Sixty-one mandibular molar teeth with clinically manifest pulpitis, wh
ich required endodontic therapy, were studied. Twenty-seven subjects r
eceived standard inferior alveolar nerve block (IANB) with 2% lidocain
e HCI with 1:100,000 epinephrine and 34 subjects received IANB with 3%
mepivacaine with no vasoconstrictor. Pulpal anesthesia was assessed w
ith dichlorodifluormethane (DDM). Subjects who gave a positive respons
e to DDM were given a periodontal ligament injection with 2% lidocaine
with 1:100,000 epinephrine. This study showed that 3% mepivacaine HCl
is as effective as 2% lidocaine HCl in achieving pulpal anesthesia in
mandibular molars with IANB. Of a total 61 IANB with lip anesthesia,
23 subjects required peridontal ligament injection to achieve a negati
ve response to DDM. It was concluded that lip anesthesia is not a reli
able indicator of pulpal anesthesia. The use of DDM is a reliable meth
od of determining true pulpal anesthesia.