Comparative Study of 6 Rotary Nickel-Titanium Systems and Hand Instrumentation for Root Canal Preparation in Severely Curved Root Canals of Extracted Teeth

IntroductionSome improvements have been developed with new generations of nickel-titanium (NiTi) rotary instruments that led to their successful and extensive application in clinical practice. The purpose of this in vitro study was to compare the root canal preparations performed by using GT Series X and Twisted File systems produced by innovative manufacturing process with Revo-S, RaCe, Mtwo, and ProTaper Universal systems manufactured directly from conventional nitinol and with stainless steel K-Flexofile instruments.MethodsThe mesiobuccal root canals of 140 maxillary first permanent molars that had between 30°–40° curvature angle and 4- to 9-mm curvature radius of the root canal were used. After root canal preparations made by using GT Series X, Twisted File, Revo-S, RaCe, Mtwo, and ProTaper Universal NiTi rotary systems and stainless steel K-Flexofile instruments, transportation occurred in the root canal, and alteration of working length (WL) was assessed by using a modified double-digital radiographic technique. The data were compared by the post hoc Tukey honestly significant difference test.ResultsNiTi rotary systems caused less canal transportation and alteration of WL than K-Flexofile instruments (P < .05). There was no significant difference between NiTi rotary system groups at any levels (P > .05) except 2.5 mm from the WL. At this level ProTaper Universal system caused significant canal transportation (P < .05).ConclusionsGT Series X and Twisted File rotary systems produced with innovative process were concluded to shape the curved canals to result in minimal canal transportation, similar to Revo-S, RaCe, Mtwo, and ProTaper Universal rotary systems manufactured by traditional methods.     

Prefrontal gamma oscillations reflect ongoing pain intensity in chronic back pain patients

Chronic pain is a major health care issue characterized by ongoing pain and a variety of sensory, cognitive, and affective abnormalities. The neural basis of chronic pain is still not completely understood. Previous work has implicated prefrontal brain areas in chronic pain. Furthermore, prefrontal neuronal oscillations at gamma frequencies (60–90 Hz) have been shown to reflect the perceived intensity of longer lasting experimental pain in healthy human participants. In contrast, noxious stimulus intensity has been related to alpha (8–13 Hz) and beta (14–29 Hz) oscillations in sensorimotor areas. However, it is not fully understood how the intensity of ongoing pain as the key symptom of chronic pain is represented in the human brain. Here, we asked 31 chronic back pain patients to continuously rate their ongoing pain while simultaneously recording electroencephalography (EEG). Time–frequency analyses revealed a positive association between ongoing pain intensity and prefrontal beta and gamma oscillations. No association was found between pain and alpha or beta oscillations in sensorimotor areas. These findings indicate that ongoing pain as the key symptom of chronic pain is reflected by neuronal oscillations implicated in the subjective perception of longer lasting pain rather than by neuronal oscillations related to the processing of objective nociceptive input. The findings, thus, support a dissociation of pain intensity from nociceptive processing in chronic back pain patients. Furthermore, although possible confounds by muscle activity have to be taken into account, they might be useful for defining a neurophysiological marker of ongoing pain in the human brain.     

Atypical presentation in Rasmussen encephalitis: delayed late-onset periodic epileptic spasms

A five-and-a-half-year-old girl started experiencing progressive left hemiparesis at age two and a half years. At age five years and four months she started presenting clusters of asymmetric periodic epileptic spasms with no hypsarrhythmia. The ictal EEG showed periodic, constant and stereotyped complexes. Serial brain imaging revealed progressive atrophy of the right hemisphere with increased T2 signal on MRI. She underwent a right hemispherotomy, and histological examination showed signs of inflammation and features of focal cortical dysplasia (FCD). She has been seizure-free for 16 months. This case is unique in the following aspects: the presence of typical Rasmussen encephalitis features of progressive unilateral brain involvement without seizures, a delay of almost three years prior to seizure onset; an atypical seizure type presentation with periodic epileptic spasms and the presence of FCD associated with inflammatory changes. [Published with video sequences].     

An adult case of temporomandibular joint osteoarthritis treated with splint therapy and the subsequent orthodontic occlusal reconstruction

Herein we report treatment for a 19-year-old female patient with severe osteoarthritis of the temporomandibular joint. The patient had severe open bite with a Class II molar relationship. She had limited mouth opening and pain. Clinical examination and magnetic resonance imaging revealed that she had anterior disc displacement without reduction. By splint therapy, limited mouth opening and pain was eliminated, but an anterior open bite developed after the treatment. By orthodontic treatment, an acceptable occlusion was achieved with a Class I molar relationship.     

A comparison of the efficacy of conventional and new retreatment instruments to remove gutta‐percha in curved root canals: an ex vivo study

Aim To compare the efficacy of conventional and new retreatment instruments when removing gutta‐percha root fillings in curved root canals. Methodology A total of 56 curved molar roots were instrumented with ProFile instruments and filled using system B and Obtura II. The root fillings were removed with manual K‐files and Hedström files (Dentsply Maillefer), ProFile (Dentsply Maillefer), R‐Endo (Micro–Mega) or ProTaper Universal retreatment files (Dentsply Maillefer). Eucalyptol was used as a solvent with all techniques. Bucco‐lingual and proximal radiographs of the roots were exposed and the percentage area of the remaining material was calculated by dividing the area of remaining filling material by the area of canal wall. Data were statistically analysed with Kruskal–Wallis and Mann–Whitney U tests (P = 0.05). Results None of the techniques completely removed the root filling materials. No significant differences were found amongst the coronal, middle and apical thirds in both radiographic projections (P > 0.05). In the bucco‐lingual direction, the remaining filling material was significantly less following manual instrumentation than R‐Endo and ProTaper instrumentation (P < 0.05). In the proximal view, it was significantly less following manual and ProFile instrumentation than R‐Endo (P < 0.05). Complete removal of filling material occurred only in three specimens (with manual instruments). Manual instruments were significantly faster than R‐Endo and ProFile (P < 0.05). More procedural errors (five fractured instruments and two perforation) were noted when using ProTaper (P < 0.05). Conclusions In this laboratory study in curved molar roots, ProTaper Retreatment and R‐Endo instruments were less effective in removing filling material from canal walls than manual and ProFile instruments.