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EFFECTS OF PREMOLAR
EXTRACTIONS ON TOOTH SIZE

INDIAN DENTAL ACADEMY
Leader in continuing dental education
www.indiandenta...
INTRODUCTIO
N
Model analysis and tooth size analysis are the important investigation in
orthodontic diagnosis and treatmen...
AIMS AND
OBJECTIVES


To evaluate the post treatment tooth size discrepancy using Bolton’s
analysis and the clinical appl...
REVIEW OF
LITERATURE
One of the goals in comprehensive orthodontic treatment is to obtain an
optimal final occlusion, over...


Bolton in 1962 presented the clinical application of his tooth-size analysis.
He explained that a ratio set-up between ...


Li et al in 2001 studied the effects of premolars extraction on Bolton
index on Chinese population and reported that Bo...
MATERIALS AND
METHOD


Materials used for the present study were Pretreatment Upper / Lower study
models, Vernier caliper...


The Bolton’s overall tooth size analysis was carried out for each pre
treatment study models with the following formula...


In this study, premolars were hypothetically removed in four different
combinations for each case and overall ratio of ...
OBSERVATION AND RESULTS
MEAN BOLTON VALUES BEFORE AND AFTER TOOTH
EXTRACTION.

0

ALL 1st P.M. ALL 2nd P.M. U1st & L2nd
Xn...
DISTRIBUTION OF DISCREPANCY IN POST EXTRACTION
BOLTON VALUES.

NO OF PATIENTS

100
80

66

65

60

46

40

41

33

20
0

4...
FREQUENCY AND MAGNITUDE OF DISCREPANCIES IN
DIFFERENT MILLIMETER RANGE FOR DIFFERENT
COMBINATION OF PREMOLARS EXTRACTION.
...
DISTRIBUTION OF DISCREPANCY IN POST EXTRACTION
BOLTON VALUES IN THE MAXILLA AND MANDIBLE

www.indiandentalacdemy.com
DISCUSSION


The tooth size discrepancy has increased in all four hypothetical extraction
combinations with maximum incre...


More number of patients showed discrepancy in mandible after extraction
with more increase in the extraction combinatio...


The results of this study can be taken into complete consideration as long
as skeletal base and profile considerations ...
SUMMARY AND
CONCLUSION


As far as tooth size discrepancies are concerned, Bolton’s analysis shows that
extraction of pre...
www.indiandentalacademy.com
Leader in continuing dental education

www.indiandentalacdemy.com
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Effects of premolar extractions on tooth size /certified fixed orthodontic courses by Indian dental academy

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Effects of premolar extractions on tooth size /certified fixed orthodontic courses by Indian dental academy

  1. 1. EFFECTS OF PREMOLAR EXTRACTIONS ON TOOTH SIZE INDIAN DENTAL ACADEMY Leader in continuing dental education www.indiandentalacademy.com www.indiandentalacdemy.com
  2. 2. INTRODUCTIO N Model analysis and tooth size analysis are the important investigation in orthodontic diagnosis and treatment planning. Wayne A. Bolton in 1958 presented the tooth size analysis ratio. The purpose of developing the tooth size analysis was to develop a method of evaluating tooth size ratio which would be an aid in diagnosis and treatment planning of orthodontic cases and also help in determining the functional and esthetic outcome of the case without the use of a diagnostic set-up. Bolton in 1962 presented the clinical application of his tooth-size analysis. He explained that a ratio set-up between arcs of unequal length (such as dental arches) would not remain constant when segments (premolars) of approximately equal size were removed from each arch. www.indiandentalacdemy.com
  3. 3. AIMS AND OBJECTIVES  To evaluate the post treatment tooth size discrepancy using Bolton’s analysis and the clinical applicability of this method and to investigate whether the extraction of four premolars as a requirement of orthodontic therapy is a factor in the creation of tooth-size discrepancies,  To determine which tooth extraction combination creates least amount of discrepancy, and  To evaluate, in which arch the tooth size discrepancy is created and by which combination of extraction of premolars? www.indiandentalacdemy.com
  4. 4. REVIEW OF LITERATURE One of the goals in comprehensive orthodontic treatment is to obtain an optimal final occlusion, overbite and over jet. There are many factors that will influence the attainability of this goal, one of which is the relationship of the total mesiodistal width of the maxillary teeth to that of the mandibular teeth. Over the years many investigators have attempted to quantify this relationship.  Neff in 1949 measured the mesiodistal dimensions of maxillary and mandibular teeth of 200 patients and developed an “anterior coefficient” by dividing the sum of six maxillary teeth by six mandibular teeth. The range was 1.17 to 1.41mm.  Bolton in 1958 measured the mesiodistal widths of the teeth from first molar to first molar in 55 patient’s casts with excellent occlusion and developed overall ratio ( 91.3 % ± 1.91%) and anterior ratio ( 77.2 % ± 1.65%) by comparing maxillary teeth with mandibular teeth.  Stifter in 1958 replicated Bolton’s study in class I dentitions and reported comparable results with overall ratio of 91.04% and anterior ratio of 77.5%. www.indiandentalacdemy.com
  5. 5.  Bolton in 1962 presented the clinical application of his tooth-size analysis. He explained that a ratio set-up between arcs of unequal length (such as dental arches) would not remain constant when segments (premolars) of approximately equal size were removed from each arch. Bolton further stated that after the extraction of four premolars, patients in whom no tooth-size discrepancy existed would have an overall ratio that fell in a range from 87% to 89% with a mean value of 88%.  Lavelle in 1972 found that blacks have larger overall and anterior ratios than whites and Asians. He also showed that anterior and overall ratios were consistently larger in males than in females.  Richardson and Malhotra in 1975 examined blacks and whites using an inter arch ratio and found overall ratio to be 94% and anterior ratio similar to Bolton’s value in blacks and both overall as well as anterior ratio similar to Bolton’s value in whites.  Saatci and Yukay in 1997 while studying the effects of premolars extraction on Bolton overall tooth size ratio have showed that premolar extractions as a requirement of orthodontic therapy creates discrepancy of larger extent in case of all first premolars extraction combination and decreases the discrepancy in case of all second premolars extraction combination. www.indiandentalacdemy.com
  6. 6.  Li et al in 2001 studied the effects of premolars extraction on Bolton index on Chinese population and reported that Bolton overall ratio decreased after extractions with all four different combinations of premolars extractions.  Yang, Xu, and Lin in 2002 also studied the effects of extraction of all first premolars on Bolton overall tooth size ratio in Chinese population and concluded that the overall ratio decreased after extraction of all first premolars.  Recently Tong and Chen in 2004 studied the effects of premolars extractions on Bolton ratio. They studied the effects on models which were divided into 3 broad groups i.e. Bolton Big (BG), Bolton Normal (BN) and Bolton Small (BS) and found that after extraction Bolton ratio have decreased in all 3 groups of models. www.indiandentalacdemy.com
  7. 7. MATERIALS AND METHOD  Materials used for the present study were Pretreatment Upper / Lower study models, Vernier caliper and Case sheet Proforma.  The sample for this study was selected from the Pre treatment study models of the patients undergoing orthodontic treatment in the Department of Orthodontics, Sharad Pawar Dental College & Hospital, Wardha.  The models were selected according to the following criteria:  All the permanent teeth were erupted to allow the measurement of their widest mesio-distal dimension.  No interproximal lesions or restorations were present.  No attempt was made to select the sample on the basis of gender, race or classification of malocclusion.  Mesio-distal width of all the teeth from first molar to first molar in both maxillary and mandibular arches was measured for all pre treatment study models, Total Tooth Material calculated and entered in case sheet. www.indiandentalacdemy.com
  8. 8.  The Bolton’s overall tooth size analysis was carried out for each pre treatment study models with the following formula: Sum of the mandibular ‘12’ width x 100= x% Sum of the maxillary ‘12’ width  Pre treatment study models having Bolton overall tooth ratio between 89.4% and 93.2% were only selected for the present study.  Total 187 pretreatment models were subjected to Bolton’s analysis to get a sample of 100 models.  In the selected sample of 100 cases in which the discrepancy was within the normal range (89.4% to 93.2%), the percentage discrepancy from the mean value of 91.3% was converted into discrepancy in mm with the help of chart given by Bolton.  Bolton in 1962 dealing with the clinical application of his tooth-size analysis stated that in no tooth size discrepancy cases, after the extraction of four premolars, an overall ratio should range from 87% to 89% with a mean value of 88%. www.indiandentalacdemy.com
  9. 9.  In this study, premolars were hypothetically removed in four different combinations for each case and overall ratio of 87% to 89% with a mean value of 88% was used to evaluate tooth size discrepancy.  The extraction combinations used were; (1) All first premolars; (2) All second premolars; (3) Upper first and lower second premolars; and (4) Upper second and lower first premolars.  Bolton analysis was again carried out for each sample after each hypothetical extraction combination by substituting “zero” to the place of the corresponding premolars that were removed.  The resultant values after Bolton’s analysis were recorded and the amount of discrepancy in % from the mean value 88% was calculated and converted into discrepancy in mm with the help of the chart given by Bolton.  All the values were subjected to statistical analysis where in Paired Sample ‘t’ test and Dunnett’s test were applied. www.indiandentalacdemy.com
  10. 10. OBSERVATION AND RESULTS MEAN BOLTON VALUES BEFORE AND AFTER TOOTH EXTRACTION. 0 ALL 1st P.M. ALL 2nd P.M. U1st & L2nd Xns Xns P.M. Xns 1.1807 0.77312 0.77312 0.5 0.77312 1 0.99708 1.4435 1.5522 1.5 0.77312 BOLTON VALUES 2 U2nd & L1st P.M. Xns www.indiandentalacdemy.com TOOTH EXTRACTION TYPE
  11. 11. DISTRIBUTION OF DISCREPANCY IN POST EXTRACTION BOLTON VALUES. NO OF PATIENTS 100 80 66 65 60 46 40 41 33 20 0 47 33 7 1 ALL FOURS 48 11 2 ALL FIVES UPPER FOUR LOWER FIVE UPPER FIVE LOWER FOUR EXTRACTION TYPE EXCESS IN MAXILLA WITHIN NORMAL RANGE www.indiandentalacdemy.com EXCESS IN MANDIBLE
  12. 12. FREQUENCY AND MAGNITUDE OF DISCREPANCIES IN DIFFERENT MILLIMETER RANGE FOR DIFFERENT COMBINATION OF PREMOLARS EXTRACTION. TOOTH EXTRACTION COMBINATION No. of patients with Discrepancy in mm 0—1 1.1—2 2.1—3 More than 3.1 ALL FIRST PREMOLARS 36 31 22 11 ALL SECOND PREMOLARS 52 37 11 0 UPPER FIRST, LOWER SECOND PREMOLARS 36 36 20 8 UPPER SECON D, LOWER FIRST PREMOLARS 46 33 19 2 www.indiandentalacdemy.com
  13. 13. DISTRIBUTION OF DISCREPANCY IN POST EXTRACTION BOLTON VALUES IN THE MAXILLA AND MANDIBLE www.indiandentalacdemy.com
  14. 14. DISCUSSION  The tooth size discrepancy has increased in all four hypothetical extraction combinations with maximum increase in all first premolars extraction combination and least increase in all second premolars extraction combination.  The extraction combination of all first premolars has created discrepancy in maximum i.e. 67 subjects, however extraction combination of all second premolars has created discrepancy in minimum 54 subjects.  The results of Paired Sample ‘t’ test and Dunnet’s test, comparing the difference between Bolton values that were measured before and after the removal of all first premolars and upper first and lower second premolars were found to be statistically significant whereas it was statistically insignificant for other two combinations.  The removal of all second premolars created discrepancies of smaller size and the removal of all first premolars created more frequent and greater discrepancies than the other combinations. www.indiandentalacdemy.com
  15. 15.  More number of patients showed discrepancy in mandible after extraction with more increase in the extraction combination of all first premolars and upper first and lower second premolars.  In this study, the mandibular second premolars showed the largest mean mesio distal dimension (7.37mm) as compared to mandibular first, maxillary first and maxillary second premolars. This may be the reason for creation of more discrepancy in the mandibular arch in other three extraction combinations as compared to all second premolars extraction combination.  Results of this study were compared with similar studies: 1. Saatci and Yukay (1997) on Turkish population. 2. Li et al (2001) and Yang, Xu and Lin (2002) on Chinese population. 3. Tong and Chen (2004) also on Chinese population. These differences in findings can be attributed to several factors like: a) b) c) d) Size of the sample studied; Type of malocclusion patients more prevailing in the sample size; Environmental, Race and Gender; Size of the individual tooth. www.indiandentalacdemy.com
  16. 16.  The results of this study can be taken into complete consideration as long as skeletal base and profile considerations are ideal and no severe proclination or any severe skeletal discrepancy is seen.  The decision to extract must be preceded by great deal of study of all factors including profile, skeletal base, soft tissue etc into consideration before coming to a final treatment diagnosis.  The tooth size ratio must be taken as a diagnostic tool and not a primary requisite, to come to a favourable treatment plan that would finally give the best results to the patient.  Clinically no diagnostic analysis should be taken as the final requirement to come to a treatment plan whereas patients should be individually evaluated and the orthodontist should be aware of other factors in determining which teeth, if any should be removed and use these findings only as one factor to be considered together with many factors. www.indiandentalacdemy.com
  17. 17. SUMMARY AND CONCLUSION  As far as tooth size discrepancies are concerned, Bolton’s analysis shows that extraction of premolars in four different combinations i.e. all first premolars, all second premolars, upper first and lower second premolars and upper second and lower first premolars as requirement of orthodontic therapy is a factor in creation of tooth size discrepancies.  Post extraction Bolton overall tooth size ratios show that after extraction, Bolton overall values have increased in all four different premolar extraction combinations as compared to pre extraction values.  Extraction combination of all second premolars has created the least amount of tooth size discrepancy and all first premolars has created the highest amount of tooth size discrepancy as compared to other combinations.  On evaluating the tooth size discrepancy in various combinations of extractions of premolars, all extraction combinations created discrepancy in mandible with maximum increase in the extraction combination of all first premolars and upper first and lower second premolars. www.indiandentalacdemy.com
  18. 18. www.indiandentalacademy.com Leader in continuing dental education www.indiandentalacdemy.com

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