Comparison of intermaxillary tooth size discrepancies among different malocclusion groups

Digital analyses of Bolton tooth size ratios and their association to gender, angle class, and other occlusal traits: a study using a partially automated digital 3D model analysis

BACKGROUND

This study aims to verify Bolton's values for tooth size ratios and to evaluate possible relationships to different occlusal traits using precise digital measurement methods.

MATERIALS AND METHODS

Including 1000 consecutively selected patients from three study centres a digital, partially automated model analysis was performed utilizing the software OnyxCeph. The measurements comprised tooth width for calculation of anterior (AR) and overall ratio (OR) as a percentage, arch width, length, perimeter, overjet, overbite, space analysis in millimetre and the assessment of the angle classification.

RESULTS

AR and OR were significantly increased compared to Bolton's ratios of 77.2% (AR) and 91.3% (OR). In the gender comparison, male patients showed larger tooth size ratios, especially in the OR. Patients with Angle Class II/1 and II/2 had smaller tooth size ratios than patients with Angle Class III and I. Thus, patients with Angle Class II/1 had the largest tooth diameters in all maxillary teeth and with Angle Class II/2 the smallest tooth sizes in the mandible. The largest tooth widths in the lower jaw were observed in the Angle Class III patient group. Furthermore, a negative correlation from AR/OR to overjet, overbite, and available space in lower jaw as well as a positive correlation to available space in upper jaw was detected.

CONCLUSIONS

There is a clear correlation between the tooth size ratios and the present dysgnathia as well as other orthodontically relevant occlusal traits. This prior knowledge about our patients is extremely important to create an individualized treatment plan and enable sufficient occlusion. To achieve a functionally good occlusion with correct overjet and overbite, it is essential that the maxillary and mandibular teeth are proportional in size. Any deviation from the ideal patient in terms of tooth size, number, shape, or arch must be considered in the pre-therapeutic treatment plan in combination with the existing dysgnathia in order to be able to achieve a stable anterior and posterior occlusion with appropriate adjustments to the therapy post-therapeutically.

Using a digital platform to establish odontometric variation based on race, gender and Angle classification

Orthodontists often encounter significant clinical challenges in the finishing stages of treatment due to a disproportion in interarch tooth size relationships. Despite the increasing presence of digital technology and concomitant focus on customized treatment approaches, there is a gap in the knowledge of how generating tooth size data using digital versus traditional methods may impact our treatment regime.

OBJECTIVE

This study aimed to compare the prevalence of tooth size discrepancies using digital models and a digitally based cast analysis in our cohort based on (i) Angle's Classification; (ii) gender and (iii) race.

MATERIALS AND METHODS

The mesiodistal widths of teeth in 101 digital models were assessed using computerized odontometric software. A Chi-square test was used to determine the prevalence of tooth size disproportions among the study groups. The differences between all three groups of the cohort were analysed using a three-way analysis of variance (ANOVA).

RESULTS

An overall Bolton tooth size discrepancy (TSD) prevalence of 36.6% was observed in our study cohort; 26.7% had an anterior Bolton TSD. No differences existed in the prevalence of tooth size discrepancies between male and female subjects as well as between the different malocclusion groups (P > .05). Caucasian subjects had a statistically significant smaller prevalence of TSD compared to Black and Hispanic patients (P < .05).

CONCLUSION

The prevalence results in this study illuminate how relatively common TSD is and underscores the importance of proper diagnosis. Our findings also suggest that racial background may be an influential factor in the presence of TSD.

A study to estimate tooth size discrepancy values specific to Saudi orthodontic patients: A systematic review and meta-analysis

Objective

This study aimed to establish intermaxillary tooth size ratios (overall index (OI) and anterior index (AI)) for normal occlusion and different Angle's malocclusions specific to the Saudi population and compare them to Bolton's values, which were specific to Americans.

Methods

The Saudi Digital Library, PubMed, Web of Science, Cochrane Library, Scopus, and Embase were searched systematically to acquire articles which reported OI and AI for Saudi patients; inclusion and exclusion criteria were applied. Data, including author's name, publication year, city, measurement technique, number of subjects, type of occlusion, means, and standard deviations, were extracted and sorted. To assess the methodological quality of the included studies, The National Heart, Lung, and Blood Institute Quality Assessment Tool for Observational Cohort and Cross-Sectional Studies was utilized.

Results

Of the 1473 articles, eight met the inclusion criteria and were included in the meta-analysis. Values for normal occlusion and Bolton's values were not significantly different. All malocclusion classes showed significant differences in the overall OI and AI values compared with Bolton's original values and values for normal occlusion, but they did not differ from each other. Gender showed an effect only on the OI ratio for Class III malocclusion.

Conclusions

Bolton's original values can be used in Saudi patients only with normal occlusion. For cases with any Angle's malocclusion, we recommend using an AI value of 79.08 (±3.4) for both genders. Classes I and II, regardless of gender, have the same OI value of 92.51 (±2.82). For Class III, values of 91.97 (±2.4) for females and 93.13 (±2.6) for males can be used.

Tooth size discrepancy in orthodontic patients with skeletal anterior open bite

OBJECTIVE

To find out if there is any relationship between tooth size discrepancy (TSD) and skeletal anterior open bite (AOB) and to assess the correlation between the amount of AOB and TSD.

METHOD

A total of 100 Class I subjects were included in this study (average age 15.21 ± 2.84 years). Fifty patients had skeletal AOB (>3 mm) and 50 subjects acted as controls and had a normal overbite. Teeth mesio-distal widths were measured using a digital caliper. Anterior, overall, and posterior TSD ratios were calculated. An independent t-test was employed to assess differences between groups and between genders. Pearson correlation coefficient was used to assess the correlation between the amount of AOB and TSD.

RESULTS

Significant differences in anterior (p = .038) and posterior (p = .015) TSD ratios were detected. In the skeletal AOB group, no significant gender differences were detected (p > .05), whereas in the normal bite and total sample group, males had smaller posterior teeth compared to females (p < .05). All the differences were smaller than 1 SD of Bolton's ratios. No significant correlation was found between the amount of AOB and TSD ratios (p > .05).

CONCLUSIONS

Skeletal AOB had larger anterior and smaller posterior mandibular teeth, but the differences were less than 1 SD of Bolton's ratios. Males have smaller mandibular posterior teeth than females. The amount of AOB is not correlated with the TSD ratios.

Buccolingual and Mesiodistal Dimensions of the Permanent Teeth, Their Diagnostic Value for Sex Identification, and Bolton Indices

Introduction

We aimed (1) to measure the mesiodistal and buccolingual widths of the permanent dentition in Iranian orthodontic patients, (2) to determine cut-off points for sex identification based on the mesiodistal and buccolingual diameters, and (3) to calculate Bolton indices.

Methods

The mesiodistal and buccolingual dimensions of 28 maxillary and mandibular permanent teeth in 331 Iranian nonsyndromic orthodontic patients (dental casts and radiographs) aged 12 to 35 years old with fully erupted permanent dentitions (except the third molars and some sporadic cases of a few teeth missing or excluded) were measured. The anterior, posterior, and overall Bolton ratios were calculated in cases with no missing teeth in the 6-to-6 range. Potentially associated factors (the skeletal Angle classes, crowding, sex, jaws, sides, and age), as well as the value of these measurements for sex determination and cut-off points for sex identification based on these measurements were assessed using receiver-operator characteristic (ROC) curves, analysis of variance (ANOVA), Tukey, unpaired t-test, partial and Pearson correlation coefficients, and multiple linear regression (α = 0.05).

Results

Sex dimorphism was very frequent (P ≤ 0.05 in 41 out of 56 measurements). Only the buccolingual widths of the maxillary lateral and the mandibular central and lateral differed across the Angle classes (ANOVA/Tukey, P < 0.05). Cut-off points were estimated for 38 dental measurements, which were proper for sex identification (P < 0.05), with 8 (2 maxillary and 6 mandibular) measurements being highly appropriate (having areas under ROC curves ≥ 64%, P < 0.05). Both the mandibular canines were the only teeth with all four measurements highly appropriate for this purpose. Controlling for the role of sex, aging was associated negatively with several crown dimensions (the buccolingual widths of the maxillary first and second premolar and mandibular second premolar and first molar; the mesiodistal diameters of the maxillary central, canine, first premolar, and first molar, mandibular central, lateral, first premolar, and first molar, P ≤ 0.05, partial correlation coefficient). There were significant correlations among crown sizes. All the 28 (right/left-averaged) measurements were smaller in microdontia cases (P ≤ 0.002). The anterior, posterior, and overall Bolton indices were 78.05, 105.42, and 91.87, respectively. There were correlations between the overall Bolton ratio with the other two Bolton ratios (Pearson R = 0.696, R = 0.740, P < 0.0005) but not between the anterior and posterior Bolton ratios (R = 0.045, P = 0.459). The skeletal Angle classes might not be associated with the overall and anterior Bolton ratios (ANOVA, regression, Pearson, P > 0.05). However, the posterior Bolton ratio was smaller in class II cases compared to classes I or III (Tukey, P ≤ 0.045). In the whole sample, there was no sex dimorphism in Bolton ratios (t-test, P > 0.05). However, in Angle class II patients, the anterior Bolton ratio was greater in men than in women (P = 0.014).

Conclusions

Sex dimorphism might be very common in the dentition of Iranians, with aging significantly reducing some measurements. The buccolingual widths of some incisors might differ across the skeletal Angle classes. Mandibular canines are the most appropriate teeth for sex identification. The Angle classes might not be associated with the anterior and overall Bolton ratios; nevertheless, the posterior Bolton ratio might be smaller in class II cases compared to others. In general, sex might not affect Bolton ratios; however, in class II patients, the anterior Bolton ratios might be larger in men.

Associations between Bolton ratio and overjet deviations in a Finnish adult population

OBJECTIVE

To determine the anterior Bolton ratio for a Finnish adult population and to investigate its associations with overjet.

MATERIAL AND METHODS

This study is part of the Northern Finland Birth Cohort 1966. Clinical oral investigations, including three-dimensional intraoral scanning and registration of occlusion, were performed in connection with the 46-year follow-up for 1,961 subjects. Subjects with normal occlusion (n = 149), extreme overjet ≥ 8 mm (n = 49), large overjet 6-7 mm (n = 86), and negative overjet (n = 16) and no orthodontic treatment history were selected for further analysis. The mesiodistal widths were measured from canine to canine to evaluate the anterior Bolton ratio.

RESULTS

A mean anterior Bolton ratio of 78.6 (SD 3.1) was found for the normal occlusion group. Subjects with extreme overjet had smaller Bolton ratios compared to the normal occlusion group and the negative overjet group (p = .005, p = .019, respectively). Overjet deviations were associated with upper canine and incisor widths.

CONCLUSIONS

The mean anterior Bolton ratio in subjects with normal occlusion was larger compared to the original Bolton ratio. Tooth size discrepancy was associated with extreme and negative overjet at population level.

The Tooth Size Discrepancy among Orthodontic Patients and Normal Occlusion Individuals from Saudi Arabia: A Three-Dimensional Scan Analysis of Diagnostic Casts

Background/Purpose:

Tooth size discrepancy is one of the causative factors of malocclusion. This study aimed to establish the TDS among various malocclusion classes and normal occlusion subjects in a Southern Saudi population.

Materials and Methods:

The study casts of orthodontic patients from Southern Saudi Arabia (mean age: 19.6 years ± 2.45; n = 120) were randomly selected and grouped into eight equal classes based on Angle's classification and gender. An additional 30 study casts, devoid of malocclusion, having excellent intercuspation and class I occlusion, were grouped into two controls (n = 15) based on gender. The study casts were three-dimensional scanned to measure mesiodistal widths of all the teeth. The calculated anterior ratios (AR) and overall ratio (OR) were statistically analyzed with analysis of variance and t-tests.

Results:

There were no significant differences in “OR” and “AR” between the genders (P > 0.05) and among the malocclusion and control subgroups (P > 0.05). The mean “OR” (92.01 ± 0.18) and “AR” (78.60 ± 0.27) of the malocclusion group were significantly higher than that of Bolton's ratios (P > 0.05). The “AR” of the control group was significantly higher than Bolton's standards (P = 0.048). However, “OR” was no different (P = 0.105). Malocclusion patients displayed a discrepancy (±2 standard deviation) in “AR” of 22.5% and 'OR' of 6.7% from Bolton's mean (BM). Similarly, the control group displayed a discrepancy in “AR” of 20% and “OR” of 10% from BM.

Conclusion:

The mean “OR” and “AR” of the Southern Saudi population showed no sexual dimorphism and no significant difference among various malocclusion and control subgroups. The “AR” of the malocclusion and control subgroups did not comply with Bolton's standards.

Facial soft tissue thickness in Yangtze River delta Han population: Accurate assessment and comparative analysis utilizing Cone-Beam CT

Facial approximation plays a vital role in personal identification when other methods cannot be applied, and the study on facial soft tissue thickness (FSTT) is important to allow more accurate facial approximation. The Cone-Beam CT (CBCT) is considered to be an accurate approach in assessing FSTT, however only few studies have assessed the FSTT norms by CBCT in Chinese populations. The aim of this study was to (1) establish forensic measurement approach on a 3D model reconstructed by CBCT image; (2) obtain FSTT norms from the adults of Yangtze River delta Han population; (3) determine the impacts of sex, age, BMI as well as malocclusion type on FSTT and (4) form a FSTT database through CBCT. A total of 60 facial landmarks were primarily established from 3D reconstructed models from CBCT images of 424 healthy Han adults (130 males and 294 females) aged from 21 to 50 years in Yangtze River delta region and measurements were carried out. The multivariate analysis of variance test and multiple linear regressions test showed that the FSTT values on most landmarks were significantly different between sexes and BMI, and males showed greater values, expect for the landmarks distributed in malarzygomatic areas. Simultaneously, BMI mostly affected the landmarks located in zygomatic region. Besides, only a few landmarks were influenced by age. Interestingly, several periodontal landmarks were influenced by malocclusion types, thus the impact of malocclusion types on FSTT requires attention. Finally, the validation analysis suggested that measurement approach is an important factor for FSTT.

Analysis of Interarch Tooth Size Relationship in Nepalese Subjects with Normal Occlusion and Malocclusions

Introduction

A proportional relationship between the maxillary and mandibular teeth size is required for achieving good finish with proper overjet and overbite postorthodontic treatment. The aims and objectives of this study were to determine the anterior and overall Bolton's ratio in Nepalese population, to compare Bolton's ratio between subjects with normal occlusion, Class I malocclusion, and Class II malocclusion, to compare these results with Bolton's norm, and to determine the frequency of clinically significant (beyond 2 SD) tooth size discrepancy compared to Bolton's norm.

Materials and Methods

The study models of the subjects with normal occlusion and Angle's Class I malocclusion and Class II malocclusion and fulfilling the inclusion criteria were retrieved from department archives. An electronic digital caliper was used to measure mesiodistal tooth size of the maxillary and mandibular teeth anterior to the second molars. The study sample of 120 study models consisted of the normal occlusion group (n = 31), Class I malocclusion group (n = 47), and Class II malocclusion group (n = 42). These measurements were then used to obtain Bolton's ratio in three groups of subjects. Bolton's ratio of study groups was compared with each other and with Bolton's original ratio.

Results

The differences in tooth size ratio of the study groups were not significant statistically, when the groups were compared on the basis of malocclusion or gender. Statistically significant differences were exclusively observed between the study groups and Bolton's original sample for the anterior ratio. The frequency of the clinically significant tooth size ratio discrepancy was lower for the overall ratio (9.1%) compared to the anterior ratio (22.5%).

Conclusions

Bolton's analysis on the Nepalese population sample shows that there was no significant difference observed on the anterior and overall tooth size ratios when these were compared based on Angle's malocclusion classes or gender. The clinically significant anterior tooth size discrepancy was more prevalent than that of the overall ratio.

A systematic review and meta-analysis on Bolton's ratios: Normal occlusion and malocclusion

INTRODUCTION

The purpose of this study was to seek and summarise the Bolton overall index (OI) and anterior index (AI) regarding normal occlusion and Angle's malocclusion according to gender, and to assess if these indices support Bolton's standards as general references.

METHODS

PubMed, LILACS, Embase, CENTRAL and Google Scholar databases were searched up to June 2019 (CRD42018088438). Non-randomised clinical studies, published in English and assessing Bolton's OI and/or AI in normal occlusion and Angle's malocclusion groups, were included. OI and AI means, sample size and SDs were collected. The National Heart, Lung, and Blood Institute's Quality Assessment Tool for Observational Cohort and Cross-Sectional Studies was used to assess the risk of bias. Pairwise random-effects and multilevel Bayesian network meta-analyses were used to synthesise available data.

RESULTS

Fifty-three observational studies were included (11,411 participants; 3746 men, 4430 women; 15 studies lacked gender information). For normal occlusion, pooled estimates for OI and AI means were 91.78% (95% confidence interval [CI] = 91.42-92.14; I² = 92.87%) and 78.25% (95% CI = 77.87-78.62; I² = 90.67%), respectively. We could identify in Angle's Class III patients meaningful OI and AI mean deviations from normal occlusion (0.76, 95% credible interval [CrI] = 0.55-0.98 and 0.61, 95% CrI = 0.35-0.87, respectively), while in Class II patients we found a meaningful mean deviation from normal occlusion only for OI (-0.28, 95% CrI = -0.52--0.05). Concerning gender impact, male patients presented higher OI (0.30, 95% CI = 0.00-0.59) and AI (0.41, 95% CI = 0.00-0.83) mean values than female patients in Class I.

CONCLUSION

Normal occlusion OI and AI mean values differ from Bolton's original values. Class II division 2, for OI mean values, and Class III, for both OI and AI, are proportionally larger than normal occlusion patients. Gender had almost no impact on teeth mesiodistal proportion.

Bolton ratios in Portuguese subjects among different malocclusion groups

Background

Several methods have been described to estimate inter-arch tooth size relationship, such as Bolton’s ratios. The aims of this study were to verify the validity of Bolton indexes in a sample of untreated Portuguese subjects based on Angle classification and to evaluate the gender difference.

Material and Methods

168 pre-treatment dental casts of orthodontics Portuguese subjects (59 males and 109 females) with different occlusions were used, which were selected randomly from 541 consecutively treated orthodontic patients. The mesiodistal widths from first molar to first molar were measured on each pre-treatment cast to the nearest 0.01 mm using digital caliper, and Bolton’s anterior and overall ratios were calculated. Descriptive statistics as mean, standard deviation and range were calculated. Moreover, the results were compared to Bolton’s ratios and differences based on gender and occlusion groups were evaluated by statistical inference methods.

Results

The results reveal that the mean values, standard deviation and range were larger than Bolton’s in normal occlusion group (78.3±3.5% in anterior ratio and 92.1±2.2% in overall ratio) and there were no differences between genders (p >0.05). Class I (anterior and overall ratios, p=0.001 and p<0.001, respectively), Class II/2 (anterior ratio, p=0.032) and Class III (overall ratio, p=0.041) were significantly different from Bolton’s reference data.

Conclusions

The results showed no differences between gender and no difference between normal occlusion and malocclusion groups. Moreover, in normal occlusion group, the anterior and overall tooth size ratios was equivalent to the original Bolton’s ratios, although the mean and standard deviation were large.

Key words:Bolton anterior and overall ratios, normal occlusion, malocclusion, portuguese population.

Overall and Anterior Tooth Size Ratios in a Group of Emiratis

Objectives:

The aims of this investigation in a group of Emiratis were (1) To study overall and anterior tooth size ratios in Class I normal occlusion, (2) To estimate overall and anterior tooth size ratios in different malocclusion groups, (3) To compare overall and anterior tooth size ratios in Class I normal occlusion with the Bolton standards, and (4) To determine the distribution of overall and anterior tooth size ratios ± 2 SD from Bolton mean values in all occlusion groups.

Materials and Methods:

In this cross-sectional investigation, consecutive patients’ files, including dental casts, were selected from the archives of orthodontic clinics of the Dubai Health Authority. The final sample was formed following the application of specific inclusion criteria. The sample consisted of 521 pairs of dental casts representing both sexes (males: 188; females: 333) and different malocclusion groups (Class I: 288; Class II: 110; Class III: 30) and Class I normal occlusion (93). The mean age of patients was 16.18y for Class I, 15.73y for Class II, 15.83y for Class III, and 16.55y for Class I normal occlusion. The dental casts were scanned and digitized by the first author using the Ortho Insight 3D laser scanner. Measurements were made regarding maxillary and mandibular sums of mesiodistal tooth dimension of the overall (6-6) and anterior (3-3) groups of teeth. Statistical analysis included descriptive statistics, paired t-test and Analysis of Variance (ANOVA). The level of significance was set at p<0.05.

Results:

There were statistically significant differences among malocclusion groups with regard to overall and anterior tooth size ratios. However, the comparison between the Class I normal occlusion group and the Bolton standards showed no statistically significant differences. Only five cases in Class II malocclusion presented an anterior tooth size discrepancy outside plus 2 SD from Bolton mean values and one case in Class I malocclusion presented with an overall tooth size discrepancy outside plus 2 SD from Bolton mean values.

Conclusion:

This study of the different occlusion groups of the Emirati sample concluded that (a) Class I normal occlusion cases presented similar overall and anterior tooth size ratios to Bolton standards; (b) Overall and anterior tooth size ratios among different malocclusion groups exhibited statistically significant differences; (c) Five cases in Class II malocclusion presented an anterior tooth size discrepancy outside plus 2 SD from Bolton mean values, and (d) One case in Class I malocclusion presented an overall tooth size discrepancy outside plus 2 SD from Bolton mean values.

[Does gender make a difference in orthodontics? A literature review]

OBJECTIVES

The objective of this literature review is to investigate whether the gender of patients and practitioners makes any difference to orthodontic treatment.

MATERIALS AND METHODS

Sixty-nine articles were selected, the vast majority of which studied patient gender.

RESULTS

Young females are the category of patients which most often apply for orthodontic treatment, probably because of their higher aesthetic demands, despite their objective needs being no greater. Aesthetic, skeletal and dental analyses reveal an obvious dimorphism with larger dimensions in males, especially for the nose, cheekbones, mouth and mandibular canines. Nevertheless, cephalometric angular values do not vary significantly between male and female individuals. Growth is quantitatively greater in males. It also occurs later, as does eruption and maturation of their teeth. Response to the different orthodontic / orthopedic therapies would appear not to differ according to the sex of the patient.

DISCUSSION

These results, however, need to be qualified according to the country concerned, the patients' life style and mind frames, as these can modify or influence the studied parameters.

A Comparative Analysis of Tooth Size Discrepancy between Male and Female Subjects Presenting with a Class I Malocclusion

OBJECTIVES

To evaluate the tooth size discrepancy and Bolton's ratios between male and female subjects with a Class I malocclusion.

MATERIALS AND METHODS

The digital e-models of 100 male and 100 female 12-year-old southern Chinese children with a Class I malocclusion were selected. The mesiodistal widths from permanent first molar to the contralateral side first molar of the upper and lower dentitions were measured. Differences between the tooth size discrepancy, together with the anterior and overall Bolton's ratios between male and female subjects, were assessed using a two-sample t-test. A paired t-test was used to determine differences between antimetric pairs of teeth within the same arch.

RESULTS

Females had statistically significant smaller teeth than males (P < 0.05) except the upper left and lower left lateral incisor and lower left and right central incisors. The mean values of anterior Bolton's ratios for males and females were 77.04 and 77.03, respectively (P > 0.05), while the mean values of overall Bolton's ratios of male and female are 90.48 and 90.65, respectively (P < 0.05). The clinical significant differences (Cohen's d > 0.2) for contralateral tooth size were shown on the maxillary canines, lateral incisors, and central incisors of males; and mandibular canines and lateral incisors of females.

CONCLUSIONS

Southern Chinese females presenting with Class I malocclusions have smaller mesiodistal tooth dimensions compared to males. Both males and females presented several tooth size asymmetries. There are no statistical differences in anterior and overall Bolton's ratios between the genders.

Bolton’s Tooth Size Discrepancy in Malaysian Orthodontic Patients: Are Occlusal Characteristics Such as Overjet, Overbite, Midline, and Crowding Related to Tooth Size Discrepancy in Specific Malocclusions and Ethnicities?

Introduction

Tooth size, occlusal traits, and ethnicity are closely interrelated, and their impact on desirable orthodontic treatment outcome cannot be underestimated. This study was undertaken to assess the occlusal characteristics and ethnic variations in occlusion of Malaysian orthodontic patients and evaluate their correlation with Bolton’s tooth size discrepancy.

Materials and Methods

On 112 pretreatment study models of orthodontic patients, molar relationship, overjet, overbite, spacing, crowding, midline shift, and Bolton’s ratios were assessed. ANOVA, one-sample t-test, Chi-squared test, and Spearman’s rho correlation coefficient were used for statistical analysis.

Results

Significant difference between anterior ratio of our study and Bolton’s ideal values was found, for the entire study sample and Chinese ethnic group. Differences between races and malocclusion groups were not statistically significant (P > 0.05). Significant correlations were found as follows – in Angle’s Class I malocclusion between 1) anterior ratio and overbite, 2) overall ratio and maxillary crowding and spacing; in Angle’s Class II malocclusion between 1) anterior ratio and overjet and midline shift, 2) overall ratio and mandibular crowding; in Angle’s Class III malocclusion between 1) anterior ratio and mandibular crowding and both maxillary and mandibular spacing 2) overall ratio and mandibular crowding.

Conclusions

Significant differences in anterior ratio and Bolton’s ideal values for the Malaysian population were found, indicating variations in anterior tooth size as compared to Caucasians. Statistically significant correlations existed between Bolton’s ratios and occlusal traits. These findings can be applied clinically in diagnosis and treatment planning by keeping in mind the specific discrepancies that can occur in certain malocclusions and addressing them accordingly.

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.

Evaluation of the accuracy and precision of four intraoral scanners with 70% reduced inlay and four-unit bridge models of international standard

The aims of this study were to evaluate the feasibility of 70% reduced inlay and 4-unit bridge models of International Standard (ISO 12836) assessing the accuracy of laboratory scanners to measure the accuracy of intraoral scanner. Four intraoral scanners (CS3500, Trios, Omnicam, and Bluecam) and one laboratory scanner (Ceramill MAP400) were used in this study. The height, depth, length, and angle of the models were measured from thirty scanned stereolithography (STL) images. There were no statistically significant mean deviations in distance accuracy and precision values of scanned images, except the angulation values of the inlay and 4-unit bridge models. The relative errors of inlay model and 4-unit bridge models quantifying the accuracy and precision of obtained mean deviations were less than 0.023 and 0.021, respectively. Thus, inlay and 4-unit bridge models suggested by this study is expected to be feasible tools for testing intraoral scanners.

Tooth-Size Discrepancies in Patients Requiring Mandibular Advancement Surgery

PURPOSE

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.

PATIENTS AND METHODS

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.

RESULTS

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.

CONCLUSION

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.

The Factors Responsible for Endodontic Treatment Failure in the Permanent Dentitions of the Patients Reported to the College of Dentistry, the University of Aljouf, Kingdom of Saudi Arabia

INTRODUCTION

The endodontic failure is a common problem in dentistry. The success of endodontic and re-endodontic treatment depends on many factors. These includes periodontal disease, root fractures, residual necrotic pulp tissue, presence of peri-radicular infection, broken instruments, mechanical perforations, root canal underfillings, root canal overfillings, missed canals or unfilled canals.

AIM

The present research was aimed at evaluating the different factors responsible for endodontic treatment failure in permanent dentitions of the patients.

MATERIALS AND METHODS

In the present in vivo cross-sectional study, 90 patients, who reported in endodontic section of Department of Conservative Dentistry, with post endodontic treatment pain, tenderness to percussion, swelling and sinus tract in their permanent dentitions were considered as endodontic failure cases, and were considered for endodontic re-treatment. The teeth with vertical root fracture and badly broken down unrestorable teeth were excluded from the present study. The study subjects were divided into three groups on the basis of their age. Informed consent was taken from the study subjects and the approval was taken for this study from the college ethical committee.

RESULTS

The results were obtained as frequencies and percentages after analysing the collected informations by using SPSS version 10 computer soft ware. The majority of the endodontic failures were noted in the age group III (41.11%) and minimum endodontic failures were found in the age group I (24.44%). According to the tooth type, the majority of the endodontic failures were noted in maxillary molars (44.4%), mandibular molars (20%) and maxillary premolars (15.5%). The endodontic treatment performed by the general dental practitioners (GDPs) showed the most failure rate (78.8%). The factors which were most responsible for endodontic failures were underfilled canals (33.3%), unfilled and missed canals (17.7%).

CONCLUSION

This study concluded that endodontic failures are more related with the lack of knowledge on the part of the operator, complex anatomy of the teeth involved and lack of referral of such patients to the specialists.

Bolton tooth size ratio among Sudanese Population sample: A preliminary study

Background:

The study of the mesiodistal size, the morphology of teeth and dental arch may play an important role in clinical dentistry, as well as other sciences such as Forensic Dentistry and Anthropology.

Aims:

The aims of the present study were to establish tooth-size ratio in Sudanese sample with Class I normal occlusion, to compare the tooth-size ratio between the present study and Bolton's study and between genders.

Materials and Methods:

The sample consisted of dental casts of 60 subjects (30 males and 30 females). Bolton formula was used to compute the overall and anterior ratio. The correlation coefficient between the anterior ratio and overall ratio was tested, and Student's t-test was used to compare tooth-size ratios between males and females, and between the present study and Bolton's result.

Results:

The results of the overall and anterior ratio was relatively similar to the mean values reported by Bolton, and there were no statistically significant differences between the mean values of the anterior ratio and the overall ratio between males and females. The correlation coefficient was (r = 0.79).

Conclusions:

The result obtained was similar to the Caucasian race. However, the reality indicates that the Sudanese population consisted of different racial groups; therefore, the firm conclusion is difficult to draw. Since this sample is not representative for the Sudanese population, hence, a further study with a large sample collected from the different parts of the Sudan is required.

Is arch form influenced by sagittal molar relationship or Bolton tooth-size discrepancy?

Background

Orthodontic patients show high prevalence of tooth-size discrepancy. This study investigates the possible association between arch form, clinically significant tooth-size discrepancy, and sagittal molar relationship.

Methods

Pretreatment orthodontic casts of 230 Saudi patients were classified into one of three arch form types (tapered, ovoid, and square) using digitally scanned images of the mandibular arches. Bolton ratio was calculated, sagittal molar relationship was defined according to Angle classification, and correlations were analyzed using ANOVA, chi-square, and t-tests.

Results

No single arch form was significantly more common than the others. Furthermore, no association was observed between the presence of significant Bolton discrepancy and the sagittal molar relationship or arch form. Overall Bolton discrepancy is significantly more prevalent in males.

Conclusions

Arch form in a Saudi patient group is independent of gender, sagittal molar relationship, and Bolton discrepancy.

Association between tooth size and interarch relationships in children with operated complete unilateral cleft lip and palate

Background

To evaluate mesiodistal tooth width of patients with UCLP comparing tooth size in different Goslon Yardstick scores and between cleft and noncleft sides.

Methods

The Department of Orthodontics at Bauru Dental School and Hospital of Rehabilitation of Craniofacial Anomalies – University of Sao Paulo. Hundred forty-four pairs of dental casts of patients with UCLP. These dental casts were divided into 3 groups: group I (patients with Goslon rating of 1 and 2), group II (Goslon rating of 3) and group III (Goslon rating of 4 and 5). The control group consisted of 40 pairs of dental casts of noncleft Class I patients at the same age range. Mesiodistal width of maxillary permanent central incisors, lateral incisors and first molars were measured using a digital caliper. Intergroup comparisons were performed using ANOVA followed by Tukey tests. T tests were used to compare tooth size between cleft and noncleft sides (p <0.05).

Results

Differences for tooth size were observed between individuals with different Goslon Yardstik scores. Mesiodistal widths of maxillary central incisors in subjects of Group III were significantly smaller compared to Group I and to the control group. The lateral incisors at the cleft side were smaller than the antimere.

Conclusions

Mesiodistal tooth size was smaller in poor Goslon yardstick scores. Cleft and noncleft sides demonstrated similar maxillary tooth size except for the lateral incisor.

Human Mesiodistal Tooth Width Measurements and Comparison with Dental Cast in a Bangladeshi Population

AIM

This analysis was aimed to determine the mesiodistal tooth width of human teeth and to compare with the measurements on plaster model in a Bangladeshi population.

MATERIALS AND METHODS

The samples of 2,892 teeth of Bangladeshi subjects were collected for this purpose. This article presents mesiodistal tooth width measurements made on all types of teeth and compares with the mesiodistal tooth width measurements of dental cast collected from Bangladeshi subjects between the ages of 18 and 24 years. The mesiodistal dimension was recorded, involving the maximum mesiodistal dimension of each tooth when measurement was rendered parallel to the occlusal and labial surfaces. Descriptive and comparative statistics were applied.

RESULTS

The mean, standard deviation and 95% confidence interval of mesiodistal tooth width measurements were determined and have been with the mesiodistal tooth width measurements of dent al cast. Significant differences have been observed between mesiodistal tooth size of direct measurement on tooth (DMT) and measurement on plaster model (MPM) for the maxillary first molar (p < 0.001) and mandibular incisors to first premolar (p < 0.001).

CONCLUSION

These data should prove to be helpful to the practitioner for performing successful orthodontic treatment in Bangladeshi population.

CLINICAL SIGNIFICANCE

Direct measurement of mesiodistal tooth width and individual variation of maxillary and mandibular permanent central incisor to first molar of the Bangladeshi individuals showed some distinguishable features, which will certainly help an orthodontist for diagnosis and treatment plan of an orthodontic case.

Tooth size discrepancy in a Libyan population, a cross-sectional study in schoolchildren

Objetives: The aim of this cross-sectional study was to investigate the tooth size discrepancy (TSD) in a group of Libyan schoolchildren, and to compare TSD between sexes.

MATERIAL AND METHODS

The sample comprised 333 Libyan schoolchildren (162 males with a mean (SD) age of 14.4 (1.1) years, and 171 females with a mean age of 14.1 (1.1) years). Anterior and overall TSD ratios were computed using descriptive statistics. Sex differences were statistically assessed using an independent t-test (P<0.05).

RESULTS

Males showed significantly wider MD tooth width compared to females (P<0.05), except for the maxillary first premolars and mandibular central incisors. There were significant differences (P<0.05) between the paired (right and left sides) tooth measurements except for the maxillary and mandibular central and lateral incisors as well as mandibular canines. The mean (SD) for overall and anterior TSD ratios were 91.3% (2.1) and 78.2% (2.6), respectively, with no significant sex differences for both variables (P> 0.05). The percentages of participants showing more than 2 SD variation for the anterior and overall ratios comprised 3% and 4.2% of the total sample, respectively.

CONCLUSIONS

The anterior and overall TSD ratios for the examined subjects were established and showed no significant sexual dimorphism. Key words:Tooth size discrepancy, Libyan, schoolchildren.

Orthodontic treatment outcome: the relationship between anterior dental relations and anterior inter-arch tooth size discrepancy

OBJECTIVE

This study investigated the pre- (T1) and post-treatment (T2) relationship between anterior (canine to canine inclusive) inter-arch tooth size ratio and various dental and skeletal variables.

DESIGN

Retrospective longitudinal clinical study.

SETTING

Swedish Health Board Clinic 2000.

SUBJECTS

Random selection of T1 and T2 orthodontic records of 137 Swedish patients (56 male and 81 female). The sample included non-extraction (77), and four premolar extraction (60) cases across a range of dental and skeletal malrelationships.

MAIN OUTCOME MEASURES

Dental cast and lateral cephalogram measurements were recorded. Exploratory modelling investigated whether a significant relationship existed between the anterior inter-arch tooth size ratio and these measurements.

RESULTS

Data was normally distributed with no statistically significant differences between males and females (P = 0.88) and extraction and non-extraction (P = 0.52) treatment modalities with respect to the anterior ratio. T1 bivariate regression analysis failed to show a relationship (p < 0.05) between variables. T2 bivariate analysis showed a statistically significant relation between three variables and anterior tooth size ratio. Multiple regression analysis led to a final model where maxillary inter-canine width (P = 0.002) and upper arch crowding (0.001) were statistically significantly related to the anterior inter-arch ratio. The coefficient of determination was however uniformly low (R(2) < 0.2) for all variables.

CONCLUSION

The anterior inter-arch tooth size ratio was not associated with any common pre- or post-treatment variables in the population studied, therefore measurement of an anterior tooth size ratio pre-treatment was not clinically beneficial for determining anterior dental relations post-treatment.

Tooth-size Discrepancy and Bolton’s Ratios: a literature review

OBJECTIVES

To review the literature on Bolton's tooth-size discrepancies (TSD) with specific attention to the prevalence of TSD, and the possible influence of different classes of malocclusion, gender and racial group. Also examined were the validity of the standard deviations from Bolton's samples as an indicator of significant TSD, methods of measurement of TSD and their reproducibility. Based on the review, suggestions are made as to how future work could be improved.

RESULTS AND CONCLUSIONS

Studies have reported from 20 to 30% of people with significant tooth-size anterior discrepancies and 5-14% for overall TSD. Bolton's original sample was appropriate for indicating what ratio is most likely to be associated with an excellent occlusion, but was not suited to indicating the size or prevalence of significant TSD. Most studies use samples that are not likely to be representative of orthodontic patients in the UK or, indeed, elsewhere. Although some statistically significant differences have been reported, gender and racial group seem unlikely to have a clinically significant influence on Bolton's tooth-size ratios. Class III malocclusions may have larger average ratios. Computerized methods of measurement are significantly more rapid. Most studies performed or reported their error analysis poorly, obscuring the clinical usefulness of the results. Studies are needed to properly explore the reproducibility of measurement of TSD and to appropriately determine what magnitude of TSD is of clinical significance.

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.

Tooth size discrepancies in Class II division 1 and Class III malocclusion requiring surgical-orthodontic or orthodontic treatment

OBJECTIVE

To compare mean anterior (AR) and mean overall (OR) tooth size ratios, prevalence of clinically significant tooth size discrepancies (TSDs) and correlation between AR and OR in subjects with Class II division 1 and Class III malocclusion treated by surgical-orthodontic or orthodontic means.

DESIGN

Retrospective, cross-sectional.

SETTING

State-funded and private clinics.

PARTICIPANTS

From pre-treatment cohorts of 770 surgical and 610 non-surgical subjects, Class II division 1 and Class III malocclusion groups were identified with 60 surgical and 60 non-surgical subjects, comprising 30 males and 30 females, in each.

METHODS

AR and OR were calculated by landmarking digital models. Differences in AR and OR and their relationship were analysed using two-way analysis of variance (ANOVA) and a correlation coefficient, respectively. The proportions of the surgical and non-surgical groups with a TSD were assessed using logistic regression. Intra-examiner reproducibility involved re-landmarking 30 randomly selected image sets and differences in ARs and ORs were compared using a paired t-test. Random error was assessed using the intraclass correlation coefficient (ICC). Analyses were performed using SAS (SAS Institute Inc., Cary, NC, USA) at the 5% level of significance.

RESULTS

There were no statistically significant differences associated with the measurement of either the mean AR (P = 0·913) or the mean OR (P = 0·874). ICC values were very high (AR = 0·95; OR = 0·90). Differences existed between both Class II and Class III surgical (AR: P<0·001; OR: P<0·001) and non-surgical groups (AR: P = 0·012; OR: P = 0·003). The AR and OR relationship was strong (correlation coefficient = 0·72). The highest percentage of clinically significant TSDs was seen in the AR of both Class II and Class III surgical groups (23·3%).

CONCLUSIONS

In the cohort examined: AR and OR differed significantly for malocclusion groups. The prevalence of clinically significant TSDs did not differ significantly between surgical and non-surgical groups although the highest percentage of clinically significant TSDs was recorded for AR in Class II and Class III surgical cases. AR and OR were closely related.

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.

Comparison of mesiodistal tooth widths in Caucasian, African and Japanese individuals with Brazilian ancestry and normal occlusion

OBJECTIVE: To observe the presence of sexual dimorphism and compare the mesiodistal width of the teeth in Caucasian, African and Japanese individuals with Brazilian ancestry not orthodontically treated and with normal occlusion. METHODS: One hundred pairs of dental casts were used. It was measured, from first molar to first molar in both arches, the teeth's mesiodistal widths, using a digital caliper. For the statistical analysis of results Kolmogorov-Smirnov, t test, ANOVA and Tukey's test (p < 0.05) were used. RESULTS: Sexual dimorphism occurred on the three evaluated groups, and the highest mesiodistal widths were found in males. There was statistically significant difference between racial groups in all evaluated teeth in males. However, in females, this same difference was found only on upper lateral incisor and first molar; and lower lateral incisor, canine, first premolar and first molar. CONCLUSION: Most of mesiodistal measures present particular characteristics in relation to gender, with higher values for males, and to race, with a tendency for African to present greater mesiodistal distance of the teeth, followed by Japanese and Caucasians, respectively, important for the correct diagnosis and orthodontic planning.

Comparison of Bolton's Ratios before and after Treatment in an Iranian Population

Background and aims

The correct relationship of the total mesiodistal width of the mandibular teeth to that of the maxillary teeth (Bolton’s ratios) is among the main factors considered in obtaining an optimal occlusion. The present study was conducted to determining the Bolton’s ratios before and after treatment in skeletal class I patients.

Materials and methods

In this descriptive analytical study, 200 study casts of 100 patients (including 73 females and 27 males) were selected from 1,700 patient files with fixed, non-extraction orthodontic treatment protocol. The greatest mesiodistal width of teeth was measured using a digital caliper. The total Bolton index (TBI) and anterior Bolton index (ABI) were calculated for subjects and the obtained results were compared with the values reported by Bolton using one-sample t-test. The alterations in these indexes before and after treatment were compared with paired t-test.

Results

Post-treatment ABI and TBI in patients were 77.35% ± 4.12% and 91.2% ± 1.66%, respectively. No significant difference was detected in ABI and TBI of patients after treatment when compared with the results of Bolton’s study (P > 0.05). However, a significant correlation was observed in values of ABI (P < 0.001) and TBI (P < 0.01) before and after treatment.

Conclusion

These findings suggest that patients with mild hypodontia have narrower teeth than normal subjects espe-cially in posterior segments, which may have clinical implications during the orthodontic treatment process.

Lengths of the maxillary central incisor, the nasal bone, and the anterior cranial base in different skeletal malocclusions

OBJECTIVE

Based on the results of previous studies of osseous structures within the frontonasal field in patients with a known malformation in the frontonasal field, the aim of the present study was to clarify whether the same structures were malformed in patients with severe skeletal malocclusions.

MATERIAL AND METHODS

Incisor, nasal, and cranial base lengths were measured on lateral radiographs of adult patients with skeletal malocclusions, including open bite (n=35), mandibular overjet (n=56), maxillary overjet (n=31), deep bite (n=19), and compared with those of a control group with neutral occlusion and normal craniofacial morphology (n=39). Two-way ANOVA tests were used to evaluate differences in lengths between groups and gender.

RESULTS

Statistically shorter maxillary central incisor length was found in the open bite group (p<0.05), the mandibular overjet group (p<0.001), and in the deep bite group (p<0.001) compared to the controls. Nasal bone length was shorter in the maxillary overjet group compared to controls (p<0.05).

CONCLUSIONS

The lengths of the maxillary central incisor and nasal bone, both parameters located in the frontonasal field, are affected in different skeletal malocclusions. The present findings, especially the deviation of the upper incisor length in different skeletal malocclusions, are considered relevant for orthodontic diagnostics and treatment.

A three-dimensional analysis of the perceived proportions of maxillary anterior teeth

OBJECTIVE

The proportions of the anterior dentition, which is important for excellent esthetics, have been extensively studied, but there have been no 3-dimensional interpretations. This study was conducted to compare real tooth sizes and perceived tooth sizes between different genders and populations and to analyze the effects of 3-dimensional tooth position and alignment.

MATERIALS AND METHODS

Complete dental stone casts were prepared for a total of 139 subjects (50 males and 44 females from Korea and 46 females from Japan). Using 3-dimensional scanning and reconstructions, virtual models were constructed and the widths, lengths and rotations of maxillary anterior teeth were measured. Parameters related to the arch form were measured orthographically. Descriptive statistics and ANOVA were performed to determine the differences among the three groups. A regression model was created to interpret the values of 2-dimensional perceived widths with 3-dimensional measurements and other parameters.

RESULTS

This study observed differences in the average mesiodistal perceived and real dimensions of the maxillary central incisors between Japanese and Korean females, as well as differences in lateral incisor/central incisor ratios and canine/lateral incisor ratios in the perceived 2-dimensional measurements. There were no differences in individual tooth rotations between groups. The r(2) values of the regression model decreased from the central incisors to the canine.

CONCLUSIONS

Several differences were found between Japanese and Korean females and the regression models that used real dimensions, rotations and arch form parameters as independent factors were not sufficient to explain the perceived widths of anterior teeth in the study samples.

Mesiodistal tooth width and tooth size discrepancies of Yemeni Arabians: A pilot study

OBJECTIVES

The aims of this study were to determine the mean mesiodistal tooth size width and Bolton's anterior and overall ratios, find any possible sex differences, and study the frequency of tooth size discrepancies among Yemeni population and if there is a difference in tooth size between the right and left sides.

MATERIALS AND METHODS

176 subjects aged 13-25 years (94 females and 82 males) with different types of malocclusions (94 Angle Class I, 37 Class II division 1, 36 Class II division 2, and 9 Class III) were included in the present study. The mean mesiodistal tooth size width and Bolton's ratios were determined.

RESULTS

The results showed that males had significantly larger teeth than females. The prevalence rates of clinically significant discrepancy greater than 2 SD were 29.53% and 14.20% in the anterior and overall tooth size ratios, respectively. Further, the results revealed that there were no significant differences in the tooth size width between right and left sides.

CONCLUSION

The findings of the present study indicate that there was no significant difference between Bolton's ratio and that of Yemeni population.

Análise de Bolton: uma proposta alternativa para a simplificação de seu uso

INTRODUÇÃO: as discrepâncias entre o tamanho mesiodistal dos dentes superiores e inferiores e seus efeitos sobre a oclusão têm sido relatados há muito tempo. O método proposto por Bolton para o diagnóstico de discrepância de tamanho dentário é, inegavelmente, um dos mais difundidos no meio ortodôntico, devido à sua relativa simplicidade. Entretanto, a aplicação desse método requer cálculos matemáticos e o uso de tabelas que, muitas vezes, inviabilizam a sua utilização durante a avaliação clínica. OBJETIVO: avaliar o método proposto por Wolford, que não requer o uso de tabelas, como alternativa ao método tradicional de Bolton. MÉTODOS: a amostra foi composta por 90 pares de modelos dentários iniciais de pacientes adultos, com diferentes más oclusões. A proporção entre os dentes inferiores e superiores foi calculada para cada paciente, resultando na obtenção de dois índices (a razão total e a razão anterior). Os índices foram obtidos por meio do método originalmente proposto por Bolton e por um método alternativo, composto por duas fórmulas (uma simplificada e a variação da mesma), que foram analisadas separadamente. RESULTADOS: comparadas ao método de Bolton, as fórmulas simplificadas mostraram uma tendência de superestimar as discrepâncias dentárias inferiores (total e anterior), embora em pequena proporção. CONCLUSÕES: ambas as fórmulas do método alternativo podem ser utilizadas em substituição ao método tradicional, uma vez que mostraram diferenças médias menores que 0,58mm quando comparadas ao método de Bolton, não apresentando, portanto, significância clínica.

Comprehensive intermaxillary tooth width proportion of Bangkok residents

Proper occlusion depends on the correct width ratio between upper and lower teeth, known as Bolton's ratio. In fact, this ratio can be calculated for each pair of teeth from the central incisor to the first permanent molar. This set of ratios, known as comprehensive cumulative percentage ratios (CPRs), can be used not only to determine which tooth or teeth have a tooth width discrepancy, but can also enable the partial graphical analysis of tooth width discrepancy when there is agenesis of certain permanent teeth. Although CPRs have been calculated for Caucasians, tooth width is known to vary depending on racial origin. Therefore, a test of differences between racial groups should be carried out. If these ratios of the Caucasians and Bangkokians are significantly different, the ratio of the Bangkokians is recommended. The objective of this study was to measure tooth size disproportion for Thai patients and to calculate a corresponding set of CPRs. Thirty-seven pairs of dental models were made from a group of Bangkok residents with normal occlusion. Mesiodistal tooth width was measured for each model. The intra- and inter-examiner measurement errors were ascertained as insignificant (p > 0.05). CPRs were then calculated and compared to those derived from other studies. Ten of thirteen CPRs were significantly different from corresponding values derived from Caucasians. We conclude that tooth width ratios vary between different racial groups, and therefore that these should be calculated specifically for each patient racial group.

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

INTRODUCTION

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.

MATERIAL AND METHODS

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.

RESULTS

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.

CONCLUSION

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.

Tooth size discrepancies in Irish orthodontic patients among different malocclusion groups

OBJECTIVE

To determine the prevalence of tooth size discrepancies (TSDs) in an Irish orthodontic population among different malocclusion groups.

MATERIALS AND METHODS

From 850 pretreatment sets of orthodontic models at a university clinic, 240 were selected with 30 female and 30 male sets for each malocclusion (Class I, Class II division 1, Class II division 2, and Class III). Digital models were produced, and the mesial and distal contact points were digitized to calculate overall and anterior tooth size ratios. The differences between the male and female groups and among the malocclusion groups were analyzed using two-way analysis of variance (ANOVA) (P < .05).

RESULTS

A clinically significant anterior TSD (more than two standard deviations from the Bolton means) existed in 37.9% of the subjects. No differences existed in the prevalence of overall TSDs between the male and female groups (P  =  .5913) or among the malocclusion groups (P  =  .0809). For the mean anterior tooth size ratios in the male group, the values for Class III and Class II division 2 were higher than in Class II division 1, and the value for Class II division 2 was higher than in Class I (P  =  .0184).

CONCLUSIONS

The prevalence of anterior tooth size discrepancies in this sample of Irish orthodontic patients was 37.9%. There were no statistically significant differences in the prevalence of mean overall TSDs with regard to malocclusion or gender. In the male group, the mean anterior tooth size ratio was higher in Class III and in Class II division 2 malocclusion than in Class II division 1 and higher in Class II division 2 malocclusion than in Class I malocclusion.

Dental archforms in dentoalveolar Class I, II and III

OBJECTIVE

To test the hypothesis that no differences exist in dental arch dimensions between dentoalveolar Classes I, II, and III, and between male and female subjects, as measured on virtual three-dimensional (3D) models.

MATERIALS AND METHODS

Samples included randomly selected plaster dental casts of 137 white patients (43 Class I, 50 Class II, and 44 Class III) from the Department of Orthodontics, School of Dental Medicine, University of Zagreb, Croatia. Dental models were scanned and digitized using ATOS II SO ("Small Objects") scanning technology (GOM mbH, Braunschweig, Germany). Eight linear and two proportional measurements were calculated for both upper and lower dental arches.

RESULTS

In men, a significant difference in the upper dental arch was present in the incisor region, and in the lower dental arch, differences were found in intercanine and intermolar widths (P < .05). Significant differences were noted between male groups in the upper molar depth dimension (P = .022) and in the lower molar and canine depth dimensions (P < .05). Class III males had the greatest lower molar and canine width/depth ratios and the smallest lower canine depth/molar depth ratio. Class III women had wider and shorter mandibular arches when compared with Class I and Class II females.

CONCLUSION

The hypothesis was rejected. The dimensions of the dental arches are related to gender and to dentoalveolar class. Class I and II subjects have similar dimensions of maxillary dental arch, but Class II subjects have a transverse deficit in the mandible. In Class III subjects, the maxillary dental arch is insufficient in transverse and sagittal dimensions, and the mandibular arch dominates in the transverse but not in the sagittal dimension.