Int. J. Oral Maxillofac. Surg. 2008; 37: 232–241doi:10.1016/j.ijom.2007.09.169, available online at http://www.sciencedirect.com

Clinical PaperOrthognathic Surgery

Stability and morbidity ofLe Fort I osteotomywith bioresorbable fixation:a randomized controlled trial

L. K. Cheung, I. H. S. Yip, R. L. K. Chow: Stability and morbidity ofLe Fort I osteotomy with bioresorbable fixation: a randomized controlled trial. Int. J.Oral Maxillofac. Surg. 2008; 37: 232–241. # 2007 International Association of Oraland Maxillofacial Surgeons. Published by Elsevier Ltd. All rights reserved.

0901-5027/030232 + 010 $30.00/0 # 2007 Intern

ational Association of Oral and Maxillofacial Surgeo

L. K. Cheung, I. H. S. Yip,R. L. K. ChowDiscipline of Oral & Maxillofacial Surgery,Faculty of Dentistry, The University of HongKong, Hong Kong

Abstract. A randomized controlled clinical trial was conducted to compare the use ofbioresorbable and titanium mini-plates and screws in Le Fort I maxillaryosteotomies for evaluation of clinical morbidity and stability. Forty patientsrequiring Le Fort I osteotomies were randomly assigned to two groups. One groupunderwent bioresorbable mini-plate fixation and the other titanium mini-platefixation. Stability of the maxilla was determined by serial cephalometric analysis at2 and 6 weeks and at 3, 6 and 12 months postoperatively. Subjective and objectiveassessment of clinical morbidity was made prospectively. There were no differencesin complications between the two fixation materials. Maxillae with bioresorbablefixation were significantly more mobile at the second postoperative week.Bioresorbable plates were initially more easily palpable, but their palpabilitydecreased with time. Titanium plates became significantly more palpable at the1-year follow-up. There was no difference in neurosensory disturbance betweengroups. Patients with bioresorbable plate fixation showed significantly more upwarddisplacement in anterior maxilla following impaction and posterior maxillafollowing downgrafting from the 2nd to 6th postoperative week. The horizontal andangular relapses in the two groups were comparable. Le Fort I osteotomy withbioresorbable fixation results in no greater morbidity than with titanium fixation upto 1 postoperative year.

Key words: bioresorbable fixation; Le Fort Iosteotomy; stability; morbidities.

Accepted for publication 10 September 2007Available online 19 November 2007

Internal fixation by plates and screws hasbecome the gold standard for stabilizationof bone segments in orthognathic surgery.The dimensions of the plates and screwshave been miniaturized for intraoralaccess, and titanium plates have gradually

replaced stainless steel and vitaliumplates. Titanium is now widely acceptedas the metal with the best biocompatibilityand also has good mechanical properties.

Studies have shown that titanium platesimplanted in the body for a long time may

give rise to problems. KIM et al.27, in thelight of their findings of local macroscopicand microscopic tissue damage around theimplanted titanium plates, proposed thatall titanium plates should be removedroutinely after bone healing. SCHMIDT

ns. Published by Elsevier Ltd. All rights reserved.

Stability and morbidity of Le Fort I osteotomy with bioresorbable fixation: a randomized controlled trial 233

Fig. 1. Mini-plate fixation at the zygomatic buttress and piriform region in Le Fort I osteotomy:

Table 1. Random errors of maxillary measurements on 40 cephalographs between two timepoints 1 week apart

Variables Random error

Horizontal movement of A-point (mm) 0.34Horizontal movement of P-point (mm) 0.36Vertical movement of A-point (mm) 0.3Vertical movement of P-point (mm) 0.24SN to UI (8) 1.3

et al.37 reported that 10% of patients fol-lowing Le Fort I osteotomies requiredplate removal. The reasons for plateremoval included palpability, sinusitis,pain, infection, temperature sensitivityand patients’ request. MOSBAH et al.34

reported a similar percentage of patientsrequired metal plate removal after orthog-nathic and trauma surgery. Although rou-tine removal of metal mini-plates has beenadvocated by some authors, most surgicalcentres consider prophylactic removal ofmetal plates necessary only for stainlesssteel plates, and not for titanium plates.

The feasibility of applying bioresorb-able plates and screws for fracture fixationwas first demonstrated in orthopaedic sur-gery36. This technique was soon extendedto cranio-maxillofacial surgery for frac-ture and osteotomy fixation6–10,16–18,20,31.The fixation devices consist of a combina-tion of different bioresorbable polymersincluding polylactide, polyglycolide andtheir co-polymers, so as to achieve a bal-ance between mechanical strength, bend-ability, miniaturization and resorptiontime.

There have been a number of clinicalreports3,4,11–15,19,21–23,25,26,28–30,32,33,35,38–42

on bioresorbable plate fixation in orthog-nathic surgery. These studies were mainlyconcerned with postoperative morbiditiesfollowing the use of these materials. Dataon maxillary stability following Le Fort Iosteotomies have been reported in onlya few studies8,21,35,41. Randomized con-trolled trials with adequate follow-up arelacking. The aim of this study was toconduct a randomized controlled clinicaltrial to compare bioresorbable with tita-nium mini-plates and screws for fixationin Le Fort I maxillary osteotomies, and toevaluate clinical morbidity and stability.

(a) titanium plates; (b) bioresorbable plates.

Materials and methods

The randomized controlled clinical trialwas conducted from February 2003 to July2005. The study was approved by theEthics Committee of the Faculty of Den-tistry, The University of Hong Kong.Patients of age 16 or above presentingwith dento-facial deformities requiringLe Fort I osteotomy were recruited.Patients with underlying systemic dis-eases, congenital craniofacial deformitiessuch as cleft lip and palate, and patholo-gical diseases of the jaws were excluded.Forty patients satisfying the inclusion cri-teria were selected. Patients were assignedinto two groups of 20 patients eachaccording to a randomization table1. Thepatients in the bioresorbable group under-went bioresorbable mini-plate and screw

fixation (2.0 compact plating system,Inion Ltd., Tampere, Finland) of the trans-posed Le Fort I maxilla at the zygomaticbuttress and piriform region of each side(Fig. 1b). Four mini-plates and 16 mini-screws were routinely used. The patientsin the titanium group underwent titaniummini-plate and screw fixation (SynthesInc., OH, USA) at the same locations asthe bioresorbable group (Fig. 1a).

Preoperative assessment

A standardized protocol was used torecord preoperative information such aspatients’ age, gender, skeletal diagnosisand baseline neurosensory values. Theneurosensory status of the infra-orbital

nerve was assessed objectively on theinfra-orbital skin at an intersecting point2 cm below the lower eyelid and 2 cmlateral to the alar of the nose on both sides.Objective tests such as static light touchthreshold, two points discrimination andpain threshold were used. The static lighttouch test was performed using a Touch-Test Sensory Evaluator kit (NC12775,North Coast Medical Inc., CA, USA).Individual filaments of ascending dia-meters were pressed against the infra-orbi-tal skin until they bent. The minimumforce that elicited a positive response wererecorded. The two points discriminationtest was carried out by a disc of pairedblunt pins at increasing separation dis-tances. The data of minimum distance that

234 Cheung et al.

a patient could identify as two distinctpoints was recorded. For the pain thresh-old test, a pin was mounted onto an ortho-dontic pressure gauge. The minimumforce in grams that could trigger a painfulsensation in a patient was recorded.

Intraoperative assessment

Standardized Le Fort I osteotomies wereperformed on all patients under generalanaesthesia. The maxillae were downfrac-tured, mobilized and segmentalizedaccording to the surgical plan. The max-illae were guided to the pre-planned posi-tion by a custom-made occlusal wafer.The maxillae in both groups were simi-larly fixed by two mini-plates and screwson each side at the piriform rim and thezygomatic buttress regions. For the bior-esorbable group, plates of appropriateshapes were softened by immersion in awarm water bath (55 8C) and then manu-ally bent into the appropriate shape. Thefinal plate adaptation was achieved bypliers. Each hole was drilled and manuallytapped before the insertion of screwsbetween 4 and 6 mm long, according tothe bone thickness.

Two additional titanium micro-screws(Synthes Inc.) were inserted into the max-illae for radiographic landmark evalua-tion. One micro-screw was placed at themost concave part of the anterior maxillaat the midline (A-point) and another wasfixed to the posterior maxilla above themesial root of the first molar (P-point).

A standardized intraoperative protocolwas used to record any intraoperativecomplications and the plating time forthe Le Fort I osteotomy. Any concomitantmandibular osteotomies performed wererecorded.

Fig. 2. Reference planes and landmarks used in cephalometric analysis of stability.

Postoperative assessment

All patients had their first postoperativefollow-up appointment within 2 weeksand were then regularly reviewed at 6weeks and at 3, 6 and 12 months post-operatively. A standardized postoperativeprotocol was used to record any post-sur-gical complications. Neurosensory record-ings at the infra-orbital regions were takenat every postoperative follow-up appoint-ment. The subjective degree of mobility ofthe maxilla, ease of palpability of theplates and degree of pain at the surgicalsites were assessed using a visual analogscale ranging from 0 to 10. Clinical mobi-lity and palpability of plates were objec-tively assessed also by clinicians using thesame visual analog scales.

Stability assessment

The skeletal stability or relapse wasassessed by serial comparison of lateralcephalographs. Standardized lateral cepha-lographs were taken preoperatively and at 2and 6 weeks and 3, 6 and 12 months post-operatively. The cephalometric analysiswas modified from CHEUNG et al.5.Micro-screws landmarks were comparedon serial cephalographs to determine theextent and direction of relapse (Fig. 2). Theradiographic landmarks and referenceplanes for the cephalometric analysis were:sella (S) – the centre of sella turcica; nasion(N) – the suture between the frontal andnasal bone; A-point (A) – the deepest pointin the concavity of the anterior maxilla inthe midline (marked by a micro-screw); andP-point (P) – above the mesial root of thefirst molar (marked by a second micro-screw).

A horizontal reference plane was con-structed at 78 from a linear line connectingthe S and N points (SN line). The verticalreference plane was a line drawn perpen-dicular to the horizontal reference planeand passing through the sella. The shortestdistances of the A and P points in relationto the horizontal and vertical referenceplanes were measured. The intersectingangle formed between the central axis ofmaxillary central incisor to the SN line(SN to UI) was measured. Lateral cepha-

lographs were serially superimposed,based on the anatomical best fit of thecranial base and SN line. An electronicdigital caliper (Digit Cal, Tesa, Renens,Switzerland) with accuracy up to 2 deci-mal points was used to measure the dis-tances.

Statistical and error analyses

The data obtained were analysed by aStatistical Package for Social Sciences(SPSS 11.5 software, SPSS Incorporation,Chicago, USA). Independent t-tests wereused to determine the differences in para-meters of the bioresorbable and titaniumgroups.

The errors of cephalometric readingswere calculated based on measurementsof 40 randomly selected cephalographsfrom 20 patients who took part in thestudy. Landmark identifications and tra-cing of the position of micro-screws wereperformed and repeated 1 week later bythe same investigator. The extent of ran-dom error was determined by Dahlberg’sformula24 and reproducibility and reliabil-ity were assessed by a paired sample t-test.The random errors were small (Table 1)and there were no significant differences(P > 0.05) between the tracings at the twodifferent time points, confirming the relia-bility of the cephalometric measurements.

Stability and morbidity of Le Fort I osteotomy with bioresorbable fixation: a randomized controlled trial 235

Table 2. Maxillary diagnoses of 40 patients

Bioresorbablefixation (n = 20)

Titaniumfixation (n = 20)

Maxillary diagnosisMaxillary hypoplasia in

antero-posterior direction15 16

Vertical maxillary excess 2 3Dento-alveolar hyperplasia 2 0Maxillary canting 1 0Maxillary transverse hypoplasia 0 1

Table 3. Concomitant mandibular osteotomies

Bioresorbablefixation

Titaniumfixation

Hofer (mandibular subapical osteotomy) 10 10Bilateral vertical subsigmoid 13 10Bilateral sagittal split 3 1Combined subsigmoid and sagittal split 1 1Genioplasty 4 4

Results

Forty patients (17 males, 23 females) par-ticipated in this randomized controlledclinical trial. The mean age of the subjectswas 22 � 5.5 in the bioresorbable groupand 24 � 8.4 in the titanium group. Allpatients received preoperative orthodontictreatment.

Table 2 shows the maxillary diagnosesof the two groups. Most patients werediagnosed with maxillary hypoplasia inthe antero-posterior direction (75% ofpatients in the bioresorbable group and80% of patients in the titanium group).Segmentalization of the Le Fort I maxillaewas performed on 33 patients (83%). Themaxillae were segmentalized into fourpieces in 21 cases (55%), into two piecesin 11 cases (28%) and into three pieces in 1case (3%).

Concomitant mandibular osteotomieswere performed in all patients (Table 3).More than half the patients (58%) hadbilateral vertical subsigmoid osteotomiesfollowed by mandibular subapical osteo-tomies (50%). Some patients had two oreven three mandibular osteotomies at thesame time; need was based on the specificdiagnoses of dento-facial deformities.There were no statistically significant dif-ferences between the background and sur-gical information of the two groups(P > 0.05).

Fig. 3. Mobility of Le Fort I maxilla with internal fixation over time: (a) subjective assessmentby patients; (b) objective assessment by clinicians.

Intraoperative findings

No intraoperative complications werereported and the planned surgical proce-dures guided by the appropriate surgicalwafers were achieved in all cases. Allsurgical movements of the maxillae wereachieved as planned. The mean plating

time of the Le Fort I osteotomies was31.9 min for the bioresorbable plategroup and 20.5 min for the titanium plategroup. The difference in plating time wasfound to be statistically significant(P < 0.01).

All patients were followed up for atleast 6 weeks after the operation. Therewere no drop outs. Most of the patients(78%) were followed up for at least 3months, and more than half (53%) for atleast 6 months. Eleven patients (28%)were followed up for more than 1 year.

Postoperative complications

Maxillary sinusitis was reported in onepatient from each group. Sinusitis in thepatient with bioresorbable plate fixationoccurred within the 2nd week after opera-

tion, while the patient with titanium platefixation presented with sinusitis at the 3-month review appointment. The conditionwas resolved in both cases following treat-ment by antibiotics and nasal deconge-stant.

Subjective and objective clinical

evaluation

Mobility of the maxilla

The mobility score, as measured on the 10-point visual analog scale, was low overall(less than 2) (Fig. 3a and b). In bothgroups, the patients experienced a similarextent of maxillary mobility immediatelypostoperatively. This may be because theywere restricted to a soft diet during thisperiod. During the 6th week and 3rdmonth patients with bioresorbable fixationfelt that their maxillae were more mobile,especially at the 6th postoperative week.No patients reported any mobility at the 1-year follow-up.

When mobility was assessed objec-tively by clinicians, the maxilla wasconsistently more mobile in patients withbioresorbable fixation at all postopera-tive periods than in those with titaniumfixation. The differences were largest atpostoperative weeks 2 and 6. The differ-ences in objective mobility between thetwo plating groups became smaller astime progressed. A statistically signifi-cant difference was noted only for objec-tive mobility in the 2nd week, when themaxillae of patients in the bioresorbablefixation group were more mobile(P < 0.05).

236 Cheung et al.

Fig. 4. Palpability of fixation plates and screws in Le Fort I maxilla over time: (a) subjectiveassessment by patients; (b) objective assessment by clinicians.

Fig. 5. Pain score of the maxillary surgical wound by bioresorbable and titanium fixationfollowing Le Fort I osteotomy over time.

Table 4. Surgical movements in different directions of the maxilla at the radiographic A-pointand P-point with bioresorbable and titanium plate fixation

A-point P-point

Bioresorbable Titanium Bioresorbable Titanium

Palpability of plates

The scores on the visual analog scaleregarding palpability of plates were gen-erally also low (Fig. 4a and b). In bothsubjective and objective evaluation ofpalpability, the plates were not easilypalpable at the 2nd postoperative week.This was perhaps because of residual soft-tissue swelling. At the 6th week after theoperation the bioresorbable plates, whichare generally more bulky than titaniumplates, became more palpable. From the3rd month onwards the titanium platesbecame more easily palpable on both sub-jective and objective evaluation as thepostoperative swelling continued to sub-side. The bioresorbable plates became lesspalpable over time as they gradually sof-tened before eventually dissolving. Therewas a statistically significant difference inpalpability between the two groups at the1-year follow-up (P < 0.01).

Advancement 3.43 (2.03) 4 (2.45) 2.93 (2.08) 3.9 (2.04)Retrusion 1.12 (1.12) 1.59 (0.84) 1.36 (0.8) 1.3 (1.4)Impaction 2.65 (2.05) 3.27 (1.84) 2.49 (1.19) 2.79 (2)Downgraft 2.87 (1.94) 1.45 (1.1) 2.41 (1.77) 1.23 (1.17)

Values are in mm (SD).

Pain of surgical wounds

The pain score was highest at the 2-weekpostoperative point (Fig. 5). For patients

with titanium fixation, pain became mini-mal at the 6th week. For the bioresorbablefixation group, there was an initial reduc-tion of pain at the 6th week, but a higherlevel of pain at the 3rd month. This may bedue to an inflammatory reaction related tothe resorption of the bioresorbable plates.There were no statistically significant dif-ferences between the two groups at anytime point (P > 0.05).

Neurosensory evaluation

Static light touch threshold

Although patients with titanium plate fixa-tion seemed to have a lower sensation of

touch during the 2nd week, the mean mini-mum force to elicit a positive response wasless than 0.4 g (Fig. 6a). The light touchthreshold was so small that it could beconsidered as within the normal range.From the 6th week onwards, the light touchresults of both groups were essentially thesame. There was no statistically significantdifference between the two groups at thedifferent time points (P > 0.05).

Two points discrimination

The minimum distance that the patientscould distinguish was marginally higherin patients with bioresorbable fixationwithin the first 6 weeks postoperatively(Fig. 6b). At the 3rd month the two groupshad similar proprioception at the infra-orbi-tal regions. From the 3rd month onwards,patients with bioresorbable fixation hadincreased sensitivity of the cheeks, butthere was no statistically significant differ-ence between the two groups (P > 0.05).

Pain threshold

In both groups the minimum forcerequired to stimulate a painful responsedecreased postoperatively and becameconstant from the 3rd month onwards(Fig. 6c). This suggests that the infra-orbital nerves developed hyperesthesiaafter osteotomy, although none of thepatients made any complaint in thisrespect. There was no significant differ-ence between the two groups (P > 0.05).

Stability of the maxilla

The mean changes of different landmarkswere analysed according to the differenttime periods: T1, preoperative to post-operative 2 weeks; T2, 2 to 6 weeks;T3, 6 weeks to 3 months; T4, 3 to 6months; T5, 6 months to 1 year. Thesurgical movements are listed in Table 4.

Horizontal changes

For the anterior maxilla, there were mini-mal postoperative horizontal displace-ments following either advancement or

Stability and morbidity of Le Fort I osteotomy with bioresorbable fixation: a randomized controlled trial 237

Fig. 6. Results of neurosensory function tests on the infra-orbital skin following Le Fort Iosteotomy over time: (a) static light touch threshold; (b) two points discrimination; (c) painthreshold.

retrusion up to 1 year (Fig. 7a). The sam-ple size for anterior maxillary retrusionwas much smaller with only five patientsfrom each group (Fig. 7b). The retrusivemovements at the anterior maxilla weremainly for correction of dento-alveolarhyperplasia.

The amount of advancement and post-operative stability for the posterior max-illa followed a similar trend whencompared to the anterior maxilla(Fig. 8a). For posterior maxillary retru-sion, there were again only five patientsfrom each group (Fig. 8b). The differ-ence in horizontal relapse between thetwo groups was again not statisticallysignificant at all postoperative timepoints.

Vertical changes

Anterior maxilla for both groups demon-strated further upward displacement up to

1 year following impaction (Fig. 9a). Thebioresorbable group had more upward dis-placement up to 6 months postoperativelyand the difference at T2 was statisticallysignificant (P < 0.01). After downgraftingof the anterior maxilla, the amount ofsuperior displacement in the bioresorbablegroup was greater at T2 (Fig. 9b). Thedifference in superior displacement wasnot statistically significant between thetwo groups.

The vertical displacements of posteriormaxillae followed a similar trend afterimpaction and downgrafting. Followingdowngrafting, there was more upward dis-placement at T2 for the bioresorbablegroup (Fig. 10b), and the difference invertical displacement between the twogroups was statistically significant(P < 0.01). The differences in verticaldisplacements in other postoperative per-iods were not statistically significantbetween the two groups.

Angular changes of upper central incisor

There was a decrease in SN to UI angle inboth groups after the osteotomies(Fig. 11). This was likely related to thesurgical up-righting of the anterior maxillafrom segmentalization or change of occlu-sal plane. Overall, there was no statisticalsignificance in the angular changes at thedifferent time points (P > 0.05).

Discussion

The stability of Le Fort I osteotomies withbioresorbable fixation has been the subjectof only a few studies. EDWARDS & KIELY

11

mentioned that all maxillae were stable bythe 4th week with no further notable occlu-sal changes, but there were no quantitativemeasurements of maxillary stability. HAERS

& SAILER21 reported stability data of 10

patients with bioresorbable plate fixation.Unfortunately, there was no control groupfor comparison and the stability data wereavailable only for the postoperative periodup to 6 weeks. The most informative studywas carried out by NORHOLT et al.35. Theirrandomized controlled trial covered a totalof 60 patients who were followed up to 1year postoperatively, but they only pre-sented stability data up to 6 weeks andmerely reported that the maxillae werestable afterwards. The present randomizedcontrolled clinical trial is the first studyreporting the post-surgical stability andmorbidity of bioresorbable plate fixationfor Le Fort I osteotomies. The stability datawere recorded at regular periods exceeding1 year.

Maxillae with bioresorbable plate fixa-tion were confirmed to have minimalrelapse compared to titanium plate fixa-tion starting from the 6th postoperativeweek onwards, but vertical instabilityoccurred in the early postoperative period.These findings are consistent with a recentstudy by UEKI et al.41, in which the inves-tigators found that the maxillae werestable in the horizontal plane but tendedto displace superiorly following Le Fort Iosteotomy when combined with eithersagittal split or intraoral vertical ramusosteotomy. The results of the present studyindicate that this upward displacementoccurs during the 2nd to the 6th post-operative weeks. In another study byCOSTA et al.8, similar superior displace-ment of the maxilla occurred mainlywithin the first 8 postoperative weeks.These authors noticed a weak but signifi-cant relapse in the horizontal plane whichwas also related to the extent of maxillaryadvancement; this relationship could notbe demonstrated in the present study.

238 Cheung et al.

Fig. 7. Horizontal changes of the anterior maxilla at A-point with bioresorbable and titaniumfixation: (a) changes following maxillary advancement; (b) changes following maxillaryretrusion.

NORHOLT et al.35 also demonstrated amean superior displacement of the maxillashortly following Le Fort I osteotomieswith bioresorbable fixation. The amountof vertical displacement was less than1 mm and considered clinically unnotice-able. In contrast, the mean verticalchanges at both anterior and posteriormaxilla in this study were more than1 mm following maxillary impaction and

Fig. 8. Horizontal changes of the posterior maxfixation: (a) changes following maxillary advancem

2 mm after downgrafting. This amount ofmaxillary displacement would influencethe upper incisal exposure and would beclinically noticeable. Proportional over-correction of the osteotomy is hencerecommended in this directional move-ment.

Micro-screws were used as landmarkidentification to facilitate easy compari-sons of serial lateral cephalolographs. This

illa at P-point with bioresorbable and titaniument; (b) changes following maxillary retrusion.

method minimized the error in landmarkidentification and overcame the problemsof remodelling of the landmarks such asthe A-point and anterior nasal spine.Moreover, if dental landmarks are used,their positions are likely to be changed bypostoperative orthodontics.

Several investigators found that afterfixation with bioresorbable plates the max-illae had slight mobility immediately post-operatively11,14,35,38,40. This degree ofmobility was not usually quantified. Inthe present study, on a 10-point visualanalog scale, the mean subjective mobilitywas less than 1 at all time points, regard-less of the method of fixation. The lowmobility scores may be because thepatients were advised to restrict them-selves to a soft diet for at least 6 weeksafter the operation, or they had intermax-illary fixation for vertical subsigmoidosteotomies. The mean scores for mobilitywere almost doubled when assessed byclinicians, especially during the 6th week.The maxillae in the bioresorbable groupwere found to be significantly moreunstable at the early time points. Thesefindings suggest that, although the max-illae were clinically mobile after theoperation, the degree of mobility experi-enced by the patients was usually welltolerated.

This study found a low incidence ofcomplications in relation to internal fixa-tion. Maxillary sinusitis was diagnosed intwo patients, but the infection wasresolved following treatment with antibio-tics. It was difficult to prove whether thesinusitis was caused by the presence ofmini-plates or by the osteotomy itself.

Three patients presented with wounddehiscence and another three with plateexposure at the mandibular premolarregions. All these complications occurredwithin 3 months postoperatively. Fortu-nately, none of these wounds becameinfected. In bioresorbable plate fixation,when there are signs of wound dehiscence,swelling and redness of the wound, clin-icians will be concerned as to whetherthese complications are related to foreignbody reactions caused by the materials.BERGSMA et al.2 investigated the degrada-tion features of bioresorbable plates infixation of zygoma fractures. They foundthat all patients presented with painlessswellings at the site of implantation duringfollow-up. These swellings may be causedby an increase in tissue volume after thematerials degrade. The bioresorbableplates they used consisted of poly L-lac-tide, which is known for its incomplete-ness in resorption. In a review article onthe complications regarding bioresorbable

Stability and morbidity of Le Fort I osteotomy with bioresorbable fixation: a randomized controlled trial 239

Fig. 9. Vertical changes of theanteriormaxilla atA-pointwith bioresorbable and titanium fixation:(a) changes following maxillary impaction; (b) changes following maxillary downgrafting.

Fig. 10. Vertical changes of the posterior maxilla at P-point with bioresorbable and titaniumfixation: (a) changes following maxillary impaction; (b) changes following maxillary down-grafting.

Fig. 11. Change in SN to upper incisor angulation at different postoperative time points.

fixation in orthognathic surgery, LAINE

et al.29 reported that two patients withsagittal split osteotomies (1 month post-operatively) and another two patients withLe Fort I osteotomies (4 and 17 monthspostoperatively) presented with a granula-tion-type tissue over the plating area. Allthese tissue responses were found to beassociated with loose screws. In LANDES &KRIENER’s30 study, two patients were con-firmed to have foreign body granuloma atthe plating area following sagittal split

osteotomy with fixation of bioresorbableplates at the 3rd and 4th month postopera-tively. The specimens obtained from othersymptom-free patients confirmed that for-eign body reaction occurred around theplates at different times. These examplesindicate that it is difficult to assess whethera foreign body reaction will produce asignificant undesirable tissue response,and if so when it will happen. Mandibularwound dehiscence and plate exposure inthe bioresorbable fixation group in thepresent study did not seem to be relatedto a foreign body reaction. All casesoccurred in the early postoperative periodand no granulation tissue reaction wasobserved. It was likely that the plateswere placed too close to the dento-alveo-lus, or directly over the incision line ofthe surgical wounds. There is a need tofurther evaluate the soft-tissue response todegradation of bioresorbable materials byhaving a longer follow-up period withsoft-tissue biopsies at different times.

The plating time was significantlylonger for bioresorbable than for titaniummini-plate fixation, due to the need formanual tapping of the screw holes beforescrew insertion in the former procedure.One way to reduce the plating time is touse self-tapping screws or the Tacker pis-tol system developed by Inion Ltd. TheTacker pistol can only be used in thinbones; in thick bone, the screws cannotbe shot in completely and further tighten-ing by screwdriver is difficult. For stan-dardization of technique, it was decided totap the holes manually, which producedmore consistent screw insertion stabilitythan the tacking technique.

The palpability of the bioresorbable andtitanium plates was similar during theearly postoperative period. They werehardly palpable initially due to theexpected postoperative swellings. Aroundthe 6th week, when there was considerablereduction in swelling, the bioresorbableplates became easily palpable becausethey were bulkier than the titanium plates.From the 3rd month onwards the biore-sorbable plates became less palpable due

240 Cheung et al.

to softening and gradual resorption. Thepattern of changes in the palpability ofbioresorbable versus titanium mini-platesin this study was similar to a previousclinical trial of the Biosorb system4.

It was reassuring that the neurosensoryfindings had returned to the baseline read-ing as early as 6 weeks after Le Fort Iosteotomy. The neurosensory function inthe infra-orbital region was similar for thedifferent fixation materials used. This con-firmed that the degradation of bioresorb-able plates and screws did not lead to anyincrease in clinical neurosensory impair-ment. As the resorption process of bior-esorbable materials may take years tocomplete, it is necessary to further evalu-ate the effect of material degradation onneurosensory function with a longer fol-low-up.

In conclusion, bioresorbable plate fixa-tion is confirmed to be an acceptablealternative to conventional titaniummini-plate fixation in Le Fort I osteotomy.There were no significant differences inmorbidity in the 1st year following theoperation. Although bioresorbable platesare expected to be more easily palpable inthe early postoperative period, theybecome less palpable over time. The LeFort I maxilla with bioresorbable fixationis expected to be slightly mobile within thefirst 6 postoperative weeks but will firm upuneventfully afterwards with associatedsuperior displacement of the maxilla.The resorbable fixation tends to causemore vertical relapse following verticalmovements than titanium fixation in theearly postoperative period. The long-termstability of Le Fort I osteotomy in hori-zontal and vertical planes was similar forbioresorbable and titanium mini-platefixation.

Financial disclosure and products

The expenses for bioresorbable plates andtitanium plates were borne by patients whoparticipated in this study.

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Address:Lim Kwong CheungOral & Maxillofacial SurgeryPrince Philip Dental Hospital34 Hospital RoadHong KongTel: +852 28590267Fax: +852 28575570E-mail: lkcheung@hkucc.hku.hk