SlideShare a Scribd company logo
1 of 24
Download to read offline
The Plan of the Human Face
ACHIEVED BY: Dr.Maen Dawodi
The Plan of the human face :
A test of three general concepts
In the hand book of facial growth, Donald Enlow proposes a series of anatomic
concepts that account for the plan of the human face .Three of those concept
are examined in this article , which presents measurements of 253 adult
female primates from thirty-two species. As part of a system of craniofacial
counterparts, Enlow proposes that the breadth of the mandibular ramus
should equal the breadth of the pharynx.
The relationship between ramus breadth and PNS-Ba in the primates studied
strongly supports this hypothesis. A second concept tested concerns the
relationship between prognathism and maxillary arch length.
The relationship is not as strong as in the previous case, and some species are
more prognathic than required for the size of their dentition. It is concluded
that arch length and prognathism have an important biologic relationship but
that two features can vary with some independence.
The 3rd concept tested is the relationship
between prognathism and interorbital
breadth.
Here the relationship is weak, and it is
concluded that the interorbital breadth it
is not significant in setting a structural
limit to the amount of facial prognathism.
• In Chapter 4 of the Hand book of
Facial Growth, Enlow Lists ten
concepts provide a basis for
explaining much of the anatomic
and functional organization of the
human face and the reasons for
differences in facial morphology
among mammals.
• While all of the concepts appear
reasonable and can be supported
by illustrations, many have never
been tested .The purpose of this
study is to use the comparative
morphology of non human
primates to test three specific
principles proposed by Enlow
• The first specific test concerns the relationship
between the anteroposterior dimensions of the
pharynx and mandibular ramus.
• As part of a more general discussion of
craniofacial counterparts, Enlow relates these
structures as follows
The Pharynx relates specifically to the middle cranial
fossa. Because of the human cranial floor flexure, the
size of the middle cranial fossa in man determines
the horizontal dimension of the pharyngeal space .
The dimensions of the middle cranial fossa should be
equaled by the breadth of the mandibular ramus.The
function of the ramus is to span the pharynx and
middle cranial fossa in order to place the lower arch
in occasions with the upper.
• The second concept to be tested is the
relationship between prognathism and
maxillary dental arch length
Enlow describe this relationship as follows
The reduction of the nasal region
associated with orbital convergence and
olfactory –anterior cranial fossa rotation
must necessarily also be accompanied by a
more or less equal reduction in maxillary
arch length , because the floor of the nasal
chamber is also the roof of the mouth.
• Because the Interorbital segment is the root of the
nasal region , a decrease in this dimension reduces
the structural (and also physiologic) base of the
bony nose . A wide nasal base can support a
proportionately longer snout. A narrow nasal base
however reduces the architectural limit to which
the bony part of the nose can protrude and the
snout is thereby shorter
• Finally, Enlow also proposes a structural
relationship between interorbital breadth and
prognathism
In order to have a comprehensive and systematic survey
of higher primates , the species selected include one
from every genus of Old World monkeys, NewWorld
monkeys , and apes , except for the small South
American Callithricidae.
MATERIALS & METHODS
Primate skeletal material in the collections of the
American Museum (Smithsonian Institution),The
Museum of Comparative Zoology (Harvard University),
and the British Museum of Natural History were
examined. Measurements from a total of 253 adults
female primates , consisting of 3 to 10 specimens of
each of 32 species , are included in the study .
• Adults were defined by the eruption of third molars into occlusion. Zoo specimens and
animals with excessive dental wear were excluded .The following variables were
measured on each specimen.
• The following variables were measured on each specimen:
• 1.Prognathism = Defined as the distance from orbitale to prosthion,parallel to occlusal
• plane.
• 2.Ramus breadth =The anteroposterior dimension of the ramus at the level of the
• occlusal plane.
• 3.Interorbital breadth =The minimum distance between the medial borders of the orbits.
• 4.PNS-Ba = Posterior nasal spine to basion
• 5.Maxillary arch length = Measured in the midline from the incisal edge of the maxillary
• central incisor to a line connecting the distal marginal ridges of the
• left and right third molars
RESULTS
• The mandibular ramus as a counterpart to the pharynx
• For all 32 species , the mean breadth of the mandibular
ramus is 26.1 mm, and the mean distance from PNS to
basion is 37.9 mm , a difference of 11.8 mm.The smallest
difference between measurements is 7.3 mm. for
Mandrillus, and the largest is 19.5 mm for Pongo
(orangutan) . In 23 of the 32 species the PNS-Ba dimension
is between 8.5 and 13.5 mm larger than the breadth of the
ramus .
RESULTS
• For the 32 species ,the
correlations coefficient
between ramus breadth and
PNS-Ba is 0.97 when the two
variables are plotted against
each other (Figure 1 shown)
• All points are rather close to
the regression line. When
PNS-Ba is used to predict
ramus breadth , no species is
more than 20% from its
expected value and all but 6
are within 10% of what would
be predicted by the
regression equation.
• Prognathism and maxillary arch length
• The mean length of the maxillary tooth row is 44.5 mm.,
and the mean prognathism is 23.9 mm , a difference of
20.6mm.The smallest difference between prognathism and
arch length is in the baboon , Papio anubis , in which the
tooth row is only 3.4mm greater in length than the
prognathism.
• When oriented parallel to the occlusal plane, almost the
entire dentition of this species is in front of the orbits .The
greatest difference between arch length and prognathism is
36.6 mm in the gorilla. For this species , about 40% of the
maxillary arch is under and behind the orbits , rather than
projected infront of them.
• The correlation between arch length and prognathism for
these 32 species is 0.92 .The regression equation resulting
from an attempt to predict tooth row length from
prognathism is shown in the figure 2 . 14 of 32 species differ
by more than 10% from predicted values
• Interorbital breath and prognathism
• The mean value of the interorbital breadth in the 32 species is 8.8 mm, with a range of 3.2
to 24.3mmThe mean prognathism is 23.9mm , with a range of 6.9 to 67.4 mm. Unlike the
previous two comparisons , these two measurement do not bear a constant relationship
to other .
• The species with the greatest interorbital breadth (24.3) is the gorilla, which has a
prognathism of 53.6 mm. However , orangutan , with a similar prognathism of 51.9mm ,
has an interorbital breadth of 11.1 mm, and Mandrillus , with a prognathism of 51.2mm ,
has an interorbital breadth of Callicebus , which has only 7.1 mm of the prognathism.The
most prognathic species Papio anubis , has an interorbital dimension of 8.9 mm , only 0.1
mm. greater than the average for all species
• The correlation coefficient between interorbital breadth and prognathism is 0.46.
Transformation of the data to logarithms , which is often done to improve the fit of this
type of data , increases correlation to 0.56 .
• When prognathism is used in a
regression equation to predict
interorbital breadth , 28 out of
32 species are predicted
incorrectly by more than 10%
and six by more than 50%
(figure 3 shown)
• DISCUSSION
• As proposed by Enlow , the first concept tested in this study involves a relationship
between
• 3 Structures :
• 1.Middle cranial fossa
• 2.The pharynx
• 3.The mandibular ramus.
• The specimens available to us did not allow any measurement of internal cranial
dimensions , so our test of this concept involves only the pharynx and the ramus
• In human beings , the posterior wall of the pharynx is demarcated by the pharyngeal
tubercles , which are several millimeters anterior to basion.
• In many non human primates , however , these tubercles are difficult to define, and the
angular relationship between the pharynx and the mouth makes the tubercles less
significant as a mark of pharyngeal depth .
• We consider PNS-Ba to represent a reasonable reproducible approximation for pharynx
depth in these highly diverse species.
• DISCUSSION cont.1
• For the second and 3rd concepts Enlow interchangeably uses “nasal chamber” , “nasal
region”, “bony nose” ,and“snout” as the feature related to maxillary arch length (concept 2)
or interorbital breadth (concept 3).We have quantified this feature as the distance that the
face protrudes in front of the orbits . Our measurement could be named in several different
ways , including “ prognathism” or snout length , and appears to us to be closely related to
the facial characteristics addressed by Enlow .
• The relationship between the ramus breadth and PNS-Ba reported in this study is a striking
confirmation of the counterpart model of craniofacial morphology as proposed by Enlow and
his co workers .The fact that the ramus dimensions and PNS-Ba differ in absolute size is not
of importance .
• Measurement of ramus breadth varies at different positions on the ramus ; PNS-Ba is not an
exact substitute for the pharynx , and soft tissues would modify the relationship between
skeletal dimensions .
• In addition to the high correlation coefficient , the average difference of 11 t0 12 mm
between ramus breadth and PNS-Ba is usually constant , particularly considering the range
of the skull size for these species
• DISCUSSION cont.2
• Callicebus torquatus ,with an average body weight of about 0.7kg. and a skull
length of about 66mm , has a difference of 11.0 mm between PNS-Ba and
ramus breadth.The gorilla at over 92 kg. in body weight and 223 mm. in skull
length , has a PNS-Ba ramus breadth difference of 13.5 mm.
• This degree of similarity is unusual in comparative metric studies over large size
range .
• The relationship between the ramus breadth and prognathism can be cast as
either supporting or contradicting Enlow’s model .
• The correlation coefficient between these two variables is high, and clearly
there is a biologic relationship between prognathism and arch length. Species
with long maxillary dental arches have a strong tendency to be more
prognathic . However , it is also evident that the organization of the face can be
altered in a variety of ways to accommodate a long dental arch.
• Some species are more like Homo sapiens in having dental arch arranged at
least partially “under” the orbits , while others, particularly baboons , have
almost the entire dentition positioned in front of the skull base and orbits .
• DISCUSSION cont.3
• There is some evidence of a relationship between prognathism and root size ,but a
simple cephalometric inspection of a prognathic species , such as Papio anubis , indicates
that the degree of prognathism is greater than that necessary to accommodate the roots
of the teeth.(figure shown)
• A consequence of this variability between prognathism and tooth size is that it is difficult
for one to argue that human beings have flat faces because the dentition has become
reduced during the later phases of hominid evolution .
• Differences in the morphology of primate faces indicate that the size of the dentition and
prognathism can evolve with some independence.
• DISCUSSION cont.4
• The hypothesis that interorbital breadth limits the size of the nasal region was first proposed
by Enlow in 1968 and was discussed at length by Enlow and McNamara.
• The results of the present study do not support this hypothesis. A correlation of 0.46
indicates that approximately 20% of the variability in interorbital breadth and prognathism is
related .
• Both prognathism and Interorbital breadth are correlated with the overall size of a species. In
comparing different species , we find that most skull dimensions increase as the overall size
of the skull becomes larger.
• The correlation of interorbital breadth with body weight for these thirty –two species is 0.81,
and the correlation of prognathism with body weight is 0.64.Thus , even if prognathism and
interorbital breadth have no functional relationship to each other, it is that they would be
correlated to some extent , because each is correlated to a 3rd variable –overall size.
• For a study using animals that vary more than 100-fold in body weight , a correlation of 0.46
between two anatomically related skeletal features is unusually low.
• There is some evidence , from both comparative morphology and biomechanical modeling ,
that the interorbital region aids in absorbing and transmitting forces of mastication
• DISCUSSION cont.5
• Hylander notes that the role of the interorbital region may depend upon detailed
morphologic features .
• If interorbital breadth is wide because of extension of the nasal process of the maxilla, forces
generated at the maxillary teeth could be transmitted to the frontal bone , but if the
interorbital structure consists primarily of the nasal bones , w/o a large nasal processes of the
maxilla , force transmission through this area will be lower.
• In either case , it cab be concluded that the structural base that support a protruding muzzle
is not determined by the interorbital breadth . It may be that prognathic primates can use the
entire width of the face in the orbital region as an architectural base for a snout .
• The reduced interorbital breadth and reduced prognathism of man are features that could
have evolved independently , instead of as structural and physiologic consequences of each
other .
• DISCUSSION cont.6
• In interpreting the results of this study , it should be recognized that whether or not the
concepts tested are confirmed depends in part on specific species selected for analysis.
• For example , baboons are unusual in facial form, and a broad survey of different mammals
instead of only primates ( or a study of primates excluding baboons ) might have yielded
different findings .Nevertheless , there is good justification for including a typical species ,
such as baboons , for they result in a more stringent test of the concept under consideration.
• The results also depend upon the precise definitions of measurements . However , the
different versions of essentially similar measurements would be highly correlated with each
other and would produce results with same general implications.
• AJODO 1984Feb.Vol.85 #2(Richard Smith DMD,Ph.D.,Stuart D.Josell,DMD
MSD)
Thank you

More Related Content

Similar to The Plan of the Human Face in orthodontics .pptx

Palatal rugae as an aid for personnel identification
Palatal rugae as an aid for personnel identification Palatal rugae as an aid for personnel identification
Palatal rugae as an aid for personnel identification
Rupal Patle
 
Adamsposter
AdamsposterAdamsposter
Adamsposter
adamem
 

Similar to The Plan of the Human Face in orthodontics .pptx (20)

Cephalometic
CephalometicCephalometic
Cephalometic
 
MODEL ANALYSIS
MODEL ANALYSISMODEL ANALYSIS
MODEL ANALYSIS
 
Bjork& jarabak cephalometric analysis
Bjork& jarabak cephalometric analysisBjork& jarabak cephalometric analysis
Bjork& jarabak cephalometric analysis
 
Rhinoplasty.pptx
Rhinoplasty.pptxRhinoplasty.pptx
Rhinoplasty.pptx
 
Model analysis in orthodontics
Model analysis in orthodonticsModel analysis in orthodontics
Model analysis in orthodontics
 
Soft tissue cephalometrics analysis /certified fixed orthodontic courses by I...
Soft tissue cephalometrics analysis /certified fixed orthodontic courses by I...Soft tissue cephalometrics analysis /certified fixed orthodontic courses by I...
Soft tissue cephalometrics analysis /certified fixed orthodontic courses by I...
 
Palatal rugae as an aid for personnel identification
Palatal rugae as an aid for personnel identification Palatal rugae as an aid for personnel identification
Palatal rugae as an aid for personnel identification
 
Correction of deep bite
Correction of deep biteCorrection of deep bite
Correction of deep bite
 
Model Analysis
Model AnalysisModel Analysis
Model Analysis
 
Henry versus thompson approach for fixation of proximal third radial shaft fr...
Henry versus thompson approach for fixation of proximal third radial shaft fr...Henry versus thompson approach for fixation of proximal third radial shaft fr...
Henry versus thompson approach for fixation of proximal third radial shaft fr...
 
Model analysis.ppt
Model analysis.pptModel analysis.ppt
Model analysis.ppt
 
maxillary anatomical landmarks
maxillary anatomical landmarksmaxillary anatomical landmarks
maxillary anatomical landmarks
 
Study models in Orthodontics
Study models in OrthodonticsStudy models in Orthodontics
Study models in Orthodontics
 
Aocmf classification . 2014, level 3 , condylar fracture ,
Aocmf classification . 2014, level 3 , condylar fracture ,Aocmf classification . 2014, level 3 , condylar fracture ,
Aocmf classification . 2014, level 3 , condylar fracture ,
 
L shaped columellar strut in asian nose(asian rhinoplasty)
L shaped columellar strut in asian nose(asian rhinoplasty)L shaped columellar strut in asian nose(asian rhinoplasty)
L shaped columellar strut in asian nose(asian rhinoplasty)
 
Surgical orthodontics / dental crown & bridge courses
Surgical orthodontics / dental crown & bridge coursesSurgical orthodontics / dental crown & bridge courses
Surgical orthodontics / dental crown & bridge courses
 
Surgical orthodontics / oral surgery courses
Surgical orthodontics / oral surgery courses  Surgical orthodontics / oral surgery courses
Surgical orthodontics / oral surgery courses
 
Surgical orthodontics/dental crown & bridge courses
Surgical orthodontics/dental crown & bridge coursesSurgical orthodontics/dental crown & bridge courses
Surgical orthodontics/dental crown & bridge courses
 
Adamsposter
AdamsposterAdamsposter
Adamsposter
 
transverse dentoskeletal features of anterior open bite in the mixed dentitio...
transverse dentoskeletal features of anterior open bite in the mixed dentitio...transverse dentoskeletal features of anterior open bite in the mixed dentitio...
transverse dentoskeletal features of anterior open bite in the mixed dentitio...
 

More from Maen Dawodi

Twin Block appliance in orthodontics .pptx
Twin Block appliance in orthodontics .pptxTwin Block appliance in orthodontics .pptx
Twin Block appliance in orthodontics .pptx
Maen Dawodi
 
‏‏THE TREATMENT OF CLASS II, DIVISION 1 MALOCCLUSION WITH FUNCTIONAL CORRECTO...
‏‏THE TREATMENT OF CLASS II, DIVISION 1 MALOCCLUSION WITH FUNCTIONAL CORRECTO...‏‏THE TREATMENT OF CLASS II, DIVISION 1 MALOCCLUSION WITH FUNCTIONAL CORRECTO...
‏‏THE TREATMENT OF CLASS II, DIVISION 1 MALOCCLUSION WITH FUNCTIONAL CORRECTO...
Maen Dawodi
 
THE INVISALIGN aligner in orthodontics .pptx
THE INVISALIGN aligner in orthodontics .pptxTHE INVISALIGN aligner in orthodontics .pptx
THE INVISALIGN aligner in orthodontics .pptx
Maen Dawodi
 
Skeletal Profile Changes Related to Two Patterns of Activator Affects.pptx
Skeletal Profile Changes Related to Two Patterns of Activator Affects.pptxSkeletal Profile Changes Related to Two Patterns of Activator Affects.pptx
Skeletal Profile Changes Related to Two Patterns of Activator Affects.pptx
Maen Dawodi
 
SELECTED FOREIGN DENTAL JURISPRUDENCE.pptx
SELECTED FOREIGN DENTAL JURISPRUDENCE.pptxSELECTED FOREIGN DENTAL JURISPRUDENCE.pptx
SELECTED FOREIGN DENTAL JURISPRUDENCE.pptx
Maen Dawodi
 
Orthopedic coordination of dentofacial development in skeletal Class II maloc...
Orthopedic coordination of dentofacial development in skeletal Class II maloc...Orthopedic coordination of dentofacial development in skeletal Class II maloc...
Orthopedic coordination of dentofacial development in skeletal Class II maloc...
Maen Dawodi
 

More from Maen Dawodi (20)

Twin Block appliance in orthodontics .pptx
Twin Block appliance in orthodontics .pptxTwin Block appliance in orthodontics .pptx
Twin Block appliance in orthodontics .pptx
 
TORQUE AND ITS APPLICATION TO ORTHODONTICS.pptx
TORQUE AND ITS APPLICATION TO           ORTHODONTICS.pptxTORQUE AND ITS APPLICATION TO           ORTHODONTICS.pptx
TORQUE AND ITS APPLICATION TO ORTHODONTICS.pptx
 
THERMOFIT By KELLER LABORATORIES.pptx
THERMOFIT    By KELLER LABORATORIES.pptxTHERMOFIT    By KELLER LABORATORIES.pptx
THERMOFIT By KELLER LABORATORIES.pptx
 
‏‏THE TREATMENT OF CLASS II, DIVISION 1 MALOCCLUSION WITH FUNCTIONAL CORRECTO...
‏‏THE TREATMENT OF CLASS II, DIVISION 1 MALOCCLUSION WITH FUNCTIONAL CORRECTO...‏‏THE TREATMENT OF CLASS II, DIVISION 1 MALOCCLUSION WITH FUNCTIONAL CORRECTO...
‏‏THE TREATMENT OF CLASS II, DIVISION 1 MALOCCLUSION WITH FUNCTIONAL CORRECTO...
 
THE THREE ORDER BENDS in STANDARD EDGEWISE TECHNIQUE.pptx
THE THREE ORDER BENDS  in STANDARD EDGEWISE TECHNIQUE.pptxTHE THREE ORDER BENDS  in STANDARD EDGEWISE TECHNIQUE.pptx
THE THREE ORDER BENDS in STANDARD EDGEWISE TECHNIQUE.pptx
 
THE INVISALIGN aligner in orthodontics .pptx
THE INVISALIGN aligner in orthodontics .pptxTHE INVISALIGN aligner in orthodontics .pptx
THE INVISALIGN aligner in orthodontics .pptx
 
Stability of Orthopedic and Surgically Assisted Rapid Palatal Expansion Over ...
Stability of Orthopedic and Surgically Assisted Rapid Palatal Expansion Over ...Stability of Orthopedic and Surgically Assisted Rapid Palatal Expansion Over ...
Stability of Orthopedic and Surgically Assisted Rapid Palatal Expansion Over ...
 
Skeletal Profile Changes Related to Two Patterns of Activator Affects.pptx
Skeletal Profile Changes Related to Two Patterns of Activator Affects.pptxSkeletal Profile Changes Related to Two Patterns of Activator Affects.pptx
Skeletal Profile Changes Related to Two Patterns of Activator Affects.pptx
 
SELECTED FOREIGN DENTAL JURISPRUDENCE.pptx
SELECTED FOREIGN DENTAL JURISPRUDENCE.pptxSELECTED FOREIGN DENTAL JURISPRUDENCE.pptx
SELECTED FOREIGN DENTAL JURISPRUDENCE.pptx
 
PRINCIPLES AND DOCTRINES IN DENTAL MALPRACTICE.pptx
PRINCIPLES AND DOCTRINES  IN DENTAL MALPRACTICE.pptxPRINCIPLES AND DOCTRINES  IN DENTAL MALPRACTICE.pptx
PRINCIPLES AND DOCTRINES IN DENTAL MALPRACTICE.pptx
 
Pathways To Better Speech Speech Mechanism .pptx
Pathways To Better Speech Speech Mechanism   .pptxPathways To Better Speech Speech Mechanism   .pptx
Pathways To Better Speech Speech Mechanism .pptx
 
Orthoplus Functional education devices .pptx
Orthoplus Functional education devices .pptxOrthoplus Functional education devices .pptx
Orthoplus Functional education devices .pptx
 
Orthopedic coordination of dentofacial development in skeletal Class II maloc...
Orthopedic coordination of dentofacial development in skeletal Class II maloc...Orthopedic coordination of dentofacial development in skeletal Class II maloc...
Orthopedic coordination of dentofacial development in skeletal Class II maloc...
 
Orthodontic Forsus Fatigue Resistant Device.pptx
Orthodontic Forsus Fatigue Resistant Device.pptxOrthodontic Forsus Fatigue Resistant Device.pptx
Orthodontic Forsus Fatigue Resistant Device.pptx
 
Orthodontic Elastics Elastics Forces.pptx
Orthodontic Elastics Elastics Forces.pptxOrthodontic Elastics Elastics Forces.pptx
Orthodontic Elastics Elastics Forces.pptx
 
Memory Titanol Spring for Uprighting of Molar.pptx
Memory Titanol Spring for Uprighting of Molar.pptxMemory Titanol Spring for Uprighting of Molar.pptx
Memory Titanol Spring for Uprighting of Molar.pptx
 
INTRAORAL ELASTICS in orthodontics .pptx
INTRAORAL ELASTICS  in orthodontics .pptxINTRAORAL ELASTICS  in orthodontics .pptx
INTRAORAL ELASTICS in orthodontics .pptx
 
HEADGEAR and FACE MASK ORTHOPEDIC FORCE .pptx
HEADGEAR and  FACE MASK ORTHOPEDIC FORCE .pptxHEADGEAR and  FACE MASK ORTHOPEDIC FORCE .pptx
HEADGEAR and FACE MASK ORTHOPEDIC FORCE .pptx
 
Genetics and Immunity The Immune System.pptx
Genetics and Immunity The Immune System.pptxGenetics and Immunity The Immune System.pptx
Genetics and Immunity The Immune System.pptx
 
Types of tooth movement orthodontic.pptx
Types of tooth movement orthodontic.pptxTypes of tooth movement orthodontic.pptx
Types of tooth movement orthodontic.pptx
 

Recently uploaded

❤️ Chandigarh Call Girls☎️98151-579OO☎️ Call Girl service in Chandigarh ☎️ Ch...
❤️ Chandigarh Call Girls☎️98151-579OO☎️ Call Girl service in Chandigarh ☎️ Ch...❤️ Chandigarh Call Girls☎️98151-579OO☎️ Call Girl service in Chandigarh ☎️ Ch...
❤️ Chandigarh Call Girls☎️98151-579OO☎️ Call Girl service in Chandigarh ☎️ Ch...
Rashmi Entertainment
 
Russian Call Girls In Pune 👉 Just CALL ME: 9352988975 ✅❤️💯low cost unlimited ...
Russian Call Girls In Pune 👉 Just CALL ME: 9352988975 ✅❤️💯low cost unlimited ...Russian Call Girls In Pune 👉 Just CALL ME: 9352988975 ✅❤️💯low cost unlimited ...
Russian Call Girls In Pune 👉 Just CALL ME: 9352988975 ✅❤️💯low cost unlimited ...
chanderprakash5506
 
Cara Menggugurkan Kandungan Dengan Cepat Selesai Dalam 24 Jam Secara Alami Bu...
Cara Menggugurkan Kandungan Dengan Cepat Selesai Dalam 24 Jam Secara Alami Bu...Cara Menggugurkan Kandungan Dengan Cepat Selesai Dalam 24 Jam Secara Alami Bu...
Cara Menggugurkan Kandungan Dengan Cepat Selesai Dalam 24 Jam Secara Alami Bu...
Cara Menggugurkan Kandungan 087776558899
 
Call Girl in Chennai | Whatsapp No 📞 7427069034 📞 VIP Escorts Service Availab...
Call Girl in Chennai | Whatsapp No 📞 7427069034 📞 VIP Escorts Service Availab...Call Girl in Chennai | Whatsapp No 📞 7427069034 📞 VIP Escorts Service Availab...
Call Girl in Chennai | Whatsapp No 📞 7427069034 📞 VIP Escorts Service Availab...
amritaverma53
 
👉 Chennai Sexy Aunty’s WhatsApp Number 👉📞 7427069034 👉📞 Just📲 Call Ruhi Colle...
👉 Chennai Sexy Aunty’s WhatsApp Number 👉📞 7427069034 👉📞 Just📲 Call Ruhi Colle...👉 Chennai Sexy Aunty’s WhatsApp Number 👉📞 7427069034 👉📞 Just📲 Call Ruhi Colle...
👉 Chennai Sexy Aunty’s WhatsApp Number 👉📞 7427069034 👉📞 Just📲 Call Ruhi Colle...
rajnisinghkjn
 

Recently uploaded (20)

Circulatory Shock, types and stages, compensatory mechanisms
Circulatory Shock, types and stages, compensatory mechanismsCirculatory Shock, types and stages, compensatory mechanisms
Circulatory Shock, types and stages, compensatory mechanisms
 
Race Course Road } Book Call Girls in Bangalore | Whatsapp No 6378878445 VIP ...
Race Course Road } Book Call Girls in Bangalore | Whatsapp No 6378878445 VIP ...Race Course Road } Book Call Girls in Bangalore | Whatsapp No 6378878445 VIP ...
Race Course Road } Book Call Girls in Bangalore | Whatsapp No 6378878445 VIP ...
 
Call 8250092165 Patna Call Girls ₹4.5k Cash Payment With Room Delivery
Call 8250092165 Patna Call Girls ₹4.5k Cash Payment With Room DeliveryCall 8250092165 Patna Call Girls ₹4.5k Cash Payment With Room Delivery
Call 8250092165 Patna Call Girls ₹4.5k Cash Payment With Room Delivery
 
ANATOMY AND PHYSIOLOGY OF RESPIRATORY SYSTEM.pptx
ANATOMY AND PHYSIOLOGY OF RESPIRATORY SYSTEM.pptxANATOMY AND PHYSIOLOGY OF RESPIRATORY SYSTEM.pptx
ANATOMY AND PHYSIOLOGY OF RESPIRATORY SYSTEM.pptx
 
ANATOMY AND PHYSIOLOGY OF REPRODUCTIVE SYSTEM.pptx
ANATOMY AND PHYSIOLOGY OF REPRODUCTIVE SYSTEM.pptxANATOMY AND PHYSIOLOGY OF REPRODUCTIVE SYSTEM.pptx
ANATOMY AND PHYSIOLOGY OF REPRODUCTIVE SYSTEM.pptx
 
Call Girls in Lucknow Just Call 👉👉8630512678 Top Class Call Girl Service Avai...
Call Girls in Lucknow Just Call 👉👉8630512678 Top Class Call Girl Service Avai...Call Girls in Lucknow Just Call 👉👉8630512678 Top Class Call Girl Service Avai...
Call Girls in Lucknow Just Call 👉👉8630512678 Top Class Call Girl Service Avai...
 
❤️ Chandigarh Call Girls☎️98151-579OO☎️ Call Girl service in Chandigarh ☎️ Ch...
❤️ Chandigarh Call Girls☎️98151-579OO☎️ Call Girl service in Chandigarh ☎️ Ch...❤️ Chandigarh Call Girls☎️98151-579OO☎️ Call Girl service in Chandigarh ☎️ Ch...
❤️ Chandigarh Call Girls☎️98151-579OO☎️ Call Girl service in Chandigarh ☎️ Ch...
 
Russian Call Girls In Pune 👉 Just CALL ME: 9352988975 ✅❤️💯low cost unlimited ...
Russian Call Girls In Pune 👉 Just CALL ME: 9352988975 ✅❤️💯low cost unlimited ...Russian Call Girls In Pune 👉 Just CALL ME: 9352988975 ✅❤️💯low cost unlimited ...
Russian Call Girls In Pune 👉 Just CALL ME: 9352988975 ✅❤️💯low cost unlimited ...
 
Cara Menggugurkan Kandungan Dengan Cepat Selesai Dalam 24 Jam Secara Alami Bu...
Cara Menggugurkan Kandungan Dengan Cepat Selesai Dalam 24 Jam Secara Alami Bu...Cara Menggugurkan Kandungan Dengan Cepat Selesai Dalam 24 Jam Secara Alami Bu...
Cara Menggugurkan Kandungan Dengan Cepat Selesai Dalam 24 Jam Secara Alami Bu...
 
Call Girls Mussoorie Just Call 8854095900 Top Class Call Girl Service Available
Call Girls Mussoorie Just Call 8854095900 Top Class Call Girl Service AvailableCall Girls Mussoorie Just Call 8854095900 Top Class Call Girl Service Available
Call Girls Mussoorie Just Call 8854095900 Top Class Call Girl Service Available
 
Call Girls in Lucknow Just Call 👉👉 8875999948 Top Class Call Girl Service Ava...
Call Girls in Lucknow Just Call 👉👉 8875999948 Top Class Call Girl Service Ava...Call Girls in Lucknow Just Call 👉👉 8875999948 Top Class Call Girl Service Ava...
Call Girls in Lucknow Just Call 👉👉 8875999948 Top Class Call Girl Service Ava...
 
Call Girls Service Jaipur {9521753030 } ❤️VVIP BHAWNA Call Girl in Jaipur Raj...
Call Girls Service Jaipur {9521753030 } ❤️VVIP BHAWNA Call Girl in Jaipur Raj...Call Girls Service Jaipur {9521753030 } ❤️VVIP BHAWNA Call Girl in Jaipur Raj...
Call Girls Service Jaipur {9521753030 } ❤️VVIP BHAWNA Call Girl in Jaipur Raj...
 
💞 Safe And Secure Call Girls Coimbatore🧿 6378878445 🧿 High Class Coimbatore C...
💞 Safe And Secure Call Girls Coimbatore🧿 6378878445 🧿 High Class Coimbatore C...💞 Safe And Secure Call Girls Coimbatore🧿 6378878445 🧿 High Class Coimbatore C...
💞 Safe And Secure Call Girls Coimbatore🧿 6378878445 🧿 High Class Coimbatore C...
 
Call Girl in Chennai | Whatsapp No 📞 7427069034 📞 VIP Escorts Service Availab...
Call Girl in Chennai | Whatsapp No 📞 7427069034 📞 VIP Escorts Service Availab...Call Girl in Chennai | Whatsapp No 📞 7427069034 📞 VIP Escorts Service Availab...
Call Girl in Chennai | Whatsapp No 📞 7427069034 📞 VIP Escorts Service Availab...
 
👉 Chennai Sexy Aunty’s WhatsApp Number 👉📞 7427069034 👉📞 Just📲 Call Ruhi Colle...
👉 Chennai Sexy Aunty’s WhatsApp Number 👉📞 7427069034 👉📞 Just📲 Call Ruhi Colle...👉 Chennai Sexy Aunty’s WhatsApp Number 👉📞 7427069034 👉📞 Just📲 Call Ruhi Colle...
👉 Chennai Sexy Aunty’s WhatsApp Number 👉📞 7427069034 👉📞 Just📲 Call Ruhi Colle...
 
Call Girls Wayanad Just Call 8250077686 Top Class Call Girl Service Available
Call Girls Wayanad Just Call 8250077686 Top Class Call Girl Service AvailableCall Girls Wayanad Just Call 8250077686 Top Class Call Girl Service Available
Call Girls Wayanad Just Call 8250077686 Top Class Call Girl Service Available
 
Call Girls Bangalore - 450+ Call Girl Cash Payment 💯Call Us 🔝 6378878445 🔝 💃 ...
Call Girls Bangalore - 450+ Call Girl Cash Payment 💯Call Us 🔝 6378878445 🔝 💃 ...Call Girls Bangalore - 450+ Call Girl Cash Payment 💯Call Us 🔝 6378878445 🔝 💃 ...
Call Girls Bangalore - 450+ Call Girl Cash Payment 💯Call Us 🔝 6378878445 🔝 💃 ...
 
💰Call Girl In Bangalore☎️63788-78445💰 Call Girl service in Bangalore☎️Bangalo...
💰Call Girl In Bangalore☎️63788-78445💰 Call Girl service in Bangalore☎️Bangalo...💰Call Girl In Bangalore☎️63788-78445💰 Call Girl service in Bangalore☎️Bangalo...
💰Call Girl In Bangalore☎️63788-78445💰 Call Girl service in Bangalore☎️Bangalo...
 
7 steps How to prevent Thalassemia : Dr Sharda Jain & Vandana Gupta
7 steps How to prevent Thalassemia : Dr Sharda Jain & Vandana Gupta7 steps How to prevent Thalassemia : Dr Sharda Jain & Vandana Gupta
7 steps How to prevent Thalassemia : Dr Sharda Jain & Vandana Gupta
 
Call girls Service Phullen / 9332606886 Genuine Call girls with real Photos a...
Call girls Service Phullen / 9332606886 Genuine Call girls with real Photos a...Call girls Service Phullen / 9332606886 Genuine Call girls with real Photos a...
Call girls Service Phullen / 9332606886 Genuine Call girls with real Photos a...
 

The Plan of the Human Face in orthodontics .pptx

  • 1. The Plan of the Human Face ACHIEVED BY: Dr.Maen Dawodi
  • 2. The Plan of the human face : A test of three general concepts
  • 3. In the hand book of facial growth, Donald Enlow proposes a series of anatomic concepts that account for the plan of the human face .Three of those concept are examined in this article , which presents measurements of 253 adult female primates from thirty-two species. As part of a system of craniofacial counterparts, Enlow proposes that the breadth of the mandibular ramus should equal the breadth of the pharynx. The relationship between ramus breadth and PNS-Ba in the primates studied strongly supports this hypothesis. A second concept tested concerns the relationship between prognathism and maxillary arch length. The relationship is not as strong as in the previous case, and some species are more prognathic than required for the size of their dentition. It is concluded that arch length and prognathism have an important biologic relationship but that two features can vary with some independence.
  • 4. The 3rd concept tested is the relationship between prognathism and interorbital breadth. Here the relationship is weak, and it is concluded that the interorbital breadth it is not significant in setting a structural limit to the amount of facial prognathism.
  • 5. • In Chapter 4 of the Hand book of Facial Growth, Enlow Lists ten concepts provide a basis for explaining much of the anatomic and functional organization of the human face and the reasons for differences in facial morphology among mammals. • While all of the concepts appear reasonable and can be supported by illustrations, many have never been tested .The purpose of this study is to use the comparative morphology of non human primates to test three specific principles proposed by Enlow
  • 6. • The first specific test concerns the relationship between the anteroposterior dimensions of the pharynx and mandibular ramus. • As part of a more general discussion of craniofacial counterparts, Enlow relates these structures as follows The Pharynx relates specifically to the middle cranial fossa. Because of the human cranial floor flexure, the size of the middle cranial fossa in man determines the horizontal dimension of the pharyngeal space . The dimensions of the middle cranial fossa should be equaled by the breadth of the mandibular ramus.The function of the ramus is to span the pharynx and middle cranial fossa in order to place the lower arch in occasions with the upper.
  • 7. • The second concept to be tested is the relationship between prognathism and maxillary dental arch length Enlow describe this relationship as follows The reduction of the nasal region associated with orbital convergence and olfactory –anterior cranial fossa rotation must necessarily also be accompanied by a more or less equal reduction in maxillary arch length , because the floor of the nasal chamber is also the roof of the mouth.
  • 8. • Because the Interorbital segment is the root of the nasal region , a decrease in this dimension reduces the structural (and also physiologic) base of the bony nose . A wide nasal base can support a proportionately longer snout. A narrow nasal base however reduces the architectural limit to which the bony part of the nose can protrude and the snout is thereby shorter • Finally, Enlow also proposes a structural relationship between interorbital breadth and prognathism
  • 9. In order to have a comprehensive and systematic survey of higher primates , the species selected include one from every genus of Old World monkeys, NewWorld monkeys , and apes , except for the small South American Callithricidae. MATERIALS & METHODS Primate skeletal material in the collections of the American Museum (Smithsonian Institution),The Museum of Comparative Zoology (Harvard University), and the British Museum of Natural History were examined. Measurements from a total of 253 adults female primates , consisting of 3 to 10 specimens of each of 32 species , are included in the study .
  • 10. • Adults were defined by the eruption of third molars into occlusion. Zoo specimens and animals with excessive dental wear were excluded .The following variables were measured on each specimen. • The following variables were measured on each specimen: • 1.Prognathism = Defined as the distance from orbitale to prosthion,parallel to occlusal • plane. • 2.Ramus breadth =The anteroposterior dimension of the ramus at the level of the • occlusal plane. • 3.Interorbital breadth =The minimum distance between the medial borders of the orbits. • 4.PNS-Ba = Posterior nasal spine to basion • 5.Maxillary arch length = Measured in the midline from the incisal edge of the maxillary • central incisor to a line connecting the distal marginal ridges of the • left and right third molars
  • 11. RESULTS • The mandibular ramus as a counterpart to the pharynx • For all 32 species , the mean breadth of the mandibular ramus is 26.1 mm, and the mean distance from PNS to basion is 37.9 mm , a difference of 11.8 mm.The smallest difference between measurements is 7.3 mm. for Mandrillus, and the largest is 19.5 mm for Pongo (orangutan) . In 23 of the 32 species the PNS-Ba dimension is between 8.5 and 13.5 mm larger than the breadth of the ramus .
  • 12. RESULTS • For the 32 species ,the correlations coefficient between ramus breadth and PNS-Ba is 0.97 when the two variables are plotted against each other (Figure 1 shown) • All points are rather close to the regression line. When PNS-Ba is used to predict ramus breadth , no species is more than 20% from its expected value and all but 6 are within 10% of what would be predicted by the regression equation.
  • 13. • Prognathism and maxillary arch length • The mean length of the maxillary tooth row is 44.5 mm., and the mean prognathism is 23.9 mm , a difference of 20.6mm.The smallest difference between prognathism and arch length is in the baboon , Papio anubis , in which the tooth row is only 3.4mm greater in length than the prognathism. • When oriented parallel to the occlusal plane, almost the entire dentition of this species is in front of the orbits .The greatest difference between arch length and prognathism is 36.6 mm in the gorilla. For this species , about 40% of the maxillary arch is under and behind the orbits , rather than projected infront of them. • The correlation between arch length and prognathism for these 32 species is 0.92 .The regression equation resulting from an attempt to predict tooth row length from prognathism is shown in the figure 2 . 14 of 32 species differ by more than 10% from predicted values
  • 14. • Interorbital breath and prognathism • The mean value of the interorbital breadth in the 32 species is 8.8 mm, with a range of 3.2 to 24.3mmThe mean prognathism is 23.9mm , with a range of 6.9 to 67.4 mm. Unlike the previous two comparisons , these two measurement do not bear a constant relationship to other . • The species with the greatest interorbital breadth (24.3) is the gorilla, which has a prognathism of 53.6 mm. However , orangutan , with a similar prognathism of 51.9mm , has an interorbital breadth of 11.1 mm, and Mandrillus , with a prognathism of 51.2mm , has an interorbital breadth of Callicebus , which has only 7.1 mm of the prognathism.The most prognathic species Papio anubis , has an interorbital dimension of 8.9 mm , only 0.1 mm. greater than the average for all species • The correlation coefficient between interorbital breadth and prognathism is 0.46. Transformation of the data to logarithms , which is often done to improve the fit of this type of data , increases correlation to 0.56 .
  • 15. • When prognathism is used in a regression equation to predict interorbital breadth , 28 out of 32 species are predicted incorrectly by more than 10% and six by more than 50% (figure 3 shown)
  • 16. • DISCUSSION • As proposed by Enlow , the first concept tested in this study involves a relationship between • 3 Structures : • 1.Middle cranial fossa • 2.The pharynx • 3.The mandibular ramus. • The specimens available to us did not allow any measurement of internal cranial dimensions , so our test of this concept involves only the pharynx and the ramus • In human beings , the posterior wall of the pharynx is demarcated by the pharyngeal tubercles , which are several millimeters anterior to basion. • In many non human primates , however , these tubercles are difficult to define, and the angular relationship between the pharynx and the mouth makes the tubercles less significant as a mark of pharyngeal depth . • We consider PNS-Ba to represent a reasonable reproducible approximation for pharynx depth in these highly diverse species.
  • 17. • DISCUSSION cont.1 • For the second and 3rd concepts Enlow interchangeably uses “nasal chamber” , “nasal region”, “bony nose” ,and“snout” as the feature related to maxillary arch length (concept 2) or interorbital breadth (concept 3).We have quantified this feature as the distance that the face protrudes in front of the orbits . Our measurement could be named in several different ways , including “ prognathism” or snout length , and appears to us to be closely related to the facial characteristics addressed by Enlow . • The relationship between the ramus breadth and PNS-Ba reported in this study is a striking confirmation of the counterpart model of craniofacial morphology as proposed by Enlow and his co workers .The fact that the ramus dimensions and PNS-Ba differ in absolute size is not of importance . • Measurement of ramus breadth varies at different positions on the ramus ; PNS-Ba is not an exact substitute for the pharynx , and soft tissues would modify the relationship between skeletal dimensions . • In addition to the high correlation coefficient , the average difference of 11 t0 12 mm between ramus breadth and PNS-Ba is usually constant , particularly considering the range of the skull size for these species
  • 18. • DISCUSSION cont.2 • Callicebus torquatus ,with an average body weight of about 0.7kg. and a skull length of about 66mm , has a difference of 11.0 mm between PNS-Ba and ramus breadth.The gorilla at over 92 kg. in body weight and 223 mm. in skull length , has a PNS-Ba ramus breadth difference of 13.5 mm. • This degree of similarity is unusual in comparative metric studies over large size range . • The relationship between the ramus breadth and prognathism can be cast as either supporting or contradicting Enlow’s model . • The correlation coefficient between these two variables is high, and clearly there is a biologic relationship between prognathism and arch length. Species with long maxillary dental arches have a strong tendency to be more prognathic . However , it is also evident that the organization of the face can be altered in a variety of ways to accommodate a long dental arch. • Some species are more like Homo sapiens in having dental arch arranged at least partially “under” the orbits , while others, particularly baboons , have almost the entire dentition positioned in front of the skull base and orbits .
  • 19. • DISCUSSION cont.3 • There is some evidence of a relationship between prognathism and root size ,but a simple cephalometric inspection of a prognathic species , such as Papio anubis , indicates that the degree of prognathism is greater than that necessary to accommodate the roots of the teeth.(figure shown) • A consequence of this variability between prognathism and tooth size is that it is difficult for one to argue that human beings have flat faces because the dentition has become reduced during the later phases of hominid evolution . • Differences in the morphology of primate faces indicate that the size of the dentition and prognathism can evolve with some independence.
  • 20. • DISCUSSION cont.4 • The hypothesis that interorbital breadth limits the size of the nasal region was first proposed by Enlow in 1968 and was discussed at length by Enlow and McNamara. • The results of the present study do not support this hypothesis. A correlation of 0.46 indicates that approximately 20% of the variability in interorbital breadth and prognathism is related . • Both prognathism and Interorbital breadth are correlated with the overall size of a species. In comparing different species , we find that most skull dimensions increase as the overall size of the skull becomes larger. • The correlation of interorbital breadth with body weight for these thirty –two species is 0.81, and the correlation of prognathism with body weight is 0.64.Thus , even if prognathism and interorbital breadth have no functional relationship to each other, it is that they would be correlated to some extent , because each is correlated to a 3rd variable –overall size. • For a study using animals that vary more than 100-fold in body weight , a correlation of 0.46 between two anatomically related skeletal features is unusually low. • There is some evidence , from both comparative morphology and biomechanical modeling , that the interorbital region aids in absorbing and transmitting forces of mastication
  • 21. • DISCUSSION cont.5 • Hylander notes that the role of the interorbital region may depend upon detailed morphologic features . • If interorbital breadth is wide because of extension of the nasal process of the maxilla, forces generated at the maxillary teeth could be transmitted to the frontal bone , but if the interorbital structure consists primarily of the nasal bones , w/o a large nasal processes of the maxilla , force transmission through this area will be lower. • In either case , it cab be concluded that the structural base that support a protruding muzzle is not determined by the interorbital breadth . It may be that prognathic primates can use the entire width of the face in the orbital region as an architectural base for a snout . • The reduced interorbital breadth and reduced prognathism of man are features that could have evolved independently , instead of as structural and physiologic consequences of each other .
  • 22. • DISCUSSION cont.6 • In interpreting the results of this study , it should be recognized that whether or not the concepts tested are confirmed depends in part on specific species selected for analysis. • For example , baboons are unusual in facial form, and a broad survey of different mammals instead of only primates ( or a study of primates excluding baboons ) might have yielded different findings .Nevertheless , there is good justification for including a typical species , such as baboons , for they result in a more stringent test of the concept under consideration. • The results also depend upon the precise definitions of measurements . However , the different versions of essentially similar measurements would be highly correlated with each other and would produce results with same general implications.
  • 23. • AJODO 1984Feb.Vol.85 #2(Richard Smith DMD,Ph.D.,Stuart D.Josell,DMD MSD)