Comparison of intermaxillary tooth size discrepancies among different malocclusion groups

Tooth size discrepancy in orthodontic patients among different malocclusion groups

An appropriate relationship of the mesiodistal (MD) widths of the maxillary and mandibular teeth favours optimal post-treatment results. The aims of this study were to determine whether there is a difference in the incidence of tooth size discrepancies among different skeletal malocclusion groups and if gender dimorphism exists. The dental casts and lateral cephalometric radiographs of 301 Croatian subjects (127 males and 174 females, mean age 16.86 +/- 2.93 years) were selected from a larger sample of records of the archives of the Orthodontic Department, School of Dental Medicine, University of Zagreb, Croatia. The subjects were from malocclusion groups according to Angle classification, with the corresponding skeletal characteristics. The MD dimensions of all teeth from first molar to first molar were measured on the dental casts using digital callipers. Statistical analysis was undertaken using Kolmogorov-Smirnov, t, and Scheffé's tests and one-way analysis of variance. A statistically significant gender difference was found in anterior ratio (P = 0.017). A significant difference in the overall and posterior ratio was observed between Class II and Class III subjects. There was a tendency for mandibular tooth size excess in subjects with an Angle Class III malocclusion and for maxillary tooth size excess in those with an Angle Class II malocclusion. The percentage of subjects more than 2 standard deviations from Bolton's means for anterior and overall ratios was 16.28 and 4.32, respectively.

Abordagem clínica não-cirúrgica no tratamento da má oclusão de Classe III

A abordagem clínica não-cirúrgica da Classe III coloca-se entre os grandes desafios da Ortodontia e vem, desde sempre, gerando controvérsia entre clínicos e pesquisadores. Alguns defendem a tese de que o crescimento e o desenvolvimento do complexo craniofacial são determinados geneticamente e, portanto, inalteráveis. Para esses, a correção da grande maioria de casos de Classe III passará por intervenções orto-cirúrgicas, devendo a terapia ser realizada assim que cessar o período mais ativo do crescimento. Por outro lado, há aqueles que, mesmo concordando com o peso da hereditariedade na etiologia da Classe III, acreditam ser possível modificar o padrão e a direção do crescimento e, através de uma abordagem não-cirúrgica, minimizar a má oclusão ou até mesmo tratá-la com sucesso. Em face da controvérsia, quais seriam as possibilidades ortodônticas? Inúmeros são os relatos de que uma intervenção adequada, em momento adequado, acompanhada de um estudo do padrão familiar, pode, muitas vezes, minimizar o desenvolvimento de uma Classe III. Procedimentos selecionados com critério podem reduzir a indicação de intervenções cirúrgicas e proporcionar resultados positivos e duradouros. Há evidências clínicas e científicas de que algumas decisões terapêuticas podem mudar o curso de muitos prognósticos sombrios.

Maxillary Anterior Tooth Size and Arch Dimensions in Unilateral Cleft Lip and Palate

Objective:

To investigate differences in size of the maxillary permanent anterior teeth and arch dimensions between individuals with repaired unilateral cleft lip and palate (UCLP) and a matched control group representing the general population.

Design:

Retrospective study cast review.

Participants:

Study casts of 30 subjects due to commence orthodontic treatment following an alveolar bone graft (ABG) were collected from the Cleft Lip and Palate Units in South Yorkshire. Thirty control subjects were collected from a previously validated control group of white individuals in South Yorkshire.

Main Outcome Measures:

Casts were analyzed with an image analysis system to measure the dimensions of the maxillary permanent anterior teeth, incisor chord lengths, and the intercanine and intermolar widths. The results were analyzed statistically using paired t-tests and two-way univariate analysis of variance (ANOVA).

Results:

The mesiodistal widths of maxillary anterior teeth in the study group were smaller than the noncleft control group (p < .01). The dimensions of the cleft side maxillary incisors and incisor chord length were smaller (p < .05 and p < .01 respectively) compared with the noncleft side. The study group maxillary cleft side incisor chord length and maxillary intercanine width were narrower than the control group (p < .0001).

Conclusions:

(1) Anterior teeth are smaller mesiodistally in individuals with UCLP. (2) Maxillary incisors are smaller on the cleft side than the noncleft side. (3) UCLP subjects had smaller maxillary cleft side incisor chord lengths and intercanine widths than the control group despite pre-ABG expansion.

Tooth size discrepancies among different malocclusions in a Japanese orthodontic population

OBJECTIVE

To identify the possible sex differences in anterior and overall tooth size ratios and to evaluate whether any differences exist in tooth size ratios and distributions of subjects with clinically significant tooth size discrepancies among Angle Class I, Class II, and Class III malocclusion groups with the corresponding skeletal characteristics in a Japanese population.

MATERIALS AND METHODS

Each malocclusion group comprised 60 subjects (30 males and 30 females). The mesiodistal width from first molar to first molar was measured on each pretreatment cast to the nearest 0.01 mm using digital calipers, and the anterior and overall ratios were calculated. Student's t-test, Welch t-test, analysis of variance, and chi2-test were performed for statistical analysis.

RESULTS

No statistically significant sex differences were found in anterior or overall ratio in any group. No significant differences in anterior or overall ratios were found among the malocclusion groups. No significant differences were found between the distributions of subjects with clinically significant tooth size discrepancies, categorized by the Bolton standard deviation definition and by the actual amount of change calculated for tooth size correction in millimeters, among the malocclusion groups except for the mandibular correction for the overall ratio between Class I and Class III subjects.

CONCLUSION

Bolton's values can be used with confidence for the typical Japanese orthodontic population. The use of the actual millimeters of correction for the tooth size ratios could help orthodontists avoid underestimating the prevalence of clinically significant tooth size discrepancies.

Evaluation of 3-dimensional tooth crown size in cleft lip and palate patients

INTRODUCTION

The aims of this study were to evaluate 3-dimensional (3D) tooth crown sizes in patients with cleft lip and palate (CLP) and to compare them with those of a Class I control group.

METHODS

Orthodontic dental casts were used of 72 subjects with CLP (20 bilateral [BCLP], 34 unilateral left [ULCLP], 18 unilateral right [URCLP]) and 53 adolescents in the permanent dentition stage with Class I occlusion. Mesiodistal (MD), labiolingual (LL), and occlusogingival (OG) measurements were recorded by the same examiner using a digital caliper. Statistical analyses were conducted, including repeatability, analysis of variance (ANOVA), and the Duncan tests.

RESULTS

Maxillary and mandibular premolar MD dimensions were larger in the CLP groups than in the control group. The smallest MD dimensions were those of the maxillary right lateral incisors in the BCLP group (P <0.05). The maxillary left lateral incisor MD dimensions in the ULCLP group were smaller when compared with other CLP groups (P <0.001). In general, all LL and OG measurements were smaller in the CLP groups than in the Class I group in both dental arches.

CONCLUSIONS

In general, MD, LL, and OG dimensions of CLP patients were smaller than those of the Class I subjects, not only in the affected maxillary dental arch, but also in the mandibular dental arch. Variations in 3D tooth dimensions were found among all CLP types. The lateral incisor in the cleft region was the smallest. A 3D tooth-size evaluation should be included in the diagnostic records to determine precise treatment planning and final occlusion in CLP patients.

A clinical analysis of tooth size discrepancy (Bolton index) among orthodontic patients in Wuhan of Central China

The purpose of this study was to determine the total Bolton index (TBI) and anterior Bolton index (ABI), evaluate the clinical significance of tooth size discrepancies and the influence of gender variation of mesiodistal tooth width on Bolton Index and estimate which tooth has the greatest influence on Bolton Index. A total of 110 pairs of pretreatment dental study casts (41 male and 69 female) were selected from patients treated in Department of Orthodontics of Union Hospital in Wuhan, China. A sliding dental Vernier caliper was used for the measurement of the mesiodistal tooth width. Descriptive statistical mean values, standard deviation, standard error of the mean values, coefficient of variance and the t-test were used for the statistical analysis of the data. The study found that TBI, ABI and the total sum of teeth width had no significant difference between male and female. Male group indicated that Bolton Index (BI) was mostly influenced by the width of lower right second premolar, whereas female group showed that BI was mostly influenced by the width of both the right and left maxillary lateral incisor.

Influence of sex and ethnic tooth-size differences on mixed-dentition space analysis

INTRODUCTION

Most mixed-dentition space analyses were developed by using subjects of northwestern European descent and unspecified sex. The purpose of this study was to determine the predictive accuracy of the Tanaka-Johnston analysis in white and black subjects in North Carolina.

METHODS

A total of 120 subjects (30 males and 30 females in each ethnic group) were recruited from clinics at the University of North Carolina School of Dentistry. Ethnicity was verified to 2 previous generations. All subjects were less than 21 years of age and had a full complement of permanent teeth. Digital calipers were used to measure the mesiodistal widths of all teeth on study models fabricated from alginate impressions. The predicted widths of the canines and the premolars in both arches were compared with the actual measured widths.

RESULTS

In the maxillary arch, there was a significant interaction of ethnicity and sex on the predictive accuracy of the Tanaka-Johnston analysis (P = .03, factorial ANOVA). The predictive accuracy was significantly overestimated in the white female group (P <.001, least square means). In the mandibular arch, there was no significant interaction between ethnicity and sex (P = .49).

CONCLUSIONS

The Tanaka-Johnston analysis significantly overestimated in females (P <.0001) and underestimated in blacks (P <.0001) (factorial ANOVA). Regression equations were developed to increase the predictive accuracy in both arches.

Accuracy of space analysis with emodels and plaster models

INTRODUCTION

The purposes of this study were to determine the accuracy and speed of measuring the overall arch length and the Bolton ratio, and the time to perform a Bolton analysis for each patient by using software (emodel, version 6.0, GeoDigm Corp, Chanhassen, Minn) compared with hand-held plaster models.

METHODS

Models from 30 patients selected from the files of the Department of Orthodontics at West Virginia University were included in this study. The mesiodistal width of each tooth from first molar to first molar was measured to the nearest 0.1 mm with digital calipers, and the Bolton ratio was calculated for each patient. The times required to make the measurements and to perform the analysis were recorded in seconds by using a stopwatch. This process was repeated to record the digital measurements with the software. To evaluate whether there was any magnification in the emodels, quarter-inch ball bearings were mounted on a modified study model. Measurements of the greatest diameter were taken on each ball bearing by using digital calipers and the emodel software. The difference between the 2 methods was calculated, and a paired t test was used to analyze the data.

RESULTS

There was no significant difference between the Bolton ratios calculated with the 2 methods. A significant difference in arch length calculations was found between the 2 methods, but it was within the range of error found in this study and was considered clinically insignificant. Significant differences were found in the time needed to make the measurements and the calculations between the 2 methods; the emodel software was an average of 65 seconds faster. The measurements on the ball-bearing mounted models were an average of .067 mm greater on the emodel software than direct measurements on the casts (range, 0 to -0.16 mm). The difference was significant (P <.0045).

CONCLUSIONS

These results suggest that, when performing a Bolton analysis, the emodel can be as accurate as, and significantly faster than, the traditional method of digital calipers and plaster models. A clinician who has switched to using emodel software can be confident in his or her diagnoses using it.

Applicability of Bolton's tooth size ratios to a Japanese orthodontic population

Previous studies have shown that tooth size ratios are ethnicity-, race-, and sex-specific. This study was carried out to determine anterior and overall ratios in a Japanese population and to compare them with Bolton's ratios. Numerical data were obtained from 60 pairs of dental casts of 30 male and 30 female Japanese orthodontic patients. The mesiodistal widths from first molar to first molar were measured on each cast to the nearest 0.01 mm, by using digital calipers, and the anterior and overall ratios were calculated. The Kolmogorov-Smirnov test, the parametric t test, and Student t test were used for statistical analyses. No statistically significant difference between men and women was found in either the anterior or overall ratio. The combined male and female anterior and overall ratios were 78.39 +/- 2.18% and 91.60 +/- 2.11%, respectively. The combined male and female anterior ratio showed a statistically significant difference from the Bolton standard, whereas the overall ratio showed no statistically significant difference. Significant discrepancies in the anterior and overall ratios were found in 21.6% and 8.3% of patients, respectively. A high prevalence rate of an anterior tooth size discrepancy more than 2SD above Bolton's mean was found. Bolton's anterior ratio was not applicable to the Japanese population, and specific standard tooth size ratios for the Japanese population are needed.

Comparison of tooth size discrepancies among different malocclusion groups

This retrospective investigation was designed to compare tooth size discrepancies among subjects with different skeletal malocclusions in an orthodontic population. The study employed the pre-treatment models of 200 patients (100 males, 100 females, aged from 14 to 20 years) selected from the records of the Orthodontic Department, Shiraz Dental School. The subjects were from four malocclusion groups, Class I, Class II division 1, Class II division 2, and Class III, with the corresponding skeletal characteristics. Each group comprised 50 healthy individuals (25 males, 25 females). The mesio-distal dimensions of teeth were measured using digital electronic callipers (accurate to 0.01 mm) and the Bolton indices were determined. The data were statistically analysed using analysis of variance and Duncan's multiple range test, with the level of significance set at P < 0.05. The results revealed that the mean anterior ratio (79.01) for the whole sample was statistically significantly different from Bolton's (77.2) but no significant difference was found for the overall ratio. The posterior and overall ratios of the Class III malocclusion group were statistically greater than the other malocclusion groups (P < 0.05). The mean anterior ratio of the Class III group was greater than that of the Class II group. However, there was no difference when compared with the Class I malocclusion group. For the two types of Class II malocclusion, no significant ratio differences were observed.

A comparison of dental arch forms between Class II Division 1 and normal occlusion assessed by euclidean distance matrix analysis

INTRODUCTION

The purpose of the study was to use euclidean distance matrix analysis to compare dental arch forms between subjects with Class II Division 1 malocclusions and normal occlusions.

METHODS

The sample consisted of 60 subjects with Class II Division 1 malocclusions and 60 subjects with normal occlusions, all between 13 and 17 years of age. Fourteen landmarks, corresponding to cusp tips and incisor edges, were identified on the dental casts with a 3-dimensional measuring machine. All possible linear distances between pairs of landmarks in an arch were computed, and arch-form differences between Class II Division 1 and normal-occlusion subjects were tested by euclidean distance matrix analysis.

RESULTS

In both sexes, the maxillary arches of the Class II Division 1 subjects were larger than the arches of the normal-occlusion subjects (1.8% and 2.7% larger for girls and boys, respectively), and arch shape was also significantly different (P < .001). The posterior teeth contributed to the shape difference between 2 groups more than the anterior teeth, moreover the main factor was narrow maxillary posterior arch width in the Class II Division 1 subjects. The mandibular arches of the Class II Division 1 subjects were also slightly larger, and arch shape was not significantly different regardless of sex.

CONCLUSIONS

Expanding the maxillary posterior arch width in Class II Division 1 subjects might be an important method to harmonize maxillary and mandibular arch forms.

Determination of Bolton tooth-size ratios by digitization, and comparison with the traditional method

The Bolton Index is one of the most useful calculations for precise orthodontic diagnosis as it shows if there is a correct ratio between dental proportions. However, at times, this calculation is not applied because it is a long and time-consuming procedure compared with digital methods. A new digital method for measuring tooth sizes and for calculating the Anterior (ABI) and the Overall (OBI) Bolton Index was tested on 100 sets of study dental casts of the permanent dentition in a Spanish sample and compared with the traditional method. The reproducibility of this digital method versus the traditional one was analysed to determine intra- and inter-examiner measurement errors by calculating the coefficients of variation. The results demonstrated that the digital method provided results comparable with those of the traditional technique, since the regression parameters for each index showed that the correlation coefficients of the two methods were very high and similar to each other: r = 0.976 and r = 0.979 for the ABI and OBI, respectively. The results also showed more discrepancies in the ABI than in the OBI using both methods in this sample.

Intermaxillary tooth size discrepancy and mesiodistal crown dimensions for a Turkish population

INTRODUCTION

The aims of this study were to determine the size of individual permanent teeth, tooth-size ratios for the maxillary and mandibular dentitions, and sex differences for those variables in a Turkish population, and to compare the figures obtained with those of the Bolton analysis.

METHODS

The data were derived from dental casts of 150 Turkish subjects (72 men, mean age 22.09 +/- 3.11 years; 78 women, mean age, 21.11 +/- 2.08 years) with normal occlusions. The mean, standard deviation, and minimum and maximum values were calculated for individual tooth size, and overall and anterior ratios, separately for men and women. To determine whether there are sex differences in intermaxillary tooth size discrepancies, an independent samples t test was performed.

RESULTS

The mesiodistal dimensions of the maxillary teeth showed greater variability than the mandibular teeth, with the first molar dimensions having the greatest variability. The overall and anterior ratios were found to be 89.88 +/- 2.29 and 78.26 +/- 2.61, respectively. A statistically significant sex difference was found only in overall ratio (P < .001). According to Bolton's mean values, a discrepancy in the overall ratio was found in 18% of Turkish normal occlusion subjects, and anterior ratios outside 2 standard deviations from the Bolton mean were found in 21.3% of our sample.

CONCLUSIONS

These findings indicate that population-specific standards are necessary for clinical assessments. Bolton's original data do not represent Turkish people, and therefore it is appropriate to use Turkish norms in daily orthodontic practice for Turkish patients.

A new way of analyzing occlusion 3 dimensionally

This article introduces a new method for 3-dimensional dental cast analysis, by using a mechanical 3-dimensional digitizer, MicroScribe 3DX (Immersion, San Jose, Calif), and TIGARO software (not yet released, but available from the author at hayasaki@dent.kyushu-u.ac.jp ). By digitizing points on the model, multiple measurements can be made, including tooth dimensions; arch length, width, and perimeter; curve of Spee; overjet and overbite; and anteroposterior discrepancy. The bias of the system can be evaluated by comparing the distance between 2 points as determined by the new system and as measured with digital calipers. Fifteen pairs of models were measured digitally and manually, and the bias was evaluated by comparing the variances of both methods and checking for the type of error obtained by each method. No systematic errors were found. The results showed that the method is accurate, and it can be applied to both clinical practice and research.

Tooth-size ratio for patients requiring 4 first premolar extractions

INTRODUCTION

The relationship between total mesiodistal widths of the maxillary and mandibular teeth is an important factor in orthodontic treatment planning. The purposes of this article are to report a mathematical tooth-size ratio specifically designed for patients needing the extraction of 4 first premolars and to compare the anterior "6" and overall "12" ratio values reported by Bolton with the calculated anterior "6" and overall "10" ratio values obtained from data in this study.

METHODS

This study was conducted in 3 phases. In the first 2 phases, we used the peer assessment rating and ideal cephalometric norms to select 53 ideal posttreatment models of patients who had had 4 premolars extracted. In the third phase, the mean overall "10" ratio and the mean anterior "6" ratio were calculated for the selected models. Bolton's mean overall "12" (91.3%) and anterior "6" ratios (77.2%) were compared statistically with calculations derived from this study by using 1-sample t test.

RESULTS

The mean overall "10" ratio and the mean anterior "6" ratio were found to be 89.28 +/- 1.07% and 77.68 +/- 1.12%, respectively. Although the difference in anterior ratio was not significantly different from Bolton's anterior "6" ratio, there was a statistically significant difference between Bolton's study and our study in overall ratio.

CONCLUSIONS

The mathematical tooth size overall ratio of 89.28% was determined for patients requiring the extraction of 4 first premolars and is recommended for use in diagnosis and treatment planning.

Prevalence of tooth-size discrepancy among different malocclusion groups

This study was designed to estimate the prevalence of tooth-size discrepancy as a factor of skeletal malocclusion in the orthodontic patient population of the Campania region. The study employed the pretreatment models of 94 patients. The mesiodistal diameters of teeth were measured by digital electronic calipers (accurate to 0.01 mm) and Bolton's indices were calculated. The sample was grouped into three malocclusion groups based on the values of Steiner cephalometric analysis. Multiple regression analysis data indicated a significant linear relationship (r2 = 0.99, P = 0.0000) for Bolton's posterior, anterior and total indices. The discriminant multivariate analysis, based on stepwise Wilke's lambda, revealed five variables capable of classifying 88.6% of the sample in the four malocclusion groups. As no relationship between the four groups identified by the discriminant analysis and the types of skeletal malocclusions exists, it was unequivocally concluded that there is no evidence of any predisposition for a tooth-size discrepancy in any of the malocclusion groups.