Bolton Ratios Research Articles

Mastering interproximal stripping: with innovations in slenderization.

ABSTRACTCrowding and irregularity remain a consistent problem for children. Management of space problems continues to play an important role in a dental practice. It also represents an area of major interaction between the primary provider and the specialists. Proximal stripping is routinely carried out to avoid extraction in borderline cases where space discrepancy is less and in cases where there is a discrepancy between the mesio- distal width of maxillary and mandibular teeth to satisfy Bolton ratio. Proximal stripping is carried out using of metallic abrasive strip, safe sided carborundum disk, or with long thin tapered fissure burs with air rotor.The use of rotary cutting instrument can harm the pulp by exposure of mechanical vibration and heat generation (in some cases). Whereas, the large diameter of the disk obstructs vision of the working area. Also fracturing away a portion is a common problem with disk. Tapered fissure burs cut the tooth structure as the width of bur or overcutting may occur of the tooth structure due to high speed. The use of metallic abrasive strip is the safest procedure amongst the above. The strip can be placed in the anterior region without any difficulty but using it in the posterior region is difficult as, it is difficult to hold it with fingers while stripping the posterior teeth.To avoid this inconvenience here with a simple and economical way of fabricating strip holder from routine lab material is presented.Clinical implications: Proper management of space in the primary and mixed dentitions can prevent unnecessary loss in arch length. Diagnosing and treating space problems requires an understanding of the etiology of crowding and the development of the dentition to render treatment for the mild, moderate and severe crowding cases. Most crowding problems with less than 4.5 mm can be resolved through preservation of the leeway space, regaining space or limited expansion in the late mixed dentition. In cases with 5 to 9 mm of crowding, some can be approached with expansion after thorough diagnosis and treatment planning. Most of these cases will require extraction of permanent teeth to preserve facial esthetics and the integrity of the supporting soft tissue. Sequential proximal stripping is routinely carried out to avoid extraction in borderline cases where space discrepancy is less and reserved for treatment of mild tooth-size/arch-size discrepancies.How to cite this article: Sharma NS, Shrivastav SS, Hazarey PV. Mastering Interproximal Stripping: With Innovations in Slenderization. Int J Clin Pediatr Dent 2012;5(2):163-166.

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.

Bolton's ratios and tooth-size discrepancies in a Nigerian population

Objective: The aim of this study was to determine the Bolton's ratios and tooth size discrepancies in a Nigerian population.Method: The Bolton tooth size analysis was performed on 54 dental casts of Nigerian subjects comprising 33 (61%) males and 21 (39%) females (mean 26.6 ± 2.1 years). The overall and anterior tooth size ratios were determined, and gender differences among the sample population was evaluated with t-test. The frequency and magnitude of deviation of theNigerian subjects outside 2 standard deviations from the Bolton's mean was also determined. Result: The result revealed no statistically significant gender differences in interarch tooth size ratios (p> 0.05) and the measurement for both males and females were therefore combined.The overall ratio was 92.1% ± 2.35 and anterior ratio was 78.9% ± 2.64. The overall tooth size discrepancy was present in 9.3% and the 25.9% of the subjects had anterior tooth size discrepancy in relations to more than 2 standard deviations from the Bolton's mean values. Conclusion: The study provided data on tooth size ratios among Nigerian subjects whosevalues were larger than Bolton's data. This study re-emphasized the importance of developing standards for each population.Key words: Tooth size discrepancy, Bolton’s ratios,

Bolton s intermaxillary tooth size ratios among Iranian schoolchildren

The aims of the present study were to determine anterior and total tooth-width ratios in a representative Iranian sample in Tabriz city and compare them with the Bolton standards. A total of 54 Iranian schoolchildren (12-14 years old) in Tabriz were examined. Alginate impressions were taken for subjects and poured by the dental stone. The mesiodistal widths of the teeth were measured using a digital caliper. The overall and anterior Bolton 's intermaxillary tooth size ratios for each model pair was calculated. There were no significant differences (p > 0.05) between the right and left sides of the dental arch and a symmetry in size exists. There were no significant differences between genders for all teeth measured except for the maxillary central incisors, maxillary canines and mandibular canines. Anterior and overall Bolton ratios for males were 77.72±0.25 and 92.44±0.19 and for females were 78.48±0.30 and 92.45±0.23 percent, respectively. There were no statistically significant differences between males and females for the anterior and overall ratios. The anterior and overall Bolton ratios among Tabrizian schoolchildren were 78.10±0.28 and 92.24±0.21 percent, respectively. There was no statistically significant difference between these ratios and those were found in the Bolton study. No significant differences between the mesiodistal sizes of contralateral teeth were observed and a symmetry in size exists. There were no significant differences in the mesiodistal sizes of similar teeth between males and females except for the maxillary central incisors, maxillary canines and mandibular canines. Significant differences in Bolton ratio between males and females, and examined population (student from Tabriz, Iran) and the Bolton's weren't observed either.

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

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

Assessment of crown angulations, crown inclinations, and tooth size discrepancies in a South Indian population

Aims and Objective:The aim of this study was to assess crown angulations, crown inclinations, and tooth size discrepancy in a sample population from Davangere, South India.Materials and Methods:One hundred adults (50 male and 50 female) of age 18–30 years, with Angle's class I ideal occlusion and balanced profiles, were selected for the study. Study models were prepared and crown angulations and crown inclinations were measured using a customized protractor device. Bolton's analysis was used to measure the tooth size discrepancies.Results:Maxillary and mandibular teeth had less crown angulations. Maxillary and mandibular incisors and maxillary molars showed increased crown inclinations, whereas mandibular molars and premolars had less crown inclinations than the original Andrews sample. The mean maxillary and mandibular tooth size ratios, overall and anterior, were similar to Bolton's ratios.Conclusions:The finding of this study indicates that there are possible racial and ethnic factors contributing to variations in crown angulations and crown inclinations.

The Applicability of Bolton's Tooth Size Ratios to the Assamese Population

The Applicability of Bolton's Tooth Size Ratios to the Assamese Population

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

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

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

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

Validity, reliability and reproducibility of three methods used to measure tooth widths for Bolton analyses

Abstract Background Vernier calipers have traditionally been used as the ‘gold-standard’ for tooth width measurements. New digital methods may prove to be as valid, reliable and reproducible as caliper measurements. Aims To determine the validity, reliability and reproducibility of mesio-distal crown measurements made with calipers, using the DigiModel method and on digital photographs, and to determine the validity, reliability and reproducibility when the measurements are employed in Bolton tooth size analyses. Methods Twenty-five consecutive study models were used. The maximum mesio-distal crown widths of 12 teeth in each arch (first molar to first molar) were measured with digital calipers, using the DigiModel software (OrthoProof, Caulfield South, Victoria, Australia) and on standardised digital photographs of the models by eight examiners. One examiner measured all models three times using the three measurement methods, two examiners measured all models once using the three measurement methods and five examiners measured all models once using the calipers only. Validity for the widths of individual teeth, the mean tooth width and the Bolton ratios were assessed using a general linear model two-way analysis of variance and pair-wise comparisons between the two digital methods and the calipers. Reliability was assessed with Cronbach’s alpha and reproducibility with the intra-class correlation coefficient. Results There were statistically significant differences between the tooth widths measured with DigiModel and the calipers (p < 0.001) and with the calipers and digital photographs (p < 0.001). However these discrepancies were judged not to be clinically significant. The Cronbach’s alpha scores for all methods were classified as ‘excellent’. The intra-class correlation coefficient values exceeded 0.75 for the digital calipers, 0.79 for DigiModel and 0.54 for the digital photographs. Conclusions The validities of DigiModel and digital photographs for tooth width measurements and Bolton analyses are clinically acceptable. The reliability of both methods is also excellent. However, DigiModel software provided more accurate Bolton’s ratios and demonstrated greater reproducibility than the digital photographs.

Tooth size discrepancies and arch parameters among different malocclusions in a Jordanian sample.

The objectives of this study were to determine the mean mesiodistal tooth width of the dentition, Bolton anterior and overall ratios, arch length, and arch width in the different malocclusions in a Jordanian sample. The mesiodistal tooth width, arch width, and length were measured on a total of 140 orthodontic models of school students aged 13-15 years of different occlusal relationships (Class I, Class II division 1, Class II division 2, and Class III malocclusions). Anterior and overall Bolton ratios were calculated. The mean and standard deviation were calculated. Student's t-test and analysis of variance were used for the statistical analysis. The results show that (1) females have smaller teeth than males; (2) Class III malocclusion showed larger teeth than the rest of the other occlusal categories; (3) no statistically significant differences were found in Bolton ratios between the different malocclusions; (4) Class II division 1 showed the narrowest maxillary arch compared with the other types of malocclusion; (5) the mandibular intercanine width was significantly larger in Class III group than in Class II division 1 and Class II division 2 groups; (6) the maxillary arch was significantly longer in Class II division 1 than in Class II division 2; and (7) the mandibular arch of both Class II categories was significantly shorter than Class III malocclusion group. In conclusion, tooth size differences were found between right and left sides, between females and males, and between the different malocclusions. Arch width and length also showed differences among the different malocclusions.

Tooth size discrepancies in female patients with palatally impacted canines

Abstract Background Small upper lateral incisors in patients with palatally impacted canines may contribute to inter-arch tooth size discrepancies. Aim To compare the Bolton ratios in female patients with and without unilateral palatally impacted canines. Methods The pretreatment dental casts of 30 female patients with unilateral palatally impacted canines (Impaction group) and 30 female patients without palatally impacted canines (Control group) were used. The latter were matched for age and incisor malocclusion with the Impaction group. The anterior and overall Bolton ratios were calculated for each group. Results Although the total width of the upper anterior teeth in the Impaction group was significantly smaller than the total width of the upper anterior teeth in the Control group (p = 0.029), there was no significant difference between the mesio-distal widths of the lower anterior teeth in the two groups. Furthermore, there were no significant group differences in either the mean anterior Bolton ratio (p = 0.156) or the overall Bolton ratio (p = 0.652). Conclusion Females patients with palatally impacted canines may not have more inter-arch tooth size discrepancies than female patients without palatally impacted canines.

Tooth size discrepancies among Jordanian schoolchildren

The aims of this study were to determine the tooth size discrepancies (TSD) in a representative sample of Jordanian schoolchildren and to compare TSD between genders. Dental casts of 367 (174 males and 193 females; mean age 15.5 years) Jordanian schoolchildren were selected. Anterior and overall Bolton ratios were determined using a digital calliper. Differences between genders were analyzed using a t-test. The results showed that there were no significant differences in the TSD between males and females. The percentages of subjects with more than 2 standard deviations for the anterior and overall ratios were 23.7 and 9.5, respectively.

Posttreatment Occlusal Variability Among Angle Class I Nonextraction Patients

To test the hypothesis that variability among posttreatment Angle Class I, nonextraction patients is not related to patient and treatment factors. One hundred thirty-eight subjects were randomly selected from the archives of the Department of Orthodontics, St Louis University. Patient factors evaluated included age, sex, mandibular plane angle, and ANB angle; treatment factors included active treatment time and supervising orthodontist. Objective Grading System (OGS) scores for six of the criteria (excluding interproximal contacts and root angulations) and the anterior Bolton ratio were measured on the posttreatment study casts. The partial mean overall OGS score was 24.9 +/- 8.0. Occlusal contact was the most important component contributing to the overall score, followed by alignment. Variation in the OGS scores was explained by sex, pretreatment mandibular plane and ANB angles, the posttreatment anterior Bolton ratio, and treatment duration. The partial overall OGS scores increased by approximately one point for every 4 degrees increase in the mandibular plane angle and nearly one point for every 3 additional months of treatment. Approximately 16% and 15% of the variation in alignment and buccolingual inclination, respectively, was due to the treating orthodontist. Posttreatment occlusal variability among Class I nonextraction patients can be partially explained by patient- and treatment-related factors.

Tooth-size discrepancy and Bolton’s ratios: the reproducibility and speed of two methods of measurement

To determine and compare the reproducibility and speed of two methods of performing Bolton's tooth-size analysis. Analysis of randomly selected clinical sample. Bristol Dental Hospital, University of Bristol, United Kingdom. Pre-treatment study casts of 150 patients were selected randomly from 1100 consecutively treated Caucasian orthodontic patients. Bolton tooth-size discrepancies and ratios were measured using two methods; one method employed entirely manual measurement and the Odontorule slide rule, while the other employed digital calipers and the HATS analysis software. Twenty study casts were measured twice, a week apart with both methods. Another three investigators also measured 20 study casts twice with the HATS analysis. There were small or no systematic errors within or between these two methods. A very significant difference was evident for mean time measurements between the two methods (mean time for HATS was 3.5 minutes and for Odontorule was 8.9 minutes). There was relatively high error variance of both methods of measurement as a percentage of the total variance. On-line electronic measurement was found to be more rapid than the manual method used. Both methods demonstrate relatively high random error and this has important consequences for the clinical use of Bolton's ratios.

Accuracy of space analysis with emodels and plaster models

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. 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. 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). 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.

Tooth-size discrepancy and Bolton's ratios: the reproducibility and speed of two methods of measurement

Tooth-size discrepancy and Bolton's ratios: the reproducibility and speed of two methods of measurement

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

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. 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.

Do Bolton’s ratios apply to a Spanish population?

Previous studies have shown that populations differ with respect to interarch tooth-size relationships, and differences in tooth sizes are not systematic. The aims of this study were to determine the Bolton ratios in Spanish subjects. We used a digital method and measured the casts to the nearest 0.05 mm. The sample consisted of 100 pairs of dental casts of Spanish subjects. The Kolmogorov-Smirnov test, t test, and 95% confidence intervals were used. Anterior tooth-width ratios were 78.31% +/- 2.59% for women and 78.34% +/- 2.16% for men (P = .955). Total tooth-width ratios were 91.91% +/- 2.04% for women and 92.10% +/- 1.73% for men (P = .668). No significant differences were found in tooth-width ratios according to sex, so the sexes were pooled and new ratios calculated: 78.32% +/- 2.45%, CI 95% (77.83%-78.81%), for the anterior tooth-width ratio and 91.97% +/- 1.95%, CI 95% (91.58%-92.35%), for the total tooth-width ratio. Twenty-one percent of the subjects had a significant anterior discrepancy (greater than 2 SD from Bolton's), and 5% had a total discrepancy. Differences between Spanish values and Bolton's were significant, and specific standards for Spanish people might be needed.