Tolerances for deviations in eye and mouth position

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ORTHODONTICS ANDORTHODONTICS AND
CRANIOFACIALCRANIOFACIAL
RESEARCHRESEARCH
VOLUME 8VOLUME 8
MARCH 2005MARCH 2005

Tolerance of deviations in eye andTolerance of deviations in eye and
mouth positionmouth position
 CA Evans, G Viana, NK Anderson and DB GiddonCA Evans, G Viana, NK Anderson and DB Giddon
 The purpose of this study was to estimate a range of acceptableThe purpose of this study was to estimate a range of acceptable
appearances for selected facial features and refine techniquesappearances for selected facial features and refine techniques
for measurement. A psychophysical method was administeredfor measurement. A psychophysical method was administered
using photocopies of altered facial photographs to measureusing photocopies of altered facial photographs to measure
tolerances for deviations in eye position and mouth angulationstolerances for deviations in eye position and mouth angulations
and judges’ reaction time( 76 individuals). The results showedand judges’ reaction time( 76 individuals). The results showed
tolerance for deviation of facial appearance varies inverselytolerance for deviation of facial appearance varies inversely
with the magnitude of the physical deviations from normal.with the magnitude of the physical deviations from normal.
Tolerance varies directly as a function of assumed familiarityTolerance varies directly as a function of assumed familiarity
with deviation. Response and reaction time varied inverselywith deviation. Response and reaction time varied inversely
with the tolerance for facial deviation.with the tolerance for facial deviation.

The investigation of the changing facialThe investigation of the changing facial
appearance of identical twins employing a 3 Dappearance of identical twins employing a 3 D
laser imaging systemlaser imaging system
 CH Kau, A Zhurov, R Bibb, L Hunter and SCH Kau, A Zhurov, R Bibb, L Hunter and S
RichmondRichmond
 They determined the changing facial appearance ofThey determined the changing facial appearance of
identical twins employing a 3D laser imaging system.identical twins employing a 3D laser imaging system.
 Two Minolta Vivid 900 3D optical laser scannersTwo Minolta Vivid 900 3D optical laser scanners
were placed as a stereo pair to capture the soft tissueswere placed as a stereo pair to capture the soft tissues
of a pair of identical twins at different time intervals.of a pair of identical twins at different time intervals.
 The results showed that changes in height and weightThe results showed that changes in height and weight
correlated with changes in facial morphology.correlated with changes in facial morphology.

Short hard palate in prenatalShort hard palate in prenatal
trisomy 21trisomy 21
 H Lauridsen, BF Hansen, I Reintoft, JW Keeling,H Lauridsen, BF Hansen, I Reintoft, JW Keeling,
LT Skovgaard and I Kjaer.LT Skovgaard and I Kjaer.
 Used post mortal material to study the midpalatalUsed post mortal material to study the midpalatal
length of the hard palate and the length of its twolength of the hard palate and the length of its two
components in trisomy 21 fetuses.components in trisomy 21 fetuses.
 31 human fetuses was used. Palates were, after31 human fetuses was used. Palates were, after
sectioning, radio graphed in lateral projection. At 2sectioning, radio graphed in lateral projection. At 2
specific ages (150 and 170 mm CRL) measurementsspecific ages (150 and 170 mm CRL) measurements
done using digital caliper.done using digital caliper.
 They concluded that the total palatal length in prenatalThey concluded that the total palatal length in prenatal
trisomy 21 is shorter than normal due to bothtrisomy 21 is shorter than normal due to both
shortness of maxilla and palatine components of hardshortness of maxilla and palatine components of hard
palate.palate.

In vitro friction of stainless steel arch wire –In vitro friction of stainless steel arch wire –
bracket combinations in air and differentbracket combinations in air and different
aqueous solutionsaqueous solutions
 S Al-Khatib, A Berradja,J-P Celis and G WellemsS Al-Khatib, A Berradja,J-P Celis and G Wellems
 Investigated in vitro coefficient of friction of stainlessInvestigated in vitro coefficient of friction of stainless
steel archwire bracket combinations under frettingsteel archwire bracket combinations under fretting
contact test conditions performed in air and in differentcontact test conditions performed in air and in different
aqueous solutions.aqueous solutions.
 It was found that SS 18x25 exhibited higher frictionalIt was found that SS 18x25 exhibited higher frictional
forces than 17x25 SS.forces than 17x25 SS.
 For all aqueous solutions a lower coefficient of frictionFor all aqueous solutions a lower coefficient of friction
was found compared to test performed in ambient air.was found compared to test performed in ambient air.

Temporary loss of plasma membraneTemporary loss of plasma membrane
integrity in orthodontic tooth movementintegrity in orthodontic tooth movement
 MF Orellana-Lezcano, PW Major, PL McNeil andMF Orellana-Lezcano, PW Major, PL McNeil and
JL BorkeJL Borke
 A rat model of orthodontic tooth movement was usedA rat model of orthodontic tooth movement was used
to support the premise that pdl cells experienceto support the premise that pdl cells experience
plasma membrane disruption and resealing eventsplasma membrane disruption and resealing events
upon application of mechanical stress.upon application of mechanical stress.
 These studies provided evidence of a novel cellularThese studies provided evidence of a novel cellular
mechanism for uptake and release of molecules andmechanism for uptake and release of molecules and
suggest a potential role for plasma membranesuggest a potential role for plasma membrane
disruption in the mechanotransduction of orthodonticdisruption in the mechanotransduction of orthodontic
tooth movement.tooth movement. www.indiandentalacademy.comwww.indiandentalacademy.com

Identification of temporal pattern ofIdentification of temporal pattern of
mandibular condylar growth: a molecularmandibular condylar growth: a molecular
and biochemical experimentand biochemical experiment
 G Shen, U Hagg AB Rabbie and KG Shen, U Hagg AB Rabbie and K
KaluarachchiKaluarachchi
 The aim of the study was to establish theThe aim of the study was to establish the
temporal pattern of condylar growth intemporal pattern of condylar growth in
Sprague- Dawley rats by biochemicallySprague- Dawley rats by biochemically
identifying the expression of these two factors.identifying the expression of these two factors.
 In situ hybridization and immunoperoxidaseIn situ hybridization and immunoperoxidase
was used.was used.

 Results : Synthesis of type X collagen andResults : Synthesis of type X collagen and
emergence of capillary endothelium wereemergence of capillary endothelium were
critical factors during the transition ofcritical factors during the transition of
condylar cartilage from chondrogenesis intocondylar cartilage from chondrogenesis into
osteogenesis.osteogenesis.
 Thrust of natural growth of condyle occurredThrust of natural growth of condyle occurred
in concomitance with pubertal growth.in concomitance with pubertal growth.

Stem cells in craniofacialStem cells in craniofacial
and dental tissue engineeringand dental tissue engineering
MV Risbud and IM ShapiroMV Risbud and IM Shapiro

 STEM CELLSSTEM CELLS are primary undifferentiated cells which retain theare primary undifferentiated cells which retain the
ability to differentiate into other cell types. This allows them to act asability to differentiate into other cell types. This allows them to act as
a repair system for the body, replenishing other cells as long as thea repair system for the body, replenishing other cells as long as the
organism is alive.organism is alive.
 Ongoing investigations suggest that the progenitor cells are present inOngoing investigations suggest that the progenitor cells are present in
mature skeletal and dental tissues. This population of self-renewingmature skeletal and dental tissues. This population of self-renewing
stem cells is termedstem cells is termed Mesenchymal stem cellsMesenchymal stem cells..
 Mesenchymal stem cells have been identified as a population ofMesenchymal stem cells have been identified as a population of
pluripotentialpluripotential self-renewing cellsself-renewing cells..
 Based on their adherence and colony forming properties, a smallBased on their adherence and colony forming properties, a small
number of MSC can be isolated from Mesenchymal tissues and bonenumber of MSC can be isolated from Mesenchymal tissues and bone
marrow. In the presence of one or more growth factors, these cellsmarrow. In the presence of one or more growth factors, these cells
commit to lineages that lead to the formation of bone, cartilage,commit to lineages that lead to the formation of bone, cartilage,
muscle, tendon and adipose tissue ,etc.muscle, tendon and adipose tissue ,etc.www.indiandentalacademy.comwww.indiandentalacademy.com

 A major focus of contemporary studies inA major focus of contemporary studies in
developmental biology has been to delineate thedevelopmental biology has been to delineate the
biological cues that drive stem cell proliferationbiological cues that drive stem cell proliferation
and differentitation.and differentitation.
 4 signaling protein4 signaling protein families that govern patterningfamilies that govern patterning
are:are:
1.1. Fibroblast growth factorsFibroblast growth factors
2.2. Hedgehog proteinsHedgehog proteins
3.3. Bone morphogenesis proteinsBone morphogenesis proteins
4.4. Wingless- and int-related proteinsWingless- and int-related proteins

Research questionResearch question
 Identification and use of stem cells forIdentification and use of stem cells for
periodontal and orthognathic surgeryperiodontal and orthognathic surgery

MSC identification and localizationMSC identification and localization
 Fridenstein and co-workers demonstrated that boneFridenstein and co-workers demonstrated that bone
marrow derived adherent cells are capable ofmarrow derived adherent cells are capable of
committing to a number of lineages.committing to a number of lineages.
 To identify and quantitate tissue MSC, colonyTo identify and quantitate tissue MSC, colony
forming unit-fibroblast (CFU-F) is utilized.forming unit-fibroblast (CFU-F) is utilized.
 Adult tissue have 1MSC / 10Adult tissue have 1MSC / 10 4-64-6

Characteristics of MSCCharacteristics of MSC
 Expression of large no. of proteins on cellExpression of large no. of proteins on cell
surfacesurface
 Absence of antigens specific for cells of theAbsence of antigens specific for cells of the
hematopoietic lineagehematopoietic lineage
 Secrete cassette of cytokines.These proteinsSecrete cassette of cytokines.These proteins
can direct the commitment of the MSC intocan direct the commitment of the MSC into
one of a number of different differentiationone of a number of different differentiation
pathways.pathways.

Use of MSC for dental andUse of MSC for dental and
craniofacial tissue-engineeringcraniofacial tissue-engineering
 Stem cells are used to generate osteoblasts, chondrocytes andStem cells are used to generate osteoblasts, chondrocytes and
periodontal ligament cells and recently for odontoblasts andperiodontal ligament cells and recently for odontoblasts and
cementocytes.cementocytes.
 To promote osteogenesis, cells can be harvested from a numberTo promote osteogenesis, cells can be harvested from a number
of autologus sources including bone marrow and fatof autologus sources including bone marrow and fat
 ADVANTAGES: Committed MSC display a high biosyntheticADVANTAGES: Committed MSC display a high biosynthetic
response and do not display the surface antigen profile as matureresponse and do not display the surface antigen profile as mature
cells.cells.
 Eliminate worries about infection and immune rejection.Eliminate worries about infection and immune rejection.

Cranio facial applicationsCranio facial applications
 For repair and replacement or regeneration of oralFor repair and replacement or regeneration of oral
tissues and craniofacial bone.tissues and craniofacial bone.
 Post cancer ablative surgery, trauma, congenitalPost cancer ablative surgery, trauma, congenital
malformations and progressive skeletal disease.malformations and progressive skeletal disease.
 Basis for procedure: stem cells are seeded onto anBasis for procedure: stem cells are seeded onto an
appropriate scaffold material. Following proliferationappropriate scaffold material. Following proliferation
and differentiation, the hybrid is transplanted into theand differentiation, the hybrid is transplanted into the
bone defect.bone defect.
 Using a rapid prototyping technology, cell scaffoldUsing a rapid prototyping technology, cell scaffold
constructs are prepared with a high cell: matrix ratio,constructs are prepared with a high cell: matrix ratio,
permeated by a dense vascular network.permeated by a dense vascular network.

 To extend the life span of MSC, and to enhanceTo extend the life span of MSC, and to enhance
osteogenesis, cells have been engineered withosteogenesis, cells have been engineered with
human telomerase reverse transcriptase, tohuman telomerase reverse transcriptase, to
activate osteogenesis by fat derived MSC.activate osteogenesis by fat derived MSC.
 Sonic hedgehog gene has been transfected intoSonic hedgehog gene has been transfected into
marrow and fat derived MSC to repair a cranialmarrow and fat derived MSC to repair a cranial
bone defect.bone defect.
 Cell derived therapy focused on repair ofCell derived therapy focused on repair of
osseous defects has been successful.osseous defects has been successful.

Dental pulp applicationsDental pulp applications
 Gronthos et al. have isolated highly proliferative cellsGronthos et al. have isolated highly proliferative cells
from adult human dental pulp that exhibit a similarfrom adult human dental pulp that exhibit a similar
immuno –phenotype to bone marrow derived MSC.immuno –phenotype to bone marrow derived MSC.
 These cells display high alkaline phosphatase activityThese cells display high alkaline phosphatase activity
and form densely calcified nodule.and form densely calcified nodule.
 In vivo transplantation experiments showed that theseIn vivo transplantation experiments showed that these
cells form a dentin-like structure.cells form a dentin-like structure.
 Unlike bone marrow derived SC, pulp cells do notUnlike bone marrow derived SC, pulp cells do not
support the formation of a marrow or adipocytes.support the formation of a marrow or adipocytes.

Cementoblast-like cells applicationCementoblast-like cells application
 Sato et al. have developed a bovine cementoblastSato et al. have developed a bovine cementoblast
progenitor line. These cells were transplantedprogenitor line. These cells were transplanted
subcutaneously into nude mice on a hydroxyapatite/subcutaneously into nude mice on a hydroxyapatite/
tricalcium phosphate scaffold.tricalcium phosphate scaffold.
 Histological analysis indicated that a bone like tissueHistological analysis indicated that a bone like tissue
was formed containing cementocyte- like cells in awas formed containing cementocyte- like cells in a
mineralized matrix.mineralized matrix.
 Seo et al. reported isolation of multipotential stemSeo et al. reported isolation of multipotential stem
cells from human PDL, they differentiated intocells from human PDL, they differentiated into
cementoblat-like cells.cementoblat-like cells.

Periodontal regenerationPeriodontal regeneration
 Ligament complex contains stem cells that canLigament complex contains stem cells that can
commit to a number of pathways.commit to a number of pathways.
 These cells respond to inductive factors – TGFThese cells respond to inductive factors – TGFßß
,BMP2, BMP12 b-FGF.,BMP2, BMP12 b-FGF.
 Kawaguchi et al. used autologus bone marrow MSCKawaguchi et al. used autologus bone marrow MSC
in combination with atelocollagen to regeneratein combination with atelocollagen to regenerate
ligament in an experimental ClassIII defect in dogs.ligament in an experimental ClassIII defect in dogs.
One month after implantation, there was regenerationOne month after implantation, there was regeneration
of cementum, periodontal ligament and alveolar bone.of cementum, periodontal ligament and alveolar bone.

ConclusionConclusion
 Research efforts are beingResearch efforts are being
focused on identifying factors thatfocused on identifying factors that
regulate and control MSCregulate and control MSC
proliferation and commitment.proliferation and commitment.
 Stem cells that form bone,Stem cells that form bone,
cementum, dentin and PDL havecementum, dentin and PDL have
been identified, which can bebeen identified, which can be
used to restore the form andused to restore the form and
function of oral cavity.function of oral cavity.

Tolerances for deviations in eye and mouth position

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