Filling material can be problematic to the oral tissues because it can cause:

irritation to the pulp
transfer to the pulp
current to be set up

Filling techniques can be a problem for the oral tissues because:

can injure the gingiva
Poor restoration margins can lead to caries
Poor occlusal relationship can lead to apical pressure and

Over instrumentation of root canals can lead to lesions but under instrumentation can lead to being left in the canals.

In terms of impression taking, these factors could affect the oral tissues:

Too fluid material = problems
Exothermic material (such as impression ) can cause
Wrong size tray = injuries

When taking biopsys the following factors should be considered:

Avoid taking biopsies of lesions
Make sure the sample is
Include normal tissue as a
Avoid of tissues
If the patient has no confidence in the practitioner
If the patient is in
If the lesion is large but
If it is not accessible at the time
If there is at the site
If there is uncontrolled disease

In terms of different types of biopsies:

Excisional = of tissue
Incisional = p removal of tissue
Extemporary = in t
Exfoliative = tests
Fine needle aspiration = if in via scalpel such as in the glands