|Year : 2015 | Volume
| Issue : 1 | Page : 3-7
Extraction: A Parameter in Bolton Ratio
Priyanka Vilas Kale, Dhiraj Rajendra Chhajed, Shivani Shailendra Khapli, Nitin Rameshchandra Tripathi, Gurjeet Kaur Gurmeet Singh Randhawa
Department of Orthodontics, Y.C.M.M and R.D.F Dental College, Ahmednagar, Maharashtra, India
|Date of Web Publication||19-Oct-2015|
Priyanka Vilas Kale
Y.C.M.M and R.D.F Dental College, Ahmednagar, Maharashtra
Source of Support: None, Conflict of Interest: None
Aims: To evaluate extraction as a parameter in determination of Bolton ratio in class II division 1 cases. Materials and Methods: Thirty Class II division 1 cases were selected from the records. Bolton overall ratio was calculated. Hypothetically extraction of four different combinations of premolars was done. These combinations were: Upper first premolar, all first premolars, upper first premolars and lower second premolar, all second premolar. The hypothetical extraction was done by substituting zero in place of the corresponding premolars that were removed. The overall ratios were measured again. Results and Conclusion: (1) Extraction can be considered as a parameter in evaluating Bolton ratio. (2) In upper first premolar extraction Bolton ratio increased. (3) When all first premolar, upper first and lower second premolar, all second premolar were extracted the ratio decreased. (4) In all four first premolar, all second premolar, upper four and lower five premolar extraction can be carried out without much affecting Bolton ratio in class II division 1 cases.
Keywords: Bolton ratio, class II division 1, extraction, premolar
|How to cite this article:|
Kale PV, Chhajed DR, Khapli SS, Tripathi NR, Randhawa GG. Extraction: A Parameter in Bolton Ratio. J Dent Allied Sci 2015;4:3-7
|How to cite this URL:|
Kale PV, Chhajed DR, Khapli SS, Tripathi NR, Randhawa GG. Extraction: A Parameter in Bolton Ratio. J Dent Allied Sci [serial online] 2015 [cited 2021 Sep 19];4:3-7. Available from: https://www.jdas.in/text.asp?2015/4/1/3/167515
| Introduction|| |
The goals of orthodontic diagnosis and treatment planning are to determine the best possible esthetic and functional result at the end of treatment. Many factors influence this goal, and one of them is extraction. Removal of permanent teeth for orthodontic purpose is still a topic subject.
Tooth size is a very important parameter considered in diagnosis and Treatment planning in orthodontics. According to Bolton, , there exists a ratio between the mesiodistal width of maxillary teeth and mandibular teeth. The reason of most of the malocclusion is because of tooth size discrepancies in either maxillary or mandibular arch. Thus, this Bolton , analysis helps in determining disproportion in size in between maxillary and mandibular arch. Also, the Bolton overall ratio will change after premolar extraction,  and it is influenced by different extraction combinations.
What is the effect of premolar extraction on Bolton overall ratio? If orthodontist knows that a tooth size discrepancy will occur or be more severe after extraction of first premolars, then they will be cautious in deciding whether to extract or not. A new parameter of extraction can be added to the Bolton ratio. If orthodontist knows that the tooth size discrepancy will be corrected after extraction of premolars,  the orthodontist will be more likely to make a decision to extract. The purpose of this study is to investigate how the Bolton ratio changes after extraction of various combinations of premolars in class II division 1 patients.
Aims and objective
- Influence of premolar extraction on tooth size discrepancy in patients with class II division 1 malocclusion 
- Find out effect of all four first premolar extraction on Bolton , index
- To determine tooth size discrepancy after upper first premolar and lower second premolar and also after all second premolar extraction
- To find out proper pattern of extraction  in patient with class II division 1 malocclusion  and applicability  of Bolton , in this patient
| Materials and Methods|| |
Class II division 1 patients , were selected from the records of individual treated at the clinical practice of the Department of Orthodontic of our Dental College and Hospital.
Selection criteria were:
- Pretreatment study models of class II division 1 patients with good quality were selected
- All permanent teeth (except third molar) had erupted and were present in both upper and lower arch
- Teeth were not affected by significant size discrepancy or form anomaly
- No tooth decay, residual crown, or crown and bridge restorations were present
- No severe mesiodistal or occlusal tooth abrasion was present
- No tooth deformity or supernumerary teeth were present
A total of 50 patients records were examined to provide 30 acceptable class II division 1 , patient acceptable for the study. They were between 11 and 19 years of age  [Figure 1],[Figure 2],[Figure 3],[Figure 4] and [Figure 5].
|Figure 2: Class II division 1 case model in occlusion - right lateral view|
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|Figure 3: Class II division 1 case model in occlusion - left lateral view|
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A caliper  was used to take readings. The caliper tips was positioned parallel to the occlusal surface of each tooth, measuring the greatest mesiodistal diameter between the anatomic mesial and distal contact points of each tooth from first molar of first quadrant to first molar of second quadrant, and also first molar of third quadrant to the first molar of fourth quadrant.
Bolton , overall ratio was calculated using the formula reported by Bolton. ,
Normal Bolton ratio group  = 91.3% (89-93%).
High Bolton ratio group  ≥ 93%.
Less Bolton ratio group  ≤ 89.
We hypothetically removed four different combinations of premolars. 
These combinations were:
- Upper first premolar
- All first premolars
- Upper fist premolars and lower second premolar
- All second premolar
The hypothetical extraction was accomplished by substituting zero in place of the corresponding premolars that were removed. The overall ratio were measured again and checked for the tooth size discrepancy  in that patient. Moreover, the resultant ratio was recorded.
Data and statistical analysis
- Three groups were done:
- Normal Bolton ratio  = 91.3 (89-93%)
- High Bolton ratio  ≥ 93%
- Less Bolton ratio  ≤ 89
- Mean were taken out of each ratio evaluated after hypothetical extraction to check how Bolton ratio changed  in case of class II division 1 , malocclusion after various combination of extraction ,
- One-way ANOVA test  was done, P value  was also recorded and results were plotted using line diagram
- Tables are made of three different group and Bolton were analyzed and recorded for comparison after considering different extraction pattern in these groups , [Table 1],[Table 2] and [Table 3].
|Table 1: Patient with low Bolton ration and Bolton ratio after different extraction pattern|
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|Table 2: Patient with normal Bolton ratio and Bolton ratio after considering different extraction pattern|
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|Table 3: Patients with high Bolton ratio and Bolton ratio after considering different extraction pattern|
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| Results|| |
- When only upper first premolar was extracted tooth size discrepancy always occurred and Bolton ratio , increased
- When all first premolar, upper first and lower second premolar, all second premolar were extracted the ratio decreased
- In patient with mandibular tooth material excess, the ratio decreased toward normal
- In patients with maxillary tooth material excess, the ratio decreased from normal to low Bolton
- According to the results if we consider Bolton , ratio then all four first premolar, all five second premolar, upper four lower five premolar extraction can be carried out without much affecting Bolton ratio in class II division 1 cases ,,
| Discussion|| |
The aim of the study was to determine Bolton ratio in class II divisions 1 patients ,, before extraction and after extraction of premolars of different combinations. , According to study done by Tong et al.  in 2004, the change of ratio was seen in all extraction combinations. It can be considered that Bolton ratio is affected by different parameters.  Of 30 selected class II division 1 patient, three different Bolton groups were formed as done by Bolton , in 1958 and 1962, 9 patients went in low Bolton ratio group,  13 in normal Bolton ratio group,  and 8 in high Bolton group  which we selected from the population  which came to seek treatment in our department. After doing hypothetical extraction,  we found that Bolton ratio obviously increased in upper first premolar extraction cases, and Bolton ratio , decreased in all first premolars, all second premolars and upper first premolar and lower second premolar extraction cases in patients having class II division 1 malocclusion. 
Study done by Tong et al.  in 2004 concluded that patient who was in high Bolton ratio group shifted in a normal Bolton ratio group and patient who was in normal Bolton ratio group shifted in a low Bolton ratio group. Also, low Bolton ratio group remained in low Bolton ratio group after all first premolars, all second premolars and upper first premolar and lower second premolar extraction cases.  In this study, same results were obtained.
One way ANOVA test  suggested that there is a significant difference in Bolton ratio before extraction and Bolton ratio after upper first premolar extraction. That is, Bolton ratio increased. Also, it suggests that difference in Bolton ratio before extraction and after extraction in remaining group have difference but the difference is not too large that is, Bolton ratio decreased in these cases
The study gave us idea about which extraction pattern can be carried out in class II division I patient without much affecting Bolton ratio and also gave idea about which extraction pattern can cause tooth size discrepancy in these patients [Chart 1-4 [Additional file 1] [Additional file 2] [Additional file 3] [Additional file 4]].
| Conclusion|| |
In the present study, the following conclusions may be drawn when combining changes of numbers and overall ratios and tooth size discrepancy: ,,
- Extraction can be considered as a parameter while doing Bolton analysis
- Extraction pattern affects the Bolton ratio after extraction
- If Bolton ratio is considered then in class II division 1 cases, we can undergo all first premolar extraction, all second premolar extraction, or upper first and lower second premolar extraction. Thus, symmetrical extractions are preferred
- If we extract only upper first premolars then tooth size discrepancy , is bound to happen.
Financial support and sponsorship
Conflicts of interest
There are no conflicts of interest.
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[Figure 1], [Figure 2], [Figure 3], [Figure 4], [Figure 5]
[Table 1], [Table 2], [Table 3]