Apical foramen perforation;. â« Periapical tissue damage;. â« Difficulties in controlling obturation length; and Post-operative pain.1. It has been shown that the.
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Technique Tips – Dynamic working length determination
Accurate determination of working length is an important step in root canal instrumentation, as incorrect preparation length can lead to: Inadequate cleaning and shaping of root canal space; Apical foramen perforation; Periapical tissue damage; Difficulties in controlling obturation length; and Post-operative pain.1 It has been shown that the working length of a canal decreases after root canal preparation.2 Therefore, constant reconfirmation of the preparation endpoint is desirable. This is normally achieved by using an ‘apex locator’ in combination with regular radiographic controls. The ‘dynamic working length determination’ technique requires the preparation of a ligature on the endodontic handpiece using a stainlesssteel orthodontic wire (Figure 1). The apex locator circuitry (the ‘file holder’ part) is directly connected to the ligature, rather than to the file, and the lip clip is connected to the patient’s body to complete an electric circuit. It should be noted that this technique is not possible if the endodontic handpiece contains ceramic components, as they will interfere with the electric circuit. It is worth mentioning that some ‘apex locators’ provide delayed readings, thus these should not be used for ‘dynamic working length determination’, as there is a risk of overinstrumentation as a result of this factor. Combinations of ‘apex locator’ and endodontic handpieces and motors are available on the market, with simultaneous preparation and measuring functions; apart from the need to purchase further equipment, the combination ‘apex locator’ and handpiece size is larger than standard ones, making it more difficult to position when working on posterior segments; furthermore, they might not be fully autoclavable,
Figure 1. A stainless-steel orthodontic wire is attached to the endodontic handpiece to create a ligature.
as an ‘apex locator’ is incorporated in the handpiece. The values of this technique are that: It allows for continuous monitoring of the position of the apical foramen in relation to the rotating instrument; If a mechanical glide path is opted for, there is control of the working length from the early stages of the procedure; There is no need to purchase and maintain further specific equipment.
References
1. Ingle JI, Himel VT, Hawrish CE, Glickman GN, Serene T, Rosenberg PA, Buchanan S, West JD, Ruddle CJ, Camp JH, Roane JB, Cecchini SB. Endodontic cavity preparation. In: Endodontics 5th edn. Ingle JI, Bakland LK, eds. London: BC Decker, 2002: pp405–570.
2. Davis RD, Marshall JG, Baumgartner JC. Effect of early coronal flaring on working length change in curved canals using rotary nickel-titanium versus stainless steel instruments. J Endod 2002; 28: 438–442.
CPD ANSWERS
January/February 2014 1. D
6. A, B, D
2. B, C
7. A, B, C
3. A
8. D
4. D
9. B, C, D
5. C
10. D
Vito Antonio Malagnino, MDS, DDS, Professor, University of Chieti-Pescara, Chieti, Italy, Luigi Canullo, DDS, Private Practice, Rome, Italy and Giampiero Rossi-Fedele, DipDent, MClinDent, PhD, Associate Professor, University of Adelaide, South Australia, Australia.
88 DentalUpdate
March 2014
