Although the sample size is small, this looks like an important study to read.
(This is the Medline record retrieved through Pub Med)

Brent N, Rudy SJ, Redd B, Rudy TE, Roth LA Sore nipples in breast-feeding
women: a clinical trial of wound dressings vs conventional care.  Arch Pediatr
Adolesc Med 1998 Nov;152(11):1077-82

BACKGROUND: Sore nipples in breast-feeding mothers are a common cause
of premature weaning, and are difficult to treat owing to recurrent trauma and
exposure to the infant's oral flora. OBJECTIVE: To compare the safety and
efficacy of a hydrogel moist wound dressing (Elasto-gel, Southwest
Technologies Inc, Baltimore, Md) with the use of breast shells and lanolin cream
in the treatment of maternal sore nipples associated with breast-feeding.
DESIGN: Randomized controlled trial comparing the above treatments for sore
nipples. Patients were seen for a maximum of 3 follow-up visits within 10 days,
or until the resolution of symptoms. SETTING: The Maternal-Infant Lactation
Center at the Mercy Hospital of Pittsburgh, Pittsburgh, Pa, a tertiary care
teaching hospital in inner-city Pittsburgh. PATIENTS: A referred sample of 42
breast-feeding women who presented to the Maternal-Infant Lactation Center
for the treatment of sore nipples. All patients with breast infection or chronic
unrelated pain conditions were excluded from the study. INTERVENTION:
After informed consent, patients were randomized to receive either a hydrogel
wound dressing or breast shells and lanolin. All patients underwent a history,
physical examination of the infant and the mother's breasts, assessment of breast-
feeding technique, and breast-feeding instruction. MAIN OUTCOME
MEASURES: The degree of pain on self-report questionnaires and the change
in scores for physical examination, breast-feeding technique, and pain behaviors
during breast-feeding. RESULTS: Although both treatments, in association with
instruction in breast-feeding technique, were effective, greater improvement was
seen in the group using breast shells and lanolin. This reached statistical
significance for physician-rated healing (P<.01) and self-reported pain (P<.05).
There were significantly more infections in the dressing group (P<.05), which
resulted in early discontinuation of the study. CONCLUSIONS: Prevention of
sore nipples by teaching proper technique on the initiation of breast-feeding
should be instituted. For those cases in which sore nipples do develop, breast
shells and lanolin in association with instruction in breast-feeding technique are
more effective than moist wound dressings. Lanolin and shells should remain
first-line therapy.

PMID: 9811284, UI: 99027423