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Hard tissue cephalometric analysis INDIAN DENTAL ACADEMY Leader in continuing dental education


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Introduction Definition and classification Various analyses: Lateral cephalometric analysis: Downs analysis Steiner’s analysis Tweeds analysis WITTS appraisal Rickett’s analysis McNamara analysis Rakosi’s functional analysis Bjork analysis,Jarabak anaylsis COGS analysis Quadrilateral analysis

• Pitchfork analysis • Postero-anterior cephalometric analyses: purpose Ricketts analysis Grummons analysis • Conclusion






• Only after completion of thoughtful,systematic evaluation should cephalometric tracings be done. • Ceph analysis is used to asses compare,express and predict the spatial relationships of the soft tissues and the craniofacial and dentofacial complexes.

Systematic approach to patient facial analysis

• The analysis can be : objective subjective

• Objective:quantification of spatial relationships by angular or linear measurements. • Subjective:visualization of changes in spatial relationships of areas or anatomical landmarks.

It provides information about sizes and shapes of the craniofacial components and their relative positions and orientations.

Requisites Cephalometric analysis with a reasonable clinical base should be: 1.

Use reference points that are clearly defined and easy to locate. 2. Rely more than one bone reference plane since these planes are themselves variables.


consider natural head position because resulting values then often reflect the actual appearance of the patient better.


Be clearly structured in skeletal and dentoalveolar assesments and always distingiush b/t different planes(sagittal,vertical,transeverse)


Include as few measurements as possible,so that an optimal overview is maintained at any time.


Include graphical representation,which is useful for immediate understanding and which enhances communication with nonorthodontic colleagues and with patients.


Be structured so that it can be changed without difficulty when better insight requires an adaptation.

Classification of ceph. analysis

• Basic methods of classification: • A)Methodological classification:Basic units of classification are angles and distances in mm: angular analyses linear analyses angular analysis : dimensional analysis eg:Down’s analysis (considers various angles in isolation comparing them with avg norms) proportional analysis eg:Koski’s analysis

Methodological Anglular Dimensional Analysis Eg:Down’s

Methodological Angular Proportional Analysis Eg: Koski’s analysis

• Linear analyses: Orthogonal analyses –a ref plane is established with various ref points projected onto it perpendicularly after which distances b/t the projections are measured geometrical Total orthogonal analyses eg: de Coster arithmetical (ref points projected onto H AND V ref planes,distances b/t projected points measured) Partial orthogonal analysis Archial analysis eg: Sassouni analysis (ref points projected by drawing arcs)

Total geometric Orthogonal analysis:

Coben’s Total Orthogonal Arithmetical Analysis

Arcial analysis Sassouni’s archial analysis

Linear analyses contd. • Dimensional linear analyses - Direct method - Projected method • Proportional linear analyses: based on relative rather than absolute values,measurements compared to each other than to norms

• B) Normative classification:accr to concepts on which norms have been based on Mononormative analyses- averages are norms Multinormative analyses Correlative analyses- to asses indiv variations of facial str,to establish their mutual relatioship • C)Accr. to area of analyses: Dento skeletal analyses Soft tissue analyses Functional analyses


Downs analysis contd. • Position of mandible used to determine facial balance. • 4 basic facial types: Retrognathic - recessive lower jaw Mesognathic - ideal / average Prognathic - protrusive True prognathism – pronounced protrusion

Downs analysis contd. • Choice of reference plane - FH plane • Control material-20 white subjects(12-17yr)

Downs analysis contd. 1. SKELETAL PATTERN 2. DENTAL PATTERN



 Facial angle (87.5°)  Angle of convexity(0°)  A-B plane (-4.6°)  Mandibular plane angle (21.9°)  Y-axis (59.4°)

1) Facial angle • Measures degree of retrusion or protrusion of lower jaw . • (Na – Pog ) Facial line + FH •

in prominent chin, retrusive chin


Mean Reading : 87.5o

Range : 82o – 95o

2) Angle of convexity • Measures the degree prominence of maxillary basal arch at its anterior limit (point A) relative to total facial profile • + reading – A-Pog anterior to N-A i.e, prominence of maxillary denture base relative to mandible

Mean Reading : 0o

Range : -8.5o – 10o


A-B plane

• Measures the relation of anterior limit of apical bases to each other relative to the facial line.(N-Pog) • Estimate of difficulty in obtaining correct axial inclination and incisor relation

Mean Reading : -4.6o

Range : 0o – - 9o

A –B plane contd. • Usually negative – as point B is behind A • Large ve- : class II facial pattern


Mandibular plane angle

• MP : tangent to gonial angle and lowest point of symphysis. • MPA : MP related to FH

Mean Reading : 21.9o

Range : 17o – 28o


plane angle contd.

High MPA: • unfavorable hyperdivergent facial pattern • Can occur both in retrusive and protrusive faces • But not sufficient alone to indicate nature of difficulty that may be experienced during treatment


Y- axis / Growth Axis

• Indicates the degree of downward, rearwards or forward position of the chin in relation to the upper face. • Acute angle at S-Gn with FH

Mean Reading : 59.4o

Range : 53o – 66o

b) Dental patterns 1. Cant of the occlusal plane 2. Inter-incisal angle 3. Incisor – occlusal plane angle 4. Incisor mandibular plane angle 5. Protrusion of maxillary incisors


1. FH plane 2. Palatal plane 3. Occlusal plane 4. Mandibular plane


Cant of occlusal plane

• OCCLUSAL PLANE: overlapping cusps of 6s & incisal overbite OR overlapping cusps 4s & 6s. CANT: Slope of occlusal plane to FH • When ant part lower than posterior, angle is large Class II pattern • Long rami tend to


Mean Reading : 9.3o

Range : 1.5o – 1.4o

2) Interincisal angle

Line through incisal edges and apex of roots of incisors. Small in anteriorly tipped teeth.

Mean reading : 135.4o

Range : 130o – 150o

Mean reading : 1.4o

Range : -8.5o – 7o


Incisor occlusal plane angle

• Relates lower incisors to functional surface at occlusal plane. • Mean 14.5° • Range 3.5 to 20°

5)Protrusion of maxillary incisors • Distance b/t incisal edge to A-Pog. • Mean 2.7mm • Range –1 to +5mm

The polygon / wiggle • Vorheis & Adams (1951) • developed a polygon to express this large grp of ceph readings graphically.

The Polygon contd. • Central vertical line along which means are located. • The range (max & min) to right and left, located at each angle of the polygon, each horizontal marking=1mm or 1 degree • Readings on left indicate class II type of face; on right class III type

• Zig zag pattern skeletal(upper ½) • Poygon subdivided Dental pattern • Effective comprehensive method of quantitaively & qualitatively illustrating a static ceph analysis.


• Cecil c. Steiner • Selected what he considered to be the most meaningful parameters & evolved a composite analysis • Maximum clinical information with minimum measurments.



a)Skeletal analysis • Relates upper & lower jaws to skull & to each other. • Choice of reference plane: S-N(Ant Cr. Base) • On lat ceph. landmarks like porion & orbitale not easily identified. • Adv : S & N midline points that are moved min. when deviates from true profile position

Skl analysis contd. 1. SNA 2. SNB 3. ANB 4. OP to SN 5. PM to SN

Mean reading : 82o

Det position of maxilla to cranial base

• > 82 ° : relative forward positioning of maxilla. • < 82° : relative recessive positioning of maxilla.

Mean reading : 80o

SNA and SNB interpretations are valid only if the SN plane is normally inclined to the true horizontal (6째) and the position of N is normal

3)ANB Relative forward /backward positions of the jaws to each other.

ANB Mean reading : 2o

• > 2 ° : class II skeletal tendency, larger the angle greater the A-P discrepancy of maxillary to mandibular apical bases. • < 2° : mandible is located ahead of the maxilla,class III tendency.

Mean reading : 14o

Mean reading : 32o

MP: GONION-GNATHION Indication of vertical proportions of face

>32째 unfavorable

growth pattern

Relative position of upper incisors to lower incisors.

Mean reading : 130o

â&#x20AC;˘ Compares the prominence of the chin with the prominence of the lower incisor, establishes the balance b/t them. â&#x20AC;˘ The more prominent the chin the more prominent the incisors can be and viseversa.This imp rel is reffered to as HOLDAWAY RATIO.


â&#x20AC;˘ Developed this analysis as an aid to treatment planning, anchorage preparation and determining the prognosis of orthodontic cases. â&#x20AC;˘ Emphasis on placement of mandibular incisors for the preservation of results.

â&#x20AC;˘ Tweeds triangle : formed by FHP MP IMP (Long axis of lower incisors)

• 3 angles : FMA = 25° IMPA = 90° FMIA = 65° • FMA =16 to 28° prognosis good 28 to 35° fair > 35° bad prognosis,extractions may further complicate the problem • Recommended FMIA maintained at 65° to 70°

1. Analysis determines the final position the lower incisors should occupy at the end of treatment , once this position of incisors determined , the space requirement could be calculated and decision regarding extraction made. 2. Prognosis could be relatively accurately based on the configuration of the triangle.



Is the ANB angle a reliable indicator of jaw discrepancy or not?

â&#x20AC;˘ Example of ANB not reflecting the degree of A-P jaw disharmony

Craniofacial skeletal variations affects ANB: 1. The A-P spatial relationship of jaws relative to the cranium 2. The rotational effect of the jaws relative to cranial reference planes : ant cranial base.

• Any change in the relative forward or backward positioning of nasion by virtue of an excessively long or short Ant cranial base (S-N) or • Relative posterior - anterior positioning of jaws within the skl craniofacial complex will directly influence the ANB reading. • Reliability of ANB suspect in cases where MPA is > 38° or < 27°

Anteroposterior relationship of the jaws relative to cranium

Rotational effect of the jaws relative to the anterior cranial base

â&#x20AC;˘ Purpose of WITS: To identify cases where ANB reading donot accurately reflect the extent of A-P jaw dysplasia. â&#x20AC;˘ It is a measure of extent to which jaws are related to each other A-P ly.

METHOD OF WITs Avg reading: -1mm for males 0mm for females

In skeletal class II cases BO located well behind AO

• In skeletal class III BO in front. • WITs reading negative

WITs appraisal applied

Application of WITs appraisal

Application of WITs appraisal to class III

â&#x20AC;˘ The more the wits readings deviate from -1mm in males and 0mm in females the greater the horizontal jaw disharmony.

Occlusal plane angulation â&#x20AC;˘ The effect on WITS value of the occlusal plane angulations and distance betweeen the points A and B

â&#x20AC;˘ To sum up wits appraisal is a linear measurement and not an analysis per se. â&#x20AC;˘ It is an adjunctive diagnostic aid that may prove useful in -- assessing the extent of antero posterior skeletal dysplasia and --in determining the reliability of ANB

Steiner’s chevrons • Whereas the ideal ANB relationship of maxilla to mandible as described by points A & B is 2°,the chevrons describe anticipated axial inclinations of the maxillary and mandibular incisors to the NA & NB lines at various ANB relationships

Example of chevron • ANB was 6 at the end of treatment, • Acceptable compromise relations of maxillary incisor to NA line are 18 , 0mm • Of mandibular incisors are 29 ,5mm • Skeletal the patient is still class II but dental relation masks the underlying skeletal discrepancy


McNamara (1984) normative standards used was derived from sources: •

Lateral cephalogram of children comprising of the Bolton’s Standards •

Selected values from a group of untreated children from Burlington research center. •

Sample of young adults from Ann Arbor having excellent dental and facial pattern.

Skeletal Vs Dentoalveolar components of malocclusion

Skeletal Vs dentoalveolar components of malocclusion â&#x20AC;˘ Maxillary skeletal protrusion â&#x20AC;˘ Maxillary dentoalveolar protrusion

â&#x20AC;˘ Soft tissue evaluation: nasolabial angle cant of the upper lip airway analysis â&#x20AC;˘ Hard tissue evaluation

Craniofacial skeleton has been divided into five sections

 Maxilla to cranial base  Maxilla to mandible  Mandible to cranial base  Dentition  Airway

Maxilla to cranial base


Nasiolabial angle : 102o + 8o

Cant of the Upper lip : Women : 14o + 8o Men

: 8o + 8 o


â&#x20AC;˘ Hard tissue evaluation: A-P orientation of maxilla relative to cranial base. distance of point A to NASION PERPENDICULAR.

Mcnamara-hardtissue evaluation Maxilla to cranial base â&#x20AC;˘ A to Pog IN WELL BALANCED FACES: 0mm ( MIXED DENTITION) 1MM( ADULTS)

â&#x20AC;˘ Maxillary skeletal protrusion

â&#x20AC;˘ Maxillary skeletal retrusion

Maxilla to mandible

â&#x20AC;˘ 2 relationsAnteroposterior relationship Vertical relationship

â&#x20AC;˘ Anteroposterior relationship: linear relationship exists between effective midface length(Co â&#x20AC;&#x201C;point A) and that of mandible length(Co-Gn)

â&#x20AC;˘ Any given MFL corresponds to an effective mandibular length within a given range. â&#x20AC;˘ The lengths of either midface or mandible described in the analysis is not gender or age dependent,but related only to the component part size. â&#x20AC;˘ Terms small ,medium,large used instead of mixed dentition ,adult female , adult male

Normative standards

Maxillomandibular differential = Midfacial length â&#x20AC;&#x201C; Effective mandibular length




Ideal maxillomandibular differential






25 â&#x20AC;&#x201C; 27mm



30 â&#x20AC;&#x201C; 33mm

Which Jaw? â&#x20AC;˘ In the event of maxillomandibular differential greater or smaller than the normative values,next step is to identify which jaw is to large or small or both or at fault

â&#x20AC;˘ Maxillomandibular relationships: 1.maxilla position normal,mandible 9mm deficient 2.skeletal midfacial deficiency of 4mm,mandibular skeletal excess 5mm

Vertical relationship: • Lower anterior face height • Mandibular plane angle • Facial axis angle

• Vertical maxillary excess • Downward and backward rotation of mandible • Increase in lower anterior face height

• Vertical maxillary deficiency • Upward and backward rotation of mandible • Reduction the lower anterior face height

• • • • • •

Lower anterior face height(LAFH): ANS to menton Correlates well with effective MFL Ideal: MFL LAFH Small indiv 85mm 60-62mm Medium size indiv 94mm 65-67mm Large size 100mm 73-77mm

â&#x20AC;˘ To asses LAFH balance effective maxillary length correlated with lower anterior facial height

• Excess LAFH: effective MFL is 93mm, the LFH should have been 65 – 66mm for balance

â&#x20AC;˘ Relationship b/t LAFH and forward and backward positioning of chin point â&#x20AC;˘ Excess LAFH causes mandible to rotate back,mandibular retrusion.

Mandibular plane angle • Anatomic FH and MP(GO-ME) • Avg = 22 +/- 4 ° • Higher measurement –excess LFH • Lesser angle-deficiency in LFH • Effect of short/long mandibular ramus not considered here

• MPA 22°

â&#x20AC;˘ High mandibular plane angle ,excessive LAFH

Angle b/t PTM-Gn and Ba-N Avg=90° Here FAA of –5 ° excessive vertical development of face

Mandible to cranial base

Mixed Dentition = 6-8mm behind nasion perpendicular Adult woman = 4-0mm behind nasion perpendicular Adult men = 2mm behind to 2mm ahead of nasion perpendicular




Airway Analysis

RICKETTS ANALYSIS Landmarks: A6 - upper molar B6 - lower molar C1 - point on head of condyle in contact with the tangent to ramus plane CC - centre of craniumCC CF - PtV+FH PT â&#x20AC;&#x201C; f.rotundum+PMF

DC-centre of condyle neck Gn-facial+MP Go-ramus +MP PM-suprapogonion Pog-on bony symphysis tangent to facial plane

PO-facial plane+corpus axis Xi point

Ricketts-landmarks Location of Pog Points: CF - PtV+FH PT - ptf+f.rotundum CC-cranium centre PM - supragonion PO - corpus axis +facial plane

Obtaining Xi point

RICKETTS analysis-planes

• Facial axis(Pt-Gn) • Facial plane(N-Pog)

RICKETTS analysis-planes • Pterygoid vertical(PtV):distal r/g outline of pterygomaxillary fissure and perpendicular to FH plane

• Ba- Na • FH

Mandibular incisor protrusion to A-Pog plane(Dental plane)


FH- porion to orbitale

2. Facial plane -nasion to gnathion 3. Mandibualr plane-gonion to gnathion 4. PtV-pterygoid verticalvertical line drwn through the distal r/g outline of the pterygomaxillary fissure and perpendicular to the frankfort horizontal 5. Ba-na-divides face and cranium

6. Occlusal plane- line extending through first molars and premolars 7. A-Pog line-dental plane

LANDMARKS: 1. A6- upper molar- point on the occlusal plane located perpendicular to the distal surface of the crown of the upper first molar. 2. B6-lower molar-point on the occlusal plane located perpendicular to the distal surface of the crown of the lower first molar 3. C1-condyle-point on the condyle head in contact with and tangent to the ramus plane

4. DT-soft tissue-point on the anterior curve of the soft tissue chin tangent to the esthetic plane or E-Line. 4. CC-centre of cranium-point of intersection of basion-nasion plane and facial axis. 5. CF-point of intersection of the pterygoid root vertical to the frankfort horizontal plane. 4. PT-the junction of pterygomaxillary fissure and the foramen rotundum:


The outline of the foramen rotundum can be located by using the template designed for the purpose or can be approximated at 10:30 position on the circular outline of the superior border of the pterygomaxillary fissure.

8. DC-point in the centre of the condyle neck along the BASION-N plane

9. Gn-gnathion-poitn at the intersection of facial and mandibular planes 10. Go-gonion-point a the intersection of ramus and mandibular planes 11. PM-suprapogonion-point at which the shape of the symphysis mentalis changes from convex to concave=protuberence menti. 12. Pog-pogonion-point on the bony symphysis tangent to the facial plane. 13. PO-intersection of facial plane and the corpus axis

14. TI point-point of intersection of occlusal and facial planes. 15. Xi-Xi point

Ricketts analysis-axes

Corpus axis(Xi-PM) To describe morphology of mandible & evaluate dentition changes

Ricketts analysis - axis

Condylar axis ( DC-Xi) Used to describe morphlogic features of the mandible

Ceph tracing using ricketts analysis

CHIN IN SPACE  Facial axis angle: 90° lesser angle- retropositioned chin greater angle – forward positioned chin  FACIAL DEPTH ANGLE:87° +/- 3° indication of horizontal position of chin whether class II or class III is due to mand.  MANDIBULAR PLANE:26° +/- 4.5° EG:Steep MPA indicates open bite may be due to skl morphologic characteristics of mandible

Convexity of Point A Mean : 2 mm +/- 2 mm Adjusted mean:-1mm/yr High convexity= class II skl pattern

Mandibular incisor protrusion to A-Pog plane(Dental plane) Defines protrusion of lower arch. Mean= 1mm ahead of A-Pog

Upper molar position(to PtV) Mean:Age + 3mm Adjusted mean:+1mm/yr DET whether maloccl is due to u6 or L6 position.also deciding if extractions are necessary.

COGS â&#x20AC;&#x201C; Cephalometrics for Orthognathic Surgery Charles J. Burstone â&#x20AC;&#x201C; 1978

University of Connecticut

COGS  Chosen landmarks and measurements can be altered by various surgical procedures. comprehensive appraisal-includes all facial bones and a cranial base reference.  Rectilinear measurements can be readily transferred to a study cast for mock surgery.

ď ą Critical facial skeletal components can be examined. ď ą Standards and statistics are available for variations in age and sex from 5 to 20 ď ą Consists of a series of measurements that can be computerised.

H-P line • Baseline for comparison of most data • Constructed plane • By drawing a line 7 ° to SN

Cranial Base 1.Ar-N:length of the cranial base (not an absolutevalue, proportional,so that can be correlated with mandibular,maxillary lengths) 2.Ar-PTM : measure horizontal distance b/t poterior aspects of mandible & maxilla.The greater the distance,the more the mandible will lie posteriorly to maxilla Males=37.1 +/- 2 mm Females = 32.8 +/- 1.9 mm 3. PTM â&#x20AC;&#x201C;N : Males = 52.8 +/- 4.1 mm females= 50.9 +/- 3.0 mm s

b. HORIZONTAL SKELETAL PROFILE 1. N-A-Pg=angle of skeletal facial convexity - indication of overall facial convexity measurement doesn’t indicate if due to maxilla or mandible + angle-convex face - angle –concave face Mean : Males : 3.9 +/- 0.4 ° females: 2.6 +/- 5.1 °

Sign convention: A perpendicular to HP drawn through N. The inferior anatomic point is horizontally measured in relation to the superior structure, with + being anterior and â&#x20AC;&#x201C; being posterior. 2.N-A : horizontal position of A is measured to this Perpendicular .measurement describes the horizontal position of Apical Base of the maxilla in relation to N ---to determine if anterior part of maxilla is protrusive or retrusive. M ean : males= 0.0 +/- 3.7mm ; females = -2.0 +/- 3.7 mm 3.N-B Mean : males= -5.3 +/- 6.7 mm ;

females= -6.9 +/- 4.3 mm

4.N-Pg = prominence of chin if unusually large or small,then compare with N-B & B-Pog: this determines if discrepancy is in the alveolar process, the chin or the mandible proper MEAN: MALES = -4.3 +/8.5 mm ; females = -6.5 +/- 5.1 mm

Horizontal Measurements


Diagnosis of: • Horizontal maxillary hypolasia/hyperplasia • Horizontal mandibular hypo/hyperplasia • Horizontal genial hypo/hyperplasia Used in planning of treatments: • Augmentation /reduction genioplasty • Ant mandibular horizontal advancement or reduction • Total mandibular horizontal advancement or reduction

c. Vertical skeletal dysplasia 1. middle 1/3 facial ht (N-ANS) â&#x2022;§ HP Anterior components

males= 54.7+/- 3.2mm females= 50 +/- 2.4mm

2. lower 1/3 facial ht ( ANS- Gn ) â&#x2022;§ HP males = 68.6 +/- 3.8mm females= 61.3 +/- 3.3mm

Posterior components 3. posterior maxillary ht (length of perpendicular line from HP intersecting PNS)

Vertical skeletal dysplasia contd. 4. MP-HP angle = relates the posterior facial divergence with respect to anterior facial height. MP angle + posterior maxillary height define Vertical dysplasia of posterior components

Helps in Diagnosis of: â&#x20AC;˘ anterior , posterior or total vertical maxillary hyperplasia or hypoplasia. â&#x20AC;˘

clockwise or counterclockwise rotations of maxilla and the mandible.

Vertical dental dyspalsia • Anterior component: Anterior maxillary height : upper1-NF Anterior mandibular height : lower1 – MP indicate how far incisors have erupted in relation to NF and MP • Posterior conponent: Posterior maxillary height :Upper 6 – NF Posterior mandibular height : Lower 6 - MP

Vertical Measurements

These value should be related with ANS-Gn and MP-HP to establish whether the origin of maxillary or mandibular discrepancies is skeletal , dental or a combination of both.

d. MAXILLA and MANDIBLE 1. PNS- ANS: total effective length of maxilla With ANS-N and PNS-N quantitatively describes maxilla in the skull complex males = 57.7 ± 2.5 mm ;females =52.6 ± 3.5mm 2. Ar- Go ( linear): length of mandibular ramus males= 52±4.2 mm ;females =46.8±2.5mm 3. Go- Pg (linear): length of mandibular body males = 83.7±4.6mm ; females = 74.3±5.8mm 4. B- Pg : prominence of chin rel to mand. Denture base males = 8.9 ± 1.7mm; female = 7.2 ± 1.9mm By comparing with N-Pg distance chin prominence rel to face

5. Ar- Go- Gn

Maxilla and Mandible

Diagnosis of: • variations in ramus height that effect open bite or deep bite • increased dimension of mandibular body length • acute or obtuse Go angles • assesment of chin prominence: prominence of chin related to mandibular denture relating to N-Pog asses the prominence of the chin in relation to the face.


Assessment of Dental anomolies • OP : line drawn from the buccal groove of both first permanent molars through a point 1mm apical to the incisal edge of the central incisor in each arch 1.OP angle: upper- HP,OP lower – HP males= 6.2 ± 5.1mm ;females =7.1 ± 2.5mm 2.A-B: relationship of maxillary and mandibular apical base to OP (linear measurement than familiar ANB) males= -1.1±2.0mm ;females = -0.4 ± 2.5mm

Diagnosis of: • Increased OP-HP :skl open bite,lip incompetence,increased facial hieght,retrognathia • Decreased OP-HP: • A-B: large A-B with point B posterior to point A ,mandibular denture discrepancy that predisposes to class II malocclusion.

3. upper incisor – NF angle males = 111.0 ±4.7° ;females = 112.5± 5.3° 4. lower incisor - MP angle males = 95.9 ± 5.2° ; females = 95.9 ± 5.7mm Indicate procumbency or recumbency of incisors,vital in assessing long term stability of the dentition.

Dental Measurements

Rakosiâ&#x20AC;&#x2122;s functional analysis

1. Analysis of facial skeleton 2. Analysis of mandibular and maxillary base. 3. Dento-alveolar analysis

Analysis of facial skeleton

1. Saddle angle • sella-nasion – articulare.(angle b/t posterior and anterior cranial base) • Sphenooccipital synchondrosis

• Large saddle angle: posterior position of the fossa Retrognathic profile • Mean = 123 + / - 5 °

2. Articular angle â&#x20AC;˘ S-Ar - Go Can be altered by orthodontic treatment. Mean = 143 +/- 6°

â&#x20AC;˘ Bite opened by Extrusion of posterior teeth or distalisation large S-Ar - Go Retrognathic profile

3. Gonial angle • Ar–Go - Me • Expression of form of mandible. • Relation b/t body and ramus. • Also part in growth prognosis.

Gonial angle continued • Mean = 128 +/- 7° • Large angle Tendency for posterior rotation of mandible with condylar growth directed posteriorly

Upper and lower gonial angles of Jarabak • Divided by N – Go • Upper angle: ascending ramus - N-Go 50 + /- 2° Large upper angle Horizontal growth changes

â&#x20AC;˘ Small upper angle caudal growth â&#x20AC;˘ Large lower angle vertical growth Small lower angle Sagittal growth

Mandibular variations due to rotations Gonial angle has marked influence on: direction of growth. profile changes. position of lower incisors.

â&#x20AC;˘ Magnitude of Go is determined by relationship B/T: ANTERIOR FACE HEIGHT LENGTH OF RAMUS Ant face height

obtuse Go eg:skl open bite large basal plane angle


Cause for increased gonial angle: 1. Adaptation of Go to increased AFH. 2. The AFH adapts to a prior large Go by increase in alveolar process height.

4. Sum of posterior angles Sum of saddle,articular gonial angle= 396 +/- 6°  396 °= vertical direction of growth < 396 °= horizontal growth

5. Facial height â&#x20AC;˘ Posterior facial height(S- Go) â&#x20AC;˘ AFH= N-Me greater PFH Horizontal growth

â&#x20AC;˘ To estimate the direction of growth = JARABAK RATIO PFH * 100 = 1% AFH MEAN :62- 65 % Ratios of <62 % indicates a vertical growth pattern, >65% indicates horizontal growth pattern, PFH

6. Anterior cranial base length Measured b/t centre of superior entrance to Sella to N point. Used to compare length of jaw bases Increases 他 mm annually 18yr = 75.4 mm ( males) 70.1 mm (females)

7.Posterior (lateral) cranial base â&#x20AC;˘ Sella to articulare Short cranial base seen in vertical growth pattern ,skl open bit,poor prognosis for functional appliance therapy Midface appears prognathic, secondary in AFH

B. Analysis of jaw bases 1. SNA angle Mean=81째 >84 째=maxillary prognathism <78째= maxillary retrognathism

2. SNB angle Mean=79째 >82=prognathic mandible <77째=retrognathism mandible

3. ANB Mean=2째

4. SN- Pog: determines basal position of mandible.If the chin projects to a marked degree, the difference b/t SNB and SN-Pog is large. 76° at 6yr ; 80° at 16yr 5.SN –Pr and SN- Id • Relation b/t alveolar process of maxilla and mandible with the cranial base • These above angles determine relationships in sagittal plane.

7.Jaw base analysis-basal plane angle Pal –MP Defines the angle of inclination of mandible to maxillary base • Angle also serves to det the rotation of mandible. Mean = 25 ° • Large BPA mandible rotated back vertical growth pattern • Small BPA Mandible rotated forward Horizontal type growth


BPA dependent on : 1. Mandibular inclination 2. Maxillay angulation Retro-inclination of maxilla relatively smaller BPA ante-inclination Larger BPA

PAL-Occl and Occ- MP • BPA divided by OP: upper angle= 11° lower angle =14° Lower angle imp in assessing prognosis for opening the bite If>20° good prognosis ,if < 7° poor prognosis poor for treatment of deep overbite.

8.Angle of inclination-J ANGLE • Pn line (perpendicular from soft tissue nasion) and palatal plane. • Angle used to asses maxillary rotation. • Large J = anteclination of lower face.

J angle â&#x20AC;˘ Angle used to asses maxillary rotation.

9. SN-MP • Gives the inclination of the mandible to ACB. • Mean- 32° >32°=posterior inclination <32°= anterior inclination • The angle registers vertical dysplasias,changes b/t selle and fossa and below fossa. eg: open bite with large SN-MP indicates that the molars have erupted in disproportion to incisors.

• If both SN –MP and the BASAL PLANE ANGLE are large, the dysplasia must lie below the fossa (the ascendng ramus in too short)

10. Y –axis (S-N – Gn) • Determines position of the mandible relative to cranial base as an additional check. • Mean= 66° • >66° = mandible posterior position • <66° = mandible anterior position rel to Cr. base

11.Linear measurement of jaw bases a)extent of mandibular base Go â&#x20AC;&#x201C; Pog It is 3mm longer then SE-N upto 12yr , after 12yr it is 3.5mm longer . Mean = 68mm at 8 yr Annual increase of 2mm for boys 1.4 mm for girls

b.extent of maxillary base:distance from PNS to Point A projected onto palatal plane. Mean = 45.5mm at 8yr Annual increase: 1.2 in boys 0.8mm in girls

c)length of ascending ramus: Go â&#x20AC;&#x201C; Condylion Constructed condylion Mean at 8yr is 46mm Annual increase of 2mm for boys 1.2 mm for girls upto 16yr

d)Width of ascending ramus: Det at height of occlusal plane Mean- 27mm at 8yr At 16yr 32.5mm for boys 30.5mm for girls

C.Dentoalveolar analysis a.Axial inclination of upper incisors: Long axis of maxillary incisor extended to incisor extended to intersect SN line and posterior angle is measured. mean=102째 , attained 2yr after eruption Also angle formed with palatal plane measured. Enlarged angle signifies very upright Incisors, smaller than average angle indicates protrusion mean = 70+/- 5째 These 2 measurements used in treatment planning Eg: regarding need for root torquing.

â&#x20AC;˘ Lower incisors Posterior angle b/t MP and long axis of lower incisor Mean 90 +/- 3°

b. Position of incisor Upper incisor Mean: 4+/- 2mm

Lower incisor position mean - 2 to +2mm

Bjork analysis • Vast study 600 patients,90 cph measurements • Special feature : polygon N–S-Ar - Go-Gn to assess and predict the direction of growth changes in lower face

1. Sum of Saddle, articular, gonial angle > 396 degree clockwise growth changes. <396 degree anticlockwise 2. At 11yr, ant Cranial Base (S-N) = GoMe 3. S-Ar :Ar-Go = 3:4 4. PFH * 100/ AFH 56 –62% clockwise growth ,long face 65 –68% anticlockwise growth

Jarabak analysis

Quadrilateral analysis

â&#x20AC;˘ Di paolo ; 1962 â&#x20AC;˘ Indivisualized approach to ceph analysis: attempts to identify skl deviations in size and position both in vertical and horizontal dimensions regardless of the dentoalveolar considerations. â&#x20AC;˘ Proportionate analysis

Two parts : skeletal assessment dental assessment

SKELETAL ASSESMENT â&#x20AC;˘ concept of lower facial proportionality: in a balanced facial pattern 1:1 proportionality b/t maxillary base length and mandibular base length. max lth = mand. Lth = ALFH + PLFH 2

SKL assesment contd. â&#x20AC;˘ Construction of quadrilateral : ANS-PNS and Go Gn 1. Maxillary base lengthPlr. Pt A to Palatal plane PTM to Palatal plane 2. Mandibular base length â&#x20AC;&#x201C; Pt B to Go Gn (ant .limit) point J to GoGn( post. limit)

• Anterior lower facial height: projection of point A on the Palatal plane to projection of point B onto Go-Gn plane. • Posterior lower facial height: projection of PTM onto Palatal plane to projection of Pt J onto Go-Gn plane. • Anterior facial height: projection of point A onto palatalplane to Nasion on the cranial base.

• • • •

ALFH PLFH AUFH AUFH : ALFH 45 :55 • Angle of facial convexity 165 – 178°

SAGITTAL RATIO Assessing the rel A-P positon of the maxillary mandibular bony bases When ALFH & PLFH are parallel & bases are equal a proportional rel exits The ratio of A:B and C:D of similar isoceles triangle is the sagittal ratio. In balanced skl patterns,sagittal ratio: 1 : 1.5 +/- 0.05(adolescence) 1 : 1.45 +/- 0.05 (adult) Sagittal angle = 23 +/-1째

â&#x20AC;˘ Angle of facial convexity: formed by intersection of ALFH and AUFH It relates the quadrilateral to upper face The degree of facial convexity will vary depending on the skeletal type and the position of the quadrilateral as it relates to the upper face.

â&#x20AC;˘ Depends on: 1. rel size differences of maxillary and mandibular bony bases 2. rel. position of the maxillary and mandibular bony bases.(sagittal ratio) 3. vertical dysplasia of the lower face (ALFH:PLFH) 4. Spatial rotation of the lower face( quadrilateral) to the UAFH.


• TYPE 1 ;NORMODIVERGENT PATERN: Equal maxillary and mandibular basal arch Length, avg vertical height = arch length • Type 2 : hypodivergent pattern: predominant horizontal growth pattern reduction on LFH SKL DEEP BITE avg Vertical ht deficieint to dental base length • Type 3 ; hyperdivergent pattern: predominant vertical growth pattern increase LFH skl open bite avg vertical height excessive compared to denture base length

DENTAL ASSESSMENT • Pt A line :5 +/- 1 mm • Pt B line:2 +/-1 mm • Pogonion line

ADVANTAGE OF QUADRILATERAL ANALYSIS Differentiates b/t jaw size and jaw position Eg:distinction b/t Mandibular excess and mandibular prognathism or mandibular retrusion and deficiency. Information critical for surgical or nonsurgical orthodontic treatment.

Pitchfork analysis • Johnston • Differentiate B/T Skeletal and dental changes , to evaluate combined treatment effect along the functional occlusal plane • Growth and displacement of maxilla and mandible are measured relative to the cranial base ( SE registration) • The changes in position of upper and lower incisors and molars are measured relative to basal bone( regional superimposition)

â&#x20AC;˘ All these measurements are made parallel to mean functional occlusal plane and are given signs appropriate to the nature of their contribution to molar and overjet changes or corrections. â&#x20AC;˘ As a result ,the algebraic sum of the various skeletal and dental changes equals the treatment change in molar relationship and incisal overjet.

Pitch fork analysis

• Maxilla+mandible =ABCH • ABCH+U6+L6 =molar correction • ABCH + u1 +L1 = overjet correction




Need for PA cephalometrics: Facial assymetry identification Gross examination- morphology,shape,size of skull,bone density,sutural morphology Diagnosis, Treatment planning Growth assessments Evaluation of treatment results

Limitations: • Errors related to X-ray projection,the measuring system,identification of landmarks. • Maintaining position of head in head holder difficult,tilt affects linear measurements. • The diagnostic interpretation of ratios for clinical applications in individual cases is difficult.

PA cephalometric analyses: 1. Ricketts analysis 2. Svanholt and Solow analysis 3. Grummons analysis 4. Grayson analysis 5. Hewitt analysis 6. Cherici method


Ricketts etal 1972

• 1. 2. 3.

Incorporates the following measurments: Nasal cavity width (24.9mm) Mandibular width (Ag –Ag) Maxillary width ( J point to Frontal line) J point= crossing of outline of the tuberosity with that of the jugal process evaluated in rel to mandible on right and left side seperately. molar – jaw = 6.2 mm ( on R and L)

Variables used in PA Ricketts 5.symmetrymidsaggitalplane, ANS,Pog to judge assymetry 6.intermolar width=54.5mm 7.intercuspid width=23.9mm 8.denture symmetry 9.upper molar to lower molar relation. MAX-MAND width =10.8mm

2)Grummons analysis • • • •

Grummons and Kappeyene van de Coppello Comparitive quantitative PA ceph analysis No normative data Components of analysis: Horizontal planes Mandibular morphology Volumetric comparison Maxillomandibular comparison of assymetry Linear assymetry assesment Maxillomandibular relation Frontal vertical proportions

Landmarks -grummons

a.4 horizontal planes constructed: • Medial aspects of zygomaticofrontal sutures(z) • Centres of zygomatic arches(ZA) • Medial aspects of jugular processes (J) • Parallel to Z-Plane through menton • Midsagittal reference line(MSR) =crista galli(Cg),ANS,chin

b.Mandibular morphology analysis grummons â&#x20AC;˘ Left and right triangles formed b/t Co-Ag-Me.

c.Volumetric comparison analysis

â&#x20AC;˘ 4 points connected: condylion antegonial notch(Ag) menton(Me) intersection with a perpendicular from Co to MSR L and R polygons are superimposed with aid of computer program and % value of symmetry obtained

d.Maxillomandibular comparison of assymetry â&#x20AC;˘ 4 lines constructed: 1)perpendicular to MSR from Ag and J bilaterally. 2)lines connecting Cg and J 3)Lines from Cg to Ag If symmetric,2 triangles formed J-Cg-J and

e. Linear assymetry analysisGrummons â&#x20AC;˘ Linear distances to MSR and the difference in the vertical dimension of perpendicular projections of bilateral landmarks Co,NC,J,Ag,Me to MSR

f. Analysis of Maxillomandibular relation • Distances from buccal surfaces of maxilalry molar to J-perpendiculars are measured. • Lines connecting ANSMe and MSR lines also drawn—reveals any dental compensation for skeletal assymetry

g. Analysis of Frontal vertical proportions-Grummons 1. 2. 3. 4. 5. 6.

Upper facial ratio Cg-ANS:Cg-Me Lower face ratio ANS-Me:Cg-Me Maxillary ratio ANS-A1:ANS-Me Total maxillary ratio ANS-A1:Cg-Me Mandibular ratio B1-Me:ANS-me Total ratio B1-Me:Cg-Me

â&#x20AC;˘ Summary facial assymetry analysis components: of horizontal planes 2.mandibular morphology analysis 3.maxillomandibular comparison of facial asymmetry

PA analyses-GRAYSON analysis • Method of analysis craniofacial assymetry with the use of multiplane posteroanterior cephalometry(1983). • Landmarks, mid points and midlines are identified in 3 different coronal or frontal planes at different depths in the craniofacial complex. • Hence this allows visualization of midlines and midpoints in the third dimension (sagittal) in a PA analysis.

3 different planes on lat ceph â&#x20AC;˘ Three separate acetate tracings are made on the same PA r/g. corresponding to the 3 different planes indicated on the lateral view

3 plane tracing-graysons Tracing along the 1st plane â&#x20AC;˘ Trace orbital rims,pyriform aperture,maxillary and mandibular incisors,midpoint of the symphysis

• Greater and leseer wing of sphenoid • Most lateral cross section of zygomatic arch • Coronoid process • Maxillary & mandibular molars • Body of mandible • Mental foramina

• Superior surface of petrous temporal • Mandibular condyles with outer border of ramus • Mastoid process

â&#x20AC;˘ Midlines constructed for 3 planes:

â&#x20AC;˘ 3 tracings superimposed â&#x20AC;˘ Wraping of midlines within craniofacial skeletons observed â&#x20AC;˘ Midline constructs deviate progressively laterally as one passes from posterior to anterior planes of the face.

Conclusions: • Cephalometric analyses are a means of obtaining information AND NOT AN END IN ITSELF. •Cephalometric analyses are merely aids in helping the clinician arrive at a diagnosis and treatment planning. • All anteroposterior skeletal discrepancies cannot be corrected to an ideal jaw relationship. •Cephalometric measurements are not to be regarded as final points or values and it is not necessary that values should exactly tally.

â&#x20AC;˘ Variation in biology is a rule, therefore a normal value is never a point so a mean is to be always considered. â&#x20AC;˘ Serial cephalograms taken during course of treatment helps us to ascertain whether our treatment goals are achieved. â&#x20AC;˘ The Wits appraisal is a linear measurement and not an analysis per se. It is simply an adjunctive diagnostic aid that may prove useful in assessing the extent of anteroposterior skeletal dysplasia and in determining the reliability of ANB angle.

â&#x20AC;˘ We should strive to develop cephalometric norms pertaining to Indian backgrounds instead of those meant for Caucasian norms.

References • An atlas and manual of cephalometric radiography ---Thomas Rakosi. • Radiographic cephalometryAlexander Jacobson. • Orthodontic cephalometry – Athanosios E Athanasiou

2.Svanholt and Solow â&#x20AC;˘ Analyses relation b/t midlines of jaws and dental arches â&#x20AC;˘ Has variables that are zero in symmetric subjects

Variables: 1)Transverse maxillary position=mx-om/ORP 2)trns. Mandibular position m-om/ORP 3)trns jaw rel = CPL/MXP 4)Upeer incisal position= isf-mx/MXP 5Lower incisal position= iif-m/MLP 6)Upper incisor compensation= isf â&#x20AC;&#x201C;mx/m

7)lower incisal compensation =iif-m/mx

PA analysis-HEWITT analysis • • • • • • • •

Triangulation of face: Cranial base region Lateral maxillary region Upper maxillary region Middle maxillary region Lower maxillary region’ Dental region Mandibular region

â&#x20AC;˘ Beatlyâ&#x20AC;&#x2122;s alternative to ANB

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