|Year : 2022 | Volume
| Issue : 2 | Page : 146-153
Effect of intermaxillary tooth-size discrepancy on accuracy of prediction equations for mixed dentition space analysis for Davangere population
Siddhi Samir Tejani, Poornima Parameswarappa, K Mallikarjuna, NB Nagaveni, KB Roopa, Neena I Eregowda
Department of Pediatric and Preventive Dentistry, College of Dental Sciences, Davangere, Karnataka, India
|Date of Submission||02-Mar-2022|
|Date of Decision||07-Jun-2022|
|Date of Acceptance||20-Jun-2022|
|Date of Web Publication||15-Jul-2022|
Dr. Siddhi Samir Tejani
Postgraduate Student, Department of Pediatric and Preventive Dentistry, College of Dental Sciences, Davangere, Karnataka
Source of Support: None, Conflict of Interest: None
| Abstract|| |
Context: In the mixed dentition period, malocclusion is in dormant stage, any interception should be preceded by a mixed dentition space analysis. Aims: To derive new regression equation in sample subjects (indigenous group) with no intermaxillary tooth size discrepancy (Bolton's ratio) residing in Davangere and to evaluate its accuracy. To assess the difference of tooth dimensions between males and females and difference between right and left of dental arches. Setting and Design: Descriptive study. Subjects and Methods: One hundred and fifty children (11–15 years) were included and dental casts were made. A digital Vernier caliper was used for the measurement of teeth. Bolton's ratio was calculated. Group A: Casts without Bolton's discrepancy and Group B: Casts with Bolton's discrepancy. Statistical Analysis Used: The data were analyzed with the SPSS software version 22.0. New regression equations were derived using correlation and regression analysis. Results: No statistically significant difference was recorded between the actual and predicted mesiodistal widths (MDWs) of permanent canine and premolars in maxilla and mandible, with/without Bolton's discrepancy. Males had statistically significant higher mean in maxillary and mandibular canine dimensions than female and no statistically significant difference between right and left side of dental arches was found. Conclusion: New regression equation was formulated for Davangere population, in which actual and predicted widths of permanent canines and premolars were found to be almost similar when established from sample with/without Bolton's discrepancy. In MDWs, the canine showed significant sexual dimorphism and no clinically significant variations were seen in the right and left sides of both the arches.
Keywords: Analysis, mixed dentition, regression, sexual dimorphism
|How to cite this article:|
Tejani SS, Parameswarappa P, Mallikarjuna K, Nagaveni N B, Roopa K B, Eregowda NI. Effect of intermaxillary tooth-size discrepancy on accuracy of prediction equations for mixed dentition space analysis for Davangere population. J Indian Soc Pedod Prev Dent 2022;40:146-53
|How to cite this URL:|
Tejani SS, Parameswarappa P, Mallikarjuna K, Nagaveni N B, Roopa K B, Eregowda NI. Effect of intermaxillary tooth-size discrepancy on accuracy of prediction equations for mixed dentition space analysis for Davangere population. J Indian Soc Pedod Prev Dent [serial online] 2022 [cited 2022 Aug 17];40:146-53. Available from: http://www.jisppd.com/text.asp?2022/40/2/146/351052
| Introduction|| |
Mixed dentition analysis (MDA) is used for the diagnosis and treatment for malocclusions. There are specific dimensional relationships between the maxillary and mandibular teeth to ensure proper interdigitation, overbite, and overjet. It is important to determine the amount and location of a tooth-size discrepancy (TSD) (Bolton's discrepancy) before starting treatment. In MDA, the prediction equations are based on erupted permanent teeth especially the Moyers and Tanaka and Johnston equations. However, their accuracy is questionable because none considered the TSD.
Hence, our study was done to derive the new regression equation in sample subjects with no Bolton's discrepancy residing in Davangere and to evaluate its accuracy. To assess the difference of tooth dimensions between males and females and between right and left sides of both arches.
Sample size estimation
Using the following formula:
n = Z2pq/e2
n = (1.96)2 (0.4) (0.6)/(0.08)2
n = 144 − 150
z = value of statistics at 95% confidence level
p = Prevalence of requirement of mixed dentition in age 11–15 years = 0.4
q = Nonprevalence = 0.6
e = instrumental error = 0.08
| Subjects and Methods|| |
One hundred and fifty children (11–15 years) were randomly selected from the outpatient clinic of the Department of Pediatric and Preventive Dentistry at College Of Dental Sciences, Davangere, Karnataka, India. Ethical clearance to conduct the study was obtained (No. CODS/3225/2019-2020).
The criteria for the inclusion in the study were: Subjects with fully erupted complete permanent dentition with no congenital anomalies of teeth, no previous orthodontic treatment, no clinically visible dental caries, restorations; Class I canine and molar relationship and indigenous subjects residing in and around Davangere. Study subjects with severe crowding/spacing (>2–4 mm) were excluded from the study. Consent was obtained.
Impressions were made using alginate material and poured in dental stone and then the cast bases were made with dental plaster. A digital Vernier caliper calibrated to an accuracy of ±0.01 mm (Aerospace) was used for obtaining the measurements.
The standardized technique proposed by Jensen et al. 1957 was followed for all the measurements. The measurements were made by the primary investigator. The reliability of measurements was assessed by double-determination method on 20 randomly selected study casts and the error was calculated with the help of Dahlberg's formula 1940. Only eight to ten pairs of study casts were measured in a day to avoid errors due to eye fatigue. The measurement consistency was determined by intraclass correlation coefficient (ICC).
Bolton's ratios for each subject, both anterior Bolton's ratio (ratio of mandibular 6 teeth and maxillary 6 teeth × 100) and over all Bolton's ratio (ratio of mandibular 12 teeth and maxillary 12 teeth × 100) were calculated thereafter. A threshold of ±2 standard deviation (SD) was considered as the criterion for selecting subjects under group A. Therefore, Group A included subject with no intermaxillary TSD, while Group B included subjects with intermaxillary TSD.
All the permanent teeth erupted during the mixed dentition period can be utilized for prediction of mesiodistal widths (MDW) of permanent canines and premolars (PCPM). The permanent maxillary lateral incisors were excluded due to the high incidence of developmental variations, leaving only five pairs of teeth available that is maxillary central incisors, maxillary first molars, mandibular central incisors, mandibular lateral incisors and mandibular first molars. Permutation-combination of five pairs of teeth, left and right sides were calculated and 26 combinations were obtained.
Simple linear regressions were computed between MDWs of all the combinations of teeth in both the arches for both Group A and B.
The regression equations generated were in the standard form,
y = a + bx
where a, b are constants;
y - is the dependent variable (averaged MDWs of PCPMs of both sides in maxilla/mandible)
x - is the predictor or independent variable (sum of both sides MDWs of different teeth combinations in maxilla/mandible).
Correlation coefficients (R) and coefficients of determination (R2) were determined for all the possible teeth combinations in each group in each arch. The best predictors for the value of x were those with highest R and R2.
The actual and predicted values of MDWs of PCPMs were compared in both the groups, for both the arches. The predicted equation was compared with a different group of children residing in the same city.
The data were tabulated and statistically analyzed with IBM SPSS Statistics for window, version 20 (IBM Crop., Armonk, N.Y., USA). Correlation and regression analysis was performed. Student's unpaired t-test was used to compare the MDWs between males and females. Paired samples t-test was used to compare between left and right-side MDWs in both the arches. Paired samples t-test was used to compare the actual and predicted values of MDWs of PCPMs in both groups, for both the arches.
| Results|| |
The measurement of error for MDWs of all the teeth, as determined by double determination method, was found to be 0.032 mm which was well within the clinically acceptable limit. The ICC was found to be 0.781 (at 95% confidence interval) indicating good measurement consistency. The statistical test carried out was correlation and regression analysis, unpaired t-test and paired t-test. For total subjects (n = 150), the mean of Anterior Bolton's ratio is 78.10 (±1.06 SD) and Overall Bolton's ratio is 90.59 (±0.67 SD). The participants were divided into Group A (without Bolton's discrepancy) and Group B (with Bolton's discrepancy).
Correlation coefficients (R) and coefficients of determination (R2) between all the teeth combinations and PCPMs for total subjects and both the groups are presented in [Table 1], [Table 2], [Table 3], respectively. The combinations showing highest coefficients for total subjects were C2 (R = 0.886) for maxilla and C23 (R = 0.859) for mandible represented in [Table 1].
|Table 1: Correlation coefficients for different teeth combinations computed using simple linear regression for total sample|
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|Table 2: Correlation coefficients for different teeth combinations computed using simple linear regression in Group A|
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|Table 3: Correlation coefficients for different teeth combinations computed using simple linear regression in Group B|
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In Group A (without Bolton's discrepancy), C2 (R = 0.905) and C12 (R = 0.891) showed highest coefficients for maxilla and mandible, respectively, represented in [Table 2] and in Group B (with Bolton's discrepancy), C1 (R = 0.941) and C22 (R = 0.931) showed highest coefficients for maxilla and mandible, respectively, represented in [Table 3].
The best derived regression equations were:
Total subjects: Maxilla: Y = −2.575 + 0.68 (C2); Mandible: Y = −4.841 + 1.096 (C23)
Group A: Maxilla: Y = −5.529 + 0.689 (C2); Mandible: Y = −10.418 + 0.877 (C12)
Group B: Maxilla: Y = 6.308 + 0.452 (C1); Mandible: Y = 2.602 + 1.205 (C22)
The validity of equations so derived was tested in an independent set of subjects. No statistically significant difference between actual and predicted values was noticed for PCPMs for both maxillary and mandibular arches represented in [Table 4].
|Table 4: Comparison of actual and predicted values of mesiodistal widths of permanent canine and premolars using paired samples t-test|
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Sexual dimorphism [Table 5] was seen in the measurements of some teeth such as permanent maxillary and mandibular canines (P < 0.05). Descriptive statistics for tooth MDWs [Table 6] showed no statistically significant differences between measurements from the left and right side.
|Table 5: Comparison of mean mesiodistal widths between males and females using unpaired t-test|
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|Table 6: Comparison of mesiodistal width tooth measurements from right and left sides of maxillary and mandibular dental arches using paired samples t-test|
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| Discussion|| |
Mixed dentition space analysis is a method of determining the MDWs of unerupted PCPMs. The prediction can be done by two ways radiographic or nonradiographic. Accordingly, the clinician can opt for serial extraction, space maintenance, space regaining, or just regular follow-up of the patient.
The combination of radiographic and statistical methods (Hixon and Oldfather 1958; Staley and Hoag 1978; Staley and Kreber 1980) involves additional radiation exposure, image distortion problems, and use of expensive equipment. Therefore, nonradiographical methods for the prediction of total MDWS of PCPMs have been preferred in the past by Moyers' (white American), Tanaka Johnston's analysis (Northwest European), and Melgaco's equation (Brazilian population) are frequently practiced., Studies on various other populations proved that these radiographic and nonradiographic methods either overestimate/underestimate the MDWs of PCPMs.,
The sum of MDWs of permanent mandibular incisors has been suggested as the best predictor by many authors Ballard and Wylie 1947, Moyers 1958; Carey 1949; Huckaba 1964; Tanaka and Johnston 1974. The sum of mandibular incisors and mandibular first permanent molars has been used as the independent predictor variable in various studies, as established by Melgaço et al. 2007, Mittal et al. 2016, Mittar et al. 2012, Shah et al. 2013.
In the United States, Ballard and Wylie and Moyers used the sum of the MDW of mandibular incisors as independent variables, in contrast, the European school selected the sum of the maxillary incisors as the best predictors. But both schools disregarded the first permanent molars, and the reason could be that caries frequently affects their mesiodistal crown diameters.
Nourallah et al. 2002, Legović et al. 2003, Bernabé and Flores-Mir 2005, Paredes et al. 2006, Memon and Fida 2012, Khanna et al. 2014, Vanjari et al. 2015, Giri et al. 2018 have found different combinations of teeth as the best predictors. Therefore, in the present study, simple linear regression equations were calculated using the combination of teeth showing highest correlation coefficients present in mixed dentition phase.
A TSD has been described as a relative excess of tooth structure in one arch in relation to the other arch. It can also be defined as a disproportion among the sizes of individual teeth. There are specific dimensional relationships between the maxillary and mandibular teeth to ensure proper interdigitation, overbite, and overjet. Hence, before beginning treatment, it is critical to evaluate the extent and location of a TSD. According to Bolton the ratio ±1 SD from his reported mean values indicated the need for diagnostic consideration., According to Sharma et al. 2011 a threshold of ± 2 SD is recommended for the study conducted in Indian population. It was in accordance with Crosby and Alexander 1989; Johe et al. 2010. Hence in the present study threshold of ±2 SD was used as a criterion to select the dental casts in Group A and Group B. The mean of Anterior Bolton's ratio was found to be 78.10 and the mean of overall Bolton's ratio 90.59.
Many researchers have used different data in their patient groups, but very few studies have considered the intermaxillary TSD. If there is TSD between the maxillary and the mandibular dentitions, regression equations built with these summations are questionable. We believe that high R and R2 values explain the good proportions of the arches.
In Group A [Table 2], the PCPMs were strongly correlated to combinations C2 and C12. In group B with increased percentage of subjects with intermaxillary discrepancy beyond ± 2 SD of the mean values [Table 3], the PCPMs were strongly correlated to combinations C1 and C22. The values of R found in the present study was higher when compared to other studies. Hence, it was noticed that accuracy of prediction equations improved by inclusion of as many teeth as possible in the regression equations.
In the present study all the combinations of teeth present in the mixed dentition phase showed good correlation coefficients and can be used in regression equation. On contrary, Uysal et al. 2009 found permanent mandibular incisors as the best predictors in the group without Bolton's discrepancy for Turkish population. Khanna et al. 2014 found mandibular incisors and first permanent molar to be the best predictors in the group without Bolton's discrepancy for both the dental arches. In the group with Bolton's discrepancy the best predictors were combination of four mandibular incisors and maxillary central incisor with maxillary first permanent molar, in the maxillary arch for the North Indian population. The study's contradictory findings can be attributed to the fact that the populations investigated are different: North Indians are of Aryan origin, whereas South Indians are with Dravidian characteristics.
In the present study, there was no significant difference noticed between the actual and the predicted values of PCPMS when derived from group with and without Bolton's discrepancy. On contrary, Uysal et al. 2009 and Khanna et al. 2014 found that the correlation was stronger when established from a sample with no intermaxillary (Bolton) discrepancy.
The MDWs difference between both the sex, have been studied by various investigators. In the present study the males had larger mesiodistal teeth dimensions of teeth than females, and the canines in both jaws displayed a statistically significant difference [Table 5]. This was in agreement with the results of Khanna et al. 2014, Hashim and Al-Ghamdi 2005, Bishara et al. 1989.
In the present study, statistics for tooth MDWs showed no statistically significant differences between left and right side [Table 6], supported by Khanna et al. 2014, Hattab et al. 1996 but contradicted by Boaz and Gupta 2009 who found a difference between left and right tooth measurements.
The strength of the study is population-specific regression equations were formulated. Though few of the studies have formulated different combinations of teeth for the value of X (independent variable), for both the arch but none of the studies have found the combinations used in the current study to show high correlations. Hence the value of X determined is considered to be unique in the current study and had never been reported before. In this investigation, there was no statistically significant difference between the actual and predicted MDWs of PCPMs in both Groups A and B.
The current study's limitations are that the sample size was less and samples from different ethnic groups within the same community were not considered. Scope for the future research can be focused on regression equations based on specific population with a bigger sample to support the findings and also consider ethnic variation.
| Conclusion|| |
- New regression equation was formulated for Davangere population (Indigenous group)
- The correlation between actual and predicted widths of PCPMS was found to be almost similar when established from the subjects with no Bolton discrepancy and with Bolton's discrepancy
- When compared between males and females the MDWS of maxillary and mandibular canines of males were greater than that of females
- No significant variation was reported between the MDWs of teeth for right and left sides of maxillary and mandibular arches.
Financial support and sponsorship
Conflicts of interest
There are no conflicts of interest.
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[Table 1], [Table 2], [Table 3], [Table 4], [Table 5], [Table 6]