Aortic Root Abscess Complicated by Fistulization and Intracerebral Hemorrhagic Infarction

We report an unusual case of a 12-year-old male with aortic root abscess complicated by fistulization and intracerebral hemorrhagic infarction. Transesophageal echocardiography provided exact information about the location and dimension. Color-flow mapping demonstrated fistulous communication between the abscess and both the aorta and the left ventricle, causing severe diastolic regurgitation through the paravalvular leak. Pulmonary autograft aortic root replacement was performed with good result.     

Aortic root diameter and nasal intermittent positive airway pressure treatment in Marfan's syndrome

We report on a patient with Marfan's syndrome, with coexistent obstructive sleep hypopnea (OSH) and restrictive lung disease, complicated by respiratory insufficiency, who was successfully treated with nasal intermittent positive airway pressure (NIPPV) and oxygen. NIPPV therapy turned out to be effective on arterial gas exchange and well tolerated. Moreover, progressive dilatation of the aortic root was attenuated during NIPPV, but could, however, not be reversed. We hypothetized that (at least partially) a decrease of nocturnal intrathoracic pressures could explain this.     

Reperfusion response changes induced by repeated,sustained contractions in normal human masseter muscle

The purpose was to evaluate the intramuscular reperfusion response characteristics associated with repeated isometric contractions in normal human masseter. Intramuscular blood volume was quantified with a near-infrared spectroscopic device that measured the total haemoglobin (Hb) concentration in the muscle. Electromyographic (EMG) activity from the masseter and total bite forces were also recorded. Sixteen healthy volunteers, eight females and eight males, without masticatory muscle pain participated. They were asked first to clench their teeth for as long as possible at 50% of their maximum voluntary contraction (MVC). This was followed by a 60s rest and then immediately by a standard clenching task (50% MVC for 30s) and a 60s recovery period, immediately after which they were asked to repeat exactly the same procedure, with a final 5 min recovery period after the second 30s contraction. Bite force, EMG and Hb concentration were measured continuously and the duration of the two endurance tasks and the amplitudes of all recorded signals were compared (first trial versus second trial). Specifically, the difference between the lowest Hb (trough) seen during the standardised 30s contractions and the highest (peak) seen just after them was assessed. The trough-to-peak difference in Hb concentration of the second standard contraction task was significantly smaller than that of the first standard task (P<0.05, paired t-test). These data show that with sustained effort the post-contraction vasodilatory reperfusion responses of the human masseter are diminished, suggesting a progressive desensitisation of the vasodilatory system.     

Cytotoxicity of resin-, zinc oxide-eugenol-, and calcium hydroxide-based root canal sealers on human periodontal ligament cells and permanent V79 cells

AIM: The purpose of this study was to determine the cytotoxicity of three different types of root canal sealer on human periodontal ligament (PDL) cells and a permanent hamster cell line (V79 cells). METHODOLOGY: Set specimens from two resin based sealers (AH26 and AHPlus), three zinc oxide-eugenol-based sealers (Canals, Endomethasone and N2) and one calcium hydroxide-based sealer (Sealapex) were eluted with culture medium for 1, 2, 3 and 7 days. Cytotoxicity was judged using tetrazolium bromide reduction assay on human primary PDL cells and V79 cells derived from a Chinese hamster. RESULTS: The results showed that elutes from resin-based, zinc oxide-eugenol-based, and calcium hydroxide-based sealers were cytotoxic to primary human PDL cultures and V79 cells. Calcium hydroxide-based sealer was the least toxic sealer amongst the chemicals tested in both cultures. The cytotoxic response decreased in an order of N2 > Endomethasone > AH26 > AHplus > Canals > Sealapex. CONCLUSIONS: The sensitivity of toxicity depended on the materials tested and the cell culture system used. Thus, the use of both permanent and primary cells is recommended for screening of the cytotoxic effects of root canal sealers. In addition, the results confirmed that root canal sealers constantly dissolve when exposed to an aqueous environment for extended periods, possibly causing moderate or severe cytotoxic reactions. Use of calcium hydroxide-based material as a root canal sealer initially may result in a more favourable response to periradicular tissues.     

A comparison of the shaping characteristics of two nickel-titanium endodontic hand instruments

AIM: The purpose of this study was to compare the shaping characteristics of Ni-Ti K-files and Ni-Ti S-files manipulated by hand. METHODOLOGY: A total of 60 extracted human roots were embedded in resin blocks. The embedded roots were divided into three groups: (i) roots with straight; (ii) apically curved; and (iii) continuously curved canals. Each of the three groups was randomly divided into two subgroups; one subgroup in each group was prepared with Ni-Ti K-files and the other with Ni-Ti S-files. The files were used with a step-back technique and enlarged so that the master apical file was size 30, and the canals were stepped back to size 40. The performance of the files was assessed by the superimposition of projected radiographs taken in bucco-lingual and mesio-distal directions before and after the preparation. The results were analysed statistically using analysis of covariance and Duncan's multiple range test. RESULTS: Although canal preparation using Ni-Ti K-files was quicker, there were no statistically significant differences between file types. The Ni-Ti S-file removed significantly more material at the most coronal level (P < 0.05). There were minor differences between instruments at the apical level. Only in the proximal view of apically curved canals prepared with Ni-Ti S-files was significantly more dentine removed from the outer aspect of the curvature (P < 0.05). At the middle level (wide danger zone) the Ni-Ti S-files removed more dentine from the inner aspect of the curvature in those roots with apically curved canals. CONCLUSIONS: Under the conditions of this study, preparation with Ni-Ti K-files produced more appropriate shapes in roots with apically curved canals than Ni-Ti S-files.     

Localized alveolar bone necrosis following the use of an arsenical paste: a case report

AIM: To describe some toxic effects of arsenic trioxide in the mouth, to condemn its continued use, and present a case in which a tooth was preserved despite significant bony destruction. SUMMARY: A case is presented in which severe alveolar bone necrosis resulted from leak-age of an arsenical devitalization paste into the periodontium.The tooth was root canal treated before root amputation, and restored with a cuspal coverage restoration. The tooth was observed to be symptomless and functional at the one-year follow-up. KEY LEARNING POINTS: * Arsenic and its compounds have no place in contemporary endodontics. * Dentists should protect their patients by avoiding the use of arsenic-containing materials and refusing to use products whose constituents are not known. * Localized bone necrosis may not require tooth extraction. Depending on the severity of the case, the tooth may be preserved by a combination of endodontic, periodontal,prosthodontic and maintenance therapies.     

When you hear hoofs,think horses,not zebras: an evidence-based model of health care accountability

Health care organizations are increasingly asked to show accountability about their performance. This paper proposes that accountability can best be achieved through evaluative methods that are based on evidence regarding the relationship between processes of care and expected outcomes. Root cause analysis (RCA) is used as an illustration of how a generic method of inquiring can be transformed into an ongoing monitoring, evaluation, user education and accountability strategy. The role of performance indicators, as well as patient and community expectations, is discussed.     

Clinical evaluation of the cleansing properties of the noninstrumental technique for cleaning root canals

AIM: The purpose of the present study was to evaluate noninstrumentation technology (NIT) for root-canal cleansing in vivo. METHODOLOGY: A total of 22 teeth that were to be extracted in 18 patients were treated with NIT for 30 min with 3.0% NaOCl. After extraction, the remaining organic debris in the root canals was evaluated histologically and categorized as the percentage of the corresponding canal length in the apical middle and coronal regions of the roots. Percentage of residual debris was categorized as follows: D1, 0%; D2, 1-50% and D3, 51-100%. RESULTS: In the coronal region, 55% of the roots were totally clean (Dl), whereas 12% and 33% were scored as D2 and D3, respectively. The middle section was evaluated as D1 in 27%, D2 in 18% and D3 in 55%. In the apical region, only 21% of the roots were totally cleaned: the remaining 79% were scored as D3. CONCLUSION: The results indicate that the noninstrumental technique for cleaning root canals needs further modifications for achieving acceptable results under clinical conditions.     

Powder emission rates of four air polishing devices

OBJECTIVES: Although highly effective in plaque and stain removal, the use of air polishing devices (APDs) on denuded root surfaces may lead to clinically relevant loss of tooth substance. As the amount of powder emitted by an APD may have a significant impact on the safety and efficacy of the instruments, the purpose of the study was to quantify the amount of powder emitted by APDs depending on their powder filling status and powder setting. METHODS: Four different APDs were filled to maximum level and the cumulative amount of powder emitted, depending on instrument settings and filling status, was quantified during 15 subsequent 120-s periods of use. Differences in powder emission were analyzed using anova repeated measures. RESULTS: Exact powder dosage was possible in one APD only (Dentsply Prophyjet) where emission rates also remained constant over the first five periods assessed. In the three other APDs assessed (EMS Air-Flow, Satellec Air-Max, KaVo Prophyflex II powder emission depended on the amount of powder present in the powder chamber and declined with ongoing use. Changes in powder setting had a significant impact on powder emission in all APDs assessed, apart from the KaVo Prophyflex II unit. CONCLUSIONS: Powder emission of APDs may vary greatly depending on the amount of powder present in the powder bowl. Therefore, instrument powder setting may not be a reliable parameter for safety and efficacy adjustments. This should be considered in clinical applications as well as in future research.     

Dissolution of USP prednisone calibrator tablets: effects of stirring conditions and particle size distribution

We investigate the effect of stirring conditions on the dissolution of United States Pharmacopoeial Convention (USP) prednisone calibrator tablets. The experiments are performed in an automated USP-II dissolution test apparatus. For this study we use a special paddle-propeller, which can be changed from an ordinary paddle to either a pulling or pushing propeller by changing the angle of the paddle blades. According to the dissolution curves obtained we find that the fastest dissolution, and hence best stirring at a certain stirring frequency, is obtained when the blades of the paddle-propeller is about +30°. This setting corresponds to a pushing, downward flow in the centre of the vessel. We show that the shape of the dissolution curves is similar to that expected from a mix of two different fractions of particles, provided that the stirring is sufficiently intense: one fraction, approximately 60 wt.%, with small particles, and one fraction with large particles. The weight of a large particle is about 100–250 times that of a small. We derive a mathematical expression, based on the cube root law, for the dissolution curves. The expression is fitted to the experimental dissolution curves to investigate the variation of key parameters with stirring and temperature.