SYNOPSIS
Dr. MANU JOHNS
POST GRADUATE STUDENT
DEPARTMENT OF PROSTHODONTICS INCLUDING
CROWN & BRIDGE AND IMPLANTOLOGY
K.V.G.DENTAL COLLEGE & HOSPITAL,
KURUNJIBAG-SULLIA (DK) KARNATAKA, INDIA
Rajiv Gandhi University of Health Sciences, Karnataka
Bangalore
ANNEXURE
PROFORMA FOR REGISTRATION OF SUBJECTS FOR DISSERTATION
1. / Name of the Candidate and Address(In block letters) / Dr. MANU JOHNS
POST GRADUATE STUDENT,
DEPARTMENT OF PROSTHODONTICS
K.V.G.DENTAL COLLEGE & HOSPITAL,
KURUNJIBAG-SULLIA(DK)
KARNATAKA,INDIA-574 327
2. / Name of the Institution / K.V.G.DENTAL COLLEGE & HOSPITAL,
KURUNJIBAG-SULLIA(DK)
KARNATAKA,INDIA-574 327
3. / Course of study and subject / MASTER OF DENTAL SURGERY
PROSTHODONTICS ,CROWN & BRIDGE
4. / Date of admission of course / 3rd of APRIL 2010
5. / Title Of The Topic:
A STUDY TO EVALUATE THE RELIABILITY OF DIFFERENTFACIAL ANATOMIC LANDMARKS CLOSEST TO THE MIDLINE OF THE FACE USING ESTHETIC FRAME CONCEPTIN TWO AGE GROUPS.
BRIEF RESUME OF INTENDED WORK :
6.1NEED FOR STUDY:
One of the primary goals of any treatment is the attainment of the best facial esthetic appearance for a given patient.
Facialmidline is the fundamental reference for all esthetic deviations. Currently there are no verifiable guidelines that direct the choice of specific anatomical landmarks to determine the midline of the face1.
Historically a number of facial anatomical landmarks located on the middle third of face, such as bisector of pupils, nasion, tip of nose, tip of philtrum and chin have been used to determine the facial and dental midlines1. Some advocate the use of intraoral landmarks such as the incisive papilla, for determination of maxillary dental midline.Based on convention and dogma, most clinicians choose one specific anatomic landmark and an imaginary line passing through it. Thus the clinician is left with no predictable guidelines, and most determine the midline based on unverified landmarks.1
Most of the literature available with regard to this dissertation is restricted to monographs written by various authors. Clinical studies have been limited to amount of tolerance of deviated dental midlines from the facial midline – a span of approximately 2-3 mm3. Currently literature does not have a definition for facial midline that can lend itself to objectivity and repeatability for research purposes the midline of the face.
As it is practically almost impossible to define the midline of the face in both static and dynamic movements, a computer generated rectangular enclosure was used to define the midline of the face objectively in this study.
Hence the aim of the study is to determine the hierarchy of facial anatomic landmarks closest to the midline of the face as well as midline of the mouth using the esthetic frame concept.
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6.2REVIEW OF LITERATURE :
A studywas conducted to determine the hierarchy of facial anatomic landmarks closest to the midline of the face as well as midline of the mouth.Three commonly used anatomic landmarks, nasion, tip of the nose, and tip of the philtrum,were marked clinically1. Frontal full-face digital images of the subjects in smilewere then made under standardized conditions. Images of 87 subjects were used for midline analysis using the concept of esthetic frame.Deviations from the midlines of the face and mouth were measured for the 3 clinical landmarks and the existing dental midline. 1-sample t tests were conducted at alpha values of .001 and .05, respectively.The results indicated that each of the 4 landmarks deviated uniquely and significantly (P<.001) from the midlines of the face as well as the mouth. And within the limitations of the study, the hierarchy of anatomic landmarks closest to the midline of the face in smile was as follows: the midline of the oral commissures, natural dental midline, tip of philtrum, nasion, and tip of the nose. The hierarchy of anatomic landmarks closest to the midline of the oral commissures was: natural dental midline, tip of philtrum, tip of the nose, and nasion. These relationships were the same for both genders1.
In another study, full facial-view, standardized photographs of 45 subjects, meeting very limited inclusion/exclusion criteria, were examined by 10 observers: 5 dentists and 5 nondental personnel2. The examiners asked whether the facial and anterior tooth midlines deviated2. The photographs then were scanned onto a computer screen, and the facial midline was determined by bisecting the distance between the medial angles of the eyes. The distance between a line perpendicular to this point and the contact point of the central incisors was measured by one examiner. The photographs were grouped according to the midline deviation: group 1, 1 mm; group 2, 1 to 2 mm; and group 3, 2 mm. The observer’s detection rates for the remaining midline deviation were compared and subjected to 1-way analysis of variance to identify significant differences at the 95% level of confidence. A post hoc Student t test was performed to identify significant differences among the groups. Dentists and non-dental personnel demonstrated a similar ability to notice deviations of anterior tooth and facial midlines. It was concluded that within the limitations of this study, the greater the deviation of anterior tooth and facial midlines, the higher the detection rate. Nearly half of the 10 observers involved in this investigation were unable to detect midline deviations of 2 mm2.
It was concludedin another study3 that an ideal situation, facial midline landmarks such as the nose, philtrum, and chin would be aligned with the facial soft-tissue midline, and the goal after orthodontic treatment would be for the dental midline to be coincident. In patients in whom the locations of the nose, philtrum, and chin are not aligned, it may be more difficult to establish goals for movement of the maxillary midline. Results from this study suggest that the ideal location of the maxillary dental midline should be determined independently of the location of other specific facial landmarks, because all photographs, in which the maxillary midline was deviated, alone or in combination with another facial landmark, were rated poorly 3.
A study4 was carried out to determine the public’spreferences for five esthetic variations ,with the goal of linking preferences to demographic data such as age ,gender ,country of residence and race .Using a computer software ,5 pairs of images with anterior tooth variations were put on a web page with forms to collect demographic data and ranking of the image pairs .Opinions were solicited by sending out a large number of e-mails with a short study description and an invitation to access the web page. The responses were tabulated and analyzed. Strongest preferences concerned diastema and midline shift and the weakest concerned whiteness and proportion. This study stresses the importance of the dental midline for esthetics 4.
The perception of discrepancies between the dental and facial midlines by orthodontists and young laypeople was investigated 5. A smiling photograph of a young female was modified by moving the dental midline relative to the facial midline. Twenty orthodontists and 20 young adults scored the attractiveness of the smile on the original image and each of the modified images using a 10 point scale. The results showed that the images were scored as less attractive both by the orthodontists and the lay people as the size of the dental and facial midline discrepancy increased 5. The scores were unrelated to the direction of the midline discrepancy or to gender of the judge. Further analysis revealed that the orthodontists were more sensitive than laypeople to small discrepancies between the dental and facial midline. It was estimated that the probability of a layperson recording a less favorable attractiveness is when there was a 2mm discrepancy between the dental and facial midlines was present 5.
The position of several anatomical landmarks relative to the facial midline was observed in patients receiving maxillary complete dentures 6. Tubercle of the upper teeth was determined to be the midline of each patient and was marked on a maxillary occlusal rim. The position of the midline is transferred from the occlusal rim to the land area of the master cast. Lines extending from midpalatine suture, the labial frenum,and the midpoint of the incisive papilla were also marked on the land area. Measurements between each of these landmarks and the facial midline were studied by a comparison of means, correlation and a 3 way analysis of variance. It was concluded that overall means of distances from the facial midline to the incisive papilla, the midpalatine suture and to the frenum was less than 1. Approximately 70% of the distances were 1mm or less and the range varied from 0 – 5.5 mm 6.
A study was designed to findout whether nature normally position the central incisors on either side of a line which extends vertically through the exact center of the anterior portion of the mouth and does the midline of the mandibular teeth normally coincide with the maxillary midline7. Five hundred subjects with natural dentitions were examined. A specially prepared form was filled out by the examiner. The results were then evaluated.The result indicated that it is very likely that the midline of the maxillary teeth and the philtrum coincide in almost 75% of the people7. The statistics indicate that it is quite unlikely that the maxillary and mandibular midlines match in more than 32% of the total population. It was concluded in the study that in an arrangement of artificial teeth the midline may be placed in the precise midsagittal plane or slightly at variance from it with no loss in natural appearance. The most reliable guide in making this decision would be the patient’s natural teeth prior to extraction. When no preextraction records are available, the most prudent course would seem to be to place the maxillary midline in the exact middle of the mouth using the philtrum as a guide and to disregard whether or not the maxillary and mandibular midlines coincide7.
OBJECTIVES OF THE STUDY:
The primary objective of the study is to find out the relative reliability of different clinical anatomical landmarks to determine the midline of face and the hierarchy of facial anatomical landmarks closest to the midline of face. The facial anatomical landmarks analyzed are those traditionally used in clinical practice such as – nasion, tip of nose, tip of philtrum and dental midline.
7.1 MATERIAL AND METHODS
Full-face digital images of subjects in smile will be made, with the subject in a seated position.
Each subject will have 3 small marks placed by a single observer using a fine-tipped erasable marker, with a tip approximately 0.5 mm in diameter on the nasion, tip of the nose, and tip of the philtrum, to simulate a clinical situation.
It is decided to conduct the study on 100 subjects, comprising both male and female, selected from the students and patients of the outpatient department of KVG Dental college, Sullia.
Informed consent will be taken from each subject.
The investigation is carried out in the following manner:
Selection of the subjects.
The following criteria’s are observed for the selection of subjects for the study:
- Two Age groupsbetween 17 to 35years, and 36 to 50years.
- No history of congenital conditions or trauma affecting facial form and appearance.
- No history of orthodontic treatment.
- No missing maxillary anterior teeth.
- No prosthetic maxillary anterior teeth.
- No interdental spacing in maxillary teeth.
- Ability to understand written informed consent documents.
The nasion, tip of the nose, and tip of the philtrum is marked on subjects face using fine-tipped erasable marker. Standardization is given to application of all anatomic marks in terms of the standard anatomic and anthropologic definitions.
Obtaining the Photographic Data
A digital camera (NIKON D40X digital SLR camera, 10.2 Megapixel; Nikon Corporation, Japan) with an 18-55mm lens and a point flash is used. The camera will have an aperture setting of F4.5 and will be mounted on a tripod, with a standardized focus and at a standardized distance of 5 feet (1.5 m) from the subject. The lighting conditions will remain the same for all the photographs. Full-face digital images of subjects in smile will be made, with the subject in a seated position. The head position will be guided by the observer to assist the subjects in assuming their natural head position.9, 10, 11,12
Analysis of the digital photograph for different clinical midlines and comparing them with the computer aided facial midline
Exclusion criteria of photographs are as follows.
- Images with rotations of head around the vertical axis.
- Obvious ophthalmic asymmetry.
- Inaccurate clinical markings.
- Images without good resolution.
The “Esthetic Frame“is then constructed over this photograph digitally. It is defined as an area on the human face, within which items of esthetic interest such as midlines, cants and smile parameters are sensitively perceptible and objectively verifiable. Its superior border is defined by a line originating at the exocanthion of 1 eye and meeting the exocanthion of the other eye.The 2 lateralborders of the frame are then drawn as perpendicular lines from the exocanthion of each eye and are parallel to each other. The inferior border of the frame is parallel to the superior border and is drawn at the most inferior border of the lower lip. This completes the 4 sides of the frame. It is assumed that it is more imperative to obtain the midline of that portion of the face included in this Esthetic Frame, rather than the “true” midline using the “entire” face.
The facial midline is established by bisecting the distance between the 2 lateral borders on the frame.Three vertical lines were then drawn along each of the anatomic points, which has been marked clinically. The fourth line is drawn along the subject’s existing dental midline.
Relative facial midline value (RFV) is defined as the relative closeness of an anatomic landmark to the facial midline. The measured distance from the lateral border of the frame to the defined facial midline is considered a constant called “F.” The measured distance from the lateral border of the frame to the nasion is considered a variable termed “n.” The RFV is then obtained by dividing n by F. Similarly, RFVs are obtained for the other 3 anatomic landmarks: tip of the nose (t), tip of philtrum (p), and dental midline (d), by dividing them by the constant F. Numerical values for n/F, t/F, p/F, and d/F are thus obtained.
The primary reason to use RFV is to develop a proportional relationship between an anatomic landmark and the midline in question. This ensures a standard common denominator for all anatomic landmarks within the esthetic frame and negated the need for size matching the images with the subject’s face.
In perfect symmetry, all 5 of the RFVs would be equal to each other and to the numeral 1.A total of 9 values are recorded per subject, along with gender and age of the patient.The entire process of data analysis will be repeated twice to ensure reliability and validity. A reliability analysis test will be performed between the first and second set of data using intraclass correlation coefficients (ICCs). To determine whether the selected landmarks significantly differed from the midline of the face, a series of sample t tests will be conducted with an alpha value of 0.05.
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.
YES,This study requires investigations to be conducted in humans.
7.4 Has ethical clearance been obtained from your institution in case of 7.3?
YES
7.5LIST OF REFERENCES:
- Avinash S. Bidra,Thomas D. Taylor,Flavio Uribe.The relationship of facial anatomical landmarks with midlines of face and mouth.J prosthet dent 2009;102:94-103.
- Harold S. Observable deviation of facial and anterior tooth midlines.
- Beyer JW, Lindauer SJ.Evaluation of dental midline position.
- Stephan F Rosenstiel.Public preferences for anterior tooth variations. A web based study. Journal of esthetic & restorative dentistry 2002 (14) no .2.
- Johnston Cd, Burden Dj, Stevenson M. Influence of dental to facial midline discrepancies in dental attractiveness ratings .European journal of orthodontics.1 ; 1999 ;517 -572.
- George H.Latta.Midline and its relation to anatomic landmarks in the edentulous patient.
- Ernest L. Miller. A study of the relationship of the dental midline to thefacial midline.
- Lombardi RE. The principles of visual perception and their clinical application to denture esthetics. J prosthet dent 1973;29:358-82.
- Peng L, Cooke MS.Fifteen year reproducibility of natural head posture: a longitudinal Study.American journal of orth. & dentofacial orthopedics- 1999 ; 116; 82-85.
- Cooke MS. Five-year reproducibility of natural head posture: a longitudinal study.
- Cooke MS, Wei Sh. The reproducibility of natural head posture: a methodological study.
- Lundström F, Lundström A.. Natural head position as a basis for cephalometric analysis.
- Rhodes G. The evolutionary psychology of facial beauty.
- Tjan Ah, Miller Gd.Some esthetic factors in a smile.
K V G DENTAL COLLEGE AND HOSPITAL
SULLIA
PROFORMA FOR REGISTRATION OF SUBJECTS FOR
MDS DISSERTATION
- Name of the Candidate