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ePaper created 2017-03-17, 11:08:54 | version 1.38.0
E v a l u a t i o n o f s u r g i c a l d i f f i c u l t y o f e x t r a c t i o n Introduction A number of classification systems have been proposed for estimating the surgical dificulty of impacted mandibular third molar extraction, based on preoperative assessment of panoram- ic radiographs. The traditional classifications are those of Pell and Gregory1 and Winter,2 based on the depth of the third molar, the relation to the mandibular ramus and the anatomical posi- tion in relation to the longitudinal axis of the adjacent second molar. Over the years, diferent modifications of these scales have been pro- posed with the aim of improving the prediction of surgical dificulty. In this regard, Pederson proposed a modification of the scale of Pell and Gregory that contemplated an additional factor: the position of the molar.3 Each variable was assigned a score of 1–4 according to its influence upon the difficulty of extraction, and these scores were then summed to yield a final score predicting surgical dificulty: 3–4 (not dificult), 5–7 (moderate dificulty) and 7–10 (great difi- culty). This scale has been widely cited in the oral and maxillofacial surgical literature as an easy way to predict the surgical dificulty of im- pacted mandibular third molar extraction. Cáceres Madroño et al. added further pa- rameters to the scale of Pedersen, such as man- dibular height, distal inclination of the second molar, size and shape of the dental follicle, and development of the roots.4 Peñarrocha et al. in turn summed the scores corresponding to peri- coronal radiolucency, pericoronal space, Win- ter’s distance and coronal area, and subdivided the size and shape of the roots into two separate parameters: the length of the root and the type of root.5 Each variable was scored from 0 to 2, and the individual scores were summed to yield a final surgical dificulty score: 0–5 (not difi- cult), 6–10 (average dificulty) and over 10 (great dificulty). This is one of the scales involving the largest number of parameters, and higher scores have been shown to correspond to longer ostec- tomy times and total surgical times—thereby confirming the eficacy of the classification.5 Another clinical and radiographic scale for predicting the dificulty of third molar extraction was developed by Romero-Ruiz et al., based on the classical parameters with the addition of integrity of the bone and mucosa covering the third molar.6 Minimum surgical dificulty was predicted if the tooth was covered only by mucosa, while maximum dificulty correspond- ed to molars fully covered by bone and mucosa. Predicting the surgical dificulty of impacted mandibular third molar extraction is essential for treatment planning and helps assess profes- sional surgical skill, reduces complications, op- timizes patient preparation, and minimizes post- operative pain and inflammation. The present study describes a radiographic surgical dificulty scale based on a series of para- meters and compares it with ostectomy time, tooth sectioning time, the presence or absence of additional ostectomy, and total surgical time. In addition, actual measurements of the radio- graphic parameters were taken to identify those that had the greatest impact upon surgical dif- ficulty. Materials and methods A retrospective study using panoramic radio- graphs was conducted of patients subjected to surgical extraction of an impacted mandibular third molar in the Department of Stomatology and Maxillofacial Surgery (General University Hospital of Valencia, Valencia, Spain), with re- cording of the following surgical times: ostec- tomy time and tooth sectioning time (in seconds) and total surgical time (in minutes), calculated from the start of the incision to the last suture. A presurgical radiographic scale was developed (Figs. 1-10), based on ten parameters that were recorded by three dental students of the Facul- ty of Medicine and Odontology, University of Valencia, Valencia, Spain, using ImageJ software (64-bit; developed by the U.S. National Insti- tutes of Health, Bethesda, Md.)7, with calcula- tion of the corresponding mean values: inclina- tion of the third molar, inclination of the second molar, pericoronal radiolucency, root radiolucen- cy, root shape, Winter’s distance, distance be- tween the ramus and second molar, width of the third molar, coronal area and root length. Calibration was carried out based on the cal- culation of the distortion of the radiographic measurements versus the real measurements of the third molar, using radiographic measure- ments of the diameter and length of 15 impact- ed mandibular third molars, exported to ImageJ, and caliper measurements obtained after ex- traction of the third molar, respectively. The statistical analysis of these dual measurements (ImageJ and calipers) showed the distortion co- eficient to be 0.11. The final score was obtained by summing the individual scores for each parameter, coded Journal of Oral Science & Rehabilitation Volume 3 | Issue 1/2017 53