WL

Question 1

Rational for filling 0.5mm – 1.0mm short of the radiographic apex

Answer 1

Kuttler – distance from the major to the minor diameters

0. 525mm (18-25y/o)
0. 659mm (>55 y/o)

Burch – measured from the occlusal aspect of the major diameter to the apex
Average distance for all roots = 0.59mm

Stein – Measured from the minor diameter (CDJ) to the major diameter = 0.72mm average. Foramen width increases with age but CDJ width does not.

Question 2

EAL

Answer 2

1. Suzuki – Original research in dogs, electrical resistance between periodontium & mucous membrane = constant value 6.5K ohms
2. Sunada – applied Suzuki’s findings to humans, contant = 6,500W (ohms)
3. Kobayashi – developed the ratio method of electronically determining working length. Root ZX measures impedance at 8 and 0,4kHz, and calculates a quotient of the impedance.
4. Baumgartner – Root ZX accurately locates minor diameter ~90% of the time
5. Shabahang – Root ZX is ~96% accurate to within 0.5mm of the apical foramen.
6. Fouad – EAL enhances length control throughout treatment, reduces x-rays

Question 3

Weiger 2001 – x-ray determined WL 0-2mm short of apex causes unintentional overinstrumentation in 51% of premolars and 22% of molars.

Answer 3

How accurate is radiographic working length estimation?

Question 4

Does any solution effect the Root ZX?

Answer 4

NO

1. Meares et al – Root ZX not adversely affected by presence of NaOCl
2. Schindler – No difference in length determination as a function of the seven irrigants used.

Question 5

Does apical resorption affect the Root ZX?

NO

Answer 5

1. Goldberg – apical root resorption did not effect determination of working length

Question 6

Does Pre-Flaring help with the ZX?

Answer 6

Yes
1. Ludlow 1999 – Apical foramen could be reached more consistently by preflaring the canals before obtaining working length.

Question 7

Uses of EAL

Answer 7

1. Katz – root length measurement in primary dentition

2. Fuss- locate perforations

Question 8

Does pulp status matter with the root ZX?

Answer 8

1. Dunlap – no statistical difference in accuracy between between vital and non-vital cases with ratio unit
2. Pommer – vital more accurate than non vital with non ratio units

Question 9

Can you use an EAL with a pacemaker patient?

Answer 9

1. Dorn – 4 of 5 locators tested did not cause inhibition or interfere with normal pacemaker function in vivo
2. Hutter - Check with MD & pacemaker manufacturer !!!