Changes of Root Length and Root-to-Crown Ratio after Apical Surgery: An Analysis by Using Cone-beam Computed Tomography.

INTRODUCTION: Apical surgery is an important treatment option for teeth with post-treatment periodontitis. Although apical surgery involves root-end resection, no morphometric data are yet available about root-end resection and its impact on the root-to-crown ratio (RCR). The present study assessed the length of apicectomy and calculated the loss of root length and changes of RCR after apical surgery. METHODS: In a prospective clinical study, cone-beam computed tomography scans were taken preoperatively and postoperatively. From these images, the crown and root lengths of 61 roots (54 teeth in 47 patients) were measured before and after apical surgery. Data were collected relative to the cementoenamel junction (CEJ) as well as to the crestal bone level (CBL). One observer took all measurements twice (to calculate the intraobserver variability), and the means were used for further analysis. The following parameters were assessed for all treated teeth as well as for specific tooth groups: length of root-end resection and percentage change of root length, preoperative and postoperative RCRs, and percentage change of RCR after apical surgery. RESULTS: The mean length of root-end resection was 3.58 ± 1.43 mm (relative to the CBL). This amounted to a loss of 33.2% of clinical and 26% of anatomic root length. There was an overall significant difference between the tooth groups (P < .05). There was also a statistically significant difference comparing mandibular and maxillary teeth (P < .05), but not for incisors/canines versus premolars/molars (P = .125). The mean preoperative and postoperative RCRs (relative to CEJ) were 1.83 and 1.35, respectively (P < .001). With regard to the CBL reference, the mean preoperative and postoperative RCRs were 1.08 and 0.71 (CBL), respectively (P < .001). The calculated changes of RCR after apical surgery were 24.8% relative to CEJ and 33.3% relative to CBL (P < .001). Across the different tooth groups, the mean RCR was not significantly different (P = .244 for CEJ and 0.114 for CBL). CONCLUSIONS: This CBCT-based study demonstrated that the RCR is significantly changed after root-end resection in apical surgery irrespective of the clinical (CBL) or anatomic (CEJ) reference levels. The lowest, and thus clinically most critical, postoperative RCR was observed in maxillary incisors. Future clinical studies need to show the impact of resection length and RCR changes on the outcome of apical surgery.

Cardan Gear Mechanism versus Slider-Crank Mechanism in Pumps and Engines

In machine design we always want to save space, save energy and produce as much power as possible. We can often reduce accelerations, inertial loads and energy consumption by changing construction. In this study the old cardan gear mechanism (hypocycloid mechanism) has been compared with the conventional slider-crank mechanism in air pumps and four-stroke engines. Comprehensive Newtonian dynamics has been derived for the both mechanisms. First the slidercrank and the cardan gear machines have been studied as lossless systems. Then the friction losses have been added to the calculations. The calculation results show that the cardan gear machines can be more efficient than the slider-crank machines. The smooth running, low mass inertia, high pressures and small frictional power losses make the cardan gear machines clearly better than the slider-crank machines. The dynamic tooth loads of the original cardan gear construction do not rise very high when the tooth clearances are kept tight. On the other hand the half-size crank length causes high bearing forces in the cardan gear machines. The friction losses of the cardan gear machines are generally quite small. The mechanical efficiencies are much higher in the cardan gear machines than in the slider-crank machines in normal use. Crankshaft torques and power needs are smaller in the cardan gear air pumps than in the equal slider-crank air pumps. The mean crankshaft torque and the mean output power are higher in the cardan gear four-stroke engines than in the slider-crank four-stroke engines in normal use. The cardan gear mechanism is at its best, when we want to build a pump or an engine with a long connecting rod (≈ 5⋅crank length) and a thin piston (≈ 1.5⋅crank length) rotating at high angular velocity and intermittently high angular acceleration. The cardan gear machines can be designed also as slide constructions without gears. Suitable applications of the cardan gear machines are three-cylinder half-radial engines for motorcycles, sixcylinder radial engines for airplanes and six-cylinder double half-radial engines for sport cars. The applied equations of Newtonian dynamics, comparative calculations, calculation results (tables, curves and surface plots) and recommendations presented in this study hold novelty value and are unpublished before. They have been made and written by the author first time in this study.

Pain-evoked alterations on gingival blood flow and gingival crevicular fluid (GCF) neuropeptide SP and collagenase-2 (MMP-8) levels

Previous studies have demonstrated that clinical pulpal pain can induce the expression of pro-inflammatory neuropeptides in the adjacent gingival crevice fluid (GCF). Vasoactive agents such as substance P (SP) are known to contribute to the inflammatory type of pain and are associated with increased blood flow. More recent animal studies have shown that application of capsaicin on alveolar mucosa provokes pain and neurogenic vasodilatation in the adjacent gingiva. Pain-associated inflammatory reactions may initiate expression of several pro- and anti-inflammatory mediators. Collagenase-2 (MMP-8) has been considered to be the major destructive protease, especially in the periodontitis-affected gingival crevice fluid (GCF). MMP-8 originates mostly from neutrophil leukocytes, the first line of defence cells that exist abundantly in GCF, especially in inflammation. With this background, we wished to clarify the spatial extensions and differences between tooth-pain stimulation and capsaicin-induced neurogenic vasodilatation in human gingiva. Experiments were carried out to study whether tooth stimulation and capsaicin stimulation of alveolar mucosa would induce changes in GCF MMP-8 levels and whether tooth stimulation would release neuropeptide SP in GCF. The experiments were carried out on healthy human volunteers. During the experiments, moderate and high intensity painful tooth stimulation was performed by a constant current tooth stimulator. Moderate tooth stimulation activates A-delta fibres, while high stimulation also activates C-fibres. Painful stimulation of the gingiva was achieved by topical application of capsaicin-moistened filter paper on the mucosal surface. Capsaicin is known to activate selectively nociceptive C-fibres of stimulated tissue. Pain-evoked vasoactive changes in gingivomucosal tissues were mapped by laser Doppler imaging (LDI), which is a sophisticated and non-invasive method for studying e.g. spatial and temporal characteristics of pain- and inflammation-evoked blood flow changes in gingivomucosal tissues. Pain-evoked release of MMP-8 in GCF samples was studied by immunofluorometric assay (IFMA) and Western immunoblotting. The SP levels in GCF were analysed by Enzyme immunoassay (EIA). During the experiments, subjective stimulus-evoked pain responses were determined by a visual analogue pain scale. Unilateral stimulation of alveolar mucosa and attached gingiva by capsaicin evoked a distinct neurogenic vasodilatation in the ipsilateral gingiva, which attenuated rapidly at the midline. Capsaicin stimulation of alveolar mucosa provoked clear inflammatory reactions. In contrast to capsaicin stimuli, tooth stimulation produced symmetrical vasodilatations bilaterally in the gingiva. The ipsilateral responses were significantly smaller during tooth stimulation than during capsaicin stimuli. The current finding – that tooth stimulation evokes bilateral vasodilatation while capsaicin stimulation of the gingiva mainly produces unilateral vasodilatation – emphasises the usefulness of LDI in clarifying spatial features of neurogenic vasoactive changes in the intra-oral tissues. Capsaicin stimulation of the alveolar mucosa induced significant elevations in MMP-8 levels and activation in GCF of the adjacent teeth. During the experiments, no marked changes occurred in MMP-8 levels in the GCF of distantly located teeth. Painful stimulation of the upper incisor provoked elevations in GCF MMP-8 and SP levels of the stimulated tooth. The GCF MMP-8 and SP levels of the non-stimulated teeth were not changed. These results suggest that capsaicin-induced inflammatory reactions in gingivomucosal tissues do not cross the midline in the anterior maxilla. The enhanced reaction found during stimulation of alveolar mucosa indicates that alveolar mucosa is more sensitive to chemical irritants than the attached gingiva. Analysis of these data suggests that capsaicin-evoked neurogenic inflammation in the gingiva can trigger the expression and activation of MMP-8 in GCF of the adjacent teeth. In this study, it is concluded that experimental tooth pain at C-fibre intensity can induce local elevations in MMP-8 and SP levels in GCF. Depending on the role of MMP-8 in inflammation, in addition to surrogated tissue destruction, the elevated MMP-8 in GCF may also reflect accelerated local defensive and anti-inflammatory reactions.

Analysis of the antibiotic prophylaxis prescribed by Spanish oral surgeons

Aim: To identify prophylactic antibiotic prescription practices among Spanish dentists with preferential dedication to Oral Surgery in different types of tooth extraction surgeries. Method: Members of the Spanish Oral Surgery Society were surveyed on antibiotic prophylaxis use in 4 different tooth extraction modalities scaled according to their surgical invasiveness. Results: Sixty-nine of the 105 distributed questionnaires were returned completed. Thirteen percent of the surveyed surgeons would prescribe antibiotics to prevent postoperative wound infection when confronted with conventional tooth extraction lasting less than 5 minutes. In the case of surgery lasting more than 5 minutes, the percentage of participants that would prescribe antibiotics increased to 39%. When a mucoperiosteal flap was elevated or an ostectomy was performed, 87% and 100%, respectively, would prescribe antibiotic prophylaxis. Amoxicillin and its combination with clavulanic acid were the most commonly prescribed antibiotics. All participants would prescribe the antibiotic orally, starting after surgery and with a duration that ranged from 2-8 days. Conclusions: The results obtained suggest that antibiotic prophylaxis for preventing local odontogenic infection is not being correctly implemented in Spain. This can generate new bacterial resistances, facilitate adverse drug reactions and favor opportunistic infections. Better designed studies are needed in order to clarify the role of antibiotics in the prevention of postsurgical wound infection

Bupivacaine 0.5 % versus articaine 4 % for the removal of lower third molars. A crossover randomized controlled trial

Objective: To compare the anesthetic action of 0.5% bupivacaine in relation to 4% articaine, both with 1:200,000 epinephrine, in the surgical removal of lower third molars. As a secondary objective hemodynamic changes using both anesthetics were analyzed. Study Design: Triple-blind crossover randomized clinical trial. Eighteen patients underwent bilateral removal of impacted lower third molars using 0.5% bupivacaine or 4% articaine in two different appointments. Preoperative, intraoperative and postoperative variables were recorded. Differences were assessed with McNemar tests and repeated measures ANOVA tests. Results: Both solutions exhibited similar latency times and intraoperative efficacy. Statistical significant lower pain levels were observed with bupivacaine between the fifth (p=0.011) and the ninth (p=0.007) postoperative hours. Bupivacaine provided significantly longer lasting soft tissue anesthesia (p<0.05). Systolic blood pressure and heart rate values were significantly higher with articaine. Conclusions: Bupivacaine could be a valid alternative to articaine especially due to its early postoperative pain prevention ability.

Complications of guided surgery and immediate loading in oral implantology: a report of 12 cases

Objectives: The growing interest in minimally invasive surgery, together with the possibility of fitting prostheses with immediate function, have led to the development of software capable of planning and manufacturing a surgical guide and prosthesis that can be placed upon conclusion of the implant surgery step. The present study evaluates the surgical and prosthetic complications of implant treatment with the guided surgery technique, together with patient comfort during and after treatment. Patients and methods: A retrospective observational study was made of 19 patients with partially or totally edentulous upper and/or lower maxillae, involving the placement of a total of 122 implants. All cases were planned and operated upon with the guided surgery technique. Results: A total of 122 implants were placed in 14 males and 5 females. The intraoperative surgical complications comprised a lack of primary stability, while the postoperative complications consisted of infections and a lack of implant osteointegration. Ten implants failed. The prosthetic complications in turn comprised loosening of the provisional prosthesis screws, prosthesis tooth fracture, and a lack of passive fit of the immediate prosthesis. The degree of patient satisfaction was evaluated using a verbal scale. Conclusions: Implant restoration with the guided surgery technique and immediate functional loading is a predictable procedure, provided patient selection and the surgical technique are adequate, affording lesser postoperative morbidity and increased patient satisfaction thanks to the immediate restoration of esthetics and function

Thermal increment due to ErCr: YSGG and CO2 laser irradiation of different implant surfaces. A pilot study

Objective: An evaluation and comparison is made of the thermal increment at different implant surfaces during irradiation with CO2 and ErCr:YSGG lasers. Study design: Five threaded and impacted implants with four types of surfaces were inserted in an adult pig rib: two implants with a hydroxyapatite surface (HA)(impacted and threaded, respectively), a machined titanium surface implant (TI mach), a titanium plasma spray surface implant (TPS), and a sandblasted, acid-etched surface implant (SBAE). A 0.5-mm diameter bone defect was made in the implant apical zone, and a type-K thermocouple (Termopar)® was placed in contact with the implant. The implants were irradiated in the coronal zone of each implant with a CO2 (4 W continuous mode) and an ErCr:YSGG laser (1.5 W, pulsed mode) first without and then with refrigeration. The temperature variations at the implant apical surface were recorded. Results: An apical temperature increase was recorded in all cases during CO2 and ErCr:YSGG laser irradiation without refrigeration. However, when the ErCr:YSGG was used with a water spray, a decrease in temperature was observed in all implants. The acid-etched and sandblasted surfaces were those most affected by the thermal changes. Conclusions: The ErCr:YSGG laser with a water spray applied to the sealing cap or coronal zone of the implants does not generate thermal increments in the apical surface capable of adversely affecting osseointegration and the integrity of the peri-implant bone tissue

Introgressive hybridization of threatened European tree frogs (Hyla arborea) by introduced H. intermedia in Western Switzerland

Hybridization by introduced taxa is a major threat to native species. Characterizing human introductions is thus one of the missions of conservation geneticists. Here we survey a declining population of the regionally endangered European tree frog (Hyla arborea) in the Grangettes natural reserve (Rhone valley, Western Switzerland), where previous evidence indicated human introduction of the Italian taxon H. intermedia. We combined fast-evolving mitochondrial and nuclear markers and an extended sampling to conduct population genetic analyses of the Grangettes and putative source areas. We show that the Grangettes population is a hybrid swarm, with all individuals featuring recent nuclear admixture and mitochondrial DNA of introduced H. intermedia, most likely of proximate south Alpine origin. In contrast, H. arborea and H. intermedia hardly introgress in their natural parapatric ranges, consistent with an advanced reproductive isolation. Thus, potential hybrid incompatibilities may account for the strong decline of this population, despite important conservation efforts. Although their hybrid nature makes them a priori unworthy of any protection, we propose specific measures to recover local H. arborea gene pool and preserve tree frogs in the Grangettes, the last population remaining from this heavily impacted part of the Alps.

Lineaarisen hammashihnaservokäytön tilasäätö

Tuotantotehokkuus näyttelee yhä suurempaa roolia teollisuudessa, minkä vuoksi myös pakkauslinjas­toille joudutaan asettamaan suuria vaatimuksia. Usein leik­kaus- ja kappaleensiirtosovelluksissa käyte­tään lineaarisia ruuvikäyttöjä, jotka voitaisiin tietyin edellytyksin korvata halvemmilla ja osittain suori­tuskykyisimmillä hammashihnavetoisilla johteilla. Yleensä paikkasäädetty työsolu muodostuu kahden tai kolmen eri koordinaatisto­akselin suuntaan asen­netuista johteista. Tällaisen työsolun paikoitustarkkuuteen vaikuttavat muun muassa käytetty säätöra­kenne, moottorisäätöketjun viiveet, sekä laitteiston eri epälineaarisuudet, kuten kitka. Tässä työssä esitetään lineaarisen hammashihnaservokäytön dynaamista käytöstä kuvaava matemaatti­nen malli ja laaditaan mallin pohjalta laitteen simulointimalli. Mallin toimivuus varmistetaan käytän­nön identifiointitesteillä. Lisäksi työssä tut­kitaan, kuinka hyvään suorituskykyyn lineaarinen hammas­hihnaservokäyttö kyke­nee, jos teollisuudessa paikoitussäätörakenteena tyypillisesti käytetty kaskadira­kenne tai PID-rakenne korvataan kehittyneemmällä mallipohjaisella tilasäädinra­kenteella. Säädön toi­mintaa arvioidaan simulointien ja koelaitteistolla suoritetta­vien mittaus­ten perusteella.

Eficacia analgésica del diclofenaco sódico vs. ibuprofeno después de la extracción quirúrgica de un tercer molar inferior incluido

Objetivo: En este estudio evaluamos la eficacia analgésica del diclofenaco sódico en comparación con el ibuprofeno, después de la extracción quirúrgica de un tercer molar inferior incluido. Diseño de estudio: Los pacientes que participaron en el estudio fueron distribuidos de forma aleatoria en dos grupos. Uno fue el grupo ibuprofeno y el otro el grupo diclofenaco. La intervención practicada fue la extracción quirúrgica de un tercer molar inferior cuya dificultad fue determinada en función del grado de inclusión en todos los pacientes. Las variables registradas fueron la intensidad del dolor y la necesidad de medicación de rescate durante un periodo de una semana. Los registros se realizaron una vez al día a la misma hora y registrados en un cuaderno por parte del paciente. Resultados: Un total de 81 pacientes (87.1%) fueron incluidos en el estudio. Los valores fueron similares en las primeras 48 horas postoperatorias, pero a partir del tercer día existió una tendencia del grupo diclofenaco a mostrar valores de dolor superiores, aunque sin llegar a existir diferencias estadísticamente significativas (p>0.05). Esta tendencia a presentar mayor dolor durante el periodo postoperatorio en el grupo diclofenaco también se vio reflejada en el requerimiento del analgésico de rescate y en el número de comprimidos empleados. Conclusiones: No se evidenciaron diferencias estadísticamente significativas en cuanto a la eficacia analgésica del diclofenaco sódico respecto al ibuprofeno, aunque sí pudo observarse una mayor tendencia hacia la necesidad de más medicación suplementaria durante los 2 primeros días del postoperatorio en el grupo diclofenaco pero sin adquirir significación estadística (p>0.05).

Are open mandibular fractures still an emergency?

INTRODUCTION: Early surgical management is often advocated for fractures of the tooth-bearing portion of the mandible. A 6-hour delay has been mentioned for the fixation of these fractures. Our aim was to bring this paradigm into question. METHODS: All patients referred to our department from September 2012 to May 2014 for fractures of the tooth-bearing portion of the mandible were retrospectively included. For each patient, age, gender, aetiology of the fracture, and characteristics of the fractures were recorded. Tobacco and/or alcohol addictions, diabetes and mandibular dental condition were taken into account. We also noticed the preoperative delay and the occurrence of complications such as: haematoma, infection, wound dehiscence, osteosynthesis failure and pseudarthrosis. RESULTS: Among the 47 patients referred, 36 were treated with a delay of more than 6hours (76.6%). In 88.8% of the cases, the reason for this delay was unavoidable. The mean delay time from trauma to surgery was 52hours (range: 7-312). Forty-nine percent of the patients had comorbidities. Complications occurred in 6 patients leading to an overall complication rate of 16.67%. A statistically significant higher complication rate was observed among smokers (P=0.006). No statistical relationship was found between the delay and the occurrence of complications (P=0.994). This study suggests that fractures of the tooth-bearing portion of the mandible should no longer be considered as an emergency that must be treated within a 6-hour delay.

Modelling the consequences of a reduction in alcohol consumption among patients with alcohol dependence based on real-life observational data.

BACKGROUND: Most available pharmacotherapies for alcohol-dependent patients target abstinence; however, reduced alcohol consumption may be a more realistic goal. Using randomized clinical trial (RCT) data, a previous microsimulation model evaluated the clinical relevance of reduced consumption in terms of avoided alcohol-attributable events. Using real-life observational data, the current analysis aimed to adapt the model and confirm previous findings about the clinical relevance of reduced alcohol consumption. METHODS: Based on the prospective observational CONTROL study, evaluating daily alcohol consumption among alcohol-dependent patients, the model predicted the probability of drinking any alcohol during a given day. Predicted daily alcohol consumption was simulated in a hypothetical sample of 200,000 patients observed over a year. Individual total alcohol consumption (TAC) and number of heavy drinking days (HDD) were derived. Using published risk equations, probabilities of alcohol-attributable adverse health events (e.g., hospitalizations or death) corresponding to simulated consumptions were computed, and aggregated for categories of patients defined by HDDs and TAC (expressed per 100,000 patient-years). Sensitivity analyses tested model robustness. RESULTS: Shifting from >220 HDDs per year to 120-140 HDDs and shifting from 36,000-39,000 g TAC per year (120-130 g/day) to 15,000-18,000 g TAC per year (50-60 g/day) impacted substantially on the incidence of events (14,588 and 6148 events avoided per 100,000 patient-years, respectively). Results were robust to sensitivity analyses. CONCLUSIONS: This study corroborates the previous microsimulation modeling approach and, using real-life data, confirms RCT-based findings that reduced alcohol consumption is a relevant objective for consideration in alcohol dependence management to improve public health.

Fatigue resistance of denture teeth

AIMS: There is no standard test to determine the fatigue resistance of denture teeth. With the increasing number of patients with implant-retained dentures the mechanical strength of the denture teeth requires more attention and valid laboratory test set-ups. The purpose of the present study was to determine the fatigue resistance of various denture teeth using a dynamic load testing machine. METHODS: Four denture teeth were used: Bonartic II (Candulor), Physiodens (Vita), SR Phonares II (Ivoclar Vivadent) and Trubyte (Dentsply). For dynamic load testing, first upper molars with a similar shape and cusp inclination were selected. The molar teeth were embedded in cylindrical steel molds with denture base material (ProBase, Ivoclar Vivadent). Dynamic fatigue loading was carried out on the mesio-buccal cusp at a 45° angle using dynamic testing machines and 2,000,000 cycles at 2Hz in water (37°C). Three specimens per group and load were submitted to decreasing load levels (at least 4) until all the three specimens no longer showed any failures. All the specimens were evaluated under a stereo microscope (20× magnification). The number of cycles reached before observing a failure, and its dependence on the load and on the material, has been modeled using a parametric survival regression model with a lognormal distribution. This allowed to estimate the fatigue resistance for a given material as the maximal load for which one would observe less than 1% failure after 2,000,000 cycles. RESULTS: The failure pattern was similar for all denture teeth, showing a large chipping of the loaded mesio-buccal cusp. In our regression model, there were statistically significant differences among the different materials, with SR Phonares II and Bonartic II showing a higher resistance than Physiodens and Trubyte, the fatigue resistance being estimated at around 110N for the former two, and at about 60N for the latter two materials. CONCLUSION: The fatigue resistance may be a useful parameter to assess and to compare the clinical risk of chipping and fracture of denture tooth materials.

Validation of a computer-assisted system on classifying lower third molars

Objectives: The present study evaluates the reliability of the Radio Memory® software (Radio Memory; Belo Horizonte,Brasil.) on classifying lower third molars, analyzing intra- and interexaminer agreement of the results. Study Design: An observational, descriptive study of 280 lower third molars was made. The corresponding orthopantomographs were analyzed by two examiners using the Radio Memory® software. The exam was repeated 30 days after the first observation by each examiner. Both intra- and interexaminer agreement were determined using the SPSS v 12.0 software package for Windows (SPSS; Chicago, USA). Results: Intra- and interexaminer agreement was shown for both the Pell & Gregory and the Winter classifications, p<0.01, with 99% significant correlation between variables in all the cases. Conclusions: The use of Radio Memory® software for the classification of lower third molars is shown to be a valid alternative to the conventional method (direct evaluation on the orthopantomograph), for both clinical and investigational applications.

Freshwater biodiversity and conservation in mediterranean climate streams of Chile.

In Chile, mediterranean climate conditions only occur in the Central Zone (ChMZ). Despite its small area, this mediterranean climate region (med-region) has been recognised as a hotspot for biodiversity. However, in contrast to the rivers of other med-regions, the rivers in the ChMZ have been studied infrequently, and knowledge of their freshwater biodiversity is scarce and fragmented. We gathered information on the freshwater biodiversity of ChMZ, and present a review of the current knowledge of the principal floral and faunal groups. Existing knowledge indicates that the ChMZ has high levels of endemism, with many primitive species being of Gondwanan origin. Although detailed information is available on most floral groups, most faunal groups remain poorly known. In addition, numerous rivers in the ChMZ remain completely unexplored. Taxonomic specialists are scarce, and the information available on freshwater biodiversity has resulted from studies with objectives that did not directly address biodiversity issues. Research funding in this med-region has a strong applied character and is not focused on the knowledge of natural systems and their biodiversity. Species conservation policies are urgently required in this highly diverse med-region, which is also the most severely impacted and most populated region of the country.