Bolton’s Ratios for Patients with Different Angle’s Malocclusions Seeking

Aims: The study aimed to evaluate the overall and anterior Bolton’s ratio between females and males of the Kurdistan population, and then compare it to Bolton’s original ratio . Materials and methods: This crosssectional study consisted of 160 orthodontic models (80 males, 80 females) that randomly selected from the Kurdistan Iraq population for patients seeking orthodontic treatment, ranging in age from 16 to 34 years. After evaluating the width of each tooth separately using digital caliper, anterior and total ratios were calculated by a formula presented by Bolton . Results: The study’s overall Bolton’s ratio was significantly higher for both females and males at 92.54 and 91.73, respectively, when compared to that of Bolton’s original value of 91.3; the anterior Bolton’s ratio was also significantly higher at 79.97 for males & 79.22 for females, when compared to that of Bolton’s original value of 77.2. The high significant difference was observed between the current study and Bolton’s ratios, with p-value of 0.01, whereas no significant gender differences in any malocclusion group have been found . Conclusions: No gender effect on Bolton’s ratios among all Angle’s classification types.


INTRODUCTION
Delivering an attractive natural smile is a key element in orthodontic patient satisfaction, as teeth master the beauty of the face (esthetic) in addition to speech (phonation) and mastication (1,2,3).
The early prospectors of orthodontics realized the importance of the relation of the teeth in the same and opposite arches should be harmonized in addition to other structures in the face and the mouth, including the tongue, muscles of mastication, and the bones of maxilla and mandible. Spacing and crowding represent the most functional and esthetic problems for patients who attend orthodontic clinics (3,4).
Since the fundamental goal of the orthodontic procedure is to correct alignment of teeth, the accurate evaluation and analysis of dental crowding and the space required to minimize it is important for the successful prognosis of orthodontic treatment, knowing the amount of crowding would be advantageous in other respects too like public health programs and epidemiological studies. By subtracting the required space from the available space, the degree and amount of spacing and crowding can be calculated (5) .
Every orthodontist needs to have an idea about the normal growth of dentition and all changes within the arches with age 6 and having good knowledge about teeth sizes for good treatment planning and good post-treatment occlusion between maxilla and mandible.
A discrepancy in this ratio can instruct treatment plan as if the re approximation is enough or extraction of specific teeth is required, it could also offer whether to include esthetic procedures such as composite bonding, prosthetic reconstruction, or crown recontouring (7) .
Variations in tooth size and width are correlated to ethnic groups (8,9) , as in many other attributes, the size of teeth differs from male to female, female teeth usually smaller than male teeth (9   The inclusion criteria were: 1.
Age ranges from 16 to 34 years.

2.
Class I, II, III molar and canine relationship.

5.
All permanent teeth fully erupted in both jaws from central incisor to the first molar 6.
Good quality cast models 7. Absences of attrition, abrasion, and erosion (3) Two examiners performed the measurements starting from the first molar, the greatest interproximal width (from mesial to distal contact point) has been measured by using sliding stainless digital calipers (Markenlos, china) having an accuracy of 0.01mm as shown in Figure 1 (11,12).

Bolton's Ratios for Patients Treatment in Kurdistan Region
Al-Rafidain Dent J Vol. 21 arches for total and anterior ratios (13,14) .

Calibration
Intra examiner and inter examiner calibration were performed to reduce the possibility of mistakes by randomly selecting 10 cases with different malocclusion types as samples from the 160 casts, the inter examiner made analyses of these cases twice with an interval of 2 weeks. Afterwards, the same samples had been evaluated by intra examiner separately with a period of one week between the two examina-tions. The paired t-test was performed to find the variations between the two results, the readings showed a p-value of 0.99 no significant difference.

Statistical analysis
After the collection and coding of the data, the results were analyzed by windows based SPSS program using t-independent test and ANOVA test with a level of significance at p≤0.05.

RESULTS
The statistical t-test analysis in Table 2 shows a gender comparison of overall and anterior ratios of Kurdistan population, the mean value of anterior ratio for males was 79.97 whereas for females was 79.22. The mean value of overall ratio for males was 92.54 whereas for females were 91.73, even though both the values were somewhat more in males than in females, no significant variation was observed between them. Figure 2 shows the graphical comparison of the same result.

DISCUSSION
The perception of aesthetics differs from one to another person and is impressed by social environment and personal experiences (15).
Among the various diagnostics tools used in order to achieve perfect occlusion with optimal overbite and overjet, Bolton's tooth size analysis is critically important, and it's considered to be the most reliable and common method for detecting interarch discrepancy (7) .
Due to ethnic and gender variations, various studies suggest that Bolton's ratio cannot be universally applied across the populations.
The Relationship between mandibular and maxillary teeth drew the attention of the examiners over decades due to its importance (2) , Initial investigations on tooth size were given by Black (1897) (17) and Neff (1949) (18) .Then Bolton presented his anterior and overall ratios by studying 55 model patients having perfect class I occlusions (7,19) .
Bolton's analysis studies the interrelation of the mesio-distal width of the maxillary teeth to that of the mandibular teeth, according to upper teeth (13) .
That's why it's very helpful in clinical settings and provides perception into functional and esthetic result of orthodontically treated cases, obliterating the need for a diagnostic setup (7,20) .
In the present study, Bolton's ratio derived by using randomly selected 160 samples of different malocclusions. the data were collected from samples of untreated individuals seeking orthodontic treatment, then the anterior and overall ratios were contrast between two genders, it showed no significant difference in either of them, it might be due to close distribution of the mesiodistal width of teeth in females and males; the result of the present study support the findings done by Jamal. (21) in Tikrit city one of the Iraq cities & Ta. et al., (22 ) in Southern Chinese population. Alam et al., (20)  and Nie and lin 29 showed the same result.
As there was no considerable difference in overall and anterior ratios between two genders, the ratios were counted as a whole in order to compare it with that of Bolton 7 .
The result of anterior and overall ratios in this study was significantly higher than Bol- All these factors in addition to different methods of measuring, Bolton's anterior and overall ratio cannot represent samples from other population and races, after applying Bolton analysis on any sample, high discrepancy will be noticed compared to Bolton ratios which could be the reason for diverse findings.