In today’s health and esthetic conscious world, smile is considered an important component an individual’s appearance. One of the primary concerns in denture esthetics is the selection of Maxillary anterior artificial teeth especially the central incisors .The size, form and colour of teeth should be in harmony with surrounding oral and facial structures. The selection of anterior teeth becomes strenuous in edentulous patients when pre-extraction records are not available, making the process arbitrary in nature.
The mesiodistal width of the teeth is more critical than the length. Many anthropometric measurements of the face have been suggested to determine the mesiodistal width of maxillary central incisor in particular for edentulous patients .However no predictor has been found to be accurate enough to predict the dimension of the maxillary central incisor .Therefore it appears that more than one variable may be needed to predict the width of maxillary anterior teeth and central incisor. These variations could be due to the ethnic characteristics specific to the population studied
The need of this study is to determine the relationship of inner canthal, interpupillary, inter tragal distance, bizygomatic width to the width of the maxillary central incisor with reference to different facial forms and gender in South Indian population.
“Studies have shown that the mean Maxillary central incisor width and inner canthal distance were significantly higher for males than females. Inner canthal distance when multiplied by a decreasing factor of 0.618 and divided by 2 was a reliable predictor for maxillary central incisor”1
“The mesiodistal measurement were recorded at the widest dimension (contact area) .Three measurements were taken per tooth and mean calculated”2
“All the measurements were performed using a caliper with a precision of 0.01 mm. One operator performed all the measurement at least thrice”3
“The inner canthal and inter pupillary distance showed highest probability (p=0.000) being of correlated to the mesiodistal width of the maxillary anterior teeth” 4
“The shape of the face can be described by the facial index (defined as facial height / facial width X100)”5
“The ratio of 1: 16 between bizygomatic width and the width of maxillary central incisor was found to exist only in females”6
6.3 Objectives of the study
1. To determine the existence of a relationship between inter tragal distance and mesiodistal width of maxillary central incisor with gender and facial form into consideration.
2. To determine if a relationship exist between inner canthal, inter pupillary, inter tragal distance, bizygomatic width and relate these findings to the mesiodistal width of Maxillary central incisor, taking gender and facial form into consideration.
7. MATERIALS AND METHODS
7.1 Source of data
1. Young adults between the age group of 21 to35 years of South Indian origin, who would be attending the O.P.D of M.S.Ramaiah Dental College.
2. Digital vernier caliper with an accuracy of 0.01 mm (Aerospace).
7.1 Method of collection of data
The subjects included in this study will be explained about the procedure, purpose of study and informed consent will be taken. The subjects would then be broadly divided into two groups based on gender as
Group A : Male (150 subjects)
Group B : Female (150 subjects)
They would be further divided into three sub groups based on facial index as
Subgroup (a) : Leptoprosopic face (long and narrow) - facial index of 90 or above
Subgroup (b) : Mesoprosopic face (ovoid) - facial index between 85 to 89.9
Subgroup (c) : Euryprosopic face (square) – facial index between 80 to 84
Distribution of subjects:
Group A (total: 150 subjects)Group B (total :150 subjects)
Sub group (a) :50 subjects Sub group (a1) :50 subjects
Sub group (b) :50 subjects Sub group (b1) :50 subjects
Sub group (c) :50 subjects Sub group (c1) :50 subjects
Thus a total of 300 subjects are included in this study.
After assigning each subject to either of the above mentioned subgroups the facial and dental measurements are obtained.
Natural tooth measurement
The mesiodistal widths of maxillary central incisors will be recorded intra orally with the help of the digital vernier caliper. The widths will be summed up and divided by two.
Determination of anthropological measurement
The subjects are seated in a dental chair with their head supported in upright position and made to look forward.
1. Inner canthal distance- The arms of the caliper would be adjusted so that it gently contacts the medial angles of the palpebral fissures of the eyes. The value obtained will be recorded as the inner canthal distance.
2. Inter pupillary distance- The caliper will be adjusted so that arms of the caliper coincide with the mid point of the pupil. This value obtained will be recorded as inter pupillary distance.
3. Inter tragal distance- The caliper will be positioned so that the arms of the caliper touch the superior tip of the tragus and the value recorded.
4. Bizygomatic width- The arms of the caliper will be adjusted to coincide with the most prominent point of the zygomatic process (zygoma) and the value obtained will be recorded.
1. Young adults belonging to the age group of 21 to 35 years of south Indian origin for at least three generations.
EXCLUSION CRITERIA Presence of caries or restoration on maxillary central incisor.
Severe attrition of maxillary central incisors.
Presence of orbital disease or discrepancies.
History of facial trauma or surgery.
Presence of diastema, rotation, slight tilting or crowding of maxillary central incisor.
Presence of tragal discrepancies.
The data obtained may be analyzed using descriptive statistics and Pearson correlation coefficients to determine whether correlation exists between the anthropological measurements and the width of the maxillary central incisor.
7.3 Does the study require any investigation or intervention to be conducted on patients or other human or animal? If so describe in briefly
Yes. This study does not include any investigation or invasive procedures. The anthropological measurements of the subjects included in the study are carried out after explaining the procedure and obtaining the informed consent .
1. Mohameed Aleem Abdullah 2002 “Inner canthal distance and geometric progression as a predictor of maxillary central incisor width” J Prosthet Dent 88;16-20.
2. Khalid A. Al Wazzan 2001 “The relationship between inter canthal dimension and the width of maxillary anterior teeth” J Prosthet Dent 86;608-12.
3. Vanderlei Luiz Gomes, Luiz Carlos Gonçalves, Celio Jesus do Prado, Itamar Lopes Junior, Barbara de Lima Lucus 2006 “Correlation between facial measurement and mesiodistal width of maxillary anterior teeth”J Esthetic Restr Dent 18; 196-205.
4. Dubravka Knezovi’c Zlatari’c , Ela Krisstek Poey Ling Loh, Gilberto Hanke, Mitsunobu Okamura ,Kwang –hunJo , Carlis A.Munoz, W.Patrick Naylor 2007” Analysis of width / length ratio of normal clinical crown of the maxillary anterior dentition : Correlation between dental proportion and facial measurements.”Int J Prosthodontics 20; 313-15.
5. TF Fok , KL Hon 2003 “Facial anthropometry of Hongkong Chinese babies” OrthoCraniofacial Res 6;164-6
Signature of Witness__________________________ Date __________________________
CERTIFICATE OF ETHICAL CLEAREANCE
This is to certify that DR. SMITHA RAVINDRAN is a post graduate (M.D.S) student in the department of PROSTHODONTICS. She was admitted to this course for the academic year 2007-2008.The ethical committee has issued ethical clearance to the candidate to carry on dissertation work on the synopsis / topic submitted by her.
Dr. Chaitanya Babu Dr.H.N. Shama Rao Chairperson Principal