PRACTICAL APPLICATION OF OVERBITE DEPTH INDICATOR, ANTEROPOSTERIOR DYSPLASIA INDICATOR AND EXTRACTION INDEX.

 

 Dr. Roberto Silva Meza.

 

Universidad Nacional Autónoma de México, campus FES Zaragoza

 

en espanol

 

Introduction.

In 1931, H. Broadbent1 published “A new X-ray technique and its application to orthodontia” giving birth to a new age in,orthodontic diagnosis – the cephalometric era .  However, Bimler2 mentioned that Argentine,Carrea, had used the cephalostat  in 1922 and Hofrat, in Germany in 1931. The cephalostat’s availability stimulated various analyses, diagnostic  and treatment planning systems, e.g., the Downs´ analysis 3 (1948), Steiner, Tweed (1953), Coben, Jenkins (Wits) (1955), Ricketts (1960), Johnston (Wits) (1968), Sassouni, Enlow (1969), Jarabak (1970), Bimler (1973), Kim (1974), Jacobson (Wits) (1975), Legan-Burstone (1980), Mc Namara (1984), and Fastlicht (2000).

Most cephalometric analyses reduce the 3-D face and teeth of the patient’s malocclusion to two dimensions and ordinarily measured in the sagittal plane.Kim4-6 developed a 2-D cephalometric analytic technique that evaluates the pattern of malocclusion from vertical and horizontal points of view, as well as an extraction index that demonstrates whether or not to extract permanent teeth for correction of the malocclusion. The paper , therefore, will present the practical application of this analytical method.

 

 

 

 

Review of literature.

In 1974, Dr. Kim,4after studying cephalograms of 119 patients with normal occlusions and 500 various malocclusions, selected fifteen cephalomteric measurements to determine which produced the highest correlation with the incisal overbite depth. The Overbite Depth Indicator (ODI) is the arithmetic sum of the angle of the A-B plane to the mandibular plane and the angle of the Palatal plane to Frankfort horizontal plane. This study produced a norm of 74.5 degrees and with a standard deviation of 6.07°.  A value of 68° or less indicates a skeletal openbite tendency7. The correlation coefficient of the incisal overbite depth and the ODI found its highest value (0.588) in the malocclusion sample of 500 individuals.  Kim noticed that when the malocclusion fell within the range of normal overbite, the skeletal pattern generally did not deviate from that norm, regardless of the Angle classification. In this study he also noted that the sample had a range and severity of 11mm of overbite and -11mm of openbite. The normal occlusion sample showed ranges of 0.5 mm. to 4 mm. for the incisal overbite depth, with a mean value of 2.8 mm. The ODI analyzes and differentiates open bites and deep overbite with cephalometric values.Later, Kim and Vietas5 analyzed cephalometric measurements in the horzontal plane and developed the Anteroposterior Dysplasia Indicator (APDI), which differentiates the anteroposterior relationship of the malocclusion pattern. Eventually, Kim combined both indicators to compare Class II, Division 1 malocclusions treated orthodontically - with and without the extraction8 of permanent teeth.This study led him to the development of the Combination Factor (CF)6, which joined two measurements into one and gave clinicians a better comprehension of facial balance.Subsequently, he related the Combination Factor with the inter-incisal angle (IIA) and lip protrusion or retrusion.As he used this new cephalometric value to elect to extract teeth or not, he named it the Extraction Index (EI) 6.

 

Method of obtaining the measurements

 

OVERBITE DEPTH INDICATOR
  1. Measure the angle of the mandibular plane(MP), and AB plane. Write it in corresponding rectangle  (MP-AB). (Example: 76°).
  2. Measure the angle of the  Frankfort horizontal plane  (FH), and the Palatal plane (PP). A positive angle occurs when the palate tips downward and forward.  A negative angle occurs when the palate tips upward and forward. In case of a positive value, write it in the corresponding positive rectangle, otherwise, write it in the corresponding negative rectangle  (Example: -3°)
  3. Combine these values to obtain the Overbite Depth Indicator  (76°-3°=73°).
    In this example the ODI is 73 degrees,which is slightly lower than the norm (74.5° ±, 6°); howerver, the diference is 1.5°. Considering the standard deviation, it falls within the normal limit with a sligth tendency to be an openbite.

 

 

 

 

Tracing  ODI.

 

MP-AB = The mandibular plane and the AB plane (Angle).

FH-PP  =  The Frankfort plane and the palatal plane (Angle).

 

Example:

                                                                                      

~

CASE ¯

 

MP-AB

           76°

 

FH-PP

+

>< OK

x

FH-PP

-           3°

> Deep

 

ODI  74.5°±  6°

=        73°

<Openbite

x

 

 

ANTEROPOSTERIOR DYSPLASIA INDICATOR

  1. Measure the angle of the Frankfort horizontal plane (FH) and the Facial plane (NP). Write it in the corresponding rectangle . (Example: 88°)
  2. Measure the angle of the Facial plane (FP) and the A-B plane. A positive angle occurs when point A is back of point B.  A negative angle occurs when point A is forward  to point B.  When positive, write it in the positive corresponding rectangle; otherwise write it in the corresponding negative rectangle  (Example: -6°)
  3. Measure the angle of the palatal plane (PP) to the Frankfort horizontal plane (FH). This measurement was obtained already in No 2 of the ODI section. If the palatal plane angle is positive, write it in the corresponding positive rectangle, otherwise, write it in the corresponding negative rectangle  (Example: -3°)
  4. Once all the values are written, calculate the formula vertically to obtain the Antero-posterior Dysplasia Indicator (88°-6°=82°-3°=79°).  In this example the APDI  is 79°,  sligthly lower than the norm (81.4° ± 3.8°),  with a diference of  2.4° . Considering the standard deviation, it lies within the normal range with a slight tendency to develop into a Class II or unilateral Class II relationship. 

 

Tracing  APDI

 

FH-FP  = The  Frankfort  plane and facial plane (N-Po), (Angle).

FP-AB  = The Facial  plane (N-Po), and the AB plane (Angle).

 

Example:

 

FH-FP

      88°

 

FP-AB

+

 

FP-AB     

-       6°

 

~

=    82°

 

FH-PP

+

>< CL I

x

FH-PP

-       3°

<  CL II

x

APDI  81.4° ± 3.7°

=    79°

> CL III

 

 

 

 

 

COMBINATION FACTOR AND EXTRACTION INDEX.

 
  1. Add  ODI +  APDI  to  obtain the Combination Factor (CF).  (Example: 73° + 79° = 152°).
  2. Measure the inter.-incisal angle (IIA). If it is lesser than the norm  (130°) write in the corresponding rectangle  (Example: 116°) If the  inter-incisal angle (IIA), is greater than the norm (130°) write it in the upper rectangle and calculated the next formula (IIA –130 ÷5 =). If the inter-incisal angle is smaller than the norm (130°)write it in lower  rectangleand calculate the next formula (130 - IIA ÷ 5 =):  (Example: 130 - 116 = 14 ÷ 5 = 2.8 ).
  3. Measure the distance between the lips and the esthetic line in millimeters. When retrusive, write it in the upper rectangle and when protrusive, write it in the lower rectangle. (Example: Upper lip = 2.5 mm retrusive, lower lip = 3 mm. protrusive ) The esthetic line is drawn from the mid-point of the nose to the tip of the soft tissue chin.
  4. After writing the values, tabulate the formula vertically to obtain the Extraction Index:    (73 + 79 =152 -2.8 + 2.5 – 3 =148.7). In this example the Combination Factor, presents a difference of 3.9 with  respect to the   norm (152–155.9=-3.9).  By analyzing the ODI and APDI we find that the APDI  indicates a slight facial imbalance with distocclusion.  The Extraction Index shows a difference and indicates a slight facial imbalance with distocclusion .  The Extraction Index displays a difference of  7.2, which is smaller than the Combination Factor, which clearly indicates a need to extract teeth  ( EI=148.7 , CF=155.9  DIF=7.2 ). Numerous factors other than the skeletal pattern influence the dentition. Myofunctional imbalance, discrepancy in the relative dimension of the dentition to each arch dimension, discrepancy in relative tooth size, congenital absence of teeth, aberrant eruptive patterns and the presence and position of third molars are some of the common and contributory factors to malocclusions5.  Clinicians must also consider these features in conjunction with the Extraction Index before deciding to sacrifice teeth. 

 

 

 

 

                           

 

                  Tracing EI                                                                             Tracing ODI APDI EI

 

 

ODI     =  Overbite Depth Indicator.
APDI   =  Anteroposterior Dysplasia Indicator.
CF       = Combination Factor (Sum of  ODI and APDI).                        
IIA       = Inter incisal Angle .
LP       = Labial Position
EL       = Esthetic Line.
EI        = Extraction Index.

 

 

 

Example:

ODI      74. 5°±  6°
~
73°
APDI    81. 4°±  3.7°
~
+79°
CF  155. 9°
 IIA¯
=152°
x¯   OK    ­
IIA > 130   (IIA - 130) ÷ 5
+
IIA<  130  (130 – IIA ) ÷ 5
116
-2.8
LP EL       Retrusive
+2.5
>< ?
LP EL       Protrusive
-3
>NO EXT
EI
®
=148.7
< EXT
X

 

 

Conclusion: 

This cephalometric analysis helps clinicians identify facial patterns of orthodontic patients that might benefit from extractions.

 

ODI – APDI - EI

 

 

PATIENT__________________________________________  AGE_______

 

OVERBITE DEPTH INDICATOR (ODI)

1. Kim YH. Overbite Depth Indicator: With particular reference to anterior openbite. Am J Orthod 1974;65:586-611

 

~ CASE ¯  
MP-AB    
FH-PP + >< OK  
FH-PP _ > Deep  
ODI  74.5°±  6° = < Openbite  


MP-AB = The mandibular plane and the AB plane (Angle).

FH-PP  =  The Frankfort plane and the palatal plane (Angle). Positive angle implies palate tipped down forward.
Negative angle implies  palate tipped down backward

 

               

 

ANTEROPOSTERIOR DYSPLASIA INDICATOR (APDI)

2. Kim YH, Vietas J. Anteroposterior Dysplasia Indicator: An adjunct to cephalometric differential diagnosis. Am J Orthod 1978;73:619-633

FH-FP
FP-AB
+
FP-AB 
-
~
=
FH-PP
+
>< CL I
  
FH-PP
-
< CL II
  
APDI  81.4° ± 3.7°
=
> CL III
  


FH-FP  = The  Frankfort horizontal plane and facial plane (N-Po), (Angle).
FP-AB  = The Facial plane (N-Po), and the A-B plane (Angle).  A positive angle indicates that point A is behind point B.
 A negative angle indicates that the  point A is forward in relation to  point B.

   


                           

EXTRACTION  INDEX ( EI)

3. Kim YH, et al Overbite Depth Indicator, Anteroposterior Dysplasia Indicator, Combination Factor and Extraction Index  Int J MEAW 1994;1(1):81-104

ODI      74. 5° ±  6° ~      
APDI    81.4 °±  3.7 ~ +    
CF  155. 9°  IIA¯ = ¯     OK    ­
IIA > 130   (IIA - 130) ÷ 5   +    
IIA<  130  (130 – IIA ) ÷ 5   -    
LP EL       Retrusive   + ><     ?    
LP EL       Protrusive   - > NO EXT    
 EI ® = <  EXT    

CF   = Combination Factor (Sum of  ODI and APDI).                        

        IIA  = Inter Incisal Angle.

        LP   = Labial Position.

        EL   = Esthetic Line.

 

                 

~

    Dates :  ®

 

 

 

ODI        

74.5°±  6

 

 

 

APDI    

81.4°± 3.7

 

 

 

CF

155. 9

 

 

 

IIA         

130

 

 

 

LP EL    

Protrusive

 

 

 

LP EL    

Retrusive

 

 

 

 

 

 

 

 

 

References

1.Broadbent HB sr. A new X-ray technique and its application to orthodontia. Angle Orthodontist 1931 ; 1 : 45-46  Reprinted in Angle Orthodontist 1981;51:93-114

2.Bimler H.P. JCO Interviews.Bimler on functional appliances. Journal of Clinical of Orthodontics 1983 Jan ; 17(1):39-49

3.Downs WB. The role of cephalometrics in orthodontic case analysis and diagnosis. American  Journal of  Orthodontics 1952; 38:162-182

4. Kim YH. Overbite Depth Indicator: With particular reference to anterior open bite. American  Journal of  Orthodontics 1974; 65:586-611

5. Kim YH, Vietas J.  Anteroposterior dysplasia indicator: An adjunct to cephalometric differential diagnosis.  American Journal of  Orthodontics 1978;73:619-633

6. Kim YH. Caulfield Z. Nahm Ch W. Chang YII. Overbite Depth Indicator, Anteroposterior Dysplasia Indicator, Combination Factor and Extraction Index. The International Journal of the  Multiloop Edgewise Arch Wire Technic and Research Foundation Sep 1994;1(1):81-104

7.Katsaros C, Berg R. Anterior open bite malocclusion : A follow up study of orthodontic treatment effects. European Journal of Orthodontics 1993;15:273-280

8. Kim YH.  A comparative cephalometric study on class II, Division 1 non-extraction and extraction cases. Angle Orthodontist 1979;49:77-84

 

Dr Roberto Silva Meza

Address:

Roberto Gayol 1255-204

Col Del Valle 03100

Tel 55-590985   

México DF México                          

E-mail   bobsilva@ prodigy.net.mx