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ORIGINAL ARTICLE
Year : 2014  |  Volume : 6  |  Issue : 1  |  Page : 31-36

Factors affecting buccal corridor space in Angle's Class II Division 1 malocclusion


1 Department of Orthodontics and Dentofacial Orthopaedics, A. B. Shetty Memorial Institute of Dental Sciences, Mangalore, Karnataka, India
2 Nitte University, A. B. Shetty Memorial Institute of Dental Sciences, Mangalore, Karnataka, India

Date of Web Publication15-May-2014

Correspondence Address:
Ravi M. Subrahmanya
Department of Orthodontics and Dentofacial Orthopaedics, A. B. Shetty Memorial Institute of Dental Sciences, Nitte University, Mangalore - 575 018, Karnataka
India
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Source of Support: None, Conflict of Interest: None


DOI: 10.4103/0975-8844.132578

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  Abstract 

Background and Objectives: Buccal corridor space has been thought of primarily in terms of maxillary width, but there is also evidence that they are heavily influenced by the antero-posterior position of maxilla. The present study was undertaken with an aim of evaluating and comparing the dental and skeletal factors related to buccal corridor space in individuals having Class I and Class II Division 1 malocclusions. Materials and Methods: A total of 80 subjects of which 40 were males and 40 were females in the age group of 20-30 years were selected as per inclusion criteria and were grouped as Group I having Class I malocclusion and as Group II having Class II malocclusions based on angle ANB. 12 linear and 2 angular cephalometric measurements and 4 study cast measurements were used to correlate with the buccal corridor linear ratio (BCLR), calculated on smile photograph using the Adobe Photoshop 7.0 software (Adobe Systems Inc., San Jose, California, USA). The data obtained was statistically evaluated using independent t-test and multiple linear regression analysis. Result: Buccal corridor space is larger in individuals with Class II Division 1 malocclusion when compared with individuals with Class I malocclusions. There exists a significant difference in buccal corridor space between males and females. Conclusion: The present study helps in establishing the correlation between certain factors and the amount of buccal corridor space in individuals having skeletal Class II pattern.

Keywords: Buccal corridor linear ratio, buccal corridor space, Class II malocclusion


How to cite this article:
Bhat R, Subrahmanya RM. Factors affecting buccal corridor space in Angle's Class II Division 1 malocclusion. J Orofac Sci 2014;6:31-6

How to cite this URL:
Bhat R, Subrahmanya RM. Factors affecting buccal corridor space in Angle's Class II Division 1 malocclusion. J Orofac Sci [serial online] 2014 [cited 2019 Nov 13];6:31-6. Available from: http://www.jofs.in/text.asp?2014/6/1/31/132578


  Introduction Top


A smile is the sum of many attributes, both positive and negative. Lip shape, smile index, smile arc, inciso-gingival display and buccal corridor width have been associated with smile esthetics in the past. Smile analysis has been treated as a separate entity from cephalometrics and cast analysis in orthodontic diagnosis and treatment planning. Specific hard and soft-tissue features of the smile have been studied extensively in the literature, but without examination of the relationship between them. [1]

A posed smile is evaluated on the basis of two major characteristics, the amount of tooth display and transverse dimension of smile. More tooth display is considered as more youthful smile. The transverse dimension of smile refers to the broadness of smile or the presence or absence of buccal corridor space. Buccal corridor space is nothing but the distance between the distal point of the canines and the lateral junction of upper and lower lips during smiling. Buccal corridor space has been thought of primarily in terms of maxillary width, but there is also evidence that they are heavily influenced by the antero-posterior position of maxilla in relation to lip drape. It is clearly stated that it is very important for an orthodontist to create an appropriately sized buccal corridor space for a better esthetic smile. [2]

The present study was designed and planned with intentions of quantifying the dental and skeletal factors related to buccal corridor space in antero-posterior, vertical and transverse dimensions in individuals with angle's Class II Division 1 malocclusion and comparing them with that of the individuals having angle's Class I malocclusion.


  Materials and methods Top


A total of 80 subjects (40 males and 40 females) in the age group of 20-30 years were selected as per inclusion criteria. Group I (control group) had 40 individuals (20 males and 20 females) having Class I malocclusion.

Inclusion criteria

  • Class I malocclusion
  • No/minimal crowding, spaces or rotations
  • Near normal occlusion up to second molar
  • Pleasing profile with Class I skeletal pattern


Group II (study group) had 40 individuals (20 males and 20 females) having Class II Division 1 malocclusion.

Inclusion criteria

  • Angle's Class II Division 1 malocclusion
  • No skeletal abnormalities
  • Skeletal Class II pattern


Exclusion criteria

  • Skeletal abnormalities
  • Prior orthodontic/surgical treatments
  • Missing teeth or large prosthesis
  • Craniofacial syndromes


The selected individuals were explained about the procedures and with their consent.

Lateral cephalograms and study casts were made for evaluation. The lateral cephalograms were made under standardized conditions with the Frankfort horizontal plane kept parallel to the floor and the mid facial plane kept in a vertical position using the Planmeca PM 2002 cc proline radiographic machine. The lateral cephalograms were traced on 0.003 inch acetate paper by the same operator in order to avoid inter-operator errors. A total of 12 linear and 02 angular measurements [Figure 1].
Figure 1: Measurements on lateral cephalogram (1) A to N perpendicular (2) B to N perpendicular (3) ANS to N (4) PNS to N (5) Upper central incisor perpendicular to palatal plane (U1-PP) (6) Upper first molar perpendicular to palatal plane (U6-PP) (7) Lower central incisor perpendicular to mandibular plane (L1-PP) (8) Lower first molar perpendicular to mandibular plane (L6-PP) (9) ANS-PNS (10) Go-Gn (11) S-Go (12) ANS-Me (13) OP-SN angle (14) Mandibular plane angle

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Dental cast analysis

Upper and lower impressions were made and study casts prepared. The following measurements were calculated in both the arches.

  • Inter canine width (in mm)
  • Inter premolar width (in mm)


Photographic analysis

Posed smile photographs were made with a digital camera (DSC-W90, 8 megapixel, ×3 zoom). The subjects were positioned with the FH plane and the inter-pupillary line parallel to the floor. The imaginary center line of the patient's face was aligned to the center vertical line on the grid of the viewfinder and both sides of the patient's ears showed the same amount to prevent transverse rotation. Since the buccal corridor can be seen differently according to different light conditions, all photos were made under standardized light conditions to get the actual buccal corridor area.

The images were saved as JPEG files (standard base line format). The mouth area in each photograph was magnified to 1000 pixels, using the Adobe Photoshop 7.0 software (Adobe Systems Inc., San Jose, California, USA). The inter canine and inter commissural widths [Figure 2] were measured in 0.01 mm units with the linear measuring tool in Adobe Photoshop software.
Figure 2: Measurement of buccal corridor space. C-C=Inter canine width, Ch-Ch=Inter commisural width

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Buccal corridor linear ratio (BCLR) was calculated with linear measuring tool in Adobe Photoshop 7.0 software using the formula:



Statistical analysis

The data obtained was statistically evaluated using independent t-test and multiple linear regression analysis. The analyses were carried out by means of statistical software for Windows (SPSS 15.0). In the statistical evaluation, the following levels of significance were used: P ≥ 0.05 (not significant). P < 0.05 and <0.0005 are considered as significant and very highly significant, respectively.


  Results Top


Lateral cephalograms, study casts and frontal photographs of posed smile were obtained from a total of 80 subjects, as per inclusion criteria. The data collected is presented with the following findings.

Independent t-test

The difference in mean value for BCLR between individuals having Class I and Class II Division 1 malocclusion was found to be very highly significant. On comparison of the mean values between males and females in Group I and in Group II, the difference was found to be not significant [Table 1].
Table 1: Comparison of BCLR between groups

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Multiple linear regression analysis

To assess the factors affecting the buccal corridor area in individuals with Class I and Class II Division 1 malocclusion, multiple linear regression analysis was carried out using backward elimination by considering BCLR as the dependent variable.

GO-GN, ANS-SN, A to N perpendicular and inter premolar width of upper arch showed significant correlation in Class I group [Table 2].
Table 2: Multiple regression analysis for Group I

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In males of Class I group, the most influencing factors on BCLR were, B-N perpendicular, A-N perpendicular, ANS-N, mandibular plane angle (MPA), upper 6 to palatal plane, OP-SN, lower 6 to mandibular plane, inter premolar width of lower arch, inter canine and inter premolar width of upper arch [Table 2].

In females of Group I, the most influencing factors on BCLR were, GO-GN, MPA, posterior facial height (PFH), upper 1 to palatal plane, upper 6 to palatal plane OP-SN, lower 6 to mandibular plane, inter premolar width of upper arch and inter canine width lower arch [Table 2].

In Group II, PFH and inter premolar width of lower arch were the most significant factors [Table 3].

In males of Group II, GOGN, A-N perpendicular, ANS-N, PNS-N, MPA, anterior and PFH, upper 6 to palatal plane, OP-SN, lower 1 to mandibular plane, inter canine width of upper and lower arch were found to be most significant [Table 3].
Table 3: Multiple regression analysis for Group II

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In females of Group II, B-N perpendicular, ANS-N, PNS-N, MPA, anterior facial height (AFH), upper 1 and upper 6 to palatal plane, OP-SN, lower 1 to mandibular plane, inter canine width of upper and lower arch were found to be most significant [Table 3].


  Discussion Top


In orthodontic treatment, esthetics has traditionally been associated with profile improvement. Angle's classification of malocclusion and numerous other soft-tissue analyzes of the face have focused attention on profile without considering the frontal view. However, Arnett and Bergman, [3] Proffit [4] emphasized the importance of esthetics in the frontal view making it necessary for orthodontists to focus on the frontal plane during the evaluation of patients.

The buccal corridor area is one of the important evaluation points of transverse dimension in smile esthetics. [5],[6],[7] It is a space between the distal aspect of maxillary canine teeth and the corner of the mouth during smile. This area appears as a black or dark space and is also termed as "negative space." [8],[9]

The smile analysis has been treated as a separate entity from cephalometrics and cast analysis during diagnosis and treatment planning. Specific hard and soft-tissue factors have been studied, but without examination of the relationship between their etiology and smile esthetics. [1] The narrow maxillary arch and extractions were thought to be the causes of buccal corridor space. A study by Ackerman et al. [10] noted that the antero-posterior position of the maxilla and the rotation of the upper first molars could be the influencing factors on buccal corridor area.

Hence, this study was conducted, in order to evaluate the influence of maxillary and mandibular skeletal and dental structures in the antero-posterior, vertical and transverse dimensions on buccal corridor area in individuals with Class I and Class II Division 1 malocclusions.

In the present study, 80 individuals (40 males and 40 females), in the age group of 20-30 years were selected as per inclusion criteria. They were divided into two groups as per the value of ANB angle in to Group I having skeletal Class I and Group II having Class II malocclusion.

The buccal corridor space was found to be very highly significantly more in Class II individuals when compared with Class I group. This could be due to the fact that the maxillary arch is narrower in Class II Division 1 individuals than in Class I subjects. If the arch is narrower, the buccal corridor space tends to be wider in dimension. This was in accordance with previous studies by Ackerman et al., [10] Sarver and Ackerman, [11] Snyder, [12] McNamara. [13]

A to N perpendicular was found to be significant factor influencing the buccal corridor space in males of Class I and in Class II Division 1 group. B-N perpendicular was found to be significant in males of Class I and females of Class II Division 1 group. This is in accordance with several previous studies which suggested that the antero-posterior position of the maxilla influences the buccal corridor space. [6],[10],[11],[14] When the maxilla is retrusive, the wider portion of the dental arch is positioned more posteriorly relative to the anterior oral commissure. This creates the illusion of greater buccal corridor in the frontal dimension. In such cases, maxillary advancement results in a wider portion of the maxilla being placed into the buccal corridor, reducing the "negative space." Transverse dimension is said to be a function of both arch width and antero-posterior position of the maxillary and mandibular arches. [11]

ANS-PNS measurement gives the total effective length of the maxilla. The ANS-PNS distance with the measurements PNS-N and ANS-N gives a quantitative description of the maxilla in the cranial complex. In our study, we found that ANS-N is significant factor in both Class I and Class II Division 1 group.

Posterior maxillary height and MPA define the vertical dysplasia of posterior components of the face. MPA was found to be significant in both the groups. MPA was found to have moderate negative correlation with buccal corridor space. This is in accordance with the study conducted by Yang et al. [5]

In Class II Division 1 group, males had the AFH moderately negatively correlating, whereas PFH showed high negative correlation. This is in accordance with the study conducted by Yang et al. [5] These results show that long face individuals with high MPA and increased facial height tend to have less buccal corridor space. According to Sarver and Ackerman, [11] the facial types near two ends of the spectrum, dolichocephaly and brachycephaly, are greatly affected by a positional change in tooth mass in the buccal corridor.

The cant of the occlusal plane was measured by OP-SN angle. It was found to be significant in both Class I and Class II Division 1 individuals. This is in accordance with the opinion of Sarver and Ackerman. [11] They stated that, sagittal cant of the maxillary occlusal plane and arch form had a significant effect on smile arc. Increasing the cant of maxillary occlusal plane will increase the anterior tooth display and improves the consonance of the smile arc.

The vertical dental dysplasia is divided into anterior and posterior components. The anterior maxillary and mandibular dental heights is obtained by upper incisor to palatal plane and lower incisor to mandibular plane. The posterior maxillary and mandibular dental heights is obtained by upper 1 st molar to palatal plane and lower 1 st molar to mandibular plane. Upper 1 st molar to palatal plane was significant in both Class I and Class II Division 1 group. Lower incisor to MP showed a high negative correlation and lower molar to MP showed a moderate negative correlation in females of Class I group. The more anteriorly and downwardly positioned upper incisors and anteriorly and upwardly positioned lower incisors create less buccal corridor space. These incisor positions could be part of the dental compensation effect of the hyper divergent tendency in a skeletal vertical pattern.

In the present study, the inter canine and inter premolar widths of the upper and lower arches were found to be significantly influencing the amount of buccal corridor space in both Class I and Class II groups. The narrower the inter canine and inter premolar width was, the larger the buccal corridor space. This is in accordance with studies done by Snyder [12] Sarver and Ackerman [15] and Ghafari. [16]

The present study helps in establishing the correlation between certain factors and the amount of buccal corridor space in individuals having skeletal Class II pattern. This fact must be considered during the orthodontic evaluation, diagnosis and planning of treatment for individuals with different types of malocclusions.

Further studies with large sample size comprising of different skeletal and dental malocclusions in various racial groups may be required for establishing buccal corridor space in males and females of different age groups.


  Conclusion Top


The following conclusions can be drawn from the study:

Buccal corridor space is larger in individuals with Class II Division 1 malocclusion when compared with individuals with Class I malocclusions.

There exists a significant difference in buccal corridor space between males and females.

The length of mandible, inter premolar width, antero-posterior position of maxilla, anterior maxillary height were found to be significant in individuals with Class I malocclusion whereas posterior face height, inter premolar width of both upper and lower arch were found to be significant in individuals with Class II Division 1 malocclusion.

The results of this study aid in establishing a diagnosis that best identifies and quantifies the components of the smile and also to identify the positive and negative attributes of a patient's smile and to protect the positive attributes.

 
  References Top

1.McNamara L, McNamara JA Jr, Ackerman MB, Baccetti T. Hard- and soft-tissue contributions to the esthetics of the posed smile in growing patients seeking orthodontic treatment. Am J Orthod Dentofacial Orthop 2008;133:491-9.  Back to cited text no. 1
    
2.Sarver DM. The importance of incisor positioning in the esthetic smile: The smile arc. Am J Orthod Dentofacial Orthop 2001;120:98-111.  Back to cited text no. 2
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3.Arnett GW, Bergman RT. Facial keys to orthodontic diagnosis and treatment planning. Part I. Am J Orthod Dentofacial Orthop 1993;103:299-312.  Back to cited text no. 3
    
4.Proffit WR. The soft tissue paradigm in orthodontic diagnosis and treatment planning: A new view for a new century. J Esthet Dent 2000;12:46-9.  Back to cited text no. 4
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5.Yang IH, Nahm DS, Baek SH. Which hard and soft tissue factors relate with the amount of buccal corridor space during smiling? Angle Orthod 2008;78:5-11.  Back to cited text no. 5
    
6.Ackerman MB. Buccal smile corridors. Am J Orthod Dentofacial Orthop 2005;127:528-9.  Back to cited text no. 6
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7.Ritter DE, Gandini LG, Pinto Ados S, Locks A. Esthetic influence of negative space in the buccal corridor during smiling. Angle Orthod 2006;76:198-203.  Back to cited text no. 7
    
8.Hulsey CM. An esthetic evaluation of lip-teeth relationships present in the smile. Am J Orthod 1970;57:132-44.  Back to cited text no. 8
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9.Lombardi RE. The principles of visual perception and their clinical application to denture esthetics. J Prosthet Dent 1973;29:358-82.  Back to cited text no. 9
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10.Ackerman MB, Brensinger C, Landis JR. An evaluation of dynamic lip-tooth characteristics during speech and smile in adolescents. Angle Orthod 2004;74:43-50.  Back to cited text no. 10
    
11.Sarver DM, Ackerman MB. Dynamic smile visualization and quantification: Part 1. Evolution of the concept and dynamic records for smile capture. Am J Orthod Dentofacial Orthop 2003;124:4-12.  Back to cited text no. 11
    
12.Snyder RJ. Class II malocclusion correction: An American board of orthodontics case. Am J Orthod Dentofacial Orthop 1999;116:424-9.  Back to cited text no. 12
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13.McNamara JA. Maxillary transverse deficiency. Am J Orthod Dentofacial Orthop 2000;117:567-70.  Back to cited text no. 13
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14.Roden-Johnson D, Gallerano R, English J. The effects of buccal corridor spaces and arch form on smile esthetics. Am J Orthod Dentofacial Orthop 2005;127:343-50.  Back to cited text no. 14
    
15.Sarver DM, Ackerman MB. Dynamic smile visualization and quantification: Part 2. Smile analysis and treatment strategies. Am J Orthod Dentofacial Orthop 2003;124:116-27.  Back to cited text no. 15
    
16.Ghafari JG. Emerging paradigms in orthodontics - An essay. Am J Orthod Dentofacial Orthop 1997;111:573-80.  Back to cited text no. 16
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    Figures

  [Figure 1], [Figure 2], [Table 3]
 
 
    Tables

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