A review of the latest developments in rotary NiTi technology and root canal preparation.

The introduction of nickel-titanium (NiTi) mechanical instruments dramatically changed clinical endodontics over the last few decades. Before NiTi, it was necessary to use more instruments to create an ideal root canal shape, and many approaches, sequences and techniques were developed over the years. Recently, NiTi endodontic instruments have undergone a series of changes brought about by modifications in design, surface treatments, and thermal treatments to improve their root canal preparation outcomes and reduce associated canal preparation risks during root canal treatment. Heat treatment is one of the most fundamental approaches to improving the fatigue resistance and flexibility of NiTi endodontic instruments. In addition, new kinematics have been developed to offer greater safety and efficiency. This narrative review describes the general properties and manufacturing of NiTi instruments, and the mechanical system evolution of NiTi instruments.

Evaluation of smear layer and debris removal by stepwise intraoperative activation (SIA) of sodium hypochlorite.

OBJECTIVES: To evaluate the efficacy of a stepwise intraoperative activation (SIA) of irrigants during and after the instrumentation compared with that of a conventional activation (CA) performed only after the instrumentation to remove smear layer and debris using different activation devices. MATERIALS AND METHODS: A total of 70 single-rooted teeth were divided into a control group (no activation, n = 10) and two different experimental groups according to the irrigant activation protocol used: group 1 (CA), in which sodium hypochlorite was activated only after the use of the last mechanical file, and group 2 (SIA), in which activation was performed during and after the instrumentation. The two groups were divided into 3 subgroups according to the activation device used (n = 10): passive ultrasonic irrigation (PUI, subgroup a), EndoActivator (EA, subgroup b), and EDDY (subgroup c). The roots were split longitudinally and observed using scanning electron microscopy (SEM) to evaluate the presence of debris and smear layer, and the results were statistically analyzed. RESULTS: All activation protocols and devices were more effective than control group in removing smear layer and debris from all root canal thirds (P < 0.05), except for CA-EA (group 1b) in the apical third. In the apical third, SIA was found to be more effective than CA (P < 0.05) to remove smear layer and residual debris when PUI was used, to remove the smear layer when EA was used (P < 0.05), and to remove residual debris when EDDY was used (P < 0.05). PUI and EDDY removed statistically more smear layer and debris than EA in the apical third (P < 0.05). CONCLUSIONS: The SIA technique improved the smear layer and debris removal from the apical third and debris removal from the coronal third, and PUI and EDDY were more effective than EA in the apical third. CLINICAL RELEVANCE: The stepwise intraoperative activation (SIA) technique may increase smear layer and debris removal.

Short lingual frenum in infants, children and adolescents. Part 1: Breastfeeding and gastroesophageal reflux disease improvement after tethered oral tissues release.

AIM: This study aimed to determine the impact of laser surgical tongue-tie, lip-tie, buccal tie release on breastfeeding and Gastroesophageal Reflux Disease (GERD) in a prospective cohort study conducted from June 2019 to June 2020 in a private general dental practice. MATERIALS AND METHODS: Preoperative, one-week and one-month postoperative surveys were completed, consisting of Visual Analogue Scale (VAS) for nipple pain severity, Breastfeeding Self-Efficacy Scale Short Form (BSES-SF), and the Revised Infant Gastroesophageal Reflux Questionnaire (I-GERQ-R). All study participants were breastfeeding dyads (0-12 weeks of age) with untreated ankyloglossia and/or tethered maxillary/buccal frena. The laser surgery was completed using 2 different near- infrared diode lasers with 300µm diameter fibre: a 980 nm wavelength diode laser (Lasotronix Smart Pro, Piaseczno Poland) was used at 4.0 W, gated with 100 µs t/on and 100 µs t/off, and a 1470 nm wavelength diode laser (Pioon S1, Wuhan Pioon Tech Co Ltd., Wuhan, China), used at 3.5W, gated with 50 ms t/on and 50 ms t/off. RESULTS: Statistically significant improvement was noted in VAS, I-GERQ-R and BSES-SF comparing preoperative scores to both one-week and one-month scores. The study had 132 breastfeeding dyads enrolled. Posterior tongue-tie was noted in 71% of this cohort. CONCLUSION: This study confirms the need for functional assessment of tongue and lip movement for this significantly affected cohort. Laser surgical release (frenotomy) of tongue-tie, lip-tie, buccal-tie resulted in significant improvement in breastfeeding outcomes. These improvements (VAS, I-GERQ-R and BSES-SF) in breastfeeding outcomes were found for cohorts of the classically recognised anterior tongue-tie and the less obvious (without functional assessment) submucosal tongue-tie were found.

Micro-CT evaluation of two different root canal filling techniques.

OBJECTIVE: The aim of this study was to compare the frequency and volume of voids in root canals obturated with two different filling techniques using micro-computed tomography (micro-CT). MATERIALS AND METHODS: Forty single-rooted permanent teeth were selected and decoronated. The roots were instrumented with WaveOne (Dentsply Maillefer, Ballaigues, Switzerland) to a large size until working length and irrigated with 5.25% sodium hypochlorite and 17% EDTA. Then, the samples were filled using a single-cone (n = 20) or the GuttaCore technique (n = 20). The presence and volume (mm3) of voids (internal, external, and combined) was calculated in the coronal, medium, and apical thirds using micro-CT (SkyScan 1072; SkyScan, Kartuizersweg, Belgium). Statistical analyses were performed using the χ2-test and Kruskal-Wallis tests (p<0.05). RESULTS: The frequency and total volume of voids in the middle third and the external voids in the coronal third were statistically significant (p<0.05). Within the same group, both techniques (single-cone and Guttacore) showed statistically significant differences in external and internal voids (p<0.05). CONCLUSIONS: The GuttaCore technique showed better results in the coronal and medium thirds than the single-cone technique. Our results showed that the single-cone and GuttaCore techniques were comparable in the apical third (p>0.05).

Influence of simulated apical resorption following orthodontic treatment on working length determination: an in vitro study.

AIM: External apical root resorption (EARR) is a common complication that may occur during and after orthodontic treatment. In case of need of endodontic therapy for a tooth with EARR, it has not been clarified yet which benefits can be derived by the use of electronic apex locators (EALs). The present study aimed to assess the accuracy of EALs on extracted teeth before and after simulation of EARR subsequent to orthodontic treatment. MATERIALS AND METHODS: Standard access cavities were prepared on 64 single-rooted teeth. After working length (CWL) determination, specimens were embedded in an alginate mass, connected to two EALs (Apit, Osada, Tokyo, Japan; Root ZX, Morita Corp., Tokyo, Japan) and the electronic working length (EWL) was measured. The apical portion of the specimens was then modified to simulate EARR, and the EWL was determined again. The discrepancy between CWL and EWL was regarded as statistical unit. Collected data underwent statistical analysis by means of non-parametric tests (p < 0.05). RESULTS: Within a range of ± 0.5 and ± 1.0 mm from CWL, the accuracies were 79.7% and 98.4% (Apit/intact tooth); 82.8% and 96.9% (Apit/simulated EARR); 81.3% and 98.4% (Root ZX/intact tooth); 76.6% and 96.9% (Root ZX/simulated EARR). No statistically significant differences in relation to device or apical condition emerged (p > 0.05). CONCLUSION: The two considered EALs showed similar accuracy, which was not affected by the EARR simulation. The use of EALs in the treatment of teeth with EARR following orthodontic treatment may be useful.

In vivo accuracy of three electronic root canal length measurement devices: Dentaport ZX, Raypex 5 and ProPex II.

AIM: To compare in vivo three different electronic root canal length measurement devices: Dentaport ZX, Raypex 5 and ProPex II. METHODOLOGY: Thirty single-rooted permanent teeth scheduled for extraction because of periodontal disease were selected from 10 adult patients (ranging from 45 to 67 years) and divided into three groups of 10 teeth. Before the extraction, an access cavity was prepared and the crown was adjusted to establish a stable reference point for all measurements. The working length in Group 1 was determined using the Dentaport ZX apex locator. A K-file with the largest diameter that could reach the last green bar on the screen was stabilized in the canal using a dual-curable flow resin composite. The same procedure was used for the Raypex 5 (the file reached the last yellow bar) and Propex II (0.0 orange bar) apex locators. The teeth were then extracted and cleared. The distance between the tip of the file and the major foramen was then calculated for each tooth using digital photography according to Axiovision AC software (Carl Zeiss). Positive values were assigned when the file tip passed beyond the major foramen, negative values when the tip was short of the foramen and zero value when the file tip and the foramen coincided. Statistical analysis was performed using the chi-squared test or Fisher's exact test (P ≤ 0.05). RESULTS: Dentaport ZX, Raypex 5 and ProPex ΙΙ produced, respectively, 6, 2 and 4 out of 10 correct measurements, 0, 6 and 5 long measurements and 4, 2, and 1 short measurements. The differences between the three electronic root canal length measurement devices were not significant (P = 0.507). CONCLUSIONS: Under the in vivo conditions of this study, the three electronic root canal length measurement devices were not significantly different in terms of locating the major foramen.

Oral inflammatory process and general health. Part 2: How does the periapical inflammatory process compromise general health?

At present, the focal infection theory still has very controversial aspects. In spite of the great number of studies, there is no evidence that focal infections or even antigenic mimicry are responsible for anything other than sporadic abscesses/infections and possibly rare autoimmune disorders. linflammation of endodontic origin (i.e., apical periodontitis--AP) has not received the same attention as inflammation originating from the periodontium. Endodontics is a microbiological problem, since the bacterial infection is the "prime mover" of pulp (before) and periapical (later) disease. The aims of endodontic treatment have to be considered from a microbiological viewpoint. Considering these problems in this second part of their study, the Authors, after close examination of the virulence of microorganisms and of the host defense, analyze the endodontic infection and microbiological species. They emphasize the possibility of a relationship between periapical inflammatory lesions and bacterial endocarditis in preventing metafocal disease. Bacterial endocarditis deserves special mention because despite involving specialists of two scientific fields, its prophylaxis is almost always assigned to medical practice, and especially, to dentistry. Given the dangers of the disease, antibiotic prophylaxis is both absolutely necessary and can be very effective, and it should be used especially in clinical situations with high risk individuals. However, the ability of antibiotic therapy to prevent or reduce the frequency, magnitude or duration of bacteremia associated with a dental procedure is controversial. Studies should also be undertaken to determine to compare the efficacy of endodontic treatment with alternative therapy such as implants, prosthetic replacements or no treatment other than extraction. To date, these studies have not been carried out, and there is no evidence to support the theory that modern endodontic therapy is not safe and effective.

Oral inflammatory process and general health. Part 1: The focal infection and the oral inflammatory lesion.

A focal infection is a localized or generalized infection caused by the dissemination of microorganisms or toxic products from a focus of infection in various organic districts, including the oral district. In the Part 1 of this two-part review article, after historical signs, the Authors describe the current pathogenic concepts like the "immuno-allergic theory" and the formation of auto-antibodies in human body, contributing to the genesis of autoimmune illnesses sustained by individual reactivity linked to eredo-constitutionality. Some theories suppose a focal origin even for general pathology such as cancer, sarcoidosis, multiple sclerosis, amyotrophic lateral sclerosis, autism, Guillain-Barré syndrome, Pediatric Autoimmune Neuropsychiatric Disorders Associated with Streptococcal infections (PANDAS), Tourette's syndrome, myasthenia gravis, polycystic kidney disease, obesity, Alzheimer's disease and diabetes mellitus. Laboratory analyses (leucocytic formula, protein electrophoresis, C-reactive protein, REUMA test VES, TAS, etc.) are suggestive of the presence of an inflammatory process or of the presence of an aspecific answer to an inflammatory situation. The DNA-Polymerase Chain Reaction method (PCR) is fundamental for the diagnosis of bacterial and viral infections, particularly for those that have non-culturable microorganisms or in cases where are present but in extremely small number in the sample to be analyzed. A positive result confirms the diagnosis, but negative result is not indicator of the absence of illness. Even for oral inflammatory lesions, different basic mechanisms concerning the possible association with systemic diseases exist. They concern local spread, metastatic spread or immunologic cross-reactivity. In this case we assume that most of the ailments come from dental or periodontal foci, as in the bacterial endocarditis, but instead of considering them as possible pathogenetic mechanism of an immune nature, we consider them as originated by the body's response to the presence of bacterial antigens through the formation of specific antibodies. Much researche, sometimes contrasting, has evaluated periodontal pathogens in atheromatous plaques isolated from patients with chronic periodontitis. Oral inflammatory lesions have been shown unequivocally to contribute to elevated systemic inflammatory responses. In some researches intensive periodontal therapy showed a significant reduction of lymphocyte formula, of CRP levels, of interleukin-6 (IL-6) and of LDL cholesterol after two months.