Assessment of dentofacial widths in adults with anterior open bite

R Dawal; MS Ravi; PS Murali; CR Soans; Shetty Kaushik

doi:10.4103/ijdr.IJDR_472_18

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ORIGINAL RESEARCH

Year : 2020 | Volume : 31 | Issue : 3 | Page : 382-388

Assessment of dentofacial widths in adults with anterior open bite

R Dawal, MS Ravi, PS Murali, CR Soans, Shetty Kaushik
Department of Orthodontics and Dentofacial Orthopedics, A.B. Shetty Memorial Institute of Dental Sciences, Nitte (Deemed to be) University, Mangalore, Karnataka, India

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Date of Submission	01-Jun-2018
Date of Decision	06-Jan-2019
Date of Acceptance	12-Jul-2019
Date of Web Publication	06-Aug-2020

Abstract

Context: Anterior open bite is a complex condition involving a combination of various dental and skeletal components in three dimensions. The data on the differences and changes in the transverse relation in individuals with anterior open bite are limited. Aims: To assess the dental arch widths in individuals with anterior open bite using study casts and facial widths using frontal cephalogram and to compare these widths with that of individuals without anterior open bite. Materials and Methods: Eighty adults [40 with and 40 without anterior open bite, mean (standard deviation) age = 20.68 years] were selected. The study group was divided into skeletal (n = 19) and dental (n = 21) open bite groups according to Jarabak's ratio. Posteroanterior cephalograms and study casts were analyzed. Results: The mean width of zygomatic arch (112.18 mm) and condylar region (100.55 mm) in the control group was significantly higher (P < 0.05). The mean gonial width in the skeletal open bite group (81.143 mm) was significantly (P < 0.05) lesser than the dental open bite group (84.842). The maxillary intercanine width for the skeletal open bite group (36.48 mm) was significantly (P < 0.01) higher than that of the dental open bite group (34.26 mm). Conclusion: A transverse deficiency was seen in in the zygomatic and condylar regions in adults with anterior open bite. Individuals with a skeletal open bite showed a narrow gonial and wider maxillary intercanine width compared with individuals with dental open bite.

Keywords: Anterior open bite, dentofacial width, frontal cephalogram, transverse discrepancy

How to cite this article:
Dawal R, Ravi M S, Murali P S, Soans C R, Kaushik S. Assessment of dentofacial widths in adults with anterior open bite. Indian J Dent Res 2020;31:382-8

How to cite this URL:
Dawal R, Ravi M S, Murali P S, Soans C R, Kaushik S. Assessment of dentofacial widths in adults with anterior open bite. Indian J Dent Res [serial online] 2020 [cited 2023 Mar 29];31:382-8. Available from: https://www.ijdr.in/text.asp?2020/31/3/382/291489

Introduction

Anterior open bite is defined as the absence of contact between the maxillary and mandibular incisor edges consequently presenting a negative overbite.^[1]

It is a complex condition involving a combination of various dental and skeletal components in three dimensions.^[2] The manifestation of various features of an open bite is contributed by the association of certain genetic and environmental factors.^[1]

Dentofacial and cranial characteristics of subjects with anterior open bite have been studied extensively in the sagittal and vertical planes with conventional analysis on lateral cephalogram.^[2],[3],[4]

The prevalence of anterior open bite ranges from 1.5% to 11% in different ethnic populations according to age and dentition^[5] (1.6% in Iranian adolescents,^[6] 8.7% in young Colombian adults,^[7] and 4.1% in young Yemeni adults^[8]).

Contraction of the zygomatic region of the maxilla and of the gonial and condylar regions of the mandible has been reported in children during mixed dentition phase. A narrow maxillary arch and a wide mandibular arch have been established on studying skulls and dental casts especially in children and adolescents. However, data on the differences and changes in the transverse relation of adult individuals with anterior open bite are limited.^[2]

Transverse incoordination of arches can lead to instability in occlusion and difficulty in mastication, affecting the dental and periodontal health. A common sequel of posterior crossbite is trauma from occlusion and poor masticatory function.^[9] While planning treatment, this is usually corrected by expansion or surgery or both. A negative overbite of upto 4 mm with no functional difficulties has been classified under moderate treatment need, while with functional difficulties under severe treatment need by index of orthognathic functional treatment need (IOFTN) for orthognathic surgery.^[10]

There is a paucity of literature on the transverse skeletal features of adults with anterior open bite and their effect on treatment options. A comprehensive analysis of dentofacial transverse characteristics of adult population with anterior open bite is required. With this background knowledge, this study is designed to analyze the dentofacial widths in adult individuals with anterior open bite.

The aims and objectives of this study are as follows:

To assess the dental arch widths in adult individuals with anterior open bite using study casts
To assess the facial widths in adult individuals with anterior open bite using frontal cephalogram
To compare the facial widths and dental arch widths in adult individuals with anterior open bite with that of adult individuals without anterior open bite.

Materials and Methods

The study included 80 adult individuals, classified into 40 individuals with anterior open bite and 40 individuals without anterior open bite. Ethical clearance was obtained from Institutional Ethical Committee (Certificate No. ABSM/EC88/2015).

Inclusion Criteria

Individuals willing to take part in the study
Individuals in the age group of 18–30 years
Presence of full complement of permanent dentition up to third molars
Presence of anterior open bite of 2 mm or more (study group)
Individuals with class I malocclusion without anterior open bite (control group).

Exclusion criteria

Previous orthodontic and/or orthognathic surgery treatment
Presence of craniofacial anomaly or syndromes
Presence of any missing teeth/large restorations
Previous history of trauma to the craniofacial region
Patients who do not give consent to be part of the study.

Written informed consent was obtained from all the selected 80 individuals (56 females and 24 males) who were divided into two groups based on the presence or absence of anterior open bite as follows:

Group I (control group) had individuals without anterior open bite (10 males, 30 females)

Group II (study group) had individuals with anterior open bite (14 males, 26 females)

Group II was further subgrouped based on the type of anterior open bite as measured on the lateral cephalogram (Jarabak's ratio was used to classify the type of anterior open bite).^[11]

Group II A had 19 individuals with skeletal anterior open bite (ratio <59%) range.

Group II B had 21 individuals with dental anterior open bite (ratio >59%) range.

The posteroanterior (PA) radiographs were made, keeping the Frankfort horizontal plane parallel to the floor under standardized conditions with the mid-facial plane kept in a vertical position. To minimize the magnification errors, the distance between the transporionic axis and film was maintained at a constant for every subject. Also, to keep the magnification of right and left sides of the face same, the central ray was passed through the center of the midsagittal plane. Planmeca PM 2002 cc Proline (Planmeca, Finland) was used.

The lateral and PA cephalogram tracings were accomplished using a 0.5-mm lead pencil on a 0.003 inch acetate paper. A single operator traced all the radiographs to avoid interoperator errors.

The upper and lower dental impressions were made using alginate impression material for all the selected individuals and study casts were prepared using dental stone for the analysis. A three-dimensional bow divider (Korkhaus) was used to measure the arch depth in maxillary casts and total arch length in maxillary and mandibular casts. For measuring the intercanine and intermolar widths, a divider and scale were used.

Facial width analysis

The six skeletal and two dental bilateral landmarks were identified and were connected (right to left) on the tracing sheets and using a 1-mm calibrated scale widths were measured and values were recorded as follows:

Skeletal landmarks and measurements [Figure 1]:

Cranial width (Eu-Eu)
Zygomatic width (Zyg-Zyg)
Intercondylar width (Cdl-Cdl)
Maxillary width (Mx-Mx)
Intergonial width (Go-Go)
Antegonial width (Ag-Ag)

Dental landmarks and measurements [Figure 1]:

Upper molar width (Um-Um), where Um is laterally the most prominent point on the upper first molar, on the buccal surface.
Lower molar (Lm-Lm), where Lm is laterally the most prominent point on the lower first molar, on the buccal surface.

Study cast analysis

The following measurements were made in upper and lower study casts [Figure 2] and [Figure 3]:

Figure 1: Facial width Analysis

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Figure 2: Dental Arch width Measurements

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Figure 3: Palatal Depth Measurements

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Intercanine width: it was measured as the distance between the cusp tips of the right and left canines on the maxillary and mandibular casts.
Intermolar width: it was measured as the distance between the central pit of the first permanent molars on the right and left sides on both the casts.
Arch length: measured as the distance between the mesial contact point between the central incisors anteriorly till an imaginary line joining the distal contact points of the first permanent molars in both the arches.
Arch depth: measured as a vertical distance from the occlusal plane at the intermolar distance at the point of greatest depth of the palate on the maxillary casts.

Statistical analysis

The unpaired t-test was used to calculate the mean values in control and study groups for age and all cephalometric and cast variables. Chi-square test was used to find the association between distribution of gender in control and study groups. A value of P < 0.05 was considered to be statistically significant. Microsoft Excel and SPSS Software version 22 were used for statistical analysis.

Results

Individuals in the age group of 18–30 years who were interested in seeking orthodontic treatment were included. The mean age in the control group was 21.18 years and in the study group was 20.18 years. Gender distribution was uneven with a higher count of females in both the groups, but the difference between the genders was insignificant (P = 0.217).

The following results were obtained from the study:

Cephalometric analysis

Intergroup analysis [Table 1] and [Graph 1]:

Table 1: Comparison of mean cephalometric values of transverse dentofacial widths in control and study groups

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The means of Zyg-Zyg and Cdl-Cdl in the control group were significantly (P < 0.05) higher compared with the study group. The mean values of Eu-Eu, Mx-Mx, Um-Um, and Lm-Lm were slightly higher in the control group compared with the study group but did not differ significantly (P > 0.05). The mean values of Go-Go and Ag-Ag in the control group were less compared with the study group but did not differ significantly (P > 0.05).

Intragroup comparison in study group [Table 2]:

Table 2: Comparison of mean cephalometric values of transverse dentofacial widths in skeletal and dental open bite groups

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The mean Go-Go width in the skeletal open bite group was significantly (P = 0.023) lesser than the dental open bite group. The means of Eu-Eu, Um-Um, and Ag-Ag were less for the skeletal open bite group compared with the dental open bite group, but did not differ significantly. Also, for the values of Zyg-Zyg, Cdl-Cdl, Mx-Mx, and Lm-Lm, the means of dental open bite group were less compared with the skeletal open bite group, but were not significant.

Dental cast analysis

Intergroup analysis

The maxillary and mandibular variables were analyzed separately. The intermolar width was the only variable following similar trend in both the arches. The mean values of maxilla IC, maxilla IM, and maxilla AL were slightly higher in the control group compared with the study group but they did not differ significantly (P > 0.05). The mean values of arch depth were slightly lower in the control group compared with the study group but they did not differ significantly (P = 0.434) [Table 3] and [Graph 2].

Table 3: Comparison of mean cast values in maxilla of various variables in control and study groups

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The mean values of mandible IC and mandible AL were slightly lower in the control group compared with the study group but they did not differ significantly (P > 0.05). The mean values of mandible IM were slightly higher in the control group compared with the study group but they did not differ significantly (P = 0.767) [Table 4] and [Graph 3].

Table 4: Comparison of mean cast values in mandible of various variables in control and study group

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Intragroup analysis in study group [Table 5]:

Table 5: Comparison of mean maxillary and mandibular cast values of variables in skeletal and dental open bite groups

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The mean maxillary intercanine value for the skeletal open bite group was found to be significantly (P = 0.008) higher than that of the dental open bite group. Other than the mean arch depth which was less in the skeletal open bite group than the dental open bite group, all the remaining dental cast measurements showed higher mean values in the skeletal open bite group.

Discussion

This study assessed and compared the facial and dental arch widths in adult individuals with and without the presence of anterior open bite. Ballanti et al. had compared the dentofacial transverse widths in mixed dentition, but the analysis was limited to cephalometrics and morphometrics.^[2] No data were found with similar analysis for an adult population.

In this study, Jarabak's ratio was used to divide the study group into dental and skeletal open bites.^[12] Various studies have found that subjects with anterior open bite have increased lower and total anterior facial heights with or without reduced posterior facial heights. This shows a general hyperdivergent facial pattern associated with anterior open bite with a skeletal etiology.^{[3],[9],[12],[13],[14],[15],[16],[17],[18],[19]}

The use of PA cephalograms for studying the transverse aspect of the craniofacial complex has been established for various types of malocclusions.^{[2],[15],[20],[21]} The most common application of PA view would be to detect and/or quantify asymmetry.^[22],[23] The difficulties include additional radiation exposure, errors associated with reproducing head posture, and superimposition of structures hence difficult in identifying them.^[24],[25]

The PA cephalometric measurements in this study show significant transverse contraction of the zygomatic and condylar regions in adults with anterior open bite. This is similar to the findings reported by Ballanti et al.,^[2] and thus zygomatic and condylar contractions of the face are present from mixed dentition to adulthood. Similar findings of reduced facial widths at skeletal level nonsignificantly have been found in Caucasian adult population at zygoma, maxillary, and mandibular levels.^[15]

The maxillary and mandibular first molar regions showed mild contraction but were not statistically significant. This is also similar to previous studies which have found a significant tranverse contraction of maxilla at skeletal and dental levels during mixed dentition^[2] and in adults.^[15]

At the gonial and antegonial levels, there was a mild expansion seen in the anterior open bite group compared with the control group. This contradicts the findings of Ballanti et al.^[2] who found a significant transverse deficiency at the gonial region. Thus, a transverse deficiency of the skeletal mandibular region may not be a norm in adult anterior open bite individuals.

On comparing the skeletal and dental open bite groups with each other, the skeletal open bite group exhibited a significant transverse contraction of the gonial region compared with the dental open bite group. No other variable differed significantly in both groups with a mild deficiency seen at euryon, upper molar, and antegonial regions for skeletal open bite group and at zygomatic, condylar, maxillary, and lower molar regions for dental open bite group.

The significant contraction of gonial region in skeletal open bites could be attributed to the prevalence of long face syndrome or increased anterior facial heights with narrow face in skeletal anterior open bite condition.^{[5],[12],[16],[17],[18],[26]}

Dental study casts are a highly reliable and commonly used diagnostic tool in orthodontics.^[27] It is one of the best ways to study arch dimensions and the changes that occur in them. On analysis of dental variables on study casts, no significant difference was found in both the arches between the anterior open bite and control groups. In the maxillary arch, the intercanine, intermolar, and arch length were deficient in anterior open bite subjects. While the palatal arch depth showed a higher and deeper palatal vault compared with normal adults.

The mandibular intermolar width showed a mild expansion, but the intercanine width and arch length showed a mild contraction in anterior open bite cases. None of the differences was significant.

These findings correlate to previous studies. Fink^[13] found arch widths to be narrow in patients with anterior open bite compared with ones without the condition. Others^[27],[28] have found narrow maxillary intermolar widths with expanded mandibular intermolar with either normal or increased palatal depth. The cause for this is mostly attributed to the habits of digit sucking and/or tongue thrusting. Warren and Bishara^[29] on studying digit sucking and pacifier habits in children found an increase in mandibular and decrease in maxillary widths, which were present long after cessation of these habits.

On comparing the study cast variables of the dental and skeletal open bite groups, the maxillary intercanine width for skeletal open bite group was significantly higher than that of the dental open bite group. Other than the mean arch depth which was lesser in the skeletal open bite group than the dental open bite group, all the remaining dental cast measurements showed higher mean values in the skeletal open bite group.

This study reinforces the existing knowledge that the variation in dentofacial characteristics does not occur in isolation. Any kind of malocclusion in any plane of space needs to be assessed in all dimensions. The individuals having vertical mal-relationships in the form of anterior open bite exhibited significant deviation in transverse dimensions too. This aspect needs to be considered during diagnosis and treatment planning and should be included in the comprehensive management protocol in orthodontics and/or orthognathic surgeries.

Conclusion

Significant differences were observed in dentofacial characteristics in transverse plane in individuals with anterior open bite as follows:

A transverse deficiency in the zygomatic and condylar regions.
A narrow gonial and wider maxillary intercanine width were found in skeletal open bite individuals compared with individuals with dental open bite.

This study emphasizes the importance of knowledge of transverse facial and dental dimension in adults with anterior open bite. These differences need to be considered during the treatment planning and management of any type of malocclusion in orthodontics.

Financial support and sponsorship

Nil.

Conflicts of interest

There are no conflicts of interest.

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Correspondence Address:
Dr. M S Ravi
Department of Orthodontics and Dentofacial Orthopedics, A.B. Shetty Memorial Institute of Dental Sciences, Nitte (Deemed to be) University, Mangalore, Karnataka - 575 018
India