Abstract:

KeyWords:

Introduction

Use of Panoramic radiographs for evaluation of Dento-facial characteristics

- A comparative study

Authors:

Dr. Ulrika Diana Pereira, MOS Former Post Graduate Student Dept. of Orthodontics& Dentofacial Orthopedics A.B.Shetty Memorial Institute of Dental Sciences

M anga lore.

Dr. M.S. Ravi, MOS; M.Orth.RCS(Eng); 0 10 8

Professor, Dept. of Orthodontics & Dentofacia l Orthopedics A.B .Shetty Memorial Institute of Dental Sciences Mangalore- 575018. Karnataka. Phone: 0984522 1386, 0824-2204572 Fax: 91-824-2204776 Email : drmsravi@yahoo.com

The most commonly used diagnostic aids used in orthodontics are the lateral cepha logram and the Panoramic Radiograph (OPG). While the lateral cephalogram is used for a quantitative description of the skeleta l and dental status of an individual, the OPG is an indispensable orthodontic screening tool in providing information about the teeth, their axial inclinations, maturation periods and surrounding tissues.' This is mostly qualitative in nature. The purpose of this study was to determine whether the use of OPG cou ld be extended for evaluating Dento-facial characteristics. '

A total of 60 subjects (30 males and 30 females) w ith Class I skeletal and dental relationship were chosen. The lateral cepha logram and OPG were made under standard conditions and various parameters were measured and compared.

The measurements obtained from the OPG when compared with their lateral cephalometric alternatives showed mild stati stically significant differences. But with the help of the regression equations obta ined from this study it is possible to determine the fo llowing cephalometric parameters using their panoramic constants respectively i.e. Go-Gn/S-N using OCOND, ANS-PNS/Go-Me using OCOND and Co-Go/Go-Me using OMAND with a predictability percentage of 15.8%, 7.8% and 10.1 % respectively.

OPG, Skeletal , Cephalogram, Dento-facial characteristics

Panorami c radi ograp hy is frequ entl y used i n orthodontic practi ce to provide important informati on about the teeth, their ax ial incl inations, maturation periods and surrounding ti ssues'. Thi s is usually the technique of choice because of its relati vely low radiation exposure, degree of pati ent comfort and the

significant amount of diagnostic information obtained by viewing all the teeth and basa l bone at once' .

The fi lm permits a determination of the number of teeth present (w ith some caution) and their positions and evaluation of gross osseous changes in the condyles and is quite helpful in asymmetry cases. The relation

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between structures are accurately depicted so that the clini cian may compare the relationship of teeth with one another and to other structures.]

One of the first methods to analyze panoramic radiographs was introduced by Levandoski in 1991 and since then very few studies have been done on this subject. Furthermore studies examining panoramic radiographs as a means of investigating skeletal patterns are lacking in orthodontic literature.'

Elaborative analysis of structural and spacial relationship of various dentofacial structures is an essential part of orthodontic diagnosis and treatment planning. Lateral cephalograms are constantly being used for the analysis of skeletal relationships. Various authors have proposed different ways and means of analysing the dental, skeletal and soft tissue relationships.

As OPG is also another radiograph made routinely as part of orthodontic diagnostic procedure, it would be clinically ideal if certain insight be obtained regarding the skeletal pattern by analyzing the OPG, though it may not be a substitute for the detailed lateral cephalometric analysis.

Therefore the purpose of this study is to determine whether their usage could be extended for evaluating craniofacial characteristics.

The study was thus designed with the following aims and objectives:

1. To compare the evaluation of Dento-facial characteristics using both panoramic and cephalometric radiographs

2. To investigate the possibility of enhancing the clinical versatility of the panoramic radiographs which is an indispensable tool for Orthodontic diagnosis &treatment Planning.

Materials and Methods The study was designed to determine whether the usage of panoramic radiographs could be extended for evaluating Dento-facial characteristics. Panoramic radiographs and lateral cephalograms of the 60 subjects (30 males and 30 females) were selected according to the following criteria.

• Subjects in the age group of 18-25 years

• Class I Skeletal and class I Dental relationship with an over jet and overbite in the range of 2-4 mm. with orthognathic profile

• No asymmetry, crowding or spacing

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• Full complement of teeth, up to 2nd molars should be present

• No history of prior orthodontic and or surgical treatment.

The radiographs were made in standardized conditions with the clinical Frankfort horizontal plane (flip) kept parallel to the floor and the mid facial plane kept in a vertical position using the Planmeca PM 2002 CC Proline machine(80 kv max/total filtration 2,5mm AL).

Orthopantomographs (Fig.l) :

Tracing was done on acetate paper using a 0.5 mm lead pencil. A single operator performed all the tracing in a standardized manner to avoid errors due to inter operator variations. Angular measurements were made to 0.50

accuracy. Measurements on panoramic radiographs were made for both the left and the right sides.

The bite plate used while making a panorami c radiograph altered the occlusion. Therefore independent reference planes were set up in the maxilla and the mandible on the panoramic images. FHP was constructed between meatus acusticus extemus (Mae) and orbital points and a reference plane was drawn between the intersection Point of the ascending and descending tangents on the mandibular canal (MO and foramen mentale (FMe).

The following panoramic landmarks were identified

Landmarlcs Significance

Or Orbitale: the lowest point on the inferior rim of the orbit.

Mae Meatus acusticus extemus: location of external auditory meatus

Co Condylion

ANS Anterior nasal spine: anterior tip of the sharp bony process of the maxilla at the lower margin of the anterior nasal opening

Me Menton: lowest point on the symphysis shadow of the mandible.

FMe Foramen mentale

MC Mandibular canal: perpendicular to lower border of the mandibular canal from the intersection of lower and upper canal; angents is considered to be a stable infrabony structure

U6 Distobuccal cusp on the upper first molar

L6 Distobuccal cusp on the lower first molar

Ul Contact point of maXillary incisors

L1 Contact point of mandibular incisors

The following reference planes were then drawn: Mae- Or: Frankfortls horizontal plane Co·MC: Condytar plane MC·FMe: Mandibular canal plane MC·Me: Corpus line

The various angular measurements determined:

Measurements Significance

FH/ANS Relationship of Frankfort's horizontal to anterior nasal spine

OMAND (Co.MGMC-Me) Panoramic alternative of cephalometric gonial angle

FH/UOP (FH/U6-Ul) Angle between Frankfort's horizontal and maxillary occlusal planes

FH/lOP(FH/l6-l1 ) Angle between Frankfort's horizontal and mandibular occlusal planes

UOCCl(U6-U l-U6) Maxillary occlusal angles

lOCCl(l6-l1-l6) Mandibular occlusa l angles

OCOND (Co-MGFme-MC) Panoramic radiograph alternative of condylar inclination angle

OMID(FH/U1) Angle between Frankfort's horizontal plane and maXillary incisors

Lateral Cephalograms ( Fig.2):

Tracing was done on acetate paper with a 0.5 mm lead pencil as done with OPG. The following cephalometric landmarks were identified:

Landmarks Significance

S Sella: geometric center of pituitary fossa

N Nasion: most anterior aspect of the frontonasal suture

Or Orbitale: lowest point on the inferior rim of the orbit

ANS Anterior nasal spine: anterior tip of the sharp bony process of the maxilla at the lower margin of the anterior nasal opening

PNS Posterior nasal spine: posterior spine of the palatine bone constituting the hard palate

A-POINT Subspinale: most posterior midline point on the concavity between anterior nasal spine and the prosthion.

UI Incisa l edge of maxi llary incisor

LI Incisa l edge of mandibular incisor

U6 Distobuccal tubercule of maxillary fi rst molar

l6 Distobuccal tubercule of mandibular fi rst molar

Gn Gnathion: midpoint between pogonion and menton

Me Menton: lowest point on the symphysis shadow of the mandible

The fo llowing reference planes were drawn:

• S-N: Anterior cranial base

• Mae-Or: Frankfort's horizontal

• ANS-PNS: Palatal plane

• L6-L 1: Lower occlusa l p lane

• U6-U1: Upper occlusa l plane

• Go-Gn: Manbdibular plane

• Go-Me: Mandibular plane

• Co-Go: Ramal plane

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Figure 1 : Landmarks in Orthopantomogram

I. OrbllJ\e 2. Meatus AcUSIlcus Ex!ernus 3. AnI .. 10< asal Spine 4. MCfltoo S. foramm Menf.)l~ 6. M.1OOIOOlar Canal

7. OiSlobucc.,1 Cusp of Upper lSi Molar 8. Oislobucc.,1 Cusp of lower t Sf Molar 9. onlXl Point of Upper Incisors

10. onIX! Point of lower Incisors 1 I. ondyUon

Figure 2 : Landmarks on Lateral Cephalogram

I. Sell. 2. aslon 3. OrbItale ~ . Anterior asal Spine 5. POSIerior 3s.>1 Spine

6- $ubstlinale 7. Incis.11 Edge of ~xillary Incisor 8. Incisal Edg of "",OOiOOI." lncilOr 9. Oistobucc~1 Cusp of Maxillary FirSl .... loIar

10. Oistobucal Cusp of M.,OOIbul." FlBI Molar

11 . Crolhioo 12. ~nlon

13. Gonion 14. M~atus AcuSii us Ex,ernus 1 S. Condyhon

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The following angular measurements were measured:

Landmarks Significance

SNA Relation of the anterior portion of the maxilla to cranial base

SNB Relation of the anterior portion of the mandible to cranial base

ANB Relation of maxilla and mandible

S-N/N-ANS Relation of cranial base to anterio r nasa l spine

Co-Go/Go-Ms Condylar inclination angle

ANS-PNS/Go-Me Relation of palata l plane to mandibular plane

FH/UI Relation of Frankfort's horizontal to the upper incisor

FH/ANS-PNS Relation of Frankfort 's horizontal to pa latal plane

Co-Go/Go-Me Gonial angle

Go-Gn/S-N Relation of mandibular plane to crani al base

FH/U6-U l Angle between Frankfort's horizontal and max. occlusa l planes

FH/L6-Ll Angle between Frankfort 's horizontal and mand. occlusa l plane

Stati st ical analysis was done to determine whether there was any di fference observed between male and female subjects in the parameters measured. Student t test was used to determine this.

- -XI -XZ t = -'---=-

SE w here

The mea n va lues and standard dev iati ons of the parameters were ca lcul ated for the panorami c radiographs and the lateral cephalographs. A paired t-test was performed to determine whether there were any di ffe rences between th e left and ri ght measurements on the panoramic radiographs.

X-a X t =-- = --

s/Fn s/Fn

x is the mea n di fference in eac h set of paired observa ti ons, s is the standard devia ti on of th e difference and n is the number of observations.

A correlati on test was performed on both sides to test the similarity between them. The correlations between the mean va lues of the panoramic measurements and their cephalometri c correspondents were obtained. Regression equat ions were set for the significa nt correlati ons. Thus it was possib le to calculate the signi fica nce level, percentage and predictability of cephalometric data from panoramic radiographs.

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RESULTS Lateral cephalograms and Orthopantomographs were made for a total of 60 subjects (30 males and 30 females) with Skeletal class I and Dental cl ass I occlusion. These were recorded with the objecti ve of eva luating and comparing craniofacial characteristics and to investi gate the poss ibility of enhancing the clinica l versatility of the panoramic radiographs.

FHI ANS (Relation of Frankfort's horizontal to anterior nasal spine): Statistically no significant difference was found between males and females. ITable IVI . A mean difference of 1.450 w ith standard deviation of 1.711 63 was noted between right and left sides w hich was very highly significant (0.001 ) ITable VI. On correlation with cephalometri c read ings it was found that FH/ANS showed a positive correlation with relation of palatal plane to mandibular plane (.081 ) and relation of cranial base to mandibular plane (.206). It showed a negative correlation to the cephalometric gonial angle (-.11 5) and condylar inclination angle (-. 150) ITable VI].

OMAN 0 (Panoramic alternative of cephalometric gonial angle): Statisticall y no signifi cant difference was noted between mal es and females ITab le IVI. On comparison of the right and left sides a mean of .5833 and standard deviati on of 4.11402 was ca lculated which was found to be statistically insignifi cant ITable VI. On correlation with cephalometric readings it was found that OMAND showed a positi ve correlation with cephalometri c condylar inclination angle (.318)' relation of mandibular plane to cranial base (.2 1 0) and

relation between palata l plane and mandibular plane (. 165), Therefore OMANO could be used as a panoramic alternative to measure the cephalometri c gonial angle using the followi ng regression equation i ,e, Co-Go/Go-Me = 72,864 (±19.425) + 10,367 (±, 144)1 OMANO, This showed a prediction va lue of W,l %,

FHA/OP (Angle between Frankfort's horizontal and maxillary occlusal plane) : On stati sti ca l comparison between males and fema les no signif icant difference was found within the sample ITable lVI , On comparison between the right and the left sides a mean of ,1 50 and standard deviation of 2,64142 was calcu lated wh ich was found to be statistica lly insignificant ITable VI, On correlation with cephalometric readings it was found that FH/ UOP showed a positive corre lation with cephalometric angle between Frankfort's hori zontal and maxi llary occlusal planes (,125) ITable VIII, On correlation with panoramic angle between Frankfort's horizontal and mandibular occlusal plane it showed a positive correlation (.415) ITable Villi, This was found to be statistica ll y very highly significant wh ich meant that with an increase in the maxillary occlusa l plane th ere was subsequent increase in the mandibular occlusa l plane,

FH/ LOP (Angle between Frankfort's horizontal and mandibular occlusal planes): On statistical comparison between males and females no sign ificant difference was noted within the sample ITable lVI , On comparison between the right and left sides a mean of 1,667 with standard deviation of 2.40527 was measured w hich wa s found to be statist ica ll y very highly significant (0,001 ) ITab le VI, On correlation w ith cepha lometric values FH/LOP showed a positive correlation with angle between Frankfort's horizonta l and lower ocelusal plane (, 270) ITable VII I,

OCONO (Panoramic radiograph alternative of condylar inclination angle): O n statistical comparison of males and females no significant difference was noted within the sample ITable lVI, O n compari son between the right and the left sides a mean of 1.3833 and standard deviation of 6, 12605 was measured whi ch was found to be statist ica lly insignificant ITable VI , On correlation with cephalometric values it showed a negative correlation with condy lar inclination angle (-.305 ), palatal plane to mandibular plane (-,279) and relation of crania l base to mandibular plane (-,397) ITable VII, Therefore OCONO can be used as a panoramiC alternative to determine cephalometri c relation of cranial base to mandibular plane and palatal plane to mandibu lar plane wi th the following regression equations respectively,

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Go-Gn/S-N= 49.711 (±7, 126)-10.46 (±, 139)1 OCONO

ANS-PNS/Go-Me = 34,278 (± 5,829) - 10,253 (±,1 14)1 OCONO

OMID (angle between Frankfort's horizontal and maxillary incisors): O n statistica l comparison between males and females no significant difference was found w ithin the sample ITable lVI, O n comparison between right and left sides a mean of 1,8667 and standard deviation of 2,38261 was calculated which was found to be statist ica ll y very highly significant ITable VI, On correlation with cepha lometric parameters it showed a positive correlation (.458) ITable VIII

Table I: Mean and standard deviations calculated for parameters measured from 60 lateral cephalograms

Parameters No, Mean Standard (Degrees) Deviation

(Degrees)

SNA 60 81.7333 3,86583

SNB 60 79,2833 3,83159

ANB 60 2.4667 1.33362

S-N/N-ANS 60 85.7000 4,15912

Co-GoiGo-Me 60 122.4167 5.34660

ANS-PNS/Go-Me 60 21.41 67 4.47703

FH/U1 60 26.4000 2.46467

Gonial Angle 60 123,2667 6,39085

FH/ANS-PNS 60 2.7167 1.76685

Go-Gn/S-N 60 26,3167 5,72681

FH/U6-U 1 60 7.3833 4,05091

FH/L6-Ll 60 4.4500 2,98258

Table II: Mean and standard deviations calculated for parameters measured from 60 OPC

Parameters No. Mean Standard (Degrees) Deviation

(Degrees)

FH/ANS (RIGHT) 60 12 ,0667 .34679

FH/ANS (LEFT) 60 10,6167 ,36211

OMAND (RIGHT) 60 135,150 ,57824

OMAND (LEFn 60 134,5667 ,72071

FH/UOP (RtGHn 60 3,2333 ,29050

FH/UOP (LEFn 60 3,0833 ,24390

FH/LOP (RtGHn 60 5.7000 ,38349

FH/LOP (LEFT) 60 4,0333 ,34524

UOCCL 60 166,800 10,15106

LOCCL 60 161.533 7,84266

OCOND (RtGHn 60 51,5667 .76371

OCOND(LEFn 60 50,1833 ,73895

OMtD (RtGHn 60 22 ,5167 ,37619

OMtD (LEFn 60 20,6500 ,34348

Table III : Comparison between males and females of the parameters measured from lateral cephalograms using Students t test.

Standard

Parameters Sex No. Mean Deviation T

(Degrees) (degrees)

SNA Male 30 81.8667 4.09148 .265

Female 30 81.6 3.69156 P=.792

SNB Male 30 79.7 3.99267 .840

Female 30 78.8667 3.68345 P=.404

ANB Male 30 2.1667 1.28877 1.774

Fema le 30 2.7667 1.33089 P=081

S·N/N-ANS Male 30 85.8 4.70070 .185

Fema le 30 85.6 3.61606 P=854

Co·Go/Go·Me Male 30 122.3333 5.40328 .120

Female 30 122.5 5.38036 P=.905

ANS-PNS/Go-Me Male 30 21.1333 4.56171 .487

Female 30 21.7 4.4501 1 P=.62S

FH/Ul Male 30 26.2333 2.73777 .52 1

Female 30 26.5667 2. 19220 P=.605

Gonial Angle Male 30 122.8333 6. 19835 .522

Female 30 123 .7 6.65479 P=.604

FH/ANS-PNS Male 30 2.8667 1.81437 .654

Female 30 2.5667 1.73570 P=5 15

Go-Gn/S-N Male 30 25.4 5.75715 1.246

Female 30 27.2333 5.64271 P=.215

FH/U6·Ul Male 30 6.8 3.87209 1.118

Female 30 7.9667 4.20577 P=265

FH/L6-L 1 Male 30 4.1 2.83269 .908

Female 30 4.8 3.13380 P=.368

No statistically significant difference was noted between the male and female samples.

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Table IV: Comparison between males and females parameters measured of the from panoramic radiographs using Students I test

Standard Parameters Se. No. Mean Deviation T

(Degrees) (degrees)

FH/ANS (RIGHT) Male 30 11.8667 2.75097 .573

Female 30 12.2667 2.65 139 P;.568

FH/ANS (LEFn Male 30 10.7 2.69290 .228

Female 30 10.5333 2.95639 P;.820

OMAND (RIGHT) Male 30 135.2333 4.70277 .143

Fema le 30 135.0667 4.32262 P;887

OMAND (LEFn Male 30 134.4667 5.69775 .138

Fema le 30 134.667 5.56053 P;891

FH/UOP (RIGHn Male 30 3.3000 2.40903 .228

Fema le 30 3. 1667 2.11861 P;.821

FH/UOP (LEFn Male 30 3.3000 2.16795 .887

Fema le 30 2.8667 1.56983 P;.379

FH/LOP (RIGHT) Male 30 5.1667 2.92532 1.40

Fema le 30 6.2333 2.96745 P;. 166

FH/LOP (LEFT) Male 30 4.0667 2.92355 .096

Female 30 4.0000 2.44949 P;924

UOCCL Male 30 168.5333 8.5 1665 1.331

Female 30 165.0667 11.4408 P;189

LOCCL Male 30 162.4667 8.34900 .921

Fema le 30 160.6000 7.32309 P;.361

UCOND (RIGHn Male 30 51.7333 6.24739 .216.0

Female 30 51.4000 5.66660 P;.829

OCOND (LEFn Male 30 51.7000 5.76045 2.112

Female 30 48.6667 5.35842 P; .039

OMID(RIGHn Male 30 22.2333 2.89689 .750

Fema le 30 22.8000 2.95250 P;.456

OMID (LEFT) Male 30 20.9667 2.68435 .921

Female 30 20.3333 2.64358 P;.361

No statistically Significant difference was noted among the male and female sample.

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Table V: Comparison between right and left sides of parameters measured from 60 panoramic radiographs using paired sample test.

Parameters Mean Standard T P (Degrees) Deviation

(Degrees)

FH/AN5(RIGHT)-FH/AN5 (LEFT) 1.450 1. 71 163 6.562 .001

OMAND(RIGHT)- OMAND (LEFn .5833 4.11402 1.098 .277

FH/UOP (RIGHT)-FH/UOP (LEFn .1500 2.64142 .440 .662

FH/LOP(RIGHT)-FH/LOP (LEFn 1.667 2.40527 5.367 .00 1

OCOND (RIGHn-OCOND (LEFn 1.3833 6. 12605 1.749 .085

OMID(RIGHn-OMID (lEFn 1.8667 2.3826 1 6.069 .001

Comparison of OPG parameters between right and left sides showed a non significant difference for all parameters except FH/ANS which showed a mean di fference of 1.450, standard deviation of 1.71163 and stati sti ca ll y was very highly significant (.001). FH/lOP showed a mean difference of 1.6667, standard deviation of 2.40527 and was statisti ca lly very highly significant (p=.OOl ). OMID showed a mean difference of 1.8667, standard deviation of 2.38261 and was very highly significant (p=.001).

Table VI: Correlation of skeletal parameters between OPG and cephalometric readings

Parameter Correlation coefficient P value

1 OMAND Vs Co-Go/Go-Me .318 0 .013

2 OMAND Vs Go-Gn/S-N .210 0.108

3 OMAND Vs AN5-PNS .165 0.209

4 OCOND Vs Co-Go/Go-Me -.305 0.018

5 OCON D Vs AN5-PNS/Go-Me -.279 0.031

6 OCOND Vs Go-Gn/S-N -.397 0.002

7 FH/ANS Vs ANS-PNS/Go-Me .081 0.537

8 FH/ANS Vs Co-Go/Go-Me -.115 0.380

9 FH/ANS Vs Go-Gn/S-N .206 0.114

10 FH/ANS Vs Gonial Angle -.150 0.253

On correlation of skeleta l parameters between OPG and lateral cephalograms a negative correlation was observed for OCOND Vs Co-Go/Go-Me, OCOND Vs ANS-PNS/Go-M e, OCOND Vs Go-Gn/S-N, FH/ANS Vs Co-Go/Go-Mc and FH/ANS Vs Gonia l angle. The rest of the parameters showed a pos itive correlation.

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Table VII: Correlation of Dental parameters between OPC and Cephalometries readings

Parameter Correlation coefficient P value

I UOOCL Vs FH/U6-U1 .032 .806

2 UOCCL Vs FH/U1 -.033 .804

3 FH/UOP Vs FH/U6-U 1 .125 .342

4 LOCCL Vs FH/L6-L 1 -.121 .359

5 FH/LOP Vs FH/L6-L 1 .270 0.037

6 OMID Vs FH/U1 .458 0.001

Among the dental parameters compared between OPG and lateral cephalograms, a negative correlation was observed in UOOCL Vs FHAjl and LOCCL Vs FH/L6-L 1. The rest of the parameters showed a positive correlation.

Table VIII: Correlation between UOCCL and LOCCL of OPC readings

Parameter Correlation Coefficient P value

I UOCCL Vs LOCCL .765 .001

2 FH/UOP Vs FH/LOP .415 .001

The maxillary and mandibular occlusal planes showed a positive correlation. This was found to be statistically very highly significant.

Table IX: Regression equations

Parameter Panoramie Constant

RE I Go-Gn/S-N OCOND

RE2 ANS-PNS/Go-Me (PP/MP) OCOND

REJ Co-Go/Go-Me OMAND

DISCUSSION OPG is one of the essential diagnostic aids used as a part of the investigations during orthodontic diagnosis and treatment planning. It is mainly used for the study of bone pattern, bone and root pathology, presence of supernumerary teeth, root shape and size, eva luation of TM], right and left symmetry etc. Its main advantage lies in the eva luation of both maxillary and mandibular arches wi th temporomandibu lar joints and their supporting structures. In addition to these benefits it is highly advantageous if skeletal relationships can also be assessed using an OPG, thereby minimizing the

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Predictors R'

Go-Gn/S-N- 49.71 1-0.46 OCOND 15.8%

ANS-PNS;34.278-0.2530COND 7.8%

Co-Go/Go-Me; 72.864+0.367 OMAND 10.1%

requirement of a lateral cephalogram only for extensive skeletal assessments.

There are very few studies involving the use of panoramic radiographs in evaluating dento-skeletal specif ica tions and th ey focus mainl y on intercondylar asymmetri es and gonial angle measurements.' ·s,'."

Skeletal pattern - comparison of skeletal parameters between OPC and lateral cephalogram (Table VI and IX)

The gonial angle (Co-Go/Go-Me) to OMAND (Co-Mc/

Mc-Me) showed a positi ve correlati on, r= 0.31.' This in accordance w ith the study by Keiji Mati a et al8 in w hich they eva luated the gonial angle (OMAN D) from

the OPG and the lateral cephalograms and suggested that they could be determ ined w ith the same degree of accuracy. They also suggested that the right and the left gonial angles ca n be quite eas il y determined individually from OPG thus avoiding the disturbing infl uence of the superimposed images found on lateral cephalograms. Thus OPG is a more obvious choice for determination of the gonial angles.

The palatal plane to mandibular plane angle (ANS­

PNS/Go-Me) in the cephalogram showed a negative correlation with OCON D (Co-Md M c-FMe) in the OPG r=-0.279, indi ca ting that as th e Palatal pl ane/ mandibular plane increased there is a corresponding decrease in the OCOND. Th is is in accordance w ith the findings of Akcam et aI. ' Thi s indicates that the pa latal plane! mandibular plane can be predicted w ith a reasonable degree of accuracy using the OCON D from the OPG. The predict ion va lue R2 was found to be 7.8%.

The mandibular plane angle (Go-Gn/S-N) to OCOND (Co-Mc/Mc-F Me) in the O PG showed a negati ve correlation, r = -0.397. This is similar to the findings of the study by Akcam et' all where the mandibular plane ang le in th e ceph alog ram in creased w ith a corresponding decrease in the OCOND of the OPG. This decrease can be predicted w ith accuracy as shown by the predicti on va lue R2 which was found to be 15.8%. Thus the level of prediction is high enough for the poss ibility of predi cting th e ceph alometri c parameters from the panoramic measurements.

The condylar inclination angle (Co-Go/Go-Me) from the lateral cephalogram showed a positi ve correlation r =0.3 18 w ith OMAND (Co-Mc/Mc-Me) in the O PG. This is in accordance w ith the study conducted by Akca m et ai ' in w hich they determined that the condylar inclinati on angle ca n be predi cted w ith reasonable certainty from the OMAND of the OPG.1 In the present study a pred iction va lue R: of 10.1 % was noted.

The prediction of the lateral cephalometric va lues from the O PG parameters ca n be done by using the

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regress ion equati ons obtained through the stati sti cal analyses .

Go-Gn/S-N = 49.711 (±7.126) - 0.46 (±.139)· OCOND

ANS-PNS/Go-Me = 34.278(±5.829) -0.253(±.1 14)'

OCON D

Co-Go/Go-Me = 72.864 (± 19.425) + 0.367 (±.144) •

OMAND

Comparison of OPG parameters between right and left (Table V)

Skeletal parameters

Compari son of OMAND (panoramic altern ati ve of gonial angle) and OCON D (panoramic alternative of condylar inclinati on angle) between the right and left sides in the OPG were stati sti ca ll y insigni ficant. which

differs from the results obtained by Akcam et al'

Dental parameters

Comparison of FH/UOP (angle between maxi llary

occlusa l planes) between the right and left sides in the O PG were stati stica lly insignificant.

Tooth angulations and inclinations- comparison of Dental parameters between OPG and lateral cephalogram ( Table VII and VIII)

The UOCCl (U6-Ul-U6, the angle formed by the molars of both sides with the incisors) of the O PG

was correlated w ith the FH/ U6-Ul (Frankfort's horizontal plane to the plane joining upper first molar and central incisor) and the FHAI1 (Frankfort's horizontal plane to the plane joining upper central incisor) angles in Lateral cephalograms.

The r va lues were found to be

r = .032 for UOCCL w ith FH/U6-U 1

r = -.033 for UOCCL with FH/U1-Po

This indicates a mild pos iti ve correlati on between UOCCL and FH/U6-U1 and a mild negati ve correlation between UOOCL and FH/ U1 . In thi s study the FH/UOP and FH/U6-U 1 were pos iti vely correlated, r = 0.39.

LOCCl angle (L6-Ll-L6) in O PG was nega ti ve ly correlated w ith FH/ L6-L 1 (Frankfort's horizontal plane to the plane joining lower first to the lower central

incisor of the lateral cephalogram}, r = -0. 121. In thi s

study a significant positive correlation between FH/LO p

and FH/L6-L 1, r =0.270 was found.

The correlation shows that UOOCL, FH/UOp, FH/LO p

and OMID can be used to predict FH/U 1, FH/U6-U 1,

FH/ L6- L 1 respec t ive ly ut i li zi ng co rres pond i ng

regression equations.

On completion of this study it can be noted that on

comparison of the skeletal parameters between the

ope and lateral cephalograms parameters such as the

gonial angle to the OMAN D (panoramic alternative),

palata l plane: mandibular plane to the OCON D and

mandibular plane angle to OCON D all produced

stat istica ll y significant va lues and wi th the help of the

regression equations obta ined, o pe could be used to

determine the skeleta l relationship wi th a certai n degree

of predictabi li ty. On compari so n of th e den tal

parameters it was seen that the following panoramic

parameters i.e. UOCCL (upper occlusa l plane), FHI

UOP (angle between FH and maxillary occlusa l planes),

FHI LOP (angle between FH and mandibular occlusa l

planes) and OMID (angle between FH and max illary

incisors) cou ld be used to obtain the fo llow ing

cephalometric measurements i.e. FH/U 1, FH/U6-U 1

and FH/L6-L 1.

On compari son of o pe parameters between the right

and left sides, both skeletal and dental parameters

showed statisti ca ll y insignifi cant di fferences which

meant that measurements could be obtained from one

side on ly.

CONCLUSION On comp letion of the study the fo llowi ng concl usion

can be drawn

t ) The ope can be used in the qu antitat ive

assessment of a malocclusion but the predictability

percentage has been found to be very low; therefore

the cli nician should be quite vigilant in thi s aspect.

2) Angular measurements of the o pe can be used as

a subs titute fo r the co rrespondi ng angul ar

measurements from the lateral cephalogram, both

for dental and skeletal parameters wi th the help of

regress ion equations.

3) Either right or left side measurements in the o pe

can be used for certain parameters instead of

measuring both sides separately, as they are not

sign ificantly different.

24

With standard exposure conditions and high image

qu ality, pano rami c rad iograph s ca n prov ide

information on the vert ica l dimensions of Dentofac ial

structures; however they are not reliable enough to give

acceptably accurate addi tional informat ion compared

wi th lateral cephalograms.

ACKNOWLEDGEMENTS: The Authors sincerely thank Dean & Princ ipal, Prof.

Dr. B. Rajendra Prasad, and Prof. Dr. U.S. Kri shna

Nayak, HO D, Orthodontics, and Dean (Academics),

A. B. Shetty M emorial Institute of Dental Sc iences,

Mangalore for thei r support.

Authors thank Prof. M .S. Koti an, Statist ician, K.M.C;

Mangalore.

BIBLIOGRAPHY 1. Akcam M O, Alti ok T, Ozdi ler E.: Panoramic

radiographs: a tool for investigating skeleta l pattern.

AmJ Orthod Dentofac. Orthop 2003;123 :1 75-81.

2. Weber JSU, Renato RA, Ori va ldo T, Jose FCH .:

Assessment of mesio-distal axial inclination through

panoramic radiography. )CO 1990;24(3) :1 66-73.

3. Fri edl and B.:C l ini ca l ra d io log ical issues in

orthodontic practice. Semin Orthod 1998;4:64-78.

4. Larh etm TA, Sva naes D B. Reproducib ili ty of

rotati onal panoramiC radiography; Mandibular

linear dimensions and Angles. Am J Orthod 1986;

90:45-5 1.

5. Piedra I. : The Levandoski panoramic analysis in

the diagnos is of fac ial and denta l asymmetries. J

Clin Pediatr Dent 1995;20:15-2 1.

6. Turp )C, Vach W, Harbi ch K, Alt KW, Strub JR.:

Determin ing mandibular condyle and ramus height

w ith the help of an orthopantomograms- a va lid

method? J O ral Rehabil 1996;23:395-400.

7. Kubota Y, Takenoshita Y, Taka mori K, et al :

Levandoski pantographic analysis in the diagnOSiS

of hyperplas.a of the coronoid process. Br J Oral

and Max illofac Surg 1999;37:409-1 1.

8. Keiji M, Mikko A, Kaarina H:. Determination of

the gonial angle from the orthopantomograms.

Angle Orthod 1977;47: 107-10.