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Camelia Szuhanek Eleonora Schiller

Adelina Grigore Adelina Popa

A GUIDE TO

ORTHODONTICS

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LABORATORY GUIDES

COLLECTION

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“VICTOR BABEŞ” UNIVERSITY OF MEDICINE AND PHARMACY TIMIŞOARA FACULTY OF DENTAL MEDICINE

Camelia Szuhanek Eleonora Schiller

Adelina Grigore Adelina Popa

A GUIDE TO ORTHODONTICS

Editura „Victor Babeş”

Timişoara, 2019

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Editura „Victor Babeş”

Piaţa Eftimie Murgu 2, cam. 316, 300041 Timişoara Tel./ Fax 0256 495 210

e-mail: [email protected] www.umft.ro/editura

Director general: Prof. univ. dr. Dan V. Poenaru Director: Prof. univ. dr. Andrei Motoc

Colecţia: GHIDURI ŞI ÎNDRUMĂTOARE DE LABORATOR Coordonator colecţie: Conf. univ. dr. Adrian Vlad Referent ştiinţific: Prof. univ. dr. Elisabeta Bratu

Indicativ CNCSIS: 324

© 2019

Toate drepturile asupra acestei ediţii sunt rezervate.

Reproducerea parţială sau integrală a textului, pe orice suport, fără acordul scris al autorilor este interzisă şi se va sancţiona conform legilor în vigoare.

ISBN 978-606-786-126-6

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TABLE OF CONTENTS

PREFACE ... 7

1. PATIENT HISTORY AND THE GENERAL CLINICAL ASSESSMENT... 8

2. FACIAL AND POSTURAL ASSESSMENTS ...11

3. ASSESSMENT OF THE MUSCLES AND OF THE FUNCTIONS OF THE DENTO-MAXILLARY APPARATUS (DMA) ...16

4. EXAMINING THE TEMPOROMANDIBULAR JOINT (TMJ) ...23

5. THE INTRAORAL EXAMINATION ...24

6. DENTAL IMPRESSION IN ORTHODONTICS ...26

7. EXAMINING THE STUDY MODEL ...29

Examining the model in the three planes ... 30

Pont’s Analysis ... 33

Tanaka and Johnston Analysis ... 35

Perimetry ... 36

Bolton Analysis ... 37

8. CEPHALOMETRIC RADIOGRAPHY ...38

9. DIGITAL CEPHALOMETRIC ANALYSIS ...64

10. DIAGNOSIS RESULTS ...69

11. CBCT IMAGING IN ORTHODONTICS ...71

12. REMOVABLE APPLIANCES ...75

13. FUNCTIONAL APPLIANCES...85

14. FIXED INTERCEPTION APPLIANCES ...96

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15. OTHER FIXED APLIANCES USED IN ORTHODONTICS: EXPANSION AND

DISTALIZATION APPLIANCES ...99

16. EXTRAORAL FUNCTIONAL APPLIANCES ... 101

17. VACUUM-FORMED ORTHODONTIC APPLIANCES... 102

18. FIXED ORTHODONTIC APPLIANCES ... 109

19. HANDLING ORTHODONTIC EMERGENCIES IN THE DENTAL OFFICE ... 114

BIBLIOGRAPHY ... 116

ANNEXES ... 118

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PREFACE

The present guide to orthodontics has been written and thought of as a support for fifth year students at the Faculty of Dental Medicine within Victor Babeș University of Medicine and Pharmacy Timișoara, but it can also be used by the residents in the first year at the Orthodontics and Dentofacial Orthopedics program.

The guide comprises fundamental notions rendered schematically, with the help of data and pictures, which aim at supporting students to easily assimilate the subject studied during medical internship.

The first part of the book discusses notions regarding clinical and paraclinical investigations of the orthodontic patient. Besides standard investigations, notions about digital cephalometric analysis or CBCT investigation are also described.

The second part is devoted to the types of appliances used in intercepting and treating dento-maxillary anomalies. A wider part is devoted to mobile and mobilisable appliances, as well as to the description of the concepts and the way of manufacturing of some types of appliances that are used more frequently in treating dento-maxillary anomalies in children. In what follows, vacuum-formed appliances, as well as fixed dental appliances, together with their components, are briefly described. As the development of fixed orthodontic techniques has been remarkable lately, we believed it was advisable to add some simple manoeuvres that the dentist can carry out in some cases of orthodontic emergency.

We hope that this guide will come in handy for students and young doctors and will help them synthesize the basic principles of orthodontic diagnosis and the main types of appliances used in treating dento-maxillary anomalies.

The authors Timişoara, 2019

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1. PATIENT HISTORY AND THE GENERAL CLINICAL ASSESSMENT

Patient history form must contain the following information:

- civil data of the patient

- the environment of origin: urban or rural - patient’s complaint and motivation - family medical history

- general personal medical history - dental history

Patient’s complaint and motivation can be linked to aesthetic aspects or to functional disorders (breathing, mastication, joint pains).

General medical history

The questions addressed to the mother refer to personal medical history and to family medical history:

- if the mother suffers from a chronic disease

- the age she got pregnant at – in elder mothers, the child’s tooth eruption is delayed

- if she had pregnancy disorders or other troubles during pregnancy – all the troubles and disorders of the mother during pregnancy affect temporary teeth, as the forming and development of temporary teeth buds takes place during this period

- if the baby was born on time – premature children suffer from delayed tooth eruption and enamel defects

- baby’s weight at birth – light weight can be accompanied by delayed tooth eruption and enamel defects

- if nursing was natural or artificial; it is well known that the baby’s mandibular moves and tongue position during breastfeeding are beneficial for a harmonious development of the dento-maxillary apparatus

- what disorders the baby suffered since birth until 7 years of age – at this age, the intraosseous formation of permanent teeth is complete, except for the wisdom teeth; all the infectious diseases, vitamin D or iron deficiency, celiac disease (gluten intolerance), endocrine diseases (hypo- or hyperfunctions of the thyroid or of the parathyroids) and other disorders may interfere with the formation and development of permanent teeth (enamel hypoplasia and hypomineralization)

- if family members have suffered from orthodontic problems: crowding /spacing of teeth, skeletal malocclusion

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This last question is important, as heredity plays a great role. At the level of the stomatognathic system, the following traits are hereditary: tooth and jaw shape and size, tooth structure (enamel), implantation (diastema vera), hypodontia, hyperdontia, maxillary or mandibular prognathism and retrognathism, overbite. Although inherited anomalies represent just 3-10% of the total dento-maxillary anomalies, they must be approached therapeutically as soon as possible, because they affect facial growth and have the greatest potential for relapse after the orthodontic treatment.

We can also talk about crossed heredity, when the child inherits the jaws from one parent and the teeth from the other parent, but they are not „compatible” although they have normal shape and size. This leads to dento-maxillary disharmony, usually implying crowding of teeth. [1]

Child’s dental history

It is important to find out if the child suffered from delated eruption or early loss of primary teeth; early loss of primary lateral teeth have the most negative consequences, as it disturbs the permanent teeth eruption pattern [2]

Traumatic injury to the primary dentition can affect the development of permanent teeth, from enamel defects to the impaction or crown / crown and root dilaceration in permanent teeth.

The most frequent injuries of primary dentition are intrusion and luxation; they have the most harmful effects over the formation and development of permanent teeth buds.

TMJ (temporomandibular joint) injury in small children can lead to cracks of mandibular collum, which, if not discovered at the right time, will lead to an asymmetric mandibular growth (the mandibular condyle is active until 15 years of age)

Bad oral habits (finger sucking, lower lip sucking or biting skin around fingernails) can have repercussions over dental occlusion.

The mother must be asked if the child has ever had an orthodontic appliance, and if yes, what type and if he used to wear it. If he used to wear it constantly, and went for an activation regularly, what the results were. In the adult patient, we ask if (s)he has ever had a fixed orthodontic appliance, if (s)he used to wear a retainer and for how long.

The general clinical assessment

One must notice the general development of the patient. The weight and height of the child must be correlated with the dental eruption and dental age. Puberty is an extremely important period in the development of a child. During this period, a burst of tridimensional growth of the jaws takes place. (the maxillary grows tridimensionally with about 3 mm and the mandible with 8 mm); for some anomalies, such as mandibular retrognathism, this can be beneficial, while for others, such as mandibular prognathism, it can represent a great disadvantage.

Patient’s posture is another factor which may indicate a possible orthodontic problem.

Multiple studies show that there are some correlations between the posture of one’s head and cervical spine and dento-maxillary anomalies [3]; child’s posture during sleep can also lead to orthodontic anomalies (hyperextension of the head may lead to mandibular retrognathism, increased flexion due to sleeping on a high-loft pillow may lead to mandibular prognathism).

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Fig. 1. Patient’s posture during sleep can influence the occlusal relationship

Evaluating child’s behaviour is another important aspect in orthodontics. Patients’

motivation strongly influences the degree of success of the orthodontic treatment.

Patient’s approval

Before pursuing extraoral and intraoral examinations, the mother or the patient must sign the agreement for the orthodontic treatment. This is an extremely important forensic document. The patients who show up at the Orthodontics Clinic must sign an agreement to partake of medical training.

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2. FACIAL AND POSTURAL ASSESSMENTS

Human face shapes and body types are varied, but not all of them have a pathological significance. It is important to mention that longilin asthenic (dolichocephalic, ectomorph) persons display a tendency for narrow maxillary arch transversally speaking, whose consequences are malocclusion or crowding of teeth.

Constitution types

Sheldon’s classification:

- ectomorphic: Tall and thin physique - mesomorphic: Average physique

- endomorphic: Short and obese physique

Fig. 1. Constitution types: ectomorphic, mesomorphic, endomorphic (dolichocephalic, mesocephalic, brachycephalic)

Face shapes

Face and skull shapes always match constitution types.

- brachycephalic (brakhys = short) – the development in a transversal manner prevails, the face is of a round shape, the palate is horizontal, the incisors are of a square shape.

- dolichocephalic (long) – the development in a vertical manner prevails, the face is narrow, the arcades are narrow, the palate is deep, they have long crowns and suffer from malocclusion

- mesocephalic – the ratio is maintained

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The cephalic index

- is the ratio between the maximum length and the maximum width of the skull - it can be calculated by using the following formula (fig. 2):

The length of the skull (Gl-Op)x100/the width of the skull (Eu-Eu)

*Gl - the glabella (the smooth prominence between the eyebrows)

*Op –the opisthocranion (the posteriormost point in the midsagittal plane of the occiput)

*Eu – euryon (the point of maximum width of the head at the level of the parietal region) The value of this ratio indicates the following skull shapes:

< 75,9 = dolichocephalic 76-80,9 = mesocephalic

>81-85,4 = brachycephalic

>85,5 = hyperbrachycephalic

Fig. 2. Calculating the cephalic index

The total facial index

- is calculated by using the following formula:

Oph-Gn x 100/ Z-Z (the bizygomatic diameter) - considering the value of this ratio, there are three facial types:

>104 leptoprosopic 97-104 mesoprosopic

< 97 euryprosopic

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Fig. 3. Calculating the total facial index Head mobility

The patient is asked to make various head movements (flexion, extension, rotation). These movements allow the evaluation of head and cervical spine mobility. If there are any limitations, the causes must be identified, as neck muscles are highly related to facial muscles.

Fig. 4. Assessing head and neck mobility

Facial symmetry

Facial symmetry is assessed by placing the patient in the correct position considering the Frankfort horizontal line and then comparing the left side of the facies with the right side; chin deviation as compared to the median line of the face is the most frequent.

Vertical assessment – the facial thirds

For examination purposes the face is divided into thirds:

- the upper third (Trichion-Ophrion) - the middle third (Ophrion-Subnasale) - the lower third (Subnasale-Gnathion)

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Fig. 5. Face sections

Assessing the thirds: the middle third is usually 5 to 10 mm smaller than the lower third. If the lower third is increased, this represents an important element in diagnosing vertical dento- maxillary anomalies, an open bite of rachitic origin respectively. If the lower third is decreased, this is a clue for deep overbite [13].

Profile facial view assessment

The profile facial view can offer information about the position of maxillary bone bases in relation to the skull. It can be straight (normal), convex (specific to Class II malocclusion) or concave (specific to Class III malocclusion), thus providing information about dento-maxillary anomalies in the sagittal plane.

Fig. 6. Types of profile facial view (from left to right ): convex, straight and concave

Examining the lips

Thick lips are usually hypotonic, while thin lips are hypertonic; dry and chapped lips are a sign of mouth breathing [13].

The assessment of lips position is made in relation to the profile and it can be:

- retruded (specific to the concave profile) - normal/straight (specific to the straight profile) - protruded (specific to the convex profile)

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Fig. 7. Assessing lips position

Normally, the lips contact each other during rest position = lip competence; if they do not contact each other, it is called lip incompetency and it is a sign of mouth breathing.

Fig. 8. The influence of lip position over frontal occlusal relationships

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3. ASSESSMENT OF THE MUSCLES AND OF THE FUNCTIONS OF THE DENTO-MAXILLARY APPARATUS (DMA)

Assessment of the muscles

Assessing the muscles implies either palpation or testing their tonicity by means of various techniques (hypotonia, normal muscle tone, hypertonia).

Palpation techniques

- pincer palpation - with the help of the index finger and the thumb - flat palpation – perpendicular to muscle fibers

- palpation by plucking

- triggering palpation – by palpating a muscle, there is the possibility of triggering a local or a radiating pain

Other techniques of assessing muscular tone:

In order to establish the muscle tone, the examiner asks the patient to make a movement which implies the use of the examinated muscle. The examiner must oppose to that movement with the help of his/her fingers and (s)he must feel some resistance. This technique is subjective, but it is more accurate than the intraoral palpation of some muscle groups. If the patient offers no resistance, the muscle is considered hypotonic. If the resistance is very high, the muscle is considered hypertonic. All the other situations are considered normal, just as the muscular tone.

Fig. 1. The importance of the insertion of mentonis muscle in the appearance of some orthodontic anomalies (class II/1 or II/2)

Temporal muscles elevate the mandible and are the most important postural muscles and the most sensitive to occlusal interferences at the same time. They can be palpated externally with both hands at the temple level.

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Masseter muscles elevates the mandible and helps mandible propulsion and retropropulsion.

External palpation is made from the zygomatic arch and past the goniac angle. Internal palpation is made by inserting one finger in the oral vestibule (M2,M3) in the superior part up to the zygoma.

These muscles are sensitive in bruxism.

Fig. 2. Extraoral palpation of elevator muscles (flat palpation)

(External) lateral pterygoid muscle

It is the muscle most talked about in specialized literature: some consider it an elevator muscle, some, a depressing muscle or a muscle involved in lateral movements. Palpation is made by inserting one finger in the oral vestibule at the M3 level and by pushing posteriorly and medially behind the tuberosity.

(Internal) medial pterygoid muscle

Together with the masseter, it forms a „strap” for elevating the mandible; it also contributes to laterality and propulsion movements. Extraoral palpation is made anterior to the goniac angle, while intraoral palpation is made posterior to the retromolar trigone (internal part of the mandible).

Tongue muscles, the orbicularis and the buccinator

- tonicity is assessed by opposing the moves which imply these muscles

- the tongue is made up of 17 muscles: 8 paired and 1 single, so its force is considerable. Any disfunctions contribute to a number of malocclusions.

- for the buccinator muscle, the patient is asked to keep the air inside the oral cavity, while the examiner applies some pressure at cheek level (the air must not be let out)

- for the orbicularis muscle, the patient is asked to purse his/her lips, while the examiner pulls both commissures.

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Fig. 3. The influence of lips and tongue muscles on dental occlusion Alar muscles

- tonicity is assessed during deep inspiration and expiration

- for safety, one can use the mirror test and then evaluate fogged up areas

Fig. 4: Orofacial muscles

The functions of dento-maxillary apparatus

Respiratory function

The symmetry and contraction of nasalis muscle are assessed.

By compressing the nostrils and assessing their rapidity of regaining normal shape, one can notice if the patient is a mouth breather; slow shape regain is a sign of mouth breathing.

Certain patients often suffer from asymmetric or flat nostrils, which may be a sign of mouth breathing. In orthodontics, this is called mouth breathing syndrome and it has the following features: deep palate, upper front teeth protrusion, thin and hypertonic upper lip, mandibular retrognathism, convex profile, that is class II/1 Angle (the American school); in fact, these changes

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in the sagittal plane are consequences of the changes in the transverse plane. Reducing nasal breathing leads to sinus and maxillary hypoplasia respectively, and the pressure of face muscles leads to maxillary transverse constriction (narrow maxillary arch – German school). As teeth no longer fit into the arch, they become protruded and the mandible retrudes in order to make stable contact in the posterior part.

- the patient is asked to inhale deeply – if (s)he inhales through the mouth, (s)he is considered a mouth breather

- nostrils compression test – if nostrils regain their shape slowly after compression, the patient is a mouth breather

- mirror test – the patient is asked to exhale through the nose; if the mirror does not fog up (negative test), the patient is a mouth breather

- all patients who suffer from mouth breathing must be redirected to an ENT assessment (in order to remove any rhinopharyngeal obstacles) [4]

Speech

- any speech defects may be a sign of orthodontic anomalies

- the patient is asked to spell dental, labial and sibilant phonemes; the tongue does not normally lean on teeth during pronunciation

Deglutition

Adult’s deglutition is produced by placing the tongue in the anterior area of the palate; at birth, deglutition is produced by placing the tongue between the edentulous dental arches. This is considered normal up to 2-3 years of age, and by some authors, up to 7 years of age; if it exceeds 7 years of age, it is considered pathological, it is called infantile swallowing and it most often causes open bite.

- a mirror or spatula is placed at the level of the lower lip and the patient is asked to perform swallowing

- patients with infantile swallowing do not display muscular contractions at the level of the temporal muscle; by palpating this muscle during deglutition, one can notice if there is a normal swallowing pattern [2]

Fig. 5. Infantile and adult swallowing patterns (left to right)

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Fig. 6. Infantile swallowing

An infantile swallowing pattern can cause open bite also in the lateral area (lateral open bite).

Fig. 7. Tongue interposition in the lateral area

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Fig. 8. Open bite (by tongue interposition between dental arches during deglutition)

Mastication

- the patient is asked to chew some gum; the examiner may detect unilateral mastication

- the patients who do not display dental attrition display slower mastication dynamics and prefer soft foods

Facial esthetics

Patients with dento-maxillary anomalies display esthetic changes on both frontal norma and lateral norma: deep occlusion is accompanied by reduced lower third of the face, protruded chin, deep labiomental fold (aged aspect); skeletal open bite is accompanied by increased lower third of the face with a ,,long face syndrome” aspect; bird-like convex profile (maxillary protrusion or mandibular retrusion), concave profile (mandibular protrusion) with an unaesthetic and aggressive aspect etc.

Notions of occlusiology in orthodontics

The analysis of dental occlusion in its dynamics implies the highlight of premature contacts and of occlusal interferences on the working/non-working side. In order to have a more accurate evidence of the interferences and of the premature contacts, the patient must be guided into centric relation. Recording with the facial arch and mounting the models on the articulator ensure an accurate occlusal analysis and are of a major importance in patients with temporomandibular dysfunction.

Protrusive movement

- from the maximum intercuspation position, the doctor guides the mandible until the incisors get in the edge-to-edge position

- by using articulating paper/occlusion spray, one marks the contacts

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- there must be no contact between teeth in the posterior area (if there is the case, one writes down the non-working side interferences in the record) and the guidance must include at least the two upper incisors

- propulsive non-working interferences usually appear on the distal slope of the internal side, at the level of the molars

- propulsive working interferences usually appear at the level of the incisal margin

Lateral movement

- starting from the maximum intercuspation position the doctor guides the mandible into left/right laterality

- one must mention if there is canine guidance or group function (the area involved in the guidance must be mentioned too)

- there must be no contact between teeth at the level of the non-working side (if there is the case, one writes down the non-working side interferences in the record)

The Curve of Spee (in the sagittal plane)

- ideally, the maximum depth of the curve is 3 mm; a deep sagittal curve is a sign of lack of space;

- Von Spee’s curve must be convex at the level of the superior dental arch and concave at the level of the mandible

The Curve of Wilson (in the transverse plane)

- it is the curve defined by the inclination of vestibular and lingual cusps at the level of the molars - this curve allows food to remain at the level of the occlusal table during mastication

- this curve usually has a superior concavity

Fig. 9. Occlusal curves – Von Spee and Wilson (from left to right)

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4. EXAMINING THE TEMPOROMANDIBULAR JOINT (TMJ)

One must check the amplitude of mouth opening (it is measured in mm/cm – normal values 40-50 mm).

One palpates the condyles and assesses their symmetry as well as the condyle excursion.

The assessment of the condyles is made by inserting the thumb in the external auditory canal and the index finger in the pretragian area; one assesses if the condyle excursion is normal, limited or blocked.

One also assesses if there are deviations at the level of the chin during mouth opening or closing, joint sounds (popping or cracking sounds, crepitus) as well as the moment they can be heard (during mouth opening or closing).

TMJ dysfunctions have multiple causes, but the ones linked to orthodontics are usually distalizations (mandibular retrusion), mezializations (mandibular protrusion) when the condyles are in distal or mezial joint blockage at the level of the glenoid fossa, as well as posterior occlusal interferences.

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5. THE INTRAORAL EXAMINATION

Examining the mucous membrane and the periodontium

- examining the frenulum – by mentioning the insertion type (low, medium, high) and its thickness (thin, medium, thick)

- a thick frenulum with a low insertion may cause diastema

- a short lingual frenulum causes a low position of the tongue which may lead to mandibular protrusion (due to excessive pressure at the level of the inferior teeth) or speech disorders

- one must mention if there are pathological changes at the level of the oral mucosa (oral manifestations of contagious diseases)

- the colour of the gums: pale pink is the normal colour; if it is pathological, it can be red, which is a sign of plaque induced gingivitis (due to poor hygiene) or of puberty gingivitis, or it can be whitish, which is a sign of anemia

- the texture of the gums: the normal texture has an orange zest aspect; if it is red and shiny, it is a sign of inflammation

- the outline of the gums: the normal outline – gum attachment and normal papilla; during inflammation, the outline is uneven and the interdental papilla is detached

- the degree of hygiene, the presence of dental plaque or of periodontal pockets (in children, these pockets are false, as the gingival proliferation is directed towards the incisor)

- the presence at gum level of any abscess or fistula (frequent complications in temporary dentition) - examining the palate – a deep palate is associated with insufficient development of the maxilla in the transverse plane; the presence of a developed torus palatinus denotes a precocious ossification of the medio-palatine suture (the growing center of the maxilla in the transverse plane, which is active up to 21 years of age approximately); in these patients maxillar expansion is difficult to obtain [13].

- examining the tongue by mentioning its dimension (microglossia, normal aspect, macroglossia), its position (low or high), and if the tongue has a candidal aspect or if it is a geographical tongue.

Dental examination

Besides the dental age and early loss of temporary teeth, orthodontics insists on the following aspects:

- number of teeth: hypodontia or hyperdontia

- dental malposition: - twisted teeth (distal or mezial rotations) - tooth versions (distal version, mesioversion)

- labial, tongue-directed or palatal positioning of teeth - ectopic eruption

- morphology or size variations – for instance: small lateral incisor, macrodontia of a single tooth, taurodontism, „double teeth” = fusion or gemination

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- shape of the arches: in permanent dentition, the ideal is maxillar parable and mandibular ellipse/semiellipse; the pathological shapes are U, V (narrow maxillary), omega-shaped (sign of constriction in the premolar area), trapeze-shaped (upper incisors in straight line), M, W. In temporary dentition, the arches are displayed in a semicircular shape; any divergence from this shape is considered pathological.

Dental aesthetic analysis

Patient’s intraoral photos can offer addition information regarding the coincidence of dental midline, the value of the overjet, the height of the gingival zenith, the value of the golden ratio.

Achieving the golden ratio at teeth level is about preserving the 1,68-1-0,68 ratio between the height of the central incisor, the width of the lateral incisor and the mesial half of the canine.

The gingival zenith of the central incisor must be at the same level with the zenith of the canine and 0.5 mm more apical as compared to the zenith of the lateral incisor.

Fig. 1. Dental aesthetic analysis (the height of the gingival zenith, the assessment of the dental midlines)

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6. DENTAL IMPRESSION IN ORTHODONTICS

A dental impression allows the execution of the study model and /or of the working model.

Based on the study model, one can better examine the palate, any dental malpositions, the occlusion in the three planes, and one can take a number of measurements. These measurements are essential for a correct diagnosis.

Choosing the trays

The trays can either be the stock trays used in dentistry or the special types used in orthodontics (for instance, having the right shape for a protruded narrow maxillary); they must exceed the arch by 0.5 cm buccaly and they must be long enough to include the last existing molar on the arch.

The chosen material for the dental impression is the alginate. It offers several major advantages:

- it sets quickly (1 minute approximately), which is very useful, mainly when dealing whin non- cooperative patients/ children

- new materials are of great fidelity - it is easy to mix

- there are various types with various flavours available (mint, tropical fruits, etc.) - it is cheap

Fig. 1. Required materials for a dental impression

Required equipment

- plastic bowl and spatula (plastic/metal) - water

- alginate and dispenser

- plastic impression trays equipped with retentions

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The mixing time is short (45 s - 1 min.) and the setting time may vary depending on water temperature. The water must be warm; if it is too cold (in winter), the material becomes very fluid and it leaks out of the tray; if the water is too hot, the material will set too fast. The errors that may appear are related mainly to the failure in maintaining the proportions between the powder and the water (they must be in an equal amount), to incorrect mixing, to wrong positioning of the impression tray (decentration, extremely posterior or anterior positioning, excessive or insufficient pressure), or to the appearance of air bubbles due to mixing or to saliva [1].

Fig. 2. Alginate dental impression Patient’s and doctor’s postures during impression

The patient must be relaxed, having a vertical trunk posture, and (s)he will hold the tray (for the saliva, surplus material, or possible regurgitation - in children).

Before the impression, one must do some exercises using the spoon in the oral cavity, in order to accustom the child to the impression and to breath control.

One must always begin the dental impression with the lower arch so that the patient gets accustomed to it and so as to avoid the appearance of queasiness, as it may be the case for the maxillary. The doctor must stay in front of the patient and must press the tray in the lateral areas of the arches using his index and middle finger. (S)he supports the mandible using the thumbs.

For the upper arch, the doctor must stay in front of the patient and (s)he must insert the material through a commissure (which is pulled using his fingers) using the tray. Then, (s)he exerts some pressure from the posterior part to the anterior one. The patient bends forward a litte bit and the doctor gets behind him, maintaining the tray into place by using his middle finger and his ring finger, and the material that overflows buccaly is put back in the front area of the oral vestibule by using the index fingers.

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Fig. 3. The impression stage (the mandibular arch)

Requirements for a correct dental impression

A correct impression must render all the important details of the imprinted area [13]:

- whole dental arches - vestibular depth

- the median raphe and the palatal rugae - the A-line

- the molar tubercle and the molar trigone

- the lingual frenulum, the labial frenulum and the vestibular flanges

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7. EXAMINING THE STUDY MODEL

The study model is made based on the impression. It is made of white, high strength impression plaster (type IV plaster is preferred).

Fig. 4. Pouring/Casting the plaster model

The study model is extremely useful in providing the correct diagnosis. The elements that must be analyzed in order to establish a correct diagnosis are the following:

- the shape of the dental arches

- the shape, the depth and the symmetry of the palate - the type of the palatal rugae and of the incisive papilla

- the insertion and thickness of the frenulums and of the flanges - dental malpositions/ hyperdontia/ crowding of teeth/ gaps - teeth shape (macrodontia/microdontia) – using Bolton analysis - size of the arches in the transverse plane – using Pont’s analysis - lack of space/ excess of space

- the analysis in the three planes.

The shape of the arches

Ideally, the shape of the maxillar arch is that of a parable and the shape of the mandibular arch is that of an ellipse. In temporary dentition, the shape of the arch is that of a semicircle. In patients with orthodontic anomalies, the shape of the arches no longer follows the normal pattern (figure 3), and they are pathological (U, V, M, trapeze-shaped, omega-shaped, atypical etc.) [6]. If the patient has missing teeth, one must mention that the arch is discontinuous.

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Fig. 5. Pathological shapes of the dental arch: M, omega-shaped, atypical, V, trapeze-shaped.

Examining the model in the three planes

The analysis of the models is made in the three reference planes:

1. The sagittal plane

Front area – the value of the space of inocclusion (OJ-overjet) - normal = 1,5-2 mm

- high > 3 mm = protrusion - absent = 0 mm = retrusion - negative = negative overjet

Fig. 6. Increased overjet (OJ)

Cuspid ratio – neutral ratio: the mesial part of the canine coincides with the distal part of the inferior canine; pathological: distalized or mesialized.

Lateral area – the molars – neutral ratio: the mesio-vestibular cusp of the maxillary first molar coincides with the first vestibular groove of the mandibular first molar (fig. 7); pathological:

distalized or mesialized.

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Fig. 7. Neutral ratio at the level of the canine and of the molar

2. The transverse plane The frontal area

- the dental midlines must coincide with one another and also with the median line of the face - pathological versions: lateral deviations of the dental midlines may be caused by dental problems (dental malpositions) or by mandibular problems, when they are accompanied by crossbite on the deviant part (functional lateral deviation); when there are anatomical mandibular changes, we talk about laterognathia.

Fig. 8. Lateral deviation of the interincisive line Lateral area

- the maxillary arch must circumscribe the mandibular arch - pathological versions:

- inverted lateral occlusion (crossbite)

- lingualized occlusion (when the mandibular lateral teeth are in lingual version)

Fig. 9. Crossbite at the level of tooth no. 13 and tooth no. 43

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Fig. 10. Crossbite from teeth no. 23 to 26

3. The vertical plane

Frontal area – Overbite (OB) - the normal value is 1/3 - pathological versions:

- vertical malocclusion: open bite

- overlap greater than 1/3 = 2/3 or 1/1 (deep bite) Lateral area

- each tooth has 2 antagonists, except for the mandibular central incisors and maxillary third molars which only have one antagonist.

- pathological versions: overbite/ open bite

After the analysis of the model in the three planes, one diagnoses the dento-maxillar anomaly. The international classification is the one made by Angle (classification made depending on the changes in the sagittal plane; M1 is the reference point):

Class I – neutrocclusion: the occlusion for the M1 is normal, but the other teeth may have problems like: crowding, open bite, proalveoly, etc.

Class II – distocclusion for the M1 and 2 subtypes for the frontal area:

Class II Division 1 - the anterior teeth are protruded Class II Division 2 – the anterior teeth are retruded

Class III - mesiocclusion for the M1 and anterior negative overjet.

For an accurate diagnosis, after the analysis of the study model in the three planes, one carries out several measurements: Pont’s analysis, Bolton analysis, perimetry, Tanaka and Johnston analysis (in the case of mixed dentition), occlusogram etc. These measurements allow the dentist to establish the space deficit and direct us towards possible treatment options. The analysis of the study model must be correlated with the intraoral examination and the cephalometric measurements.

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Pont’s Analysis

In the orthodontic practice, besides the analysis of the model in the three planes, there are a number of parameters which are used in order to obtain a complete diagnosis and to take the right therapeutical decision. The applicability of Pont’s analysis refers to the cases which require transverse expansion. Pont’s index indicates the development of the arches in the transverse plane [7].

In order to determine Pont’s index, one measures (by using a ruler/ some other device) the distance (width) between the upper and lower molars and the distance (width) between the upper and lower premolars on the study model. These values will be compared to a value that is established with the help of a standard formula. If there are differences between the established values and the values obtained through measurement, it means that there are some anomalies.

Depending on the identified anomaly, one chooses the correct therapeutic solution.

The measurement method for the upper arch is the following:

- the interpremolar distance (width) for the upper arch is measured from the center of the occlusal grooves of the maxillary first premolars (fig. 1)

Fig. 1. Measuring the interpremolar width of the upper arch

- the intermolar distance for the upper arch is measured from the center of the occlusal grooves of the maxillary first molars (fig. 2)

Fig. 2. Measuring the intermolar width of the upper arch

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The measurement method for the lower arch is the following:

- the premolar diameter of the lower arch is measured at the level of the vestibular contact point of the mandibular premolars (fig. 3)

Fig. 3. Measuring the premolar diameter for the lower arch

- the molar diameter of the lower arch is measured at the level of the tip of the mesiovestibular cusps of the mandibular first molar (fig. 4)

Fig. 4. Measuring the intermolar width of the lower arch

The values obtained through measurement are written down in patient’s medical record.

These values are compared to the values established with the help of the formulas.

Employed formulas (SI = sum of the incisal widths of incisors):

- for the premolar diameter: PD = SI x 100/ 80 - for the molar diameter: MD = SI x 100/64

In the formula, the value employed for both arches is the sum of the upper incisal width of incisors.

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SI is the sum of the mesio-distal diameters of the four maxillary incisors. The normal values are between 28-35 mm; any value under 28 mm is absolute microdontia, while any value that is over 35 mm is absolute macrodontia.

If the values established through measurements are lower than the values established through calculation, Pont’s index shows a narrowing of the arches (either at premolar level or at molar level, depending on the case). In the opposite situation, the index shows an excessive width of the arches.

Any differences from Pont’s index may be assessed as follows:

+/- 2 mm – normal

+/- 2-4 mm – slight deviation +/- 4-10 mm – significant deviation +/- 10 mm – major deviation

There are some situations when this index is not applicable:

- when the premolars/molars are missing or they have an incomplete/ ectopic eruption, Pont’s index cannot be determined

- when the sum of the incisal widths of incisors does not belong to the standard range (28-35 mm) - it cannot be applied in the case of mixed dentition

*Pont’s index refers to brachycephalic people from southern France, so one should keep in mind that this analysis may not be accurate and it should not be seen as completely reliable.

Tanaka and Johnston Analysis

This analysis is useful in the case of mixed dentition, in order to foresee the space that is needed for further alignment of the canine, first premolar and second premolar in permanent dentition [2].

The formula is applied to one hemiarch. For both arches, the value taken into consideration is the sum of the lower SI (sum of the incisal widths of incisors).

- upper arch – the room needed for the alignment of teeth 3,4,5 = the lower SI/2 + 11 mm - lower arch – the room needed for the alignment of teeth 3,4,5 = the lower SI/2 + 10.5 mm

The value obtained through calculation is compared to the value obtained through measurements made on the study model, between the distal side of the lateral incisor and the mesial side of the first molar.

If the value obtained through measurement is lower than the one obtained through calculation, the analysis reveals that there is not enough space for permanent tooth eruption (space deficit).

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Tanaka & Johnston Half of the mesio-distal

distance between the four mandibular incisors

+10.5 mm = C+PM1+PM2 for one quadrant

for the mandible

+ 11 mm = C+PM1+PM2 for one quadrant

for the maxillary

Perimetry

Perimetry is an indicator for space deficit/space excess. This measurement method offers information about the necessary space for permanent teeth alignment.

With the help of a divider/ any other device, one measures the mesio-distal diameter of each tooth (fig. 1) which is situated in a mesial position as compared to the first permanent molar. By making the sum of these diameters, one obtains the dental perimeter of that arch. This value is compared to the alveolar perimeter. The difference between the two may be a sign of space deficit or of space excess.

Fig. 1. Measuring the mesio-distal diameter of the mandibular second molar (for the calculation of the dental perimeter)

The alveolar perimeter is measured between the mesial sides of the first permanent molars, with the help of a small string. Then the string is measured with a ruler and the value is written down in the medical record of the patient. (fig. 2).

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Fig. 2. The alveolar perimeter

Bolton Analysis

Bolton analysis helps in discovering if there is a difference in volume between the teeth on the upper arch and the teeth on the lower arch this measurement method is necessary for establishing a diagnosis and an appropriate treatment plan, as well as for discovering if there is a need for interproximal reduction (stripping).

There are two versions of this analysis - the Anterior Analysis and the Overall Analysis. If there are missing teeth on the lateral side, the Anterior Analysis is the only one that can be carried out.

Calculation method – Overall Analysis

- one measures and makes the sum of the mesio-distal diameters of the 12 lower teeth and the sum of the mesio-distal diameters of the 12 upper teeth (up to the second molar)

- the values obtained are written down in patient’s medical record

- one calculates the ratio between the two values and the sum is multiplied by 100 The obtained percentage indicates the following:

- the normal value is 91.3 %

- any value that exceeds this percentage is a sign of excessive width of the lower teeth - any value that is lower than this percentage is a sign of excessive width of the upper teeth

Depending on the values obtained, interproximal reduction will be performed either on the upper arch or on the lower arch.

Calculation method – Anterior Analysis

- the calculation formula stays the same, but it only contains the sum of the mesio-distal diameters of the six front teeth (up to the first premolar)

- the sum of the mesio-distal diameters of the six lower teeth/ the sum of the mesio-distal diameters of the six upper teeth x 100

- the normal value is 77,2 %.

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8. CEPHALOMETRIC RADIOGRAPHY

Cephalometric radiography is employed in the orthodontic diagnosis in order to examine the dental and facial relationships of the patient before the treatment, the changes that appear during the treatment as well as for the final assessment after the orthodontic treatment.

The orthodontic diagnosis is not reached based on cephalometry alone, as it is complementary to the process of establishing the diagnosis.

Uses of the cephalometric analysis:

 Diagnosis purposes, in order to establish whether a malocclusion is due to skeletal or dental causes

 Allows the clinician to know exactly to what extent the patient deviates from the normal values.

 Monitoring the changes that appear during growth or during treatment.

 VTO (Visualized Treatment Objective)

A cephalometric analysis implies the precise localization of several points which represent intersections, lines or overlappings of the anatomical structures as a result of the radiological projection, and the assessment of the ratios between these cephalometric points and landmarks.

Several cephalometric analyses have been developped with the purpose of establishing criteria and standards that could define an ideal of facial proportions. Based on the linear and angular measurements, one can establish the vertical and sagittal positions of the maxillaries as compared to the base of the skull, as well the position between themselves, their relationship with the dental structures, the interdental relationships and the assessment of soft tissues.

Methods of cephalometric analysis:

1. The manual method – transfer paper is superposed on the radiograph and the outline of the soft and hard tissues is traced

2. The digital method – there are many cephalometric softwares, among which the most popular are: Romexis Planmeca, AudaxCeph etc.

1. Employed landmarks in the analysis of the teleradiography

Cephalometric landmarks

1.1. Bony landmarks

NASION (N) – most anterior point on the frontonasal suture in the mid-sagittal plane; it corresponds to the nasal root.

– anatomic, bony, unilateral landmark

Localization: one traces the outline of the cortical plate of the frontal bone, the nasal bone and the frontonasal suture. Nasion is the meeting point of the three;

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Applicability: Nasion is used as a reference point in drawing the angles and planes which assess:

 The relationship between the maxilla and the cranial base: ANS angle

 The relationship between the mandible and the cranial base: SNB angle

 The relationship between the maxilla, the mandible and the cranial base: ANB angle

 The position of the maxillary incisors: the angle between NA and the axis of the maxillary incisor and the linear distance NA - maxillary incisor

 The position of the mandibular incisors: the angle between NB and the axis of the mandibular incisor and the linear distance NB -mandibular incisor

 The angle of sella turcica: N-S-Ar

Fig. 1.1. Nasion – radiographic appearance

Fig. 1.2. Nasion – graphic illustration (Audax)

SELLA (S) – the midpoint of sella turcica – anatomic, bony, unilateral landmark

Localization: the sella turcica is located in the upper body of the sphenoid bone and it is bounded by the anterior and posterior clinoid processes; one traces the outline of the clinoid processes and the lower margin of the fossa. The geometric center of the sella turcica is the Sella.

Applicability: it is used as a reference point in the construction of the angles and planes which assess:

 The relationship between the maxilla and the cranial base: ANS angle

 The relationship between the mandible and the cranial base: SNB angle

 The angle of sella turcica: N-S-Ar

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Fig. 1.3. Sella – radiographic appearance

Fig. 1.4. Sella – graphic illustration (Audax)

BASION (Ba) – the most inferior point of the anterior margin of the foramen magnum, located at the base of clivus occipitalis.

– anatomic, bony, unilateral landmark

Localization: the distance between the upper delimitation of the second cervical vertebra and Basion is of 3 mm approximately.

Fig. 1.5. Basion - radiographic appearance

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Fig. 1.6. Basion - graphic illustration (Audax)

PORION (Po) – the superior (most external) point on the bony delimitation of the external auditory meatus

– anatomic, bony, bilateral landmark

Localization: - 3-4 mm radiolucence, located at the same height as the condylar head approximately

- the internal auditory meatus is in an ”11 o’clock position” as compared to the external auditory meatus

- the Frankfort Horizontal (Po-Or) makes a 27-29° angle with the cranium base (Ba-N).

Applicability: Porion is used as a reference point in drawing the Frankfort Horizontal (Po-Or) which assesses the vertical growth pattern using following angle:

 FMA angle - Frankfort Horizontal and the mandibular plane (Go-Me)

Fig. 1.7. Porion - radiographic appearance

Fig. 1.8. Porion - graphic illustration (Audax)

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ORBITALE (Or) – The lowest point in the inferior margin of the orbit . – anatomic, bony, bilateral landmark

Localization: if the patient is in a correct position, right and left infra-orbital margins are superimposed on the lateral cephalogram and appear under the shape of a radiopaque line on the teleradiography. Orbitale will be the inferiormost point on the inferior margin of the orbit.

Applicability: Orbitale is used as a reference point in drawing the Frankfort Horizontal (Po-Or) which assesses the vertical growth pattern through:

FMA angle - Frankfort Horizontal and the mandibular plane (Go-Me)

Fig. 1.9. Orbitale - radiographic appearance

Fig. 1.10. Orbitale - graphic illustration (Audax)

THE ANTERIOR NASAL SPINE (ANS) – the anteriormost point of the nasal spine – anatomic, bony, unilateral landmark

Localization: there is an individual variation in the length and widh of the anterior nasal spine; in some cases, it can be long and thin, in other cases it can be short and thick.

 If the nasal spine is thin, it will appear unclear and it will overlap with the nasal cartilage

 If the nasal spine is thick, it will appear clear and it will be easy to trace.

Applicability: The anterior nasal spine is a landmark for drawing the palatal plane (ANS-PNS) employed in:

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 Ricketts analysis/ McLaughlin analysis – vertical ratio between the maxilla and the mandible: the angle between the mandibular plane (Go-Me) and the palatal plane (ANS-PNS)

 The position of the maxillary incisor as compared to the palatal plane (the axis of the maxillary incisor – PP)

McLaughlin analysis: the angle between the palatal plane and the occlusal plane

Fig. 1.11. ANS - radiographic appearance

Fig. 1.12. ANS - graphic illustration (Audax)

THE POSTERIOR NASAL SPINE (PNS) – The posteriormost point of the hard palate – anatomic, bony, unilateral landmark

Localization: just as for the anterior nasal spine, the length as well as the height of the posterior nasal spine may vary; it is difficult to trace it when there are unerupted teeth – in this situation, PNS may be localized between the floor of the nasal cavity and the lower margin of the palatal bone.

Applicability: The posterior nasal spine is a reference point for drawing the palatal plane (ANS- PNS) employed in:

 Ricketts analysis/ McLaughlin analysis – vertical ratio between the maxilla and the mandible: the angle between the mandibular plane (Go-Me) and the palatal plane (ANS-PNS)

 The position of the maxillary incisor as compared to the palatal plane (the axis of the maxillary incisor – PP)

McLaughlin analysis: the angle between the palatal plane and the occlusal plane

(44)

Fig. 1.13. PNS - radiographic appearance

Fig. 1.14. PNS - graphic illustration (Audax)

PROSTHION (Pr) – the inferior- and anteriormost point of the upper alveolar process in the mid- sagittal plane.

– anatomic, bony, unilateral landmark

Localization: it delimits the alveola of the maxillary central incisor at the cementoenamel junction Applicability: a landmark in drawing the angle for assessing the position of the maxillaskeletal base to the cranial base: S-N-Pr

Fig. 1.13. Prosthion - radiographic appearance

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Fig. 1.14. Prosthion - graphic illustration (Audax)

A POINT – the posteriormost point on the curvature of the anterior nasal spine under ANS and in front of the root of the maxillary central incisor. The posteriormost point on the bony outline between ANS-Pr.

– anatomic, bony, unilateral landmark

Localization: one traces the outline of the palate bone, the anterior nasal spine and the anterior margin of the alveolar process. Then, one traces the outline of the maxillary central incisor including the apex and the incisal edge.

*A Point is 2 mm anterior to and approximately at the same height with the apex of the central incisor.

Applicability: a reference point in drawing the planes and the angles which assess:

 The relationship between the maxilla and the cranial base: SNA angle

 The relationship between the maxilla, the mandible and the cranial base: ANB

 The position of the maxillary incisors: the angle between NA and the axis of the maxillary incisor and the linear distance NA - maxillary incisor

 WITS analysis: the perpendicular drawn from the A Point to the occlusal plane

 Ricketts analysis: the distance/ angulation of the maxillary/mandibular incisors on the A-Pg plane

Fig. 1.17. A Point - radiographic appearance

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Fig. 1.18. A Point - graphic illustration (Audax)

INFRADENTALE (Id) – the superior and anteriormost point of the lower alveolar process in mid- sagittal plane. It delimits the alveola of the mandibular central incisor at the cementoenamel junction.

–anatomic, bony, unilateral landmark

Localization: It delimits the alveola of the mandibular central incisor at the cementoenamel junction

Applicability: it is a reference point in drawing the S-N-Id angle

Fig. 1.19. Infradentale - radiographic appearance

Fig. 1.15. Infradentale - graphic illustration (Audax)

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POGONION (Pog) – the anteriormost midpoint on the mental protuberance – anatomic, bony, unilateral landmark

Localization: one traces the outline of the labial cortical plate in the anterior symphysis. Below the B Point, there is a convex outline of labial cortical plate of mandibule and Pogonion is its most prominent point.

Applicability: a reference point in drawing the planes and the angles which assess:

 The relationship between the mandible and the cranial base: the facial angle – S-N-Pog

 Ricketts analysis: the distance/ angulation of the maxillary/ mandibular incisors on the A-Pg plane

 McLauglin analysis: the distance between Pog and the N-based perpendicular to the Frankfort Horizontal

Fig. 1.21. Pogonion - radiographic appearance

Fig. 1.22. Pogonion - graphic illustration (Audax)

B POINT – the posteriormost point on the profile of the mandibular alveolar process, between Id and Pog

– anatomic, bony, median landmark

Localization: one traces the outline of the labial cortical plate of the mandible from the Infradentale to Pogonion. B Point is the posteriormost point between the two.

Applicability: it is used as a reference point in drawing the angles and planes which assess:

 The relationship between the mandible and the cranial base: SNB angle

 The relationship between the maxilla and the mandible and the cranial base: ANB angle

 The position of the mandibular incisors: the angle between NB and the axis of the mandibular incisor and the linear distance NB - mandibular incisor

 WITS analysis: the perpendicular drawn from the B Point to the occlusal plane

(48)

Fig. 1.16. B Point - radiographic appearance

Fig. 1.17. B Point - graphic illustration (Audax)

GNATHION (Gn) – the anterior- and inferiormost point of the menton.

– constructed, bony, unilateral landmark

Localization: one traces the labial cortical plate of the mandible. Under B Point (the posteriormost point) there are Pog (the anteriormost point) and Me (the anterior- and inferiormost point). One then traces a straight line between Pog and Me; Gn is the middle of it, the point determined by the bisector of the angle of intersection of the facial plane (N-Pog) and the mandibular plane (Go- Me).

Applicability: a reference point in drawing the angles and planes which assess:

 The growth pattern: N-S-Gn angle

 Mandibular rotation: Jarabak – SeGn/Frankfort Horizontal axis

 Ricketts analysis: mandibular growth direction: the angle formed by the facial axis (Pt-Gn) with Ba-N

Fig. 1.25. Gnathion - radiographic appearance

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Fig. 1.26. Gnathion - graphic illustration (Audax)

MENTON (Me) – the inferiormost point on the mandibular symphysis.

– anatomic, bony, unilateral landmark

Localization: one traces the labial cortical plate of the mandibular symphysis; Menton is the anterior- and inferiormost point on the lower side of the mandibular symphysis.

Applicability: it is a reference point in drawing the Go-Me mandibular plane which is used when assessing:

 The position of the mandibular incisor: the angle formed by the axis of the mandibular incisor with the mandibular plane

 Tweed analysis: FMA angle formed by the Frankfort Horizontal (Po-Or) with the mandibular plane

 The growth pattern: the angle formed by the SN plane with the mandibular plane

 McLauglin analysis: the angle formed by the occlusal plane with the mandibular plane

McLauglin analysis: the angle formed by the palatal plane with the mandibular plane

Fig. 1.27. Menton - radiographic appearance

Fig. 1.28. Menton - graphic illustration (Audax)

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GONION (Go) – the posteriormost, inferiormost and most lateral point of each gonial angle – anatomic, bony, bilateral landmark

Localization: one traces the outline of the inferior and posterior borders of the mandible; Gonion is represented by the intersection of the tangent to the two margins.

Applicability: it is a reference point in drawing the Go-Me mandibular plane which is used when assessing:

 The position of the mandibular incisor: the angle formed by the axis of the mandibular incisor with the mandibular plane

 Tweed analysis: FMA angle formed by the Frankfort Horizontal (Po-Or) with the mandibular plane

 The growth pattern: the angle formed by the SN plane with the mandibular plane

 McLauglin analysis: the angle formed by the occlusal plane with the mandibular plane

 McLauglin analysis: the angle formed by the palatal plane with the mandibular plane

Fig. 1.29. Gonion - radiographic appearance

Fig. 1.30. Gonion - graphic illustration (Audax)

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1.2 Cutaneous landmarks

GLABELLA (G) – the anteriormost point of the forehead in the mid-sagittal plane, at the level of the upper orbital ridges

– cutaneous, unilateral landmark

Fig. 1.31. Glabella - radiographic appearance

Fig. 1.32. Glabella - graphic illustration (Audax)

NASION (n) – posteriormost point of the nasal root – cutaneous, unilateral landmark

Applicability: Nasofrontal or Dreyfus plane

Fig. 1.33. Nasion - radiographic appearance

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Fig. 1.34. Nasion - graphic illustration (Audax)

PRONASALE (Pn) – the anteriormost point of the nose – cutaneous, unilateral landmark

Applicability

 landmark in assessing nasal projection

 Ricketts analysis: Ricketts’ aesthetic line (E-line) – assessing the relationship between the maxillary/mandibular incisors and the upper/lower lip

Fig. 1.35. Pronasale - radiographic appearance

Fig. 1.36. Pronasale - graphic illustration (Audax)

(53)

SUBNASALE (Sn) – it corresponds to the junction between the philtrum of the upper lip and the columella in mid-sagittal plane

– cutaneous, unilateral landmark Applicability:

 landmark in assessing nasal projection and nose height

 Burstone’s line – assessing the relationship between the maxillary/ mandibular incisors and the upper/ lower lip

Fig. 1.37. Subnasale - radiographic appearance

Fig. 1.38. Subnasale - graphic illustration (Audax)

LABIALIS SUPERIOR (Ls) – the anteriormost point of the margin of the upper lip – cutaneous, unilateral landmark

Applicability:

 Holdaway line for assessing the relationship between the maxillary/ mandibular incisors and the upper/ lower lip

 Merrifield’s Z-angle for assessing the relationship between the maxillary/ mandibular incisors and the upper/ lower lip

 Measuring the length of the upper lip

 Arnett’s analysis – PIP (planned incisor position)

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Fig. 1.39. Labialis superior - radiographic appearance

Fig. 1.40. Labialis superior - graphic illustration (Audax)

LABIALIS INFERIOR (Li) – anteriormost point of the interior margin of the lower lip – cutaneous, unilateral landmark

Applicability:

 Measuring the length of the lower lip

 Arnett’s analysis – PIP (planned incisor position)

Fig. 1.41. Labialis inferior - radiographic appearance

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Fig. 1.42. Labialis inferior - graphic illustration (Audax)

SOFT TISSUE POGONION (Pog) – anteriormost point of the chin in mid-sagittal plane – cutaneous, unilateral landmark

Applicability:

 Landmark in assessing the chin projection

 Steiner’s aesthetic line - “S line”

 Ricketts’ aesthetic line – “E line”

 Burstone’s aesthetic line – “B line”

 Holdaway’s aesthetic line - “H line”

Fig. 1.43. Pogonion - radiographic appearance

Fig. 1.44. Pogonion - graphic illustration (Audax)

(56)

CUTANEOUS GNATHION (Gns) – the point located between the anteriormost and the inferiormost points of the chin in mid-sagittal plane

Fig. 1.45. Gnathion - radiographic appearance

Fig. 1.46. Gnathion - graphic illustration (Audax)

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