Quantative evaluation of apically extruded debris and solution in reciprocal and rotary techniques

A successful endodontic treatment is highly dependent on a correct diagnosis and treatment planning as well as an effective cleaning and shaping and 3-dimensional filling of the root canal system. During root canal treatment, pulp remnants, dentin particles, intracanal debris, microorganisms and irrigating solutions may be inadvertently extruded into periradicular tissues. It has been stated that this phenomenon described as ?apical extrusion? is an inherent occurrence of endodontic treatment and cannot be prevented irrespective of the technique used. The most significant disadvantage associated with apical extrusion is the initiation of an acute inflammatory response and ?inter-appointment flare-ups?, a distressful condition both for the patient and the practitioner. The extent and degree of acute exacerbations vary according to the structure of the root canal content, whether it is infected or not and the virulence of the extruded microorganisms. It has also been shown that even uninfected particles may trigger an acute response by causing a foreign body reaction. Therefore; one of the major responsibilities of a dental practitioner during endodontic treatment is to perform a root canal preparation that minimizes extrusion of debris and irrigants. Various root canal shaping techniques have been launched to the market in recent years. Engine-driven rotary instruments are specifically preferred by dental practitioners due to their capacity to complete the procedures rapidly and effectively. There has been a modification in existing rotary techniques recently and single instruments have been produced that are claimed to complete the root canal shaping procedure using only one instrument. Meanwhile; modifications have also been made in terms of rotational motion and techniques incorporating a reciprocal motion have also been launched into the market. Although the general principle behind these techniques is facilitating the efficacy of root canal shaping, they should be evaluated from multiple perspectives, one of which is debris and liquid extrusion. Therefore; the aim of this study was to comparatively evaluate contemporary reciprocal and rotary techniques (WaveOne, Reciproc, ProTaper and S5) in terms of apical debris and liquid extrusion. One hundred single rooted human teeth with single root canals were included in the study. After dimensional standardization of the experimental teeth and removal of coronal root portions to obtain equal lengths, teeth in Group 1 were enlarged with the step-back technique using K-files and used as control. The experimental groups were treated as follows: Group 2: ProTaper (Dentsply, Maillefer, Switzerland), Group 3: WaveOne (Dentsply, Maillefer, Switzerland), Group 4: Reciproc (VDW, GmbH, München), Group 5: S5 Rotary system (Sendoline, Täby, Sweden). The study design developed by Myers and Montgomery were used with some modifications and the teeth were secured in plastic stoppers fitted on top of collecting vials. The weights of empty tubes were calculated using a precise microbalance and recorded. The collecting vials were filled using physiological saline solution during shaping and the excess liquid during shaping and irrigation were collected in calibrated insulin injectors used to balance internal and external pressures. Following shaping and calculation of extruded liquid, the glass vials were placed in dry air sterilizator and the liquid was evaporated. Later, each vial was weighed again and the weight of the extruded debris was calculated by subtracting the weight of the empty tube from the debris extruded weight. The obtained results were statistically analyzed. Statistical evaluation showed that the extruded liquid by the step-back control group was significantly higher compared to ProTaper and S5, WaveOne and Reciproc groups (p<0.01). No significant difference was observed among other groups in terms of liquid extrusion. In terms of debris extrusion, step-back group was determined to be significantly higher compared to ProTaper and S5 groups whereas extruded debris in the Reciproc group was significantly higher compared to the S5 group (p<0.05) No significant difference was observed among the other groups (p> 0.05). When the relationship between solution and debris extrusion were evaluated separately, no statistically significant difference was observed (p>0.05). In general, hand instruments resulted in higher amount of extrusion specifically in terms of liquid, compared to rotary and reciprocating systems. The step-back technique also resulted in significantly higher amount of debris compared to rotary groups incorporating the usage of multiple instruments. Though the results of the study show a tendency of reciprocating systems to extrude relatively more debris, the existing evidence is not yet satisfactory to draw definite conclusions and further supporting research is necessary to draw more reliable conclusions.