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Go Back       Himalayan Journal of Medicine and Surgery | Volume:3 Issue:2 | March 20, 2022
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DOI : 10.47310/Hjms.2022.v03i02.002       Download PDF       HTML       XML



Composite Cephalometric Analysis for Orthognathic Surgery (CCAOS)


Dr. Sunil.T1, Dr. Amitha H A1 and Dr Nishitha C Gowda1

1Department of Orthodontics, V.S.Dental College & Hospital

*Corresponding Author

Dr. Sunil.T


Article History

Received: 27.02.2022

Accepted: 05.03.2022

Published: 20.03.2022


Abstract: The Successful Treatment Depends On Careful Diagnosis. The Role Of Orthodontist In Orthognathic Surgery Cases Is To Evaluate The Skeletal Problem, Identify And Quantify The Same. There Are Various Cephalometric Analysis To Evaluate The Orthognathic Surgery Cases Such As Cephalometric Analysis For Orthognathic Surgery (Cogs), Quadrilateral Analysis, Arnett Analysis, Burstone And Legan Soft Tissue Cephalometric Analysis, Etc,. All These Analysis Were Based On Hard Tissue References With The Paradigm Shift To Soft Tissue. It Is Very Difficult To Do So Many Analysis For Each Case. There Are Many Common Overlapping Parameters In These Analysis. The Commonly Used Analysis Are Burstone's Cephalometric Analysis For Orthognathic Surgery (Cogs), Dipaolo's Quadrilateral Analysis, Arnett's Soft Tissue Cephalometric Analysis (Stca). Hence, An Attempt Is To Combine The Overlapping Parameters Of These Three Analysis And Composite Cephalometric Analysis For Orthognathic Surgery (Ccaos) Is Arrived And Is Presented.


Keywords: CCAOS, orthognathic surgery, COGS, STCA, quadrilateral analysis

INTRODUCTION

The assessment of craniofacial dimension is not a new skill in orthodontics. Cephalometry is used to assess craniofacial growth and determine treatment responses. Cephalometric radiology was introduced in orthodontics during the 1930’s but the method really gained wider acceptance for practical application during the last 20 years (Rakosi, T. et al., 1993). Over the years, whole range of analysis has been developed by number of authors. The analysis will only supply answers to a particular set of questions and these answers will depend on correct application of the method and interpretation of results.

The successful treatment of orthodontics of orthognathic surgical treatment is dependent on careful diagnosis. It is important for the clinician to be able to predict the soft tissue changes resulting from alterations of the hard tissue. Many studies have attempted to evaluate the relationship between hard tissue surgery and the effects it has on the overlying soft tissue (Chew, M. T. 2005). Though cephalometric analysis has its limitations, it is a tool which will guide us in planning orthodontic treatment.

The various cephalometric analysis given by many authors such as Cephalometric Analysis for Orthognathic Surgery(COGS) (Burstone, C. J. et al., 1978), Quadrilateral Analysis (Di Paolo, R. J. et al., 1983), Arnett Analysis (Arnett, G. W. et al., 1999), Burstone and Legan Soft Tissue Cephalometric Analysis (Legan, H. L., & Burstone, C. J. 1980) ,etc., were used for surgical patients for interpretation of results. All these analysis were based on hard tissue references with the paradigm shift to soft tissue. Arnett, G. W. et al., (1999), presented the facial keys to orthodontic diagnosis and treatment planning.

Widely used cephalometric analysis for surgical analysis of an orthognathic surgery cases are-

  1. Burstone’s Cephalometric Analysis for Orthognathic Surgery(COGS)

  2. Dipaolo’s Quadrilateral Analysis

  3. Arnett’s Soft Tissue Cephalometric Analysis (STCA)

Though each analysis has its own merits and demerits, there are many overlapping parameters studied by these three authors. Hence, the aim of the present study is to identify the significant parameters and overlapping parameters from the above analyses and to arrive at a CCAOS.


Obtaining the lateral cephalometric radiograph-

Lundström, A., & Lundström, F. (1995) findings indicate that a horizontal line, related to natural head position, adjusted to natural head orientation when indicated, presents the most reliable basis for cephalometric analysis. Some patients assume an “Unnatural head position”. Accordingly these patients need adjustment to “natural head orientation” (Arnett, G. W. et al., 1999).


Anatomical landmarks used for the analysis:

The landmarks used in the cephalometric analysis are the following (fig 1):


Hard tissues: Sella (S), Nasion(N), Pterygomaxillary fissure(PTM), Subspinale (A), Supramentale(B), Pogonion(Pog), Anterior nasal spine(ANS), Posterior nasal spine(PNS), Gnathion


(Gn), Gonion(Go) (Burstone, C. J. et al., 1978), J point, Nasal floor (Di Paolo, R. J. et al., 1983).


Soft tissues: Glabella(G’), Nasal tip(NT), Subnasale(Sn), Subspinale(A’), Submentale(B’), Upper lip anterior (ULA), Lower lip anterior (LLA), Pogonion(Pog’) (Arnett, G. W. et al., 1999)


Figure Image is Available in PDF Format


Fig: 1 Anatomic Land marks and reference planes


Reference Planes:

COGS (Burstone, C. J. et al., 1978)- Hard tissue-horizontal plane (H-P) [Surrogate Frankfurt Horizontal plane].

STCA(Arnett, G. W. et al., 1999) - Soft tissue –True vertical line.


Other Planes:

Palatal plane- ANS-PNS (Di Paolo, R. J. et al., 1983), Mandibular Plane (MP)- GoGn (Burstone, C. J. et al., 1978; & Di Paolo, R. J. et al., 1983) and Functional Occlusal Plane (Burstone, C. J. et al., 1978)


Method: Cephalogram of an adult patient with skeletal malocclusion case is taken. Lateral Cephalogram is traced using 4H lead pencil on Acetate tracing paper.


Linear measurements:

Hard tissue- In this most of the measurements are made either parallel or perpendicular to HP plane.

Chin prominence: Perpendicular line from H-P plane is dropped from point N. Distance from Pog to this line indicates the prominence of chin. These measurement help determine if there is horizontal genial hyperplasia or hypoplasia.


Vertical Skeletal and Dental Discrepancy:

Posterior maxillary height: is the length of perpendicular line dropped from HP intersecting the PNS


Vertical Dental Dysplasia:

It is divided into Anterior and Posterior

Components:


Anterior maxillary dental height and mandibular dental height:

Perpendicular from Upper incisor (U1) to nasal floor (ANS-PNS).

The tip of the Lower incisor (L1) to Mandibular plane (Go-Gn).


Posterior dental measurement:

Perpendicular length of a line through the maxillary first molar mesiobuccal cusp tip to MP.

It is a similar line through the mandibular first molar mesiobuccal tip of the cusp constructed to MP.


Skeletal Assessment:

Maxillary base length (fig 2): Horizontal linear measurement along the palatal plane between the two points. The anterior limit is determined by projecting a perpendicular from point A upward to palatal plane (ANS-PNS), while the posterior limit is determined by projecting a perpendicular from the most inferior portion of pterygomaxillary fissure (PTM) downward to palatal plane.


Figure Image is Available in PDF Format


Fig: 2 Maxillary Base Length.


Mandibular base length (fig 3): is measured horizontally along the Go-Gn plane between the two points. The anterior limit is determined by projecting a perpendicular from point B downward to the mandibular plane (GoGn), while the posterior limit is determined by projecting a perpendicular from point J downward to the mandibular plane (GoGn).


Figure Image is Available in PDF Format


Fig: 3 Mandibular Base Length.

Proportionality (fig 4)-

The quadrilateral analysis indicates that in a balanced facial pattern a 1:1 ratio exists between the maxillary and mandibular bony base lengths.

Maxillary length=Mandibular length= ALFH+PLFH


Figure Image is Available in PDF Format


Fig: 4 Assessment of Proportionality


Figure Image is Available in PDF Format


Fig:5 Dental assessment


Dental Assessment (fig 5)

Maxillary incisor position: determined by drawing line through point A parallel to the anterior lower facial height (ALFH). A perpendicular from this line to the most anterior point on the maxillary incisor.


Mandibular incisor position: determined by drawing line through point A parallel to the anterior lower facial height (ALFH) . A perpendicular from this line to the most anterior point on the mandibular incisor.


Chin position: determined by drawing line tangent to the Pog parallel to the anterior lower facial height(ALFS). A perpendicular from this line to most anterior point on the mandibular incisor. This measurement will indicate if the chin is excessive or deficient in size.


Saggittal ratio: Extend the Quadrilateral to meet at a point. It forms an isosceles triangle. It is divided into anterior and posterior legs. The anterior legs are formed by maxillary and mandibular base and posterior legs formed extending the anterior legs to meet at a common point. This helps in pinpointing the area of deformity whether or not surgical procedure is indicated.


Posterior Divergence of the Mandible: It is shown by MP angle. It is the angle formed between a line from Go-Gn (MP) and HP as it intersects at Gn. Posterior maxillary height and MP angle defines the vertical dysplasia of the posterior components


Angle of facial convexity: is the angle formed between N, projection of point A onto the palatal plane and projection of point B onto mandibular plane (Go-Gn).


Soft tissue -Most of the measurements were made either parallel or perpendicular TVL. The factors considered and measured in this analysis for SCCA are:


Dentofacial factors:

Overjet: parallel lines are drawn from incisal edge of upper and lower incisors to True vertical line (TVL)and distance between these 2 parallel lines are measured.

Overbite: Perpendicular lines are drawn from incisal edge of upper and lower incisors to True vertical distance line (TVL) and the distance between these two perpendicular lines are measured.


Figure Image is Available in PDF Format


Fig:6 Soft tissue assessment


Soft tissue thickness:

Upper lip(ULT): measured from inside of upper lip to upper lip anterior.

Lower lip(LLT): measured from inside of lower lip to lower lip anterior or vermilion-cutaneous junction.

Pogonion –chin(PCT): measured from hard tissue pogonion (Pog) to soft tissue pogonion (Pog).


Soft tissue lengths:

Upper lip length: distance between the projection of subnasale to TVL and projection of upper lip inferior to TVL.

Lower lip length: distance between the projection of lower lip inferior to TVL and projection of soft tissue menton(Me’) to TVL.


True Vertical line projection: this gives thickness of overlying soft tissue in relation to TVL.

High midface: (i)Glabella(G’) to TVL.

Maxillary projections:

(i) Nasal tip (NT)to TVL

(ii) Soft tissue point A (A’) to TVL


Mandibular projections:

(i) Lower lip anterior (LLA) to TVL

(ii) Soft tissue point B (B’) to TVL

(iii) Soft tissue pogonion (Pog’) to TVL

(iv) Throat length: neck throat point (NTP) to soft tissue pogonion (Pog’)

Upper lip angle: angle formed between tangent to upper lip anterior to TVL

Nasolabial angle: angle formed between tangent to upper lip anterior, subnasale and columella.


Figure Image is Available in PDF Format


Fig: 5 Composite Cephalometric analysis for Orthognathic surgery


Discussion

COGS do not offer a complete diagnostic assessment of both anteroposterior and vertical skeletal dysplasias. Diagnostic methods that are currently used are unable to “pinpoint” where the skeletal discrepancy exists or the magnitude of that discrepancy. The quadrilateral analysis shows that this is a vertical problem only and not an anteroposterior disharmony in jaw size (Di Paolo, R. J. et al., 1983). Arnett’s Soft tissue cephalometric analysis is a method for quantifying facial disharmony and identifying its underlying cause. This is important because, as a rule, improved facial aesthetics are achieved if the underlying problems are identified and treated (Arnett, G. W. et al., 1999). Hence, an attempt is made to study the advantages and disadvantages of these three widely used analysis and present it in a compact manner for better diagnosis. The standardized values for the Composite Cephalometric Analysis for Orthognathic Surgery (CCAOS) are being listed in Table I.


Conclusion-

The orthognathic surgical cases require proper planning and implementation of the treatment strategies. One cephalometric analysis cannot yield the proper inference for planning the surgical procedures hence these three analysis tracings which are widely used were simplified henceforth, saving a lot of time for the clinician, patient as well as for the proper outcome of the treatment.


References

  1. Rakosi, T., Jonas, I., & Graber, T. M. (1993). colour atlas of dental medicine- Orthodontic diagnosis, Thieme publications1993.

  2. Chew, M. T. (2005). Soft and hard tissue changes after bimaxillary surgery in Chinese Class III patients. The Angle Orthodontist75(6), 959-963.

  3. Burstone, C. J., James, R. B., Legan, H., Murphy, G. A., & Norton, L. A. (1978). Cephalometrics for orthognathic surgery. Journal of Oral Surgery (American Dental Association: 1965)36(4), 269-277.

  4. Di Paolo, R. J., Philip, C., Maganzini, A. L., & Hirce, J. D. (1983). The quadrilateral analysis: An individualized skeletal assessment. American journal of orthodontics83(1), 19-32.

  5. Arnett, G. W., Jelic, J. S., Kim, J., Cummings, D. R., Beress, A., Worley Jr, C. M., ... & Bergman, R. (1999). Soft tissue cephalometric analysis: diagnosis and treatment planning of dentofacial deformity. American Journal of Orthodontics and Dentofacial Orthopedics116(3), 239-253.

  6. Legan, H. L., & Burstone, C. J. (1980). Soft tissue cephalometric analysis for orthognathic surgery. Journal of Oral Surgery (American Dental Association: 1965)38(10), 744-751.

  7. Lundström, A., & Lundström, F. (1995). The Frankfort horizontal as a basis for cephalometric analysis. American Journal of Orthodontics and Dentofacial Orthopedics107(5), 537-540.


Table I : The standard values for the Composite Cephalometric Analysis for Orthognathic Surgery






NORMS

FEMALE±SD

MALE±SD

Horizontal skeletal



1)N-A

-2 ± 3.7mm

0±3.7mm

2)N-B

-6.9±4.3mm

-5.3±6.7mm

3)N-Pog

-6.5 ±5.1mm

-4.3±8.5mm

B.

Vertical(skeletal, dental)



1)PNS-N

50.6±2.2mm

53.9±1.7mm

2)MP-HP Angle

24.20±50

230±5.90

3)Upper incisor to NF

27.5±1.7mm

30.5±2.1mm

4)Lower incisor to MP

40.8±1.8mm

45±2.1mm

5)Upper molar to NF

32±1.9mm

35.8±2.6mm

6)Lower molar to MP

32±1.9mm

35.8±2.6mm

C.

Skeletal


1)Maxillary bony base length

50.9±2mm

2)Mandibular bony base length

50±2.5mm

3)Discrepancy

N/M

4)Posterior legs of maxilla

N/M

5)Posterior legs of mandible

N/M

6)Lower anterior facial height

60±3.5mm

7)Lower posterior facial height

39.4±2.2mm

8)Upper anterior facial height

49.2±2.3mm

9)Maxillary incisor position

5±1mm

10)Mandibular incisor position

2±1mm

11)Chin position

0±2mm

12)Angle of convexity

169.5±3.20

D.

Dentoskeletal factors



1)Overjet

3.2±0.4mm

3.0±0.6mm

2)Overbite

3.2±0.7mm

3.2±0.7mm

E.

Soft tissue thickness



1)Upper lip

12.6±1.8mm

14.8±1.4mm

2)Lower lip

13.6±1.4mm

15.1±1.2mm

3)Pogonion-chin

11.8±1.5mm

13.5±2.3mm

F.

Soft tissue lengths



1)Upper lip

21±1.9mm

24.4±2.5mm

2)Lower lip

46.9±2.3mm

54.3±2.4mm

G.

True vertical line projection



1)Glabella

8.5±2.4mm

-8±2.5mm

2)Nasal projection

16±1.4mm

17.4±1.7mm

3)Soft tissue point A

0.1±1.0mm

-0.3±1.0mm

4)Upper lip anterior

3.7±1.2mm

3.3±1.7mm

5)Upper lip angle

12.1±5.10

8.3±5.40

6)Nasolabial angle

103.5±6.80

106.4±7.70

7)Lower lip anterior

1.9±1.4mm

1±2.2mm

8)Soft tissue B point

5.3±1.5mm

7.1±1,6mm

9)Soft tissue pogonion

2.6±1.9mm

-3.5±1.8mm

10)Chin throat length

58.2±5.8mm

61.4±7.4mm


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