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					           DISSERTATION – SYNOPSIS




             Dr. VISHNU BEN LATIF

          POST GRADUATE STUDENT
DEPARTMENT OF ORTHODONTICS AND DENTOFACIAL
               ORTHOPEDICS




A .J. INSTITUTE OF DENTAL SCIENCES, MANGALORE
                    2012 – 2013
 RAJIV GANDHI UNIVERSITY OF HEALTH SCIENCES,
          BANGALORE, KARNATAKA.
                          ANNEXURE – II

       PROFORMA FOR REGISTRATION OF SUBJECTS FOR

                          DISSERTATION


1.   NAME OF THE CANDIDATE         DR. VISHNU BEN LATIF
     AND ADDRESS                   POST GRADUATE STUDENT,
     (In Block Letters)            DEPARTMENT        OF   ORTHODONTICS
                                   AND DENTOFACIAL ORTHOPEDICS,
                                   A.J. INSTITUTE OF DENTAL SCIENCES
                                   MANGALORE

2.   NAME OF THE INSTITUTION A.J INSTITUTE OF DENTAL SCIENCES
                                   MANGALORE

3.   COURSE OF THE STUDY           MASTER OF DENTAL SURGERY
     AND SUBJECT                   IN ORTHODONTICS AND
                                   DENTOFACIAL ORTHOPEDICS.

4.   DATE OF ADMISSION TO
                                     24TH MAY 2012
     COURSE
                                   “ASSESSMENT OF ANTERO-
5.   TITLE OF THE TOPIC            POSTERIOR SKELETAL & SOFT
                                   TISSUE RELATIONSHIPS OF ADULT
                                   INDIAN SUBJECTS IN NATURAL
                                   HEAD POSITION & CENTRIC
                                   RELATION”
6.   BRIEF RESUME OF THE INTENDED WORK

     6.1: Need for the study :

     The desire for improved facial aesthetics is a major driving force for people seeking

     orthodontic treatment, for which accurate and reliable diagnosis is important.

     Cephalometric diagnosis is an inevitable component of orthodontic treatment. We are in

     constant search of methods to fine tune the accuracy of data obtained from

     cephalograms. Orthodontists have been using intracranial reference lines like Sella-

     Nasion (SN) and Frankfort horizontal (FH) planes for analyzing antero-posterior position

     of maxilla and mandible, when it comes to assessing orthodontic and orthognathic

     surgical cases. But these lines do not always coincide with facial esthetics, and they also

     show a tendency towards inter individual discrepancy. Thus, the need of a reproducible

     reference positional plane for diagnostic radiographs is important for the diagnosis and

     treatment of orthodontic patients and two-jaw surgery patients1. It is at this juncture that

     the relevance of natural head position and centric relation comes into the limelight.

     Broca defined natural head position as “when man is standing and his

     visual axis is horizontal, he is in the natural position”.2

     The Natural Head Position (NHP) was introduced into orthodontics in the late 1950s3

     and has been advocated as a craniofacial reference system because of its good intra-

     individual reproducibility to a true vertical plumb line3-5. Another characteristic of the

     NHP is the representation of the true-to-life appearance and ease of registration.

     Therefore, setting up a reliable reference line with the NHP is necessary.
Orthodontists also need to have a reliable and repeatable position of the mandible to

diagnose maxillo-mandibular relationships and occlusion in patients. Centric relation

(CR) is known as the single most repeatable position.1 Glossary of Prosthodontic Terms6

defines CR as a maxillo-mandibular relationship in which the condyles articulate with

the thinnest avascular portion of their respective disks with the complex in the antero-

superior position against the slopes of the articular eminence.



The purpose of this study is to verify the intra-individual reproducibility of the NHP in

CR position, to prove the inter-individual differences in the FH plane and SN line

compared to the True Horizontal Line (THL), and to establish linear norms from A-

point, B-point, Pog as well as soft tissue A-point, soft tissue B-point, and soft tissue Pog

to Nasion true vertical line (NTVL) in adult Indian subjects.
         6.2: Review of Literature

1. Ahn JH et al (2010)1 conducted a study aimed to verify intra-individual reproducibility

of natural head position in adult Korean individuals in centric relation position. The same

study analyzed the inter-individual variability of Frankfort horizontal plane and sella-

nasion line compared to true horizontal line. The study also investigated the correlations

between linear measurements from point-A and point-B to the nasion true vertical line, and

the angular measurements from point-A and point-B to the SN line. Two lateral

cephalograms were taken of 116 subjects -23 males (19 to 41 years) and 93 females(19 to

47 years), using centric relation wax bites in NHP at one week interval. The results

obtained were as thus: Method errors of three variables and intraclass correlation

coefficients of six parameters proved the intra-individual reproducibility of NHP. The

angle of the FH to the THL was not significantly different from 0o, but it was clinically

variable (SD 3.89o) on the inter-individual level. Conversely, the angle of the SN line to

the THL was significantly different from 7o. Very low correlation was found between the

linear measurements and angular measurements of A-point and B-point. They concluded

by saying that NHP can be a useful position for diagnosing orthodontic and orthognathic

surgical cases reproducibly and reliably. Adding that, the NTVL can be used to assess the

antero-posterior skeletal relationship in the NHP and CR instead of the SN line and FH

plane.
2. Madsen DP, Sampson WJ and Townsend GC (2008) 7conducted a study to evaluate

the potential usefulness of a range of craniofacial reference planes to True horizontal

(HOR), including the Krogman – Walker (KW) line, the neutral horizontal axis, the

foramen magnum line, and the posterior maxillary plane. A sample of 57 (38 female, 19

males) consecutive, pre-treatment orthodontic subjects aged 12 – 18 years were

photographically recorded in a standing mirror-guided natural head position (NHP).

Cephalograms taken at the same time were traced, orientated to a plumb line (true vertical)

transferred from the photograph, and measured. Thirty-nine of these subjects were

photographically recorded 2 months later to test the reproducibility of NHP. The planes

illustrating the lowest variability to HOR were FH and the KW line. These, however,

showed approximately double the variation in NHP reproducibility. They concluded that

the KW line and palatal plane are potential substitutes for the commonly used reference

planes in the absence of a reliable NHP. Stating that however, NHP still represents a more

valid craniofacial reference system than the investigated reference planes.


3. Wood RP, Elliot RW (2003) 8conducted a study a). To determine the reproducibility,

measured with the condylar position indicator device (CPI), of two piece CR bite technique

described by Roth. b).to determine direction of centric slide. c).to determine differences in

overjet measured from centric relation and maximum intercuspation and d).to evaluate

location of initial tooth contacts in centric relation.
The condylar displacements of 39 subjects were measured in vertical and horizontal

direction from mounted models. A CR bite registration was taken five times and used to

remount the lower cast and record the data five times. They concluded that the Roth bite

registration is highly reproducible since there was no significant difference between the

five CPI readings, a statistically significant difference was found in the overjet

measurements between CR and MI and thirty six out of thirty nine subjects had initial tooth

contact in CR on the most posterior tooth.



4. Marcotte MR (1981) 9undertook a study , including 136 subjects randomly picked

from an orthodontic practice where lateral cephalograms were taken in natural head

position, by asking the subjects to look at the reflection of their own eyes, on a vertical

mirror kept 8 feet away. The head position on the film was oriented to a true vertical metal

plumb line. A horizontal line was constructed from sella, at an angle 7o from SN line. Head

posture was measured by the angle between this constructed horizontal line and true

vertical line. An upward head position was assigned a negative sign and a downward head

position was assigned a positive sign. This was evaluated with parameters in relation to

facial form (22 measurements in each cephalogram). The antero-posterior position of

mandible relative to nasion showed the highest correlation with head position. When

mandible is located anteriorly, the head posture is angle is more downward (more positive),

and those with relatively retrusive mandibles were found to have a higher head posture.
     6.3: Objectives of the study :

             To verify intra-individual reproducibility of natural head position in adult
              patients in centric relation

             To prove inter-individual variability of Frankfurt horizontal plane and sella-
              nasion line to true horizontal line.

             To establish linear norms from A-point, B-point, Pog as well as soft tissue A-
              point, soft tissue B-point, and soft tissue Pog to NTVL in adult Indian subjects.

             The possibility of adopting NHP and CR as a useful position for diagnosing
              orthodontic cases and orthognathic, instead of FH or SN line will be evaluated.




7.   MATERIALS AND METHODS

     7.1 Source of Data:

     Data will be collected from patients visiting A.J. Institute of Dental Sciences, Mangalore

     to receive treatment and volunteers who wish to take part in the study, in the age group

     18 to 40 years, with informed consent.



     Inclusion criteria :

     Normal healthy adult individuals, both males and females, in the age group 18 to 40

     years, of Angles class I molar relation and class I skeletal pattern with ANB angle 1o to

     3o

     Exclusion criteria :

     History of orthodontic treatment or orthognathic surgery.

     Presence of intra oral prosthesis spanning more than 3 units.

     Absence of more than two molars, excluding third molars.
7.2 Method of Collection of Data :

The study will be done on 116 subjects, patients visiting A.J. Institute of Dental
Sciences, Mangalore, and volunteers who wish to take part in the study, in the age group
18 to 40 years, both groups with informed consent.


Methodology:
A centric relation record by Roth technique8, 13 (power centric method) using a two piece
wax bite will be recorded for each individual before taking the lateral cephalogram.
NHP registration shall be done using the Solow and Tallgren10 method, were the subject
will be asked to stand with their feet a shoulder width apart and arms relaxed. The
subjects shall be wearing an eyeglass with an attached fluid leveler, staring at their own
eyes, on a mirror placed about 120 cm away from the subject. This will be done after
exercising their necks up and down, thereby attaining a relaxed position. The subjects
shall be asked to bite on their previously made CR wax records, in a lips relaxed manner.
A metal chain (plumb line) will be dropped in front of the subject, which will help to
attain the Nasion TVL and radiographs will be recorded using KODAK 8000C Machine
(78Kvp, 12 MA, 1 sec exposure) . The ANB angle will be measured in the first digitised
cephalogram (T1) , using an Imaging Software, subjects those with ANB in the range 1o
to 3o will be included in the study.
After a week interval, a second lateral cephalogram (T2) will be recorded of all selected
subjects , following the same criterion.
A total of seventeen landmarks will be marked on the digitized cephalograms, in both
the first (T1) and second (T2) lateral cephalograms. Six angular parameters namely :
   1. Nasion TVL to palatal plane
   2. NTVL to E- line
   3. NTVL to cervical vertibrae tangent
   4. NTVL to sella-nasion
   5. True horizontal line(THL) to Odontoid Process Tangent(OPT)
   6. SN to OPT
will be assessed to prove the intraclass reliability and reproducibility of NHP.
Cephalometric parameters
The selected reference planes to be investigated are
   1. Nasion true vertical line (NTVL), passing through nasion and perpendicular to
       the floor.
   2. E- line, tip of nose to soft tissue pogonion
   3. Cervical vertebrae tangent plane, posterior tangent to odontoid process through
       Cv4ip.
   4. Odontoid process tangent plane, posterior tangent to odontoid process through
       Cv2ip.
   5. Palatal plane, ANS to PNS.
   6. True horizontal line passing through nasion, perpendicular to NTVL.
   7. Sella -Nasion plane.
   8. Frankfort horizontal plane, porion to orbitale.
The criteria for selecting the six parameters are as follows:
NTVL/E-line for reproducibility of facial aesthetics,
NTVL/palatal plane as an intramaxillary reference line,
NTVL/CVT and OPT for the cervical vertebrae,
NTVL/SN for the anterior cranial base (SN),
SN/OPT for the anterior cranial base to cervical vertebrae.


Also the THL to FH plane and SN plane angles will be measured, and compared to
norms9 (THL–FH =O degrees, THL-SN=7 degrees) where, the mean value of THL from
T1 and T2 will be considered.
Linear measurements of A-point, B-point, Pog to nasion true vertical line (NTVL) will
be evaluated. Linear measurements of soft tissue A-point, soft tissue B-point, soft tissue
Pog to nasion true vertical line (NTVL) shall also be evaluated.


Method errors in digitizing landmarks and measurements, in randomly selected 15
subjects, and method errors in positioning in the whole sample size of 116 subjects shall
be evaluated using Dahlberg’s formula.
Based on the result of the study, the possibility of adopting NHP and CR as a useful
position for diagnosing orthognathic and orthodontic cases will be evaluated.
Statistical analysis :

The analysis will be done using intraclass correlation coefficient , Dahlberg’s formula

and Pearson correlation coefficient



7.3: Does the study require any investigation or interventions to be conducted on

patients or other humans or animals? If so, please describe briefly

YES

Two lateral cephalograms per patient to be taken.


7.4: Has ethical clearance been obtained from your institution in case of 7.3?

Yes, clearance obtained.
                            Investigation Design

      Centric relation will be recorded using Roth power centric method, of individuals included
      in the selection criteria



      First of the two lateral cephalograms taken (T1). The subjects will be wearing eyeglasses
      with attached fluid leveler, in natural head position, biting on CR wax records and lips
      relaxed. A metal chain is dropped in front of subject to draw the NTVL.




                                    Digitizing of lateral cephalograms.




                                        Measurement of ANB angle.
         Only those subjects with ANB within 1o-3o, shall continue in the study. In these subjects, the
           2nd radiograph (T2)will be taken after a week interval, following same criterion as T1.



  Method errors in digitizing landmarks                               Reliability and reproducibility of
  and measurements calculated.                                        NHP assessed using 6 angular
  Method errors in positioning evaluated .                            parameters, according to intraclasss
  Both, using Dahlbergs formula.                                      correlation coefficient.




Linear measurements of A-point, B-                                  Differences in FH plane to THL and SN
point, Pog, soft tissue A-point, soft                              plane to THL are compared to norms.
tissue B-point, soft tissue Pog to
nasion true vertical line (NTVL) shall
be evaluated.




                                             Analysis of results
8
    LIST OF REFERENCES :


    1. Ahn JH, Bae KH, Park YJ, Hong RK, Nam JH, Kim MJ. Assessment of antero-

    posterior skeletal relationships in adult Korean patients in natural head position and

    centric relation. Korean J Orthod 2010;40(6):421-31.

    2. Broca M. Sur les projections de la tète, et sur un nouveau procède de

    cephalometrié. Bull de la Société D’Anthropologie de Paris 1862;3:514-44.

    3. Moorrees CFA, Kean MR. Natural head position: a basic consideration in the

    interpretation of cephalometric radiographs. Am J Phys Anthrop 1958;16:213-34

    4. Leitão P, Nanda RS. Relationship of natural head position to craniofacial

    morphology. Am J Orthod Dentofacial Orthop 2000;117:406-17.

    5. Peng L, Cooke MS. Fifteen-year reproducibility of natural head posture: A

    longitudinal study. Am J Orthod Dentofacial Orthop 1999;116:82-5.

    6. The glossary of prosthodontic terms. The Academy of

    Prosthodontics. J Prosthet Dent 1994;71:41-112.

    7. Madsen DP, Sampson WJ, Townsend DC. Craniofacial reference plane variation and

    natural head position. EJO 2008;30:532-40.

    8. Wood DP, Elliot RW. Reproducibility of centric bite relation bite registration

    technique. Angle Orthod1994;63(3):211-21.

    9. Marcotte MR. Head posture and dentofacial proportions. Angle Orthod

    1981;51:208-13.
10. Solow B, Tallgren A. Head posture and craniofacial morphology. Am J Phys

Anthropol 1976;44(3):417-35.

11. Showfety KJ, Vig PS, Matteson S. A simple method for taking natural head position

cephalograms. Am J Orthod 1983;83: 495-500.

12. Huggare JA. A natural head position technique for radiographic cephalometry.

Dentomaxillofac Radiol 1993;22:74-6.

13. Roth RH. Functional occlusion for the orthodontist. Part .1. J Clin Orthod 1981;

15(1):32-51
9.    Signature of the Candidate

10.   Remarks of the Guide


11.   11.1 Name and Designation of     DR. KESHAVARAJ. MDS
      Guide                            READER,
      (In Block Letters)               DEPARTMENT OF ORTHODONTICS AND
                                       DENTOFACIAL ORTHOPEDICS,
                                       A.J. INSTITUTE OF DENTAL SCIENCES
                                       MANGALORE-575 004.


      11.2 Signature


      11.3 Co-Guide (if any)           DR ROHAN RAI. MDS
                                       PROFESSOR AND HEAD,
                                       DEPARTMENT OF ORTHODONTICS AND
                                       DENTOFACIAL ORTHOPEDICS,
                                       A.J. INSTITUTE OF DENTAL SCIENCES
                                       MANGALORE-575 004

      11.4 Signature



      11.5 Head of the Department      DR ROHAN RAI. MDS
                                       PROFESSOR AND HEAD,
                                       DEPARTMENT OF ORTHODONTICS AND
                                       DENTOFACIAL ORTHOPEDICS,
                                       A.J. INSTITUTE OF DENTAL SCIENCES
                                       MANGALORE-575 004.


      11.6 Signature




      12.1 Remarks of the Chairman &
12.
      Principal
      Dr. DEEPAK NAYAK U.S.
      12.2 Signature
                               CONSENT FORM



1) INFORMATION SHEET

TITLE OF RESEARCH:

“ASSESSMENT OF ANTERO-POSTERIOR SKELETAL & SOFT TISSUE

RELATIONSHIPS OF ADULT INDIAN SUBJECTS IN NATURAL HEAD

POSITION & CENTRIC RELATION”



INVESTIGATORS:



Dr. Keshavaraj

Reader and PG Guide,

Department of Orthodontics and Dentofacial Orthopedics,

A J Institute of Dental Sciences, Mangalore - 04



Dr. Vishnu Ben Latif,

1st year Post graduate,

Department of Orthodontics and Dentofacial Orthopedics’,

A J Institute of Dental Sciences, Mangalore – 04
INTRODUCTION:

I, Dr. Vishnu Ben Latif, Post Graduate Student in the Department of Orthodontics and

Dentofacial Orthopedics, A. J. Institute of Dental Sciences, Kuntikana, Mangalore, is

working on my dissertation titled “ASSESSMENT OF ANTERO-POSTERIOR

SKELETAL & SOFT TISSUE RELATIONSHIPS OF ADULT INDIAN SUBJECTS

IN NATURAL HEAD POSITION & CENTRIC RELATION”. My study subjects

shall be 116 adult male and female patients visiting A. J. Institute of Dental Sciences,

including subjects volunteering to participate, age ranging from 18 to 40 years.



VOLUNTARY PARTICIPATION

Your participation in this research is entirely voluntary. It is your choice whether to

participate or not. Whether you choose to participate or not, it will not affect the

patient’s treatment in any way.



EXPLANATION OF THE PROCEDURE:

A centric relation record by Roth technique using a two piece wax bite will be

recorded for each individual before taking the lateral cephalogram.

NHP registration shall be done using the Solow and Tallgren method, were the subject

will be asked to stand with their feet a shoulder width apart and arms relaxed. The

subjects shall be wearing an eyeglass with an attached fluid leveler, staring at their

own eyes, on a mirror placed about 120 cm away from the subject. This will be done

after exercising their necks up and down, thereby attaining a relaxed position. The

subjects shall be asked to bite on their previously made CR wax records, in a lips

relaxed manner.
The radiographs will be recorded using KODAK 8000C Machine (78Kvp, 12 MA, 1

sec exposure) and a metal chain (plumb line) will be dropped in front of the subject,

which will help to attain the Nasion TVL. The ANB angle will be measured in the

first digitised cephalogram (T1) of each subject, if found to be in the range 1o to 3o

shall continue in the study.

After a week interval, a second lateral cephalogram (T2) will be recorded of all

selected subjects , following the same criterion.



POSSIBLE BENEFITS

Linear norms from A-point, B-point, Pog as well as soft tissue A-point, soft tissue B-

point, and soft tissue Pog to NTVL in adult Indian subjects can be established.


Based on the result, the possibility of adopting NHP and CR as a useful position for

diagnosing orthognathic and orthodontic cases, instead of FRH or SN line will be

evaluated.



POSSIBLE RISKS:

Digital radiograph radiation exposure will be far below the permissible annual dosage

of 5 mSv.

The radiograph would be taken by experienced technicians in a controlled

environment with all necessary precautions.
CONFIDENTIALITY:

The information that we collect from this research project will be kept confidential.

Information about the patient that will be collected during the research will be put

away and no one but the researchers will be able to see it. Any information about the

patient will have a number code and the name & identity of the patient will be kept

confidential.



WITHDRAWAL:

You are entitled to withdraw from the study at any point of time.



SIGNIFICANT NEW FINDINGS:

New findings as and when made regarding your condition would be informed to you.



COST INCURRED BY YOU FOR PARTICIPATION:

The procedure will be free of cost.



PAYMENT IN CASE OF UNTOWARD INCIDENTS DURING THE STUDY:

No monetary compensation would be given in case of untoward incidents such as

occurrence of complications during the study.
CONTACTS:

If you have any questions about your investigation and study, you may please contact.

Dr. Keshavaraj

Reader and PG Guide,

Department of Orthodontics and Dentofacial Orthopedics,

A J Institute of Dental Sciences, Mangalore -04

OR

Dr. Vishnu Ben Latif

1st year Post graduate,

Department of Orthodontics and Dentofacial Orthopedics,

A J Institute of Dental Sciences, Mangalore – 04

Mobile No. – 08095515116



LEGAL RIGHTS:

By signing on the consent form you will be waiving off all legal liabilities against the

institution and staff.
                             CERTIFICATE OF CONSENT



I                                             , D/O / S/O,

aged              years, is ready to take part in the proposed experiment . The course

and nature of the procedure have been explained to me with possible benefits and

risks. All of the above has been explained to me in a language I best comprehend and

I hereby give my full consent to participate in the study.



1. Name of the patient-

    Signature / thumb print of patient-




2. Name of the investigator /

    designee obtaining informed consent –

    Signature of the investigator /

    designee obtaining informed consent –




3. Name of witness-

    Signature of witness-

				
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