الفهرس 
Fracture resistance of upper primary anterior teeth restored with fiber post pretreated with Laser and different treatment modalities
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Abstract
Badly broken primary anterior teeth present higher risk of failure due to loss of tooth structure.The aim of this in-vitro study is to evaluate and compare the influence of fiber post surface treatments (Er,Cr:YSGG laser sandblasting, and 9% hydrofluoric acid ) on surface roughness and morphology and to assess the fracture resistance of upper primary anterior teeth restored with fiber posts after Al2O3 sandblasting, 9% hydrofluoric acid and Er,Cr:YSGG laser (2790 nm) surface pretreatments.
Materials and Methods:
A total of 120 fiber posts were used and randomly divided into 4 groups according to the surface pretreatment method into: group I: control (no pretreatment), group II: sandblasting (Al2O3), group III: etch 9% hydroflouric acid etching , group IV: Er,Cr:YSGG laser iradiation (2790 nm) .group IV was further subdivided according to laser power to; subgroup A: 0.5W, subgroup B: 1W, subgroup C: 1.5W. Surface roughness (Ra) of the posts before and after surface treatment was measured using surface profilometer. The posts were examined under SEM for assessment of surface morphology. Sixty extracted primary maxillary anterior teeth were collected. After pulpectomy roots were filled with Metapex then surface treated fiber post were cemented with resin cement. Fracture resistance was measured using universal testing machine at a cross head speed of 0.5mm/min. Each sample was loaded at 135º along the long axis of the teeth on the mid-palatal surface until fracture.
Results :
There was statistical significant difference in the Ra value between the control group and all the tested groups (p<0.001). Sandblasting showed the highest significant mean Ra value while hydrofluoric acid had the lowest significant values. Fracture resistance results revealed a statistically significant difference between the control and all the treated groups except for group II (p=0.868). Subgroup B had the highest mean fracture resistance value (370 N +/-43.97) while group III showed the lowest mean value (111.78 N ±16.97).
Conclusion:
All the tested surface treatments method increased the surface roughness, and changed the surface morphology of the tested fiber posts. However, sandblasting and Er,Cr:YSGG 1.5W caused distinctive irregularities, fiber rupture and cracks. Surface treatments with Er,Cr:YSGG (2790 nm) 1W is an effective method for improving the fracture resistance of badly broken primary anterior teeth restored with fiber post.