Orthodontic Diagnosis For general practitioners Prepared by Dr. M Alruby Orthodontic diagnosis deals with recognition of the various characteristics of the malocclusion. It involves collection of data in a systematic manner to help in identifying the nature and cause of the problem. Comprehensive orthodontic diagnosis is established by use of certain clinical implements called diagnostic aids. Consideration of general health, appearance and attitude: The first step in any orthodontic examination is to form a general idea of patient's health status, physical appearance and attitude toward orthodontics. Case history: Case history involves eliciting and recording of relevant information from the patient and parents to aid in the overall diagnosis of the case. The information is gathered from the patient and parents. Personal details: Name: the patient's name should be recorded for the purpose of communication and identification. Most patients like being called by their name. Addressing the patient by his or her name has a beneficial psychological effect as well. In case of children it is wise to record their pet names. Age: the patient's chronological age should be recorded. Age consideration helps in diagnosis as well as treatment planning. There are certain modalities that are best carried out during the growing age. Growth modification procedures using functional and orthopedic appliances are carried out during the growth period. Surgical respective procedure is best carried out after the cessation of growth. ** Dental age determination: can be determined by two different methods: - Stage of eruption of teeth. - Stage of tooth mineralization on radiograph. Determination of the dental age from observation has been the only method available for long time. In certain cases however, the accuracy of the method is limited. When determining the dental age radiographically according to the stage of germination, the degree of development of individual teeth is compared to a fixed scale. ** Skeletal age evaluation: assessment of the skeletal age is often made with the help of a hand radiograph which can be considered the biologic clock. For the analysis of skeletal maturity the stage of mineralization of the carpal bones must be determined thereafter the development of the metacarpal bones and phalanges should be evaluated. For the evaluation of the hand radiograph various indicators regarding the development and maturity are established which occur regularly in a definite sequence during skeletal development. Sex: the patient sex should be recorded in the case history. This is important in planning treatment, as the timing of growth events such as growth spurts is different in males and females. Females usually precede males in onset of growth spurts, puberty and termination of growth. Address and occupation: this help in evaluation of socio-economic status of the patients and parents. Some countries

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Dr. Mohammed Alruby
Orthodontics for G.P
Orthodontic Diagnosis
For general practitioners
Prepared by Dr. M Alruby

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Dr. Mohammed Alruby
Orthodontics for G.P
Orthodontic diagnosis deals with recognition of the various characteristics of the
malocclusion. It involves collection of data in a systematic manner to help in identifying the
nature and cause of the problem. Comprehensive orthodontic diagnosis is established by use of
certain clinical implements called diagnostic aids.
Consideration of general health, appearance and attitude:
The first step in any orthodontic examination is to form a general idea of patient's health status,
physical appearance and attitude toward orthodontics.
Case history:
Case history involves eliciting and recording of relevant information from the patient and
parents to aid in the overall diagnosis of the case. The information is gathered from the patient
and parents.
Personal details:
Name: the patient's name should be recorded for the purpose of communication and
identification. Most patients like being called by their name. Addressing the patient by his or her
name has a beneficial psychological effect as well. In case of children it is wise to record their
pet names.
Age: the patient's chronological age should be recorded. Age consideration helps in diagnosis as
well as treatment planning. There are certain modalities that are best carried out during the
growing age. Growth modification procedures using functional and orthopedic appliances are
carried out during the growth period. Surgical respective procedure is best carried out after the
cessation of growth.
** Dental age determination: can be determined by two different methods:
- Stage of eruption of teeth.
- Stage of tooth mineralization on radiograph.
Determination of the dental age from observation has been the only method available for long
time. In certain cases however, the accuracy of the method is limited.
When determining the dental age radiographically according to the stage of germination, the
degree of development of individual teeth is compared to a fixed scale.
** Skeletal age evaluation: assessment of the skeletal age is often made with the help of a hand
radiograph which can be considered the biologic clock. For the analysis of skeletal maturity the
stage of mineralization of the carpal bones must be determined thereafter the development of the
metacarpal bones and phalanges should be evaluated. For the evaluation of the hand radiograph
various indicators regarding the development and maturity are established which occur
regularly in a definite sequence during skeletal development.
Sex: the patient sex should be recorded in the case history. This is important in planning
treatment, as the timing of growth events such as growth spurts is different in males and females.
Females usually precede males in onset of growth spurts, puberty and termination of growth.
Address and occupation: this help in evaluation of socio-economic status of the patients and
parents. Some countries have normal slight bimaxillary protrusion. We can determine the
awareness of the patients and his or her parents to the orthodontic treatment and this affect the
patient's cooperation.

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Dr. Mohammed Alruby
Orthodontics for G.P
Chief complaint:
The patient's chief complaint should be recorded in his or her own words. For any patient need
orthodontic treatment, complaint from:
1- Impaired dentofacial esthetic and this important to the patient because the teeth appear
unaesthetic, that can lead to psychological problems.
2- Impaired function.
3-
Medical history:
Before orthodontic treatment is undertaken, a full medical history is recorded. Fortunately
very few medical conditions contraindicate the use of orthodontic appliances most of these
conditions may require certain precautionary measures to be taken prior to or during the
orthodontic therapy. Diabetic patient must be under control and also needs special care before
and during treatment. Patients having rheumatic fever or cardiac anomalies require antibiotic
coverage. It is advisable to delay orthodontic treatment in patients suffering from epilepsy until it
is controlled. The medical history should include information on the drugs usage. The use of
certain drugs like aspirin may impede the orthodontic tooth movement. Patient that take a long
time suffer from metabolic disease as calcium and phosphorus disorder need special care
because this can affect the quality of the bone formation. Ask the patient about cancer, asthma,
anemia, liver disease, sleep problem, heart problem, speech and hearing problem, also need to
ask about allergy to certain drugs or others like latex or nickel. The use of long time with steroids
leads to less resistance to infection. Patient with thyroid hormone deficiency has a generalized
root resorption.
Dental history:
The dental history of the patient should include information on the age of eruption of
deciduous and permanent teeth. Ask about the dental health and care and times of tooth
brushing, history of tooth decay, extraction and restoration, and trauma to dentition or TMJ.
History about the caries index to the patient and the cooperation during any operative
procedure.
Family history:
Observe the anomalies that present in the family of the patient, as certain types of
malocclusion like Class II or Class III skeletal malocclusion has familial background. Some
congenital defects as cleft palate or cleft lip have familial background.
Behavior of the patient:
Behavior of the patient depends on:
1- Patient motivation for treatment.
2- What he or she expect as a result of treatment.
3- How patient cooperation or uncooperation is likely to be.
** Patient motivation: the patient motivation may be external that supplied by pressure from
another individual as parents or his or her friends that they need the teeth to look better. Or it
may be internal motivation that comes from within the individuals and based on his or her
assessment of situation and need for treatment. It is difficult to find purely internal motivation
especially in children but can be developed in adolescence. The motivation affect the cooperation
as the cooperation is better for the patient feels that the treatment is benefit for him than that
feels that this treatment similar to anything done to him. So it is necessary to ask the patient, do
you need the orthodontic treatment and why, to establish what motivation is rarely.
** Patient expectation: is very much related to the type of motivation.

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Orthodontics for G.P
** Patient cooperation: this more likely to problem in children than adults and determined by:
1- The extent to hich the child sees the treatment is benefit.
2- The degree of parents' control.
General examination:
The general examination comprises of the general assessment of the patient. An observant
clinician usually begins his general examination as soon as the patient enters the clinic. This
general examination as Height and weight, gait, posture, this can give an idea about:
- Growth and maturation of the patient that may have dento-facial correlation.
- Abnormalities in gait are usually associated with neuromuscular disorder that may have
dental correlation.
- Abnormal postures can predispose to malocclusion due to alteration in maxilla-
mandibular relationship.
Extra-oral examination:
The patient should be seated in the dental chair in an upright position and his head is
placed well over the vertebral column, and the Frankfort horizontal plane should be roughly
parallel to the floor and this position in the chair not usual for intra-oral examinations.
Frontal examination of the face:
Firstly divide the face into three thirds, upper, middle, lower third, (in vertical direction)
Upper third extended from the hair line to glabella and composed of cranium and forehead.
Middle extended from glabella to the junction of the nose and upper lip (subnasal).
Lower extended from subnasal to menton, and the lower third is divided into upper lip portion
and lower lip portion. Generally the three thirds should be equal to each other in its proportions.
** For horizontal direction: determine the facial midline of the face that passes through soft
tissue nasion, tip of the nose, and filtrum of the upper lip and this is an imaginary line on the face
and examine the structures on the face in relation to this line, the both sides should be equal in
horizontal direction. Patient that has normal vertical and horizontal proportions is considered as
a normal patient.
 Alar width: equal the size from the inner canthus of the eye to the inner canthus of the eye
on the other side.
 Mouth width: equal the inter-pupillary line of the eye.
Profile examination:
The vertical relationship of the face can be examined from the profile view as from the
frontal view, so it divided into three thirds and examine its relation to each other. The profile is
assessed by joining the two reference lines:
1- A line joining the forehead and the soft tissue point A (deepest point in the curvature of the
upper lip)
2- A line joining point A and soft tissue pogonion (most anterior point on the chin).
Based on the relationship between the two lines, three types of profile exist.
Convex: ------- --------------------- - Class II-------- retrognathic face.
Concave: --------- ------------------- Class III ------- prognathic face.
Straight or slight convex face: -----Class I -------- orthognathic face.

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** Clinical assessment of facial profile:
1- Visual examination of the patient during rest.
2- Palpation of maxillary and mandibular basal bone by index and middle finger when the
teeth in occlusion, but the thickness of the lips may interfere with this assessment so the
lips may retract to give a good diagnosis.
Pleasing of the patient:
The esthetic of the patient is difficult to detect because the esthetic is variable in its means
and differ from one person to another, the pleasing of the patient depend on the opinion of the
patient and doctor and others, and also depend on coincident of the facial proportions to each
other in vertical and horizontal direction and presence of a symmetry or not.
Examination of chin:
The chin position is evaluated with the patient's head oriented along the Frankfort
horizontal plane (FH), an imaginary line is drawn from soft tissue nasion perpendicular to FH
plane. If the chin falls significantly behind this line, it indicate anteroposterior mandibular
deficiency, if the chin is significantly in front of this line, it indicate anteroposterior mandibular
excess.
Mentolabial sulcus: the mento labial sulcus is a concavity seen below the lower lip. Deep mento-
labial sulcus is seen in Class II division 1 malocclusion while is shallow in bimaxillary
protrusion.
Mental activity: normally the mentalis muscle does not show any contraction at rest. Hyperactive
mentalis muscle as Class II division 1 cases puckering of the chin.
Examination of the nose:
Many congenital diseases are associated with abnormal nasal morphology: as congenital
syphilis that characterized by depressed nasal bridge, skeletal deep bite that characterized by
large nose and wide apertures, skeletal open bite that characterized by long slender nose and
narrow apertures.
The size, shape and position of the nose determine the esthetic appearance of the face, so the
assessment of the nose is important before treatment because rhinoplasty may be necessary later.
Nose size: normally the nose is one third of the total facial height (from hair line to lower border
of chin).
Nostrils: they are oval in shape and should be bilaterally symmetrical. Stenosis of the nostril may
be indicating impaired nasal breathing.
Width of the nostril is approximately 70% of the length of the nose.
Nasolabial angle: it is the angle formed between the lower border of the nose and a line
connecting the intersection of nose and upper lip with the tip of the lip (labrale superius) this
angle is normally 100 degree -+10 degree. It reduces in patients having proclined upper anterior
teeth or prognathic maxilla. It increases in patients with retrognathic maxilla or retroclined
maxillary anterior teeth.
Facial symmetry:
From the clinical point of view, there is no face that is symmetrical at all in all facial
dimensions either for vertical and horizontal because there is a small degree of bilateral facial
asymmetry exists in all normal individuals. This can be revealed most readily by comparing full
face photographs with composites consists of two right and two left sides and this called normal

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Orthodontics for G.P
a symmetry , which usually result from small size differences between the two sides and this
should be distinguished from the high disproportion in horizontal and vertical direction.
Examination of lips:
In normally relaxed unstrained position of the lips, the lips are sealed together, upper lip
measure one third of the lower face height, and lower lip measure two third of lower face height.
Normally the upper lip covers the entire labial surface of the upper incisors except about 2-3mm
from the incisal edge. The lower lip covers the entire labial surface of lower centeral incisors
and about 2-3mm of the incisal edge of the upper incisors.

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Dr. Mohammed Alruby
Orthodontics for G.P
Color of lips: the two lips should be had a similar colour and texture but in some cases that the
lower lips rests beneath the upper incisors during swallowing, it usually redder, heavier, moist
and smooth.
Lip steps: positive lip step: as in Class III.
Negative lip step: as in normal case and normal profile.
Marked negative lip step: as in case of Class II.
Types of lips:
1- Competent lip: the lips are slight contact when the musculatures are relaxed.
2- Incompetent lips: the lips are morphologically short that does not form a lip seal in
relaxed state. The lip seal can occur by active contraction of the lip musculature.
3- Potentially incompetent lips: they are normal lips fail to form seal due to proclined upper
incisors.
4- Everted lip: it is a hypotrophied lip with redundant tissue but weak muscular tonicity.
Lip dysfunction: can be observed during speaking and swallowing and present as lip sucking and
lip insufficiency. Any change in lips during function is a symptom of oro-facial dysfunction.
Physiologic analysis of the lips and face:
1- During rest: during rest upper and lower lips meet each other lightly without active
contraction to provide anterior oral seal, sometimes the lips may be habitual a part in few
nasal breather without dental interference.
2- During function:
a- Mastication: during normal mastication the lips are held lightly together. Strong
contraction will be seen in sever Class II malocclusion with large over jet.
b- Swallowing: during normal mature swallowing, the lips touch lightly without active
contraction, the facial muscles does not contract; the temporal muscle is contracting to
elevate the mandible.
Examination of breathing:
In normal breathing the lips touch lightly and breathing is achieved through the nose. But in
mouth breathing the lips are a parted, the mandible and the tongue assume in low position to
provide an adequate oral air way. The normal breathing is important because it allow
stimulation of the growth of the nasal air way by pressure of air through the nasal air way.
There are types of tests that used to examine the mode of breathing:
1- Mirror test: place a mirror in the front of the nasal orifices, the mirror is cloud in the case
of nasal breather.
2- Cotton butterfly test: place a thin cotton fiber against the nasal orifices it will move in
case of nasal breathing. This test used to determine unilateral nasal blockage.
3- Water test: the patient is asked to fill his mouth with water and retain it a period of time.
While the nasal breathers accomplished this with ease, mouth breathers fined the task
difficult.
4- Observation: In nasal breathers the external nares dilate during respiration. In mouth
breathers, there is either no change in the external nares or they may constrict during
inspiration.

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Dr. Mohammed Alruby
Orthodontics for G.P
Marked negative lip step negative lip step positive lip step
Incompetent lip competent lip

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Dr. Mohammed Alruby
Orthodontics for G.P
Normal tooth display gum smile
Intra-oral examination:
Examination of tongue:
Shape, color and configuration are assessed at the first clinical examination. The tongue
can be small, long, or broad in relation to the oral cavity.
Tongue size: In normal position of the tongue the lateral border touch the lingual cusps of
molars and premolars, the tip of the tongue rest on the lingual surface of the lower centeral
incisors, and the dorsum of the tongue touches the palate lightly the clinical picture of a long
tongue which can reach the tip of the nose.
When the lips are a parted by the mouth mirror or cheeks are withdrawn by cheek
retractors, normal tongue activity may be inhibited and what is observed is accommodation to
the stretching of the lips and cheeks.
Abnormalities of the tongue can upset the muscle balance and equilibrium leading to
malocclusion. Presence of large tongue size is indicated by the presence of imprints of the teeth
on the lateral margins of the tongue giving it a scalloped appearance.
The lingual frenum should be examined for tongue tie, in patients having tongue tie there is an
alteration in the resting position of the tongue as well as impairment of tongue movement.
Observe the tongue during swallowing, observe the role of the tongue during mastication,
and observe the role of the tongue during speech.
Examination of the palate:
The palate should be examined for the following finding:
1- Presence of any swelling on the palate can be indicative of an impacted tooth, presence of
cyst or other bony pathosis.
2- Mucosal ulceration and indentation are features of traumatic deep bite.
3- Presence of clefts in the palate is associated with discontinuity of the palate.
4- The third rugae is usually in line with the canines. This is useful in the assessment of the
maxillary anterior proclination.
The oral health is closely related to pharyngeal condition, inflamed, hypertrophied tissue or
infected tonsils may give rise to alteration in the tongue posture, mandibular posture, swallowing
or breathing reflexes.

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Orthodontics for G.P
Examination of gingiva:
The gingival should be examined for any inflammation, recession, and other mucogingival
lesions. Presence of poor oral hygiene is usually associated with generalized marginal gingivitis.
It is common to find anterior marginal gingivitis in mouth breathers due to dryness of the mouth
caused by the open lip posture. Presence of traumatic occlusion can cause localized gingival
recession.
In case of hyper active mentalis muscle, there is an inflammation on the lower anterior segment.
(Hyper active mentalis muscle characterized by deep mento-labial sulcus and this habitual
pattern of muscle impedes the forward development of anterior alveolar process in the mandible,
this abnormality can occur together with lip sucking)
Examination of dentition:
The dentition is examined and the following data are recorded:
1- Number of teeth present inside the oral cavity.
2- Number of unerupted and missing teeth.
3- Evaluation of the size of the teeth.
4- Examine the sequence of eruption of the teeth.
5- Examination of individual malposed teeth: malposition of teeth must be evaluated
according to their developmental status, not by their ultimate position in the line of the
arch, for example: maxillary cuspids usually erupt high in the alveolar process point
mesially and labially in such position normal only if there is adequate space in the arch
for the tooth.
6- Occlusal relationship of the teeth: with the mandible in the retruded contact position or
the ideal occlusal position, the examiner should explain the occlusal relationship of the
teeth in details, begging at one side in the molar region and advancing around the arch to
the opposite side.
1- Note the precise intercuspation of each of posterior teeth and whether the
intercuspation is symmetric.
2- Determine precisely the anteroposterior relationship of the molars and cuspids.
3- Measure the incisors relationship both vertically and horizontally. (Over jet and over
bite).
4- Note any lake of incisal stopper as in an open bite and fined any explanation for their
absence.
5- Palpate the teeth to observe any mobility of it.
Attached lingual frenum long size tongue

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Dr. Mohammed Alruby
Orthodontics for G.P
Broad size tongue tongue show indentation
Simple tongue thrust swallowing retained infantile swallowing
Lateral tongue thrust

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Dr. Mohammed Alruby
Orthodontics for G.P
Normal swallowing abnormal swallowing behavior
Highly attached labial freum

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Dr. Mohammed Alruby
Orthodontics for G.P
Functional examination:
Orthodontic diagnosis should not be restricted to static evaluation of the teeth and their
supporting structures but should include the examination of the various functional units of the
stomatognathic system. The functional examination should include the following:
1- Assessment of postural rest position and inter-occlusal space.
2- Path of closure.
3- Examination of temporomandibular joint.
4- Examination of swallowing.
5- Examination of speech.
Assessments of postural rest position and inter-occlusal clearance:
The postural rest position is the position of the mandible at which the muscles that close the jaws
and those that open them are, in a state of minimal contraction to maintain the posture of the
mandible. At the postural rest position, a space exists between the upper and lower jaws, this
space called the inter-occlusal clearance or the free way space. Normally the free way space is
3mm in the canine region.
The following are some of the methods used to record the postural rest position:
1- Phonetic method: the patient is asked to repeat some consonants like "M" or "C", the
mandible return to the postural rest position 1-2 seconds after the exercise. The patient is
told not to change the jaw, lip or tongue positions after the phonation, as the dentist a part
the lips to study the inter-occlusal space.
2- Command method: the patient is asked to perform certain functions as swallowing. The
mandible tends to return to rest position following this act.
3- Non command method: the patient is distracted so as not to perceive which type of
examination is being carried out. While being distracted the patient relax as well and the
mandible revert the postural rest position.
4- Tapping method: the chin is placed between the thumb and the fore finger, the clinician
uses this grip to carry out passive opening and closing movements of the mandible in
rapid succession in order to relax the masticatory muscles prior to determining the rest
position. Verify whether the musculature has been relaxed by palpating the sub- mental
muscles.
5- Direct intra-oral method: vernier calipers can be used directly in the patient's mouth at
the canine region to measure the free way space.
6- Direct extra-oral procedure: two marks are placed one at the tip of the nose and another
one at the chin in the midsagittal plane. The distance between the two points is measured
after instructing the patient to remain at rest position. Later the patient is asked to occlude
the teeth and the distance between the two points is again measured. The difference
between the two readings is the free way space.
7- Indirect extra-oral procedure: the inter-occlusal space is determined in the radiograph.
Two lateral cephalograms, one at rest position and the other at the centric occlusion, the
differences between the two measures is the free way space.
Evaluation of the path of closure:
The path of closure is the movement of the mandible from rest position to habitual occlusion;
abnormalities in the path of closure are seen in some forms of malocclusion.
1- Forward path of closure: a forward path of closure occurs in patients with edge to edge
incisors relationship. In such patients, the mandible is guided to a more forward position
to allow the mandibular incisors to go labial to the upper incisors.

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Orthodontics for G.P
2- Backward path of closure: in cases of Class II division 2 exhibit premature incisor contact
due to retroclined maxillary incisors. Thus the mandible is guided posteriorly to establish
occlusion.
3- Lateral path of closure: lateral deviation of the mandible to the right or to the left is
associated with occlusal prematurity and narrow maxillary arch.
Examination of the temporomandibular joint:
1- Auscultation: sounds made by the temporomandibular joints can be evaluated with a
stethoscope; even slight abnormal sounds can be registrated. Also the timing of the click
during opening or closing.
2- Lateral palpation of the temporomandibular joint: exert slight pressure on the condyle
with index finger to palpate both sides simultaneously, resister any tenderness to
palpation of the joints and any irregularities in condylar movement during opening and
closing. The coordination of the action between the right and left condylar head should be
assessed at the same time.
3- Posterior palpation of the TMJ: position of the little finger in the external auditory meatus
and palpate the posterior surface of the condyle during opening and closing movement of
the mandible, palpation should be carried out in such a way that the condyle displaces the
little finger when closing in full occlusion.
4- Recording inter-incisal distance: in maximum jaw opening the distance between the
incisal edge of the upper and lower centeral incisors are measured with Boley gauge. The
extent of maximum jaw opening between the incisal edges is usually 40-45 mm. in cases
with dysfunction, hyper mobility is often registered in the initial stage and limitation in the
later stage.
Examination of swallowing:
In newborn, the tongue is relatively large and protrudes between the gum pads and takes part in
establishing the lip seal. This kind of swallow is called infantile swallow and is seen till 1 1/2 to 2
years of age. Infantile swallow is replaced by mature swallow as the buccal teeth start erupting.
The persistence of infantile swallowing can be a cause for malocclusion, thus the swallowing
pattern of individual should be examined. The persistence of infantile swallow is indicated by the
presence of the following features:
a- Protrusion of the tip of the tongue.
b- Contraction of perioral muscles during swallowing.
c- No contact at the molar region during swallowing.
Examination of speech:
Certain malocclusion may cause defects in speech due to interference with the movement of the
tongue and lips. This should be observed while conversing with the patient. The patient can be
asked to read out from a book or asked to count from 1 – 20 while observing the speech. Patients
having tongue thrust habit tend to lisp while cleft patients may have a nasal tone.
Orthodontic study models:
It is the positive replica of the teeth and their supporting structure, it should be reproduce
accurately all the anatomical details of the teeth, alveolar process, mucobuccal folds, palate,
frenal attachments as well as the exact relationship of the mandibular and the maxillary dental
arch. Good models begin with good impression, orthodontic impression should displace the lips
and cheeks, so that; the full depth of mucobuccal sulci is recorded. This over extension of

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Orthodontics for G.P
impression is obtained by building up the tray periphery with wax or by using special orthodontic
trays. The position of maximum intercuspation should be recorded by getting the patient to bite
through softened wax that is important for:
1- Recording the proper intercuspation especially in cases of poor occlusal fit due to
extraction or tongue thrust. So that it is wise to check the occlusion in the mouth and
compare it to the occluded cast to insure that the model is correctly articulated.
2- Trimming the upper and lower cast together without change in the occlusal relationship
or fracture of the teeth.
Information obtained from study models:
1- To examine the occlusion from the lingual aspect as well as from the labio-buccal aspects.
2- To explain the treatment plane to the patient and his or her parents.
3- To detect the direction to which the teeth should be moved.
4- To determine the individual teeth malposition, rotation, axial inclination, midline shifting,
occlusal fitness and degree of over bite and over jet.
5- Arch length analysis either in mixed or permanent dentition.
6- The construction of diagnostic set up.
7- As pretreatment record to which results of treatment can be compared and as pos
treatment record to which the stability of occlusion can be checked.
8- Determination of transverse and anteroposterior a symmetry of the arch.
9- Classification of malocclusions.
10-It makes it possible to simulate treatment procedure on the cast such as mock surgery.
(N.B) gnathostatic models: they are study models where the base of the maxillary cast is trimmed
to correspond to the Frankfort horizontal plane.
Diagnostic set up: the individual teeth and their associated alveolar process are sectioned off
and replaced on the model base in the desired positions. The diagnostic set up helps in
simulating the various tooth movements that are planned for patients.
Uses of diagnostic set up:
1- It is useful in difficult space management problems to ascertain before orthodontic
treatment is begun, and the amount, direction of each tooth must be move.
2- It is best mathematical representation of the problem during the mixed dentition.
3- It is a popular practical technique for visualizing space problem in three dimensions in
the permanent dentition.
4- It well demonstrates the amount of space created by the extraction and the tooth
movement necessary to that space.
5- It also aid in choosing which teeth to be extracted.
The cast is cut using a fretsaw blade to separate the individual teeth. A horizontal cut is made
3mm apical to the gingival margin. Vertical cuts are made to separate the individual teeth, the
individual teeth are set in desired position using red wax.
Mixed dentition analysis: the purpose of mixed dentition analysis is to evaluate the amount of
space available in the arch for eruption of permanent teeth and occlusal adjustment.
Nance analysis: the length of the dental arch from the mesial surface of one mandibular 1st
molar
to the mesial surface of the corresponding tooth on the opposite side was always shortened
during the transition from the mixed dentition to the permanent dentition and this because of the
lee way space.
** The width of the erupted four mandibular permanent incisors is first measured.

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Orthodontics for G.P
** The width of the unerupted canines, 1st
premolar and 2nd
premolar on the radiograph should
be measured.
If one of the premolars on one side is rotated we can used the similar tooth on the other side.
*** The two measurements give an indication to the space needed to accommodate all the
permanent teeth anterior to the 1st
permanent molars.
*** Next step is to determine the amount of space available for the permanent and this by using
of 0.026 inch brass wire contoured on the arch surface and passing from the mesial surface of 1st
permanent molar of one side to the mesial surface of 1st
permanent molar on the other side. The
wire should passing through the buccal cusps of posterior teeth and the incisal edge of anterior
teeth for the lower arch, and for the upper arch should passing on the palatal surface of the
incisors. Then calculate the length of the brass wire that represents the space available.
Permanent dentition analysis:
1- Space analysis in permanent dentition:
For patients with mal-alignment of teeth resulting from lack of space, it is important to
determine from the study casts the amount of crowding in the maxillary and mandibular arches.
The purpose is to determine the differences between space available and space required for tooth
alignment. This means that two measurements are required in each arch for intra-maxillary
analysis of space requirement:
1- Calculation of space required.
2- Calculation of space available.
The Nance analysis:
1- Recording the mesiodistal w3idth of each tooth material to the 1st
permanent molar. The
sum total of the width corresponds to the necessary space required (ideal dental arch
length).
2- Recording the actual arch length using a soft wire this is contoured to the individual arch
shape and placed on the occlusal surface over the contact points of the posterior teeth and
palatal surface of upper anterior teeth an d incisal edge of lower anterior teeth, the
distance between the mesial contact points of the 1st
permanent molars on both sides –
recorded from the straightened – the amount of space available in the dental arch ( actual
arch length).
3- The assessment of space relationship is the result of the difference between the ideal and
actual arch length ( negative value= space deficiency, positive value = space excess)

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Dr. Mohammed Alruby
Orthodontics for G.P
Upper arch length lower arch length
Measurement of tooth material

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Dr. Mohammed Alruby
Orthodontics for G.P
2- Bolton' tooth ratio analysis:
Objective:
1- Studied the inter arch effects of discrepancies in tooth size to devise a procedure for
determining the ratio of total mandibular versus maxillary tooth size and anterior
mandibular versus maxillary tooth size.
2- Study of these ratio helps in estimating the over bite and over jet relationship that well
obtain after treatment finished.
3- Study of the effects of contemplated extraction on posterior occlusion and incisor
relationship and the identification of occlusal disharmony produced by interrelation of
tooth size in-compatibility.
Procedure: over all ratios
(Sum of width of 12 mandibular teeth / Sum of widths of 12 maxillary teeth X 100 = 91.3% (mean
ratio).
The mean ratio result in ideal over bite and over jet relationships. If the ratio increases, the
discrepancy is due to excessive mandibular tooth material. In the chart, one locates the figure
corresponding to the patient's maxillary tooth size, opposite is the desired mandibular
measurements. The difference between actual and the desired mandibular measurements is the
amount of excessive mandibular teeth material when ratio is greater than 91.3 %. If the ratio is
less than 91.3% the difference between the actual maxillary size and the desired maxillary size is
the amount of excessive maxillary tooth material.
Anterior ratio:
(Sum of the width of 6 mandibular anterior teeth / sum of the width of 6 maxillary anterior teeth
X 100 = 77.2%.
The desired anterior ratio is 77.2% which provide ideal over bite and over jet relationships. If
the angulations of the incisor are correct and if the labio-lingual thickness of the edges are not
excessive. If the anterior ratio increased, there is excess mandibular tooth material and vice
versa, i.e. there is excessive maxillary tooth material. If less than 77.2% there is excess maxillary
tooth material.
A quick method check for anterior tooth size discrepancies can be done by comparing the size of
the upper and lower lateral incisors and quick check for posterior teeth size discrepancies is to
compare the size of the upper and lower second premolars which should be equal size.
N:B: care must be taken in the use of this analysis since Bolton's formula don't take into account
quantitatively the incisor angulations.
Disharmony between the width of upper and lower teeth can be improved by
1- Alter the normal extraction plane to compensate for size discrepancies.
2- Interdental stripping.
3- In extreme cases by increasing the mesiodistal tooth size by adding composite resin or
crown.
4- Changing the inclination of the incisors.
5- Accept a small space in one of the arches, usually distal to the lateral incisors.

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Dr. Mohammed Alruby
Orthodontics for G.P
3- How's analysis
How's reported the fact that crowding could result not only from excessive tooth size but
also from inadequate apical base, so How's formula for determination whether the apical base
could accommodated the teeth.
Tooth material (TM) = the sum of mesiodistal diameter of the teeth from the first permanent
molars of one side to the other side.
Premolar diameter (PMD) = arch width measured at the tip of the buccal cusps of the 1st
premolar.
PMD /TM: ratio of premolar diameter to tooth material.
PMBAW: premolar basal arch width measured by bowed end of Boley gauge at the apical base
on the dental casts at the apices of the 1st
premolars.
BAL: basal arch length is measured at the midline from the estimated anterior limits of the apical
base to perpendicular that is tangent to the distal surface of the two first molars.
BAL / TM: ratio of basal arch length to tooth material.
For normal occlusion how's believed that the PMBAW should equal approximately 44% of
mesiodistal widths of the 12 teeth in the maxilla if is sufficient large to accommodates all the
teeth.
When BAL / TM ratio is less than 37% How's considered that is due basal arch deficiency
necessating extraction of premolars.
When the PMBAW is greater than the PM coronal arch width expansion of the premolars may be
undertaken safely.
The objective of How's analysis: it is useful in planning treatment of problem with suspected
apical base deficiency whether to be:
Extraction.
Expansion.
Or split the palate.
4- Palatal height: palatal height is defined as a vertical line perpendicular to the mid-
palatal raphe which runs from the surface of the palate to the level of the occlusal plane.
Palatal height index = palatal height / posterior arch width.
The average index is 42%. The index figure is increased when the palatal vault relative to the
transverse arch development is high and decreased when the palate is shallow.
A high palate is a principal feature of apical narrowing of the maxillary alveolar process which
often occurs in cases of chronic mouth breathing, rickets, and in certain types of sucking habits.
(The anterior arch width is defined as the distance between the anterior reference points
(premolar region). The posterior arch width is the distance between the 1st
molars.)
5- Peck and peck:
Peck and peck stated that well aligned mandibular incisors possess distinctive dimensional
characteristics (smaller mesio-distal (MD) and larger facio-lingual (FL) diameters)
The MD /FL index = MD / FL X 100.
Lower centeral incisor = 88.4 SD 4.3
Lower lateral incisor = 90.4 SD 4.8
For Egyptians:
Lower centeral incisors = 88.2 SD 0.58
Lower lateral incisor = 92.3 SD 0.62
If the index is within normal or less ----------------perfect alignment.
If the index is higher than this normal --------------crowding incisors.

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Dr. Mohammed Alruby
Orthodontics for G.P
Irregular mandibular incisors with favorable MD / FL indices reveal that factors other than
tooth shape are responsible for crowding. Stripping is described as a clinical procedure for
correcting tooth deviations.
6- arch symmetry: (Harvold symmetrograph:
The symmetrograph is transparent plastic device with an inscribed grid.
Steps:
1- Place the maxillary cast on its base and carefully mark the median palatine raphe with a
series of tiny dots.
2- Orient the symmetrograph so that its midline is directly superimposed over the median
palatine raphe and parallel to the occlusal surface.
3- Total and partial arch symmetry are quickly visualized and localized as are drifting,
tipping and rotation of individual teeth.
4- A similar analysis of the mandibular dentition was made but it was less precise than the
maxillary arch because the mandibular lingual frenum is not reliable median structure as
the palatine raphe.
Symmetrograph

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Dr. Mohammed Alruby
Orthodontics for G.P
Anteroposterior and transverse a symmetry

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Dr. Mohammed Alruby
Orthodontics for G.P
Shift of midline away from reference line
Measurements of curve of spee

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Dr. Mohammed Alruby
Orthodontics for G.P
Premolar basal arch width
Palatal height (Cast depth)