MODEL ANALYSIS: BOLTONS ANALYSIS

Sid Ahmed HussainDN-2010-017UMST - Orthodontics Department

INTRODUCTION

Study casts are essential diagnostic aids.

Needed for diagnosis & treatment planning.

Casts are studied & analyzed using various methods.

BOLTON’S ANALYSIS

Analysis performed on study casts Assess tooth size; in the mesio-distal

dimension. According to Bolton; “There exists a ratio

between the mesio-distal widths of maxillary & mandibular teeth.

Abnormal tooth size ---> malocclusion! This analysis help determine disproportion in

size between Maxillary & Mandibular teeth.

BOLTON’S ANALYSIS

There are 4 measurements or variables used in determining the ratio between the maxillary & mandibular teeth1. Sum of Mandibular 122. Sum of Maxillary 123. Sum of Mandibular 64. Sum of Maxillary 6

MODEL

SUM OF MANDIBULAR 12

Sum of all teeth mesial to second permanent molars

Mesio-distal direction measured & summed up.

MODEL

SUM OF MAXILLARY 12

Sum of all teeth mesial to second permanent molars

Mesio-distal direction measured & summed up.

MODEL

SUM OF MANDIBULAR 6

Sum of all teeth mesial to first premolars

Mesio-distal direction measured & summed up.

MODEL

SUM OF MAXILLARY 6

Sum of all teeth mesial to first premolars

Mesio-distal direction measured & summed up.

MODEL

DETERMINING THE OVERALL RATIO

According to Bolton; “The sum of mesio-distal widths of the

mandibular teeth anterior to the second permenant molars is 91.3% the medio-distal width of the maxillary teeth mesial to the second molars”

DETERMINING THE OVERALL RATIO

From the previous slide, it can be concluded that the overall ratio can be determined using the following formula:

Overall Ratio=

Sum of Mandibular 12 x100Sum of

Maxillary 12

DETERMINING THE OVERALL RATIO

If the overall ratio is less than 91.3%, it indicated maxillary tooth material excess.

Maxillary excess is determined using:

Maxillary 12 -

Mandibular 12 x 100

91.3

DETERMINING THE OVERALL RATIO

If the overall ratio is more than 91.3%, it indicated mandibular tooth material excess.

Mandibular excess determined using:

Mandibular 12 - Maxillary 12 x 91.3

100

DETERMINING THE ANTERIOR RATION According to Bolton:

“The sum of mesio-distal width of mandibular anteriors should be 77.2% of the mesio-distal width of maxillary anteriors”

DETERMINING THE ANTERIOR RATIO

From the previous slide, it can be concluded that the anterior ratio can be determined using the following formula:

Anterior Ratio =

Sum of Mandibular 6 x100Sum of

Maxillary 6

DETERMINING THE ANTERIOR RATIO

If the anterior ratio is less than 77.2%, it indicated maxillary anterior excess.

Maxillary excess is determined using:

Maxillary 6 - Mandibular 6 x 100

77.2

DETERMINING THE ANTERIOR RATIO

If the anterior ratio is more than 77.2%, it indicated mandibular anterior excess.

Mandibular excess determined using:

Mandibular 6 - Maxillary 6 x 77.2

100

CONCLUSION

Used in Cast analysis Considers tooth material in medio-distal

dimention 4 measurements taken from cast Overall ratio determined by

< 91.3%; Maxillary excess Maxillary 12 -

>91.3%; Mandibular excess Mandibular 12 -

Sum of Mandibular 12 x100Sum of

Maxillary 12

Mandibular 12 x 100

91.3

Maxillary 12 x 91.3

100

Anterior ratio determined by

<77.2%; Maxillary anterior excess

Maxillary 6 -

>77.2%; Mandibular excess

Mandibular 6 -

Sum of Mandibular 6 x100Sum of

Maxillary 6

Mandibular 6 x 100

77.2

Maxillary 6 x 77.2

100

Mandibular 12

Maxillary 12

Maxillary 6

Mandibular 6

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