7/28/2019 Cambios en flujo sanguneo Le Fort I
1/6
Changes in bone blood flow in segmental LeFort I osteotomies
Winfried Bernhard Kretschmer, MD, DDS,a Grigore Baciut, MD, DDS, PhD,b
Mihaela Baciut, MD, DDS, PhD,c Werner Zoder, MD, DDS,d and
Konrad Wangerin, MD, DDS, PhD,e Stuttgart, Germany, and Cluj-Napoca, RomaniaMARIENHOSPITAL AND UNIVERSITY OF MEDICINE AND PHARMACY IULIU HATIEGANU
Objective. The aim of the present study was to investigate the effect of segmentation and different movements of thesegments in LeFort I osteotomies on the bone blood flow (BBF).Material and methods. The study sample of the prospective cohort study was composed of subjects scheduled toundergo 3-piece LeFort I osteotomies and simultaneous BSSO for correction of developmental skeletal deformities. Theprimary predictor variables were: time (T1, before LeFort I osteotomy; T2, after LeFort I osteotomy; T3, aftersegmentation and fixation of the maxilla) and magnitude of maxillary movement in the sagittal, vertical, and transverseplanes measured in millimeters (mm). The subjects were assigned to 2 risk groups (high/low) depending on the amountof the movement. The primary outcome variable was maxillary bone blood flow measured with a laser Doppler at 4sites: premaxilla, right and left maxillary lateral segments, and the mandible.Results. No significant difference was observed among the 3 maxillary regions. The mean decrease of the maxillaryBBF between T1 and T2 as well as the reduction of BBF between T2 and T3 were statistically significant for all regions
(P .028 to P .005 for T1/T2; P .003 to P .028 for T2/T3). No significant difference could be found betweenthe 2 risk groups of maxillary movements.Conclusions. Multisegmental maxillary osteotomies lead to a significant reduction of BBF. Moderate maxillarymovements have no significant influence on the blood supply. (Oral Surg Oral Med Oral Pathol Oral Radiol Endod2009;108:178-183)
Multisegmental Le Fort I osteotomy is a standard pro-
cedure in orthognathic surgery. The reestablishment of
a blood supply to the dento-osseous segments was
shown by Bell et al.1,2 in animal studies on macaque
monkeys. Yet, a significant reduction in perfusion ofthe dento-osseous segments has been observed during
the first hours after surgery.1-7 Thus, adverse sequelae
can occur, such as pulp changes, nonunion of the bone,
and partial or complete loss of segments. Thirty-six
cases of aseptic necroses were described by Lanigan
and West.8 Expansion of the segmented maxilla and
superior repositioning seem to exhibit the highest risk
for this kind of complication.8,9 Emshoff et al.10,11 have
shown that segmentation leads to a reduction of pulpal
blood flow (PBF) after LeFort I osteotomy. Expansion
or specific movements of the maxilla were not quanti-fied. So far, no study has been performed on the effect
of expansion, advancement, or vertical repositioning on
the bone blood flow in the dento-osseous segments.
Laser Doppler flowmetry has been described to be a
reliable method for continuous measurement of pulpal
or gingival blood flow in orthognathic surgery. Intra-
operative recording of gingival blood flow (GBF) dur-
ing Le Fort I osteotomies was done by Dodson et
al.12-14 Studies on bone blood flow (BBF) with laser
Doppler flowmetry in orthognathic surgery are not
known. The current study was designed to evaluate the
effect of segmentation, intraoperative expansion, ad-vancement, and vertical repositioning on BBF of pre-
maxilla and lateral segments during multisegmental Le
Fort I osteotomies.
MATERIAL AND METHODS
Study design and sampleA prospective cohort study was designed to investi-
gate the effect of segmentation and magnitude of max-
illary movement in the sagittal, vertical and transverse
planes on BBF of the maxilla. The study sample was
composed of subjects scheduled to undergo 3-piece
aSenior Registrar, Department of Oral and Maxillofacial Surgery,
Marienhospital, Stuttgart, Germany; PhD Student, University of
Medicine and Pharmacy Iuliu Hatieganu, Cluj-Napoca, Romania.bProfessor and Chair, Clinic of Cranio-Maxillofacial Surgery, Uni-
versity of Medicine and Pharmacy Iuliu Hatieganu, Cluj-Napoca,Romania.cAssociate Professor, Clinic of Cranio-Maxillofacial Surgery, Uni-
versity of Medicine and Pharmacy Iuliu Hatieganu, Cluj-Napoca,
Romania.dSenior Registrar, Department of Oral and Maxillofacial Surgery,
Marienhospital, Stuttgart, Germany.eProfessor and Head of the Department, Department of Oral and
Maxillofacial Surgery, Marienhospital, Stuttgart, Germany.
Received for publication Feb 23, 2009; returned for revision Apr 4,
2009; accepted for publication Apr 16, 2009.
1079-2104/$ - see front matter
2009 Published by Mosby, Inc.
doi:10.1016/j.tripleo.2009.04.029
178
7/28/2019 Cambios en flujo sanguneo Le Fort I
2/6
LeFort I osteotomies and simultaneous bilateral sagittal
split osteotomy (BSSO) for correction of developmen-
tal skeletal deformities. Inclusion criteria were the fol-
lowing: fixed orthodontic appliances, availability of a
sterilized probe (the laser probes had to be sent outside
the hospital for gamma sterilization), a sufficient bone
thickness of the measurement areas, and a clinicalpostoperative follow-up of at least 6 weeks. Patients
with previous surgery in the maxilla (e.g., cleft palate,
rapid maxillary expansion) or general diseases (non
class I according to the American Society of Anesthe-
siology) were excluded. The protocol was reviewed and
approved by the institutional review board. Each sub-
ject has given a written informed consent.
Study variablesThe predictor variables were time, direction, and
magnitude of maxillary movement and location of
blood flow measurement. BBF (outcome variable) was
measured after incision of the upper and lower vesti-
bule and soft tissue dissection (T1), after Le Fort I
osteotomy and mobilization of the maxilla (T2) and
after segmentation and fixation of the maxilla (T3).
Direction and magnitude of maxillary movement were
planned with the Onyxceph software 2.7.15 (Image
Instruments GmbH, Jena, Germany). The following
landmarks were used for the study: upper incision (hor-
izontal movement) and mesial cusp of the first molar
(vertical movement). The movements are given in re-
lation to the Frankfurt horizontal plane. Widening of
the maxillary dental arch was measured for the first
molar on the dental casts before and after model sur-
gery. The subjects were assigned to 2 risk groups.
Advancement, superior repositioning, and widening of
2 mm and more were considered a risk. The high-risk
group included subjects with 2 or 3 movements at risk,
whereas the low-risk group included subjects with only
1 or no movement at risk. The locations of BBF mea-
surement were premaxilla, right and left lateral segment
of the maxilla, and mandible (control measurement).
Other collected variables included age and gender.
Anesthesia and surgical techniqueAll patients received hypotensive anesthesia. Stan-
dardized Le Fort I and sagittal split osteotomies with
rigid fixation were performed according to Bell and
Proffit15 and Hunsuck.16 Tissue perfusion was opti-
mized by administration of 500 mL of hydroxyethyl
starch 6%/200/0.5 before segmentation of the maxilla;
this bolus infusion was repeated after 8 and 20 hours.
Segmentation of the maxilla was done between the
lateral incisor and the canine on both sides with appro-
priate burrs. The maxilla was operated on first in all
cases. The maxillary segments were stabilized with
2.0-mm miniplates and an interocclusal splint.
Blood flow measurementA laser Doppler flowmeter (Periflux PF 5001, Per-
imed, Jrflla, Sweden) was used to assess the BBF in
the maxilla and the mandible. Light with a wavelength
of 632.8 nm is produced by a 1-mW He-Ne laser.
Custom-made probe holders (Perimed) were fixed in
the premaxilla, both canine regions and the mandible
(anterior to the planned sagittal split) through 1.9-mm
burr holes in the cortical bone (Fig. 1). The measure-
ment in the mandible served as a control. A custom-made probe (PF 415-310, Perimed) (Fig. 2) was used to
conduct the light to the measurement site in the can-
cellous bone and to return the backscattered light to the
flowmeter. The probe had a diameter of 1 mm. The
optical fiber had a diameter of 125 m; the fiber-to-
fiber distance was 500 m. According to the Doppler
effect, the amount of backscattered light is recorded by
the flowmeter. The voltage of the produced output
signal has a linear relation to the flow of the red blood
cells (number of cells average velocity). The perfu-
sion units (PU) shown by the laser Doppler are a
relative measurement of the blood flow in the respec-tive tissue. The data were collected on a wide band
setting. A computer was connected to the RS-232 port
of the laser Doppler for storage of the date and later
analysis with the specific software (PeriSoft for Win-
dows, Perimed). Reproducibility of the measurements
was ensured with the fixed probeholder. Calibration of
the probes was done before each sterilization process
with a plastic block for zero voltage and a motility
standard for 250 PU (Perimed). For each site the data
were registered continuously until at least 2 minutes of
stable values were seen on the screen.
Fig. 1. Probe holder fixed into the maxillary bone (premaxilla
and lateral segments) intraoperatively.
OOOOE
Volume 108, Number 2 Kretschmer et al. 179
7/28/2019 Cambios en flujo sanguneo Le Fort I
3/6
Data analysisFor the analysis of the recordings, the PeriSoft for
Windows software was used. The mean perfusion was
calculated for each session during the phase of stablevalues. Peaks attributable to movement artefacts were
excluded. Further data analysis was done with the Sta-
tistica 8.0 software (StatSoft Inc., Tulsa, OK). Perfu-
sion changes of the mandible, the premaxilla, and the
lateral segments between the respective sessions were
investigated with the Wilcoxon matched pairs test. The
Friedman analysis of variance (ANOVA) was used to
detect differences among the 3 maxillary regions within
every session. To compare the results with those of other
studies, the percentage of BBF reduction was calculated
for the 3 maxillary regions. Differences between the 2 risk
groups at T2 and T3 were analyzed with the Kruskal-Wallis ANOVA by ranks. A probability ofP less than .05
was considered significant.
RESULTSTwelve patients undergoing bimaxillary osteotomies
with 3-piece maxilla from April 2008 to February 2009
were included in the study. Two patients were excluded
from the study, because maxillary blood flow measure-
ment was not possible in the lateral segments because
of extremely thin bone. Mean, standard deviation, and
range of the study variables are given in Table I. Seven
patients were included in the high-risk group, whereas
5 patients were assigned to the low-risk group (Table
II). No anesthetic or surgical complications were ob-
served during surgery. The descending palatine artery
was preserved in all cases. Means, standard deviations,
and ranges of all measurement sites and time points are
shown in Table III. The mandibular perfusion showed
no significant differences between the recording ses-
sions T1/T2 (P .071) and T2/T3 (P .875). No
significant differences could be found between premax-
illa, right and left lateral segment at T1 (P .338), T2
(P .920), and T3 (P .368). A significant reductionof BBF was observed between T1 to T2 in the right
lateral segment (P .028), the premaxilla (P .028),
and the left lateral segment (P .005). Between T2 and
T3 a further significant decrease of perfusion was seen
in the right lateral segment (P .028), the premaxilla
(P .003), and the left lateral segment (P .008)
(Table III). The mean percentage of BBF reduction at
the end of the maxillary procedure (T1/T3) was 63.3%
(SD 18.54) in the premaxilla, 45.5% (SD 44.27) in the
right lateral segment, and 60.7% (SD 18.63) in the left
lateral segment. No significant differences could be
Table I. Study variables (n 12; 7 male, 5 female)
Variable Mean SD Range
Age 22.5 4.25 16 to 31
Maxillary advancement, mm 1.6 1.16 0 to 3
Vertical movement first molar, mm 2.4 3.02 7 to 2
Expansion first molars, mm 1.5 1.90 1 to 4.5
Table II. Risk groups for decrease of bone blood flowin segmental LeFort I osteotomies: high (n 7) and
low (n 5)
Patient Advancement Vertical movement Expansion Risk group
1 2 2.5 4 High
2 3 7 0 High
3 1 1 3 Low
4 1 2 1 Low
5 1 1 0 Low
6 3 4 3 High7 0 4 2 High
8 1 6 0 Low
9 3 1 3 High
10 0 2 0 Low
11 3 3 0 High
12 1 5 4.5 High
Advancement, superior repositioning, and expansion of 2 mm or
more were considered a risk.
Subjects with 2 or 3 movements at risk were assigned to the high-risk
group.
Fig. 2. Laser Doppler probe (PF 415-310, Perimed, Jrflla,
Sweden) for measurement of bone blood flow (BBF).
OOOOE
180 Kretschmer et al. August 2009
7/28/2019 Cambios en flujo sanguneo Le Fort I
4/6
found between the 2 risk groups at T2 and T3 (Table
IV). Postoperatively, no avascular sequelae were seen.
DISCUSSION
Avascular necrosis is a possible sequelae of a com-promised blood supply to the dento-osseous segments
in multisegmental Le Fort I osteotomies.8,9 Lanigan
and West8 reported 36 cases with aseptic necrosis fol-
lowing maxillary osteotomies. Of these 36 cases, 34
were multisegmental osteotomies. Basic research on
the BBF after different osteotomies of the maxilla was
done by Bell et al.,1,2 Nelson et al.,3 and Meyer and
Cavanaugh4 on macaque monkeys. As it is not possible
to use radioactive microspheres for clinical research in
humans, laser Doppler flowmetry has shown to be the
method of choice for blood flow measurements in or-
thognathic surgery.5,10-14,17-24
The work of Firestone etal.,17 Buckley et al.,18 and Hellem et al.25 confirmed its
reproducibility. Emshoff et al.10,11 have shown the de-
crease of pulpal blood flow 3 to 5 days after segmental
maxillary osteotomies. Although it is known that the
highest reduction of maxillary perfusion can be found
during the first hours after Le Fort I osteotomy,1-7 few
data have been published about the intraoperative dy-
namics of maxillary blood flow.12-14 Superior reposi-
tioning and transverse expansion seem to be a potential
risk for vascular impairment.8,9 So far, no research has
been reported on the correlation between different max-
illary movements and the drop of maxillary blood sup-
ply in multisegmental osteotomies.
To investigate the effects of orthognathic surgery on
maxillary blood supply, research has mainly been done
with laser Doppler assessment of pulpal (PBF) and
gingival blood flow (GBF).5,10-14,17,18,22-24 This has
some disadvantages: orthodontic treatment has shownto have an effect on PBF5,17 as well as the distance of
the subapical osteotomy to the apex.24,26 Injuries of the
teeth during surgery will certainly have an influence on
PBF. Furthermore, positioning of the probes with cus-
tom-made wafers, as done by most authors,10,11,19-23 is
difficult intraoperatively, especially in cases with seg-
mentation of the maxilla. Measurement of BBF with
laser Doppler flowmetry has been developed for the
control of free flaps.27-29 Animal studies have shown
the reliability of this method.25,27,30-32
The intraoperative decrease of maxillary perfusion
found in the present study was up to 95% in certainareas of the maxilla. This is comparable to the animal
study of Nelson et al.3 with radioactive microspheres.
They found a decrease of BBF up to 89% when the
descending palatine artery (DPA) was cut. The DPA
was not, however, severed in any case of the present
study. The role of the DPA is not clear. Dodson and
Bays12 did not find a significant difference between 2
groups with and without ligation of the DPA when
measuring gingival blood flow intraoperatively. In con-
trast to this, Ramsay et al.23 reported 2 mild avascular
complications in a sample of 14 patients. Both under-
went a 2-piece Le Fort I osteotomy with expansion andhad 1 descending palatine artery transected. They have
not found significantly lower perfusion values in these
cases measuring 1 to 6 days after surgery. This con-
firms the importance of intraoperative assessment as
proclaimed by Dodson et al.12-14 It is not clear when to
classify a decrease of perfusion as adverse outcome. In
a recent study, Emshoff et al.10 defined a reduction of
PBF of more than 40% as adverse; 64% of their sub-
jects with multisegmental maxillary osteotomy and
32% of those with single-piece Le Fort I osteotomy
showed an adverse outcome 3 to 5 days after surgery.
Table III. Regional bone blood flow measurements (n 12) in perfusion units (PU)
Region
T1 T2 T3
Mean (SD) Range Mean (SD) Range Mean (SD) Range
Mandible 59.7 (44.8) 12.9-151.6 40.5 (30.2) 9.1-99.6 44.4 (34.6) 7.9-115.6
Maxilla:
Right lateral segment 77.5 (63.4) 12.7-210.3 46.8 (40.0) 5.1-139.2* 34.7 (41.8) 1.4-145.9*
Left lateral segment 79.6 (30.6) 19.5-112.3 41.1 (20.5) 13.8-75.5* 30.5 (19.4) 4.1-67.0*Premaxilla 70.6 (31.9) 24.8-121.8 47.5 (35.1) 13.0-105.1* 22.8 (15.4) 3.5-52.8*
T1, before LeFort I osteotomy; T2, after LeFort I osteotomy; T3, after segmentation and fixation of the maxilla.
*Significant difference to the previous session (P .05) in the Wilcoxon matched pairs test.
Table IV. Comparison of the maxillary bone bloodflow between the high-risk group (n 7) and the
low-risk group (n 5) at T2 and T3 (P values)
Region T2 T3
Right lateral segment 0.685 0.935
Left lateral segment 0.570 0.935
Premaxilla 0.223 0.168
Kruskal-Wallis analysis of variance by ranks.
T2, after LeFort I osteotomy; T3, after segmentation and fixation of
the maxilla.
OOOOE
Volume 108, Number 2 Kretschmer et al. 181
7/28/2019 Cambios en flujo sanguneo Le Fort I
5/6
Information about clinically observed avascular se-
quelae was not given. We observed a mean intraoper-
ative BBF reduction in the maxillary regions between
45.5% and 63.3% after segmentation and fixation.
Avascular complications were not seen. Dodson and
Bays,12 Harada et al.,19,20 and Sato et al.21 reported
similar results. The drop of GBF after downfracturewas greater than 70% in both study groups (with and
without DPA ligation) of Dodson and Bays.12 For both
groups, a reduction of over 60% was found at the end
of the procedure. PBF decreased by more than 80% 1
day after surgery in the studies of Harada et al.19,20 and
Sato et al.21 None of these authors reported avascular
sequelae. Segmentation of the maxilla with superior
repositioning and expansion is reported to be one of the
main factors for avasular necrosis.8,9 Epker9 mentioned
a risk of avulsing portions of the palatal pedicle,
when expanding the maxilla more than 3 to 5 mm.
Lanigan and West8
reported maxillary widening up to15 mm in one study about 36 cases exhibiting aseptic
necrosis. In a study of Poswillo33 on Old World mon-
keys with open bite, 10-mm advancement of the pre-
maxilla led to irreversible pulp changes. Animal studies
with not more than 2 mm repositioning of the segments
have not shown permanent effects.1,2,6,24,25,34 No data
can be found concerning the correlation between ver-
tical maxillary movement and decrease of blood sup-
ply. Advancement, vertical repositioning, and expan-
sion of the maxilla did not have a significant influence
on BBF in the present study. The moderate maxillary
movements and the relatively small sample might bereasons for these findings. As the supposed limit of
expansion should not be exceeded in humans for ethical
reasons, further animal studies are needed. Intraopera-
tive measurement of BBF should be continued to in-
vestigate the effect of vertical repositioning, widening,
and advancement with larger samples. Thus, regression
analysis for single factors will be possible. Monitoring
of critical dento-osseous segments, e.g., in patients with
cleft palate and previous surgery, is a possible indica-
tion for routine clinical application of the technique.
We thank Dr. Sorana-Daniela Bolboaca, M.S., M.D., Ph.D.,
Department of Biometry, University of Cluj-Napoca, for
help with the statistical analysis.
REFERENCES1. Bell WH, Fonseca RJ, Kenneky JW III, Levy BM. Bone healing
and revascularization after total maxillary osteotomy. J Oral Surg
1975;33:253-60.
2. Bell WH. Revascularization and bone healing after anterior max-
illary osteotomy: a study using adult rhesus monkeys. J Oral Surg
1969;27:249-55.
3. Nelson RL, Path MG, Ogle RG, Jensen GD, Olson DV, Soko-
loski PM, et al. Quantitation of blood flow after Le Fort I
osteotomy. J Oral Surg 1977;35:10-6.
4. Meyer MW, Cavanaugh GD. Blood flow changes after orthog-
nathic surgery: maxillary and mandibular subapical osteotomy.
J Oral Surg 1976;34:495-501.
5. Geylikman YB, Artun J, Leroux BG, Bloomquist D, Baab D,
Ramsay DS. Effects of Le Fort I osteotomy on human gingival
and pulpal circulation. Int J Oral Maxillofac Surg 1995;24:
255-60.
6. Qeujada JG, Kawamura H, Finn RA, Bell WH. Wound healingassociated with segmental total maxillary osteotomy. J Oral
Maxillofac Surg 1986;44:366-77.
7. Sugg GR, Fonseca RJ, Leeb IJ, Howell RM. Early pulp changes
after anterior maxillary osteotomy. J Oral Surg 1981;39:14-20.
8. Lanigan DT, West RA. Aseptic necrosis following maxillary
osteotomies: report of 36 cases. J Oral Maxillofac Surg
1990;48:296-300.
9. Epker BN. Vascular considerations in orthognathic surgery: 2.
Maxillary osteotomies. Oral Surg Oral Med Oral Pathol 1984;
57:467-72.
10. Emshoff R, Kranewitter R, Brunold S, Laimer K, Norer B.
Characteristics of pulpal blood flow levels associated with non-
segmented and segmented Le Fort I osteotomy. Oral Surg Oral
Med Oral Pathol Oral Radiol Endod 2008;105:379-84.11. Emshoff R, Kranewitter R, Gerhard S, Norer B, Hell B. Effect of
segmental Le Fort I osteotomy on maxillary tooth-type related
pulpal blood flow characteristics. Oral Surg Oral Med Oral
Pathol Oral Radiol Endod 2000;89:749-52.
12. Dodson TB, Bays RA. Maxillary perfusion during Le Fort I
osteotomy afterligation of the descending palatine artery. J Oral
Maxillofac Surg 1997;55:51-5.
13. Dodson TB, Bays RA, Paul RE, Neuenschwander MC. The
effect of local anesthesia with vasoconstrictor on gingival blood
flow during Le Fort I osteotomy. J Oral Maxillofac Surg
1996;54:810-4.
14. Dodson TB, Neuenschwander MC, Bays RA. Intraoperative as-
sessment of maxillary perfusion during Le Fort I osteotomy.
J Oral Maxillofac Surg 1994;52:827-31.15. Bell WH, Proffit WB. Maxillary excess. In: Bell WH, Proffit
WR, White RP, editors. Surgical correction of dentofacial defor-
mities. Philadelphia: Saunders; 1980. p. 234-442.
16. Hunsuck EE. A modified intraoral sagittal splitting technique for
correction of mandibular prognathism. J Oral Surg 1968;26:
250-3.
17. Firestone AR, Wheatley AM, Ther UW. Measurement of blood
perfusion in the dental pulp with laser Doppler flowmetry. Int J
Microcirc 1997;17:298-304.
18. Buckley JG, Jones ML, Hill M, Sugar AW. An evaluation of the
changes in maxillary blood flow associated with orthognathic
surgery. Br J Orthod 1991;26:39-45.
19. Harada K, Sato M, Omura K. Blood-flow and neurosensory
changes in the maxillary dental pulp after differing Le Fort Iosteotomies. Oral Surg Oral Med Oral Pathol Oral Radiol Endod
2004;97:12-7.
20. Harada K, Sato M, Omura K. Blood-flow change and recovery of
sensibility in the maxillary dental pulp during and after maxillary
distraction: a pilot study. Oral Surg Oral Med Oral Pathol Oral
Radiol Endod 2004;98:528-32.
21. Sato M, Harada K, Okada Y, Omura K. Blood-flow change and
recovery of sensibility in the maxillary dental pulp after a single-
segment LeFort I osteotomy. Oral Surg Oral Med Oral Pathol
Oral Radiol Endod 2003;95:660-4.
22. Justus T, Chang BL, Bloomquist D, Ramsey DS. Human gingi-
val and pulpal blood flow during healing after Le Fort I osteot-
omy. J Oral Maxillofac Surg 2001;59:2-7.
OOOOE
182 Kretschmer et al. August 2009
7/28/2019 Cambios en flujo sanguneo Le Fort I
6/6
23. Ramsay DS, Artun J, Bloomquist D. Orthognathic surgery and
pulpal blood flow: a pilot study using Laser Doppler flowmetry.
J Oral Maxillofac Surg 1991;49:564-70.
24. Yoshida S, Kazuhiko O, Kazuo T. Biological responses of the
pulp to single-tooth dento-osseous osteotomy. Oral Surg Oral
Med Oral Pathol Oral Radiol Endod 1996;82:152-60.
25. Hellem S, Jacobsson LS, Nilsson GE, Lewis DH. Measurement of
microvascular blood flow in cancellous bone using laser Dopplerflowmetry and 133Xe-clearance. Int J Oral Surg 1983;12:165-77.
26. Zisser G, Gattinger B. Histological investigations of pulpal
changes following maxillary and mandibular alveolar osteoto-
mies in the dog. J Oral Maxillofac Surg 1982;40:332-9.
27. Schuurman AH, Bos KE. Laser Doppler bone probe: an exper-
imental study in dogs. Microsurgery 1991;12:246-51.
28. Schuurman AH, Bos KE, Van Nus YH. Laser Doppler bone
probe in vascularized fibula transfers: a preliminary report. Mi-
crosurgery 1987;8:186-9.
29. Yuen JC, Feng Z. Monitoring free flaps using the laser Doppler
flowmeter: five-year experience. Plast Reconstr Surg 2000;105:
55-61.
30. Swiontkowski MF, Schlehr F, Collins JC, Sanders R, Pou A.
Comparison of two laser Doppler flowmetry systems for bone
blood flow analysis. Calcif Tissue Int 1988;43:103-7.
31. Swiontkowski MF, Collins JC, Schlehr A, Pou A, Sanders R.
Correlation of Laser Doppler flowmetry with microsphere esti-
mates for bone blood flow. Microcirculation-an update 1987;1:
341-3.
32. Swiontkowski MF, Tepic S, Perren SM, Moor R, Ganz R, Rahn
BA. Laser Doppler flow measurement: correlation with micro-
sphere estimates and evaluation of the effect of intracapsular
pressure on femoral head blood flow. J Orthop Res 1986;4:362-71.
33. Poswillo DE. Early pulp changes following reduction of open
bite by segmental surgery. Int J Oral Surg 1972;1:87-97.
34. Ware WH, Ashamalla M. Pulpal response following anterior
maxillary osteotomies. Am J Orthod 1971;60:156-64.
Reprint requests:
Winfried Bernhard Kretschmer, MD, DDS
Department of Oral and Maxillofacial Surgery
Marienhospital Stuttgart
Boeheimstr. 37
70199 Stuttgart, Germany
OOOOE
Volume 108, Number 2 Kretschmer et al. 183
mailto:[email protected]:[email protected]Top Related