Anterior Bolton Ratios Research Articles

Evaluation and comparison of tooth size discrepancies among different malocclusion groups

Introduction: The compliance of proportions between the mesiodistal dimensions of the upper and the lower teeth is necessary for good intercuspidation. Given that a significant discrepancy in tooth size can prevent ideal occlusion at the end of orthodontic treatment, the absence of tooth size discrepancy is a significant factor for the realization of the ideal occlusion.The aim: Aim of this study was to determine whether there is a difference in the incidence of tooth size discrepancies among different skeletal malocclusion groups in the orthodontic patients.Material and methods: The sample comprised 300 pretreatment study casts (118 males and 182 females) with fully erupted andcomplete permanent dentition except third molars, which were selected randomly from records of orthodontic patients. All subjects were divided in three groups, according to the Angle classification of malocclusion. The measurements were made on study models with digital calipers accurately to 0.01 mm.The Class was defined by using the Steiner analysis on lateral cephalograms.The subjects were divided into three groups depending on the value of the ANB angle. For every subject, the value of the angles SNA, SNB and ANB was measured.The reliability of measurements was examined by the Pearson’s correlation coefficient. To determine whether there were gender differences an independent sample t-test was performed.Results: There is no statistically significant differences in Bolton’s discrepancy by different gender, or at different classes. The averagevalue of the anterior Bolton ratio was 78.16 and of the overall were 90.87. Values of the anterior and overall Bolton ratios are highestin patients with Class III. The highest average value of anterior discrepancy was in male subjects with III Class (-0.72), while the highest average value of overall discrepancy was in male subjects with II Class (0.65).Conclusion: The results of the study show that there are no statistically significant differences in Bolton’s discrepancy by different gender, or at different classes.

Bolton tooth size ratio among qatari population sample: An odontometric study.

Objectives:To establish the overall and anterior Bolton ratio among a sample of Qatari population and to investigate whether there is a difference between males and females, as well as to compare the result obtained by Bolton.Materials and Methods:The current study consisted of 100 orthodontic study participants (50 males and 50 females) with different malocclusions and age ranging between 15 and 20 years. An electronic digital caliper was used to measure the mesiodistal tooth width of all maxillary and mandibular permanent teeth except second and third molars. The Student's t-test was used to compare tooth-size ratios between males and females and between the results of the present study and Bolton's result.Results:The anterior and overall ratio in Qatari individuals were 78.6 ± 3.4 and 91.8 ± 3.1, respectively. The tooth size ratios were slightly greater in males than that in females, however, the differences were not statistically significant (P > 0.05). There were no significant differences in the overall ratio between Qatari individuals and Bolton's results (P > 0.05), whereas statistical significant differences were observed in anterior ratio (P = 0.007).Conclusions:Within the limitation of the limitations of the present study, definite conclusion was difficult to establish. Thus, a further study with a large sample in each malocclusion group is required.

The applicability of Bolton's tooth size ratios for population-specific malocclusion

Aims: This study aims to evaluate the Bolton ratio in Beed population in Maharashtra with different malocclusion. Materials and Methods: Fifty study casts were taken from the patients undergoing orthodontic treatment, and individuals were divided into three groups: Group I (Angle's Class I, n = 25), Group II (Angle's Class II, n = 25), and Group III (mean of Group I and Group II). Statistical Analysis Used: ANOVA and Tukey's test. Results: A mean total Bolton ratio of 93.05 ± 5.87 and a mean anterior Bolton ratio of 81.08 ± 5.93 were found for the sample; significantly, higher mean anterior tooth ratios were found for Group I (Angle's Class I) patients (P Conclusions: Mean anterior tooth size discrepancy for Angle Class I individuals was significantly greater compared to Bolton's mean anterior ratio.

Comparison of Bolton’s Ratios in a Sample of Iraqi and Egyptian Populations

Background: The objective of this study was to investigate the possibility of standardizing the Bolton ratio analysis as a diagnostic measure for both Iraqi and Egyptian orthodontic populations within three Angle' classification groups. Materials and methods: Two hundred forty pretreatment study casts (one hundred twenty of each population) were included in this study and divided into three Angle' classification groups. The mesiodistal crown diameters of all teeth were measured for computing the anterior and total Bolton ratios. Analysis of variance was performed to compare the mean ratios of Bolton analysis as a function of the Angle classification.HSD test was used to specify the classes of malocclusion that have significant differences. Results: No statistically significant differences were determined in the mean values of the anterior ratio among the angle classification groups in both Iraqi and Egyptian populations. No statistically significant differences were determined in the mean values of the overall ratio among the angle classification groups in Iraqi population. While there were statistically significant differences in the mean values of overall ratio among the angle classification groups in Egyptian population. This difference is specified with in class II malocclusion of Egyptian population. Conclusion: Anterior Bolton ratio can be standardized for both Iraqi and Egyptian orthodontic populations. While the overall ratio can be standardized only in class I and III malocclusions of both populations.

Tooth-Size Discrepancies in Patients Requiring Mandibular Advancement Surgery

Numerous studies have shown that tooth size is an important key to ideal occlusion. Bolton (Angle Orthod 28:13, 1958; 48:504, 1962) described a constant ratio between the widths of the upper and lower teeth that must be present to achieve an optimal occlusion. The purpose of this study was to determine the incidence of Bolton discrepancies in patients with Class II malocclusion scheduled for mandibular advancement surgery. This study included 126 patients (40 male, 86 female) with Class II malocclusion who had at least a mandibular advancement as part of their surgical treatment. The mesiodistal widths of the 6 anterior maxillary and mandibular teeth were measured on preoperative models using a caliper. The measurements were used to compute the anterior Bolton ratio. Seventy-three of 126 patients (57.9%) were found to have an anterior Bolton ratio greater than the Bolton norm, indicating too much lower tooth mass compared with the upper mass or too little upper tooth mass compared with the lower mass. Tooth-size discrepancies are common in patients requiring mandibular advancement surgery. This can make it difficult to advance the mandible into a solid Class I relation at the time of surgery. Bolton discrepancies should be considered when planning treatment with presurgical orthodontics. In addition, if necessary, the width of the lower incisors should be decreased or a space distal to the maxillary lateral incisors should be created to allow the establishment of a solid Class I canine occlusion at the time of surgery.

Anterior Tooth Discrepancy in Different Bangladeshi Malocclusion Group at BSMMU

Anterior tooth discrepancy, an important clinical orthodontic tool to manage malocclusions, may vary on different race, ethnicity and gender. Therefore this study on anterior tooth discrepancy of Bangladeshi malocclusion groups were formulated to calculate and set up a standard norm, and to evaluate the gender discrepancy. A cross sectional type study was done among 207 pretreated dental casts (60 male, 147 female) of malocclusion patient at the Department of Orthodontics, Faculty of Dentistry, BSMMU, Bangladesh. Bolton anterior ratio were measured and compared statistically (in the Angle’s group of malocclusion). No significant anterior discrepancy was observed between Bangladeshi male and female groups. A similar value for anterior discrepancy was observed in neighboring countries.J Bangladesh Coll Phys Surg 2015; 33(4): 191-194

Intermaxillary tooth size discrepancy in a Pakistani population: A stereomicroscope versus digital caliper.

Objective:Comprehensive diagnosis and treatment planning are essential in a successful orthodontic practice. The purpose of this study is to determine and compare intermaxillary tooth size discrepancy (IMTSD) using traditional digital caliper (DC) measurement on plaster dental models and stereomicroscopic digital dental models (SM).Materials and Methods:The samples were randomly selected from different states of Pakistan. Total 7168 variables were measured on plaster dental casts (128) and SM digital dental models (128) according to the selection criteria. For IMTSD, the 6 variable measured as for anterior tooth size (maxilla, mandibular), overall tooth size (maxilla, mandibular), Bolton's anterior ratios (BAR), and Bolton's overall ratios (BOR). The independent t-test and ANOVA were used for statistical analyses.Results:Significant sexual disparities in the sum of anterior tooth size and overall tooth size via DC and SM methods. No significant sexual disparities for BAR and BOR. No statistically significant differences were found in BAR and BOR between DC and SM. No significant differences were found on IMTSD ratio among different arch length and arch perimeters groups.Conclusions:Norms were developed based on DC and SM for IMTSD. Sexual disparities were observed in the sum of teeth size. However, no significant differences in BAR and BOR for IMTSD between the two methods.

Accuracy of Bolton analysis measured in laser scanned digital models compared with plaster models (gold standard) and cone-beam computer tomography images.

ObjectiveThe aim of this study was to compare the accuracy of Bolton analysis obtained from digital models scanned with the Ortho Insight three-dimensional (3D) laser scanner system to those obtained from cone-beam computed tomography (CBCT) images and traditional plaster models.MethodsCBCT scans and plaster models were obtained from 50 patients. Plaster models were scanned using the Ortho Insight 3D laser scanner; Bolton ratios were calculated with its software. CBCT scans were imported and analyzed using AVIZO software. Plaster models were measured with a digital caliper. Data were analyzed with descriptive statistics and the intraclass correlation coefficient (ICC).ResultsAnterior and overall Bolton ratios obtained by the three different modalities exhibited excellent agreement (> 0.970). The mean differences between the scanned digital models and physical models and between the CBCT images and scanned digital models for overall Bolton ratios were 0.41 ± 0.305% and 0.45 ± 0.456%, respectively; for anterior Bolton ratios, 0.59 ± 0.520% and 1.01 ± 0.780%, respectively. ICC results showed that intraexaminer error reliability was generally excellent (> 0.858 for all three diagnostic modalities), with < 1.45% discrepancy in the Bolton analysis.ConclusionsLaser scanned digital models are highly accurate compared to physical models and CBCT scans for assessing the spatial relationships of dental arches for orthodontic diagnosis.

Bolton ratio in a North Indian population with different malocclusions.

Objective:The objective was to evaluate the Bolton ratio in a North Indian population in Lucknow with different malocclusion.Materials and Methods:Totally, 110 study cast [Age: Female (14.2 ± 1.5 years, Male (13.9 ± 2.3 years)] were taken from the patients undergoing orthodontic treatment and Subjects were divided into three groups: Group I (Angle's Class I, n = 40), Group II (Angle's Class II, n = 50) and Group III (Angle's Class III, n = 20) according Angle's classification of malocclusion. The mesiodistal widths of all maxillary and mandibular teeth from right first molar to left first molar were measured with a digital caliper to calculate the Bolton ratio. The readings were then used to compute the anterior and total Bolton ratios. ANOVA and Tukey's test were used for the statistical analysis.Results:A mean total Bolton ratio of 91.36 ± 2.13 and a mean anterior Bolton ratio of 78.14 ± 4.09 were found for the sample, Significantly higher mean anterior tooth ratios were found for Group II (Angle's Class II) patients (P < 0.01). All other ratios were within close range of Bolton's norms.Conclusions:Angle's Class II patients showed a tendency toward wider mesiodistal widths of teeth in the mandibular anterior region or smaller tooth sizes in the maxillary anterior region.

Bolton tooth size ratio and its relation with arch widths, arch length and arch perimeter: A cone beam computed tomography (CBCT) study

Objective. The prime aim of the study was to measure and compare the 3D CBCT Bolton tooth size ratio in relation to the upper and lower arch widths, arch length and arch perimeter. Materials and methods. The data source was CBCT high volumetric data from the archives. Tooth size, arch widths, arch length and arch perimeter were measured in maxilla and mandibular arches. The independent t-test and ANOVA were used for statistical analyses. Results. The female Bolton anterior ratio (BAR) (78.373) and Bolton overall ratio (BOR) (93.231) show a greater tooth size ratio in comparison to male BAR (77.162) and BOR (93.124), respectively. However, no significant difference was found in the sexual comparison of all the measurements. Tooth size ratio in arch width groups also showed no significant difference. Significant discrepancies in the arch length (p < 0.05) groups and overall ratio and in the arch perimeter groups (p < 0.05 and p < 0.01) and anterior ratio were revealed. Conclusions. Tooth size ratios during orthodontic treatment for different arch length and arch perimeter groups need to be evaluated carefully.

Comparison of Effects of Tooth Extraction and Air-rotor Stripping Therapy on Tooth-size Discrepancy in Class I Borderline Patients

ABSTRACT Aim The objectives of this study were to investigate the effects of tooth extraction and air-rotor stripping therapy on tooth-size discrepancy, and to compare the changes between two groups. Materials and methods The sample comprised the preand post-treatment dental models of 20 postadolescent class I borderline patients. First group was composed of dental models of 10 patients (mean age of 17.1 ± 2.5 years) treated with four first premolars extraction. Second group included dental models of 10 patients (mean age of 18.8 ± 2.7 years) treated with air-rotor stripping. Treatment effects on Bolton overall and anterior ratios/values were analyzed by paired sample t-test and independent sample t-test was used for intergroup comparisons. Results The change in Bolton overall ratio was found statistically significant for the extraction and insignificant for the air-rotor stripping group. A statistically significant decrease was observed in Bolton anterior ratio for the air-rotor stripping group. Neither four premolars extraction nor air-rotor stripping therapy created statistically significant changes in Bolton overall/anterior values. The changes in Bolton overall ratio/value did not show a statistically significant difference between the groups. Conclusion This study showed that tooth extraction or air-rotor stripping therapy did not have an unfavorable effect on toothsize discrepancy in class I borderline patients. How to cite this article Kaya D, Taner T, Germeç-Çakan D. Comparison of Effects of Tooth Extraction and Air-rotor Stripping Therapy on Tooth-size Discrepancy in Class I Borderline Patients. Int J Experiment Dent Sci 2014;3(1):8-13.

Gambaran indeks Bolton pada pasien yang dirawat dengan piranti ortodontik lepasan di Rumah Sakit Gigi Mulut Universitas Hasanuddin Overview of Bolton index on patients treated with removable orthodontic appliance in Dental Hospital of Hasanuddin University

Orthodontic treatment requires complete planning. Various analyzes is needed to determine the treatment plan; one ofthem is analysis of tooth size differences or Bolton analysis. Orthodontic treatments in Dental Hospital of HasanuddinUniversity do not apply Bolton analysis, so it is necessary to know the overview of Bolton index of the cases that have beentreated. This observational descriptive study was conducted in Department of Orthodontics, Dental Hospital ofHasanuddin University in March-May 2012. The samples were patients who completed treatment in 2010-2011. A total of156 samples consisting of 117 females and 39 males. The result showed that the non-intervention group Ideal AnteriorBolton Ratios and group Overall Bolton Ratio &lt;93.21% have a tendency orthodontic treatment success rate, higher thanthe other groups. While the group Overall Bolton Ratio &lt;89.39% showed the lowest successful rate of orthodontictreatment. The conclusion is the case with interventions of extraction, slicing, and expansion showed inconsistenciestendency of the three categories of orthodontic treatment outcome assessment, namely canine position, overjet, andoverbite.

A Study on Bolton Anterior Tooth Size Discrepancies among Different Malocclusion Groups

Aim: To investigate the correlation between anterior tooth size discrepancies among Angle's Class l, ll, lll malocclusions and corresponding normal occlusion, as well as their prevalence in Bangladeshi population. This study would act as a reference for diagnosis, treatment planning and assessment of prognosis in some orthodontic cases. Methods: This cross sectional study was conducted in the Department of Orthodontics &amp; Dentofacial Orthopedics, Dhaka Dental College &amp; Hospital. A total number of 200 subjects were selected in Angle's Class l, ll, lll and corresponding normal group. Each group had 50 subjects with males and females. A chi-square test was performed to statistically compare the prevalence of anterior tooth size discrepancies among Angle's Class l, ll, lll malocclusions and corresponding normal occlusion and two genders. Analysis of variance was used to compare the mean Bolton anterior tooth size ratios as a function of angle classification and gender. Statistical differences were determined at the 95% confidence level (p&lt; 0.05). Results: No significant difference was observed in the mean Bolton anterior ratio between normal group and class-I malocclusion group (p = 0.343). Significant differences were observed between Class-II malocclusion and normal group (p=0.001), and also between Class-III malocclusion and normal group (p = 0.001). Individuals with Angle Class lll and Class ll malocclusions showed significantly greater prevalence of tooth size discrepancy than Class l malocclusion and corresponding normal group. Conclusion: The great diversity and ethnic mix of Bangladeshi population should alert our orthodontist to use Bolton analysis as an important diagnostic tool and become aware of the moderate variations that may be present and treated. It may somehow guide planning of this type of study in future. DOI: http://dx.doi.org/10.3329/bjodfo.v1i2.15982 Ban J Orthod &amp; Dentofac Orthop, April 2011; Vol-1, No.2, 1-4

Overjet, overbite and dental midline shift as predictors of tooth size discrepancy in a Bangladeshi population and a graphical overview of global tooth size ratios

Objectives. This study aimed to measure and compare tooth size ratios in a Bangladeshi population across the following groups: those with normal occlusion, crowding or spacing; those with normal, increased or decreased overjet; those with normal, increased or decreased overbite; those with or without dental mid-line discrepancy; and those with or without lip competence. It also presents a graphical overview of the anterior and overall ratios from the study and using available global data. Materials and methods. This study was performed on dental casts of 260 Bangladeshi individuals, comprising 114 males and 146 females (age range, 18–24 years, mean age = 20). The Bolton anterior ratio and overall ratio were determined for the following groups: those with normal occlusion, crowding or spacing; those with normal, increased or decreased overjet; those with normal, increased or decreased overbite; those with or without dental mid-line discrepancy; and those with or without lip competence. Results. There were statistically significant differences in the anterior tooth size ratios between those with or without dental mid-line discrepancy, with a mean value of 78.83% and 80.05%, respectively. Statistically significant differences were also found in overall tooth size ratios between those with normal, increased or decreased overjet and also between those with normal, increased or decreased overbite. Graphical presentations of anterior and overall ratios from the present study and using global data showed variations between populations. Conclusion. In the Bangladeshi population, increased tooth size ratios in subjects with dental mid-line discrepancy (anterior ratio) and also in those with decreased overjet or decreased overbite (overall ratio) may be predictors of tooth size discrepancies. The graphical overview also suggests that different international ethnic groups display unique Bolton ratios.

Validity, reliability, and reproducibility of linear measurements on digital models obtained from intraoral and cone-beam computed tomography scans of alginate impressions

Digital 3-dimensional models are widely used for orthodontic diagnosis. The aim of this study was to assess the validity, reliability, and reproducibility of digital models obtained from the Lava Chairside Oral scanner (3M ESPE, Seefeld, Germany) and cone-beam computed tomography scans of alginate impressions for tooth-width measurements and the Bolton analysis. A digital model, an intraoral scan, and a plaster model were made for each of 22 subjects. Tooth-width measurements on the digital model and the intraoral scan were compared with those on the corresponding plaster models (gold standard). Intraclass correlation coefficients were calculated to determine the interexaminer reliability of the measurements of each method. The anterior and overall Bolton ratios were calculated for each participant and for each method. The paired ttest was used to determine the validity. The scanning time for the intraoral scanner was registered and analyzed. Tooth-width measurements of each tooth on the digital models and the intraoral scans did not differ significantly from those on the plaster models (P>0.05). The overall and anterior Bolton ratios from the 2 types of digital models differed significantly from the gold standard (P<0.05). However, the differences never exceeded 1.5 mm; this could be regarded as clinically insignificant. The scanning times of the intraoral scanner decreased significantly with the number of scans performed. Both intraoral scanning and cone-beam computed tomography scanning of alginate impressions are valid, reliable, and reproducible methods to obtain dental measurements for diagnostic purposes.

Analysis of Bolton's ratio among different malocclusion groups: A hospital based study

AimThe aim of the present study was to compare overall and anterior Bolton ratio in different malocclusion groups with Bolton standards. MethodsSample comprised of 509 pre-treatment casts taken from the department of Orthodontics and dentofacial orthopaedics. Bolton's ratio was measured in different malocclusion groups, and the results were compared with the standard Bolton values. Further ratios were calculated on gender basis and were compared with standard values. Data obtained was analyzed using student's t-test. ResultsStatistically significant differences were found for the whole study group and for overall ratios of class I group. Anterior ratio of class I, class II div 1 and class II div 2 also showed statistical significant differences. There was also significant difference in the overall ratio of male and anterior ratio of male and female groups, when compared with original Bolton standards. ConclusionBolton ratio in patients with malocclusion differ from Bolton standard.

Mesiodistal sizes and intermaxillary tooth-size ratios of two populations; Spanish and Peruvian. A comparative study

Adequate tooth-size ratios are required to ensure the satisfactory outcome of orthodontic treatment. Consequently, various methods of measuring tooth-size ratios have been developed being the Bolton ratio the most commonly accepted, known and used one. This ratio depending directly on mesiodistal tooth size has been associated with different ethnic backgrounds. Some authors suggest the need for specific standards for every population. The objectives of our study were; to measure and to compare mesiodistal tooth sizes and the Anterior and Overall Bolton ratios in two different populations, one Peruvian and the other Spanish with the same digital method. The sample included 149 individuals composed of two groups; 99 Spanish (mean age 14.19), 65 being females and 34 males and 50 Peruvian (mean age 14.46), 18 being males and 32 females. The mesiodistal sizes of each of the patients were measured using a digital method and the Anterior and Overall Bolton ratios were calculated. Tooth size does indeed involve a strong ethnic component, and the Anterior Bolton ratio is specific for each ethnic group. The conclusions are; tooth sizes of the Peruvian population were greater than those of the Spanish population. The Anterior Bolton ratio of Peruvian individuals was greater than that of the Spanish, whereas no differences were found for Overall Bolton ratio. These differences suggest the need for specific standards for the Spanish and Peruvian population.

The effect of premolar extractions on tooth-size discrepancy in malocclusion patients

To establish the ideal occlusal relationship, the values of tooth size and ratio must be in a normal range. In this study, the means and standard deviations of Bolton's anterior ratio and overall ratio using mesiodistal dimensions of teeth measured on diagnostic models of 334 Korean malocclusion patients were calculated and differences in Bolton ratio according to the groups of malocclusion patients were studied. Also the changes that can occur in overall ratio before and after hypothetical tooth extractions were observed. The results are as follows. 1. The mean anterior ratio of Korean malocclusion patients was 78.0;pm;2.69%, and the mean overall ratio was 91.56;pm;2.28%. 2. The largest value of tooth size ratio could be found in Class III group, followed by Class I and Class II groups in order. However there was no statically significant difference. 3. The values of overall ratio reduced significantly after premolar extractions in all malocclusion groups, which was much more significant in the extraction of upper second premolar and lower first premolar(U5L4) or upper second premolar and lower second premolar(U5L5). 4. The values of overall ratio reduced significantly after premolar extractions in all 3 groups divided based on Bolton ratio, which was much more significant in the extraction of upper second premolar and lower first premolar(U5L4) or upper second premolar and lower second premolar(U5L5).

Analysis of interjaw ratios in relation to permanent tooth size in subjects with class I malocclusion

A certain ratio of maxillary to mandibular tooth size is very important for the proper occlusion formation. In regular occlusion, the teeth must be proportional to size. A discrepancy in tooth size between the mandibular and maxillary arch is usually the cause of disharmonious occlusion ratios. One of the most widespread methods in determining of discrepancy in tooth size between the upper and lower jaw is the Bolton analysis of mesiodistal width of permanent teeth. The subjects of both sexes with the permanent dentition and occlusive ratio of Angle Class I classification had had the precise impressions taken on the basis of which the study models were obtained. 60 patients were selected for this investigation (30 males and 30 females) according to the following criteria: the presence of completely erupted teeth of permanent dentition from the first molar on one side to the first molar on the other side of the dental string; good quality of the study models; the absence of mesiodistal and occlusive abrasion, caries lesions, Class II fillings; the absence of prosthetic or composite restoration;the absence of anomalies in regard to shapes, structures and tooth development. We measured the mesiodistal width of each tooth from the first molar on one side to the first molar on the other side, from the mesial contact point to the distal contact point with the greatest interproximal distance. The obtained results for mesiodistal tooth width of the right and left side do not show statistically significant differences. The mean values of the Bolton anterior ratio showed neither the sexual dimorphism nor did the mean values of the Bolton total ratio show any differences in sexes. The mean values of the Bolton anterior ratio in our examinees of both sexes are significantly higher compared to the values of Bolton norms. The mean values of the Bolton total ratios in our examinees of both sexes were not statistically different compared to the values of Bolton norms. Determining of intermaxillary ratios is an important diagnostic and prognostic value in orthodontics since it offers a possibility to predict the outcome of orthodontic therapy applied on persons with tooth size discrepancy related to the upper and lower jaw.

Overall and anterior Bolton ratio in Class I, II, and III orthodontic patients

The aim of the investigation was to compare overall and anterior Bolton ratios in different malocclusion groups with Bolton's standards. The material comprised 600 pre-treatment study casts (262 males and 338 females, aged 12-25 years), selected from the models of 3088 patients who had applied for orthodontic treatment based on the following criteria: permanent dentition from the first right molar to the first left molar and no interproximal caries or restorations. There were 162 Class I, 144 Class II division 1, 155 Class II division 2, and 139 Class III patients. Statistical analysis of the data was undertaken using a Student's t-test. Statistically significant differences were found for the mean overall ratio when compared with the original Bolton norm for the whole study group, as well as for patients with Class I and III malocclusions when the mean anterior ratio was compared with the original Bolton norm. Significant differences were observed in all malocclusion groups for both genders. Discrepancies exceeding 2 SD were found in 31.2 per cent of the studied population for the anterior ratio when compared with Bolton's norm. The highest mean values for anterior ratio were in males with Class I (79.1) and Class III (80.1) malocclusions.