Download Rajiv Gandhi University of Health Sciences, Karnataka

DISSERTATION – SYNOPSIS
DR. SUMITHA SHETTY B.
POSTGRADUATE STUDENT,
A. J. INSTITUTE OF DENTAL SCIENCES, KUNTIKANA,
MANGALORE.
BATCH 2008-2009.
Rajiv Gandhi University of Health Sciences, Karnataka,
Bangalore
ANNEXURE II
PROFORMA FOR REGISTRATION OF SUBJECTS FOR DISSERTATION
1.
Name of the Candidate
SUMITHA SHETTY B.
and address
(in block letters)
2.
A. J. INSTITUTE OF DENTAL
SCIENCES,
N.H.17, KUNTIKANA,
MANGALORE-575004.
Name of the institution
A. J. INSTITUTE OF DENTAL
SCIENCES .
3.
Course of study and subject
MASTER OF DENTAL SURGERY
ORTHODONTICS
4.
Date of admission to course
5.
Title of the topic:
28.05.2008
EVALUATION OF CHANGES
IN CRANIAL BASE
MORPHOLOGY IN DIFFERENT
MALOCCLUSIONS.
6.
Brief resume of the intended work:
6.1 Need for the study
Description and diagnosis of a malocclusion is the primary objective of the
Orthodontist. In the assessment of Orthodontic problems involving
anteroposterior malrelationship of the jaws, the problem is usually the result
of size, form and position of the jaw.
Despite the effects of head posture1, breathing mode2 or even spine position3
that have been shown to influence craniofacial morphology, cranial base
flexion has been put forward to be a possible indicator of a skeletal
malocclusion.
Depending on the fact that the maxilla is connected with the anterior part of
the cranial base and the rotation of the mandible is influenced by the maxilla,
a relationship can be found between the cranial base variations and saggital
malpositions of the jaw.
Due to controversy in the current literature, the present study is done to
investigate, in a cross-sectional sample, whether the cranial base flexure or
shape of the cranial base could show morphological differences in skeletal
class I, class II and class III malocclusions.
6.2 Review of literature:
A cross-sectional retrospective study was carried out to investigate any
possible differences in the shape and position of the cranial base in class I, class
II and class III skeletal patterns. The results showed that there were no
differences observed in anterior and posterior cranial base lengths and cranial
base angles between the three malocclusions. However, cranial base inclinations
were increased in class III malocclusions.4
A study was done to examine the contribution of cranial base angle in the
four groups of malocclusion as classified by the British Standards Institute
incisor classification. A total of 200 cephalometric radiographs of caucasian
patients (50 for each malocclusion group, with an age range between 8-12
years) were selected for the study.
Following linear and angular variables were calculated :
Cranial base flexure, jaw position, skeletal pattern, dento-alveolar pattern,
cranial base lengths and jaw lengths.
Results showed that the cranial base flexure does not play a pivotal role in
determining malocclusion. Jaw size, however, was significantly different
between the main classes of malocclusion. The maxilla was found to be longer
in class II subjects and the mandible longer in class III subjects.5
A longitudinal study was conducted to investigate skeletal features in
patients with small and large cranial base angles at the age of 5 and 12 years.
Subjects with large cranial base angle in the primary dentition demonstrated a
skeletal class II tendency both at the initial observation and at the longitudinal
follow up. The cephalometric variables indicated a constancy of the skeletal
pattern during longitudinal follow-up. The relationship between cranial base
flexure and skeletal pattern of the jaws seems to be established before the age of
5 years.6
A study was conducted to compare seven cephalometric measurements of
the cranial base in subjects with class I and class II skeletal patterns at ages
1month, 2 years and 14 years.
Results indicate that individuals with class II skeletal pattern do not have
significantly more obtuse cranial base angle. In fact, this angle became more
acute with age in both of the groups that were studied, with the greatest change
occurring between 1 month and 2 years. No significant changes were found in
this angle between 2 years and 14 years. The results indicate that these
differences do not lie within the cranial base and thus lead us to look more
precisely at the structural and growth differences of the maxilla and mandible.7
A study was done to examine the craniofacial patterns in class III, class II
division 1 and class II division 2, malocclusions respectively.
The results of the study were that the linear and angular dimensions of the
cranial base tend to be smaller in class III malocclusions and to be larger in
class II malocclusions when compared with a common control group of children
with either normal occlusion or class I malocclusion. The variation of the
cranial base stood out as the most consistent factor associated with
anteroposterior malrelationships of the dental arches. It was concluded that the
dimensions of the cranial base are a major factor in determining anteroposterior
relationship of the jaw and the dental arches which must be taken into account
in diagnosis and treatment.8
An investigation was done to analyze the growth mechanism of the cranial
base on 243 Swedish boys ( first examined at the age of 12 and later at the age
of 20). The material on which the investigation was based consisted of two
series of standardized lateral head x-ray pictures.
Results of the investigation were: The general growth pattern showed the cranial
base was elongated virtually by frontal apposition in the glabella region, without
any appreciable longitudinal, sutural increment of the anterior cranial fossa. The
dorsal elongation of the cranial base, in the medial region due to the
endochondral growth of the clivus, is accompanied by a dorsal displacement
due to the sutural growth of the lateral regions of the cranial base and the brain
case, forming the median and the posterior cranial fossae and a simultaneous
lowering of these regions in relation to the anterior cranial fossa. There was on
an average, an insignificant straightening of the cranial base and there was a
virtually parallel lowering of the foramen magnum.9
6.3 6.3 Objectives of the study:
To evaluate the following in skeletal class I, class II and Class III malocclusions:
 the differences in cranial base flexure
 anterior and posterior cranial base lengths
 cranial base inclinations.
7.
Material and methods:
7.1 Source of data:

Lateral cephalometric radiographs (pretreatment) of 75 patients,
referred for treatment, to the Department of Orthodontics and
Dentofacial Orthopaedics, A. J. Institute of Dental Sciences,
Mangalore will be taken.



25 patients with skeletal class I,
25 patients with skeletal class II and
25 patients with skeletal class III will be selected for the study.

The mean age group of the patients for the study will be 15±4.
7.2 Methods of collection of data(including sampling procedure,
if any)
Selection of teeth:
Not applicable.
Methodology:
Lateral cephalometric radiographs of each subject will be taken with a digital
panoramic and cephalometric system.
All the subjects will be positioned in the cephalostat with the saggital plane at
right angle to the path of x-rays with the Frankfort plane parallel to the
horizontal, teeth in centric occlusion and lips relaxed.
Following are the criteria used in selecting the patients for the study:
 Group 1 (n=25): skeletal class I malocclusion with an ANB angle of 2±2º,
favorable over jet and overbite and minimal crowding of both arches.
 Group 2 (n=25): skeletal class II malocclusions with ANB angle of +5º or
more, increased overjet.
 Group 3 (n=25): skeletal class III malocclusions with an ANB angle of −1º
or less negative overjet.
 Patients with a history of any oral habit will be excluded from
the study.
 All of the patients will be past pubertal growth spurt stage as assessed
according to cervical vertebrae maturation index CV4 developmental stage
and showed normal vertical growth pattern as determined by GoGnSN angle
(GoGnSN=32±6) according to Steiner’s analysis.10
The radiographs will be traced and following landmarks will be used for
cephalometric analysis:
Point A (A), Point B (B), Sella (S), Nasion (N), Articulare (Ar), Basion (Ba),
Gonion (Go), Gnathion (Gn), Porion (Po), Orbitale (Or).
The following reference lines and angles will be used in this study:
S-N, S-Ba, SNA, SNB, ANB, GoGn-SN, N-S-Ar, N-S-Ba, SN-FH, SBa-FH.
7.3 Does the study require any investigations or interventions to
be conducted on patients or other humans or animals? If so,
please. Describe briefly.
Lateral cephalometric radiographs of patients will be required to do the
study.
7.4 Has ethical clearance been obtained from your institution in
case of 7.3?
Yes.
INVESTIGATION DESIGN
Lateral cephalometric
radiographs of 75 patients
(pretreatment) will be taken
Skeletal Class I (25)
Skeletal Class II (25)
Skeletal Class III (25)
The following landmarks will be used for cephalometric analysis:
Point A (A), Point B (B), Nasion (N), Articulare (A), Basion (Ba),
Gonion (Go), Gnathion (Gn), Porion (Po), Orbitale (Or).
Parameters that will be used are
Angular measurements
Saggital
growth
pattern:
SNA,
SNB,
ANB.
Vertical
growth
pattern:
GoGn-SN.
Linear
measurements
A-P cranial
base
inclinations :
SN-FH
SBa-FH.
Cranial
base
flexure:
N-S-Ar,
N-S-Ba.
Cranial base
dimensions:
S-N,
S-Ba.
Mean and standard deviations will be estimated for cephalometric
variables in each group using ANOVA and TUKEY tests.
Statistical analysis will be done using Statistical package for Social
sciences software package (SPSS for windows, Version 15.0,
Chicago, IL, USA).
8.
List of References
1. Solow B, Tallgren A. Head posture and craniofacial morphology. Am J Phys
Anthropol 1976;44:417-435.
2. Peltomäki T. The effect of mode of breathing on craniofacial growth-revisited.
Eur J Orthod 2007;29:426-429.
3. Solow B, Sandham A. Cranio-cervical posture: a factor in the development and
function of the dentofacial structures. Eur J Orthod 2002;24:447-456.
4. Palot OO, Kaya B. Changes in cranial base morphology in different
malocclusions. Orthod Craniofacial Res.2007;10:216-221.
5. Dhopatkar A, Bhatia S, Rock P. An investigation into the relation between
cranial base angle and malocclusion. Angle Orthod 2002;72:456-63.
6. Klocke A, Nanda RS, Kahl-Nieke B. Role of cranial base flexure in developing
saggital jaw discrepancies. Am J Orthod Dentofacial Orthop 2002;122:386-91.
7. Wilhelm BM, Beck FM, Lidral AC, Vig KWL. A comparison of cranial base
growth in class I and class II skeletal patterns. Am J Orthod Dentofacial Orthop
2001;119:401-5.
8. Hopkin GB, Houston WJB, James GA. The cranial base as an etiological factor
in malocclusion. Angle Orthod.1968;38:250-5.
9. Bjork A .Cranial base development. Am J Orthod 1955;41:198-255.
10. Steiner C. C. Cephalometrics for you and me. Am J Orthod.1950;36:877-898.
11. Dibbets JMH. Morphological associations between the Angle classes. Eur J
Orthod 1996;18:111-118.
12. Kasai K, Moro T, Kanazawa E, Iwasawa T. Relationship between cranial base
and maxillofacial morphology. Eur J Orthod 1995;17:403-10.
13. Kerr WJS, Hirst D. Craniofacial characteristics of subjects with normal and
postnormal occlusion. A longitudinal study. Am J Orthod Dentofacial Orthop
1987;92:207-12.
14. Jarvinen S. Saddle angle and maxillary prognathism: a radiological analysis of
the association between the NSAr and SNA angles. Br J Orthod.1984;11:20913.
15. Anderson DL, Popovitch F. Lower cranial height vs craniofacial dimensions in
Angles class II malocclusion. Angle Orthod 1983;53:253-60.
16. Kerr WJS. A method of superimposing lateral cephalometric films for the
purpose of comparison: a preliminary report. Br J Orthod 1978;5:51-3.
17. Lewis AB, Roche AF. The saddle angle: constancy or change? Angle Orthod
1977;47:46-54.
18. Ricketts RM. Cephalometric analysis and synthesis. Angle Orthod
1961;31:141-56.
19. Renfroe EW. A study of the facial patterns associated with class I, class II
division 1 and class II division 2 malocclusion. Angle Orthod 1948;18:12-5.
20. Solow B, Kreilborg S. Soft tissue stretching: a possible control factor in
craniofacial morphogenesis. Scand J Dent Res 1977;85:505-7.
9.
Signature of candidate
10.
Remarks of the guide:
Name & Designation of
11.
(in block letters):
DR. NILLAN SHETTY K.
PROFESSOR
DEPARTMENT OF ORTHODONTICS
AND DENTOFACIAL ORTHOPAEDICS.
11.1 Guide:
11.2 Signature:
11.3 Co-Guide (if any)
DR. ROHAN RAI
PROFESSOR AND HEAD OF THE
DEPARTMENT
DEPARTMENT OF ORTHODONTICS
AND DENTOFACIAL ORTHOPAEDICS.
11.4 Signature:
11.5 Head of Department
11.6 Signature
12.
12.1 Remarks of the Chairman &
Principal:
12.2 Signature
DR. ROHAN RAI
DEPARTMENT OF ORTHODONTICS
AND DENTOFACIAL ORTHOPAEDICS.