A soft palate desensitization procedure for patients requiring palatal lift prostheses

Successful results for the patient with a hyperactive gag reflex depend to a large extent on the manner of initial presentation. The patient should understand that the fitting process may be difficult and lengthy. In addition, the prosthesis may not provide immediate speech improvement due to initial reduction of the posterior portion of the lift, it may have to be built in stages, and it will feel foreign in the mouth for a period of weeks or even months. The patient should also be informed as to the care and maintenance of the palatal lift prosthesis. Fore-warning should be given that tooth clasps may loosen and need to be tightened and that extra care with dental hygiene will be necessary. The negative aspects of the palatal lift prosthesis should be presented prior to the patient's decision to begin prosthetic treatment.     

The effect of change of surface microstructure of carbon oral implants on gingival structures

Failure of oral implants is usually due to the breakdown of the soft tissue barrier or “seal” around the implant, followed by the invasion of microorganisms and subsequent infection. This study investigates the effect of different implant surfaces on gingival structures.     

Scanning electrochemical microscopy: theory and experiment for the positive feedback mode with unequal diffusion coefficients of the redox mediator couple1

Theory for the chronoamperometric positive feedback mode of the scanning electrochemical microscope (SECM) is extended to include the situation where the oxidised and reduced forms of the redox mediator couple have arbitrary diffusion coefficients. Under typical positive feedback conditions, the solution initially contains a redox-active species, R, along with excess supporting electrolyte. The potential of the tip ultramicroelectrode (UME), positioned close to an interface of interest, is adjusted to a value where R is electrolysed to produce species O at a diffusion-controlled rate. O diffuses away from the tip towards the interface, where the reverse redox reaction occurs leading to the production, and diffusional feedback of R for electrolysis at the tip electrode. When positive feedback measurements are carried out under diffusion-controlled chronoamperometric conditions, the form of the normalised current–time behaviour, at a particular tip to interface distance, is found to be sensitive to the ratio of the diffusion coefficients of the O/R couple. As a steady-state is established, the normalised current becomes independent of the diffusion coefficient ratio and depends only on the tip to interface distance. Experimental measurements on the chronoamperometric oxidation of ferrocene (Fc) in acetonitrile solution at a Pt tip UME positioned close to a Pt substrate electrode, provide support for the theoretical predictions and demonstrate that the diffusion coefficient ratio can readily be determined from SECM chronoamperometry. Although Fc and Fc⁺ are often assumed to have the same diffusion coefficients, steady-state and chronoamperometric measurements at a conventional UME yield a value of 2.0×10^?5 cm² s^?1 for the diffusion coefficient of Fc, while SECM chronoamperometry indicates that the diffusion coefficient of Fc⁺ is 1.6×10^?5 cm² s^?1.     

A simple model for the measurement of charge transfer resistances of reactions with slow kinetics1

The response of an electrode, initially at equilibrium, to an applied potential step, is modelled with an equivalent circuit. The model is valid for reactions that are slow in comparison with the time constant of the decay of charging currents. In the measurement, an external resistor is added in series with the working electrode to match approximately the charge transfer resistance, R_CT, of the electron transfer. Extraction of R_CT is then particularly simple. In addition to R_CT, the uncompensated resistance, R_u, and the double layer capacitance, C_dl, can be determined. An advantage of the model is that even if the potentiostat rise time is far from ideal, R_CT can be obtained reliably if R_u is known. Criteria for applicability of the equivalent circuit model are derived.     

Linear and non-linear analysis using the Oldham–Zoski steady-state equation for determining heterogeneous electrode kinetics at microdisk electrodes and digital simulation of the microdisk geometry with the fast quasi-explicit finite difference method1

A procedure which utilizes a linearized version of the Oldham–Zoski current-potential equation has been developed for the evaluation of electrode kinetic parameters from near-steady state voltammograms obtained at microdisk electrodes. The inherent advantage of the method is its mathematical simplicity relative to the other procedures already available in the literature. The procedure is applied to synthetic data obtained under near-steady state conditions from the fast quasi-explicit finite difference simulation of quasi-reversible electron transfer at a microdisk electrode. A procedure using non-linear optimization based on the Marquardt algorithm is also applied to the simulated data. Near-steady state voltammograms showing the effect of a potential dependent charge transfer coefficient are presented and analyzed. The robustness of the analysis is tested with voltammograms containing a random noise component and the near-steady state terms inherently present in experimental data. Application of the Oldham–Zoski equation to the simulated voltammograms enables the fidelity of both methods to be established over a wide range of heterogeneous kinetic conditions.     

Restoring masticatory function in a patient with severe microstomia using rapid prototyped mesh and a custom-made hinge and swing-lock prosthesis

This clinical report describes the use of rapid prototyped mesh in a complete swing-lock prosthesis to restore masticatory function in an edentulous patient with severe microstomia and perioral scar tissue after an industrial hot tar accident.     

Subluxation of the atlanto-axial joint

A case of post operative atlanto-axial dislocation is presented which was diagnosed on CT scan although the clinical signs and symptoms should have suggested the diagnosis. It is recommended that all patients who present with torticollis in the early post operative period should be considered to have C1-C2 dislocation and an orthopaedic opinion should be sought.     

Cleft lip and palate in nigerian children and adults: A comparative study

A survey of cleft lip and palate in 160 Nigerians is presented. In clefts of the lip alone, there was no sex predilection whereas cleft lip and palate cases showed a slight male preponderance. 119 (74·4%) cases presented below the age of 12 years and 41 (25·6%) cases were first seen above 12 years of age. Only a few cleft lip and palate cases survived to adulthood possibly because of malnutrition combined with the lethal effects of associated congenital abnormalities. This study confirms the view that late primary repair of clefts is less likely to produce impaired growth of the maxilla due to contraction of scar tissue commonly seen in early surgery. The importance of early primary repair is emphasised.     

A two-dimensional Born–Oppenheimer treatment of intramolecular electron transfer reactions

The Born–Oppenheimer (BO) formulation of polar solvation is developed and implemented at the semiemperical (PM3) configuration interaction (CI) level, yielding estimates of electron transfer (ET) coupling elements (V₀) for intramolecular ET in several families of radical ion systems. In contrast to the traditional treatment based on a single solvent coordinate and a fixed gas-phase coupling element, the present treatment yields a self-consistent characterization of kinetic parameters in a 2-dimensional solvent framework which includes an exchange coordinate. The dependence of V₀ on inertial solvent contributions and on donor/acceptor separation (r_DA) is discussed.     

Application of the mean spherical approximation and ion association to describe the activity coefficients of aqueous 1:1 electrolytes1

The unrestricted version of the mean spherical approximation has been applied to describe the concentration dependence of the mean ionic activity coefficients for 12 aqueous electrolyte solutions for which extensive permittivity data are also available. By using the actual solvent permittivity rather than that of the pure solvent, it is shown that this primitive model fits the experimental data in almost all cases to the maximum concentrations for which the permittivity can be described by the use of three adjustable parameters, namely, an effective ionic diameter, σ₊ or σ_?, the effective ion pair diameter σ_ip, and the association constant K_as for ion pair formation. The values of K_as obtained are discussed with respect to results from experiments reported in the literature.     

不同类型感染根管内4种厌氧菌定植状况分析

目的　应用16S rDNA-PCR技术检测不同类型感染根管内4种厌氧菌的定植状况。方法　于南京大学医学院附属口腔医院收集临床上拔除的新鲜离体牙30颗,分为3组：牙髓炎组、根尖周炎组、根管治疗失败组,每组10颗。将各组牙齿的根管分为根管冠中段（离根尖6 mm）和根管尖段（离根尖3 mm）,提取每个根管段的细菌基因组DNA,用PCR扩增细菌16S rDNA基因片段的方法检测细菌种类,计算检出率并进行统计学分析。结果　在牙髓炎组,根管冠中段能检测到牙髓卟啉单胞菌（P.endodontalis, P.e）、具核梭杆菌（F.nucleatum,F.n）、粪肠球菌（E.faecalis,E.f）和中间普氏菌（P.intermedia,P.i）,其中P.e的检出率最高（P < 0.05）,根管尖段只检测到P.e的存在。在根尖周炎组,4种厌氧菌（P.e、F.n、E.f、P.i）在根管冠中段和尖段的检出率差异无统计学意义（P > 0.05）。在根管治疗失败组,E.f在根管尖段的检出率（60%）比在根管冠中段的检出率（10%）高,差异有统计学意义（P < 0.05）。结论　牙髓炎的根管细菌主要定植在冠中段,P.e检出率最高;根尖周炎的根管冠中段和根管尖段4种细菌检出率无明显差别,都是以P.i为主;根管治疗失败的根管细菌以E.f为主,主要集中于根管尖段。     

Normal handling of phosphate in the salivary glands of X-linked hypophosphataemic mice

In X-linked hypophosphataemia (Hyp gene) there is reduced renal tubule re-absorption of phosphate and an osteomalacic bone disorder. To determine whether altered phosphate transport also occurs in the salivary gland, saliva was analysed from normal and Hyp mice at 10 weeks of age. The effect of plasma inorganic phosphate on the composition of saliva was controlled by placing both genotypes on either a control diet or a low-P diet for three days. Inorganic phosphate, total phosphate, calcium, sodium, potassium, chloride, amylase, sialic acid, protein, osmotic pressure, percentage water, percentage inorganic solids and sample volume were measured. The Hyp mice fed the control diet showed a significant decrease in salivary-inorganic phosphate, total phosphate, osmotic pressure and sialic acid. These four variables were similarly lower in the normal mice fed the low-phosphate diet. The changes seem to stem from the low plasma inorganic phosphate and not from expression of the Hyp gene in the salivary gland. The total evidence from various organ systems suggests that the altered phosphate transport in X-linked hypophosphataemia may be restricted to the kidney and is not a generalized phosphate-transport deficiency.     

Should dentures be worn continuously?

Material has been presented to show the potential problem in continuous denture wearing. Commercial booklets for patient education have been reviewed and found to be in need of revision. Dental schools are not in agreement in the subject of continuous denture wear. The need for unanimity is evident, and if this is to be achieved, patient education publications must be revised. A maximum effort is needed to educate edentulous patients about oral tissue health, and especially the length of time that dentures should be worn.     

A removal torque and histomorphometric study of commercially pure niobium and titanium implants in rabbit bone

Screw-shaped commercially pure (c.p.) niobium and c.p. titanium implants were inserted in rabbit bone. After a healing period of 3 months, a significantly higher removal torque was demonstrated to unscrew the niobium implants (average 32.9 Ncm) compared to the c.p. titanium implants (average 25.3 Ncm). In the histomorphometric part of the study, there were no significant differences in bone-to-metal contact between the 2 implant materials. An average of 41.1% bony contact was demonstrated for the niobium screws compared to an average of 37.2% for the c.p. titanium ones. Our removal torque findings could be related to the differences that we observed between the 2 implant surfaces as indicated by SEM. Since niobium implants showed a more irregular surface topography and niobium is a softer metal than c.p. titanium, this seems the most probable reason for the differences observed in removal torque between the 2 metals. Hypothetically, a more "positive biocompatibility" of the c.p. niobium in comparison to the c.p. titanium remains as another possible reason for the observed differences. However, against such a difference in biocompatibility between c.p. niobium and c.p. titanium, there is the very similar amount of bony contact registered in the histomorphometric analysis.     

Pyoderma gangrenosum with involvement of the tongue

A case of pyoderma gangrenosum with an oral lesion is presented and the differential diagnosis is discussed.