Statement of Problem: Tooth size discrepancies (BOLTON RATIO) affect the best possible esthetic and functional results at the end of treatment. The extraction decision is the most critical decision when planning treatment and the premolars are the most common teeth in this decision.Purpose: The purpose of this study was to compare the effect of different patterns of premolar extraction on tooth size discrepancy at the end of orthodontic treatments.Materials and Method: This cross-sectional study was carried out on 200 study models of the patients (145 females and 55 males) who were selected through available selective sampling method. The greatest mesiodistal width of all teeth was measured except for the second and third molars. The measuring was done by a digital caliper with 0.01mm accuracy. According to calculated BOLTON overall RATIOs, the patients’ casts were divided into three groups: NB (Normal BOLTON), DB (Decreased BOLTON), and IB (Increased BOLTON). This classification was based on the overall BOLTON normal values plus or minus one standard deviation. The BOLTON overall RATIOs of each group were measured before and after hypothetical extractions of different four premolars. The data was analyzed using one way ANOVA, and the paired t-test was used for comparing the RATIOs between males and females.Results: The results showed that there was no significant difference between males and females in BOLTON overall RATIOs. Significant differences were found between overall RATIOs for different combinations of premolar extraction before and after extractions. The BOLTON overall RATIOs showed to be smaller after premolar extractions in each group. After premolar extractions, some patients in the NB and IB groups were transferred to the DB, and NB group respectively.Conclusion: According to the results of this study four premolars extraction causes a decrease in BOLTON overall RATIO and in some patients, increased overall RATIOs could be corrected to normal values after removal of second mandibular premolars.

Background and Aim: According to the importance of the harmony of teeth size in establishing a correct occlusion with appropriate overjet, overbite and molar and canine class I relationship, also considering the insufficient and contradictory previous studies in such a field, the goal of the current study was comparing the BOLTON RATIO between different malocclusion groups.Material and methods: The Method of this study was descriptive and cross sectional. For this study 120 cast of orthodontic patients with permanent dentition were selected and divided to four equal malocclusion group (Cl I, Cl II div1, Cl II div2, Cl III). There were 30 patients in each group. The largest mesiodistal width of the teeth of each cast was measured by caliper accurate to 0.1 mm from first left molar of the upper jaw to the first right molar of the lower jaw and BOLTON RATIO were calculated for each specimen. Then ANOVA statical analysis and chi-square test were done on data.Results: BOLTON overall RATIO in patients with class III malocclusion was greater than patients with class I and II malocclusion and this index in patients with class I malocclusion was greater than patients with class II malocclusion. But there were no significant differences between class II div1 and class II div2. Regarding the BOLTON anterior RATIO this index in patients with class III malocclusion was greater than class I and II, and in patients with class I malocclusion was greater than class II div1. But there were no significant differences between class II div1 and 2 and between class I and class II div2. The prevalence of discrepancies about BOLTON overall RATIO was 44.2% and about BOLTON anterior RATIO was 60% in sample population.Conclusion: Findings show highly prevalence of BOLTON discrepancies in sample population. That means we should pay more attention on teeth size before orthodontic treatment

Introduction: The outcome of orthodontic treatment depends on the malocclusion and the RATIO of the size of the upper and lower teeth. The aim of this study was to evaluate the discrepancy of tooth crown size in different groups of malocclusions. Materials & Methods: In this cross-sectional study, 165 patients referred to the Orthodontic Department of Babol School of Dentistry were randomly selected. The samples were divided into three skeletal malocclusion groups (55 in each group) according to the ANB angle. The level of anterior and total BOLTON RATIO in the cases was calculated, and the deviation from normal value of anterior and posterior BOLTON was calculated. The results were analyzed using the ANOVA and chi-square test. The significance level was set at p <0. 05. Results: The sample consists of 80 males and 85 females aged 12 to 25 years. The mean and standard deviation of the anterior tooth RATIO were 79. 06 ±,2. 87 in Cl I, 79. 23 ±,3. 18 in Cl II, and 80. 16 ±,3. 71 in Cl III, and there was no significant difference between the mean anterior RATIO between the malocclusion groups. The mean and standard deviation of the total BOLTON RATIO (TBI) were 91. 3 ±,2. 39 in Cl I, 91. 6 ±,2. 49 in Cl II, and 92. 49 ±,2. 64 in Cl III and the difference between the mean total RATIO among the groups was statistically significant. Conclusion: Based on the results of this study between different groups of malocclusion, clinicians should consider the detailed examination of dental proportions in the diagnosis and treatment planning stage.

Background: There has long been an understanding that a certain maxillary-tomandibular tooth size relationship is important for proper occlusal relationships. The purposes of this study were to compare the BOLTON RATIO's (Anterior and total) of skeletal and dental Cl I individuals in Shiraz and to assess the sizes of teeth and correlation coefficient between similar teeth in the left and right sides and in the upper and lower jaws in males and females.Materials and Method: The data were derived from collected post treatment casts of 50 class I skeletal and dental patients (29 females, 21 males) treated orthodontically by noneextraction method. Measurements of the mesio-distal size (M-D) were performed on the models and BOLTON RATIOs were calculated. Then statistical analysis was done to compare the tooth size and also BOLTON RATIOs.Results: The teeth size correlation was calculated 0.9 between the right and left sides of the jaws and 0.8 between the similar teeth in the upper and lower jaws. The mean value and standard deviation (SD) for the anterior and total RATIOs were: %77.2±2.66, %90.6±2, whit no significant difference with BOLTON's RATIOs, but the range of RATIOs was greater respectively in our sample. The RATIOs were also compared among males and females, but no sex dimorphism was seen.Conclusion: 1- The upper maxillary incisors had the most variable M-D sizes. 2- There was no sex difference in the M-D tooth size of this sample. 3- Although the values of RATIOs were not significantly different from those of BOLTON's value, the greater range and SD of the RATIOs showed the different distribution patterns of the RATIOs in our study. Therefore a careful analysis of interarch relationship should always be induced in diagnostic procedures.

Purpose: To evaluate the prevalence of tooth- size discrepancies among orthodontic patients with sagittal malocclusions by performing BOLTON analysis.Methods & Materials: Two hundred pairs of study models of skeletal Cl I, II, III and crowding were selected. All permanent teeth were present except second and third molars, without any attrition, caries or restoRATIOns on their interproximal surfaces. The greatest mesiodistal diameter was measured to the nearest 0.01 mm by means of digimatic calipers. The BOLTON's anterior and overall RATIOs were perfomed on these models to find tooth-size discrepancies. The mean, SD, range, CV and SE were assessed. The four groups were compared by variance analysis. The amount of obtained RATIOs were compared with BOLTON's RATIOs by T -test, and the difference over 2SD was considered significant.Results: The tooth size discrepancy was more prevalent in crowding group (%14) regarding the overall RATIO, and more in cl III group (%28) regarding anterior RATIO. The means of Anterior and Overall RATIOs in the present study (78.21±2.69, 92.01±92.01±2.45) were larger than BOLTON's measurements (77.2±1.65, 91.3±1.91) (P<0.0001). Even though the means of the tooth size RATIOs of the current study were significantly different from BOLTON's results, the amount of differences were not more than 1.5mm, hence we can apply the BOLTON's RATIOs for Iranian people. When the BOLTON's results were applied to our study, for the Anterior RATIO 23% and for the Overall RATIO 9% of patients fell outside of 2SD and tooth-size discrepancies.Conclusion: Regarding tooth- size discrepancies specially in crowding and crossbite cases, which are not detectable by inspection alone, it is suggested that BOLTON's tooth size analysis be performed before starting the orthodontic treatment. 

Introduction: For proper occlusal interdigitation or coordination of arches in the finishing stage of orthodontic treatment with proper overjet and overbite would have been a proper mesiodistal tooth size RATIO (BOLTON analysis) between maxillary and madibular teeth. The BOLTON analysis should be taken into consideRATIOn when diagnosing, treatment planning and predicting prognosis in clinical orthodontics. In this study tooth size RATIO was evaluated among different malocclusion groups.Materials and Method: This study was carried out on 200 pretreatment orthodontic casts, which were chosen through selective available sampling procedure according to selective criteria's. They were classified by the Angle classification, coincided with skeletal categories.  Skeletal types were assessed by ANB angle from cephalometric analysis. All the subjects were divided into 4 groups: each group consisted of 25 males and 25 females. These groups were Cl I malocclusion, Cl II Div 1, Cl II Div 2 and Cl III. The greatest mesiodistal diameters of all the teeth on each cast were obtained except the second and third molars. The measurement was done by digital caliper with 0.01 mm accuracy. Then tooth size RATIOs were analyzed as BOLTON described.Results: The main anterior RATIO for male patients was larger than that of female patients in all groups (p<0.05), while there was no significant sexual dimorphism for overall and posterior RATIOs between the groups. The mean of the anterior RATIO of Cl III patients was shown to be more than Cl II Div 1 amd Cl II Div 2. No statistical difference was found between Cl III and Cl I patients. Posterior and overall RATIOs of Cl III patients were larger than other groups. The mean overall RATIO of Cl I patients was larger than Cl II Div 1, but it had no significant difference with Cl II Div 2 group.Conclusion: This study suggests that the tooth size discrepancy between the maxillary and mandibular teeth may be one of the important factors in the cause of malocclusions, especially in Cl III malocclusion.

Objective: The aim of this study was to determine BOLTON RATIOs in the Iranian orthodontically treated population of different malocclusions and compare these values among malocclusion groups and with BOLTON reference values. Methods: BOLTON RATIOs of 210 subjects were investigated in three groups of Class I, II, and III skeletal patterns. The measurement of mesiodistal width of teeth was made on post-treatment dental models using a digital caliper. One-way analysis of variance and one-sample t-test were used to compare obtained anterior values and overall RATIOs among studied groups and with reference values, respectively. P-value<0. 05 was considered as significant. Results: The mean values of anterior RATIO in total subjects were 76. 77, and in the Class I skeletal pattern group was 76. 51, which were significantly different from the reference value (p-value < 0. 05). However, the differences in the mean anterior RATIOs of Class II and III groups and the mean overall RATIOs of three studied groups with reference values were not statistically significant. Furthermore, there was no significant difference between the anterior and overall BOLTON RATIOs of the three studied groups (p-value>0. 05). Conclusion: Since the obtained BOLTON RATIOs in Class II and III groups were not significantly different from reference values, these values are also applicable for mild skeletal malocclusions. However, the difference in mean anterior RATIOs of the total 210 subjects and Class I group with BOLTON reference values could be caused by racial differences or several factors related to orthodontic treatment, which can be investigated in subsequent studies.

Introduction: BOLTON analysis is a good indicator to evaluate tooth size discrepancies but the ethnic variation of these values should be considered. Thus, the aim of this study was to determine the tooth RATIOs in different sexes and malocclusion groups in Iranian population and to compare these RATIOs with the data from the BOLTON study. Also the best predictors of anterior and overall BOLTON discrepancies were determined in this study.Materials & Methods: In this cross-sectional study, a total of 715 dental casts (526 female, 189 male) were recruited from department of orthodontics of Shiraz dental school and private offices of orthodontists. The samples were divided into three groups based on Angle’s Malocclusion groups. Then the greatest mesiodistal widths of all teeth were measured with digital caliper with accuracy of 0.01 mm and the anterior and overall RATIOs were calculated. Finally, the data were analyzed by Pearson Correlation, independent t-test and Kruskal-Wallis test, through SPSS software.Results: The anterior RATIO (78.74%) and the overall RATIO (91.94%) showed no statistically significant differences according to sex and malocclusion groups in south Iranian population. The results revealed that the correlation coefficient of lateral RATIO with anterior BOLTON discrepancy was 0.544 and central RATIO with anterior BOLTON discrepancy was 0.536. Also the correlation coefficient of first premolar RATIO with overall BOLTON discrepancy was 0.440 and the second premolar RATIO with overall BOLTON discrepancy was 0.407. Conclusion: The anterior RATIO for the whole population was statistically different from BOLTON’s, but no statistically significant difference was found for the overall RATIO. In Iranian population, the best predictor of anterior BOLTON discrepancy was lateral tooth and the best predictor of overall BOLTON discrepancy was first premolar.

Introdution: For the proper occlusal interdigitation or coordination of arches in the finishing stage of orthodontic treatment with proper overjet and overbite, there must be a proper mesiodistal tooth size RATIO between maxillary and mandibular teeth. The BOLTON analysis should be taken into consideRATIOn while diagnosing, treatment planning and predicting prognosis in clinical orthodontics. The purpose of this study was to evaluate the prevalence of BOLTON discrepancy in the patients attending to Orthodontics Department of Kerman Dental School and private clinics to determine the effects of gender and unilateral maxillary canine impaction on BOLTON RATIO. Methods: This cross sectional study was performed on 311 pretreatment orthodontic casts of patients attending to Orthodontics Department of Kerman Dental School and private clinics between 2012-2015. The greatest mesiodistal dimensions of teeth were measured with digital caliper with accuracy of 0. 01 mm. Independent t-test and chi square were applied to analyze the data by SPSS 18 software and values were considered to be significant when P<0. 05. Results: The mean anterior and overall BOLTON’ s RATIOs were 78. 49% and 91. 73%, respectively without considering malocclusion and gender. The most prevalent anterior and overall BOLTON RATIOs were 41. 5% and 25. 7%, respectively. The anterior and overall BOLTON RATIOs for female patients were greater than male patients. There were no significant relationship between canine impaction and BOLTON’ s RATIOs. Conclusion This study indicated a noticeable prevalence of tooth-size discrepancies in the patients. Regarding tooth-size discrepancies and their effects on occlusion and dental relations, it is suggested that BOLTON’ s tooth size analysis must be performed before starting the orthodontic treatment.