mode of FRC posts is debonding at the adhesive resin-dentin interface. Obviously, dentin hybridization is very important in resin – dentin bond and can be affected by different types of dentin pretreatments .The aim of this in-vitro study was to assess the impact of three different root canal pretreatments {chlorhexidine(CHX), Er:YAG laser and CHX+ Er:YAG laser} on the microleakge of  cemented fiber posts.

Method and Material: Thirty-two extracted human maxillary central incisors were selected and disinfected in 0.5% chloramine T solution. The crowns of the teeth were removed below the CEJ using a diamond disc perpendicular to the long axis. The root canals were instrumented using step- back technique and obturated with gutta-percha and AH26 using lateral condensation technique. The access cavities were temporized with a non- eugenole provisional material .The roots were stored in normal saline at 37°C for one week for full sealer setting. Guttapercha fillings were removed to a depth of 9 mm with No.3 Gates Glidden and post space preparation up to 9 mm was carried out with #2 White Post system drills .The specimens were  randomly allocated into 4 groups (n =8) according to the dentin conditioning.

Group 1: no additional canal pretreatment (Control ) .

Group 2: placement of  CHX 2%  for 30 seconds in root canals (Fig.1)

Group 3: irradiation of root canals with Er:YAG laser .(Fig2) Laser parameters were set at output power1.5W; wavelength 2940 nm, pulse frequency 25Hz; air pressure of 65% and water pressure of 100%  in an irradiation of 5 s for 3 times at 10 s intervals using H4 fiber tip with a diameter of 400 µm.

Group 4:  combination of CHX 2% for 30seconds and Er:YAG laser

fiber posts #2 ( Fig3) were then cemented with Panavia F2 resin cement.

The roots were thermocycled in distilled water for 1500 cycles .Dye penetration technique was used to assess the depth  of microleakage  in  µm at the cement – dentin interface from the orifice on both mesial and distal surfaces under stereomicroscope at 40X.(Fig 4,5,6) The data were analyzed using SPSS v.22 by one-way ANNOVA test .The accepted level of error was set at P<0.05.

 Results:

Microleakage in the specimens treated with CHX was lower than other groups. The highest microleakage mean value was found in laser-treated group. However, One-way ANOVA revealed no significant differences between the groups (p>0.05).

 Discussion: 

Our results indicated that the use of 2% CHX prior to the application of self-etch cement did not increase the microleakage compared to the control group. CHX is an amphiphilic molecule that binds to several proteins and acts as an inhibitor of matrix metalloproteinases by cation chelating mechanism; hence the integrity of resin-dentin bond will be secured during the time. However, controversial findings have been reported about effects of CHX on the adhesion. In the present study we used Panavia F2 as a self –etch cement. Our results are in agreement with the findings of Shafiei et al that reported CHX application with Panavia F2.0 cement did not lead to a significant difference in the microleakage. Our findings are also in accordance with the results of Geraldo-Martins et al in which no significant differences were found in the microleakage of  class V cavities treated with CHX 2% ,Er:YAG laser and CHX plus Er:YAG laser and restored using a self-etch adhesive.

To the best of our knowledge, this is the first study that evaluated the effect of laser treatment on microleakage of fiber posts. Previous studies assessed the bond strength of cemented fiber posts to laser-treated dentin  or microleakage of coronal restorations ,therefore, direct comparison of our results with those studies is difficult. In this matter, Bitter et al showed that there were no significant differences between the push out bond strength of fiber posts cemented with Panavia F2 cement in the Er:YAG treated group and the controls irrigated with chlorhexidine .  In accordance to our finding Muhammed et al and Navarro et al represented that the amount of microleakage was not influenced with Er:YAG laser irradiation in Cl V restorations.

Conclusion: 

Our observations suggest that none of the pretreatment methods completely eliminated the microleakage. Among the study groups CHX revealed the lowest microleakage and Er: YAG laser showed the highest amount. Therefore, it can be concluded that post space conditioning with Er: YAG laser due to technique sensitivity and high cost is not recommended

 

 

 


 

 


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