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Factors of Renton et al Predictive of a Difficult Mandibular Third Molar Extraction

Purpose: To identify a patient with a mandibular third molar that may be difficult to extract based on the study of Renton et al.

Description

Renton et al identified a number of factors predictive of a difficult extraction of a mandibular third molar. These factors can help to identify a patient who may have more problems during the procedure. The authors are from Guy's, Kings and St. Thomas's Schools of Medicine in London.


Parameters associated with an increased operative time based on multivariate analysis:

(1) age in years

(2) ethnicity of the patient

(3) body weight in kilograms

(4) impaction of the molar

(5) depth of application (from top of the elveolar crest vertically to point of application)

(6) root morphology

 

Parameter

Finding

Points

age

<= 35 years

0

 

> 35 years

1

ethnicity

Caucasian

0

 

non-Caucasian

1

body weight

<= 70 kilograms

0

 

> 70 kilograms

1

impaction of the molar

none or into soft tissue

0

 

into bone

1

depth of applications

<= 6 mm

0

 

> 6 mm

1

root morphology

favorable

0

 

unfavorable (divergent, club-shaped)

1

 

total number of risk factors =

= SUM(points for all 6 parameters)

 

Interpretation:

• minimum number of factors: 0

• maximum number of factors: 6

• Difficulty increased with the number of risk factors.


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Specialty

Objective

ICD-10