الفهرس 
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Abstract
“Endodontics” involves dealing with both the vital and necrotic pulp of the tooth so that patients can keep their natural teeth functioning and with good aesthetics. Although the success of root canal treatment depends on many factors, one of the most important factors is the mechanical preparation of the root canal space. This factor is considered essential as it determines the effectiveness of all subsequent steps. This factor includes several steps: mechanical debridement, creating sufficient space for drug delivery, and preparing the acceptable geometry of the obturation.
The mechanical root canal preparation has evolved over the years -and still is- in order to achieve the best treatment outcomes. These are achieved through the elimination of any causative that might lead to further pain or flare-ups. Amongst these causatives are the RC cleanliness and the apically extruded debris. Hence, securing an adequate mechanical debridement would guarantee a high rate of success.
A crucial factor in affecting the quality of mechanical debridement is the type of file system used. All the file systems on the market vary in their geometry, metallurgy and even the number of files used to achieve an adequate preparation and most of all they vary in their motion used. There are several types of motions used with the engine-driven file systems, the most popular amongst these are the continuous rotation and the reciprocating motion. The latter was developed more recent than the former one in a trial to overcome the drawbacks of the older motion.
To test these claims, the current study aimed at evaluating the apical extrusion, the root cleanliness (in the laboratory), the post-operative pain and the healing of small periapical lesions (clinically) using the iRace (FKG) multiple-file system representing the continuous rotation and the WaveOne Gold (Dentsply) single-file system representing the reciprocating motion. And the null hypothesis adopted by the study was the absence of any significant difference between the tested file systems in all tested parameters.
In the laboratory experiment:
1. Studying the degree of cleanliness of the root canals after completing the preparation in 40 newly extracted lower human molars using the aforementioned rotary files; where the teeth in question were divided into two groups according to the type of files used, with each group including 20 human lower single rooted premolars. After completing the preparation of the root canals and irrigating them with distilled water. Crowns were decoronated, and roots were split vertically. Then, roots were examined at the apical region using a scanning light microscope (SEM). The resulting images were analysed using the Image J program to measure the amount of debris covering the surface, in addition to the use of the Rome score.
The results of this part showed that there was no statistically significant difference between the two file systems. Yet, WaveOne Gold showed better results over the iRace system.
2. Evaluating the apical extrusion using the same number and type of teeth and also the same preparation protocol that was used in the cleanliness testing. Prior to root canal preparation empty Eppendorf tubes were colour coded and weighed and recorded. The apically extruded debris collected during root canal preparation was by the means of a debris collection model following that of the Meyers-Montgomery model. The debris were collected in the previously colour-coded and weighed Eppendorf tubes. This was followed by placing them in the incubator at 70°C for 5 days to dry the extruded debris. After being dried, the tubes were weighed one more time and the difference was calculated to reveal the debris dry weight. The analysed data collected from this experiment showed no statistically significant difference. And, in this experiment, the iRace group showed superior results compared to the WaveOne Gold file system.
For the clinical trial:
Root canal treatment of 45 asymptomatic mandibular molars with a degree of root canal curvature equal to 20o-35o degrees (measured using Schneider technique) and an apical lesion size of less than 5 mm was preformed.
Patients recruited were adults with no history of chronic diseases affecting the bone health nor taking medications that might affect it or affect their pain perception.
Patients were haphazardly divided into two groups, each containing 22 (iRace) and 23 (WaveOne Gold):
After receiving the treatment, the patients were asked to report their pain levels using a combination of the VAS score scale and the Wong-Baker FACES scale altogether with their intake of the prescribed Ibuprofen (only when needed). The reporting intervals were 24h, 48h, 72h, and 7d post-operatively. Analysis of the collected pain data showed no statistically significant difference between the test groups at all time points.
For the healing evaluation, the immediate post-operative X-ray was assessed, and the periapical lesion was measured. This was later compared to follow-ups X-rays at 3-months, 6-months, 9-months and 12-months time points with the help of the digital subtraction radiography using the digital 2D periapical radiographs, Image J and Adobe Photoshop Software. And the overall change percentage in the lesion size was calculated upon comparing the immediate post-operative X-ray to the 12-months follow-up time point. Again, there was no statistically significant difference between the iRace and the WaveOne Gold groups.
It was noticed also that, nor gender nor age had a significant impact on the pain and the healing outcomes in this study.
Within the limitations of the current study, the null hypothesis was accepted supporting the absence of any significant differences between iRace and WaveOne Gold in the aforementioned tested parameters.