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2. AIMS AND OBJECTIVES
3. REVIEW OF LITERATURE
4. MATERIALS AND METHODS
Table 1: Descriptive statistics for comparison of predominant maxillary central incisor tooth form in males and females of Saudi Arabian population.
Table 2: Descriptive statistics for comparison of predominant maxillary arch form in males and females of Saudi Arabian population.
Table 3 : Descriptive statistics for comparison of predominant palatal form in males and females of Saudi Arabian population.
Graph 1: Comparison of predominant maxillary central incisor tooth form in males and females of Saudi Arabian population.
Graph 2: Comparison of predominant maxillary arch form in males and females of Saudi Arabian population.
Graph 3: Comparison of predominant palatal form in males and females of Saudi Arabian population.
Figure 1: Frontal photograph of the maxillary incisor teeth.
Figure 2: Occlusal photograph of the maxillary dental arch.
Figure 3: Occlusal photograph of the maxillary dental arch for cross sectional palatal form.
Figure 4: Tracing printout of the maxillary incisor tooth form.
Figure 5: Tracing printout of the maxillary arch form.
Figure 6: Tracing printout of the palatal form.
Facial esthetics has important social and psychological effects on the human personality in which the appearance of anterior teeth is critical for an attractive face and pleasing smile. Thus, dental and facial esthetics is the common aim for all patients seeking dental treatment. When only parts of the dentition have to be restored, the remaining natural dentition can serve as a guide. However, in cases where the entire dentition has to be restored and no information can be gained from remaining natural teeth, old photographs, or cast models, other methods have to be applied to select and design the missing teeth. One of the most crucial parameters in this context is in selecting the correct shape and size of the maxillary anterior teeth. 
The review of dental literature reveals several factors, methods, techniques and theories that have been suggested as aids for artificial tooth selection. The most universally accepted “Law of Harmony” was stated by James Leon William 1914 who hypothesized the relation between the form of inverted maxillary central incisor and the face form. Numerous studies [1, 4, 5] have been conducted on various population groups based on William’s geometric theory to evaluate the correlation between the tooth form and the face form. Among which some studies proved [6, 7] with positive results while many others [8, 9, 10] disproved which may be attributed due to racial and gender differences. [2, 11, 12, 13]
In prosthetic dentistry, sex related differences in tooth forms and arrangement of anterior teeth are assumed and optimal esthetics is also assumed to be achieved only if the face, arch, and tooth forms are in harmony. Furthermore, these forms are classified as square, tapering or ovoid by use of basic geometric shapes along with additional combination forms. Nelson’s  “Esthetic triangle” theory proposed a close relationship between face, tooth, arch and alignment but the studies revealed insignificant correlation and was not highly defined. [1, 14]
Currently, there is no such universally accepted single esthetic factor that can be reliably used in artificial tooth selection. Also, among Saudi population, there is lack of research evidence pertaining to factors related to artificial tooth selection for edentulous patients. So, the present clinical study was conducted to classify various anterior tooth forms, arch forms and palatal forms with its predominant occurrence in both males and females of Saudi population. The results thus obtained would be used as guidelines during selection of teeth, arrangement of teeth among edentulous patients of Saudi Arabian population for esthetically pleasing fixed and removable dental prosthesis.
To determine predominant maxillary central incisor tooth form in males and females of Saudi Arabian population.
To determine predominant maxillary arch form in males and females of Saudi Arabian population.
To determine predominant palatal form in males and females of Saudi Arabian population.
The correlation thus obtained could be used in the selection and arrangement of artificial teeth for edentulous patients of Saudi Arabian population.
Young HA3 (1954) suggested that the size of upper central incisor tooth should be in harmony with the face size. The tooth proportion of width to length should be closely parallel in the facial proportion; particularly the central incisor. In his article he has mentioned twenty one techniques of selecting anterior tooth mold.
Bell RA4 (1978) tested the validity of William’s geometric theory of selection of artificial teeth. He observed that the significance was low to establish any correlation between the face forms and form of maxillary central incisors. Therefore the geometric theory was invalid. The maxillary central incisors of 31 subjects were radiographed and photographed, the cast of maxillary arch were made and subject’s faces were photographed. Three dentists classified the form of maxillary central incisors as shown by intra oral photographs, radiographs made by the paralleling technique and from the casts. The face forms were classified from frontal view photographs. The relationship of face form to tooth form as seen on the casts were as follows: ovoid tooth form related to 4 in ovoid face forms, 4 in square face forms and 1 in tapered face form with total of 9 (29%), square tooth forms was related to 8 in ovoid, 6 in square and 4 in tapered face forms with a total of 18 (58%). These data were fed to a computer to determine if a correlation axis existed. But there was no correlation between the form of the face and form of the maxillary central incisors.
Mavroskoufis F, Ritchie GM5 (1980) have investigated on 70 dental students, predominantly white, to assess the validity of the method based on Williams “law of harmony” for the selection of upper central incisor teeth by two standardized photographs of the face and the two maxillary central incisors. The outline forms of the “actual” face and then of the “apparent” face were drawn on a thin white paper of appropriate translucency. On the “actual face” outline, a straight line joined the highest points of the eyebrows, the ends of it then bending downward to meet the most lateral visible point of the zygomatic arch. Each line continued downward by following the outlines of the cheeks and chin, until meeting in the region of the symphysis menti. When recording the “apparent” face, the upper portion of the outline was drawn to follow the hair-skin border line, thus including the forehead of the subject into the face form. The outlines forms of maxillary central incisors were drawn and superimposed on the face forms outline. The formula devised for assessing the comparability of face forms and tooth forms was:
Where; Lf = length of the recorded face form.
Lt = projected length of tooth from drawn on the face diagram.
D = difference in length
When D did not exceed 1%, implied a negligible difference in length, the related forms were considered identical. When D ranged between 1% and 7%, the compared forms were designated as “similar”. When any value exceeded a 7% difference, the forms were considered “dissimilar”. The authors employed the same procedure for comparison with both “actual” and “apparent” face forms and with both right and left maxillary central incisor forms. The results between the comparison of 70 “apparent” face forms with the tooth outline forms of 140 maxillary central incisors (70 right and 70 left) showed that for 8 students 5.7% correlated forms were identical, for 36 students 25.6% were similar and for 96 students 68.7% there was a dissimilarity. Similarly in comparison between the tooth forms and the “actual” face form, only 2 students 1.45% were identical, for 22 students 15.75% were similar and for 116 students 82.8% were dissimilar. The authors concluded that the observations showed greater percentage of dissimilarity between incisor form and face form, both “actual” and “apparent” than similarity. Thus the selection of teeth based on the proposed “law of harmony” had no validity.
Marunick MT, Chamberlain BB, Robison C 24 (1983) conducted a study to evaluate whether the lay public perceives anterior teeth selected by Williams’s typal matching method as aesthetically pleasing by testing laymen responding to questions about photographs of three edentulous male and female patients who were representatives of square, tapering and ovoid facial forms. The photographs were portrait views of the patients wearing different dentures displaying square, tapering, and ovoid teeth. It was concluded that, most individuals did not focus on the dentition as the dominant characteristic of the photograph until their attention was directed to the shapes of the teeth. This suggested typal matching may be of negligible importance in denture aesthetics in comparison to other factors such as tooth size, arrangement and contour of the gingival border. Preferences for square teeth for males and ovoid teeth for females support the dentogenic concept.
Sellen PN, Phil B, Jagger DC, Harrison A1 (1998) described a new method incorporating a computer program to analyze four esthetics factors form of the face, arch form, palatal contour and tooth shape, to determine whether there was correlation between tooth, face and arch forms and palatal contour among 50 dentate dental students (30 females and 20 males) with age ranging from 20-31 years. Irreversible hydrocolloid impression of maxillary dentition was made and study casts prepared with 50/50 plaster / stone. Standardized photographs were taken to correlate the esthetic factors by super imposition of the outline tracings. A visual analysis was made to determine the extent of correlation and the findings recorded on one of three categories -
1) Correspond: In those cases of superimposition where correlation was at its best, conformity in outline as low as 80% was sufficient to give a very close visual match.
2) Similar: Outline tracings that correspond with another factor between 50% and 80% of its entirely, visually having some resemblance in form during superimposition.
3) Dissimilar: Where superimposition coincide less than 50% visual resemblance between tracing and factor differed significantly and was often negligible.
The results showed that for correlation by visual analysis of tooth to face form nearly half of the comparisons were dissimilar being 22 (44%) in which males (40.9%) and females (59.1%) and only 11 (22%) corresponded with males 36.4% and females 63.3% had the lowest level of correspondence. Those correlated to be similar where 17 (34%) with males 35.3% and females 64.7%. Highest correspondence 28% occurred between arches to face form, followed by arch to tooth form 24%. Arch to tooth showed the lowest level of dissimilarity of 32%. Among the correlation of classification in each subject, men tended to dominate tapering classes, whereas women dominated square and ovoid classes. The palatal contours possess characteristic outlines that are incompatible in shape with outline forms of other three factors. Therefore it was not possible to assess correlation by superimposition of outline forms of palatal contour with tooth, face and arch forms. It was concluded that correspondence of outline forms through superimposition revealed an insignificant correlation between face, tooth and arch forms. Although this method applies high technology, that does not improve the accuracy of determining shape and size of teeth in an edentulous patient. The cost and complexity of the method of measurement may also make it impractical for common application.
Ibrahimagic L, Jerolimov V, Celebic A, Carek V, Baucic I, Zlataric DK9 (2001) conducted a study to re-examine Leon Williams geometric theory and to find the degree of correspondence between the face and the tooth form in the population of Zenica, Bosnia and Herzegovina. Two thousand individuals with intact frontal teeth, in age between 17 and 24 years, were measured for 3 horizontal distances on the face: temporal width (Ft-Ft), zygomatic width (Zyg-Zyg) and gonial width (Go-Go) and for 3 horizontal distances on the both upper incisors: cervical width (CW), contact point width (CPW) and incisal width (IW). The length of the face (Tr-Gn) as well as the length of the central maxillary incisors was also measured. The results revealed: 1. Men had significantly larger dimensions for all facial and tooth dimensions (p < 0.05) than women, except for the cervical tooth width (p > 0.05); the left and the right central incisors were of identical dimensions and forms (p > 0.05). 2. The width of upper central incisors were smaller approximately 1.5 mm than in west Europeans. 3. Upon the relation between the 3 horizontal dimensions measured on the face and upper maxillary incisor, 11 facial forms and 10 upper central tooth forms could be recognised in the study population, but 98% of the population had only 3 tooth and face forms. Face shapes: Oval faces--83.3%, square-tapered face--9.2% and tapered face--7%; tooth forms: tapered-square incisor--53%, oval incisor--30%, tapered incisor--16%. 4. Reversed and enlarged tooth form was in line associated with the facial form in only 30%, while the most common combination was of the oval face form and the tapered-square central incisor (45%). 5. These results disapprove William's theory and may be helpful for the choice of artificial teeth in complete denture construction and the dental industry.
Smily PK, Nair KNV, Kumar CP, Nagaraj KR, Kumar MV13 (2002) conducted a study to analyze whether the gender difference exists in the harmony of tooth form to face form and tooth form to arch form on 60 dentate dental students in which 30 were males and 30 were females with age group 18-22years. Face forms and tooth forms were classified as given by William’s into square, tapering and ovoid. Hydrocolloid impression of maxillary arch of the students was made and cast poured in dental stone. From these study models, arch form was visually analyzed and classified as square, tapering and ovoid arch forms. The data obtained was statistically analyzed. The result showed the harmony of tooth form to face form was similar only in square tooth forms in 6 (20%) males and in 9 (30%) females. It was concluded that harmony between tooth form and face form is predominant in females as numerical value only and no statistical significance was found. No theory or concept about artificial teeth selection may be universally accepted to all clinical situations.
Berksun S, Hasanreisoglu U, Gokdeniz B14 (2002) conducted a computer based programme among randomly selected 60 subjects (25 males and 35 females) to evaluate whether anterior tooth form reflects gender identification and to question the hypothesis that was there a correlation among face, arch, and tooth forms on the basis of dentists’ perception. Standardized photographs of full face, dental arch and anterior tooth images were taken. The average values of face-to-arch form were 54% and face-to-tooth form was 51%, correlations were higher than the tooth-to-arch form correlation of 46%. The overall correlation among all forms was 31%. A database was arranged as a questionnaire for evaluation by 13 prosthodontists who were asked to define the sex and morphologic features by examining the images of the subjects taken. The results of gender identification of the subjects showed that the experts were unsuccessful in distinguishing actual sex by visual assessment of anterior tooth segment alone. There was also significant interobserver and intraobserver difference in classifying face, arch and especially tooth forms. The correlation among these forms was not highly defined.
Wolfart S, Menzel H, Kern M7 (2004) examined whether there exists a gender-dependent correlation between the inverted face shape and that of the upper central incisor. Two standardized photographs of each 204 Caucasian dental students (mean age 23.7 ± 2.7 years) of 102 males and 102 females were taken, portrait (closed lips) and the anterior teeth without lips. Standardized enlargements (5.5:1) of facial outlines and of the upper right incisor outlines were traced, copied on translucent foil, and were analyzed as follows.
Evaluation of tooth shape - The outline of the upper right incisor was traced; the median of the tooth was drawn in the sketch. (X) was the most apical point of intersection between the median and the outline of incisor. The Mesial and distal tangents were constructed to the outline – parallel to the median. Two perpendiculars were dropped on the median starting from the most apical (O1) and the most incisal (O2) point of intersection between the outline and the tangent. Two points of intersection (S1 and S2) are defined. The line S1 and S2 was bisected by S. By taking the width of the tooth through (S) the widest stretch across the tooth was defined (TB). Dividing the line SX into five parts, the line TA could be constructed parallel to TB on 4/5 of the length of XS.
Evaluation of face shape - The outline sketch was turned upside down. The lines FB (the widest stretch across the face) and FA (a defined parallel stretch to line FB) were constructed in an analogous manner to the lines TA and TB.
Classification of tooth and face shape – The quotient (TQ and FQ) of the lengths TA/TB and FA/FB was calculated. Tooth and face shape were classified as tapered if FQ or TQ £ 0.61, as ovoid if FQ or TQ were between 0.62 and 0.69, and as square-shaped if FQ or TQ ³ were between 0.70.
The tooth form quotient (TQ) and face form quotient (FQ) was calculated. The evaluation was done by 5 dental practitioners with 10 year experience and 5 post graduate students with 1-2 years experience.
The results obtained were as follows: Tooth shape was classified in 25% of the cases as tapered, 39% as ovoid and 36% as square tooth shapes. Face shape was classified in 27% of the cases as tapered, 41% as ovoid and 32% as square face shapes. Tapered faces were more common in female subjects of 34% than males 21%. Square faces were less common in female subjects of 26% than males of 38%. Approximately 35% of all the cases tooth and face shapes conformed but no statistically significant correlation was found. They concluded that both the theory that the tooth shape corresponds to the inverted facial shape, nor the theory that female tooth shape is more often ovoid and the male tooth shape more square is confirmed. A significant correlation was shown between face shape and gender but not between tooth shape and gender. The participants were not able to determine the gender of a person from strictly intraoral photographs alone. Therefore, the rules concerning the selection of anterior teeth should be reconsidered. Neither the inverted facial shape nor the gender should be used as guidelines for anterior tooth selection in complete dentures because it could lead to unsatisfactory results. Instead, the opinions and desires of the patients should be taken into account to ensure optimal dental aesthetics for each individual.
Lindemann HB, Knauer C, Pfeiffer P6 (2004) did a study to determine whether a relationship exists between maxillary central incisors and face shapes in 50 men (age range 18-74 years, mean 45.8 ± 17.7 years) and 50 women (age range 19-79 years, mean 43.2 ± 16.8 years). Casts were made of the maxillary anterior teeth of 50 men and 50 women. A standardized digital photographic procedure was used to record frontal views of each subject’s face and of the maxillary central incisors of the dental casts. For the determination of tooth shape, casts were obtained from irreversible hydrocolloid impressions of the maxillary anterior teeth. A circular marking around each anterior tooth were made with lead pencil and each tooth was photographed. The orthogonal projection of tooth picture was first converted into grey scale and later selected manually with use of lasso function of a graphics program. The contour shape of each anterior tooth was generated as a black and white bitmap file. Determination of face shape was done by measuring the distance between the hairline to the chin margin as well as from the eyebrow line to the chin margin using caliper and a slide gauge. The shapes of the maxillary central incisors were compared with the face forms and were evaluated according to their Hausdorff distance (HDD). The function h(A,B) is called the directed HDD from shape A (face outline form) to shape B (tooth outline form). The similarity of both shapes is given as a non-negative number. The value (0,0) indicates the figures are identical. Higher values indicate that shapes differ more substantially.
The results showed that the tooth shapes of maxillary right and left central incisors of each subject are more similar than the tooth shapes of different subjects. Face shape (superior edges of the eyebrows to the chin margin) produced a better match than face shape (hairline to chin margin). The maxillary central incisors of women displayed a significant smaller HDD than men. The heights of the maxillary central incisors of men are longer than women (1.09 versus 1.04). No significant difference between the widths of maxillary central incisors of men and women was found (0.91 versus 0.89).
It was concluded that neither the maxillary central incisor nor the face shapes could be classified in a three or four class pattern. The height of maxillary central incisors displayed significant sex specific differences in which of men were longer. There was no significant difference between the widths of the maxillary central incisors displayed that was higher by a factor of 1.9 than the face shapes (chin margin to the eyebrow line). Maxillary central incisors produced a better match with the face shape from the chin margin to the eyebrow line than from the chin to the hair line. Comparison of tooth and face shapes was 0.108 for hairline to chin margin and 0.084 for eyebrow line to chin margin.
Hasanreisoglu U, Berksun S, Aras K, Arslan I11 (2005) analyzed the clinical crown dimensions of maxillary anterior teeth to determine whether consistent relationships exist between tooth width and several facial measurements in a subset of the Turkish population. Full-face and anterior tooth images of 100 Turkish dental students viewed from the front and engaged in maximum smiling were recorded with digital photography under standardized conditions. Gypsum casts of the maxillary arches of the subjects were also made. The dimensions of the anterior teeth, the occurrence of the golden ratio, the difference between the actual and perceived sizes, and the relationship between the anterior teeth and several facial measurements by gender were analyzed using the information obtained from both the computer images and the casts.
The results showed the mean coronal tooth width-to-height ratios for men versus women, respectively were as follows: central incisor, 88.7% versus 91.2%; lateral incisor, 82.1% versus 83.4%; and canine, 83.4% versus 87.3%. Lateral incisor did not exhibit significant gender difference in width and height values. Significant difference emerged when mean ratio between various perceived widths of central incisor to lateral incisor and canines and to lateral incisors were compared with their ideal golden ratio of 1.618 and 0.618 respectively for both genders.
It was concluded that the maxillary central incisor and canine dimensions of men were greater than those of women in the Turkish population studied, with the canines showing the greatest gender variation. Neither a golden proportion nor any other recurrent proportion for all anterior teeth was determined. Bizygomatic width and interalar width may serve as references for establishing the ideal width of the maxillary anterior teeth, particularly in women.
Vajao FM, Nogueira SS, Filho JNA12 (2006) conducted a study to evaluate the correlation between the central incisor form and face form in 4 racial groups of Brazilian population and to investigate if there was agreement among the experts in categorizing the central incisor forms. 160 Brazilian subjects (40 Whites, 40 Blacks, 40 Mulattos and 40 Asians) with age ranging from 18-33 years were selected. Standardized photographic procedure was used to obtain images of the maxillary central incisors and the face. Each subject was seated with the head supported by a head rest and with the occlusal plane of maxillary teeth parallel to the floor. Intraoral photographs of the maxillary right central incisor were made with a digital camera mounted on a tripod. The camera was adjusted until the lens was parallel to the buccal surface of the tooth. Cheek retractors were used to obtain full exposure of the central incisors. A full face photograph with closed lips was also obtained, with the lens positioned parallel to the subject’s face.
The images of the tooth and the face were transferred to a computer having image editing software (Photoshop 5.0, Adobe) so that they could be edited. An outline tracing of the tooth was made around the buccal surface of the central incisor, which corresponded to the mesial and distal contours, the incisal edge and cervical margin. An outline tracing of the face was drawn to follow the hairline, thus including the forehead. The line then curved downward and met the most lateral visible point of the zygomas. From there each line continued downward by following the outer lines of the cheeks and chin, until meeting in the region of the symphysis menti.
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