An evaluation of the changes in maxillary pulpal blood flow associated with orthognathic surgery.

The objective of this study was to evaluate the use of the Laser Döppler Flowmeter (LDF) in the measurement of pulpal blood flow following orthognathic surgery and to conduct an initial study of the effects of a Le Fort I osteotomy on the pulpal blood flow of the maxillary central incisors. The design consisted of a preliminary prospective controlled consecutive clinical trial undertaken at the Orthodontic Clinic, University Dental Hospital NHS Trust, Wales, 1994. The study group consisted of 15 consecutive patients who were to receive a standard advancement Le Fort I osteotomy. Seven patients who were to undergo a mandibular advancement only acted as a control. A further 20 separate patients participated in a study for the assessment of measurement error. The blood flow in relative perfusion unit v. time, was measured using a Laser Döppler Flowmeter. Measurement error for flowmeter recordings with hand-held application and custom-made splint support showed no consistent difference or significant random variation between the two methods for holding the probe against the teeth (pooled S.D. of reproducibility 1/1 = 1.91/1.39 for custom splint location as opposed to 0.96/1.07 for hand-held/fixed bracket location). For the surgical patients under investigation no significant differences for maxillary pulpal blood flow were found in the control group (mandibular osteotomy) over time. However, in the maxillary osteotomy patients there was a tendency for an initial rise in the maxillary perfusion post-surgery as measured at the central incisor pulps, followed by an overall reduction at 6 months. As an example, the mean value for the upper right central showed a significant increase in blood flow during the immediate post-operative period (P < 0.05), but at 6 months after surgery demonstrated a statistically significant overall reduction in comparison with the presurgical reading (P < 0.001). The laser Döppler flowmeter is not an easy instrument to use in the clinical assessment of pulpal blood flow. However, it would appear from these longitudinal series of readings, taken over a 6-month period on 15 patients, that the maxillary perfusion recorded at the central incisor pulps may be permanently affected in many Le Fort I osteotomy patients. For patients that already have a prejudiced blood supply this could lead to devitalization and discoloration of incisors. It is not known if this affect on the perfusion of the pulp continues beyond 6 months post-surgery.