# Plywood Jig--A New Technique for Root Canal Curvature Measurement
###### Abstract  
The successful outcome of endodontic treatment is dependent on complete cleaning, shaping as well as three dimensional obturation of the root canal system. A conventional radiograph is a two-dimensional replication of a three-dimensional object and does not provide any conclusive evidence for canal curvatures. An accurate knowledge of the tooth anatomy and curvature is essential to avoid procedural errors. 100 freshly extracted human teeth were used in this study. Digital images were obtained using the plywood JIG and Schneider's technique. These images were analyzed using the VixWin Pro digital image analyzing software (Gendex system). Statistical analysis was done using paired \(t\) test. The canal curvature average values measured using Jig method and [PERSON] method for mandibular teeth are 28.23\({}^{\circ}\) (\(\pm\)9.96) and 22.07\({}^{\circ}\) (\(\pm\)9.46) respectively. The smallest/largest curvature angles measured using Jig method and [PERSON] technique are 12/52\({}^{\circ}\) and 8/44\({}^{\circ}\) respectively. Canal curvature average values measured using Jig method and [PERSON] method for maxillary teeth were 23.40\({}^{\circ}\) (\(\pm\)11.36) and 19.23\({}^{\circ}\) (\(\pm\)11.94) respectively. The smallest/largest average curvature angles measured using Jig method, Schneider technique were 9/70\({}^{\circ}\) and 5/72\({}^{\circ}\) respectively. The values of the canal curvature angle obtained during routine radiographs in clinics have lower curvature angle and higher radius values as compared to the values obtained by this innovative JIG technique. Therefore, a clinician should always keep in mind the difference while measuring the curvature angle on radiographs during root canal treatment.  
endodontic; plywood; root canal curvature; instrumentation +
Footnote †: journal: MedicalThe root canal anatomy differs among different ethnic groups and sub-populations [2]. So, it is essential for the dentist to know about the anatomic variabilities in his practicing population. Few authors have previously tried to analyze and measure the degree of curvature present in root canals of various teeth. [PERSON] was one of the first researchers to provide a detailed analysis and report on determination of canal curvatures from clinical radiographs [3; 4]. The drawback was that he did not investigate curvatures seen from the proximal view. But in truth, curvatures are present not only in a mesio-distal direction, as seen in a clinical radiograph, but also in a bucco-lingual direction. [PERSON] and [PERSON] used a roentgenographic method to analyze and evaluate root canals from both the proximal as well as the clinical views [5]. Three-dimensional imaging techniques can give the exact picture of root canal anatomy like MRI and Computed Tomography, but which are expensive and tedious and will not be applicable to clinical practice [6]. Research has been conducted using different techniques to measure the canal curvatures of the mesio-buccal root of the maxillary first molar and mesial root of the mandibular first molar because of the increase in the frequency of performing endodontic treatment in these teeth and the presence of innumerable number of anomalies coupled with variable amount of canal curvatures [7; 8]. Canal curvature is known to be influenced during shaping by the different file system or by the pressure on the canal walls, a research conducted evaluated the pressure distribution against the root canal wall by using finite element analysis (FEA), wherein authors concluded that the instrument shaping ability can be predicted by using FEA as a virtual tool [9]. Here we come with a new, simple, inexpensive and accurate method to measure the canal curvature angle, radius and peak height of curvature in an in vitro situation and the accuracy was compared with the standard Schneider's canal curvature measurement.