A comparative assessment of maxillary perfusion between two different Le Fort I osteotomy techniques

Abstract

Compromised maxillary perfusion following Le Fort I osteotomy is a potentially serious complication resulting in hard and/or soft tissue loss. The aim of this study was to compare the change in perfusion between two techniques of posterior maxillary disjunction by intraoperative measurement of maxillary gingival blood flow (GBF). Further, we sought to correlate the association of the movement of the maxilla and estimated blood loss as factors. The study population comprised 38 individuals, divided equally into two groups: a pterygoid disjunction group and a third molar socket disjunction group. GBF was measured using Doppler flowmetry. A P -value of <0.05 was considered significant. There was a significant drop in GBF in both groups. However, there was no significant difference between the groups based on magnitude of blood flow drop. Superior repositioning of the osteotomized maxilla caused the greatest drop in GBF, which was statistically significant. There was significantly less blood loss in the pterygoid disjunction group. In conclusion, Le Fort I osteotomy causes a significant decrease in GBF. The technique used for posterior maxillary disjunction does not influence the magnitude of drop in perfusion. There is a significant correlation of other factors such as the effect of superior repositioning of the maxilla and blood loss with the osteotomy techniques.

Maxillary osteotomy surgery/orthognathic surgery is advised when an abnormally positioned jaw is giving rise to skeletally based malocclusions or cosmetic problems. It is also used to correct other problems such as obstructive sleep apnoea, to gain access to advanced tumours with intracranial extensions, and for other base of skull surgeries. A more recent use has been in the management of oculo-facio-cardio-dental syndrome.

The Le Fort I osteotomy for maxillary orthognathic surgery is based on the fracture lines described in the widely accepted classifications for midface fractures by the French military surgeon Rene Le Fort in 1901. Various techniques for the Le Fort I osteotomy have been developed over the years, by many surgeons, including that of down-fracture and posterior maxillary disjunction.

The main problem of the various techniques for the Le Fort I osteotomy is intraoperative bleeding and maintaining the blood supply to the osteotomized segment. The control of bleeding and vascular preservation after complete mobilization of the maxillary segments in order to avoid vascular necrosis were the main concerns of maxillofacial surgeons at the beginning of Le Fort I type osteotomy surgery. Avascular necrosis related to a lack of blood supply was one of the main complications after Le Fort I osteotomy and has been reported in some studies.

For these reasons, Turvey and Fonseca performed vascular studies on the maxillary artery anatomy and reported the importance of an accurate surgical technique in the posterior maxilla to preserve the integrity of the maxillary artery. The importance of posterior soft tissue pedicles for maxillary blood supply was investigated by Bell, Justus et al. (Doppler analysis), and Buckley et al., who suggested attention to vascular risk, particularly in patients using orthodontic appliances or post-surgical splints, which may induce unwanted pressure on the soft tissue pedicle. Tooth modification with narrowing of the pulp canals after Le Fort I osteotomy was investigated by Ellingsen and Artun. Life-threatening complications following Le Fort I osteotomies were, however, deemed to be very rare.

The main problems related to vascular compromise after maxillary mobilization are rupture of the descending palatal artery, postoperative thrombosis, perforation of the palatal mucosa in segmented maxillary surgery, and partial stripping or excessive tension of the palatal fibro-mucosa in maxillary expansion. Anatomical irregularities such as craniofacial dysplasia and orofacial clefts, as well as vascular anomalies, increase the risks of vascular problems following maxillary osteotomy surgery. In particular, in the segmented Le Fort I osteotomy, palatal fibro-mucosa preservation is an important factor to avoid partial necrosis and malunion of the maxillary bone fragments, especially in patients with orthodontic appliances or palatal splints causing pressure on the palatal mucosa. In cases of multi-segmental Le Fort I osteotomy, palatal perforations anteriorly in a horizontal direction are more worrisome from a vascular standpoint than perforations more posteriorly that are parallel to the direction of the greater palatine artery. Palatal perforations can be important even in single-piece Le Fort I osteotomies if there is a horizontal tear in the mucosa at the junction of the hard and soft palates, which can occur with a traumatic maxillary down-fracture.

Compromised maxillary perfusion and ischaemia following Le Fort I osteotomy is a potentially serious complication resulting in hard and/or soft tissue loss. Various studies have assessed the effect of the Le Fort I osteotomy on maxillary perfusion intraoperatively using Doppler flowmetry. However, none of the studies have compared the different techniques for performing the pterygomaxillary separation. The majority of studies have compared the perfusion of the maxilla to that of the mandible following an osteotomy—a setting that cannot control for all of the factors associated with the maxillary anatomy and osteotomy. Posterior maxillary disjunction in Le Fort I osteotomies is done most commonly at the junction of the maxillary tuberosity and the pterygoid plates, or through the maxillary tuberosity (third molar socket) area itself. However no clinical study has yet compared the intraoperative change in maxillary perfusion between the two techniques using Doppler flowmetry.

The aim of the present study was to evaluate the difference in perfusion, by intraoperative measurement of maxillary blood flow, between the two maxillary osteotomy techniques—separation at the junction of the maxillary tuberosity and the pterygoid plates, or through the maxillary tuberosity (third molar socket) area.

Materials and methods

This was a prospective randomized cohort study conducted over a period of 18 months. The study population comprised patients undergoing a Le Fort I osteotomy for an orthognathic surgical procedure at our institution. The total study population was 38 (statistical power of 80%); 14 were males and 24 were females. These patients satisfied the following inclusion criteria: ASA 1 patient (American Society of Anesthesiologists); no history of maxillary surgery. The patients were divided randomly into two groups of 19 patients each based on a lots system. Group 1 ( n = 19) underwent disjunction of the maxilla at the junction of the pterygoid plate level and group 2 ( n = 19) underwent disjunction of the maxilla through the third molar socket. Eight patients in group 1 and five patients in group 2 underwent multi-segmental maxillary osteotomies (Le Fort I osteotomy and maxillary anterior segmental osteotomy). The disjunction in both groups was performed using a curved pterygoid chisel. The outcome variables were mean gingival blood flow (GBF), movement of the maxilla, and estimated blood loss. The two groups were controlled for the direction of movements. All patients underwent induced hypotension at the time of administration of the general anaesthetic.

The assessment of perfusion was based on microcirculatory vascular flow of the attached gingiva between the central and lateral incisor. A micro-probe was used with the Bidop ES-100V3 handheld Doppler (Kody Medical Electronics Pvt Ltd). The anterior maxillary GBF was measured in centimetres per second. Readings were taken at five intervals: T0, preoperative; T1, after intubation; T2, after down-fracture of the maxilla; T3, after fixing the maxilla in the new position; T4, after extubation. We used a hand-held probe technique because of the difficulty of using probe-positioning splints in patients with fixed appliances and orthodontic archwires.

Local anaesthesia with a vasoconstrictor was used to infiltrate the maxillary mucosa for all patients at the beginning of surgery ; hypotensive anaesthesia was used for all patients.

Movement of the maxilla was recorded based on preoperative planning and on-table decisions and execution. In group 1, 14 patients underwent intrusion of the maxilla and five underwent extrusion; in group 2, all patients underwent intrusion of the maxilla. No patients in group 2 underwent maxillary extrusion. Estimated blood loss (EBL) was calculated by measuring the contents of the suction collection bottle and deducting the amount of normal saline used for irrigation. Care was taken to ensure that gauze was not used to mop up any blood and that the suction collection bottle was empty prior to surgery.

Consent for the study was obtained from the patients before they underwent the surgery. The nature of the study and its purpose was explained to them. The patients were given the choice to participate and at no time were they forced or coerced into being a part of the study.

The statistical analysis was done using IBM SPSS version 22.0 (IBM Corp., Armonk, NY, USA). P -values of <0.05 were considered statistically significant.

Results

The study was conducted among patients who underwent maxillary orthognathic surgery of the Le Fort I type with/without concomitant segmental or mandibular osteotomy. A total of 38 subjects volunteered and met all the inclusion and exclusion criteria. The sample had a mean age of 22 years; 36.8% were males and 63.2% were females.

The groups were comparable with regard to age distribution, preoperative haemoglobin, bleeding time, and clotting time, with similar means and no statistically significant difference. The drop in anterior maxillary GBF over the intraoperative course of surgery was found to be statistically significant within each group ( P < 0.001) ( Table 1 ).

Table 1
Friedman test to compare the blood flow between time points.
Group Mean rank P -value
Third molar socket disjunction
GBF (cm/s): T0 4.42 <0.001
GBF (cm/s): T1 4.47
GBF (cm/s): T2 2.71
GBF (cm/s): T3 1.89
GBF (cm/s): T4 1.50
Pterygoid disjunction
GBF (cm/s): T0 4.47 <0.001
GBF (cm/s): T1 4.47
GBF (cm/s): T2 2.58
GBF (cm/s): T3 1.66
GBF (cm/s): T4 1.82
GBF, gingival blood flow.

The comparative drop in anterior maxillary GBF over the intraoperative course of surgery was found not to be statistically significant between the two groups ( P = 0.571) ( Fig. 1 ; Tables 2 and 3 ). Comparison between the two groups for the drop in GBF based on only maxillary surgery or both maxilla and mandibular surgery also showed no statistically significant association. Performing the maxillary osteotomy in multiple segments versus a one-piece Le Fort I osteotomy had no statistically significant effect on GBF.

Fig. 1
Magnitude of the drop in gingival blood flow between the groups.

Table 2
Mann–Whitney test for comparisons of blood flow between groups.
Variable Group Number Mean rank P -value
GBF (cm/s): T0 Third molar socket disjunction 19 20.11 0.707
Pterygoid disjunction 19 18.89
GBF (cm/s): T1 Third molar socket disjunction 19 20.58 0.526
Pterygoid disjunction 19 18.42
GBF (cm/s): T2 Third molar socket disjunction 19 22.21 0.080
Pterygoid disjunction 19 16.79
GBF (cm/s): T3 Third molar socket disjunction 19 22.42 0.053
Pterygoid disjunction 19 16.58
GBF (cm/s): T4 Third molar socket disjunction 19 18.32 0.452
Pterygoid disjunction 19 20.68
GBF, gingival blood flow.

Table 3
Magnitude of blood flow drop: Mann–Whitney test.
Group Number Mean rank P -value
Third molar socket disjunction 19 20.42 0.571
Pterygoid disjunction 19 18.58

The effect of the direction of maxillary movement on GBF was compared within each group and between the two groups. Only superior repositioning of the maxilla showed a statistically significant influence on GBF, at the T3 time interval ( P = 0.049) within each group ( Fig. 2 ; Table 4 ). There was no statistically significant influence of maxillary movement between the two groups.

Fig. 2
Association between movement of the maxilla and gingival blood flow.

Table 4
Pearson’s correlations between maxillary movement and blood flow.
Movement of maxilla (mm)
Superior Posterior Anterior
GBF (cm/s): T0
Correlation 0.044 0.054 −0.593
P -value 0.812 0.816 0.292
Number 32 21 5
GBF (cm/s): T1
Correlation −0.028 0.043 −0.563
P -value 0.880 0.854 0.324
Number 32 21 5
GBF (cm/s): T2
Correlation 0.349 0.144 −0.074
P -value 0.051 0.532 0.906
Number 32 21 5
GBF (cm/s): T3
Correlation 0.350 −0.064 −0.033
P -value 0.049 0.784 0.957
Number 32 21 5
GBF (cm/s): T4
Correlation 0.254 0.215 0.367
P -value 0.161 0.348 0.543
Number 32 21 5
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Jan 17, 2018 | Posted by in Oral and Maxillofacial Surgery | Comments Off on A comparative assessment of maxillary perfusion between two different Le Fort I osteotomy techniques
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