Platelet-rich Fibrin and Grooving for Sagittal Split Osteotomy

Neurosensory Outcomes With Platelet-Rich Fibrin and Proximal Segment Grooving in Sagittal Split Osteotomy: A Randomized Clinical Trial

Sagittal split osteotomy (SSO) is a common operation done to move the mandible to correct dentofacial deformities and obstructive sleep apnea (OSA). Inferior alveolar nerve (IAN) injury and associated paresthesia is a well-known negative outcome following SSO, causing temporary or sometimes, permanent numbness in the chin and/or lip. There are limited methods to decrease the occurrence and duration of neurosensory dysfunction. Recent research has shown that platelet-rich fibrin (PRF) aids neurosensory recovery after SSO. Another method to minimize nerve injury is proximal segment grooving (PSG) to create space for the nerve to rest. This grooving method has never been formerly reported. The purpose of this study is to answer the following question: Among patients undergoing bilateral sagittal split osteotomy (BSSO) for dentofacial deformity or OSA, do those who receive PRF with or without PSG, compared to those who do not, have shorter times to functional sensory recovery (FSR) of the IAN? The null hypothesis is that there is no difference among 4 treatment groups and neurosensory outcomes. The specific aims of this proposal are to 1) enroll and randomize subjects who will undergo BSSO for correction of dentofacial deformity or OSA into 4 different treatment groups (PSG with PRF, PSG alone, PRF alone, neither PSG or PRF), 2) measure objective and subjective post-operative nerve function at fixed intervals post-operatively for up to 1 year, 3) compare differences in neurosensory outcomes among treatment groups, and 4) identify other variables that might be associated with differences in neurosensory outcomes.

Platelet rich fibrin (PRF) serves as a structural reservoir of cytokines such as platelet-derived growth factor (PDGF), transforming growth factor (TGF-b), insulin-like growth factor (IGF), platelet factor 4 (PF4) and vascular endothelial growth factor (VEGF) which aids in healing and preventing infection. PRF will be prepared as recommended by the manufacturer (Intra-Lock International) by centrifuging 20 mL of the subject's venous blood for 12 minutes at 2700 rpm, followed by compression. The fibrin clot will then be applied to the SSO site prior to fixation. The blood draw for the PRF will be performed approximately 15 minutes prior to fixation of the mandible. 20 mL will be drawn for each PRF side treated. The blood venous draw will be from the subject's arm or from an existing intra-venous line.

Proximal segment grooving is a mechanical method to create additional space within the inferior alveolar canal to allow the IAN to rest without compression or trauma. The surgeon uses a round or acrylic bur to cautiously remove any bony spicules, and remove cancellous bone in the proximal mandibular segment. PSG will be done by using an acrylic round bur on a surgical handpiece to remove 3 to 4 mm of cancellous bone where the IAN will passively rest into prior to fixation.

Adopted by the British Medical Research Council (MRC) scale, the primary outcome will be FSR, as defined as static 2-point discrimination less than 20 mm and superficial pain/tactile sensation without over-reaction on exam. Neurosensory parameters assessed will be Level A: static light touch, brush stroke direction and static 2-point discrimination; Level B: tensile light touch, using von Frey's hairs; and Level C: pinprick sensation (pain) and temperature.

Subjective IAN function will be measured using a visual analogue scale (VAS) and recorded as a continuous variable from 0-10. A score of 0 will represent anesthesia, 1-9 hypoesthesia and 10 normal.

Inclusion Criteria: Inclusion criteria include patients ages 18 and older, male or female, with a diagnosis of dentofacial deformity and/or OSA who will undergo BSSO. Exclusion Criteria: Exclusion criteria include patients with a history of previous mandibular surgery and preoperative neurosensory dysfunction of the trigeminal nerve. Other exclusion criteria are patients without capacity to consent for themselves or unable to read the consent form. Subjects who have conditions which may impair healing (such those on bisphosphonates treatments, blood thinners, corticosteroids, chemotherapy, etc.) will be excluded from participation in the research.