STATISTICAL ESTIMATION OF TEETH LENGHT USING CROWN DIMENSIONS: A NEW METHOD TO DETERMINE ROOT CANAL LENGHT

Objectives: Introduction: Teeth length (TL) determination is important to clinicians that perform procedures within root canal system (RCS) such as endodontic treatments as well as post placing. In endodontics, TL may be used to determine working length (WL). There are methods to determine WL based on using radiographs and/or apex locators (AL). However, those methods have not unquestionable reliability, and there are patients that cannot undergo to these procedures. Here raises the need of developing a reliable method, without contraindications, to obtain TL and WL.
Objective: To determine a multiple linear regression model (MLR) to estimate TL and WL using teeth crown dimensions (TCD).
Methods: Methods: Were evaluated 92 extracted teeth, 49 maxillary seconds premolars and 43 mandibular seconds premolars. The teeth were selected according to defined inclusion and exclusion criteria. The response variable (RV) was TL measured using an electronic digital caliper (DC) RedLine®. Predictor variables (PV) were proposed using combinations of TCD made with DC. Was calculated the linear correlation coefficient using RV and each PV to determine which PV would be used in MLR. Were proposed 23 MLRs, and were fitted using the least square method. Evaluation and comparison of models was performed using methods proposed by Salas et al. (2002).
Results: Results: The MLR Y=β0+β1(X1*X3)+β2arc+ei (X1: crown length , X3: crown width vestibulo-lingual, arc: dental arch) can estimate TL using TCD. Results of TL obtained with this model were compared to TL measured using DC to each tooth. There were not statistically significant differences comparing both methods (p>0.05, paired samples t-test).
Conclusions: Conclusions: TCD can be used to modeling TL with an acceptable statistical error. Proposed MLR may be an option to determine TL and/or WL in patients that cannot undergo to Radiographs and/or AL procedures as well as in emergency pulpectomy procedures where x-ray and/or AL are not available.