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Clinical Endodontics

0 Comments Jul 10, 2017 | Endodontics Middle East

Treatment of 16 with severe curvature

Post a comment by Dr. Justin Dinley, UK

The patient presented with a continuous dull ache, tenderness to percussion and apical palpation. There was no response to vitality testing. The 16 was a NWSI requiring post treatment cuspal coverage. The diagnosis was acute apical periodontitis.

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Dr. Justin Dinley Dr. Justin Dinley

The patient was anesthetised with a buccal infiltration of Lignospan (2% lidocaine hydrochloride, adrenaline 1:80000) and palatal infiltration from the numb buccal aspect. The 16 had Caulking placed around the gingival margin and rubber dam and a clamp placed to allow for an aseptic technique. It is an essential component in an aseptic endodontic technique in which its benefits far out weigh its disadvantages (Ahmad, A. 2009)

Access was achieved with a tapered 554 and an EndoZ safe end cutting TTungsten carbidebur. On access there was suppuration of pus from the palatal canal, however the buccal canals were vital and hyperaemic. The access chamber was cleaned with 2%(5.25%) Naocl and ultrasonic instrumentation prior to any access into the canals from the coronal portion of the tooth. A 35/08 race instrument was used to minimally to coronally the canal orifices, additional access was achieved with a ETBD ball ended diamond coated ultrasonic tip Satalec. Initially the mesial canals were scouted with size .06, .08, and .10 k-flex handfilies (Dentsply Maillefer) to confirm the degree of curvature (Schneider 1971)

Conventional ISO 10 and 15 flex-o-files were used to scout the palatal and disto buccal canals prior to obtaining a zero reading with an electronic length measuring device (Root ZX Morita Inc. R)

The Radiograph showed an approximate curvature of 90° with a larger radius in the MB1 and a smaller radius signifying a more acute curvature in the MB2.

Root canal curvature is measured according to Schneider 1971 and classified as mild <5°, moderate 10-25° and severe >25°. This paper however did not discuss the radius of the curvature as the smaller the radius the higher the risk of cyclic fatigue (Pruett 1997) The square of the diameter, doubles the amount of cyclic fatigue, implying that as the taper increases from. .04 to .06 there is a six fold increase in the risk of cyclic fatigue. Cyclic fatigue of files is determined by the cross sections area, taper, degree of curvature and most importantly the radius of the curvature (Ugur 2007).

Glide path provision was achieved with an FKG 02/10 Scout RaCe file running at 900rpm. The .02 taper and triangular cross section, alternating cutting edges to prevent a screwing in effect, make the file highly flexible, while electroplating reduces the effects of cyclic fatigue (Lopes et al, 2010). Although cyclic fatigue for the scout file maybe higher than that of Pathfiles (Dentsply), results for angular deflection favour the scout files for the advancement with severe curvatures (Lopes et al, 2012).

The scout race file was placed in contact with the EAL to allow for a guide as to the canal length. This is a safe technique as the ISO 10 file will not “Blow out” the apical constriction, as it is narrower than the stated average for a molar of around ISO 30 (El Ayouti, 2014) and potentially wider in individuals under the age of 30.

With the exception of the mesial canals, the 16 was shaped with a modified Race protocol of 25/02, 25/04 and a final file of 35/04. There is a 70% increase in the amount of irrigant than can be placed in the apical 3mm if the ISO is increased from a 25-35 (Trope 2010, Card 2002, McGurkin-Smith 2005) while Khademi et al, 2005 found that the minimal apical size for effective irrigation was ISO 30 and above.

The mesial canals were again shaped and cleaned to a size 35/04 with a differing protocol. Race Scout files were used at 900 rpm in sequence from 10/02, 15/02, 25/02 and 35/02 (BR4C file) with continued use of 2% NaOCL, due to the .02 constant taper being flexible than the conventional systems that may involve a multitude of tapers to clean differing portions of the canals.

The final preparation size was a constant 35/04 tapered instrument.

Cleaning was achieved with a combination 2% NaOCL and Passive ultrasonic irrigation for a minimum of 3 x 20 seconds per canal. The effect of cavitation and acoustic microstreaming has been found to be more effective than syringe irrigation (Gu et al, 2009.,Van de Sluis et al, 2010).

With NaOCL in situ a working length periapical radiograph was taken to assess the position of the working length. This is mainly to rule out over extension and potential reduced outcome, as radiographic apex is found to be on average at least 0.9mm from the position of the apical constriction and this can increase with age due to cementum deposition up to 2-3mm. (El Ayouti et al, 2014).

Constant 04 taper paper point were used to dry the canals and assess for any residual moisture in the canals which may indicate a period of dressing the tooth prior to obturation.

TotalFill bioceramic sealer was placed into each canal, and vibrated to working length with Endoacticvator to spread the sealer and to prevent an apical air lock which could prevent seating of the bioceramic impregnated gutta percha single cone. Bioceramic sealer has been found to be biocompatible, antibacterial, expand (by 0.02%), seal as effectively as MTA and also cause deposition of apatite into the dentinal tubules. The apical 4mm was then coated in sealer and place gently into the canals, seared coronally with SystemB and down packed to create a seal at the orifice level to prevent washout of the sealer.

The combination of bioceramic sealer and bioceramic impregnated cones has been found to make root treated teeth more resistant to fracture in comparison to AH plus and gutta percha, potentially due to the formation of a tertiary monoblock (Ghoneim et al, 2014), with fracture resistance being almost that of untreated roots.

Coronal restoration is an essential part of obturation (Ray and Trope, 1995. Gillen et al, 2011)

The access cavity was etched, scrubbed with 2% CHX to reduce failure of the hybrid layer due to production of matrix-metaloproteases (MMP) (Carrilho et al, 2007) and then primed and bonded. The cavity was restored with incremental composite. A final treatment letter was sent back to the referring dentist for the provision of a full cuspal coverage restoration.

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