Marcos Cesar Pimenta de Araújo

Histological evaluation of the effectiveness of five instrumentation techniques for cleaning the apical third of root canals

The efficacy of five instrumentation techniques for cleaning the apical third of curved root canals was assessed by histological examination. Mesial root canals of freshly extracted human mandibular molars were prepared by the following instrumentation methods: step-back technique using stainless steel files; step-back technique using nickel-titanium files; ultrasonic technique; balanced force technique; and Canal Master U technique and instruments. The apical portion of the root was histologically processed, and cross-sections were examined for remaining soft tissue, predentin, and debris. The results showed no significant differences among the techniques. Although the five instrumentation methods were effective in removal of major amounts of tissue from the canals, none totally debrided the entire root canal system, especially when variations in the internal anatomy were present.

Postobturation pain and associated factors in adolescent patients undergoing one- and two-visit root canal treatment

OBJECTIVES This prospective study evaluated the frequency and intensity of postobturation pain and associated factors in adolescents undergoing one- and two-visit root canal treatment. METHODS 121 patients aged 11-18 years presenting with molars with pulp necrosis were assigned randomly into two treatment groups: one- and two-visit (including interappointment dressing with calcium hydroxide paste). The canals of all teeth were prepared using a preflaring (2/3 middle-cervical) and step-back (1/3 apical) preparation techniques and filled with laterally compacted gutta-percha and sealer. Postobturation pain was recorded on a visual analogue scale (VAS) of 0-5. Data were statistically analyzed using multivariate logistic regression. RESULTS The frequencies of postobturation pain were 10.5% (6/57) in the one-visit group and 23.0% (14/61) in the two-visit group. There were no statistically significant differences between the groups (p=0.07). The intensity of the pain was similar in both groups, particularly flare-ups, with a prevalence of 1.75% in the one-visit group and 1.65% in the two-visit group. Postobturation pain was significantly associated with the presence of preoperative pain (p=0.04; OR=3.54; CI 95%=1.02-12.30) and a positive culture at the time of obturation (p=0.00; OR=9.43; CI 95%=2.93-30.35). CONCLUSIONS Postobturation pain was more present in the two-visit group, but was not statistically significant. The intensity of postobturation pain was similar. Effective microbiological control and the presence of preoperative pain may influence the postobturation pain in adolescents.

Influence of electrochemical polishing on the mechanical properties of K3 nickel-titanium rotary instruments.

Instrument fracture is a serious concern in endodontic treatment. Several studies have evaluated the influence of various factors on the fracture of nickel-titanium endodontic rotary instruments. The present study analyzes the influence of electrochemical polishing on flexural fatigue and torsional properties of K3 nickel-titanium endodontic rotary instruments. New files and polished files were tested for flexural fatigue and for resistance to fracture by twisting. The t test was used to compare the groups for number of cycles, angle of rotation, and maximum torque necessary to fracture. No statistical difference existed between these groups. Scanning electron microscopy analysis showed no significant differences caused by electrochemical polishing between these groups. These results suggest that electrochemical polishing has no influence on resistance to fracture of K3 rotary instruments.

Dissolution of Nickel-Titanium Endodontic Files via an Electrochemical Process: A New Concept for Future Retrieval of Fractured Files in Root Canals

INTRODUCTION The retrieval of fractured instruments from root canals has been largely reported in the literature. However, a less complex retrieval method that causes minimum damage to the dental structures is needed. The aim of this article is to introduce a new concept of retrieval of fractured instruments from root canals based on an electrochemical process. METHODS Current register tests were used to evaluate the dissolution process of 25.04 nickel-titanium (NiTi) K3 rotary files. A constant anodic potential was applied to the NiTi files, whereas the Potentiostat registered the anodic current. After the tests, all files were observed by using an optical microscope. RESULTS The current attained initial values of approximately 55 mA that declined during the entire test. A good reproducibility of results was observed. The optical microscopy analysis evidenced a progressive consumption of the files with increasing polarization time. CONCLUSIONS The results presented here show that the concept of fractured file retrieval by an electrochemical process is feasible. This concept resulted in a consistent basis for the development of a method to remove fractured instruments from root canals.

A Comparative Study on the Frequency, Location, and Direction of Accessory Canals Filled With the Hydraulic Vertical Condensation and Continuous Wave of Condensation Techniques

The present study compared the frequency, location, and direction of accessory canals filled with two different filling techniques. Sixty-four mandibular first molars were accessed, prepared, and divided into two groups of 32 teeth each. The teeth from group A and group B were filled using the hydraulic vertical condensation technique and the continuous wave of condensation technique, respectively. The specimens were then decalcified, dehydrated, rendered transparent, and analyzed by three independent evaluators. There was no significant difference (t test, p < 0.05) between the two groups in relation to the total number of filled ramifications. Moreover, there was no significant difference among the three thirds of the roots in relation to the number of filled ramifications (analysis of variance, p < 0.05). The filled ramifications were more frequently detected toward lingual, buccal, distal-lingual, and distal-buccal directions. It was concluded that the two filling techniques are not different in relation to the frequency, location, and direction of the ramifications filled.

An initial investigation of the electrochemical dissolution of fragments of nickel-titanium endodontic files.

INTRODUCTION A recent study presented the concept of an electrochemical-induced dissolution technique of fractured instruments. The purpose of this study was to test the ability to dissolve embedded fragments of K3 nickel-titanium (NiTi) files. The surface of the fragment exposed to the electrolytic solution was the main parameter evaluated as an interfering factor on the dissolution process. METHODS Three types of K3 NiTi 30.06 file fragments were produced, resulting in different exposed cross-section areas. Anodic current was recorded and used as a reference to evaluate the dissolution process of the fragments. Analysis of variance (P < .05) was used to compare the total electrical charge obtained from current versus time records among the fragments of the 3 groups. Radiographic analysis was carried out before and after the tests to observe the extension of dissolution achieved. RESULTS The total electrical charge values generated during the tests evidence a statistical difference among the 3 groups of fragments (analysis of variance, P < .05). The larger is the diameter of the exposed surface cross section, the higher is the total value of electrical charge. The radiographic images obtained before and after the tests showed a significant reduction of the fragment length as a result of the polarization imposed. CONCLUSIONS The results presented here showed that it is possible to obtain a significant dissolution of K3 NiTi endodontic instrument fragments. The diameter of the surface of fragment exposed to the medium affects the current levels used to promote the dissolution.

Electromagnetic interference of endodontic equipments with cardiovascular implantable electronic device

OBJECTIVES Assess the electromagnetic interference (EMI) of endodontic equipment with cardiovascular implantable electronic devices (CIEDs) and related factors. METHODS The laser device, electronic apex locators (EAL), optical microscope, endodontic rotary motors, gutta-percha heat carrier (GH), gutta-percha gun and ultrasonic device were tested next to CIEDs (Medtronic and Biotronik) with varied sensitivity settings and distances. CIEDs were immersed in a saline solution to simulate the electrical resistence of the human body. The endodontic equipment was tested in both horizontal and vertical positions in relation to the components of the CIED. The tests were performed on a dental chair in order to assess the cumulative effect of electromagnetic fields. RESULTS It was found no EMI with the Biotronik pacemaker. EALs caused EMI with Medtronic PM at a 2 cm distance, with the NSK(®) EAL also affecting the Medtronic defibrillator. GH caused EMI at 2 cm and 5 cm from the Medtronic defibrillator. EMI occurred when devices were horizontally positioned to the CIED. In the majority of the cases, EMI occurred when the pacemaker was set to maximum sensitivity. There was cumulative effect of electromagnetic fields between GH and dental chair. CONCLUSIONS EALs and GH caused EMI which ranged according to type and sensitivity setting of the CIEDs and the distance. However, no endodontic equipment caused permanent damage to the CIED. The use of GH caused a cumulative effect of electromagnetic fields. It suggests that during the treatment of patients with CIEDs, only the necessary equipments should be kept turned on. CLINICAL RELEVANCE Patients with CIEDs may be subject to EMI from electronic equipment used in dental offices, as they remain turned on throughout the treatment. This is the first article assessing the cumulative effect of electromagnetic fields.

Postoperative pain and associated factors in adolescent patients undergoing two-visit root canal therapy.

This prospective study investigated the frequency and intensity of postoperative pain and identified associated factors in adolescents undergoing two-visit root canal therapy. Sixty-four patients aged 11 to 18 years old presenting with molars with pulp necrosis were assigned consecutively to two visits (plus an interappointment dressing using calcium-hydroxide paste). Pain intensity was recorded on a visual analogue scale (VAS) of 0-5. Data were analysed using multivariate logistic regression. The frequency of postoperative pain was 32.8% (21/64), with intensities of VAS 1 and VAS 2 in 81%, VAS 3 in 14.3% and VAS 4 in 4.7% of the 21 cases in which it was experienced. Spontaneous preoperative pain (odds ratio (OR) = 6.60; 95% confidence interval (CI) = 1.61-26.97; P = 0.009) and absence of apical perodontitis (OR = 5.65; 95% CI = 1.34-23.87; P = 0.01) were associated with postoperative pain. The frequency of postoperative pain was high, but the intensity, in general, was low, including flare-ups. The presence of spontaneous preoperative pain and absence of apical periodontitis increase the probability of suffering from postoperative pain.

Influence of Heat Treatment of Nickel-Titanium Rotary Endodontic Instruments on Apical Preparation: A Micro-Computed Tomographic Study

INTRODUCTION The aim of this study was to make a 3-dimensional comparison of the canal transportation and changes in apical geometry using micro-computed tomographic imaging after canal preparation with K3 (SybronEndo, Orange, CA) and K3XF (SybronEndo) file systems. METHODS Twenty-eight mandibular molars were randomly divided into 2 groups according to the rotary system used in instrumentation: K3 or K3XF. The specimens were scanned by micro-computed tomographic imaging before and after instrumentation. Images before and after instrumentation from each group were compared with regard to canal volume, surface area, and structure model index (SMI) (paired t test, P < .05). After instrumentation, the canals from each group were compared regarding the changes in volume, surface area, SMI, and canal transportation in the last 4 apical mm (t test, P < .05). RESULTS Instrumentation with the 2 rotary systems significantly changed the canal volume, surface area, and SMI (P < .05). There were no significant differences between instrument types concerning these parameters (P > .05). There were no significant differences between the 2 groups with regard to canal transportation in the last 4 apical mm (P > .05). CONCLUSIONS Both rotary systems showed adequate canal preparations with reduced values of canal transportation. Heat treatment did not influence changes in root canal geometry in the apical region.

Electromagnetic interference of dental equipment with implantable cardioverter defibrillators

Abstract Objective: Implantable cardioverter defibrillators (ICDs) are subject to electromagnetic interference (EMI). The aim of this study was to assess both the EMI of dental equipments with ICDs and related factors. Materials and methods: High- and low-speed handpieces, an electric toothbrush, an implant motor and two types of ultrasonic devices were tested next to an ICD with different sensitivity settings. The ICD was immersed in a saline solution with electrical resistance of 400–800 ohms to simulate the resistance of the human body. The dental equipments were tested in both horizontal (0°) and vertical (90°) positions in relation to the components of the ICD. The tests were performed with a container containing saline solution, which was placed on a dental chair in order to assess the cumulative effect of electromagnetic fields. Results: The dental chair, high- and low-speed handpieces, electric toothbrush, implant motor and ultrasonic devices caused no EMI with the ICD, irrespective of the program set-up or positioning. No cumulative effect of electromagnetic fields was verified. Conclusions: The results of this study suggest that the devices tested are safe for use in patients with an ICD.