Transverse Stability after RPE in y Cleft Palate Patients

Transverse Stability y after RPE in
Cleft Palate Patients
109 th AAO Annual Session
Boston, MA 2009
AAaron MMolen, l DDS DDS, MS

Etiology of Cleft Palate
• Failure of the palatal shelves to fuse in utero
• Multifactorial
-Coronal slice of developing embryo-

Epidemiology of Cleft Palate
• 1.5 Clefts for every 1,000 births in U.S.A.
(Wyszynski 2002)
• Incidence of clefts is on the rise (Tolarova et al. 1998)

Developmental Problems
• Transverse Deficiency
• Anterior‐Posterior
Anterior Posterior
Deficiency

Overview of Treatment
• Complex treatment
utilizing multidisciplinary
team of physicians &
dentists
• From birth to adulthood
• GGoals l of f TTreatment: t t
• Esthetics
• Expansion of max max.
• Stabilization of max.
• Correct malocclusion
• Correct ant.-post.
issues

Transverse Deficiency
• At bbirth, h transverse
width of palate is
normal (Robertson et al. 1975)
• At 3 months, , ppalate
begins to collapse
around cleft (Ball ( et al. 1995) )
• At 3 years, transverse
collapse is complete
(Robertson et al. 1975)
• Maxilla is narrow
relative to mandible

Deciduous
Canine Permanent Unilateral
Transverse Problems
Centrals Cleft
• Narrow maxilla creates
problems p
(Gray 1975; Ross et al. 1967)
– Arch length
discrepancies (crowding)
– Retarded maxillary
growth ( (Maulina l et al. l 2007) )
– Dental cross‐bites
• Rapid palatal expansion
(RPE) ( )p performed to
correct these problems

Rapid Palatal Expander Designs

Stability of Expansion
• Conflicting fl findings f d in non‐cleft lfpopulation l
– 80% retained expansion at max. 1st molars at 1 year
(Lima et al. 2005)
– 40% retained expansion at max. 1st molars at 1 year
(Schiffman et al. 2001)
• Conflicting findings in cleft population
– 20% retained expansion at max. 1st 20% retained expansion at max. 1 molars at 1 year
– 63% retained expansion at max. canines at 1 year
(Nicholson et al. 1989)
– Max. Canines, 1st & 2nd premolars are stable at 8
years post‐treatment (Brägger et al. 1991)

Previous Study Methods
• Di Direct t measurements t on plaster l t casts t (Long et al. 1995)
– Prone to distortion when impressions are made
Onl er pted permanent 1st – Only erupted permanent 1 molars meas red
st molars measured
• Measurements on photographs (Ramstad et al. 1997)
– Sensitive to the angle and distance of camera
• Measurements on 2D projection images (Kindelan et al. 1999)
– Example: Lateral Head Films Films, Periapicals Periapicals, Occlusals
– Affected by variable magnification and
superimposition of structures
– Sensitive to orientation of patient
• Variable findings g of ppast studies may y be due to
poor imaging modalities

Cone‐Beam Computed Tomography
• CBCT is less prone to error
than previous p modalities
• Accurate from 0.125 to
04 0.4 mm with ihno detectable d bl magnification ifi i
• Slices can be viewed individually y
to eliminate overlapping structures
• Pti Patient’s t’ orientation i t ti (Cartesian (C t i coordinates) di t )
can be standardized using software

Gap in Knowledge
• Due to limitations of conventional 2D
projection p j imaging, g g, we have a limited
understanding of the transverse and anterior‐
posterior changes that occur in the maxilla
following palatal expansion
• Cone‐beam CT offers ff the potential to
investigate these changes with more accuracy

Statement of Purpose
• The h purpose of f this hi study d was to evaluate l short‐ h
term transverse stability after RPE in patients
with ith cleft lftpalate lt
• Specifically, does the amount of palatal expansion
performed before the graft, correlate to post‐
graft transverse changes at six months & one
year? ?
• Understanding this relationship is important
because insight into post‐expansion changes may
influence pre‐expansion treatment decisions

Time Points
• Pre‐Expansion/Initial (I): Before RPE.
• Post Post‐Expansion E pansion (E (Ex): ) Aft After RPE, RPE bbut tbf before graft. ft
• Post‐Graft (G): Within 1 month after graft.
• Six Months (M): 6 months after graft.
• OOne Year Y (Y) (Y): 1 year after ft graft.
ft

Data Collection
• CBCT scans captured using NewTom
– Isotropic Voxel Size: 0.4 mm
– Measurements accurate to ± 04mm 0.4 mm
• Scans converted to DICOM‐3 format in NewTom
software
• DICOM files uploaded into Dolphin 3D software for
measurements
– Dolphin 3D found to be accurate for X, Y, & Z
measurements compared to dry skulls (K (Kumar et t al. l 2008)
• All measurements made twice by same rater
• Sli Slices viewed i dat 33‐voxel l thickness hi k (1.2 mm)

UCLA UCLA‐Molen Molen 3D Orientation
First, the Z‐Points were Horizontally Aligned

UCLA‐Molen 3D Orientation
Second, Frankfort (Po‐Or) was Horizontally Aligned

UCLA‐Molen 3D Orientation
Third, the Zygomaticotemporal (ZT) Sutures were Horizontally Aligned

UCLA‐Molen 3D Orientation

Dental Landmarks (Axial View)
t‐Point
•Geometric G t i CCenter t of f TTooth th
(Midtgård et al. 1974)
•Less Sensitive to Rotation
•More oeSe Sensitive s t e to Tipping pp g

j‐Point
j
•Most Medial Point at CEJ
•Less Sensitive to Tipping
•More Sensitive to Rotation
(McDougall et al. 1982)

Dental Landmarks (Coronal View)
t‐point & j‐point were
located within the
same axial slice

Absolute Measurements (mm)
M 1st • Max. 1 M l (U6)
st Molars (U6)
– Middle of tooth (t) to Middle of tooth (t)
– Medial CEJ of tooth (j) to Medial CEJ of tooth (j)
• Max. 2 nd Premolars (U5)
– U5t and U5j
• Max. 1 st Premolars (U4)
– U4t and U4j
• Canines (U3)
– U3t and U3j
• Same measurements
for L6s, L6s L5s, L5s L4s, L4s & L3s

Relative Measurements (mm)
• Maxillary width minus mandibular width (D)
– Relative difference between arches
– Example: D6t = U6t (45 mm) – L6t (40 mm) = (5 mm)
– A Value over 4 mm indicates positive overlap

Alveolar Cleft Width Measurements
Measured at narrowest
Measured at narrowest
point of cleft
(Long et al. 1995)

Conclusion #1
• Relative palatal expansion in patients with
cleft palate p is stable at:
– The 1 st molars & 2 nd premolars through one year
The 1st – The 1 premolars through six months
st premolars through six months
6 mos.
1 yr.
1 yr.

Conclusion #2
• Absolute expansion of the max. 1st p premolars p
shows the greatest correlation with the
expansion of unilateral alveolar clefts
• Clinical Recommendation:
– Use modified expander design to direct expansive
pressure toward unerupted max. 1 st premolars

CConclusion l i #2
Fan‐Haas Combo
UCLA Expander

Conclusion #3
• Expansion is less stable in the anterior palate
(max. canines and 1st ( premolars) p )
• Clinical Recommendations:
– LLeave UCLA Expander E d iin place l after ft expansion i for f
retention or…
– Use modified trans‐palatal arch design

CConclusion l i #3

Conclusion #4
• Relative expansion of the 1 st molars at j‐point
shows the greatest g correlation with ppost‐graft g
expansion, measured at six months
t
j
j
t

Conclusion #5
• The UCLA‐Molen 3D Orientation is repeatable
and facilitates accurate X, , Y, , and Z
measurements between time points

Acknowledgements
• Special Thanks to:
– Dr. Jeanne Nervina, PhD, DMD, MS
• Assistant Professor, UCLA Section of Orthodontics
– Dr. Stuart White, PhD, DDS
• Chair, UCLA Section of Oral & Maxillofacial Radiology
– Dr. Eric Ting, DMSc, DMD
• Chair, UCLA Section of Orthodontics
– Dr. Hao‐Fu Lee, DDS, MS
• Vi Visiting iti AAssistant i t tP Professor f
– Dr. Bart Boulton, DDS
• UCLA Orthodontic Class of 2005
– Dr Dr. Christopher Cruz Cruz, DDS
• UCLA Orthodontic Class of 2005
– Ms. Lisa Yi, DMRT
• Clinic Administrator Administrator, UCLA Oral Radiology Clinic
– Dr. Jeffery Gornbein
• UCLA Biostatistics
– Mrs Mrs. Jennifer Egli
• UCLA Dental Class of 2009
– All of the Residents & their Patients