Shaping ability of BioRace, ProTaper NEXT and Genius nickel-titanium instruments in curved canals of mandibular molars: a MicroCT study.

AIM: To evaluate and compare the canal shaping ability of BioRace, ProTaper NEXT and Genius engine-driven nickel-titanium (NiTi) file systems in extracted mandibular first molars using micro-computed tomography (MCT). METHODOLOGY: Sixty mesial root canals of mandibular first molars were randomly divided into three equal groups, according to the instrument system used for root canal preparation (n = 20): BioRace (BR), ProTaper NEXT (PTN) or Genius (GN). Root canals were prepared to the full WL using a crown-down technique up to size 35, .04 taper instruments for BR and GN groups and size 30, .07 taper instruments for the PTN group. MCT was used to scan the specimens before and after canal instrumentation. Changes in dentine volume, the percentage of uninstrumented canal surface and degree of canal transportation were evaluated in the coronal, middle and apical thirds of canals. Data were analysed statistically using one-way analysis of variance and Tuckey's post hoc tests with the significance level set at 5%. RESULTS: There were no significant differences between the three groups in the terms of dentine removed after preparation and determination of the root canal volume, or percentage of uninstrumented canal surface (P > 0.05). No significant differences were found between the systems for canal transportation in any canal third (P > 0.05). CONCLUSIONS: The shaping ability of the BR, PTN and GN NiTi file systems was equally effective. All instrumentation systems prepared curved root canal systems with no evidence of undesirable changes in 3D parameters or significant shaping errors.

Atomic layer deposition of Cu(i) oxide films using Cu(ii) bis(dimethylamino-2-propoxide) and water.

To grow films of Cu2O, bis-(dimethylamino-2-propoxide)Cu(ii), or Cu(dmap), is used as an atomic layer deposition precursor using only water vapor as a co-reactant. Between 110 and 175 °C, a growth rate of 0.12 ± 0.02 Å per cycle was measured using an in situ quartz crystal microbalance (QCM). X-ray photoelectron spectroscopy (XPS) confirms the growth of metal-oxide films featuring Cu(i).

Correction: Atomic layer deposition of Cu(i) oxide films using Cu(ii) bis(dimethylamino-2-propoxide) and water.

Correction for 'Atomic layer deposition of Cu(i) oxide films using Cu(ii) bis(dimethylamino-2-propoxide) and water' by J. R. Avila, et al., Dalton Trans., 2017, DOI: .

Functionalised cyclodextrin-based metal-organic frameworks.

CD-MOF, an extended framework incorporating the C8 symmetric cyclic oligosaccharide, γ-cyclodextrin (γ-CD), is based on the coordination of alkali metal cations to alternating α-1,4-linked d-glucopyranosyl units on the primary and secondary faces of the γ-CD tori. Here, we report the synthesis and characterisation of an amino-functionalised CD-MOF that is isostructural with pristine CD-MOF and adsorbs CO2 permanently.

Second-generation hexavalent molybdenum oxo-amidinate precursors for atomic layer deposition.

The synthesis of molybdenum oxo-amidinate complexes MoO2(R2AMD)2 [AMD = N,N'-di-R-acetamidinate; R = Cy (2; cyclohexyl) and iPr (3)], and their characterization by 1H, 13C NMR, X-ray diffraction, and thermogravimetric analysis is reported. Quartz-crystal microbalance and X-ray photoelectron spectroscopic studies confirm that 3 is an improved ALD precursor versus the R = t-butyl derivative for MoO3 film growth. Complex 3 is accessible in higher yields (80%+), is easier to handle without mass loss, and in conjunction with O3 as the second ALD reagent, yields nitride-free MoO3 films.

Histological periapical repair after obturation of infected root canals in dogs.

Histological periapical healing of infected roots obturated in one-step or with prior calcium hydroxide (Ca(OH)2) disinfection was compared. Seventy-two roots of vital dog teeth were instrumented to ISO size 45. Sixty roots were infected with dental plaque and closed. Six weeks later, apical periodontitis was radiographically confirmed in the infected roots. The teeth were divided into the following groups: group 1, one-step (n = 24)-roots were irrigated with 10 ml of saline, obturated, and permanently restored; group 2, Ca(OH)2 (n = 24)-roots were treated as in group 1, except that after saline irrigation, Ca(OH)2 dressing was placed in the canal for 1 wk before obturation; group 3, positive control (n = 12)--the roots were irrigated with saline, but the canals were not obturated; and an additional group, group 4, served as a negative control (n = 12)--these teeth that were not infected with plaque were aseptically obturated. The dogs were sacrificed after 6 months. The roots and surrounding apical tissues were prepared and histologically examined by two independent evaluators blinded to the treatment groups. A two-way ANOVA test demonstrated that the four treatment groups were significantly different from one another. The positive control showed the most inflammation, the negative control the least, and the Ca(OH)2 group had significantly less inflammation than the one-step group (p < 0.05). It is concluded that Ca(OH)2 disinfection before obturation of infected root canals results in significantly less periapical inflammation than obturation alone.

The treatment of depression in elderly patients.

Primary care physicians provide a large proportion of psychiatric care today, especially for elderly persons with limited resources and concomitant medical diseases. To determine the frequency and type of psychiatric care provided by internists, the experience of a large academic group practice was studied. Depression was the most frequent psychiatric diagnosis among persons over 59 years of age and the fifth most common of all diagnoses made by physicians. Consultations with psychiatrists were infrequent and were used primarily for confirmation of the diagnosis. Physicians generally treated the depression with supportive counseling and often employed pharmacologic therapy with tricyclic antidepressants. Elderly patients were less likely than younger patients to receive tricyclic antidepressants, and they received lower doses. The observed response to antidepressant drugs was positive but required at least 50 mg to be taken daily. Side effects were frequent, especially at doses greater than 100 mg/d, but generally not severe.

Quality assurance, benchmarking, assessment and mutual international recognition of qualifications.

The aim of this report is to provide guidance to assist in the international convergence of quality assurance, benchmarking and assessment systems to improve dental education. Proposals are developed for mutual recognition of qualifications, to aid international movement and exchange of staff and students including and supporting developing countries. Quality assurance is the responsibility of all staff involved in dental education and involves three levels: internal, institutional and external. Benchmarking information provides a subject framework. Benchmarks are useful for a variety of purposes including design and validation of programmes, examination and review; they can also strengthen the accreditation process undertaken by professional and statutory bodies. Benchmark information can be used by institutions as part of their programme approval process, to set degree standards. The standards should be developed by the dental academic community through formal groups of experts. Assessment outcomes of student learning are a measure of the quality of the learning programme. The goal of an effective assessment strategy should be that it provides the starting point for students to adopt a positive approach to effective and competent practice, reflective and lifelong learning. All assessment methods should be evidence based or based upon research. Mutual recognition of professional qualifications means that qualifications gained in one country (the home country) are recognized in another country (the host country). It empowers movement of skilled workers, which can help resolve skills shortages within participating countries. These proposals are not intended to be either exhaustive or prescriptive; they are purely for guidance and derived from the identification of what is perceived to be 'best practice'.

Myocardial infarction: current management strategies.

Coronary artery disease is a common malady in industrialized societies. The end stage of this progressive disorder frequently results in myocardial infarction (MI), now known to be due to acute thrombosis of a narrowed coronary artery. In the past, supportive care was all that could be offered to patients suffering MI. But the new therapeutic modalities of thrombolysis and transluminal coronary angioplasty now offer a means of limiting the damage caused by coronary stenosis and thrombosis in many cases. This article reviews conventional, recently introduced, and possible future treatment strategies to manage coronary obstruction. Current concepts of handling the patient suffering a suspected acute coronary thrombosis in the office setting are presented as well.

Advances in cardiovascular pharmacological therapy.

Progress in the pharmacological management of cardiovascular disease has been accompanied by the appearance of drugs with never before seen capabilities to alter human physiological processes. The widespread use of these potent agents poses a challenge to the oral and maxillofacial surgeon attempting to safely manage patients in the ambulatory setting. This article reviews the field of contemporary cardiovascular pharmacotherapy from the aspect of how it affects the practice of oral and maxillofacial surgery.

Superselective angiography with digital subtraction and embolization of a maxillary hemangioma in a patient with Eisenmenger's syndrome.

Central maxillofacial hemangiomas can represent diagnostic and therapeutic problems. The concurrent existence of Eisenmenger's complex in the presented case added an anesthetic challenge. The development of superselective arterial catheterization and digital subtraction angiography has been instrumental in improving the ability of clinicians to diagnose and effectively manage vascular lesions, especially in the maxillofacial region. Embolization remains an excellent adjunctive therapy for vascular processes.

Changing methods of preventing infective endocarditis following dental procedures: 1943 to 1993.

The report by Northrop and Crowley in the inaugural issue of the Journal of Oral Surgery heralded the appearance of studies designed to confirm both the relationship between dental procedure-induced bacteremia and infective endocarditis and the best methods to interrupt this chain of causation. Their discovery that antibiotics can modulate bacteremias produced by dental procedures eventually led to the universal adoption of the prophylactic regimens to prevent cases of infective endocarditis following dental procedures. Advances since their work have involved a greater understanding of the role of adherence in the mechanism of action of prophylactic antibiotics, an appreciation of the ability to limit antibiotic administration to only the immediate preoperative period, the need to keep prophylactic regimens as uncomplicated as is safe, and greater knowledge about the interaction between dental procedures and bacteremias. Whether the widespread use of prophylactic antibiotics during dental procedures significantly decreases the incidence of endocarditis remains open to future investigation.

Intensity and duration of amnesia from intravenous midazolam given for sedation.

A clinical study was performed investigating the ability of intravenous midazolam to cause amnesia for visual, auditory and painful stimuli presented during surgical removal of third molars. Various stimuli were presented prior to and after administration of a sufficient quantity of midazolam to produce profound sedation. Recall was then tested immediately after, one day, and one week following the surgery. The study found that midazolam produces at least 20 minutes of profound amnesia for all stimuli in 93 +/- 6% of individuals. However, little correlation was found between the dose of midazolam and the duration of amnesia. Anesthesia literally means the loss of sensation. In the clinical dental situation, the principle sensation lost, when using either regional or general anesthesia, is pain perception. Although prevention of pain sensation is the primary reason patients request local anesthesia prior to invasive dental care, for many patients, control of pain only partially prepares them to receive dental care. These patients request the adjunctive use of sedation or general anesthesia, not for further pain control, but rather requiring periodontal or oral/maxillofacial surgery in which such factors as the sight and taste of blood, the noise of bone-cutting equipment, or the pressure placed on the jaws is not eliminated by local anesthetics. Although effective anxiolytic oral, inhalational, or parenteral agents have been available for several decades, patients still usually retain their memory of events occurring during their dental care, particularly anxiety-provoking events. This memory of the uncomfortable portions of dental care stimulates additional anxiety so that patients may procrastinate when dental care is necessary.(ABSTRACT TRUNCATED AT 250 WORDS)

Use of porous hydroxylapatite blocks for augmentation of atrophic mandibles.

A clinical study of the use of porous blocks of hydroxylapatite (Interpore 200) for augmentation of atrophic residual mandibular ridges was performed. Fifteen patients each had three preoperatively customized blocks placed. They were then examined clinically and radiographically for at least 2 years. Six patients had skin-graft vestibuloplasties performed over the blocks 3 months after implantation; dentures were made for 11 of the patients. No clinical or radiographic evidence of migration or resorption of the blocks was found; however, all 15 patients suffered complications. Eleven developed ulcerations over the blocks with persistent exposure, six had suture line dehiscence leading to exposure, two infections occurred, and two patients developed chronic pain in the area of block insertion. The skin graft took only partially in all patients undergoing subsequent vestibuloplasties. To date, 37 of the original 45 blocks have required complete removal. Histologic examination of removed blocks has revealed partial filling of the pores with lamellar bone. The use of blocks of porous hydroxylapatite to reconstruct atrophic residual mandibular ridges was found to have an unacceptably high rate of failure and the ability to sustain an overlying split-thickness skin graft was unpredictable.

Aspiration pneumonitis: etiology, therapy, and prevention.

Aspiration pneumonitis is a serious potential complication of many procedures that oral and maxillofacial surgeons perform. It is therefore necessary for all practitioners to be familiar with current concepts concerning the pathophysiology and treatment of this disorder. More importantly, techniques that decrease the likelihood of aspiration should be practiced whenever possible. This paper presents the etiology, therapy (in both office and hospital settings), and means of preventing pulmonary aspiration. Special emphasis will be given to the current controversies surrounding the use of corticosteroids and antibiotics.

Using resonance Raman spectroscopy to examine vibrational barriers to electron transfer and electronic delocalization.

A time-dependent approach to the interpretation of resonance Raman scattering intensities has been used to obtain quantitative vibrational mode displacement information from scattering intensities associated with charge-transfer excitation. The displacements and associated frequencies are the key parameters needed to understand Franck-Condon effects in electron-transfer kinetics, and to delineate in a mode-specific way the composition of vibrational reorganization energies. Application of the approach to a number of types of electron-transfer reactions is described, including symmetrical and unsymmetrical intervalence electron transfers in inorganic and organic redox systems, metal-to-ligand charge-transfer reactions, and interfacial electron-transfer reactions. Also described is how the approach can be used to elucidate mechanisms for valence delocalization in strongly interacting redox systems.

How far do electrons move? A semiempirical investigation of thermal electron-transfer distances in cationic bis(hydrazine) and bis(hydrazyl) mixed-valence compounds.

A computational approach for estimating thermal electron-transfer reaction distances in symmetrical mixed-valence compounds is described and applied to a series of bis(hydrazine) and bis(hydrazyl) radical cations and derivatives, some of which have been investigated experimentally by Nelsen and co-workers. Ground-state semiempirical charge distributions are obtained by using optimized reactant geometries. Advantage is then taken of the approximate C(2) symmetry, or the approximate mirror symmetry, of each of the targeted compounds, and the inherent degeneracy of the corresponding electron-transfer reactions, such that the change in dipole moment (Delta-mu) upon charge transfer can be estimated from an appropriately distance-weighted sum of charge differences between approximately symmetry-equivalent atoms found on the donor and acceptor sides of the molecule. Delta-mu can then be related directly to the effective one-electron-transfer distance. We find that calculated adiabatic electron-transfer distances can differ appreciably from the geometric donor-site/acceptor-site separation distances. Furthermore, for a fixed geometric separation distance, the effective electron-transfer distance can vary considerably, depending on chemical substituent composition and/or isomeric configuration. Further advantage is taken of the approximate donor-site/acceptor-site symmetry, in the context of a Newton-Cave type analysis, to establish the relative importance of electronic delocalization effects versus self-polarization and inductive effects in diminishing or enhancing effective one-electron-transfer distances.

The empty sella syndrome.

Oral and maxillofacial surgeons, in the course of patient evaluation, may incidentally discover abnormalities of the sella turcica. A large percentage of patients with sella deformities will be found to have the empty sella syndrome. The clinical and radiographic manifestations of this disorder, and the significance of this diagnosis, are discussed.