Patient discomfort and other side effects after bilateral sagittal split osteotomy or distraction osteogenesis of the mandible: a randomized clinical trial


A randomized clinical trial was conducted to compare bilateral sagittal split osteotomy (BSSO) with distraction osteogenesis (DO) for the advancement of the mandible, with a focus on patient discomfort, postoperative pain, the need for analgesics, and occurrence of infection. All patients were non-syndromal, had a class II hypoplastic mandible, and had not undergone previous mandibular surgery. A total of 66 patients were allocated randomly to the BSSO group (32 patients) or the DO group (34 patients). Sixty-three patients were eligible for evaluation, 29 in the BSSO group and 34 in the DO group. Patients in the DO group experienced more pain after 6 days postoperative, and were administered more analgesics after 5 days postoperative than patients in the BSSO group ( P = 0.030 and P = 0.045, respectively). The operating time was significantly shorter for the BSSO group than for the DO group (78 min vs. 100 min, P = 0.024). All postoperative infections (12 in total) emerged in the DO group ( P = 0.005). All patients in the DO group had a second surgery in day care to remove the distractor, while two patients in the BSSO group needed plate removal. It is concluded that patients experienced more pain after DO, needed more analgesics postoperatively, and had more infections in comparison to the BSSO group.

The bilateral sagittal split osteotomy (BSSO) is the most frequently used surgical technique for advancement of the retrognathic mandible. The BSSO was first described by Trauner and Obwegeser and was modified by Dal Pont and Hunsuck. The most published complications of this procedure are neurosensory disorders of the inferior alveolar nerve and skeletal relapse. Other reported sequelae are bruises, oedema, limited mouth opening, and an unfavourable fracture, the so-called ‘bad split’.

With the introduction of distraction osteogenesis (DO) more than 20 years ago, it was suggested that DO would overcome the inherent disadvantages associated with BSSO. Although early reports on DO were promising, comparative studies between DO and BSSO revealed no differences. A recent prospective study comparing BSSO and DO for advancement of the non-syndromal hypoplastic mandible showed equal results with regard to the primary outcome parameters of skeletal stabilty and neurosensory disorders. In this respect BSSO and DO are comparable procedures.

The aim of the present study was to compare DO and BSSO with a focus on secondary outcome parameters such as operating time, blood loss, postoperative wound infection, postoperative pain scores, analgesic use, and overall costs. It was anticipated that the results from this study would provide further evidence in regard to whether DO should remain a justified alternative to BSSO for advancement of the mandible in non-syndromal class II patients.

Materials and methods

A prospective study was designed, and 66 patients were recruited between March 2008 and July 2011. The study was performed at the Department of Oral and Maxillofacial Surgery (OMFS) of the Isala Clinics, Zwolle, Netherlands, which is a training facility for senior oral and maxillofacial surgery residents. A staff surgeon (JdeL, FB, or EMB) and a resident performed all of the surgical procedures. The inclusion criterion was a non-syndromal skeletal class II patient. Exclusion criteria were age >35 years and previous mandibular surgery ( Fig. 1 ). After providing informed consent, the patients were allocated randomly to the DO or BSSO group. Randomization was performed using a randomly generated list ( ) with a fixed block size and no stratification.

Fig. 1
Design of the randomized clinical trial (DO, distraction osteogenesis; BSSO, bilateral sagittal split osteotomy).

The full results of this study regarding neurosensory disorders of the inferior alveolar nerve and skeletal stability have been published elsewhere. This study was approved by the hospital medical ethics committee.

Of the 66 patients enrolled, 32 were assigned randomly to the BSSO group and 34 to the DO group. For 11 patients, a Le Fort I osteotomy was performed simultaneously with the mandibular surgery (three patients in the BSSO group and eight patients in the DO group). In the BSSO group, two patients were lost during follow-up and one patient subsequently underwent a unilateral procedure. Thus a total 29 patients in the BSSO group and 34 patients in the DO group were available for evaluation ( Table 1 ).

Table 1
Patient characteristics.
Patients, n 32 34 66
Lost to follow-up, n 2 0 2
Conversion, n 1 a 0 1
Patients for evaluation, n 29 34 63
Male, n 12 16 28
Female, n 17 18 35
Age (years)
Mean 18.6 21.3 20.1
Range 14.3–26.7 14.7–34.8
Advancement (mm)
Mean 7.0 7.3 7.2
Range 4–12 5–12

BSSO, bilateral sagittal split osteotomy; DO, distraction osteogenesis.

a One male patient had a unilateral SSO.

The surgical procedure

The surgery was performed under general anaesthesia in both groups. Preoperatively, 2 g of cefazolin and 0.5 mg/kg dexamethasone were given intravenously. Another dosage of 10 mg dexamethasone was given at 8 and 16 h postoperatively. The patients in the DO group received feneticilline 500 mg three times a day for 5 days.

Bilateral sagittal split osteotomy (BSSO)

Local infiltration was performed with articaine (Ultracaine DS forte). After incision and reflection of the full-thickness mucoperiosteal flaps, a standard BSSO was performed according to the technique of Trauner and Obwegeser and as modified by Dal Pont and Hunsuck. The mandibular foramen was identified on the medial side of the ramus. The horizontal osteotomy just above the lingula was extended to the buccal side at the external oblique line and passed through the buccal cortex in the region of the first or second molar. The osteotomy was finished at the lower mandibular border. The osteotomy of the mandible was then completed with a Smith ramus separator and sagittal separator left/right (Biomet Microfixation, Jacksonville, FL, USA) without the use of chisels. After advancement, the mandible was positioned according to the planned occlusion using a thin interocclusal acrylic splint (wafer) and fixed with stainless steel intermaxillary wires.

The osteotomy was then stabilized with titanium miniplates (2.0 plates; Synthes GmbH, Solothurn, Switzerland). The miniplates were fixed with at least two monocortical 5- or 7-mm screws on each side of the osteotomy. The intermaxillary fixation was then released and the occlusion was checked. After 1 week, guiding elastic bands (if required) were placed for 4–6 weeks.

Distraction osteogenesis (DO)

The mucosa was infiltrated with articaine (Ultracaine DS forte). The mandibular body and angle were exposed and a buccal vertical bone incision including the mandibular lower border was made just behind the second molar. If present, the third molar was removed at this stage. The corticotomy was extended distal to the second molar, to the lingual side of the mandible, with a fissure bur. Before completion of the corticotomy, a unidirectional distractor device (Zurich Distractor; KLS Martin GmbH & Co, Tuttlingen, Germany) was adapted, installed, and fixed in place with at least two monocortical screws on each side of the distraction device. The distractor was placed parallel to the occlusal plane. After removal of the distractor, the corticotomy was completed on the lingual side of the mandible. Finally, the distractor device was reattached in the marked position and fixed with six monocortical screws. Before closure of the wounds, the distractor was activated to confirm proper functioning, and finally the distractor was returned to its original position. After a latency period of 5–7 days, the distractor devices were activated by 0.5 mm two times per day. Distraction was continued until a class I occlusion was achieved. Intermaxillary guiding elastic bands were used during this period to prevent opening of the bite. The bone consolidation period lasted 8–10 weeks, after which the devices were removed under general anaesthesia.

Perioperative protocol and questionnaires

Postoperatively, patients in the BSSO group were asked to refrain from chewing for 6 weeks and those in the DO group for 8–10 weeks.

During surgery the patients were given opioids. Patients were asked to record the pain they experienced on each postoperative day, starting the day after surgery, using a visual analogue scale (VAS) (0–100 mm). At the end of each postoperative day the patients recorded three VAS scores for pain: they were asked to register the lowest perceived pain score of the day, the highest perceived pain score of the day, and the pain score they were experiencing at the time they completed the VAS evaluation in the evening. The mean of these three VAS scores was calculated to give a final VAS score for each postoperative day.

Patients were also asked to register the daily number of analgesics administered. A combination of ibuprofen 600 mg three times a day and paracetamol 500 mg eight times a day was usually prescribed. For each painkiller, the score was related to the maximum dose per day for each drug. A score of 1 represented the maximum dose of one analgesic per day, and a score of 0.66 meant that the patient had used two-thirds of the maximum dose of that analgesic per day. Thus, if the patient used ibuprofen 600 mg three times a day, this was scored as 1; if the patient took the maximum prescribed number of ibuprofen and paracetamol, this was scored as 2. Some patients combined these two analgesics with a third – tramadol 50 mg three times per day. When these three analgesics were taken to the maximum, the score was 3.

Finally, the actual operating time, blood loss, total costs, and occurrence of postoperative infection related to the mandibular surgery were also recorded. The duration of hospital admission was registered for all patients.

Statistical analysis

The data were analyzed using SPSS version 18.0 software (SPSS Inc., Chicago, IL, USA). Continuous data were analyzed with a Student’s t -test and dichotomous data with a Pearson χ 2 test.


The mean reported VAS scores for pain and the numbers of analgesics taken each postoperative day are listed in Tables 2 and 3 . Unfortunately not all patients recorded the data adequately. The VAS scores for pain were completed fully by 16 patients (55%) in the BSSO group and 29 patients (85%) in the DO group. One patient in the BSSO group and two patients in the DO group recorded the VAS scores incompletely.

Table 2
Mean VAS scores for pain on postoperative days 1–8. a
Operation n Mean SD SEM
Pain VAS day 1 DO 29 31.45 19.965 3.707
BSSO 16 35.56 21.103 5.276
Pain VAS day 2 DO 31 36.26 19.931 3.580
BSSO 16 37.31 21.899 5.475
Pain VAS day 3 DO 31 32.71 19.761 3.549
BSSO 17 29.88 17.940 4.351
Pain VAS day 4 DO 31 29.39 18.237 3.275
BSSO 17 22.41 16.183 3.925
Pain VAS day 5 DO 31 26.03 15.738 2.827
BSSO 17 17.65 13.043 3.163
Pain VAS day 6 DO 31 28.55 20.133 3.616
BSSO 17 17.29 19.830 4.809
Pain VAS day 7 DO 31 28.32 19.997 3.592
BSSO 17 11.53 12.228 2.966
Pain VAS day 8 DO 31 28.16 19.460 3.495
BSSO 17 9.18 11.041 2.678
VAS, visual analogue scale; DO, distraction osteogenesis; BSSO, bilateral sagittal split osteotomy; SD, standard deviation; SEM, standard error of the mean.

a Days 1–6, P > 0.05 not significant; day 7, P = 0.03 significant; day 8, P = 0.01 significant.

Table 3
Mean analgesics administered per day. a
Operation n Mean SD SEM
Analgesics day 1 DO 29 1.00734 0.511266 0.094940
BSSO 18 1.14822 0.610924 0.143996
Analgesics day 2 DO 30 1.03890 0.549093 0.100250
BSSO 18 1.12272 0.601757 0.141835
Analgesics day 3 DO 30 0.94310 0.587518 0.107266
BSSO 18 0.90983 0.434078 0.102313
Analgesics day 4 DO 30 0.94420 0.650810 0.118821
BSSO 18 0.79172 0.457851 0.107917
Analgesics day 5 DO 30 0.93333 0.591471 0.107987
BSSO 18 0.63428 0.397065 0.093589
Analgesics day 6 DO 30 0.88477 0.627218 0.114514
BSSO 18 0.53711 0.444927 0.104870
Analgesics day 7 DO 30 0.81537 0.621666 0.113500
BSSO 18 0.42128 0.404473 0.095335
Analgesics day 8 DO 30 0.74033 0.673790 0.123017
BSSO 18 0.33800 0.393509 0.092751
Analgesics day 9 DO 30 0.61803 0.597266 0.109045
BSSO 18 0.28239 0.381527 0.089927
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Jan 17, 2018 | Posted by in Oral and Maxillofacial Surgery | Comments Off on Patient discomfort and other side effects after bilateral sagittal split osteotomy or distraction osteogenesis of the mandible: a randomized clinical trial
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