Leading Clinical Paper

Orthognathic Surgery

Int. J. Oral Maxillofac. Surg. 2011; 40: 662–671doi:10.1016/j.ijom.2011.03.005, available online at http://www.sciencedirect.com

Lateral cephalometry changesafter SARPEA. Parhiz, S. Schepers, I. Lambrichts, L. Vrielinck, Y. Sun, C. Politis: Lateral cephalometrychanges after SARPE. Int. J. Oral Maxillofac. Surg. 2011; 40: 662–671. # 2011International Association of Oral and Maxillofacial Surgeons. Published by ElsevierLtd. All rights reserved.

Abstract. Surgically assisted rapid palatal expansion (SARPE) is associated withpostoperative cephalometric changes. In this study we analyse these changes in thesagittal plane in orthognathic patients undergoing SARPE followed by orthodontictreatment and Le Fort I, bilateral sagittal split osteotomy (BSSO), or bimaxillarysurgery. This is a retrospective review of 50 patients (20 males, 30 females)undergoing orthognathic treatment with SARPE to correct transversal deficiency ofthe maxilla as part of a comprehensive treatment plan. PP-SN, SNA, and ANBangles were increased and U1-SN and U1-PP angles were decreased. All changeswere statistically significant. Changes of SNB, PP-Mand plane angle, and SN-Mand. plane angle were not statistically significant. Surgically assisted rapid palatalexpansion using a bone-borne appliance as a preparative step for later orthognathicsurgery results in clockwise rotation of the maxilla.

0901-5027/070662 + 010 $36.00/0 # 2011 International Association of Oral and Maxillofacial Surge

A. Parhiz, S. Schepers, I. Lambrichts,L. Vrielinck, Y. Sun, C. PolitisDepartment of Oral Maxillofacial Surgery,St. John’s Hospital, Genk, Belgium

Key words: surgically assisted rapid palatalexpansion; SARPE; lateral cephalometrychanges.

Accepted for publication 4 March 2011Available online 12 April 2011

In orthognathic surgery, correction of themaxillary transversal dimension via LeFort I expansion osteotomy is one of theleast stable movements21,22. Relapse ismost common during the first postopera-tive year. The authors’ approach to correcttransverse maxillary deficiency in non-syndromic adolescent or adult orthog-nathic patients is to perform multisegmen-tal Le Fort I osteotomy when an expansionof less than 5 mm in the molar area isneeded in adults or when a dual-planemaxilla is present. In other cases, a pre-liminary surgically assisted rapid palatalexpansion (SARPE) is preferred19. Thisoperation is performed at least 1 yearbefore the planned Le Fort I procedureand allows for simultaneous extraction ofpremolars and/or third molars, because ofthe bone-borne nature of the transpalataldistractor.

Transverse maxillary hypoplasia is afrequent finding in non-syndromic adoles-cents and adults20. Non-surgical treatmentoptions to correct transverse maxillaryhypoplasia in children and young adoles-cents are slow maxillary expansion (SME)for mild discrepancies or rapid maxillaryexpansion (RME) for more severe cases.Owing to the increased skeletal resistance,RME in adults is associated with alveolarbending, periodontal ligament compres-sion, buccal root resorption of the anchorteeth, fenestration of the buccal corticalplate, and tipping and extrusion of theanchor teeth2. The negative effects arepresumably due to the tooth-borne ancho-rage of conventional appliances. Tooth-borne appliances deliver stress to the rootsand periodontal ligament as well as thealveolar bone during expansion. Addition-ally, the bony movement is not retained

during the consolidation period27. This ledto the introduction of the first bone-borneappliance (distractor) in 1999, which deli-vers the expansion force directly to themaxillary bone and avoids the negativeorthodontic and periodontal effects15.

After MOMMAERTS introduced the ‘Trans-palatal Distractor’ (TPD) in 1999, research-ers evaluated the dental and skeletal effectsof this appliance. Most of these studiesfocused on the amount of transverse expan-sion after activating TPD or its dental andperiodontal effects8,14,18,23,26. In this studythe authors analyse the lateral cephalo-metric changes associated with TPD.

Materials and methods

Of 280 patients treated by SARPE usingTPD from July 2000 to February 2010 inHasselt University, Belgium, 50 patients

ons. Published by Elsevier Ltd. All rights reserved.

Lateral cephalometry changes after SARPE 663

(20 male, 30 female) who also underwentorthognathic surgery after palatal expan-sion were selected.

Pretreatment records, including poster-oanterior (PA) and lateral cephalograms,panoramic and periapical radiographs,intraoral and extraoral photographs, andstudy models were taken for all patients.The lateral cephalometric radiograph wastaken using the Orthophos XG Plus (SIR-ONA Company). Using Onyx software, theSNA, SNB, ANB, PP-SN plane angle, PP-Mand. (angle between palatal plane andmandibular plane), SN-Mand. angle (anglebetween SN plane and mandibular plane),U1-palatal plane angle, and U1-SN planeangle were measured and recorded (Fig. 1).

Under general anaesthesia, MOM-

MAERTS’ TPD appliance15 was mountedonto the molar region of the palate.Mid-palatal osteotomy with Le Fort Iosteotomy and nasal and pterygopalataldisjunction was performed in all patients(Fig. 2). Adequate mobilization of themaxillary halves was checked both withthe osteotome and with activation of the

Fig. 1. Cephalometric tracing illustrating measur(angle 3), U1-SN (angle 4), U1-PP (angle 5), PPand SN plane), PP-mandibular plane angle (angleand SN-mandibular plane angle (angle betweedepression point in the anterior of maxilla (A pmandibular (B point), middle of sella (S point),

plane passed from coronal tip and root apex of

nasal spine to posterior nasal spine (palatal planepoint (SN plane), plane from menton point to goangle made by S point and N point and A point (Sand B point (SNB angle), angle made by A poinbetween SN plane and palatal plane (PP-SN

mandibular plane (SN-Mand. plane angle), angl(PP-Mand. plane angle), angle between U1 anbetween U1 and palatal plane (U1-PP plane ang

TPD, until a central diastema of a fewmillimetres was reached. The TPD screwwas then turned until a central diastema of1 mm was reached and the lock screw wasplaced. In patients requiring only minimalexpansion in the anterior region and wideexpansion in the posterior region, an ante-rior blockage was applied from the left tothe right upper incisor. Between the fifthand seventh postoperative days, patientswere evaluated for removal of the lockscrew and to begin activation of the TPDat 1208 (0.33 mm) a day. During the acti-vation period, patients were seen eachweek until the desired expansion wasachieved. No overcorrection was done.12 weeks after surgery, the patient’s ortho-dontist started orthodontic treatment. Thedistractor was kept in place for a max-imum of 9 months to minimize the risk ofrelapse. After completion of orthodontictreatment, standard imaging (panoramicradiograph, PA, lateral cephalogramsand occlusal view) were taken. Postopera-tively, the SNA, SNB, ANB, PP-SNplane, PP-Mand. angle, SN-Mand. angle,

ements of SNA (angle 1), SNB (angle 2), ANB-SN plane angle (angle between palatal plane

between palatal plane and mandibular plane),n SN plane and mandibular plane). Greatestoint), greatest depression point in the anteriorjunction of the nose and the frontal bone (N),the central incisors (U1), plane from anterior

or PP plane), plane passed from S point and Nnial angle of the mandible (mandibular plane),NA angle), angle made by S point and N pointt and N point and B point (ANB angle), angleplane angle), angle between SN plane and

e between palatal plane and mandibular planed the SN plane (U1-SN plane angle), anglele).

U1-palatal plane, and U1-SN plane anglechanges were evaluated.

Statistical methods

To evaluate patterns within the data, EDAwas performed. Descriptive statisticsincluding means and standard deviations(SD) for each measurement of each anglewere calculated.

Student’s paired t-test was used to com-pare preoperative and postoperative datafor each patient. The paired t-test providesa hypothetical evaluation of the differencebetween population means for a pair ofrandom samples whose differences areapproximately normally distributed.

Regression analysis was performed toinvestigate the ability to predict post-operative PP-SN angle based on patientcharacteristics.

The Institute for Biostatistics at HasseltUniversity performed all statistical ana-lyses.

Results

The patient group consisted of 50 patients,35 (70%) had class II occlusion and 15(30%) had class III occlusion. The averageage of the participants was 26 years (range15–49 years); none were younger than 15years. Follow-up measurements were per-formed after completion of orthodonticalignment of the upper and lower jawbefore orthognathic surgery (Le Fort I,bilateral sagittal split osteotomy (BSSO),bimaxillary surgery) (20 � 9 months).

EDA

Table 1 shows that angles did not changein a minority of patients. Most patients haddecreased UI-SN and UI-PP angles andincreased SNA, PP-SN, and ANB anglesafter surgery. For PP-Mand., SN-Mand.,and SNB, the number of patients withincreasing versus decreasing angles weresimilar. This is confirmed by paired t-testanalysis (Table 2).

For U1-SN and U1-PP angles, themajority of patients had a decreased mea-surement following surgery. For the PP-SN, SNA, and ANB angles more patientshad increased rather than decreasedvalues. Student’s paired t-test was usedto determine the statistical significance ofthese changes.

Student’s paired t-test

Changes in U1-SN and U1-PP angles(retroclination of upper incisors towardsSN or PP, respectively) and PP-SN, SNA,

664 Parhiz et al.

Fig. 2. The treatment sequence in all patients in this study was SARPE TPD as a first step, followed by orthodontic alignment and subsequentmaxillary and/or mandibular orthognatic surgery.

and ANB angles (clockwise rotation ofpalatal plane and increase of SNA andANB) were statistically significant(Fig. 3). Changes in PP-Mand., SNB, andSN-Mand. were not statistically different.

Table 1. The number of patients with or without

and after surgery.

Angle (8)Direction of change

Increase (+) Decre

UI-SN 13

UI-PP 13

PP-SN 29

PP-Mand. 23

SNA 35

SNB 22

ANB 30

SN-Mand. 29

Angle between U1 and the SN plane (U1-SN pAngle between U1 and palatal plane (U1-PP plAngle between SN plane and palatal plane (PP-Angle between palatal plane and mandibular plAngle made by S point and N point and A poinAngle made by S point and N point and B poinAngle made by A point and N point and B poinAngle between SN plane and mandibular plane

PP-SN plane angle

As shown in Fig. 3, the PP-SN plane angleincreased after surgery. On regression ana-lysis, only a few response variables were

changes in lateral cephalometric angles before

ase (�) No change (difference = 0)

35 236 111 1022 59 621 77 1316 5

lane angle).ane angle).SN plane angle).ane (PP-Mand. plane angle).t (SNA angle).t (SNB angle).t (ANB angle).

(SN-Mand. plane angle).

available for analysis (PP-SN post jawsurgery with the covariates PP-SN presurgery, gender, age, and occlusion).Table 3 shows that after TPD, malepatients had a higher tendency towardsa clockwise rotation of PP than femalepatients. This is indicated in the boxplotdiagram in Fig. 4. Table 4 showsdescriptive statistics for PP-SN by occlu-sion. Class II patients tend to have smal-ler PP-SN values than Class III patientsboth pre- and post-SARPE (Fig. 5).

To determine if age affects PP-SN angleafter surgery, the authors created a scatterplot (Fig. 6). As Fig. 6 shows, there is norelationship between age and PP-SN planeangle.

The correlation between PP-SN anglebefore (PP-SN pre) and after (PP-SNpost) SARPE was established and isshown with the scatter plot presentedin Fig. 7. Patients with a lower PP-SNbefore surgery tend to have a lower PP-SN postoperatively. A higher preopera-tive PP-SN was associated with a higherpostoperative PP-SN (post). The correla-

Lateral cephalometry changes after SARPE 665

Table 2. Student’s paired t-test results.

Angle (8)Pre surgery Post surgery Change 95% CI Change

Prob.Mean SD Mean SD Mean SD Lower Upper

U1-SN 102.6 9.39 97.78 8.32 �4.82 8.94 �7.36 �2.28 0.000*

U1-PP 108.22 9.33 104.36 8.33 �3.86 8.56 �6.29 �1.43 0.002PP-SN 5.62 3.66 6.56 3.89 0.94 2.13 0.33 1.55 0.003*

PP-Mand. 34.88 7.78 34.66 8.47 �0.22 3.38 �1.18 0.74 0.648SNA 80.3 4.08 81.9 3.74 1.60 2.57 0.87 2.33 0.000*

SNB 76.46 5.54 76.92 5.80 0.46 2.61 �0.28 1.20 0.219ANB 3.94 4.38 5 4.30 1.06 2.00 0.49 1.63 0.000*

SN-Mand. 40.5 7.67 41.16 8.19 0.66 3.03 �0.20 1.52 0.131* Changes statistically significant with a = 5%.The null hypothesis is that there is no change after SRPE in the sagittal planes or angles (two

sided Student’s paired t-test).For abbreviations see Table 1.

tion between PP-SN before and aftersurgery is 0.84.

Regression analysis

Both the available covariates and theirpossible interactions were included to findthe best statistical model. Confirmation ofthe assumption of regression analysis isalso needed. The following model was

Table 3. Descriptive statistics of PP-SN angle b

Gender N Minim

Female PP-SN(pre) 30 �1PP-SN(post) 30 0

Male PP-SN(pre) 20 1PP-SN(post) 20 1

Angle between SN plane and palatal plane (PP-

Fig. 3. Superimposition of lateral cephalometry

plane angle is increased. This increase is statist

reached:

y ¼ �1:331 þ 0:897 PPSNpre

þ 1:483 GENDER

þ 0:063 AGE

þ 0:768 OCCLUSION

The significance of each covariate canbe seen in Table 5. The presurgical PP-SN

y gender.

um Maximum Mean SD

15 5.20 3.458 16 5.77 3.839

15 6.25 3.945 16 7.75 3.740

SN plane angle).

before and after surgery shows that the PP-SNically significant (P = 0.003*).

angle has a significant effect on postopera-tive PP-SN angle. A unit increase in PP-SN before surgery leads to an increase inthe post surgery PP-SN angle of 0.897when other variables are held constant.Gender also affects PP-SN angle. Malepatients tend to have an increased anglepost surgery compared with femalepatients. The covariates, age and occlu-sion, had no significant effect on post-operative PP-SN. In the regressionanalysis, no assumption is violated.

Coefficient determination for thismodel is 0.753, meaning that 75.3% ofthe total variance in Y (PP-SN plane angleafter surgery) can be explained by PP-SN(preoperative value), gender, age, andocclusion. The remaining 24.7% of thetotal variation value in angle PP-SN postsurgery remains unexplained.

U1-PP and U1-SN plane angles

All patients in this study had orthodonticalignment (pre-Le Fort I, pre-BSSO, pre-bimaxillary surgery) before second stan-dard radiographs were taken. The U1-PPand U1-SN plane angles decreased afterSARPE. Tables 6 and 7 show the mini-mum, maximum, mean, and standarddeviation value of U1-SN and U1-PPangles by gender.

The U1-PP angle and U1-SN angle isdecreased after SARPE TPD in both maleand female patients. In females thechanges before and after surgery in bothU1-SN plane angle and U1-PP plane angleis statistically greater than in males (Stu-dent’s paired t-test).

The patients were grouped based on U1-SN angle before SARPE. Patients withnormal U1-SN angle (within the range104–1068) are included in the first group(9 patients). Patients who have U1-SN lessthan 1038 and greater than 1068 areincluded in group 2 (lower than normal:25 patients) and 3 (greater than normal: 16patients), respectively.

666 Parhiz et al.

Fig. 4. Boxplot for PP-SN angle pre-SARPE and post-SRPE by gender.

Table 4. Descriptive statistic of PP-SN angle by occlusion.

Occlusion N Minimum Maximum Mean SD

Class III PP-SN(pre) 15 1 15 6.67 4.100PP-SN(post) 15 1 16 7.13 3.662

Class II PP-SN(pre) 35 �1 13 5.17 3.417PP-SN(post) 35 0 16 6.31 4.006

Angle between SN plane and palatal plane (PP-SN plane angle).

The boxplots of changes of U1-SNangle before and after SARPE for the threeU1-SN groups are presented in Fig. 8. Forpatients with a normal presurgical angle, anormal value after SARPE and subsequentorthodontic alignment is expected. Theresults show that this is not the case. Mostpatients show a decrease in U1-SN follow-ing surgery. Patients with a lower than

Fig. 5. Boxplot for PP-SN angle pre-surgery an

normal UI-SN prior to surgery, on aver-age, tend to have a stable angle (no furtherdecrease). Only a few patients in thisgroup showed an increasing U1-SN. Inpatients with a presurgical U1-SN aboveaverage, there was a trend towards adecrease of this angle after SARPE.

Similarly, the patients were groupedbased on the preoperative U1-PP angle.

d post-surgery by occlusion.

Patients with a normal U1-PP angle(within the range 110–1168) are includedin the first group (11 patients). Patientswith a U1-PP less than 1108 and greaterthan 1178 were assigned to groups 2(lower than normal: 27 patients) and 3(greater than normal: 12 patients), respec-tively. The box plot of angle changes forU1-PP groups is presented in Fig. 9.

Changes similar to that seen with U1-SN also occur for the U1-PP angle. Aftersurgery, the patients with normal U1-PPangles tend to have a decreased angle,whereas on average, patients with lowerpreoperative angles tended to have a stableU1-PP angle. The variability in this groupis quite high, with some having normalpostoperative U1-PP values and somewith abnormal values. Patients whose pre-operative U1-PP angle was higher thannormal had a decreased angle afterSARPE.

One of the limitations of this study isthat only a few covariables were availablefor regression analysis (age, gender,occlusion, pre-SARPE values). Otherimportant variables that could affect out-come were not available owing to theretrospective nature of this study: the typeof orthodontic appliances, the exactamount of transverse expansion, the sagit-tal position of the TPD device, and thevertical position of the brackets on theincisors. A systemic review of the effectsof bone-borne surgical assisted rapid max-illary expansion27 indicates no additionalcovariant factor in this respect.

Discussion

The preliminary surgical correction oftransverse maxillary discrepancies inpatients with planned subsequent orthog-nathic treatment is different from that inwhich the SARPE procedure is the soleintervention. In the first scenario, the incli-nation of the upper front teeth is intendedto be corrected on the maxillary base bythe orthodontic presurgical alignment,independent of the relation with the lowerjaw. The authors have previously providedthe rationale for this approach, based ontiming, amount of maxillary expansion,and stability issues. Whenever subsequentsurgery is planned, the inclination of U1-PP is aimed at approximately 1128 (range110–1148), except in treatment planswhere a posterior intrusion of the upperjaw calls for a presurgical inclination ofU1-PP greater than 1128. The transversalgain by the preliminary SARPE should notbe compromised by undesired sagittal orvertical changes.

Lateral cephalometry changes after SARPE 667

Fig. 6. Scatter plot of age and PP-SN post surgery.

Fig. 7. Scatter plot of PP-SN before and after surgery.

Table 5. Coefficient of regression and their significance for model angle PP-SN post surgery.

ModelCoefficients

t Sig.B SE

(Constant) �1.331 1.296 �1.027 .310PPSN(pre) .897 .081 11.133 .000*

Gender 1.483 .619 2.396 .021*

Age .063 .036 1.740 .089Occlusion .768 .656 1.170 .248

Angle between SN plane and palatal plane (PP-SN plane angle).* The covariate is statistically significant with a = 5%.

Table 6. Descriptive statistic of U1-SN angle by gender.

Gender N Minimum Maximum Mean SD

Male U1-SN(pre) 20 84 124 102.35 9.965U1-SN(post) 20 86 119 101.60 6.707

Female U1-SN(pre) 30 80 121 102.77 9.153U1-SN(post) 30 76 110 95.23 8.406

Angle between U1 and the SN plane (U1-SN plane angle).

Little is known about the sagittalchanges after surgical expansion of theupper jaw with bone-borne appliances.In Table 8, two studies concerning SARPEwith bone-borne appliances are summar-ized. These trials report results similar tothe present study: an increase in SNA andANB (significant in the study by GUNBAY

et al.10, nonsignificant in the study byLAGRAVERE et al.12) and a retroclinationof the upper incisors (significant in thepresent study but nonsignificant in theLAGRAVERE et al. study12).

Also in Table 8, four studies concerningSARPE with tooth-borne appliances arepresented. GILON et al.9 reported a max-illary expansion of 5 mm (range 1.5–8.5 mm) and a nasal expansion of4.4 mm (2.2–6.6 mm). Vertically, theyalso found a significant anterior rotationof the palatal plane of 1.58 (�0.6 to�3.6 mm) and sagittally a decrease ofthe SNB angle of 1.788 (�0.2 to�3.8 mm). This is similar to the presentfindings.

LAGRAVERE et al.13 performed a sys-tematic review and concluded that usinga tooth-borne device for SARPE results ina greater expansion at the molars, whichdiminished progressively to the anteriorpart of the dental arch in all the evaluationperiods. Vertical and sagittal skeletalchanges were minimal or not clinicallysignificant. In cases of SARME usingthe HAAS appliance, CHUNG et al.5

reported anterior movement as well asvertical movement of the maxillaryhalves, without significance. CHUNG

et al.5 also found that the maxillary inci-sors slightly but significantly retroclinedafter surgically assisted RPE.

NEUBERT et al.17 reported maxillarychanges immediately after surgery, butno vertical or sagittal maxillary displace-ment was found. In the NEUBERT study theskeletal expansion was small at 1.7 mm.

More literature is found concerningsagittal changes after non-surgical expan-sion of the upper jaw. In 1961, HAAS

11

described the downward and forwardmovement of the maxilla that occurs dur-ing rapid maxillary expansion (tooth-borne device) because of the location ofthe craniomaxillofacial sutures. This phe-nomenon has a favourable effect on ske-letal class III patients with maxillarydeficiency.

Similar results were reported by DAVIS

and KRONMAN7 and WERTZ

28. However, DA

SILVA FILHO et al.6 found no significantalterations of the maxilla in the anteropos-terior position for young patients whounderwent orthopaedic RPE, althoughthe mandible had some downward and

668 Parhiz et al.

Table 7. Descriptive statistic of U1-PP angle by gender.

Gender N Minimum Maximum Mean SD

Male U1-PP(pre) 20 90 126 108.60 9.864U1-PP(post) 20 95 120 109.25 6.155

Female U1-PP(pre) 30 85 125 107.97 9.122U1-PP(post) 30 87 116 101.10 8.062

Angle between U1 and palatal plane (U1-PP plane angle).

Fig. 8. Box plot of the change of U1-SN angle before and after SARPE.

backward rotation. They also found thatthe maxilla was dislocated downward,displaying a downward and backwardrotation in the palatal plane, which canresult in increasing facial height6. Theseresults are similar to the present study.

In their investigation of the effects oforthopaedic RPE on maxillary incisors,WERTZ

28, SANDIKCIOGLU and HAZAR24,

and AKKAYA et al.1 reported incisor retro-clination and an increase of the interincisalangle after maxillary expansion. DAVIS

Fig. 9. Box plot of the change in U1-PP angle

and KRONMAN7 indicated that the ‘A’ point

moves forward as a result of splitting thepalatal suture. They also show that the SN-PP (palatal plane) angle increases inapproximately half of the cases with aresultant lowering of the ‘A’ point; themandibular plane angle tends to increase,thus opening the bite in half of the casesand closing the bite in three cases. Theseresults are similar to the present study.

WERTZ28 showed that the maxilla was

routinely displaced downward 1–2 mm,

before and after surgery.

but rarely moves forward significantly.The vertical displacement of the maxillavaried from ANS to PNS, so that the SN-palatal plane angle sometimes opened andsometimes closed. Sometimes the palatedescended in a parallel manner, but open-ing of the SN-PP angle predominated. TheANB angle tended to be increased, butfrequently it was decreased.

In a RPE study, CHUNG and FONT4 show

that SNA and ANB increased and SNBdecreased, although these decreases werenot statistically significant. Both ANS andPNS moved significantly downward. TheMP-SN angle increased and suggested adownward and backward rotation of themandible. The PP-SN did not change sig-nificantly, but the PP-MP increased sig-nificantly. Previous studies by DAVIS andKRONMAN

7, WERTZ28, and DA SILVA FILHO

et al.6 also showed an increase in themandibular plane angle.

Using a bonded RPE appliance (withocclusal coverage), AKKAYA et al.1

reported that the maxilla moved forwardand the mandible moved backward.Therefore, the ANB and mandibular planeangle increased significantly after expan-sion. Similar results were reported byBASCIFTCI and KARAMAN

3 but SARVER andJOHNSTON

25 reported that the maxillamoved forward less in the bonded RPEsample than in the banded RPE sample.They found the maxilla even moved back-ward in some bonded RPE patients.

MONINI et al.16 performed a prospectivestudy on children younger than 12 yearsshowing that after RME, an improvementof nasal flow and resistance was recordedin patients in the supine position. Theyalso concluded that PP-Mand. plane angleand SN-Mand. plane angle will decrease(non significantly) and this would berelated to the change from oral to nasalbreathing, with a consequent mandibleautorotation and reduction of facial height.

As the increase in PP-SN, SNA, andANB was statistically significant in thecurrent study, the data confirm that max-illary expansion is followed by downwardrotation of the maxilla. This is indepen-dent of the surgical or non-surgicalapproach but possibly dependent on theamount of transversal expansion.

In the present study, the authors foundthat the decrease of the U1-SN and U1-PPangles were statistically significant. Thedecrease in U1-SN plane angle is in partdue to clockwise rotation of palatal plane,but the U1-PP plane angle is alsodecreased. Since the study concernedpatients with presurgical alignment, theauthors expected that no retroclinationof the upper incisors would occur, or

Lateral cephalometry changes after SARPE 669

Table 8. Present data and previous study results.

Study Kind of appliance Result Comparison with the present study

HAAS11 RME (tooth-borne device) Downward and forward movement

of the maxillaSimilar

DAVIS and KRONMAN7 RME (tooth-borne device) Downward and forward movement

of the maxillaSimilar

Mandibular backward movement In the present study the SNBincreased but is not significant

WERTZ28 RME (tooth-borne device) Downward and forward movement

of the maxilla, incisor retroclinationSimilar

DA SILVA FILHO et al.6 RME (tooth-borne device) No significant alterations of themaxilla in the anteroposterior position

In the present study we did notmeasure linear changes

Downward and backward rotation inthe palatal plane, which can result inincreasing facial height

Similar

Mandibular downward and backwardrotation

In the present study the SNBincreased but is not significant

CHUNG et al.5 HAAS appliance Anterior and vertical movement ofthe maxillary halves, which werenot significance

Downward movement of maxillain this study is significant

Incisor retroclination Similar

SANDIKCIOGLU and HAZAR24 RME (tooth-borne device) Incisor retroclination Similar

AKKAYA et al.1 RME (tooth-borne device) Incisor retroclination Similar

LAGRAVERE et al.13 SRPE (tooth-borne device) Vertical and sagittal skeletal changeswere nil or not clinically significant

Not similar

Downward movement of maxilla inthis study is significant

LAGRAVERE et al.12 Tooth borne and boneborne appliances

No significant anterior skeletal ordental movement

In the present study we did notmeasure linear changesRetroclination of the upper incisorswere significant in the present study

NEUBERT et al.17 Biedermann-Hyrax-screw No vertical or sagittal maxillarydisplacement

Not similar

Downward movement of maxilla inthis study is significant

GILON et al.9 SRPE (tooth-borne device) Significant anterior rotation of thepalatal plane

Similar

Decrease of the SNB angle In the present study the SNB increasedbut is not significant

DAVIS and KRONMAN7 RME (tooth-borne device) Increasing SN-PP (palatal plane)

angleSimilar

CHUNG and FONT4 RME (tooth-borne device) Both ANS and PNS moved

significantly downwardNot similar

Downward and backward rotationof the mandible

Not similar

BASCIFTCI and KARAMAN3 RME (tooth-borne device) Downward and forward movement

of the maxillaSimilar

Mandibular backward movement In the present study the SNBincreased but is not significant

SARVER and JOHNSTON25 RME (tooth-borne device) Forward movement of the maxilla In the present study we did not

measure linear changesMONINI et al.16 RME (tooth-borne device) Mandibular counter-clockwise

rotation and reduction of facialheight

–

GUNBAY et al.10 TPD (bone-borne) Increasing of Sn_ Go-Gn angleand SNA and ANB

Similar

Decreasing SNB In the present study we did notmeasure linear changes

670 Parhiz et al.

would have been counteracted by theorthodontic treatment with fixed appli-ances. A decrease of U1-SN can be usefulin class III patients, but most patients inthis study had class II occlusion and thesechanges are not desirable since itdiminishes overjet. In 7 patients (14%),the authors had to modify the primarytreatment plan because of undesirablechanges in overjet (negative overjet)necessitating an additional Le Fort Iadvancement in the treatment plan. It isunclear why these changes in inclinationof upper incisors occur, despite of ortho-dontic efforts. The retrospective nature ofthe present study allowed only a limitednumber of variables to be examined. Ofclinical interest is the significant correla-tion between the pre-treatment inclinationof the upper incisors and the amount ofsubsequent change. Steeply inclined inci-sors will not change much in inclination,whereas upper incisors in proclination willchange much more.

After SARPE with bone-borne appli-ances and subsequent orthodontic align-ment in patients scheduled for Le Fort I,BSSO, or bimaxillary osteotomies, thisstudy supports the finding that theexpanded maxilla has a clockwise rotationwith an SNA angle increase(1.608 � 2.57) (P < 0.05) and PP-SNplane angle increase (mean0.948 � 2.13) (P < 0.05). The results alsoshowed than the initial inclination of theupper incisors will decrease (the higher theinclination, the more the decrease) as fol-lows: U1-SN plane angle (�4.828 � 8.94)(P < 0.05) and U1-PP plane angle(�3.868 � 8.56) (P < 0.05). The fact thatthe maxilla rotates clockwise explainswhy the decrease of the angle of the upperincisor to SN is greater than the decreaseof the angle of the upper incisor to palatalplane.

Funding

None.

Conflict of interest

None declared.

Ethical approval

Not required.

Acknowledgement. The authors would liketo thank Martijn Peters and HanneloreBove for their valuable contribution tothis study.

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Address:Constantinus PolitisDepartment Oral Maxillofacial Surgery

St. John’s HospitalSchiepse Bos 63600 GenkBelgiumTel: +3289326162;Fax: +3289327917E-mail: c.politis@village.uunet.be