Why Crown Down can be dangerous for the patient?

[drmithila]

Why Crown Down can be dangerous for the patient?
Bigger and bigger, thats how taper in endo is going on, but what is the price to pay, many teeth are lost in few months/years, gross removal of coronal tooth material and then crown prep leads to this kind of fractures, see pic below-what will be left after crown prep?

        

[drmithila]

Objective
The aim was to compare the force required to fracture uninstrumented and instrumented canines and to investigate the root-reinforcing capability of AH Plus sealer.

Study design
In groups 1-3 (n = 24) canals were instrumented with either GT files, FlexMaster, or stainless steel hand instruments. Twelve teeth from each group were obturated with lateral compaction using gutta-percha and AH Plus. Group 4 (n = 12) acted as uninstrumented controls. The force required to fracture the roots was measured. ANOVA, Scheffé, and t test were used for statistical analysis.

Results
The intact roots were significantly stronger than all groups with instrumented and unobturated roots (P < .05). Roots enlarged with GT files were significantly weaker (P < .05) than those instrumented with FlexMaster or hand instruments. Between the obturated and unobturated roots there were no significant differences (P > .05).

Conclusions
The roots were significantly weakened by the preparation with greater taper instruments. An obturation with AH Plus did not increase the fracture resistance.

        

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