the correlation of bizygomatic width and ridge...

727Drug Invention Today | Vol 10 • Issue 5 • 2018

The correlation of bizygomatic width and ridge relationships in determination of width of maxillary anterior teethNor Masitah Mohamed Shukri1, Ashish R. Jain2*

INTRODUCTIONA prosthetic denture has always been biologically compatible and desirable for both dentulous and edentulous patient as it always meets patients’ satisfaction with their daily life, oral status, and treatment. This also emphasizes that esthetics is an important criteria in patient’s consideration psychology. In relation to this, the selection of maxillary anterior teeth is the primary consideration because it plays a significant role in facial esthetic that a correct proportion is important for facial rhythm.[1] According to Young, “it is apparent that beauty, harmony, naturalness, and individuality are major qualities of esthetics.”[2]

Research Article

1Department of Prosthodontics, Saveetha Dental College, Saveetha University, Chennai, Tamil Nadu, India, 2Department of Prosthodontics, Saveetha Dental College and Hospital, Saveetha University, Chennai, Tamil Nadu, India

*Corresponding author: Dr. Ashish R. Jain, Department of Prosthodontics, Saveetha Dental College and Hospital, Saveetha University, Poonamallee High Road, Chennai - 600 127, Tamil Nadu, India. Phone: +91-9884233423. E-mail: [email protected]

Received on: 23-02-2017; Revised on: 21-04-2018; Accepted on: 19-05-2018

Access this article online

Website: jprsolutions.info ISSN: 0975-7619

In the early 18th century, Madame Schimmelpeinik introduced the geometric classification of face form and profile, which was used in dentistry for esthetic teeth selection. Later, White projected a consideration of correlation of tooth form and color in 1872. He proposed that the size of the tooth must be in proportional to the face and its color must be corresponding with the facial complexion.[1]

In addition, there are various anatomical methods available for the determination of the correct size of anterior teeth, the width of the eyes, the inner canthal distance, the interpupillary distance, the interalar width, the intercommisural width, and the bizygomatic width (BW). These measurement will be a great aid in teeth selection as maxillary anterior teeth must be harmony to facial appearance to attain esthetic and functionally compatible replacement of missing teeth.[1,3-5] It helps clinician to determine the

ABSTRACT

Background: A denture is fabricated as a coverage prosthesis to replace some or a missing teeth. It has been used extensively to replace the missing dentition which enhances the esthetic pleasing of the patient. Determination of the mesiodistal width of maxillary anterior teeth is one of the difficult aspects in teeth selection. Many attempts have been done to establish methods for estimating the appropriate width of the six maxillary anterior teeth. Aim: The scope of the research was to study the correlation of the bizygomatic width (BW) and ridge relationship in the determination of the width of maxillary anterior teeth. Materials and Methods: A total of 28 students from two populations were participated in this study. 14 students from Malaysia and 14 Indian students were selected. The measurements include facial, dental, and denture cast measurement. The data were analyzed using Karl Pearson correlation test and P-value of the data was considered 0.05 statistically. Result: The population of Indian is having larger width (mean = 11.72 cm) when compared to the Malaysian population (mean = 11.17 cm). The correlation coefficient test in Indian population for facial measurement with the width of the maxillary central incisor (P = 0.05 and r = 0.73) and the total width of the maxillary anterior teeth (P = 0.05 and r = 0.54) showed average correlation. Conclusion: It was found that Indians have relatively higher values of correlation between the BW and hamular notches than the population of Malaysian. There was a high significant correlation between all the parameters for the samples except for the measurement between the distance of interhamular notches and combined width of the maxillary anterior teeth, which showed a weak downhill linear relationship.

KEY WORDS: Bizygomatic, Denture esthetic, Interhamular notch distance, Maxillary anterior teeth, Pound’s formulae, Selection, Teeth

Nor Masitah Mohamed Shukri and Ashish R. Jain

Drug Invention Today | Vol 10 • Issue 5 • 2018728

correct distoproximal size of anterior teeth. These kind guidelines have been introduced to determine the width of maxillary anterior teeth when previous teeth records are not available.

Based on the suggested measurement, three of them are commonly used till now, which are Berry’s biometric ratio method, interalar width measurement, and the canine-to-canine method. The first is introduced by Berry during 1906. He stated that the upper central incisor tooth had a definite proportion to the face anatomy. It was 1: 16 maxillary central incisor (MCI) width to the BW ratio.[1] Second, many suggestions have been made for interalar width with different views in teeth selection. Based on Picard (1958), he was the first to demonstrate that maxillary anterior teeth can be selected based on interalar width. In 1967, another view from Wehner et al. reported that the teeth selection could also be used from the extension parallel lines from the lateral surfaces of the ala of the nose onto the labial surface of maxillary occlusion rim. This measurement had a significant correlation between interalar width and width of the maxillary anterior teeth as stated by Al-el Sheikh (1982).[6] The third method is known as canine-to-canine method because the measurement is along the anterior curvature of the contoured occlusal rim. A flexible ruler is used to record the distance from two marks at both ends which indicated the corners of the patient’s mouth.[1]

In the long standing of lifetime, the anterior portion of maxilla can be resorbed due to the episode of teeth extraction.[7] Edentulism is common in dentate species since the teeth and bone jaws are dynamic and prone to resorption over time.[8] This causing some important anatomical landmarks in the maxilla cannot be used anymore to determine the width of maxillary anterior teeth in denture prosthetic. Nevertheless, hamular notches are not subjected to resorption after the extraction of teeth. It is stated in some studies that hard palate is those that have close relationship between the morphology and the dimension of the MCIs.[9] According to a study by Petricevic, various ratios are calculated: Hamular width/cervical width of central incisor = 5.71, hamular width/incisal width of central incisor = 5.70, and hamular width/contact point 6 width of central incisor = 5.51. In the complete denture patients, the ability of the upper lip and lower lip to have proper contact at the vermillion border and maintain distortion influences the positioning of the anterior teeth. This can be guided by the occlusal rim, and this case may be varying depending on individual. Despite this, incisive papilla can be used because it is made up of dense connective tissue and a stable landmark compared to the measurement on occlusal rim though it has a variety of shape.[10-12] Usually, the middle of the papilla is used to determine the teeth selection.

As mentioned above, there are many presentations of methods to aid in the determination of maxillary anterior teeth but some may not specific. Determination of maxillary anterior teeth is the most important criteria in making prosthetic denture for patient because a denture should be not vary from natural tooth to achieve its esthetic aspect. Furthermore, it is more challenging if the patient does not has previous records to serve as a guide. Therefore, it is necessary for every clinician to identify the best approach with the teeth selection despite the various methods of measurement. The purpose of this study was to study the correlation of determination of the width of maxillary anterior teeth based on the BW and ridge relationship (interhamular notches [IHN] and distance from incisive papilla to right and left hamular notches).

MATERIALS AND METHODSA total sample of 28 students from two populations were participated in this study. 14 students from Malaysia and 14 local students were included. The sample size was determined based on the G Power analysis.[13] It was calculated using prevalence of 0.05%, and the precision (d) is 0.08.

Sample sizeZ p p

d

a =

−( )−1 2

2

2

1/

Here,

Z 1–α/22 is the standard normal variate. As in majority of studies, P values are considered as 0.05, so 1.96 is used in formula.

P is the expected proportion in a population based on previous studies, and the value is 0.05.

d is the absolute error or precision and it is 0.08.

Samplesize =×

=1 96 0 05 1 0 05

0 0528

2

2

. . ( - . )

.

The criteria selection are having normal overjet and overbite, should have all permanent maxillary anterior and premolar teeth, having less missing teeth, symmetrical arches, angle Class I occlusion, and those above 18 years old (complete facial growth). Participants having gingival recession and frontal teeth with attrition, dental restoration that can grossly affected the width of maxillary anterior teeth, gingival inflammation or hypertrophy, and prosthetic appliances were excluded from this study. All of them were informed about the aim and method of this study for their acknowledgment.

Alginate (Zhermack Tropicalgin Alginate 453 g) impressions of the maxillary jaw were made from each



participant, and the casts were poured into hard stones (Onpharno Lifesciences 3 kg). The measurements were taken on the hard stones by using a Vernier caliper (Generic Mini Portable 100 Mm Brass Vernier Caliper Double Scale Mm/Inch). The measurements were divided into extraoral and intraoral. The extraoral is the BW, and the intraoral is the length and width of the MCI (WMCI).

Selection of MeasurementFacial measurement (BW)In this method, a Vernier caliper was used to measure the distance from the most prominent point on the zygomatic bone on both the sides without applying a pressure [Figure 1]. The participant must be in erect position and at rest.

Dental measurementThe mesiodistal widths of the maxillary anterior teeth were measured from canine to canine. It was measured by Vernier caliper with 0.1 cm precise at the maximum coronal width of the tooth [Figure 2]. Each measurement of the widths of maxillary anterior teeth was taken and added to give a total width for six maxillary anterior teeth.

Denture cast measurementThe measurement was made on the denture cast based on two important marks: Hamular notch on the left and right side and incisive papilla. Hamular distance (distance between the mesial side of the right and left hamular notch) and distance from right hamular notch to incisive papilla and left hamular notch to the incisive papilla were measured on the casts. Dental floss is used to measure the distance as mentioned above and it is recorded by a stainless ruler in Figure 3.

RESULTSThis study comprised of 28 subjects in total which divided into halves of Indian and Malaysian population. The minimum age of the subject was 20 years and maximum 22 years, while the mean age was 21.53. The data were analyzed using Karl Pearson correlation test and P-value of the data was considered 0.05 statistically. The Pearson correlation was applied to check the relationship between facial measurement (BW) and distance of the IHN. In addition, it was also used to determine the correlation of facial measurement and hamular notch on both the sides. Another parameter in this study was the relationship between facial measurement and WMCI. The attribution of the distance of the IHN and combined width of maxillary anterior teeth were also measured.

According to this present study, Table 1 shows the comparison between Indian and Malaysian population based on four parameters, namely, facial measurement (BW), denture cast measurement (IHN), and dental

Figure 1: Bizygomatic width measurement

Figure 2: Mesiodistal width of each maxillary anterior teeth

Figure 3: Denture cast measurement. (a) Measurement of incisive papilla to right hamular notch. (b) Measurement of incisive papilla to left hamular notch. (c) Measurement between hamularnotches on both sides



measurement (intercanine distance and the WMCI). As depicted in Table 1, the population of Indian was having larger bizygomatic width (mean = 11.72 cm) when compared to the Malaysian population (mean = 11.17cm). The distance of IHN was showing that Indian population has a longer distance than Malaysian population with a mean of 5.60 cm and standard deviation of 0.48 cm. Again, dental measurement (intercanine distance and the WMCI) in Indian population has a higher value of mean and inversely proportional to the value of the standard deviation [Table 1].

In these scattered graphs, the result showed good correlation coefficient values in Indians. It can be observed in Malaysia population; there is a linear downhill of the correlation between the IHN and facial measurements [Figure 4].

There are positive correlation between facial measurement (bizygomatic width) and dental measurement (width of the maxillary central incisor). However, this correlation is seen to be greater in the population of Indian compared to Malaysians [Figure 5].

Indians have a higher value of correlation coefficient test value than Malaysians. The result was found to have a positive correlation on the population of Indian and inversely seen in Malaysians. This is depicted in the two graphs as shown in Figure 6.

It can be seen that the overall values of correlation coefficient in Indians were higher than in Malaysian population. In the Indian population, the Pearson correlation coefficient test between facial and IHN measurements was found to be 0.56, meanwhile −0.08 for Malaysians. Plus, both correlations of facial measurement with right and left hamular notches in Indians were an excellent agreement as they were more than half. The correlation coefficient test in Indian population for facial measurement with the WMCI (P = 0.05 and r = 0.73) and the total width of the maxillary anterior teeth (P = 0.05 and r = 0.25) showed an average correlation. In Malaysian population, Pearson correlation coefficient test between facial measurement and WMCI showed an excellent agreement, which was r = 0.45. The result for the correlation coefficient test between the distance of right and left hamular notches and the width of intercanine

Table 1: Comparison of facial, dental, and denture cast measurement in Malaysians and Indians descriptive statistics

Population Variables BW (cm) IHN (cm) ICD (cm) MCI (cm)Indian Mean 11.72 5.60 3.60 0.91

n 14 14 14 14SD 0.47 0.48 0.16 0.14

Malaysian Mean 11.17 4.95 3.52 0.90n 14 14 14 14SD 0.67 0.31 0.27 0.08

SD: Standard deviation, BW: Bizygomatic width, IHN: Interhamular notches, ICD: Intercanine distance, MCI: Maxillary central incisor

Table 2: Correlation coefficient of facial, dental, and denture cast measurement in Malaysians and Indians descriptive statistics

Parameter Mean±SD (cm) n Correlation “r”Indian

Facial measurement 11.72 (0.47) 14 0.56IHN measurement 5.60 (0.48) 14Facial measurement 11.72 (0.47) 14 0.58IP-RHN measurement 6.35 (0.65) 14Facial measurement 11.72 (0.47) 14 0.50IP-LHN measurement 6.26 (0.76) 14Facial measurement 11.72 (0.47) 14 0.73WMCI measurement 0.91 (0.14) 14Denture cast measurement 5.60 (0.48) 14 0.25IC measurement 3.60 (0.16) 14

MalaysianFacial measurement 11.17 (0.67) 14 −0.08IHN measurement 4.95 (0.31) 14Facial measurement 11.17 (0.67) 14 0.37IP-RHN measurement 5.24 (0.30) 14Facial measurement 11.17 (0.67) 14 0.18IP-LHN measurement 5.27 (0.30) 14Facial measurement 11.17 (0.67) 14 0.45WMCI measurement 0.90 (0.08) 14Denture cast measurement 4.95 (3.52) 14 −0.16IC measurement 0.31 (0.27) 14

IHN: Inter hamular notches, IP-RHN: Incisive papilla to right hamular notch, IP-LHN: Incisive papilla to left hamular notch, WMCI: Width of maxillary central incisor, IC: Intercanines



distance in Indian and Malaysian subjects was found to be r = 0.25 and r = −0.16, respectively [Table 2].

DISCUSSIONIn general, teeth selection is an important step in the fabrication of a denture regardless in a complete edentulous or partially edentulous patient to meet up their satisfaction. As each single population on Earth has genetically variant of dental and facial measurement due to geographical location and

family background, it is significantly to have broad knowledge regarding tooth norm group for easier teeth selection. Based on Pound, there are five qualities that must be in harmony to restore facial appearance and function, namely, size, color, form, arrangement, and the framing of the teeth.[14] This also emphasizes the correct distribution and proportion between the facial measurement and the width of the anterior teeth.[15]

It has been noted in the result that Indian population has relatively higher values of mean than the population

Figure 4: Correlation coefficient between interhamular notches and facial measurement

Figure 6: Correlation coefficient between facial and dental measurement

Figure 5: Correlation coefficient between dental and denture cast measurement



of Malaysian for each parameter used. This finding suggests that it can be related due to the factor of the racial norms and gender characteristics. However, additional research with a large sample size is needed before anticipating the result to the general population. The result in this study showed that the value of mean based on facial width in Indians (11.72 cm) is slightly greater than Malaysia population (11.17 cm). Based on a study done by Shetti (2011), the comparison between Indian and Malaysian subjects exhibits that Indian had a higher facial width (mean = 12.12 cm) than Malaysians (mean = 11.97 cm) though the difference is not statistically significant. She also mentioned the facial index in both the nations that the Indian population had a high mean value of facial index, more 0.28 than Malaysians.[16] Similarly, Salim in 2017 reported that Indians were having larger dimensional of anterior teeth (mean = 9.25 mm) compared to Malaysian population (mean = 9.23 mm).[17] In addition to this, there have been many studies in the past that significantly show gender variations in the dimension of the anterior teeth. The size and morphology of the maxillary anterior teeth in men exhibit wider teeth than women. Gillen et al. found that the width and length of the maxillary anterior teeth of men were greater than those in women, African and American population.[18]

Universally, the average WMCI is estimated to be 1:16 to the BW. The result of this study showed a high significant correlation between all the parameters for the samples except for the measurement between the distance of IHN and combined width of the maxillary anterior teeth, which showed a weak downhill linear relationship. There was no correlation between denture cast and dental measurement in the Malaysians. This can be because of the selection of teeth that can make this procedure tentative as being said by Boucher. A study by Forrest et al. stated that there is a correlation between BW and the MCI and Hasanreisoglu et al. found that females have the most correlation between BW and the WMCI than those in males.[19]

In Graph 6, the distance of IHN again shows that Indian population has a longer distance than Malaysian population with a mean of 5.60 cm and standard deviation of 0.48. The value of mean of the IHN in a study conducted by Ranjan was 46.22 cm and a standard deviation of 2.50.[20] The large different values can be explained on the basis of the sample size studied. It can be deduced based on those values that Indians tend to have greater distance of IHN and wider width of the six maxillary anterior teeth. The distance between two hamular notches on both sides will give the width measurement of the combined six maxillary anterior teeth. This can be supported by Petricevic et al. as he concluded that the distance of IHN is equal to the combined width of maxillary anterior teeth.[9,21]

When reviewing the correlation coefficient between facial and IHN measurements, it was showed that Indians had a great relationship between these two variables compared to population of Malaysian. Again, concordance between facial measurement and the distances of incisive papilla to hamular notches on both sides was highest in Indians. This result emphasizes that facial and denture cast measurement are not reliable for selecting maxillary anterior teeth in Malaysian population. In this study, there was no significant correlation between denture cast and dental measurement in the Malaysians. It can be explained by varying anatomical landmarks in between ethnic group variations. Furthermore, such parameters such as the proximal wearing of teeth with aging, gender, and ethnic variations and sample size can limit the reliability in the selection of teeth.[20] It is strongly convincing because in the studies by Ranjan et al.[20] and Guldag et al.[22] both suggested that the interpterygomaxillary notch has no correlation with the width of the six anterior teeth. Unlikely to that, Baker et al. in their study stated that interhamular notch had a strong correlation with the width of anterior teeth by adding 10 mm to it.[1] Similarly, Johnson and Stratton also suggested that adding 5 mm to the interhamular notch could be a guide to select anterior teeth.[23]

CONCLUSIONIn a view of limitation to this study, it can be conclusively that mean values of all parameters measured in the population of Indian tend to be greater than those in Malaysians. A strong correlation was found between the facial and dental measurements in both nations; hence, it can be used predictive factor in the selection of anterior teeth in these two populations. However, the correlation between denture cast and facial measurement in the population of Malaysian was weak. This suggests the demand of implementation of newer study associates with anatomical landmarks in different racial norms for a reliable guide in teeth selection for a particular population.

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Relationship of denture cast measurements to width of maxillary anterior teeth. J Prosthet Dent 2011;105:44-50.

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Source of support: Nil; Conflict of interest: None Declared

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17. Salim NB, Jain AR, Varma A. Reliability of H. pound’s formula for anterior teeth selection. Biomed Pharmacol J 2017;10:2.

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20. Ranjan M, Raj R, Rohit C, Kumara R. Correlation between mesiodistal width of maxillary anterior teeth and interhamular notch distance amongst dakshin kannada population. Int J Contem Med Res 2017;4:1471-4.

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