Bolton tooth size discrepancies in skeletal Class I individuals presenting with different dental angle classifications

Class II subdivision: Cone beam computed tomography- CBCT Analysis

Background

To estimate whether there is skeletal and/or dental asymmetry in class II subdivision patients, between the Class II side and the Class I side using of cone beam computed tomography (CBCT).

Material and Methods

A sample of 30 patients, from a private clinic, retrospectively selected; with a class II subdivision diagnosis requiring treatment, who underwent wide-field CBCT that met the inclusion criteria. The data was processed with Dolphin 3D version 11.95 Premium software. The craniometric points, as well as the spatial orientation scheme of the three-dimensional model were proposed by Craig Minich, et al. (1).

Results

The Class II subdivision side and the Class I side of each patient were compared through intramaxillary, intramandibular, and intermaxillary measurements, evaluating each one in three dimensions (sagittal, frontal, and axial). Also, the measurements made from the three-dimensional volume, were contrasted with those generated in the biplane views. The level of significance used was 0.05. Statistical analysis was performed using the R program (R Development Core Team), version 3.4.4. The intraoperative variability was previously verified using the Dahlberg formula. This error is 0.35 -1.10, so the spatial orientation and placement of craniometric points are repeatable and reliable.

Conclusions

Statistically significant differences have been found with respect to skeletal values and dentoalveolar position. Regarding the skeletal findings, the class II subdivision side is narrower and there is a shortening of the condylar branch. In the dentoalveolar position on this side, the upper molar and canine are in an advanced position, the lower molar is posterior and lower than the contralateral and the lower canine is in a delayed position. Furthermore, measurements made from a two-dimensional image cannot be extrapolated with those made directly from a three-dimensional volume. The problem is generated by a deviation in dental position as well as an underlying asymmetry.

Key words:Class II subdivision, cone beam computed tomography, skeletal asymmetry, dentoalveolar position.

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.

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.

Dental arch dimensions, form and tooth size ratio among a Saudi sample

Objectives:

To determine the dental arch dimensions and arch forms in a sample of Saudi orthodontic patients, to investigate the prevalence of Bolton anterior and overall tooth size discrepancies, and to compare the effect of gender on the measured parameters.

Methods:

This study is a biometric analysis of dental casts of 149 young adults recruited from different orthodontic centers in Jeddah, Saudi Arabia. The dental arch dimensions were measured. The measured parameters were arch length, arch width, Bolton’s ratio, and arch form. The data were analyzed using IBM SPSS software version 22.0 (IBM Corporation, New York, USA); this cross-sectional study was conducted between April 2015 and May 2016.

Results:

Dental arch measurements, including inter-canine and inter-molar distance, were found to be significantly greater in males than females (p<0.05). The most prevalent dental arch forms were narrow tapered (50.3%) and narrow ovoid (34.2%), respectively. The prevalence of tooth size discrepancy in all cases was 43.6% for anterior ratio and 24.8% for overall ratio. The mean Bolton’s anterior ratio in all malocclusion classes was 79.81%, whereas the mean Bolton’s overall ratio was 92.21%. There was no significant difference between males and females regarding Bolton’s ratio.

Conclusion:

The most prevalent arch form was narrow tapered, followed by narrow ovoid. Males generally had larger dental arch measurements than females, and the prevalence of tooth size discrepancy was more in Bolton’s anterior teeth ratio than in overall ratio.

Size discrepancies in molars and first key to optimal occlusion

Objective:

The aim of this research project was to determine whether the sizes of the first molars allow clinicians to achieve the first goal of an ideal clinical outcome.

Material and Methods:

Seventy-eight sets of dental casts that have been presented to the American Board of Orthodontics were evaluated. A Boley gauge was used to measure the length from the mesiobuccal cusp to the distobuccal cusp of the maxillary first molar and the length from the mesiobuccal groove of the mandibular first molar to the occlusal embrasure between the mandibular first and second molars. These two measurements were taken on both sides of each set of dental casts for a total of four measurements per set.

Results:

The maxillary measurements ranged from 3.6 to 6.9 mm with an average of 5.2 mm. The mandibular measurements ranged from 5.0 to 8.0 mm with an average of 6.5 mm. The data were tested for normality and found to be equally distributed. A t-test revealed significant differences in tooth sizes between maxillary and mandibular first molars on both sides. On average, the mesiodistal length measured on maxillary first molars was about 80% of that of their mandibular counterparts. Only 5 of the 78 sets of dental casts evaluated had equal maxillary and mandibular measurements on one side (either left or right), and none of them had equal measurements on both sides.

Conclusion:

Clinicians have to understand that tooth size discrepancies do exist in patients and that these discrepancies make the completion of a perfect case challenging.

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

OBJECTIVE

Comprehensive diagnosis and treatment planning are essential in a successful orthodontic practice. The purpose of this study is to determine and compare intermaxillary tooth size discrepancy (IMTSD) using traditional digital caliper (DC) measurement on plaster dental models and stereomicroscopic digital dental models (SM).

MATERIALS AND METHODS

The samples were randomly selected from different states of Pakistan. Total 7168 variables were measured on plaster dental casts (128) and SM digital dental models (128) according to the selection criteria. For IMTSD, the 6 variable measured as for anterior tooth size (maxilla, mandibular), overall tooth size (maxilla, mandibular), Bolton's anterior ratios (BAR), and Bolton's overall ratios (BOR). The independent t-test and ANOVA were used for statistical analyses.

RESULTS

Significant sexual disparities in the sum of anterior tooth size and overall tooth size via DC and SM methods. No significant sexual disparities for BAR and BOR. No statistically significant differences were found in BAR and BOR between DC and SM. No significant differences were found on IMTSD ratio among different arch length and arch perimeters groups.

CONCLUSIONS

Norms were developed based on DC and SM for IMTSD. Sexual disparities were observed in the sum of teeth size. However, no significant differences in BAR and BOR for IMTSD between the two methods.

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.

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.

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.