Help Needed Regarding Design Of Electronic Circuit.

design Of Circuit For Electronic Apex Locator

hi friends,
im doing a project on ELECTRONIC APEX LOCATOR, its a device used by dentists. i have to design a circuit which will measure the resistance of the teeth.the resistance of the teeth varies from 6Mhm: at the top of the teeth to 6khm: at the apical foramen. im unable to design a proper working circuit. kindly pls help me design the circuit. im running out of time.pls pls help me.
the parameters for the design of the circuit are as follows:
1) voltage= 28mV.
2) frequency= 8khZ
3) waveform shape= pulse.

regards,
amit

Use a multimeter?

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