Effect of cervical lesion centered access cavity restored with short glass fibre reinforced resin composites on fracture resistance in human mandibular premolars- an in vitro study.

Aim: The aim of this study was to evaluate the fracture resistance of cervical lesion centered access cavity restored with short glass fibre reinforced resin materials in human mandibular premolars.

Materials And Methods: Sixty freshly extracted human mandibular premolars were collected and assigned to positive control group (G1- Intact teeth) and other experimental groups (G2, G3. G4, G5, G6), Traditional Access Cavity(TAC) and Cervical Lesion Centered Access Cavity(CLCAC). Following endodontic therapy, samples were grouped accordingly, G2-CLCAC without restoration (Negative Control), G3-CLCAC restored with conventional nano-hybrid composite (Tetric-N-Ceram), G4-TAC restored with short glass fibre reinforced resin composite (Ever-X Posterior), G5-CLCAC restored with short glass fibre reinforced resin composite (Ever-X Posterior), G6- CLCAC restored with individually formed unidirectional fibre-reinforced post (Everstick post) and short glass fibre-reinforced resin composite (Ever-X Posterior). The samples were thermocycled (35 °C/28s, 15 °C/2s, 35 °C/28s, 45 °C/2s/10,000 cycles) and cyclically fatigued(2,50,000 cycles/15-30N/2 Hz) and then subsequently loaded to failure. The mean load to fracture (Newtons) were statistically analyzed using one-way ANOVA and Tukey's post HOC test and failure mode analysis was also done.

Results: The mean fracture resistance of the CLCAC design restored with fibre reinforced materials was higher when compared to the TAC design but the difference was not statistically significant. The negative control group (CLCAC without restoration) showed significantly the least fracture resistance (P < 0.05) when compared to all the other groups except for group 3 (CLCAC restored with conventional composites).

Conclusions: Within the limitations of the study, it can be concluded that short glass fibre reinforced resin composites improved the fracture resistance of endodontically treated mandibular premolars irrespective of the type of access cavity designs. Favourable fractures were seen more in cervical lesion centered access cavity restored with short glass fibre reinforced composite materials. Nevertheless, the applicability of this design in multirooted teeth, canal cleanliness efficacy, and long term clinical performance are yet to be explored to complement this new access design.